Autophagy in spinal muscular atrophy: from pathogenic mechanisms to therapeutic approaches

© 2024 Rashid and Dimitriadi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). https://creativecommons.org/licenses/by/4.0/Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While the genetic cause of SMA has been well documented, the exact mechanism(s) by which SMN depletion results in disease progression remain elusive. A wide body of evidence has highlighted the involvement and dysregulation of autophagy in SMA. Autophagy is a highly conserved lysosomal degradation process which is necessary for cellular homeostasis; defects in the autophagic machinery have been linked with a wide range of neurodegenerative disorders, including amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. The pathway is particularly known to prevent neurodegeneration and has been suggested to act as a neuroprotective factor, thus presenting an attractive target for novel therapies for SMA patients. In this review, (a) we provide for the first time a comprehensive summary of the perturbations in the autophagic networks that characterize SMA development, (b) highlight the autophagic regulators which may play a key role in SMA pathogenesis and (c) propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.Peer reviewe

The effect of cooling procedures on monomer elution from heat-cured polymethyl methacrylate denture base materials

Objective: To evaluate the amount of methyl methacrylate (MMA) released in water from heat-cured polymethyl methacrylate (PMMA) denture base materials subjected to different cooling procedures. Methodology: Disk-shaped specimens (Ø:17 mm, h:2 mm) were fabricated from Paladon 65 (PA), ProBase Hot (PB), Stellon QC-20 (QC) and Vertex Rapid Simplified (VE) denture materials using five different cooling procedures (n=3/procedure): A) Bench-cooling for 10 min and then under running water for 15 min; B) Cooling in water-bath until room temperature; C) Cooling under running water for 15 min; D) Bench-cooling, and E) Bench-cooling for 30 min and under running water for 15 min. A, B, D, E procedures were proposed by the manufacturers, while the C was selected as the fastest one. Control specimens (n=3/material) were fabricated using a long polymerization cycle and bench-cooling. After deflasking, the specimens were ground, polished and stored in individual containers with 10 ml of distilled water for seven days (37oC). The amount of water-eluted MMA was measured per container using isocratic ultra-fast liquid chromatography (UFLC). Data were analyzed using Student’s and Welch’s t-test (α=0.05). Results: MMA values below the lower quantification limit (LoQ=5.9 ppm) were registered in B, C, E (PA); E (PB) and B, D, E (QC) procedures, whereas values below the detection limit (LoD=1.96 ppm) were registered in A, D (PA); A, B, C, D (PB); C, D, E (VE) and in all specimens of the control group. A, B (VE) and A, C (QC) procedures yielded values ranging from 6.4 to 13.2 ppm with insignificant differences in material and procedure factors (p>0.05). Conclusions: The cooling procedures may affect the monomer elution from denture base materials. The Ε procedure may be considered a universal cooling procedure compared to the ones proposed by the manufacturers, with the lowest residual monomer elution in water

Developing microfluidic platforms for rapid identification of new targets for neurodegenerative disorders

Peer reviewe

Single copy/knock-in models of ALS SOD1 in C. elegans suggest loss and gain of function have different contributions to cholinergic and glutamatergic neurodegeneration

Mutations in Cu/Zn superoxide dismutase 1 (SOD1) lead to Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease that disproportionately affects glutamatergic and cholinergic motor neurons. Previous work with SOD1 overexpression models supports a role for SOD1 toxic gain of function in ALS pathogenesis. However, the impact of SOD1 loss of function in ALS cannot be directly examined in overexpression models. In addition, overexpression may obscure the contribution of SOD1 loss of function in the degeneration of different neuronal populations. Here, we report the first single-copy, ALS knock-in models in C. elegans generated by transposon- or CRISPR/Cas9- mediated genome editing of the endogenous sod-1 gene. Introduction of ALS patient amino acid changes A4V, H71Y, L84V, G85R or G93A into the C. elegans sod-1 gene yielded single-copy/knock-in ALS SOD1 models. These differ from previously reported overexpression models in multiple assays. In single-copy/knock-in models, we observed differential impact of sod-1 ALS alleles on glutamatergic and cholinergic neurodegeneration. A4V, H71Y, G85R, and G93A animals showed increased SOD1 protein accumulation and oxidative stress induced degeneration, consistent with a toxic gain of function in cholinergic motor neurons. By contrast, H71Y, L84V, and G85R lead to glutamatergic neuron degeneration due to sod-1 loss of function after oxidative stress. However, dopaminergic and serotonergic neuronal populations were spared in single-copy ALS models, suggesting a neuronal-subtype specificity previously not reported in invertebrate ALS SOD1 models. Combined, these results suggest that knock-in models may reproduce the neurotransmitter-type specificity of ALS and that both SOD1 loss and gain of toxic function differentially contribute to ALS pathogenesis in different neuronal populations.Peer reviewe

