Albumin overload induces apoptosis in LLC-PK(1) cells.
The degree of albuminuria is a well-known adverse prognostic indicator in human glomerular diseases. However, the mechanisms by which albuminuria by itself contributes to tubulointerstitial injury and progression of renal disease remain unclear. We tested the hypothesis that apoptosis may represent one of the mechanisms by which tubule epithelial cells are damaged after albumin overload in vitro. Cultured LLC-PK(1) proximal tubule cells were incubated with varying concentrations of BSA. This resulted in a dose- and duration-dependent induction of apoptosis, as evidenced by internucleosomal DNA cleavage (DNA laddering and nick-end labeling), externalization of plasma membrane phosphatidylserine (annexin labeling), and characteristic morphological changes (cell shrinkage and nuclear condensation). Albumin overload also resulted in a dose-dependent upregulation of Fas and Fas-associated protein with death domain (FADD), and activation of caspase 8. Incubation with the caspase 8 inhibitor IETD ameliorated the albumin-induced apoptosis. Collectively, our results indicate that albumin overload induces apoptosis of cultured LLC-PK(1) cells, mediated at least in part by the Fas-FADD-caspase 8 pathway.
Erkan
E
E
Pediatric Nephrology, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York 10467, USA.
De Leon
M
M
Devarajan
P
P
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D053200:Fas-Associated Death Domain Protein; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism*; D018374:LLC-PK1 Cells; D009842:Oligopeptides / Q000494:pharmacology; D011507:Proteinuria / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics*; D013552:Swine; D015854:Up-Regulation / Q000187:drug effects; D019014:fas Receptor / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D009842:Oligopeptides; D019014:fas Receptor; C425644:isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; D012710:Serum Albumin, Bovine; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases