scholarly journals Transthyretin Maintains Muscle Homeostasis through the Novel Shuttle Pathway of Thyroid Hormones during Myoblast Differentiation

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1565 ◽  
Author(s):  
Eun Ju Lee ◽  
Sibhghatulla Shaikh ◽  
Dukhwan Choi ◽  
Khurshid Ahmad ◽  
Mohammad Hassan Baig ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Thyroid Hormones ◽  
Muscle Growth ◽  
Vital Role ◽  
Myoblast Differentiation ◽  
Mouse Muscle ◽  
Total Body Mass ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Muscle Homeostasis

Skeletal muscle, the largest part of the total body mass, influences energy and protein metabolism as well as maintaining homeostasis. Herein, we demonstrate that during murine muscle satellite cell and myoblast differentiation, transthyretin (TTR) can exocytose via exosomes and enter cells as TTR- thyroxine (T4) complex, which consecutively induces the intracellular triiodothyronine (T3) level, followed by T3 secretion out of the cell through the exosomes. The decrease in T3 with the TTR level in 26-week-old mouse muscle, compared to that in 16-week-old muscle, suggests an association of TTR with old muscle. Subsequent studies, including microarray analysis, demonstrated that T3-regulated genes, such as FNDC5 (Fibronectin type III domain containing 5, irisin) and RXRγ (Retinoid X receptor gamma), are influenced by TTR knockdown, implying that thyroid hormones and TTR coordinate with each other with respect to muscle growth and development. These results suggest that, in addition to utilizing T4, skeletal muscle also distributes generated T3 to other tissues and has a vital role in sensing the intracellular T4 level. Furthermore, the results of TTR function with T4 in differentiation will be highly useful in the strategic development of novel therapeutics related to muscle homeostasis and regeneration.

Anemic Hypoxemia Reduces Myoblast Proliferation and Muscle Growth in Late Gestation Fetal Sheep

2021 ◽  
Author(s):  
Paul J. Rozance ◽  
Stephanie R Wesolowski ◽  
Sonnet S. Jonker ◽  
Laura D Brown
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Muscle Growth ◽  
Late Gestation ◽  
Whole Body ◽  
Myoblast Differentiation ◽  
Fetal Sheep ◽  
Body Protein ◽  
Skeletal Muscle Growth ◽  
Myoblast Proliferation

Fetal skeletal muscle growth requires myoblast proliferation, differentiation, and fusion into myofibers in addition to protein accretion for fiber hypertrophy. Oxygen is an important regulator of this process. Therefore, we hypothesized that fetal anemic hypoxemia would inhibit skeletal muscle growth. Studies were performed in late gestation fetal sheep that were bled to anemic, and therefore hypoxemic, conditions beginning at ~125 days of gestation (term = 148 days) for 9 ± 0 days (n=19) and compared to control fetuses (n=16). A metabolic study was performed on gestational day ~134 to measure fetal protein kinetic rates. Myoblast proliferation and myofiber area were determined in biceps femoris (BF), tibialis anterior (TA), and flexor digitorum superficialis (FDS) muscles. mRNA expression of muscle regulatory factors was determined in BF. Fetal arterial hematocrit and oxygen content were 28% and 52% lower, respectively, in anemic fetuses. Fetal weight and whole-body protein synthesis, breakdown, and accretion rates were not different between groups. Hindlimb length, however, was 7% shorter in anemic fetuses. TA and FDS muscles weighed less and FDS myofiber area was smaller in anemic fetuses compared to controls. The percentage of Pax7+ myoblasts that expressed Ki67 was lower in BF and tended to be lower in FDS from anemic fetuses indicating reduced myoblast proliferation. There was less MYOD and MYF6 mRNA expression in anemic vs. control BF consistent with reduced myoblast differentiation. These results indicate that fetal anemic hypoxemia reduced muscle growth. We speculate that fetal muscle growth may be improved by strategies that increase oxygen availability.

scholarly journals Interaction of CREB and PGC-1α Induces Fibronectin Type III Domain-Containing Protein 5 Expression in C2C12 Myotubes

