PERK inhibition in zebrafish mimics human Wolcott-Rallison syndrome phenotypes.

Wolcott-Rallison Syndrome (WRS) is the most common cause of permanent neonatal diabetes mellitus among consanguineous families. The diabetes associated with WRS is non-autoimmune, insulin-requiring and associated with skeletal dysplasia and growth retardation. The therapeutic options for WRS patients rely on permanent insulin pumping or on invasive transplants of liver and pancreas. WRS has a well identified genetic cause: loss-of-function mutations in the gene coding for an endoplasmic reticulum kinase named PERK (protein kinase R-like ER kinase). Currently, WRS research is facilitated by cellular and rodent models with PERK ablation. While these models have unique strengths, cellular models incompletely replicate the organ/system-level complexity of WRS, and rodents have limited scalability for efficiently screening potential therapeutics. To address these challenges, we developed a new in vivo model of WRS by pharmacologically inhibiting PERK in zebrafish. This small vertebrate displays high fecundity, rapid development of organ systems and is amenable to highly efficient in vivo drug testing. PERK inhibition in zebrafish produced typical WRS phenotypes such as glucose dysregulation, skeletal defects, and impaired development. PERK inhibition in zebrafish also produced broad-spectrum WRS phenotypes such as impaired neuromuscular function, compromised cardiac function and muscular integrity. These results show that zebrafish holds potential as a versatile model to study WRS mechanisms and contribute to the identification of promising therapeutic options for WRS.

Blood Concentration of Macro- and Microelements in Women Who Are Overweight/Obesity and Their Associations with Serum Biochemistry.

Risk elements in blood matrices can affect human health status through associations with biomarkers at multiple levels. The aim of this study was to analyze 15 macro- and microelements in the blood serum of women with overweight (BMI of ≥25 kg/m2) and obesity (BMI of ≥30 kg/m2) and to examine possible associations with biochemical, liver enzymatic parameters, and markers of oxidative stress. Based on the power calculation, the study involved women (in the postmenopausal stage) with overweight (n = 26) and obesity (n = 22), aged between 50-65 years. Multifrequency bioelectrical impedance analysis was used to measure body composition parameters. Concentrations of elements were determined by inductively coupled plasma optical emission spectrometry, and Hg was measured using cold-vapor atomic absorption spectroscopy. Individuals with obesity, as indicated by a higher BMI, percentage of body fat, and visceral fat area, had elevated serum levels of Ca, Mg, Fe, Al, Sr, Pb, and Hg. Concentrations of Al, Cu, K, Sb, Zn, and Pb significantly affected biochemical and liver function markers in women with overweight or obesity. Elements such as Cu and Al were associated with increased total cholesterol. The correlation analysis between total antioxidant status and Cu, Al, and Ni confirmed associations in both groups. Our findings underscore the importance of addressing excess body weight and obesity in relation to risk elements. The results of the research could be beneficial in identifying potential targets for the treatment or prevention of comorbidities in people with obesity.

Edaravone counteracts redox and metabolic disruptions in an emerging zebrafish model of sporadic ALS.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which the death of motor neurons leads to loss of muscle function. Additionally, cognitive and circadian disruptions are common in ALS patients, contributing to disease progression and burden. Most ALS cases are sporadic, and environmental exposures contribute to their aetiology. However, animal models of these sporadic ALS cases are scarce. The small vertebrate zebrafish is a leading organism to model neurodegenerative diseases; previous studies have proposed bisphenol A (BPA) or ß-methylamino-l-alanine (BMAA) exposure to model sporadic ALS in zebrafish, damaging motor neurons and altering motor responses. Here we characterise the face and predictive validity of sporadic ALS models, showing their potential for the mechanistic study of ALS drugs. We phenotypically characterise the BPA and BMAA-induced models, going beyond motor activity and motor axon morphology, to include circadian, redox, proteostasis, and metabolomic phenotypes, and assessing their predictive validity for ALS modelling. BPA or BMAA exposure induced concentration-dependent activity impairments. Also, exposure to BPA but not BMAA induced motor axonopathy and circadian alterations in zebrafish larvae. Our further study of the BPA model revealed loss of habituation to repetitive startles, increased oxidative damage, endoplasmic reticulum (ER) stress, and metabolome abnormalities. The BPA-induced model shows predictive validity, since the approved ALS drug edaravone counteracted BPA-induced motor phenotypes, ER stress, and metabolic disruptions. Overall, BPA exposure is a promising model of ALS-related redox and ER imbalances, contributing to fulfil an unmet need for validated sporadic ALS models.

