scholarly journals Impact of L-FABP and glucose on polyunsaturated fatty acid induction of PPARα-regulated β-oxidative enzymes

2013 ◽  
Vol 304 (3) ◽  
pp. G241-G256 ◽  
Author(s):  
Anca D. Petrescu ◽  
Huan Huang ◽  
Gregory G. Martin ◽  
Avery L. McIntosh ◽  
Stephen M. Storey ◽  
...  
Keyword(s):  
Fatty Acid ◽  
High Glucose ◽  
Target Genes ◽  
De Novo ◽  
Oxidative Enzymes ◽  
Enhancement Effect ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fatty Acid Binding ◽  
Long Chain

Liver fatty acid binding protein (L-FABP) is the major soluble protein that binds very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) in hepatocytes. However, nothing is known about L-FABP's role in n-3 PUFA-mediated peroxisome proliferator activated receptor-α (PPARα) transcription of proteins involved in long-chain fatty acid (LCFA) β-oxidation. This issue was addressed in cultured primary hepatocytes from wild-type, L-FABP-null, and PPARα-null mice with these major findings: 1) PUFA-mediated increase in the expression of PPARα-regulated LCFA β-oxidative enzymes, LCFA/LCFA-CoA binding proteins (L-FABP, ACBP), and PPARα itself was L-FABP dependent; 2) PPARα transcription, robustly potentiated by high glucose but not maltose, a sugar not taken up, correlated with higher protein levels of these LCFA β-oxidative enzymes and with increased LCFA β-oxidation; and 3) high glucose altered the potency of n-3 relative to n-6 PUFA. This was not due to a direct effect of glucose on PPARα transcriptional activity nor indirectly through de novo fatty acid synthesis from glucose. Synergism was also not due to glucose impacting other signaling pathways, since it was observed only in hepatocytes expressing both L-FABP and PPARα. Ablation of L-FABP or PPARα as well as treatment with MK886 (PPARα inhibitor) abolished/reduced PUFA-mediated PPARα transcription of these genes, especially at high glucose. Finally, the PUFA-enhanced L-FABP distribution into nuclei with high glucose augmentation of the L-FABP/PPARα interaction reveals not only the importance of L-FABP for PUFA induction of PPARα target genes in fatty acid β-oxidation but also the significance of a high glucose enhancement effect in diabetes.

SUMO modification selectively regulates transcriptional activity of peroxisome-proliferator-activated receptor γ in C2C12 myotubes

2010 ◽  
Vol 433 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Sung Soo Chung ◽  
Byung Yong Ahn ◽  
Min Kim ◽  
Jun Ho Kho ◽  
Hye Seung Jung ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Transcriptional Activity ◽  
Target Genes ◽  
C2c12 Cells ◽  
C2c12 Myotubes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Mouse Muscle ◽  
Fatty Acid Binding ◽  
Specific Protease

PPAR (peroxisome-proliferator-activated receptor) γ, a nuclear receptor, can be conjugated with SUMO (small ubiquitin-like modifier), which results in the negative regulation of its transcriptional activity. In the present study, we tested whether de-SUMOylation of PPARγ affects the expression of PPARγ target genes in mouse muscle cells and investigated the mechanism by which de-SUMOylation increases PPARγ transcriptional activity. We found that the SUMO-specific protease SENP2 [SUMO1/sentrin/SMT3 (suppressor of mif two 3 homologue 1)-specific peptidase 2] effectively de-SUMOylates PPARγ–SUMO conjugates. Overexpression of SENP2 in C2C12 cells increased the expression of some PPARγ target genes, such as FABP3 (fatty-acid-binding protein 3) and CD36 (fatty acid translocase), both in the absence and presence of rosiglitazone. In contrast, overexpression of SENP2 did not affect the expression of another PPARγ target gene ADRP (adipose differentiation-related protein). De-SUMOylation of PPARγ increased ChIP (chromatin immunoprecipitation) of both a recombinant PPRE (PPAR-response element) and endogenous PPREs of the target genes CD36 and FABP3, but ChIP of the PPRE in the ADRP promoter was not affected by SENP2 overexpression. In conclusion, these results indicate that SENP2 de-SUMOylates PPARγ in myotubes, and de-SUMOylation of PPARγ selectively increases the expression of some PPARγ target genes.

