Biology subjects

Laranjeiro, R.

Publications and source records attributed to Laranjeiro, R..

5 recordsLinked to original sources

bioRxiv2022

The glyoxylate shunt protein ICL-1 protects from mitochondrial superoxide stress through activation of the mitochondrial unfolded protein response.

Eliminating mitochondrial superoxide dismutase (SOD) causes neonatal lethality in mice and death of flies within 24 hours after eclosion. Deletion of mitochondrial sod genes in C. elegans impairs fertility as well, but surprisingly is not detrimental to survival of progeny generated. The comparison of metabolic pathways among mouse, flies and nematodes reveals that mice and flies lack the glyoxylate shunt. Here we show that ICL-1, the only protein of the glyoxylate shunt, is critical for protection against embryonic lethality resulting from elevated levels of mitochondrial superoxide. In exploring the mechanism by which ICL-1 protects against ROS-mediated embryonic lethality, we find that ICL-1 is required for the efficient activation of mitochondrial unfolded protein response (UPRmt) and that the UPRmt is essential to suppress embryonic/neonatal lethality in animals lacking mitochondrial SOD. In sum, we identified a biochemical pathway that highlights a molecular strategy for combating superoxide consequences in cells.

biochemistry↗

bioRxiv2020

Spaceflight Affects Neuronal Morphology and Alters Transcellular Degradation of Neuronal Debris in Adult Caenorhabditis elegans

Extended space travel, such as crewed missions to Mars and beyond, is a goal for both government space agencies and private companies. Research over the past decades, however, has shown that spaceflight poses risks to human health, including negative effects on musculoskeletal, cardiovascular, and immune systems. Details regarding effects on the nervous system have been less well described. The use of animal models holds great potential to identify and dissect conserved mechanisms of neuronal response to spaceflight. Here, we exploited the unique experimental advantages of the nematode Caenorhabditis elegans to explore how spaceflight affects adult neurons in vivo, at the single-cell level. We found that animals that lived 5 days of their adult life on the International Space Station exhibited considerable dendritic remodeling of the highly branched PVD neuron and modest morphological changes in touch receptor neurons when compared to ground control animals. Our results indicate hyperbranching as a common response of adult neurons to spaceflight. We also found that, in the presence of a neuronal proteotoxic stress, spaceflight promotes a remarkable accumulation of neuronal-derived waste in the surrounding tissues (especially hypodermis), suggesting an impaired transcellular degradation of debris that is released from neurons. Overall, our data reveal that spaceflight can significantly affect adult neuronal morphology and clearance of neuronal trash, highlighting the need to carefully assess the risks of long-duration spaceflight on the nervous system and to develop countermeasures to protect human health during space exploration.

neuroscience↗

bioRxiv2020

Multi-environment phenotyping of C. elegans for robust evaluation of physical performance

Determining the physical performance of humans using several measures is essential to evaluating the severity of diseases, understanding the role of environmental factors, and developing therapeutic interventions. Development of analogous measures of physical performance in model organisms can help in identifying conserved signaling pathways and prioritizing drug candidates. In this study, we propose a multi-environment phenotyping (MEP) approach that generates a comprehensive set of measures indicative of physical performance in C. elegans. We challenge C. elegans in different mechanical environments of burrowing, swimming, and crawling, each of which places different physiological demands on the animals to generate locomotory forces. Implementation of the MEP approach is done using three established assays corresponding to each environment-a hydrogel-based burrowing assay, the CeleST swim assay, and the NemaFlex crawling strength assay. Using this approach, we study individuals and show that these three assays report on unique aspects of nematode physiology, as phenotypic measures obtained from different environments do not correlate with one another. Analysis of a subset of genes representative of oxidative stress, glucose metabolism, and fat metabolism show differential expression depending on the animals environment, suggesting that each environment evokes a response with distinct genetic requirements. To demonstrate the utility of the MEP platform, we evaluate the response of a muscular dystrophy model of C. elegans dys-1 to drug interventions of prednisone, melatonin and serotonin. We find that prednisone, which is the current treatment standard for human Duchenne muscular dystrophy, confers benefits in all three assays. Furthermore, while the tested compounds improve the physical performance of dys-1, these compounds are not able to fully restore the measures to wild-type levels, suggesting the need for discovery efforts to identify more efficacious compounds that could be aided using the MEP platform. In summary, the MEP platforms ability to robustly define C. elegans locomotory phenotypes demonstrates the utility of the MEP approach toward identification of candidates for therapeutic intervention, especially in disease models in which the neuromuscular performance is impaired.

