J Alex Parker et al. (2005) International Worm Meeting "Defining sirtuin activation as a neuroprotective strategy in models of Huntingtons Disease"

Emmanuel Lambert, J Alex Parker, Christian Neri, Cendrine Tourette, Helene Catoire, Margarita Arango, Salima Abderhamane

[International Worm Meeting, 2005]

Several reports suggest that the regulation of signal transduction and transcription is central to Huntingtons Disease (HD) pathogenesis and modification. We previously generated C. elegans transgenics expressing N-terminal huntingtin in touch receptor neurons, a model system that shows polyglutamine-dependent neuronal dysfunction and axonal dystrophy. We performed a genetic analysis of the cytotoxic pathways involved in this model. We found that Sir2 activation through increased sir-2.1 dosage or treatment with the sirtuin activator resveratrol specifically rescued early neuronal dysfunction phenotypes induced by mutant polyglutamines, two effects dependent on the transcription factor daf-16/FOXO. Additionally, resveratrol showed mutant polyglutamine-specific rescue of cell death in neuronal cells derived from HdhQ111 knock-in mice, an effect abolished by the co-incubation with sirtuin blockers. Sirtuin activation may thus protect against mutant polyglutamines. Additional studies will be needed to understand further the molecular basis of the neuroprotection elicited by sirtuin activation. Our data suggest that sirtuin activation may have therapeutic potential for HD and, potentially, other polyglutamine expansion neurodegenerative diseases.

Parker, J Alex et al. (2011) International Worm Meeting "Neuroprotection by Sirtuin sir-2.1 from Expanded Polyglutamines Requires b-catenin in C. elegans and the Age-at-Onset of Huntington's Disease is Modified by the b-catenin Repressor GSK-3b."

Tourette, Cendrine, Tissenbaum, Heidi, Durr, Alexandra, Mukhopadhyay, Arnad, Orth, Michael, Dolbeau, Guillaume, Maison, Patrick, Darbois, Aurelie, Orfila, Anne-marie, Menet, Sophie, Swenke, Susanne, Offner, Nicolas, Neri, Christian, Vasquez-Manrique, Rafael, Bachoud-Levi, Anne-Catherine, Brice, Alexis, Parker, J Alex

[International Worm Meeting, 2011]

One of the current challenges of neurodegenerative disease research is to determine whether pathways relevant in either development or as a function of age contribute to neuron survival and thereby contribute to the pathogenic process in human disease. Using a C. elegans model that recapitulates an early phase of expanded polyglutamine (polyQ) neurotoxicity, we previously reported that increased dosage of sirtuin sir-2.1/SIRT1 is neuroprotective, and requires the longevity-promoting factor daf-16/FoxO. Here, we report this neuroprotective effect also requires bar-1/b-catenin, a downstream effector of canonical Wnt that also acts as a DAF-16/FOXO partner, and ucp-4, a DAF-16 regulated gene that encodes the sole mitochondrial uncoupling protein (UCP) in nematodes. These results fit with a previously-proposed mechanism in which the SIR-2.1 and b-catenin pathways converge onto DAF-16 to regulate cell survival. Consistent with these effects in nematodes, survival of mutant-huntingtin striatal cells derived from the HdhQ111 knock-in mice was enhanced with SIRT1 overexpression. In addition, siRNAs of b-catenin enhanced cell death, and these effects were accompanied by the modulation of neuronal UCP (UCP2, UCP4) expression levels. Finally, we further extend these findings where we identify single nucleotide polymorphism in GSK-3b, a major b-catenin repressor, modifies the age-at-onset of motor symptoms in two well-characterized HD cohorts. Our results suggest that FOXO interactors regulate early stages of expanded polyQ toxicity and lead to GSK-3b modulation of the pathogenic process in HD patients.

J Alex Parker et al. (2001) International C. elegans Meeting "The C. elegans Homologue of Human Huntingtin Interacting Protein 1 has Multiple Roles"

Ann M Rose, J Alex Parker

[International C. elegans Meeting, 2001]

The HIP1/SlA2 family of genes have been ascribed numerous functions including maintenance of the cortical actin cytoskeleton, endocytosis, vesicle trafficking, RNA stability and apoptosis. Human HIP1 is reported to have a pro-aptotic function and may contribute to the etiology of Huntington disease. The majority of the work with this family of genes has come from mammalian biochemistry and yeast genetics. Analysis of this gene family in a metazoan animal system has not been fully explored. We have used C. elegans to study the role of the nematode homologue, CeHIP1, in the development of an animal system. CeHIP1 is found in several tissues of adult animals including the germline, somatic gonad and pharynx. RNAi results in reduced fecundity; treated animals have a decreased brood size and lay a large number of unfertilized oocytes. Also, the pharynxes of treated adult animals are deformed. We have evidence that the locus is dose sensitive, with overexpression being toxic to the animal. We beleive the study of CeHIP1 may provide a good model to understand the function of human HIP1. Both genes show restricted expression (HIP1 in the central nervous system and testes, CeHIP1 as described) and have dose sensitive toxic effects. This is the first description of this gene family in animal system.

