Glycated albumin induces superoxide generation in mesangial cells.
OBJECTIVE
Reactive oxygen species are involved in the pathogenesis of diabetic nephropathy. Amadori-modified glycated albumin modulates signaling pathways in mesangial cells that contribute to the development of diabetic nephropathy. However, the effects of glycated albumin on mesangial cell superoxide (O2-) production are unknown. Thus, we examined whether glycated albumin induces mesangial cell O2- generation and whether increased O2- production elicits cell growth.


METHODS
Quiescent human mesangial cells (HMC) were exposed to bovine serum albumin (BSA) or glycated BSA (Gly-BSA) with or without diphenylene iodonium (DPI) or apocynin, inhibitors of NAD(P)H oxidase, GF109203X (GFX), a protein kinase C (PKC) inhibitor.


RESULTS
Gly-BSA increased PKC activity, particularly PKC-alpha and -alpha1, within 15 min of incubation with HMC, which decreased to the control value at 2 h. Gly-BSA incubated with HMC increased O2- production by 2 times vis-á-vis BSA-treated cells. The Gly-BSA-induced increased O2- generation was suppressed by DPI or GFX. Gly-BSA significantly increased mesangial [3H]-leucine incorporation, whereas these processes were abrogated by DPI, apocynin or GFX.


CONCLUSIONS
Gly-BSA induces PKC/NAD(P)H oxidase-dependent O2- production in HMC, which in turn results in cell hypertrophy. Thus, O2- induced by glycated albumin might cause mesangial cell alterations in diabetes participating in the pathophysiology of diabetic nephropathy.
Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
Chong Woo
CW
Yoo
Chi Young
CY
Song
Bong Cho
BC
Kim
Hye Kyoung
HK
Hong
Hyun Soon
HS
Lee
D002478:Cells, Cultured; D003928:Diabetic Nephropathies / Q000209:etiology / Q000378:metabolism; D005920:Glomerular Mesangium / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D017127:Glycation End Products, Advanced; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009861:Onium Compounds / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism / Q000494:pharmacology*; D013481:Superoxides / Q000032:analysis / Q000378:metabolism*; D000093423:Glycated Serum Albumin
D017127:Glycation End Products, Advanced; D007211:Indoles; D008301:Maleimides; D009861:Onium Compounds; D012709:Serum Albumin; D013481:Superoxides; C007517:diphenyleneiodonium; D019255:NADPH Oxidases; D011493:Protein Kinase C; C070515:bisindolylmaleimide I; D000093423:Glycated Serum Albumin