Myostatin Gene Expression Research Articles

Effect of prior application with and without post-injury treatment with low-level laser on the modulation of key proteins in the muscle repair process.

The aim of the present study was to evaluate the effects of LLLT prior to muscle injury with and without post-injury irradiation on the expression of isoforms of myosin heavy chain (MyHC), calcineurin (CaN), and myostatin during the repair process. Wistar rats were divided into five groups: control (n = 7); injury (n = 21); LLLT + injury (n = 21); injury + LLLT (n = 21), and LLLT + injury + LLLT (n = 21). Cryoinjury was performed on the tibialis anterior (TA) muscle. The injured groups were euthanized at 3, 7, and 14days after injury. LLLT was performed using an infrared laser (780nm) with the following parameters: 10J/cm2, 40mW, 10s per point, 8 points, and 3.2J of total energy. At the end of each period, the TA muscle was removed for the analysis of MyHC, CaN, and myostatin gene expression using real-time PCR. The data were tested statistically by Kruskal-Wallis with Dunn's post hoc test (p < 0.05). The results demonstrated that prior irradiation reduced the mRNA expression of all proteins at 3days. Post irradiation reduced the mRNA expression of MyHC-1, MyHC-2a, MyHC-2b, and CaN at 7days. Prior irradiation combined with post-injury irradiation reduced the mRNA expression of MyHC-2x and CaN at 14days and increased the mRNA expression of myostatin in the same period. In conclusion, different protocols of photobiomodulation can modulate the expression of the different isoforms of MyHC, CaN, and myostatin during the repair process. It is noteworthy that the combination of the prior and post-injury irradiation was the protocol that most promoted changes in the final phase of the repair process.

Experimental Increases in Foraging Costs Affect Pectoralis Muscle Mass and Myostatin Expression in Female, but Not Male, Zebra Finches (Taeniopygia guttata).

Skeletal muscle remodeling is an important component of phenotypic flexibility in birds and impacts organismal metabolism and performance, which could potentially influence fitness. One regulator of skeletal muscle remodeling is myostatin, an autocrine/paracrine muscle growth inhibitor that may be down-regulated under conditions promoting heavier muscle masses. In this study, we employed protocols requiring hovering while foraging to increase foraging costs and modify phenotypes of zebra finches (Taeniopygia guttata). We examined the effects of high-cost foraging (HF) on skeletal muscle masses and used real-time reverse-transcription polymerase chain reaction and Western blots to measure gene and protein expression of myostatin and its metalloproteinase activators tolloid-like proteases TLL-1 and TLL-2 in pectoralis muscle. Female finches average shorter wings and higher wing loading than males, so increased flight costs might be expected to disproportionately affect females. Indeed, HF female finches exhibited reduced total fat masses, increased pectoralis muscle masses, and lower myostatin protein levels than controls. Male finches showed no significant differences in pectoralis muscle masses or myostatin protein levels between HF and control birds. Myostatin, TLL-1, and TLL-2 messenger RNA (mRNA) expression remained stable between treatments for both female and male finches. Myostatin mRNA and protein levels showed variable directions of correlations with pectoralis mass residuals among treatments. Thus, these data offer only mixed support for a regulatory role for myostatin in mediating the flexibility of pectoralis muscle phenotypes of small birds.

Myostatin Gene Expression and Its Application on Goat Breeding Programme

Characteristics of double muscled growth in animals are influenced by myostatin gene (MSTN). Myostatin gene is known as a member of the growth gene's superfamily (TGF-β) which works to suppress the muscle growth. However, the presence of six mutations on MSTN cause the gene inactive, and trigger the occurrence of muscle hypertrophy. Identification of myostatin gene was conducted by molecular techniques, and the most common method is polymerase chain reaction followed by single-strand conformation polymorphism (PCR-SSCP). Research on sheep and goat in several countries showed that there had been several variations occurred in myostatin gene but further studies are required to correlate these variations to body weight gain and other important production parameters. For goat production in Indonesia, myostatin mutations cause double muscling that can be utilised for genetic improvement in goat breeding plan to produce a new breed with high quality meat.

