Clathrin‐dependent endocytosis predominantly mediates protein absorption by fat body from the hemolymph in Bombyx mori

Abstract

During insect larval-pupal metamorphosis, proteins in the hemolymph are absorbed by the fat body for the maintenance of intracellular homeostasis; however, the type of proteins and how these proteins are internalized into the fat body are unclear. In Bombyx mori, the developmental profiles of total proteins in the hemolymph and fat body showed that hemolymph-decreased protein bands (55-100 kDa) were in accordance with those protein bands that increased in the fat body. Inhibition of clathrin-dependent endocytosis predominantly blocked the transportation of 55-100 kDa proteins from the hemolymph into the fat body, which was further verified by RNA interference treatment of Bmclathrin. Six hexamerins were shown to comprise ß90% of the total identified proteins in both the hemolymph and fat body by mass spectrum (MS) analysis. In addition, hemolymphspecific proteins were mainly involved in material transportation, while fat body-specific proteins particularly participated in metabolism. In this paper, four hexamerins were found for the first time, and potential proteins absorbed by the fat body from the hemolymph through clathrin-dependent endocytosis were identified. This study sheds light on the protein absorption mechanism during insect metamorphosis.

Clathrin‐dependent endocytosis plays a critical role in larval and pupal development, and female oocyte production in the red flour beetle (Tribolium castaneum)

“…Clathrin-dependent endocytosis is a well-characterized route responsible for the internalization of nutrients, pathogens, antigen, growth factors, and proteins. 32,33 In insects, clathrindependent endocytosis has been shown to be an important pathway for viruses to enter the cells. [34][35][36] During the last few years, clathirn-dependent endocytosis has also been demonstrated as a predominate pathway for cellular uptake of dsRNA in insects.…”

“…Clathrin‐dependent endocytosis is a well‐characterized route responsible for the internalization of nutrients, pathogens, antigen, growth factors, and proteins 32,33 . In insects, clathrin‐dependent endocytosis has been shown to be an important pathway for viruses to enter the cells 34–36 .…”

Bombyx mori can synthesize ascorbic acid through the l‐gulose pathway to varying degrees depending on developmental stage

“…In insects such as the silkworm, the tissues similar to the kidney and liver in vertebrates are the martensian tube and the fat body (Orville Singh et al, 2016; Wang et al, 2020), respectively. The larval martensian tube degenerates and disappears during the pupal metamorphosis period.…”

Transcriptomic analysis reveals recovery strategies in strawberry roots after using a soil amendment in continuous cropping soil

“…Endocytosis is used by cells to internalize molecules and external nutrients, or it mediates the entry of invading pathogens into host cells [29,30]. External materials can be internalized by the clathrindependent endocytosis pathway; subsequently, the external materials are engulfed in an endosome and delivered to the lysosome for degradation [28,31,32]. In addition, cells have evolved protein quality control systems to prevent or delay a myriad of diseases.…”