11 Papers found (0.015 seconds)

Palikaras K et al. (2016) Bio Protoc "Measuring Oxygen Consumption Rate in Caenorhabditis elegans."

[

Bio Protoc,

2016]

The rate of oxygen consumption is a vital marker indicating cellular function during lifetime under normal or metabolically challenged conditions. It is used broadly to study mitochondrial function (Artal-Sanz and Tavernarakis, 2009; Palikaras et al., 2015; Ryu et al., 2016) or investigate factors mediating the switch from oxidative phosphorylation to aerobic glycolysis (Chen et al., 2015; Vander Heiden et al., 2009). In this protocol, we describe a method for the determination of oxygen consumption rates in the nematode Caenorhabditis elegans.

Park, Y. et al. (2019) International Worm Meeting "Identify genes to mediate ascr#3 avoidance in C. elegansIdentify genes to mediate ascr#3 avoidance in C. elegans."

Ryu, L., Cheon, Y., Kim, K., Park, Y.

[

International Worm Meeting,

2019]

Insulin-like signaling pathway plays diverse roles in metabolism, growth, longevity, development, and behaviors in the animal kingdom. C. elegans genome encodes 40 insulin-like genes (Duret et al., 1998; Pierce et al., 2001; Li et al., 2003; Li and Kim, 2008), which regulate development and behaviors. Also, C. elegans releases small molecules ascarosides, which control dauer formation, sex-specific and social behaviors. We and others previously showed that C. elegans hermaphrodite exhibits acute avoidance behavior to ascr#3 (asc-?C9, C9) exposure via the ascr#3-sensing ADL neurons (Jang et al., 2012). Moreover, we also showed that feeding state affects ascr#3 avoidance through DAF-2 insulin-like receptor (Ryu et al., 2018). To further investigate role of ILPs in ascr#3 avoidance, we examined contribution of INS-1 to ascr#3 avoidance. We first found that ins-1 mutant animals decrease ascr#3 avoidance behaviors in well-fed condition. We are currently identifying where and how INS-1 acts to mediate ascr#3 avoidance. Additionally, we are testing whether energy-sensing AMPK signaling affects ascr#3 avoidance. Key words: ILPs, Pheromone Avoidance, Starvation. AMPK signaling

Hwang, H. et al. (2019) International Worm Meeting "Plasticity of ascr#3 avoidance behavior in C. elegans."

Hwang, H., Kim, K.

[

International Worm Meeting,

2019]

Experiences or environmental cues can influence neuronal functions and behaviors. However, the neuronal and molecular mechanisms of behavioral plasticity are not fully understood. Caenorhabditis elegans secretes a mixture of small molecules referred as ascarosides that sense environmental conditions including population density and influence many aspects of development and behavior of C. elegans (Edison, 2009; Srinivasan et al., 2012). Wild-type hermaphrodites are repulsive to ascr#3(asc-?9, C9) while wild-type males are attractive to it (Macosko et al., 2009, Jang et al 2012). Previously, we have shown that ascr#3 avoidance behaviors are modulated by early experience of ascr#3 and feeding state, indicating that ascr#3 avoidance behaviors are plastic (Hong et al., 2017, Ryu et al., 2018). Here, we next investigated whether ascr#3 response is habituated by repeated exposure of ascr#3. We found that wild-type hermaphrodites exhibit normal ascr#3 avoidance to each exposure up to ten times, suggesting that ascr#3 avoidance behavior is not habituated. However, we found that the ascr#3-sensing ADL neurons shows decreased Ca2+ response to ascr#3 upon repeated exposure of ascr#3, indicating that adapted ADL responses to repeated ascr#3 exposure do not lead to habituation of ascr#3 avoidance behavior. In addition, we examined the effects of mating on ascr#3 avoidance and found that mated hermaphrodites appear to exhibit increased ascr#3 avoidance. Understanding how the behaviors are altered upon various experience or condition is the essential step to dissect molecular and neuronal mechanisms of behavioral plasticity.

