Affymetrix exon array analysis of control and hnRNP H knockdown in 293T cells

ABSTRACT: Splice site strength and the presence of splicing regulatory elements (SREs) play central roles in the control of pre-mRNA splicing1-3 and in exon evolution4. However, the degree to which SRE function is dependent or independent of the strength of nearby splice sites is not well understood. Here, we show that the activity of a major class of mammalian SREs is highly sensitive to the strength of the adjacent 5' splice site (5'ss) sequence, with important functional and evolutionary implications. Using extensive splicing reporter assays, we found that activity of identical 'G-run' intronic splicing enhancers (ISEs)5, 6 was higher by ~4-fold for 5'ss of intermediate strength relative to weak 5'ss, and higher by ~1.3-fold relative to strong 5'ss, based on established 5'ss scoring criteria7. This dependence on 5'ss strength was supported both by comparative genomic analyses and by high-throughput transcriptome sequencing analyses of splicing changes following RNAi against the G-run-binding factor heterogeneous nuclear ribonucleoprotein (hnRNP) H. This pattern and an inverse pattern of 5'ss-dependent activity observed for G-run exonic splicing silencers (ESSs) enables G-runs and hnRNP H to buffer 5'ss mutations and to function as effective evolutionary capacitors8 of splicing change. Human exons flanked by G-runs exhibited increased 5'ss polymorphism and a ~30% increased frequency of evolutionary change between constitutive and alternative splicing, supporting a role in facilitating splicing-level evolution. Evolutionary conservation indicated a substantially greater role for intronic elements generally in splicing of exons with weak and intermediate 5'ss, and supported 5'ss strength-dependent activity for several other intronic motifs, suggesting widespread functional and evolutionary differences between exons of differing 5'ss strength. Keywords: gene expression array-based, exon and protein coding gene analysis

ORGANISM(S): Homo sapiens

PROVIDER: GSE12386 | GEO | 2009/09/13

SECONDARY ACCESSION(S): PRJNA113135

REPOSITORIES: GEO