Identification and functional characterization of IGFBP genes in Leopard Coral Grouper (Plectropomus leopardus): Insights into growth regulation and stress response

The Insulin-like Growth Factor Binding Protein (IGFBP) family genes, which function as carrier proteins in the circulation, are integral to various physiological processes such as growth, metabolism, reproduction, and stress responses. However, the systematic identification, characterization, and functional analysis of igfbp family genes in teleosts remain to be explored. In this study, we identified and characterized a total of 11 IGFBP family members in the Leopard Coral Grouper (Plectropomus leopardus). Expression analysis revealed that igfbp genes exhibit tissue-specific expression patterns in adult P. leopardus. Notably, certain igfbp genes were differentially expressed in growth-related tissues in fast-growing versus slow-growing individuals, suggesting their potential role in growth regulation. Specifically, the expression of igfbp2a and igfbp2b in the liver was further validated using FISH. Furthermore, knockdown of igfbp2b expressed specifically in the liver resulted in the promotion of muscle development and increased expressions related to muscle cell development. Additionally, several igfbp genes were dynamically involved in the response to acute hypothermia in the brain, gills, kidneys, and liver. These findings offer a comprehensive understanding of the characteristics and functions of igfbp family genes in P. leopardus, providing a solid foundation for further investigation into the functional mechanisms of igfbp genes in teleosts.