335 - Spatial transcriptomics uncover sex-differences in beta cell transcriptome and epigenetic changes in murine offspring of obese mice.

Kelli A. DeVanna, Indiana University School of Medicine, Indianapolis, IN, United States; Taylor J. Spice, Indiana University School of Medicine, Noblesville, IN, United States; Marzieh Nemati, Indiana University School of Medicine, Indianapolis, IN, United States; Malgorzata M.. Kamocka, Indiana University School of Medicine, Indianapolis, IN, United States; Kok Lim Kua, Indiana University School of Medicine, Indianapolis, IN, United States; Emma Scifres, Indiana University, Indianapolis, IN, United States; Preethi Krishnan, Indiana University School of Medicine, Indianapolis, IN, United States

Background: Children born to obese mothers are at higher risk of developing type 2 diabetes as adults due to islet β cell dysfunction and insulin resistance. We have reported that in a mouse model, male offspring of obese dams developed islet dysfunction and glucose intolerance, while female offspring of obese dams were unaffected. To date, the molecular mechanisms contributing to the sex differences in islet dysfunction in offspring of obese dams are largely understudied.

Objective: We aim to test the hypothesis that exposure to maternal obesity leads to sex-specific transcriptomic changes in β cells.

Design/Methods: We used the GeoMx Digital Spatial Profiling platform to define the transcriptomes of β cells and surrounding acinar tissues in intact pancreata collected from 21-day-old (P21) pups born to chow-fed (Con) or western diet-fed obese dams (MatOb). (n=4/sex/grp) Region of interest (ROI) were selected based on insulin staining (β cells) and morphology (acinar tissue). Oligonucleotide barcodes in selected ROI were UV-photocleaved and sequenced using NextSeq 2000. Differentially expressed genes (DEG) were defined using GeoMx Analysis Suite 2.4.2.2 Linear Mixed Models with Benjamini-Hochberg correction (adjusted p< 0.05). Pathway analyses were performed using gene set enrichment analysis (GSEA) and Ingenuity Pathway Analysis (IPA). Immunofluorescence (IF) staining was performed to assess trimethylation of lysine 27 site on Histone H3 (H3727me3) using 3-5 pancreata/sex/group using P21 and 6-weeks-old offspring.

Results: Compared to same-sex Con, β cells of male MatOb pups had 79 DEG (31 up- and 48 down-), while β cells of female MatOb pups had 190 DEG (147 up- and 43 down-) (FDR < 0.05). Surprisingly, there was no DEG within acinar cells. Compared to same-sex Con, IPA showed positive enrichment in insulin secretion signaling, AMPK signaling, and EIF2 signaling in female MatOb pups β-cells, while these pathways important to β cell health were negatively enriched in male MatOb pups β-cells (corrected p< 0.05). GSEA showed female MatOb pups β-cells also expressed transcriptomes enriching for gene sets related to epigenetics changes suggesting increased trimethylation of lysine 27 on Histone H3 (H3K27me3) in female MatOb. IF staining confirmed higher nuclear H3k27me3 staining in β cells of P21 (46±20% inc vs. Con) and 6-weeks-old female MatOb mice (85±27% inc vs. Con).

Conclusion(s): Exposure to maternal obesity results in sex-specific changes in transcriptomes within offspring β cells that are critical in regulating insulin secretion. Future studies will focus to identify gene regions regulated by H3k27me3