scholarly journals The aromatic amino acid tryptophan stimulates skeletal muscle IGF1/p70s6k/mTor signaling in vivo and the expression of myogenic genes in vitro

Nutrition ◽  
2015 ◽  
Vol 31 (7-8) ◽  
pp. 1018-1024 ◽  
Author(s):  
Amy Dukes ◽  
Colleen Davis ◽  
Mona El Refaey ◽  
Sunil Upadhyay ◽  
Sarah Mork ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Mtor Signaling ◽  
Amino Acid Tryptophan

“In vivo” amplification of biological activity of tetragastrin by amino acid hydroxamates

1984 ◽  
Vol 4 (12) ◽  
pp. 1009-1015 ◽  
Author(s):  
J. P. Bali ◽  
H. Mattras ◽  
A. Previero ◽  
M. A. Coletti-Previero
Keyword(s):  
Biological Activity ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Aminopeptidase Activity ◽  
Proteolytic Degradation ◽  
Short Peptides ◽  
Rat Blood ◽  
Active Peptides

Rat blood was shown to contain an aminopeptidase which rapidly hydrolyses short peptides containing an aromatic amino acid as N-terminal residue. Using tetragastrin (Trp-Met-Asp-PheNH 2) as substrate, we showed that some amino acid hydroxamates inhibit rat aminopeptidase activity ‘in vitro’ in the following order: HTrpNHOH > HPheNHOH ≫ HAIaNHOH. The same hydroxamates markedly enhanced the biological activity of tetragastrin ‘in vivo’. The amplification of the secretory effect, correlated with the amount of the hydroxamate used, strongly suggests that these compounds can stabilize a number of active peptides in vivo by inhibiting their proteolytic degradation.

The effect of caffeine on skeletal muscle anabolic signaling and hypertrophy

2017 ◽  
Vol 42 (6) ◽  
pp. 621-629 ◽  
Author(s):  
Timothy M. Moore ◽  
Xavier M. Mortensen ◽  
Conrad K. Ashby ◽  
Alexander M. Harris ◽  
Karson J. Kump ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Growth ◽  
Mtor Signaling ◽  
Signaling Proteins ◽  
Signaling Protein ◽  
Before And After ◽  
Amp Activated Protein Kinase

Caffeine is a widely consumed stimulant with the potential to enhance physical performance through multiple mechanisms. However, recent in vitro findings have suggested that caffeine may block skeletal muscle anabolic signaling through AMP-activated protein kinase (AMPK)-mediated inhibition of mechanistic target of rapamycin (mTOR) signaling pathway. This could negatively affect protein synthesis and the capacity for muscle growth. The primary purpose of this study was to assess the effect of caffeine on in vivo AMPK and mTOR pathway signaling, protein synthesis, and muscle growth. In cultured C2C12 muscle cells, physiological levels of caffeine failed to impact mTOR activation or myoblast proliferation or differentiation. We found that caffeine administration to mice did not significantly enhance the phosphorylation of AMPK or inhibit signaling proteins downstream of mTOR (p70S6k, S6, or 4EBP1) or protein synthesis after a bout of electrically stimulated contractions. Skeletal muscle-specific knockout of LKB1, the primary AMPK activator in skeletal muscle, on the other hand, eliminated AMPK activation by contractions and enhanced S6k, S6, and 4EBP1 activation before and after contractions. In rats, the addition of caffeine did not affect plantaris hypertrophy induced by the tenotomy of the gastrocnemius and soleus muscles. In conclusion, caffeine administration does not impair skeletal muscle load-induced mTOR signaling, protein synthesis, or muscle hypertrophy.

scholarly journals Reassessment of the Role of Aromatic Amino Acid Hydroxylases and the Effect of Infection by Toxoplasma gondii on Host Dopamine

2014 ◽  
Vol 83 (3) ◽  
pp. 1039-1047 ◽  
Author(s):  
Zi T. Wang ◽  
Steve Harmon ◽  
Karen L. O'Malley ◽  
L. David Sibley
Keyword(s):  
Amino Acid ◽  
Toxoplasma Gondii ◽  
Aromatic Amino Acid ◽  
Content Type ◽  
Aromatic Amino Acid Hydroxylase ◽  
Aromatic Amino Acid Hydroxylases ◽  
Host Brain

