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Constitutive activated Cdc42-associated kinase (Ack) phosphorylation at arrested endocytic clathrin-coated pits of

Hongying Shen1, Shawn M Ferguson, Noah Dephoure

  • 1Department of Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA.

Molecular Biology of the Cell
|December 21, 2010
PubMed

Insights

Clathrin-mediated endocytosis regulates the activation of activated Cdc42-associated kinase (Ack). Blocking endocytic vesicle formation freezes Ack in an active state, revealing a link between clathrin pit progression and Ack activity.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Clathrin-mediated endocytosis (CME) is crucial for internalizing cell surface molecules, including growth factor receptors.
  • Tyrosine phosphorylation is a key signaling output of growth factor receptor activation.

Purpose of the Study:

  • To investigate the impact of impaired CME on tyrosine phosphorylation signaling.
  • To elucidate the role of dynamin and clathrin in regulating nonreceptor tyrosine kinase activity.

Main Methods:

  • Utilized fibroblasts from dynamin 1 and dynamin 2 double conditional knockout mice to halt CME at deep invagination.
  • Employed RNA interference and pharmacological inhibitors to study Ack activation.
  • Investigated Ack's interaction with clathrin heavy chain.

Main Results:

  • Cells lacking functional dynamin exhibited increased tyrosine phosphorylation of activated Cdc42-associated kinase (Ack).
  • Ack accumulates at clathrin-coated pits and binds clathrin heavy chain.
  • Ack phosphorylation requires clathrin assembly and active Cdc42.

Conclusions:

  • CME progression is linked to the activation-deactivation cycle of Ack.
  • Dynamin and clathrin are essential for regulating Ack activity during endocytosis.

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