Abstract
Comparison of human and mouse genomics revealed a similar long range sequences organization, and many genes that are orthologous between human and mouse. Alternative splicing is a very important post-transcriptional event leading to an increase in the transcriptome diversity. Recently, genomics studies estimate that 40-60% of human genes undergo alternative splicing. It is interesting to appraise the level of conservation of alternative splicing. To address this question, we developed a bioinformatics method to identify alternative splicing events that are conserved and alternative splicing events that are not conserved between human and mouse. Here we report an analysis of 3,613 orthologous genes in human and mouse, which discover 2,628 alternative splicing events are conserved in both transcriptome and 2,783 alternative splicing events are not conserved. Further classification of these conserved alternative splicing events reveals that 239 events are due to exon skipping, 34 events are due to mutually exclusive, 1,540 events are due to 3′ splice sites, 815 events are due to 5′ splice sites, and no events are due to intron retention. By comparison, non-conserved alternative splicing events reveals that 609 events are due to exon skipping, 47 events are due to mutually exclusive, 1,048 events are due to 3′ splice sites, 960 events are due to 5′ splice sites, and 370 events are due to intron retention. We combined with the human exons and mouse exons to discover the cross-species alternative splicing events. The cross-species alternative splicing event means that in orthologous genes, there is no alternative splicing event in both species and their splicing forms are distinct. We discovered 235 such events.