Toxoplasma gondiiinfection has been described previously to cause infected mice to lose their fear of cat urine. This behavioral manipulation has been proposed to involve alterations of host dopamine pathways due to parasite-encoded aromatic amino acid hydroxylases. Here, we report successful knockout and complementation of the aromatic amino acid hydroxylaseAAH2gene, with no observable phenotype in parasite growth or differentiationin vitroandin vivo. Additionally, expression levels of the two aromatic amino acid hydroxylases were negligible both in tachyzoites and in bradyzoites. Finally, we were unable to confirm previously described effects of parasite infection on host dopamine eitherin vitroorin vivo, even whenAAH2was overexpressed using theBAG1promoter. Together, these data indicate that AAH enzymes in the parasite do not cause global or regional alterations of dopamine in the host brain, although they may affect this pathway locally. Additionally, our findings suggest alternative roles for theAHHenzymes inT. gondii, sinceAAH1is essential for growth in nondopaminergic cells.

scholarly journals SWELL1-LRRC8 complex regulates skeletal muscle cell size, intracellular signalling, adiposity and glucose metabolism

2020 ◽  
Author(s):  
Ashutosh Kumar ◽  
Litao Xie ◽  
Chau My Ta ◽  
Antentor J. Hinton ◽  
Susheel K. Gunasekar ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ex Vivo ◽  
Anion Channel ◽  
Muscle Differentiation ◽  
Mtor Signaling ◽  
Skeletal Muscle Differentiation ◽  
Skeletal Myofiber ◽  
Cellular Oxygen

AbstractMaintenance of skeletal muscle is beneficial in obesity and Type 2 diabetes. Mechanical stimulation can regulate skeletal muscle differentiation, growth and metabolism, however the molecular mechanosensor remains unknown. Here, we show that SWELL1 (LRRC8a) functionally encodes a swell-activated anion channel that regulates PI3K-AKT, ERK1/2, mTOR signaling, muscle differentiation, myoblast fusion, cellular oxygen consumption, and glycolysis in skeletal muscle cells. SWELL1 over-expression in SWELL1 KO myotubes boosts PI3K-AKT-mTOR signaling to supra-normal levels and fully rescues myotube formation. Skeletal muscle targeted SWELL1 KO mice have smaller myofibers, generate less force ex vivo, and exhibit reduced exercise endurance, associated with increased adiposity under basal conditions, and glucose intolerance and insulin resistance when raised on a high-fat diet, compared to WT mice. These results reveal that the SWELL1-LRRC8 complex regulates insulin-PI3K-AKT-mTOR signalling in skeletal muscle to influence skeletal muscle differentiation in vitro and skeletal myofiber size, muscle function, adiposity and systemic metabolism in vivo.

scholarly journals SWELL1 regulates skeletal muscle cell size, intracellular signaling, adiposity and glucose metabolism

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ashutosh Kumar ◽  
Litao Xie ◽  
Chau My Ta ◽  
Antentor O Hinton ◽  
Susheel K Gunasekar ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Intracellular Signaling ◽  
Ex Vivo ◽  
Anion Channel ◽  
Muscle Differentiation ◽  
Mtor Signaling ◽  
Skeletal Muscle Differentiation ◽  
Skeletal Myofiber

Maintenance of skeletal muscle is beneficial in obesity and Type 2 diabetes. Mechanical stimulation can regulate skeletal muscle differentiation, growth and metabolism; however, the molecular mechanosensor remains unknown. Here, we show that SWELL1 (Lrrc8a) functionally encodes a swell-activated anion channel that regulates PI3K-AKT, ERK1/2, mTOR signaling, muscle differentiation, myoblast fusion, cellular oxygen consumption, and glycolysis in skeletal muscle cells. LRRC8A over-expression in Lrrc8a KO myotubes boosts PI3K-AKT-mTOR signaling to supra-normal levels and fully rescues myotube formation. Skeletal muscle-targeted Lrrc8a KO mice have smaller myofibers, generate less force ex vivo, and exhibit reduced exercise endurance, associated with increased adiposity under basal conditions, and glucose intolerance and insulin resistance when raised on a high-fat diet, compared to wild-type (WT) mice. These results reveal that the LRRC8 complex regulates insulin-PI3K-AKT-mTOR signaling in skeletal muscle to influence skeletal muscle differentiation in vitro and skeletal myofiber size, muscle function, adiposity and systemic metabolism in vivo.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

Synthesis of Fragments of the Vasoactive Intestinal Peptide (VIP) and Analysis of Their Residual Biological Activities

