1. Cell Biology
Download icon

Comment on 'Orthogonal lipid sensors identify transbilayer asymmetry of plasma membrane cholesterol'

  1. Kevin C Courtney
  2. Karen YY Fung
  3. Frederick R Maxfield
  4. Gregory D Fairn  Is a corresponding author
  5. Xiaohui Zha  Is a corresponding author
  1. University of Ottawa, Canada
  2. St Michael's Hospital, Canada
  3. Weill Cornell Medical College, United States
  • Cited 13
  • Views 1,998
  • Annotations
Cite this article as: eLife 2018;7:e38493 doi: 10.7554/eLife.38493

Abstract

The plasma membrane in mammalian cells is rich in cholesterol. How cholesterol partitions between the two leaflets of the plasma membrane remains a matter of debate. Recently, Liu et al used domain 4 (D4) of perfringolysin O as a cholesterol sensor to argue that cholesterol is mostly in the exofacial leaflet (Liu et al., 2017). This conclusion was made by interpreting D4 binding in live cells using in vitro calibrations with liposomes. However, liposomes may be unfaithful in mimicking the plasma membrane, as we demonstrate here. Also, D4 binding is highly sensitive to the presence of cytosolic proteins. In addition, we find that a D4 variant, that requires >35 mol% cholesterol to bind to liposomes in vitro, does in fact bind to the cytoplasmic leaflet of the plasma membrane in a cholesterol-dependent manner. Thus, we believe, based on the current evidence, that it is unlikely that there is a significantly higher proportion of cholesterol in the exofacial leaflet of the plasma membrane compared to the cytosolic leaflet.

Data availability

All data generated or analysed during this study are included in the manuscript.

Article and author information

Author details

  1. Kevin C Courtney

    Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
    Competing interests
    The authors declare that no competing interests exist.
  2. Karen YY Fung

    Keenan Research Centre, St Michael's Hospital, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  3. Frederick R Maxfield

    Department of Biochemistry, Weill Cornell Medical College, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4396-8866
  4. Gregory D Fairn

    Keenan Research Centre, St Michael's Hospital, Toronto, Canada
    For correspondence
    fairng@smh.ca
    Competing interests
    The authors declare that no competing interests exist.
  5. Xiaohui Zha

    Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
    For correspondence
    xzha@ohri.ca
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2873-3073

Funding

Canadian Institutes of Health Research (Operating Grant MOP-130453)

  • Xiaohui Zha

Natural Sciences and Engineering Research Council of Canada (Discovery Grant RGPIN 40210-2013)

  • Xiaohui Zha

National Institutes of Health (R01 GM123462)

  • Frederick R Maxfield

Canadian Institutes of Health Research (MOP-133656)

  • Gregory D Fairn

The authors declare that there was no funding for this work

Reviewing Editor

  1. Arun Radhakrishnan, University of Texas Southwestern Medical Center, United States

Publication history

  1. Received: June 4, 2018
  2. Accepted: November 6, 2018
  3. Accepted Manuscript published: November 13, 2018 (version 1)
  4. Version of Record published: November 27, 2018 (version 2)
  5. Version of Record updated: November 29, 2018 (version 3)

Copyright

© 2018, Courtney et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 1,998
    Page views
  • 314
    Downloads
  • 13
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Download citations (links to download the citations from this article in formats compatible with various reference manager tools)

Open citations (links to open the citations from this article in various online reference manager services)

Further reading

    1. Cell Biology
    Julie Favre et al.
    Research Article

    Estrogen receptor alpha (ERα) activation by estrogens prevents atheroma through its nuclear action whereas plasma membrane-located ERα accelerates endothelial healing. The genetic deficiency of ERα was associated with a reduction in flow-mediated dilation (FMD) in one man. Here, we evaluated ex vivo the role of ERα on FMD of resistance arteries. FMD, but not agonist (acetylcholine, insulin)-mediated dilation, was reduced in male and female mice lacking ERα (Esr1-/- mice) compared to wild-type mice and was not dependent on the presence of estrogens. In C451A-ERα mice lacking membrane ERα, not in mice lacking AF2-dependent nuclear ERα actions, FMD was reduced, and restored by antioxidant treatments. Compared to wild-type mice, isolated perfused kidneys of C451A-ERα mice revealed a decreased flow-mediated nitrate production and an increased H2O2 production. Thus, endothelial membrane ERα promotes NO bioavailability through inhibition of oxidative stress and thereby participates in FMD in a ligand-independent manner.

    1. Biochemistry and Chemical Biology
    2. Cell Biology
    Rania Elsabrouty et al.
    Research Article

    UbiA prenyltransferase domain-containing protein-1 (UBIAD1) utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize the vitamin K2 subtype menaquinone-4. The prenyltransferase has emerged as a key regulator of sterol-accelerated, endoplasmic reticulum (ER)-associated degradation (ERAD) of HMG CoA reductase, the rate-limiting enzyme in synthesis of cholesterol and nonsterol isoprenoids including GGpp. Sterols induce binding of UBIAD1 to reductase, inhibiting its ERAD. Geranylgeraniol (GGOH), the alcohol derivative of GGpp, disrupts this binding and thereby stimulates ERAD of reductase and translocation of UBIAD1 to Golgi. We now show that overexpression of Type 1 polyisoprenoid diphosphate phosphatase (PDP1), which dephosphorylates GGpp and other isoprenyl pyrophosphates to corresponding isoprenols, abolishes protein geranylgeranylation as well as GGOH-induced ERAD of reductase and Golgi transport of UBIAD1. Conversely, these reactions are enhanced in the absence of PDP1. Our findings indicate PDP1-mediated hydrolysis of GGpp significantly contributes to a feedback mechanism that maintains optimal intracellular levels of the nonsterol isoprenoid.