Hormones – Cytokines – Signaling
Kidney International (2001) 59, 1706–1716; doi:10.1046/j.1523-1755.2001.0590051706.x
Glucocorticoids stimulate p21CIP1 in mesangial cells and in anti-GBM glomerulonephritis
Yoshio Terada, Tomokazu Okado, Seiji Inoshita, Satoko Hanada, Michio Kuwahara, Sei Sasaki, Tadashi Yamamoto and Fumiaki Marumo
Second Department of Internal Medicine, Tokyo Medical and Dental University, Tokyo, and Department of Pathology, Institute of Nephrology, Niigata University School of Medicine, Niigata, Japan
Correspondence: Yoshio Terada, M.D., Second Department of Internal Medicine, Tokyo Medical and Dental University, 5-45, Yushima 1-chome, Bunkyo-ku, Tokyo 113-8519, Japan. E-mail: yterada.kid@tmd.ac.jp
Received 23 August 2000; Revised 22 November 2000; Accepted 29 November 2000.
Abstract
Glucocorticoids stimulate p21CIP1 in mesangial cells and in anti-GBM glomerulonephritis.
Background
Glucocorticoids are widely used for the treatment of glomerulonephritis, but the mechanism of cell cycle inhibition by glucocorticoids is poorly understood at a molecular level.
Methods
The effects of dexamethasone on cell cycle progression were examined in rat mesangial cells. To investigate the mechanisms of cell cycle inhibition by dexamethasone, we transfected the -2.3 kb p21CIP1 promoter-CAT construct to mesangial cells using an electroporation method. We also examined whether glucocorticoids stimulate the expression of p21CIP1 and inhibit cell proliferation in glomeruli of anti-glomerular basement membrane (GBM) glomerulonephritis in rats.
Results
Dexamethasone inhibited 3H-thymidine uptake and the percentages of S and G2/M phases in rat mesangial cells. Dexamethasone stimulated CAT activity of the p21CIP1 promoter 4.5-fold. Deletion analysis of the p21CIP1 promoter revealed that the glucocorticoid-responsive region (GRE) is present between -1.4 and -1.1 kb upstream of the transcription initiation site. Dexamethasone inducibility of p21CIP1 promoter activity requires the presence of the C/EBP
DNA binding site in the GRE of the p21CIP1 promoter and C/EBP protein. Intravenous injection of anti-GBM antibody caused mesangial proliferation, crescent formation, and proteinuria in rats. Ten days of administration of prednisolone (1 mg/kg/day) reduced proteinuria and inhibited mesangial cell proliferation and crescent formation. The glomerular-sieving method revealed that prednisolone increased p21CIP1 expression in glomeruli.
Conclusion
These data suggest that the cell cycle arrest of mesangial cells is mediated by a functional link between the glucocorticoid receptor and the transcriptional control of p21CIP1 not only in vitro but also in vivo. Our observations provide new insights into the molecular mechanisms of glucocorticoid action in glomerulonephritis.
Keywords:
dexamethasone, cell cycle, mesangial proliferative glomerulonephritis, kinase inhibitory protein family, cyclin-dependent kinase
