RNA-binding protein hnRNPK: a multifunctional regulator of skeletal muscle biology and disease.

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is a highly conserved, multifunctional DNA/RNA-binding protein that regulates gene expression at both transcriptional and post-transcriptional levels. In skeletal muscle, hnRNPK is essential for development, regeneration, and homeostasis, influencing satellite cell activation, myoblast proliferation and differentiation, and myofiber maturation. Its dysregulation is linked to muscle atrophy, degenerative diseases, and impaired regeneration. This review summarizes current knowledge of hnRNPK's molecular structure, subcellular localization and dynamics, and interactions with nucleic acids and proteins. We highlight its roles in myogenic differentiation, gene expression control, signaling pathway cross-talk, and skeletal muscle development. We also discuss the potential of hnRNPK as a diagnostic biomarker and therapeutic target in muscle disorders, and outline key directions for future research to resolve outstanding questions about its complex regulatory functions. Together, these insights provide a framework for advancing muscle biology and improving the management of muscle-related diseases.