1. Cell Biology
  2. Developmental Biology

Cholesterol accessibility at the ciliary membrane controls Hedgehog signaling

  1. Maia Kinnebrew
  2. Ellen Jean Iverson
  3. Bhaven B Patel
  4. Ganesh V Pusapati
  5. Jennifer H Kong
  6. Kristen A Johnson
  7. Giovanni Luchetti
  8. Kaitlyn M Eckert
  9. Jeffrey G McDonald
  10. Douglas F Covey
  11. Christian Siebold
  12. Arun Radhakrishnan  Is a corresponding author
  13. Rajat Rohatgi  Is a corresponding author
  1. Stanford University School of Medicine, United States
  2. Stanford University School of medicine, United States
  3. University of Texas Southwestern Medical Center, United States
  4. Washington University School of Medicine, United States
  5. University of Oxford, United Kingdom
https://doi.org/10.7554/eLife.50051
Share this article
Cite this article
  1. Maia Kinnebrew
  2. Ellen Jean Iverson
  3. Bhaven B Patel
  4. Ganesh V Pusapati
  5. Jennifer H Kong
  6. Kristen A Johnson
  7. Giovanni Luchetti
  8. Kaitlyn M Eckert
  9. Jeffrey G McDonald
  10. Douglas F Covey
  11. Christian Siebold
  12. Arun Radhakrishnan
  13. Rajat Rohatgi
(2019)
Cholesterol accessibility at the ciliary membrane controls Hedgehog signaling
eLife 8:e50051.
https://doi.org/10.7554/eLife.50051
  2. Download BibTeX
  3. Download .RIS

Abstract

Previously we proposed that transmission of the Hedgehog signal across the plasma membrane by Smoothened is triggered by its interaction with cholesterol (Luchetti et al., 2016). But how is cholesterol, an abundant lipid, regulated tightly enough to control a signaling system that can cause birth defects and cancer? Using toxin-based sensors that distinguish between distinct pools of cholesterol, we find that Smoothened activation and Hedgehog signaling are driven by a biochemically-defined, small fraction of membrane cholesterol, termed accessible cholesterol. Increasing cholesterol accessibility by depletion of sphingomyelin, which sequesters cholesterol in complexes, amplifies Hedgehog signaling. Hedgehog ligands increase cholesterol accessibility in the membrane of the primary cilium by inactivating the transporter-like protein Patched 1. Trapping this accessible cholesterol blocks Hedgehog signal transmission across the membrane. Our work shows that the organization of cholesterol in the ciliary membrane can be modified by extracellular ligands to control the activity of cilia-localized signaling proteins.

Data availability

All data generated or analyzed are included in Supplementary Files 1-5 in this manuscript.

Article and author information

Author details

  1. Maia Kinnebrew

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7344-8231

  2. Ellen Jean Iverson

    Department of Biochemistry, Stanford University School of medicine, Stanford, United States
    Competing interests
    No competing interests declared.

  3. Bhaven B Patel

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    Competing interests
    No competing interests declared.

  4. Ganesh V Pusapati

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    Competing interests
    No competing interests declared.

  5. Jennifer H Kong

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    Competing interests
    No competing interests declared.

  6. Kristen A Johnson

    Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    No competing interests declared.

  7. Giovanni Luchetti

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    Competing interests
    No competing interests declared.

  8. Kaitlyn M Eckert

    Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    No competing interests declared.

  9. Jeffrey G McDonald

    Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    No competing interests declared.

  10. Douglas F Covey

    Department of Developmental Biology, Washington University School of Medicine, St Louis, United States
    Competing interests
    No competing interests declared.

  11. Christian Siebold

    Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6635-3621

  12. Arun Radhakrishnan

    Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
    For correspondence
    arun.radhakrishnan@utsouthwestern.edu
    Competing interests
    Arun Radhakrishnan, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7266-7336

  13. Rajat Rohatgi

    Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
    For correspondence
    rrohatgi@stanford.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7609-8858

Funding

National Institutes of Health (GM118082)

  • Rajat Rohatgi

American Heart Association (14POST20370057)

  • Ganesh V Pusapati

American Heart Association (19POST34380734)

  • Jennifer H Kong

National Institutes of Health (GM13251801)

  • Jennifer H Kong

Ford Foundation (Pre-doctoral Fellowship)

  • Giovanni Luchetti

National Institutes of Health (GM106078)

  • Rajat Rohatgi

National Institutes of Health (HL20948)

  • Kristen A Johnson
  • Jeffrey G McDonald
  • Arun Radhakrishnan

Welch Foundation (I-1793)

  • Kristen A Johnson
  • Arun Radhakrishnan

Cancer Research UK (C20724/A14414)

  • Christian Siebold

Cancer Research UK (C20724/A26752)

  • Christian Siebold

European Research Council (647278)

  • Christian Siebold

National Science Foundation (Pre-doctoral Fellowship)

  • Maia Kinnebrew

National Science Foundation (Pre-doctoral Fellowship)

