CIPC is a mammalian circadian clock protein without invertebrate homologues

Zhao, Wen-Ning; Malinin, Nikolay L.; Yang, Fu-Chia; Staknis, David; Gekakis, Nicholas; Maier, Bert; Reischl, Silke; Kramer, Achim; Weitz, Charles J.

doi:10.1038/ncb1539

Cited by 75 publications

(97 citation statements)

References 38 publications

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“…However, CRY1 has only moderate affinity (K d ∼1 μM) for the isolated TAD (11,17), suggesting that it makes at least one other interaction with CLOCK:BMAL1 that allows it to serve as a potent repressor when expressed to near stoichiometric levels (18). Previous studies suggest the CLOCK PAS-B domain is important for repression by CRY1 (11,19,20), but evidence for a direct interaction is lacking. To further explore the biochemical basis for interactions between CRY1 and CLOCK:BMAL1, we purified the core PHR of mouse CRY1 and a tandem PAS domain heterodimer (comprising PAS-A and PAS-B domains, PAS-AB) of mouse CLOCK:BMAL1 (Fig.…”

Section: Cry1mentioning

confidence: 99%

“…Several residues in the HI loop (connecting the Hβ and Iβ strands) of CLOCK PAS-B are important for CRY1-mediated repression of CLOCK:BMAL1 (11,19,20). The entire HI loop is freely accessible in the crystal structure of the CLOCK:BMAL1 basic helix-loop-helix (bHLH)-PAS dimer, protruding out from the PAS-B dimer interface ( Fig.…”

Section: Cry1mentioning

confidence: 99%

“…Based on previous mutagenesis data and our own studies herein, we used the following residues as active restraints, defined by their importance for binding and solvent accessibility: CRY1: G106, R109, E383, E382 (17,24); and CLOCK PAS-B: G332, H360, Q361, W362, E367 ( Fig. 3A) (11,19,20). The CRY1 restraints cluster around the secondary pocket in the PHR, which is structurally conserved with photolyase where it serves as a chromophore binding pocket (12).…”

Section: Cry1mentioning

confidence: 99%

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Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

Michael

Fribourgh

Chelliah

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The basic helix–loop–helix PAS domain (bHLH-PAS) transcription factor CLOCK:BMAL1 (brain and muscle Arnt-like protein 1) sits at the core of the mammalian circadian transcription/translation feedback loop. Precise control of CLOCK:BMAL1 activity by coactivators and repressors establishes the ∼24-h periodicity of gene expression. Formation of a repressive complex, defined by the core clock proteins cryptochrome 1 (CRY1):CLOCK:BMAL1, plays an important role controlling the switch from repression to activation each day. Here we show that CRY1 binds directly to the PAS domain core of CLOCK:BMAL1, driven primarily by interaction with the CLOCK PAS-B domain. Integrative modeling and solution X-ray scattering studies unambiguously position a key loop of the CLOCK PAS-B domain in the secondary pocket of CRY1, analogous to the antenna chromophore-binding pocket of photolyase. CRY1 docks onto the transcription factor alongside the PAS domains, extending above the DNA-binding bHLH domain. Single point mutations at the interface on either CRY1 or CLOCK disrupt formation of the ternary complex, highlighting the importance of this interface for direct regulation of CLOCK:BMAL1 activity by CRY1.

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Section: Cry1mentioning

confidence: 99%

Section: Cry1mentioning

confidence: 99%

Section: Cry1mentioning

confidence: 99%

See 1 more Smart Citation

Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

Michael

Fribourgh

Chelliah

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…At present, the exact composition of the module is unclear, although multiple additional proteins have been suggested to contribute to the periodic inhibition of CLOCK-BMAL1 activity. These include mammalian Timeless (Sangoram et al 1998;Barnes et al 2003), the bHLH transcription factors DEC1/2 (Honma et al 2002), the PER1-associated proteins NONO and WDR5 (Brown et al 2005a) as well as the CLOCK-interacting protein CIPC (Zhao et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Role of Phosphorylation in the Mammalian Circadian Clock

