Inhibition of Myoblast Fusion After One Round of Dna Synthesis in 5-Bromodeoxyuridine

Bischoff, Richard; Holtzer, H.

doi:10.1083/jcb.44.1.134

Cited by 311 publications

(79 citation statements)

References 39 publications

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“…In most experiments this medium also contained 1001AM 5-bromodeoxyuridine (BUdR). BUdR incorporation inhibits cell differentiation (30,31), and we have shown that the incorporation of BUdR into undifferentiated myoblasts prevents myosin light chain induction after their fusion to differentiated myocytes (28) . In high concentrations, BUdR also inhibits cell division .…”

Section: Methodsmentioning

confidence: 99%

Induction of muscle genes in neural cells.

Wright¹

1984

The Journal of Cell Biology

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The regulation of skeletal muscle genes was examined in heterokaryons formed by fusing differentiated chick skeletal myocytes to four different rat neural cell lines. Highly enriched populations of heterokaryons isolated using irreversible biochemical inhibitors were labeled with ["S]methionine and analyzed on two-dimensional gels . Rat skeletal myosin light chains were induced in three of the four cell combinations. The one exception, the S-20 cholinergic cell line, not only failed to synthesize rat muscle proteins but also suppressed chick myogenic functions . Experiments with heterokaryons between chick myocytes and cells from whole embryonic rat brain cultures demonstrated that rat skeletal myosin light chains are inducible in normal diploid neural cells as well as in established neural cell lines . In contrast, dividing cell hybrids between rat myoblasts and rat glial cells were nonmyogenic . These results demonstrate that although neural cells may contain factors that prevent the decision to differentiate along myogenic lines in cell hybrids, most neural cell lines do not dominantly suppress the expression of muscle structural genes in heterokaryons . Furthermore, the skeletal myosin light chain genes in most neural cell lines are regulated by a mechanism that permits them to respond to putative chick skeletal myocyte-inducing factors . The "open" state of these myogenic genes may explain many of the reports of apparent "transdifferentiation" to muscle in neural cultures and neural tumors .Heterokaryons are the initial fusion product between two cells, where both nuclei exist within a common cytoplasm . The interactions in heterokaryons ofthe regulatory molecules from both parents provide a test system for examining the mechanisms of specific gene activation, the nature of cell determination, and the potential reversibility of cell differentiation . We have shown that differentiated functions can be induced in determined but undifferentiated precursor cells following their fusion to terminally differentiated cells within the same developmental lineage. Fusing undifferentiated rat or quail myoblasts to differentiated chick skeletal myocytes resulted in the induction of rat or quail myosin light chain synthesis (1-3). In contrast, when cells from a different histiotype were used, differentiated functions were suppressed. Neither rat nor chick myosin light chain synthesis occurred in heterokaryons formed by fusing rat fibroblasts to differentiated chick skeletal myocytes (4) . These results are consistent with the hypothesis that cell determination and differentiation involve the dominant suppression ofalternate developmental pathways. To examine the generality ofthis phenomenon, we have now examined the regulation of muscle functions in heterokaryons formed by fusing chick myocytes to cells of additional histiotypes.

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Section: Methodsmentioning

confidence: 99%

Induction of muscle genes in neural cells.

Wright¹

1984

The Journal of Cell Biology

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“…Muscle is an interesting case and has probably been studied in the greatest detail (Bischoff and Holtzer 1970). Chicken myoblasts grown in BrdU do not express any differentiated markers (Paterson and Bishop 1977) and will continue to divide until the analog is removed.…”

Section: Brdu Inhibits Cmd1 and Myod1 Expression In Myoblastsmentioning

confidence: 99%

An avian muscle factor related to MyoD1 activates muscle-specific promoters in nonmuscle cells of different germ-layer origin and in BrdU-treated myoblasts.

Lin¹,

Dechesne²,

Eldridge³

et al. 1989

Genes Dev.

161

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We isolated the cDNA encoding a myogenic [actor expressed in embryonic chick breast muscle by virtue of its weak hybridization to the mouse MyoD1 clone. Nucleotide sequence analysis and amino acid comparison define this clone, CMD1, as encoding a protein similar to mouse MyoD1. CMD1 encodes a polypeptide smaller than MyoD1, 298 versus 318 amino acids, respectively, and is 80% concordant by amino acid sequence overall. The basic and myc domains required for myogenic conversion of mouse 10TI/2 'fibroblasts' to myoblasts with MyoD1 are completely conserved in CMD1. CMD1 is just as efficient as the mouse homolog in myogenic conversion of 10TV2 cells and coactivates the endogenous mouse MyoD1 gene in the process. The efficiency of myoblast conversion depends on the levels of CMD 1 expression and suggests that the cellular concentration of CMD1 plays a role in the onset of myogenesis. Transient expression of CMD1 in a variety of nonmuscle cells from different germ-layer origins activates both cotransfected muscle-specific promoters and, in some cases, endogenous muscle-specific genes. 5-Bromodeoxyuridine (BrdU) treatment of chicken and mouse myoblasts reduces the expression of CMD1 and MyoD1, respectively, and may explain how this thymidine analog inhibits myogenesis and the activity of transfected muscle-specific promoters in BrdU-treated myoblasts. Transient expression of CMD 1 in BrdU-treated myoblasts reactivates cotransfected muscle-specific promoters. CMD1 activates muscle-specific promoters in cotransfections regardless of cell type, whereas 'housekeeping' or constitutive promoters can be activated moderately, unaffected, or repressed, depending on the promoter and cell background. The rate and degree of myogenic conversion may be more restricted by cell phenotype than by germ-layer origin.

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“…Labtek chamber slides (Nunc, Denmark) were used for in situ hybridisation studies. In order to study the influence of an inhibition of myogenic differentiation, some cultures were treated by 5 µg·mL -1 of 5-bromo-deoxyuridine (BrdU, [26]). All cultures were incubated at 37 o C in a 5% CO 2 atmosphere, and were fed fresh medium 24 h after plating.…”

Section: Cell Culturesmentioning

confidence: 99%

Location of myostatin expression during bovine myogenesis in vivo and in vitro

et al. 2003

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-Mutations in the myostatin gene lead to double-muscling in cattle indicating that it is a negative regulator of the total number of muscle fibres. Myostatin expression was analysed by RT-PCR in three developing bovine muscles. It decreased during differentiation in Semitendinosus and Biceps femoris, and increased in the late differentiating Masseter during gestation. A combination of in situ hybridisation and immuno-histochemical detection of myosin heavy chains (MHC) allowed us to locate the expression in myofibres containing only developmental MHC at different stages and in fast IIA fibres at the end of gestation. In vitro, myostatin was undetectable during proliferation, peaked at the onset of fusion and decreased during terminal differentiation. It was not detected in myotubes by in situ hybridisation. The inhibition of differentiation by BrdU prevented the decrease in expression. Our results show that the peak in myostatin expression coincides with early differentiation indicating a regulatory role in cattle myogenesis. myostatin [GDF8] / cattle / myogenesis / myoblast culture / in situ hybridisation

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Inhibition of Myoblast Fusion After One Round of Dna Synthesis in 5-Bromodeoxyuridine

Cited by 311 publications

References 39 publications

Induction of muscle genes in neural cells.

Induction of muscle genes in neural cells.

An avian muscle factor related to MyoD1 activates muscle-specific promoters in nonmuscle cells of different germ-layer origin and in BrdU-treated myoblasts.

Location of myostatin expression during bovine myogenesis in vivo and in vitro

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