2. Academic Validation
  3. The Endoplasmic Reticulum Cargo Receptor SURF4 Facilitates Efficient Erythropoietin Secretion

The Endoplasmic Reticulum Cargo Receptor SURF4 Facilitates Efficient Erythropoietin Secretion

  • Mol Cell Biol. 2020 Nov 6;40(23):e00180-20. doi: 10.1128/MCB.00180-20.
Zesen Lin 1,  Richard King 2,  Vi Tang 3,  Greggory Myers 4,  Ginette Balbin-Cuesta 5 6,  Ann Friedman 2,  Beth McGee 2,  Karl Desch 5 7,  Ayse Bilge Ozel 8,  David Siemieniak 9,  Pavan Reddy 2 5 10,  Brian Emmer 2,  Rami Khoriaty 11 4 5 10
Affiliations

Affiliations

  • 1 Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.
  • 2 Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
  • 3 Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA.
  • 4 Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA.
  • 5 Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, USA.
  • 6 Medical Scientist Training Program, University of Michigan, Ann Arbor, Michigan, USA.
  • 7 Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA.
  • 8 Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA.
  • 9 Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA.
  • 10 University of Michigan Rogel Cancer Center, Ann Arbor, Michigan, USA.
  • 11 Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA ramikhor@umich.edu.
PMID: 32989016 DOI: 10.1128/MCB.00180-20
Abstract

Erythropoietin (EPO) stimulates erythroid differentiation and maturation. Though the transcriptional regulation of EPO has been well studied, the molecular determinants of EPO secretion remain unknown. Here, we generated a HEK293T reporter cell line that provides a quantifiable and selectable readout of intracellular EPO levels and performed a genome-scale CRISPR screen that identified SURF4 as an important mediator of EPO secretion. Targeting SURF4 with multiple independent single guide RNAs (sgRNAs) resulted in intracellular accumulation and extracellular depletion of EPO. Both of these phenotypes were rescued by expression of SURF4 cDNA. Additionally, we found that disruption of SURF4 resulted in accumulation of EPO in the endoplasmic reticulum (ER) compartment and that SURF4 and EPO physically interact. Furthermore, SURF4 disruption in Hep3B cells also caused a defect in the secretion of endogenous EPO under conditions mimicking hypoxia, ruling out an artifact of heterologous overexpression. This work demonstrates that SURF4 functions as an ER cargo receptor that mediates the efficient secretion of EPO. Our findings also suggest that modulating SURF4 may be an effective treatment for disorders of erythropoiesis that are driven by aberrant EPO levels. Finally, we show that SURF4 overexpression results in increased secretion of EPO, suggesting a new strategy for more efficient production of recombinant EPO.

Keywords

CRISPR screen; erythropoiesis; erythropoietin.

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