THE FIBRONECTIN GENE AS A MODEL FOR SPLICING AND TRANSCRIPTION STUDIES

The fibronectin (FN) gene has become paradigmatic to illustrate genome evolution by exon shuffling, generation of protein diversity by alter native mRNA splicing, and topological coordination between transcripti on and splicing, Alternative splicing in three sites of the primary tr anscript gives rise to multiple FN polypeptides. This process is cell type-, development- and age-regulated, The different FN variants seem to play specific roles in FN dimer secretion, blood clotting, adhesion to lymphoid cells, skin wound healing, atherosclerosis, and liver fib rosis, This review focuses on function assignment to the alternatively spliced segments, as well as on the external signals and cis-acting s equences that control the mechanisms of alternative splicing, We also discuss FN transcriptional regulation in response to viral transformat ion, growth factors, and cyclic AMP in the light of promoter architect ure and its interaction with specific transcription factors, The relev ance of FN RNA ''tracks'' as assembly lines of coordinated transcripti on and RNA processing is also addressed.