Transcriptional regulation of muscle-specific genes during myoblast differentiation.

A rapid, highly sensitive method to determine the mRNA level of muscle-specific markers using TaqMan PCR analysis was developed and used to study sequential gene regulation of myoblasts during induced differentiation of C2C12 cells. mRNA levels of muscle regulatory factor (MRF) myogenin, alpha-actin, thermoregulatory uncoupling protein UCP2 and glucose transporter isotype glut4 increased rapidly during early stage differentiation. In contrast, myf5, beta-actin, UCP1 and glut1 mRNA levels gradually decreased during 8 days. However, the mRNA level of other genes such as MyoD, glyceraldehyde-3-phosphate dehydrogenase and hexokinase II changed only slightly in comparison. Muscle-specific uncoupling protein UCP3 mRNA was detected during differentiation and increased rapidly within 8 days. These data clearly show the sequential and the differential regulation of muscle-specific genes in C2C12 cells during multinucleate myotube formation.