A PDGF/VEGF homologue provides new insights into the nucleus grafting operation and immune response in the pearl oyster Pinctada fucata

The involvement of VEGF and VEGFR in bacterial recognition and regulation of antimicrobial peptides in Eriocheir sinensis

Vascular endothelial growth factor (VEGF) and VEGF reporter (VEGFR) are essential molecules in VEGF signalling pathway. Although the functions of VEGF and VEGFR have been well reported in vertebrates, their functions are still poorly understood in invertebrates. In this study, the open reading frame sequences of EsVEGF1 and EsVEGFR4 were cloned from Eriocheir sinensis, and their corresponding proteins shared typical structure characteristics with their counterparts in other species. EsVEGF1 were predominantly expressed in hepatopancreas and muscle while EsVEGFR4 mainly expressed in hemocytes and intestine. The expression levels of EsVEGF1 in hemocytes were rapidly induced by Staphylococcus aureus and Vibrio parahaemolyticus, and it also increased rapidly in hepatopancreas after being challenged with V. parahaemolyticus. The expression levels of EsVEGFR4 only increased in hepatopancreas of crabs injected with S. aureus. The extracellular immunoglobulin domain of EsVEGFR4 could bind with Gram-negative and Gram-positive bacteria as well as lipopolysaccharide and peptidoglycan. EsVEGF1 could act as the ligand for EsVEGFR4 and Toll-like receptor and regulate the expression of crustins and lysozyme with a tissue-specific manner, while have no regulatory function on that of anti-lipopolysaccharide factors. This study will provide new insights into the immune defense mechanisms mediated by VEGF and VEGFR in crustaceans.

Regulation of IL-17 by lncRNA of IRF-2 in the pearl oyster

Long noncoding RNAs (lncRNAs), once thought to be nonfunctional, have recently been shown to participate in the multilevel regulation of transcriptional, posttranscriptional and epigenetic modifications and to play important roles in various biological processes, including immune responses. However, the expression and roles of lncRNAs in invertebrates, especially nonmodel organisms, remain poorly understood. In this study, by comparing a transcriptome to the PfIRF-2 genomic structure, we identified lncIRF-2 in the PfIRF-2 genomic intron. The results of the RNA interference (RNAi) and the nucleus grafting experiments indicated that PfIRF-2 might have a negative regulatory effect on lncIRF-2, and PfIRF-2 and lncIRF-2 may have a positive regulatory effect on PfIL-17. Additionally, lncIRF-2, PfIRF-2 and PfIL-17 were involved in responses to the nucleus graft. These results will enhance the knowledge of lncIRF-2, IRF-2, and IL-17 functions in both pearl oysters and other invertebrates.