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Skeletal muscle hypertrophy

Hsien-Chun Chiu, Chen-Yuan Chiu, Rong-Sen Yang, Ding-Cheng Chan, Shing-Hwa Liu, Chih-Kang Chiang
BACKGROUND: A global consensus on the loss of skeletal muscle mass and function in humans refers as sarcopenia and cachexia including diabetes, obesity, renal failure, and osteoporosis. Despite a current improvement of sarcopenia or cachexia with exercise training and supportive therapies, alternative and specific managements are needed to discover for whom are unable or unwilling to embark on these treatments. Alendronate is a widely used drug for osteoporosis in the elderly and postmenopausal women...
March 6, 2018: Journal of Cachexia, Sarcopenia and Muscle
Bill Tachtsis, Donny Camera, Orly Lacham-Kaplan
Omega-3 polyunsaturated fatty acids (n-3 PUFAs), which are commonly found in fish oil supplements, are known to possess anti-inflammatory properties and more recently alter skeletal muscle function. In this review, we discuss novel findings related to how n-3 PUFAs modulate molecular signaling responsible for growth and hypertrophy as well as the activity of muscle stem cells. Muscle stem cells commonly known as satellite cells, are primarily responsible for driving the skeletal muscle repair process to potentially damaging stimuli, such as mechanical stress elicited by exercise contraction...
March 5, 2018: Nutrients
Stefan M Reitzner, Jessica Norrbom, Carl Johan Sundberg, Eva-Karin Gidlund
The striated activator of rho-signaling (STARS) protein acts as a link between external stimuli and exercise adaptation such as muscle hypertrophy. However, the acute and long-term adaptational response of STARS is still unclear. This study aimed at investigating the acute and long-term endurance training response on the mRNA and protein expression of STARS and its related upstream and downstream factors in human skeletal muscle. mRNA and protein levels of STARS and related factors were assessed in skeletal muscle of healthy young men and women following an acute bout of endurance exercise (n = 15) or 12 weeks of one-legged training (n = 23)...
March 2018: Physiological Reports
Joanne Young, Yoran Margaron, Mathieu Fernandes, Eve Duchemin-Pelletier, Joris Michaud, Mélanie Flaender, Oana Lorintiu, Sébastien Degot, Pauline Poydenot
Despite the need for more effective drug treatments to address muscle atrophy and disease, physiologically accurate in vitro screening models and higher information content preclinical assays that aid in the discovery and development of novel therapies are lacking. To this end, MyoScreen was developed: a robust and versatile high-throughput high-content screening (HT/HCS) platform that integrates a physiologically and pharmacologically relevant micropatterned human primary skeletal muscle model with a panel of pertinent phenotypic and functional assays...
March 1, 2018: SLAS Discovery
Grazia Morandi, Claudia Piona, Daniela Degani, May Chebl El Hachem, Nicoletta Resta, Carmela Richelli, Silvana Lauriola
The second daughter of two healthy non-consanguineous parents, born at 37 weeks, presented with a large 3×2 cm abdominal angiomatous formation on her left flank, associated with left leg hypertrophy, macrodactyly of both feet with syndactyly of the second and third finger of the right food and left polydactyly (figure 1). Her neurological development and cardiopulmonary function were normal; she had no gastrointestinal or skeletal problems. Her weight was 3195 g (75th-90th centile). edpract;archdischild-2017-314021v1/F1F1F1Figure 1Photos of the lower limbs and the left side of the abdomen reveal bilateral hypertrophy of the limbs, more evident in the left leg, macrodactyly of both feet with syndactyly of the second and third finger of the right foot and left polydactyly and a large abdominal angiomatous formation...