Alex Parker et al. (2006) Neuronal Development, Synaptic Function, and Behavior Meeting "Studying the modifier genes of neuronal cell response to mutant huntingtin expression in C. elegans"

Maryline Mage, Christian Neri, Sabine Cloax, Beate Gertsbrein, Alex Parker, Salima Abderrahmane, Cendrine Tourette, Emmanuel Lambert

[Neuronal Development, Synaptic Function, and Behavior Meeting, 2006]

Huntington"s disease (HD) is a neurodegenerative disease caused by polyglutamine expansion in huntingtin. Although HD is inherited, its age of onset shows great variability, suggesting neuronal dysfunction and death in HD is influenced by modifier genes. To study how the neuronal cell may respond to mutant htt, we have developed C. elegans transgenics that overexpress mutant N-terminal htt fused to fluorescent proteins in touch receptor neurons. This model shows neuronal dysfunction without cell death, an effect accompanied by aggregate formation and dystrophy of neuronal processes (Parker et al., PNAS 2001). To study the pathways underlying these transgenic phenotypes, we use a combination of C. elegans mutants, RNAi screens, microarray analysis, and physiological analysis. This effort has led us to identify sirtuin activation as a neuroprotective mechanism against the effects of mutant htt expression, an effect mediated by daf-16/FOXO, (Parker et al., Nature Genetics 2005). Our findings indicated that modulators of organismal longevity like sir2 and FOXO may modify early-stage pathogenesis of neurodegenerative diseases, defining a new strategy with therapeutic potential. We will present an update on the progress made with our models in better understanding how mutant htt may be toxic to the neuronal cell and how neuroprotection may be achieved.

Alex Parker et al. (2002) European Worm Meeting "A C. elegans model of neuronal dysfunction in Huntington's Disease: Expanded polyglutamines cause severe neuronal phenotypes without cell death."

Christian Neri, Emmanuel Lambert, Alex Parker

[European Worm Meeting, 2002]

Proteins with expanded polyglutamine repeats cause Huntington's Disease (HD) and several other neurodegenerative disorders. HD is a dominant neurodegenerative disorder caused by polyglutamine expansion in the protein huntingtin. HD pathogenesis appears to involve the production of a mutated amino terminal fragment, cytoplasmic and nuclear aggregates, and abnormal activity of huntingtin interactor proteins essential to neuronal survival. Before cell death, neuronal dysfunction may be an important stage of HD pathogenesis. The number of proteins and genetic pathways implicated in HD is large and is growing. Simple model organisms may provide a convenient setting in which to manipulate and decipher polyglutamine mediated neuronal toxicity. We have used Caenorhabditis elegans to investigate the effects of expressing normal and mutant N-terminal huntingtin fused to fluorescent marker proteins in a portion of the nematode nervous system responsible for touch reception. Mutated huntingtin (128 Glns) produced a loss of touch response at the tail at high penetrance. Similar perinuclear deposits and faint nuclear accumulation of fusion proteins was observed for normal and expanded polyglutamine containing proteins. In contrast, significant deposits and morphological abnormalities in the touch receptor PLM cell axons were observed in animals expressing 128 glutamines. Neuronal cell death was not detected. These animals indicate that significant neuronal dysfunction can occur without cell death and may be induced by expanded polyglutamines and may correlate with axonal insult and not cell body aggregates.

