Role of protein kinase C-angiotensin II pathway for extracellular matrix production in cultured human mesangial cells exposed to high glucose levels.
The intrarenal renin-angiotensin system has been implicated in the pathogenesis of diabetic nephropathy. This study investigates the mechanisms for glucose-induced increase in angiotensin II (AII) production by human mesangial cells (MCs) in relation to protein kinase C (PKC). We also examine whether locally produced AII mediates extracellular matrix protein production in high-glucose conditions. Human MCs were cultured in 5 or 33 mmol/l glucose for 8 days, and were incubated with or without 5 mmol/l GFX, a PKC inhibitor, 0.1 micromol/l candesartan cilexetil (CC), a specific type 1 AII receptor antagonist, for another 24 h. In addition, MCs grown in 5 mmol/l glucose were incubated with 0.1 micromol/l phorbol-12,13-dibutyrate (PDBu) for 24 h. AII, TGF-beta1, fibronectin and type IV collagen in the culture media were measured by ELISA. The amount of AII secreted from MCs exposed to high-glucose levels was significantly greater (P<0.01) than that in normal glucose levels. The increase in AII production was completely prevented by GFX. The addition of PDBu mimicked the effect of glucose on AII production. The glucose-induced increases in the production of TGF-beta1, fibronectin and type IV collagen were partially, but significantly restored (P<0.01) by CC, while GFX totally abolished these effects of glucose. These results suggest that elevated glucose levels stimulate AII production via mechanisms dependent on glucose-induced PKC activation in human MCs, and that locally produced AII partly mediates the increase in mesangial matrix synthesis in high-glucose conditions.
Ikehara
Kayoko
K
Second Department of Internal Medicine, Toho University School of Medicine, Toho University, 6-11-1 Ohmorinishi, Ohtaku, Tokyo 143-8541, Japan. kayoko-n@nifty.com
Tada
Hisaya
H
Kuboki
Koji
K
Inokuchi
Toshiki
T
D000804:Angiotensin II / Q000378:metabolism*; D057911:Angiotensin Receptor Antagonists; D001562:Benzimidazoles / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D024141:Collagen Type IV / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005109:Extracellular Matrix / Q000378:metabolism*; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013777:Tetrazoles; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D024141:Collagen Type IV; D003470:Culture Media; D007211:Indoles; D008301:Maleimides; C508960:TGFB1 protein, human; D013777:Tetrazoles; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D005947:Glucose; C088060:bisindolylmaleimide; C077793:candesartan cilexetil