| 1. |
- Aspock, G, et al.
(författare)
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The Caenorhabditis elegans ems class homeobox gene ceh-2 is required for M3 pharynx motoneuron function
- 2003
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 130:15, s. 3369-3378
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Tidskriftsartikel (refereegranskat)abstract
- Several homeobox genes, for example those of the ems class, play important roles in animal head development. We report on the expression pattern and function of ceh-2, the Caenorhabditis elegans ems/Emx ortholog. CEH-2 protein is restricted to the nuclei of one type of small muscle cell, one type of epithelial cell, and three types of neurons in the anterior pharynx in the head. We have generated a deletion allele of ceh-2 that removes the homeobox. Animals homozygous for this deletion are viable and fertile, but grow slightly slower and lay fewer eggs than wild type. We assayed the function of two types of pharynx neurons that express ceh-2, the pairs M3 and NSM. M3 activity is substantially reduced in electropharyngeograms of ceh-2 deletion mutants; this defect can account for the observed retardation in larval development, as M3 activity is known to be necessary for effective feeding. NSM function and metabolism are normal based on the assays used. All cells that express ceh-2 in wild type are present in the ceh-2mutant and have normal morphologies. Therefore, unlike other ems/Emxgenes, ceh-2 seems to be important for a late differentiation step and not for neuron specification or regional patterning. Because the CEH-2 homeodomain is well conserved, we tested whether ceh-2 can rescue ems- brain defects in Drosophila, despite the apparent differences in biological roles. We found that the C. elegans ems ortholog is able to substitute for fly ems in brain development, indicating that sequence conservation rather than conservation of biological function is important.
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| 2. |
- Efimenko, Evgeni, et al.
(författare)
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Analysis of xbx genes in C-elegans
- 2005
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Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 132:8, s. 1923-1934
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Tidskriftsartikel (refereegranskat)abstract
- Cilia and flagella are widespread eukaryotic subcellular components that are conserved from green algae to mammals. In different organisms they function in cell motility, movement of extracellular fluids and sensory reception. While the function and structural description of cilia and flagella are well established, there are many questions that remain unanswered. In particular, very little is known about the developmental mechanisms by which cilia are generated and shaped and how their components are assembled into functional machineries. To find genes involved in cilia development we used as a search tool a promoter motif, the X-box, which participates in the regulation of certain ciliary genes in the nematode Caenorhabditis elegans. By using a genome search approach for X-box promoter motif-containing genes (xbx genes) we identified a list of about 750 xbx genes (candidates). This list comprises some already known ciliary genes as well as new genes, many of which we hypothesize to be important for cilium structure and function. We derived a C elegans X-box consensus sequence by in vivo expression analysis. We found that xbx gene expression patterns were dependent on particular X-box nucleotide compositions and the distance from the respective gene start. We propose a model where DAF-19, the RFX-type transcription factor binding to the X-box, is responsible for the development of a ciliary module in C elegans, which includes genes for cilium structure, transport machinery, receptors and other factors.
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| 3. |
- Lin, XX, et al.
(författare)
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DAF-16/FOXO and HLH-30/TFEB function as combinatorial transcription factors to promote stress resistance and longevity
- 2018
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1, s. 4400-
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Tidskriftsartikel (refereegranskat)abstract
- The ability to perceive and respond to harmful conditions is crucial for the survival of any organism. The transcription factor DAF-16/FOXO is central to these responses, relaying distress signals into the expression of stress resistance and longevity promoting genes. However, its sufficiency in fulfilling this complex task has remained unclear. Using C. elegans, we show that DAF-16 does not function alone but as part of a transcriptional regulatory module, together with the transcription factor HLH-30/TFEB. Under harmful conditions, both transcription factors translocate into the nucleus, where they often form a complex, co-occupy target promoters, and co-regulate many target genes. Interestingly though, their synergy is stimulus-dependent: They rely on each other, functioning in the same pathway, to promote longevity or resistance to oxidative stress, but they elicit heat stress responses independently, and they even oppose each other during dauer formation. We propose that this module of DAF-16 and HLH-30 acts by combinatorial gene regulation to relay distress signals into the expression of specific target gene sets, ensuring optimal survival under each given threat.
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