INVESTIGATION OF THE CHROMATIN REGULATOR SET4 IN HYPOXIC STRESS IN SACCHAROMYCES CEREVISIAE

Stress responses in yeast are often mediated by changes in gene expression during cellular adaptation. This genomic reprogramming is dependent on dynamic signaling events that modulate the chromatin environment, resulting in changes in transcriptional regulation. The conserved yeast protein Set4 is induced under low oxygen conditions and is a key regulator of the chromatin environment in hypoxia. Set4 is part of a subset of the SET domain lysine methyltransferases that appear to lack catalytic activity known as the Set3 SET domain subfamily. It is a paralog to the chromatin regulator Set3 in yeast, and orthologous to mammalian MLL5/KMT2E and SETD5, which have each been implicated in dysregulation of neurodevelopment and various cancers. Thus, determining the mechanisms by which these noncanonical SET domain proteins function in regulating chromatin may elucidate further insight into human disease. Though the protein interactions of the Set3 subfamily have been characterized, it remains unclear what proteins interact with Set4 and by what mechanism Set4 mediates its protective role under hypoxic stress. Here, we present our current investigation on Set4 and its involvement with chromatin modifiers and transcription regulators to control gene regulation in hypoxia. We also show potential protein interactors of Set4 and detail multiple methods used to immunoprecipitate Set4. Finally, we characterize the noncanonical SET domains of Set3 and Set4 and differentiate the roles of these paralogs in hypoxic stress. Altogether, these studies shed new light on the complex regulation of chromatin and gene expression in response to hypoxia and reveal potential new roles for this disease-associated family of proteins.