Novel Potential Targets for Function-Promoting Therapies: Orphan Nuclear Receptors, Anti-inflammatory Drugs, Troponin Activators, Mas Receptor Agonists, and Urolithin A

In recent years, several new classes of therapies have been investigated with their potential for restoring or improving physical functioning in older adults. These have included Mas receptor agonists, regulators of mitophagy, skeletal muscle troponin activators, anti-inflammatory compounds, and targets of orphan nuclear receptors. The present article summarizes recent developments of the function-promoting effects of these exciting new compounds and shares relevant preclinical and clinical data related to their safety and efficacy. The development of novel compounds in this area is expanding and likely will need the advent of a new treatment paradigm for age-associated mobility loss and disability

Large-scale functional RNAi screen in C. elegans identifies genes that regulate the dysfunction of mutant polyglutamine neurons

<p>Abstract</p> <p>Background</p> <p>A central goal in Huntington's disease (HD) research is to identify and prioritize candidate targets for neuroprotective intervention, which requires genome-scale information on the modifiers of early-stage neuron injury in HD.</p> <p>Results</p> <p>Here, we performed a large-scale RNA interference screen in <it>C. elegans </it>strains that express N-terminal huntingtin (htt) in touch receptor neurons. These neurons control the response to light touch. Their function is strongly impaired by expanded polyglutamines (128Q) as shown by the nearly complete loss of touch response in adult animals, providing an <it>in vivo </it>model in which to manipulate the early phases of expanded-polyQ neurotoxicity. In total, 6034 genes were examined, revealing 662 gene inactivations that either reduce or aggravate defective touch response in 128Q animals. Several genes were previously implicated in HD or neurodegenerative disease, suggesting that this screen has effectively identified candidate targets for HD. Network-based analysis emphasized a subset of high-confidence modifier genes in pathways of interest in HD including metabolic, neurodevelopmental and pro-survival pathways. Finally, 49 modifiers of 128Q-neuron dysfunction that are dysregulated in the striatum of either R/2 or CHL2 HD mice, or both, were identified.</p> <p>Conclusions</p> <p>Collectively, these results highlight the relevance to HD pathogenesis, providing novel information on the potential therapeutic targets for neuroprotection in HD.</p

Integration of beta-Catenin, Sirtuin, and FOXO Signaling Protects from Mutant Huntingtin Toxicity

One of the current challenges of neurodegenerative disease research is to determine whether signaling pathways that are essential to cellular homeostasis might contribute to neuronal survival and modulate the pathogenic process in human disease. In Caenorhabditis elegans, sir-2.1/SIRT1 overexpression protects neurons from the early phases of expanded polyglutamine (polyQ) toxicity, and this protection requires the longevity-promoting factor daf-16/FOXO. Here, we show that this neuroprotective effect also requires the DAF-16/FOXO partner bar-1/beta-catenin and putative DAF-16-regulated gene ucp-4, the sole mitochondrial uncoupling protein (UCP) in nematodes. These results fit with a previously proposed mechanism in which the beta-catenin FOXO and SIRT1 proteins may together regulate gene expression and cell survival. Knockdown of beta-catenin enhanced the vulnerability to cell death of mutant-huntingtin striatal cells derived from the HdhQ111 knock-in mice. In addition, this effect was compensated by SIRT1 overexpression and accompanied by the modulation of neuronal UCP expression levels, further highlighting a cross-talk between beta-catenin and SIRT1 in the modulation of mutant polyQ cytoxicity. Taken together, these results suggest that integration of beta-catenin, sirtuin and FOXO signaling protects from the early phases of mutant huntingtin toxicity

The Wnt Receptor Ryk Reduces Neuronal and Cell Survival Capacity by Repressing FOXO Activity During the Early Phases of Mutant Huntingtin Pathogenicity