High versus Low doses of Anti-inflammatory Drugs Do Not Differentially Affect Muscle Molecular Response to Acute Resistance Exercise

PURPOSE: We recently reported that high doses of non-steroidal anti-inflammatory drugs (NSAIDs) attenuate resistance exercise-induced muscle hypertrophy in young adults. Yet, little is known about the molecular mechanisms behind this effect. The current study aimed to examine acute muscle molecular responses to resistance exercise during co- ingestion of high and low doses of anti-inflammatory drugs. METHODS: Thirty one young (age 18-35 years) healthy men and women were randomly assigned to daily consumption of high doses of ibuprofen (IBU; 1200 mg; n=15) or low doses of acetylsalicylic acid (ASA; 75 mg; n=16) during an 8-week training intervention. During this period, subjects performed 20 supervised resistance training sessions (4 x 7-12 repetitions) involving the knee extensor muscles. Gene expression and protein signaling of key muscle growth regulators were analyzed from skeletal muscle biopsies obtained before training/treatment and 3 hours after an acute resistance exercise session during week 4 of the intervention. Real-time qPCR procedures were employed to determine mRNA expression. Protein signaling was assessed using western blots. RESULTS: Gene expression of myostatin (0.4-fold; p>0.0005), MuRF-1 (0.8-fold; p=0.015) and FoxO3 (0.6-fold; p>0.0005) decreased in response to the resistance exercise bout, with no difference across groups. Gene expression of IL-6 and STAT3 were unaltered. Protein phosphorylation of p70S6K increased (24-fold, P>0.0005) in response to the resistance exercise bout, with no difference across groups. Protein phosphorylation of STAT3 remained unchanged. CONCLUSIONS: These results show that high and low doses of NSAIDs do not differentially affect exercise-induced changes in gene expression and protein signaling for key markers of muscle growth in young adults. We therefore conclude that these acute markers do not seem to explain the negative effects of high doses of NSAIDs on muscle hypertrophy.

Myostatin: Twenty Years Later

In recent years, there has been an increasing interest in myostatin, a hormone that inhibits the growth and differentiation of muscle tissue. This interest is associated with an increase in the amount of data on the spectrum of the myostatin functioning. Myostatin, which has been known since 1997, belongs to the family of transforming growth factor β (TGF-β) and is a paracrine factor of skeletal muscle myocytes. It turned out that myostatin also affects the satellite cells and muscle fibroblasts, and its functions are not only to limit growth, but also to remodel skeletal muscles, which is necessary for muscle adaptation to physical training. Recent studies show that myostatin can play a significant role in musculoskeletal and cardiac cachexias in various pathologies, including cancer. It has been found that myostatin can be produced not only by skeletal muscle cells, but also by adipocytes and cardiomyocytes. It has been shown that, in cardiac pathology, the level of myostatin production increases in cardiac tissue. It is suggested that an increase in the myostatin production in the heart is necessary to prevent myocardial hypertrophy, which develops in some cardiac diseases. In this review, we examined the myostatin functions, as well as aspects of myostatin gene expression, mechanisms of its biosynthesis, its effect on various intracellular targets and transcription factors, and the regulation of its production. The importance of myostatin functions, as well as its involvement in pathological processes, allows us to consider this hormone as a promising target in therapeutic studies.

Prevention of chemotherapy-induced cachexia by ACVR2B ligand blocking has different effects on heart and skeletal muscle.

BackgroundToxicity of chemotherapy on skeletal muscles and the heart may significantly contribute to cancer cachexia, mortality, and decreased quality of life. Doxorubicin (DOX) is an effective cytostatic agent, which unfortunately has toxic effects on many healthy tissues. Blocking of activin receptor type IIB (ACVR2B) ligands is an often used strategy to prevent skeletal muscle loss, but its effects on the heart are relatively unknown.MethodsThe effects of DOX treatment with or without pre‐treatment with soluble ACVR2B‐Fc (sACVR2B‐Fc) were investigated. The mice were randomly assigned into one of the three groups: (1) vehicle (PBS)‐treated controls, (2) DOX‐treated mice (DOX), and (3) DOX‐treated mice administered with sACVR2B‐Fc during the experiment (DOX + sACVR2B‐Fc). DOX was administered with a cumulative dose of 24 mg/kg during 2 weeks to investigate cachexia outcome in the heart and skeletal muscle. To understand similarities and differences between skeletal and cardiac muscles in their responses to chemotherapy, the tissues were collected 20 h after a single DOX (15 mg/kg) injection and analysed with genome‐wide transcriptomics and mRNA and protein analyses. The combination group was pre‐treated with sACVR2B‐Fc 48 h before DOX administration. Major findings were also studied in mice receiving only sACVR2B‐Fc.ResultsThe DOX treatment induced similar (~10%) wasting in skeletal muscle and the heart. However, transcriptional changes in response to DOX were much greater in skeletal muscle. Pathway analysis and unbiased transcription factor analysis showed that p53‐p21‐REDD1 is the main common pathway activated by DOX in both skeletal and cardiac muscles. These changes were attenuated by blocking ACVR2B ligands especially in skeletal muscle. Tceal7 (3‐fold to 5‐fold increase), transferrin receptor (1.5‐fold increase), and Ccl21 (0.6‐fold to 0.9‐fold decrease) were identified as novel genes responsive to blocking ACVR2B ligands. Overall, at the transcriptome level, ACVR2B ligand blocking had only minor influence in the heart while it had marked effects in skeletal muscle. The same was also true for the effects on tissue wasting. This may be explained in part by about 18‐fold higher gene expression of myostatin in skeletal muscle compared with the heart.ConclusionsCardiac and skeletal muscles display similar atrophy after DOX treatment, but the mechanisms for this may differ between the tissues. The present results suggest that p53‐p21‐REDD1 signalling is the main common DOX‐activated pathway in these tissues and that blocking activin receptor ligands attenuates this response, especially in skeletal muscle supporting the overall stronger effects of this treatment in skeletal muscles.

