Identification of a large region of secondary structure in the 3'-untranslated region of chicken elastin mRNA with implications for the regulation of mRNA stability.

Synthesis of aortic elastin peaks in the perinatal period and then is strongly down-regulated with postnatal vascular development. Our laboratory has previously shown that changes in elastin mRNA stability contribute to this developmental decrease in elastin production. Here we identify a large region of stable secondary structure in the 3'-untranslated region (3'-UTR) of chicken elastin mRNA. Reverse transcriptase polymerase chain reaction or polymerase chain reaction amplification of the 3'-UTR consistently resulted in products with an approximately 328-bp deletion from the central region of the 3'-UTR, suggesting the presence of secondary structure. The presence of this structure was confirmed by probing the 3'-UTR with RNases with selectivity for single- or double-stranded RNA. Gel migration shift assays using cytosolic extracts from 2-day old chicken aorta demonstrate specific binding of a cytosolic protein to riboprobes containing the 3'-UTR of elastin but not to riboprobes either corresponding to other areas of the message or containing the 3'-UTR but lacking the region of secondary structure. Binding of cytosolic protein was particularly prominent in aortic extracts from 2-day old chickens, a time when elastin message is stable, as compared with 8- and 15-week old chickens, when the elastin message is relatively unstable, suggesting that this region of secondary structure may play a role in developmental regulation of stability of elastin mRNA.