Adam Brown et al. (2003) International Worm Meeting "Genetic analysis of AFD thermosensory neuron function in C. elegans."

Adam Brown, Piali Sengupta

[

International Worm Meeting,

2003]

Thermosensation plays an important role in the development, metabolism, and behavior of animals. C. elegans can be used to genetically dissect thermosensation, as they demonstrate distinct behaviors in response to temperature gradients. Genetic and laser ablation experiments have identified a circuit of neurons responsible for this behavior, including the primary temperature sensing neuron type, AFD. However, little is known about how AFD mediates its functions, as well as how worms form the "memory" of their cultivation temperature that modulates this behavior. Previously, a screen for mutations that alter the expression of a fusion gene gcy-8::gfp expressed specifically in the AFD neuron pair was performed in our lab to investigate AFD development and function. This screen led to the identification of the Otx/Otd-like homeobox transcription factor gene ttx-1, which is necessary and sufficient to specify AFD fate (Satterlee et al, 2001), and the cmk-1 CaMKI ortholog (see abstract by Satterlee and Sengupta). We are currently continuing this screen to identify further components of the AFD developmental and sensory pathways. We have screened the progeny of over 25,000 haploid genomes and identified a number of mutants. It is expected that a subset of these mutants may define additional genes required for both the function and development of the AFD neurons. Additionally, we also plan to carry out thermosensory behavioral screens to identify mutants with defects in distinct aspects of thermosensation. Finally, in collaboration with Will Ryu and Aravi Samuel (Rowland Institute, Harvard University), we have initiated behavioral analyses of both new and existing signaling mutants in an attempt to further dissect the neuronal pathways and molecules required for thermosensory behaviors.

Ye Z et al. (2023) Front Cell Dev Biol "Trends in mitochondrial unfolded protein response research from 2004 to 2022: A bibliometric analysis."

Wei Y, Luan Y, Ye Z, Chai R, Shi S, Hu Y, Du Y, Wu H, Zhang L, Xue W

[

Front Cell Dev Biol,

2023]

The mitochondrial unfolded protein response (UPRmt) is a stress response pathway that regulates the expression of mitochondrial chaperones, proteases, and other proteins involved in protein folding and degradation, thereby ensuring proper mitochondrial function. In addition to this critical function, the UPRmt also plays a role in other cellular processes such as mitochondrial biogenesis, energy metabolism, and cellular signaling. Moreover, the UPRmt is strongly associated with various diseases. From 2004 to 2022, there has been a lot of interest in UPRmt. The present study aims to utilized bibliometric tools to assess the genesis, current areas of focus, and research trends pertaining to UPRmt, thereby highlighting avenues for future research. There were 442 papers discovered to be related to UPRmt, with the overall number of publications rising yearly. International Journal of Molecular Sciences was the most prominent journal in this field. 2421 authors from 1,402 institutions in 184 nations published studies on UPRmt. The United States was the most productive country (197 documents). The top three authors were Johan Auwerx, Cole M Haynes, and Dongryeol Ryu. The early focus of UPRmt is "protein." And then the UPRmt research shifted from Caenorhabditis elegans back to mammals, and its close link to aging and various diseases. The top emerging research hotspots are neurodegenerative diseases and metabolic diseases. These findings provide the trends and frontiers in the field of UPRmt, and valuable information for clinicians and scientists to identify new perspectives with potential collaborators and cooperative countries.

Narayan, Anusha et al. (2009) International Worm Meeting "Transfer at a thermosensory synapse in C. elegans."