Μελέτη γεωργικών πρακτικών με χρήση φυτοφαρμάκων (εντομοκτόνων , ζιζανιοκτόνων) και επιπτώσεις στο περιβάλλον και την υγεία

Τα πρόσκαιρα θετικά αποτελέσματα από τη χρήση φυτοφαρμάκων και λιπασμάτων στη γεωργία τη δεκαετία του 1950 οδήγησαν στην αλόγιστη χρήση αυτών, η οποία συνεχίζεται μέχρι και σήμερα και έχει ως αποτέλεσμα την έκθεση του ανθρώπου, αλλά και του περιβάλλοντος, σε κινδύνους. Η επιστημονική κοινότητα συνδέει πλέον την αύξηση των παθήσεων των ενδοκρινών αδένων, καθώς και του νευρικού και του αναπαραγωγικού συστήματος, με τα παρασιτοκτόνα. Τα παρασιτοκτόνα έχουν την ικανότητα να συνδέονται με τους υποδοχείς των ορμονών, με αποτέλεσμα αυτές να μην μπορούν να δράσουν στα όργανα «στόχους». Αυτό το φαινόμενο είναι γνωστό ως «ενδοκρινική διατάραξη». Επίσης, μελέτες έχουν δείξει πως τα παρασιτοκτόνα συμμετέχουν στην καρκινογένεση, είτε δρώντας ως προαγωγείς (ενεργοποιητές) ή μέσω παραγόντων που επηρεάζουν διάφορους μηχανισμούς άμυνας του οργανισμού με το σχηματισμό καρκινογόνων μεταβολιτών. Οι κυριότερες χημικές ενώσεις που εντοπίζονται στα παρασιτοκτόνα είναι Οργανοφωσφορικά, Οργανοχλωριωμένα, Πυρεθρίνες, Καρβαμιδικά, Τριαζίνες, Τριαζόλες. Σε αυτήν την εργασία θα μελετηθούν οι γεωργικές πρακτικές που χρησιμοποιούνται στις καλλιέργειες και τα παρασιτοκτόνα που αναφέρθηκαν παραπάνω, καθώς και ο τρόπος με τον οποίο οι ουσίες αυτές εισέρχονται στο περιβάλλον και καταλήγουν στον ανθρώπινο οργανισμό, και τέλος η επίδραση τους στο περιβάλλον και την ανθρώπινη υγεία με έμφαση στη δράση τους ως ενδοκρινικοί διαταράκτες.In 1950s farmers focused on yield as their key priority which has led to the adoption of high levels of pesticides and fertilizers in agriculture. The following years this irrational use of pesticides has resulted in exposure of humans and the environment to hazards. The scientific community is now linking the increase in endocrine, nervous and reproductive system diseases with pesticides. Pesticides have the ability to connect with hormone receptors, inhibiting the action of hormones on target organs. This phenomenon is known as "endocrine disruption". Studies have also shown that pesticides can contribute to carcinogenesis, either by acting as promoters or through factors that influence various defense mechanisms of the body by inducing the formation of carcinogenic metabolites. The main chemical compounds found in pesticides are Organophosphates, Organochlorines, Pyrethrins, Carbamates, Triazines and triazoles. This study examines the agricultural practices used in crops, the above pesticides, the way in which pesticides are introduced into the environment and subsequently into the human body, and finally their impact on the environment and human health with emphasis on their action as endocrine disrupters

Irregular Migration, Trafficking and Smuggling of Human Beings: Policy Dilemmas in the EU. CEPS Paperback, 22 February 2016

The expert contributors to this edited volume, representing a multidisciplinary selection of academics, examine the treatment of irregular migration, human trafficking and smuggling in EU law and policy. The various chapters explore the policy dilemmas encountered in efforts to criminalise irregular migration and humanitarian assistance to irregular immigrants. The book aims to provide academic input to informed policy-making in the next phase of the European Agenda on Migration. In his Foreword, Matthias Ruete, Director General of DG Home Affairs of the European Commission, writes: “This initiative aims to stimulate evidence-based policy-making and to bring fresh thinking to develop more effective policies. The European Commission welcomes the valuable contribution of this initiative to help close the wide gap in our knowledge about the smuggling of migrants, and especially the functioning of smuggling networks.

