Sex chromosomes and beta-cell function - Project Summary. Although Type 2 diabetes (T2D) has been established as a disease affecting insulin producing pancreatic β-cells, surprisingly little is known on the molecular differences across sex. Recent work demonstrates that sex affects T2D pathogenesis, and therapeutic response. Generally, sex differences across disease are due to 1) sex chromosome genes, and/or 2) sex hormones. Sex chromosome genes consist of unique epigenetic modifiers which alter the transcriptome owing to dichotomous gene regulation. Similarly, sex hormones target conserved sex hormone receptors which effect cellular function via 1) direct genomic interaction and 2) extra-genomic cytoplasmic effects. These differences confer dichotomous advantages to cells from each sex. However molecular studies describing transcriptional regulation of sex differences across pancreatic cells in humans are lacking, primarily owing to the lack of a human islet culture system enabling the study of sex differences. I developed a novel long term culture system using human pancreatic slices establishing this as a model to study islet biology. Furthermore, to decipher transcriptional sex differences across islets, I have performed an multiomic study utilizing scRNAseq, snATACseq and dynamic hormone secretion. Together this work has established the foundation for my ongoing work on identifying novel regulators of islet function across sex. I have successfully set up the pancreatic slice system and performed multi-pronged screening interrogating novel genes in the context of sex differences. These studies combined network analysis of differentially expressed genes across the transcriptome and gene accessibility across the genome in islet cells, to discover differences across sex. This data reveals two important aspects on sex differences in islets 1) in a hormone free environment sex differences are restricted to sex chromosome genes, 2) female islet cells suppress their mitochondrial electron transport chain genes in T2D preventing oxidative stress. In Aim 1.1, I hypothesize that sex differences in β-cell function and resilience during T2D result from a combination of sex hormone effects observed only within the in vivo environment, and cell autonomous sex chromosome effects, moreover sex hormone effects are driven by the action of sex steroid estrogen receptor (ER)α. I intend to answer this by answering two questions utilizing the four-core mouse model 1) does ERα agonist action rely on sex chromosome complement? and 2) how the molecular landscape of ERα signaling drive resilience to metabolic stress in islets. In Aim 1.2, I propose to study if androgen receptor (AR) signaling has a similar effect to that of ERα in promoting a resilient molecular landscape in female islet cells. Aim 2 will establish if genes observed in Aim 1.1 drive similar pathways supporting β-cell in human islets. I will perform this by 1) utilizing human pancreatic slices to establish differences in physiological function and 2) use scRNAseq and snATACseq to dissect the molecular architecture of sex differences. These data will open exciting avenues of research by understanding the impact of sex chromosomes and hormones of islet physiology.