Laurent, Gilles, Sternberg, Paul, Narayan, Anusha

[

International Worm Meeting,

2009]

C.elegans is an attractive system for neural circuit analysis. To analyze the functional dynamics of circuits that control behavior, it is necessary to understand the underlying synaptic transformations. Thermotaxis is an established behavior in C. elegans[1-2]. We attempt to characterize the transfer function at a prominent synapse within the thermotactic circuit: between AFD, the primary thermosensory neuron[3], and AIY, its principal post-synaptic partner. We drive expression of Channelrhodopsin-2(chR2), a light-activated cation channel [4], solely in AFD, using a cell-specific promoter, and use whole-cell patch-clamp recording techniques to measure the light-evoked synaptic response at AIY. We are able to reliably activate the presynaptic cell AFD, evoking depolarizing potentials of up to 40 mV and inward currents of up to 15 pA. The postsynaptic response at AIY is small: less than 5 mV, with inward currents of less than 1 pA, and is graded and tonic, lasting the duration of the stimulus. The response reverses around 0 mV and seems to be frequency independent, showing no obvious short-term facilitation or depression. Our results further validate the use of chR2 to stimulate neural activity, and indicate that this synapse has low gain, and transmits information from AFD to AIY with short latencies and high fidelity. It will be interesting to see how AIY integrates this information with other incoming streams, and to examine processing downstream in the thermotactic circuit. 1.Mori, I., H. Sasakura, and A. Kuhara, Worm thermotaxis: a model system for analyzing thermosensation and neural plasticity. Curr Opin Neurobiol, 2007. 17(6): p. 712-9. 2.Ryu, W.S. and A.D. Samuel, Thermotaxis in Caenorhabditis elegans analyzed by measuring responses to defined Thermal stimuli. J Neurosci, 2002. 22(13): p. 5727-33. 3.Clark, D.A., et al., The AFD sensory neurons encode multiple functions underlying thermotactic behavior in Caenorhabditis elegans. J Neurosci, 2006. 26(28): p. 7444-51. 4.Boyden, E.S., et al., Millisecond-timescale, genetically targeted optical control of neural activity. Nat Neurosci, 2005. 8(9): p. 1263-8.

Dave Markwardt et al. (2001) International C. elegans Meeting "A screen for natural targets of NMD using C. elegans cDNA microarrays"

Philip Anderson, Dave Markwardt

[

International C. elegans Meeting,

2001]

mRNA transcripts that contain premature termination codons are degraded in a regulated manner by a specific decay pathway termed mRNA surveillance or nonsense mediated mRNA decay (NMD). mRNA surveillance has been described in all eukaryotes tested including plants, flies, yeast, nematodes, and mammals. Loss-of-function mutations affecting any of seven smg genes eliminates mRNA surveillance in C. elegans . While much progress has been made in defining the cis -acting elements and trans -acting factors necessary for mRNA surveillance, less is know about the mRNAs produced during the normal course of gene expression that serve as substrates of NMD. In order to systematically investigate these natural targets of NMD, I have probed high density microarrays of C. elegans cDNA clones. These arrays, made in Stuart Kim's lab at Stanford University, consist of PCR fragments from 17,871 genes currently annotated in the C. elegans genome (Jiang et al., 2001). We performed nine different hybridizations, each comparing expression profiles of poly(A) + mRNA from smg(-) and smg(+) samples. The microarray screen identified 402 mRNAs whose abundance is 2-fold or greater in smg(-) mutants. Several observations suggest that microarrays are a reliable method for identifying natural targets of mRNA surveillance: 1. Control mRNAs known previously to be natural targets of mRNA surveillance ( rpl-12 and srp-20 ) were consistently elevated on the microarray screen. 2. Both northern blots and quantitative PCR analyses confirm the microarray results. These results indicate that the microarray screen will be useful for the systematic investigation of the C. elegans natural targets of NMD. We are presently analyzing smg(-) affected mRNAs to establish whether they are direct or indirect targets of NMD, and understand why their abundance is increased in smg(-) mutants. We anticipate that analysis of the ~400 candidate genes will identify broad categories of mRNAs produced in wild-type animals yet targeted for degradation by NMD and, possibly, new principles of post-transcriptional regulation of gene expression. Jiang M, Ryu J, Kiraly M, Duke K, Reinke V, Kim SK. Genome-wide analysis of developmental and sex-regulated gene expression profiles in Caenorhabditis elegans . Proc. Nat. Acad. Sci. USA. (2001) 98 (1):218-23.

