Role of α3β1 integrin in tubulogenesis of Madin-Darby canine kidney cells

Role of α3β1 integrin in tubulogenesis of Madin-Darby canine kidney cells.BackgroundWe isolated several Madin-Darby canine kidney (MDCK) subclones that exhibit different degrees of branching tubulogenesis in lower concentrations of collagen gel. The M634 clone formed cell aggregates in 0.3% collagen gel, but developed branching tubules vigorously in 0.1% collagen gel. In contrast, the Y224 clone formed cysts in 0.3% collagen gel and displayed fewer branching structures in 0.1% collagen gel. Morphologically, M634 cells exhibited higher levels of cell scattering as well as collagen-induced cell migration than Y224. We conducted this study to delineate the underlying mechanism of branching tubulogenesis in M634 cells.MethodsComponents of the focal contact machinery were analyzed in both cell lines, including the extracellular matrix glycoproteins fibronectin, laminin, and vitronectin; cytoskeleton-associated elements α-actinin, talin, and vinculin; and receptors for extracellular matrix and α2, α3, α5, αv, β1, and β3 integrins. Furthermore, we established several stable transfectants of α3 integrin antisense RNA in M634 cells to examine the role of α3β1 integrin in branching morphogenesis directly.ResultsThere were no obvious differences in levels of the focal adhesion complex proteins between M634 and Y224 cells, except that the content of the α3 and β1 integrins were 1.2- and 0.6-fold higher in M634 cells, respectively. The expression of α3 integrin antisense RNA significantly lowered the levels of α3 integrin mRNA and protein. The potential of cell scattering, migration, and branching tubulogenesis in M634 cells was inhibited according to the decrease in α3 integrin expression.ConclusionOur data indicate that expression of α3β1 integrin regulates cell scattering, migration, and branching tubulogenesis of MDCK cells, possibly via adhesion to or serving as a signaling molecule for type I collagen