Identification of integrin heterodimers functioning on the surface of undifferentiated porcine primed embryonic stem cells

Abstract

In vitro expansion of undifferentiated porcine primed embryonic stem (ES) cells is facilitated by use of non-cellular niches that mimic three-dimensional (3D) microenvironments enclosing an inner cell mass of porcine blastocysts. Therefore, we investigated the integrin heterodimers on the surface of undifferentiated porcine primed ES cells for the purpose of developing a non-cellular niche to support in vitro maintenance of the self-renewal ability of porcine primed ES cells. Immunocytochemistry and a fluorescence immunoassay were performed to assess integrin α and β subunit levels, and attachment and antibody inhibition assays were used to evaluate the function of integrin heterodimers. The integrin α₃ , α₅ , α₆ , α₉ , α_V , and β₁ subunits, but not the α₁ , α₂ , α₄ , α₇ , and α₈ subunits, were identified on the surface of undifferentiated porcine primed ES cells. Subsequently, significant increase of their adhesion to fibronectin, tenascin C, and vitronectin were observed and functional blocking of integrin heterodimer α₅ β₁ , α₉ β₁ , or α_V β₁ showed significantly inhibited adhesion to fibronectin, tenascin C, or vitronectin. No integrin α₆ β₁ heterodimer-mediated adhesion to laminin was detected. These results demonstrate that active α₅ β₁ , α₉ β₁ , and α_V β₁ integrin heterodimers are present on the surface of undifferentiated porcine primed ES cells, together with inactive integrin α₃ (presumed) and α₆ subunits.

Keywords: cell adhesion; extracellular matrix; integrin.