The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Taek-jeong Nam - One of the best experts on this subject based on the ideXlab platform.
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Protective Effect of Pyropia yezoensis Peptide on Dexamethasone-Induced Myotube Atrophy in C2C12 Myotubes.
Marine drugs, 2019Co-Authors: Min-kyeong Lee, Jeong-wook Choi, Youn Hee Choi, Taek-jeong NamAbstract:Dexamethasone (DEX), a synthetic glucocorticoid, causes skeletal muscle atrophy. This study examined the protective effects of Pyropia yezoensis peptide (PYP15) against DEX-induced myotube atrophy and its association with insulin-like growth factor-I (IGF-I) and the Akt/mammalian target of rapamycin (mTOR)-forkhead box O (FoxO) signaling pathway. To elucidate the molecular mechanisms underlying the effects of PYP15 on DEX-induced myotube atrophy, C2C12 Myotubes were treated for 24 h with 100 μM DEX in the presence or absence of 500 ng/mL PYP15. Cell viability assays revealed no PYP15 toxicity in C2C12 Myotubes. PYP15 activated the insulin-like growth factor-I receptor (IGF-IR) and Akt-mTORC1 signaling pathway in DEX-induced myotube atrophy. In addition, PYP15 markedly downregulated the nuclear translocation of transcription factors FoxO1 and FoxO3a, and inhibited 20S proteasome activity. Furthermore, PYP15 inhibited the autophagy-lysosomal pathway in DEX-stimulated myotube atrophy. Our findings suggest that PYP15 treatment protected against myotube atrophy by regulating IGF-I and the Akt-mTORC1-FoxO signaling pathway in skeletal muscle. Therefore, PYP15 treatment appears to exert protective effects against skeletal muscle atrophy.
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Pyropia yezoensis Protein Prevents Dexamethasone-Induced Myotube Atrophy in C2C12 Myotubes.
Marine drugs, 2018Co-Authors: Min-kyeong Lee, Jeong-wook Choi, Youn Hee Choi, Taek-jeong NamAbstract:Glucocorticoids (GCs), which are endocrine hormones released under stress conditions, can cause skeletal muscle atrophy. This study investigated whether Pyropia yezoensis crude protein (PYCP) inhibits synthetic GCs dexamethasone (DEX)-induced myotube atrophy associated with proteolytic systems. Mouse skeletal muscle C2C12 Myotubes were treated with DEX in the presence or absence of PYCP. DEX exposure (100 μM) for 24 h significantly decreased myotube diameter and myogenin expression, which were all increased by treatment with 20 and 40 μg/mL PYCP. Additionally, PYCP significantly reduced the nuclear expression of the forkhead box transcription factors, FoxO1 and FoxO3a, and ubiquitin-proteasome pathway activation. Further mechanistic research revealed that PYCP inhibited the autophagy-lysosome pathway in DEX-induced C2C12 Myotubes. These findings indicate that PYCP prevents DEX-induced myotube atrophy through the regulation of FoxO transcription factors, followed by the inhibition of the ubiquitin-proteasome and autophagy-lysosome pathways. Therefore, we suggest that inhibiting these two proteolytic processes with FoxO transcription factors is a promising strategy for preventing DEX-related myotube atrophy.
A J Harris - One of the best experts on this subject based on the ideXlab platform.
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Formation of Myotubes in aneural rat muscles.
Developmental biology, 1993Co-Authors: S.j. Wilson, A J HarrisAbstract:Skeletal muscles formed in the absence of innervation are deficient in number of fibers, atrophic, and prone to degeneration. We and others have suggested that primary Myotubes form autonomously, and the major effect of embryonic denervation is to halt the formation of secondary Myotubes by removing the mitotic stimulus for generation of their precursor myoblasts. This hypothesis has recently been put into question by the results of work by Condon et al . (Dev. Biol., 138, 275-295, 1990) and by B. J. Fredette and L. T. Landmesser (Dev. Biol. 143, 19-35, 1991) who propose that lowered secondary myotube numbers are at least in part due to absence of the primary Myotubes which would normally serve as scaffold for their formation. We distinguish between these hypotheses by studying generation and degeneration of primary Myotubes and formation of secondary Myotubes in fetal rat muscles denervated by injection of β-bungarotoxin at different times between Embryonic Days (E) 14 and 17. Denervation at any of these times reduced primary myotube numbers on E18 to about 80% of control. Despite this modest decrease in primary myotube numbers, secondary myotube generation fell to below 3% of normal in extensor digitorum longus (EDL) muscles denervated on E14 or E15 and to below 12% of control in soleus muscles denervated on E14-E16. Secondary Myotubes were associated with degenerating as well as intact primary Myotubes. More secondary Myotubes were generated only if nerves had been present up until E16 for EDL or E17 for soleus. We suggest that these observations of a critical period until E16 (EDL) or E17 (soleus) during which innervation is an absolute prerequisite for secondary myotube formation reflect the presence of a nerve-dependent population of myoblasts which must be activated before secondary myotube formation can commence.
Michael B. Reid - One of the best experts on this subject based on the ideXlab platform.
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doxorubicin acts via mitochondrial ros to stimulate catabolism in c2c12 Myotubes
American Journal of Physiology-cell Physiology, 2012Co-Authors: Laura A A Gilliam, Jennifer S Moylan, Elaine Patterson, Anne S Wilson, Zaheen Rabbani, Jeffrey D. Smith, Michael B. ReidAbstract:Doxorubicin, a commonly prescribed chemotherapeutic agent, causes skeletal muscle wasting in cancer patients undergoing treatment and increases mitochondrial reactive oxygen species (ROS) production. ROS stimulate protein degradation in muscle by activating proteolytic systems that include caspase-3 and the ubiquitin-proteasome pathway. We hypothesized that doxorubicin causes skeletal muscle catabolism through ROS, causing upregulation of E3 ubiquitin ligases and caspase-3. We tested this hypothesis by exposing differentiated C2C12 Myotubes to doxorubicin (0.2 μM). Doxorubicin decreased myotube width 48 h following exposure, along with a 40–50% reduction in myosin and sarcomeric actin. Cytosolic oxidant activity was elevated in Myotubes 2 h following doxorubicin exposure. This increase in oxidants was followed by an increase in the E3 ubiquitin ligase atrogin-1/muscle atrophy F-box (MAFbx) and caspase-3. Treating Myotubes with SS31 (opposes mitochondrial ROS) inhibited expression of ROS-sensitive atrogin-1/MAFbx and protected against doxorubicin-stimulated catabolism. These findings suggest doxorubicin acts via mitochondrial ROS to stimulate myotube atrophy.
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Interleukin-1 stimulates catabolism in C2C12 Myotubes
American journal of physiology. Cell physiology, 2009Co-Authors: Jennifer S Moylan, Jeffrey D. Smith, Melissa A. Chambers, Michael B. ReidAbstract:Interleukin-1 (IL-1) is an inflammatory cytokine that has been linked to muscle catabolism, a process regulated by muscle-specific E3 proteins of the ubiquitin-proteasome pathway. To address cellular mechanism, we tested the hypothesis that IL-1 induces myofibrillar protein loss by acting directly on muscle to increase expression of two critical E3 proteins, atrogin1/muscle atrophy F-box (MAFbx) and muscle RING-finger 1 (MuRF1). Experiments were conducted using mature C2C12 Myotubes to eliminate systemic cytokine effects and avoid paracrine signaling by nonmuscle cell types. Time-course protocols were used to define the sequence of cellular responses. We found that atrogin1/MAFbx mRNA and MuRF1 mRNA are elevated 60–120 min after myotube exposure to either IL-1α or IL-1β. These responses are preceded by signaling events that promote E3 expression. Both IL-1 isoforms stimulate phosphorylation of p38 mitogen-activated protein kinase and stimulate nuclear factor-κB (NF-κB) signaling; I-κB levels fall and NF-κB DNA binding activity increases. Other regulators of E3 expression are unaffected by IL-1 [cytosolic oxidant activity, Forkhead-O (Foxo) activity] or respond paradoxically (AKT). Chronic exposure of C2C12 Myotubes over 48 h resulted in reduced myotube width and loss of sarcomeric actin. We conclude that IL-1α and IL-1β act via an oxidant- and AKT/Foxo-independent mechanism to activate p38 MAPK, stimulate NF-κB signaling, increase expression of atrogin1/MAFbx and MuRF1, and reduce myofibrillar protein in differentiated Myotubes.
Min-kyeong Lee - One of the best experts on this subject based on the ideXlab platform.
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Protective Effect of Pyropia yezoensis Peptide on Dexamethasone-Induced Myotube Atrophy in C2C12 Myotubes.
Marine drugs, 2019Co-Authors: Min-kyeong Lee, Jeong-wook Choi, Youn Hee Choi, Taek-jeong NamAbstract:Dexamethasone (DEX), a synthetic glucocorticoid, causes skeletal muscle atrophy. This study examined the protective effects of Pyropia yezoensis peptide (PYP15) against DEX-induced myotube atrophy and its association with insulin-like growth factor-I (IGF-I) and the Akt/mammalian target of rapamycin (mTOR)-forkhead box O (FoxO) signaling pathway. To elucidate the molecular mechanisms underlying the effects of PYP15 on DEX-induced myotube atrophy, C2C12 Myotubes were treated for 24 h with 100 μM DEX in the presence or absence of 500 ng/mL PYP15. Cell viability assays revealed no PYP15 toxicity in C2C12 Myotubes. PYP15 activated the insulin-like growth factor-I receptor (IGF-IR) and Akt-mTORC1 signaling pathway in DEX-induced myotube atrophy. In addition, PYP15 markedly downregulated the nuclear translocation of transcription factors FoxO1 and FoxO3a, and inhibited 20S proteasome activity. Furthermore, PYP15 inhibited the autophagy-lysosomal pathway in DEX-stimulated myotube atrophy. Our findings suggest that PYP15 treatment protected against myotube atrophy by regulating IGF-I and the Akt-mTORC1-FoxO signaling pathway in skeletal muscle. Therefore, PYP15 treatment appears to exert protective effects against skeletal muscle atrophy.
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Pyropia yezoensis Protein Prevents Dexamethasone-Induced Myotube Atrophy in C2C12 Myotubes.
Marine drugs, 2018Co-Authors: Min-kyeong Lee, Jeong-wook Choi, Youn Hee Choi, Taek-jeong NamAbstract:Glucocorticoids (GCs), which are endocrine hormones released under stress conditions, can cause skeletal muscle atrophy. This study investigated whether Pyropia yezoensis crude protein (PYCP) inhibits synthetic GCs dexamethasone (DEX)-induced myotube atrophy associated with proteolytic systems. Mouse skeletal muscle C2C12 Myotubes were treated with DEX in the presence or absence of PYCP. DEX exposure (100 μM) for 24 h significantly decreased myotube diameter and myogenin expression, which were all increased by treatment with 20 and 40 μg/mL PYCP. Additionally, PYCP significantly reduced the nuclear expression of the forkhead box transcription factors, FoxO1 and FoxO3a, and ubiquitin-proteasome pathway activation. Further mechanistic research revealed that PYCP inhibited the autophagy-lysosome pathway in DEX-induced C2C12 Myotubes. These findings indicate that PYCP prevents DEX-induced myotube atrophy through the regulation of FoxO transcription factors, followed by the inhibition of the ubiquitin-proteasome and autophagy-lysosome pathways. Therefore, we suggest that inhibiting these two proteolytic processes with FoxO transcription factors is a promising strategy for preventing DEX-related myotube atrophy.
S.j. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Formation of Myotubes in aneural rat muscles.
Developmental biology, 1993Co-Authors: S.j. Wilson, A J HarrisAbstract:Skeletal muscles formed in the absence of innervation are deficient in number of fibers, atrophic, and prone to degeneration. We and others have suggested that primary Myotubes form autonomously, and the major effect of embryonic denervation is to halt the formation of secondary Myotubes by removing the mitotic stimulus for generation of their precursor myoblasts. This hypothesis has recently been put into question by the results of work by Condon et al . (Dev. Biol., 138, 275-295, 1990) and by B. J. Fredette and L. T. Landmesser (Dev. Biol. 143, 19-35, 1991) who propose that lowered secondary myotube numbers are at least in part due to absence of the primary Myotubes which would normally serve as scaffold for their formation. We distinguish between these hypotheses by studying generation and degeneration of primary Myotubes and formation of secondary Myotubes in fetal rat muscles denervated by injection of β-bungarotoxin at different times between Embryonic Days (E) 14 and 17. Denervation at any of these times reduced primary myotube numbers on E18 to about 80% of control. Despite this modest decrease in primary myotube numbers, secondary myotube generation fell to below 3% of normal in extensor digitorum longus (EDL) muscles denervated on E14 or E15 and to below 12% of control in soleus muscles denervated on E14-E16. Secondary Myotubes were associated with degenerating as well as intact primary Myotubes. More secondary Myotubes were generated only if nerves had been present up until E16 for EDL or E17 for soleus. We suggest that these observations of a critical period until E16 (EDL) or E17 (soleus) during which innervation is an absolute prerequisite for secondary myotube formation reflect the presence of a nerve-dependent population of myoblasts which must be activated before secondary myotube formation can commence.
