Cloning of multiple chicken FGF1 mRNAs and their differential expression during development of whole embryo and of the lens

Five different 5' untranslated regions (5' UTRs) of FGF1 mRNAs mere cloned in chicken, The structure of these transcripts suggests that, as in mammals, distinct 5' untranslated exons are spliced to the first coding exon via alternative splicing and alternative promoter usage, In an attempt to correlate the expression of specific transcripts to distinct biological activities, the distribution of these transcripts in different tissues and during the development of both the whole embryo and the lens was studied, In tissues, we have shown a differential, but not exclusive, expression of these transcripts, In the whole embryo, the expression of one transcript correlates with later developmental processes, In the lens, only two transcripts were detected that are both differently expressed and distributed, These results suggest that the biological properties of FGF1 depend on the expression of specific FGF1 mRNAs, Because these transcripts only differ in their 5' UTRs, they could be involved in distinct translational controls.