Abstract
Methyl farnesoate (MF) serves as an essential regulator of key developmental processes in crustaceans, similar to juvenile hormones (JHs) in insects. However, it is susceptible to degradation in circulation. Despite the detection of proteins binding to MF in crustacean hemolymph for 3 decades, the precise genes encoding these proteins remain unclear. The present study identifies genes in crustaceans containing the juvenile hormone-binding protein (JHBP) domain. Among the 11 JHBPs found in the Pacific white shrimp (Litopenaeus vannamei), XP_027209752.1, which is primarily expressed in the hepatopancreas, emerges as the predominant form. This protein exhibits selective binding to MF rather than to JHs, leading to its designation as a methyl farnesoate-binding protein (MFBP) in crustaceans. Alterations in the amino acid sequence are predicted to induce structural changes that enhance the affinity of MFBP for MF. Endogenous MFBP inhibits molting, consistent with the function of MF. Furthermore, positive regulation of MFBP by MF has been observed in hepatopancreatic primary cells, with similar trends of hepatopancreatic MFBP mRNA and hemolymph MF levels during molting and ovarian development. This study identifies a novel MFBP in crustaceans that, despite being a homolog of insect JHBP, specifically binds MF to regulate molting in penaeid shrimp. These findings may advance our understanding of crustacean endocrine regulation and provide a molecular basis for improving their aquaculture techniques.