Kruempel, Joseph et al. (2015) International Worm Meeting "The heterochronic transcription factor lin-14 promotes dauer arrest."

Hu, Patrick, Kruempel, Joseph, Flibotte, Stephane, Chen, Albert, Moerman, Donald

[International Worm Meeting, 2015]

In C. elegans, reducing insulin/insulin-like-growth-factor signaling (IIS) through mutations in the insulin/insulin-like-growth-factor receptor (IGFR) homologue daf-2 increases activity of the FoxO transcription factor DAF-16, which promotes increased longevity and arrest in an alternative larval stage called dauer. Activation of IIS causes increased phosphorylation of DAF-16/FoxO by AKT-1, which promotes cytoplasmic sequestration of DAF-16/FoxO. We have discovered the EAK (enhancer of akt-1 dauer arrest) pathway, which inhibits daf-16/FoxO in parallel to the canonical IIS pathway without affecting DAF-16/FoxO nuclear localization. The most downstream component of the EAK pathway is eak-7, a conserved plasma membrane-associated protein of unknown function.To characterize the mechanism by which the EAK pathway inhibits DAF-16/FoxO, we screened for mutations which suppress eak-7;akt-1 dauer arrest (seak mutations). This screen has identified a mutation in the heterochronic transcription factor lin-14 as a suppressor of eak-7;akt-1 dauer arrest. Wild type lin-14 promotes gene expression and cell division programs specific to the L1 larval stage and prevents precocious expression of programs specific to later stages. We have shown that the dauer arrest phenotype of eak-7;akt-1 mutants is suppressed by lin-14 mutation and lin-14(RNAi). Dauer arrest of daf-2/IGFR mutants is suppressed by lin-14 mutation in combination with lin-14(RNAi). These data suggest a novel role for lin-14 in the insulin/insulin like growth factor signaling pathway.

Arena JP (1994) Parasitol Today "Expression of Caenorahbditis elegans messenger RNA in Xenopus oocytes: A model systems to study the mechanism of action of avermectins."

Arena JP

[Parasitol Today, 1994]

It has recently been shown that Xenopus oocytes injected with mRNA from the free-living nematode Caenorhabditis elegans express avermectin-sensitive chloride channels(1). Joseph Arena here reviews whet is known about the mechanism of action of avermectin and how these recent results relate to the mechanism in nematodes.

Dumas, Kathleen et al. (2013) International Worm Meeting "A novel role for the p120RasGAP family member GAP-3 in dauer regulation."

Dumas, Kathleen, Hu, Patrick, Flibotte, Stephane, Moerman, Donald, Kruempel, Joseph

[International Worm Meeting, 2013]

p120RasGAP family members antagonize Ras/MAP kinase (MAPK) signaling by accelerating GTP hydrolysis by Ras GTPases. In C. elegans, the p120RasGAP family member GAP-3 antagonizes Ras/MAPK signaling in vulval and germline development. Here we describe a novel role for GAP-3 in the control of dauer arrest. To identify new regulators of the FoxO transcription factor DAF-16, we have embarked upon a search for suppressors of the eak-7;akt-1 dauer-constitutive phenotype (seak mutants). One spontaneous eak-7;akt-1 suppressor contained a missense mutation in the GTPase-activating domain of GAP-3. Two independent loss-of-function gap-3 alleles also suppress eak-7;akt-1 dauer arrest, confirming gap-3 as a bonafide seak gene. Mutations in gap-1 and gap-2, which encode the other predicted RasGAPs in the C. elegans genome, did not suppress eak-7;akt-1 dauer arrest. Surprisingly, a let-60/Ras gain-of-function mutation did not phenocopy gap-3 mutation, suggesting that GAP-3 controls dauer arrest in a LET-60/Ras-independent manner. However, deletion of lip-1, which encodes a dual-specificity MAP kinase phosphatase, suppressed the eak-7;akt-1 dauer-constitutive phenotype to the same extent as gap-3 mutation, suggesting that MAP kinase activation is sufficient to suppress eak-7;akt-1 dauer arrest. Our findings implicate a novel LET-60/Ras-independent MAPK signaling pathway in dauer regulation that may act by regulating DAF-16/FoxO activity.

Teixeira-Castro A et al. (2015) Brain "Serotonergic signalling suppresses ataxin 3 aggregation and neurotoxicity in animal models of Machado-Joseph disease."