Effect of eccentric action velocity on expression of genes related to myostatin signaling pathway in human skeletal muscle.

The aim of this study was to investigate the effects of an acute bout of eccentric actions, performed at fast velocity (210º.s-1) and at slow velocity (20º.s-1), on the gene expression of regulatory components of the myostatin (MSTN) signalling pathway. Participants performed an acute bout of eccentric actions at either a slow or a fast velocity. Muscle biopsy samples were taken before, immediately after, and 2 h after the exercise bout. The gene expression of the components of the MSTN pathway was assessed by real-time PCR. No change was observed in MSTN, ACTRIIB, GASP-1 or FOXO-3a gene expression after either slow or fast eccentric actions (p > 0.05). However, the MSTN inhibitors follistatin (FST), FST-like-3 (FSTL3) and SMAD-7 were significantly increased 2 h after both eccentric actions (p < 0.05). No significant difference between bouts was found before, immediately after, or 2 h after the eccentric actions (slow and fast velocities, p > 0.05). The current findings indicate that a bout of eccentric actions activates the expression of MSTN inhibitors. However, no difference was observed in MSTN inhibitors’ gene expression when comparing slow and fast eccentric actions. It is possible that the greater time under tension induced by slow eccentric (SE) actions might compensate the effect of the greater velocity of fast eccentric (FE) actions. Additional studies are required to address the effect of eccentric action (EA) velocities on the pathways related to muscle hypertrophy.

Electrical pulse stimulation: an in vitro exercise model for the induction of human skeletal muscle cell hypertrophy. A proof-of-concept study.

What is the central question of this study? Is electrical pulse stimulation (EPS) an in vitro exercise model able to elicit the hypertrophy of human muscle cells? What is the main finding and its importance? The addition of a restitution period of 8h after EPS induces the enlargement of human muscle cells, a major physiological end-point to resistance exercise. This is supported by downregulationof myostatin, a negative regulator of muscle mass, and increased phosphorylated mTOR and 4E-BP1, key factors in the growth cascade. This proof-of-concept study provides a model of physiologically mediated muscle growth, which will be the basis for future studies aiming to depict molecular events governing the hypertrophy of human muscle cells. Electrical pulse stimulation (EPS) of muscle cells has previouslybeenused as an in vitro exercise model. The present study aimedto establish an EPS protocol promoting the hypertrophy ofhuman muscle cells, which represents a major physiological end-point to resistance exercise in humans. We hypothesized that adding a resting period after EPS would be crucial for the occurrence of the morphological change. Myoblasts obtained from human muscle biopsies (n=5) were differentiated into multinucleated myotubes and exposed to 8h of EPS consisting of 2ms pulses at 12V, with a frequency of 1Hz. Myotube size was assessed using immunohistochemistry immediately, 4 and 8h after completed EPS. Gene expression and phosphorylation status of selected markers of hypertrophy were assessed using RT-PCR and Western blotting, respectively. Release of the myokine interleukin-6 in culture medium was measured using enzyme-linked immunosorbent assay. We demonstrated a significant increase (31±14%; P=0.03) in the size of myotubes when EPS was followed by an 8h resting period, but not immediately or 4h after completion of EPS. The response was supported by downregulation (P=0.04) of the gene expression of myostatin, a negative regulator of muscle mass, and an increase in phosphorylated mTOR (P=0.03) and 4E-BP1 (P=0.01), which are important factors in the cellular growth signalling cascade. The present work demonstrates that EPS is an in vitro exercise model promoting the hypertrophy of human muscle cells, recapitulating a major physiological end-point to resistance exercise in human skeletal muscle.

Effect of acute treadmill exercise on cisplatin-induced muscle atrophy in the mouse.

