scholarly journals Drosophila Activin signaling promotes muscle growth through InR/dTORC1 dependent and independent processes

Development ◽  
2020 ◽  
pp. dev.190868
Author(s):  
Myung-Jun Kim ◽  
Michael B. O'Connor
Keyword(s):  
Muscle Growth ◽  
Negative Regulator ◽  
Muscle Size ◽  
Wild Type ◽  
Larval Body ◽  
Activin Signaling ◽  
Sarcomeric Protein ◽  
Muscle Geometry ◽  
Tgfβ Superfamily ◽  
Vertebrate Skeletal Muscle

The Myostatin/Activin branch of the TGFβ superfamily acts as a negative regulator of vertebrate skeletal muscle size, in part, through downregulation of insulin/IGF-1 signaling. Surprisingly, recent studies in Drosophila indicate that motoneuron derived Activin signaling acts as a positive regulator of muscle size. Here we demonstrate that Drosophila Activin signaling promotes growth of the muscle cells along all three axes; width, thickness and length. Activin signaling positively regulates the InR/dTORC1 pathway and the level of Mhc, an essential sarcomeric protein, via increased Pdk1 and Akt1 expression. Enhancing InR/dTORC1 signaling in the muscle of Activin pathway mutants restores Mhc levels close to wild-type, but only increases muscle width. In contrast, hyperactivation of the Activin pathway in muscles increases overall larval body and muscle fiber length even when Mhc levels were lowered by suppression of dTORC1. Together, these results indicate that the Drosophila Activin pathway regulates larval muscle geometry and body size via promoting InR/dTORC1-dependent Mhc production and the differential assembly of sarcomeric components into either pre-existing or new sarcomeric units depending on the balance of InR/dTORC1 and Activin signals.

scholarly journals Drosophila Activin signaling promotes muscle growth through InR/dTORC1 dependent and independent processes

2020 ◽  
Author(s):  
Myung-Jun Kim ◽  
Michael B. O’Connor
Keyword(s):  
Muscle Growth ◽  
Muscle Cells ◽  
Negative Regulator ◽  
Muscle Size ◽  
Mammalian Skeletal Muscle ◽  
Wild Type ◽  
Activin Signaling ◽  
Sarcomeric Protein ◽  
Muscle Geometry ◽  
Tgfβ Superfamily

SummaryThe Myostatin/Activin branch of the TGFβ superfamily acts as a negative regulator of mammalian skeletal muscle size, in part, through downregulation of insulin/IGF-1 signaling. Surprisingly, recent studies in Drosophila indicate that Activin signaling acts as a positive regulator of muscle size. Here we demonstrate that Drosophila Activin signaling promotes growth of the muscle cells along all three axes; width, length and thickness. In addition, Activin signaling positively regulates the InR/dTORC1 pathway and the level of MHC, an essential sarcomeric protein, via promoting the transcription of Pdk1 and Akt1. Enhancing InR/dTORC1 signaling in the muscle of Activin pathway mutants restores MHC levels close to wild-type, but only increased the width of muscle cells. In contrast, hyperactivation of the Activin pathway increases the length of muscle cells even when MHC levels were lowered by suppression of dTORC1. Together, these results indicate that Drosophila Activin pathway regulates larval muscle geometry via promoting InR/dTORC1-dependent MHC production and the differential assembly of sarcomeric components into either pre-existing (width) or new (length) sarcomeric units depending on the balance of InR/dTORC1 and Activin signals.

Pharmacological Inhibition of Myostatin and Changes in Lean Body Mass and Lower Extremity Muscle Size in Patients Receiving Androgen Deprivation Therapy for Prostate Cancer

2014 ◽  
Vol 99 (10) ◽  
pp. E1967-E1975 ◽  
Author(s):  
Desmond Padhi ◽  
Celestia S. Higano ◽  
Neal D. Shore ◽  
Paul Sieber ◽  
Erik Rasmussen ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lean Body Mass ◽  
Body Mass ◽  
Phase 1 ◽  
Muscle Growth ◽  
Androgen Deprivation ◽  
Negative Regulator ◽  
Muscle Size ◽  
Muscle Loss ◽  
Lower Extremity Muscle

