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PKC ε Phosphorylates and Mediates the Cell Membrane Localization of RhoA

Tizhi Su1, Samuel Straight, Liwei Bao

  • 1Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA ; Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.

ISRN Oncology
|November 6, 2013
PubMed

Insights

Protein kinase C epsilon (PKCε) directly phosphorylates RhoA, influencing its movement to the cell membrane. This interaction is key to understanding how PKCε regulates cell invasion and motility.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein kinase C epsilon (PKCε) is known to signal through RhoA.
  • The precise molecular mechanisms governing the PKCε-RhoA interaction and its functional consequences remain incompletely understood.

Purpose of the Study:

  • To elucidate the detailed interaction between PKCε and RhoA.
  • To investigate the phosphorylation sites on RhoA by PKCε.
  • To characterize the spatiotemporal dynamics of the PKCε-RhoA complex.

Main Methods:

  • Phosphopeptide mapping to identify phosphorylation sites.
  • Recombinant protein binding assays.
  • Time-lapse fluorescence microscopy for translocation studies.
  • Förster resonance energy transfer (FRET) analysis for molecular interactions.

Main Results:

  • PKCε phosphorylates RhoA at threonine 127 (T127) and serine 188 (S188).
  • PKCε and RhoA exhibit coordinated translocation from the cytoplasm to the cell membrane upon PKCε activation.
  • FRET analysis revealed a biphasic interaction pattern, with initial cytoplasmic complex formation followed by prolonged membrane association.
  • Kinase-inactive PKCε (K437R) can still recruit RhoA to the membrane, suggesting proximity to the catalytic site but potential independence from phosphorylation.

Conclusions:

  • PKCε directly phosphorylates RhoA, modulating its cell membrane translocation.
  • The PKCε-RhoA complex forms in the cytoplasm and is subsequently recruited to the cell membrane.
  • This phosphorylation-dependent translocation is a novel mechanism by which PKCε regulates RhoA activity and downstream cellular processes like invasion and motility.

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