Investigating the regulation of distinct human adipocyte subpopulations

Project Summary Adipose tissue is a central player in energy balance and glucose homeostasis, it is able to expand in the face of caloric overload in order to store energy safely, but it can become overloaded and dysfunctional, leading to systemic metabolic compromise in the form of insulin resistance and Type 2 diabetes. To investigate differences in individual cell types in lean and obese individuals, I have performed single nucleus RNA sequencing (sNuc- seq) on human subcutaneous and visceral white adipose tissue and created an atlas of cell types present in white adipose tissue. A major finding from this work was the identification of distinct subpopulations of adipocytes, some of which are associated with body mass index (BMI). By associating our data with genome- wide association studies (GWAS) for metabolic traits such as T2D, we additionally predict that some adipocyte subpopulations are associated with metabolic disease. The objective of this project is to identify factors that predispose one subpopulation over another, both externally as well as transcriptionally. To do this I will perform sNuc-seq on adipose tissue collected from subjects during and post-bariatric surgery in order to characterize the change in adipocyte subpopulation during weight loss. I will next interrogate the chromatin state of adipocyte subpoulations by performing the Assay for Transposase Accessible Chromatin on single nuclei from adipose tissue of lean and obese individuals. Finally, I will directly test potential signaling and transcriptional regulators of subpopulation identity by performing a screen of potential signaling regulators as well as a CRISPRa screen of potential transcriptional regulators to try to recapitulate distinct subpopulations in vitro. The experience that I have in characterizing adipose tissue at single cell resolution, as well as the experience of my mentor and co- mentor in studying transcriptional and genetic regulation of adipocytes make me uniquely positioned to answer these questions. Taken together, these studies will enhance our knowledge of human white adipocyte diversity and will set the stage for downstream studies in my own independent lab and in the community at large.