Premium
Autophagy Maturation Controlled by CD38‐Lysosome Signaling in Glomerular Podocytes of Mice
Author(s) -
xiong jing,
Xia Min,
Xu Ming,
Li Xiao-Xue,
Abais Justine,
Boini Krishna,
Li Pin-Lan
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.690.14
Subject(s) - lysosome , autophagy , podocyte , lamp1 , microbiology and biotechnology , bafilomycin , pi3k/akt/mtor pathway , wortmannin , sequestosome 1 , chemistry , biology , signal transduction , endocrinology , biochemistry , kidney , apoptosis , proteinuria , enzyme
Podocytes are well differentiated glomerular epithelial cells, and their structural and functional integrity are mainly maintained by a self‐defense or adaptive mechanism, autophagy. However, it remains unknown how podocyte autophagy is regulated to maintain the integrity of glomerular structure and function. The present study tested whether CD38‐mediated signaling, an important regulatory pathway of lysosome function, plays a critical role in the regulation of podocyte autophagy. Western blot analysis showed that rapamycin stimulation significantly increased the LC3‐II and beclin expression with or without prior treatment of nicotinamide, an inhibitor of CD38 or bafilomycin, a lysosome function inhibitor. Laser flow cytometry demonstrated that treatment of podocytes with nicotinamide enhanced the autophagosome (AP) accumulation (2.34±0.19 vs 1.63±0.21 of control), but decreased the formation of autophagolysosomes (1.12±0.18 vs 1.65±0.14 of control) under rapamycin stimulation. Using CD38 shRNA, we confirmed that CD38 gene silencing had similar effects to those observed by using pharmacological inhibition of CD38 activity or lysosome function, as analyzed both Western blot analysis and cytometry. To explore the possibility that CD38 may control podocyte autophagy through its regulation of lysosome function, we directly investigated the fusion of APs with lysosomes in living podocytes by co‐transfection of GFP‐LC3B and RFP‐Lamp1 expression vectors to express both proteins that were located to APs and lysosome, respectively. It was found that a colocalization of GFP‐LC3B and RFP‐Lamp1 upon stimulation of rapamycin became obvious in transfected podocytes, which could be substantially blocked by nicotinamide, CD38 shRNA, and bafilomycin. In conclusion, CD38 is a critical molecule that controls lysosome function and thereby determine autophagy maturation in podocytes (supported by NIH grants HL‐091464 and DK54927).