Rab11a-Regulated Exosomes Inhibit Bacterial Infection through the Activation of Antilipopolysaccharide Factors in Crustaceans.

Exosomes, secreted by most cells, are critical antimicrobial immune factors in animals. Recent studies of certain key regulators of vesicular transport, the Rab GTPases, have linked Rab dysfunction to regulation of innate immune signaling. However, the relationship between exosomes and Rab GTPases, resulting in antimicrobial activity in vertebrates and invertebrates during pathogenic infection, has not been addressed. In this study, Rab11a was reported to have a protective effect on the survival rate of mud crabs after s challenge through the stimulation of exosome secretion and modulation of anti-LPS factor (ALF) expression. Furthermore, 14-3-3 was confirmed to be densely packaged in exosomes after s infection, which could recruit the MyD88 and TLR by binding the Toll/IL-1R domain to the plasma membrane, promoting the translocation of Dorsal from the cytoplasm into the nucleus, and thereby regulating ALFs expression in the hemocytes of mud crab in response to the bacterial infection. The findings therefore provide, to our knowledge, a novel mechanism that underlies the cross-talk between Rab11a-regulated exosome formation and ALFs expression in innate immune response in invertebrates, with a crustacean species, mud crab , as a model study.