Novel exonic elements that modulate splicing of the human fibronectin EDA exon.
Three exons in the fibronectin primary transcript are alternatively spliced in a tissue- and developmental stage-specific manner. One of these exons, EDA, has been shown previously by others to contain two splicing regulatory elements between 155 and 180 nucleotides downstream of the 3'-splice site: an exon splicing enhancer and a negative element. By transient expression of a chimeric beta-globin/fibronectin EDA intron in COS-7 cells, we have identified two additional exonic splicing regulatory elements. RNA generated by a construct containing the first 120 nucleotides of the fibronectin EDA exon was spliced with an efficiency of approximately 50%. Deletion of most of the fibronectin EDA exon sequences resulted in a 20-fold increase in the amount of spliced RNA, indicative of an exon splicing silencer. Deletion and mutagenesis studies suggest that the fibronectin exon splicing silencer is associated with a conserved RNA secondary structure. In addition, sequences between nucleotides 93 and 118 of the EDA exon contain a non-purine-rich splicing enhancer as demonstrated by its ability to function in a heterologous context.
Staffa
A
A
Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada.
Acheson
N H
NH
Cochrane
A
A
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D005091:Exons; D005353:Fibronectins / Q000235:genetics*; D005914:Globins / Q000235:genetics; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017433:Protein Structure, Secondary
D005353:Fibronectins; D005914:Globins