title: The activation mechanism of ACK1 (activated Cdc42-associated tyrosine kinase 1).
abstract: ACK [activated Cdc42 (cell division cycle 42)-associated tyrosine kinase; also called TNK2 (tyrosine kinase, non-receptor, 2)] is activated in response to multiple cellular signals, including cell adhesion, growth factor receptors and heterotrimeric G-protein-coupled receptor signalling. However, the molecular mechanism underlying activation of ACK remains largely unclear. In the present study, we demonstrated that interaction of the SH3 (Src homology 3) domain with the EBD [EGFR (epidermal growth factor receptor)-binding domain] in ACK1 forms an auto-inhibition of the kinase activity. Release of this auto-inhibition is a key step for activation of ACK1. Mutation of the SH3 domain caused activation of ACK1, independent of cell adhesion, suggesting that cell adhesion-mediated activation of ACK1 is through releasing the auto-inhibition. A region at the N-terminus of ACK1 (Leu10-Leu14) is essential for cell adhesion-mediated activation. In the activation of ACK1 by EGFR signalling, Grb2 (growth-factor-receptor-bound protein 2) mediates the interaction of ACK1 with EGFR through binding to the EBD and activates ACK1 by releasing the auto-inhibition. Furthermore, we found that mutation of Ser445 to proline caused constitutive activation of ACK1. Taken together, our studies have revealed a novel molecular mechanism underlying activation of ACK1.
authors.affiliation: School of Medical Sciences and Laboratory Medicine, Jiangsu University, Zhenjiang 212013, China. qlin1@geisinger.edu
authors.forename: Qiong
authors.initials: Q
authors.lastname: Lin
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Chandra
authors.initials: C
authors.lastname: Childress
authors.forename: Wannian
authors.initials: W
authors.lastname: Yang
mesh_terms: D015153:Blotting, Western; D002448:Cell Adhesion; D049109:Cell Proliferation; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D025461:Feedback, Physiological; D051380:GRB2 Adaptor Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D018909:src Homology Domains
chemical_list: D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D034741:RNA, Small Interfering; C512478:EGFR protein, human; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; C403262:TNK2 protein, human