Protein phosphatase 2A regulatory subunit Bβ Promotes MAP kinase-mediated migration of A431 cells

Abstract

Background/Aims: Phosphatases are involved in regulation of MAP kinase (MAPK). A431 cells migrate on collagen after EGF stimulation using MAPK. To clarify the involvement of PP2A in this MAPKdependent migration, the expression of an isoform of the B regulatory subunit was inhibited. Methods: An antisense sequence corresponding to Bβ cDNA was transfected into A431 cells. Their migratory activity on collagen was examined using Transwell, and MAPK phosphorylation and phosphatase activity were measured, and the results were compared with those obtained with mock-transfected cells. Results: Antisense-transfected cells showed less Bβ protein and phosphatase activity than mock-transfected controls. Migration of antisense-transfected cells showed a low response to EGF. The response of MAPK phosphorylation of antisense-transfected cells to EGF stimulation and adhesion to collagen in the presence or absence of EGF were markedly decreased. Phosphatase activity of PP2A-Bβ also did not respond to EGF, collagen or EGF plus collagen, and remained at low levels. Conclusion: These results suggested that PP2A-Bβ promotes cell migration through the MAPK cascade. Copyright © 2005 S. Karger AG, Basel.