-
Bitonto V, Protti N, Nuez-Martinez M, Vinas C, Laromaine A, Guerreiro JF, Mendes F, Pinto CIG, Xavier JAM, Munoz-Juan A, Marques F, Crich SG, Teixidor F
[
Cancers (Basel),
2021]
Purpose: The aim of our study was to assess if the sodium salt of cobaltabis(dicarbollide) and its di-iodinated derivative (Na[o-COSAN] and Na[8,8'-I2-o-COSAN]) could be promising agents for dual anti-cancer treatment (chemotherapy + BNCT) for GBM.Methods: The biological activities of the small molecules were evaluated in vitro with glioblastoma cells lines U87 and T98G in 2D and 3D cell models and in vivo in the small model animal Caenorhabditis elegans (C. elegans) at the L4-stage and using the eggs.Results: Our studies indicated that only spheroids from the U87 cell line have impaired growth after treatment with both compounds, suggesting an increased resistance from T98G spheroids, contrary to what was observed in the monolayer culture, which highlights the need to employ 3D models for future GBM studies. In vitro tests in U87 and T98G cells conclude that the amount of 10B inside the cells is enough for BNCT irradiation. BNCT becomes more effective on T98G after their incubation with Na[8,8'-I2-o-COSAN], whereas no apparent cell-killing effect was observed for untreated cells.Conclusions: These small molecules, particularly [8,8'-I2-o-COSAN]-, are serious candidates for BNCT now that the facilities of accelerator-based neutron sources are more accessible, providing an alternative treatment for resistant glioblastoma.
-
[
PLoS One,
2022]
Environmental oxidative stress threatens cellular integrity and should therefore be avoided by living organisms. Yet, relatively little is known about environmental oxidative stress perception. Here, using microfluidics, we showed that like I2 pharyngeal neurons, the tail phasmid PHA neurons function as oxidative stress sensing neurons in C. elegans, but display different responses to H2O2 and light. We uncovered that different but related receptors, GUR-3 and LITE-1, mediate H2O2 signaling in I2 and PHA neurons. Still, the peroxiredoxin PRDX-2 is essential for both, and might promote H2O2-mediated receptor activation. Our work demonstrates that C. elegans can sense a broad range of oxidative stressors using partially distinct H2O2 signaling pathways in head and tail sensillae, and paves the way for further understanding of how the integration of these inputs translates into the appropriate behavior.
-
[
Chemistry,
2023]
Cobaltabis(dicarbollides), ferrabis(dicarbollide), and their halogenated derivatives are the most studied metallacarboranes with great medical potential. These versatile compounds and their iodinated derivatives can be used in chemotherapy, radiotherapy, particle therapy, and bioimaging when isotopes are used. These metallacarboranes have been evaluated in vitro and recently in vivo with complex animal models. Lately, these studies have been complemented using the invertebrate Caenorhabditis elegans , a nematode largely used in toxicology. When evaluated at the L4 stage, cobaltabis(dicarbollides), ([o-COSAN]- and [8,8'-I2-o-COSAN]-), exhibited a higher mean lethal dose (LD50) than ferrabis(dicarbollides) ([o-FESAN]- and [8,8'-I2-o-FESAN]-). In this work, we use the C. elegans embryos since they are a complex biological barrier with concentric layers of polysaccharides and proteins that protect them from the environment. We assessed if the metal atom changes their biointeraction with the C. elegans embryos. First, we assessed the effects on embryo development for metallacarboranes and their di-iodinated derivatives. We observed changes in color and in their surface structure. An exhaustive physicochemical characterization was performed to understand better this interaction, revealing a stronger interaction of ferrabis(dicarbollide) compounds with C. elegans embryos than the cobaltabis(dicarbollide) molecules. Unveiling the biological interaction of these compounds is of great interest for their future biomedical applications.
-
[
MicroPubl Biol,
2022]
Perception of oxidative stress in nematodes involves specific neurons expressing antioxidant enzymes. Here, we carefully characterized GFP knock-in lines for C. elegans peroxiredoxin PRDX-2 and thioredoxin TRX-1, and uncovered that left and right I2, PHA and ASJ neurons reproducibly express an asymmetric level of each enzyme. We observed that high-expressing neurons are in most cases associated with a particular side, indicating a directional rather than stochastic type of asymmetry. We propose that the biological relevance of this left-right asymmetry is to fine-tune H 2 O 2 or light sensing, which remains to be investigated.
-
[
Curr Biol,
2015]
Neural circuits have long been known to modulate myogenic muscles such as the heart, yet a mechanistic understanding at the cellular and molecular levels remains limited. We studied how light inhibits pumping of the Caenorhabditis elegans pharynx, a myogenic muscular pump for feeding, and found three neural circuits that alter pumping. First, light inhibits pumping via the I2 neuron monosynaptic circuit. Our electron microscopic reconstruction of the anterior pharynx revealed evidence for synapses from I2 onto muscle that were missing from the published connectome, and we show that these "missed synapses" are likely functional. Second, light inhibits pumping through the RIP-I1-MC neuron polysynaptic circuit, in which an inhibitory signal is likely transmitted from outside the pharynx into the pharynx in a manner analogous to how the mammalian autonomic nervous system controls the heart. Third, light causes a novel pharyngeal behavior, reversal of flow or "spitting," which is induced by the M1 neuron. These three neural circuits show that neurons can control a myogenic muscle organ not only by changing the contraction rate but also by altering the functional consequences of the contraction itself, transforming swallowing into spitting. Our observations also illustrate why connectome builders and users should be cognizant that functional synaptic connections might exist despite the absence of a declared synapse in the connectome.
