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DNA methylation pattern of a tandemly repeated LacZ transgene indicates that most copies are silent
Author(s) -
Lau Stephen,
Jardine Karen,
McBurney Michael W.
Publication year - 1999
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/(sici)1097-0177(199906)215:2<126::aid-dvdy5>3.0.co;2-8
Subject(s) - biology , transgene , dna methylation , gene , microbiology and biotechnology , cpg site , genetics , locus (genetics) , methylation , dna , genomic imprinting , gene expression
The Pgk‐1,2‐lacZ transgene consists of the ubiquitously‐expressed Pgk‐1 promoter driving expression of the E. coli lacZ reporter gene. We studied the expression of this transgene in a mouse strain carrying 8–9 tandem copies of this construct. When inherited through the male germ line, the transgene was expressed in all tissues examined but when inherited through the female germ line, the transgene became irreversibly inactivated. The lacZ region is a CpG‐rich island that was essentially entirely methylated in all copies of the silent, maternally‐inherited transgene. At the active transgenic locus, all but one of the copies were entirely methylated. This one unmethylated copy was adjacent to the cellular DNA and was presumed to be the expressed transgene copy. These results suggest that the tandem repeats of transgenes become silenced by a mechanism associated with DNA methylation and that proximity to the cellular genome may be important in maintaining expression against the spread of inactivation from the adjacent silent transgenes. Dev Dyn 1999;215:126–138 . © 1999 Wiley‐Liss, Inc.