Cell Biology – Immunology – Pathology
Kidney International (2005) 68, 133–144; doi:10.1111/j.1523-1755.2005.00387.x
ATRA induces podocyte differentiation and alters nephrin and podocin expression in vitro and in vivo
MICHAEL R VAUGHAN, JEFFREY W PIPPIN, SIÂN V GRIFFIN, RON KROFFT, MARGARET FLEET, LEAH HASELEY and STUART J SHANKLAND
Department of Medicine, Division of Nephrology, University of Washington, Seattle, Washington
Correspondence: Stuart J. Shankland, M.D., University of Washington Medical Center, Division of Nephrology, 1959 NE Pacific Street, Box 356521, Room BB1269, Seattle, WA 98195. E-mail: stuartjs@u.washington.edu
Received 27 February 2004; Revised 18 October 2005; Accepted 15 February 2005.
Abstract
ATRA induces podocyte differentiation and alters nephrin and podocin expression in vitro and in vivo.
Background
Podocytes are terminally differentiated and highly specialized epithelial cells. The factors governing podocyte differentiation are poorly understood. We tested the hypothesis that all-trans retinoic acid (ATRA), a vitamin A derivative, induces podocyte differentiation in vitro and in vivo.
Methods
We tested the effects of ATRA on podocytes. Primary rat, primary mouse, and immortalized mouse podocytes were exposed to ATRA (1, 5, 10, 20, 40, 50, 80, 160, and 200 
mol/L) or control (ethanol) for 72 hours. Cell morphology was examined by electron microscopy, the expression of podocyte specific proteins was measured by immunoflourescence and Western blot analysis, cell number and apoptosis were measured by 3-[4,5] dimethylthiazol-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst staining, respectively. To determine if ATRA alters podocyte differentiation in vivo, experimental injury was induced in C57BL6 mice using the antiglomerular antibody. Animals were given either daily intraperitoneal ATRA (16 mg/kg) or vehicle (corn oil). For end points, we measured proteinuria, podocyte-specific protein immunostaining, and proliferation [proliferating cell nuclear antigen (PCNA)] at days 5 and 14 (N = 5/group/time point).
Results
ATRA induced podocyte process formation in vitro, and significantly increased the expression of nephrin and podocin. This coincided with a reduction in proliferation. ATRA also significantly prevented the decrease in staining for synaptopodin, nephrin, and podocin in experimental animals (P < 0.05 vs. control). This was accompanied by reduced proteinuria and decreased podocyte proliferation (P < 0.05 vs. control).
Conclusion
ATRA induces podocyte differentiation in vitro and in vivo and alters the expression of certain podocyte-specific proteins. Further studies are ongoing to delineate the mechanism of this effect.
Keywords:
glomerular epithelial cell, podocyte, ATRA, retinoic acid, vitamin A, nephrin, podocin, differentiation
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Kidney International Original Article
Kidney International Original Article
