Sumoylation controls CLOCK-BMAL1-mediated clock resetting via CBP recruitment in nuclear transcriptional foci

Abstract

CLOCK-BMAL1 is a key transcription factor complex of the molecular clock system that generates circadian gene expression and physiology in mammals. Here, we demonstrate that sumoylation of BMAL1 mediates the rapid activation of CLOCK-BMAL1 by CREB-binding protein (CBP) in nuclear foci and also the resetting of the circadian clock. Under physiological conditions, a bimolecular fluorescence complementation-based fluorescence resonance energy transfer (BiFC-FRET) assay revealed that CLOCK-BMAL1 rapidly dimerized and formed a ternary complex with CBP in discrete nuclear foci in response to serum stimuli. We found that the formation of this ternary complex requires sumoylation of BMAL1 by SUMO3. These processes were abolished by both the ectopic expression of the SUMP2/3-specific protease, SUSP1, and mutation of the major sumoylation site (Lys259) of BMAL1. Moreover, molecular inhibition of BMAL1 sumoylation abrogated acute Per1 transcription and severely dampened the circadian gene oscillation triggered by clock synchronization stimuli. Taken together, these findings suggest that sumoylation plays a critical role in the spatiotemporal co-activation of CLOCK-BMAL1 by CBP for immediate-early Per induction and the resetting of the circadian clock.

CLOCK and BMAL1 stabilize and activate RHOA to promote F-actin formation in cancer cells

“…CLOCK and BMAL1 are traditionally considered to be two transcription factors that play core roles by forming CLOCK/BMAL1 heterodimers. These molecules initiate target gene transcription by binding to the promoter regions of the genes in mammals 28 , 29 . Nevertheless, our data provide novel mechanistic insight into circadian genes as a regulator to inhibit CUL3-mediated RHOA ubiquitination and suppress the binding of RhoGDIs to RHOA.…”

Inhibitor of DNA binding 2 (Id2) Regulates Photic Entrainment Responses in Mice: Differential Responses of the Id2-/- Mouse Circadian System Are Dependent on Circadian Phase and on Duration and Intensity of Light

“…Some mechanistic insight into the Id2-/-phenotype can be found from the clock-resetting pathway that involves the CLOCK-BMAL1 complex (Shearman and Weaver, 1999;Jung et al, 2003;Shim et al, 2007;Lee et al, 2010;Lee et al, 2015). A current model poses that the protein kinase C-activated CLOCK becomes partnered with sumoylated BMAL1 together with CREB binding protein, which, as a complex, results in the activation of the per1 gene promoter via its E-box elements (Lee et al, 2015). Importantly, this event is achieved independently of the classical pCREB activation of the CRE of the per1 promoter (Travnickova-Bendova et al, 2002;Lee et al, 2010;Jagannath et al, 2013).…”

Regulation of transcription factors by sumoylation

“… 12 Similarly, association of CBP with the CLOCK1-BMAL1 TF complex is dependent on BMAL1 sumoylation, allowing transcription of the circadian rhythm-regulated gene Per1 . 22 CBP/p300 contains a type of ZZ zinc finger domain that mediates a direct interaction with SUMO1, suggesting that additional TFs might recruit CBP/p300 through their sumoylation. 24 In other cases, TF sumoylation promotes transcription not by recruiting coactivators, but by disrupting the recruitment or assembly of corepressor complexes.…”