Splice site strength-dependent activity and genetic buffering by poly-G runs.
Pre-mRNA splicing is regulated through the combinatorial activity of RNA motifs, including splice sites and splicing regulatory elements. Here we show that the activity of the G-run (polyguanine sequence) class of splicing enhancer elements is approximately 4-fold higher when adjacent to intermediate strength 5' splice sites (ss) than when adjacent to weak 5' ss, and approximately 1.3-fold higher relative to strong 5' ss. We observed this dependence on 5' ss strength in both splicing reporters and in global microarray and mRNA-Seq analyses of splicing changes following RNA interference against heterogeneous nuclear ribonucleoprotein (hnRNP) H, which cross-linked to G-runs adjacent to many regulated exons. An exon's responsiveness to changes in hnRNP H levels therefore depends in a complex way on G-run abundance and 5' ss strength. This pattern of activity enables G-runs and hnRNP H to buffer the effects of 5' ss mutations, augmenting both the frequency of 5' ss polymorphism and the evolution of new splicing patterns. Certain other splicing factors may function similarly.
Xiao
Xinshu
X
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Wang
Zefeng
Z
Jang
Minyoung
M
Nutiu
Razvan
R
Wang
Eric T
ET
Burge
Christopher B
CB
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000818:Animals; D003432:Cross-Linking Reagents / Q000378:metabolism; D005091:Exons; D005821:Genetic Techniques; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000378:metabolism; D006801:Humans; D051379:Mice; D008957:Models, Genetic; D020411:Oligonucleotide Array Sequence Analysis; D011068:Poly G / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism
D003432:Cross-Linking Reagents; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D012322:RNA Precursors; D012333:RNA, Messenger; D011068:Poly G