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Mitochondrial amidoxime-reducing component 1 p.Ala165Thr increases protein degradation mediated by the proteasome

Tanmoy Dutta1, Kavitha Sasidharan1, Ester Ciociola1

  • 1Department of Molecular and Clinical Medicine, Institute of Medicine, The Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden.

Liver International : Official Journal of the International Association for the Study of the Liver
|February 20, 2024
PubMed
Abstract

Insights

The MARC1 A165T variant, linked to protection against metabolic dysfunction-associated steatotic liver disease (MASLD), shows reduced protein stability and accelerated degradation. Lowering hepatic MARC1 levels may offer a therapeutic strategy for MASLD.

Area of Science:

  • Biochemistry
  • Genetics
  • Hepatology

Background:

  • Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing global health issue lacking specific treatments.
  • A genetic variant (rs2642438 minor allele) in the MARC1 gene, resulting in an Ala165Thr substitution, is associated with protection against MASLD, but the underlying mechanisms are unclear.

Purpose of the Study:

  • To investigate the impact of the MARC1 p.Ala165Thr substitution on protein stability and subcellular localization.
  • To elucidate the molecular mechanisms behind the protective effect of the MARC1 variant against MASLD.

Main Methods:

  • Overexpression of wild-type (A165) and mutant (165T) MARC1 in mouse models and human hepatoma cell lines (HepG2, HuH-7).
  • Site-directed mutagenesis to generate various mutants at position 165.
  • Assessment of protein levels, ubiquitination status, and subcellular localization.

Main Results:

  • The MARC1 165T mutant exhibited significantly lower protein levels compared to the wild-type A165 form, both in vivo and in vitro.
  • Mutations at position 165 generally led to reduced protein stability.
  • The 165T mutant protein was found to be polyubiquitinated and degraded via the ubiquitin-proteasome pathway (lysine-48 linkage).
  • The substitution at position 165 did not alter the subcellular localization of MARC1.

Conclusions:

  • Alanine at position 165 of MARC1 is critical for protein stability.
  • The threonine substitution (p.Ala165Thr) results in a hypomorphic MARC1 variant with decreased protein levels.
  • Reduced hepatic MARC1 protein levels may represent a viable therapeutic approach for managing MASLD.
Keywords:
MASHMASLDMOSC domain‐containing protein 1MTARC1NAFLDNASHfatty livermolybdenum cofactor (MOCO) sulfurase C‐terminal domain‐containing protein 1 (MOSC1)

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