A transcriptomics-based drug repositioning approach to identify drugs with similar activities for the treatment of muscle pathologies in spinal muscular atrophy (SMA) models

© 2023 The Author(s). Published by Oxford University Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder caused by the reduction of survival of motor neuron (SMN) protein levels. Although three SMN-augmentation therapies are clinically approved that significantly slow down disease progression, they are unfortunately not cures. Thus, complementary SMN-independent therapies that can target key SMA pathologies and that can support the clinically approved SMN-dependent drugs are the forefront of therapeutic development. We have previously demonstrated that prednisolone, a synthetic glucocorticoid (GC) improved muscle health and survival in severe Smn-/-;SMN2 and intermediate Smn2B/- SMA mice. However, long-term administration of prednisolone can promote myopathy. We thus wanted to identify genes and pathways targeted by prednisolone in skeletal muscle to discover clinically approved drugs that are predicted to emulate prednisolone's activities. Using an RNA-sequencing, bioinformatics, and drug repositioning pipeline on skeletal muscle from symptomatic prednisolone-treated and untreated Smn-/-; SMN2 SMA and Smn+/-; SMN2 healthy mice, we identified molecular targets linked to prednisolone's ameliorative effects and a list of 580 drug candidates with similar predicted activities. Two of these candidates, metformin and oxandrolone, were further investigated in SMA cellular and animal models, which highlighted that these compounds do not have the same ameliorative effects on SMA phenotypes as prednisolone; however, a number of other important drug targets remain. Overall, our work further supports the usefulness of prednisolone's potential as a second-generation therapy for SMA, identifies a list of potential SMA drug treatments and highlights improvements for future transcriptomic-based drug repositioning studies in SMA.Peer reviewe

Decreased function of survival motor neuron protein impairs endocytic pathways

This document is the Accepted Manuscript version. The final, definitive version is available online at https://doi.org/10.1073/pnas.1600015113.Spinal muscular atrophy (SMA) is caused by depletion of the ubiquitously expressed survival motor neuron (SMN) protein, with 1 in 40 Caucasians being heterozygous for a disease allele. SMN is critical for the assembly of numerous ribonucleoprotein complexes, yet it is still unclear how reduced SMN levels affect motor neuron function. Here, we examined the impact of SMN depletion in Caenorhabditis elegans and found that decreased function of the SMN ortholog SMN-1 perturbed endocytic pathways at motor neuron synapses and in other tissues. Diminished SMN-1 levels caused defects in C. elegans neuromuscular function, and smn-1 genetic interactions were consistent with an endocytic defect. Changes were observed in synaptic endocytic proteins when SMN-1 levels decreased. At the ultrastructural level, defects were observed in endosomal compartments, including significantly fewer docked synaptic vesicles. Finally, endocytosis-dependent infection by JC polyomavirus (JCPyV) was reduced in human cells with decreased SMN levels. Collectively, these results demonstrate for the first time, to our knowledge, that SMN depletion causes defects in endosomal trafficking that impair synaptic function, even in the absence of motor neuron cell death.Peer reviewedFinal Accepted Versio

Neurocalcin Delta Suppression Protects against Spinal Muscular Atrophy in Humans and across Species by Restoring Impaired Endocytosis

This document is the Accepted Manuscript version of the following article: Riessland et al., 'Neurocalcin Delta Suppression Protects against Spinal Muscular Atrophy in Humans and across Species by Restoring Impaired Endocytosis', The American Journal of Human Genetics, Vol. 100 (2): 297-315, first published online 26 January 2017. The final, published version is available online at doi: http://dx.doi.org/10.1016/j.ajhg.2017.01.005 © 2017 American Society of Human Genetics.Homozygous SMN1 loss causes spinal muscular atrophy (SMA), the most common lethal genetic childhood motor neuron disease. SMN1 encodes SMN, a ubiquitous housekeeping protein, which makes the primarily motor neuron-specific phenotype rather unexpected. SMA-affected individuals harbor low SMN expression from one to six SMN2 copies, which is insufficient to functionally compensate for SMN1 loss. However, rarely individuals with homozygous absence of SMN1 and only three to four SMN2 copies are fully asymptomatic, suggesting protection through genetic modifier(s). Previously, we identified plastin 3 (PLS3) overexpression as an SMA protective modifier in humans and showed that SMN deficit impairs endocytosis, which is rescued by elevated PLS3 levels. Here, we identify reduction of the neuronal calcium sensor Neurocalcin delta (NCALD) as a protective SMA modifier in five asymptomatic SMN1-deleted individuals carrying only four SMN2 copies. We demonstrate that NCALD is a Ca(2+)-dependent negative regulator of endocytosis, as NCALD knockdown improves endocytosis in SMA models and ameliorates pharmacologically induced endocytosis defects in zebrafish. Importantly, NCALD knockdown effectively ameliorates SMA-associated pathological defects across species, including worm, zebrafish, and mouse. In conclusion, our study identifies a previously unknown protective SMA modifier in humans, demonstrates modifier impact in three different SMA animal models, and suggests a potential combinatorial therapeutic strategy to efficiently treat SMA. Since both protective modifiers restore endocytosis, our results confirm that endocytosis is a major cellular mechanism perturbed in SMA and emphasize the power of protective modifiers for understanding disease mechanism and developing therapies.Peer reviewedFinal Accepted Versio