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Sanchez, Sophia et al. (2021) International Worm Meeting "Systematic Behavioral Screen of 21st Chromosome Gene Overexpression in C. elegans"

Bigham, Caymee, Syed, Briana, Smith, Sofia, Nordquist, Sarah, Pierce, Jon, Perks, Katherine, Sanchez, Sophia

[

International Worm Meeting,

2021]

Down syndrome (DS) is caused by overexpression of 21st chromosome (Hsa21) genes due to the presence of an extra copy of Hsa21. A major goal in DS research is to understand the individual contribution of each Hsa21 gene to the numerous phenotypes that accompany DS. Progress is being made using mouse models to understand the role of certain Hsa21 genes. However, most Hsa21 genes have not been studied in any detail. To circumvent the time and cost of mouse models for single-gene studies, we are leveraging the speed and affordability of the nematode C. elegans. Our lab found that C. elegans has 51 highly-conserved orthologs of Hsa21 genes. By studying loss-of-function mutants and performing RNAi for these orthologs, we found that 14 are essential and 10 are required for neural or muscular function in C. elegans -- 3 of which had not previously been studied. Through epistasis analysis, we found that the novel molecule, MTQ-2, appears to modify G-protein signaling to regulate rates of cholinergic synaptic transmission. Additionally, to probe how overexpression (OE) of individual Hsa21 genes contributes to neuronal, muscular, and developmental phenotypes related to DS, we are generating a complementary set of 51 C. elegans transgenic strains that each overexpress a different Hsa21 ortholog. We are performing quantitative behavioral analyses with the OE strains to deduce which genes cause neural or muscular dysfunction when overexpressed. Thus far, we discovered a specific behavioral defect for six OE strains including EVA-1, a novel slit receptor involved in axon guidance recently discovered in C. elegans. By identifying Hsa21 genes that cause phenotypes when overexpressed in C. elegans, this study will highlight individual Hsa21 genes and pathways to prioritize for further study in other models and to consider as potential therapeutic targets for improving health in those with DS.

Scott, Luisa et al. (2013) International Worm Meeting "Identifying Novel BK Channel Modulators."

Scott, Luisa, Davis, Scott, Shen, Angela, Nordquist, Sarah, Philpo, Ashley, Iyer, Sangeetha, Pierce-Shimomura, Jon

[

International Worm Meeting,

2013]

The large-conductance calcium-activated potassium (BK) channel is an evolutionarily conserved target of ethanol. Physiologically relevant concentrations of ethanol increase BK channel opening. Additionally, genetic manipulation of BK channel function affects behavioral sensitivity to ethanol in multiple animal models. These findings suggest that the BK channel is a viable therapeutic target for alcohol intoxication and addiction. To begin to test this, we have developed a screen to identify peptides that alter BK channel function. First, we screened 30 million 9 amino acid peptide sequences using a monovalent phagemid display technique. Twenty-seven unique peptides remained after panning for sequences that bind to the human BKa channel but not the rat SK2 channel or human glycine a1 receptor. Sequences with clusters of positively charged amino acids were enriched 100-300 fold. Three motifs were enriched 3000-6000 fold. Next, select peptides were rapidly screened for functional effects using the nematode, C. elegans. Several peptides with highly enriched motifs affected an ethanol- and BK-channel dependent behavior in this animal. The behavioral assay suggests that peptide pskan4 enhances the ethanol mediated increase in BK channel opening, but does not alter channel activity in the absence of ethanol. Peptide pskan1 had BK channel- but not ethanol-dependent effects. In contrast, a peptide without a highly enriched motif had non-specific effects, and a 9 amino acid peptide not selected in the panning procedure did not alter locomotion. Finally, we have begun to confirm the function of the peptides electrophysiologically. Preliminary recordings support the putative action of peptides pskan1 and pskan4 as BK channel openers. Overall, these findings show that we have developed and successfully employed a screen for identifying and characterizing novel peptides that alter BK channel-dependent behavior in the presence of physiologically relevant concentrations of ethanol. This screening technique can be applied to identify modulators of other ion channels.

