CD38 经TFEB 介导促进溶酶体再生而 调节巨噬细胞胆固醇外流.

AIM: To explore the effects of CD38 on lysosome reformation and cholesterol efflux in macrophages. METHODS: Bone marrow-derived macrophages from low-density lipoprotein （LDL） receptor knockout （LDLr-/-） mice were cultured as cell model. Live cell imaging system was applied to evaluate the effect of nicotinic acid adenine dinucleotide phosphate （NAADP） on lysosome number. ELISA was conducted to measure NAADP level in macrophages. After the cells were treated with nicotinic acid （NA）, RT-qPCR was conducted to detect CD38 mRNA expression, and Western blot was conducted to observe CD38 protein expression and phosphorylated transcription factor EB（TFEB） level. Laser scanning confocal microscopy was applied to evaluate the influence of CD38/NAADP signaling on lysosome number and cholesterol egression. RESULTS: NAADP remarkably increased lysosome number （P<0. 05）, and this effect was significantly inhibited by NAADP antagonist NED-19, Ca2+ chelator BAPTA, and calcineurin inhibitor CsA （P<0. 05）. CD38 markedly enhanced NAADP synthesis in macrophages （P<0. 05）. NAADP synthetic substrate NA prominently elevated the expression of CD38 mRNA and protein （P<0. 05）. NA significantly decreased the phosphorylated TFEB level; this effect was also attenuated by NED-19, BAPTA and CsA （P<0. 05）. Disrupting CD38/NAADP signaling pathway markedly inhibited NA-induced enhancement of lysosome number, lysosomal free cholesterol and cytosol cholesterol ester efflux in macrophages （P<0. 05）. NA-induced enhancement of lysosome number, lysosomal free cholesterol and cytosol cholesterol ester efflux abolished in LDLr/CD38 DKO macrophages （P<0. 05）, whereas these effects induced by NA were recovered after CD38 gene rescue. CONCLUSION: CD38 triggers lysosome reformation via TFEB and consequently promotes the efflux of lysosomal free cholesterol and cytosol cholesterol ester. [ABSTRACT FROM AUTHOR]