Exon skipping of exonuclease 1 in MRL/MpJ mice is caused by a nucleotide substitution of the branchpoint sequence in intron eight
2004
Namiki, Y. (Hokkaido Univ., Sapporo (Japan)) | Kon, Y. | Sasaki, N. | Agui, T. | Endoh, D.
In MRJ/MpJ mice, there is a genetic mutation of exonuclease 1 (Exol), in which the exon 9 is sometimes deleted. In the present study, to check the gen-eration of the spliced exons, exon 8-intron 8-exon 9 (pCX/Ex/EIE/B and pCX/ Ex/EIE/M) plasmids were temporally transfected in vitro into BALB 3T3 cells, and RT-PCR using appropriate primer pair was carried out 1 day after transfection. In these constructions, pCX/Ex/EIE/B was derived from genomic sequence of C57BL/6 mice, and pCX/Ex/EIE/M was from MRL/MpJ. A spliced band was detected in pCX/Ex/EIE/B , but was present little or very weakly in pCX/Ex/EIE/M . Next, the same spliced band was demonstrated in pCX/Ex/EIE/M(T) plasmid, in which the branchpoint sequence (BPS) of pCX/Ex/EIE/M including the exon 9 was changed into that of pCX/Ex/EIE/B. The splicing did not occur in the del1/B mutant, in which 1960 nucleotides of the intron 8 were deleted, whereas it was detected in the del2/B plasmid deleted 1036 nucleotides in its middle region. These results suggest that the nucleotide T to A mutation of the BPS in the intron 8 is at least a sufficient for generation of splice variants (tr-l and tr-2 Exol).
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