Differential functions of ApoER2 and very low density lipoprotein receptor in Reelin signaling depend on differential sorting of the receptors

J Biol Chem. 2010 Feb 12;285(7):4896-908. doi: 10.1074/jbc.M109.025973. Epub 2009 Nov 30.

Abstract

ApoER2 and very low density lipoprotein (VLDL) receptor transmit the Reelin signal into target cells of the central nervous system. To a certain extent, both receptors can compensate for each other, and only the loss of both receptors results in the reeler phenotype, which is characterized by a gross defect in the architecture of laminated brain structures. Nevertheless, both receptors also have specific distinct functions, as corroborated by analyses of the subtle phenotypes displayed in mice lacking either ApoER2 or VLDL receptor. The differences in their function(s), however, have not been defined at the cellular level. Here, using a panel of chimeric receptors, we demonstrate that endocytosis of Reelin and the fate of the individual receptors upon stimulation are linked to their specific sorting to raft versus non-raft domains of the plasma membrane. VLDL receptor residing in the non-raft domain endocytoses and destines Reelin for degradation via the clathrin-coated pit/clathrin-coated vesicle/endosome pathway without being degraded to a significant extent. Binding of Reelin to ApoER2, a resident of rafts, leads to the production of specific receptor fragments with specific functions of their own and to degradation of ApoER2 via lysosomes. These features contribute to a receptor-specific fine tuning of the Reelin signal, leading to a novel model that emphasizes negative feedback loops specifically mediated by ApoER2 and VLDL receptor, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cell Adhesion Molecules, Neuronal / genetics
  • Cell Adhesion Molecules, Neuronal / metabolism*
  • Cell Line
  • Cell Membrane / metabolism
  • Clathrin / metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Endocytosis / genetics
  • Endocytosis / physiology
  • Extracellular Matrix Proteins / genetics
  • Extracellular Matrix Proteins / metabolism*
  • Humans
  • LDL-Receptor Related Proteins
  • Mice
  • Microscopy
  • NIH 3T3 Cells
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Protein Transport / genetics
  • Protein Transport / physiology
  • Receptors, LDL / genetics
  • Receptors, LDL / metabolism*
  • Receptors, Lipoprotein / genetics
  • Receptors, Lipoprotein / metabolism*
  • Reelin Protein
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism*
  • Signal Transduction / genetics
  • Signal Transduction / physiology

Substances

  • Cell Adhesion Molecules, Neuronal
  • Clathrin
  • Extracellular Matrix Proteins
  • LDL-Receptor Related Proteins
  • Nerve Tissue Proteins
  • Receptors, LDL
  • Receptors, Lipoprotein
  • Reelin Protein
  • VLDL receptor
  • low density lipoprotein receptor-related protein 8
  • RELN protein, human
  • Reln protein, mouse
  • Serine Endopeptidases