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AICAR Protects against High Palmitate/High Insulin-Induced Intramyocellular Lipid Accumulation and Insulin Resistance in HL-1 Cardiac Cells by Inducing PPAR-Target Gene Expression.

Rodríguez-Calvo R, Vázquez-Carrera M, Masana L, Neumann D - PPAR Res (2015)

Bottom Line: Treatment with AICAR induced gene expression of all three PPARs, but only the Ppara and Pparg regulation were dependent on AMPK.AICAR treatment induced the expression of Acadvl and Glut4, which correlated to prevention of the HP/HI-induced intramyocellular lipid build-up, and attenuation of the HP/HI-induced impairment of glucose uptake.These data support the hypothesis that AICAR contributes to cardiac metabolic adaptation via regulation of transcriptional mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Faculty of Health, Medicine and Life Sciences, Maastricht University, 6200 MD Maastricht, Netherlands.

ABSTRACT
Here we studied the impact of 5-aminoimidazole-4-carboxamide riboside (AICAR), a well-known AMPK activator, on cardiac metabolic adaptation. AMPK activation by AICAR was confirmed by increased phospho-Thr(172)-AMPK and phospho-Ser(79)-ACC protein levels in HL-1 cardiomyocytes. Then, cells were exposed to AICAR stimulation for 24 h in the presence or absence of the AMPK inhibitor Compound C, and the mRNA levels of the three PPARs were analyzed by real-time RT-PCR. Treatment with AICAR induced gene expression of all three PPARs, but only the Ppara and Pparg regulation were dependent on AMPK. Next, we exposed HL-1 cells to high palmitate/high insulin (HP/HI) conditions either in presence or in absence of AICAR, and we evaluated the expression of selected PPAR-targets genes. HP/HI induced insulin resistance and lipid storage was accompanied by increased Cd36, Acot1, and Ucp3 mRNA levels. AICAR treatment induced the expression of Acadvl and Glut4, which correlated to prevention of the HP/HI-induced intramyocellular lipid build-up, and attenuation of the HP/HI-induced impairment of glucose uptake. These data support the hypothesis that AICAR contributes to cardiac metabolic adaptation via regulation of transcriptional mechanisms.

No MeSH data available.


Related in: MedlinePlus

AICAR stimulation attenuates HP/HI-induced glucose uptake impairment in HL-1. HL-1 cells were stimulated with HP/HI for 16 h in the presence or absence of AICAR (24 h), and [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) were assessed in the presence (a) and absence (b) of insulin (200 nmol/L, 10 min). [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) determination in HL-1 cells stimulated with AICAR (24 h) in the presence and absence of insulin (200 nmol/L, 10 min) (c). Data are expressed as mean ± SD of 4 different experiments performed in duplicate. (∗P < 0.05, ∗∗∗P < 0.001 versus control cells without insulin stimulation; &&&P < 0.001 versus control cells stimulated with insulin; #P < 0.05 versus HP/HI-challenged cells stimulated with insulin (a) or without insulin (b); $P < 0.05 versus AICAR-treated cells stimulated with insulin).
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fig5: AICAR stimulation attenuates HP/HI-induced glucose uptake impairment in HL-1. HL-1 cells were stimulated with HP/HI for 16 h in the presence or absence of AICAR (24 h), and [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) were assessed in the presence (a) and absence (b) of insulin (200 nmol/L, 10 min). [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) determination in HL-1 cells stimulated with AICAR (24 h) in the presence and absence of insulin (200 nmol/L, 10 min) (c). Data are expressed as mean ± SD of 4 different experiments performed in duplicate. (∗P < 0.05, ∗∗∗P < 0.001 versus control cells without insulin stimulation; &&&P < 0.001 versus control cells stimulated with insulin; #P < 0.05 versus HP/HI-challenged cells stimulated with insulin (a) or without insulin (b); $P < 0.05 versus AICAR-treated cells stimulated with insulin).

Mentions: Because GLUT4 is the main glucose transporter in HL-1 cardiomyocytes, we wonder whether the AICAR-induced Glut4 mRNA levels for 24 h may be related to a transcriptional metabolic adaptation aimed at preparing the cell for increasing glucose uptake. Thus, we assessed the effect of AICAR treatment over insulin stimulated glucose uptake and AKT phosphorylation in HL-1 cardiomyocytes challenged with HP/HI. As shown in Figure 5(a), acute insulin stimulation induced glucose uptake (~1.4-fold; P < 0.001 versus CT-Ins) and AKT phosphorylation. However, HP/HI-stimulated cells were not sensitive to insulin (−41.3%; P < 0.001 versus CT + Ins). AICAR treatment prevented the HP/HI effects reducing glucose uptake (~1.3-fold; P < 0.05 versus HP/HI + Ins) and AKT phosphorylation (Figure 5(a)). Because AICAR is able to stimulate glucose uptake in a non-insulin dependent way [25, 26], we explored the effect of this drug in the absence of insulin. AICAR itself induced glucose uptake (~1.5-fold; P < 0.001 versus CT) and prevented HP/HI-induced glucose uptake downregulation (Figure 5(b)), with no changes in the AKT phosphorylation state. Finally, to further clarify the action of this drug on insulin-response, the additive action of insulin and AICAR was evaluated. Combination of AICAR and insulin showed a synergistic effect on glucose uptake (~1.8-fold; P < 0.05 versus CT + Ins; ~1.7-fold; P < 0.05 versus AICAR − Ins), but not on the AKT phosphorylation (Figure 5(c)).


