Human Reproduction Update, Vol.18, No.1 pp. 60–72, 2012
Advanced Access publication on November 14, 2011 doi:10.1093/humupd/dmr044
Spindle assembly checkpoint and its
regulators in meiosis
Shao-Chen Sun and Nam-Hyung Kim*
Department of Animal Sciences, Chungbuk National University, Cheongju 361-763, Korea
*Correspondence address. Tel: +82-43-261-2546; Fax: +82-43-272-8853; E-mail: [email protected]
Submitted on July 29, 2011; resubmitted on September 8, 2011; accepted on October 6, 2011
table of contents
...........................................................................................................................
†
†
†
†
†
†
Introduction
Methods
Spindle assembly checkpoint regulators
Mad1
Mad2
Bub1
Bub3
BubR1
Mps1
Microtubule-kinetochore attachment regulators
Ndc80 complex
Chromosomal passenger complex (CPC)
MCAK
KNL-1
Mis12 complex
Spindle stability regulators
MAPK
Other spindle stability regulators
Conclusion and future directions
background: Meiosis is a unique form of cell division in which cells divide twice but DNA is duplicated only once. Errors in chromosome segregation during meiosis will result in aneuploidy, followed by loss of the conceptus during pregnancy or birth defects. During mitosis,
cells utilize a mechanism called the spindle assembly checkpoint (SAC) to ensure faithful chromosome segregation. A similar mechanism has
been uncovered for meiosis in the last decade, especially in the past several years.
methods: For this review, we included data and relevant information obtained through a PubMed database search for all articles published in English from 1991 through 2011 which included the term ‘meiosis’, ‘spindle assembly checkpoint’, or ‘SAC’.
results: There are 91 studies included. Evidence for the existence of SAC functions in meiosis is provided by studies on the SAC proteins
mitotic-arrest deficient-1 (Mad1), Mad2, budding uninhibited by benzimidazole-1 (Bub1), Bub3, BubR1 and Mps1; microtubule-kinetochore
attachment regulators Ndc80 complex, chromosomal passenger complex, mitotic centromere-associated kinesin (MCAK), kinetochore null
1 (KNL1) and Mis12 complex and spindle stability regulators.
conclusions: SAC and its regulators exist and function in meiosis, and their malfunctions may cause germ cell aneuploidy. However,
species and sexual differences exist. Moreover, interaction of SAC components with other regulators is still poorly understood, which needs
further study.
Key words: spindle assembly checkpoint / meiosis / chromosome segregation / aneuploidy
& The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.
For Permissions, please email: [email protected]
61
Spindle assemble checkpoint in meiosis
Introduction
During the cell cycle, genomic stability requires accurate chromosome
segregation (Nasmyth et al., 2000). In mitosis, each cell cycle produces
two daughter cells with the same number of chromosomes, which is
also the same number as in the mother cell. Errors in this process can
cause aneuploidy and lead to tumorigenesis (Cahill et al., 1998; Matsuura et al., 2000). To ensure faithful chromosome segregation, cells
develop a mechanism called the spindle assembly checkpoint (SAC)
(Musacchio and Salmon, 2007). This mechanism can detect unattached microtubules or loss of tension, and cause a metaphase
‘arrest’ until all of the microtubules from the spindle poles capture
the kinetochores and the chromosomes are congressed to the equatorial plate (Wassmann and Benezra, 2001; Millband et al., 2002).
Then, the SAC is silenced and the anaphase-promoting complex/
cyclosome (APC/C) is activated, resulting in the onset of chromosome segregation and entry of the cell into anaphase (Musacchio
and Salmon, 2007).
Meiosis is a unique form of cell division. Different from mitosis,
meiosis undergoes two cell divisions with only a single round of
DNA duplication. In meiosis I, homologous chromosomes are segregated and sister chromatids are driven to one of the spindle poles
under the regulation of Rec8 and Shugoshin 1 (Sgo1) (Macy et al.,
2009). In meiosis II, the sister chromatids themselves are segregated,
which is similar to mitosis. Between the two meiotic divisions, an intervening S phase is lost. Errors of chromosome segregation in meiosis
can also result in aneuploidy, leading to subsequent infertility or
birth defects (Handel and Schimenti, 2010; Yanowitz, 2010).
It is critical to ensure faithful segregation of homologous chromosomes and sister chromatids during meiosis. Accumulating evidence
from the past decade, especially from the past 3 years, has uncovered
the SAC mechanism in meiosis (Fig. 1). In this review, recent findings
on how the SAC functions in germ cell meiosis are discussed, focusing
on three aspects: spindle checkpoint proteins, microtubulekinetochore attachment regulators and spindle stability regulators
(Fig. 2).
Methods
For this review, we included data and relevant information obtained
through a PubMed database search for all articles published in English
from 1991 through 2011 which included the term ‘meiosis’, ‘spindle assembly checkpoint’, or ‘SAC’.
SAC proteins
SAC proteins were first identified in Saccharomyces cerevisiae. These
include the Mad (mitotic-arrest deficient) proteins Mad1 and Mad2,
the Bub (budding uninhibited by benzimidazole) proteins Bub1,
Bub3 and BubR1 and Mps1 (Hoyt et al., 1991; Li and Murray,
1991). In eukaryotes, these are all conserved (Musacchio and Hardwick, 2002; Taylor et al., 2004). The target of the SAC proteins is
Cdc20, a co-factor of APC/C (Hwang et al., 1998; Kim et al.,
1998). In mitosis, the regulatory mechanisms of the SAC proteins
and the relationship between them have all been well-studied (Musacchio and Salmon, 2007). In contrast, for meiosis, the functions of the
SAC proteins have only been released in recent years (Table I).
Mad1
Mad1 has been reported to be associated with meiosis in yeast, Caenorhabditis elegans, Xenopus and mouse oocytes (Kitagawa and Rose,
1999; Tunquist et al., 2003; Cheslock et al., 2005; Zhang et al., 2005;
Stein et al., 2007). Interestingly, instead of localizing at the kinetochore
as in mitosis, during meiosis in mouse oocytes, Mad1 first localized at
the kinetochores at pre-metaphase I (MI) stage, and then translocated
to the poles of the spindle at MI stage. Mad1 may be responsible for
sensing tension or microtubule attachment and may act as a negative
sensor, for only after spindle disruption does Mad1 relocate to the
kinetochore (Zhang et al., 2005). This transport mechanism may be
dependent on the regulation of dynein (Zhang et al., 2007). When
tension is lost, Mad1 is driven by dynein to the kinetochore to activate
the SAC.
During meiosis, Mad1 may inhibit the activity of APC/C and cause a
metaphase delay to provide time for both homologous chromosome
and sister chromatid alignment. Functional study from antibody injection experiments and mutant research in different species mentioned
earlier all reveal that loss of Mad1 causes misaligned chromosomes,
accelerates entry into anaphase I (Tunquist et al., 2003; Cheslock
et al., 2005; Zhang et al., 2005; Stein et al., 2007).
Mad2
Figure 1 Diagram of SAC in meiosis I and meiosis II. In both
meiosis I and meiosis II, unattached kinetochores will active SAC to
cause a pro-metaphase arrest; when all the chromosomes align and
all the kinetochores attach to the microtubules, SAC is silenced, chromosomes are segregated and germ cells enter anaphase.
As in mitosis, Mad2 was reported to localize at kinetochores during
meiosis in mouse (Kallio et al., 2000), rat (Zhang et al., 2004), pig
(Ma et al., 2005), maize (Yu et al., 1999) and grasshopper (Nicklas
et al., 2001). This is true for both female meiosis and male meiosis
in mammals. However, the patterns of Mad2 dynamics are different
among species. Specifically, in meiosis I of maize and grasshopper,
Mad2 localizes at unattached kinetochores. After proper attachment,
62
Sun and Kim
Figure 2 Known localization of SAC regulators in meiosis. The SAC regulators are detected at kinetochores, spindle poles and spindle microtubules.
it is lost from the kinetochores, indicating that Mad2 may sense microtubule attachment (Yu et al., 1999), and that the successful attachment
of microtubule to kinetochore can determine Mad2 binding (Nicklas
et al., 2001). However, in mouse spermatogenesis, Mad2 is shown
to remain at most kinetochores throughout meiosis I and is lost
only during metaphase of meiosis II. The persistence of Mad2 at kinetochores in oocytes was seen during meiosis II (Kallio et al., 2000).
This suggests that in mammalian species, the role of the kinetochore
with respect to the SAC may be different between the two meiotic
divisions, and between male and female meiosis. However, the
reason for this difference is still unknown.
