scholarly journals Effect of obesity and exercise on the expression of the novel myokines, Myonectin and Irisin

Author(s):  
Jonathan M Peterson ◽  
Ryan Mart ◽  
Cherie E Bond

Metabolic dysfunction in skeletal muscle is a major contributor to the development of type 2 diabetes. Endurance exercise training has long been established as an effective means to directly restore skeletal muscle glucose and lipid uptake and metabolism. However, in addition to the direct effects of skeletal muscle on glucose and lipids, there is renewed interest in the ability of skeletal muscle to coordinate metabolic activity of other tissues, such as adipose tissue and liver. The purpose of this study was to examine the effects of endurance exercise on the expression level of two novel muscle-derived secreted factors, or myokines, Myonectin and Fibronectin type III domain containing 5 (Fndc5), the precursor for Irisin. Methods: We used the diaphragm muscle from both the obese Zucker rat (OZR) and lean Zucker Rat (LZR) with 9 weeks of aerobic training on a motorized treadmill. We examined the gene expression of 12 commonly used reference genes and performed quantitative real-time PCR analysis on the gene expression of Myonectin and Fndc5. Results: Of the 12 commonly used PCR reference genes tested we were able to establish that Hypoxanthine phosphoribosyltransferase 1 (HPRT1) and lactate dehydrogenase A (Ldha) remained stable in the diaphragm muscle regardless of obesity or exercise training. Interestingly, we also concluded that the commonly used reference genes: beta-Actin, beta-2-microglobulin, Non-POU domain containing, octamer-binding, Peptidylprolyl isomerase H, 18S ribosomal rna, TATA box binding protein and Transferrin receptor were all found to be altered by the combination of exercise and obesity. Our study showed that the diaphragm muscle of the OZR had significantly higher expression levels of both myonectin and Fndc5. Exercise training had no effect on the expression level of Fndc5, but significantly lowered the gene expression of myonectin in both the LZR and OZR groups. Conclusion: Contrary to prior findings regarding the regulation of Fndc5 and myonectin we show that myonectin and Fndc5 expression are both increased in the OZR model of obesity. Further, long-term exercise training decreases myonectin levels, which is opposite, the effect reported with short-term exercise. However, this report confirms earlier work showing that Fndc5 gene expression is not altered by chronic exercise.

2014 ◽  
Author(s):  
Jonathan M Peterson ◽  
Ryan Mart ◽  
Cherie E Bond

Metabolic dysfunction in skeletal muscle is a major contributor to the development of type 2 diabetes. Endurance exercise training has long been established as an effective means to directly restore skeletal muscle glucose and lipid uptake and metabolism. However, in addition to the direct effects of skeletal muscle on glucose and lipids, there is renewed interest in the ability of skeletal muscle to coordinate metabolic activity of other tissues, such as adipose tissue and liver. The purpose of this study was to examine the effects of endurance exercise on the expression level of two novel muscle-derived secreted factors, or myokines, Myonectin and Fibronectin type III domain containing 5 (Fndc5), the precursor for Irisin. Methods: We used the diaphragm muscle from both the obese Zucker rat (OZR) and lean Zucker Rat (LZR) with 9 weeks of aerobic training on a motorized treadmill. We examined the gene expression of 12 commonly used reference genes and performed quantitative real-time PCR analysis on the gene expression of Myonectin and Fndc5. Results: Of the 12 commonly used PCR reference genes tested we were able to establish that Hypoxanthine phosphoribosyltransferase 1 (HPRT1) and lactate dehydrogenase A (Ldha) remained stable in the diaphragm muscle regardless of obesity or exercise training. Interestingly, we also concluded that the commonly used reference genes: beta-Actin, beta-2-microglobulin, Non-POU domain containing, octamer-binding, Peptidylprolyl isomerase H, 18S ribosomal rna, TATA box binding protein and Transferrin receptor were all found to be altered by the combination of exercise and obesity. Our study showed that the diaphragm muscle of the OZR had significantly higher expression levels of both myonectin and Fndc5. Exercise training had no effect on the expression level of Fndc5, but significantly lowered the gene expression of myonectin in both the LZR and OZR groups. Conclusion: Contrary to prior findings regarding the regulation of Fndc5 and myonectin we show that myonectin and Fndc5 expression are both increased in the OZR model of obesity. Further, long-term exercise training decreases myonectin levels, which is opposite, the effect reported with short-term exercise. However, this report confirms earlier work showing that Fndc5 gene expression is not altered by chronic exercise.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Fei Xiong ◽  
Xiangyun Cheng ◽  
Chao Zhang ◽  
Roland Manfred Klar ◽  
Tao He

Abstract Background Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) remains one of the best-established techniques to assess gene expression patterns. However, appropriate reference gene(s) selection remains a critical and challenging subject in which inappropriate reference gene selction can distort results leading to false interpretations. To date, mixed opinions still exist in how to choose the most optimal reference gene sets in accodrance to the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guideline. Therefore, the purpose of this study was to investigate which schemes were the most feasible for the identification of reference genes in a bone and cartilage bioengineering experimental setting. In this study, rat bone mesenchymal stem cells (rBMSCs), skeletal muscle tissue and adipose tissue were utilized, undergoing either chondrogenic or osteogenic induction, to investigate the optimal reference gene set identification scheme that would subsequently ensure stable and accurate interpretation of gene expression in bone and cartilage bioengineering. Results The stability and pairwise variance of eight candidate reference genes were analyzed using geNorm. The V0.15- vs. Vmin-based normalization scheme in rBMSCs had no significant effect on the eventual normalization of target genes. In terms of the muscle tissue, the results of the correlation of NF values between the V0.15 and Vmin schemes and the variance of target genes expression levels generated by these two schemes showed that different schemes do indeed have a significant effect on the eventual normalization of target genes. Three selection schemes were adopted in terms of the adipose tissue, including the three optimal reference genes (Opt3), V0.20 and Vmin schemes, and the analysis of NF values with eventual normalization of target genes showed that the different selection schemes also have a significant effect on the eventual normalization of target genes. Conclusions Based on these results, the proposed cut-off value of Vn/n + 1 under 0.15, according to the geNorm algorithm, should be considered with caution. For cell only experiments, at least rBMSCs, a Vn/n + 1 under 0.15 is sufficient in RT-qPCR studies. However, when using certain tissue types such as skeletal muscle and adipose tissue the minimum Vn/n + 1 should be used instead as this provides a far superior mode of generating accurate gene expression results. We thus recommended that when the stability and variation of a candidate reference genes in a specific study is unclear the minimum Vn/n + 1 should always be used as this ensures the best and most accurate gene expression value is achieved during RT-qPCR assays.


1997 ◽  
Vol 82 (6) ◽  
pp. 1862-1868 ◽  
Author(s):  
Richard M. McAllister ◽  
Brian L. Reiter ◽  
John F. Amann ◽  
M. Harold Laughlin

McAllister, Richard M., Brian L. Reiter, John F. Amann, and M. Harold Laughlin. Skeletal muscle biochemical adaptations to exercise training in miniature swine. J. Appl. Physiol. 82(6): 1862–1868, 1997.—The primary purpose of this study was to test the hypothesis that endurance exercise training induces increased oxidative capacity in porcine skeletal muscle. To test this hypothesis, female miniature swine were either trained by treadmill running 5 days/wk over 16–20 wk (Trn; n = 35) or pen confined (Sed; n = 33). Myocardial hypertrophy, lower heart rates during submaximal stages of a maximal treadmill running test, and increased running time to exhaustion during that test were indicative of training efficacy. A variety of skeletal muscles were sampled and subsequently assayed for the enzymes citrate synthase (CS), 3-hydroxyacyl-CoA dehydrogenase, and lactate dehydrogenase and for antioxidant enzymes. Fiber type composition of a representative muscle was also determined histochemically. The largest increase in CS activity (62%) was found in the gluteus maximus muscle (Sed, 14.7 ± 1.1 μmol ⋅ min−1 ⋅ g−1; Trn, 23.9 ± 1.0; P < 0.0005). Muscles exhibiting increased CS activity, however, were located primarily in the forelimb; ankle and knee extensor and respiratory muscles were unchanged with training. Only two muscles exhibited higher 3-hydroxyacyl-CoA dehydrogenase activity in Trn compared with Sed. Lactate dehydrogenase activity was unchanged with training, as were activities of antioxidant enzymes. Histochemical analysis of the triceps brachii muscle (long head) revealed lower type IIB fiber numbers in Trn (Sed, 42 ± 6%; Trn, 10 ± 4; P < 0.01) and greater type IID/X fiber numbers (Sed, 11 ± 2; Trn, 22 ± 3; P < 0.025). These findings indicate that porcine skeletal muscle adapts to endurance exercise training in a manner similar to muscle of humans and other animal models, with increased oxidative capacity. Specific muscles exhibiting these adaptations, however, differ between the miniature swine and other species.


2017 ◽  
Vol 123 (2) ◽  
pp. 460-472 ◽  
Author(s):  
Scott K. Powers

Endurance exercise training promotes numerous cellular adaptations in both cardiac myocytes and skeletal muscle fibers. For example, exercise training fosters changes in mitochondrial function due to increased mitochondrial protein expression and accelerated mitochondrial turnover. Additionally, endurance exercise training alters the abundance of numerous cytosolic and mitochondrial proteins in both cardiac and skeletal muscle myocytes, resulting in a protective phenotype in the active fibers; this exercise-induced protection of cardiac and skeletal muscle fibers is often referred to as “exercise preconditioning.” As few as 3–5 consecutive days of endurance exercise training result in a preconditioned cardiac phenotype that is sheltered against ischemia-reperfusion-induced injury. Similarly, endurance exercise training results in preconditioned skeletal muscle fibers that are resistant to a variety of stresses (e.g., heat stress, exercise-induced oxidative stress, and inactivity-induced atrophy). Many studies have probed the mechanisms responsible for exercise-induced preconditioning of cardiac and skeletal muscle fibers; these studies are important, because they provide an improved understanding of the biochemical mechanisms responsible for exercise-induced preconditioning, which has the potential to lead to innovative pharmacological therapies aimed at minimizing stress-induced injury to cardiac and skeletal muscle. This review summarizes the development of exercise-induced protection of cardiac myocytes and skeletal muscle fibers and highlights the putative mechanisms responsible for exercise-induced protection in the heart and skeletal muscles.


2020 ◽  
Vol 318 (4) ◽  
pp. E492-E503
Author(s):  
Kenichi Tanaka ◽  
Hirokazu Takahashi ◽  
Sayaka Katagiri ◽  
Kazuyo Sasaki ◽  
Yujin Ohsugi ◽  
...  

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have been reported to improve obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) in addition to exercise training, whereas the combined effects remain to be elucidated fully. We investigated the effect of the combination of the SGLT2i canagliflozin (CAN) and exercise training in high-fat diet-induced obese mice. High-fat diet-fed mice were housed in normal cages (sedentary; Sed) or wheel cages (WCR) with or without CAN (0.03% of diet) for 4 wk. The effects on obesity, glucose metabolism, and hepatic steatosis were evaluated in four groups (Control/Sed, Control/WCR, CAN/Sed, and CAN/WCR). Numerically additive improvements were found in body weight, body fat mass, blood glucose, glucose intolerance, insulin resistance, and the fatty liver of the CAN/WCR group, whereas CAN increased food intake and reduced running distance. Exercise training alone, CAN alone, or both did not change the weight of skeletal muscle, but microarray analysis showed that each resulted in a characteristic change of gene expression in gastrocnemius muscle. In particular, in the CAN/WCR group, there was acceleration of the angiogenesis pathway and suppression of the adipogenesis pathway compared with the CAN/Sed group. In conclusion, the combination of an SGLT2i and exercise training improves obesity, insulin resistance, and NAFLD in an additive manner. Changes of gene expression in skeletal muscle may contribute, at least in part, to the improvement of obesity and insulin sensitivity.


2018 ◽  
Vol 20 (1) ◽  
pp. 34 ◽  
Author(s):  
Jing-Jing Wang ◽  
Shuo Han ◽  
Weilun Yin ◽  
Xinli Xia ◽  
Chao Liu

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most sensitive technique for evaluating gene expression levels. Choosing appropriate reference genes for normalizing target gene expression is important for verifying expression changes. Metasequoia is a high-quality and economically important wood species. However, few systematic studies have examined reference genes in Metasequoia. Here, the expression stability of 14 candidate reference genes in different tissues and following different hormone treatments were analyzed using six algorithms. Candidate reference genes were used to normalize the expression pattern of FLOWERING LOCUS T and pyrabactin resistance-like 8. Analysis using the GrayNorm algorithm showed that ACT2 (Actin 2), HIS (histone superfamily protein H3) and TATA (TATA binding protein) were stably expressed in different tissues. ACT2, EF1α (elongation factor-1 alpha) and HIS were optimal for leaves treated with the flowering induction hormone solution, while Cpn60β (60-kDa chaperonin β-subunit), GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and HIS were the best reference genes for treated buds. EF1α, HIS and TATA were useful reference genes for accurate normalization in abscisic acid-response signaling. Our results emphasize the importance of validating reference genes for qRT-PCR analysis in Metasequoia. To avoid errors, suitable reference genes should be used for different tissues and hormone treatments to increase normalization accuracy. Our study provides a foundation for reference gene normalization when analyzing gene expression in Metasequoia.


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