The First Exon of the Rat Aldolase C Gene Is Essential for Restoring the Chromatin Structure in Transgenic Mice

Abstract

A 13-kb fragment of the rat aldolase C gene contains sufficient information for gene expression. Transgenic mice carrying the 13-kb fragment showed restoration of chromatin structure and tissue-specific, copy number-dependent expression. To localize the regulatory elements responsible for restoring chromatin structure, several mutated constructs were used to produce transgenic mice. Three activities were examined: recreation of DNase hypersensitive sites, restoration of methylation status, and copy number-dependent expression. Deletions of the 3'-flanking region did not affect those activities. Deletion of seven introns affected the mRNA levels but not the restoration of the chromatin structure. The insertion of the LacZ gene into the first exon of the transgene interfered with both the restoration of the chromatin structure and the copy number-dependent expression in transgenic mice. DNase I footprinting assays revealed that brain-specific factors bind to the sequence disrupted by the LacZ insertion. These results suggest that the sequence in the first exon is essential for restoring the chromatin structure of the rat aldolase C gene.

Upstream Elements Involved in Vivo in Activation of the Brain-specific Rat Aldolase C Gene

“…However, ␤-galactosidase localization was different in four other lines, probably due to an integration site effect. Therefore, a relevant study of brain expression patterns directed by different combinations of cis-acting sequences of the rat aldolase C gene will require the inclusion of essential regulatory elements in the transgenes, as has been proposed recently for exon 1 (67).…”

BLG‐e1 – A novel regulatory element in the distal region of the β‐lactoglobulin gene promoter

“…Intragenic sequences have already been shown to affect the promoter's chromatin [33]. The general requirement for intronic sequences, particularly those residing in BLG intron 1, for detectable transcription in transgenic mice [15,16,34,35] argues their involvement in preventing the localization of genes near centromeric heterochromatin [36] or their barrier activity against the propagation of heterochromatic domains [37].…”