A probable novel splicing isoform of human vascular endothelial growth factor

To characterize a new alternative splicing isoform of human vascular endothelial growth factor (VEGF) gene.

The total RNA was extracted from the lung tissue of a legally aborted 4-month-old fetus and amplified by RT-PCR. The amplified product was cloned into the plasmid pMD18-T and plasmid pcDNA3.1- for sequence analysis.

Electrophoresis of the RT-PCR products displayed one short band for VEGF(121) (487 bp) and a long band. The latter was characterized to contain two fragments: one was normal VEGF(165) (619 bp), and the other (639 bp) had an identical nucleotide sequence to VEGF(165) with a 20 bp fragment inserted between exons 3 and 4. Sequence analysis showed that this 20-bp nucleotide was inserted from the 3' end of the third intron containing a splicing signal, thus causing shift mutation in the reading frame of VEGF gene and early appearance of the stop codon UAG in the middle of exon 4.

A new alternative splicing isoform of VEGF probably exists in the lung tissue of a legally aborted human fetus, and its biological significance remains to be further investigated.