Comparative proteomic analysis of silkworm fat body after knocking out fibroin heavy chain gene: a novel insight into cross-talk between tissues.

Cross-talk between tissues plays key roles in development of organisms; however, there are few researches on cross-talk between tissues in insects. Our previous studies showed that the pupal body weight was elevated after knocking out the fibroin heavy chain gene (BmFib-H), whereas the gene specifically expressed in silk glands of silkworm. Hence, the mutant is a good material for studying the cross-talk between tissues. It is considered that the fat body of silkworm during larval stage is used to store nutrients for pupal development. Herein, comparative proteomic of fat body on the 5th day of fifth instar was performed between BmFib-H gene knock-out Bombyx mori line (FGKO) and its wide-type Dazao. These results revealed that a single gene knock-out in silk gland triggered large-scale metabolic pathways changes in fat body. The levels of proteins involved in glycolysis/gluconeogenesis, pentose phosphate pathway, and glycine-serine biosynthetic pathway were down-regulated in the FGKO fat body. In contrast, the abundances of many proteins participating in protein synthesis, including ribosomal proteins, eukaryotic translation initiation factor, and elongation factor, were up-regulated. Moreover, the concentrations of glycogen and proteins in the FGKO fat body were greatly increased. These findings provided a novel insight into the cross-talk between silk gland and fat body in silkworm, and the presence of cross-talk between silk gland and fat body could regulate the redistribution of nutrients in the FGKO fat body leading to the increase of the pupal weight.