Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner

Research output: Contribution to journalArticle

Abstract

Sterol regulatory element-binding protein (SREBP) transcription factors are central regulators of cellular lipid homeostasis and activate expression of genes required for fatty acid, triglyceride, and cholesterol synthesis and uptake. SREBP cleavage activating protein (SCAP) plays an essential role in SREBP activation by mediating endoplasmic reticulum (ER)-to-Golgi transport of SREBP. In the Golgi, membrane-bound SREBPs are cleaved sequentially by the site-1 and site-2 proteases. Recent studies have shown a requirement for the SREBP pathway in the development of fatty liver disease and tumor growth, making SCAP a target for drug development. Fatostatin is a chemical inhibitor of the SREBP pathway that directly binds SCAP and blocks its ERto-Golgi transport. In this study, we determined that fatostatin blocks ER exit of SCAP and showed that inhibition is independent of insulin-induced gene proteins, which function to retain the SCAP-SREBP complex in the ER. Fatostatin potently inhibited cell growth, but unexpectedly exogenous lipids failed to rescue proliferation of fatostatin-treated cells. Furthermore, fatostatin inhibited growth of cells lacking SCAP. Using a vesicular stomatitis virus glycoprotein (VSVG) trafficking assay, we demonstrated that fatostatin delays ERto-Golgi transport of VSVG. In summary, fatostatin inhibited SREBP activation, but fatostatin additionally inhibited cell proliferation through both lipid-independent and SCAPindependent mechanisms, possibly by general inhibition of ER-to-Golgi transport.-Shao, W., C. E. Machamer, and P. J. Espenshade. Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner. J. Lipid Res. 2016. 57: 1564-1573.

Original languageEnglish (US)
Pages (from-to)1564-1573
Number of pages10
JournalJournal of Lipid Research
Volume57
Issue number8
DOIs
StatePublished - Aug 1 2016

Fingerprint

Sterol Regulatory Element Binding Proteins
Cell growth
Endoplasmic Reticulum
Growth
Lipids
Vesicular Stomatitis
Viruses
Glycoproteins
Chemical activation
Cells
SREBP cleavage-activating protein
fatostatin
Lipoma
Cell proliferation
Fatty Liver
Liver
Liver Diseases
Tumors
Assays
Triglycerides

Keywords

  • Endoplasmic reticulum
  • Endoplasmic reticulum-to-golgi transport
  • Sterol regulatory element-binding protein
  • Sterol regulatory element-binding protein cleavage activating protein

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology

Cite this

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title = "Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner",
abstract = "Sterol regulatory element-binding protein (SREBP) transcription factors are central regulators of cellular lipid homeostasis and activate expression of genes required for fatty acid, triglyceride, and cholesterol synthesis and uptake. SREBP cleavage activating protein (SCAP) plays an essential role in SREBP activation by mediating endoplasmic reticulum (ER)-to-Golgi transport of SREBP. In the Golgi, membrane-bound SREBPs are cleaved sequentially by the site-1 and site-2 proteases. Recent studies have shown a requirement for the SREBP pathway in the development of fatty liver disease and tumor growth, making SCAP a target for drug development. Fatostatin is a chemical inhibitor of the SREBP pathway that directly binds SCAP and blocks its ERto-Golgi transport. In this study, we determined that fatostatin blocks ER exit of SCAP and showed that inhibition is independent of insulin-induced gene proteins, which function to retain the SCAP-SREBP complex in the ER. Fatostatin potently inhibited cell growth, but unexpectedly exogenous lipids failed to rescue proliferation of fatostatin-treated cells. Furthermore, fatostatin inhibited growth of cells lacking SCAP. Using a vesicular stomatitis virus glycoprotein (VSVG) trafficking assay, we demonstrated that fatostatin delays ERto-Golgi transport of VSVG. In summary, fatostatin inhibited SREBP activation, but fatostatin additionally inhibited cell proliferation through both lipid-independent and SCAPindependent mechanisms, possibly by general inhibition of ER-to-Golgi transport.-Shao, W., C. E. Machamer, and P. J. Espenshade. Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner. J. Lipid Res. 2016. 57: 1564-1573.",
keywords = "Endoplasmic reticulum, Endoplasmic reticulum-to-golgi transport, Sterol regulatory element-binding protein, Sterol regulatory element-binding protein cleavage activating protein",
author = "Wei Shao and Machamer, {Carolyn E} and Peter Espenshade",
year = "2016",
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doi = "10.1194/jlr.M069583",
language = "English (US)",
volume = "57",
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TY - JOUR