February 28, 2018: Archives of Disease in Childhood. Education and Practice Edition
Yajuan Huang, Haishen Wen, Meizhao Zhang, Nan Hu, Yufeng Si, Siping Li, Feng He
Many genes related to muscle growth determine the proliferation of myoblasts, initiate myoblast differentiation and muscle hypertrophy. MyoD is a myogenic determination factor and contributes to myoblast determination, and IGF-I regulates muscle hypertrophy and muscle mass. MyoD interacted with IGF-I in regulating muscle hypertrophy and muscle mass. The aim of our study was to assess DNA methylation and mRNA expression patterns of MyoD and IGF-I during different developmental stages of Japanese flounder, and to examine the relationship between MyoD and IGF-I gene...
February 24, 2018: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
Fanxing Zeng, Hua Zhao, Jingwen Liao
This study was designed to investigate the effects of exogenous androgen and resistance exercise on skeletal muscle hypertrophy and the role of the mammalian target of rapamycin (mTOR) signalling during the process. A total of 24 male Sprague-Dawley rats were randomly assigned to sham operation and dihydrotestosterone (DHT) implantation groups with subgroups subjected to sedentary conditions or resistance exercise (SHAM+SED, SHAM+EX, DHT+SED, and DHT+EX). The experimental procedure lasted for 10 days. The mRNA expression of androgen receptor (AR) and insulin-like growth factor I (IGF-I), the expression of myosin heavy chain (MHC), as well as the phosphorylation statuses of AR, mTOR, p70 ribosomal S6 kinase (p70S6K ), and eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) were determined in the white gastrocnemius muscle...
December 2017: Biology of Sport
Bo Gao, Wei Wang, Han Wu, Cai Chen, Dan Shen, Saisai Wang, Wei Chen, Li Zhang, Shuheng Chan, Chengyi Song
Insulin-like growth factor (IGF-I) is an important growth factor in mammals, but the functions of the local muscle-specific isoform of insulin-like growth factor 1 (mIGF-1) to skeletal muscle development have rarely been reported. To determine the effect of pig mIGF-1 on body development and muscle deposition in vivo and to investigate the molecular mechanisms, the transgenic mouse model was generated which can also provide experimental data for making transgenic pigs with pig endogenous IGF1 gene. We constructed a skeletal muscle-specific expression vector using 5'- and 3'-regulatory regions of porcine skeletal α-actin gene...
February 22, 2018: Biochemical Genetics
Randall F D'Souza, Nina Zeng, James F Markworth, Vandre Casagrande Figueiredo, Llion Arwyn Roberts, Truls Raastad, Jeff S Coombes, Jonathan M Peake, David Cameron-Smith, Cameron J Mitchell
Resistance training (RT) increases muscle fiber size and induces angiogenesis to maintain capillary density. Cold water immersion (CWI), a common post-exercise recovery modality may improve acute recovery, but it attenuates muscle hypertrophy compared with active recovery (ACT). It is unknown if CWI following RT alters muscle fiber type expression or angiogenesis. Twenty-one men strength trained for 12 weeks, with either 10 min of CWI (n=11) or ACT (n=10) performed following each session. Vastus lateralis biopsies were collected at rest before and after training...
February 21, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Ilona Schirmer, Tippaporn Bualeong, Heidi Budde, Diana Cimiotti, Avinash Appukuttan, Nicole Klein, Philip Steinwascher, Peter Reusch, Andreas Mügge, Rainer Meyer, Yury Ladilov, Kornelia Jaquet
AIMS: In contrast to the membrane bound adenylyl cyclases, the soluble adenylyl cyclase (sAC) is activated by bicarbonate and divalent ions including calcium. sAC is located in the cytosol, nuclei and mitochondria of several tissues including cardiac muscle. However, its role in cardiac pathology is poorly understood. Here we investigate whether sAC is involved in hypertrophic growth using two different model systems. METHODS AND RESULTS: In isolated adult rat cardiomyocytes hypertrophy was induced by 24 h β1-adrenoceptor stimulation using isoprenaline (ISO) and a β2-adrenoceptor antagonist (ICI118,551)...
