From cellular vulnerability to altered circuit activity:a systems biology approach to study amyotrophic lateral sclerosis

The devastating effects of the brain losing its ability to control voluntary body movement are illustrated by diseases such as amyotrophic lateral sclerosis (ALS) - where the nerve cells that allow the brain to effectively communicate with muscles are progressively lost. Most of the ALS research traditionally revolves around the affected nerve cells, known as motoneurons, and aims to rescue their decline in function. Motoneurons are however part of larger networks in the nervous system and constantly receive, process and transmit signals. Therefore, even the smallest alteration of a single motoneuron will likely leave a mark on its connecting neurons and vice versa. Could it be that solely targeting the function of diseased neurons has unexpected effects in an already (mal)adapted network? To mimic ALS, we used the worm Caenorhabditis elegans engineered to express the human gene TDP-43. Dysregulated TDP-43 is considered a uniform hallmark of ALS and its expression in C. elegans causes severe paralysis. By developing and combining numerous technology-driven, mostly unbiased screening approaches we show that TDP-43 impedes neuronal function and causes an imbalance between stimulatory and inhibitory signals in the motor circuit. While functional output of repressed motoneurons could be restored via modulation of their activity, these interventions did not result in improved locomotion. Rebalancing the derailed motor circuit dynamics by combining multiple treatments, however, effectively restored movement. Because of the high degree of similarity in genetic alterations and pathology between ALS worms and patients, similar therapeutic strategies may eventually be valuable for ALS patients

Massively parallel C. elegans tracking provides multi-dimensional fingerprints for phenotypic discovery.

BACKGROUND: The nematode worm C. elegans is a model organism widely used for studies of genetics and of human disease. The health and fitness of the worms can be quantified in different ways, such as by measuring their bending frequency, speed or lifespan. Manual assays, however, are time consuming and limited in their scope providing a strong motivation for automation. NEW METHOD: We describe the development and application of an advanced machine vision system for characterising the behaviour of C. elegans, the Wide Field-of-View Nematode Tracking Platform (WF-NTP), which enables massively parallel data acquisition and automated multi-parameter behavioural profiling of thousands of worms simultaneously. RESULTS: We screened more than a million worms from several established models of neurodegenerative disorders and characterised the effects of potential therapeutic molecules for Alzheimer's and Parkinson's diseases. By using very large numbers of animals we show that the sensitivity and reproducibility of behavioural assays is very greatly increased. The results reveal the ability of this platform to detect even subtle phenotypes. COMPARISON WITH EXISTING METHODS: The WF-NTP method has substantially greater capacity compared to current automated platforms that typically either focus on characterising single worms at high resolution or tracking the properties of populations of less than 50 animals. CONCLUSIONS: The WF-NTP extends significantly the power of existing automated platforms by combining enhanced optical imaging techniques with an advanced software platform. We anticipate that this approach will further extend the scope and utility of C. elegans as a model organism

The cellular modifier MOAG-4/SERF drives amyloid formation through charge complementation.

While aggregation-prone proteins are known to accelerate aging and cause age-related diseases, the cellular mechanisms that drive their cytotoxicity remain unresolved. The orthologous proteins MOAG-4, SERF1A, and SERF2 have recently been identified as cellular modifiers of such proteotoxicity. Using a peptide array screening approach on human amyloidogenic proteins, we found that SERF2 interacted with protein segments enriched in negatively charged and hydrophobic, aromatic amino acids. The absence of such segments, or the neutralization of the positive charge in SERF2, prevented these interactions and abolished the amyloid-promoting activity of SERF2. In protein aggregation models in the nematode worm Caenorhabditis elegans, protein aggregation and toxicity were suppressed by mutating the endogenous locus of MOAG-4 to neutralize charge. Our data indicate that MOAG-4 and SERF2 drive protein aggregation and toxicity by interactions with negatively charged segments in aggregation-prone proteins. Such charge interactions might accelerate primary nucleation of amyloid by initiating structural changes and by decreasing colloidal stability. Our study points at charge interactions between cellular modifiers and amyloidogenic proteins as potential targets for interventions to reduce age-related protein toxicity

Gender equality, resilience to climate change, and the design of livestock projects for rural livelihoods

Currently, there is growing interest in how livestock projects can contribute to resilience to the effects of climate change. In this article we recommend a shift away from gross productivity to sustainability, via the use of thrifty local breeds, with an additional emphasis on improving survival of young animals. These animals, due to their local adaptations, are more likely to be resilient to climate change. There is a gender dimension to these proposals, since smaller animals and local breeds are more likely to be perceived by communities as suitable for husbandry by women. We recommend a re-orientation towards an explicit gender-equality focus for these projects

Post-load glucose subgroups and associated metabolic traits in individuals with type 2 diabetes:An IMI-DIRECT study