Abstract Context: Myostatin is a negative regulator of muscle growth. Androgen deprivation (ADT) is associated with muscle loss and increased body fat, and currently available therapies have limited efficacy to treat this complication. The antimyostatin peptibody (AMG 745/Mu-S) markedly attenuated muscle loss and decreased fat accumulation in orchiectomized mice. Objective: The objective of the study was to evaluate the safety, pharmacokinetics, and muscle efficacy of AMG 745 in men undergoing ADT for nonmetastatic prostate cancer. Methods: This was a randomized, blinded, placebo-controlled, multiple-dose, phase 1 study of AMG 745 given for 28 days. The end point of percentage change from baseline in lean body mass (LBM) as assessed by dual x-ray absorptiometry was prespecified. Results: Rates of adverse events (AMG 745 vs placebo) were the following: diarrhea (13% vs 9%), fatigue (13% vs 4%), contusion (10% vs 0%), and injection site bruising (6% vs 4%). Exposure increased linearly from 0.3 mg/kg to 3 mg/kg. AMG 745 significantly increased LBM in the 3 mg/kg vs the placebo groups on day 29 by 2.2% (±0.8% SE, P = 0.008); in exploratory fat mass analysis, a decrease of −2.5% (±1.0% SE, P = 0.021) was observed. Pharmacodynamic changes in muscle and fat were maintained at follow-up, 1 month after day 29. Conclusion: Four weekly sc doses of AMG 745 were well tolerated and were associated with increased LBM and decreased fat in the men receiving ADT for nonmetastatic prostate cancer. Results support further investigation of AMG 745 in clinical settings with muscle loss and atrophy.

Abstract 355: Increasing Muscle Mass Improves Vascular Function In Obese Mice

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Shuiqing Qiu ◽  
James Mintz ◽  
Christina Salet ◽  
Nitirut Nernpermpisooth ◽  
David Fulton ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Vascular Function ◽  
Muscle Growth ◽  
Gluteus Maximus ◽  
Mesenteric Arteries ◽  
Negative Regulator ◽  
Muscle Size ◽  
Obese Mice ◽  
Fiber Size ◽  
Oxide Synthase

Exercise improves endothelial function in obese patients. Salutatory effects of exercise include increases in muscle size and quality, reduction in fat mass and alterations of the plasma milieu. The relationships between these changes and improvements in vascular function are poorly defined. Hypothesis Increasing muscle mass by deletion of muscle growth negative regulator myostatin, improves vascular function in mesenteric arteries from obese db/db mice. Myostatin deletion increased muscle mass in both lean (gastrocnemius 57.93%, gluteus maximus 60.95%, triceps 57.64%) and obese mice (gastrocnemius 79.64%, gluteus maximus 112.32%, triceps 103.61%). Myostatin deletion increased muscle fiber size in lean and obese mice (p< 0.05) but had no significant effects on adipocyte size in obese mice. Fasting glucose, HbA1c and glucose tolerance were improved in obese myostatin null mice. Obese mice demonstrated superoxide-mediated impairment of ACh-induced vasodilation compared to lean mice. Deletion of myostatin in obese mice improved ACh-induced vasodilation in mesenteric arteries without effects in lean mice. This improvement was blunted by L-NAME. PGI 2 and EDHF mediated vasodilation were preserved in obese mice, and unaffected by myostatin deletion. Treatment with sepiapterin (a precursor of the nitric oxide synthase cofactor tetrahydrobiopoterin) restored impairment of vasodilation in obese mice, and this improvement was blocked by L-NAME. Taken together, these data suggested that increasing muscle mass by deletion of myostatin improved NO not PGI 2 or EDHF mediated vasodilation in obese mice.

scholarly journals Marker-assisted introgression of the Compact mutant myostatin allele MstnCmpt-dl1Abc into a mouse line with extreme growth effects on body composition and muscularity

2004 ◽  
Vol 84 (3) ◽  
pp. 161-173 ◽  
Author(s):  
LUTZ BÜNGER ◽  
GERHARD OTT ◽  
LÁSZLÓ VARGA ◽  
WERNER SCHLOTE ◽  
CHARLOTTE REHFELDT ◽  
...  
Keyword(s):  
Body Fat ◽  
Muscle Growth ◽  
Segregation Ratio ◽  
Quadriceps Muscle ◽  
Negative Regulator ◽  
Wild Type ◽  
Fat Depots ◽  
Total Body Fat ◽  
Gene Expression Studies ◽  
Total Body

