Way, A. et al. (2017) International Worm Meeting "A network of transcription factors regulates lysosomal lipolysis in C. elegans."

Mony, V.K., Way, A., O'Rourke, E.J.

[International Worm Meeting, 2017]

Adaptation to nutritional changes is a prominent example of plasticity in living organisms. Evolutionary conserved pathways like Insulin signaling, mechanistic Target of Rapamycin (mTOR), TGF- beta , caloric restriction (CR) and Notch receptor pathways have been characterized for their effects in growth and reproduction along with changes in fat metabolism in response to nutritional stress. Within each of these pathways "canonical" transcription factors (TFs) control the expression of distinctive downstream effectors. On the other hand, many TFs have shared regulators and targets. Given the plasticity in nutrient responses, it is an open question whether different upstream nutrient sensors would canalize nutritional information through their canonical TFs to activate adaptive responses, or whether the adaptive downstream effectors would be controlled by a small subset of specialized TFs common to all nutrient sensing pathways modulating a given adaptive molecular response. We have performed transcriptional analyses to dissect the regulation of genes encoding the C. elegans lysosomal lipases lipl-1, lipl-3 and lipl-4. Although known to have at least partially redundant roles, here we show that the genes encoding these lysosomal lipases are differentially controlled by a network of transcriptional activators and repressors that yield distinct expression patterns in animals with altered nutrient sensing or nutritional status. Surprisingly, HLH-30 (mammalian TFEB), a transcription factor we established to be required for activation of the lipl genes in fasting conditions, is found to be required for induction of lysosomal lipase upon mTOR inhibition but not in CR, insulin deficient, TGF-beta deficient, sterile worms, or other tested models of metabolic dysregulation. By contrast, DAF-16 (mammalian FOXO) is found to control lysosomal lipases downstream of multiple nutrient sensing pathways. Similarly surprising, PHA-4, a gene activating gene expression in CR animals, and NHR-49 a master activator of beta-oxidation upon fasting, act as repressors of the lipl genes, suggesting a dual role for PHA-4 and NHR-49 in adaptation to food scarcity. Additionally, DAF-3 (co-SMAD), NHR-80 (HNF4), SKN-1 (Nfr2), and HSF-1 contribute to regulation of the expression of the lysosomal lipases. All in all, we found that although the specificity of lipase expression depended on the same TFs downstream of multiple nutrient regulatory pathways, they are also under the promiscuous regulation of disparate TFs. *Way A. and Mony V.K. contributed equally to the work presented in the abstract.

Birsoy, Bilge et al. (2009) International Worm Meeting "Right Way to Have Sex."

Bloss, Tim, Birsoy, Bilge, Rothman, Joel H., Downes, Joanna C., Choi, Shin Sik

[International Worm Meeting, 2009]

While the mechanism that breaks left-right (L-R) anatomical asymmetry (handedness) has been described in C. elegans, we have found that at least one additional mechanism must exist to establish other handedness cues that generates L-R differences in the deployment of alternative cell death pathways (see abstract from our lab by Choi et al.). To assess whether such a system might affect a behavior in the worm, we investigated whether male mating behavior exhibits L-R handedness. Upon recognizing a hermaphrodite, males initiate backward locomotion and continuously scan along the hermaphrodite''s body. When their tails reach either the head or tail of the hermaphrodite, males turn to maintain contact and then continue backward locomotion on the opposite side of the hermaphrodite. We found that this turning behavior shows a distinct right-handed bias: when individual males were allowed to mate with lin-2(e1309) vulvaless hermaphrodites, >70% of the turns when made over the hermaphrodites'' body (away from the agar surface) and >55% of turns when made under the hermaphrodites'' body (toward the agar surface) are right-handed. To determine whether this bias in turning direction correlated with L-R asymmetry in the male mating structure, which results from stochastic EGL-1-dependent loss of sensory rays (Choi et al. abstract), we examined the turning bias in egl-1(n1084n3082) mutants. We were surprised to find that, although wild-type males lack rays more frequently on the right, the right-hand turning bias is actually increased in the egl-1 mutant, in which no rays are lost and therefore rays are always symmetrically arranged. Thus, the intrinsic turning bias is even more apparent in males with symmetric mating structures. To assess whether this L-R behavioral bias is dependent on anatomical handedness, we analyzed gpa-16(it143) mutants in which the L-R asymmetry of the internal organs is reversed as a result of the reversal in the early embryonic symmetry break. Males with reversed anatomical asymmetry showed a virtually identical right hand bias in turning, demonstrating that a handedness-determining system that is independent of the previously described L-R symmetry breaking event must control this behavior. These findings raise the possibility that, analogous to brain laterality in humans, functionally L-R asymmetry in the C. elegans motor nervous system may be independent of anatomical handedness.

Way JC et al. (1987) International C. elegans Meeting "cloning the mec-3 gene."

Chalfie M, Way JC

[International C. elegans Meeting, 1987]

Way JC et al. (1991) International C. elegans Meeting "CONTROL OF MEC-3 MAINTENANCE EXPRESSION"

Zhang J, Way JC

[International C. elegans Meeting, 1991]

The mec-3 gene promotes dfflerentiation of the C. elegans touch receptors and two other sets of mechanoreceptors, probably by turning on structural genes necessary for mechanoreceptor function. Our goal is to understand how mec-3 is regulated in order to understand how a stereotyped cell lineage works. We find that the mec-3 promoter contains 4 non-coding regions that are conserved between two C. elegans and the Caenorhabditis species WS9-6. These regions contain presumptive binding sites for unc-86 and mec-3: there are two sequences that resemble the POU consensus binding site, and two other sequences that resemble the binding site for 1sl-1, a trarlscription factor from the pancreas that has an extended homology to mec3. Site-directed mutagenesis reveals that one of the presumptive unc-86 sites is required for mec-3-dependent maintenance of mec-3 expression. Temperature shift experiments with an unc-86-ts mutant show that unc-86 is necessary for continued mec-3 expression, in addition to its known role in establishment of mec-3 synthesis (see Zhang and Way abstract). Mutations in a second site cause expression in additional cells (the SDas and probably the ALNs, both sisters of touch receptors) and also extend the duration of establishment synthesis seen in a rnec-3 mutant background. This site may be a target for a repressor of mec-3 that could mediate asyrnmetric expression of mec-3 during stereotyped cell lineages.

Wicky C et al. (1991) International C. elegans Meeting "A WAY TO CLONE C. ELEGANS TELOMERES"

Mueller F, Wicky C, Tobler H

[International C. elegans Meeting, 1991]

By doing Bal 31 digestion experiments, we have shown that about 4 to 9 kb of the simple repeated sequence TTAGGC are located at the end of the C. elegans chromosomes. This sequence, also present at the A. lumbricoides telomeres, shows similiarities to the telomeric sequences found in all organisms analyzed so far, including some lower eukaryotes, plants and vertebrates. In order to develop an efficient strategy to clone C. elegans telomeres, we have constructed a YAC (yeast artificial chromosome), carrying an Ascaris telomere at one end. Upon transformation, we could show that the sequence TTAGGC functions as telomere in yeast, which adds its own telomeric sequences to it. We conclude, therefore, that cloning of C. elegans telomeres can be done by complementation of a deficient YAC vector. Besides the fact that telomeres are specialized structures important for chromosome stability, the particular significance of cloned C. elegans telomeres is that they will contribute to achieve the physical mapping of chromosomes and that they provide one set of elements for the construction of artificial C.elegans chromosomes.

Abbatemarco, S. et al. (2019) International Worm Meeting "Cytoplasmic PLK-1 foci: a way to regulate PLK-1 function?"

Gotta, M., Schwager, F., Abbatemarco, S., Cirillo, L.

[International Worm Meeting, 2019]

The cytoplasm of a cell is a very crowded place where a large number of different molecules work together to ensure the accomplishment of all cellular processes. Proteins and RNAs freely diffuse within the densely packed space of the cytoplasm, but under specific conditions, they condensate and undergo liquid-liquid phase-separation. This phase transition leads to the formation of liquid droplets, membrane-less organelles, where proteins and RNAs are concentrated. Through this process cells are able to regulate the activity of specific proteins in a precise space and time. Recently, we identified a novel protein in C. elegans embryos, named PQN-59 (Prion-like-(Q/N-rich)-domain-bearing protein). We found that the depletion of PQN-59 leads to the formation of cytoplasmic granules of the mitotic kinase Polo Like Kinase 1 (PLK-1). However, the nature of these granules and the signal that triggers their formation is unknown. The absence of PQN-59 is also associated with the appearance of several mitotic defect such as erroneous chromosome alignment and erroneous chromosome segregation. We are currently investigating if the mitotic defects observed in absence of PQN-59 are the result of the sequestration of PLK-1 into the cytoplasmic aggregates. Taken together, our data lead us to hypothesize that PQN-59 is involved in the regulation of the cytoplasmic state of specific proteins and therefore their function.

