The α6β4 integrin complex is generally thought to be expressed by epithelial cells, where it is localized in specific adhesion structures, the hemidesmosomes. Recent observations have suggested a new localization of the β4 integrin chain in small vessels, possibly in endothelial cells, i.e., in cells of mesenchymal origin. In the present study we show that (a) the α6 and β4 integrin chains are not expressed by endothelial cells, since they are not localized in von Willebrand factor-producing cells; (b) instead, smooth muscle cells of small vessels are intensely positive to antibodies to both α6 and β4 integrin chains; and (c) in some restricted regions of these smooth muscle cells there is a clear colocalization between α-smooth muscle actin and α6 and β4 integrin chains, suggesting that a new type of cytoskeletal linkage for the α6β4 integrin complex may occur in mesenchyme-derived cells. Our observations are supported by confocal laser microscopy (CLSM) images of specimens labeled by double immunofluorescence. This technical choice was made to take advantage of the higher resolution offered by CLSM in comparison with conventional immunofluorescence. A careful selection of barrier filters was necessary to separate accurately emission and excitation spectra of the fluorochromes used in this study, resulting in an efficient colocalization analysis.
|Number of pages||8|
|Journal||Journal of Histochemistry and Cytochemistry|
|Publication status||Published - 1994|
- Actin isoforms
- Adhesion receptors
ASJC Scopus subject areas
- Cell Biology