title: A proteomic study of myosin II motor proteins during tumor cell migration.
abstract: Myosin II motor proteins play important roles in cell migration. Although myosin II filament assembly plays a key role in the stabilization of focal contacts at the leading edge of migrating cells, the mechanisms and signaling pathways regulating the localized assembly of lamellipodial myosin II filaments are poorly understood. We performed a proteomic analysis of myosin heavy chain (MHC) phosphorylation sites in MDA-MB 231 breast cancer cells to identify MHC phosphorylation sites that are activated during integrin engagement and lamellar extension on fibronectin. Fibronectin-activated MHC phosphorylation was identified on novel and previously recognized consensus sites for phosphorylation by protein kinase C and casein kinase II (CK-II). S1943, a CK-II consensus site, was highly phosphorylated in response to matrix engagement, and phosphoantibody staining revealed phosphorylation on myosin II assembled into leading-edge lamellae. Surprisingly, neither pharmacological reduction nor small inhibitory RNA reduction in CK-II activity reduced this stimulated S1943 phosphorylation. Our data demonstrate that S1943 phosphorylation is upregulated during lamellar protrusion, and that CK-II does not appear to be the kinase responsible for this matrix-induced phosphorylation event.
authors.affiliation: Department of Cell Biology, Lerner College of Medicine, Case Western Reserve University, The Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Venkaiah
authors.initials: V
authors.lastname: Betapudi
authors.forename: Giridharan
authors.initials: G
authors.lastname: Gokulrangan
authors.forename: Mark R
authors.initials: MR
authors.lastname: Chance
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Egelhoff
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D019556:COS Cells; D047390:Casein Kinase II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D002522:Chlorocebus aethiops; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024462:Myosin Type II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020543:Proteome / Q000032:analysis*; D011554:Pseudopodia / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D005353:Fibronectins; D020033:Protein Isoforms; D020543:Proteome; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D047390:Casein Kinase II; D024462:Myosin Type II; D018995:Myosin Heavy Chains