Ross JM et al. (2000) Midwest Worm Meeting "Sex-specific gene expression in C. elegans: in search of tra-1 and mab-3 targets"

Zarkower D, Yi W, Jiang M, Kim S, Ryu J, Duke KK, Ross JM, Thoemke K, Sohrmann M

[

Midwest Worm Meeting,

2000]

The transcription factor TRA-1A functions as the terminal global regulator of somatic sexual development. Thus TRA-1A must regulate, directly or indirectly, most or all sex-specifically expressed genes. TRA-1A probably directly regulates multiple genes involved in restricted aspects of sexual differentiation. One gene regulated by tra-1 is mab-3, which itself encodes a transcription factor that is required for male sexual differentiation. Specifically, MAB-3 functions in males to repress intestinal yolk production and to promote sensory ray development and also has functions in male behavior (see Yi, et al. and Ross, et al. abstracts). We have begun to use DNA microarray analysis and representational difference analysis (RDA) to identify tra-1 and mab-3 regulated genes. We have also used a hidden Markov model (HMM) computer algorithm to predict potential TRA-1A and MAB-3 binding sites in the C. elegans genome. By comparing the data obtained from each of these analyses we are attempting to identify the most likely tra-1 and mab-3 regulated genes, which can then be further tested. To find direct targets we are using three criteria: differential expression, a nearby DNA binding site for the regulator, and conservation of the binding site in C. briggsae. The DNA microarray includes fragments representing all of the predicted genes of the C. elegans genome. Comparison of adult N2 XX hermaphrodites to adult him-8 XO males (data of Ryu and Kim) identifies about 1,300 reproducibly male-enriched genes and 200 hermaphrodite-enriched genes (with a cutoff of statistically significant 3-fold difference). A similar comparison of mRNA from L4 N2 XX hermaphrodites and tra-2 (ts) XX pseudomales identifies about 200 sex-specific genes. Currently we are testing earlier developmental stages to generate a developmental profile of sex-specific gene expression. As a second approach to find sex-specific mRNAs, we used the cDNA subtraction method RDA to identify male-specific cDNAs from mRNAs differentially expressed between L4 N2 XX hermaphrodites and tra-2 (ts) XX pseudomales, confirming the differential expression by northern blotting and comparison to microarray data. This has identified six highly male-specific genes. Differentially expressed genes identified using microarrays and RDA that lie near conserved TRA-1A or MAB-3 binding sites are being further characterized as potential tra-1 and mab-3 targets.

Janton, Francis et al. (2017) International Worm Meeting "The DVA neuron promotes wakefulness via a cAMP-mediated mechanism."

Nelson, Matthew, Szurgot, Mary, Brown, Amelia, Sullivan, Nicole, Vance, Ryan, Janton, Francis

[

International Worm Meeting,

2017]

