Lee, Hee Kyung et al. (2021) International Worm Meeting "The role of mitochondria calcium uniporter in C. elegans odor learning"

Yoon, Kyoung-hye, Kwon, Saebom, Antonio, Jessica, Lee, Hee Kyung

[International Worm Meeting, 2021]

Calcium is essential for neuronal function - for activation, synaptic transmission, and also for modulating sensory adaptation and synaptic strength. Calcium concentration is carefully regulated in the cell by actively sequestering calcium into ER and mitochondria by transporters and calcium binding proteins. Mitochondrial calcium uniporter (MCU) is the transporter that permits calcium entry into the mitochondrial matrix, where, in addition to buffering cytosolic calcium, it regulates mitochondria-mediated cellular processes such as ATP synthesis and apoptosis. However, the role of MCU and mitochondrial calcium in neuronal function remains largely unknown. In this study, we sought to find the role of MCU and mitochondrial calcium in neurons in C. elegans, by using simple odor learning paradigms. We found that, whereas wild type strain shows significantly decreased chemotaxis index in response to 60 min pre-exposure, mcu-1 mutants show only a modest decrease. This was the case only for odors detected by the AWC sensory neuron, such as benzaldehyde and butanone. Restoring MCU-1 in all neurons and AWC resulted in normal adaptation, showing that MCU-1 in the sensory neuron is sufficient for adaptation. Using the heat shock inducible promoter, we found that mcu-1 is required during early larval development (egg or L1 stage), and restoring expression after L4 or adult stage did not improve odor learning. Surprisingly, we found that overexpression of mcu-1 in the AWC neuron resulted in delayed forgetting of the odor memory. This suggests that mcu-1 may regulate the plasticity of odor memory depending on its expression levels. We are currently investigating the downstream mechanism of our observations.

Kwon, Saebom et al. (2021) International Worm Meeting "Investigating the mechanism of the cell-nonautonomous roles of the nuclear hormone receptor NHR-49 in the nervous system of Caenorhabditis elegans"

Lee, Hee Kyung, Yoon, Kyoung-hye, Antonio, Jessica, Kwon, Saebom, Lee, Jin Il

[International Worm Meeting, 2021]

The central nervous system plays a key role in regulating and coordinating whole-body metabolism. In C. elegans, the nuclear hormone receptor NHR-49 is ubiquitously expressed and serve as an important regulator of fat metabolism. In addition to altered lipid composition, nhr-49 mutants display a pleiotropy of defects, including shorter lifespan, impaired starvation response, and increased susceptibility to oxidative stress and pathogenic bacteria. Interestingly, NHR-49 expression in the neuron alone is sufficient to nearly restore lifespan. In light of recent findings of the cell-nonautonomous effects of neurons in cell stress and energy homeostasis in C. elegans, we wondered whether NHR-49 function in the neuron alone could also reverse other known nhr-49 mutant defects. We confirmed that expressing NHR-49 exclusively in the neurons restores lifespan to a near-wild type level and found that it was also sufficient to restore resistance to gut commensal bacteria. In contrast, neuronal NHR-49 did not restore resistance to oxidative stress. We are currently trying to identify the circuitry and signaling mechanism of this neuron-to-periphery communication.

Abate JP et al. (2009) Cell Metab "Life is short, if sweet."

Blackwell TK, Abate JP

[Cell Metab, 2009]

Insulin is essential for glucose homeostasis, but reducing its activity delays the aging process in model organisms. In this issue of Cell Metabolism, Lee et al. (2009) show how these effects of insulin signaling intersect when glucose is fed to C. elegans.

Lee C et al. (2017) Bio Protoc "Single-molecule RNA Fluorescence in situ Hybridization (smFISH) in Caenorhabditis elegans."

Sorensen EB, Lee C, Seidel HS, Lynch TR, Crittenden SL, Kimble J

[Bio Protoc, 2017]

Single-molecule RNA fluorescence <i>in situ</i> hybridization (smFISH) is a technique to visualize individual RNA molecules using multiple fluorescently-labeled oligonucleotide probes specific to the target RNA ( Raj <i>et al.</i>, 2008 ; Lee <i>et al.</i>, 2016a ). We adapted this technique to visualize RNAs in the <i>C. elegans</i> whole adult worm or its germline, which enabled simultaneous recording of nascent transcripts at active transcription sites and mature mRNAs in the cytoplasm ( Lee <i>et al.</i>, 2013 and 2016b). Here we describe each step of the smFISH procedure, reagents, and microscope settings optimized for <i>C. elegans</i> extruded gonads.

Dawes-Hoang RE et al. (2003) Dev Cell "Bringing classical embryology to C elegans gastrulation."

Zallen JA, Wieschaus EF, Dawes-Hoang RE

[Dev Cell, 2003]

In a recent paper, Lee and Goldstein develop an explant assay that recapitulates key aspects of gastrulation in C. elegans and permits classical embryological manipulations. The resulting detailed analysis of cell behavior will ultimately extend to broader issues, such as, whether morphogenesis can be described as the sum of single-cell events or if unique phenomena emerge at the multicellular level.

