Cited by 137Cholesterol and Lipid MetabolismLipoproteins and Cardiovascular HealthLipid metabolism and disorders

Feedback Regulation of Cholesterol Uptake by the LXR–IDOL–LDLR Axis

Open access
Zhang, Li, Reue, Karen, Fong, Loren G., Young, Stephen G., Tontonoz, Peter·2012·Arteriosclerosis, Thrombosis, and Vascular Biology

Abstract

Inducible degrader of the low-density lipoprotein receptor (IDOL) is an E3 ubiquitin ligase that mediates the ubiquitination and degradation of the low-density lipoprotein receptor (LDLR). IDOL expression is controlled at the transcriptional level by the cholesterol-sensing nuclear receptor liver X receptor (LXR). In response to rising cellular sterol levels, activated LXR induces IDOL production, thereby limiting further uptake of exogenous cholesterol through the LDLR pathway. The LXR–IDOL–LDLR mechanism for feedback inhibition of cholesterol uptake is independent of and complementary to the sterol regulatory element–binding protein pathway. Since the initial description of the LXR–IDOL pathway, biochemical studies have helped to define the structural basis for both IDOL target recognition and LDLR ubiquitin transfer. Recent work has also suggested links between IDOL and human lipid metabolism.

AI snapshot

Written from the paper’s full text.

TL;DR

This review describes the LXR–IDOL–LDLR axis, in which LXR-induced IDOL ubiquitinates and degrades LDLR (and VLDLR/ApoER2), providing feedback inhibition of cholesterol uptake independent of SREBP. It synthesizes structural, cellular, mouse, and human genetic evidence and highlights unresolved questions about IDOL in human lipid metabolism.

Key findings

  • IDOL is an E3 ubiquitin ligase whose promoter is directly regulated by LXR/RXR; LXR agonists induce IDOL and reduce LDLR protein without changing LDLR mRNA, and IDOL-null ES cells have higher basal LDLR protein and internalize LDL more readily. In IDOL-null ES cells, LXR agonists have no effect on LDLR protein or LDL uptake.
  • The LXR–IDOL pathway acts acutely: oxysterol activation reduces plasma membrane LDLR protein in WT cells with a half-maximum effect as early as 2 h, whereas in IDOL-deficient cells LDLR downregulation is slower and only via SREBP-mediated transcriptional suppression.
  • IDOL recognizes targets through its FERM F3b PTB-like domain binding a WxxKNxxSI/MxF motif in cytoplasmic tails; key LDLR residues include W813, I821, and F823, and IDOL residues Y265/T269 (with H272 implicated independently) are important. UBE2D family members (UBE2D1–4) support IDOL autoubiquitination and LDLR ubiquitination, while UBE2N/UBE2V1 has also been implicated.
  • Human genetics: the N342S SNP in IDOL alters LDLR degradation (N342 more active than S342); in a cohort of Mexican hyperlipidemic patients, subjects homozygous for the less active S342 allele exhibited 7% lower plasma cholesterol. GWAS have linked IDOL-region SNPs to total cholesterol, LDL-cholesterol, and statin response.

Methods

  • Narrative review; no new primary data are reported. It synthesizes published biochemical, cell-culture, mouse, structural, GWAS, and human cohort studies.
  • Main analysis is qualitative integration of cited literature, including IDOL-deficient ES cells, LXR agonist treatments, adenoviral overexpression, mutagenesis, and in vitro ubiquitination assays.
  • No systematic review methods, search strategy, or meta-analysis are reported.

Limitations

  • Stated: the role of IDOL in human cholesterol metabolism remains an open question; no complete loss-of-function or dominant-negative IDOL alleles have been described, so effects of dramatic changes in IDOL activity are unknown, and whether pharmacologic inhibition of IDOL-dependent LDLR degradation would substantially affect human lipid levels is unknown.
  • Stated: the relative importance of E2 enzymes (UBE2D vs UBE2N/UBE2V1) and of K48 vs K63 ubiquitin linkages in IDOL function remains to be clarified; the role of IDOL in brain development and function requires further study; and the mechanism for weaker IDOL responsiveness to LXR in mouse liver versus human hepatocyte cell lines is unknown.
  • Evident: as a review, conclusions depend on previously published studies and no new experimental validation is presented.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1161/atvbaha.112.250571

Cites

44 of 44 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

3 of 11 cited sources checked · 3 supported · 0 flagged

  • Findingcitation

    The IDOL FERM domain binds directly to a recognition sequence in the cytoplasmic tails of its three known targets: LDLR, VLDLR, and ApoER2.

