Integrative multi-omics analysis unveils the regulatory landscape of diabetic cardiomyopathy: from chromatin...

Diabetic cardiomyopathy (DCM) is a major contributor to heart failure in diabetic patients, characterized by profound metabolic remodeling and diastolic dysfunction. However, the multi-layered epitranscriptomic and post-transcriptional networks involved in this disease remain poorly understood. To address this, we established a type 2 diabetes-associated DCM mouse model using a high-fat diet (HFD) combined with low-dose streptozotocin (STZ) injections. By integrating single-molecule direct RNA sequencing (DRS-seq), chromatin accessibility profiling (ATAC-seq), and conventional bulk RNA-seq, we constructed a comprehensive epigenetic-transcriptional regulatory map of DCM. Using DRS-seq, we identified 21,156 full-length transcripts, including 8,457 (39.97%) novel unannotated isoforms, and observed a systemic 3'-UTR elongation under diabetic stress. Joint ATAC-seq and DRS-seq analysis identified concurrent reductions in promoter chromatin accessibility and transcript abundance for four genes, including Fam210b (mitochondrial iron homeostasis), Cdh22 (intercalated disc adhesion), Fbxo10 (ubiquitin-mediated RAGE degradation), and Cenpx (DNA double-strand break repair), suggesting a potential link between altered chromatin accessibility and transcriptional regulation in DCM. Additionally, DRS-seq revealed extensive alterations in the cardiac epitranscriptome, identifying 1,719 differential m⁶A sites and 3,146 differential m⁵C sites at single-molecule resolution. Among these epitranscriptomic changes, we observed a potential post-transcriptional interplay between m⁶A and alternative polyadenylation (APA). Furthermore, by applying the CIBERSORT algorithm to the DRS-seq dataset, we characterized the cardiac immune microenvironment, revealing distinct pathological remodeling defined by decreased plasma cells and Th1 cells alongside a specific increase in CD4+ memory T-cell infiltration. Pearson correlation analysis showed that, among the candidate genes, only the down-regulated mitochondrial regulator Fam210b exhibited a significant negative correlation with CD4+ memory T-cell infiltration, suggesting a potential molecular association between mitochondrial dysfunction and local adaptive immune changes. Together, our study provides a high-resolution landscape of the native cardiac transcriptome and epitranscriptome, highlighting epigenetic-transcriptional coupling, m⁶A-APA cooperative decay, and Fam210b-associated local immune microenvironment remodeling as potential pathogenic contributor, thus offering candidate therapeutic targets for diabetic heart failure.