Evaluation of anti-adipogenic active homoisoflavonoids from Portulaca oleracea

2019 ◽  
Vol 74 (9-10) ◽  
pp. 265-273 ◽  
Author(s):  
Jung Im Lee ◽  
Jung Hwan Oh ◽  
Chang-Suk Kong ◽  
Youngwan Seo
Keyword(s):  
Fatty Acid ◽  
Crude Extract ◽  
Lipid Accumulation ◽  
Target Genes ◽  
Adipogenic Differentiation ◽  
Portulaca Oleracea ◽  
Fatty Acid Transport ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fatty Acid Binding

Abstract This study was performed to isolate antiobesity components from the crude extract of Portulaca oleracea. The crude extract was partitioned into n-hexane, 85% aqueous methanol, n-butanol, and water fractions. Their effects on adipogenic differentiation were evaluated in 3T3-L1 cells. Among the solvent fractions from P. olearacea, the 85% aq. MeOH effectively reduced the levels of lipid accumulation. Further purification of 85% aq. MeOH led to the isolation of the known homoisoflavonoids 1–4, as the active substances. The administration of homoisoflavonoids to adipocyte cells decreased the lipid accumulation and glucose consumption and increased the release of glycerol into culture medium. In particular, homoisoflavonoid 3 effectively down-regulated the adipogenic transcription genes such as peroxisome proliferator activated receptor-γ (PPARγ) and CCAAT/enhancer-binding proteins (C/EBPα), and adipogenic target genes such as fatty acid binding protein 4 (FABP4), fatty acid transport protein 1 (FATP1), and acyl-CoA synthase 1 (ACS1).

scholarly journals Inhibitors of Fatty Acid Synthesis Induce PPARα-Regulated Fatty Acidβ-Oxidative Genes: Synergistic Roles of L-FABP and Glucose

PPAR Research ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-22 ◽  
Author(s):  
Huan Huang ◽  
Avery L. McIntosh ◽  
Gregory G. Martin ◽  
Anca D. Petrescu ◽  
Kerstin K. Landrock ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
High Glucose ◽  
Fatty Acid Synthase ◽  
Binding Protein ◽  
Acid Synthesis ◽  
Oxidative Enzymes ◽  
Peroxisome Proliferator ◽  
Synthesis Inhibitor ◽  
Fatty Acid Binding

While TOFA (acetyl CoA carboxylase inhibitor) and C75 (fatty acid synthase inhibitor) prevent lipid accumulation by inhibiting fatty acid synthesis, the mechanism of action is not simply accounted for by inhibition of the enzymes alone. Liver fatty acid binding protein (L-FABP), a mediator of long chain fatty acid signaling to peroxisome proliferator-activated receptor-α(PPARα) in the nucleus, was found to bind TOFA and its activated CoA thioester, TOFyl-CoA, with high affinity while binding C75 and C75-CoA with lower affinity. Binding of TOFA and C75-CoA significantly altered L-FABP secondary structure. High (20 mM) but not physiological (6 mM) glucose conferred on both TOFA and C75 the ability to induce PPARαtranscription of the fatty acidβ-oxidative enzymes CPT1A, CPT2, and ACOX1 in cultured primary hepatocytes from wild-type (WT) mice. However, L-FABP gene ablation abolished the effects of TOFA and C75 in the context of high glucose. These effects were not associated with an increased cellular level of unesterified fatty acids but rather by increased intracellular glucose. These findings suggested that L-FABP may function as an intracellular fatty acid synthesis inhibitor binding protein facilitating TOFA and C75-mediated induction of PPARαin the context of high glucose at levels similar to those in uncontrolled diabetes.

scholarly journals Human FABP1 T94A variant impacts fatty acid metabolism and PPAR-α activation in cultured human female hepatocytes

2014 ◽  
Vol 307 (2) ◽  
pp. G164-G176 ◽  
Author(s):  
Avery L. McIntosh ◽  
Huan Huang ◽  
Stephen M. Storey ◽  
Kerstin K. Landrock ◽  
Danilo Landrock ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Mrna Expression ◽  
De Novo ◽  
Carnitine Palmitoyltransferase ◽  
De Novo Lipogenesis ◽  
Oxidative Enzymes ◽  
Peroxisome Proliferator ◽  
Serum Triglycerides ◽  
Fatty Acid Binding ◽  
Nonalcoholic Fatty Liver

