3118-LB: Molecular Pathways Underlying Sex Differences in ER Stress Response in Human Beta Cells

Introduction and Objective: Sex differences in diabetes risk and progression are well documented, yet the underlying molecular mechanisms remain unclear. Endoplasmic reticulum (ER) stress is central to pancreatic beta cell dysfunction in diabetes. Previously, integrated single-cell RNA-seq meta-analysis revealed heightened ER stress signatures in male human islet cells compared with females. We hypothesized that sex-specific differences in ER stress responses in the beta cells contribute to beta cell dysfunction and increased diabetes susceptibility in males. Methods: Primary human islets from female and male donors were treated with 1 μM thapsigargin (Tg) to induce ER stress. (1) Single-cell RNA-seq was performed at 0, 12, and 48 hours to define sex-specific transcriptional responses. (2) ER stress kinetics were assessed using an XBP1-based fluorescent reporter with live-cell imaging over 48 hours following Tg treatment. (3) Genotyping of Transcriptomes (GoT) at the XBP1 splice site quantified IRE1-XBP1 pathway activity in β cells. Results: Female islets exhibited an earlier, lower ER stress peak and faster recovery compared with males. Differential expression and pseudotime analyses demonstrated increased IRE1-XBP1 pathway activation in male β cells. GoT confirmed higher spliced XBP1 levels and prolonged signaling dynamics in males, consistent with reporter-based measurements. Conclusion: Female β cells display greater resilience to ER stress than males. Sex-specific regulation of the IRE1-XBP1 pathway may contribute to differential diabetes risk and represents a potential target for precision therapeutics. Disclosure M.P. Toledo: None. X. Hu: None. C.J. Mickey: None. P. Sandoval Sanchez: None. Y. Wang: None.