Cisplatin, a platinum-based anti-cancer drug, is one of the most effective broad-spectrum anti-cancer agents used against various cancers. It has been recently suggested that low skeletal muscle mass is predictive of mortality in patients with cancer. Although several molecules produced by the actual tumor itself contribute to skeletal muscle impairment, we recently suggested that the administration of cisplatin could increase levels of muscle RING finger-1 (MuRF1) and atrogin-1, possibly leading to muscle atrophy in the mouse. Exercise is an important factor that induces muscle protein synthesis and muscle hypertrophy by enhancing the positive effects of the Akt/mTOR/p70S6 kinase pathway. In the present study, we therefore investigated the effect of treadmill exercise on cisplatin-induced muscle atrophy. C57BL/6J mice were treated with cisplatin (3mg/kg, i.p.) or saline for four consecutive days. On day 4, the quadriceps and gastrocnemius muscles were isolated from the mice. The animals in the treadmill exercise groups were forced to run on a motorized treadmill for 20min once a day for 9days. In addition to muscle mass, the decrease in myofiber diameter associated with cisplatin administration was significantly restored by treadmill exercise. This exercise also significantly attenuated cisplatin-induced upregulation of MuRF1 and atrogin-1 in quadriceps and gastrocnemius muscle. The decreased Akt, p70S6 kinase, and Foxo3a phosphorylation observed with cisplatin treatment was significantly recovered by treadmill exercise in both the muscles. In the present study, myostatin (Mstn) gene expression, upregulated by cisplatin administration, was also attenuated by treadmill exercise. These findings suggest that treadmill exercise could attenuate cisplatin-induced muscle atrophy, at least partially, and could improve prognosis.

Age and sex differences in human skeletal muscle fibrosis markers and transforming growth factor-β signaling.

The aim of the study was to determine whether higher fibrosis markers in skeletal muscle of older adults are accompanied by increased expression of components of the canonical TGF-β signal transduction pathway. Fourteen healthy young (21-35years; 9 males and 5 females) and seventeen older (55-75years; 9 males and 8 females) participants underwent vastus lateralis biopsies to determine intramuscular mRNA and protein expression of fibrogenic markers and TGF-β signaling molecules related to TGF-β1 and myostatin. Expression of mRNA encoding the pro-fibrotic factors; axin 2, collagen III, β-catenin and fibronectin, were all significantly higher (all p<0.05) in the older participants (350, 170, 298, and 641%, respectively). Furthermore, axin 2 and β-catenin mRNA were significantly higher in older females than older males (p<0.05). Gene expression of ActRIIB, myostatin, and TGF-β1 were higher in older adults compared to younger adults (all p<0.05). There was, however, no difference in the total protein content of myostatin, myoD or myogenin (all p>0.05), whereas Smad3 protein phosphorylation was 48% lower (p<0.05) in muscle from older adults. Increased abundance of mRNA of fibrotic markers was observed in muscle from older adults and was partly accompanied by altered abundance of pro-fibrotic ligands in a sex specific manner.

Rhaponticum carthamoides and Rhodiola rosea plant extracts: the right combination between both to get the optimal effect on muscle de novo protein synthesis and performance gain

