The ubiquitin E3 ligase HRD1 restricts hepatic lipid metabolism by suppressing PPARα-driven m6A RNA modification

🥉 Top 5% JournalJan 6, 2026Science signaling

The protein HRD1 limits liver fat metabolism by reducing PPARα-related m6A RNA changes

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Hepatic lipid accumulation was decreased in mice with a deficiency of HRD1 when fed a high-fat diet.

The endoplasmic reticulum-localized E3 ubiquitin ligase HRD1 is associated with increased lipid accumulation in the liver.
m6A RNA modification and the expression of related mRNAs are regulated by circadian rhythms and nutrient availability.
HRD1 and the m6A writer METTL14 have opposing roles in modifying and expressing mRNAs related to fatty acid metabolism.
Deficiency of METTL14 or YTHDF resulted in increased hepatic lipid accumulation in mice fed normal chow.
HRD1 promotes the degradation of PPARα, which plays a role in the regulation of liver lipid metabolism.

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Hepatic lipid metabolism is regulated by circadian rhythms and dynamically responds to nutrient availability, such that lipid synthesis, oxidation, and storage are temporally coordinated. We demonstrated that the endoplasmic reticulum (ER)-localized E3 ubiquitin ligase HRD1 stimulated lipid accumulation in the liver by decreasing the-methyladenosine (m6A) methylation and expression of mRNAs encoding factors involved in lipid metabolism. In mouse livers, m6A RNA modification and the expression of mRNAs encoding the m6A writer METTL14 and the m6A reader YTHDF3 were under circadian control and inversely correlated with the abundance of HRD1. m6A RNA sequencing analyses revealed that HRD1 and the m6A writer METTL14 had opposing roles in the m6A modification and expression of mRNAs encoding factors involved in fatty acid metabolism. In vivo, hepatic lipid accumulation and triglyceride amounts were decreased in mice with hepatic HRD1 deficiency fed a high-fat diet but increased in mice with hepatic METTL14 or YTHDF deficiency fed normal chow. Mechanistically, HRD1 mediated the polyubiquitination and degradation of PPARα, which transcriptionally activatedandexpression in the liver. Our work identifies a pathway regulated by circadian rhythms or nutrients in which HRD1 promotes the degradation of PPARα to decrease the m6A modification and expression of hepatic mRNAs encoding factors involved in lipid metabolism. N METTL14YTHDF3 6

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