Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish

Deanna L. Howarth, Claudia Lindtner, Ana M. Vacaru, Ravi Sachidanandam, Orkhontuya Tsedensodnom, Taisa Vasilkova, Christoph Buettner, Kirsten Sadler Edepli

Research output: Contribution to journalArticle

Abstract

Fatty liver disease (FLD) is characterized by lipid accumulation in hepatocytes and is accompanied by secretory pathway dysfunction, resulting in induction of the unfolded protein response (UPR). Activating transcription factor 6 (ATF6), one of three main UPR sensors, functions to both promote FLD during acute stress and reduce FLD during chronic stress. There is little mechanistic understanding of how ATF6, or any other UPR factor, regulates hepatic lipid metabolism to cause disease. We addressed this using zebrafish genetics and biochemical analyses and demonstrate that Atf6 is necessary and sufficient for FLD. atf6 transcription is significantly upregulated in the liver of zebrafish with alcoholic FLD and morpholino-mediated atf6 depletion significantly reduced steatosis incidence caused by alcohol. Moreover, overexpression of active, nuclear Atf6 (nAtf6) in hepatocytes caused FLD in the absence of stress. mRNA-Seq and qPCR analyses of livers from five day old nAtf6 transgenic larvae revealed upregulation of genes promoting glyceroneogenesis and fatty acid elongation, including fatty acid synthase (fasn), and nAtf6 overexpression in both zebrafish larvae and human hepatoma cells increased the incorporation of 14C-acetate into lipids. Srebp transcription factors are key regulators of lipogenic enzymes, but reducing Srebp activation by scap morpholino injection neither prevented FLD in nAtf6 transgenics nor synergized with atf6 knockdown to reduce alcohol-induced FLD. In contrast, fasn morpholino injection reduced FLD in nAtf6 transgenic larvae and synergistically interacted with atf6 to reduce alcoholic FLD. Thus, our data demonstrate that Atf6 is required for alcoholic FLD and epistatically interacts with fasn to cause this disease, suggesting triglyceride biogenesis as the mechanism of UPR induced FLD.

Original languageEnglish (US)
Article numbere1004335
JournalPLoS Genetics
Volume10
Issue number5
DOIs
StatePublished - Jan 1 2014

Fingerprint

Activating Transcription Factor 6
Alcoholic Fatty Liver
Alcoholic Liver Diseases
fatty liver
liver diseases
Zebrafish
Fatty Liver
Danio rerio
Liver Diseases
transcription factors
Unfolded Protein Response
unfolded protein response
Fatty Acid Synthases
Morpholinos
fatty-acid synthase
Larva
fatty acid
Hepatocytes
Liver
protein

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics
  • Genetics(clinical)
  • Cancer Research

Cite this

Howarth, D. L., Lindtner, C., Vacaru, A. M., Sachidanandam, R., Tsedensodnom, O., Vasilkova, T., ... Sadler Edepli, K. (2014). Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish. PLoS Genetics, 10(5), [e1004335]. https://doi.org/10.1371/journal.pgen.1004335

Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish. / Howarth, Deanna L.; Lindtner, Claudia; Vacaru, Ana M.; Sachidanandam, Ravi; Tsedensodnom, Orkhontuya; Vasilkova, Taisa; Buettner, Christoph; Sadler Edepli, Kirsten.

In: PLoS Genetics, Vol. 10, No. 5, e1004335, 01.01.2014.

Research output: Contribution to journalArticle

Howarth, DL, Lindtner, C, Vacaru, AM, Sachidanandam, R, Tsedensodnom, O, Vasilkova, T, Buettner, C & Sadler Edepli, K 2014, 'Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish', PLoS Genetics, vol. 10, no. 5, e1004335. https://doi.org/10.1371/journal.pgen.1004335
Howarth DL, Lindtner C, Vacaru AM, Sachidanandam R, Tsedensodnom O, Vasilkova T et al. Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish. PLoS Genetics. 2014 Jan 1;10(5). e1004335. https://doi.org/10.1371/journal.pgen.1004335
Howarth, Deanna L. ; Lindtner, Claudia ; Vacaru, Ana M. ; Sachidanandam, Ravi ; Tsedensodnom, Orkhontuya ; Vasilkova, Taisa ; Buettner, Christoph ; Sadler Edepli, Kirsten. / Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish. In: PLoS Genetics. 2014 ; Vol. 10, No. 5.
@article{cd08383c441f403bbc27d5a565aa140f,
title = "Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish",
abstract = "Fatty liver disease (FLD) is characterized by lipid accumulation in hepatocytes and is accompanied by secretory pathway dysfunction, resulting in induction of the unfolded protein response (UPR). Activating transcription factor 6 (ATF6), one of three main UPR sensors, functions to both promote FLD during acute stress and reduce FLD during chronic stress. There is little mechanistic understanding of how ATF6, or any other UPR factor, regulates hepatic lipid metabolism to cause disease. We addressed this using zebrafish genetics and biochemical analyses and demonstrate that Atf6 is necessary and sufficient for FLD. atf6 transcription is significantly upregulated in the liver of zebrafish with alcoholic FLD and morpholino-mediated atf6 depletion significantly reduced steatosis incidence caused by alcohol. Moreover, overexpression of active, nuclear Atf6 (nAtf6) in hepatocytes caused FLD in the absence of stress. mRNA-Seq and qPCR analyses of livers from five day old nAtf6 transgenic larvae revealed upregulation of genes promoting glyceroneogenesis and fatty acid elongation, including fatty acid synthase (fasn), and nAtf6 overexpression in both zebrafish larvae and human hepatoma cells increased the incorporation of 14C-acetate into lipids. Srebp transcription factors are key regulators of lipogenic enzymes, but reducing Srebp activation by scap morpholino injection neither prevented FLD in nAtf6 transgenics nor synergized with atf6 knockdown to reduce alcohol-induced FLD. In contrast, fasn morpholino injection reduced FLD in nAtf6 transgenic larvae and synergistically interacted with atf6 to reduce alcoholic FLD. Thus, our data demonstrate that Atf6 is required for alcoholic FLD and epistatically interacts with fasn to cause this disease, suggesting triglyceride biogenesis as the mechanism of UPR induced FLD.",
author = "Howarth, {Deanna L.} and Claudia Lindtner and Vacaru, {Ana M.} and Ravi Sachidanandam and Orkhontuya Tsedensodnom and Taisa Vasilkova and Christoph Buettner and {Sadler Edepli}, Kirsten",
year = "2014",
month = "1",
day = "1",
doi = "10.1371/journal.pgen.1004335",
language = "English (US)",
volume = "10",
journal = "PLoS Genetics",
issn = "1553-7390",
publisher = "Public Library of Science",
number = "5",