T1 - Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner

AU - Shao, Wei

AU - Machamer, Carolyn E

AU - Espenshade, Peter

PY - 2016/8/1

Y1 - 2016/8/1

N2 - Sterol regulatory element-binding protein (SREBP) transcription factors are central regulators of cellular lipid homeostasis and activate expression of genes required for fatty acid, triglyceride, and cholesterol synthesis and uptake. SREBP cleavage activating protein (SCAP) plays an essential role in SREBP activation by mediating endoplasmic reticulum (ER)-to-Golgi transport of SREBP. In the Golgi, membrane-bound SREBPs are cleaved sequentially by the site-1 and site-2 proteases. Recent studies have shown a requirement for the SREBP pathway in the development of fatty liver disease and tumor growth, making SCAP a target for drug development. Fatostatin is a chemical inhibitor of the SREBP pathway that directly binds SCAP and blocks its ERto-Golgi transport. In this study, we determined that fatostatin blocks ER exit of SCAP and showed that inhibition is independent of insulin-induced gene proteins, which function to retain the SCAP-SREBP complex in the ER. Fatostatin potently inhibited cell growth, but unexpectedly exogenous lipids failed to rescue proliferation of fatostatin-treated cells. Furthermore, fatostatin inhibited growth of cells lacking SCAP. Using a vesicular stomatitis virus glycoprotein (VSVG) trafficking assay, we demonstrated that fatostatin delays ERto-Golgi transport of VSVG. In summary, fatostatin inhibited SREBP activation, but fatostatin additionally inhibited cell proliferation through both lipid-independent and SCAPindependent mechanisms, possibly by general inhibition of ER-to-Golgi transport.-Shao, W., C. E. Machamer, and P. J. Espenshade. Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner. J. Lipid Res. 2016. 57: 1564-1573.

AB - Sterol regulatory element-binding protein (SREBP) transcription factors are central regulators of cellular lipid homeostasis and activate expression of genes required for fatty acid, triglyceride, and cholesterol synthesis and uptake. SREBP cleavage activating protein (SCAP) plays an essential role in SREBP activation by mediating endoplasmic reticulum (ER)-to-Golgi transport of SREBP. In the Golgi, membrane-bound SREBPs are cleaved sequentially by the site-1 and site-2 proteases. Recent studies have shown a requirement for the SREBP pathway in the development of fatty liver disease and tumor growth, making SCAP a target for drug development. Fatostatin is a chemical inhibitor of the SREBP pathway that directly binds SCAP and blocks its ERto-Golgi transport. In this study, we determined that fatostatin blocks ER exit of SCAP and showed that inhibition is independent of insulin-induced gene proteins, which function to retain the SCAP-SREBP complex in the ER. Fatostatin potently inhibited cell growth, but unexpectedly exogenous lipids failed to rescue proliferation of fatostatin-treated cells. Furthermore, fatostatin inhibited growth of cells lacking SCAP. Using a vesicular stomatitis virus glycoprotein (VSVG) trafficking assay, we demonstrated that fatostatin delays ERto-Golgi transport of VSVG. In summary, fatostatin inhibited SREBP activation, but fatostatin additionally inhibited cell proliferation through both lipid-independent and SCAPindependent mechanisms, possibly by general inhibition of ER-to-Golgi transport.-Shao, W., C. E. Machamer, and P. J. Espenshade. Fatostatin blocks ER exit of SCAP but inhibits cell growth in a SCAP-independent manner. J. Lipid Res. 2016. 57: 1564-1573.

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KW - Sterol regulatory element-binding protein cleavage activating protein

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