La Rocca, Federica et al. (2021) International Worm Meeting "hnRNPQ/hrp-2 role in splicing and neurodegeneration."

Cieri, Federica, Di Schiavi, Elia, La Rocca, Federica, Santonicola, Pamela, Zampi, Giuseppina

[International Worm Meeting, 2021]

A correct splicing of mRNA is globally required in all cells, but neurons seem highly sensitive to perturbations with numerous neurological diseases caused by splicing defects, including spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and dementias. Neurons have features that make them vulnerable to mis-splicing events, such as their postmitotic state and longevity. However, the reason of this peculiar sensitivity of neurons to splicing alterations, why only subclasses of neurons are affected and which step of RNA processing is impaired in these diseases is still debated. We are investigating the molecular mechanisms underlying the neurodegeneration caused by splicing defects in SMA, using a neuron specific silencing approach in C.elegans. SMA is a motor neurons (MNs) specific disorder caused by mutations in the Survival Motor Neuron (SMN) gene. RNA-sequencing of iPS-MNs from SMA patients and healthy people allowed us to identify differentially expressed/spliced genes, enriched in RNA motif 7 (CAAAAAG). This motif is specifically bound by hnRNPQ, a protein interacting with SMN in the SMN complex. hrp-2 is the C.elegans homolog of hnRNPQ and we determined that, similarly to smn-1(KO), hrp-2 (ok1278) null mutants arrest as larvae, have a severe decrease in lifespan and locomotion defects. hrp-2 mutants show a reduction of visible D-type MNs and axonal defects, suggesting a specific role in neuron survival. hrp-2 overexpression in D-type MNs rescued the degeneration of MNs and the defects in locomotion observed in smn-1 silenced animals. These data suggest a specific involvement of hrp-2 in MNs survival and in smn-1 pathway, supporting the role of hrp-2 as an smn-1 modifier and as a possible therapeutic target for the disease. Further experiments are ongoing to better understand the genetic interaction between the two genes in MNs and to identify the role of mis-spliced targets in neurodegeneration.

Chen TC et al. (2023) Prostaglandins Leukot Essent Fatty Acids "Effect of omega-6 linoleic acid on neurobehavioral development in Caenorhabditis elegans."

Chao HR, Lai YR, Chen TC, Tsai MH, Wu CY, Hsu WL, Chen CH

[Prostaglandins Leukot Essent Fatty Acids, 2023]

Linoleic acid (LA, omega-6), an essential polyunsaturated fatty acid, is supplied by vegetable oils such as corn, sunflower and soybean. Supplementary LA in infants and children is required for normal growth and brain development, but has also been reported to induce brain inflammation and neurodegenerative diseases. This controversial role of LA development requires further investigation. Our study utilized Caenorhabditis elegans (C. elegans) as a model to clarify the role of LA in regulating neurobehavioral development. A mere supplementary quantity of LA in C. elegans larval stage affected the worm's locomotive ability, intracellular ROS accumulation and lifespan. We found that more serotonergic neurons were activated by supplementing LA above 10 μM thereby promoting locomotive ability with upregulation of serotonin-related genes. Supplementation with LA above 10 μM also inhibited the expression of mtl-1, mtl-2 and ctl-3 to accelerate oxidative stress and attenuate lifespan in nematodes; however, enhancement of stress-related genes such as sod-1, sod-3, mtl-1, mtl-2 and cyp-35A2 by supplementary LA under 1 μM decreased oxidative stress and increased the worm's lifespan. In conclusion, our study reveals that supplementary LA possesses both pros and cons in worm physiology and provides new suggestions for LA intake administration in childhood.

Nathalie Pujol et al. (2001) Worm Breeder's Gazette "Ver midi IV"

Jonathan Ewbank, Nathalie Pujol

[Worm Breeder's Gazette, 2001]

La quatrieme reunion annuelle des equipes francaises ayant un interet pour C. elegans se tiendra le Vendredi 23 fevrier 2001 a Luminy, Marseille. Contact: pujol@ibdm.univ-mrs.fr ewbank@ciml.univ-mrs.fr

Lavatelli A et al. (2020) J Biol Chem "Defining Caenorhabditis elegans as a model system to investigate lipoic acid metabolism."

de Mendoza D, Lavatelli A, Mansilla MC

[J Biol Chem, 2020]

Lipoic acid (LA) is a sulfur-containing cofactor that covalently binds to a variety of cognate enzymes that are essential for redox reactions in all three domains of life. Inherited mutations in the enzymes that make LA, namely lipoyl synthase, octanoyltransferase and amidotransferase, result in devastating human metabolic disorders. Unfortunately, because many aspects of this essential pathway are still obscure, available treatments only serve to alleviate symptoms. We envisioned that the development of an organismal model system might provide new opportunities to interrogate LA biochemistry, biology, and physiology. Here we report our investigations on three <i>Caenorhabditis elegans</i> orthologous proteins involved in this post-translational modification. We established that M01F1.3 encodes a lipoyl synthase, ZC410.7 an octanoyltransferase and C45G3.3 an amidotransferase. Worms subjected to RNAi against <i>M01F1.3</i> and <i>ZC410.7</i> manifest larval arrest in the second generation. The arrest was not rescued by LA supplementation, indicating that endogenous synthesis of LA is essential for <i>C. elegans</i> development. Expression of the enzymes M01F1.3, ZC410.7 and C45G3.3 completely rescue bacterial or yeast mutants affected in different steps of the lipoylation pathway, indicating functional overlap. Thus, we demonstrate that, similarly to humans, <i>C. elegans</i> is able to synthesize LA de novo via a lipoyl-relay pathway, and suggest this nematode could be a valuable model to dissect the role of protein mislipoylation and to develop new therapies.