The Impact of HPP-Assisted Biocontrol Approach on the Bacterial Communities' Dynamics and Quality Parameters of a Fermented Meat Sausage Model.

Traditional foods are increasingly valued by consumers, whose attention and purchase willingness are highly influenced by other claims such as 'natural', 'sustainable', and 'clean label'. The purpose of the present study was to evaluate the impact of a novel non-thermal food processing method (i.e., HPP-assisted biocontrol combining mild high hydrostatic pressure, listeriophage Listex, and pediocin PA-1 producing Pediococcus acidilactici) on the succession of bacterial communities and quality of a fermented sausage model. A comparative analysis of instrumental color, texture, and lipid peroxidation revealed no significant differences (p > 0.05) in these quality parameters between non- and minimally processed fermented sausages throughout 60-day refrigerated storage (4 °C). The microbiota dynamics of biotreated and untreated fermented sausages were assessed by 16S rRNA next-generation sequencing, and the alpha and beta diversity analyses revealed no dissimilarity in the structure and composition of the bacterial communities over the analyzed period. The innovative multi-hurdle technology proposed herein holds valuable potential for the manufacture of traditional fermented sausages while preserving their unique intrinsic characteristics.

Stress response mechanisms in protein misfolding diseases: Profiling a cellular model of Huntington's disease.

Stress response pathways like the integrated stress response (ISR), the mitochondrial unfolded protein response (UPRmt) and the heat shock response (HSR) have emerged as part of the pathophysiology of neurodegenerative diseases, including Huntington's disease (HD) - a currently incurable disease caused by the production of mutant huntingtin (mut-Htt). Previous data from HD patients suggest that ISR is activated while UPRmt and HSR are impaired in HD. The study of these stress response pathways as potential therapeutic targets in HD requires cellular models that mimic the activation status found in HD patients of such pathways. PC12 cells with inducible expression of the N-terminal fragment of mut-Htt are among the most used cell lines to model HD, however the activation of stress responses remains unclear in this model. The goal of this study is to characterize the activation of ISR, UPRmt and HSR in this HD cell model and evaluate if it mimics the activation status found in HD patients. We show that PC12 HD cell model presents reduced levels of Hsp90 and mitochondrial chaperones, suggesting an impaired activation or function of HSR and UPRmt. This HD model also presents increased levels of phosphorylated eIF2α, the master regulator of the ISR, but overall similar levels of ATF4 and decreased levels of CHOP - transcription factors downstream to eIF2α - in comparison to control, suggesting an initial activation of ISR. These results show that this model mimics the ISR activation and the impaired UPRmt and HSR found in HD patients. This work suggests that the PC12 N-terminal HD model is suitable for studying the role of stress response pathways in the pathophysiology of HD and for exploratory studies investigating the therapeutic potential of drugs targeting stress responses.

Swimming against ALS: How to model disease in zebrafish for pathophysiological and behavioral studies.

