Gene expression and secretion of insulin-like growth factor-binding proteins during myoblast differentiation

Catherine W. Ernst, Robert H. McCusker, Michael E. White

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Numerous cell types have been reported to secrete insulin-like growth factor-binding proteins (IGFBPS) in vitro. We have observed such IGFBPS in culture medium conditioned by the mouse myoblast cell line C2C12and have identified IGFBP-2 among the secreted IGFBPS. Since C2C12cells fuse in culture, these cells were used to examine IGFBP-2 mrna expression and protein secretion during myogenic differentiation. Cells were harvested at approximately 80% of confluent density. Additional cultures were rinsed, fed differentiation medium, and harvested when approximately 15%, 60%, and 85% differentiated (fused). Northern and dot blot analyses were performed using total cellular RNA and a labeled cdna specific for rat IGFBP-2. A single mrna transcript of approximately 1.8 kilobases was observed. The level of expression of IGFBP-2 mRNA was highest in proliferating cells and decreased to 35%, 20%, and less than 10% of initial levels as differentiation progressed. Serum-free medium was conditioned for 24 h at each time point and collected from similar cultures. Three IGFBP species of 32, 000, 30, 000, and 24, 000 mol wt (Mr) were detected in conditioned medium by probing Western blots with [125I]Igf-I (ligand blot analysis). The intensity of the 32, 000 Mrband decreased with differentiation. These same blots were probed with an antibody raised against the 34, 000 Mr bovine IGFBP-2. This antibody specifically bound to only the 32, 000 MrIGFBP. The level of antibody binding decreased by 50%, 90%, and nearly 100% as differentiation progressed. It, therefore, appears that IGFBP-2 is expressed and secreted in a differentiation-dependent manner by C2C12myoblasts and may, thus, be involved in the process of myoblast differentiation.

Original languageEnglish (US)
Pages (from-to)607-615
Number of pages9
Issue number2
StatePublished - Feb 1992


Dive into the research topics of 'Gene expression and secretion of insulin-like growth factor-binding proteins during myoblast differentiation'. Together they form a unique fingerprint.

Cite this