Activated Cdc42-associated kinase 1 is a component of EGF receptor signaling complex and regulates EGF receptor degradation.
Cdc42-associated tyrosine kinase 1 (ACK1) is a specific down-stream effector of Cdc42, a Rho family small G-protein. Previous studies have shown that ACK1 interacts with clathrin heavy chain and is involved in clathrin-coated vesicle endocytosis. Here we report that ACK1 interacted with epidermal growth factor receptor (EGFR) upon EGF stimulation via a region at carboxy terminus that is highly homologous to Gene-33/Mig-6/RALT. The interaction of ACK1 with EGFR was dependent on the kinase activity or tyrosine phosphorylation of EGFR. Immunofluorescent staining using anti-EGFR and GFP-ACK1 indicates that ACK1 was colocalized with EGFR on EEA-1 positive vesicles upon EGF stimulation. Suppression of the expression of ACK1 by ACK-RNAi inhibited ligand-induced degradation of EGFR upon EGF stimulation, suggesting that ACK1 plays an important role in regulation of EGFR degradation in cells. Furthermore, we identified ACK1 as an ubiquitin-binding protein. Through an ubiquitin-association (Uba) domain at the carboxy terminus, ACK1 binds to both poly- and mono-ubiquitin. Overexpression of the Uba domain-deletion mutant of ACK1 blocked the ligand-dependent degradation of EGFR, suggesting that ACK1 regulates EGFR degradation via its Uba domain. Taken together, our studies suggest that ACK1 senses signal of EGF and regulates ligand-induced degradation of EGFR.
Shen
Feng
F
Weis Center for Research, Geisinger Clinic, Danville, PA 17822, USA.
Lin
Qiong
Q
Gu
Yan
Y
Childress
Chandra
C
Yang
Wannian
W
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D006224:Cricetinae; D003412:Cricetulus; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D025801:Ubiquitin / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D025801:Ubiquitin; D004815:Epidermal Growth Factor; C498594:Tnk2 protein, mouse; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases