scholarly journals A Novel Mechanism of Sequestering Fibroblast Growth Factor 2 by Glypican in Lipid Rafts, Allowing Skeletal Muscle Differentiation

2010 ◽  
Vol 30 (7) ◽  
pp. 1634-1649 ◽  
Author(s):  
Jaime Gutiérrez ◽  
Enrique Brandan
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Lipid Rafts ◽  
Muscle Differentiation ◽  
Myoblast Fusion ◽  
Fibroblast Growth Factor 2 ◽  
Skeletal Muscle Differentiation ◽  
Fibroblast Growth ◽  
Raft Domains

ABSTRACT Heparan sulfate proteoglycans (HSPGs) are critical modulators of growth factor activities. Skeletal muscle differentiation is strongly inhibited by fibroblast growth factor 2 (FGF-2). We have shown that HSPGs present at the plasma membrane are expressed in myoblasts and are downregulated during muscle differentiation. An exception is glypican-1, which is present throughout the myogenic process. Myoblasts that do not express glypican-1 exhibit defective differentiation, with an increase in the receptor binding of FGF-2, concomitant with increased signaling. Glypican-1-deficient myoblasts show decreased expression of myogenin, the master gene that controls myogenesis, myosin, and the myoblast fusion index. Reversion of these defects was induced by expression of rat glypican-1. Glypican-1 is the only HSPG localized in lipid raft domains in myoblasts, resulting in the sequestration of FGF-2 away from FGF-2 receptors (FGFRs) located in nonraft domains. A chimeric glypican-1, containing syndecan-1 transmembrane and cytoplasmic domains, is located in nonraft domains interacting with FGFR-IV- and enhanced FGF-2-dependent signaling. Thus, glypican-1 acts as a positive regulator of muscle differentiation by sequestering FGF-2 in lipid rafts and preventing its binding and dependent signaling.

scholarly journals Gait disturbances and muscle dysfunction in fibroblast growth factor 2 knockout mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Homer-Bouthiette ◽  
L. Xiao ◽  
Marja M. Hurley
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Muscle Strength ◽  
Fibroblast Growth Factor ◽  
Muscle Function ◽  
Fibroblast Growth Factor 2 ◽  
Fibroblast Growth ◽  
Skeletal Muscle Function ◽  
Age Related ◽  
Gait Disturbances

AbstractFibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.

scholarly journals Cell surface fibroblast growth factor and epidermal growth factor receptors are permanently lost during skeletal muscle terminal differentiation in culture.

1988 ◽  
Vol 107 (2) ◽  
pp. 761-769 ◽  
Author(s):  
B B Olwin ◽  
S D Hauschka
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Surface ◽  
Fibroblast Growth Factor ◽  
Growth Factor Receptor ◽  
Growth Factor Receptors ◽  
Skeletal Muscle Differentiation ◽  
Fibroblast Growth ◽  
Epidermal Growth

One characteristic of skeletal muscle differentiation is the conversion of proliferating cells to a population that is irreversibly postmitotic. This developmental change can be induced in vitro by depriving the cultures of specific mitogens such as fibroblast growth factor (FGF). Analysis of cell surface FGF receptor (FGFR) in several adult mouse muscle cell lines and epidermal growth factor receptor (EGFR) in mouse MM14 cells reveals a correlation between receptor loss and the acquisition of a postmitotic phenotype. Quiescent MM14 cells, mitogen-depleted, differentiation-defective MM14 cells, and differentiated BC3H1 muscle cells (a line that fails to become postmitotic upon differentiation) retained their cell surface FGFR. These results indicate that FGFR loss is not associated with either reversible cessation of muscle cell proliferation or biochemical differentiation and thus, further support a correlation between receptor loss and acquisition of a postmitotic phenotype. Comparison of the kinetics for growth factor receptor loss and for commitment of MM14 cells to a postmitotic phenotype reveals that FGFR rises transiently from approximately 700 receptors/cell to a maximum of approximately 2,000 receptors/cell 12 h after FGF removal, when at the same time, greater than 95% of the cells are postmitotic. FGFR levels then decline to undetectable levels by 24 h after FGF removal. During the interval in which FGFR increases and then disappears there is no change in its affinity for FGF. The transient increase in growth factor receptors appears to be due to a decrease in ligand-mediated internalization because EGFR, which undergoes an immediate decline when cultures are deprived of FGF (Lim, R. W., and S. D. Hauschka. 1984. J. Cell Biol. 98:739-747), exhibits a similar transient rise when cultures are grown in media containing both EGF and FGF before switching the cells to media without these added factors. These results indicate that the loss of certain growth factor receptors is a specific phenotype acquired during skeletal muscle differentiation, but they do not resolve whether regulation of FGFR number is causal for initiation of the postmitotic phenotype. A general model is presented in the discussion.

scholarly journals Repression of myogenic differentiation by aFGF, bFGF, and K-FGF is dependent on cellular heparan sulfate.

