Comparative genomic and evolutionary analysis of the heat shock protein gene family in the chicken genome

This study provides a detailed genomic and evolutionary analysis of the heat shock protein (HSP) gene family in the chicken (<i>Gallus gallus</i>), identifying 64 HSP genes. The HSP40 (DNAJ) subfamily was the largest, with 39 members, followed by HSP70, HSP90, and smaller subfamilies. Phylogenetic and structural analyses indicated intricate evolutionary dynamics, encompassing both ancient and recent duplication events. The Ka/Ks ratio suggests that purifying selection is the dominant force, although significant segmental duplications (e.g. DNAJC28/DNAJC30) exhibit evidence of positive selection. Analysis of the protein-protein interaction network identified HSPA8, HSPA9, and HSP90B1 as central hubs. Functional enrichment revealed significant clusters associated with chaperone-mediated protein folding, protein complex assembly, and a novel cluster related to toxin transport. Expression profiling by RT-qPCR revealed notable tissue-specificity, with HSP90 and HSP40 exhibiting the highest upregulation (fold change > 3) in leg muscle relative to liver, highlighting their involvement in musculoskeletal stress adaptation. The findings establish a foundational resource for understanding the molecular mechanisms of stress resilience in poultry, highlighting specific gene families and functional modules as potential targets for enhancing thermotolerance and productivity.