cis and trans activation of globin gene transcription in transient assays.
We examined the effects of the simian virus 40 enhancer sequence on transcription of cloned human alpha- and beta-globin genes shortly after their introduction into cultured mammalian cells. We find that (i) detectable transcription of the beta-globin gene but not the alpha-globin gene requires linkage to the enhancer; (ii) the enhancer increases the amount of beta-globin RNA at least 100-fold but results in only a 5- to 10-fold increase in the amount of alpha-globin RNA; (iii) plasmid replication does not increase the level of beta-globin RNA, regardless of linkage to the enhancer, but does result in an approximately equal to 50-fold increase in the level of alpha-globin RNA; (iv) the enhancer is not required for and does not increase transcription of either gene in 293 cells, an adenovirus 5-transformed human kidney cell line. We also show that an enhancer sequence is not required for activity of the normally enhancer-dependent simian virus 40 early promoter in 293 cells, indicating that these cells contain a trans-acting factor(s) that circumvents the requirement for the enhancer sequence.
D000510:Alpha-Globulins / Q000235:genetics*; D001483:Base Sequence; D001609:Beta-Globulins / Q000235:genetics*; D002460:Cell Line; D003001:Cloning, Molecular; D005796:Genes; D008040:Genetic Linkage; D005822:Genetic Vectors; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D010957:Plasmids; D013539:Simian virus 40 / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection
D000510:Alpha-Globulins; D001609:Beta-Globulins