TISSUE-SPECIFIC AND DEVELOPMENT-SPECIFIC EXPRESSION IN TRANSGENIC MICE OF A TYPE-I PROCOLLAGEN (COL1A1) MINIGENE CONSTRUCT WITH 2.3 KB OF THE PROMOTER REGION AND 2 KB OF THE 3'-FLANKING REGION - SPECIFICITY ISINDEPENDENT OF THE PUTATIVE REGULATORY SEQUENCES IN THE 1ST INTRON
Bp. Sokolov et al., TISSUE-SPECIFIC AND DEVELOPMENT-SPECIFIC EXPRESSION IN TRANSGENIC MICE OF A TYPE-I PROCOLLAGEN (COL1A1) MINIGENE CONSTRUCT WITH 2.3 KB OF THE PROMOTER REGION AND 2 KB OF THE 3'-FLANKING REGION - SPECIFICITY ISINDEPENDENT OF THE PUTATIVE REGULATORY SEQUENCES IN THE 1ST INTRON, Biochemistry, 32(35), 1993, pp. 9242-9249
Previous reports have provided inconsistent data as to the cis-regulat
ory elements that are essential for correct expression of the gene for
the proalpha1 (I) chain of type I procollagen (COL1A1) in the many ti
ssues in which the protein is synthesized. Here, two internally delete
d minigene versions of the human COL1A1 gene were used to prepare tran
sgenic mice. The constructs made it possible to test regulatory sequen
ces in the normal context of the gene. Also, in contrast to the report
er genes used in previous experiments, the constructs made it possible
to assay quantitatively expression of the exogenous genes relative to
expression of the endogenous COL1A1 gene, both as mRNA and as protein
. The average level of expression of the minigenes varied among three
transgenic lines, but the ratio of expression of the minigenes to expr
ession of the endogenous gene was the same in all transgenic mice of a
given line. Within the same line, the ratio of expression was essenti
ally the same in nine or more tissues in which expression of the endog
enous gene varied widely. Also, the ratio of expression within a given
line was the same in 15-day-old embryos and in mice ranging in age fr
om 4 days to 4 months. In addition, the ratio remained constant during
repair of a surgical wound. The results demonstrated, therefore, that
the minigene constructs with about 2.3 kb of the promoter region and
about 2 kb of the 3'-flanking region contained all of the sequences ne
cessary for correct expression of the genes in a tissue-specific and d
evelopment-specific manner. Assays of a line of transgenic mice expres
sing the minigene with the deletion in the first intron demonstrated t
hat the first intron of the COL1A1 gene had no discernible effect on t
he specificity of expression. Therefore, the results did not support p
revious data suggesting that the relatively large first intron of the
gene contains important regulatory sequences.