Amom, Prativa et al. (2021) International Worm Meeting "Cell fate plays critical roles in promoting collective cell movements in C. elegans gastrulation and ventral cleft closure during embryogenesis"

Sesterhenn, Thomas M., Anderson, Breana D., Amom, Prativa, Ganjawala, Tushar H., Hanson, Jorin T., Zacharias, Amanda L.

[International Worm Meeting, 2021]

Wnt signaling can promote cell fate decisions and collective cell movements through distinct mechanisms. In C. elegans embryogenesis, Wnt acts primarily through the Wnt/beta-catenin asymmetry pathway, which is known to regulate cell fate decisions, but it is unclear how this pathway impacts collective cell movements. We examined a cGAL Wnt mis-expression mutant by time-lapse fluorescent microscopy and found that left-right axis rotation, gastrulation, and ventral cleft closure were disrupted. To determine whether these defects were due to a direct regulation of collective cell movements by Wnt or an indirect disruption of cell fates, we examined embryonic cell movements in fate mutants for five major cell types using a time-lapse imaging approach with automated lineage reconstruction. We were able to recapitulate previously described disruptions to gastrulation in end-1/end-3 intestinal fate mutants, and also observed defects in ventral cleft closure. In hlh-1/unc-120 muscle fate mutants, we observed that the putative muscle cells underwent gastrulation normally, but the embryos had an extrinsic defect in ventral cleft closure. In nhr-25 or elt-1 hypodermal fate mutants, we observed that the putative hypodermal cells adopted the correct positions on the dorsal side of the embryo, but on the ventral side, some mesodermal cells failed to complete gastrulation and ventral cleft closure failed. In cnd-1/ngn-1/lin-32 neuronal fate mutant embryos, we observed failure in ventral cleft closure by the presumptive neuroblasts. In pha-4 pharynx fate mutants, we observed that some of the putative pharyngeal cells failed to undergo gastrulation by the end of comma stage. Taken together, these finding indicate that cell fate plays key roles in regulating gastrulation and ventral cleft closure, but not left-right axis rotation, indicating that this collective cell movement could be directly regulated by Wnt signaling. We found that ventral cleft closure is a complex process that depends on intestine, muscle, hypodermal, and neuronal fates, possibly through the regulation of juxtacrine signaling, cell adhesion, or extracellular matrix remodeling by the muscle and intestinal cells and long-range signaling from the hypodermal cells. Our results also indicate that mesodermal gastrulation is also dependent on long range signals from the hypodermal cells. Thus, our results identify two novel roles for the hypodermis in organizing the early embryo prior to ventral enclosure and highlight novel intrinsic and extrinsic roles for cell fate regulators in collective cell movements.

Samuel ADT et al. (2003) J Neurosci "Synaptic activity of the AFD neuron in Caenorhabditis elegans correlates with thermotactic memory."

Murthy VN, Samuel ADT, Silva RA

[J Neurosci, 2003]

Thermotactic behavior in Caenorhabditis elegans is sensitive to both a worm's ambient temperature (T-amb) and its memory of the temperature of its cultivation (T-cult). The AFD neuron is part of a neural circuit that underlies thermotactic behavior. By monitoring the fluorescence of pH-sensitive green fluorescent protein localized to synaptic vesicles, we measured the rate of the synaptic release of AFD in worms cultivated at temperatures between 15 and 25degreesC, and subjected to fixed, ambient temperatures in the same range. We found that the rate of AFD synaptic release is high if either T-amb > T-cult or T-amb > T-cult, but AFD synaptic release is low if T-amb congruent to T-cult. This suggests that AFD encodes a direct comparison between T-amb and T-cult.

Bommireddy R et al. (2007) Trends Mol Med "TGFbeta1 and Treg cells: alliance for tolerance."

Bommireddy R, Doetschman T

[Trends Mol Med, 2007]

Transforming growth factor beta1 (TGFbeta1), an important pleiotropic, immunoregulatory cytokine, uses distinct signaling mechanisms in lymphocytes to affect T-cell homeostasis, regulatory T (T(reg))-cell and effector-cell function and tumorigenesis. Defects in TGFbeta1 expression or its signaling in T cells correlate with the onset of several autoimmune diseases. TGFbeta1 prevents abnormal T-cell activation through the modulation of Ca(2+)-calcineurin signaling in a Caenorhabditis elegans Sma and Drosophila Mad proteins (SMAD)3 and SMAD4-independent manner; however, in T(reg) cells, its effects are mediated, at least in part, through SMAD signaling. TGFbeta1 also acts as a pro-inflammatory cytokine and induces interleukin (IL)-17-producing pathogenic T-helper cells (T(h) IL-17 cells) synergistically during an inflammatory response in which IL-6 is produced. Here, we will review TGFbeta1 and its signaling in T cells with an emphasis on the regulatory arm of immune tolerance.

Agulnik SI et al. (1995) Genomics "Conservation of the T-box gene family from Mus musculus to Caenorhabditis elegans."

