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Inhibition of differentiation in myoblasts deprived of the interferon-related protein PC4
D Guardavaccaro1, M T Ciotti, B W Schäfer
1Istituto di Neurobiologia, Consiglio Nazionale delle Ricerche, Rome, Italy.
Abstract:
PC4 (pheochromocytoma cell-4) is an immediate early gene related to IFN-gamma, the mRNA of which is induced during the course of neuronal differentiation by nerve growth factor in the PC12 cell line. Here we report that PC4 mRNA is also expressed in the myoblast C2C12 cell line and is regulated during differentiation; its expression decreases within 6 h from the onset of differentiation, attains a minimum after 12 h, and returns to basal level within 36 h. This transient down-regulation of PC4 expression in C2C12 myoblasts is prevented by transforming growth factor beta, a molecule which inhibits the differentiation of muscle. Sense and antisense PC4 cDNA transfection strategies in C2C12 cells were then used to clarify the role of PC4 in muscle differentiation. While no effect was seen by over-expression of PC4, stable transfectants underexpressing PC4 exhibited a delay in attaining the differentiated phenotype, with an impairment of myogenin and myosin expression. Myogenin was also inhibited in C2C12 cells microinjected with the anti-PC4 polyclonal antibody A451. We thus postulate a role for PC4 as a positive regulator during muscle differentiation.
Insights
Pheochromocytoma cell-4 (PC4) gene expression is transiently downregulated during muscle cell differentiation. Underexpression of PC4 delays muscle differentiation, suggesting PC4 positively regulates this process.
Area of Science:
- Molecular Biology
- Cell Biology
- Developmental Biology
Background:
- PC4 (pheochromocytoma cell-4) is an immediate early gene.
- PC4 mRNA is induced during neuronal differentiation in PC12 cells.
- PC4's role in muscle differentiation was previously uncharacterized.
Purpose of the Study:
- To investigate the expression and role of PC4 during muscle cell differentiation.
- To determine if PC4 influences key muscle differentiation markers.
Main Methods:
- Quantitative analysis of PC4 mRNA expression in differentiating C2C12 myoblasts.
- Overexpression and underexpression of PC4 using cDNA transfection.
- Microinjection of anti-PC4 polyclonal antibody.
Main Results:
- PC4 mRNA expression decreased transiently during C2C12 myoblast differentiation.
- Transforming growth factor beta prevented PC4 downregulation.
- PC4 underexpression delayed differentiation and impaired myogenin and myosin expression.
- Anti-PC4 antibody inhibited myogenin expression.
Conclusions:
- PC4 plays a positive regulatory role in muscle differentiation.
- PC4 is a key regulator of myogenin and myosin expression during myogenesis.