AICAR Protects against High Palmitate/High Insulin-Induced Intramyocellular Lipid Accumulation and Insulin Resistance in HL-1 Cardiac Cells by Inducing PPAR-Target Gene Expression.

Rodríguez-Calvo R, Vázquez-Carrera M, Masana L, Neumann D - PPAR Res (2015)

AICAR stimulation attenuates HP/HI-induced glucose uptake impairment in HL-1. HL-1 cells were stimulated with HP/HI for 16 h in the presence or absence of AICAR (24 h), and [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) were assessed in the presence (a) and absence (b) of insulin (200 nmol/L, 10 min). [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) determination in HL-1 cells stimulated with AICAR (24 h) in the presence and absence of insulin (200 nmol/L, 10 min) (c). Data are expressed as mean ± SD of 4 different experiments performed in duplicate. (∗P < 0.05, ∗∗∗P < 0.001 versus control cells without insulin stimulation; &&&P < 0.001 versus control cells stimulated with insulin; #P < 0.05 versus HP/HI-challenged cells stimulated with insulin (a) or without insulin (b); $P < 0.05 versus AICAR-treated cells stimulated with insulin).
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Related In: Results  -  Collection

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fig5: AICAR stimulation attenuates HP/HI-induced glucose uptake impairment in HL-1. HL-1 cells were stimulated with HP/HI for 16 h in the presence or absence of AICAR (24 h), and [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) were assessed in the presence (a) and absence (b) of insulin (200 nmol/L, 10 min). [3H]-deoxyglucose uptake (up) and AKT phosphorylation (down) determination in HL-1 cells stimulated with AICAR (24 h) in the presence and absence of insulin (200 nmol/L, 10 min) (c). Data are expressed as mean ± SD of 4 different experiments performed in duplicate. (∗P < 0.05, ∗∗∗P < 0.001 versus control cells without insulin stimulation; &&&P < 0.001 versus control cells stimulated with insulin; #P < 0.05 versus HP/HI-challenged cells stimulated with insulin (a) or without insulin (b); $P < 0.05 versus AICAR-treated cells stimulated with insulin).
Mentions: Because GLUT4 is the main glucose transporter in HL-1 cardiomyocytes, we wonder whether the AICAR-induced Glut4 mRNA levels for 24 h may be related to a transcriptional metabolic adaptation aimed at preparing the cell for increasing glucose uptake. Thus, we assessed the effect of AICAR treatment over insulin stimulated glucose uptake and AKT phosphorylation in HL-1 cardiomyocytes challenged with HP/HI. As shown in Figure 5(a), acute insulin stimulation induced glucose uptake (~1.4-fold; P < 0.001 versus CT-Ins) and AKT phosphorylation. However, HP/HI-stimulated cells were not sensitive to insulin (−41.3%; P < 0.001 versus CT + Ins). AICAR treatment prevented the HP/HI effects reducing glucose uptake (~1.3-fold; P < 0.05 versus HP/HI + Ins) and AKT phosphorylation (Figure 5(a)). Because AICAR is able to stimulate glucose uptake in a non-insulin dependent way [25, 26], we explored the effect of this drug in the absence of insulin. AICAR itself induced glucose uptake (~1.5-fold; P < 0.001 versus CT) and prevented HP/HI-induced glucose uptake downregulation (Figure 5(b)), with no changes in the AKT phosphorylation state. Finally, to further clarify the action of this drug on insulin-response, the additive action of insulin and AICAR was evaluated. Combination of AICAR and insulin showed a synergistic effect on glucose uptake (~1.8-fold; P < 0.05 versus CT + Ins; ~1.7-fold; P < 0.05 versus AICAR − Ins), but not on the AKT phosphorylation (Figure 5(c)).

Bottom Line: Treatment with AICAR induced gene expression of all three PPARs, but only the Ppara and Pparg regulation were dependent on AMPK.AICAR treatment induced the expression of Acadvl and Glut4, which correlated to prevention of the HP/HI-induced intramyocellular lipid build-up, and attenuation of the HP/HI-induced impairment of glucose uptake.These data support the hypothesis that AICAR contributes to cardiac metabolic adaptation via regulation of transcriptional mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Faculty of Health, Medicine and Life Sciences, Maastricht University, 6200 MD Maastricht, Netherlands.

ABSTRACT
Here we studied the impact of 5-aminoimidazole-4-carboxamide riboside (AICAR), a well-known AMPK activator, on cardiac metabolic adaptation. AMPK activation by AICAR was confirmed by increased phospho-Thr(172)-AMPK and phospho-Ser(79)-ACC protein levels in HL-1 cardiomyocytes. Then, cells were exposed to AICAR stimulation for 24 h in the presence or absence of the AMPK inhibitor Compound C, and the mRNA levels of the three PPARs were analyzed by real-time RT-PCR. Treatment with AICAR induced gene expression of all three PPARs, but only the Ppara and Pparg regulation were dependent on AMPK. Next, we exposed HL-1 cells to high palmitate/high insulin (HP/HI) conditions either in presence or in absence of AICAR, and we evaluated the expression of selected PPAR-targets genes. HP/HI induced insulin resistance and lipid storage was accompanied by increased Cd36, Acot1, and Ucp3 mRNA levels. AICAR treatment induced the expression of Acadvl and Glut4, which correlated to prevention of the HP/HI-induced intramyocellular lipid build-up, and attenuation of the HP/HI-induced impairment of glucose uptake. These data support the hypothesis that AICAR contributes to cardiac metabolic adaptation via regulation of transcriptional mechanisms.

No MeSH data available.


Related in: MedlinePlus