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease that leads to progressive disability and motor impairment. Existing therapies provide modest improvements in patient survival, raising a need for new treatments for ALS. Zebrafish is a promising model animal for translational and fundamental research in ALS - it is an experimentally tractable vertebrate, with high homology to humans and an ample experimental toolbox. These advantages allow high-throughput study of behavioral and pathophysiological phenotypes. The last decade saw an increased interest in modelling ALS in zebrafish, leading to the current abundance and variety of available methods and models. Additionally, the rise of gene editing techniques and toxin combination studies has created novel opportunities for ALS studies in zebrafish. In this review, we address the relevance of zebrafish as a model animal for ALS studies, the strategies for model induction and key phenotypical evaluation. Furthermore, we discuss established and emerging zebrafish models of ALS, analyzing their validity, including their potential for drug testing, and highlighting research opportunities in this area.

Disruptions of circadian rhythms, sleep, and stress responses in zebrafish: New infrared-based activity monitoring assays for toxicity assessment.

Behavioural disruptions are sensitive indicators of alterations to normal animal physiology and can be used for toxicity assessment. The small vertebrate zebrafish is a leading model organism for toxicological studies. The ability to continuously monitor the toxicity of drugs, pollutants, or environmental changes over several days in zebrafish can have high practical application. Although video-recordings can be used to monitor short-term zebrafish behaviour, it is challenging to videorecord prolonged experiments (e.g. circadian behaviour over several days) because of the darkness periods (nights) and the heavy data storage and image processing requirements. Alternatively, infrared-based activity monitors, widely used in invertebrate models such as drosophila, generate simple and low-storage data and could optimize large-scale prolonged behavioural experiments in zebrafish, thus favouring the implementation of high-throughput testing strategies. Here, we validate the use of a Locomotor Activity Monitor (LAM) to study the behaviour of zebrafish larvae, and we characterize the behavioural phenotypes induced by abnormal light conditions and by the Parkinsonian toxin MPP+. When zebrafish were deprived from daily light-cycle synchronization, the LAM detected various circadian disruptions, such as increased activity period, phase shifts, and decreased inter-daily stability. Zebrafish exposed to MPP+ (10, 100, 500 µM) showed a concentration-dependent decrease in activity, sleep disruptions, impaired habituation to repetitive startles (visual-motor responses), and a slower recovery to normal activity after the startle-associated stress. These phenotypes evidence the feasibility of using infrared-based LAM to assess multi-parameter behavioural disruptions in zebrafish. The procedures in this study have wide applicability and may yield standard methods for toxicity testing.

Electron Flow From the Inner Membrane Towards the Cell Exterior in Geobacter sulfurreducens: Biochemical Characterization of Cytochrome CbcL.

Exoelectrogenic microorganisms are in the spotlight due to their unique respiratory mechanisms and potential applications in distinct biotechnological fields, including bioremediation, bioenergy production and microbial electrosynthesis. These applications rely on the capability of these microorganisms to perform extracellular electron transfer, a mechanism that allows the bacteria to transfer electrons to the cell's exterior by establishing functional interfaces between different multiheme cytochromes at the inner membrane, periplasmic space, and outer membrane. The multiheme cytochrome CbcL from Geobacter sulfurreducens is associated to the inner membrane and plays an essential role in the transfer of electrons to final electron acceptors with a low redox potential, as Fe(III) oxides and electrodes poised at -100 mV. CbcL has a transmembranar di-heme b-type cytochrome domain with six helices, linked to a periplasmic cytochrome domain with nine c-type heme groups. The complementary usage of ultraviolet-visible, circular dichroism and nuclear magnetic resonance permitted the structural and functional characterization of CbcL's periplasmic domain. The protein was found to have a high percentage of disordered regions and its nine hemes are low-spin and all coordinated by two histidine residues. The apparent midpoint reduction potential of the CbcL periplasmic domain was determined, suggesting a thermodynamically favorable transfer of electrons to the putative redox partner in the periplasm - the triheme cytochrome PpcA. The establishment of a redox complex between the two proteins was confirmed by probing the electron transfer reaction and the molecular interactions between CbcL and PpcA. The results obtained show for the first time how electrons are injected into the periplasm of Geobacter sulfurreducens for subsequent transfer to the cell's exterior.

