Differential Regulation of Cell Migration and Proliferation through Proline-Rich Tyrosine Kinase 2 in Endothelial Cells

Proline-rich tyrosine kinase 2 (Pyk2), a member of the focal adhesion kinase family, is thought to act as a key component in vasculogenesis and angiogenesis. Therefore, we studied the effect of mutant Pyk2 expression on the migration and proliferation in endothelial cells (ECs). Two types of mutant Pyk2 were examined by adenovirus vectors AxCA-Pyk2K457A, expressing a kinase inactive mutant, and AxCA-Pyk2Y402F, expressing a tyrosine autophosphorylation site mutant, in addition to AxCA-Pyk2, expressing wild-type Pyk2. Migration of ECs infected with AxCA-Pyk2Y402F increased to a level similar to that of ECs infected with AxCA-Pyk2. The size of effect was dependent on the amount of applied adenoviruses within the range of 3-30 multiplicity of infection. In contrast, AxCA-Pyk2K457A infection did not show any significant effect on cell migration. Western blotting showed that both phosphorylation of Pyk2 Y(881) and association of p130(Cas) with Pyk2 were enhanced in ECs infected with AxCA-Pyk2Y402F as well as with AxCA-Pyk2, but not in ECs infected with AxCA-Pyk2K457A. Therefore, signaling mediated by Pyk2 Y(881) and p130(Cas) may be involved in the migration of ECs infected either with AxCA-Pyk2Y402F or with AxCA-Pyk2. In proliferation assay, AxCA-Pyk2 infection suppressed EC proliferation significantly; however, neither AxCA-Pyk2Y402F nor AxCA-Pyk2K457A showed such an inhibitory effect. Thus, the two Pyk2 mutants revealed that Pyk2 signaling differentially regulates cell migration and proliferation pathways.