scholarly journals Isolation and validation of human prepubertal skeletal muscle cells: maturation and metabolic effects of IGF-I, IGFBP-3 and TNFα

2005 ◽  
Vol 568 (1) ◽  
pp. 229-242 ◽  
Author(s):  
Malcolm Grohmann ◽  
Emily Foulstone ◽  
Gavin Welsh ◽  
Jeff Holly ◽  
Julian Shield ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Metabolic Effects ◽  
Igf I ◽  
Igfbp 3

ALY688 elicits adiponectin-mimetic signaling and improves insulin action in skeletal muscle cells

2021 ◽  
Author(s):  
Hye Kyoung Sung ◽  
Patricia L. Mitchell ◽  
Sean Gross ◽  
Andre Marette ◽  
Gary Sweeney
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Muscle Cells ◽  
Temporal Analysis ◽  
Skeletal Muscle Cells ◽  
Adiponectin Receptor ◽  
Metabolic Effects

Adiponectin is well established to mediate many beneficial metabolic effects, and this has stimulated great interest in development and validation of adiponectin receptor agonists as pharmaceutical tools. This study investigated the effects of ALY688, a peptide-based adiponectin receptor agonist, in rat L6 skeletal muscle cells. ALY688 significantly increased phosphorylation of several adiponectin downstream effectors, including AMPK, ACC and p38MAPK, assessed by immunoblotting and immunofluorescence microscopy. Temporal analysis using cells expressing an Akt biosensor demonstrated that ALY688 enhanced insulin sensitivity. This effect was associated with increased insulin-stimulated Akt and IRS-1 phosphorylation. The functional metabolic significance of these signaling effects was examined by measuring glucose uptake in myoblasts stably overexpressing the glucose transporter GLUT4. ALY688 treatment both increased glucose uptake itself and enhanced insulin-stimulated glucose uptake. In the model of high glucose/high insulin (HGHI)-induced insulin resistant cells, both temporal studies using the Akt biosensor as well as immunoblotting assessing Akt and IRS-1 phosphorylation indicated that ALY688 significantly reduced insulin resistance. Importantly, we observed that ALY688 administration to high-fat high sucrose fed mice also improve glucose handling, validating its efficacy in vivo. In summary, these data indicate that ALY688 activates adiponectin signaling pathways in skeletal muscle, leading to improved insulin sensitivity and beneficial metabolic effects.

scholarly journals Focal adhesion kinase is required for IGF-I-mediated growth of skeletal muscle cells via a TSC2/mTOR/S6K1-associated pathway

2013 ◽  
Vol 305 (2) ◽  
pp. E183-E193 ◽  
Author(s):  
Hannah Crossland ◽  
Abid A. Kazi ◽  
Charles H. Lang ◽  
James A. Timmons ◽  
Philippe Pierre ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Growth ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Muscle Hypertrophy ◽  
Kinase Activity ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Cell Phenotype ◽  
Igf I

Focal adhesion kinase (FAK) is an attachment complex protein associated with the regulation of muscle mass through as-of-yet unclear mechanisms. We tested whether FAK is functionally important for muscle hypertrophy, with the hypothesis that FAK knockdown (FAK-KD) would impede cell growth associated with a trophic stimulus. C2C12 skeletal muscle cells harboring FAK-targeted (FAK-KD) or scrambled (SCR) shRNA were created using lentiviral transfection techniques. Both FAK-KD and SCR myotubes were incubated for 24 h with IGF-I (10 ng/ml), and additional SCR cells (±IGF-1) were incubated with a FAK kinase inhibitor before assay of cell growth. Muscle protein synthesis (MPS) and putative FAK signaling mechanisms (immunoblotting and coimmunoprecipitation) were assessed. IGF-I-induced increases in myotube width (+41 ± 7% vs. non-IGF-I-treated) and total protein (+44 ± 6%) were, after 24 h, attenuated in FAK-KD cells, whereas MPS was suppressed in FAK-KD vs. SCR after 4 h. These blunted responses were associated with attenuated IGF-I-induced FAK Tyr397 phosphorylation and markedly suppressed phosphorylation of tuberous sclerosis complex 2 (TSC2) and critical downstream mTOR signaling (ribosomal S6 kinase, eIF4F assembly) in FAK shRNA cells (all P < 0.05 vs. IGF-I-treated SCR cells). However, binding of FAK to TSC2 or its phosphatase Shp-2 was not affected by IGF-I or cell phenotype. Finally, FAK-KD-mediated suppression of cell growth was recapitulated by direct inhibition of FAK kinase activity in SCR cells. We conclude that FAK is required for IGF-I-induced muscle hypertrophy, signaling through a TSC2/mTOR/S6K1-dependent pathway via means requiring the kinase activity of FAK but not altered FAK-TSC2 or FAK-Shp-2 binding.