Myostatin is a negative regulator of muscle growth and mutations in its gene lead to muscular hypertrophy and reduced fat. In cattle, this is seen in ‘double muscled’ breeds. We have used marker-assisted introgression to introduce a murine myostatin mutation, MstnCmpt-dl1Abc [Compact (C)], into an inbred line of mice (DUHi) that had been selected on body weight and had exceptional growth. Compared with homozygous wild-type mice, homozygous (C/C) mice of this line were ~4–5% lighter, had ~7–8% shorter tails, substantially increased muscle weights (e.g. quadriceps muscle in males was 59% heavier) and an increased ‘dressing percentage’ (~49% vs 39%), an indicator of overall muscularity. The weights of several organs (e.g. liver, kidney, heart and digestive tract) were significantly reduced, by 12–20%. Myostatin deficiency also resulted in drastic reductions of total body fat and of various fat depots, total body fat proportion falling from ~17·5% in wild-type animals of both sexes to 9·5% and 11·6% in homozygous (C/C) females and males, respectively. Males with a deficiency in myostatin had higher gains in muscle traits than females. Additionally, there was a strong distortion of the segregation ratio on the DUHi background. Of 838 genotyped pups from inter se matings 29%, 63% and 8% were homozygous wild type (+/+), heterozygous (C/+) and homozygous (C/C), respectively, showing that MstnCmpt-dl1Abc has lower fitness on this background. This line, when congenic, will be a useful resource in gene expression studies and for finding modifying genes.

scholarly journals Myostatin propeptide mutation of the hypermuscular Compact mice decreases the formation of myostatin and improves insulin sensitivity

2017 ◽  
Vol 312 (3) ◽  
pp. E150-E160 ◽  
Author(s):  
Tamas Kocsis ◽  
Gyorgy Trencsenyi ◽  
Kitti Szabo ◽  
Julia Aliz Baan ◽  
Geza Muller ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Genetic Background ◽  
Negative Regulator ◽  
Metabolic Effects ◽  
Muscle Size ◽  
Whole Body ◽  
Rab Gtpase ◽  
Wild Type ◽  
Absolute Size

The TGFβ family member myostatin (growth/differentiation factor-8) is a negative regulator of skeletal muscle growth. The hypermuscular Compact mice carry the 12-bp Mstn(Cmpt-dl1Abc) deletion in the sequence encoding the propeptide region of the precursor promyostatin, and additional modifier genes of the Compact genetic background contribute to determine the full expression of the phenotype. In this study, by using mice strains carrying mutant or wild-type myostatin alleles with the Compact genetic background and nonmutant myostatin with the wild-type background, we studied separately the effect of the Mstn(Cmpt-dl1Abc) mutation or the Compact genetic background on morphology, metabolism, and signaling. We show that both the Compact myostatin mutation and Compact genetic background account for determination of skeletal muscle size. Despite the increased musculature of Compacts, the absolute size of heart and kidney is not influenced by myostatin mutation; however, the Compact genetic background increases them. Both Compact myostatin and genetic background exhibit systemic metabolic effects. The Compact mutation decreases adiposity and improves whole body glucose uptake, insulin sensitivity, and 18FDG uptake of skeletal muscle and white adipose tissue, whereas the Compact genetic background has the opposite effect. Importantly, the mutation does not prevent the formation of mature myostatin; however, a decrease in myostatin level was observed, leading to altered activation of Smad2, Smad1/5/8, and Akt, and an increased level of p-AS160, a Rab-GTPase-activating protein responsible for GLUT4 translocation. Based on our analysis, the Compact genetic background strengthens the effect of myostatin mutation on muscle mass, but those can compensate for each other when systemic metabolic effects are compared.

Transcriptomic Analysis of MSTN Knockout in the Early Differentiation of Chicken Fetal Myoblasts

Genes ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 58
Author(s):  
Ke Xu ◽  
Hao Zhou ◽  
Chengxiao Han ◽  
Zhong Xu ◽  
Jinmei Ding ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Molecular Mechanism ◽  
Growth And Development ◽  
Biological Effects ◽  
Muscle Growth ◽  
Negative Regulator ◽  
Myoblast Differentiation ◽  
Fatty Acid Binding ◽  
Knock Out ◽  
Early Differentiation