2018 ◽  
Vol 50 (4) ◽  
pp. 1574-1584 ◽  
Author(s):  
Xiu-ying Yang ◽  
Margaret C.L. Tse ◽  
Xiang Hu ◽  
Wei-hua Jia ◽  
Guan-hua Du ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Metabolic Effects ◽  
Hek293 Cells ◽  
Metabolic Phenotype ◽  
C2c12 Myotubes ◽  
Type Iii ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Fibronectin Type

Background/Aims: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. Methods: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). Results: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. Conclusion: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.

scholarly journals AMPK inhibits myoblast differentiation through a PGC-1α-dependent mechanism

2009 ◽  
Vol 297 (2) ◽  
pp. E304-E314 ◽  
Author(s):  
David L. Williamson ◽  
David C. Butler ◽  
Stephen E. Alway
Keyword(s):  
Cell Cycle ◽  
Skeletal Muscle ◽  
Protein Expression ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Myoblast Differentiation ◽  
P21 Protein ◽  
Compound C ◽  
Ampk Phosphorylation ◽  
Cell Cycle Transition

Elevated phosphorylation of AMP-activated protein kinase (AMPK) has been shown to inhibit skeletal muscle growth in both culture and animal models, but its role in differentiation of muscle cells is less clear. p21 is known to have an important role in differentiation, but AMPK's role regulating p21 in differentiation in muscle cultures is unknown. Therefore, the purpose of this study was to determine the role of p21 in differentiation of skeletal muscle cells under conditions of elevated AMPK phosphorylation. Treating C2C12 myoblast cultures with 1 mM 5-aminoimidazole-4-carboxamide 1-β-d-ribonucleoside (AICAR) for up to 24 h induced AMPK phosphorylation. Activation of AMPK reduced p21 protein and mRNA expression, which was associated with reduced G1/S cell cycle transition and p21 promoter activity. AICAR-treated myoblasts undergoing differentiation also had reduced p21 protein expression, reduced myotube formation, and myosin accumulation. When myotube cultures were treated with AICAR for 24 h, p21, myosin protein expression, and MyoD were significantly reduced. Myotube atrophy was also apparent compared with control conditions. Addition of compound C, an AMPK inhibitor, attenuated AICAR's negative effects on the myotube cultures. The nuclear expression of p21 protein appeared to be more affected by AICAR-treated myotubes than the cytosolic portion of p21 protein, which was attenuated with compound C treatment. Further analysis revealed that AICAR treatment increased PGC-1α and decreased FOXO3A protein expression, which was reversed with compound C cotreatment. Knockdown of PGC-1α with shRNA corroborated the compound C data, preserving nuclear FOXO3A and p21 protein expression. These data demonstrate that AICAR-induced AMPK phosphorylation inhibits cell cycle transition, reducing differentiation of myoblasts into myotubes, through PGC-1α-FOXO3A-p21.

scholarly journals Irisin Mitigates Oxidative Stress, Chondrocyte Dysfunction and Osteoarthritis Development through Regulating Mitochondrial Integrity and Autophagy

Antioxidants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 810
Author(s):  
Feng-Sheng Wang ◽  
Chung-Wen Kuo ◽  
Jih-Yang Ko ◽  
Yu-Shan Chen ◽  
Shao-Yu Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Dna Damage ◽  
Articular Chondrocytes ◽  
Atp Production ◽  
Knee Oa ◽  
Fibronectin Type Iii ◽  
Cartilage Erosion ◽  
Fibronectin Type Iii Domain ◽  
Muscle Homeostasis