IGF-I and vitamin C promote myogenic differentiation of mouse and human skeletal muscle cells at low temperatures

2011 ◽  
Vol 317 (3) ◽  
pp. 356-366 ◽  
Author(s):  
Ai Shima ◽  
Jennifer Pham ◽  
Erica Blanco ◽  
Elisabeth R. Barton ◽  
H. Lee Sweeney ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Vitamin C ◽  
Low Temperatures ◽  
Human Skeletal Muscle ◽  
Myogenic Differentiation ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Human Skeletal Muscle Cells ◽  
Igf I

scholarly journals GH Regulation of IGF-I and Suppressor of Cytokine Signaling Gene Expression in C2C12 Skeletal Muscle Cells

Endocrinology ◽  
2001 ◽  
Vol 142 (9) ◽  
pp. 3890-3900 ◽  
Author(s):  
Cynthia L. Sadowski ◽  
Thomas T. Wheeler ◽  
Lu-Hai Wang ◽  
Henry B. Sadowski
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
Igf I ◽  
C2c12 Skeletal Muscle Cells

scholarly journals The effect of toll-like receptor ligands on energy metabolism and myokine expression and secretion in cultured human skeletal muscle cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ragna H. Tingstad ◽  
Frode Norheim ◽  
Fred Haugen ◽  
Yuan Z. Feng ◽  
Hege S. Tunsjø ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Oleic Acid ◽  
Energy Metabolism ◽  
Glucose Metabolism ◽  
Human Skeletal Muscle ◽  
Acid Metabolism ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Metabolic Effects ◽  
Human Skeletal Muscle Cells

AbstractSkeletal muscle plays an important role in glycaemic control and metabolic homeostasis, making it a tissue of interest with respect to type 2 diabetes mellitus. The aim of the present study was to determine if ligands of Toll-like receptors (TLRs) could have an impact on energy metabolism and myokine expression and secretion in cultured human skeletal muscle cells. The myotubes expressed mRNA for TLRs 1–6. TLR3, TLR4, TLR5 and TLR6 ligands (TLRLs) increased glucose metabolism. Furthermore, TLR4L and TLR5L increased oleic acid metabolism. The metabolic effects of TLRLs were not evident until after at least 24 h pre-incubation of the cells and here the metabolic effects were more evident for the metabolism of glucose than oleic acid, with a shift towards effects on oleic acid metabolism after chronic exposure (168 h). However, the stimulatory effect of TLRLs on myokine expression and secretion was detected after only 6 h, where TLR3-6L stimulated secretion of interleukin-6 (IL-6). TLR5L also increased secretion of interleukin-8 (IL-8), while TLR6L also increased secretion of granulocyte–macrophage colony stimulating factor (GM-CSF). Pre-incubation of the myotubes with IL-6 for 24 h increased oleic acid oxidation but had no effect on glucose metabolism. Thus IL-6 did not mimic all the metabolic effects of the TLRLs, implying metabolic effects beyond the actions of this myokine.