Functions of Mad2 are released by antibody injection, RNAi, morpholino (MO) injection and overexpression approaches. It has been
shown that Mad2 is a key SAC protein involved in regulation of
meiotic chromosome segregation and APC/C activity. In the
absence of Mad2, a shortened duration of meiosis I, meiotic spindle
abnormality (Wang et al., 2007), chromosome misalignment (Niault
et al., 2007) and meiosis I non-disjunction were observed in mouse
oocytes (Shonn et al., 2003). Disruption of Mad2 activity by antibody
injection causes precocious anaphase onset and misaligned chromosomes during meiosis I in rat oocytes (Zhang et al., 2004). In addition,
the incidence of aneuploidy also increases in Mad2-depleted oocytes
(Homer et al., 2005a, c). Complementary results are observed after
Mad2 mRNA injection, and overexpression of Mad2 leads to cell-cycle
arrest in MI (Wassmann et al., 2003), chromosome misalignment
(Niault et al., 2007) and inhibition of homolog disjunction in mammalian oocytes (Homer et al., 2005c). Mad2 mRNA injection also can
counteract the depletion of Mad2 by MO injection (Homer et al.,
2005c). Moreover, the expression of Mad2 has been found to gradually decrease during pig oocyte aging, supporting the idea of a role for
Mad2 in the regulation of aneuploidy (Ma et al., 2005). Due to
meiosis-specific APC/C regulation, Mad2 is essential for both
meiotic divisions (Yamamoto et al., 2008a). Metaphase II (MII)
arrest by maintaining CSF (cytostatic factor) activity is disrupted in
frog oocytes in response to the disruption of Mad2 expression (Tunquist et al., 2003). However, in mouse oocytes, in contrast to frog
eggs, it appears that Mad2, together with other SAC proteins, is not
required for establishing or maintaining CSF arrest (Tsurumi et al.,
2004).
Securin and cyclin B may be the targets of Mad2, as securin and
cyclin B are destabilized in Mad2-depleted mouse oocytes (Homer
et al., 2005b, c). And BRCA1 and Nedd1 may be upstream regulators
of Mad2, since MAD2 fails to rebind to the kinetochores when
exposed to nocodazole at the MI stage after BRCA1 RNAi in
oocytes (Xiong et al., 2008). Knockdown of Nedd1 also causes persistent MAD2 expression at the kinetochores, indicating activation
of the SAC (Ma et al., 2010).
Bub1
As in mitosis, Bub1 also localized to the kinetochores of unaligned
meiotic chromosomes in Drosophila, Xenopus and mouse oocytes
(Basu et al., 1999; Schwab et al., 2001; Brunet et al., 2003). Bub1 is
required for localization of Bub3 and Rec8 during meiosis I, suggesting
that Bub1 kinase activity is essential for establishing proper kinetochore function (Basu et al., 1998; Yamaguchi et al., 2003). In mammalian female meiosis, Bub1 shows conserved roles as a SAC protein and
may regulate cyclin B to affect APC/C activity. As evidence in support
of this, depletion of Bub1 by RNAi induced cyclin B degradation, precocious anaphase onset and polar body extrusion in mouse oocytes.
In addition, misaligned chromosomes were also observed (Yin et al.,
2006; McGuinness et al., 2009). Bub1 mutation experiments lead to
female-specific germ cell aneuploidy in mice (Leland et al., 2009),
and chromosome missegregation and fragmentation are observed in
63
Spindle assemble checkpoint in meiosis
Table I SAC proteins in meiosis.
Gene
Species
Approaches
Phenotypes
References
.............................................................................................................................................................................................
Mad1 protein injection; antibody
injection
Metaphase arrest; block the CSF arrest in meiosis Tunquist et al. (2003) and Zhang et al. (2005,
2007)
II; misaligned chromosomes; the transport
dependence on dynein
C. elegans
Mutant
Aberrant alleles suppress APC mutants; aberrant Kitagawa and Rose (1999)
anaphase onset
Yeast
Mutant
Aberrant metaphase delay
Cheslock et al. (2005)
Nocodazole treatment; taxol
treatment; mutant injection;
RNAi; overexpression; MO
injection
Nocodazole causes Mad2 localization at all
kinetochores, taxol induces the loss of Mad2
from kinetochores; meiosis I accelerates but the
oocytes are still arrested at MII; meiotic spindle
abnormality; chromosome missegregation;
aneuploidy; proteolysis of cyclin B and securin
commences earlier; BRCA1 and Nedd1 may be
the upstream regulators
Kallio et al. (2000), Wassmann et al. (2003) and
Tsurumi et al. (2004), Homer et al. (2005a, b,
c), Niault et al. (2007), Wang et al. (2007),
Xiong et al. (2008) and Ma et al. (2010)
Nocodazole treatment; taxol
treatment
MAD2 is observed in all treated oocytes
Zhang et al. (2004)
Mad1 Mouse
Mad2 Mouse
Rat
Pig
Ageing
MAD2 is reduced during oocyte aging
Ma et al. (2005)
Yeast
Mutant
Meiosis I non-disjunction occurs, and can be
corrected by delaying the onset of anaphase;
Regulates APC/C through Cdc20
Shonn et al. (2003) and Yamamoto et al. (2008a)
Maize
Oryzalin treatment
Localization of Mad2 is correlated with a
measure of tension
Yu et al. (1999)
Grasshopper
Weak attachment setup by micro In the absence of tension, weakly attached
manipulation
kinetochores lose Mad2 and become
dephosphorylated
Nicklas et al. (2001)
Mouse
Mos KO mouse; antibody
injection; mutant
BUB1 is not depended on the MOS-MAPK
pathway; Cyclin B degradation and precocious
anaphase onset, misaligned chromosomes;
aneuploidy
Brunet et al. (2003), Yin et al. (2006), Leland
et al. (2009) and McGuinness et al. (2009)
Xenopus
p90(Rsk) injection
p90(Rsk) phosphorylates Bub1
Schwab et al. (2001)
Drosophila
Mutant
Accelerated exit from metaphase, chromosome Basu et al. (1998, 1999) and Tunquist et al.
(2002)
missegregation and fragmentation, disrupt
localization of Bub3; block the ability of Mos to
establish CSF arrest
Yeast
Mutant
Cdc2p phosphorylates Bub1p, Bub1p maintains Bernard et al. (2001), Yamaguchi et al. (2003),
localization of Rec8p and Sgo1; sister chromatids Kitajima et al. (2004), Kiburz et al. (2005) and
move to opposite spindle poles during MI
Vaur et al. (2005)
Mouse
Overexpression; RNAi; Parp-1
KO mouse;
Inhibit meiotic metaphase– anaphase transition; Jeganathan and van Deursen (2006), Li et al.
Misaligned chromosomes, abnormal polar body; (2009) and Yang et al. (2009)
Aneuploidy; localization of Bub3 depends on
Parp-1; male fertility and accurate chromosome
segregation is not depended on Bub3
BubR1 Mouse
Overexpression; RNAi; mutant
BubR1 mutant causes infertile. BubR1 depletion
accelerates meiotic progression, overexpression
of BubR1 arrests oocyte meiosis, chromosome
misalignment, depleted Chd1; the last protein to
be assembled at the outer kinetochore; Aurora
C, p38 MAPK inhibited the localization of BubR1;
Setpin 2 may be the upstream regulator
Bub1
Bub3
Baker et al. (2004), Homer et al. (2009),
Parra et al. (2009), Fan (2010), Ou et al. (2010),
Wei et al. (2010), Yang et al. (2010) and Zhu
et al. (2010)
Drosophila
Mutant
Required for sister-chromatid cohesion
Malmanche et al. (2007)
Yeast
Mutant
Early developmental arrest, abnormal syncytial
nuclear divisions, defects in chromosome
congression, premature sister chromatids
separation, irregular chromosome distribution
and asynchronous divisions
(Perez-Mongiovi et al., 2005)
Continued
64
Sun and Kim
Table I Continued
Gene
Species
Approaches
Phenotypes
References
.............................................................................................................................................................................................
Mps1
Mouse
Mutant
Precocious metaphase I, aberrant chromosome
alignment, disruption of Aurora C localization
Hached et al. (2011)
Yeast
Mutant
Disrupt sporulation, chromosome
missegregation
Straight et al. (2000)
Zebrafish
Mutant
Chromosome missegregation, aneuploidy
Poss et al. (2004)
Drosophila
Mutant
Defects in female meiotic chromosome
segregation; accelerate meiotic progression
Gilliland et al. (2005, 2007)
Arabidopsis
thaliana
Mutant
Male and female sterility, chromosome
missegregation, aberrant spindles
Jiang et al. (2009)
Mps1 is required for metaphase arrest with
Cyclin E-Cdk2
Grimison et al. (2006)
Xenopus
Drosophila (Basu et al., 1999). Moreover, in mouse and fission yeast,
loss of Bub1 causes the movement of sister chromatids to opposite
spindle poles during meiosis I, indicating that Bub1 is required for
the unification of sister kinetochores and retention of centromeric cohesion (Bernard et al., 2001; McGuinness et al., 2009), which is critical
for the accurate segregation of homologous chromosomes. Bub1 is
required for the localization of the meiosis cohesion regulators Sgo1
and Shugoshin 2 (Sgo2) during meiosis I (Kitajima et al., 2004;
Kiburz et al., 2005). The N-terminus of Bub1 is necessary for the targeting of Sgo1 to centromeres and the protection of cohesion,
whereas the C-terminal acts together with Sgo2 to promote sisterkinetochore co-orientation at the MI stage during fission-yeast
meiosis (Vaur et al., 2005). Thus, besides the similarity to mitosis
with respect to monitoring microtubule attachment, Bub1 can also
regulate sister chromatin cohesion in meiosis I.
However, the activation mechanism of Bub1 may differ between different species. In Xenopus oocytes, the substrate of mitogen-activated
protein kinase (MAPK), p90Rsk phosphorylates and activates Bub1, indicating the existence of a MAPK-dependent pathway (Schwab et al.,
2001). Depletion of Bub1 can block the ability of Mos to establish CSF
arrest (Tunquist et al., 2002). In contrast, p90Rsk and Bub1 are not
required for establishing or maintaining CSF arrest in mouse oocytes
(Tsurumi et al., 2004; Dumont et al., 2005), and Bub1 is phosphorylated until anaphase of both meiotic M phases, indicating that the
phosphorylation of Bub1 does not depend on the MOS/MAPK
pathway (Brunet et al., 2003). Thus, species differences need to be
considered when investigating Bub1 functions in meiosis.
