1. Cell Biology

Hepatic inactivation of murine Surf4 results in marked reduction in plasma cholesterol

  1. Vi T Tang
  2. Joseph McCormick
  3. Bolin Xu
  4. Yawei Wang
  5. Huan Fang
  6. Xiao Wang
  7. David Siemieniak
  8. Rami Khoriaty
  9. Brian T Emmer
  10. Xiao-Wei Chen
  11. David Ginsburg  Is a corresponding author
  1. University of Michigan-Ann Arbor, United States
  2. Peking University, China
https://doi.org/10.7554/eLife.82269
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  1. Vi T Tang
  2. Joseph McCormick
  3. Bolin Xu
  4. Yawei Wang
  5. Huan Fang
  6. Xiao Wang
  7. David Siemieniak
  8. Rami Khoriaty
  9. Brian T Emmer
  10. Xiao-Wei Chen
  11. David Ginsburg
(2022)
Hepatic inactivation of murine Surf4 results in marked reduction in plasma cholesterol
eLife 11:e82269.
https://doi.org/10.7554/eLife.82269
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Abstract

PCSK9 negatively regulates low-density lipoprotein receptor (LDLR) abundance on the cell surface, leading to decreased hepatic clearance of LDL particles and increased levels of plasma cholesterol. We previously identified SURF4 as a cargo receptor that facilitates PCSK9 secretion in HEK293T cells (Emmer et al., 2018). Here, we generated hepatic SURF4-deficient mice (Surf4fl/fl Alb-Cre+) to investigate the physiologic role of SURF4 in vivo. Surf4fl/fl Alb-Cre+ mice exhibited normal viability, gross development, and fertility. Plasma PCSK9 levels were reduced by ~60% in Surf4fl/fl Alb-Cre+ mice, with a corresponding ~50% increase in steady state LDLR protein abundance in the liver, consistent with SURF4 functioning as a cargo receptor for PCSK9. Surprisingly, these mice exhibited a marked reduction in plasma cholesterol and triglyceride levels out of proportion to the partial increase in hepatic LDLR abundance. Detailed characterization of lipoprotein metabolism in these mice instead revealed a severe defect in hepatic lipoprotein secretion, consistent with prior reports of SURF4 also promoting the secretion of apolipoprotein B. Despite a small increase in liver mass and lipid content, histologic evaluation revealed no evidence of steatohepatitis or fibrosis in Surf4fl/fl Alb-Cre+ mice. Acute depletion of hepatic SURF4 by CRISPR/Cas9 or liver-targeted siRNA in adult mice confirms these findings. Together, these data support the physiologic significance of SURF4 in the hepatic secretion of PCSK9 and APOB-containing lipoproteins and its potential as a therapeutic target in atherosclerotic cardiovascular diseases.

Data availability

Sequencing data have been deposited in GEO (accession number GSE214393) . All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for figure 1, figure 2, figure 3, and figure 6-figure supplement 1.

The following data sets were generated

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Author details

  1. Vi T Tang

    Department of Molecular and Integrative Physiology, University of Michigan-Ann Arbor, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Joseph McCormick

    Life Sciences Institute, University of Michigan-Ann Arbor, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Bolin Xu

    College of Future Technology, Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.

  4. Yawei Wang

    Center for Life Sciences, Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.

  5. Huan Fang

    College of Future Technology, Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.

  6. Xiao Wang

    College of Future Technology, Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.

  7. David Siemieniak

    Life Sciences Institute, University of Michigan-Ann Arbor, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.

  8. Rami Khoriaty

    Department of Internal Medicine, University of Michigan-Ann Arbor, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.

  9. Brian T Emmer

    Department of Internal Medicine, University of Michigan-Ann Arbor, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7365-1021

  10. Xiao-Wei Chen

    State Key Laboratory of Membrane Biology, Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4564-5120

  11. David Ginsburg

    Life Sciences Institute, University of Michigan-Ann Arbor, Ann Arbor, United States
    For correspondence
    ginsburg@umich.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6436-8942

Funding

American Heart Association (20PRE35210706)

  • Vi T Tang

University of Michigan (Rackham Predoctoral Fellowship)

  • Vi T Tang

Howard Hughes Medical Institute

  • David Ginsburg

National Institutes of Health (R35HL135793)

  • David Ginsburg

National Institutes of Health (R01HL148333)

  • Rami Khoriaty

National Institutes of Health (R01HL157062)

  • Rami Khoriaty

National Institutes of Health (K08HL148552)

  • Brian T Emmer

National Key Research and Development Program of China (2018YFA0506900)

  • Xiao-Wei Chen

National Science Foundation of China (91954001)

  • Xiao-Wei Chen

National Science Foundation of China (31571213)

  • Xiao-Wei Chen

National Science Foundation of China (31521062)

  • Xiao-Wei Chen

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

Ethics

Animal experimentation: All animal care and use complied with the Principles of Laboratory and Animal Care established by the National Society for Medical Research. All animal protocols in this study have been approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Michigan (protocol number PRO00009304) and the IACUC of Peking University.

Copyright

© 2022, Tang 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.

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  1. Vi T Tang
  2. Joseph McCormick
  3. Bolin Xu
  4. Yawei Wang
  5. Huan Fang
  6. Xiao Wang
  7. David Siemieniak
  8. Rami Khoriaty
  9. Brian T Emmer
  10. Xiao-Wei Chen
  11. David Ginsburg
(2022)
Hepatic inactivation of murine Surf4 results in marked reduction in plasma cholesterol
eLife 11:e82269.
https://doi.org/10.7554/eLife.82269

Share this article

https://doi.org/10.7554/eLife.82269

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Further reading

    1. Cell Biology

    The cargo receptor SURF4 promotes the efficient cellular secretion of PCSK9

    Brian T Emmer, Geoffrey G Hesketh ... David Ginsburg
    Research Article

    PCSK9 is a secreted protein that regulates plasma cholesterol levels and cardiovascular disease risk. Prior studies suggested the presence of an ER cargo receptor that recruits PCSK9 into the secretory pathway, but its identity has remained elusive. Here, we apply a novel approach that combines proximity-dependent biotinylation and proteomics together with genome-scale CRISPR screening to identify SURF4, a homologue of the yeast cargo receptor Erv29p, as a primary mediator of PCSK9 secretion in HEK293T cells. The functional contribution of SURF4 to PCSK9 secretion was confirmed with multiple independent SURF4-targeting sgRNAs, clonal SURF4-deficient cell lines, and functional rescue with SURF4 cDNA. SURF4 was found to localize to the early secretory pathway where it physically interacts with PCSK9. Deletion of SURF4 resulted in ER accumulation and decreased extracellular secretion of PCSK9. These findings support a model in which SURF4 functions as an ER cargo receptor mediating the efficient cellular secretion of PCSK9.