Identification and Functional Analysis of a Key Gene in the CHH Gene Family for Glucose Metabolism in the Pacific White Shrimp Litopenaeus vannamei

The crustacean hyperglycemic hormone (CHH) is a unique multifunctional neuroendocrine hormone superfamily in crustaceans, crucial for maintaining physiological homeostasis and stress adaptation. To explore the role of CHHs in shrimp metabolism and growth, we identified LvCHH Ia, a CHH family member who regulates glucose metabolism in the Pacific white shrimp (Litopenaeus vannamei), through CHH family gene classification, phylogenetic analysis, gene structure analysis, and transcription factor binding site (TFBS) prediction. Subsequently, we cloned two alternative splicing variants of this gene, LvCHH Ia-1 and LvCHH Ia-2, both expressed in the nervous system but with different expression levels, and LvCHH Ia-2 exhibiting a broader tissue distribution. Using interference (RNAi)-mediated gene silencing and recombinant protein injection, we investigated the functional similarities and differences between the two variants. Our results show that both variants affect glucose metabolism by modulating the expression of key enzyme genes involved in gluconeogenesis/glycolysis, such as HK, TPI, PCK1, ALD. Specifically, they likely regulate hemolymph glucose levels via the Wnt and PI3K-AKT signaling pathways, with LvCHH Ia-1 exerting a more sustained effect on glucose metabolism compared to LvCHH Ia-2. Furthermore, LvCHH Ia may also act as a molting inhibitory hormone by suppressing the expression of ecdysone synthesis-related genes, where LvCHH Ia-2 plays a more significant role. These findings deepen our understanding of CHH regulatory mechanisms in crustaceans and provide potential applications for shrimp physiological research and aquaculture.