Uncoupling protein 3 transcription is regulated by peroxisome proliferator‐activated receptor α in the adult rodent heart

Uncoupling protein-3 (UCP3) is a member of the mitochondrial carrier family expressed preferentially in skeletal muscle and heart. It appears to be involved in metabolic handling of fatty acids in a way that minimizes excessive production of reactive oxygen species. Fatty acids are powerful regulators of UCP3 gene transcription. We have found that the role of peroxisome proliferator-activated receptor-α (PPARα) on the control of UCP3 gene expression depends on the tissue and developmental stage. In adults, UCP3 mRNA expression is unaltered in skeletal muscle from PPARα-null mice both in basal conditions and under the stimulus of starvation. In contrast, UCP3 mRNA is down-regulated in adult heart both in fed and fasted PPARα-null mice. This occurs despite the increased levels of free fatty acids caused by fasting in PPARα-null mice. In neonates, PPARα-null mice show impaired UCP3 mRNA expression in skeletal muscle in response to milk intake, and this is not a result of reduced free fatty acid levels. The murine UCP3 promoter is activated by fatty acids through either PPARα or PPARδ but not by PPARγ or retinoid X receptor alone. PPARδ-dependent activation could be a potential compensatory mechanism to ensure appropriate expression of UCP3 gene in adult skeletal muscle in the absence of PPARα. However, among transcripts from other PPARα and PPARδ target genes, only those acutely induced by milk intake in wild-type neonates were altered in muscle or heart from PPARα-null neonates. Thus, PPARα-dependent regulation is required for appropriate gene regulation of UCP3 as part of the subset of fatty-acid-responsive genes in neonatal muscle and heart.

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Up-regulation of uncoupling protein 3 by thyroid hormone, peroxisome proliferator-activated receptor ligands and 9-cis retinoic acid in L6 myotubes

FEBS Letters ◽

10.1016/s0014-5793(99)01477-5 ◽

1999 ◽

Vol 461 (3) ◽

pp. 319-322 ◽

Cited By ~ 57

Author(s):

Itsuro Nagase ◽

Shigeru Yoshida ◽

Xavier Canas ◽

Yukiko Irie ◽

Kazuhiro Kimura ◽

...

Keyword(s):

Retinoic Acid ◽

Thyroid Hormone ◽

Uncoupling Protein ◽

Peroxisome Proliferator ◽

Receptor Ligands ◽

Peroxisome Proliferator Activated Receptor ◽

L6 Myotubes ◽

Uncoupling Protein 3

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Pancreatic Islet Adaptation to Fasting Is Dependent on Peroxisome Proliferator-Activated Receptor α Transcriptional Up-Regulation of Fatty Acid Oxidation

Endocrinology ◽

10.1210/en.2004-0667 ◽

2005 ◽

Vol 146 (1) ◽

pp. 375-382 ◽

Cited By ~ 71

Author(s):

Sandrine Gremlich ◽

Christopher Nolan ◽

Raphaël Roduit ◽

Rémy Burcelin ◽

Marie-Line Peyot ◽

...

Keyword(s):

Insulin Secretion ◽

Fatty Acid ◽

Fatty Acid Oxidation ◽

Pancreatic Islet ◽

Cellular Response ◽

Uncoupling Protein ◽

Acid Oxidation ◽

Hyperinsulinemic Hypoglycemia ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor

The cellular response to fasting and starvation in tissues such as heart, skeletal muscle, and liver requires peroxisome proliferator-activated receptor-α (PPARα)-dependent up-regulation of energy metabolism toward fatty acid oxidation (FAO). PPARα null (PPARαKO) mice develop hyperinsulinemic hypoglycemia in the fasting state, and we previously showed that PPARα expression is increased in islets at low glucose. On this basis, we hypothesized that enhanced PPARα expression and FAO, via depletion of lipid-signaling molecule(s) for insulin exocytosis, are also involved in the normal adaptive response of the islet to fasting. Fasted PPARαKO mice compared with wild-type mice had supranormal ip glucose tolerance due to increased plasma insulin levels. Isolated islets from the PPARα null mice had a 44% reduction in FAO, normal glucose use and oxidation, and enhanced glucose-induced insulin secretion. In normal rats, fasting for 24 h increased islet PPARα, carnitine palmitoyltransferase 1, and uncoupling protein-2 mRNA expression by 60%, 62%, and 82%, respectively. The data are consistent with the view that PPARα, via transcriptionally up-regulating islet FAO, can reduce insulin secretion, and that this mechanism is involved in the normal physiological response of the pancreatic islet to fasting such that hypoglycemia is avoided.

