Novel fibroblast growth factor 2 transcripts are expressed in mouse embryos

We have discovered two new exons in the mouse fibroblast growth factor 2 (F GF-2 or bFGF) gene that can be alternatively spliced to the second coding e xon of the gene. The newly identified exons 1b and 1c are located at, respe ctively, approximately 19 and 32 kb downstream of the canonical exon 1a. Us ing RT-PCR analysis, mRNAs containing exon 1c and canonical exons 2 and 3 w ere identified in embryonic limb, placenta, face, carcass and ocular tissue s. A 3.7-kb transcript present in placenta and embryonic limb hybridizes wi th an exon 1c-derived probe in Northern blot analysis. Alternative splicing of exon 1c to exon 2 creates a transcript for which the predicted alternat ive FGF-2 (altFGF-2) polypeptide contains a novel N-terminal domain. Our da ta indicate that in mouse embryos multiple novel mRNA variants are transcri bed from the FGF-2 locus using alternative splicing. These data suggest tha t proteins arising from these alternative transcripts may play a role in mo use embryogenesis. (C) 2001 Academic Press.