The rat myogenic cell line L6E9 induces skeletal but not cardiac α-actin mRNA upon fusion to form myotubes. However, when a human cardiac α-actin gene was introduced into L6E9 myoblasts, ...differentiation of the cells led to the accumulation of human gene transcripts in parallel with those derived from the endogenous skeletal α-actin gene. This result demonstrates that factors which direct rat myogenesis can regulate a muscle gene from another species and that the L6E9 cells may have a defect in their ability to activate endogenous cardiac actin gene expression.
Somatic cell hybrids between hepatoma and Friend erythroleukemia parental cells were studied for the expression of liver-specific and erythroid properties. Several independent clones were isolated ...using HAT selection and were shown to be true hybrids by isozyme and chromosome analysis. All displayed a complete extinction of hemoglobin and globin mRNA production, but a retention of albumin and transferrin secretion. The data suggest that erythroid differntiation is being actively inhibited by the hepatoma genome. Possible mechanisms that might explain these results are discussed in the light of current hypotheses regarding the mechanism of cell differentiation.
PDF
