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Assaying Protein Kinase Activity with Radiolabeled ATP
Published on: May 26, 2017
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The Nck-interacting kinase NIK increases Arp2/3 complex activity by phosphorylating the Arp2 subunit
Lawrence L LeClaire1, Manish Rana2, Martin Baumgartner3
1Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143 Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688 leclaire@southalabama.edu.
The Journal of Cell Biology
|January 21, 2015
Summary
Phosphorylation of the Arp2/3 complex is essential for cell migration. Nck-interacting kinase (NIK) directly phosphorylates Arp2, activating the Arp2/3 complex and driving membrane protrusion.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The Arp2/3 complex is crucial for branched actin filament assembly, driving cell migration.
- Previously, Arp2/3 complex activation was linked to nucleation-promoting factors, but phosphorylation of the Arp2 subunit is now recognized as essential.
- Mutant Arp2 lacking phosphorylation impairs actin assembly and membrane protrusion.
Purpose of the Study:
- To investigate the role of Arp2 subunit phosphorylation in Arp2/3 complex activity.
- To identify the kinase responsible for Arp2 phosphorylation and its impact on cell migration.
- To elucidate the mechanism by which growth factors regulate actin dynamics via the Arp2/3 complex.
Main Methods:
- Utilized mammary carcinoma cells expressing mutant Arp2.
- Investigated the interaction and phosphorylation of Arp2 by Nck-interacting kinase (NIK).
- Assessed the necessity of NIK kinase activity for Arp2 phosphorylation and membrane protrusion in response to epidermal growth factor.
Main Results:
- Mutant Arp2 lacking phosphorylation suppressed actin filament assembly and membrane protrusion.
- Nck-interacting kinase (NIK) directly binds and phosphorylates the Arp2 subunit, enhancing Arp2/3 complex nucleating activity.
- NIK kinase activity is required for epidermal growth factor-induced Arp2 phosphorylation and plasma membrane protrusion.
Conclusions:
- NIK is the first identified kinase that phosphorylates and activates the Arp2/3 complex.
- Findings suggest NIK integrates growth factor signaling to regulate actin filament dynamics.
- Arp2 phosphorylation is a critical regulatory step for Arp2/3 complex-mediated cell migration.
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