Alex J Parker et al. (2003) International Worm Meeting "C. elegans as a model to study the pathogenesis and therapy of Huntingtons disease"

Abderrahmane Salima, Neri Christian, Lambert Emmanuel, Alex J Parker, Holbert Sebastien

[International Worm Meeting, 2003]

C. elegans amenability to genetic analyses and pharmacological screens may uncover aspects of the toxicity of human disease-associated proteins difficult to manipulate in vivo by other means. We have validated a worm-based approach to the study of Huntington's disease pathogenesis. We have observed that huntingtin, the HD protein, is able to interact with C. elegans proteins, and that human homologs of huntingtin interactors in worms may be involved in HD pathogenesis, as shown for the transcriptional regulator CA150, a candidate modifier gene in HD. We have described a transgenic C. elegans model of polyglutamine-dependent neuronal dysfunction without cell death. In this model, polyQ-expanded N-terminal huntingtin fused to fluorescent reporter proteins produces a significant mechanosensory defect at the tail. This phenotype partially correlates with aggregation of fusion proteins in neuronal processes and abnormal morphology of neuronal cell axons. This phenotype can be genetically suppressed with or without a reduction of aggregation, and genetic suppressors are being characterized. As part of a multi-assay neurodegeneration drug screening program coordinated by the NINDS, we have tested a collection of 1040 drugs in our transgenic animals. We have detected a manageable number of confirmed hits that show a dose-dependent restoration of touch sensitivity at the tail. One of these compounds appeared to significantly reduce aggregation in neuronal processes and abnormal morphology of axons in a dose-dependent manner. Our drug screening data suggest that the use of worm mechanosensation allows for a sensitive detection and validation of active compounds, which may be instructive in selecting drug leads.

Tauffenberger, Arnaud et al. (2009) International Worm Meeting "Age-dependent modification of expanded CAG toxicity in simple C. elegans models."

Tauffenberger, Arnaud, Bel-Hadj, Samar, Parker, Alex

[International Worm Meeting, 2009]

Arnaud Tauffenberger1,2,3, Samar Bel-Hadj1, Alex Parker1,2, 3 1CRCHUM, 2Centre of Excellence in Neuromics, 3Department de pathologie et biologie cellulaire, Universite da Montreal, Montreal, Quebec, Canada The expansion of CAG trinucleotides coding for glutamine is the cause of at least nine late-onset neurodegenerative diseases. The expanded CAG (expCAG) diseases may have some pathogenic mechanisms in common as the disease threshold for all of these disorders is around 40 CAG repeats and they display misfolded intracellular protein aggregation phenotypes. We have turned to the model organism C. elegans to explore two areas of interest: 1. Age-dependent toxicity: Although the expCAG diseases show anticipation, the size of CAG repeat only partially correlates with the variation in age-of-onset. Evidence suggests that even for these single trait neurodegenerative diseases, disease onset and progression may have additional environmental and genetic components. Using C. elegans transgenic worms expressing expCAG in neurons we are exploring the links between aging and late-onset neurodegeneration. We hypothesize that genes regulating longevity, stress response, their associated signaling pathways and downstream effectors may encode new therapeutic targets for age-dependent proteotoxicity in humans. 2. Mechanisms of expCAG toxicity: Long homopolymeric CAG nucleotide stretches are unstable and may be prone to translation errors. Mistranslation of expCAG to alternate reading frames may produce hybrid proteins with additional toxicity. We have created transgenic strains to investigate this phenomenon. A summary of our data and recent findings will be presented.

Schmeisser, Kathrin et al. (2017) International Worm Meeting "Neuronal nicotinamide-N-methyltransferase controls metabolism, behavior, and aging by regulating neuronal autophagy."

Schmeisser, Kathrin, Parker, Alex

[International Worm Meeting, 2017]

The enzyme nicotinamide N-methyl-transferase (NNMT) is an essential contributor in various important epigenetic, reproductive, and metabolic processes. It plays a role in healthy aging, cellular stress response and resistance, and it regulates weight gain and the prevalence of obesity, among others. Although it is expressed and functionally active in the brain, its role in neurons remains obscure. This is surprising given that in vitro studies have shown NNMT to be a potential risk factor for psychiatric diseases like schizophrenia and neurodegeneration, especially in dopaminergic neurodegeneration typical of Parkinson's disease. Neurodegeneration is a pervasive major risk for increased mortality in the elderly. Here, we studied the role of neuronal NNMT in vivo using C. elegans. The nematodal ortholog of human NNMT is ANMT-1. In contrast to most in vitro studies, we found neuronal ANMT-1/NNMT overexpression to be neuroprotective in wild type and various disease models as the animals age. ANMT-1/NNMT uses methyl groups from S-adenosyl-methionine (SAMe). As the most important methyl group donor in the cell, SAMe also provides methyl groups for the methyltransferase B0285.4, the C. elegans ortholog of the human leucine carboxyl methyltransferase 1 (LGMT1). ANMT-1/NNMT titrates methyl groups from B0285.4/LGMT1, reducing its catalytic capacities. B0285.4/LGMT1 targets NPRL-2 (human NPR2-like, GATOR1 complex subunit), a known regulator of autophagy and cell growth. Autophagy is activated by neuronal overexpression of ANMT-1/NNMT, which acts by "clearing up" misfolded, dysfunctional and aggregated proteins within the neurons, maintaining proteostasis and healthy neuronal function in age. Furthermore, neuronal expression of ANMT-1/NNMT mediates increased neurotransmitter release, which may act as an endocrine-like signal in the whole animal to control metabolism, behavior, and extend lifespan. This study shows for the first time that ANMT-1/NNMT may contribute to neuronal health in vivo based on its direct or indirect regulation of cellular processes such as the induction of autophagy and endocrine-like signalling, which are critical for neuronal homeostasis, ultimately curtailing neurodegeneration, all the while promoting healthy aging.