Compromised autophagy and mitochondrial dysfunction downregulate chondrocytic activity, accelerating the development of osteoarthritis (OA). Irisin, a cleaved form of fibronectin type III domain containing 5 (FNDC5), regulates bone turnover and muscle homeostasis. Little is known about the effect of Irisin on chondrocytes and the development of osteoarthritis. This study revealed that human osteoarthritic articular chondrocytes express decreased level of FNDC5 and autophagosome marker LC3-II but upregulated levels of oxidative DNA damage marker 8-hydroxydeoxyguanosine (8-OHdG) and apoptosis. Intra-articular administration of Irisin further alleviated symptoms of medial meniscus destabilization, like cartilage erosion and synovitis, while improved the gait profiles of the injured legs. Irisin treatment upregulated autophagy, 8-OHdG and apoptosis in chondrocytes of the injured cartilage. In vitro, Irisin improved IL-1β-mediated growth inhibition, loss of specific cartilage markers and glycosaminoglycan production by chondrocytes. Irisin also reversed Sirt3 and UCP-1 pathways, thereby improving mitochondrial membrane potential, ATP production, and catalase to attenuated IL-1β-mediated reactive oxygen radical production, mitochondrial fusion, mitophagy, and autophagosome formation. Taken together, FNDC5 loss in chondrocytes is correlated with human knee OA. Irisin repressed inflammation-mediated oxidative stress and extracellular matrix underproduction through retaining mitochondrial biogenesis, dynamics and autophagic program. Our analyses shed new light on the chondroprotective actions of this myokine, and highlight the remedial effects of Irisin on OA development.

Perturbation of PI3K/Akt Signalling affected Autophagy Modulation in Dystrophin-Deficient Myoblasts

2020 ◽  
Author(s):  
Muhammad Dain Yazid ◽  
Hung-Chih Chen
Keyword(s):  
Skeletal Muscle ◽  
Protein Extraction ◽  
Vital Role ◽  
Mdx Mouse ◽  
Autophagic Flux ◽  
Autophagosome Formation ◽  
Myoblast Cell Line ◽  
Protein Localisation ◽  
Myoblast Cell ◽  
Muscle Homeostasis

Abstract The absence of dystrophin has gave a massive impact on myotube development in Muscular Dystrophy pathogenesis. One of the conserved signalling pathways involved in skeletal muscle differentiation is the PI3K/Akt/mTOR pathway that play a vital role in autophagy regulation. To further understand and establish targeted therapy in dystrophin-deficient myoblasts, protein expression profiling has been determined which provides information on perturbed autophagy modulation and activation. In this study, dystrophin-deficient myoblast cell line established from skeletal muscle of dystrophic (mdx) mouse were used as model. The dfd13 (dystrophin-deficient) and C2C12 (non-dystrophic) myoblasts were cultured in low mitogen conditions for 10 days to induce differentiation. The cells were subjected to total protein extraction prior to western blotting assay technique. Protein sub-fractionation has been conducted to determine protein localisation. The live cell analysis of autophagy assay were done using flow cytometer. As results, in our culture system, the dfd13 myoblasts did not achieved terminal differentiation. PTEN expression was profoundly increased in dfd13 myoblasts throughout the differentiation day subsequently imposed perturbation of PI3K/Akt/mTOR regulation. In addition, rictor-mTORC2 was also found inactivated in this event. This occurrence has caused FoxO3 misregulation resulting higher activation of autophagy related genes in dfd13 myoblasts. Autophagosome formation was increased as LC3B-I/II showed accumulation upon differentiation. However, ratio of LC3B lipidation and autophagic flux were shown decreased which exhibited dystrophic features. As a conclusion, perturbation of the PTEN-PI3K/Akt pathway triggers excessive autophagosome formation, and subsequently reduced autophagic flux within dystrophin-deficient myoblasts where this finding are of important to understand DMD patients which fit with the actual scenario. We believe that some manipulation within its regulatory signalling reported in this study could help restore muscle homeostasis and attenuate disease progression.

scholarly journals Constitutive activation of CaMKKα signaling is sufficient but not necessary for mTORC1 activation and growth in mouse skeletal muscle

2014 ◽  
Vol 307 (8) ◽  
pp. E686-E694 ◽  
Author(s):  
Jeremie L. A. Ferey ◽  
Jeffrey J. Brault ◽  
Cheryl A. S. Smith ◽  
Carol A. Witczak
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Knockout Mice ◽  
Muscle Growth ◽  
Mouse Muscle ◽  
Constitutive Activation ◽  
Mouse Skeletal Muscle ◽  
Mtorc1 Signaling ◽  
Mtorc1 Activation ◽  
Constitutively Active

