Exploring the Effects and Mechanism of the
CEP-1 Tumor Suppressor on Chromosome
Nondisjunction in C. elegans
Kendrick Yim
Mentors: Dr. Nate Dudley, Dr. Pradeep Joshi
Faculty Advisor: Dr. Joel Rothman
Molecular, Cellular, and Developmental Biology
Beckman Scholars Program, UCSB
8/16/12
The Cancer Epidemic
• What is cancer?
• American Cancer
Society: 1 in 2 men and
1 in 3 women will
develop cancer.
• Cancer mortality rates
have remained
stagnant.
The Role of p53 and Chromosome
Nondisjunction in Cancer
• p53: Master guardian of the •
genome
• Normal cell  cancerous cell •
Aneuploidy: abnormal
complement of chromosomes
Chromosome Nondisjunction:
Chromosome distribution error
CEP-1 in C. elegans as p53 model
• CEP-1 = p53 homologue
• C. elegans: genetic and
biochemical tools
-
Assay for X nondisjunction
• DNA binding domain
Goal:
• Effects of knocking out and
overexpressing CEP-1 on
chromosome nondisjunction
• Elucidate the molecular
mechanism
Derry et al. 2001. Caenorhabditis elegans p53: Role in Apoptosis,
Meiosis, and Stress Resistance. Science 294,591
Testing for X Chromosome Nondisjunction
• Cross to generate
hs-CEP-1; him-5(-) strain
• HS worms at 33°C during
gametogenesis
• Compare % of males in
progeny before/after
heatshock
Testing for Autosomal Nondisjunction
• Cross to generate
1) him-6(-); hs-CEP-1; (dpy; unc)
2) him-6(-); CEP-1(-); (dpy, unc)
• Score embryonic lethality and
proportion of markers in both
strains
http://wormclassroom.org/files/worm/dpyHalf.mov
Overexpression of CEP-1 Suppresses
Him Phenotype
• ~29% decrease in proportion of males
CEP-1’s Novel Role
• CEP-1 regulates X chromosome segregation
– Suppresses X nondisjunction
• In the absence of HIM-5, CEP-1 is recruited to help
facilitate proper X chromosome distribution.
CEP-1
CEP-1
In Progress/ Future Studies
• Determining the optimal window for CEP-1
suppression.
• qPCR to quantitate levels of CEP-1 expression
• Finish constructing him-6 mutants and score
• Begin to elucidate molecular mechanism of
CEP-1
CEP-1 Understanding May Translate to
p53 Understanding
• In many aspects CEP-1 = p53
• p53 may also regulate chromosome
nondisjunction in humans
• Development of new diagnostic and
therapeutic tools
Acknowledgements
•
•
•
•
•
Dr. Joel H. Rothman
Dr. Nate Dudley
Dr. Pradeep Joshi
Other Rothman lab members
Dr. Arica Lubin, Dr. Mariateresa Napoli, Tyler Shropshire,
and all other CSEP organizers
• Arnold and Mabel Beckman Foundation
– Beckman Scholars Program
Questions?
1
dpy
1
2
unc
wt
him-6; hs-CEP-1; dpy I, unc II
2
wt
him-6; hs-CEP-1
Non-dpy, unc
dpy
unc
wt
wt