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- Title
Polyol pathway mediates high glucose-induced collagen synthesis in proximal tubule.
- Authors
Bleyer, Anthony J.; Fumo, Peter; Snipes, Edward R.; Goldfarb, Stanley; Simmons, David A.; Ziyadeh, Fuad N.
- Abstract
The polyol pathway in diabetes is activated in tissues that are not dependent on insulin for glucose uptake. To examine the role of the polyol pathway in renal extracellular matrix accumulation, we incubated murine proximal tubule cells in either normal or high glucose concentration in the presence or absence of the aldose reductase inhibitor sorbinil. Raising medium glucose from 100 to 450 mg/dl for 72 hours increased cell sorbitol levels sevenfold. Addition of 0.4 mM sorbinil reduced sorbitol content to virtually undetectable levels as measured by gas chromatography. Sorbinil (0.1 to 0.2 mM) also reduced the secretion of collagens types IV and I in the high glucose concentration after 48 to 72 hours but had no appreciable effect in the normal glucose concentration. Concordantly. 0.1 mM sorbinil inhibited the high glucose-induced stimulation of α(IV) and α2(I) mRNA levels without affecting levels in normal glucose concentration. To study the role of transcriptional activation of collagen genes, we transfected proximal tubule cells with a chloramphenicol acetyltransferase (CAT) reporter gene linked to the promoter and regulatory elements of α1(IV) gene. CAT activity increased several-fold in Ihe cells grown in the high versus normal glucose concentration; this transcriptional activation in culture media containing high glucose concentration was reduced by treatment of the cells with 0.1 mM sorbinil. Thus, high ambient glucose activates the polyol pathway in proximal tubule cells, and may mediate the high glucose-induced stimulation of gene expression for collagens types IV and I. For type IV collagen, activation of the polyol pathway may also involve, at least in part, transcriptional activation of cis-acting gene regulatory elements.
- Subjects
BLOOD sugar; KIDNEY tubules; POLYOLS; INSULIN; COLLAGEN
- Publication
Kidney International, 1994, Vol 45, Issue 3, p659
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/ki.1994.88