title: Transcriptome analyses of the human retina identify unprecedented transcript diversity and 3.5 Mb of novel transcribed sequence via significant alternative splicing and novel genes.
abstract: BACKGROUND
  The retina is a complex tissue comprised of multiple cell types that is affected by a diverse set of diseases that are important causes of vision loss. Characterizing the transcripts, both annotated and novel, that are expressed in a given tissue has become vital for understanding the mechanisms underlying the pathology of disease.
  
  
  RESULTS
  We sequenced RNA prepared from three normal human retinas and characterized the retinal transcriptome at an unprecedented level due to the increased depth of sampling provided by the RNA-seq approach. We used a non-redundant reference transcriptome from all of the empirically-determined human reference tracks to identify annotated and novel sequences expressed in the retina. We detected 79,915 novel alternative splicing events, including 29,887 novel exons, 21,757 3' and 5' alternate splice sites, and 28,271 exon skipping events. We also identified 116 potential novel genes. These data represent a significant addition to the annotated human transcriptome. For example, the novel exons detected increase the number of identified exons by 3%. Using a high-throughput RNA capture approach to validate 14,696 of these novel transcriptome features we found that 99% of the putative novel events can be reproducibly detected. Further, 15-36% of the novel splicing events maintain an open reading frame, suggesting they produce novel protein products.
  
  
  CONCLUSIONS
  To our knowledge, this is the first application of RNA capture to perform large-scale validation of novel transcriptome features. In total, these analyses provide extensive detail about a previously uncharacterized level of transcript diversity in the human retina.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Farkas
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Grant
authors.forename: Joseph A
authors.initials: JA
authors.lastname: White
authors.forename: Maria E
authors.initials: ME
authors.lastname: Sousa
authors.forename: Mark B
authors.initials: MB
authors.lastname: Consugar
authors.affiliation: Ocular Genomics Institute, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA. eric_pierce@meei.harvard.edu.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Pierce
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D019295:Computational Biology / Q000379:methods; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D056726:Genetic Association Studies; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D058977:Molecular Sequence Annotation; D009363:Neoplasm Proteins / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D059368:RNA Isoforms; D015203:Reproducibility of Results; D012160:Retina / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D004268:DNA-Binding Proteins; C120898:KMT2D protein, human; D009363:Neoplasm Proteins; D059368:RNA Isoforms