Two exonic elements in the flanking constitutive exons control the alternative splicing of the alpha exon of the ZO-1 pre-mRNA.
The 240-bp alpha exon of the tight junction (TJ) protein ZO-1 pre-mRNA is alternatively spliced. Expression of both ZO-1alpha+/ZO-1alpha- isoforms results in hermetic TJs, and these become leaky when ZO-1alpha- expression prevails. The alpha exon inclusion/skipping mechanism was studied by in vivo RT-PCR splicing assays in neural and epithelial cells, utilizing a canine minigene construct containing the alpha exon, and the flanking introns and exons. Inclusion of the alpha exon always occurs in wild-type MDCK cells and it is detectable in transfected HeLa cells. However, the alpha exon is skipped in transfected neural cells. Accordingly, both 5' and 3' splice sites surrounding the alpha exon appear to be suboptimal and no cis-acting splicing control elements were found in this exon. Deletion analysis revealed an 83-bp splicing enhancer in the downstream exon and a 35-bp splicing silencer at the beginning of the upstream exon. In epithelial cells all constructs rendered alpha exon inclusion. We conclude that, in neural cells, skipping of the alpha exon depends on two antagonistic exonic elements located in the flanking constitutive exons.
Martínez-Contreras
Rebeca
R
Departmento de Fisiología, Biofísica y Neurociencias, CINVESTAV-México, Apartado Postal 14-740, DF 07000, México.
Galindo
José Manuel
JM
Aguilar-Rojas
Arturo
A
Valdés
Jesús
J
D017398:Alternative Splicing; D000818:Animals; D004285:Dogs; D004848:Epithelium / Q000378:metabolism; D005091:Exons; D005786:Gene Expression Regulation; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
D008565:Membrane Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D012322:RNA Precursors; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein