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IGF-binding protein-3 modulates TGF-beta/BMP-signaling in glomerular podocytes

Imke Peters1, Irini Tossidou, Johannes Achenbach

  • 1Division of Nephrology, Department of Medicine, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, 30625 Germany, and Division of Pediatric Nephrology, Children's Hospital at Montefiore, Bronx, NY, USA.

Journal of the American Society of Nephrology : JASN
|May 5, 2006
PubMed

Insights

Insulin-like growth factor-binding protein-3 (IGFBP-3) promotes podocyte apoptosis by altering TGF-beta1 signaling pathways. This discovery sheds light on the IGF/IGFBP axis

Area of Science:

  • Nephrology
  • Molecular Biology
  • Cell Biology

Background:

  • Podocyte apoptosis is a key event in glomerulosclerosis.
  • TGF-beta1 pathway activation drives podocyte apoptosis.
  • CD2AP modulates TGF-beta-induced survival signaling via PI3K/AKT pathway.

Purpose of the Study:

  • To identify novel modulators of apoptosis and survival signaling in glomerular podocytes.
  • To investigate the role of IGF-binding protein-3 (IGFBP-3) in podocyte apoptosis.

Main Methods:

  • Analysis of urinary IGFBP-3 in CD2AP-knockout mice.
  • Detection of IGFBP-3 expression in glomerular cells.
  • In vitro studies on cultured murine podocytes using TGF-beta1 and BMP-7 stimulation.
  • Examination of p38 MAPK and PI3K/AKT signaling pathways.

Main Results:

  • High urinary IGFBP-3 levels in diseased CD2AP-/- mice.
  • IGFBP-3 induces podocyte apoptosis and alters actin cytoskeleton.
  • IGFBP-3 enhances TGF-beta1-induced apoptosis by increasing p38 MAPK phosphorylation and decreasing AKT phosphorylation.
  • IGFBP-3 with BMP-7 promotes anti-apoptotic signaling via AKT phosphorylation.

Conclusions:

  • IGFBP-3 is a novel modulator of apoptosis and survival signaling in glomerular podocytes.
  • The IGF/IGFBP axis plays a critical role in podocyte apoptosis by modulating TGF-beta and BMP-7 signaling.
  • IGFBP-3's specific effects depend on the co-stimulatory cytokine, highlighting complex signaling interactions.

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