Intracisternal A particles: RNA expression and DNA methylation in murine teratocarcinoma cell lines.

Two main intracisternal-A-particle-specific RNA species (29 to 30S and 35 to 36S) are variably expressed in particle-producing and particle-nonproducing murine teratocarcinoma cell lines. An analysis of DNA methylation patterns after hybridization with an intracisternal-A-particle-specific probe showed an apparent direct correlation between DNA methylation and RNA expression. However, when the methylation assay was performed on the excised intracisternal A particle genes in one of the particle-rich cell lines (PCC6), some undermethylated sequences were detectable. These results are consistent with the concept that only few of the genes are transcriptionally active.