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Measuring Plasma Membrane Protein Endocytic Rates by Reversible Biotinylation
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Measuring Plasma Membrane Protein Endocytic Rates by Reversible Biotinylation

Published on: December 23, 2009

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Mdm2-mediated ubiquitination of PKCβII in the nucleus mediates clathrin-mediated endocytic activity

Xiao Min1, Xiaohan Zhang2, Ningning Sun1

  • 1Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea.

Biochemical Pharmacology
|October 22, 2019
PubMed

Insights

Mdm2 E3 ubiquitin ligase targets protein kinase C beta II (PKCβII) for degradation, influencing its lifespan and cellular roles. This ubiquitination impacts G protein-coupled receptor endocytosis and disease pathogenesis.

Area of Science:

  • Cellular Biology
  • Molecular Mechanisms
  • Protein Degradation

Background:

  • Protein kinase C (PKC) isoforms are activated by cellular stimuli but depleted by prolonged stimulation.
  • Ubiquitination mediates protein degradation, yet its role in PKC ubiquitination is poorly understood.
  • PKCβII is a widely expressed isoform regulating diverse cellular functions.

Purpose of the Study:

  • To elucidate the molecular mechanisms of PKCβII ubiquitination.
  • To identify the E3 ubiquitin ligase responsible for PKCβII ubiquitination.
  • To understand the functional consequences of PKCβII ubiquitination on its lifespan and endocytic roles.

Main Methods:

  • Stimulation of Gq-coupled angiotensin II type 1 receptor and phorbol ester treatment.
  • Co-immunoprecipitation to detect protein interactions (Mdm2 and PKCβII).
  • Western blotting to assess ubiquitination and protein levels.

Main Results:

  • Mdm2, an E3 ubiquitin ligase, interacts with PKCβII in the nucleus upon stimulation.
  • PKCβII is ubiquitinated at C-terminal residues K668 and K672, leading to its downregulation.
  • Ubiquitinated PKCβII mediates clathrin-dependent endocytosis of GPCRs, while non-ubiquitinated PKCβII uses an independent pathway.

Conclusions:

  • Activity-dependent ubiquitination of PKCβII by Mdm2 regulates its stability and endocytic functions.
  • Understanding PKCβII ubiquitination is crucial for diseases like diabetic vasculitis.
  • This study provides insights into the pathogenesis of PKCβII-related diseases.
Keywords:
Clathrin-mediated endocytosisDopamine receptorMdm2PKCβIIUbiquitination

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