SEARCH OF THE 5' UNTRANSLATED REGION OF THE HUMAN CARDIAC ACTIN GENE FOR SEGMENTS CONTROLLING TRANSLATION

We have examined the possibility that the 5′-UT region of the human cardiac actin (cH-actin) mRNA is responsible for regulating translation of this transcript during skeletal myogenesis. Genes were constructed which consisted of the murine leukaemia virus promoter driving the Escherichia coli LacZ coding region with and without the cH-actin 5′-UT region. These constructs were transfected into L6 myoblasts that were subsequently differentiated into myotubes. The presence of the cH-actin 5′-UT region appeared to have no effect on expression of the LacZ reporter gene. EGTA blocks myogenesis and inhibits translation of muscle-specific transcripts (Endo, T. and Nadal-Ginard, B. (1987) Cell 49, 515-526) but EGTA had no effect on expression of the chimaeric LacZ transcripts. Thus, if the cH-actin transcript is subject to translational regulation, it must be mediated by sequences other than those of the 5′-UT region. © 1990.