Vaccaro, Alexandra et al. (2011) International Worm Meeting "Development of C. elegans models for Amyotrophic Lateral Sclerosis."

Vaccaro, Alexandra, Tauffenberger, Arnaud, Parker, Alex

[International Worm Meeting, 2011]

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease characterized by a progressive and selective loss of motor neurons in the brain stem, the motor cortex and the spinal cord. The progression of ALS is marked by fatal paralysis and respiratory failure leading to death within 2 to 5 years. Unfortunately, to date there is no effective treatment known to slow or halt disease progression. Two recently discovered causative genes for ALS, TDP-43 (TAR DNA Binding Protein 43) and FUS/TLS (Fused in Sarcoma/Translocated in Liposarcoma), are under further investigation regarding their biological roles in neuropathies. Since TDP-43 and FUS are evolutionarily conserved we turned to the model organism C. elegans to learn more about their biological functions. The following objectives are being carried out: 1. The worm orthologues of TDP-43 and FUS are tdp-1 and fust-1 and we have obtained deletion mutants for each gene. These mutants are being characterized for their contribution to cellular stress resistance and longevity. We observed that tdp-1 and fust-1 have roles in the oxidative and osmotic stress and that tdp-1 may act to specify stress response signaling. 2. We have taken a transgenic approach to study the in vivo consequences of TDP-43 and FUS mutations. We engineered strains to express wild type and mutant human TDP-43 or FUS in worm motor neurons. The expression of mutant TDP-43 or FUS produces robust, adult onset, age-dependent motility defects ultimately leading to paralysis. These phenotypes are distinct from animals expressing wild type TDP-43 or FUS alleles. These phenotypes are useful for genetic and pharmacological suppressor screening. We have conducted a genetic screen and isolated a number of suppressors of mutant TDP-43 toxicity. An update of our findings will be presented.

Doyle, James-Julian et al. (2015) International Worm Meeting "C. elegans model of PGRN-deficient FTLD."

Bennett, Hugh, Parker, Alex, Doyle, James-Julian, Bateman, Andrew

[International Worm Meeting, 2015]

Frontotemporal lobar degeneration (FTLD) is a devastating neurodegenerative disease, characterized by the progressive atrophy of the frontal and temporal lobes of the brain. Advances in genetic testing have identified many of its underlying genetic causes. Among the genes identified are mutations in the GRN gene encoding for Progranulin (PGRN). To date over 70 different mutations have been identified, most resulting in a haploinsufficiency of the protein. Recent studies have shown that PGRN has neuroprotective properties, protecting against mutant TDP-43 and polyglutamine toxicity, and plays a significant role in cell survival and stress resistance. Nonetheless, its normal function in the brain, as well as its pathogenic mechanism, remain poorly understood. In order to understand the mechanism of PGRN-deficient FTLD, our lab has turned to the C. elegans nematode as a model. Given that C. elegans have an orthologue of the human GRN gene, pgrn-1, we used the pgrn-1(tm985) deletion mutant to model the loss-of-function. We began by characterizing the C. elegans pgrn-1(tm985) phenotype. This revealed that the worms present a motility defect when assessed in liquid culture. In order to better understand the action of PGRN-1 in the worms, we used RNAi knockdown technology to supress gene expression in the worms' muscle, intestinal, and neuronal cells. Furthermore, we have expressed GFP in the mutant worms' GABAergic motor neurons to assess neuronal health. Finally, we have taken advantage of the worm as a genetic tool to study the interactions between pgrn-1 and the worm orthologues of other known FTLD-causative genes. Based on our findings thus far, we will utilize the worm motility defect to our advantage by performing a high-throughput drug screen to identify potential therapeutics. Together, our findings will increase current understandings on the cause of PGRN-deficient FTLD.