title: Alternative splicing of the actin binding domain of human cortactin affects cell migration.
abstract: Cortactin is a filamentous actin (F-actin)-binding protein that regulates cytoskeletal dynamics by activating the Arp2/3 complex; it binds to F-actin by means of six N-terminal "cortactin repeats". Gene amplification of 11q13 and consequent overexpression of cortactin in several human cancers is associated with lymph node metastasis. Overexpression as well as tyrosine phosphorylation of cortactin has been reported to enhance cell migration, invasion, and metastasis. Here we report the identification of two alternative splice variants (SV1 and SV2) that affect the cortactin repeats: SV1-cortactin lacks the 6th repeat (exon 11), whereas SV2-cortactin lacks the 5th and 6th repeats (exons 10 and 11). SV-1 cortactin is found co-expressed with wild type (wt)-cortactin in all tissues and cell lines examined, whereas the SV2 isoform is much less abundant. SV1-cortactin binds F-actin and promotes Arp2/3-mediated actin polymerization equally well as wt-cortactin, whereas SV2-cortactin shows reduced F-actin binding and polymerization. Alternative splicing of cortactin does not affect its subcellular localization or growth factor-induced tyrosine phosphorylation. However, cells that overexpress SV1- or SV2-cortactin show significantly reduced cell migration when compared with wt-cortactin-overexpressing cells. Thus, in addition to overexpression and tyrosine phosphorylation, alternative splicing of the F-actin binding domain of cortactin is a new mechanism by which cortactin influences cell migration.
authors.affiliation: Department of Pathology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.
authors.forename: Agnes G S H
authors.initials: AG
authors.lastname: van Rossum
authors.forename: Jos H
authors.initials: JH
authors.lastname: de Graaf
authors.forename: Ellen
authors.initials: E
authors.lastname: Schuuring-Scholtes
authors.forename: Philip M
authors.initials: PM
authors.lastname: Kluin
authors.forename: Ying-Xin
authors.initials: YX
authors.lastname: Fan
authors.forename: Xi
authors.initials: X
authors.lastname: Zhan
authors.forename: Wouter H
authors.initials: WH
authors.lastname: Moolenaar
authors.forename: Ed
authors.initials: E
authors.lastname: Schuuring
mesh_terms: D000199:Actins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D019556:COS Cells; D002465:Cell Movement; D051356:Cortactin; D004305:Dose-Response Relationship, Drug; D005091:Exons; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000199:Actins; C495868:CTTN protein, human; D051356:Cortactin; C495869:Cttn protein, mouse; D008840:Microfilament Proteins; D020033:Protein Isoforms; D014443:Tyrosine; D005982:Glutathione Transferase