Genes for collagen types I, IV, and V are transcribed in Hela cells but a postinitiation block prevents the accumulation of type I mRNA

Collagen mRNA synthesis in HeLa cells was evaluated by in vitro transcription of type I collagen DNA, nuclear run-on studies, and steady-state mRNA analysis. Type I collagen mRNA was accurately initiated by HeLa cell RNA polymerase II in nuclear extracts, and run-on analysis indicated that mRNAs for collagen types α1(I), α2(I), α1(III), α1(IV), and α2(V) were synthesized in HeLa cells. However, on assessing the steady-state levels of mRNAs of collagen types α1(I), α2(I), α1(IV), and α2(V), no type I mRNA was found in HeLa cells while types α1(IV) and α2(V) collagen mRNAs were observed. These results suggest that a postinitiation process prevents the accumulation of type I collagen mRNAs in HeLa cells. Persistence of types IV and V collagen mRNAs is consistent with the involvement of types IV and V collagen in adhesion of HeLa cells to glass or plastic.