Alcedo J et al. (2000) West Coast Worm Meeting "Temporal and spatial requirement of sensory cilia in the regulation of worm lifespan"

Apfeld J, Kenyon CJ, Hsin H, Dorman JB, Tsung BT, Albinder B, Alcedo J

[West Coast Worm Meeting, 2000]

C. elegans is an excellent organism in which to study the regulation of lifespan. Genetic analyses have already shown that an insulin/IGF-like hormonal control system, the DAF-2 pathway, regulates lifespan in the worm. However, many components of the pathway, whose existence has been inferred from previous studies (Apfeld and Kenyon, (1999). Nature 402, 804-809; and Hsin and Kenyon, (1999) Nature 399, 362-366) have not been identified. To search for more genes that would help to elucidate mechanisms that control lifespan in the worm, our group has done an EMS mutagenesis screen for long-lived worms and found 29 independent long-lived mutants. At least one of the mutants, mu377(IV), maps to and fails to complement the gene daf-10, which is required for the normal development of the worms sensory cilia. Apfeld and Kenyon (1999) have recently shown that worms defective in sensory cilia, including daf-10 mutants, live longer than normal worms, which suggests that the lifespan of C. elegans might be regulated by the perception of a signal(s) from the environment. mu377(IV) has a temperature-sensitive defect in its sensory cilia, which is linked to its temperature-sensitive lifespan phenotype. At the restrictive temperature, its lifespan is longer than wild-type and it exhibits a defect in its sensory cilia; whereas at the permissive temperature, its lifespan is the same as wild-type and it exhibits normal sensory cilia. Since the defect in the sensory cilia of mu377(IV) is reversible, we determined the temporal requirement for the gene product of mu377(IV) in regulating the lifespan of the worm. To gain insight into the spatial requirement for sensory perception in controlling the worms lifespan, we are also in the process of determining which sensory neurons are necessary to regulate its lifespan by expressing wild-type sensory genes in subsets of mutant sensory neurons.

J Alcedo et al. (1999) International C. elegans Meeting "Identification and characterization of long-lived mutants in C. elegans"

N Arantes-Oliveira, B Tsung, J Alcedo, H Hsin, D Garigan, B Albinder, J Apfeld, N Libina, C Kenyon

[International C. elegans Meeting, 1999]

C. elegans is an excellent organism in which to study the regulation of lifespan. Genetic analyses have already shown that an insulin/IGF-like hormonal control system, the DAF-2 pathway, regulates lifespan in the worm. However, many components of the pathway, whose existence has been inferred from previous studies (see abstracts by Apfeld and Kenyon and by Hsin and Kenyon, International Worm Meeting 1999), have not been identified. To search for more genes that would help to elucidate mechanisms that control lifespan in the worm, our group has done an EMS mutagenesis screen for long-lived worms and found 29 independent long-lived mutants. Two mutants fail to complement daf-2 , while one mutant fails to complement age-1 . Some of the remaining mutants form dauers at 27 degC but complement daf-2 or age-1 , and may identify new genes involved in regulating lifespan. Some of the other mutants may have defects in the sensory cilia as determined by the inability of their amphid sensory neurons to take up DiI (see abstract by Apfeld and Kenyon, International Worm Meeting 1999); and this defect has been linked to the long-life phenotype of at least one mutant. In addition, some of the mutants have a slow-growing phenotype and might be candidate clk alleles. We are currently mapping these mutations using a PCR-mapping strategy.

Mishra, S. et al. (2019) International Worm Meeting "Different sensory neurons modulate distinct steps in oogenesis in response to food quality."

Marbach, K., Alcedo, J., MISHRA, S.

[International Worm Meeting, 2019]

The sensory system integrates diverse environmental cues to regulate animal physiology. Likewise, sensory neurons in the worm Caenorhabditis elegans regulate various physiological processes, such as the reproductive patterns on different types of food sources. Previously, we have shown that worms fed E. coli CS180 produce fewer progeny compared to worms fed E. coli OP50 [1]. However, worms on CS180 have a faster rate of reproduction [1]. Now we show that the low progeny number on CS180 is due to an early onset of oogenesis, which is largely modulated by a pair of taste neurons known as ASJ. We also show that this onset is dependent on insulin signaling. CS180 also promotes faster reproduction rates through faster oocyte maturation rates. In contrast to the neurons that regulate the onset of oogenesis, we find that oocyte maturation is regulated primarily by the AWA olfactory neurons. Together our data indicate that specific sensory neurons detect precise environmental cues to modulate distinct steps in oogenesis-onset versus maturation-via two different pathways. Reference: [1] Maier W, Adilov B, Regenass M, Alcedo J (2010) A Neuromedin U Receptor Acts with the Sensory System to Modulate Food Type-Dependent Effects on C. elegans Lifespan. PLOS Biology 8(5): e1000376

Wolfgang Maier et al. (2008) European Worm Meeting "A putative neuropeptide receptor that senses food quality to inhibit longevity"

Martin Regenass, Bakhtiyor Adilov, Wolfgang Maier, Joy Alcedo

[European Worm Meeting, 2008]

The lifespan of C. elegans is influenced by its sensory system [1, 2], but. the mechanisms that underlie this sensory influence remain largely unknown.. The genome of the worm encodes a large number of predicted neuropeptide. receptors, which may modulate the information processed by the sensory. system and thus affect lifespan. Consistent with this hypothesis, we have. found that nmur-1, a gene encoding a receptor with homology to mammalian. neuromedin U receptors (NMURs), inhibits longevity. An nmur-1::GFP. reporter construct is expressed in neurons, including sensory neurons, and. the somatic gonad.. nmur-1 appears to act with the worm''s insulin/IGF-1 receptor, daf-2, to. inhibit longevity, but functions independent of the FOXO transcription. factor daf-16, which acts downstream of daf-2. In addition, unlike. mutations in many longevity-inhibiting genes, including daf-2, the deletion. of nmur-1 causes only subtle phenotypes in processes that require energy. expenditure. This suggests that nmur-1 plays a minor role in regulating. the overall metabolism of the worm. Interestingly, the lifespan phenotype. of nmur-1 is dependent on its bacterial food source. Thus, nmur-1 appears. to be involved in sensing food quality to influence lifespan.. References: [1] Apfeld, J., and C. Kenyon. 1999. Nature 402: 804 - 809.. [2] Alcedo, J., and C. Kenyon. 2004. Neuron 41: 45 - 55.

Wolfgang Maier et al. (2006) European Worm Meeting "Identification of Genes Involved in the Neural Regulation of Lifespan"

Martin Regenass, Joy Alcedo, Wolfgang Maier, Monique Thomas

[European Worm Meeting, 2006]

Wolfgang Maier, Martin Regenass, Monique Thomas and Joy Alcedo. Aging is influenced by several factors, which include the environment of the animal. For example, mutations that impair sensory function extend the lifespan of C. elegans, which suggests that lifespan, of at least this animal, is regulated by the perception of environmental cues (1). Specific sensory neurons appear to regulate lifespan, at least in part, through the insulin/IGF-1 pathway (1, 2). Since several putative insulin-like ligands are also expressed in these neurons (3), it is possible that an environmental signal(s) sensed by these neurons regulates the production of these ligands. To elucidate further the molecular mechanisms of the sensory influence on lifespan, we are carrying out an RNA-mediated interference screen for enhancers and suppressors of the lifespan phenotype of sensory mutant animals. As we identify genes involved in the sensory influence on lifespan, we will study their expression patterns using GFP-fusion reporter constructs to determine in which cells they function. We also plan to measure the lifespans of strains in which the particular gene was knocked out or overexpressed. Furthermore, we will conduct pertinent studies on how the gene products function, such as testing if the functions of these genes require each other or involve the daf-2 insulin/IGF-1 pathway or other signaling pathways in the worm known to influence its lifespan. References: (1) Apfeld, J., and C. Kenyon. 1999. Nature (Lond.). 402: 804 809; (2) Alcedo, J., and C. Kenyon. 2004. Neuron 41: 45 55; (3) Pierce, S. B., et al. 2001. Genes Dev. 15: 672 - 686.

Jun-ichi Aikawa (2001) International C. elegans Meeting "Molecular characterization of heparan sulfate/heparin N-deacetylase/N-sulfotransferase in worms"

Jun-ichi Aikawa

[International C. elegans Meeting, 2001]

Heparan sulfate binds and activates a large variety of growth factors, enzymes and extracellular matrix proteins. These interactions largely depend on the specific arrangement of sulfated moieties and uronic acid epimers within the chains. These oligosaccharide sequences are generated in a step-wise manner, initiated by the formation of a linkage tetrasaccharide which is then extended by copolymerization of alternating a1,4GlcNAc and b1,4GlcA residues. As the chains polymerize, they undergo a series of sulfation and epimerization reactions. The first set of modifications involves the removal of acetyl units from subsets of GlcNAc residues, and the addition of sulfate groups to the resulting free amino groups. These reactions are catalyzed by a family of enzymes designated as GlcNAc N-deacetylase/N-sulfotransferases (NDST), since they simultaneously. Four members of the family have been identified in vertebrates, with single orthologs present in Drosophila and C. elegans. We have revealed tissue-specific expression pattern and unique enzymatic properties of these four isozymes1,2). In fly, loss of NDST (sulfateless) results in unsulfated chains and defective signaling by multiple growth factors and morphogens. I reconstituted cDNA for worm NDST from EST clones and 5' RACE products. Enzymatic activities will be discussed. 1) Aikawa, J. & Esko, J. D J. Biol. Chem. 274, 2690-2695 (1999) 2) Aikawa, J., Grobe, K., Tsujimoto, M. & Esko, J. D J. Biol. Chem. 276, 5876-5882 (2001)

Maier W et al. (2010) Aging, Metabolism, Stress, Pathogenesis, and Small RNAs, Madison, WI "The Neuropeptide Receptor nmur-1 Mediates the Sensory Influence on Lifespan in a Food Type-Dependent Manner"

Alcedo J, Maier W, Regenass M, Adilov B

[Aging, Metabolism, Stress, Pathogenesis, and Small RNAs, Madison, WI, 2010]

The sensory system has previously been shown to mediate the effects of food intake on lifespan. However, the lifespan of an animal is affected not only by the level of its food intake but also by the type of its food source. Now we provide evidence that the sensory system also alters lifespan in response to specific food types as opposed to different food levels. We show that different subsets of sensory neurons modulate the effects of different E. coli food sources on C. elegans lifespan. We also find that sensory neurons act with nmur-1, a homolog of mammalian neuromedin U receptors, to influence lifespan in a food source-dependent manner. Wild-type nmur-1, which is expressed in the somatic gonad, sensory neurons and interneurons, shortens lifespan only on specific E. coli strains--an effect that depends on short E. coli lipopolysaccharide (LPS) structure. Moreover, unlike the effect of restricting food levels, the food type-dependent effect of nmur-1 on lifespan can be uncoupled from its effects on feeding rate, development and reproduction. Together our data suggest not only that sensory neurons recognize food types to affect lifespan but also that the nmur-1 neuropeptide signaling pathway is involved in this process. Furthermore, our study leads us to propose that the two forms of dietary influence on lifespan--food type-dependence and food-level restriction--employ distinct, but overlapping, mechanisms. Thus, nmur-1 appears to process information from specific food cues, like the E. coli LPS structure, to influence lifespan and other aspects of physiology.

Maier W et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "A Neuromedin U receptor Acts with the Sensory System to Modulate Food Type-Dependent Effects on C. elegans Lifespan"

Regenass M, Alcedo J, Maier W, Adilov B

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

The sensory system has previously been shown to mediate the effects of food intake on lifespan. However, the lifespan of an animal is affected not only by the level of its food intake but also by the type of its food source. Thus, we have examined the role of the sensory system in the food-source influence on C. elegans lifespan and the signaling pathway(s) that might be involved in this process. We find that different subsets of sensory neurons modulate the effects of different E. coli food sources on C. elegans longevity. We also show that the sensory system acts with a homolog of mammalian neuromedin U receptors, nmur-1, to affect lifespan in a food source-dependent manner. Wild-type nmur-1, which is expressed in the somatic gonad, sensory neurons and interneurons, shortens lifespan only on specific E. coli strains an effect that is dependent on the type of E. coli lipopolysaccharide (LPS) structure. Moreover, unlike the effect of food-level restriction, the food type-dependent effect of nmur-1 on lifespan can be uncoupled from its effects on feeding rate, development and reproduction. Together our data suggest that (i) sensory neurons recognize food types to affect lifespan and (ii) the nmur-1 neuropeptide signaling pathway is involved in this process. Furthermore, our study leads us to propose that the two forms of dietary influence on lifespan food type-dependence and food-level restriction employ distinct, but overlapping, mechanisms. Thus, nmur-1 appears to process information from specific food cues, like the E. coli LPS structure, to influence lifespan and other aspects of physiology.

Husson, Steven J. et al. (2011) International Worm Meeting "C. elegans mutants defective in neuropeptide amidation enzymes are abnormal in egg-laying behavior."

Landuyt, Bart, Schoofs, Liliane, Gottschalk, Alexander, Horvitz, H.Robert, Temmerman, Liesbet, Husson, Steven J., Ringstad, Niels, Meelkop, Ellen

[International Worm Meeting, 2011]

Egg laying has mainly been studied at the behavioral, neuronal and neurochemical levels, but little is known about the biochemical control of the relevant neuropeptidergic signaling systems. Biosynthesis of endogenous peptides requires processing enzymes, such as proprotein convertase 2, which is encoded by egl-3 (1, 2), and a carboxypeptidase encoded by egl-21 (3, 4). Mutants defective in these genes have egg-laying defects, consistent with the finding that FMRFamide-like peptides (FLPs) have been linked to egg laying behavior. C. elegans enzymes that carry out the last step in the production of biologically active peptides, the carboxy-terminal amidation reaction, have not been characterized. This multistep reaction involves hydroxylation of the glycine a-carbon by a peptidyl-a-hydroxylating monooxygenase (PHM), followed by a cleavage reaction performed by peptidyl a-hydroxyglycine a-amidating lyase (PAL) to generate a glyoxylate molecule and the a-amidated peptide. In vertebrates, both enzymatic activities responsible for the carboxyterminal amidation reaction are contained in one bifunctional enzyme, peptidylglycine a-amidating monooxygenase (PAM). By contrast, invertebrates generally express two separate enzymes encoded by two different genes. Here we report the identification and characterization of C. elegans amidating enzymes using bioinformatics to identify candidate genes and mass spectrometry to compare the neuropeptides in wild-type and newly generated mutants. Mutants lacking a functional PHM displayed an altered neuropeptide profile, showed impaired egg laying behavior and had a decreased brood size. Interestingly, PHM mutants still displayed fully processed amidated neuropeptides, probably as a result of the presence of a bifunctional PAM, the main amidating enzyme in vertebrates. Our data indicate the existence of a robust complementation system for the amidation reaction of neuropeptides in nematodes and suggest the involvement of amidated neuropeptides in egg laying. (1) S. J. Husson et al., J. Neurochem. 98, 1999 (2006); (2) J. Kass et al., J. Neurosci. 21, 9265 (2001); (3) S. J. Husson et al., J. Neurochem. 102, 246 (2007); (4) T. C. Jacob, J. M. Kaplan, J. Neurosci. 23, 2122 (2003).

Crittenden SL et al. (1997) International C. elegans Meeting "TEMPERATURE-SENSITIVE REPRESSION OF TRANSGENES CARRYING A fem-3(gf) MUTANT 3'UTR"

Crittenden SL, Kimble JE

[International C. elegans Meeting, 1997]

We are developing a method to control gene expression in a temperature dependent manner. Our strategy is to regulate reporter expression with a well-defined promoter at the 5' end and a mutant fem-3 3'UTR at the 3' end. The fem-3(gf) mutations map to the fem-3 3'UTR and release fem-3 from post-transcriptional repression at 25 C, but not at 15 C (1,2). We have tested expression of a lag-2 promoter::GFP construct that carries either a strong or a weak fem-3(gf) 3'UTR. The lag-2 promoter drives expression in the distal tip cells of adults (3-5). We find that transgenes express GFP at much lower levels at 15 C than at 25 C when carrying a fem-3(gf) 3'UTR. We are currently trying to optimize repression at 15 C using the lag-2 promoter and GFP as a reporter. In addition, we are testing whether temperature sensitive repression can be achieved in other tissues, and we are starting to explore the biological activity of various proteins expressed in the distal tip cell. 1. Ahringer, J., and Kimble, J. (1991). Nature 349, 346-348. 2. Barton, M. K., Schedl, T. B., and Kimble, J. (1987). Genetics 115, 107-119. 3. Fitzgerald, K., and Greenwald, I. (1995). Development 121, 4275-4282. 4. Gao, D. and J. Kimble, midwest worm meeting 1996. 5. Henderson, S. T., Gao, D., Lambie, E. J., and Kimble, J. (1994). Development 120, 2913-2924.