Bub3
In meiosis of spermatocytes, Bub3 appears at the kinetochore and this
localization is dependent on Bub1 (Basu et al., 1998). A recent study
showed that Parp-1 is also necessary for Bub3 localization in mouse
oocytes (Yang et al., 2009). The roles of Bub3 have been well-studied
in mouse oocytes and similarity between mammalian mitosis and
meiosis has been illustrated. Overexpression of Bub3 by mRNA injection causes meiotic arrest, while depletion of Bub3 from kinetochores
causes chromosome misalignment and abnormal polar body extrusion. A cold treatment experiment proved that Bub3 is required for
microtubule-kinetochore attachment. Aneuploidy is also observed in
response to the knockdown of Bub3 (Li et al., 2009). These results
confirm the conserved roles of Bub3 in female meiosis. However, in
male meiosis, Bub3 has been shown to be unnecessary for male fertility and accurate chromosome segregation during spermatogenesis,
indicating that the mechanisms ensuring accurate chromosome segregation may be different in male and female meiosis (Jeganathan and van
Deursen, 2006).
BubR1
Localization of BubR1 to the kinetochore was first shown in meiosis of
Drosophila (Perez-Mongiovi et al., 2005). Similar to mitosis, BubR1
binds to the kinetochore in mouse oocytes (Wei et al., 2010).
BubR1 may be the last protein that is loaded to the kinetochore
during male mouse meiosis (Parra et al., 2009) and it is a critical regulator of accurate chromosome segregation (Jeganathan and van
Deursen, 2006). In female meiosis, Aurora C and p38 MAPK are
shown as upstream regulators for the localization of BubR1 (Ou
et al., 2010; Yang et al., 2010). The functions of BubR1 are wellcharacterized in mouse oocytes. Depletion of BubR1 causes the
failure of prophase I arrest and a simultaneous decrease in Cdh1, indicating the involvement of BubR1 in APC/C activity (Homer et al.,
2009). BubR1 depletion by RNAi accelerates meiotic progression,
and overexpression of BubR1 causes meiotic arrest (Fan, 2010; Wei
et al., 2010). These results suggest the regulation of SAC activity by
BubR1 in oocytes. Similarly to Bub3, cold treatment also disrupts
spindle microtubules in BubR1-depleted oocytes, suggesting that
BubR1 monitors kinetochore-microtubule attachments (Wei et al.,
2010). BubR1 is also essential for maintaining sister chromatid cohesion during meiotic progression in both sexes in Drosophila
(Malmanche et al., 2007). Since Bub1 regulates Shugoshin’s involvement in this process, and BubR1 is the last SAC protein loaded to
the kinetochore, a Bub1-BubR1-Shugoshin pathway may exist in
meiosis. Septin2 may regulate BubR1 for the SAC activity, since
Septin2 disruption causes failure of the MI-anaphase I and telophase
I transition, and BubR1 is labeled on all the chromosomes (Zhu
et al., 2010), indicating the activation of SAC.
Mps1
Mps1 is another SAC protein and its functions in meiosis have been
preliminarily reported. Mps1 monitors accurate chromosome
65
Spindle assemble checkpoint in meiosis
alignment; disruption of Mps1 causes chromosome missegregation and
aneuploidy in mouse, yeast, zebrafish and Drosophila (Straight et al.,
2000; Poss et al., 2004; Gilliland et al., 2005; Hached et al., 2011).
Mps1 is also required for metaphase arrest, since Mps1 disruption
causes precocious entry into anaphase I without completing spindle
formation in mouse, Drosophila and Arabidopsis thaliana (Gilliland
et al., 2007; Jiang et al., 2009; Hached et al., 2011). Cyclin E-Cdk2
may be an upstream regulator of Mps1, since the metaphase arrest
caused by Mps1 depletion has been shown to be regulated by cyclin
E-Cdk2 (Grimison et al., 2006). Aurora C may be the downstream
regulator of Mps1, and in Mps1 mutant mouse oocytes, localization
of Aurora C is disrupted (Hached et al., 2011).
To summarize, all of the SAC proteins are shown to involve in the
regulation of meiosis, and show relatively conserved roles compared
with mitosis. In meiosis, these proteins can cause metaphase arrest
in response to the detection of a lack of microtubule attachment
and can inhibit the activity of the APC/C until all of the chromosomes
are well aligned, which can ensure accurate chromosome segregation
and consistency of daughter cells, avoid the following aneuploidy, infertility and birth defects. However, the slight difference may exist
between mitosis and meiosis, and even between sexes and species.
The difference between males and females may possibly contribute
to gender-specific genetic risk and differences between species may
also be involved in species-specific susceptibility to meiotic errors
(Vogt et al., 2008). Since Shugoshin and Rec8 are major regulators
for meiosis cohesion, the relationship between the SAC proteins, Shugoshin and Rec8 needs further investigation.
Mammalian oocytes are arrested at MII stage before fertilization, with
well aligned chromosomes in the middle plate of the meiotic spindle. At
the same time, SAC proteins are localized at the kinetochore, and SAC
is kept active. It is known that the MII arrest is maintained by the activity
of the CSF, but why SAC keeps activated when all chromosomes are
well aligned and how CSF components act to keep SAC activity thus
prevent metaphase–anaphase transition needs further study.
Microtubule-kinetochore
attachment regulators
The critical event for SAC activity is the successful attachment of
microtubules to the kinetochore. Besides the SAC proteins, multiple
regulators participate in the regulation of microtubule-kinetochore attachment. In mitosis, the Ndc80 complex, chromosomal passenger
complex (CPC), mitotic centromere-associated kinesin (MCAK), kinetochore null 1 (KNL1) and Mis12 complex are shown to be the main
regulators and involve in this process. Whereas the SAC proteins function more as sensors, these molecules function more like regulators.
For meiosis, most of these regulators have been revealed in recent
years (Table II).
Ndc80 complex
The Ndc80 complex consists of Ndc80, Nuf2, Spc24 and Spc25
(Ciferri et al., 2007). In mitosis, the Ndc80 complex localizes at the
kinetochore outer plate after the G2 phase and is shown to be the
main regulator for kinetochore-microtubule attachment. To accomplish this, the Ndc80 complex, together with several additional kinetochore proteins, KNL1/Spc105 and the Mtw1/Mis12 complex, forms
the KMN network (Tanaka and Desai, 2008). The Ndc80 complex
is capable of recruiting the SAC proteins Mad1, Mad2, Mps1 and
Mps2 to the kinetochores but it is not essential for Bub1, Bub3 and
BubR1 recruitment (Ciferri et al., 2007; Tanaka and Desai, 2008).
The role of the Ndc80 complex in meiosis has been well-studied
and recently revealed.
In contrast to the SAC proteins, evidence from Ndc80 in maize and
pig, and Spc25 in mouse oocytes shows that this complex binds to the
kinetochore during all stages of meiosis (Du and Dawe, 2007; Sun
et al., 2010a, 2011). A novel localization pattern of Ndc80 has been
also observed: in mouse oocytes, Ndc80 also localizes at microtubules
(Sun et al., 2011). More interestingly, in mouse somatic cells, Ndc80
localizes at the spindle poles and kinetochore (Diaz-Rodriguez et al.,
2008). This localization pattern indicates the additional functions of
Ndc80 in these systems. CENP-C and Mis12 have been identified as
regulators of Ndc80 in maize meiosis (Du and Dawe, 2007; Li and
Dawe, 2009). In mammalian oocyte meiosis, Ndc80 and Spc25 are
both essential for SAC activity: depletion of Ndc80 and Spc25 in
mouse oocytes causes precocious polar body extrusion (Sun et al.,
2010a, 2011; Sun, 2011; Xiong, 2011), while overexpression of
Spc25 causes meiotic arrest (Sun et al., 2010a). And the regulation
mechanism of Ndc80 complex in meiosis may be related with
SAC-regulated APC/C activity, for cyclin B1 expression is disturbed
by the perturbation of Spc25 expression. Disruption of kinetochoremicrotubule attachment may occur, since chromosome misalignment
has also been observed (Sun et al., 2010a). Moreover, in meiosis,
the Ndc80 complex is also involved in the regulation of spindle formation, for the perturbation of Ndc80 and Spc25 expression all cause
spindle disruption. It has been traditionally thought that kinetochore
proteins do not affect spindle formation; however, recent reports
on Ndc80 in mouse somatic cells (Diaz-Rodriguez et al., 2008) and
oocytes (Sun et al., 2011) all showed disruption of the spindle after
RNAi. It is still unknown whether there is a relationship between
spindle disruption and kinetochore attachment, for disruption of
each will cause the other to become aberrant.
Chromosomal passenger complex
The CPC consists of Aurora B, INCENP, survivin and borealin. During
mitosis, CPC associates with kinetochores to correct misaligned chromosomes, properly form the central spindle, regulate the SAC, and
complete cytokinesis. In this complex, Aurora B is the core component. While INCENP binds to Aurora B, survivin targets Aurora B
to kinetochores and borealin stabilizes survivin and Aurora B
(Ruchaud et al., 2007). Recently, Aurora B was also listed as a SAC
protein in mitosis (Musacchio and Salmon, 2007).