We previously reported in C2C12 myotubes that a Rhaponticum carthamoides root extract (RCE) was able to significantly stimulate protein synthesis and induce an activation of the Akt/mTOR signalling pathway (induction of Akt and S6K1 phospohrylations), that a Rhodiola rosea root extract (RRE) had also the capacity to induce protein synthesis and to inhibit myostatin gene expression and that the combination of both exhibited inhibition of atrogin gene expression (unpublished). Therefore, we aimed to investigate the effects of RCE or RRE alone or combinations of both on acute muscle protein synthesis stimulation and on performance gain following a 4-week resistance training program in adult rats. Acutely, rats were trained on a ladder making 3 repetitions of 10 climbs with a load that successively reached 0%, 50% and 75% of their body mass and were fed (oral gavage) just after training with either placebo, whey protein (910 mg/kg bw) as a positive control, RRE (43 mg/kg bw), RCE (43 mg/kg) and different doses of a 50:50 combination of both (87, 43, 22 or 9 mg/kg bw). RCE alone but not RRE was able to significantly stimulate protein synthesis as measured by western blot quantitative analysis of puromycin incorporation in the flexor digitorum profondus (FDP) and in comparison to placebo (200% versus 100% for RCE and placebo group respectively). Any doses of the combination was significantly superior to RRE alone (300% versus 150%) or RCE alone (300% versus 200%) and also significantly superior to whey proteins (300% versus 150%). The same results were obtained in the biceps and deltoid muscles. In the second part of the study rats followed a 4-week progressive resistance training program while consuming RRE alone (22 mg/kg), RCE alone (22 mg/kg) and different ratio and doses of the combination (50:50 ratio: 43, 22 or 9 mg/kg bw; 83 RCE:17 RRE ratio: 26 mg/kg; 76 RCE:24 RRE ratio: 28 mg/kg; 70 RCE:30 RRE ratio: 15 mg/kg. Training sessions (19) consisted in one set of 10 repetitions with 2 minutes rest between trials and 5 minutes between each set, were held five times a week with initial load fixed at 50% of the rat body weight and increased progressively until 200% after 4 weeks. Maximal repetition was determined as the maximum weight carried up the exercise ladder by the rats in one climb and performance gain was calculated as delta power (post versus pre resistance training). As shown in Figure 1, RCE alone but not RRE was able to significantly increase performance gain in comparison to placebo after 4 weeks of resistance training (0.66±0.08 versus 0.39±0.08 W respectively, + 65%, p<0.05). A synergistic effect on performance gain was detected for the 50:50 combination but interestingly, the combination ratio 70:30 warranted the best improvement of performance gain with the lower daily dosage (15 mg/kg bw) in comparison to placebo (0.62±0.08 versus 0.39±0.08 W respectively, + 59%, p<0.05). These results clearly demonstrated synergy of the combination of extracts on protein synthesis stimulation in the FDP, deltoid and biceps muscles following acute resistance exercise and an improvement of performance gain following a 4-week resistance training program. Those effects are currently investigated in recreationally active men and histological analysis of muscle fibers are under investigations in rats to understand what could drive the effect on performance.

Effect of propolis ethanol extract on myostatin gene expression and muscle morphometry of Nile tilapia in net cages.

Propolis can be used as growth enhancer due to its antimicrobial, antioxidant, and immune-stimulant properties, but its effects on morphometry and muscle gene expression are largely unknown. The present study evaluates the influence of propolis on muscle morphometry and myostatin gene expression in Nile tilapia (Oreochromis niloticus) bred in net cages. Reversed males (GIFT strain) with an initial weight of 170 ± 25 g were distributed in a (2 x 4) factorial scheme, with two diets (DPRO, commercial diet with 4% propolis ethanol extract and DCON, commercial diet without propolis, control) and four assessment periods (0, 35, 70, and 105 experimental days). Muscles were evaluated at each assessment period. Histomorphometric analysis classified the fiber diameters into four groups: <20 μm; 20-30 μm; 30-50 μm; and > 50 μm. RT-qPCR was performed to assess myostatin gene expression. Fibers < 20 µm diameter were more frequent in DPRO than in DCON at all times. Fiber percentages >30 µm (30-50 and > 50 µm) at 70 days were 25.39% and 40.07% for DPRO and DCON, respectively. There was greater myostatin gene expression at 105 days, averaging 1.93 and 1.89 for DCON and DPRO, respectively, with no significant difference in any of the analyzed periods. Propolis ethanol extract did not affect the diameter of muscle fibers or the gene expression of myostatin. Future studies should describe the mechanisms of natural products' effects on muscle growth and development since these factors are highly relevant for fish production performance.

Dietary supplementation of inosine monophosphate promotes cellular growth of muscle and upregulates growth-related gene expression in Nile tilapia Oreochromis niloticus