Developmental regulation of the mouse IGF-I exon 1 promoter region by calcineurin activation of NFAT in skeletal muscle

2007 ◽  
Vol 292 (5) ◽  
pp. C1887-C1894 ◽  
Author(s):  
Christina M. Alfieri ◽  
Heather J. Evans-Anderson ◽  
Katherine E. Yutzey
Keyword(s):  
Skeletal Muscle ◽  
Signaling Pathways ◽  
Muscle Development ◽  
Developmental Regulation ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Conserved Regions ◽  
Igf I ◽  
Exon 1 ◽  
I Gene

Skeletal muscle development and growth are regulated through multiple signaling pathways that include insulin-like growth factor I (IGF-I) and calcineurin activation of nuclear factor of activated T cell (NFAT) transcription factors. The developmental regulation and molecular mechanisms that control IGF-I gene expression in murine embryos and in differentiating C2C12 skeletal myocytes were examined. IGF-I is expressed in developing skeletal muscle, and its embryonic expression is significantly reduced in embryos lacking both NFATc3 and NFATc4. During development, the IGF-I exon 1 promoter is active in multiple organ systems, including skeletal muscle, whereas the alternative exon 2 promoter is expressed predominantly in the liver. The IGF-I exon 1 promoter flanking sequence includes two highly conserved regions that contain NFAT consensus binding sequences. One of these conserved regions contains a calcineurin/NFAT-responsive regulatory region that is preferentially activated by NFATc3 in C2C12 skeletal muscle cells and NIH3T3 fibroblasts. This NFAT-responsive region contains three clustered NFAT consensus binding sequences, and mutagenesis experiments demonstrated the requirement for two of these in calcineurin or NFATc3 responsiveness. Chromatin immunoprecipitation analyses demonstrated that endogenous IGF-I genomic sequences containing these conserved NFAT binding sequences interact preferentially with NFATc3 in C2C12 cells. Together, these experiments demonstrated that a NFAT-rich regulatory element in the IGF-I exon 1 promoter flanking region is responsive to calcineurin signaling and NFAT activation in skeletal muscle cells. The identification of a calcineurin/NFAT-responsive element in the IGF-I gene represents a potential mechanism of intersection of these signaling pathways in the control of muscle development and homeostasis.

IGF-I and insulin receptor signal transduction in trout muscle cells

2006 ◽  
Vol 290 (6) ◽  
pp. R1683-R1690 ◽  
Author(s):  
Juan Castillo ◽  
Ina Ammendrup-Johnsen ◽  
Marta Codina ◽  
Isabel Navarro ◽  
Joaquim Gutiérrez
Keyword(s):  
Skeletal Muscle ◽  
Signal Transduction ◽  
Primary Cultures ◽  
Insulin Receptors ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Suitable Model ◽  
Igf I ◽  
Trout Muscle

In this study, primary cultures of trout skeletal muscle cells were used to investigate the main signal transduction pathways of insulin and IGF-I receptors in rainbow trout muscle. At different stages of in vitro development (myoblasts on day 1, myocytes on day 4, and fully developed myotubes on day 11), we detected in these cells the presence of immunoreactivity against ERK 1/2 MAPK and Akt/PKB proteins, components of the MAPK and the phosphatidylinositol 3-kinase-Akt pathways, respectively, two of the main intracellular transduction pathways for insulin and IGF-I receptors. Both insulin and IGF-I activated both pathways, although the latter provoked higher immunoreactivity of phosphorylated MAPKs and Akt proteins. At every stage, increases in total MAPK immunoreactivity levels were observed when cells were stimulated with IGF-I or insulin, while total Akt immunoreactivity levels changed little under stimulation of peptides. Total Akt and total MAPK levels increased as skeletal muscle cells differentiated in culture. Moreover, when cells were incubated with IGF-I or insulin, MAPK-P immunoreactivity levels showed greater increases over the basal levels on days 1 and 4, with no effect observed on day 11. Although Akt-P immunoreactivity displayed improved responses on days 1 and 4 as well, a stimulatory effect was still observed on day 11. In addition, the present study demonstrates that purified trout insulin receptors possess higher phosphorylative activity per unit of receptor than IGF-I receptors. In conclusion, these results indicate that trout skeletal muscle culture is a suitable model to study the insulin and IGF-I signal transduction molecules and that there is a different regulation of MAPK and Akt pathways depending on the developmental stage of the muscle cells.

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