The PERKs of mitochondria protection during stress: insights for PERK modulation in neurodegenerative and metabolic diseases.

Protein kinase RNA-like ER kinase (PERK) is an endoplasmic reticulum (ER) stress sensor that responds to the accumulation of misfolded proteins. Once activated, PERK initiates signalling pathways that halt general protein production, increase the efficiency of ER quality control, and maintain redox homeostasis. PERK activation also protects mitochondrial homeostasis during stress. The location of PERK at the contact sites between the ER and the mitochondria creates a PERK-mitochondria axis that allows PERK to detect stress in both organelles, adapt their functions and prevent apoptosis. During ER stress, PERK activation triggers mitochondrial hyperfusion, preventing premature apoptotic fragmentation of the mitochondria. PERK activation also increases the formation of mitochondrial cristae and the assembly of respiratory supercomplexes, enhancing cellular ATP-generating capacity. PERK strengthens mitochondrial quality control during stress by promoting the expression of mitochondrial chaperones and proteases and by increasing mitochondrial biogenesis and mitophagy, resulting in renewal of the mitochondrial network. But how does PERK mediate all these changes in mitochondrial homeostasis? In addition to the classic PERK-eukaryotic translation initiation factor 2α (eIF2α)-activating transcription factor 4 (ATF4) pathway, PERK can activate other protective pathways - PERK-O-linked N-acetyl-glucosamine transferase (OGT), PERK-transcription factor EB (TFEB), and PERK-nuclear factor erythroid 2-related factor 2 (NRF2) - contributing to broader regulation of mitochondrial dynamics, metabolism, and quality control. The pharmacological activation of PERK is protective in models of neurodegenerative and metabolic diseases, such as Huntington's disease, progressive supranuclear palsy and obesity, while the inhibition of PERK was protective in models of Parkinson's and prion diseases and diabetes. In this review, we address the molecular mechanisms by which PERK regulates mitochondrial dynamics, metabolism and quality control, and discuss the therapeutic potential of targeting PERK in neurodegenerative and metabolic diseases.

Automated analysis of activity, sleep, and rhythmic behaviour in various animal species with the Rtivity software.

Behavioural studies provide insights into normal and disrupted biological mechanisms. In many research areas, a growing spectrum of animal models-particularly small organisms-is used for high-throughput studies with infrared-based activity monitors, generating counts per time data. The freely available software to analyse such data, however, are primarily optimized for drosophila and circadian analysis. Researchers investigating other species or non-circadian behaviour would thus benefit from a more versatile software. Here we report the development of a free and open-source software-Rtivity-allowing customisation of species-specific parameters, and offering a versatile analysis of behavioural patterns, biological rhythms, stimulus responses, and survival. Rtivity is based on the R language and uses Shiny and the recently developed Rethomics package for a user-friendly graphical interface without requiring coding skills. Rtivity automatically assesses survival, computes various activity, sleep, and rhythmicity parameters, and performs fractal analysis of activity fluctuations. Rtivity generates multiple informative graphs, and exports structured data for efficient interoperability with common statistical software. In summary, Rtivity facilitates and enhances the versatility of the behavioural analysis of diverse animal species (e.g. drosophila, zebrafish, daphnia, ants). It is thus suitable for a broad range of researchers from multidisciplinary fields such as ecology, neurobiology, toxicology, and pharmacology.

Allosteric activation of Hsp70 reduces mutant huntingtin levels, the clustering of N-terminal fragments, and their nuclear accumulation.

