Hepatopancreatic Vitellogenin Regulation in Marsupenaeus japonicus: Transcriptome Based on Endogenous Variation in Vitellogenin Expression Levels

In penaeids, the major yolk protein precursor vitellogenin is synthesized in both the hepatopancreas and the ovary. While ovarian vitellogenin expression is clearly regulated by hormones from the X-organ/sinus gland in the eyestalk, regulation in the hepatopancreas remains poorly understood. Here, we performed transcriptome profiling stratified by endogenous hepatopancreatic vitellogenin gene (Maj-Vg1) expression levels in immature kuruma prawn Marsupenaeus japonicus. Pathway enrichment analysis identified the insulin, mechanistic target of rapamycin (mTOR), glucagon, and AMP-activated protein kinase (AMPK) pathways as candidate modules associated with the control of hepatopancreatic Maj-Vg1 expression. Analysis of differentially expressed genes identified slit-like (Slit) and calreticulin (Calr) as genes potentially involved in the regulation of Maj-Vg1 expression. In ex vivo hepatopancreas explants, insulin-like peptide 1 from this species induced Maj-Vg1 and was accompanied by the upregulation of lipogenic markers (Max-like protein X (Mlx) and acetyl-CoA carboxylase (Acc)), consistent with vitellogenin’s lipid-transport role. Expression patterns of Calr, tuberous sclerosis complex 1 and 2 (Tsc1 and Tsc2) suggest regulatory inputs beyond insulin signaling, indicating context-dependent regulation. Taken together, these data identify metabolic status as an important contributor to hepatopancreatic Maj-Vg1 expression and define further research targets, including mTOR, AMPK, glucagon, and the Slit/Roundabout axis, for understanding vitellogenesis in penaeids.