Cryptochrome proteins regulate the circadian intracellular behavior and localization of PER2 in mouse suprachiasmatic nucleus neurons.
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Authors
Niranjan, Dhevahi
Polidarova, Lenka
Chin, Jason W
Publication Date
2022-01-25Journal Title
Proc Natl Acad Sci U S A
ISSN
0027-8424
Publisher
Proceedings of the National Academy of Sciences
Volume
119
Issue
4
Language
eng
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Smyllie, N. J., Bagnall, J., Koch, A. A., Niranjan, D., Polidarova, L., Chesham, J. E., Chin, J. W., et al. (2022). Cryptochrome proteins regulate the circadian intracellular behavior and localization of PER2 in mouse suprachiasmatic nucleus neurons.. Proc Natl Acad Sci U S A, 119 (4) https://doi.org/10.1073/pnas.2113845119
Abstract
The ∼20,000 cells of the suprachiasmatic nucleus (SCN), the master circadian clock of the mammalian brain, coordinate subordinate cellular clocks across the organism, driving adaptive daily rhythms of physiology and behavior. The canonical model for SCN timekeeping pivots around transcriptional/translational feedback loops (TTFL) whereby PERIOD (PER) and CRYPTOCHROME (CRY) clock proteins associate and translocate to the nucleus to inhibit their own expression. The fundamental individual and interactive behaviors of PER and CRY in the SCN cellular environment and the mechanisms that regulate them are poorly understood. We therefore used confocal imaging to explore the behavior of endogenous PER2 in the SCN of PER2::Venus reporter mice, transduced with viral vectors expressing various forms of CRY1 and CRY2. In contrast to nuclear localization in wild-type SCN, in the absence of CRY proteins, PER2 was predominantly cytoplasmic and more mobile, as measured by fluorescence recovery after photobleaching. Virally expressed CRY1 or CRY2 relocalized PER2 to the nucleus, initiated SCN circadian rhythms, and determined their period. We used translational switching to control CRY1 cellular abundance and found that low levels of CRY1 resulted in minimal relocalization of PER2, but yet, remarkably, were sufficient to initiate and maintain circadian rhythmicity. Importantly, the C-terminal tail was necessary for CRY1 to localize PER2 to the nucleus and to initiate SCN rhythms. In CRY1-null SCN, CRY1Δtail opposed PER2 nuclear localization and correspondingly shortened SCN period. Through manipulation of CRY proteins, we have obtained insights into the spatiotemporal behaviors of PER and CRY sitting at the heart of the TTFL molecular mechanism.
Keywords
FRAP, Cry1, Scn, Nuclear Retention, Intracellular Mobility
Sponsorship
Medical Research Council (MC_U105170643)
NIGMS NIH HHS (R35 GM141849, R01 GM107069)
Biotechnology and Biological Sciences Research Council (BB/P017347/1)
Identifiers
PMC8795536, 35046033
External DOI: https://doi.org/10.1073/pnas.2113845119
This record's URL: https://www.repository.cam.ac.uk/handle/1810/334252
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