The Wnt receptor Ryk is an evolutionary-conserved protein important during neuronal differentiation through several mechanisms, including γ-secretase cleavage and nuclear translocation of its intracellular domain (Ryk-ICD). Although the Wnt pathway may be neuroprotective, the role of Ryk in neurodegenerative disease remains unknown. We found that Ryk is up-regulated in neurons expressing mutant huntingtin (HTT) in several models of Huntington's disease (HD). Further investigation in Caenorhabditis elegans and mouse striatal cell models of HD provided a model in which the early-stage increase of Ryk promotes neuronal dysfunction by repressing the neuroprotective activity of the longevity-promoting factor FOXO through a noncanonical mechanism that implicates the Ryk-ICD fragment and its binding to the FOXO co-factor β-catenin. The Ryk-ICD fragment suppressed neuroprotection by lin-18/Ryk loss-of-function in expanded-polyQ nematodes, repressed FOXO transcriptional activity, and abolished β-catenin protection of mutant htt striatal cells against cell death vulnerability. Additionally, Ryk-ICD was increased in the nucleus of mutant htt cells, and reducing γ-secretase PS1 levels compensated for the cytotoxicity of full-length Ryk in these cells. These findings reveal that the Ryk-ICD pathway may impair FOXO protective activity in mutant polyglutamine neurons, suggesting that neurons are unable to efficiently maintain function and resist disease from the earliest phases of the pathogenic process in HD. © 2014 Tourette et al

Détection et caractérisation de cibles et de marqueurs pour la maladie de Huntington par une approche combinée basée sur le nématode Caenorhabditis elegans

La maladie de Huntington (MH) est une maladie neurodégénérative dominante due à des expansions de polyglutamines (polyQ) en N-terminal (Nter) de la huntingtine (HTT). Afin de recenser les modulateurs de la neurotoxicité des polyQ mutées, nous utilisons un modèle C. elegans dans lequel la HTT Nter normale (19Q) ou mutée (128Q) est exprimée dans les neurones récepteurs du toucher (NRT). Les animaux 128Q sont insensibles au toucher et nous avaient permis de découvrir le rôle neuroprotecteur des sirtuines et des FoxOs. Ici, nous avons analysé le profil d expression des gènes dans les NTR au niveau génomique. Des analyses basées sur des tests d enrichissement (GSEA) et sur des réseaux de gènes nous ont permis de découvrir des modulateurs comme les voies Wnt, TGFß et pha-4/FoxA1. Les validations soulignent le rôle du corécepteur Wnt lin-18/RYK : il est surexprimé dans le cerveau des patients MH et son inhibition est protectrice dans les modèles. Nous avons aussi montré le rôle d autres membres de la voie Wnt comme la ß-caténine et GSK3ß. Enfin, nos résultats suggèrent que GSK3ß serait un modificateur de la MH chez l homme, influençant l âge d apparition des symptômes. Ces travaux indiquent que les voies Wnt et FoxO coopèrent dans la survie neuronale et suggèrent de nouvelles pistes thérapeutiques pour la MH, comme l inhibition de RYK et de GSK3ß.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Genomic Analysis of ATP Efflux in Saccharomyces cerevisiae

Adenosine triphosphate (ATP) plays an important role as a primary molecule for the transfer of chemical energy to drive biological processes. ATP also functions as an extracellular signaling molecule in a diverse array of eukaryotic taxa in a conserved process known as purinergic signaling. Given the important roles of extracellular ATP in cell signaling, we sought to comprehensively elucidate the pathways and mechanisms governing ATP efflux from eukaryotic cells. Here, we present results of a genomic analysis of ATP efflux from Saccharomyces cerevisiae by measuring extracellular ATP levels in cultures of 4609 deletion mutants. This screen revealed key cellular processes that regulate extracellular ATP levels, including mitochondrial translation and vesicle sorting in the late endosome, indicating that ATP production and transport through vesicles are required for efflux. We also observed evidence for altered ATP efflux in strains deleted for genes involved in amino acid signaling, and mitochondrial retrograde signaling. Based on these results, we propose a model in which the retrograde signaling pathway potentiates amino acid signaling to promote mitochondrial respiration. This study advances our understanding of the mechanism of ATP secretion in eukaryotes and implicates TOR complex 1 (TORC1) and nutrient signaling pathways in the regulation of ATP efflux. These results will facilitate analysis of ATP efflux mechanisms in higher eukaryotes

A Phase 1 study for safety and pharmacokinetics of BIO101 (20‐hydroxyecdysone) in healthy young and older adults

