RNA splicing isoform alterations in muscle mitochondrial membranes of peripheral artery disease patients

Background Stress-induced metabolic reprogramming is thought to be paralleled by a reorganization of splicing programs, favoring alternative over canonical mRNA isoforms. In peripheral artery disease (PAD), lower extremity muscles are exposed to hypoxia and episodes of ischemia-reperfusion. These conditions may induce cellular stress that triggers metabolic reprogramming. Whether these stress responses are associated with the production of alternatively spliced protein-coding isoforms remains unclear. Methods Differential transcript usage analysis was performed on high-depth RNA sequencing data from gastrocnemius muscle biopsies of 31 participants with PAD and 28 age- and sex-matched non-PAD controls to identify differentially spliced RNA variants. Results A total of 200 splicing isoform variants from 132 genes were differentially expressed between PAD and non-PAD control muscle (p adj < 0.05). Genes exhibiting altered splicing were significantly enriched for gene products associated with the mitochondrial inner membrane (OR = 4.07, p adj = 0.03), including genes encoding respiratory chain complex I subunits/assembly factors (such as NDUFAF4 : p adj = 0.048; NDUFS5 : p adj = 0.0001; NDUFC1 : p adj = 0.003) and mitochondrial transporters (such as SLC25A37 : p adj = 0.017; SLC25A11 : p adj = 0.035; SLC25A39 : p adj = 0.0002). Conclusions These findings suggest that hypoxia and ischemia-reperfusion in PAD are associated with the production of alternative mitochondrial membrane protein–coding RNA isoforms. Whether these transcripts are translated into functional protein isoforms remains unknown. Further longitudinal study is needed to delineate the function and therapeutic relevance of these findings.