Isaac Edery Professor Rutgers University Department of Molecular Biology and Biochemistry CABM Room 339 679 Hoes Lane Piscataway. NJ 08854 (732) 235-5550 FAX - 5318 edery@cabm.rutgers.edu

Circadian clocks. photic signal transduction. Drosophila behavior. seasonal adaptation. pre-mRNA splicing. protein phosphorylation and degradation

The main goal of our laboratory is to understand the molecular and biochemical bases of biological clocks. To achieve this goal. we are using the powerful genetics available in Drosophila in combination with biochemical. molecular and histochemical approaches.

Daily fluctuations in biochemical. physiological and behavioral phenomena are governed by endogenous circadian (~24 hour) clocks that can be synchronized (entrained) by external time cues (zeitgebers). most notably the daily changes in light/dark and temperature. This adaptive feature of circadian clocks enables organisms to temporally align their physiology and behavior such that they occur at biologically advantageous times during the day.

The isolation of "clock genes" has provided significant insights into the molecular underpinnings governing circadian rhythms. A common theme in clocks from bacteria to humans is that at the "heart" of these pacemakers lie transcriptional-translational feedback loops. The best characterized animal model system for a circadian clock is Drosophila melanogaster. where four clock proteins termed PERIOD (PER). TIMELESS (TIM). dCLOCK and CYCLE (CYC) function in a negative transcriptional autoregulatory loop. dCLOCK and CYC are members of the basic-helix-loop-helix (bHLH)/PAS (PER-ARNT-SIM) superfamily of transcription factors and are required for the daily stimulation of per and tim expression. PER and TIM form a complex in the cytoplasm that enters the nucleus in a temporally gated manner where they bind the dCLOCK-CYC heterodimer blocking its DNA binding activity. In the absence of denovo synthesis. the concentrations of PER and TIM in the nucleus decrease below threshold levels relieving autoinhibition. enabling the next round of per and tim transcript accumulation. Posttranscriptional mechanisms play an important role because they introduce "biochemical time constraints" that stretch the transcriptional feedback loop to ~24 hr and also allows it to respond to external stimuli. For example. light evokes the rapid degradation of TIM. the primary clock-specific photoresponse resetting the oscillatory mechanism. A blue-light photoreceptor called CRYPTOCHROME (CRY) has been implicated in transducing photic signals to TIM. Furthermore. the cytoplasmic phosphorylation of PER by the kinase DOUBLE-TIME (DBT) renders PER unstable. Cytoplasmic PER is stabilized by interacting with TIM which ensures that the accumulation and nuclear entry of the PER-TIM complex is a slow process creating a time-window for daily increases in the levels of per and tim transcripts. Our studies are geared towards isolating all the components that comprise a circadian timekeeping device and understanding how the daily changes in visible light and ambient temperature modulate the oscillatory mechanism.

Selected Publications

Edery I. (2009) A stretch from the periphery helps brain clocks feel the daily heat. Neuron. 64(2):157-60.

Low KH, Lim C, Ko HW, Edery I. (2008) Natural variation in the splice site strength of a clock gene and species-specific thermal adaptation. Neuron. 60(6):1054-67.

Chiu JC, Vanselow JT, Kramer A, Edery I. (2008) The phospho-occupancy of an atypical SLIMB-binding site on PERIOD that is phosphorylated by DOUBLETIME controls the pace of the clock. Genes Dev. 22(13):1758-72.

Yang M, Lee JE, Padgett RW, Edery I. (2008) Circadian regulation of a limited set of conserved microRNAs in Drosophila. BMC Genomics. 9:83.

Lee JE, Edery I. (2008) Circadian regulation in the ability of Drosophila to combat pathogenic infections. Curr Biol. 18(3):195-9.

Ko HW, DiMassa S, Kim EY, Bae K, Edery I. (2007) Cis-combination of the classic per(S) and per(L) mutations results in arrhythmic Drosophila with ectopic accumulation of hyperphosphorylated PERIOD protein. J Biol Rhythms. 22(6):488-501.

Kim EY, Ko HW, Yu W, Hardin PE, Edery I. (2007) A DOUBLETIME kinase binding domain on the Drosophila PERIOD protein is essential for its hyperphosphorylation, transcriptional repression and circadian clock function. Mol Cell Biol. 27(13):5014-28.

Edery I. (2007) A blend of two circadian clocks, seasoned to perfection. Cell. 129(1):21-3.

Bae K, Edery I. (2006) Regulating a circadian clock's period, phase and amplitude by phosphorylation: insights from Drosophila. J Biochem (Tokyo). 140(5):609-17.

Chen WF, Majercak J, Edery I. (2006) Clock-gated photic stimulation of timeless expression at cold temperatures and seasonal adaptation in Drosophila. J Biol Rhythms. 21(4):256-71.

Kim EY. Edery I. (2006) Balance between DBT/CKIepsilon kinase and protein phosphatase activities regulate phosphorylation and stability of Drosophila CLOCK protein. Proc Natl Acad Sci U S A. 103(16):6178-83.

Ko HW. Edery I. (2005) Analyzing the degradation of PERIOD Protein by the ubiquitin-proteasome pathway in cultured Drosophila cells. Methods Enzymol. 393:394-408.

Majercak. J.. Chen. W.-F. and Edery. I. (2004). Splicing of period 3' terminal intron is regulated by light. circadian clock factors and phospholipase C. Mol. Cell. Biol. 24: 3359-3372.

Akten. B.. E. Jauch. G. K. Genova. E. Y. Kim. I. Edery. T. Raabe. F. R. Jackson. (2003). A role for CK2 in the Drosophila circadian oscillator. Nature Neurosci. 6. 251-257.