Abstract Background Sarcopenia is an age‐related skeletal muscle disorder characterized by loss of muscle mass and strength leading to mobility disability. 20‐Hydroxyecdysone (20E) is a polyhydroxylated plant steroid that demonstrates pharmacological effects in many disease animal models including ageing/sarcopenia. BIO101 is a 20E purified investigational drug (≥97%) that previously demonstrated good toxicology profiles in rat and dog. BIO101 is evaluated in healthy young and older adults in a Phase 1 study. Methods This study is a Single Ascending Dose (SAD) followed by a 14‐day Multiple Ascending Dose (MAD). In SAD, BIO101 was administered orally to 16 young adults at doses from 100 to 1400 mg and to 8 older adults (age ≥65 years) at 1400 mg. In MAD, doses of 350 mg once daily (qd), 350 mg twice daily (bid) and 450 mg bid were administered to 10 older adults. The primary objective was to evaluate safety and pharmacokinetics (PK), including dosing of circulating metabolites. Pharmacodynamic effects were investigated with regard to myostatin, procollagen‐III‐amino‐terminal propeptide (PIIINP), myoglobin, creatine‐kinase Muscle Brain (CKMB), renin and aldosterone plasma/serum levels. Results BIO101 showed a good safety profile with only mild to moderate adverse events and a satisfactory pharmacokinetic profile. In SAD, at 100 mg to 1400 mg, mean Cmax and areas under the curve increased less than dose‐proportionally. Mean half‐life was short (2.4–4.9 h), and mean renal clearance was comparable in all doses (4.05–5.05 L/h). Mean plasma exposure was slightly lower in older adults (22% lower for Cmax and 13%–15% lower for AUCs) compared with young subjects. In MAD, 350 and 450 mg bid led to a slight accumulation over 14 days (mean ratio of accumulation [Rac] of 1.31 in both cohorts). Reduction of biomarkers (myoglobin, CK‐MB) mean serum levels (vs. baseline) was observed at 450 mg bid. Two major metabolites of 20E (14‐deoxy‐20‐hydroxyecdysone and 14‐deoxypoststerone) were identified and quantified. Conclusions BIO101 shows a good safety and pharmacokinetic profile that led to the selection of doses for the subsequent interventional clinical trials of Phase 2 in age‐related sarcopenia (SARA‐INT) and Phase 3 in Covid‐19 (COVA)

Association between Cognitive Status before Surgery and Outcomes in Elderly Patients with Hip Fracture in a Dedicated Orthogeriatric Care Pathway

International audienceAbstract: Background: Dementia is associated with a worse prognosis of hip fracture, but the impact of a dedicated geriatric care pathway on the prognosis of these patients has not been evaluated. Objective: According to the cognitive status before surgery, our main objective was to compare mortality rate at 6 months; secondary outcomes were to compare in-hospital complications, the risk of new institutionalization, and the ability to walk at 6 months. Methods: Between 2009 and 2015, all patients (>70 years) admitted after hip fracture surgery into a dedicated unit of peri-operative geriatric care were included: patients with dementia (DP), without dementia (NDP), and with cognitive status not determined (CSND). Data are expressed as hazard ratio (HR) for multivariate cox analysis or odds ratio (OR) for multivariate logistic regression analysis and their 95% confidence interval (CI). Results: We included 650 patients (86±6 years): 168 DP, 400 NDP, and 82 CSND. After adjustment for age, sex, comorbidities, polypharmacy, pre-fracture autonomy, time-to-surgery, and delirium, there were no significant differences for 6-month mortality (DP versus NDP: HR = 0.7[0.4–1.2], DP versus CSND: HR = 0.6[0.3–1.4], CSND versus NDP: HR = 0.8[0.4–1.7]); but DP and CSND were more likely to be newly institutionalized after 6 months compared to NDP (OR DP = 2.6[1.4–4.9], p = 0.003, OR CSND = 2.9[1.4–6.1], p = 0.004). 92% of population was walking after 6 months (63% with assistance): no difference was found between the three groups. Conclusion: In a dedicated geriatric care pathway, DP and CSND undergoing hip surgery have the same 6-month mortality and walking ability as NDP