Influence of elastin gene polymorphism on the elastin content of the aorta- A study in 2 strains of rat

The elastin content in the thoracic aorta of male Brown-Norway (BN) rats is 31.4+/-1.2% (dry weight),whereas that of male LOU rats is 37.2+/-1.0%. A s imilar difference in the elastin content of the thoracic aorta is also obse rved in female animals. Furthermore, in the thoracic aorta of young, growin g rats as well as in cultured aortic smooth muscle cells, the steady-state level of elastin mRNA is significantly lower in the BN than in the LOU stra in. These results suggested that 1 or more genes control the elastin mRNA l evel and the elastin content in the aortas of BN and LOU rats. A possible r elationship between a polymorphism in the elastin gene and the elastin cont ent of the aorta was tested. For this purpose, the aortic elastin content w as measured in F-1 and F-2 generations bred from LOU and BN rats and was co mpared with that of the F-0 (parental) generation. A polymorphic marker loc ated in intron 25 of the elastin gene has been used to genotype the F-2 rat s. The degree of genetic determination of aortic elastin content was estima ted to be 73% in the F-2 cohort, but the elastin locus accounts for only 3. 9% of the total variance in aortic elastin content. Other genes are thus re sponsible for the major part of the observed interstrain difference by regu lating the transcription of the gene, the stability of elastin mRNA, and/or posttranslational events.