}

TY - JOUR

T1 - Activating Transcription Factor 6 Is Necessary and Sufficient for Alcoholic Fatty Liver Disease in Zebrafish

AU - Howarth, Deanna L.

AU - Lindtner, Claudia

AU - Vacaru, Ana M.

AU - Sachidanandam, Ravi

AU - Tsedensodnom, Orkhontuya

AU - Vasilkova, Taisa

AU - Buettner, Christoph

AU - Sadler Edepli, Kirsten

PY - 2014/1/1

Y1 - 2014/1/1

N2 - Fatty liver disease (FLD) is characterized by lipid accumulation in hepatocytes and is accompanied by secretory pathway dysfunction, resulting in induction of the unfolded protein response (UPR). Activating transcription factor 6 (ATF6), one of three main UPR sensors, functions to both promote FLD during acute stress and reduce FLD during chronic stress. There is little mechanistic understanding of how ATF6, or any other UPR factor, regulates hepatic lipid metabolism to cause disease. We addressed this using zebrafish genetics and biochemical analyses and demonstrate that Atf6 is necessary and sufficient for FLD. atf6 transcription is significantly upregulated in the liver of zebrafish with alcoholic FLD and morpholino-mediated atf6 depletion significantly reduced steatosis incidence caused by alcohol. Moreover, overexpression of active, nuclear Atf6 (nAtf6) in hepatocytes caused FLD in the absence of stress. mRNA-Seq and qPCR analyses of livers from five day old nAtf6 transgenic larvae revealed upregulation of genes promoting glyceroneogenesis and fatty acid elongation, including fatty acid synthase (fasn), and nAtf6 overexpression in both zebrafish larvae and human hepatoma cells increased the incorporation of 14C-acetate into lipids. Srebp transcription factors are key regulators of lipogenic enzymes, but reducing Srebp activation by scap morpholino injection neither prevented FLD in nAtf6 transgenics nor synergized with atf6 knockdown to reduce alcohol-induced FLD. In contrast, fasn morpholino injection reduced FLD in nAtf6 transgenic larvae and synergistically interacted with atf6 to reduce alcoholic FLD. Thus, our data demonstrate that Atf6 is required for alcoholic FLD and epistatically interacts with fasn to cause this disease, suggesting triglyceride biogenesis as the mechanism of UPR induced FLD.

AB - Fatty liver disease (FLD) is characterized by lipid accumulation in hepatocytes and is accompanied by secretory pathway dysfunction, resulting in induction of the unfolded protein response (UPR). Activating transcription factor 6 (ATF6), one of three main UPR sensors, functions to both promote FLD during acute stress and reduce FLD during chronic stress. There is little mechanistic understanding of how ATF6, or any other UPR factor, regulates hepatic lipid metabolism to cause disease. We addressed this using zebrafish genetics and biochemical analyses and demonstrate that Atf6 is necessary and sufficient for FLD. atf6 transcription is significantly upregulated in the liver of zebrafish with alcoholic FLD and morpholino-mediated atf6 depletion significantly reduced steatosis incidence caused by alcohol. Moreover, overexpression of active, nuclear Atf6 (nAtf6) in hepatocytes caused FLD in the absence of stress. mRNA-Seq and qPCR analyses of livers from five day old nAtf6 transgenic larvae revealed upregulation of genes promoting glyceroneogenesis and fatty acid elongation, including fatty acid synthase (fasn), and nAtf6 overexpression in both zebrafish larvae and human hepatoma cells increased the incorporation of 14C-acetate into lipids. Srebp transcription factors are key regulators of lipogenic enzymes, but reducing Srebp activation by scap morpholino injection neither prevented FLD in nAtf6 transgenics nor synergized with atf6 knockdown to reduce alcohol-induced FLD. In contrast, fasn morpholino injection reduced FLD in nAtf6 transgenic larvae and synergistically interacted with atf6 to reduce alcoholic FLD. Thus, our data demonstrate that Atf6 is required for alcoholic FLD and epistatically interacts with fasn to cause this disease, suggesting triglyceride biogenesis as the mechanism of UPR induced FLD.

UR - http://www.scopus.com/inward/record.url?scp=84901594244&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84901594244&partnerID=8YFLogxK

U2 - 10.1371/journal.pgen.1004335

DO - 10.1371/journal.pgen.1004335

M3 - Article

C2 - 24874946

AN - SCOPUS:84901594244

VL - 10

JO - PLoS Genetics

JF - PLoS Genetics

SN - 1553-7390

IS - 5

M1 - e1004335

ER -