Integrin alpha 4 beta 1-dependent T cell migration requires both phosphorylation and dephosphorylation of the alpha 4 cytoplasmic domain to regulate the reversible binding of paxillin.
alpha 4 integrins mediate increased cell migration and decreased cell spreading because the alpha 4 cytoplasmic domain (tail) binds tightly to paxillin, a signaling adaptor protein. Paxillin binding to the alpha 4 tail is blocked by alpha 4 phosphorylation at Ser988. To establish the biological role of alpha 4 phosphorylation, we reconstituted alpha 4-deficient Jurkat T cells with phosphorylation-mimicking (alpha 4(S988D)) or non-phosphorylatable (alpha 4(S988A)) mutants. alpha 4(S988D) disrupted paxillin binding and also inhibited cell migration and promoted cell spreading. In contrast, the non-phosphorylatable alpha 4(S988A) resulted in a further reduction in cell spreading; however, this mutation led to an unexpected suppression of cell migration. The suppression of cell migration by alpha 4(S988A) was ascribable to enhanced alpha 4-paxillin association, because enforced association by an alpha 4-paxillin fusion led to a phenotype similar to that of the non-phosphorylatable alpha 4(S988A) mutant. These data establish that optimal alpha 4-mediated cell migration requires both phosphorylation and dephosphorylation of the alpha 4 cytoplasmic domain to regulate the reversible binding of paxillin.
Han
Jaewon
J
Department of Cell Biology, Division of Vascular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Rose
David M
DM
Woodside
Darren G
DG
Goldfinger
Lawrence E
LE
Ginsberg
Mark H
MH
D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D006224:Cricetinae; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D006801:Humans; D039041:Integrin alpha4beta1 / Q000502:physiology*; D019169:Jurkat Cells; D016297:Mutagenesis, Site-Directed; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D039041:Integrin alpha4beta1; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D011994:Recombinant Proteins; D019000:Phosphotyrosine