Characterization of the complete rat elastin gene: Analysis ofcis-acting elements involved in regulation of gene expression and alternative splicing and the role of repetitive sequences in gene instability

Elastin is the major component of elastic fibers which imparts the properties of extensibility and elastic recoil to tissues such as the nuchal ligament, aorta, lung and skin. The synthesis of this protein is subject to developmental and tissue-specific regulation. In addition several isoforms of tropoelastin, the insoluble precursor of elastin, have been identified and are believed to be the result of alternative splicing which is also controlled both developmentally and in a tissue-specific manner. We have isolated and characterized the rat tropoelastin gene to analyze putative cis-acting elements that may be involved in regulation of tropoelastin gene expression and alternative splicing.;We have screened two rat genomic libraries and isolated several overlapping recombinants that contained the entire rat elastin gene. These clones were subjected to extensive restriction and sequencing analyses. About 1 kbp of the rat tropoelastin promoter and the whole of intron 1 (about 8 kbp) were sequenced. Besides basic promoter elements and several transcription factor binding sites, an enhancer core sequence in the promoter and 4 enhancer core motifs in intron 1 were identified. In addition, the sequences of the promoter and intron 1 were studied to identify possible CpG islands. The roles different elements may play in developmental and tissue specific regulation of tropoelastin gene expression are discussed.;Exon-flanking sequences were analyzed. Comparison between alternatively spliced exons and exons that were not alternatively spliced showed that weak polypyrimidine tracts and branch point sequences may be involved in alternative splicing of exons 14 and 33. Stem-loop structures that form between exons 13 and 15 and their 5;Several repeat sequences were identified, and particularly in the 3...