Vanselow¹,

Kramer²

2007

Cold Spring Harbor Symposia on Quantitative Biology

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Circadian clocks regulate a wide variety of processes ranging from gene expression to behavior. At the molecular level, circadian rhythms are thought to be produced by a set of clock genes and proteins interconnected to form transcriptional-translational feedback loops. Rhythmic gene expression was formerly regarded as the major drive for rhythms in clock protein abundance, but recent findings underline the crucial importance of posttranslational mechanisms for both the generation and dynamics of circadian rhythms. In particular, the reversible phosphorylation of PER proteins-essential components within the negative feedback loop in Drosophila and mammals-seems to have a key role for the correct timing of nuclear repression. To understand how PER protein phosphorylation regulates the dynamics of the circadian oscillator, we have mapped endogenous phosphorylation sites in mPER2. Detailed investigation of the functional role of one particular phosphorylation site (Ser-659, which is mutated in the familial advanced sleep phase syndrome [FASPS]) led us propose a model of functionally different phosphorylation sites in PER2. This concept explains not only the FASPS phenotype, but also the effect of the tau mutation in hamster.

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“…These include CRY1 and CRY2 (30), DEC1 and DEC2 (20), NONO, WDR5 (5), and CIPC (63). The intriguing question is the mechanism by which these negative regulators suppress CLOCK-BMAL1-dependent transactivation in combination or independently.…”

mentioning

confidence: 99%

Roles of CLOCK Phosphorylation in Suppression of E-Box-Dependent Transcription

Yoshitane

Takao

Satomi

et al. 2009

Molecular and Cellular Biology

119

159

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In mammalian circadian clockwork, the CLOCK-BMAL1 heterodimer activates E-box-dependent transcription, while its activity is suppressed by circadian binding with negative regulators, such as CRYs. Here, we found that the CLOCK protein is kept mostly in the phosphorylated form throughout the day and is partly hyperphosphorylated in the suppression phase of E-box-dependent transcription in the mouse liver and NIH 3T3 cells. Coexpression of CRY2 in NIH 3T3 cells inhibited the phosphorylation of CLOCK, whereas CIPC coexpression markedly stimulated phosphorylation, indicating that CLOCK phosphorylation is regulated by a combination of the negative regulators in the suppression phase. CLOCK-BMAL1 purified from the mouse liver was subjected to tandem mass spectrometry analysis, which identified Ser38, Ser42, and Ser427 as in vivo phosphorylation sites of CLOCK. Ser38Asp and Ser42Asp mutations of CLOCK additively and markedly weakened the transactivation activity of CLOCK-BMAL1, with downregulation of the nuclear amount of CLOCK and the DNA-binding activity. On the other hand, CLOCK⌬19, lacking the CIPC-binding domain, was far less phosphorylated and much more stabilized than wild-type CLOCK in vivo. Calyculin A treatment of cultured NIH 3T3 cells promoted CLOCK phosphorylation and facilitated its proteasomal degradation. Together, these results show that CLOCK phosphorylation contributes to the suppression of CLOCK-BMAL1-mediated transactivation through dual regulation: inhibition of CLOCK activity and promotion of its degradation.Many physiological activities of living organisms show rhythmic changes, with a period of approximately 24 h, even under constant conditions without any external time cues. These daily variations, called circadian rhythms, are generated by the circadian clock, a cell-autonomous time-measuring system that has evolved in a wide variety of organisms, from cyanobacteria to higher plants and humans (9). In mammals, a master clock is located in the hypothalamic suprachiasmatic nucleus, while self-sustaining molecular clocks reside even in the peripheral tissues, such as the liver (18,40,45). In these central and peripheral clock cells, the clock genes form a transcription/ translation-based negative-feedback loop to generate the molecular oscillation with 24-h periodicity. CLOCK and BMAL1 are basic helix-loop-helix (bHLH)-PAS transcription factors, and the CLOCK-BMAL1 heterodimer binds to CACGTG E-box (14) or E-box-like (25, 61) sequences for the transactivation of negative regulatory genes, such as Period (Per1 and Per2) and Cryptochrome (Cry1 and Cry2) genes. Newly translated PERs and CRYs enter the nuclei and bind to the CLOCK-BMAL1 heterodimer, leading to suppression of its transactivation (30).In the mouse liver, the abundances and the phosphorylation states of both PER1 and PER2 show striking temporal changes (32). The total amount of each PER protein shows the lowest level at CT6 (CT is circadian time, with CT0 under the constant-dark [DD] condition corresponding to the lights-on time in the...

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CIPC is a mammalian circadian clock protein without invertebrate homologues

Cited by 75 publications

References 38 publications

Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

Role of Phosphorylation in the Mammalian Circadian Clock

Roles of CLOCK Phosphorylation in Suppression of E-Box-Dependent Transcription

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