Activated AMPK inhibits PPAR-α and PPAR-γ transcriptional activity in hepatoma cells

Margaret S. Sozio, Changyue Lu, Yan Zeng, Suthat Liangpunsakul, David Crabb

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor- α(PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643- stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to rely on the activated conformation of AMPK. AMPK inhibition of PPAR-α and -γ may allow for short-term processes to increase energy generation before the cells devote resources to increasing their capacity for fatty acid oxidation.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume301
Issue number4
DOIs
StatePublished - Oct 2011

Fingerprint

Peroxisome Proliferator-Activated Receptors
AMP-Activated Protein Kinases
Hepatocellular Carcinoma
rosiglitazone
Metformin
Retinoid X Receptors
Peroxisome Proliferators
Response Elements
Protein Kinase Inhibitors
Plasmids
Fatty Acids
Retinoic Acid Receptors
DNA
Protein Subunits
Cytoplasmic and Nuclear Receptors
Luciferases

Keywords

  • AMP-activated protein kinase
  • Compound C
  • Fatty acid oxidation
  • Nuclear receptors
  • Peroxisome proliferator-activated receptor

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology (medical)
  • Physiology
  • Hepatology

Cite this

Activated AMPK inhibits PPAR-α and PPAR-γ transcriptional activity in hepatoma cells. / Sozio, Margaret S.; Lu, Changyue; Zeng, Yan; Liangpunsakul, Suthat; Crabb, David.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 301, No. 4, 10.2011.

Research output: Contribution to journalArticle

@article{74b76ee6848a40cf9fbfcbcb65cd68b3,
title = "Activated AMPK inhibits PPAR-α and PPAR-γ transcriptional activity in hepatoma cells",
abstract = "AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor- α(PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643- stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to rely on the activated conformation of AMPK. AMPK inhibition of PPAR-α and -γ may allow for short-term processes to increase energy generation before the cells devote resources to increasing their capacity for fatty acid oxidation.",
keywords = "AMP-activated protein kinase, Compound C, Fatty acid oxidation, Nuclear receptors, Peroxisome proliferator-activated receptor",
author = "Sozio, {Margaret S.} and Changyue Lu and Yan Zeng and Suthat Liangpunsakul and David Crabb",
year = "2011",
month = "10",
doi = "10.1152/ajpgi.00432.2010",
language = "English (US)",
volume = "301",
journal = "American Journal of Physiology",
issn = "0193-1857",
publisher = "American Physiological Society",
number = "4",

}

TY - JOUR

T1 - Activated AMPK inhibits PPAR-α and PPAR-γ transcriptional activity in hepatoma cells

AU - Sozio, Margaret S.

AU - Lu, Changyue

AU - Zeng, Yan

AU - Liangpunsakul, Suthat

AU - Crabb, David

PY - 2011/10

Y1 - 2011/10

N2 - AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor- α(PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643- stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to rely on the activated conformation of AMPK. AMPK inhibition of PPAR-α and -γ may allow for short-term processes to increase energy generation before the cells devote resources to increasing their capacity for fatty acid oxidation.

AB - AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor- α(PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643- stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to rely on the activated conformation of AMPK. AMPK inhibition of PPAR-α and -γ may allow for short-term processes to increase energy generation before the cells devote resources to increasing their capacity for fatty acid oxidation.

KW - AMP-activated protein kinase

KW - Compound C

KW - Fatty acid oxidation

KW - Nuclear receptors

KW - Peroxisome proliferator-activated receptor

UR - http://www.scopus.com/inward/record.url?scp=80053198203&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80053198203&partnerID=8YFLogxK

U2 - 10.1152/ajpgi.00432.2010

DO - 10.1152/ajpgi.00432.2010

M3 - Article

C2 - 21700905

AN - SCOPUS:80053198203

VL - 301

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0193-1857

IS - 4

ER -