Jessica Smith et al. (1999) International C. elegans Meeting "When humans lead the way: uncovering the role of C27H5.1"

Michelle Chambers, Dave Pilgrim, Jessica Smith

[International C. elegans Meeting, 1999]

C27H5.1 is a weak homologue of UNC-119, a gene involved in axon guidance and outgrowth. We first became interested in C27H5.1 because of its similarity to UNC-119. We have since learned that there is a mammalian homologue of C27H5.1; rod phosphodiesterase delta subunit PDE6D. These two proteins are very highly conserved exhibiting 70% identity and 85% similarity. UNC-119 also has a close mammalian homologue; retinal protein HRG4/RRG4. Both C27H5.1 and UNC-119 are pan-neuronal in C. elegans while HRG4 and PDE6D are expressed in the mammalian retina. The conservation of these genes has led us to speculate that they may constitute a new protein family. While UNC-119 has been fairly well characterized, very little is known about C27H5.1. Based upon its conservation with UNC-119 and PDE6D, we suspect that C27H5.1 is playing an important role, perhaps in nervous system development. However, C27H5.1 may play a more general role. Unlike UNC-119, C27H5.1 expression is not limited to the nervous system. There is also expression in pharyngeal and vulval muscle. To determine this role, we have performed RNA interference against C27H5.1. Unfortunately, no phenotype was observed. Subsequently we performed RNAi against GFP under the control of the C27H5.1 promoter. There was no reduction in fluorescence suggesting that the expression of C27H5.1 is not affected by RNAi. We are currently screening for a deletion in C27H5.1. Although we have not yet been successful in determining the C27H5.1 mutant phenotype, studies with its mammalian homologue, PDE6D, suggest a possible role for this protein. PDE6D has been shown to bind to and solubilize rod phosphodiesterase (PDE). Since PDE6D expression is not limited to the retina, PDE d may regulate the membrane binding of a variety of proteins. Interestingly, C27H5.1 also binds human rod phosphodiesterase, suggesting that there is at least some functional conservation between PDE d and C27H5.1.

Way JC et al. (1989) International C. elegans Meeting "localization of mec-3 expression using a mec-3-lacZ gene fusion."

Chalfie M, Way JC

[International C. elegans Meeting, 1989]

Jens Schulze et al. (2007) International Worm Meeting "An alternative way to construct a nematode: Cell lineages and cell fate specification in Romanomermis culicivorax."

Jens Schulze, Einhard Schierenberg

[International Worm Meeting, 2007]

During early embryogenesis of C. elegans a small number of somatic founder cells is generated via a series of polar unequal cleavages of the germline. These founder cells give rise to fixed numbers of descendants with invariable fate. In order to determine to what extent this pattern is characteristic for nematodes in general, we have started to study the phylogenetically distant parasitic species Romanomermis culicivorax (order Mermithida) in comparison to the standard C. elegans. Using 4-D recordings of living embryos, we find prominent differences with respect to cell cycle durations, cell lineage patterns, establishment of bilateral symmetry, fate assignments of somatic founder cells, and spatial arrangements of blastomeres. For example, the complete gut is derived from the S1 (AB) cell instead of S2 (EMS) and all hypodermal cells are descendants of a single founder cell. This blastomere undergoes three consecutive transverse cleavages this way generating a cell ring as a basic building block. A series of a-p cleavages leads to a multiplication of these units. This way, starting from the posterior pole, the hypodermis eventually extends over the whole remainder of the embryo. In addition, starting with the first division, cytoplasmic pigment is segregated during early embryogenesis into hypodermis and body muscle precursors. In general, the lineage design of R. culicivorax appears to be considerably simpler than that of C. elegans, i.e. to a much higher degree monoclonal. These and other studies from our laboratory indicate that massive developmental modifications took place during evolution in the phylum Nematoda.

Schulze, Jens et al. (2009) International Worm Meeting "An alternative way to construct a nematode - Embryogenesis of Romanomermis culicivorax differs considerably from C. elegans."

Schierenberg, Einhard, Schulze, Jens

[International Worm Meeting, 2009]

Nematodes constitute excellent candidates for comparative studies of early embryogenesis. However, our picture of their embryonic development is mainly shaped by C. elegans and Ascaris megalocephala. Their pattern of development is therefore considered typical for the whole taxon. For the first time a comprehensive description of embryogenesis in the basal nematode Romanomermis culicivorax is presented and found to differ considerably from the standard C. elegans. The segregation of colored cytoplasm into specific somatic founder cell and its descendants, a so far unique phenomenon in nematodes, resembles the distribution of pigmented myoplasm in certain ascidians. Polar cortical interphase microtubules in early blastomeres suggest a new MTOC involved in the asymmetric distribution of the colored cytoplasm. The cell lineage is less complex in that many branches generate predominantly cells with monoclonal fates. New is also that hypodermal and neuronal cells form duplicating rings along the a-p axis resembling segmentation and may give embryonic support for the Ecdysozoa hypothesis. Furthermore, we detected a global shift in fate assignment of the somatic founder cells in R. culicivorax compared to C. elegans. In summary, our data give evidence that in the course of nematode evolution massive modifications of the developmental program took place and embryogenesis of C. elegans is just one option within the taxon of nematodes.