Sex-specific differences in cardiac transcriptome under time-restricted feeding

Introduction: Restricted feeding influences daily rhythms of metabolism and gene expression in the heart. Biological sex plays an important role in cardiac physiology and the heart’s response to disease development. We examined the molecular architecture of the heart in male and female mice under restricted feeding conditions. Hypothesis: Time-restricted feeding to the light cycle differentially impacts average cardiac mRNA transcript levels in male and female mouse hearts measured across the 24-hour cycle. Methods: Wild-type 129S6 male and female mice were maintained under 12h:12h light-dark cycles. Mice underwent either ad libitum feeding (ALF) or light-cycle restricted feeding (LRF, zeitgeber time or ZT2-9). After two weeks of LRF, ventricular tissue was collected at four time points (ZT1, ZT7, ZT13, ZT19) to measure the 24-hour average in mRNA transcript expression. Oxford Nanopore long-read RNA sequencing was used to capture full-length transcripts. Gene expression was normalized using DESeq2, and differential expression analysis was performed applying thresholds of absolute fold change >1.5 and p< 0.01. Gene Ontology biological pathway enrichment analysis was performed using clusterProfiler with Benjamini-Hochberg multiple testing correction, with a significance threshold of p-adjusted < 0.05. Results: We detected 19,885 unique genes in all samples. Sex-specific differences in ALF included 7,764 (39%) differentially expressed genes (DEGs) (p< 0.01, |FC| >1.5). Female-enriched mRNA transcript pathways included regulatory processes and signaling cascades, whereas male-enriched pathways included mitochondrial function, translation, and energy metabolism. Notable sex-specific changes in ALF were observed in cardiac transcription factors (Gata4, Nkx2, and Mef2a). Under ALF, female-enriched genes included Epo (erythropoietin) and Pgls (pentose phosphate pathway), while male-enriched genes included Eno3 (glycolysis) and Rpl4 (translation). Sex-specific differences in LRF included 7,784 (39%) DEGs (p< 0.01, |FC| >1.5). GO enrichment pathway differences were largely similar across ALF and LRF (regulatory signaling for female and energy production, translation, and structural maintenance for male), but LRF uniquely enriched negative regulation of protein modification process for female hearts and contractile muscle fiber pathway for male hearts. Within sex, LRF modified the average gene expression for only 36 (0.16%) and 38 (0.18%) of detected genes in female and male hearts, respectively. Under LRF, females upregulated Plcd3 (cellular signaling) and Upf3a (mRNA surveillance), while males upregulated Mhrt (cardiac lncRNA) and Nfkbia (stress signaling). The hearts of both sexes upregulated RGCC, a cell-cycle regulatory gene responding to complement activation, inflammation, and cellular stress, nearly 2-fold. Conclusion/Summary: There were large sex-specific differences in the 24-hour average cardiac transcriptome in male and female mouse hearts. The differences persisted across feeding conditions. Time-restricted feeding to the light cycle minimally affects the 24-hour average cardiac transcriptome in male and female mouse hearts. Only one gene, RGCC, showed a consistent increase in cardiac expression following LRF in male and female hearts. Funding: National Heart, Lung, and Blood Institute grants R01HL172813 and R01HL153042 to Prof. Brian P. Delisle. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.