In mammals, Myostatin (MSTN) is a known negative regulator of muscle growth and development, but its role in birds is poorly understood. To investigate the molecular mechanism of MSTN on muscle growth and development in chickens, we knocked out MSTN in chicken fetal myoblasts (CFMs) and sequenced the mRNA transcriptomes. The amplicon sequencing results show that the editing efficiency of the cells was 76%. The transcriptomic results showed that 296 differentially expressed genes were generated after down-regulation of MSTN, including angiotensin I converting enzyme (ACE), extracellular fatty acid-binding protein (EXFABP) and troponin T1, slow skeletal type (TNNT1). These genes are closely associated with myoblast differentiation, muscle growth and energy metabolism. Subsequent enrichment analysis showed that DEGs of CFMs were related to MAPK, P13K/AKT, and STAT3 signaling pathways. The MAPK and P13K/AKT signaling pathways are two of the three known signaling pathways involved in the biological effects of MSTN in mammals, and the STAT3 pathway is also significantly enriched in MSTN knock out chicken leg muscles. The results of this study will help to understand the possible molecular mechanism of MSTN regulating the early differentiation of CFMs and lay a foundation for further research on the molecular mechanism of MSTN involvement in muscle growth and development.

RNF43 mutations to predict survival from treatment with immune checkpoint inhibitors and are associated with a high tumor mutation burden in bladder cancer.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e16528-e16528
Author(s):  
Liping Li ◽  
Mengmei Yang ◽  
Mengli Huang
Keyword(s):  
Bladder Cancer ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitors ◽  
Checkpoint Inhibitors ◽  
Negative Regulator ◽  
Wilcoxon Test ◽  
Wild Type ◽  
Tumor Mutation Burden ◽  
Mutation Burden ◽  
The Impact

e16528 Background: Immune checkpoint inhibitors (ICIs) targeting PD-1/L1 have been approved as first-line treatment for cisplatin-ineligible patients and as second-line therapy for patients with metastatic urothelial carcinoma of the bladder. Biomarkers can help select patients who are more likely to response to ICIs. RNF43 is an E3 ubiquitin ligase that acts as a negative regulator of Wnt/β-catenin signaling pathway. In colorectal cancer (CRC) patients treated with immune checkpoint inhibitors (ICIs), RNF43 mutations predicted longer overall survival (OS). The impact of RNF43 mutations on the efficiency of ICIs in bladder cancer(BLC) remains to be explored. Methods: We downloaded the mutation and clinical data of 211 BLC patients treated with ICIs from the immunotherapeutic cohort published by Samstein et al. (2019). OS analyses were conducted using Kaplan-Meier curves and log-rank tests. Wilcoxon test was used for the comparison of TMB. We also downloaded a TCGA cohort for prognostic analysis. The correlations between RNF43 and immune infiltrates were analyzed in the TIMER2.0 database. Statistical significance was set at p = 0.05. Results: RNF43 mutations were identified in 4.3%(9/211) and 3%(13/438) BLC patients in the immunotherapeutic and TCGA cohort, respectively. In the immunotherapeutic cohort, patients with RNF43 mutations had significantly longer OS (25 months vs 8 months; p = 0.015) and higher tumor mutation burden(TMB, 42.3 vs 7.9; p = 3.15E-06) than RNF43-wild-type patients. Different from this, no significant difference was found in OS between RNF43-mutant and RNF43-wild-type BLC patients with standard treatment in the TCGA cohort (p = 0.696). These results indicated that RNF43 was not a prognostic factor but a predictive biomarker of survival in BLC treated with ICIs. No difference was observed in subsets of immune cells between RNF43-mutant and the RNF43-wide-type BLC patients, including neutrophils, macrophages, CD8+ T cells, Tregs, B cells and NK cells. Conclusions: RNF43 mutations may be a predictor of survival benefit from ICIs in bladder cancer and correlated with higher TMB. Further studies in other ICI-treated cohorts are needed to confirm these results.

scholarly journals A Systematic Review with Meta-Analysis of the Effect of Resistance Training on Whole-Body Muscle Growth in Healthy Adult Males

2020 ◽  
Vol 17 (4) ◽  
pp. 1285 ◽  
Author(s):  
Pedro J. Benito ◽  
Rocío Cupeiro ◽  
Domingo J. Ramos-Campo ◽  
Pedro E. Alcaraz ◽  
Jacobo Á. Rubio-Arias
Keyword(s):  
Systematic Review ◽  
Resistance Training ◽  
Muscle Mass ◽  
Meta Analysis ◽  
Muscle Growth ◽  
Fat Free Mass ◽  
Muscle Size ◽  
Whole Body ◽  
Cochrane Library ◽  
Significant Variable

