Intronic ANG II type 2 receptor gene polymorphism 1675 G/A modulates receptor protein expression but not mRNA splicing

The X-linked ANG II type 2 receptor (AT2) is supposed to be involved in cardiovascular disorders. Two studies associated the A allele of the AT2 gene polymorphism (PM) 1675 G/A with left ventricular hypertrophy in men and coronary ischemia in women. Because the PM is located in the short intron 1 of the AT2 gene within a sequence motif similar to the splice branch site consensus, we tested whether it might affect pre-mRNA splicing and/or modulate AT2 receptor expression. We first analyzed the AT2 mRNA splice pattern by RT-PCR in myocardial samples from 12 explanted human hearts and compared it with the respective genotypes. All 12 patients, 10 hemizygous males (7 A, 3 G allele carriers) and 2 homozygous females (2 G/G allele carriers), exhibited the same myocardial AT2 splice pattern with a relative abundance of transcript exon 1/2/3 compared with exon 1/3. Next, AT2 minigene constructs were cloned from both alleles, comprising the core promoter and the complete transcribed region up to the translation st...