Muscle growth mechanisms are controlled by different cellular and molecular pathways, and dietary supplementation of nucleotides (NTs) may play an important role to influence such pathways in fish. In this study, we hypothesized that dietary supplementation of inosine monophosphate (IMP) would enhance cellular muscle growth, and upregulate growth-related gene expression in juvenile Nile tilapia Oreochromis niloticus. Five isonitrogenous (40% crude protein) and isocaloric (20.3 KJ/g diet) test diets were formulated by supplementing 0, 0.1, 0.2, 0.4 and 0.8% IMP in casein and fishmeal based semi-purified diet. Triplicate groups of juvenile Nile tilapia (0.59±0.1g) were stocked in 15 fiberglass tanks (150L capacity), arranged in a simple biological filters-based closed system, with stocking density of 25 individuals per tank. The feed was applied at a daily feeding rate of 10% body weight (BW) initially and reduced to 5% BW finally for 60days. Treatments results were compared using ANOVA (α=0.05). At 60th day (60 D), final body weight of fish fed with 0.2–0.8% IMP were significantly higher than that of fish fed without IMP supplemented diet. At 60 D, both the hyperplastic (diameter class 10=≤10μm) and hypertrophic (diameter class 60=50>d≤60μm and class 70=d>60μm) muscle fiber frequency were significantly higher in 0.2–0.8% IMP supplemented diets compared to 0–0.1% IMP supplemented diet. Two-way ANOVA result demonstrated that the pituitary GH, hepatic IGF-1 and GHR-1, and muscle-specific MyoD, myogenin and Pax7 gene expression were upregulated in fish fed with 0.2–0.8% IMP compared to the fish fed without IMP supplemented diet. However, hepatic IGF-2 and myostatin gene expression were not significantly affected by the dietary treatments. Real-time PCR data also demonstrated that myostatin gene expression was downregulated and all other gene expression were upregulated at the end of feeding trial (60 D) compared to the initial period (1 D). The results of the present study indicated that IMP supplementation enhanced the muscle growth by promoting hyperplasia and hypertrophy, and upregulating the growth-related gene expression in Nile tilapia. In conclusion, IMP is a potential feed additive and supplementation of ≥0.2% IMP is the most effective for enhancing growth of Nile Tilapia. Statement of relevance-In most cases, fish growth was analyzed by calculating the increase in size or weight of fish. However, fish/muscle growth are controlled by different cellular and molecular pathways, which are poorly studied areas in aquaculture and nutritional studies. A research was conducted to investigate the effects of dietary supplementation of inosine monophosphate on: (1) cellular muscle growth characteristics, and (2) expression of major growth-related genes (GH, GHR-1, IGFs, MRFs, Pax7 and myostatin) in juvenile Nile tilapia. This research will help to understand the reason behind the improved growth or production of fish with a specific nutrient or diet.

Correlating single nucleotide polymorphisms in the myostatin gene with performance traits in rabbit

The Myostatin (MSTN), or Growth and Differentiation Factor 8 (GDF8), gene has been implicated in the double muscling phenomenon, in which a series of mutations render the gene inactive and unable to properly regulate muscle fibre deposition. Single nucleotide polymorphisms (SNPs) in the MSTN gene have been correlated to production traits, making it a candidate target gene to enhance livestock and fowl productivity. This study aimed to assess any association of three SNPs in the rabbit MSTN gene (c.713T&amp;gt;A in exon 2, c.747+34C&amp;gt;T in intron 2, and c.*194A&amp;gt;G in 3’-untranslated region) and their combinations, with carcass, production and reproductive traits. The investigated traits included individual body weight, daily body weight gain, carcass traits and reproductive traits. The 3 SNPs were screened using PCR-restriction fragment length polymorphism (RFLP)-based analysis and the effects of the different SNP genotypes and their combinations were estimated in a rabbit population. Additionally, additive and dominance effects were estimated for significant traits. The results found no significant association between the c.713 T&amp;gt;A SNP and all the examined traits. Allele T at the c.747+34C&amp;gt;T SNP was only significantly associated (P&amp;lt;0.05) with increased body weight at 12 wk of age. However, for the SNP residing in the 3’ untranslated region (c.*194A&amp;gt;G), allele G was significantly associated (P&amp;lt;0.05) with increased body weight and high growth rate. Genotype GG at the c.*194A&amp;gt;G SNP also had positive effects on most carcass traits. The estimated additive genetic effect for the c.*194A&amp;gt;G SNP was significant (P&amp;lt;0.05) with most body weight, daily gain and carcass traits. No significant association was obtained between any MSTN SNPs and reproductive traits. In the combinations analysis, regardless of the genotypes of SNPs at c.713T&amp;gt;A and c.747+34C&amp;gt;T, GG at the c.*194A&amp;gt;G SNP correlated with highest values in body weight and daily weight gain. In conclusion, the ‘G’ allele at the c.*194A&amp;gt;G SNP had positive effects on growth and carcass traits and so could be used as a favourable allele in planning rabbit selection. Further population-wide studies are necessary to test the association of the c.*194A&amp;gt;G SNP with carcass traits. We also recommend evaluation of the potential effects of the c.*194A&amp;gt;G SNP on MSTN gene expression.

Gene Expression and Polymorphism of Myostatin Gene and its Association with Growth Traits in Chicken

ABSTRACTMyostatin is a member of TGF-β super family and is directly involved in regulation of body growth through limiting muscular growth. A study was carried out in three chicken lines to identify the polymorphism in the coding region of the myostatin gene through SSCP and DNA sequencing. A total of 12 haplotypes were observed in myostatin coding region of chicken. Significant associations between haplogroups with body weight at day 1, 14, 28, and 42 days, and carcass traits at 42 days were observed across the lines. It is concluded that the coding region of myostatin gene was polymorphic, with varied levels of expression among lines and had significant effects on growth traits. The expression of MSTN gene varied during embryonic and post hatch development stage.