We performed a systematic review and meta-analysis to study all published clinical trial interventions, determined the magnitude of whole-body hypertrophy in humans (healthy males) and observed the individual responsibility of each variable in muscle growth after resistance training (RT). Searches were conducted in PubMed, Web of Science and the Cochrane Library from database inception until 10 May 2018 for original articles assessing the effects of RT on muscle size after interventions of more than 2 weeks of duration. Specifically, we obtain the variables fat-free mass (FMM), lean muscle mass (LMM) and skeletal muscle mass (SMM). The effects on outcomes were expressed as mean differences (MD) and a random-effects meta-analysis and meta-regressions determined covariates (age, weight, height, durations in weeks…) to explore the moderate effect related to the participants and characteristics of training. One hundred and eleven studies (158 groups, 1927 participants) reported on the effects of RT for muscle mass. RT significantly increased muscle mass (FFM+LMM+SMM; Δ1.53 kg; 95% CI [1.30, 1.76], p < 0.001; I2 = 0%, p = 1.00). Considering the overall effects of the meta-regression, and taking into account the participants’ characteristics, none of the studied covariates explained any effect on changes in muscle mass. Regarding the training characteristics, the only significant variable that explained the variance of the hypertrophy was the sets per workout, showing a significant negative interaction (MD; estimate: 1.85, 95% CI [1.45, 2.25], p < 0.001; moderator: -0.03 95% CI [−0.05, −0.001] p = 0.04). In conclusion, RT has a significant effect on the improvement of hypertrophy (~1.5 kg). The excessive sets per workout affects negatively the muscle mass gain.

scholarly journals Accumulation of Inorganic Polyphosphate in phoU Mutants of Escherichia coli and Synechocystis sp. Strain PCC6803

2002 ◽  
Vol 68 (8) ◽  
pp. 4107-4110 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Tatsuya Maruo ◽  
Yoko Shirai ◽  
Junichi Kato ◽  
Tsukasa Ikeda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Biological Process ◽  
Negative Regulator ◽  
Wild Type ◽  
Inorganic Polyphosphate ◽  
Insertional Inactivation ◽  
Synechocystis Sp ◽  
Polyp Accumulation

ABSTRACT The biological process for phosphate (Pi) removal is based on the use of bacteria capable of accumulating inorganic polyphosphate (polyP). We obtained Escherichia coli mutants which accumulate a large amount of polyP. The polyP accumulation in these mutants was ascribed to a mutation of the phoU gene that encodes a negative regulator of the Pi regulon. Insertional inactivation of the phoU gene also elevated the intracellular level of polyP in Synechocystis sp. strain PCC6803. The mutant could remove fourfold more Pi from the medium than the wild-type strain removed.

scholarly journals FK506-binding protein FklB is involved in biofilm formation through its peptidyl-prolyl isomerase activity

2020 ◽  
Author(s):  
Chrysoula Zografou ◽  
Maria Dimou ◽  
Panagiotis Katinakis
Keyword(s):  
Biofilm Formation ◽  
Negative Regulator ◽  
Cell Length ◽  
Wild Type ◽  
Prolyl Isomerase ◽  
Ppiase Activity ◽  
Peptidyl Prolyl Isomerase ◽  
Knock Out ◽  
E Coli ◽  
The Mean

AbstractFklB is a member of the FK506-binding proteins (FKBPs), a family that consists of five genes in Escherichia coli. Little is known about the physiological and functional role of FklB in bacterial movement. In the present study, FklB knock-out mutant ΔfklB presented an increased swarming and swimming motility and biofilm formation phenotype, suggesting that FklB is a negative regulator of these cellular processes. Complementation with Peptidyl-prolyl isomerase (PPIase)-deficient fklB gene (Y181A) revealed that the defects in biofilm formation were not restored by Y181A, indicating that PPIase activity of FklB is modulating biofilm formation in E. coli. The mean cell length of ΔfklB swarming cells was significantly smaller as compared to the wild-type BW25113. Furthermore, the mean cell length of swarming and swimming wild-type and ΔfklB cells overexpressing fklB or Y181A was considerably larger, suggesting that PPIase activity of FklB plays a role in cell elongation and/or cell division. A multi-copy suppression assay demonstrated that defects in motility and biofilm phenotype were compensated by overexpressing sets of PPIase-encoding genes. Taken together, our data represent the first report demonstrating the involvement of FklB in cellular functions of E. coli.

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