title: A splice acceptor mutation in C. elegans daf-19/Rfx disrupts functional specialization of male-specific ciliated neurons but does not affect ciliogenesis.
abstract: RFX transcription factors are master regulators of ciliogenesis in diverse animal species. The sole Caenorhabditis elegans RFX homolog, DAF-19, plays at least two roles in the formation of functional cilia. The DAF-19(C) isoform is required for ciliogenesis and the DAF-19(M) isoform is required for the functional specialization of a subset of male-specific ciliated neurons called PKD neurons. Here we report the identification of a novel mutation, daf-19(sm129), which disrupts the functional specification of PKD neurons and thus suggests that daf-19m activity is compromised. However, ciliogenesis is not disrupted in daf-19(sm129) mutants suggesting that daf-19c activity is retained. The sm129 mutation disrupts a splice acceptor site adjacent to an exon common to the daf-19c and daf-19m isoforms resulting in aberrant splicing in a proportion of transcripts. While aberrant splicing of daf-19c to upstream cryptic sites results in in-frame and functional products, a large proportion of daf-19m mRNAs include the entire upstream intron, which introduces a frameshift and stop codons. At least 15% of disease-causing mutations affect splicing of the gene bearing the mutation, thus it is important to understand the consequences of splice site mutations on gene function. However, predicting the effects of a splice site mutation remains difficult and experimental determination is still required. Using daf-19(sm129) as a model, our results suggest that this problem is exacerbated when a splice acceptor mutation is used by multiple isoforms of the same gene because the effects on each isoform can be dramatically different.
authors: Colorado College, Department of Molecular Biology, Colorado Springs, CO 80903, United States.
authors: Kristen L
authors: KL
authors: Wells
authors: The College of New Jersey, Department of Biology, Ewing, NJ 08628, United States.
authors: Mazhgan
authors: M
authors: Rowneki
authors: Colorado College, Department of Molecular Biology, Colorado Springs, CO 80903, United States. Electronic address: darrell.killian@coloradocollege.edu.
authors: Darrell J
authors: DJ
authors: Killian
mesh_terms: D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D002923:Cilia / Q000502:physiology; D004252:DNA Mutational Analysis; D008297:Male; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009474:Neurons / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D022821:RNA Splice Sites; D012326:RNA Splicing; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; C410596:DAF-19 protein, C elegans; D020033:Protein Isoforms; D022821:RNA Splice Sites; D014157:Transcription Factors
keywords: C. elegans; Cilia; Ciliogenesis; Splicing; daf-19