Abstract Background Sarcopenia, or skeletal muscle loss, is a common and clinically significant complication of chronic obstructive pulmonary disease (COPD), contributing to frailty, disability, and increased mortality. With advancing disease, progressive airflow limitation leads to prolonged intermittent hypoxia (PIH) in skeletal muscle, which promotes metabolic stress and impaired protein synthesis. We hypothesized that integrated multi-omics and network analyses of in vitro and in vivo models exposed to PIH would reveal the key molecular processes that drive PIH-induced sarcopenia. Design Differentiated murine C2C12 myotubes were exposed for three days to normoxia, PIH (8 h 1% O2/16 h 21% O2), or chronic hypoxia (CH; 24 h 1% O2). Male wild-type C57BL/6 mice (n = 7/group, 10 weeks old) were exposed for three weeks to normoxia, PIH (12 h 10% O2/12 h 21% O2), or CH (24 h 10% O2). RNA sequencing, quantitative proteomics, and untargeted metabolomics were performed on both C2C12 cells and murine skeletal muscle using standard pipelines. Multi-omic integration was conducted using Sparse Multiple Canonical Correlation Network analysis (SmCCNet) was performed to identify vertical (across omic layers) and horizontal (across models) connected molecular networks. Pathway enrichment was performed with G:Profiler, and selected results were validated experimentally. Results Integration of in vitro transcriptomic, proteomic, and metabolomic datasets revealed enrichment of molecules known to undergo O-GlcNAc post-translational modification or regulation by the hexosamine biosynthesis pathway (HBP), which generates the O-GlcNAc precursor UDP-GlcNAc. These included Pgd (pentose phosphate pathway enzyme) and Samhd1 (DNA repair enzyme). Pathways related to stress response, regulation of catabolic processes, and UDP-glucuronate formation (a cofactor for hyaluronan synthesis) were significantly enriched. Integration of in vivo murine muscle data identified hypoxia-responsive molecules such as Tgfα (an HBP-dependent transcriptional target), as well as O-GlcNAc-modified enzymes including Snrpd2, Rps3a1, and Hmgcs2. Pathway enrichment implicated demyelination and bacterial-invasion signaling, suggesting activation of cellular stress and immune pathways in PIH-exposed muscle. Experimental validation confirmed increased global O-GlcNAc modification of proteins under PIH, while CRISPR-Cas9 knockout of Gfat (the rate-limiting enzyme from the HBP) restored protein synthesis under PIH in vitro. Conclusion Integrated multi-omic and network analyses identify activation of the hexosamine biosynthesis and O-GlcNAc modification pathways as central features of PIH-induced skeletal muscle remodeling. These findings provide mechanistic insight into the molecular basis of sarcopenia in COPD and highlight the HBP-O-GlcNAc axis as a potential therapeutic target to preserve muscle health in chronic hypoxic conditions. This abstract is funded by: K08 HL16834801A1
Attaway et al. (Fri,) studied this question.