Polymorphism of Myostatin (MSTN) Promoter Gene and its Association with Growth and Muscling Traits in Bali Cattle

Myostatin (MSTN) gene plays a key role in skletal muscle homeostasis such as inducing muscle athrophy, poliferation of myoblast, increasing ubiquitin-proteasomal, downregulating IGF pathway, and glucolysis. Myostatin gene expression is controled by CpG island located in promoter region. The objectives of this research were to identify polymorphism of MSTN promoter gene and to associate the polymorphism of SNP with growth and muscling traits in Bali cattle. A total of 48 Bali cattle from BPTU-HMT Bali island was screened to identify genetic polymorphisms in MSTN promoter region using sequencing method. The growth and muscling traits were measured at 12 months of age. The muscling traits were evaluated using ultrasound console with linear transducer having frequency 6.5 Hz and scaning we conducted at 130 mm in deep. Analysis of polymorphism was conducted by using PopGen 1.32 software. The association of MSTN with growth and muscling traits were analyzed by using General Linear Model (GLM) procedure. This result showed that a total of 20 polymorphic SNPs (seven SNPs in CpG island) were detected in this region. Although, only 3 SNPs (g.-8078C>T, g.-7996G>C, and g.-7930A>G) had equilibrium condition in Hardy-Weinberg analysis. The association result showed that 2 SNPs (g.-7799T>C and g.-7941C>T) were significantly associated with intramuscular fat percentage (P≤0.05) in Bali cattle. Although the 2 SNPs were nominally significant at nominal P≤0.05 threshold, they were not significant after Bonferroni correction for multiple testing. It could be concluded that MSTN promoter gene was polymorphic in Bali cattle and there were 2 SNPs associated with carcass quality.

A comparative examination of cortisol effects on muscle myostatin and HSP90 gene expression in salmonids

Cortisol, the primary corticosteroid in teleost fishes, is released in response to stressors to elicit local functions, however little is understood regarding muscle-specific responses to cortisol in these fishes. In mammals, glucocorticoids strongly regulate the muscle growth inhibitor, myostatin, via glucocorticoid response elements (GREs) leading to muscle atrophy. Bioinformatics methods suggest that this regulatory mechanism is conserved among vertebrates, however recent evidence suggests some fishes exhibit divergent regulation. Therefore, the aim of this study was to evaluate the conserved actions of cortisol on myostatin and hsp90 expression to determine if variations in cortisol interactions have emerged in salmonid species. Representative salmonids; Chinook salmon (Oncorhynchus tshawytscha), cutthroat trout (Oncorhynchus clarki), brook trout (Salvelinus fontinalis), and Atlantic salmon (Salmo salar); were injected intraperitoneally with a cortisol implant (50μg/g body weight) and muscle gene expression was quantified after 48h. Plasma glucose and cortisol levels were significantly elevated by cortisol in all species, demonstrating physiological effectiveness of the treatment. HSP90 mRNA levels were elevated by cortisol in brook trout, Chinook salmon, and Atlantic salmon, but were decreased in cutthroat trout. Myostatin mRNA levels were affected in a species, tissue (muscle type), and paralog specific manner. Cortisol treatment increased myostatin expression in brook trout (Salvelinus) and Atlantic salmon (Salmo), but not in Chinook salmon (Oncorhynchus) or cutthroat trout (Oncorhynchus). Interestingly, the VC alone increased myostatin mRNA expression in Chinook and Atlantic salmon, while the addition of cortisol blocked the response. Taken together, these results suggest that cortisol affects muscle-specific gene expression in species-specific manners, with unique Oncorhynchus-specific divergence observed, that are not predictive solely based upon mammalian stress responses.

8 Weeks of Resistance Training Effect on Myostatin Gene Expression of Myocardium in Healthy Male Wistar Rats

Aims: Based on the clinical studies, there are higher myostatin gene expression and serum level in cardiovascular patients than the healthy persons. In addition, based on some studies, regular resistance exercises is in line with a reduction in the myostatin gene expression. The aim of this study was to investigate the effects of 8-week resistance exercises on the myostatin gene expressions of myocardium in the healthy male Wistar rats. Materials & Methods: In the experimental study, 13 male adult Wistar rats, aged 15 weeks, were divided into experimental (n=7) and control (n=6) groups. In experimental group, 8-week exercises were done as climbing up a 26-step 1meter ladder, inclined 85°, with a sinker. (There were 3 sessions a week exercises; each session consisted of 3 sets of 5 repetitions.) 24 hours after the last exercise session and after 12-hour fasting, the rats being dissected, muscle tissue samples were prepared to assess mRNA levels. Data was analyzed in SPSS 16 software using independent T test. Findings: After 8-week resistance exercises, there was no significant difference in the myostatin mRNA expression level in the myocardium between experimental (1.56±0.44) and control (1.94±0.55) groups (p=0.197). Conclusion: 8-week resistance exercises leads to no significant change in the myostatin gene expression of myocardium in the healthy Wistar male rats.