In mouse male meiosis, the CPC proteins appear to form a platform
that can recruit the other SAC proteins to the kinetochore, with borealin, INCENP and Aurora B being loaded first to the kinetochores
(Parra et al., 2009). The core component Aurora B has been
well-studied in meiosis. The involvement of Aurora B in SAC activity
may be dependent on the regulation of BubR1 and Bub1, since treatment with the Aurora B inhibitor ZM447439 causes disruption of
BubR1 and Bub1 from the kinetochore (Wang et al., 2006; Vogt
et al., 2009; Yang et al., 2010).
Aurora B activity controls the SAC during meiosis. Similar effects
have been observed with mitosis in the oocytes of various species,
66
Sun and Kim
Table II Microtubule-kinetochore attachment regulators in meiosis.
Gene
Species
Approaches
Phenotypes
References
.............................................................................................................................................................................................
Ndc80
Mouse
Antibody injection; RNAi Precocious polar body extrusion, misaligned chromosomes, Sun et al. (2011)
aberrant spindle
Maize
Mutant
Associate with DNA following replication; associated with Du and Dawe (2007) and Li and Dawe
Mis12, kinetochores separate and orient randomly in MI
(2009)
Spc25
Mouse
Overexpression; RNAi
Precocious polar body extrusion, misaligned chromosomes, Sun et al. (2010a), Sun (2011) and Xiong
aberrant spindle
(2011)
Aurora B
Mouse
Overexpression;
Inhibitor treatment
Prevent polar body formation, affect spindle formation and Swain et al. (2008), Shuda et al. (2009),
chromosome congression at meiosis I, reduce histone H3 Vogt et al. (2009), Lane et al. (2010) and
lysine 9 trimethylation, aneuploidy; absence of histone-H3 Sharif et al. (2010)
phosphorylation at serine 10 and 28; overexpression of
Aurora B leads to a failure of APC/C activation
Rat
Inhibitor treatment
Defects in the spindle morphology and chromosomes
misalignment, a forced exit from the meiotic M-phase
without cytokinesis
Wang et al. (2006)
Surf clam
Inhibitor treatment
Chromatin decondensation, loss of histone H3
phosphorylation and reformation of the nuclear envelope,
block of polar body formation
George et al. (2006)
Pig
Yeast
Aurora B is not required for chromosome condensation in Jelinkova and Kubelka (2006)
pig oocytes
Mutant
Protect cohesin and cohesion; recruited by Sgo1 and
maintain PP2A activity; Regulate kinetochore-microtubule
attachment
Monje-Casas et al. (2007) and Yu and
Koshland (2007)
Drosophila Mutant
Promote meiotic sister chromatid cohesion through
Shuogoshin
Resnick et al. (2006)
de Carvalho et al. (2008)
C. elegans Mutant; RNAi
Protect cohesion; Restricted by LAB-1
INCENP
Mouse
Activate APC/C before chromosomes have properly
Sharif et al. (2010)
congressed in meiosis I and prevent cytokinesis and hence
extrusion of the first polar body
Drosophila Mutant
Initial assembly of spindle microtubules is delayed
Survivin
Mouse
Overexpression; MO
injection; antibody
injection
Chromosome misalignment, precocious polar body
Sun et al. (2009)
extrusion; overexpression of survivin causes meiotic arrest
Rat
Antibody injection
Abnormal spindle assembly, chromosome segregation and Wang et al. (2010)
precocious polar body emission
Mouse
Antibody injection
Aberrant spindle formation, chromosome misalignment
Sun et al. (2010b)
Drosophila Mutant
Chromosome misalignment; no effect on meiotic histone
phosphorylation or spindle formation
Gao et al. (2008)
Mouse
MO injection; RNAi
Interact with Aurora B; chromosome misalignment; Delay in Sampath et al. (2004), Parra et al. (2006),
chromosome congression and meiosis I arrest
Eichenlaub-Ritter et al. (2010), Illingworth
et al. (2010) and Vogt et al. (2010)
Xenopus
Mutant
Regulated by Aurora B; assembly of mono-astral and
monopolar structures
Borealin
MCAK
RNAi
Aurora B RNAi and inhibitor treatment all cause defects of chromosome congression, spindle formation and polar body extrusion in
meiosis I. In addition, meiotic progression accelerates, indicating the
silence of SAC (George et al., 2006; Swain et al., 2008; Vogt et al.,
2009; Lane et al., 2010). Inhibition of either Aurora B or its homologue
Aurora C can cause chromosome scattering in the cytoplasm (Yang
et al., 2010). Moreover, inhibition of Aurora B overcomes SAC
arrest caused by nocodazole and so rescues polar body extrusion.
Aurora B inhibition also rescues cyclin B1 degradation (Lane et al.,
2010). Overexpression of Aurora B can rescue chromosome alignment defects (Shuda et al., 2009).
Colombie et al. (2008)
Ohi et al. (2004)
The effects of Aurora B on chromosome congression may be due
to the regulation of histone 3, since Aurora B inhibition reduces
histone H3 lysine 9 trimethylation (Vogt et al., 2009) and histone-H3
phosphorylation at serine 10 and 28 (Swain et al., 2008). However, in
pig oocytes, Aurora B activity and Ser-10 phosphorylation of histone
H3 are not required for chromosome condensation, indicating that different mechanisms of Aurora B may also exist between mouse and pig
(Jelinkova and Kubelka, 2006).
The mechanism that Aurora B employs to regulate SAC activity may
be due to the involvement of Aurora B in cohesion (Yu and Koshland,
2007), for kinetochore orientation during meiosis has been shown to
67
Spindle assemble checkpoint in meiosis
be controlled by Aurora B (Monje-Casas et al., 2007). A recent study
showed that Aurora B promotes meiotic sister chromatid cohesion
through the localization of Shugoshin in Drosophila (Resnick et al.,
2006). Long arm of the bivalent-1 (LAB-1) has also been shown to
be involved in the preservation of meiotic sister chromatid cohesion
by restricting C. elegans Aurora B (de Carvalho et al., 2008). Moreover, another evidence shows that Aurora B may regulate protein
phosphatase 2A (PP2A) (a molecule which regulates chromosome
connect with Shuogoshin) activity at the centromere (Yu and Koshland, 2007).
The roles of INCENP, survivin and borealin are also conserved. Depletion of INCENP in mouse oocytes activates the APC/C before
chromosomes have properly congressed in meiosis I and also prevents
cytokinesis and polar body emission (Sharif et al., 2010). In female
meiosis, INCENP is also crucial to the assembly of the acentrosomal
metaphase spindle (Colombie et al., 2008). The initial identification of
survivin was from spermatogenesis studies (Weikert et al., 2005), and
thereafter its function has been studied in mouse and rat oocyte
meiosis. Depletion of survivin results in chromosome misalignment,
precocious polar body extrusion and large polar bodies. Overexpression of survivin also causes chromosome misalignment and meiotic
arrest in mouse oocytes. These results suggest that survivin is required
for chromosome alignment and regulation of spindle checkpoint activity during murine oocyte meiosis (Sun et al., 2009; Wang et al., 2010).
In mitosis, borealin promotes the binding of survivin to INCENP and is
directly phosphorylated by Mps1 on residues that are crucial for
Aurora B activity and chromosome alignment (Bourhis et al., 2007;
Jelluma et al., 2008). The borealin paralogue Australian was first identified in male meiosis in Drosophila, and it was showed that Australian
was required for chromosome alignment, segregation and cytokinesis
(Gao et al., 2008). In the mouse oocyte, borealin has been proved to
regulate spindle formation (Sun et al., 2010b).
All the findings of CPC in meiosis show that this complex regulates
SAC activity to affect chromosome alignment, spindle formation and
meiotic progression. Its interaction with other molecules such as
SAC proteins can ensure the maintenance of SAC activity for accurate
kinetochore-microtubule attachment and chromosome segregation.
However, in meiosis, inhibition of each component activity causes a
different SAC activity response. The regulation mechanism of SAC
proteins by this complex and how the components interact with
each other in meiosis remain unclear.
for chromosome alignment, since depletion of MCAK causes chromosome misalignment. Disruption of MCAK activity also causes meiotic
arrest in meiosis I, indicating the regulation of SAC activity by
MCAK. Aberrant spindle and hypoploidy are also observed in
meiosis II (Eichenlaub-Ritter et al., 2010; Illingworth et al., 2010;
Vogt et al., 2010). However, another report showed that MCAK
was not necessary for preventing chromosome segregation errors in
meiosis I of mouse oocyte (Illingworth et al., 2010).
KNL-1
KNL-1 was recently found to be involved in C. elegans meiosis
(Dumont et al., 2010; Han and Srayko, 2010). KNL-1 directs the assembly of meiotic kinetochores and is required for the orientation
of chromosomes and accurate meiotic chromosome segregation.
However, chromosome separation during meiotic anaphase is
kinetochore-independent. It seems that the separation is controlled
by a meiosis-specific chromosomal domain to coordinate cohesin
removal and chromosome segregation (Dumont et al., 2010).
