Meagan Esbin

Graduate Student

Understanding Fundamental Gene Regulation by General Transcriptional Coactivators


Gene activation by transcription factors (TFs) is one of the most fundamental processes in a cell. The relay and integration of gene activation signals is coordinated by large co-activator complexes that bind to both the TFs themselves and the general transcription machinery (GTFs) to nucleate pre-initiation complex (PIC) formation at the promoters of specific genes.
In humans, these complexes include TFIID, SAGA, and the Mediator complex. Each of these complexes have unique TF-binding, DNA-binding, and/or chromatin modifying activities and genome-wide studies have found both overlapping and gene- and context-specific roles for each complex.
I am also utilizing a specific biological gene activation network central to autophagy with applications to human diseases including neurodegenerative disorders and cancer, to investigate the roles and coactivators involved in network regulation.
My project aims to elucidate the structural, mechanistic, and live-cell dynamic regulation of these coactivators using state-of-the-art imaging techniques to visualize single molecules of such complexes in living cells as well as collaborative cryo-EM studies with the Nogales Lab. Coupled with specific perturbations and biochemical and genomic approaches, we can gain mechanistic insight into fundamental co-activator mechanisms and dynamics.

Structure of the human SAGA coactivator complex (Herbst & Esbin et al. BioRxiv 2021).

TFEB is a master regulator of autophagy – upon starvation or mTOR inhibition, TFEB is dephosphorylated and translocates to the nucleus where it activates the CLEAR gene network and upregulates autophagy. Diagram created with bioRENDER.

Single molecule tracking done with 500ms exposure time to visualize chromatin-bound molecules of an endogenous Halo-tagged human coactivator subunit in HeLa cells.