Caenorhabditis elegans display unique forms of sleep: developmentally timed sleep (DTS) and stress-induced sleep (SIS), which are regulated by overlapping and distinct mechanisms (Trojanowski et al., 2015). The cyclic adenosine monophosphate (cAMP)/Protein Kinase A (PKA) pathway promotes arousal in invertebrates and vertebrates (Crocker and Sehgal, 2010). This signaling pathway is downregulated during DTS in C. elegans (Belfer et al., 2013) and we show the same is true for SIS. To determine where cAMP/PKA functions during sleep we have been expressing and activating the near infrared light-activated adenylyl cyclase called IlaC, which converts ATP into cAMP in the presence of red light, in candidate neurons (Ryu et al., 2014). We have chosen this tool because, unlike blue light, red light does not wake worms up during sleep. We find that pan-neuronal activation of IlaC reduces both DTS and SIS. Induction of cAMP in either the motor neurons, command interneurons or the sleep-regulating interneuron RIA is not sufficient to reduce DTS or SIS. However, activation of IlaC in the DVA interneuron, by expressing it from the full twk-16 promoter or using a DVA-specific enhancer from the twk-16 promoter (Puckett Robinson et al., 2013), significantly reduces SIS, DTS and non-physiological quiescence induced by neuropeptide over-expression (Nelson et al. 2013 and 2014). This suggests that DVA may be a common wake-promoting neuron downstream of distinct sleep promoting circuits. To confirm DVA's place in the known circuitry, we have expressed a cAMP biosensor, Epac1-camps (Shafer et al., 2008) in DVA and are currently measuring cAMP levels during sleep. What lies downstream of the cAMP/PKA pathway during DTS and SIS is still unclear. The cAMP response element binding protein (CREB) is a transcription factor known to play a role in C. elegans sleep and arousal, as well as arousal in mammals (Graves et al., 2003). CRH-1 is the C. elegans CREB homologue; and crh-1 loss-of-function mutants display increased amounts of DTS (Singh et al., 2014), which we have observed as well. We show evidence that CRH-1 functions downstream of cAMP/PKA in the nervous system during DTS, and are currently testing if DVA is the wake-promoting site of action. Surprisingly, we find that crh-1 mutants have reduced SIS, thus cAMP/PKA promotes arousal after SIS in DVA via distinct mechanisms.

Jung, Yoonji et al. (2021) International Worm Meeting "A Golgi protein MON-2/MON2 mediates longevity via upregulating autophagy"

[

International Worm Meeting,

2021]

The Golgi apparatus is a crucial organelle for post-translational modification and transport of macromolecules, including proteins and lipids. Impaired functions of the Golgi complex cause various diseases but its role in organismal longevity remains elusive. Here, we show that an evolutionarily conserved Golgi protein MON-2, a mediator of trafficking between endosome and the Golgi, promotes longevity caused by inhibition of mitochondrial respiration. By performing quantitative proteomics followed by RNAi-based lifespan screen, we identified factors that are required for the extended lifespan of the respiration isp-1(qm150) and clk-1(qm30) mutants. Among them, we found that genetic inhibition of mon-2 by RNAi and mutation suppressed the longevity of the respiration mutants. We showed that other factors that mediate trafficking between the Golgi and the endosome, such as snx-3/sorting nexin 3, tbc-3/TBC1D22A and PAD-1/DOP1, were also required for the longevity of respiration mutants. Next, we asked how two organelles, the Golgi and mitochondria, communicated with each other for the regulation of longevity. We hypothesized that MON-2 and established pro-longevity factors coordinately mediate the longevity of mitochondrial mutants. We demonstrated that MON-2 was required for enhancing autophagy, a process essential for long lifespan of respiratory mutants. We found that the number of LGG-1 puncta, a reporter of autophagy, was increased by isp-1(qm150) and clk-1(qm30) but decreased by mon-2(xh22) mutation. We further showed that MON-2 was required for the long lifespan caused by several regimens that upregulate autophagy, such as mutations in insulin/IGF-1 receptor, daf-2(e1370), dietary restriction mimetic eat-2(ad1116) and food deprivation. We found that HLH-30/TFEB and BEC-1/Atg6, key regulators of autophagy, promoted longevity by acting together with MON-2. We then showed that mammalian MON2 also upregulated autophagy under starvation conditions by binding to GABARAP L2, a member of LC3 family proteins. Interestingly, we found that starvation induced the translocation of MON2 from the Golgi to recycling endosome, which may contribute to autophagosome formation in cultured mammalian cells. Thus, evolutionarily conserved MON-2/MON2 appears to promote longevity via upregulating autophagy. Altogether our study highlights the crucial roles of inter-organelle communications between mitochondria, the Golgi and autophagosome in the regulation of longevity.

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