2018: PloS One
Stella Maris Lins Terena, Kristianne Porta Santos Fernandes, Sandra Kalil Bussadori, Aldo Brugnera Junior, Daniela de Fátima Teixeira da Silva, Eric Moreno Ramos Magalhães, Raquel Agnelli Mesquita Ferrari
BACKGROUND: The photobiomodulation using the low-level laser therapy (LLLT) exerts a positive modulating effect on the synthesis of collagen in skeletal muscles and tendons. However, few studies have addressed this effect during the compensatory overload. OBJECTIVE: Evaluate the effect of infrared laser on the deposition and organization of collagen fibers in muscle and tendon tissue during compensatory overload of the plantar muscle in rats. MATERIALS AND METHODS: Wistar rats were submitted to bilateral ablation of the synergist muscles of the hind paws and divided in groups: Control, Hypertrophy, and Hypertrophy (H)+LLLT (780 nm, 40 mW, 9...
February 21, 2018: Photomedicine and Laser Surgery
Jozo Grgic, Jan Homolak, Pavle Mikulic, Javier Botella, Brad J Schoenfeld
An emerging body of evidence is starting to suggest that the hypertrophy of skeletal muscle fibers might be load specific. In other words, it may be that resistance training with high loads (i.e., ≥60% of 1 repetition maximum [RM]) emphasizes a greater growth of type II muscle fibers, while resistance training with low loads (i.e., <60% of 1RM) might primarily augment hypertrophy of type I muscle fibers. Type I and type II muscle fibers possess certain distinct characteristics, with type II muscle fibers having faster calcium kinetics, faster shortening velocities, and ability to generate more power than type I muscle fibers...
March 2018: Medical Hypotheses
Manuela Cervelli, Alessia Leonetti, Guglielmo Duranti, Stefania Sabatini, Roberta Ceci, Paolo Mariottini
Skeletal muscle comprises approximately 40% of the total body mass. Preserving muscle health and function is essential for the entire body in order to counteract chronic diseases such as type II diabetes, cardiovascular diseases, and cancer. Prolonged physical inactivity, particularly among the elderly, causes muscle atrophy, a pathological state with adverse outcomes such as poor quality of life, physical disability, and high mortality. In murine skeletal muscle C2C12 cells, increased expression of the spermine oxidase (SMOX) enzyme has been found during cell differentiation...
February 14, 2018: Medical Sciences: Open Access Journal
Nobuki Moriya, Mitsunori Miyazaki
Skeletal muscle mass is determined by the net dynamic balance between protein synthesis and degradation. Although the Akt/mechanistic target of rapamycin (mTOR)-dependent pathway plays an important role in promoting protein synthesis and subsequent skeletal muscle hypertrophy, the precise molecular regulation of mTOR activity by the upstream protein kinase Akt is largely unknown. In addition, the activation of satellite cells has been indicated as a key regulator of muscle mass. However, the requirement of satellite cells for load-induced skeletal muscle hypertrophy is still under intense debate...
February 14, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Tomoya Kitakaze, Meiku Oshimo, Yasuyuki Kobayashi, Mizuyuki Ryu, Yasushi A Suzuki, Hiroshi Inui, Naoki Harada, Ryoichi Yamaji
Lactoferrin (Lf) is a multifunctional glycoprotein, which promotes the proliferation of murine C2C12 myoblasts. In the present study, it was investigated how Lf promotes myoblast proliferation and whether Lf promotes myoblast differentiation or induces myotube hypertrophy. Lf promoted the proliferation of myoblasts in a dose‑dependent manner. Myoblast proliferation increased on day 3 when myoblasts were cultured in the presence of Lf for three days and also when myoblasts were cultured in the presence of Lf for the first day and in the absence of Lf for the subsequent two days...
