PKC-delta promotes renal tubular cell apoptosis associated with proteinuria.
Proteinuria may contribute to progressive renal damage by inducing tubulointerstitial inflammation, fibrosis, and tubular cell injury and death, but the mechanisms underlying these pathologic changes remain largely unknown. Here, in a rat kidney proximal tubular cell line (RPTC), albumin induced apoptosis in a time- and dose-dependent manner. Caspase activation accompanied albumin-induced apoptosis, and general caspase inhibitors could suppress this activation. In addition, Bcl-2 transfection inhibited apoptosis and attenuated albumin-induced Bax translocation to mitochondria and cytochrome c release from the organelles, further confirming a role for the intrinsic pathway of apoptosis in albuminuria-associated tubular apoptosis. We observed phosphorylation and activation of PKC-delta early during treatment of RPTC cells with albumin. Rottlerin, a pharmacologic inhibitor of PKC-delta, suppressed albumin-induced Bax translocation, cytochrome c release, and apoptosis. Moreover, a dominant-negative mutant of PKC-delta blocked albumin-induced apoptosis in RPTC cells. In vivo, we observed activated PKC-delta in proteinuric kidneys of streptozotocin-induced diabetic mice and in kidneys after direct albumin overload. Notably, albumin overload induced apoptosis in renal tubules, which was less severe in PKC-delta-knockout mice. Taken together, these results suggest that activation of PKC-delta promotes tubular cell injury and death during albuminuria, broadening our understanding of the pathogenesis of progressive proteinuric kidney diseases.
Li
Xiaoning
X
Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans' Affairs Medical Center, Augusta, Georgia 30912, USA.
Pabla
Navjotsingh
N
Wei
Qingqing
Q
Dong
Guie
G
Messing
Robert O
RO
Wang
Cong-Yi
CY
Dong
Zheng
Z
D000098:Acetophenones / Q000494:pharmacology; D000418:Albumins / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001578:Benzopyrans / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000150:complications; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D011507:Proteinuria / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D013311:Streptozocin; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D000098:Acetophenones; D000418:Albumins; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D013311:Streptozocin; D045304:Cytochromes c; C085746:rottlerin; D051745:Protein Kinase C-delta; D020169:Caspases
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