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Liraglutide suppresses obesity and promotes browning of white fat via miR-27b in vivo and in vitro

Journal of International Medical Research ◽

10.1177/03000605211055059 ◽

2021 ◽

Vol 49 (11) ◽

pp. 030006052110550

Author(s):

Xing Wang ◽

Shuchun Chen ◽

Dan Lv ◽

Zelin Li ◽

Luping Ren ◽

...

Keyword(s):

Uncoupling Protein ◽

Density Lipoprotein ◽

Peroxisome Proliferator ◽

Sprague Dawley ◽

Peroxisome Proliferator Activated Receptor ◽

Protein Levels ◽

White Adipocytes ◽

White Fat

Objective To investigate the effect of liraglutide on the browning of white fat and the suppression of obesity via regulating microRNA (miR)-27b in vivo and in vitro. Methods Sprague-Dawley rats were fed a high-fat (HF) diet and 3T3-L1 pre-adipocytes were differentiated into mature white adipocytes. Rats and mature adipocytes were then treated with different doses of liraglutide. The mRNA and protein levels of browning-associated proteins, including uncoupling protein 1 (UCP1), PR domain containing 16 (PRDM16), CCAAT enhancer binding protein β (CEBPβ), cell death-inducing DFFA-like effector A (CIDEA) and peroxisome proliferator-activated receptor-γ-coactivator 1α (PGC-1α), were detected using quantitative real-time polymerase chain reaction and Western blotting. Results Liraglutide decreased body weight and reduced the levels of blood glucose, triglyceride and low-density lipoprotein cholesterol in HF diet-fed rats. Liraglutide increased the levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α in vivo and vitro. The levels of miR-27b were upregulated in HF diet-fed rats, whereas liraglutide reduced the levels of miR-27b. In vitro, overexpression of miR-27b decreased the mRNA and protein levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α. Transfection with the miR-27b mimics attenuated the effect of liraglutide on the browning of white adipocytes. Conclusion Liraglutide induced browning of white adipose through regulation of miR-27b.

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Peroxisome Proliferator-Activated Receptor α (PPARα) Potentiates, whereas PPARγ Attenuates, Glucose-Stimulated Insulin Secretion in Pancreatic β-Cells

Endocrinology ◽

10.1210/en.2004-1430 ◽

2005 ◽

Vol 146 (8) ◽

pp. 3266-3276 ◽

Cited By ~ 71

Author(s):

Kim Ravnskjaer ◽

Michael Boergesen ◽

Blanca Rubi ◽

Jan K. Larsen ◽

Tina Nielsen ◽

...

Keyword(s):

Insulin Secretion ◽

Mitochondrial Membrane ◽

Uncoupling Protein ◽

Peroxisome Proliferator ◽

Dependent Manner ◽

Β Cells ◽

Pancreatic Β Cells ◽

Peroxisome Proliferator Activated Receptor ◽

Glucose Stimulated Insulin Secretion

Abstract Fatty acids (FAs) are known to be important regulators of insulin secretion from pancreatic β-cells. FA-coenzyme A esters have been shown to directly stimulate the secretion process, whereas long-term exposure of β-cells to FAs compromises glucose-stimulated insulin secretion (GSIS) by mechanisms unknown to date. It has been speculated that some of these long-term effects are mediated by members of the peroxisome proliferator-activated receptor (PPAR) family via an induction of uncoupling protein-2 (UCP2). In this study we show that adenoviral coexpression of PPARα and retinoid X receptor α (RXRα) in INS-1E β-cells synergistically and in a dose- and ligand-dependent manner increases the expression of known PPARα target genes and enhances FA uptake and β-oxidation. In contrast, ectopic expression of PPARγ/RXRα increases FA uptake and deposition as triacylglycerides. Although the expression of PPARα/RXRα leads to the induction of UCP2 mRNA and protein, this is not accompanied by reduced hyperpolarization of the mitochondrial membrane, indicating that under these conditions, increased UCP2 expression is insufficient for dissipation of the mitochondrial proton gradient. Importantly, whereas expression of PPARγ/RXRα attenuates GSIS, the expression of PPARα/RXRα potentiates GSIS in rat islets and INS-1E cells without affecting the mitochondrial membrane potential. These results show a strong subtype specificity of the two PPAR subtypes α and γ on lipid partitioning and insulin secretion when systematically compared in a β-cell context.

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