title: Genetic suppression of intronic +1G mutations by compensatory U1 snRNA changes in Caenorhabditis elegans.
abstract: Mutations to the canonical +1G of introns, which are commonly found in many human inherited disease alleles, invariably result in aberrant splicing. Here we report genetic findings in C. elegans that aberrant splicing due to +1G mutations can be suppressed by U1 snRNA mutations. An intronic +1G-to-U mutation, e936, in the C. elegans unc-73 gene causes aberrant splicing and loss of gene function. We previously showed that mutation of the sup-39 gene promotes splicing at the mutant splice donor in e936 mutants. We demonstrate here that sup-39 is a U1 snRNA gene; suppressor mutations in sup-39 are compensatory substitutions in the 5' end, which enhance recognition of the mutant splice donor. sup-6(st19) is an allele-specific suppressor of unc-13(e309), which contains an intronic +1G-to-A transition. The e309 mutation activates a cryptic splice site, and sup-6(st19) restores splicing to the mutant splice donor. sup-6 also encodes a U1 snRNA and the mutant contains a compensatory substitution at its 5' end. This is the first demonstration that U1 snRNAs can act to suppress the effects of mutations to the invariant +1G of introns. These findings are suggestive of a potential treatment of certain alleles of inherited human genetic diseases.
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz 95064, USA. zahler@biology.ucsc.edu
authors.forename: Alan M
authors.initials: AM
authors.lastname: Zahler
authors.forename: John D
authors.initials: JD
authors.lastname: Tuttle
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Chisholm
mesh_terms: D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D017238:Genes, Helminth; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013489:Suppression, Genetic
chemical_list: D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA