Activation of cyclin D1-Cdk4 and Cdk4-directed phosphorylation of RB protein in diabetic mesangial hypertrophy

Denis Féliers, Meredith A. Frank, Daniel J. Riley

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


To determine the role of cell-cycle proteins in regulating pathological renal hypertrophy, diabetes was induced in mice expressing a human retinoblastoma (RB) transgene and in wild-type littermates. Whole-kidney and glomerular hypertrophy caused by hyperglycemia was associated with specific G1 phase cell-cycle events: early and sustained increase in expression of cyclin D1 and activation of cyclin D1-cdk4 complexes, but no change in expression of cyclin E or cdk2 activity. Over-expression of RB alone likewise caused hypertrophy and increased only cyclin D1-cdk4 activity; these effects were not further augmented by high glucose. Identical observations were made when isolated mesangial cells conditionally overexpressing RB from a tetracycline-repressible system hypertrophied in response to high glucose. A mitogenic signal in the same cell-culture system, in contrast, transiently and sequentially activated both cyclin D1-cdk4 and cyclin E-cdk2. In vivo and in cultured mesangial cells, high glucose resulted in persistent partial phosphorylation of RB, an event catalyzed specifically by cyclin D1-cdk4. These data indicate that mesangial hypertrophy caused by hyperglycemia in diabetes results in sustained cyclin D1-cdk4-dependent phosphorylation of RB and maintenance of mesangial cells in the early-to-middle G1 phase of the cell cycle.

Original languageEnglish (US)
Pages (from-to)3290-3299
Number of pages10
Issue number11
StatePublished - Nov 1 2002

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism


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