Bollag RJ, Silver LM, Agulnik SI

[Genomics, 1995]

Recently, a novel family of genes with a region of homology to the mouse T locus, which is known to play a crucial, and conserved, role in vertebrate development, has been discovered. The region of homology has been named the T-box. The T-box domain of the prototypical T locus product is associated with sequence-specific DNA binding activity. In this report, we have characterized four members of the T-box gene family from the nematode Caenorhabditis elegans. All lie in close proximity to each other in the middle of chromosome III. Homology analysis among all completely sequenced T-box products indicates a larger size for the conserved T-box domain (166 to 203 residues) than previously reported. Phylogenetic analysis suggests that one C. elegans T-box gene may be a direct ortholog of the mouse Tbx2 and Drosophila omb genes. The accumulated data demonstrate the ancient nature of the T-box gene family and suggest the existence of at least three separate T-box-containing genes in a common early metazoan ancestor to nematodes and vertebrates.

Ju T et al. (2006) Glycobiology "Identification of core 1 O-glycan T-synthase from Caenorhabditis elegans."

Ju T, Zheng Q, Cummings RD

[Glycobiology, 2006]

The common O-glycan core structure in animal glycoproteins is the core 1 disaccharide Galbeta1-3GalNAcalpha1-Ser/Thr, which is generated by addition of Gal to GalNAcalpha1-Ser/Thr by core 1 UDP-Gal:GalNAcalpha1-Ser/Thr beta1,3-galactosyltransferase (core 1 beta3-Gal-T or T-synthase, EC2.4.1.122)(2). Although O-glycans play important roles in vertebrates, much remains to be learned from model organisms such as the free-living nematode Caenorhabditis elegans, which offer many advantages in exploring O-glycan structure/function. Here we report the cloning and enzymatic characterization of T-synthase from C. elegans (Ce-T-synthase). A putative C. elegans gene for T-synthase, C38H2.2, was identified in GenBank by a BlastP search using the human T-synthase protein sequence. The full-length cDNA for Ce-T-synthase, which was generated by PCR using a C. elegans cDNA library as the template, contains 1,170 bp including the stop TAA. The cDNA encodes a protein of 389 amino acids with typical type-II membrane topology and a remarkable 42.7% identity to the human T-synthase. Ce-T-synthase has 7 Cys residues in the lumenal domain including 6 conserved Cys residues in all of the orthologs. The Ce-T-synthase has 4 potential N-glycosylation sequons, whereas the mammalian orthologs lack N-glycosylation sequons. Only one gene for Ce-T-synthase was identified in the genome-wide search and it contains 8 exons. Promoter analysis of the Ce-T-synthase using green fluorescent protein constructs show that the gene is expressed at all developmental stages and appears to be in all cells. Unexpectedly, only minimal activity was recovered in the recombinant, soluble Ce-T-synthase secreted from a wide variety of mammalian cell lines, whereas robust enzyme activity was recovered in the soluble Ce-T-synthase expressed in Hi-5 insect cells. Vertebrate T-synthase requires the molecular chaperone Cosmc, but our results show that Ce-T-synthase does not require Cosmc, and might require invertebrate-specific factors for formation of the optimally active enzyme. These results show that the Ce-T-synthase is a functional ortholog to the human T-synthase in generating core 1 O-glycans and opens new avenues to explore O-glycan function in this model organism.

Muir RE et al. (2007) Int J Syst Evol Microbiol "Leucobacter chromiireducens subsp. solipictus subsp. nov., a pigmented bacterium isolated from the nematode Caenorhabditis elegans, and emended description of L. chromiireducens."

Muir RE, Tan MW

[Int J Syst Evol Microbiol, 2007]

A yellow-pigmented, Gram-positive, aerobic, non-motile, non-spore-forming, irregular rod-shaped bacterium (strain TAN 31504(T)) was isolated from the bacteriophagous nematode Caenorhabditis elegans. Based on 16S rRNA gene sequence similarity, DNA G+C content of 69.5 mol%, 2,4-diaminobutyric acid in the cell-wall peptidoglycan, major menaquinone MK-11, abundance of anteiso- and iso-fatty acids, polar lipids diphosphatidylglycerol and phosphatidylglycerol and a number of shared biochemical characteristics, strain TAN 31504(T) was placed in the genus Leucobacter. DNA-DNA hybridization comparisons demonstrated a 91 % DNA-DNA relatedness between strain TAN 31504(T) and Leucobacter chromiireducens LMG 22506(T) indicating that these two strains belong to the same species, when the recommended threshold value of 70 % DNA-DNA relatedness for the definition of a bacterial species by the ad hoc committee on reconciliation of approaches to bacterial systematics is considered. Based on distinct differences in morphology, physiology, chemotaxonomic markers and various biochemical characteristics, it is proposed to split the species L. chromiireducens into two novel subspecies, Leucobacter chromiireducens subsp. chromiireducens subsp. nov. (type strain L-1(T)=CIP 108389(T)=LMG 22506(T)) and Leucobacter chromiireducens subsp. solipictus subsp. nov. (type strain TAN 31504(T)=DSM 18340(T)=ATCC BAA-1336(T)).