Bauer, Jack et al. (2021) MicroPubl Biol

Labb, Jean-Claude, Lacroix, La, Bauer, Jack

[MicroPubl Biol, 2021]

To perturb actomyosin function in the primordial germ line, we first monitored germ line organization in L1-stage animals bearing temperature-sensitive (ts) alleles in genes encoding actomyosin regulators and that were reported to interfere with cytokinesis during embryogenesis (Davies et al. 2014). Previous work demonstrated that the initial stages of germline expansion occur normally in cyk-4(ts) and zen-4(ts) animals raised at restrictive temperature from the L1 stage (Lee et al. 2018). We found that primordial germ line organization in cyk-1(ts), nmy-2(ts), cyk-4(ts) or zen-4(ts) L1 larvae maintained at restrictive temperature for 12h was no different than control (Figure 1A-B). Furthermore, the first primordial germ cell (PGC) division occurred normally upon feeding these animals at restrictive temperature with typical bacterial food (E. coli OP50). As noted previously (Lee et al. 2018), germ line disorganization and sterility were observed in all cases when animals reached adulthood (Figure 1B).

Mondol V et al. (2012) Curr Top Dev Biol "Let's make it happen: the role of let-7 microRNA in development."

Mondol V, Pasquinelli AE

[Curr Top Dev Biol, 2012]

Noncoding RNAs have emerged as an integral part of posttranscriptional gene regulation. Among that class of RNAs are the microRNAs (miRNAs), which posttranscriptionally regulate target mRNAs containing complementary sequences. The broad presence of miRNAs in lower eukaryotes, plants, and mammals highlights their importance throughout evolution. MiRNAs have been shown to regulate many pathways, including development, and disruption of miRNA function can lead to disease (Ivey and Srivastava, 2010; Jiang et al., 2009). Although the first miRNA genes were discovered in the nematode, Caenorhabditis elegans, almost 20 years ago, the field of miRNA research began when they were found in multiple organisms a little over a decade ago (Lagos-Quintana et al., 2001; Lau et al., 2001; Lee and Ambros, 2001; Lee et al., 1993; Pasquinelli et al., 2000; Wightman et al., 1993). Here, we review one of the first characterized miRNAs, let-7, and describe its role in development and the intricacies of its biogenesis and function.

Ho F et al. (1992) Worm Breeder's Gazette "The Second Approach to Aligning the Genetic and Physical Maps on Chromosome I: PCR mapping of Potential Deletions"

Ho F, Janmaat A, Ha TT, Melathopoulos A, Liu T, Rose AM, Salmon R

[Worm Breeder's Gazette, 1992]

For the right portion of the chromosome, where we don't have a high density of mapped mutants, we are using the PCR mapping protocol of Barstead and Waterston (in 1991 C Mot Cyto 20:69) to position gamma-induced lethals (potential deletions). Using hIn1 as a balancer (Zetka and Rose, 1992 Genetics), we recovered several lethals linked to unc-101 and lev-11 which were induced with 1500 rads of gamma radiation. Primers were kindly provided by Junho Lee in Paul Sternberg's lab and Yuko Kozono in Bob Waterstons's lab. As controls for the PCR reactions, we are using a deletion outside the hIn1 region, hDf8 ,and primers from bli-4 (Ken Peters, unpublished) and AHH sequences (Prasad, Starr and Rose, in press). hDf8 deletes AHH, but not bli-4 .We have tested nine of our gamma induced lethals to date and one of these hDf14 (h1277 )is lacking DNA for the primer set INT 7-10 from unc-101 sequences provided by Junho Lee.

Dana Byrd et al. (2008) Development & Evolution Meeting "Subcellular Architecture of the Germline Stem Cell Niche"

Karla Knobel, Judith Kimble, Katharyn Schmitt, Dana Byrd, Audra Amasino

[Development & Evolution Meeting, 2008]

A stem cell's decision between self-renewal and differentiation is governed by extrinsic stimuli from the surrounding microenvironment, or niche, as well as by intrinsic cues. In C. elegans, the distal tip cell (DTC) provides the niche for germline stem cells and maintains a "mitotic region" by Notch signaling (e.g. Kimble and Crittenden 2007). DTC number and dosage of the LAG-2 DSL ligand, which is expressed by the DTC, can affect the number of germ cells in the mitotic region (Dyan Vogel and Myon-Hee Lee). To investigate DTC niche function, we made a panel of fluorescent protein markers to visualize its subcellular structure in vivo. These include markers for the nuclear envelope, endoplasmic reticulum, Golgi, endosomes, and plasma membrane. Using membrane markers, we found that contact between the DTC niche and germ cells in the mitotic region is extensive. The DTC extends membrane processes that surround adjacent germ cells. The intimate contact between the niche and germ cells may provide a mechanism to physically anchor the distal-most germ cells within the niche and/or provide more localized signaling to maintain the germline stem cells. With a combination of DTC, sheath cell, and germ cell markers, we are examining the relationship between the extent of niche contact and the region of cells with stem cell potential. We are also using tissue-specific RNAi to test which genes are required in the DTC for regulation of germline stem cells.

Miranda MC et al. (2024) MicroPubl Biol "Investigating the effects of antipsychotic drugs as a treatment for improving the activity of the unc-33 /Dpysl2 gene in C. elegans."

Miranda MC, Hyde J, Holgado A, Salazar K, Bell B

[MicroPubl Biol, 2024]

Prenatal stress is hypothesized to contribute to the development of schizophrenia. Lee and colleagues determined that prenatal stress in rats decreases levels of Dpysl2, which is found to be inactivated in schizophrenic patients. UNC-33 , the homolog to Dpysl2 in <i>C. elegans</i> , is important for axonal outgrowth and synapse formation. Herein, we study the effects of antipsychotic drugs on developing <i>C.elegans</i> exposed to stress through high temperatures. Results indicate that the <i>unc-33</i> promoter was not impacted by antipsychotic drug treatment, but the lifespan was decreased.