P177
The Drosophila Brahma chromatin remodeling complex and its role in regulating
circadian transcription: uncovering regulatory events at the per promoter
Rosanna Kwok , Ying Li , Anna Lei , Joanna Chiu
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1Entomology, University of California, Davis, Davis, CA, UNITED STATES
Temporal changes in the levels of mRNAs and proteins of the positive and negative elements of the
circadian oscillator over the circadian cycle are critical for the normal progression of the clock and its control
over organismal physiology and behavior. These molecular oscillations are tightly controlled by
transcriptional-translational feedback mechanisms orchestrated by key clock transcription factors that have
been studied extensively, as well as interactions between these proteins, chromatin remodeling factors, and
RNA polymerase II (pol II). Using Drosophila melanogaster as a model and its versatile genetic tools, we
investigated the role of the BRAHMA (BRM) chromatin remodeling complex in regulating the circadian
transcriptome. Our results suggest that the BRM complex interacts with key clock proteins and binds to the
per promoter in a temporally-dependent manner. Without BRM, flies exhibit defective behavioral rhythms
and have increased levels of per and tim mRNA, suggesting a role in the repression of CLK-dependent
activation of circadian promoters. Ongoing experiments aim to uncover the regulatory events that take place
at the per promoter by (i) testing whether and how BRM affects CLK binding at the per promoter, (ii)
exploring how BRM alters chromatin structure, and (iii) uncovering RNA Pol II occupancy at the per
promoter in the absence of BRM. Our research advances the understanding of transcriptional control,
specifically the role of chromatin remodeling, in this oscillating system. Moreover, our study will contribute to
the broad area of study on the effects of chromatin modifications on the control of cellular and organismal
physiology.