Skeletal muscle loading/overload stimulates the Ca2+-activated, serine/threonine kinase Ca2+/calmodulin-dependent protein kinase kinase-α (CaMKKα); yet to date, no studies have examined whether CaMKKα regulates muscle growth. The purpose of this study was to determine if constitutive activation of CaMKKα signaling could stimulate muscle growth and if so whether CaMKKα is essential for this process. CaMKKα signaling was selectively activated in mouse muscle via expression of a constitutively active form of CaMKKα using in vivo electroporation. After 2 wk, constitutively active CaMKKα expression increased muscle weight (∼10%) and protein content (∼10%), demonstrating that activation of CaMKKα signaling can stimulate muscle growth. To determine if active CaMKKα expression stimulated muscle growth via increased mammalian target of rapamycin complex 1 (mTORC1) signaling and protein synthesis, [3H]phenylalanine incorporation into proteins was assessed with or without the mTORC1 inhibitor rapamycin. Constitutively active CaMKKα increased protein synthesis ∼60%, and this increase was prevented by rapamycin, demonstrating a critical role for mTORC1 in this process. To determine if CaMKKα is essential for growth, muscles from CaMKKα knockout mice were stimulated to hypertrophy via unilateral ablation of synergist muscles (overload). Surprisingly, compared with wild-type mice, muscles from CaMKKα knockout mice exhibited greater growth (∼15%) and phosphorylation of the mTORC1 substrate 70-kDa ribosomal protein S6 kinase (Thr389; ∼50%), demonstrating that CaMKKα is not essential for overload-induced mTORC1 activation or muscle growth. Collectively, these results demonstrate that activation of CaMKKα signaling is sufficient but not necessary for activation of mTORC1 signaling and growth in mouse skeletal muscle.

scholarly journals Perturbation of PI3K/Akt Signaling Affected Autophagy Modulation in Dystrophin-deficient Myoblasts

2020 ◽  
Author(s):  
Muhammad Dain Yazid ◽  
Hung-Chih Chen
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Protein Extraction ◽  
Protein Localization ◽  
Vital Role ◽  
Autophagic Flux ◽  
Autophagosome Formation ◽  
Myoblast Cell Line ◽  
Myoblast Cell ◽  
Muscle Homeostasis

Abstract Background: The absence of dystrophin has gave a massive impact on myotube development in Muscular Dystrophy pathogenesis. One of the conserved signaling pathways involved in skeletal muscle differentiation is the PI3K/Akt/mTOR pathway that plays a vital role in autophagy regulation. To further understand and establish targeted therapy in dystrophin-deficient myoblasts, protein expression profiling has been determined which provides information on perturbed autophagy modulation and activation. Methods: In this study, a dystrophin-deficient myoblast cell line established from the skeletal muscle of a dystrophic (mdx) mouse was used as a model. The dfd13 (dystrophin-deficient) and C2C12 (non-dystrophic) myoblasts were cultured in low mitogen conditions for 10 days to induce differentiation. The cells were subjected to total protein extraction prior to Western blotting assay technique. Protein sub-fractionation has been conducted to determine protein localization. The live-cell analysis of autophagy assay was done using a flow cytometer. Results: In our culture system, the dfd13 myoblasts did not achieve terminal differentiation. PTEN expression was profoundly increased in dfd13 myoblasts throughout the differentiation day subsequently indicates perturbation of PI3K/Akt/mTOR regulation. In addition, rictor-mTORC2 was also found inactivated in this event. This occurrence has caused FoxO3 misregulation leads to higher activation of autophagy-related genes in dfd13 myoblasts. Autophagosome formation was increased as LC3B-I/II showed accumulation upon differentiation. However, the ratio of LC3B lipidation and autophagic flux were shown decreased which exhibited dystrophic features. Conclusion: perturbation of the PTEN-PI3K/Akt pathway triggers excessive autophagosome formation and subsequently reduced autophagic flux within dystrophin-deficient myoblasts where these findings are of importance to understand Duchenne Muscular Dystrophy (DMD) patients. We believe that some manipulation within its regulatory signaling reported in this study could help restore muscle homeostasis and attenuate disease progression.

scholarly journals Urotensin II Induces Mice Skeletal Muscle Atrophy Associated with Enhanced Autophagy and Inhibited Irisin Precursor (Fibronectin Type III Domain Containing 5) Expression in Chronic Renal Failure

