ISSN:
1573-9368
Keywords:
gene expression
;
lacZ
;
HPRT
;
ES cells
;
gene targeting
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Transgenes in mice often exhibit different expression patterns in different transgenic lines. While the basis for this phenomenon is not understood, it is widely believed that the site at which the transgene becomes integrated into the mouse genome is a major factor in determining the pattern of expression. Most transgenic mice have been produced by microinjection of DNA into the male pronucleus, which results in integration of tandem arrays of the transgene at random chromosomal sites. In the experiments described in this report, electroporation of embryonic stem (ES) cells was used to place single copies of alacZ transgene into either random sites or into the HPRT (hypoxanthine phosphoribosyl transferase) locus of the mouse genome. Expression oflacZ was assayed by histochemical staining forEscherichia coli β-galactosidase activity in ES cells and in differentiated derivatives obtained by teratocarcinoma formation. Several of the randomly integrated cell lines expressedlacZ at high levels in a variety of cell types present in the tumours, but most notably in epithelial cells. Targeted cell lines withlacZ in opposite orientation to the direction of HPRT gene transcription also expressed well in epithelial cells, but the targeted cell lines did not express in a wider variety of cell types than some of the nontargeted cell lines. Targeted cell lines transcribinglacZ in the same orientation as HPRT transcription did not express high levels oflacZ in any differentiated cell type. Analysis of transcripts suggested that this orientation effect may have been the result of transcriptional interference perpetrated by the HPRT gene promoter.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01977675
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