EXPRESSION OF INSULIN-LIKE GROWTH-FACTOR-II (IGF-II) AND H19 IN MURINE TERATOCARCINOMAS DERIVED FROM EMBRYONIC STEM (ES) CELLS

Insulin-like growth factor II (IGF-II) is expressed during embryogenes is in rodents and humans, but is not produced in most adult tissues. T his pattern of expression is closely shared by the gene H19, which lie s 3' to IGF-II. This, together with the fact that the genes are recipr ocally imprinted, has led to the proposal that the genes are under com mon transcriptional control by the H19 enhancers during development. I n the present study, embryonic stem (ES) cells have been used to gener ate teratocarcinomas in mice. These tumours generate a wide range of d ifferentiated tissues which have been subjected to hybridisation histo chemistry with RNA probes to H19 and IGF-II. Coexpression of the two g enes was found in a range of tissues, a pattern consistent with the id ea of common transcriptional control. However, there were some areas i n which H19 was expressed strongly in comparison with IGF-II and vice versa suggesting the existence of further control elements other than the H19 enhancers.