Keith Nykamp et al. (2006) Development & Evolution Meeting "The Conserved La Motif Protein, LARP-1, Negatively Regulates MAPK Signalling in the Germ Line"

Judith Kimble, Keith Nykamp

[Development & Evolution Meeting, 2006]

The human La protein was first described as an autoantigen present in the sera of systemic lupus erythematosus (SLE) and Sjogren's patients. Since then, a large family of La-related proteins has been described (Wolin & Cedervall, 2002). La family members are all characterized by a highly conserved La Motif (LaM), which has RNA-binding activity. Typically, LaM family members, including human La and yeast Lhp1p, harbor additional RNA Recognition Motifs (RRMs) and localize predominately to the nucleus. Both La and Lhp1p bind RNA polymerase III transcripts (i.e. tRNAs, 5S rRNAs and snRNAs) and direct their maturation. In contrast, two atypical yeast LaM proteins, Sro9p and Slf1p, do not have any other recognizable RNA-binding domains and are predominately cytoplasmic. Sro9p and Slf1p are believed to play a role in mRNA metabolism, although it is unclear what their RNA targets and exact mechanism of control might be (Sobel and Wolin, 1999). The Caenorhabditis elegans genome encodes three LaM family members: C44E4.4, T12F5.5 and R144.7/larp-1. Of the three, LARP-1 is most closely related to yeast Sro9p and Slf1p. Initial RNAi experiments indicated that LARP-1 might be important for oogenesis. To confirm the RNAi results, we isolated larp-1(q783), a deletion mutant that eliminates expression of LARP-1 protein. We find that larp-1(q783) hermaphrodites are self-fertile, but have more developing oocytes in the proximal gonad than normal. We have also found active MAP kinase to be more abundant in larp-1(q783) germ lines than in wild-type. Our working model is that LARP-1 negatively regulates MAPK activity to ensure proper oogenesis.

Esther Zanin et al. (2005) International Worm Meeting "Studying the function of the PAR-3 complex in the early C. elegans embryo"

Monica Gotta, Esther Zanin

[International Worm Meeting, 2005]

Cell polarity is a crucial biological process that is essential to generate cell diversity. The anterior-posterior axis of the C. elegans embryo is determined by the entry of the sperm. The earliest polarity markers known are the conserved partitioning defective (PAR) proteins that localize asymmetrically on the cell cortex in the one cell embryo after fertilization. A protein complex consisting of PAR-3, PAR-6 and aPKC-3 (atypical protein kinase C 3) is enriched on the anterior cortex. Together PAR-3, PAR-6 and aPKC-3 (PAR-3 complex) determine the orientation of the first mitotic spindle along the anterior-posterior axis and the displacement of the spindle during anaphase toward the posterior of the embryo. In addition the PAR-3 complex has been suggested to regulate the cell lineage specific expression of cell fate determinants. Although there is clear support for the requirement of the PAR-3 complex in establishing and maintaining anterior-posterior polarity in the early C. elegans embryo, much less is known about its molecular functions. Therefore we want to identify phosphorylation targets of PKC-3 in C. elegans and investigate how their activity is modulated by PKC-3 in order to generate cell diversity. We performed a yeast two-hybrid screen using a C. elegans embryonic cDNA library and the kinase-dead kinase domain of PKC-3 as a bait. We identified a LA-domain containing protein as an interactor of PKC-3. The LA-domain is a putative RNA-binding domain but the molecular function of this protein is unknown. Interestingly SRO9, a S. cerevisiae LA-domain containing protein, shows a genetic interaction with tropomyosin 1 and RHO3. This observation, together with other data in S. cerevisiae, indicates that SRO9 is required for the stabilization of actin filaments. Depletion of LA by RNAi results in less than 10% embryonic lethality. However, the embryos show a strong posterior meeting of the paternal and maternal pronuclei, a reduced AB size and they are small. Interestingly we found that reducing the level of the LA by RNAi can partially rescue par-2 (it5ts) lethality. This suggests that the LA-domain protein could function either as a regulator or an effector of the PAR-3 complex. In order to understand if the reduction of the LA-domain protein influences the localization and/or levels of the PAR-3 complex we will analyze PAR-3 and PAR-6 immuno-staining in par-2 (it5ts) mutant embryos where the LA has been depleted by RNAi. Finally we aim to reveal if the LA-domain protein regulates F-actin stability via tropomyosin by testing its genetic interactions further. Current progress on the project will be presented at the meeting.

GroBe Brinkhaus S et al. (2014) Metallomics "Elemental bioimaging of manganese uptake in C. elegans."