1995 ◽  
Vol 60 (7) ◽  
pp. 1229-1235 ◽  
Author(s):  
Ivana Zoulíková ◽  
Ivan Svoboda ◽  
Jiří Velek ◽  
Václav Kašička ◽  
Jiřina Slaninová ◽  
...  
Keyword(s):  
Amino Acid ◽  
Biological Activities ◽  
Residual Activity ◽  
Detailed Examination ◽  
Amino Acid Residues ◽  
Linear Peptide ◽  
Zone Electrophoresis ◽  
Capillary Zone

The vasoactive intestinal (poly)peptide (VIP) is a linear peptide containing 28 amino acid residues, whose primary structure indicates a low metabolic stability. The following VIP fragments, as potential metabolites, and their analogues were prepared by synthesis on a solid: [His(Dnp)1]VIP(1-10), VIP(11-14), [D-Arg12]VIP(11-14), [Lys(Pac)15,21,Arg20]VIP(15-22), and VIP(23-28). After purification, the peptides were characterized by amino acid analysis, mass spectrometry, RP HPLC, and capillary zone electrophoresis. In some tests, detailed examination of the biological activity of the substances in vivo and in vitro gave evidence of a low, residual activity of some fragments, viz. a depressoric activity in vivo for [His(Dnp)1]VIP(1-10) and a stimulating activity for the release of α-amylase in vitro and in vivo for [Lys(Pac)15,21,Arg20]VIP(15-22) and VIP(23-28).

scholarly journals Studies on Aromatic Amino Acid Uptake by Rat Brain in Vivo

1962 ◽  
Vol 237 (3) ◽  
pp. 803-806
Author(s):  
Gordon Guroff ◽  
Sidney Udenfriend
Keyword(s):  
Amino Acid ◽  
Rat Brain ◽  
Aromatic Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake

scholarly journals Upregulation of Long Noncoding RNA_GAS5 Suppresses Cell Proliferation and Metastasis in Laryngeal Cancer via Regulating PI3K/AKT/mTOR Signaling Pathway

2021 ◽  
Vol 20 ◽  
pp. 153303382199007
Author(s):  
Wenlin Liu ◽  
Jiandong Zhan ◽  
Rong Zhong ◽  
Rui Li ◽  
Xiaoli Sheng ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Signaling Pathway ◽  
Laryngeal Cancer ◽  
Mtor Signaling ◽  
Mtor Signaling Pathway ◽  
Proliferation And Metastasis ◽  
Cancer Tissues ◽  
Lncrna Gas5

Background: Laryngeal cancer is one of the most common malignant tumors among head and neck cancers. Accumulating studies have indicated that long noncoding RNAs (lncRNAs) play an important role in laryngeal cancer occurrence and progression, however, the functional roles and relative regulatory mechanisms of lncRNA growth arrest-specific transcript 5 (GAS5) in laryngeal cancer progression remain unclear. Methods: The expression of lncRNA GAS5 in both laryngeal cancer tissues and cell lines was evaluated using quantitative reverse transcription-polymerase chain reaction (RT-qPCR) assay. The relationships between lncRNA GAS5 expression and clinical parameters were also analyzed. To determine the biological function of lncRNA GAS5, a lncRNA GAS5-specific plasmid was first transfected into laryngeal cancer cells using lentiviral technology. Cell counting kit-8 assay, flow cytometry, and Transwell assays were used to detect in vitro cell proliferation, apoptosis, cycle distribution, and metastasis abilities, respectively. Furthermore, in vivo cell growth experiments were also performed using nude mice. Additionally, western blotting was performed to identify the underlying regulatory mechanism. Results: In the current study, lncRNA GAS5 was downregulated in laryngeal cancer tissues and its low expression was closely associated with poor tumor differentiation, advanced TNM stage, lymph node metastasis, and shorter overall survival time. In addition, lncRNA GAS5 upregulation significantly inhibited laryngeal cancer cell proliferation both in vitro and in vivo. Moreover, in response to lncRNA GAS5 overexpression, more laryngeal cancer cells were arrested at the G2/M stage, accompanied by increased cell apoptosis rates and suppressed migration and invasion capacities. Mechanistically, our data showed that the overexpression of lncRNA GAS5 significantly regulated the PI3K/AKT/mTOR signaling pathway. Conclusion: LncRNA GAS5 might act as a suppressor gene during laryngeal cancer development, as it suppressed cell proliferation and metastasis by regulating the PI3K/AKT/mTOR signaling pathway; thus, lncRNA GAS5 is a promising therapeutic biomarker for the treatment of laryngeal cancer.

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