Regulation of embryonic skeletal muscle satellite cell proliferation by CDK1 expression levels in goats

Skeletal muscle development is a key determinant of growth and meat production traits in ruminants, yet the regulatory mechanisms of embryonic myogenesis in goats remain unclear. Here, weighted gene co-expression network analysis (WGCNA) based on RNA-seq data from 11 developmental stages of longissimus dorsi muscle identified an orange module specifically activated during embryonic days 65–90, which was enriched in cell cycle and DNA replication pathways. Cyclin-dependent kinase 1 ( CDK1 ) was identified as the hub gene with the highest intramodular connectivity. In goat skeletal muscle satellite cells, moderate CDK1 upregulation promoted cell viability and proliferation, whereas excessive expression induced cell cycle arrest and inhibited proliferation. Integrated transcriptomic and proteomic analyses revealed that high CDK1 levels suppressed DNA replication and cell cycle programs and activated checkpoint-associated pathways. These changes are consistent with a feedback response involving replication stress-associated checkpoint signalling, although replication stress itself was not directly measured. These results support a time- and expression level-dependent regulatory model in which CDK1 maintains a balance between myogenic proliferation and checkpoint control. We define embryonic days 65–90 as a critical proliferative window in goat muscle development and identify CDK1 as a key sensitive regulator of myogenesis, providing new insights into ruminant muscle development.