physiology↗

bioRxiv2019

Pluronic gel-based burrowing assay for rapid assessment of neuromuscular health in C. elegans

Whole-organism phenotypic assays are central to the assessment of neuromuscular function and health in model organisms such as the nematode C. elegans. In this study, we report a new assay format for engaging C. elegans in burrowing that enables rapid assessment of nematode neuromuscular health. In contrast to agar environments that pose specific drawbacks for characterization of C. elegans burrowing ability, here we use the optically transparent and biocompatible Pluronic F-127 gel that transitions from liquid to gel at room temperature, enabling convenient and safe handling of animals. The burrowing assay methodology involves loading animals at the bottom of well plates, casting a liquid-phase of Pluronic on top that solidifies via a modest temperature upshift, enticing animals to reach the surface via chemotaxis to food, and quantifying the relative success animals have in reaching the chemoattractant. We study the influence of Pluronic concentration, gel height and chemoattractant choice to optimize assay performance. To demonstrate the simplicity of the assay workflow and versatility, we show its novel application in multiple areas including (i) evaluating muscle mutants with defects in dense bodies and/or M-lines (pfn-3, atn-1, uig-1, dyc-1, zyx-1, unc-95 and tln-1), (ii) tuning assay conditions to reveal changes in the mutant gei- 8, (iii) sorting of fast burrowers in a genetically-uniform wild-type population for later quantitation of their distinct muscle gene expression, and (iv) testing proteotoxic animal models of Huntington and Parkinsons disease. Results from our studies show that stimulating animals to navigate in a dense environment that offers mechanical resistance to three- dimensional locomotion challenges the neuromuscular system in a manner distinct from standard crawling and thrashing assays. Our simple and high throughput burrowing assay can provide insight into molecular mechanisms for maintenance of neuromuscular health and facilitate screening for therapeutic targets.

neuroscience↗

bioRxiv2019

Swim exercise in C. elegans extends neuromuscular and intestinal healthspan, enhances learning ability, and protects against neurodegeneration

Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer, and age-associated declines in muscle, immune, and cognitive function. In fact, regular physical exercise is the most powerful intervention known to enhance robustness of health and aging. Still, the molecular and cellular mechanisms that mediate system-wide exercise benefits remain poorly understood, especially as applies to \"off target\" tissues that do not participate directly in training activity. Elaborating molecular mechanisms of whole-animal exercise benefits is therefore of considerable importance to human health. The development of exercise protocols for short-lived genetic models holds great potential for deciphering fundamental mechanisms of exercise trans-tissue signaling during the entire aging process. Here, we report on the optimization of a long-term swim exercise protocol for C. elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs only during a restricted phase during early adulthood. We found that multiple daily swim sessions are essential for exercise adaptation in C. elegans, leading to body wall muscle improvements in structural gene expression, locomotory performance, and mitochondrial morphology. Swim exercise training enhances whole-animal health parameters such as mitochondrial respiration and mid-life survival and increases the functional healthspan of pharynx and intestine. Importantly, we show that swim exercise also enhances nervous system health: exercise increases learning ability of adult animals and protects against neurodegeneration in C. elegans models of tauopathy, Alzheimers disease, and Huntingtons disease. An important point is that swim training only during C. elegans early adulthood induces long-lasting systemic benefits that in several cases are still detectable well into mid-life. Overall, our data reveal the broad impact of swim exercise in promoting extended healthspan of multiple C. elegans tissues, underscore the potency of early exercise experience to influence long-term health (even after cessation of exercise), and establish the foundation for exploiting the powerful advantages of this genetic model to dissect the exercise-dependent molecular circuitry that confers long-lasting system-wide health benefits to aging or diseased adults.

neuroscience↗