Specific tyrosine phosphorylation sites on cortactin regulate Nck1-dependent actin polymerization in invadopodia.
Invadopodia are matrix-degrading membrane protrusions in invasive carcinoma cells enriched in proteins that regulate actin polymerization. The on-off regulatory switch that initiates actin polymerization in invadopodia requires phosphorylation of tyrosine residues 421, 466, and 482 on cortactin. However, it is unknown which of these cortactin tyrosine phosphorylation sites control actin polymerization. We investigated the contribution of individual tyrosine phosphorylation sites (421, 466, and 482) on cortactin to the regulation of actin polymerization in invadopodia. We provide evidence that the phosphorylation of tyrosines 421 and 466, but not 482, is required for the generation of free actin barbed ends in invadopodia. In addition, these same phosphotyrosines are important for Nck1 recruitment to invadopodia via its SH2 domain, for the direct binding of Nck1 to cortactin in vitro, and for the FRET interaction between Nck1 and cortactin in invadopodia. Furthermore, matrix proteolysis-dependent tumor cell invasion is dramatically inhibited in cells expressing a mutation in phosphotyrosine 421 or 466. Together, these results identify phosphorylation of tyrosines 421 and 466 on cortactin as the crucial residues that regulate Nck1-dependent actin polymerization in invadopodia and tumor cell invasion, and suggest that specifically blocking either tyrosine 421 or 466 phosphorylation might be effective at inhibiting tumor cell invasion in vivo.
Oser
Matthew
M
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA.
Mader
Christopher C
CC
Gil-Henn
Hava
H
Magalhaes
Marco
M
Bravo-Cordero
Jose Javier
JJ
Koleske
Anthony J
AJ
Condeelis
John
J
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism*; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D051356:Cortactin / Q000235:genetics / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D005260:Female; D006801:Humans; D009361:Neoplasm Invasiveness / Q000235:genetics; D015513:Oncogene Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011554:Pseudopodia / Q000378:metabolism*; D014443:Tyrosine / Q000235:genetics; D018909:src Homology Domains / Q000235:genetics
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D051356:Cortactin; C078332:Nck protein; D015513:Oncogene Proteins; D014443:Tyrosine