Biomedical subjects

Jocelyn E Shaw

Publications and source records attributed to Jocelyn E Shaw.

4 recordsLinked to original sources

PubMed2006

The molecular identities of the Caenorhabditis elegans intraflagellar transport genes dyf-6, daf-10 and osm-1.

The Caenorhabditis elegans genes dyf-6, daf-10, and osm-1 are among the set of genes that affect chemotaxis and the ability of certain sensory neurons to take up fluorescent dyes from the environment. Some genes in this category are known to be required for intraflagellar transport (IFT), which is the bidirectional movement of raft-like particles along the axonemes of cilia and flagella. The cloning of dyf-6, daf-10, and osm-1 are described here. The daf-10 and osm-1 gene products resemble each other and contain WD and WAA repeats. DYF-6, the product of a complex locus, lacks known motifs, but orthologs are present in flies and mammals. Phenotypic analysis of dyf-6 mutants expressing an OSM-6::GFP reporter indicates that the cilia of the amphid and phasmid dendritic endings are foreshortened. Consistent with genetic mosaic analysis, which indicates that dyf-6 functions in neurons of the amphid sensilla, DYF-6::GFP is expressed in amphid and phasmid neurons. Movement of DYF-6::GFP within the ciliated endings of the neurons indicates that DYF-6 is involved in IFT. In addition, IFT can be observed in dauer larvae.

Amino Acid Sequence↗

PubMed2004

SMU-2 and SMU-1, Caenorhabditis elegans homologs of mammalian spliceosome-associated proteins RED and fSAP57, work together to affect splice site choice.

Mutations in the Caenorhabditis elegans gene smu-2 suppress mec-8 and unc-52 mutations. It has been proposed that MEC-8 regulates the alternative splicing of unc-52 transcripts, which encode the core protein of perlecan, a basement membrane proteoglycan. We show that mutation in smu-2 leads to enhanced accumulation of transcripts that skip exon 17, but not exon 18, of unc-52, which explains our finding that smu-2 mutations suppress the uncoordination conferred by nonsense mutations in exon 17, but not in exon 18, of unc-52. We conclude that smu-2 encodes a ubiquitously expressed nuclear protein that is 40% identical to the human RED protein, a component of purified spliceosomes. The effects of smu-2 mutation on both unc-52 pre-mRNA splicing and the suppression of mec-8 and unc-52 mutant phenotypes are indistinguishable from the effects of mutation in smu-1, a gene that encodes a protein that is 62% identical to human spliceosome-associated protein fSAP57. We provide evidence that SMU-2 protects SMU-1 from degradation in vivo. In vitro and in vivo coimmunoprecipitation experiments indicate that SMU-2 and SMU-1 bind to each other. We propose that SMU-2 and SMU-1 function together to regulate splice site choice in the pre-mRNAs of unc-52 and other genes.

Alternative Splicing↗

PubMed2003

The Caenorhabditis elegans innexin INX-3 is localized to gap junctions and is essential for embryonic development.

Innexins are the proposed structural components of gap junctions in invertebrates. Antibodies that specifically recognize the Caenorhabditis elegans innexin protein INX-3 were generated and used to examine the patterns of inx-3 gene expression and the subcellular sites of INX-3 localization. INX-3 is first detected in two-cell embryos, concentrated at the intercellular interface, and is expressed ubiquitously throughout the cellular proliferation phase of embryogenesis. During embryonic morphogenesis, INX-3 expression becomes more restricted. Postembryonically, INX-3 is expressed transiently in several cell types, while expression in the posterior pharynx persists throughout development. Through immuno-EM techniques, INX-3 was observed at gap junctions in the adult pharynx, providing supporting evidence that innexins are components of gap junctions. An inx-3 mutant was isolated through a combined genetic and immunocytochemical screen. Homozygous inx-3 mutants exhibit defects during embryonic morphogenesis. At the comma stage of early morphogenesis, variable numbers of cells are lost from the anterior of inx-3(lw68) mutants. A range of terminal defects is seen later in embryogenesis, including localized rupture of the hypodermis, failure of the midbody to elongate properly, abnormal contacts between hypodermal cells, and failure of the pharynx to attach to the anterior of the animal.

Animals↗

PubMed2002

MEC-8 regulates alternative splicing of unc-52 transcripts in C. elegans hypodermal cells.

Previous work has shown that C. elegans MEC-8 is a putative RNA-binding protein that promotes specific alternative splices of unc-52 transcripts. unc-52 encodes homologs of mammalian perlecan that are located extracellularly between muscle and hypodermis and are essential for muscle development in both embryos and larvae. We show that MEC-8 is a nuclear protein found in hypodermis at most stages of development and not in most late embryonic or larval body-wall muscle. We have also found that overexpression of MEC-8 in hypodermis but not muscle can suppress certain unc-52 mutant phenotypes. These are unexpected results because it has been proposed that UNC-52 is produced exclusively by muscle. We have constructed various tissue-specific unc-52 minigenes fused to a gene for green fluorescent protein that have allowed us to monitor tissue-specific mec-8-dependent alternative splicing; we show that mec-8 must be expressed in the same cell type as the unc-52 minigene in order to regulate its expression, supporting the view that MEC-8 acts directly on unc-52 transcripts and that UNC-52 must be synthesized primarily by the hypodermis. Indeed, our analysis of unc-52 genetic mosaics has shown that the focus of unc-52 action is not in body-wall muscle but most likely is in hypodermis.

Alternative Splicing↗