Identification and characterization of a novel type (Insulin-type) of insulin-like peptide involved in glucose metabolism and growth in Pacific white shrimp Litopenaeus vannamei

Insulin-like peptides (ILPs) are a family of highly conserved peptide hormones that play fundamental regulatory roles in growth, metabolism, and reproduction across metazoans. Although ILPs have been extensively studied in vertebrates and insects, their characterization in crustaceans, particularly their specific roles in regulating shrimp growth and glucose homeostasis, remain largely unknown. In this study, we report the identification and functional characterization of a novel Insulin-type ILP gene, designated LvIns, from the Pacific white shrimp (Litopenaeus vannamei). The full-length LvIns cDNA is 676 bp and sequence analysis indicated that LvIns possesses the typical conserved sequences and structural features of ILPs. Tissue expression profiling demonstrated that LvIns is mainly expressed in female reproductive tissues and nerve tissue. In vivo and in vitro experiments involving glucose treatment and exogenous insulin treatment confirmed that LvIns participates in the regulation of glucose metabolism in shrimp. Furthermore, RNA interference experiments (including long-term and short-term interference) demonstrated that knockdown of LvIns expression significantly reduced the growth rate of shrimp and decreased serum glucose clearance efficiency. Further research indicated that that LvIns may influence shrimp growth by regulating the downstream PI3K/AKT signaling pathways, thereby modulating key glucose metabolic processes such as glycolysis and gluconeogenesis. This study provides a comprehensive characterization of an Insulin-type ILP in a crustacean species, elucidating its crucial role in regulating growth and glucose metabolism.