scholarly journals Direct Thiazolidinedione Action on Isolated Rat Skeletal Muscle Fuel Handling Is Independent of Peroxisome Proliferator-Activated Receptor- -Mediated Changes in Gene Expression

Diabetes ◽  
2001 ◽  
Vol 50 (10) ◽  
pp. 2309-2315 ◽  
Author(s):  
B. Brunmair ◽  
F. Gras ◽  
S. Neschen ◽  
M. Roden ◽  
L. Wagner ◽  
...  
2015 ◽  
Vol 40 (1) ◽  
pp. 96-98 ◽  
Author(s):  
Jeremy J. Walsh ◽  
Brittany A. Edgett ◽  
Michael E. Tschakovsky ◽  
Brendon J. Gurd

Brain-derived neurotrophic factor (BDNF) gene expression was measured in human skeletal muscle following 3 intensities of exercise and a 48-h fast. No change in BDNF mRNA was observed following exercise, while fasting upregulated BDNF by ∼3.5-fold. These changes were dissociated from changes in peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) following exercise (+2- to 15-fold) and fasting (∼–25%). These results challenge our understanding of the response of BDNF to energetic stress and highlight the importance of future work in this area.


2004 ◽  
Vol 24 (20) ◽  
pp. 9079-9091 ◽  
Author(s):  
Janice M. Huss ◽  
Inés Pineda Torra ◽  
Bart Staels ◽  
Vincent Giguère ◽  
Daniel P. Kelly

ABSTRACT Estrogen-related receptors (ERRs) are orphan nuclear receptors activated by the transcriptional coactivator peroxisome proliferator-activated receptor γ (PPARγ) coactivator 1α (PGC-1α), a critical regulator of cellular energy metabolism. However, metabolic target genes downstream of ERRα have not been well defined. To identify ERRα-regulated pathways in tissues with high energy demand such as the heart, gene expression profiling was performed with primary neonatal cardiac myocytes overexpressing ERRα. ERRα upregulated a subset of PGC-1α target genes involved in multiple energy production pathways, including cellular fatty acid transport, mitochondrial and peroxisomal fatty acid oxidation, and mitochondrial respiration. These results were validated by independent analyses in cardiac myocytes, C2C12 myotubes, and cardiac and skeletal muscle of ERRα−/− mice. Consistent with the gene expression results, ERRα increased myocyte lipid accumulation and fatty acid oxidation rates. Many of the genes regulated by ERRα are known targets for the nuclear receptor PPARα, and therefore, the interaction between these regulatory pathways was explored. ERRα activated PPARα gene expression via direct binding of ERRα to the PPARα gene promoter. Furthermore, in fibroblasts null for PPARα and ERRα, the ability of ERRα to activate several PPARα targets and to increase cellular fatty acid oxidation rates was abolished. PGC-1α was also shown to activate ERRα gene expression. We conclude that ERRα serves as a critical nodal point in the regulatory circuitry downstream of PGC-1α to direct the transcription of genes involved in mitochondrial energy-producing pathways in cardiac and skeletal muscle.


2016 ◽  
Vol 121 (3) ◽  
pp. 806-810 ◽  
Author(s):  
Yu Kitaoka ◽  
Koichi Nakazato ◽  
Riki Ogasawara

Recent studies have demonstrated that resistance exercise leads not only to muscle hypertrophy, but it also improves mitochondrial function. Because calorie restriction (CR) has been suggested as a way to induce mitochondrial biogenesis, we examined the effects of resistance training with or without CR on muscle weight and key mitochondrial parameters in rat skeletal muscle. Four weeks of resistance training (thrice/wk) resulted in increased gastrocnemius muscle weight by 14% in rats fed ad libitum (AL). The degree of muscle-weight increase via resistance training was lower in rats with CR (7.4%). CR showed no effect on phosphorylation of mammalian target of rapamycin (mTOR) signaling proteins rpS6 and ULK1. Our results revealed that CR resulted in elevated levels of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) protein, a known master regulator of mitochondrial biogenesis. Resistance training alone also resulted in increased PGC-1α levels in skeletal muscle. The magnitude of the increase in PGC-1α was similar in rats in both the CR and AL groups. Moreover, we found that resistance training with CR resulted in elevated levels of proteins involved in mitochondrial fusion (Opa1 and Mfn1), and oxidative phosphorylation, whereas there was no effect of CR on the fission-regulatory proteins Fis1 and Drp1. These results indicate that CR attenuates resistance training-induced muscle hypertrophy, and that it may enhance mitochondrial adaptations in skeletal muscle.


Endocrinology ◽  
2006 ◽  
Vol 147 (10) ◽  
pp. 4695-4704 ◽  
Author(s):  
Neus Pedraza ◽  
Meritxell Rosell ◽  
Joan Villarroya ◽  
Roser Iglesias ◽  
Frank J. Gonzalez ◽  
...  

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.


1998 ◽  
Vol 83 (8) ◽  
pp. 2830-2835 ◽  
Author(s):  
Kyong Soo Park ◽  
Theodore P. Ciaraldi ◽  
Kristin Lindgren ◽  
Leslie Abrams-Carter ◽  
Sunder Mudaliar ◽  
...  

abstract Troglitazone, besides improving insulin action in insulin-resistant subjects, is also a specific ligand for the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ). To determine whether troglitazone might enhance insulin action by stimulation of PPARγ gene expression in muscle, total PPARγ messenger RNA (mRNA), and protein were determined in skeletal muscle cultures from nondiabetic control and type II diabetic subjects before and after treatment of cultures with troglitazone (4 days ± troglitazone, 11.5μ m). Troglitazone treatment increased PPARγ mRNA levels up to 3-fold in muscle cultures from type II diabetics (277 ± 63 to 630 ± 100 × 103 copies/μg total RNA, P = 0.003) and in nondiabetic control subjects (200 ± 42 to 490 ± 81, P = 0.003). PPARγ protein levels in both diabetic (4.7 ± 1.6 to 13.6± 3.0 AU/10 μg protein, P < 0.02) and nondiabetic cells (7.4 ± 1.0 to 12.7 ± 1.8, P < 0.05) were also up-regulated by troglitazone treatment. Increased PPARγ was associated with stimulation of human adipocyte lipid binding protein (ALBP) and muscle fatty acid binding protein (mFABP) mRNA, without change in the mRNA for glycerol-3-phosphate dehydrogenase, PPARδ, myogenin, uncoupling protein-2, or sarcomeric α-actin protein. In summary, we showed that troglitazone markedly induces PPARγ, ALBP, and mFABP mRNA abundance in muscle cultures from both nondiabetic and type II diabetic subjects. Increased expression of PPARγ protein and other genes involved in glucose and lipid metabolism in skeletal muscle may account, in part, for the insulin sensitizing effects of troglitazone in type II diabetes.


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