Rapamycin promotes podocyte autophagy and ameliorates renal injury in diabetic mice.
The aim was to explore the effects of rapamycin on autophagy and injury of podocytes in streptozocin (STZ)-induced type 1 diabetic mice, and its role in delaying progression of diabetic nephropathy. In this study, male Balb/c mice were divided into three groups: control (n = 12), STZ-induced diabetic (n = 12), and rapamycin-treated diabetic (DM + Rapa) (n = 12), which received intraperitoneal injection of rapamycin (2 mg/kg/48 h) after induction of DM. Levels of urinary albumin (UA), blood urea nitrogen, serum creatinine, and kidney weight/body weight were measured at week 12. Renal pathologic changes, number of podocytes autophagy, and organelles injury were investigated by PAS staining, transmission electron microscopy, and immunofluorescence staining, respectively. Western blot was performed to determine the expression of LC3 (a podocyte autophagy marker), phosphorylated mammalian target of rapamycin, p-p70S6K, bax, and caspase-3 protein. Podocytes count was evaluated by immunofluorescence staining and Wilms tumor 1 immunohistochemistry, and Western blot of nephrin and podocin. The results indicated that rapamycin could reduce the kidney weight/body weight and UA secretion. It could alleviate podocyte foot process fusion, glomerular basement membrane thickening, and matrix accumulation, and increase the number of autophagosomes, and LC3-expressing podocytes. Down-regulation of bax and caspase-3 protein, and up-regulation of nephrin and podocin protein were observed in the glomeruli of diabetic mice after administration of rapamycin. In conclusion, rapamycin can ameliorate renal injury in diabetic mice by increasing the autophagy activity and inhibition of apoptosis of podocytes.
Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, People's Republic of China.
Tangli
T
Xiao
Xu
X
Guan
Ling
L
Nie
Song
S
Wang
Lei
L
Sun
Ting
T
He
Yunjian
Y
Huang
Jingbo
J
Zhang
Ke
K
Yang
Junping
J
Wang
Jinghong
J
Zhao
D000419:Albuminuria / Q000209:etiology / Q000517:prevention & control; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D015415:Biomarkers / Q000097:blood; D001806:Blood Urea Nitrogen; D053148:Caspase 3 / Q000378:metabolism; D019610:Cytoprotection; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D003928:Diabetic Nephropathies / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008807:Mice, Inbred BALB C; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494827:Bax protein, mouse; D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; C480860:Map1lc3b protein, mouse; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C407223:NPHS2 protein; D051028:bcl-2-Associated X Protein; C113267:nephrin; D038762:Ribosomal Protein S6 Kinases, 70-kDa; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020123:Sirolimus