The relative strengths of SR protein-mediated associations of alternative and constitutive exons can influence alternative splicing.
We have characterized the functional role of SR protein-mediated exon/exon associations in the alternative splicing of exon 5 of chicken cardiac troponin T (cTnT). We have previously shown that SR proteins can promote the association of the alternative exon 5 with the flanking constitutive exon 6 of this pre-mRNA. In this study, we have shown that when exons 2, 3, and 4 of the cTnT pre-mRNA are spliced together, the composite exon 2/3/4 contains an additional SR protein binding site. Furthermore, we have found that SR proteins can also promote interactions between the pairs of exons 2/3/4-5 and 2/3/4-6. We then asked whether the SR protein binding sites in these exons play a role in cTnT alternative splicing in vivo. We found that the SR protein binding sites in exons 2/3/4 and 6 promote exon 5 skipping, and it has previously been shown that the SR protein binding site in exon 5 promotes exon 5 inclusion. Consistent with these results, we find that the SR protein-mediated association of exon 2/3/4 with 6 is preferred over associations involving exon 5, in that exons 2/3/4 and 6 are more efficient than exon 5 in competing an SR protein-mediated exon/exon association. We suggest that the relative strengths of SR protein-mediated associations of alternative and constitutive exons play a role in determining alternative splicing patterns.
Stark
J M
JM
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104, USA.
Cooper
T A
TA
Roth
M B
MB
D017398:Alternative Splicing; D001483:Base Sequence; D005091:Exons; D011485:Protein Binding; D012313:RNA / Q000235:genetics; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*
D012322:RNA Precursors; D016601:RNA-Binding Proteins; D012313:RNA