Open AccessSARs stimulate but do not confer position independent gene expression
Author(s) -
Leonora Poljak,
Carole Seum,
Tiziana Mattioni,
Ulrich Karl Laemmli
Publication year - 1994
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/22.21.4386
Subject(s) - biology , reporter gene , enhancer , transfection , gene , schneider 2 cells , variegation (histology) , gene expression , position effect , microbiology and biotechnology , scaffold/matrix attachment region , genetics , rna interference , rna , chromatin remodeling
Two minimal scaffold-associated regions (SARs) from Drosophila were tested in stably transformed cells for their effects on the expression of reporter genes. The expression of genes bounded by two SARs is consistently stimulated by about 20- to 40-fold, if the average of a pool of cell transformants is analyzed. However, analysis of individual, stable cell transformants demonstrates that flanking SAR elements do not confer position-independent expression on the reporter gene and that the extent of position-dependent variegation is similarly large with or without the flanking SAR elements. The SAR stimulation of expression is observed in stable but not in transiently transfected cell lines. The Drosophila scs and scs' boundary elements, which do not bind to the nuclear matrix in vitro, are only about one-tenth as active as SARs in stimulating expression in stable transformants. Interestingly, the SAR stimulatory effect can be blocked by a fragment containing CpG islands (approximately 70% GC), if positioned between the SAR and the enhancer. In contrast, when inserted in the same position, control fragments, such as the scs/scs' elements, do not interfere with SAR function.