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Keywords:

  • coronary artery;
  • epicardium;
  • integrin;
  • fibronectin;
  • vitronectin;
  • fibrillar adhesions;
  • cell adhesion

Abstract

Formation of the epicardium requires interactions between α4β1 integrin, and the extracellular matrix. We investigated the role of other integrins expressed by epicardial cells. We detected transcripts for α5, α8, αv, β1, β3, and β5 integrins in the chick proepicardial organ (PE). We demonstrate that α5β1, α8β1, and αvβ3 integrins are expressed by chick epicardial mesothelial cells (EMCs). Migration of EMCs in vitro was reduced by RGD-containing peptides. Using adenoviruses expressing an antisense to chick α4 (AdGFPα4AS), full-length (Adhα4V5), and C-terminal deleted α4 (Adhα4ΔCV5), we found that EMCs were less able to adhere to vitronectin and fibronectin120 indicating that α4β1 plays a role in regulating EMC adhesion to ligands of α5β1, α8β1, and αvβ3. In Adhα4ΔCV5-infected EMCs, α5β1 was diminished in fibrillar adhesions and new FN matrix assembly was abnormal. We propose that cooperation between α4β1 and RGD integrins is important for EMC adhesion and subepicardial matrix formation. Developmental Dynamics 237:962–978, 2008. © 2008 Wiley-Liss, Inc.