AIMS: Huntington's disease (HD) is caused by a mutant huntingtin protein that misfolds, yields toxic N-terminal fragments, aggregates, and disrupts proteostasis. The Hsp70 chaperone is a potential therapeutic target as it prevents proteotoxicity by favouring protein folding, disaggregation, or degradation. We tested the hypothesis that allosteric Hsp70 activation with a pharmacological mimetic of the Hsp70 co-chaperone Hip, YM-1, could modulate huntingtin proteostasis. MAIN METHODS: We used HD cell models expressing either N-terminal or full-length huntingtin. Using single-cell analysis we studied huntingtin aggregation in different cellular compartments by fluorescence microscopy. Protein interaction was evaluated by immunoprecipitation, while protein levels were quantified by immunofluorescence and western-blot. KEY FINDINGS: N-terminal huntingtin interacted with Hsp70 and increased its levels. Treatment with YM-1 reduced N-terminal huntingtin clustering and nuclear aggregation. Full-length mutant huntingtin also interacted with Hsp70, and treatment with YM-1 reduced huntingtin levels when combined with Hsp70 induction by heat shock. Mechanistically, YM-1 increases the Hsp70 affinity for substrates, promoting their proteasomal degradation. Consistently, YM-1 reduced the levels of ubiquitinated proteins. Interestingly, YM-1 accumulated in mitochondria, interfered with its Hsp70 isoform involved in protein import, and increased NRF1 levels, a regulator of proteasome genes. We thus suggest that YM-1 may trigger the coordination of mitochondrial and cytosolic proteostasis, enhancing protein degradation. SIGNIFICANCE: Our findings show that the strategy of allosteric Hsp70 activation holds potential for HD. While drug efficacy may be limited to tissues with elevated Hsp70, combined therapies with Hsp70 elevating strategies could harness the full potential of allosteric Hsp70 activators for HD.

The interplay between redox signalling and proteostasis in neurodegeneration: In vivo effects of a mitochondria-targeted antioxidant in Huntington's disease mice.

Abnormal protein homeostasis (proteostasis), dysfunctional mitochondria, and aberrant redox signalling are often associated in neurodegenerative disorders, such as Huntington's (HD), Alzheimer's and Parkinson's diseases. It remains incompletely understood, however, how changes in redox signalling affect proteostasis mechanisms, including protein degradation pathways and unfolded protein responses (UPR). Here we address this open question by investigating the interplay between redox signalling and proteostasis in a mouse model of HD, and by examining the in vivo effects of the mitochondria-targeted antioxidant MitoQ. We performed behavioural tests in wild-type and R6/2 HD mice, examined markers of oxidative stress, UPR activation, and the status of key protein degradation pathways in brain and peripheral tissues. We show that R6/2 mice present widespread markers of oxidative stress, with tissue-specific changes in proteostasis that were more pronounced in the brain and muscle than in the liver. R6/2 mice presented increased levels of cytosolic and mitochondrial chaperones, particularly in muscle, indicating UPR activation. Treatment with MitoQ significantly ameliorated fine motor control of R6/2 mice, and reduced markers of oxidative damage in muscle. Additionally, MitoQ attenuated overactive autophagy induction in the R6/2 muscle, which has been associated with muscle wasting. Treatment with MitoQ did not alter autophagy markers in the brain, in agreement with its low brain bioavailability, which limits the risk of impairing neuronal protein clearance mechanisms. This study supports the hypotheses that abnormal redox signalling in muscle contributes to altered proteostasis and motor impairment in HD, and that redox interventions can improve muscle performance, highlighting the importance of peripheral therapeutics in HD.

Non-thermal approach to Listeria monocytogenes inactivation in milk: The combined effect of high pressure, pediocin PA-1 and bacteriophage P100.

Non-thermal food processing and replacement of chemical additives by natural antimicrobials are promising trends in the food industry. The objective of the present work was to evaluate the effect of a process which combines mild high hydrostatic pressure - HHP (200 and 300 MPa, 5 min, 10 °C), phage Listex™ P100 and the bacteriocin pediocin PA-1 as a new non-thermal process for destruction of Listeria monocytogenes (104 CFU mL-1 or 107 CFU mL-1) in milk. For inoculum levels of 104 CFU mL-1, HHP combined with phage P100 eliminated L. monocytogenes immediately after pressurization. When L. monocytogenes was inoculated at levels of 107 CFU mL-1, a synergistic effect between phage P100, pediocin PA-1 and HHP (300 MPa) on the inactivation of L. monocytogenes was observed during storage of milk at 4 °C. For non-pressure treated samples inoculated with phage or pediocin or both, L. monocytogenes counts decreased immediately after biocontrol application, but regrowth was observed in a few samples during storage. Phage particles were stable during refrigerated storage for seven days while pediocin PA-1 remained stable only during three days. Further studies will have to be performed to validate the findings of this work in specific applications (e.g. production of raw milk cheese).