KNL-1 may indirectly regulate SAC through interaction with the
Ndc80 complex but this requires further investigation. In mouse
female meiosis, Spindly localizes to the kinetochore from prometaphase to metaphase, and this localization is dependent on KNL-1
(Yamamoto et al., 2008b). Spindly depletion results in arrest at the
pro-MI/MI stage and failure to enter anaphase, indicating that
KNL-1 may regulate Spindly to participate in SAC silencing as a recruiter and/or a transporter of kinetochore proteins (Zhang et al., 2010).
Mis12 complex
Mis12 participates in fission-yeast meiosis (Asakawa et al., 2005;
Hayashi et al., 2006). Mis12 dissociates during meiotic prophase, indicating that it may reassemble to establish the functional metaphase
kinetochore for meiotic chromosome segregation. Mis12 binds the
Ndc80 complex, which in turn binds directly to microtubules. Knockdown of Mis12 causes the Mis12-Ndc80 connection to break and the
kinetochores to separate randomly in meiosis I, which indicates that
Mis12 may regulate homologous chromosome segregation (Li and
Dawe, 2009). Similar to KNL-1, the Mis12 complex may also act as
a component of the KNL network to regulate SAC proteins, but
this requires further investigation.
Spindle stability regulators
MCAK
The expression of MCAK in meiosis was first identified in Xenopus
(Ohi et al., 2004). In mouse male meiosis, MCAK co-localizes with
Aurora B. Aurora B and Sgo2 seem to regulate the loading of
MCAK to the kinetochore (Parra et al., 2006, 2009). Aurora B inhibits
Xenopus MCAK activity in a phosphorylation-dependent manner (Ohi
et al., 2004; Sampath et al., 2004). In Xenopus, MCAK is shown to be
required for bipolar meiotic spindle assembly, and this may be regulated via the stabilization of chromatin-associated microtubules by
the CPC (Ohi et al., 2004; Sampath et al., 2004). In mouse female
meiosis, MCAK is shown to localize at the spindle poles and centromeres (Illingworth et al., 2010; Vogt et al., 2010), and is involved in
the regulation of SAC through the regulation of Aurora B in both
meiosis I and meiosis II (Vogt et al., 2010). MCAK is also required
Besides the SAC proteins and kinetochore-microtubule attachment
regulators, recent reports show that spindle stability regulators can
also regulate SAC activity through effects on the SAC proteins
during meiosis (Table III).
Mitogen-activated protein kinase
The Mos-MEK1-MAPK-p90(Rsk) cascade utilizes SAC components to
affect metaphase arrest (Grimison et al., 2006). p42 MAPK and p38a
MAPK are shown to localize at poles of spindle, while ERK3 is shown
to localize at spindle. Chemical inhibition of p42 MAPK inhibits oocyte
maturation, indicating that p42 MAPK is responsible for both CSF- and
checkpoint-induced metaphase arrest (Cross and Smythe, 1998).
ERK3 deletion disrupts kinetochore-microtubule attachment and
arrests the oocytes at the MI stage, while BubR1 could be detected
68
Sun and Kim
Table III Spindle stability regulators in meiosis.
Gene
Species
Approaches
Phenotypes
References
.............................................................................................................................................................................................
p42
MAPK
Xenopus
Inhibitor treatment
Inhibition of oocyte maturation
Cross and Smythe,
(1998)
p38
MAPK
Mouse
RNAi;
Overexpression
Defects of spindle pole formation; decreased BubR1; Aneuploidy
Ou et al. (2010)
ERK
Mouse
MO injection
MI arrest; impaired spindles and misaligned chromosomes; maintain BubR1 on
centromere
Li et al. (2010)
EMB-30
C. elegans Mutant
Polar bodies are not produced, pronuclei fail to form and cytokinesis does not occur Furuta et al. (2000)
Mlh1
Mouse
Chromosomes misalignment
Eaker et al. (2002)
Dgrip84
Drosophila Mutant
Ensuring spindle bipolarity and correct completion of cytokinesis
Colombie et al. (2006)
KO mouse
Figure 3 Known pathway of SAC regulators in meiosis. Dotted line shows that the pathway only exists in specific species due to the species
difference.
consistently on the kinetochores (Li et al., 2010). Depletion of p38a
MAPK decreases BubR1 and interferes with SAC, which could result
in aneuploid oocytes (Ou et al., 2010).
proteins. This needs further investigation since only limited evidence
is shown.
Other spindle stability regulators
Conclusion and future directions
EMB-30, a molecule which interacts with Mad1, also regulates SAC activity and metaphase– anaphase transition in C. elegans (Furuta et al.,
2000). In mouse male meiosis, chromosomes are observed to be misaligned in the majority of Mlh1(2/2) spermatocytes, and meiotic
progression is also delayed (Eaker et al., 2002). The Mlh1 mutant
mouse confirms the involvement of Mlh1 in SAC activity in mouse
female meiosis (Nagaoka et al., 2011). The Drosophila gamma-tubulin
small complex subunit Dgrip84 also seems to be essential for SAC activity during male meiosis and can ensure both spindle bipolarity and
the correct completion of cytokinesis (Colombie et al., 2006).
The regulation of SAC by spindle stability regulators may be related
to spindle integrity. Spindle disruption will cause the failure of
microtubule-kinetochore attachment, which further actives SAC
In mitosis, the functions and mechanisms of SAC regulators are all
clearly interpreted. Recent works have also characterized the functions of most of these molecules in meiosis. Compared with
mitosis, roles observed in meiosis are basically conserved and all of
the molecules identified regulate accurate chromosome segregation
through the inhibition of APC/C activity. However, there are some
questions which still needed to be clarify: First, how these molecules
interact with each other during meiosis is still largely unclear, since
most of them have been only individually analyzed (Fig. 3). Second,
slightly different mechanisms may exist between meiosis and mitosis.
Localization and expression pattern differences are observed
between mitosis and meiosis. Species differences also need to be considered, since different phenotypes are observed. Recent work also
69
Spindle assemble checkpoint in meiosis
shows that different mechanisms exist between mammalian male
meiosis and female meiosis. Different from male meiosis, anaphase
onset require stable bipolar attachment of a critical mass—but not
all—of chromosomes in mouse oocytes. This is probably one of the
reasons for making the oocyte inherently error prone in chromosome
segregation, and may explain why there are higher percentage of aneuploid oocytes than sperm, and contribute to the age-related increase in aneuploidy (Hawley, 2011; Nagaoka et al., 2011). The
exact gender-difference of the SAC functions and how the difference
contributes the germ cell aneuploid are still unclear.
Besides the conserved role of regulating metaphase arrest, SAC regulators seem to take more responsibilities due to the specificity of
meiosis. One unique feature of meiosis is that sister chromatids do
not separate during meiosis I; thus, a specific mechanism is needed to
protect sister cohesion. Although several studies have shown that
some SAC regulators are involved in Shugoshin-related or Rec8-related
meiosis I regulation, it is still unclear how the SAC regulators are involved
in this complicated process. The other unique feature is the specific
acentrosomal spindle formation that exists in oocyte meiosis, which indicates a more complicated mechanism. The general consensus holds that
SAC protein does not affect spindle formation. However, the disruption
of most SAC molecules causes aberrant spindle morphology in meiosis,
which indicates that, in meiosis, the SAC regulators may also have been
involved in this process. It is shown that chromosome misalignment
influences MI spindle formation and stabilization (Hawley, 2011;
Nagaoka et al., 2011), and this sets up the direct evidence for the link
of SAC and spindle formation, although the main regulatory role of
SAC is to monitor the chromosome alignment. Although the functions
of numerous SAC regulators have been studied in model animals,
their roles in mammalian species are still unknown. For example, roles
of KNL-1 and Mis12 complex in mammalian meiosis are lacking, the
direct evidence for KNL-1 and Mis12 complex to SAC regulation is
also absent.
Slight differences in the localization and functions of SAC proteins
and their regulators have been revealed in germ cell meiosis of different sexes and species, which may determine the incidence of chromosome missegregation. Further research is needed to investigate the
underlying mechanisms for gender-specific and species-specific differences in aneuploidy induction.
The SAC should ensure the faithful chromosome segregation to
avoid aneuploidy, however, most studies have been conducted in
model animals and little is known about this process in human
oocytes, which are prone to segregation errors (Jones, 2008).
Whether noted differences of SAC components are consistent with
chromosome segregation and whether there is a unique nature of
SAC and its regulators in human oocytes definitely needs further investigations. Clearly, clarification of the above questions will lead to a
better understanding on the regulation of germ cell development
and the cause for aneuploidy, which may further aid in understanding
human fertility and birth defects.
Authors’ roles
S.C.S. design of the study, acquisition and interpretation of data, drafting and revising of the article and the final approval. N.H.K. design of
the study, revising of the article and the final approval.
Acknowledgements
We thank Dr Bo Xiong at National Institute of Diabetes and Digestive
and Kidney Diseases (NIDDK) for helpful discussion.
Funding
This work is sponsored by Next-Generation Biogreen 21 Program
(No.PJ008067), RDA, Republic of Korea.
References
Asakawa H, Hayashi A, Haraguchi T, Hiraoka Y. Dissociation of the Nuf2-Ndc80
complex releases centromeres from the spindle-pole body during meiotic
prophase in fission yeast. Mol Biol Cell 2005;16:2325 –2338.
Baker DJ, Jeganathan KB, Cameron JD, Thompson M, Juneja S, Kopecka A, Kumar R,
Jenkins RB, de Groen PC, Roche P et al. BubR1 insufficiency causes early onset of
aging-associated phenotypes and infertility in mice. Nat Genet 2004;36:744– 749.
