Transient receptor potential melastatin 2 regulates autophagosome-lysosome fusion in macrophages and protect endoxemia (TUM6P.972)

Abstract

Abstract Background: Disruption of autophagy in macrophages can lead to inflammation and exacerbation of sepsis. Transient Receptor Potential Melastatin 2 (TRPM2), a nonselective Ca2+-permeable channel, is important for immune function of macrophage. However, whether TRPM2 participates in macrophage autophagy during endoxemia remains unknown. Methods: Endotoxemia was induced via intraperitoneal injection of lipopolysaccharide (LPS) in wild-type and TRPM2-deficiency mice. The mortality was evaluated. The protein levels of Rab7A and LAMP1 were assayed both in peritoneal macrophages from the LPS-challenged mice and LPS-stimulated bone marrow-derived macrophages (BMDMs). mRFP-GFP-Lc3 distribution in BMDMs were also analyzed by confocal microscopy. Results: TRPM2-/- mice challenged with LPS had increased mortality. In peritoneal macrophages from the LPS-challenged TRPM2-deficiency mice and LPS-stimulated TRPM2-deficiency BMDM, the expressions levels of RAB7A and LAMP1 were significantly decreased. Compared with that in wild-type macrophages, most puncta of mRFP-GFP-Lc3 in transfected TRPM2-deficiency cells were yellow (autophagosome) after LPS stimulation. Conclusions: TRPM2 may regulate the fusion of autophagosomes and lysosomes in macrophages after LPS stimulation, which may play important roles during endoxemia.