February 13, 2018: Molecular Medicine Reports
Kamil Kobak, Monika Kasztura, Magdalena Dziegala, Jacek Bania, Violetta Kapuśniak, Waldemar Banasiak, Piotr Ponikowski, Ewa A Jankowska
There is clinical evidence that patients with heart failure and concomitant iron deficiency have increased skeletal muscle fatigability and impaired exercise tolerance. It was expected that a skeletal muscle cell line subjected to different degrees of iron availability and/or concomitant hypoxia would demonstrate changes in cell morphology and in the expression of atrophy markers. L6G8C5 rat skeletal myocytes were cultured in normoxia or hypoxia at optimal, reduced or increased iron concentrations. Experiments were performed to evaluate the iron content in cells, cell morphology, and the expression of muscle specific atrophy markers [Atrogin1 and muscle‑specific RING‑finger 1 (MuRF1)], a gene associated with the atrophy/hypertrophy balance [mothers against decapentaplegic homolog 4 (SMAD4)] and a muscle class‑III intermediate filament protein (Desmin) at the mRNA and protein level...
February 12, 2018: International Journal of Molecular Medicine
Yunlong Zou, Yanjun Dong, Qingyong Meng, Yaofeng Zhao, Ning Li
In this study, we upregulated insulin-like growth factor-1 (IGF1) expression specifically in skeletal muscle by engineering an enhancer into its non-coding regions and verified the expected phenotype in a mouse model. To select an appropriate site for introducing a skeletal muscle-specific myosin light chain (MLC) enhancer, three candidate sites that exhibited the least evolutionary conservation were chosen and validated in C2C12 single-cell colonies harbouring the MLC enhancer at each site. IGF1 was dramatically upregulated in only the site 2 single-cell colony series, and it exhibited functional activity leading to the formation of extra myotubes...
February 9, 2018: Scientific Reports
Yoriko Sato, Yusuke Sato, Reiko Suzuki, Kodwo Obeng, Fumiaki Yoshizawa
Mammalian target of rapamycin (mTOR) signaling controls skeletal muscle cell differentiation, growth, and metabolism by sensing the intracellular energy status and nutrients. Recently, leucyl-tRNA synthetase (Lars) was identified as an intracellular sensor of leucine involved in the activation of mTOR signaling. However, there is still no evidence for the activation of mTOR signaling by Lars and its physiological roles in skeletal muscle cells. In this study, we determined the potential roles of Lars for the activation of mTOR signaling, skeletal muscle cell differentiation, hypertrophy, and metabolism using small interfering (si)-RNA knockdown...
February 6, 2018: Experimental Cell Research
Byung-Joon Ko, Yoosoo Chang, Jeong Gyu Kang, Jimin Kim, Hyun-Suk Jung, Kyung Eun Yun, Chan-Won Kim, Hocheol Shin, Seungho Ryu
OBJECTIVES: The association between low skeletal muscle mass and left ventricular diastolic dysfunction (LVDD), a predictor of future heart failure, is largely unexplored. We investigated the relationship between relative muscle mass and LVDD. METHODS: We conducted a cross-sectional study in 67,106 Koreans who underwent an echocardiography as part of a comprehensive health examination between January 2012 and December 2014. Skeletal muscle mass index (SMI) [SMI (%)=total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer...
March 15, 2018: International Journal of Cardiology
Sajedah M Hindi, Shuichi Sato, Guangyan Xiong, Kyle R Bohnert, Andrew A Gibb, Yann S Gallot, Joseph D McMillan, Bradford G Hill, Shizuka Uchida, Ashok Kumar
Skeletal muscle mass is regulated by a complex array of signaling pathways. TGF-β-activated kinase 1 (TAK1) is an important signaling protein, which regulates context-dependent activation of multiple intracellular pathways. However, the role of TAK1 in the regulation of skeletal muscle mass remains unknown. Here, we report that inducible inactivation of TAK1 causes severe muscle wasting, leading to kyphosis, in both young and adult mice.. Inactivation of TAK1 inhibits protein synthesis and induces proteolysis, potentially through upregulating the activity of the ubiquitin-proteasome system and autophagy...
February 8, 2018: JCI Insight
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