Niehaus R, Reifschneider O, Wehe CA, Aschner M, Bornhorst J, Karst U, Chakraborty S, GroBe Brinkhaus S

[Metallomics, 2014]

A new method for elemental bioimaging with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was developed and applied to study the uptake of manganese (Mn) in Caenorhabditis elegans (C. elegans). C. elegans is a well-established model organism in neuroscience, genetics and genomics, which has been extensively studied to decipher mechanisms of heavy metal induced toxicity. Knowledge about the distribution of manganese (Mn) and other metals in this organism will be helpful in elucidating pathways and mechanisms of transport, distribution and excretion. The LA-ICP-MS method requires limited sample preparation and can be used rapidly and easily to visualize the Mn distribution in C. elegans. Due to thorough optimization of the analytical parameters, intense Mn signals in C. elegans wild-type (WT) and mutants were obtained at a spatial resolution as small as 4 m, thus proving the suitability of LA-ICP-MS to study the uptake of metals in C. elegans.

Keith Nykamp et al. (2008) Development & Evolution Meeting "LARP-1 Localizes to Germline P Bodies and Attenuates RAS-MAPK signaling During Oogenesis"

Myon-Hee Lee, Judith Kimble, Keith Nykamp

[Development & Evolution Meeting, 2008]

RNA regulators are critical for animal development, especially in the germ line. In this work, we focus on C. elegans LARP-1, a representative of one La-related protein (Larp) cluster that is broadly conserved among eukaryotes. LARP-1 possesses a signature La motif, which is an ancient RNA-binding domain, plus another conserved motif we have dubbed the LARP1 domain. LARP-1 binds RNA in vitro via the La motif and the LARP1 domain. A larp-1 null mutant has germline defects reminiscent of hyperactive Ras-MAPK signaling; genetic interactions indicate that LARP-1 normally attenuates Ras-MAPK signaling in the germ line; and mRNAs encoding certain Ras-MAPK signaling components are elevated in larp-1(0) mutant germ lines. LARP-1 co-localizes with cytoplasmic granules called P bodies, which have been implicated in mRNA degradation. We propose that LARP-1 affects the stability of selected mRNAs via its association with germline P bodies.

Han GC et al. (2021) Toxicology "Effects of lanthanum nitrate on behavioral disorder, neuronal damage and gene expression in different developmental stages of Caenorhabditis elegans."

Li ZN, Gao S, Han GC, Jing HM, Zhang WJ, Zhang GY, Zhang N, Ning JY, Li GJ

[Toxicology, 2021]

Rare earth elements (REEs) are widely used in the industry, agriculture, biomedicine, aerospace, etc, and have been shown to pose toxic effects on animals, as such, studies focusing on their biomedical properties are gaining wide attention. However, environmental and population health risks of REEs are still not very clear. Also, the REEs damage to the nervous system and related molecular mechanisms needs further research. In this study, the L1 and L4 stages of the model organism Caenorhabditis elegans were used to evaluate the effects and possible neurotoxic mechanism of lanthanum(III) nitrate hexahydrate (La(NO3)3-6H2O). For the L1 and L4 stage worms, the 48-h median lethal concentrations (LC50s) of La(NO3)3-6H2O were 93.163 and 648.0 mg/L respectively. Our results show that La(NO3)3-6H2O induces growth inhibition and defects in behavior such as body length, body width, body bending frequency, head thrashing frequency and pharyngeal pumping frequency at the L1 and L4 stages in C. elegans. The L1 stage is more sensitive to the toxicity of lanthanum than the L4 stage worms. Using transgenic strains (BZ555, EG1285 and NL5901), we found that La(NO3)3-6H2O caused the loss or break of soma and dendrite neurons in L1 and L4 stages; and &#945;-synuclein aggregation in L1 stage, indicating that Lanthanum can cause toxic damage to dopaminergic and GABAergic neurons. Mechanistically, La(NO3)3-6H2O exposure inhibited or activated the neurotransmitter transporters and receptors (glutamate, serotonin and dopamine) in C. elegans, which regulate behavior and movement functions. Furthermore, significant increase in the production of reactive oxygen species (ROS) was found in the L4 stage C. elegans exposed to La(NO3)3-6H2O. Altogether, our data show that exposure to lanthanum can cause neuronal toxic damage and behavioral defects in C. elegans, and provide basic information for understanding the neurotoxic effect mechanism and environmental health risks of rare earth elements.

Felix MA et al. (2002) Hermann, Editeurs des Sciences et des Arts. Paris, France. "Caenorhabditis elegans. Un organisme modele en biologie."

Labouesse M, Segalat L, Felix MA

[Hermann, Editeurs des Sciences et des Arts. Paris, France., 2002]

L'espce Caenorhabditis elegans fut dcrite en 1900 Alger par E. Maupas, qui s'intressait son mode de reproduction hermaphrodite. Plus tard, vers le milieu du vingtime sicle, V. Nigon et ses collaboratuers Lyon tudirent les reorganizations cellulaires accompagnant la fecundation et les premiers clivages. J. Brun isola les preiers mutants morpholgiques.