Journal Article

Functional Analysis of <i>cis</i>-Acting Elements Regulating the Alternative Splicing of Human CFTR Exon 9

Martina Niksic, Maurizio Romano, Emanuele Buratti, Franco Pagani and Francisco E. Baralle

in Human Molecular Genetics

Volume 8, issue 13, pages 2339-2349
Published in print December 1999 | ISSN: 0964-6906
Published online December 1999 | e-ISSN: 1460-2083 | DOI:
Functional Analysis of cis-Acting Elements Regulating the Alternative Splicing of Human CFTR Exon 9

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The rate of exon 9 exclusion from the cystic fibrosis transmembrane conductance regulator (CFTR) mRNA is associated with monosymptomatic forms of cystic fibrosis. Exon 9 alternative splicing is modulated by a polymorphic polythymidine tract within its 3′ splice site. We have generated a minigene carrying human CFTR exon 9 with its flanking intronic sequences and set up an invivo model to study the cis-acting DNA elements which modulate its splicing. Transfections into human cell lines showed that T5, but not T9 or T7 alleles, significantly increases the alternative splicing of exon 9. Moreover, we found that another polymorphic locus juxtaposed upstream of the T tract, and constituted by (TG)n repeats, can further modulate exon 9 skipping but only when activated by the T5 allele. Then, we extended our studies to the mouse CFTR exon 9 which does not show alternative splicing. Comparison of human and mouse introns 8 and 9 revealed a low homology between the two sequences and the absence of the human polymorphic loci within the mouse intron 3′ splice site. We have tested a series of constructs where the whole human exon 9 with its flanking intronic sequences was replaced partially or completely by the murine counterpart. The transfections of these constructs in human and murine cell lines reveal that also sequences of the downstream intron 9 affect exon 9 definition and co-modulate, with the UG/U 3′ splice site sequences, the extent of exon 9 skipping in CFTR mRNA.

Journal Article.  6332 words.  Illustrated.

Subjects: Genetics and Genomics

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