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Linking integrin alpha6beta4-based cell adhesion to the intermediate filament cytoskeleton: direct interaction

G A Rezniczek1, J M de Pereda, S Reipert

  • 1Institute of Biochemistry and Molecular Cell Biology, Vienna Biocenter, 1030 Vienna, Austria.

The Journal of Cell Biology
|May 16, 1998
PubMed

Insights

Plectin directly links integrin beta4 and cytokeratin filaments, stabilizing hemidesmosomes. This cytoskeletal linker is crucial for maintaining hemidesmosome integrity, as shown in studies of epidermolysis bullosa simplex.

Area of Science:

  • Cell biology
  • Molecular biology
  • Biochemistry

Background:

  • Plectin, a cytoskeletal linker, is implicated in hemidesmosome integrity, particularly in epidermolysis bullosa simplex.
  • Integrin alpha6beta4, a basement membrane receptor, connects the transmembrane complex to cytokeratin filaments.
  • The beta4 subunit's cytoplasmic tail is key for linking integrin to the intermediate filament network.

Purpose of the Study:

  • To elucidate the molecular-level interactions between plectin and the beta4 subunit of integrin alpha6beta4.
  • To define plectin's role in hemidesmosome stabilization through its interaction with integrin beta4.

Main Methods:

  • In vitro binding assays using recombinant proteins and mutant forms.
  • In vivo cotransfection assays to study protein interactions.
  • Gold immunoelectron microscopy to visualize protein localization and orientation.
  • Ectopic overexpression of integrin beta4 cytoplasmic domains in PtK2 and 804G cells.

Main Results:

  • Direct interaction between plectin and the integrin beta4 cytoplasmic tail was confirmed through multiple molecular domains.
  • Integrin beta4 cytoplasmic domains exhibit self-interaction in vitro.
  • Overexpression of the beta4 cytoplasmic domain disrupted intermediate filament networks and dislocated plectin.
  • Immunoelectron microscopy showed plectin associated with hemidesmosomes in a random orientation.

Conclusions:

  • Plectin directly interlinks integrin beta4 subunits and cytokeratin filaments.
  • This interaction stabilizes hemidesmosomes, highlighting plectin's essential role in maintaining cellular structure.
  • Findings provide a molecular basis for plectin's function in hemidesmosome stability and its relevance to genetic disorders.

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