Does the antidepressant sertraline show chronic effects on aquatic invertebrates at environmentally relevant concentrations? A case study with the keystone amphipod, Gammarus locusta.

The increasing use of Sertraline (SER) as antidepressant and its consequent presence in the aquatic environment is raising concern about the chronic effects of this pharmaceutical to aquatic organisms. As the current concentrations of SER in surface waters are typically in the low ng/L range, acute toxicity is unlikely to occur. However, prolonged exposure to low concentrations of SER may lead to sub-lethal effects in aquatic organisms, including alterations in important physiological functions like growth, reproduction, behaviour, and also in key biochemical processes, such as those associated with neurotransmission and redox balance. To test this hypothesis, we selected the amphipod Gammarus locusta, a keystone species used in ecotoxicological hazard assessment. In the present study, juveniles' G. locusta from a permanent laboratory culture were chronically exposed to low concentrations of SER (8-1000 ng/L) in a bioassay that lasted for 48 days, allowing for a life-cycle study including effects on reproduction. At the lowest SER concentrations with environmental relevance (8, 40 and 200 ng/L) we detected no significant changes in key ecological endpoints such as survival, growth, reproduction and movement behaviour, or in any of the biochemical markers analysed. However, at 1000 ng/L SER (a concentration one order of magnitude higher than the levels reported in aquatic environments) females showed a significant increase in movement versus control, whereas no activity changes were observed in males. Overall, these findings indicate that G. locusta females are potentially more susceptible to the chronic effects of SER. Moreover, the current environmental SER concentrations are unlikely to affect amphipod's ecological endpoints because only SER concentrations higher than the levels reported in aquatic environments produced effects on the behaviour of G. locusta females. However, the increasing consumption of SER, highlights the importance of monitoring its chronic risk to the aquatic wildlife.

Mitochondrial superoxide generation induces a parkinsonian phenotype in zebrafish and huntingtin aggregation in human cells.

Superoxide generation by mitochondria respiratory complexes is a major source of reactive oxygen species (ROS) which are capable of initiating redox signaling and oxidative damage. Current understanding of the role of mitochondrial ROS in health and disease has been limited by the lack of experimental strategies to selectively induce mitochondrial superoxide production. The recently-developed mitochondria-targeted redox cycler MitoParaquat (MitoPQ) overcomes this limitation, and has proven effective in vitro and in Drosophila. Here we present an in vivo study of MitoPQ in the vertebrate zebrafish model in the context of Parkinson's disease (PD), and in a human cell model of Huntington's disease (HD). We show that MitoPQ is 100-fold more potent than non-targeted paraquat in both cells and in zebrafish in vivo. Treatment with MitoPQ induced a parkinsonian phenotype in zebrafish larvae, with decreased sensorimotor reflexes, spontaneous movement and brain tyrosine hydroxylase (TH) levels, without detectable effects on heart rate or atrioventricular coordination. Motor phenotypes and TH levels were partly rescued with antioxidant or monoaminergic potentiation strategies. In a HD cell model, MitoPQ promoted mutant huntingtin aggregation without increasing cell death, contrasting with the complex I inhibitor rotenone that increased death in cells expressing either wild-type or mutant huntingtin. These results show that MitoPQ is a valuable tool for cellular and in vivo studies of the role of mitochondrial superoxide generation in redox biology, and as a trigger or co-stressor to model metabolic and neurodegenerative disease phenotypes.

