A CORRELATION BETWEEN DEXAMETHASONE INDUCIBILITY AND BASAL EXPRESSIONLEVELS OF RETROVIRAL VECTOR PROVIRUSES

Citation
M. Duch et al., A CORRELATION BETWEEN DEXAMETHASONE INDUCIBILITY AND BASAL EXPRESSIONLEVELS OF RETROVIRAL VECTOR PROVIRUSES, Nucleic acids research, 21(20), 1993, pp. 4777-4782
Citations number
50
Categorie Soggetti
Biology
Journal title
ISSN journal
03051048
Volume
21
Issue
20
Year of publication
1993
Pages
4777 - 4782
Database
ISI
SICI code
0305-1048(1993)21:20<4777:ACBDIA>2.0.ZU;2-T
Abstract
Identical transcription units inserted at different positions of mamma lian chromosomes may vary widely in transcriptional activity. We have used a set of ten cell clones with random unselected single integratio ns of retroviral vectors to study such position effects. The vector us ed carries a neo gene driven by the Akv murine leukemia virus long ter minal repeat that has only a weak promoter- enhancer activity in the t arget cell, the lymphoid cell line L691. Under transient expression co nditions, the strength of the Akv promoter - enhancer in the L691 cell s is increased by dexamethasone. In cell clones with single vector int egrations, a correlation is observed between the non-induced expressio n levels and the degree of dexamethasone induction. The strongest rela tive induction is found for the integrated vectors with the lowest non -induced expression levels and approaches the inducibility under trans ient expression. These results indicate that expression levels are com posed of distinct contributions from the integrated vector and from th e site of integration and are best explained in terms of a model in wh ich the sites of chromosomal integration exert variable positive enhan cer effects upon vector transcription.