2019 ◽  
Vol 44 (4) ◽  
pp. 479-495 ◽  
Author(s):  
Ya-Jing Pan ◽  
Si-Jia Zhou ◽  
Jin Feng ◽  
Qiong Bai ◽  
La-Ta A ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Renal Failure ◽  
Chronic Renal Failure ◽  
Muscle Atrophy ◽  
Skeletal Muscle Atrophy ◽  
Urotensin Ii ◽  
Muscle Weight ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Fibronectin Type

Background/Aims: Skeletal muscle atrophy is one of the main manifestations of protein energy wasting. We hypothesized that urotensin II (UII) can lead to skeletal muscle atrophy through upregulating autophagy and affecting Irisin precursor fibronectin type III domain containing 5 (FNDC5) expressions. Methods: Three animal models (the sham operation, wild-type C57BL/6 mice with 5/6 nephrectomy, UII receptor (UT) gene knockout (UTKO) mice with 5/6 nephrectomy) were designed. Skeletal muscle weight, cross-sectional area (CSA) along with UII, FNDC5, LC3, and p62 expression were investigated. C2C12 cells were differentiated for up to 4 days into myotubes. These cells were then exposed to different UII concentrations (10–5 to 10–7 M) for 6–12 h and analyzed for the expressions of autophagic markers. These cells were also exposed to the same predetermined UII concentrations for 48–72 h and analyzed for the FNDC5 expression. Myotube diameter was measured. Results: Upregulation of UII expression in skeletal muscle tissue was accompanied by reduced muscle weight and skeletal muscle CSA in the 2 posterior limbs, upregulated autophagy markers expression, and downregulated FNDC5 expression in 5/6 nephrectomy mice. The decrease of skeletal muscle weight, skeletal muscle CSA, downregulation of FNDC5 expression, and the upregulation of autophagy markers were inhibited in UTKO with 5/6 nephrectomy mice. Our in vitrostudy showed that UII could directly decrease myotube diameter, induce autophagy markers upregulation, and inhibit expression of FNDC5. When UII receptor gene was interfered by UT-specific siRNA, UII induced autophagy markers upregulation and FNDC5 downregulation were inhibited. Conclusion: We are the first to verify UII induces mice skeletal muscle atrophy associated with enhanced skeletal muscle autophagy and inhibited FNDC5 expression in chronic renal failure.

scholarly journals Genome-Wide Identification, Characterization and Expression Profiling of myosin Family Genes in Sebastes schlegelii

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 808
Author(s):  
Chaofan Jin ◽  
Mengya Wang ◽  
Weihao Song ◽  
Xiangfu Kong ◽  
Fengyan Zhang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
Muscle Growth ◽  
Myoblast Differentiation ◽  
Growth Stages ◽  
Marine Teleost ◽  
Black Rockfish ◽  
Skeletal Muscle Growth ◽  
Sebastes Schlegelii

Myosins are important eukaryotic motor proteins that bind actin and utilize the energy of ATP hydrolysis to perform a broad range of functions such as muscle contraction, cell migration, cytokinesis, and intracellular trafficking. However, the characterization and function of myosin is poorly studied in teleost fish. In this study, we identified 60 myosin family genes in a marine teleost, black rockfish (Sebastes schlegelii), and further characterized their expression patterns. myosin showed divergent expression patterns in adult tissues, indicating they are involved in different types and compositions of muscle fibers. Among 12 subfamilies, S. schlegelii myo2 subfamily was significantly expanded, which was driven by tandem duplication events. The up-regulation of five representative genes of myo2 in the skeletal muscle during fast-growth stages of juvenile and adult S. schlegelii revealed their active role in skeletal muscle fiber synthesis. Moreover, the expression regulation of myosin during the process of myoblast differentiation in vitro suggested that they contribute to skeletal muscle growth by involvement of both myoblast proliferation and differentiation. Taken together, our work characterized myosin genes systemically and demonstrated their diverse functions in a marine teleost species. This lays foundation for the further studies of muscle growth regulation and molecular mechanisms of indeterminate skeletal muscle growth of large teleost fishes.

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