title: Two Novel Heparin-binding Vascular Endothelial Growth Factor Splices, L-VEGF144 and L-VEGF138, are Expressed in Human Glioblastoma Cells.
abstract: The expression levels of different vascular endothelial growth factor A (VEGF) isoforms are associated with the angiogenesis and the patient's prognoses in human cancers. Ribosomes specifically scan from 5' to 3' CUG initiation codon in the long 5'-untranslated region (5'-UTR) of the VEGF mRNA, resulting in the generation of high mol wt VEGF isoform [call large VEGF (L-VEGF)]. Alternative splicing of VEGF mRNA transcripts results in several isoforms with distinct properties that are dependent up their exon compositions. In this study, we observed two novel kinds of splicing VEGF isoforms that transcripted at the first upstream CUG codon, and which we have named large-VEGF144 (LVEGF144), and large-VEGF138 (L-VEGF138). The expression levels of messenger RNA for the different VEGF splice forms were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). After DNA sequencing, the genetic structure of L-VEGF144 involved not only a partial exon 1, exon 6a, and exons 7-8, but also an unique 108- nucleotides insertion of VEGF intron 5 interposed between exon 1 and exon 6. At the same time, L-VEGF144 lacked most of the Nterminal fragments (exons 1-5). We further found that a specific detection model could easily and rapidly confirm the presence of L-VEGF144 mRNA fragments in the biopsies or cell lines via RT-PCR assay. In addition, we used visible fluorescent fusion proteins to prove that both L-VEGF144 and L-VEGF138 have nuclear localization ability. Taken together, the findings of this study indicate that, unlike previously identified isoforms, these novel VEGF isoforms are likely to suggest a further level of complexity in the angiogenic process.
authors.affiliation: Department of Physical Therapy, Hung Kuang University, Taichung 43302, Taiwan; No. 160, Sec. 3 Taichung-Kang Rd., Taichung 407, Taiwan. ccshen61093@gmail.com.
authors.forename: Chiung-Chyi
authors.initials: CC
authors.lastname: Shen
authors.forename: Wen-Yu
authors.initials: WY
authors.lastname: Cheng
authors.forename: Ming-Tsang
authors.initials: MT
authors.lastname: Chiao
authors.forename: Yea-Jiuan
authors.initials: YJ
authors.lastname: Liang
authors.forename: Tsuo-Fei
authors.initials: TF
authors.lastname: Mao
authors.forename: Bai-Shuan
authors.initials: BS
authors.lastname: Liu
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D043925:Angiogenesis Inducing Agents / Q000378:metabolism*; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: D043925:Angiogenesis Inducing Agents; D020033:Protein Isoforms; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D006493:Heparin