    “Indeed, we showed that the IDOL FERM domain binds directly to a recognition sequence in the cytoplasmic tails of its three known targets–LDLR, VLDLR, and ApoER2 (Figure 1).31”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [31] Calkin AC Goult BT Zhang L Fairall L Hong C Schwabe JW Tontonoz P Ferm-dependent e3 ligase recognition is a conserved mechanism for targeted degradation of lipoprotein receptors. Proc Natl Acad Sci U S A 2011 108 20107 20112 22109552 PMC3250164

      Not checked in the free run.

  • Findingcitation

    In a cohort of Mexican hyperlipidemic patients, subjects homozygous for the less active S342 allele exhibited 7% lower plasma cholesterol levels.

    “Furthermore, in a cohort of Mexican hyperlipidemic patients, subjects homozygous for the less active S342 allele exhibited a 7% lower plasma cholesterol levels, a result that would be consistent with increased hepatic LDLR expression.43”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [43] Weissglas-Volkov D Calkin AC Tusie-Luna T Sinsheimer JS Zelcer N Riba L Tino AM Ordonez-Sanchez ML Cruz-Bautista I Aguilar-Salinas CA Tontonoz P Pajukanta P The n342s mylip polymorphism is associated with high total cholesterol and increased ldl receptor degradation in humans. J Clin Invest 2011 121 3062 3071 21765216 PMC3148733

      Not checked in the free run.

  • Findingown data

    E3 ubiquitin ligase MYLIP (renamed IDOL) is the mediator of the effects of LXR on the LDLR.

    “Through transcription profiling studies and candidate gene analyses, we identified the E3 ubiquitin ligase MYLIP (re-named IDOL) as the mediator of the effects of LXR on the LDLR.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Zelcer N Hong C Boyadjian R Tontonoz P Lxr regulates cholesterol uptake through idol-dependent ubiquitination of the ldl receptor. Science 2009 325 100 104 19520913 PMC2777523

      Not checked in the free run.

  • Findingcitation

    Treatment of macrophages and hepatocytes with the LXR agonists GW3965 and T0901317 markedly inhibits the binding and uptake of LDL by these cells.

    “Treatment of various cell types including macrophages and hepatocytes with the LXR agonists GW3965 and T0901317 markedly inhibits the binding and uptake of LDL by these cells.5”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Zelcer N Hong C Boyadjian R Tontonoz P Lxr regulates cholesterol uptake through idol-dependent ubiquitination of the ldl receptor. Science 2009 325 100 104 19520913 PMC2777523

      Not checked in the free run.

  • Interpretationreasoning

    In response to rising cellular sterol levels, activated LXR induces IDOL production, thereby limiting further uptake of exogenous cholesterol through the LDLR pathway.

    “In response to rising cellular sterol levels, activated LXR induces IDOL production, thereby limiting further uptake of exogenous cholesterol through the LDLR pathway.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Zelcer N Hong C Boyadjian R Tontonoz P Lxr regulates cholesterol uptake through idol-dependent ubiquitination of the ldl receptor. Science 2009 325 100 104 19520913 PMC2777523

      Not checked in the free run.

  • May combine two claims. 3
  • May combine two claims.

    Findingcitation

    Cells lacking IDOL expression exhibit higher basal levels of LDLR protein and internalize LDL more readily than wild-type cells, and LXR agonists have no effect on LDLR protein or LDL uptake in IDOL-null ES cells.

