title: RNA-Sequencing data supports the existence of novel VEGFA splicing events but not of VEGFAxxxb isoforms.
abstract: Vascular endothelial growth factor (VEGFA), a pivotal regulator of angiogenesis and valuable therapeutic target, is characterised by alternative splicing which generates three principal isoforms, VEGFA121, VEGFA165and VEGFA189. A second set of anti-angiogenic isoforms termed VEGFAxxxb that utilise an alternative splice site in the final exon have been widely reported, with mRNA detection based principally upon RT-PCR assays. We sought confirmation of the existence of the VEGFAxxxb isoforms within the abundant RNA sequencing data available publicly. Whilst sequences derived specifically from each of the canonical VEGFA isoforms were present in many tissues, there were no sequences derived from VEGFAxxxb isoforms. Sequencing of approximately 50,000 RT-PCR products spanning the exon 7-8 junction in 10 tissues did not identify any VEGFAxxxb transcripts. The absence or extremely low expression of these transcripts in vivo indicates that VEGFAxxxb isoforms are unlikely to play a role in normal physiology. Our analyses also revealed multiple novel splicing events supported by more reads than previously reported for VEGFA145and VEGFA148isoforms, including three from novel first exons consistent with existing transcription start site data. These novel VEGFA isoforms may play significant roles in specific cell types.
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, UK.
authors.forename: Stephen
authors.identifier: 0000-0001-9330-5820
authors.initials: S
authors.lastname: Bridgett
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Dellett
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, UK. David.Simpson@qub.ac.uk.
authors.forename: David A
authors.identifier: 0000-0003-0157-1211
authors.initials: DA
authors.lastname: Simpson
mesh_terms: D017398:Alternative Splicing; D057809:HEK293 Cells; D006801:Humans; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; D042461:Vascular Endothelial Growth Factor A