Basu J, Logarinho E, Herrmann S, Bousbaa H, Li Z, Chan GK, Yen TJ, Sunkel CE,
Goldberg ML. Localization of the Drosophila checkpoint control protein Bub3 to
the kinetochore requires Bub1 but not Zw10 or Rod. Chromosoma 1998;
107:376 –385.
Basu J, Bousbaa H, Logarinho E, Li Z, Williams BC, Lopes C, Sunkel CE,
Goldberg ML. Mutations in the essential spindle checkpoint gene bub1 cause
chromosome missegregation and fail to block apoptosis in Drosophila. J Cell Biol
1999;146:13– 28.
Bernard P, Maure JF, Javerzat JP. Fission yeast Bub1 is essential in setting up the
meiotic pattern of chromosome segregation. Nat Cell Biol 2001;3:522 –526.
Bourhis E, Hymowitz SG, Cochran AG. The mitotic regulator Survivin binds as a
monomer to its functional interactor Borealin. J Biol Chem 2007;282:35018 –35023.
Brunet S, Pahlavan G, Taylor S, Maro B. Functionality of the spindle checkpoint
during the first meiotic division of mammalian oocytes. Reproduction 2003;
126:443 –450.
Cahill DP, Lengauer C, Yu J, Riggins GJ, Willson JK, Markowitz SD, Kinzler KW,
Vogelstein B. Mutations of mitotic checkpoint genes in human cancers. Nature
1998;392:300– 303.
Cheslock PS, Kemp BJ, Boumil RM, Dawson DS. The roles of MAD1, MAD2 and
MAD3 in meiotic progression and the segregation of nonexchange
chromosomes. Nat Genet 2005;37:756– 760.
Ciferri C, Musacchio A, Petrovic A. The Ndc80 complex: hub of kinetochore
activity. FEBS Lett 2007;581:2862– 2869.
Colombie N, Verollet C, Sampaio P, Moisand A, Sunkel C, Bourbon HM, Wright M,
Raynaud-Messina B. The Drosophila gamma-tubulin small complex subunit
Dgrip84 is required for structural and functional integrity of the spindle
apparatus. Mol Biol Cell 2006;17:272 –282.
Colombie N, Cullen CF, Brittle AL, Jang JK, Earnshaw WC, Carmena M, McKim K,
Ohkura H. Dual roles of Incenp crucial to the assembly of the acentrosomal
metaphase spindle in female meiosis. Development 2008;135:3239 –3246.
Cross DA, Smythe C. PD 98059 prevents establishment of the spindle assembly
checkpoint and inhibits the G2-M transition in meiotic but not mitotic cell
cycles in Xenopus. Exp Cell Res 1998;241:12–22.
de Carvalho CE, Zaaijer S, Smolikov S, Gu Y, Schumacher JM, Colaiacovo MP. LAB-1
antagonizes the Aurora B kinase in C. elegans. Genes Dev 2008;22:2869 –2885.
Diaz-Rodriguez E, Sotillo R, Schvartzman JM, Benezra R. Hec1 overexpression
hyperactivates the mitotic checkpoint and induces tumor formation in vivo. Proc
Natl Acad Sci USA 2008;105:16719– 16724.
Du Y, Dawe RK. Maize NDC80 is a constitutive feature of the central kinetochore.
Chromosome Res 2007;15:767 –775.
Dumont J, Umbhauer M, Rassinier P, Hanauer A, Verlhac MH. p90Rsk is not
involved in cytostatic factor arrest in mouse oocytes. J Cell Biol 2005;
169:227 –231.
Dumont J, Oegema K, Desai A. A kinetochore-independent mechanism drives
anaphase chromosome separation during acentrosomal meiosis. Nat Cell Biol
2010;12:894 –901.
70
Eaker S, Cobb J, Pyle A, Handel MA. Meiotic prophase abnormalities and metaphase
cell death in MLH1-deficient mouse spermatocytes: insights into regulation of
spermatogenic progress. Dev Biol 2002;249:85– 95.
Eichenlaub-Ritter U, Staubach N, Trapphoff T. Chromosomal and cytoplasmic
context determines predisposition to maternal age-related aneuploidy: brief
overview and update on MCAK in mammalian oocytes. Biochem Soc Trans
2010;38:1681 –1686.
Fan HY. BubR1, a spindle assembly checkpoint protein in mammalian oocyte
meiosis. Cell Cycle 2010;9:1456 –1465.
Furuta T, Tuck S, Kirchner J, Koch B, Auty R, Kitagawa R, Rose AM, Greenstein D.
EMB-30: an APC4 homologue required for metaphase-to-anaphase transitions
during meiosis and mitosis in Caenorhabditis elegans. Mol Biol Cell 2000;
11:1401– 1419.
Gao S, Giansanti MG, Buttrick GJ, Ramasubramanyan S, Auton A, Gatti M,
Wakefield JG. Australin: a chromosomal passenger protein required specifically
for Drosophila melanogaster male meiosis. J Cell Biol 2008;180:521– 535.
George O, Johnston MA, Shuster CB. Aurora B kinase maintains chromatin
organization during the MI to MII transition in surf clam oocytes. Cell Cycle
2006;5:2648 – 2656.
Gilliland WD, Wayson SM, Hawley RS. The meiotic defects of mutants in the
Drosophila mps1 gene reveal a critical role of Mps1 in the segregation of
achiasmate homologs. Curr Biol 2005;15:672– 677.
Gilliland WD, Hughes SE, Cotitta JL, Takeo S, Xiang Y, Hawley RS. The multiple
roles of mps1 in Drosophila female meiosis. PLoS Genet 2007;3:e113.
Grimison B, Liu J, Lewellyn AL, Maller JL. Metaphase arrest by cyclin E-Cdk2 requires
the spindle-checkpoint kinase Mps1. Curr Biol 2006;16:1968 –1973.
Hached K, Xie SZ, Buffin E, Cladiere D, Rachez C, Sacras M, Sorger PK,
Wassmann K. Mps1 at kinetochores is essential for female mouse meiosis I.
Development 2011;138:2261 –2271.
Han X, Srayko M. Meiotic kinetochores get pushed aside by a CLS act. Nat Cell Biol
2010;12:849 –851.
Handel MA, Schimenti JC. Genetics of mammalian meiosis: regulation, dynamics and
impact on fertility. Nat Rev Genet 2010;11:124– 136.
Hawley RS. Oogenesis: when most is good enough. Curr Biol 2011;21:R288 –R290.
Hayashi A, Asakawa H, Haraguchi T, Hiraoka Y. Reconstruction of the kinetochore
during meiosis in fission yeast Schizosaccharomyces pombe. Mol Biol Cell 2006;
17:5173– 5184.
Homer HA, McDougall A, Levasseur M, Herbert M. Restaging the spindle assembly
checkpoint in female mammalian meiosis I. Cell Cycle 2005a;4:650 –653.
Homer HA, McDougall A, Levasseur M, Murdoch AP, Herbert M. Mad2 is required
for inhibiting securin and cyclin B degradation following spindle depolymerisation
in meiosis I mouse oocytes. Reproduction 2005b;130:829– 843.
Homer HA, McDougall A, Levasseur M, Yallop K, Murdoch AP, Herbert M. Mad2
prevents aneuploidy and premature proteolysis of cyclin B and securin during
meiosis I in mouse oocytes. Genes Dev 2005c;19:202 –207.
Homer H, Gui L, Carroll J. A spindle assembly checkpoint protein functions in
prophase I arrest and prometaphase progression. Science 2009;326:991– 994.
Hoyt MA, Totis L, Roberts BT. S. cerevisiae genes required for cell cycle arrest in
response to loss of microtubule function. Cell 1991;66:507– 517.
Hwang LH, Lau LF, Smith DL, Mistrot CA, Hardwick KG, Hwang ES, Amon A,
Murray AW. Budding yeast Cdc20: a target of the spindle checkpoint. Science
1998;279:1041 –1044.
Illingworth C, Pirmadjid N, Serhal P, Howe K, Fitzharris G. MCAK regulates
chromosome alignment but is not necessary for preventing aneuploidy in
mouse oocyte meiosis I. Development 2010;137:2133 –2138.
Jeganathan KB, van Deursen JM. Differential mitotic checkpoint protein
requirements in somatic and germ cells. Biochem Soc Trans 2006;34:
583 –586.
Jelinkova L, Kubelka M. Neither Aurora B activity nor histone H3 phosphorylation is
essential for chromosome condensation during meiotic maturation of porcine
oocytes. Biol Reprod 2006;74:905– 912.
Jelluma N, Brenkman AB, van den Broek NJ, Cruijsen CW, van Osch MH, Lens SM,
Medema RH, Kops GJ. Mps1 phosphorylates Borealin to control Aurora B activity
and chromosome alignment. Cell 2008;132:233– 246.
Jiang H, Wang FF, Wu YT, Zhou X, Huang XY, Zhu J, Gao JF, Dong RB, Cao KM,
Yang ZN. MULTIPOLAR SPINDLE 1 (MPS1), a novel coiled-coil protein of
Arabidopsis thaliana, is required for meiotic spindle organization. Plant J 2009;
59:1001– 1010.