-
[
Cell,
2013]
The relationship between neural circuit function and patterns of synaptic connectivity is poorly understood, in part due to a lack of comparative data for larger complete systems. We compare system-wide maps of synaptic connectivity generated from serial transmission electron microscopy for the pharyngeal nervous systems of two nematodes with divergent feeding behavior: the microbivore Caenorhabditis elegans and the predatory nematode Pristionchus pacificus. We uncover a massive rewiring in a complex system of identified neurons, all of which are homologous based on neurite anatomy and cell body position. Comparative graph theoretical analysis reveals a striking pattern of neuronal wiring with increased connectional complexity in the anterior pharynx correlating with tooth-like denticles, a morphological feature in the mouth of P.pacificus. We apply focused centrality methods to identify neurons I1 and I2 as candidates for regulating predatory feeding and predict substantial divergence in the function of pharyngeal glands.
-
[
Acta Crystallogr Sect F Struct Biol Cryst Commun,
2006]
Hsp70 is an important molecular chaperone involved in the regulation of protein folding. Crystals of the C-terminal 10 kDa helical lid domain (residues 542-640) from a Caenorhabditis elegans Hsp70 homologue have been produced that diffract X-rays to approximately 3.4 A. Crystals belong to space group I2(1)2(1)2(1), with unit-cell parameters a = b = 197, c = 200 A. The Matthews coefficient, self-rotation function and Patterson map indicate 24 monomers in the asymmetric unit, showing non-crystallographic 432 symmetry. Molecular-replacement studies using the corresponding domain from rat, the only eukaryotic homologue with a known structure, failed and a mercury derivative was obtained. Preliminary MAD phasing using SHELXD and SHARP for location and refinement of the heavy-atom substructure and SOLOMON for density modification produced interpretable maps with a clear protein-solvent boundary. Further density-modification, model-building and refinement are currently under way.
-
[
Neuron,
2015]
While gustatory sensing of the five primary flavors (sweet, salty, sour, bitter, and savory) has been extensively studied, pathways that detect non-canonical taste stimuli remain relatively unexplored. Inparticular, while reactive oxygen species cause generalized damage to biological systems, no gustatory mechanism to prevent ingestion of such material has been identified in any organism. We observed that light inhibits C.elegans feeding and used light as a tool to uncover molecular and neural mechanisms for gustation. Light can generate hydrogen peroxide, and we discovered that hydrogen peroxide similarly inhibits feeding. The gustatory receptor family members LITE-1 and GUR-3 are required for the inhibition of feeding by light and hydrogen peroxide. The I2 pharyngeal neurons increase calcium in response to light and hydrogen peroxide, and these responses require GUR-3 and a conserved antioxidant enzyme peroxiredoxin PRDX-2. Our results demonstrate a gustatory mechanism that mediates the detection and blocks ingestion of a non-canonical taste stimulus, hydrogen peroxide.
-
[
Acta Crystallogr D Biol Crystallogr,
2003]
The nucleoside hydrolases (NHs) are a family of nucleoside-modifying enzymes. They play an important role in the purine-salvage pathway of many pathogenic organisms which are unable to synthesize purines de novo. Although well characterized in protozoan parasites, their precise function and mechanism remain unclear in other species. For the first time, NHs from Caenorhabditis elegans and Campylobacter jejuni, which are representatives of mesozoa and bacteria, respectively, have been cloned and purified. Steady-state kinetics indicate a different substrate-specificity profile to previously described hydrolases. Native diffraction data sets were collected from crystals of NH from each organism. The hexagonal crystals (space group P6(2)22 or P6(4)22) of NH from C. elegans diffracted to a resolution of 2.8 Angstrom, while the data set from the orthorhombic crystals (space group I222 or I2(1)2(1)2(1)) of NH from C. jejuni could be processed to 1.7 Angstrom resolution. The unit-cell parameters were a=b=102.23, c=117.27 Angstrom in the former case and a=101.13, b=100.13, c=81.37 in the latter.
-
[
J Mol Biol,
2004]
A family of antioxidant proteins, the peroxiredoxins, serve two purposes, detoxification of reactive oxygen species and cellular signaling. Among the three peroxiredoxins of Caenorhabditis elegans (CePrx1-3), CePrx2 was found to have a very unusual expression pattern, restricted to only two types of pharyngeal neurons; namely, the single pharyngeal interneuron I4 and the sensory interneuron I2. CePrx1 and CePrx3-depleted worms showed no obvious phenotypic alterations, whereas worms devoid of CePrx2 were retarded developmentally and had a significantly reduced brood size. Other features, such as lifespan, pharyngeal activity or defecation rates were indistinguishable from those of wild-type worms. Recombinant CePrx2 revealed antioxidant activity, as it was able to detoxify hydrogen peroxide and butylhydroperoxide (t-BOOH), and to protect glutamine synthetase from inactivation by thiol-dependent metal-catalyzed oxidation. In addition, the molecule was able to act as a terminal peroxidase in the thioredoxin system. Expression of ceprx2 in C. elegans was induced after short-term exposure of worms to t-BOOH but survival of ceprx2 knockout mutants in the presence of reactive oxygen or nitrogen species was not impaired. Thus, CePrx2 may protect specifically the two types of neurons from oxidative damage or, more likely, plays a critical role in peroxide signaling in this nematode.