Kindlin-2 regulates podocyte adhesion and fibronectin matrix deposition through interactions with phosphoinositides and integrins

J Cell Sci. 2011 Mar 15;124(Pt 6):879-91. doi: 10.1242/jcs.076976. Epub 2011 Feb 15.

Abstract

Kindlin-2 is a FERM and PH domain-containing integrin-binding protein that is emerging as an important regulator of integrin activation. How kindlin-2 functions in integrin activation, however, is not known. We report here that kindlin-2 interacts with multiple phosphoinositides, preferentially with phosphatidylinositol 3,4,5-trisphosphate. Although integrin-binding is essential for focal adhesion localization of kindlin-2, phosphoinositide-binding is not required for this process. Using biologically and clinically relevant glomerular podocytes as a model system, we show that integrin activation and dependent processes are tightly regulated by kindlin-2: depletion of kindlin-2 reduced integrin activation, matrix adhesion and fibronectin matrix deposition, whereas overexpression of kindlin-2 promoted these processes. Furthermore, we provide evidence showing that kindlin-2 is involved in phosphoinositide-3-kinase-mediated regulation of podocyte-matrix adhesion and fibronectin matrix deposition. Mechanistically, kindlin-2 promotes integrin activation and integrin-dependent processes through interacting with both integrins and phosphoinositides. TGF-β1, a mediator of progressive glomerular failure, markedly increased the level of kindlin-2 and fibronectin matrix deposition, and the latter process was reversed by depletion of kindlin-2. Our results reveal important functions of kindlin-2 in the regulation of podocyte-matrix adhesion and matrix deposition and shed new light on the mechanism whereby kindlin-2 functions in these processes.

Publication types

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

MeSH terms

  • Cell Adhesion
  • Cell Line
  • Extracellular Matrix / chemistry
  • Extracellular Matrix / genetics
  • Extracellular Matrix / metabolism
  • Fibronectins / genetics
  • Fibronectins / metabolism*
  • Humans
  • Integrin beta1 / genetics
  • Integrin beta1 / metabolism*
  • Integrin beta3 / genetics
  • Integrin beta3 / metabolism*
  • Kidney Glomerulus / cytology
  • Kidney Glomerulus / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Neoplasm Proteins / chemistry
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Phosphatidylinositols / metabolism*
  • Podocytes / chemistry
  • Podocytes / cytology*
  • Podocytes / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Transforming Growth Factor beta1 / metabolism

Substances

  • FERMT3 protein, human
  • Fibronectins
  • Integrin beta1
  • Integrin beta3
  • Membrane Proteins
  • Neoplasm Proteins
  • Phosphatidylinositols
  • Transforming Growth Factor beta1