Optogenetic regulation of Ca2+ signaling
April 15, 2013
Class objectives:
• What is optogenetics?
• Mammalian rhodopsin.
• Biophysics of channelrhodopsin-2.
• Opto-XR
• Optically-induced dimerization
What is optogenetics?
“Optogenetics is the combination of optical and
molecular strategies to monitor and control
designated molecular and cellular activities in
living tissues and cells using genetically encoded
photosensitive proteins.”
Mammalian rhodopsin
11-cis-retinal
11-cisretinylidene
All-transretinylidene
Channelrhodopsin-2 is a lightactivated cation channel
Green alga
Chlamydomonas reinhardtii
Nagel G et al. PNAS 2003;100:13940-13945
Action spectra of channelrhodopsins
Nagel G et al. PNAS 2003;100:13940-13945
ChR chimeras with different spectral
properties
Prigge M et al. J. Biol. Chem. 2012;287:31804-31812
Dual light excitation and ion selectivity for
blue and green light-absorbing ChRs.
Prigge M et al. J. Biol. Chem. 2012;287:31804-31812
Signalling specificity and in vivo
functionality of Opto-XRs
RD Airan et al. Nature (2009)
OptoXR: optogenetic control of
intracellular signal transduction.
RD Airan et al. Nature 000, 1-5 (2009) doi:10.1038/nature07926
Opto-a1AR activation of TRPV4
channels
Systems for optically-induced
protein interactions
Activation
wavelength
(nm)
Flavin-binding, kelch
repeat, F box 1 (FKF1)
and gigantea (GI)
Blue light
Phytocrome B and
PIF6
Associates with
red light and
dissociates with
far-red light
CIB1 and cryptochrome Blue light
2 (CRY2), a blue light–
absorbing photosensor
that binds CIB1 in its
photoexcited state9
Reversible
Reference
Yes (hours) Yazawa et al.
2009
Yes
(seconds)
Liu et al. 2008
Yes
(minutes)
Kennedy et al.
2010
Light-induced translocation of
PKCa
FKF1-GI system
0s
60 s
Rapid light-induced recruitment of a 5-ptase
to the plasma membrane
Idevall-Hagren O et al. PNAS 2012;109:E2316-E2323
Blue light-induced recruitment of a 5phosphatase to the plasma membrane
rapidly decreases KCNQ2/3 current.
Idevall-Hagren O et al. PNAS 2012;109:E2316-E2323
Intermission
Jia et al.(2011) Fig. 1
Jia et al.(2011) Fig. 2a-b
Jia et al.(2011) Fig. 2c-e
Jia et al.(2011) Fig. 3a-c
Jia et al.(2011) Fig. 3d-f
Jia et al.(2011) Fig. 4a-b
Jia et al.(2011) Fig. 3c-g
Jia et al.(2011) Supplemental Fig. 1a-b
Jia et al.(2011) Supplemental Fig. 1c-d
Jia et al.(2011) Supplemental Movies
Supplemental movies