Targeting the proteostasis network in Huntington's disease.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion mutation in the huntingtin protein. Expansions above 40 polyglutamine repeats are invariably fatal, following a symptomatic period characterised by choreiform movements, behavioural abnormalities, and cognitive decline. While mutant huntingtin (mHtt) is widely expressed from early life, most patients with HD present in mid-adulthood, highlighting the role of ageing in disease pathogenesis. mHtt undergoes proteolytic cleavage, misfolding, accumulation, and aggregation into inclusion bodies. The emerging model of HD pathogenesis proposes that the chronic production of misfolded mHtt overwhelms the chaperone machinery, diverting other misfolded clients to the proteasome and the autophagy pathways, ultimately leading to a global collapse of the proteostasis network. Multiple converging hypotheses also implicate ageing and its impact in the dysfunction of organelles as additional contributing factors to the collapse of proteostasis in HD. In particular, mitochondrial function is required to sustain the activity of ATP-dependent chaperones and proteolytic machinery. Recent studies elucidating mitochondria-endoplasmic reticulum interactions and uncovering a dedicated proteostasis machinery in mitochondria, suggest that mitochondria play a more active role in the maintenance of cellular proteostasis than previously thought. The enhancement of cytosolic proteostasis pathways shows promise for HD treatment, protecting cells from the detrimental effects of mHtt accumulation. In this review, we consider how mHtt and its post translational modifications interfere with protein quality control pathways, and how the pharmacological and genetic modulation of components of the proteostasis network impact disease phenotypes in cellular and in vivo HD models.

Modulation of Molecular Chaperones in Huntington's Disease and Other Polyglutamine Disorders.

Polyglutamine expansion mutations in specific proteins underlie the pathogenesis of a group of progressive neurodegenerative disorders, including Huntington's disease, spinal and bulbar muscular atrophy, dentatorubral-pallidoluysian atrophy, and several spinocerebellar ataxias. The different mutant proteins share ubiquitous expression and abnormal proteostasis, with misfolding and aggregation, but nevertheless evoke distinct patterns of neurodegeneration. This highlights the relevance of the full protein context where the polyglutamine expansion occurs and suggests different interactions with the cellular proteostasis machinery. Molecular chaperones are key elements of the proteostasis machinery and therapeutic targets for neurodegeneration. Here, we provide a focused review on Hsp90, Hsp70, and their co-chaperones, and how their genetic or pharmacological modulation affects the proteostasis and disease phenotypes in cellular and animal models of polyglutamine disorders. The emerging picture is that, in principle, Hsp70 modulation may be more amenable for long-term treatment by promoting a more selective clearance of mutant proteins than Hsp90 modulation, which may further decrease the necessary wild-type counterparts. It seems, nevertheless, unlikely that a single Hsp70 modulator will benefit all polyglutamine diseases. Indeed, available data, together with insights from effects on tau and alpha-synuclein in models of Alzheimer's and Parkinson's diseases, indicates that Hsp70 modulators may lead to different effects on the proteostasis of different mutant and wild-type client proteins. Future studies should include the further development of isoform selective inhibitors, namely to avoid off-target effects on Hsp in the mitochondria, and their characterization in distinct polyglutamine disease models to account for client protein-specific differences.

Chronic effects of triclocarban in the amphipod Gammarus locusta: Behavioural and biochemical impairment.

