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Munc-18-1 inhibits phospholipase D activity by direct interaction in an epidermal growth factor-reversible manner

Hye Young Lee1, Jong Bae Park, Il Ho Jang

  • 1Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784 Republic of Korea.

The Journal of Biological Chemistry
|January 28, 2004
PubMed

Insights

Munc-18-1 negatively regulates phospholipase D (PLD) activity. Epidermal growth factor (EGF) stimulation disrupts this interaction, activating PLD signaling pathways.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Signaling

Background:

  • Mammalian phospholipase D (PLD) is crucial for epidermal growth factor (EGF)-induced cellular signaling.
  • The precise regulatory mechanisms governing PLD activity remain incompletely understood.

Purpose of the Study:

  • To identify regulatory proteins of PLD.
  • To elucidate the role of Munc-18-1 in PLD regulation.
  • To investigate the effect of EGF stimulation on the PLD-Munc-18-1 interaction.

Main Methods:

  • Protein identification via peptide-mass fingerprinting.
  • In vitro binding assays with purified proteins.
  • Co-transfection and activity assays in COS-7 cells.
  • Immunoprecipitation and co-localization studies.
  • Analysis in primary cultured chromaffin cells.

Main Results:

  • Munc-18-1 was identified as a PLD-binding protein.
  • Munc-18-1 potently inhibits basal PLD activity in vitro and in vivo.
  • Munc-18-1 interacts with and colocalizes with PLD2 at the plasma membrane.
  • EGF stimulation causes Munc-18-1 dissociation from PLD, leading to PLD activation.

Conclusions:

  • Munc-18-1 acts as a significant negative regulator of basal PLD activity.
  • EGF signaling abolishes the inhibitory interaction between Munc-18-1 and PLD, enabling PLD activation.

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