Bessa C, Duarte-Silva S, Maciel P, Bessa J, Silverman RB, Miranda A, Kang S, Summavielle T, Oliveira S, da Silva Santos L, Neto MF, Esteves S, Brielmann RM, Neves-Carvalho A, Teixeira-Castro A, Oliveira P, Morimoto RI, Silva-Fernandes A, Jalles A

[Brain, 2015]

Polyglutamine diseases are a class of dominantly inherited neurodegenerative disorders for which there is no effective treatment. Here we provide evidence that activation of serotonergic signalling is beneficial in animal models of Machado-Joseph disease. We identified citalopram, a selective serotonin reuptake inhibitor, in a small molecule screen of FDA-approved drugs that rescued neuronal dysfunction and reduced aggregation using a Caenorhabditis elegans model of mutant ataxin 3-induced neurotoxicity. MOD-5, the C. elegans orthologue of the serotonin transporter and cellular target of citalopram, and the serotonin receptors SER-1 and SER-4 were strong genetic modifiers of ataxin 3 neurotoxicity and necessary for therapeutic efficacy. Moreover, chronic treatment of CMVMJD135 mice with citalopram significantly reduced ataxin 3 neuronal inclusions and astrogliosis, rescued diminished body weight and strikingly ameliorated motor symptoms. These results suggest that small molecule modulation of serotonergic signalling represents a promising therapeutic target for Machado-Joseph disease.

Chen, Albert et al. (2015) International Worm Meeting "New longevity genes revealed by integrative analysis of daf-2 and glp-1 mutants."

Pande, Manjusha, Chen, Albert, McEachin, Richard, Hu, Patrick, Grant, Ana, Waters, Ian, Guo, Chunfang, Kruempel, Joseph

[International Worm Meeting, 2015]

FoxO transcription factors promote longevity across taxa. How they do so remains poorly understood. In C. elegans, the FoxO transcription factor DAF-16 extends life span in the contexts of reduced DAF-2 insulin-like signaling and germline ablation. To prioritize a subset of DAF-16/FoxO target genes for phenotypic analysis, we performed whole transcriptome profiling on two distinct daf-2 mutants and glp-1(e2141) mutants lacking a germline in the context of wild-type daf-16 and two daf-16 mutations that fully suppress life span extension. Integration of phenotypic data with transcriptome profiles defined a set of 46 DAF-16/FoxO target genes, the differential expression of which is associated with longevity (dal genes). daf-2 RNAi life span assays on loss-of-function mutants corresponding to nineteen dal genes revealed that mutation of five dal genes significantly reduces life span extension induced by daf-2 RNAi. One of these genes encodes an acetylcholinesterase homolog of unknown function. Our results underscore the efficacy of integrative analysis in defining tractable sets of DAF-16/FoxO target genes for detailed interrogation.

Allen, Parker et al. (2021) International Worm Meeting "Role of the conserved cholinesterase family member CEST-1.1 and its modular metabolite products in life span control"

Curtis, Brian, Kruempel, Joseph, Hu, Patrick, Wrobel, Chester, Allen, Parker, Schroeder, Frank, Higgins-Chen, Albert

[International Worm Meeting, 2021]

Although the role of the C. elegans FoxO transcription factor DAF-16 in promoting longevity is well established, how DAF-16/FoxO extends life span remains poorly understood. While the identities of thousands of DAF-16/FoxO target genes are known, mechanistic links between DAF-16/FoxO-dependent regulation of specific genes and DAF-16/FoxO-dependent life span extension are lacking. We have discovered that a conserved cholinesterase family member encoded by the DAF-16/FoxO target gene cest-1.1 is required for full life span extension in the context of reduced DAF-2 insulin-like signaling and sufficient to extend life span when expressed in a wild-type background. A functional CEST-1.1::GFP fusion protein is expressed specifically in the intestine and localizes to the apical plasma membrane. Comparative metabolomic analysis using HPLC-high resolution mass spectrometry revealed that CEST-1.1 is required for the biosynthesis of two structurally novel nucleoside-like ascarosides termed uglas#1 and uglas#11. These surprising findings support a role for an unprecedented class of metabolites in life span control and orthogonally expand the landscape of biogenic small molecules that may influence aging.

Kawaguchi Y et al. (1994) Nat Genet "CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1."

Kawaguchi Y, Inoue M, Nishimura M, Kawakami H, Okamoto T, Katayama S, Nakamura S, Aizawa M, Akiguchi I, Taniwaki M

[Nat Genet, 1994]

We have identified a novel gene containing CAG repeats and mapped it to chromosome 14q32.1, the genetic locus for Machado-Joseph disease (MJD). In normal individuals the gene contains between 13 and 36 CAG repeats, whereas most of the clinically diagnosed patients and all of the affected members of a family with the clinical and pathological diagnosis of MJD show expansion of the repeat-number (from 68-79). Southern blot analyses and genomic cloning demonstrates the existence of related genes. These results raise the possibility that similar abnormalities in related genes may give rise to diseases similar to MJD.

