Nuclear relocation of the nephrin and CD2AP-binding protein dendrin promotes apoptosis of podocytes

Proc Natl Acad Sci U S A. 2007 Jun 12;104(24):10134-9. doi: 10.1073/pnas.0700917104. Epub 2007 May 30.

Abstract

Kidney podocytes and their slit diaphragms (SDs) form the final barrier to urinary protein loss. There is mounting evidence that SD proteins also participate in intracellular signaling pathways. The SD protein nephrin serves as a component of a signaling complex that directly links podocyte junctional integrity to actin cytoskeletal dynamics. Another SD protein, CD2-associated protein (CD2AP), is an adaptor molecule involved in podocyte homeostasis that can repress proapoptotic TGF-beta signaling in podocytes. Here we show that dendrin, a protein originally identified in telencephalic dendrites, is a constituent of the SD complex, where it directly binds to nephrin and CD2AP. In experimental glomerulonephritis, dendrin relocates from the SD to the nucleus of injured podocytes. High-dose, proapoptotic TGF-beta1 directly promotes the nuclear import of dendrin, and nuclear dendrin enhances both staurosporine- and TGF-beta1-mediated apoptosis. In summary, our results identify dendrin as an SD protein with proapoptotic signaling properties that accumulates in the podocyte nucleus in response to glomerular injury and provides a molecular target to tackle proteinuric kidney diseases. Nuclear relocation of dendrin may provide a mechanism whereby changes in SD integrity could translate into alterations of podocyte survival under pathological conditions.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology*
  • Cell Line
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Fluorescent Antibody Technique, Direct
  • Glomerulonephritis / etiology
  • Glomerulonephritis / pathology
  • Glutathione Transferase / metabolism
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Male
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Membrane Proteins / physiology*
  • Membrane Proteins / ultrastructure
  • Mice
  • Mice, Inbred Strains
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Nerve Tissue Proteins / physiology*
  • Nerve Tissue Proteins / ultrastructure
  • Podocytes / physiology*
  • Podocytes / ultrastructure
  • Recombinant Fusion Proteins / metabolism

Substances

  • Membrane Proteins
  • Nerve Tissue Proteins
  • Recombinant Fusion Proteins
  • dendrin
  • nephrin
  • Green Fluorescent Proteins
  • Glutathione Transferase