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PRR5L degradation promotes mTORC2-mediated PKC-δ phosphorylation and cell migration downstream of Gα12

Xiaoqing Gan1, Jiyong Wang, Chen Wang

  • 1Department of Pharmacology and Program in Vascular Biology and Therapeutics, Yale School of Medicine, New Haven, Connecticut 06520, USA.

Nature Cell Biology
|May 22, 2012
PubMed

Insights

Lysophosphatidic acid (LPA) triggers a novel signaling pathway involving Gα(12) and RFFL E3 ubiquitin ligase to regulate mTORC2 activity, impacting cell migration and pulmonary fibrosis.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Biochemistry

Background:

  • Mammalian target of rapamycin complex 2 (mTORC2) is crucial for cell migration by phosphorylating AGC kinases like protein kinase C (PKC).
  • The precise regulatory mechanisms governing mTORC2 activity, particularly its hydrophobic motif phosphorylation, remain largely unelucidated.
  • Understanding mTORC2 regulation is vital for addressing cellular dysfunction in diseases such as fibrosis.

Purpose of the Study:

  • To elucidate the signaling pathway by which lysophosphatidic acid (LPA) regulates mTORC2.
  • To investigate the role of specific signaling components, including Gα(12), ARAF, and RFFL, in mTORC2-mediated PKC-δ phosphorylation.
  • To determine the functional significance of this pathway in fibroblast migration and the development of pulmonary fibrosis.

Main Methods:

  • Investigated the two-phase phosphorylation of PKC-δ hydrophobic motif induced by LPA.
  • Utilized Gα(12) signaling to identify downstream effectors, including ARAF activation and RFFL E3 ubiquitin ligase.
  • Examined the ubiquitylation and degradation of the mTORC2 PRR5L subunit and its impact on PKC-δ and AKT phosphorylation.
  • Assessed the role of the identified pathway in fibroblast migration and pulmonary fibrosis models.

Main Results:

  • LPA induces a late-phase PKC-δ hydrophobic motif phosphorylation dependent on Gα(12).
  • Gα(12) activates ARAF, leading to increased RFFL E3 ubiquitin ligase expression.
  • RFFL mediates ubiquitylation and degradation of PRR5L, a suppressor of mTORC2 activity.
  • PRR5L destabilization specifically enhances PKC-δ, not AKT, hydrophobic motif phosphorylation and activation.
  • This pathway is essential for fibroblast migration and the pathogenesis of pulmonary fibrosis.

Conclusions:

  • A novel Gα(12)-ARAF-RFFL signaling axis regulates mTORC2 by degrading PRR5L.
  • This pathway specifically controls PKC-δ activation, influencing cell migration.
  • The elucidated mechanism is critical for fibroblast migration and the development of pulmonary fibrosis, offering potential therapeutic targets.

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