1992 ◽  
Vol 118 (3) ◽  
pp. 631-639 ◽  
Author(s):  
B B Olwin ◽  
A Rapraeger
Keyword(s):  
Skeletal Muscle ◽  
Biological Activity ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Heparan Sulfate ◽  
Chondroitin Sulfate ◽  
Fibroblast Growth Factor ◽  
Skeletal Muscle Differentiation ◽  
Fibroblast Growth ◽  
Fgf Signalling

We have proposed a model in which fibroblast growth factor (FGF) signalling requires the interaction of FGF with at least two FGF receptors, a heparan sulfate proteoglycan (HSPG) and a tyrosine kinase. Since FGF may be a key mediator of skeletal muscle differentiation, we examined the synthesis of glycosaminoglycans in MM14 skeletal muscle myoblasts and their participation in FGF signalling. Proliferating and differentiated MM14 cells exhibit similar levels of HSPG, while differentiated cells exhibit reduced levels of chondroitin sulfate proteoglycans and heparan sulfate chains. HSPGs, including syndecan, present in proliferating cells bind bFGF, while the majority of chondroitin sulfate and heparan sulfate chains do not. Treatment of skeletal muscle cells with chlorate, a reversible inhibitor of glycosaminoglycan sulfation, was used to examine the requirement of sulfated proteoglycans for FGF signalling. Chlorate treatment reduced glycosaminoglycan sulfation by 90% and binding of FGF to high affinity sites by 80%. Chlorate treatment of MM14 myoblasts abrogated the biological activity of acidic, basic, and Kaposi's sarcoma FGFs resulting in terminal differentiation. Chlorate inhibition of FGF signalling was reversed by the simultaneous addition of sodium sulfate or heparin. Further support for a direct role of heparan sulfate proteoglycans in fibroblast growth factor signal transduction was demonstrated by the ability of heparitinase to inhibit basic FGF binding and biological activity. These results suggest that activation of FGF receptors by acidic, basic or Kaposi's sarcoma FGF requires simultaneous binding to a HSPG and the tyrosine kinase receptor. Skeletal muscle differentiation in vivo may be dependent on FGFs, FGF tyrosine kinase receptors, and HSPGs. The regulation of these molecules may then be expected to have important implications for skeletal muscle development and regeneration.

scholarly journals Heparan sulphate proteoglycans modulate fibroblast growth factor-2 binding through a lipid raft-mediated mechanism

2004 ◽  
Vol 379 (2) ◽  
pp. 331-341 ◽  
Author(s):  
Chia Lin CHU ◽  
J. Ann BUCZEK-THOMAS ◽  
Matthew A. NUGENT
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Lipid Rafts ◽  
Lipid Raft ◽  
Heparan Sulphate ◽  
Fibroblast Growth Factor 2 ◽  
Fibroblast Growth ◽  
Protein Kinase Cα ◽  
Heparan Sulphate Proteoglycans ◽  
Factor Interactions

We investigated how lipid raft association of HSPG (heparan sulphate proteoglycans) modulates FGF-2 (fibroblast growth factor-2/basic fibroblast growth factor) interactions with vascular smooth-muscle cells. When lipid rafts were disrupted with sterol-binding agents, methyl-β-cyclodextrin and filipin, FGF-2 binding to HSPG was reduced 2–5-fold, yet the amount and turnover of cell-surface HSPG were unaffected. Approx. 50–65% of bound FGF-2 was in lipid raft-associated fractions based on insolubility in cold Triton X-100 and flotation in OptiPrep density gradients, and this level was increased with higher FGF-2 concentrations. Less FGF-2 (50–90%) was associated in raft fractions when cholesterol was depleted or HSPG were degraded with heparinase III. To investigate how lipid raft–HSPG interactions altered binding, we compared the rates of FGF-2 dissociation with native, MβCD (methyl-β-cyclodextrin)- and filipin-treated cells. We found that FGF-2 dissociation rates were increased when lipid rafts were disrupted. These results suggest that localization of HSPG within lipid rafts creates high local concentrations of binding sites such that dissociation of FGF-2 is hindered. The localization of FGF-2 and HSPG to lipid rafts also correlated with the activation of protein kinase Cα. Thus raft association of HSPG might create growth factor traps resulting in increased binding and signal transduction to enhance cell sensitivity.

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