Bcl-2–Modifying Factor Induces Renal Proximal Tubular Cell Apoptosis in Diabetic Mice

  1. John S.D. Chan1
  1. 1Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
  2. 2Research Centre, Maisonneuve-Rosemont Hospital, Montreal, Quebec, Canada
  3. 3Pediatric Nephrology Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
  4. 4Nephrology/Internal Medicine, Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
  5. 5Division of Nephrology, Institute of Physiology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
  1. Corresponding author: John S.D. Chan, john.chan{at}umontreal.ca.
  1. G.J.L., N.G., and H.M. contributed equally to this study.

Abstract

This study investigated the mechanisms underlying tubular apoptosis in diabetes by identifying proapoptotic genes that are differentially upregulated by reactive oxygen species in renal proximal tubular cells (RPTCs) in models of diabetes. Total RNAs isolated from renal proximal tubules (RPTs) of 20-week-old heterozygous db/m+, db/db, and db/db catalase (CAT)-transgenic (Tg) mice were used for DNA chip microarray analysis. Real-time quantitative PCR assays, immunohistochemistry, and mice rendered diabetic with streptozotocin were used to validate the proapoptotic gene expression in RPTs. Cultured rat RPTCs were used to confirm the apoptotic activity and regulation of proapoptotic gene expression. Additionally, studies in kidney tissues from patients with and without diabetes were used to confirm enhanced proapoptotic gene expression in RPTs. Bcl-2–modifying factor (Bmf) was differentially upregulated (P < 0.01) in RPTs of db/db mice compared with db/m+ and db/db CAT-Tg mice and in RPTs of streptozotocin-induced diabetic mice in which insulin reversed this finding. In vitro, Bmf cDNA overexpression in rat RPTCs coimmunoprecipated with Bcl-2, enhanced caspase-3 activity, and promoted apoptosis. High glucose (25 mmol/L) induced Bmf mRNA expression in RPTCs, whereas rotenone, catalase, diphenylene iodinium, and apocynin decreased it. Knockdown of Bmf with small interfering RNA reduced high glucose–induced apoptosis in RPTCs. More important, enhanced Bmf expression was detected in RPTs of kidneys from patients with diabetes. These data demonstrate differential upregulation of Bmf in diabetic RPTs and suggest a potential role for Bmf in regulating RPTC apoptosis and tubular atrophy in diabetes.

Footnotes

  • Received February 5, 2011.
  • Accepted October 26, 2011.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

| Table of Contents

This Article

  1. Diabetes vol. 61 no. 2 474-484
  1. Supplementary Data
  2. All Versions of this Article:
    1. db11-0141v1
    2. 61/2/474 most recent