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  • Disruption of exon-bridging interactions between the minor and major spliceosomes results in alternative splicing around minor introns.

Disruption of exon-bridging interactions between the minor and major spliceosomes results in alternative splicing around minor introns.

Nucleic acids research (2021-03-05)
Anouk M Olthof, Alisa K White, Stephen Mieruszynski, Karen Doggett, Madisen F Lee, Almahdi Chakroun, Alice K Abdel Aleem, Justine Rousseau, Cinzia Magnani, Chaim M Roifman, Philippe M Campeau, Joan K Heath, Rahul N Kanadia
ABSTRACT

Vertebrate genomes contain major (>99.5%) and minor (<0.5%) introns that are spliced by the major and minor spliceosomes, respectively. Major intron splicing follows the exon-definition model, whereby major spliceosome components first assemble across exons. However, since most genes with minor introns predominately consist of major introns, formation of exon-definition complexes in these genes would require interaction between the major and minor spliceosomes. Here, we report that minor spliceosome protein U11-59K binds to the major spliceosome U2AF complex, thereby supporting a model in which the minor spliceosome interacts with the major spliceosome across an exon to regulate the splicing of minor introns. Inhibition of minor spliceosome snRNAs and U11-59K disrupted exon-bridging interactions, leading to exon skipping by the major spliceosome. The resulting aberrant isoforms contained a premature stop codon, yet were not subjected to nonsense-mediated decay, but rather bound to polysomes. Importantly, we detected elevated levels of these alternatively spliced transcripts in individuals with minor spliceosome-related diseases such as Roifman syndrome, Lowry-Wood syndrome and early-onset cerebellar ataxia. In all, we report that the minor spliceosome informs splicing by the major spliceosome through exon-definition interactions and show that minor spliceosome inhibition results in aberrant alternative splicing in disease.

MATERIALS
Product Number
Brand
Product Description

Roche
cOmplete, Mini, EDTA-free Protease Inhibitor Cocktail, Protease Inhibitor Cocktail Tablets provided in a glass vial, Tablets provided in a glass vial
Sigma-Aldrich
Anti-SNRNP40 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution