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Optogenetic regulation of Ca2+ signalingApril 15, 2013
Class objectives:• What is optogenetics? • Mammalian rhodopsin.• Biophysics of channelrhodopsin-2.• Opto-XR• Optically-induced dimerization
“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.”
What is optogenetics?
Mammalian rhodopsin
11-cis-retinal
11-cis-retinylidene
All-trans-retinylidene
Channelrhodopsin-2 is a light-activated cation channel
Green alga Chlamydomonas reinhardtii
Nagel G et al. PNAS 2003;100:13940-13945
Nagel G et al. PNAS 2003;100:13940-13945
Action spectra of channelrhodopsins
Prigge M et al. J. Biol. Chem. 2012;287:31804-31812
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.
RD Airan et al. Nature (2009)
Signalling specificity and in vivo functionality of Opto-XRs
RD Airan et al. Nature 000, 1-5 (2009) doi:10.1038/nature07926
OptoXR: optogenetic control of intracellular signal transduction.
Opto-1AR activation of TRPV4 channels
Activation wavelength
(nm)
Reversible Reference
Flavin-binding, kelch repeat, F box 1 (FKF1) and gigantea (GI)
Blue light Yes (hours) Yazawa et al. 2009
Phytocrome B and PIF6
Associates with red light and dissociates with far-red light
Yes (seconds)
Liu et al. 2008
CIB1 and cryptochrome 2 (CRY2), a blue light–absorbing photosensor that binds CIB1 in its photoexcited state9
Blue light Yes (minutes)
Kennedy et al. 2010
Systems for optically-induced protein interactions
Light-induced translocation of PKC
FKF1-GI system
Idevall-Hagren O et al. PNAS 2012;109:E2316-E2323
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 5-phosphatase to the plasma membrane rapidly decreases KCNQ2/3 current.
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
Supplemental movies
Jia et al.(2011) Supplemental Movies
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