Ali Khan L et al. (1997) International C. elegans Meeting "MATERNAL GENE EMB-8 IS NECESSARY FOR ASYMMETRIC DISTRIBUTION OF DEVELOPMENTAL POTENTIALS IN EARLY C. ELEGANS EMBRYOS"

Siddiqui SS, Ali Khan L, Ali MY, Miwa J, Kikuno R, Kohara Y, Siddiqui ZK

[

International C. elegans Meeting,

1997]

A number of observations suggest that emb-8 gene plays critical roles in C. elegans development. At non-permissive temperature, emb-8 embryos divides symmetrically; in 50% the first division produces two equal sized cells, and in the second cleavage both of these cells divide symmetrically again to produce four equal sized cells. In some embryos, these four cells fuse togather and produce two asymmetric cells. emb-8 variably mislocalizes P-granules, they are uniformly distributed in 1-cell embryos, are localized on both anterior AB, and posterior P1 cells of the 2-cell embryos, and are found in all four blastomeres of the 4-cell embryos. Crittenden et al., (1996) also observed mislocalization of the P-granules and Glp-1 in emb-8 embryos. emb-8 also appears to control the orientation of early mitotic spindles, similar to the par-3 muatnts (K. Kemphues and others). However complementation tests show that emb-8 and par-3 are different genes. We thank Sarah Crittenden, Judith Kimble and Ken Kemphues for sharing unpublished results.

Munoz-Lobato, Fernando et al. (2021) International Worm Meeting "Sleep is required for odor exposure to consolidate memory and remodel olfactory synapses."

[

International Worm Meeting,

2021]

Sleep is not only an essential function of humans but remains conserved across metazoans. Here we demonstrate that wild-type C. elegans sleep after repeated odor trainings This provides us with a platform to dissect how sleep affects memory at a synaptic resolution. We identified that sleep immediately after training is required for the animal to retain a long-term memory of the odor. We found that if animals do not sleep in the first two hours after training, memory is not consolidated. After identifying the neurons that are required for the memory, we show that the sensory-interneuron connections within the circuit are downscaled after sleep. Therefore, we found a time-specific requirement of sleep that modulates synaptic downscaling to preserve memory. Conversely, lack of sleep post-training erases the long-term memory and destabilizes the synaptic downscaling, indicating that modulating the amount of sleep is sufficient to modulate memory. These results make C. elegans an excellent tool to ask what molecular mechanisms, cell biological processes and circuit level reorganizations are engaged during sleep to promote memory. This understanding will provide insights into the functions of sleep that contributes to our health and well-being.

Dayong Wang (2003) International Worm Meeting "Exploring the roles of hlb-1, homologue of iprin protein SYD-2"

Dayong Wang

[

International Worm Meeting,

2003]

Exploring the Roles of hlb-1, homologue of liprin protein SYD-2 Dayong Wang and Mei Zhen Samuel Lunenfeld Research Institute, Toronto, ON, Canada M5G 1X5 At synaptic junctions, the active zone, an electron-dense membrane structure, functions in vesicle docking and neurotransmitter release. Signaling mechanism that control the formation of the active zone and how active zone components regulate the neurotransmitter release, are not fully understood. SYD-2, a liprin family protein, localizes at the active zones, and restricts the area of active zones in C. elegans (Zhen and Jin, Nature 401:371-375, 1999). SYD-2 homologue in Drosophila may recruit receptor type tyrosine phosphatases to define areas for active zone development (Kaufmann et al., Neuron 34:27-38, 2002). It was also shown in vertebrates that a liprin protein directly interacts with RIM, another active zone component required for vesicle fusion (Schoch et al., Nature 415: 321-326, 2002). Despite its interaction with molecules essential for synaptic development and synaptic functions, the behavior phenotypes of syd-2 null animals are very mild. For example, active zones only show a 2-fold increase in size, and neurotransmission, as indicated by aldicarb tests, is only moderately defective. It is therefore possible other liprin homologue in C. elegans plays redundant roles. hlb-1(homologue of liprin-beta) encodes the only other liprin protein in C. elegans. HLB-1 protein has three coiled-coil domains, a putative trans-membrane domain and a SAM domain. Its SAM domain at the carboxy terminus is similar to that of SYD-2 protein, but its coiled-coil domain at the amino terminus is more divergent from that of SYD-2. We have generated a mutant in hlb-1 gene with deletion of the carboxy terminal region. The hlb-1 mutant animals exhibit a mild decrease in the thrashing frequency, moderate aldicarb resistance, and transient egg laying defects, suggesting that hlb-1 may be required for neuronal function. In the nervous system, we did not find axonal abnormalities, whereas there might be a more diffuse SNB-1::GFP vesicle marker distribution. Furthermore, the syd-2hlb-1 double mutant has more severe vesicle marker diffusion and acute aldicarb resistance than the syd-2 null mutant, or the hlb-1 mutants. We are analyzing the subcellular localization of HLB-1 protein, and if SYD-2 and HLB-1 functions together in presynaptic termini to regulate the development and function of active zones. (We acknowledge Dr. Joe Culotti and Sarah Bajurny for the deletion library and initial screen for hlb-1 mutants)