title: Mass spectrometric analysis identifies a cortactin-RCC2/TD60 interaction in mitotic cells.
abstract: Cortactin is an F-actin binding protein that functions as a scaffold to regulate Arp2/3 mediated actin polymerization in lamellipodia and invadopodia formation as well as functioning in cell migration and endocytosis of many different cell types. In light of the fact that regulated actin polymerization is critical for many cellular processes we launched a search for novel cortactin interactions with cellular proteins that might indicate heretofore undescribed biological activities supported by cortactin. Using a modified stable isotope labeling in cell culture (SILAC) approach in HEK293 cells and Flag-tagged cortactin (F-cortactin) as bait, we identified a limited set of cortactin interactions including several proteins which have not previously been identified as cortactin associated proteins. Among these were serine/threonine-protein phosphatase 2A subunit beta (PP2A-beta) and RCC2/TD60, a Rac guanine nucleotide exchange factor (GEF) required for completion of mitosis and cytokinesis. The interaction between cortactin and RCC2/TD60 was verified in cell lysates immunoprecitated with anti-RCC2/TD60 antibody. Furthermore, cortactin was localized by immunofluorescence in the equatorial plane of dividing HeLa cells in the region where RCC2/TD60 has previously been localized thus providing support for a complex containing cortactin and RCC2/TD60 complex that may play a functional role in cells undergoing mitosis.
authors.affiliation: Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, United States.
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Grigera
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Borgman
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Pinto
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Sherman
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Parsons
authors.forename: Jay W
authors.initials: JW
authors.lastname: Fox
mesh_terms: D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D051356:Cortactin / Q000378:metabolism*; D048749:Cytokinesis / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008938:Mitosis / Q000502:physiology*; D046912:Multiprotein Complexes / Q000378:metabolism*; D054648:Protein Phosphatase 2 / Q000378:metabolism
chemical_list: C495868:CTTN protein, human; D002868:Chromosomal Proteins, Non-Histone; D051356:Cortactin; D020662:Guanine Nucleotide Exchange Factors; D046912:Multiprotein Complexes; C477650:RCC2 protein, human; D054648:Protein Phosphatase 2