Characterization of cloned sequences complementary to F9 cell double-stranded RNA and their expression during differentiation.

In a cDNA library prepared from the RNA of cultured murine F9 teratocarcinoma cells, we identified sequences exhibiting strong hybridization to double-stranded RNA (dsRNA) of F9 cells but weak hybridization to mouse liver dsRNA. Northern-blot hybridization of RNA extracted from F9 cells with or without treatment with retinoic acid revealed differences in the expression of some of these sequences in undifferentiated and differentiated cells. As shown by Southern-blot hybridization experiments, these differences of expression were not related to a gross rearrangement of the corresponding genomic DNA sequences of the differentiated cells. When RNA from F9 cells was used, one of the cloned dsRNA-related sequences selected mRNA which was translated in vitro to a polypeptide with an Mr of 24,000; the level of this mRNA was reduced in F9 cells that had been treated with retinoic acid. Our results show that the differentiation of F9 cells induced by retinoic acid results in the differential expression of some middle-repetitive sequences.