Modulation in vitro of H-ras oncogene expression by trans-splicing.
In man, activated N-, K- and H-ras oncogenes have been found in around 30% of the solid tumours tested. An exon known as IDX, which has been described previously and is located between exon 3 and exon 4A of the c-H-ras pre-mRNA, allows an alternative splicing process that results in the synthesis of the mRNA of a putative protein named p19. It has been suggested that this alternative pathway is less tumorigenic than that which results in the activation of p21. We have used the mammalian trans-splicing mechanism as a tool with which to modulate this particular pre-mRNA processing to produce mRNA similar to that of mature p19 RNA. The E4A exon of the activated H-ras gene was found to be a good target for external trans-splicing. We reprogrammed the rat carnitine octanoyltransferase exon 2 to specifically invade the terminal region of H-ras. Assays performed with this reprogrammed trans-exon showed that the trans-splicing product was obtained in competition with cis-splicing of the D intron of the H-ras gene, and was associated with concomitant down-modulation of D intron cis-splicing. We also found that the exon 4A of the human c-H-ras gene underwent successive trans-splicing rounds with an external exon.
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IIBB-CSIC (Instituto de Investigaciones Biomédicas de Barcelona-Consejo Superior de Investigaciones Científicas), Dept. PMT, Unidad de Biología y Farmacología Molecular del Cáncer, c/Jorge Girona Salgado 18-26, 08034 Barcelona, Spain.
Guil
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Caudevilla
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Serra
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Asins
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Graessmann
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Hegardt
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Bach-Elias
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D000818:Animals; D004742:Enhancer Elements, Genetic; D005091:Exons; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D051381:Rats; D020040:Trans-Splicing