Agulnik SI et al. (1997) Genome "Three novel T-box genes in Caenorhabditis elegans."

Ruvinsky I, Agulnik SI, Silver LM

[Genome, 1997]

The T-box gene family consists of members that share a unique DNA binding domain. The best characterized T-box gene, Brachyury or T, encodes a transcription factor that plays an important role in early vertebrate development. Seven other recently described mouse T-box genes are also expressed during development. In the nematode Caenorhabditis elegans, four T-box genes have been characterized to date. In this study, we describe three new C. elegans T-box genes, named Ce-tbx-11, Ce-tbx-12, and Ce-tbx-17. Ce-tbx-11 and Ce-tbx-17 were uncovered through the sequencing efforts of the C. elegans Genome Project. Ce-tbx-12 was uncovered through degenerate PCR analysis of C. elegans genomic DNA. Ce-tbx-11 and Ce-tbx-17 are located in close proximity to the four other previously described T-box genes in the central region of chromosome III. In contrast, Ce-tbx-12 maps alone to chromosome II. Phylogenetic analysis of all known T-box domain sequences provides evidence of an ancient origin for this gene family.

Sara Maxwell et al. (2002) European Worm Meeting "Functional analysis of the C. elegans T-box gene family"

Alison Woollard, Roger Pocock, Lizzie Clarke, Sara Maxwell

[European Worm Meeting, 2002]

T-box genes are a group of developmentally important transcription factors united by a common DNA binding domain. T-box genes are present in all metazoan species so far analysed but are absent from yeast. There are 20 T-box genes in C. elegans, more than twice the number found in Drosophila. Many of the C. elegans T-box genes are highly diverged from those found in other species while others have clear orthologues present throughout the metazoan kingdom. One highly conserved T-box gene is mab-9, a member of the tbx20 sub-family1. This was the first C. elegans T-box gene to be identified by mutation and is required for cell fate specification during hindgut and male tail development, and aspects of nervous system function. One other conserved T-box gene has recently been reported to be important for a particular muscle cell fate specification2. We have inactivated the remaining C. elegans T-box genes by RNAi and have found obvious phenotypes only in very few cases. These phenotypes include embryonic lethality, L1 lethality, and a Dpy phenotype with weakly penetrant male tail defects, and will be described in detail. The remaining T-box genes give no obvious phenotype by RNAi. Phylogenetic analysis reveals that several pairs of T-box genes are very similar to eachother and are therefore likely to be the result of recent duplications. This might suggest functional redundancy. Double RNAi experiments have revealed this to be the case with at least two of the T-box gene pairs (see also poster by Pocock et al). Study of the expression patterns of the whole T-box family may suggest other potential redundancy relationships which can be explored by RNAi. Comparison of the C. elegans T-box genes with the set of T-box genes now defined for C. briggsae is being used as a tool for defining potentially important regulatory regions present in orthologous genes.

Won SM et al. (2016) J Med Food "Tenebrio molitor Extracts Modulate the Response to Environmental Stressors and Extend Lifespan in Caenorhabditis elegans."

Park SK, Yi SS, Kim SJ, Cha HU, Won SM

[J Med Food, 2016]

Tenebrio molitor are large insects and their larvae are consumed as food in many countries. The nutritional composition of T. molitor has been studied and contains high amounts of proteins, unsaturated fatty acids, and valuable minerals. However, the bioactivity of T. molitor has not been fully understood. We examined the effects of T. molitor extracts on resistance to oxidative stress and organism's lifespan using Caenorhabditis elegans as a model system. The response to heat shock and ultraviolet (UV) irradiation was monitored in vivo. The extracts from T. molitor showed significant effects on resistance to oxidative stress and UV irradiation and extend both mean and maximum lifespan of C. elegans. The number of progeny produced significantly increased in animals supplemented with T. molitor extracts. In addition, the expression of hsp-16.2 and sod-3 was markedly upregulated by supplementation with T. molitor extracts. These findings suggest that T. molitor extracts can increase response to stressors and extend lifespan by the induction of longevity assurance genes in C. elegans.

Massoulie J et al. (2006) J Mol Neurosci "The C-terminal T peptide of cholinesterases: structure, interactions, and influence on protein folding and secretion."

Bon S, Massoulie J

[J Mol Neurosci, 2006]

Mammalian cholinergic tissues mostly express the T splice variant of acetylcholinesterase, in which the catalytic domain is associated with a C-terminal peptide of 40 residues, called the t peptide (Massoulie, 2002). Homologous t peptides exist in all vertebrate cholinesterases, acetylcholinesterases (AChEs), and butyrylcholinesterases (BChEs): they contain a series of seven conserved aromatic residues, including three tryptophans, and a cysteine at position-4 of their C-terminus. The major AChE isozyme of the nematode Caenorhabditis elegans also contains a similar peptide. Although the C-terminal t peptides do not seem to affect the catalytic activity of cholinesterases, they determine their physiological function, because they allow cholinesterase subunits of type T to form oligomers and to associate with structural anchoring proteins. When reduced to their catalytic domain, AChE subunits without a t peptide are active but remain monomeric and soluble.