Rodrigues AJ et al. (2007) FASEB J "Functional genomics and biochemical characterization of the C. elegans orthologue of the Machado-Joseph disease protein ataxin-3."

Ailion M, Rodrigues AJ, Maciel P, Geschwind DH, Coppola G, Santos C, Costa MD, Sequeiros J

[FASEB J, 2007]

Machado-Joseph disease (MJD) is the most common dominant spinocerebellar ataxia. MJD is caused by a CAG trinucleotide expansion in the ATXN3 gene, which encodes a protein named ataxin-3. Ataxin-3 has been proposed to act as a deubiquitinating enzyme in the ubiquitin-proteasome pathway and to be involved in transcriptional repression; nevertheless, its precise biological function(s) remains unknown. To gain further insight into the function of ataxin-3, we have identified the Caenorhabditis elegans orthologue of the ATXN3 gene and characterized its pattern of expression, developmental regulation, and subcellular localization. We demonstrate that, analogous to its human orthologue, C. elegans ataxin-3 has deubiquitinating activity in vitro against polyubiquitin chains with four or more ubiquitins, the minimum ubiquitin length for proteasomal targeting. To further evaluate C. elegans ataxin-3, we characterized the first known knockout animal models both phenotypically and biochemically, and found that the two C. elegans strains were viable and displayed no gross phenotype. To identify a molecular phenotype, we performed a large-scale microarray analysis of gene expression in both knockout strains. The data revealed a significant deregulation of core sets of genes involved in the ubiquitin-proteasome pathway, structure/motility, and signal transduction. This gene identification provides important clues that can help elucidate the specific biological role of ataxin-3 and unveil some of the physiological effects caused by its absence or diminished function.--Rodrigues, A-J., Coppola, G., Santos, C., do Carmo Costa, M., Ailion, M., Sequeiros, J., Geschwind, D. H., Maciel, P. Functional genomics and biochemical characterization of the C. elegans orthologue of the Machado-Joseph disease protein ataxin-3.

Pohl F et al. (2024) MicroPubl Biol "Pharmacological inhibition of acetylcholinesterase improves the locomotion defective phenotype of a SCA3 C. elegans model."

Maciel P, Pohl F, Teixeira-Castro A, Lindsay-McGee V, Kong Thoo Lin P

[MicroPubl Biol, 2024]

Inhibition of acetylcholinesterase (AChE) is a common used treatment option for Alzheimer's disease. However, there has been limited research on the potential use of AChE inhibitors for the treatment of Machado-Joseph disease (MJD)/Spinocerebellar Ataxia 3 (SCA3), in spite of the positive results using AChE inhibitors in patients with other inherited ataxias. MJD/SCA3, the most common form of dominant Spinocerebellar Ataxia worldwide, is caused by an expansion of the polyglutamine tract within the ataxin-3 protein, and is characterized by motor impairments. Our study shows that administration of the AChE inhibitor neostigmine is beneficial in treating the locomotion defective phenotype of a SCA3/MJD model of <i>C. elegans</i> and highlights the potential contribution of AChE enzymes to mutant ataxin-3-mediated toxicity.

Teixeira-Castro A et al. (2011) Hum Mol Genet "Neuron-specific proteotoxicity of mutant ataxin-3 in C. elegans: rescue by the DAF-16 and HSF-1 pathways."

Oliveira JF, Vilaca JL, Brignull HR, Ailion M, Teixeira-Castro A, Dias N, Neves-Carvalho A, Maciel P, Morimoto RI, Jalles A, Rodrigues P

[Hum Mol Genet, 2011]

The risk of developing neurodegenerative diseases increases with age. Although many of the molecular pathways regulating proteotoxic stress and longevity are well characterized, their contribution to disease susceptibility remains unclear. In this study, we describe a new Caenorhabditis elegans model of Machado-Joseph disease pathogenesis. Pan-neuronal expression of mutant ATXN3 leads to a polyQ-length dependent, neuron subtype-specific aggregation and neuronal dysfunction. Analysis of different neurons revealed a pattern of dorsal nerve cord and sensory neuron susceptibility to mutant ataxin-3 that was distinct from the aggregation and toxicity profiles of polyQ-alone proteins. This reveals that the sequences flanking the polyQ-stretch in ATXN3 have a dominant influence on cell-intrinsic neuronal factors that modulate polyQ-mediated pathogenesis. Aging influences the ATXN3 phenotypes which can be suppressed by the downregulation of the insulin/insulin growth factor-1-like signaling pathway and activation of heat shock factor-1.