Involvement of SASH1 in the Maintenance of Stable Cell-Cell Adhesion

Biochemistry (Mosc). 2020 Jun;85(6):660-667. doi: 10.1134/S0006297920060036.

Abstract

SASH1 is an adapter and signaling protein that contains SH3 and SAM domains responsible for protein-protein interactions. SASH1 downregulation has been observed in many tumors. We examined localization of SASH1 in cultures of normal IAR-20 epithelial cells and HT-29 colorectal cancer cells using immunofluorescence staining and confocal microscopy. IAR-20 normal epithelial cells and HT-29 cells with epithelial phenotype formed stable linear adherens junctions (AJs) associated with circumferential actin bundles. In both IAR-20 and HT-29 cells, SASH1 was co-localized with zones of circumferential actin bundles and linear AJs. SASH1 was not detected in lamellipodia. IAR-20 and HT-29 cells treated with Epidermal Growth Factor underwent epithelial-mesenchymal transition (EMT). We observed significant differences in the course of EMT between IAR-20 and HT-29 cultures. IAR-20 cells underwent partial EMT acquiring migratory phenotype but retaining E-cadherin in unstable radial AJs. SASH1 was present in these contacts. Disappearance of AJs was observed in HT-29 cell undergoing a complete EMT, which also resulted in disruption of stable cell-cell adhesion. SASH1 was lost from the zones of cell-cell interaction. SASH1 depletion by means of RNA interference in IAR-20 cells led to destruction of stable linear AJs and acquisition of mesenchymal phenotype by some of the cells. These data indicate involvement of SASH1 in the maintenance of stable cell-cell adhesion.

MeSH terms

  • Actins / metabolism*
  • Adherens Junctions / metabolism*
  • Antigens, CD / metabolism*
  • Cadherins / metabolism*
  • Cell Adhesion*
  • Cell Communication
  • Cells, Cultured
  • Epithelial Cells / physiology*
  • Epithelial-Mesenchymal Transition*
  • Humans
  • Signal Transduction
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*

Substances

  • Actins
  • Antigens, CD
  • CDH1 protein, human
  • Cadherins
  • SASH1 protein, human
  • Tumor Suppressor Proteins