Genome-wide identification and characterization of IGF/IGFR/IGFBP gene families in spotted sea bass and their expression profiles in response to environmental stress

Insulin-like growth factor (IGF) signaling pathway constitutes an ancient regulatory network essential for neuroendocrine functions, significantly influencing developmental processes, reproductive activities, and adaptation to environmental challenges. In this study, we detected 3 IGF genes, 3 IGFR genes and 11 IGFBP genes in spotted sea bass genome. The annotation accuracy and evolutionary conservation of identified genes were confirmed through phylogenetic, syntenic and copy number analyses. Molecular basis of gene functions, and protein interaction relationships were investigated by gene structure and protein-protein interaction (PPI) network analyses. Moreover, selective pressure analysis revealed that most genes primarily underwent purifying selection during evolution. Furthermore, RNA-Seq datasets were utilized to analyze tissue expression profiling for IGF/IGFR/IGFBP genes, along with documentation of their environmental stress-responsive transcriptional dynamics in targeted tissues. Our results demonstrated that IGF/IGFR/IGFBP genes were widely expressed in different tissues, with several genes exhibiting high expression levels in specific tissues. Additionally, the stress response mechanisms of IGF signaling system mainly involve IGFs functions regulated by IGFBPs and IGF-independent functions of IGFBPs. Notably, igf1, igf2, igfbp1a, igfbp3b and igfbp4 were pinpointed as key functional genes of environmental challenge adaptation in this species. This investigation provides foundational insights into the IGF/IGFR/IGFBP gene families in spotted sea bass, delivering the first comprehensive genomic resource for these gene families while clarifying their functional contributions to environmental stress adaptation.