Insulin signaling and skeletal muscle atrophy and autophagy in transition dairy cows either overfed energy or fed a controlled energy diet prepartum.

During periods of negative energy balance, mobilization of muscle is a physiologic process providing energy and amino acids. This is important in transition dairy cows experiencing negative energy and protein balance postpartum. Overconsumption of energy during late pregnancy affects resting glucose and insulin concentrations peripartum and increases the risk for hyperketonemia postpartum, but the effects on muscle tissue are not fully understood. Skeletal muscle accounts for the majority of insulin-dependent glucose utilization in ruminants. Our objective was to study peripartal skeletal muscle insulin signaling as well as muscle accretion and atrophy in cows with excess energy consumption prepartum. Skeletal muscle biopsies were obtained 28 and 10 days prepartum, as well as 4 and 21 days postpartum from 24 Holstein cows. Biopsies were taken immediately before and 60 min after intravenous glucose challenge causing endogenous release of insulin. Gene expression of IGF-1, myostatin, and atrogin-1, as well as immunoblot analysis of atrogin-1, muRF1, ubiquitinated proteins, LC3, and phosphorylation of AKT, ERK and mTORC1 substrate 4EBP1 was performed. Excess energy consumption in late pregnancy did not lead to changes in insulin-dependent molecular regulation of muscle accretion or atrophy compared with the controlled energy group. In both groups, phosphorylation of AKT and mTORC1 substrate was significantly decreased postpartum whereas proteasome activity and macroautopagy were upregulated. This study showed that in addition to the proteasome pathway of muscle atrophy, macroautophagy is upregulated in postpartum negative energy and protein balance regardless of dietary energy strategy prepartum and was higher in cows overfed energy throughout the study period.

Loss of Ovarian Function Results in Increased Loss of Skeletal Muscle in Arthritic Rats.

We studied the effects of loss of ovarian function (ovariectomy) on muscle mass of gastrocnemius and the mRNA levels of IGF-1, atrogin-1, MuRF-1, and myostatin in an experimental model of rheumatoid arthritis in rats. We randomly allocated 24 female Wistar rats (9 weeks, 195.3 ± 17.4 grams) into four groups: control (CT-Sham; n = 6); rheumatoid arthritis (RA; n = 6); ovariectomy without rheumatoid arthritis (OV; n = 6); ovariectomy with rheumatoid arthritis (RAOV; n = 6). We performed the ovariectomy (OV and RAOV) or Sham (CT-Sham or RA) procedures at the same time, fifteen days before the rheumatoid arthritis induction. The RA and RAOV groups were immunized and then were injected with Met-BSA in the tibiotarsal joint. After 15 days of intra-articular injections the animals were euthanized. We evaluated the external manifestations of rheumatoid arthritis (perimeter joint) as well as animal weight, and food intake throughout the study. We also analyzed the cross-sectional areas (CSA) of gastrocnemius muscle fibers in 200 fibers (H&E method). In the gastrocnemius muscle, we analyzed mRNA expression by quantitative real time PCR followed by the Livak method (ΔΔCT). The rheumatoid arthritis induced reduction in CSA of gastrocnemius muscle fibers. The RAOV group showed a lower CSA of gastrocnemius muscle fibers compared to RA and CT-Sham groups. Skeletal muscle IGF-1 mRNA increased in arthritics and ovariectomized rats. The increased IGF-1 mRNA was higher in OV groups than in the RA and RAOV groups. Antrogin-1 mRNA also increased in the gastrocnemius muscle of arthritic and ovariectomized rats. However, the increased atrogin-1 mRNA was higher in RAOV groups than in the RA and OV groups. Gastrocnemius muscle MuRF-1 mRNA increased in the OV and RAOV groups, but not in the RA and Sham groups. However, the RAOV group showed higher MuRF-1 mRNA than the OV group. The myostatin gene expression was similar in all groups. Loss of ovarian function results in increased loss of skeletal muscle-related ubiquitin ligases atrogin-1 and MuRF-1 in arthritic rats.