Phosphorylation of a conserved integrin alpha 3 QPSXXE motif regulates signaling, motility, and cytoskeletal engagement.
Integrin alpha 3A cytoplasmic tail phosphorylation was mapped to amino acid S1042, as determined by mass spectrometry, and confirmed by mutagenesis. This residue occurs within a "QPSXXE" motif conserved in multiple alpha chains (alpha 3A, alpha 6A, alpha 7A), from multiple species. Phosphorylation of alpha 3A and alpha 6A did not appear to be directly mediated by protein kinase C (PKC) alpha, beta, gamma, delta, epsilon, zeta, or mu, or by any of several other known serine kinases, although PKC has an indirect role in promoting phosphorylation. A S1042A mutation did not affect alpha 3-Chinese hamster ovary (CHO) cell adhesion to laminin-5, but did alter 1) alpha 3-dependent tyrosine phosphorylation of focal adhesion kinase and paxillin (in the presence or absence of phorbol 12-myristate 13 acetate stimulation), and p130(CAS) (in the absence of phorbol 12-myristate 13 acetate stimulation), 2) the shape of cells spread on laminin-5, and 3) alpha 3-dependent random CHO cell migration on laminin-5. In addition, S1042A mutation altered the PKC-dependent, ligand-dependent subcellular distribution of alpha 3 and F-actin in CHO cells. Together, the results demonstrate clearly that alpha 3A phosphorylation is functionally relevant. In addition, the results strongly suggest that alpha 3 phosphorylation may regulate alpha 3 integrin interaction with the cytoskeleton.
Zhang
X A
XA
Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Bontrager
A L
AL
Stipp
C S
CS
Kraeft
S K
SK
Bazzoni
G
G
Chen
L B
LB
Hemler
M E
ME
D000470:Alkaloids; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D053119:Benzophenanthridines; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism / Q000494:pharmacology; D002465:Cell Movement; D017124:Conserved Sequence; D006224:Cricetinae; D003412:Cricetulus; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D039422:Integrin alpha3; D016023:Integrins / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010617:Phenanthridines / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology; D000097794:Kalinin
D000470:Alkaloids; D015703:Antigens, CD; D053119:Benzophenanthridines; D015815:Cell Adhesion Molecules; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D019833:Genistein; D039422:Integrin alpha3; D016023:Integrins; D010617:Phenanthridines; D011493:Protein Kinase C; D011505:Protein-Tyrosine Kinases; D012694:Serine; D019311:Staurosporine; D000097794:Kalinin; C016299:chelerythrine