Bcl-2 protects tubular epithelial cells from ischemia/reperfusion injury by dual mechanisms

Transplant Proc. 2009 Jan-Feb;41(1):52-4. doi: 10.1016/j.transproceed.2008.10.026.

Abstract

Ischemia/reperfusion (I/R) injury, which induces extensive loss of tubular epithelial cells, is associated with delayed graft function following kidney transplantation. Recent reports have suggested that cell death by I/R injury occurs by autophagy, a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins, as well as by apoptosis. Recently, we demonstrated that overexpression of the anti-apoptotic factor, Bcl-2, inhibited tubular apoptosis and subsequent tubulointerstitial damage after I/R injury. Autophagy is also observed in cells undergoing cell death in several diseases. Therefore, we hypothesized that increased Bcl-2 protein may protect tubular epithelial cells by suppressing autophagy and inhibiting apoptosis. In the present study, a transgenic mouse model (LC3-GFP TG) in which autophagosomes are labeled with LC3-GFP and Bcl-2/LC3-GFP double transgenic mice (Bcl-2/LC3-GFP TG) were used to examine the effect of Bcl-2 on I/R-induced autophagy. I/R injury, which is associated with marked disruption of normal tubular morphology, promoted the formation of LC3-GFP dots, representing extensively induced autophagosomes. On electron microscopy, the autophagosomes contained mitochondria in I/R-injured tubular epithelial cells. In contrast, Bcl-2 augmentation suppressed the formation of autophagosomes and there was less tubular damage. In conclusion, Bcl-2 augmentation protected renal tubular epithelial cells from I/R injury by suppressing autophagosomal degradation and inhibiting tubular apoptosis.

MeSH terms

  • Animals
  • Autophagy / drug effects
  • Epithelial Cells / drug effects
  • Epithelial Cells / pathology
  • Epithelial Cells / physiology
  • Genes, Reporter
  • Genes, bcl-2
  • Humans
  • Mice
  • Mice, Transgenic
  • Proto-Oncogene Proteins c-bcl-2 / therapeutic use
  • Pyruvate Kinase / genetics
  • Rats
  • Reperfusion Injury / pathology
  • Reperfusion Injury / prevention & control*

Substances

  • Proto-Oncogene Proteins c-bcl-2
  • Pyruvate Kinase