PROMOTION OF MANTLE MINERALIZATION BY AKT MEDIATED IGF2BP IN HYRIOPSIS CUMINGII

Insulin-like growth factor binding protein (IGFBP) plays an important role in various biological processes such as cell growth, apoptosis, bone formation by binding IGF. Additionally, it exerts regulatory functions on shellfish biomineralization. In this study, the IGF2BP gene was cloned for the first time, and its tissue expression profile was constructed after nucleation. Subsequently, human IGF2BP2 was introduced after nucleation, resulting in the suppression of IGF2BP2 (CWI1-2). The effects on the expression of insulin-like growth factor 1 receptor (IGF1R) mediated by AKT signaling pathway and the mineralization related genes chitinase (CHS1) and bone morphogenetic protein 10 (BMP10) were analyzed through tissue section staining. The results showed that the CDS region of IGF2BP gene was 1824 bp, encoding 607 Aa and containing 6 domains, consistent with the typical conserved domain characteristics of IGF2BPs. The relative molecular weight of the protein was 66.69 kDa, with a theoretical isoelectric point of 8.96. The expression level of HcIGF2BP mRNA increased significantly after nucleation, exhibiting a notable trend of initial elevation followed by a gradual decline at each time point after nucleation, peaking at 21d (P<0.05); Exogenous addition of IGF2BP2 can significantly promote the expression of HcIGF2BP, CHS1, and IGF1R at the 14th day (P<0.05), and significantly promoted the expression of AKT1 and BMP10 on the 14th and 28th days (P<0.05). In the inhibition group, the gene expression of HcIGF2BP, CHS1, IGF1R, and AKT1 was significantly suppressed on the 14th day (P<0.05), leading to a significantly inhibition of downstream gene BMP10 expression on the 14th and 28th days (P<0.05). Tissue section observation results showed that exogenous IGF2BP2 promoted cell migration and proliferation on the surface of nucleus nucellus, facilitating cell morphological transformation. The results of this study indicate that IGF2BPs can regulate the expression of key mineralization genes relevant to pearl formation through the AKT signaling pathway, influencing the structure of pearl sac. This study lays a theoretical basis for further exploring the regulatory role of IGF system in the mineralization function of shellfish, and providing molecular basis for accelerating the pearl cultivation process and shortening the cultivation time.