Although human liver fatty acid-binding protein (FABP1) T94A variant has been associated with nonalcoholic fatty liver disease and reduced ability of fenofibrate to lower serum triglycerides (TG) to target levels, molecular events leading to this phenotype are poorly understood. Cultured primary hepatocytes from female human subjects expressing the FABP1 T94A variant exhibited increased neutral lipid (TG, cholesteryl ester) accumulation associated with 1) upregulation of total FABP1, a key protein stimulating mitochondrial glycerol-3-phosphate acyltransferase (GPAM), the rate-limiting enzyme in lipogenesis; 2) increased mRNA expression of key enzymes in lipogenesis ( GPAM, LPIN2) in heterozygotes; 3) decreased mRNA expression of microsomal triglyceride transfer protein; 4) increased secretion of ApoB100 but not TG; 5) decreased long-chain fatty acid (LCFA) β-oxidation. TG accumulation was not due to any increase in LCFA uptake, de novo lipogenesis, or the alternate monoacylglycerol O-acyltransferase pathway in lipogenesis. Despite increased expression of total FABP1 mRNA and protein, fenofibrate-mediated FABP1 redistribution to nuclei and ligand-induced peroxisome proliferator-activated receptor (PPAR-α) transcription of LCFA β-oxidative enzymes (carnitine palmitoyltransferase 1A, carnitine palmitoyltransferase 2, and acyl-coenzyme A oxidase 1, palmitoyl) were attenuated in FABP1 T94A hepatocytes. Although the phenotype of FABP1 T94A variant human hepatocytes exhibits some similarities to that of FABP1-null or PPAR-α-null hepatocytes and mice, expression of FABP1 T94A variant did not abolish or reduce ligand binding. Thus the FABP1 T94A variant represents an altered/reduced function mutation resulting in TG accumulation.

scholarly journals Regulation of cardiac fatty acids metabolism in transgenic mice overexpressing bovine GH

2009 ◽  
Vol 201 (3) ◽  
pp. 419-427 ◽  
Author(s):  
Fausto Bogazzi ◽  
Francesco Raggi ◽  
Federica Ultimieri ◽  
Dania Russo ◽  
Aldo D'Alessio ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Transgenic Mice ◽  
Fatty Acid Transport ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fatty Acid Binding ◽  
Chain Acyl ◽  
Fatty Acids Metabolism ◽  
Key Enzyme ◽  
Key Steps

Cardiac energy metabolism depends mainly on fatty acid (FA) oxidation; however, regulation of FA metabolism in acromegalic (Acro) heart is unknown. The aim of the study was to evaluate cardiac expression of key proteins of FA metabolism in young and elder transgenic mice overexpressing bovine GH Acro. Expression of proteins regulating FA entry into the cells, their uptake by mitochondria and β-oxidation were evaluated by western blot, while FA content by Fourier transform infrared microspectrometry. Regulatory mechanisms of key steps of FA metabolism were also studied. The expression of plasma-membrane FA carriers (fatty acid-binding protein and fatty acid transport protein-1) and acylCoA synthetase was higher in young and lower in elder Acro than in corresponding controls; likewise, expression of cytoplasm to mitochondria-1 (CPT-1), the key enzyme of mitochondrial FA uptake, and that of medium-chain acyl-CoA dehydrogenase and long-chain acyl-CoA dehydrogenase, two regulatory β-oxidation dehydrogenases, followed a similar pattern. FA content was lower in young and higher in elder Acro than in wild-type, suggesting an increased utilisation in young animals. GH regulated expression of key proteins of FA metabolism through changes in peroxisome proliferator-activated receptor α (PPARα) expression, which varied accordingly. GH effect was confirmed by treatment of Acro mice with a receptor antagonist, which abolished changes in key proteins of FA metabolism in young Acro. GH increased phosphorylation of AMP-activated protein kinase and anti-acetyl-CoA-carboxylase, two regulatory kinases, leading to lower CPT-1 inhibition by malonyl-CoA, and intervened in regulating PPARα expression through the ERK 1/2 pathway. In conclusion, chronic GH excess increased FA metabolism in the young age, whereas its action was overwhelmed in elder ages likely by GH-independent mechanisms, leading to reduced expression of key enzyme of FA metabolism.

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