Sun and Kim
Jones KT. Meiosis in oocytes: predisposition to aneuploidy and its increased
incidence with age. Hum Reprod Update 2008;14:143 –158.
Kallio M, Eriksson JE, Gorbsky GJ. Differences in spindle association of the mitotic
checkpoint protein Mad2 in mammalian spermatogenesis and oogenesis. Dev
Biol 2000;225:112– 123.
Kiburz BM, Reynolds DB, Megee PC, Marston AL, Lee BH, Lee TI, Levine SS,
Young RA, Amon A. The core centromere and Sgo1 establish a 50-kb
cohesin-protected domain around centromeres during meiosis I. Genes Dev
2005;19:3017 –3030.
Kim SH, Lin DP, Matsumoto S, Kitazono A, Matsumoto T. Fission yeast Slp1: an
effector of the Mad2-dependent spindle checkpoint. Science 1998;
279:1045 –1047.
Kitagawa R, Rose AM. Components of the spindle-assembly checkpoint are essential
in Caenorhabditis elegans. Nat Cell Biol 1999;1:514 –521.
Kitajima TS, Kawashima SA, Watanabe Y. The conserved kinetochore protein
shugoshin protects centromeric cohesion during meiosis. Nature 2004;
427:510 –517.
Lane SI, Chang HY, Jennings PC, Jones KT. The Aurora kinase inhibitor ZM447439
accelerates first meiosis in mouse oocytes by overriding the spindle assembly
checkpoint. Reproduction 2010;140:521– 530.
Leland S, Nagarajan P, Polyzos A, Thomas S, Samaan G, Donnell R, Marchetti F,
Venkatachalam S. Heterozygosity for a Bub1 mutation causes female-specific
germ cell aneuploidy in mice. Proc Natl Acad Sci USA 2009;106:12776 –12781.
Li X, Dawe RK. Fused sister kinetochores initiate the reductional division in meiosis
I. Nat Cell Biol 2009;11:1103– 1108.
Li R, Murray AW. Feedback control of mitosis in budding yeast. Cell 1991;
66:519– 531.
Li M, Li S, Yuan J, Wang ZB, Sun SC, Schatten H, Sun QY. Bub3 is a spindle assembly
checkpoint protein regulating chromosome segregation during mouse oocyte
meiosis. PLoS One 2009;4:e7701.
Li S, Ou XH, Wang ZB, Xiong B, Tong JS, Wei L, Li M, Yuan J, Ouyang YC, Hou Y
et al. ERK3 is required for metaphase-anaphase transition in mouse oocyte
meiosis. PLoS One 2010;5:e13074.
Ma W, Zhang D, Hou Y, Li YH, Sun QY, Sun XF, Wang WH. Reduced expression of
MAD2, BCL2, and MAP kinase activity in pig oocytes after in vitro aging are
associated with defects in sister chromatid segregation during meiosis II and
embryo fragmentation after activation. Biol Reprod 2005;72:373 –383.
Ma W, Baumann C, Viveiros MM. NEDD1 is crucial for meiotic spindle stability and
accurate chromosome segregation in mammalian oocytes. Dev Biol 2010;
339:439 –450.
Macy B, Wang M, Yu HG. The many faces of shugoshin, the ‘guardian spirit,’ in
chromosome segregation. Cell Cycle 2009;8:35 –37.
Malmanche N, Owen S, Gegick S, Steffensen S, Tomkiel JE, Sunkel CE. Drosophila
BubR1 is essential for meiotic sister-chromatid cohesion and maintenance of
synaptonemal complex. Curr Biol 2007;17:1489– 1497.
Matsuura S, Ito E, Tauchi H, Komatsu K, Ikeuchi T, Kajii T. Chromosomal instability
syndrome of total premature chromatid separation with mosaic variegated
aneuploidy is defective in mitotic-spindle checkpoint. Am J Hum Genet 2000;
67:483– 486.
McGuinness BE, Anger M, Kouznetsova A, Gil-Bernabe AM, Helmhart W, Kudo NR,
Wuensche A, Taylor S, Hoog C, Novak B et al. Regulation of APC/C activity in
oocytes by a Bub1-dependent spindle assembly checkpoint. Curr Biol 2009;
19:369– 380.
Millband DN, Campbell L, Hardwick KG. The awesome power of multiple model
systems: interpreting the complex nature of spindle checkpoint signaling. Trends
Cell Biol 2002;12:205–209.
Monje-Casas F, Prabhu VR, Lee BH, Boselli M, Amon A. Kinetochore orientation
during meiosis is controlled by Aurora B and the monopolin complex. Cell
2007;128:477– 490.
Musacchio A, Hardwick KG. The spindle checkpoint: structural insights into dynamic
signalling. Nat Rev Mol Cell Biol 2002;3:731– 741.
Musacchio A, Salmon ED. The spindle-assembly checkpoint in space and time. Nat
Rev Mol Cell Biol 2007;8:379– 393.
Nagaoka SI, Hodges CA, Albertini DF, Hunt PA. Oocyte-specific differences in
cell-cycle control create an innate susceptibility to meiotic errors. Curr Biol
2011;21:651 –657.
Nasmyth K, Peters JM, Uhlmann F. Splitting the chromosome: cutting the ties that
bind sister chromatids. Science 2000;288:1379– 1385.
Spindle assemble checkpoint in meiosis
Niault T, Hached K, Sotillo R, Sorger PK, Maro B, Benezra R, Wassmann K.
Changing Mad2 levels affects chromosome segregation and spindle assembly
checkpoint control in female mouse meiosis I. PLoS One 2007;2:e1165.
Nicklas RB, Waters JC, Salmon ED, Ward SC. Checkpoint signals in grasshopper
meiosis are sensitive to microtubule attachment, but tension is still essential.
J Cell Sci 2001;114:4173– 4183.
Ohi R, Sapra T, Howard J, Mitchison TJ. Differentiation of cytoplasmic and meiotic
spindle assembly MCAK functions by Aurora B-dependent phosphorylation. Mol
Biol Cell 2004;15:2895– 2906.
Ou XH, Li S, Xu BZ, Wang ZB, Quan S, Li M, Zhang QH, Ouyang YC, Schatten H,
Xing FQ et al. p38alpha MAPK is a MTOC-associated protein regulating spindle
assembly, spindle length and accurate chromosome segregation during mouse
oocyte meiotic maturation. Cell Cycle 2010;9:4130 –4143.
Parra MT, Gomez R, Viera A, Page J, Calvente A, Wordeman L, Rufas JS, Suja JA. A
perikinetochoric ring defined by MCAK and Aurora-B as a novel centromere
domain. PLoS Genet 2006;2:e84.
Parra MT, Gomez R, Viera A, Llano E, Pendas AM, Rufas JS, Suja JA. Sequential
assembly of centromeric proteins in male mouse meiosis. PLoS Genet 2009;
5:e1000417.
Perez-Mongiovi D, Malmanche N, Bousbaa H, Sunkel C. Maternal expression of the
checkpoint protein BubR1 is required for synchrony of syncytial nuclear divisions
and polar body arrest in Drosophila melanogaster. Development 2005;
132:4509 – 4520.
Poss KD, Nechiporuk A, Stringer KF, Lee C, Keating MT. Germ cell aneuploidy in
zebrafish with mutations in the mitotic checkpoint gene mps1. Genes Dev 2004;
18:1527– 1532.
Resnick TD, Satinover DL, MacIsaac F, Stukenberg PT, Earnshaw WC,
Orr-Weaver TL, Carmena M. INCENP and Aurora B promote meiotic sister
chromatid cohesion through localization of the Shugoshin MEI-S332 in
Drosophila. Dev Cell 2006;11:57–68.
Ruchaud S, Carmena M, Earnshaw WC. Chromosomal passengers: conducting cell
division. Nat Rev Mol Cell Biol 2007;8:798–812.
Sampath SC, Ohi R, Leismann O, Salic A, Pozniakovski A, Funabiki H. The
chromosomal passenger complex is required for chromatin-induced
microtubule stabilization and spindle assembly. Cell 2004;118:187 –202.
Schwab MS, Roberts BT, Gross SD, Tunquist BJ, Taieb FE, Lewellyn AL, Maller JL.
Bub1 is activated by the protein kinase p90(Rsk) during Xenopus oocyte
maturation. Curr Biol 2001;11:141–150.
Sharif B, Na J, Lykke-Hartmann K, McLaughlin SH, Laue E, Glover DM,
Zernicka-Goetz M. The chromosome passenger complex is required for fidelity
of chromosome transmission and cytokinesis in meiosis of mouse oocytes.
J Cell Sci 2010;123:4292– 4300.
Shonn MA, Murray AL, Murray AW. Spindle checkpoint component Mad2
contributes to biorientation of homologous chromosomes. Curr Biol 2003;
13:1979– 1984.
Shuda K, Schindler K, Ma J, Schultz RM, Donovan PJ. Aurora kinase B modulates
chromosome alignment in mouse oocytes. Mol Reprod Dev 2009;76:1094 –1105.
Stein KK, Davis ES, Hays T, Golden A. Components of the spindle assembly
checkpoint regulate the anaphase-promoting complex during meiosis in
Caenorhabditis elegans. Genetics 2007;175:107– 123.
Straight PD, Giddings TH Jr, Winey M. Mps1p regulates meiotic spindle pole body
duplication in addition to having novel roles during sporulation. Mol Biol Cell 2000;
11:3525– 3537.