    “Cells lacking IDOL expression exhibit higher basal levels of LDLR protein and internalize LDL more readily than wild-type cells.32”
    • Also stated in: § Complementary regulation of the LDLR by the SREBP and the IDOL pathways · hedged
      “Furthermore, synthetic LXR agonists have no effect on protein levels of the LDLR or the uptake of LDL in IDOL-null ES cells, indicating that IDOL is absolutely required for LXR's effect on the LDLR.32”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [32] Scotti E Hong C Yoshinaga Y Tu Y Hu Y Zelcer N Boyadjian R de Jong PJ Young SG Fong LG Tontonoz P Targeted disruption of the idol gene alters cellular regulation of the low-density lipoprotein receptor by sterols and liver x receptor agonists. Molecular and cellular biology 2011 31 1885 1893 21343340 PMC3133228 source
  • May combine two claims.

    Interpretationcitation

    The LXR-IDOL-LDLR mechanism for feedback inhibition of cholesterol uptake is independent of and complementary to the SREBP pathway.

    “The LXR–IDOL–LDLR mechanism for feedback inhibition of cholesterol uptake is independent of and complementary to the SREBP pathway.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [32] Scotti E Hong C Yoshinaga Y Tu Y Hu Y Zelcer N Boyadjian R de Jong PJ Young SG Fong LG Tontonoz P Targeted disruption of the idol gene alters cellular regulation of the low-density lipoprotein receptor by sterols and liver x receptor agonists. Molecular and cellular biology 2011 31 1885 1893 21343340 PMC3133228 source
  • May combine two claims.

    Findingcitation

    PCSK9 is still able to stimulate LDLR degradation in cells lacking IDOL, indicating that IDOL and PCSK9 function in complementary but independent pathways.

    “Furthermore, PCSK9 is still able to stimulate LDLR degradation in cells lacking IDOL, indicating that IDOL and PCSK9 function in complementary but independent pathways.32”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [32] Scotti E Hong C Yoshinaga Y Tu Y Hu Y Zelcer N Boyadjian R de Jong PJ Young SG Fong LG Tontonoz P Targeted disruption of the idol gene alters cellular regulation of the low-density lipoprotein receptor by sterols and liver x receptor agonists. Molecular and cellular biology 2011 31 1885 1893 21343340 PMC3133228 source
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Authors
Zhang, L., Reue, K., Fong, L. G., Young, S. G., & Tontonoz, P.
Affiliations
Howard Hughes Medical Institute (US)
Venue
Arteriosclerosis, Thrombosis, and Vascular Biology
Published
2012-11
Volume
32
Issue
11
Pages
2541-2546
ISSN
  • 1079-5642 (ISSN-L)
  • 1524-4636
OpenAlex
W2157159684
Cited by
137
References
44
Citations by year
2026: 5 · 2025: 7 · 2024: 19 · 2023: 7 · 2022: 13 · 2021: 10 · 2020: 11 · 2019: 5 · 2018: 7 · 2017: 4 · 2016: 18 · 2015: 11 · 2014: 9 · 2013: 11
FWCI
1.91
Type
journal article
Language
en
Open access
Locations
  • Arteriosclerosis Thrombosis and Vascular Biology (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Howard Hughes Medical Institute
  • National Institutes of Health (HL090553)
  • National Heart, Lung, and Blood Institute (P01HL090553, HL066088, R01HL066088)
Topics
  • Health Sciences › Medicine › Surgery › Cholesterol and Lipid Metabolism
  • Health Sciences › Medicine › Surgery › Lipoproteins and Cardiovascular Health
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Lipid metabolism and disorders
Keywords
liver X receptor, idols, LDL receptor, cholesterol absorption, feedback regulation, E3 ubiquitin ligase, LDLR degradation, SREBP, cholesterol sensing, lipid metabolism, ubiquitination
MeSH terms
Liver X Receptors, Animals, Biological Transport, Cholesterol, Humans, Liver, Receptors, LDL, Substrate Specificity, Gene Expression Regulation, Enzymologic, Feedback, Physiological, Ubiquitin-Protein Ligases, Atherosclerosis, Ubiquitination, Orphan Nuclear Receptors

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