Stabilin-1 mediates phosphatidylserine-dependent clearance of cell corpses in alternatively activated macrophages

J Cell Sci. 2009 Sep 15;122(Pt 18):3365-73. doi: 10.1242/jcs.049569.

Abstract

Stabilin-1 is specifically expressed in alternatively activated macrophages. These macrophages participate in anti-inflammatory and healing processes, and display a high phagocytic capacity. In this study, we provide evidence that stabilin-1 is a membrane receptor that performs a crucial function in the clearance of cell corpses. Stabilin-1 is expressed on the cell surface of alternatively activated macrophages and is recruited to the sites of recognition and engulfment of apoptotic bodies, as well as to early phagosomes. Blocking stabilin-1 in macrophages results in defective engulfment of aged red blood cells. Ectopic expression of stabilin-1 induces the binding and engulfment of aged cells in mouse fibroblast L cells. The binding and phagocytosis are dependent on phosphatidylserine (PS), which is well known as an engulfing ligand. Furthermore, using PS-coated beads, we demonstrate that PS directly interacts with stabilin-1 and is sufficient for stabilin-1-mediated phagocytosis. EGF-like domain repeat in stabilin-1 is responsible for PS recognition and binding. Thus, our results demonstrate that stabilin-1, found on alternatively activated macrophages, is a phagocytic receptor mediating the clearance of apoptotic cells in a PS-dependent manner. Therefore, this protein might play an important role in the maintenance of tissue homeostasis and prevention of autoimmunity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cell Adhesion Molecules, Neuronal / chemistry
  • Cell Adhesion Molecules, Neuronal / metabolism*
  • Cell Line
  • Cellular Senescence / drug effects
  • Dexamethasone / pharmacology
  • Epidermal Growth Factor / chemistry
  • Erythrocytes / cytology
  • Erythrocytes / drug effects
  • Humans
  • Interleukin-4 / pharmacology
  • Macrophage Activation* / drug effects
  • Macrophages / cytology*
  • Macrophages / drug effects
  • Macrophages / metabolism*
  • Mice
  • Phagocytosis* / drug effects
  • Phagosomes / drug effects
  • Phagosomes / metabolism
  • Phosphatidylserines / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Receptors, Lymphocyte Homing / chemistry
  • Receptors, Lymphocyte Homing / metabolism*

Substances

  • Cell Adhesion Molecules, Neuronal
  • Phosphatidylserines
  • Receptors, Lymphocyte Homing
  • STAB1 protein, human
  • STAB2 protein, human
  • Interleukin-4
  • Epidermal Growth Factor
  • Dexamethasone