  • Ellen Jean Iverson

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Duojia Pan, UT Southwestern Medical Center and HHMI, United States

Version history

  1. Received: July 12, 2019
  2. Accepted: October 25, 2019
  3. Accepted Manuscript published: October 28, 2019 (version 1)
  4. Accepted Manuscript updated: October 30, 2019 (version 2)
  5. Version of Record published: November 12, 2019 (version 3)
  6. Version of Record updated: November 15, 2019 (version 4)

Copyright

© 2019, Kinnebrew 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

  • 6,338
    Page views
  • 1,133
    Downloads
  • 80
    Citations

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

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)

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

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

  1. Maia Kinnebrew
  2. Ellen Jean Iverson
  3. Bhaven B Patel
  4. Ganesh V Pusapati
  5. Jennifer H Kong
  6. Kristen A Johnson
  7. Giovanni Luchetti
  8. Kaitlyn M Eckert
  9. Jeffrey G McDonald
  10. Douglas F Covey
  11. Christian Siebold
  12. Arun Radhakrishnan
  13. Rajat Rohatgi
(2019)
Cholesterol accessibility at the ciliary membrane controls Hedgehog signaling
eLife 8:e50051.
https://doi.org/10.7554/eLife.50051

Categories and tags

Further reading

    1. Cell Biology
    2. Developmental Biology

    Patched 1 reduces the accessibility of cholesterol in the outer leaflet of membranes

    Maia Kinnebrew, Giovanni Luchetti ... Rajat Rohatgi
    Research Advance Updated

    A long-standing mystery in vertebrate Hedgehog signaling is how Patched 1 (PTCH1), the receptor for Hedgehog ligands, inhibits the activity of Smoothened, the protein that transmits the signal across the membrane. We previously proposed (Kinnebrew et al., 2019) that PTCH1 inhibits Smoothened by depleting accessible cholesterol from the ciliary membrane. Using a new imaging-based assay to directly measure the transport activity of PTCH1, we find that PTCH1 depletes accessible cholesterol from the outer leaflet of the plasma membrane. This transport activity is terminated by binding of Hedgehog ligands to PTCH1 or by dissipation of the transmembrane potassium gradient. These results point to the unexpected model that PTCH1 moves cholesterol from the outer to the inner leaflet of the membrane in exchange for potassium ion export in the opposite direction. Our study provides a plausible solution for how PTCH1 inhibits SMO by changing the organization of cholesterol in membranes and establishes a general framework for studying how proteins change cholesterol accessibility to regulate membrane-dependent processes in cells.

    1. Biochemistry and Chemical Biology
    2. Developmental Biology

    Cholesterol activates the G-protein coupled receptor Smoothened to promote Hedgehog signaling

    Giovanni Luchetti, Ria Sircar ... Rajat Rohatgi
    Research Article Updated

    Cholesterol is necessary for the function of many G-protein coupled receptors (GPCRs). We find that cholesterol is not just necessary but also sufficient to activate signaling by the Hedgehog (Hh) pathway, a prominent cell-cell communication system in development. Cholesterol influences Hh signaling by directly activating Smoothened (SMO), an orphan GPCR that transmits the Hh signal across the membrane in all animals. Unlike many GPCRs, which are regulated by cholesterol through their heptahelical transmembrane domains, SMO is activated by cholesterol through its extracellular cysteine-rich domain (CRD). Residues shown to mediate cholesterol binding to the CRD in a recent structural analysis also dictate SMO activation, both in response to cholesterol and to native Hh ligands. Our results show that cholesterol can initiate signaling from the cell surface by engaging the extracellular domain of a GPCR and suggest that SMO activity may be regulated by local changes in cholesterol abundance or accessibility.

    1. Cell Biology

    Rab12 is a regulator of LRRK2 and its activation by damaged lysosomes

    Xiang Wang, Vitaliy V Bondar ... Anastasia G Henry
    Short Report Updated

    Leucine-rich repeat kinase 2 (LRRK2) variants associated with Parkinson’s disease (PD) and Crohn’s disease lead to increased phosphorylation of its Rab substrates. While it has been recently shown that perturbations in cellular homeostasis including lysosomal damage can increase LRRK2 activity and localization to lysosomes, the molecular mechanisms by which LRRK2 activity is regulated have remained poorly defined. We performed a targeted siRNA screen to identify regulators of LRRK2 activity and identified Rab12 as a novel modulator of LRRK2-dependent phosphorylation of one of its substrates, Rab10. Using a combination of imaging and immunopurification methods to isolate lysosomes, we demonstrated that Rab12 is actively recruited to damaged lysosomes and leads to a local and LRRK2-dependent increase in Rab10 phosphorylation. PD-linked variants, including LRRK2 R1441G and VPS35 D620N, lead to increased recruitment of LRRK2 to the lysosome and a local elevation in lysosomal levels of pT73 Rab10. Together, these data suggest a conserved mechanism by which Rab12, in response to damage or expression of PD-associated variants, facilitates the recruitment of LRRK2 and phosphorylation of its Rab substrate(s) at the lysosome.