Smad2-dependent downregulation of miR-30 is required for TGF-β-induced apoptosis in podocytes

PLoS One. 2013 Sep 26;8(9):e75572. doi: 10.1371/journal.pone.0075572. eCollection 2013.

Abstract

Transforming growth factors beta (TGF-β) are multi-functional cytokines capable of inducing apoptosis in epithelial cells, including glomerular podocytes. We and others have previously shown that podocyte-selective genetic deletion of the microRNA (miR)-processing enzyme, Dicer, caused glomerulosclerosis that was associated with podocyte apoptosis, and the miR-30 family was implicated in the process. Here, we report that apoptosis-associated genes were highly enriched among the predicted targets of miR-30 when compared with randomly selected miRs (26% vs. 4.5 ± 2.1%) or with the known TGF-β-regulated miR-192 (6%), miR-216a (5.1%), and miR-217 (0%). miR-30 family members were abundantly expressed in podocytes in normal mice but were downregulated in albumin/TGF-β transgenic mice with podocyte apoptosis and glomerulosclerosis. In vitro, TGF-β downregulated miR-30s in wildtype and Smad3-deficient, but not Smad2- or Smad2/Smad3-deficient, podocytes. The TGF-β-induced activation of caspase 3 and an increase in TUNEL-positive nuclei were significantly inhibited by the lentivirus-mediated overexpression of miR-30d, but not by a scrambled control miR, in podocytes. TGF-β stimulated the phosphorylation of pro-apoptotic p53 in podocytes with lentiviral expression of a scrambled miR, but not in podocytes expressing miR-30d. In contrast, miR-30d had no effect on the phosphorylation of pro-apoptotic p38 MAP kinase induced by TGF-β. Thus, we report that Smad2-dependent inhibition of miR-30s in podocytes is required for the activation of p53 and the induction of apoptosis by TGF-β. These results demonstrate a novel functional role for miR-30 in podocyte survival and indicate that the loss of miR-30 survival signaling is a novel and specific mechanism of TGF-β-induced podocyte apoptosis during glomerulosclerosis. We propose the therapeutic replacement of miR-30 as a novel strategy to prevent the podocyte apoptosis that is characteristic of progressive glomerular diseases.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / genetics*
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cell Line
  • Down-Regulation / genetics*
  • Humans
  • In Situ Nick-End Labeling
  • Mice
  • Mice, Transgenic
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism*
  • Podocytes / metabolism*
  • Signal Transduction / genetics
  • Smad2 Protein / genetics*
  • Smad2 Protein / metabolism
  • Transforming Growth Factor beta / genetics*
  • Transforming Growth Factor beta / metabolism
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • MicroRNAs
  • Mirn30d microRNA, mouse
  • Smad2 Protein
  • Smad2 protein, mouse
  • Transforming Growth Factor beta
  • Tumor Suppressor Protein p53
  • p38 Mitogen-Activated Protein Kinases
  • Caspase 3