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IQGAP1 binds AMPK and is required for maximum AMPK activation.

Andrew C Hedman1, Zhigang Li1, Laëtitia Gorisse1

  • 1Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, USA.

The Journal of Biological Chemistry
|November 16, 2020
PubMed
Summary

IQGAP1 directly binds to AMPK and CaMKK2, modulating cellular energy homeostasis. IQGAP1 is crucial for activating AMP-activated protein kinase (AMPK) signaling in response to metabolic cues.

Keywords:
AMP-activated kinase (AMPK)IQGAP1calciumcalmodulin (CaM)homeostasismetabolic regulationmetforminprotein–protein interactionscaffold proteinsignaling

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Area of Science:

  • Cellular biology
  • Molecular signaling
  • Metabolic regulation

Background:

  • AMP-activated protein kinase (AMPK) is a key energy sensor regulating cellular metabolism.
  • IQGAP1 is a scaffold protein involved in various signaling pathways, with its role in metabolism poorly understood.
  • AMPK activation requires phosphorylation by LKB1 or CaMKK2.

Purpose of the Study:

  • To investigate the molecular mechanisms by which IQGAP1 influences AMPK signaling.
  • To determine if IQGAP1 interacts with AMPK and its activators.
  • To assess the role of IQGAP1 in metabolic regulation via AMPK.

Main Methods:

  • In vitro binding assays using fusion proteins.
  • siRNA-mediated gene silencing.
  • RT-PCR analysis.
  • Generation and analysis of IQGAP1 knockout mice.
  • Cellular assays measuring AMPK activation.

Main Results:

  • IQGAP1 directly binds to the AMPK α1 subunit and CaMKK2.
  • IQGAP1 facilitates the activation of AMPK by metformin and Ca2+.
  • IQGAP1-null cells exhibit reduced AMPK activation and impaired metabolic gene regulation.
  • IQGAP1 knockout mice show defects in fasting response and metabolic gene transcription.

Conclusions:

  • IQGAP1 is a novel modulator of AMPK signaling.
  • IQGAP1 plays a critical role in maintaining cellular energy homeostasis through AMPK.
  • IQGAP1 interacts with both AMPK and CaMKK2, integrating metabolic signals.