Autoinhibition of the Kit Receptor Tyrosine Kinase by the Cytosolic Juxtamembrane Region

AUTOR(ES)

Chan, Perry M.

FONTE

American Society for Microbiology

RESUMO

Genetic studies have implicated the cytosolic juxtamembrane region of the Kit receptor tyrosine kinase as an autoinhibitory regulatory domain. Mutations in the juxtamembrane domain are associated with cancers, such as gastrointestinal stromal tumors and mastocytosis, and result in constitutive activation of Kit. Here we elucidate the biochemical mechanism of this regulation. A synthetic peptide encompassing the juxtamembrane region demonstrates cooperative thermal denaturation, suggesting that it folds as an autonomous domain. The juxtamembrane peptide directly interacted with the N-terminal ATP-binding lobe of the kinase domain. A mutation in the juxtamembrane region corresponding to an oncogenic form of Kit or a tyrosine-phosphorylated form of the juxtamembrane peptide disrupted the stability of this domain and its interaction with the N-terminal kinase lobe. Kinetic analysis of the Kit kinase harboring oncogenic mutations in the juxtamembrane region displayed faster activation times than the wild-type kinase. Addition of exogenous wild-type juxtamembrane peptide to active forms of Kit inhibited its kinase activity in trans, whereas the mutant peptide and a phosphorylated form of the wild-type peptide were less effective inhibitors. Lastly, expression of the Kit juxtamembrane peptide in cells which harbor an oncogenic form of Kit inhibited cell growth in a Kit-specific manner. Together, these results show the Kit kinase is autoinhibited through an intramolecular interaction with the juxtamembrane domain, and tyrosine phosphorylation and oncogenic mutations relieved the regulatory function of the juxtamembrane domain.

Documentos Relacionados

• Targeted mutations of the juxtamembrane tyrosines in the Kit receptor tyrosine kinase selectively affect multiple cell lineages
• SHP-1 Binds and Negatively Modulates the c-Kit Receptor by Interaction with Tyrosine 569 in the c-Kit Juxtamembrane Domain
• Signal transduction by normal isoforms and W mutant variants of the Kit receptor tyrosine kinase.
• Gastrointestinal stromal tumors in a mouse model by targeted mutation of the Kit receptor tyrosine kinase
• Phosphorylation of Tyrosine Residues in the Kinase Domain and Juxtamembrane Region Regulates the Biological and Catalytic Activities of Eph Receptors