AIM: Subclasses of different glycaemic disturbances could explain the variation in characteristics of individuals with type 2 diabetes (T2D). We aimed to examine the association between subgroups based on their glucose curves during a five-point mixed-meal tolerance test (MMT) and metabolic traits at baseline and glycaemic deterioration in individuals with T2D. METHODS: The study included 787 individuals with newly diagnosed T2D from the Diabetes Research on Patient Stratification (IMI-DIRECT) Study. Latent class trajectory analysis (LCTA) was used to identify distinct glucose curve subgroups during a five-point MMT. Using general linear models, these subgroups were associated with metabolic traits at baseline and after 18 months of follow up, adjusted for potential confounders. RESULTS: At baseline, we identified three glucose curve subgroups, labelled in order of increasing glucose peak levels as subgroup 1-3. Individuals in subgroup 2 and 3 were more likely to have higher levels of HbA1c, triglycerides and BMI at baseline, compared to those in subgroup 1. At 18 months (n = 651), the beta coefficients (95% CI) for change in HbA1c (mmol/mol) increased across subgroups with 0.37 (-0.18-1.92) for subgroup 2 and 1.88 (-0.08-3.85) for subgroup 3, relative to subgroup 1. The same trend was observed for change in levels of triglycerides and fasting glucose. CONCLUSIONS: Different glycaemic profiles with different metabolic traits and different degrees of subsequent glycaemic deterioration can be identified using data from a frequently sampled mixed-meal tolerance test in individuals with T2D. Subgroups with the highest peaks had greater metabolic risk

Saved by the Matrix:UPR Independent Survival under ER Stress

Cells are protected from endoplasmic reticulum stress through the unfolded protein response (UPR). In this issue of Cell, Schinzel, Higuchi-Sanabria, Shalem et al., identify a mechanism that helps cells cope with ER stress but is independent of canonical UPR activation, instead involving the extracellular matrix hyaluronidase, TMEM2, as a signaling mediator

C. elegans as a Model for Synucleinopathies and Other Neurodegenerative Diseases: Tools and Techniques

Caenorhabditis elegans is widely used to investigate biological processes related to health and disease. Multiple C. elegans models for human neurodegenerative diseases do exist, including those expressing human α-synuclein. Even though these models do not feature all pathological and molecular hallmarks of the disease they mimic, they allow for the identification and dissection of molecular pathways that are involved. In line with this, genetic screens have yielded multiple modifiers of proteotoxicity in C. elegans models for neurodegenerative diseases. Here, we describe a set of common screening approaches and tools that can be used to study synucleinopathies and other neurodegenerative diseases in C. elegans. RNA interference and mutagenesis screens can be used to find genes that affect proteotoxicity, while relatively simple molecular, cellular (fractionation studies), metabolic (respiration studies), and behavioral (thrashing and crawling) readouts can be used to study the effects of disease proteins and modifiers more closely

Cellular Regulation of Amyloid Formation in Aging and Disease

As the population is aging, the incidence of age-related neurodegenerative diseases, such as Alzheimer and Parkinson disease, is growing. The pathology of neurodegenerative diseases is characterized by the presence of protein aggregates of disease specific proteins in the brain of patients. Under certain conditions these disease proteins can undergo structural rearrangements resulting in misfolded proteins that can lead to the formation of aggregates with a fibrillar amyloid-like structure. Cells have different mechanisms to deal with this protein aggregation, where the molecular chaperone machinery constitutes the first line of defense against misfolded proteins. Proteins that cannot be refolded are subjected to degradation and compartmentalization processes. Amyloid formation has traditionally been described as responsible for the proteotoxicity associated with different neurodegenerative disorders. Several mechanisms have been suggested to explain such toxicity, including the sequestration of key proteins and the overload of the protein quality control system. Here, we review different aspects of the involvement of amyloid-forming proteins in disease, mechanisms of toxicity, structural features, and biological functions of amyloids, as well as the cellular mechanisms that modulate and regulate protein aggregation, including the presence of enhancers and suppressors of aggregation, and how aging impacts the functioning of these mechanisms, with special attention to the molecular chaperones

An economical and highly adaptable optogenetics system for individual and population-level manipulation of Caenorhabditis elegans

This dataset contains the raw imaging files of the following study. Background: Optogenetics allows the experimental manipulation of excitable cells by a light stimulus without the need for technically challenging and invasive procedures. The high degree of spatial, temporal and intensity control that can be achieved with a light stimulus, combined with cell type-specific expression of light-sensitive ion channels, enables highly specific and precise stimulation of excitable cells. Optogenetic tools have therefore revolutionized the study of neuronal circuits in a number of models, including Caenorhabditis elegans. Despite the existence of several optogenetic systems that allow spatial and temporal photoactivation of light-sensitive actuators in C. elegans, their high costs and low flexibility have limited wide access to optogenetics. Here, we developed an inexpensive, easy-to-build, modular and adjustable optogenetics device for use on different microscopes and worm trackers, which we called the OptoArm. Results: The OptoArm allows for single- and multiple-worm illumination and is adaptable in terms of light intensity, lighting profiles and light-color. We demonstrate the OptoArm′s power in a population-based multi-parameter study on the contributions of motor circuit cells to age-related motility decline. We found that individual components of the neuromuscular system display different rates of age-dependent deterioration. The functional decline of cholinergic neurons mirrors motor decline, while GABAergic neurons and muscle cells are relatively age-resilient, suggesting that rate-limiting cells exist and determine neuronal circuit aging. Conclusion: We have assembled an economical, reliable and highly adaptable optogenetics system which can be deployed to address diverse biological questions. We provide a detailed description of the construction as well as technical and biological validation of our set-up. Importantly, use of the OptoArm is not limited to C. elegans and may benefit studies in multiple model organisms, making optogenetics more accessible to the broader research communit