Sun QY. Ndc80 complex: new evidence for the existence of spindle assembly
checkpoint in mammalian oocyte meiosis. Cell Cycle 2011;10:877– 878.
Sun SC, Wei L, Li M, Lin SL, Xu BZ, Liang XW, Kim NH, Schatten H, Lu SS, Sun QY.
Perturbation of survivin expression affects chromosome alignment and
spindle checkpoint in mouse oocyte meiotic maturation. Cell Cycle 2009;8:
3365 – 3372.
Sun SC, Lee SE, Xu YN, Kim NH. Perturbation of Spc25 expression affects meiotic
spindle organization, chromosome alignment and spindle assembly checkpoint in
mouse oocytes. Cell Cycle 2010a;9:4552 –4559.
Sun SC, Lin SL, Zhang DX, Lu SS, Sun QY, Kim NH. Borealin regulates bipolar
spindle formation but may not act as chromosomal passenger during mouse
oocyte meiosis. Front Biosci (Elite Ed) 2010b;2:991 –1000.
Sun SC, Zhang DX, Lee SE, Xu YN, Kim NH. Ndc80 regulates meiotic spindle
organization, chromosome alignment, and cell cycle progression in mouse
oocytes. Microsc Microanal 2011;17:431–439.
71
Swain JE, Ding J, Wu J, Smith GD. Regulation of spindle and chromatin dynamics
during early and late stages of oocyte maturation by aurora kinases. Mol Hum
Reprod 2008;14:291– 299.
Tanaka TU, Desai A. Kinetochore-microtubule interactions: the means to the end.
Curr Opin Cell Biol 2008;20:53 –63.
Taylor SS, Scott MI, Holland AJ. The spindle checkpoint: a quality control mechanism
which ensures accurate chromosome segregation. Chromosome Res 2004;
12:599– 616.
Tsurumi C, Hoffmann S, Geley S, Graeser R, Polanski Z. The spindle assembly
checkpoint is not essential for CSF arrest of mouse oocytes. J Cell Biol 2004;
167:1037 – 1050.
Tunquist BJ, Schwab MS, Chen LG, Maller JL. The spindle checkpoint kinase bub1
and cyclin e/cdk2 both contribute to the establishment of meiotic metaphase
arrest by cytostatic factor. Curr Biol 2002;12:1027– 1033.
Tunquist BJ, Eyers PA, Chen LG, Lewellyn AL, Maller JL. Spindle checkpoint proteins
Mad1 and Mad2 are required for cytostatic factor-mediated metaphase arrest.
J Cell Biol 2003;163:1231– 1242.
Vaur S, Cubizolles F, Plane G, Genier S, Rabitsch PK, Gregan J, Nasmyth K,
Vanoosthuyse V, Hardwick KG, Javerzat JP. Control of Shugoshin function
during fission-yeast meiosis. Curr Biol 2005;15:2263 –2270.
Vogt E, Kirsch-Volders M, Parry J, Eichenlaub-Ritter U. Spindle formation,
chromosome segregation and the spindle checkpoint in mammalian oocytes
and susceptibility to meiotic error. Mutat Res 2008;651:14–29.
Vogt E, Kipp A, Eichenlaub-Ritter U. Aurora kinase B, epigenetic state of
centromeric heterochromatin and chiasma resolution in oocytes. Reprod Biomed
Online 2009;19:352 –368.
Vogt E, Sanhaji M, Klein W, Seidel T, Wordeman L, Eichenlaub-Ritter U. MCAK is
present at centromeres, midspindle and chiasmata and involved in silencing of the
spindle assembly checkpoint in mammalian oocytes. Mol Hum Reprod 2010;
16:665– 684.
Wang Y, Toppari J, Parvinen M, Kallio MJ. Inhibition of Aurora kinases perturbs
chromosome alignment and spindle checkpoint signaling in rat spermatocytes.
Exp Cell Res 2006;312:3459 –3470.
Wang JY, Lei ZL, Nan CL, Yin S, Liu J, Hou Y, Li YL, Chen DY, Sun QY. RNA
Interference as a tool to study the function of MAD2 in mouse oocyte meiotic
maturation. Mol Reprod Dev 2007;74:116– 124.
Wang K, Jiang GJ, Wei L, Liang XW, Miao DQ, Sun SC, Guo L, Wang ZB, Lu SS.
Survivin is a critical regulator of spindle organization and chromosome
segregation during rat oocyte meiotic maturation. Zygote 2011;19:307– 313.
Wassmann K, Benezra R. Mitotic checkpoints: from yeast to cancer. Curr Opin Genet
Dev 2001;11:83 –90.
Wassmann K, Niault T, Maro B. Metaphase I arrest upon activation of the
Mad2-dependent spindle checkpoint in mouse oocytes. Curr Biol 2003;
13:1596– 1608.
Wei L, Liang XW, Zhang QH, Li M, Yuan J, Li S, Sun SC, Ouyang YC, Schatten H,
Sun QY. BubR1 is a spindle assembly checkpoint protein regulating meiotic cell
cycle progression of mouse oocyte. Cell Cycle 2010;9:1112 – 1121.
Weikert S, Schrader M, Muller M, Schulze W, Krause H, Miller K. Expression levels
of the inhibitor of apoptosis survivin in testes of patients with normal
spermatogenesis and spermatogenic failure. Fertil Steril 2005;83(Suppl
1):1100 –1105.
Xiong B. Spc25: how the kinetochore protein plays during oocyte meiosis. Cell Cycle
2011;10:1028 –1029.
Xiong B, Li S, Ai JS, Yin S, Ouyang YC, Sun SC, Chen DY, Sun QY. BRCA1 is
required for meiotic spindle assembly and spindle assembly checkpoint
activation in mouse oocytes. Biol Reprod 2008;79:718– 726.
Yamaguchi S, Decottignies A, Nurse P. Function of Cdc2p-dependent Bub1p
phosphorylation and Bub1p kinase activity in the mitotic and meiotic spindle
checkpoint. EMBO J 2003;22:1075 –1087.
Yamamoto A, Kitamura K, Hihara D, Hirose Y, Katsuyama S, Hiraoka Y. Spindle
checkpoint activation at meiosis I advances anaphase II onset via
meiosis-specific APC/C regulation. J Cell Biol 2008a;182:277–288.
Yamamoto TG, Watanabe S, Essex A, Kitagawa R. SPDL-1 functions as a
kinetochore receptor for MDF-1 in Caenorhabditis elegans. J Cell Biol 2008b;
183:187 –194.
Yang F, Baumann C, De La Fuente R. Persistence of histone H2AX phosphorylation
after meiotic chromosome synapsis and abnormal centromere cohesion in poly
(ADP-ribose) polymerase (Parp-1) null oocytes. Dev Biol 2009;331:326 –338.
72
Yang KT, Li SK, Chang CC, Tang CJ, Lin YN, Lee SC, Tang TK. Aurora-C kinase
deficiency causes cytokinesis failure in meiosis I and production of large
polyploid oocytes in mice. Mol Biol Cell 2010;21:2371 –2383.
Yanowitz J. Meiosis: making a break for it. Curr Opin Cell Biol 2010;22:744– 751.
Yin S, Wang Q, Liu JH, Ai JS, Liang CG, Hou Y, Chen DY, Schatten H, Sun QY. Bub1
prevents chromosome misalignment and precocious anaphase during mouse
oocyte meiosis. Cell Cycle 2006;5:2130– 2137.
Yu HG, Koshland D. The Aurora kinase Ipl1 maintains the centromeric localization
of PP2A to protect cohesin during meiosis. J Cell Biol 2007;176:911 –918.
Yu HG, Muszynski MG, Kelly Dawe R. The maize homologue of the cell cycle
checkpoint protein MAD2 reveals kinetochore substructure and contrasting
mitotic and meiotic localization patterns. J Cell Biol 1999;145:425– 435.
Zhang D, Ma W, Li YH, Hou Y, Li SW, Meng XQ, Sun XF, Sun QY, Wang WH.
Intra-oocyte localization of MAD2 and its relationship with kinetochores,
microtubules, and chromosomes in rat oocytes during meiosis. Biol Reprod
2004;71:740 –748.
Sun and Kim
Zhang D, Li M, Ma W, Hou Y, Li YH, Li SW, Sun QY, Wang WH. Localization
of mitotic arrest deficient 1 (MAD1) in mouse oocytes during the first meiosis
and its functions as a spindle checkpoint protein. Biol Reprod 2005;
72:58 –68.
Zhang D, Yin S, Jiang MX, Ma W, Hou Y, Liang CG, Yu LZ, Wang WH,
Sun QY. Cytoplasmic dynein participates in meiotic checkpoint inactivation
in mouse oocytes by transporting cytoplasmic mitotic arrest-deficient (Mad)
proteins from kinetochores to spindle poles. Reproduction 2007;133:
685 –695.
Zhang QH, Wei L, Tong JS, Qi ST, Li S, Ou XH, Ouyang YC, Hou Y, An LG,
Schatten H et al. Localization and function of mSpindly during mouse oocyte
meiotic maturation. Cell Cycle 2010;9:2230– 2236.
Zhu JL, Lin SL, Li M, Ouyang YC, Hou Y, Schatten H, Sun QY. Septin2 is modified by
SUMOylation and required for chromosome congression in mouse oocytes. Cell
Cycle 2010;9:1607 –1616.