Different routes of bone morphogenic protein (BMP) receptor endocytosis influence BMP signaling

Mol Cell Biol. 2006 Oct;26(20):7791-805. doi: 10.1128/MCB.00022-06. Epub 2006 Aug 21.

Abstract

Endocytosis is important for a variety of functions in eukaryotic cells, including the regulation of signaling cascades via transmembrane receptors. The internalization of bone morphogenetic protein (BMP) receptor type I (BRI) and type II (BRII) and its relation to signaling were largely unexplored. Here, we demonstrate that both receptor types undergo constitutive endocytosis via clathrin-coated pits (CCPs) but that only BRII undergoes also caveola-like internalization. Using several complementary approaches, we could show that (i) BMP-2-mediated Smad1/5 phosphorylation occurs at the plasma membrane in nonraft regions, (ii) continuation of Smad signaling resulting in a transcriptional response requires endocytosis via the clathrin-mediated route, and (iii) BMP signaling leading to alkaline phosphatase induction initiates from receptors that fractionate into cholesterol-enriched, detergent-resistant membranes. Furthermore, we show that BRII interacts with Eps15R, a constitutive component of CCPs, and with caveolin-1, the marker protein of caveolae. Taken together, the localization of BMP receptors in distinct membrane domains is prerequisite to their taking different endocytosis routes with specific impacts on Smad-dependent and Smad-independent signaling cascades.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Morphogenetic Protein Receptors, Type I / metabolism*
  • Bone Morphogenetic Protein Receptors, Type II / genetics
  • Bone Morphogenetic Protein Receptors, Type II / metabolism*
  • Bone Morphogenetic Proteins / metabolism*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Caveolae / metabolism
  • Caveolin 1 / metabolism
  • Cell Line
  • Chlorocebus aethiops
  • Cholesterol / metabolism
  • Endocytosis*
  • Genetic Variation / genetics
  • Humans
  • Mice
  • Microscopy, Electron
  • Mutation / genetics
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Binding
  • RNA Splicing
  • Signal Transduction*
  • Smad Proteins / metabolism

Substances

  • Bone Morphogenetic Proteins
  • Calcium-Binding Proteins
  • Cav1 protein, mouse
  • Caveolin 1
  • Phosphoproteins
  • Smad Proteins
  • Cholesterol
  • Bone Morphogenetic Protein Receptors, Type I
  • Bone Morphogenetic Protein Receptors, Type II