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Interaction with the Paxillin LD1 Motif Relieves MEKK2 Auto-inhibition

Michael P Kahle1, Bruce D Cuevas1

  • 1Department of Molecular Pharmacology and Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.

Journal of Molecular Signaling
|April 21, 2016
PubMed

Insights

Paxillin binding and ubiquitylation activate MEK kinase 2 (MEKK2), a key regulator of MAPK signaling. This study reveals a novel bi-directional regulatory relationship between MEKK2 and paxillin.

Area of Science:

  • Cellular Biology
  • Molecular Signaling

Background:

  • MEK kinase 2 (MEKK2) is a crucial regulator of MAPK activity, influencing diverse cellular functions.
  • Mechanisms controlling MEKK2 activity remain incompletely understood.
  • Previous work demonstrated MEKK2 binds and promotes ubiquitylation of paxillin, altering adhesion complexes.

Purpose of the Study:

  • To further investigate the interaction between MEKK2 and paxillin.
  • To elucidate the role of paxillin in MEKK2 activation.
  • To identify specific paxillin domains involved in MEKK2 regulation.

Main Methods:

  • Recombinant protein expression and purification.
  • In vitro kinase assays to measure MEKK2 auto-phosphorylation.
  • siRNA-mediated gene knockdown to assess MEKK2 activity in paxillin-deficient cells.
  • Analysis of protein-protein interactions using specific paxillin domains.

Main Results:

  • Recombinant paxillin induced MEKK2 auto-phosphorylation.
  • MEKK2 activity was significantly reduced in cells with depleted paxillin.
  • The paxillin Leucine-Rich Motif 1 (LD1) was sufficient for binding to MEKK2's N-terminal region and activating MEKK2.
  • Demonstrated paxillin association promotes MEKK2 activation.

Conclusions:

  • Paxillin directly promotes MEKK2 activation through its LD1 domain.
  • Established a novel bi-directional regulatory relationship between MEKK2 and paxillin.
  • Provides new insights into the regulation of MAPK signaling pathways.
Keywords:
Kinaseauto-inhibitory domainauto-phosphorylationphosphorylationscaffold

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