Expression of alternatively spliced FGF-2 antisense RNA transcripts in the central nervous system: regulation of FGF-2 mRNA translation.
The fibroblast growth factor-2 (FGF-2) gene is bidirectionally transcribed to produce the FGF-2 mRNA and a 1.5 kb antisense (FGF-AS) transcript complementary to the 3' untranslated region of the FGF-2 transcript. The FGF-AS RNA has been postulated to play a role in the post-transcriptional regulation of FGF-2, but this function has not been conclusively demonstrated. We characterized FGF-AS cDNAs from rat brain and C6 glioma cells, and investigated their role in regulation of FGF-2 expression. Three FGF-AS cDNAs were isolated; the full-length FGF-AS mRNA and two alternative splice variants lacking exon 2 or exons 2 and 3 of the FGF-AS sequence. The alternatively spliced FGF-AS RNAs are widely expressed in the CNS, whereas liver predominantly expressed the full-length transcript. The full-length and first splice variant encode 35 and 28 kDa isoforms of GFG, a MutT-related nuclear protein, whereas the second splice variant was not translated. The effect of FGF-AS RNA on FGF-2 expression was evaluated in stable C6 transfectants over-expressing the full-length or alternatively spliced FGF-AS RNA forms. All three constructs suppressed cellular FGF-2 protein (but not FGF-2 mRNA) levels, and this effect correlated directly with the level of FGF-AS RNA. Cellular FGF receptor content was increased and cell proliferation inhibited compared to wild type or vector-transfected cells, indicating disruption of the FGF-2 autocrine pathway by FGF-AS RNA. These findings demonstrate for the first time that the FGF-AS RNA regulates FGF-2 expression in mammalian cells, and suggest that this effect is exerted predominantly at the level of translation.
Li
A W
AW
Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, 5859 University Avenue, NS, Halifax, Canada B3H 4H7.
Murphy
P R
PR
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002455:Cell Division; D002490:Central Nervous System / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D016222:Fibroblast Growth Factor 2 / Q000235:genetics*; D005910:Glioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D016372:RNA, Antisense / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D018076:DNA, Complementary; D016372:RNA, Antisense; D016222:Fibroblast Growth Factor 2