Analysis of chromosome aberrations induced by U5 RNA

A small nuclear RNA, U5, was reported previously to induce chromosome aberrations. This was further analyzed in the present study. An in vitro transcript from a synthetic DNA template, which corresponds to the 3' half of the first stem of U5, induced chromosome aberrations upon transfection of a rat fibroblast, 3Y1 cells. Introduction of an expression vector construct carrying the same part of the U5 sequence resulted in morphological transformation of the cells. A cytological analysis of the transformed cells showed chromosome abnormalities similar to those induced by the RNAs. It was also shown that the frequency of chromosome aberrations in the transformed cells increased by elevating the level of the transcript. A possible mechanism of chromosome aberrations by the RNAs is discussed.