The amino-terminal domain of desmoplakin binds to plakoglobin and clusters desmosomal cadherin-plakoglobin complexes

J Cell Biol. 1997 Nov 3;139(3):773-84. doi: 10.1083/jcb.139.3.773.

Abstract

The desmosome is a highly organized plasma membrane domain that couples intermediate filaments to the plasma membrane at regions of cell-cell adhesion. Desmosomes contain two classes of cadherins, desmogleins, and desmocollins, that bind to the cytoplasmic protein plakoglobin. Desmoplakin is a desmosomal component that plays a critical role in linking intermediate filament networks to the desmosomal plaque, and the amino-terminal domain of desmoplakin targets desmoplakin to the desmosome. However, the desmosomal protein(s) that bind the amino-terminal domain of desmoplakin have not been identified. To determine if the desmosomal cadherins and plakoglobin interact with the amino-terminal domain of desmoplakin, these proteins were co-expressed in L-cell fibroblasts, cells that do not normally express desmosomal components. When expressed in L-cells, the desmosomal cadherins and plakoglobin exhibited a diffuse distribution. However, in the presence of an amino-terminal desmoplakin polypeptide (DP-NTP), the desmosomal cadherins and plakoglobin were observed in punctate clusters that also contained DP-NTP. In addition, plakoglobin and DP-NTP were recruited to cell-cell interfaces in L-cells co-expressing a chimeric cadherin with the E-cadherin extracellular domain and the desmoglein-1 cytoplasmic domain, and these cells formed structures that were ultrastructurally similar to the outer plaque of the desmosome. In transient expression experiments in COS cells, the recruitment of DP-NTP to cell borders by the chimera required co-expression of plakoglobin. Plakoglobin and DP-NTP co-immunoprecipitated when extracted from L-cells, and yeast two hybrid analysis indicated that DP-NTP binds directly to plakoglobin but not Dsg1. These results identify a role for desmoplakin in organizing the desmosomal cadherin-plakoglobin complex and provide new insights into the hierarchy of protein interactions that occur in the desmosomal plaque.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cadherins / chemistry
  • Cadherins / genetics
  • Cadherins / metabolism*
  • Cytoplasm / chemistry
  • Cytoplasm / metabolism
  • Cytoskeletal Proteins / chemistry*
  • Cytoskeletal Proteins / metabolism*
  • Cytoskeletal Proteins / physiology*
  • Desmocollins
  • Desmoglein 1
  • Desmogleins
  • Desmoplakins
  • Desmosomes / chemistry
  • Desmosomes / genetics
  • Desmosomes / metabolism*
  • Extracellular Space / chemistry
  • Extracellular Space / genetics
  • Humans
  • L Cells
  • Macromolecular Substances
  • Mice
  • Peptides / metabolism
  • Peptides / physiology
  • Protein Binding
  • Protein Structure, Tertiary*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / physiology
  • alpha Catenin
  • gamma Catenin

Substances

  • CTNNA1 protein, human
  • Cadherins
  • Ctnna1 protein, mouse
  • Cytoskeletal Proteins
  • DSG1 protein, human
  • DSP protein, human
  • Desmocollins
  • Desmoglein 1
  • Desmogleins
  • Desmoplakins
  • Dsg1a protein, mouse
  • Dsp protein, mouse
  • Macromolecular Substances
  • Peptides
  • Recombinant Fusion Proteins
  • alpha Catenin
  • gamma Catenin