Triclocarban (TCC), a common antimicrobial agent widely used in many household and personal care products, has been widely detected in aquatic ecosystems worldwide. Due to its high lipophilicity and persistence in the aquatic ecosystems, TCC is of emerging environmental concern. Despite the frequently reported detection of TCC in the environment and significant uncertainties about its long term effects on aquatic ecosystems, few studies have addressed the chronic effects of TCC in aquatic organisms at ecologically relevant concentrations. Therefore, we aimed at testing a broad range of biological responses in the amphipod Gammarus locusta following a chronic (60 days) exposure to environmentally relevant concentrations of TCC (100, 500 and 2500ng/L). This work integrated biochemical markers of oxidative stress (catalase (CAT), glutathione-s-transferase (GST) and lipid peroxidation (LPO)) and neurotransmission (acetylcholinesterase (AChE)) with several key ecological endpoints, i.e. behaviour, survival, individual growth and reproduction. Significant alterations were observed in all biochemical markers. While AChE showed a dose-response curve (with a significant increased activity at a TCC concentration of 2500ng/L), oxidative stress markers did not follow a dose-response curve, with significant increase at 100 and/or 500ng/L and a decreased activity in the highest concentration (2500ng/L). The same effect was observed in the females' behavioural response, whereas males' behaviour was not affected by TCC exposure. The present study represents a first approach to characterize the hazard of TCC to crustaceans.

Mitochondrial dynamics and quality control in Huntington's disease.

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by polyglutamine expansion mutations in the huntingtin protein. Despite its ubiquitous distribution, expression of mutant huntingtin (mHtt) is particularly detrimental to medium spiny neurons within the striatum. Mitochondrial dysfunction has been associated with HD pathogenesis. Here we review the current evidence for mHtt-induced abnormalities in mitochondrial dynamics and quality control, with a particular focus on brain and neuronal data pertaining to striatal vulnerability. We address mHtt effects on mitochondrial biogenesis, protein import, complex assembly, fission and fusion, mitochondrial transport, and on the degradation of damaged mitochondria via autophagy (mitophagy). For an integrated perspective on potentially converging pathogenic mechanisms, we also address impaired autophagosomal transport and abnormal mHtt proteostasis in HD.

Pharmacological modulation of HDAC1 and HDAC6 in vivo in a zebrafish model: Therapeutic implications for Parkinson's disease.

Histone deacetylases (HDACs) are key epigenetic enzymes and emerging drug targets in cancer and neurodegeneration. Pan-HDAC inhibitors provided neuroprotection in Parkinson's Disease (PD) models, however, the HDAC isoforms with highest neuroprotective potential remain unknown. Zebrafish larvae (powerful pharmacological testing tools bridging cellular and in vivo studies) have thus far been used in PD modelling with limited phenotypic characterization. Here we characterize the behavioural and metabolic phenotypes of a zebrafish PD model induced with MPP(+), assess the feasibility of targeting zebrafish HDAC1 and HDAC6 isoforms, and test the in vivo effects of their selective inhibitors MS-275 and tubastatin A, respectively. MPP(+) induced a concentration-dependent decrease in metabolic activity and sensorimotor reflexes, and induced locomotor impairments rescuable by the dopaminergic agonist apomorphine. Zebrafish HDAC1 and HDAC6 isoforms show high sequence identity with mammalian homologues at the deacetylase active sites, and pharmacological inhibition increased acetylation of their respective histone and tubulin targets. MS-275 and tubastatin rescued the MPP(+)-induced decrease in diencephalic tyrosine hydroxylase immunofluorescence and in whole-larvae metabolic activity, without modifying mitochondrial complex activity or biogenesis. MS-275 or tubastatin alone modulated spontaneous locomotion. When combined with MPP(+), however, neither MS-275 nor tubastatin rescued locomotor impairments, although tubastatin did ameliorate the head-reflex impairment. This study demonstrates the feasibility of pharmacologically targeting the zebrafish HDAC1 and HDAC6 isoforms, and indicates that their inhibition can rescue cellular metabolism in a PD model. Absence of improvement in locomotion, however, suggests that monotherapy with either HDAC1 or HDAC6 inhibitors is unlikely to provide strong benefits in PD. This study highlights parameters dependent on the integrity of zebrafish neuronal circuits as a valuable complement to cell-based studies. Also, the demonstrated feasibility of pharmacologically targeting HDAC1 and HDAC6 in this organism paves the way for future studies investigating HDAC inhibitors in other diseases modelled in zebrafish.