Autophagic down-regulation in motor neurons remarkably prolongs the survival of ALS mice

Mechanism of motoneuronal and pyramidal cell death in amyotrophic lateral sclerosis and its potential therapeutic modulation

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder clinically characterized by muscle atrophy and progressive paralysis. Loss of motoneurons and pyramidal cells is thought to be the center piece of the complex and multifaceted ALS pathology, however, the exact mechanisms laying behind motoneuronal cell death in the spinal cord and motor cortex are still unknown. It was originally proposed that apoptosis plays a fundamental role in motoneuronal demise, nonetheless, later it became clear that other forms of regulated cell death, including necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death, may also contribute to motoneuron loss. Over the past years, multiple studies aimed to improve our understanding of the contributory role of these mechanisms as well as to offer novel targets for potential therapeutic interventions. The pharmacological inhibition of the ferroptotic pathway and the modulation of the autophagic machinery seem to have particularly promising effects, reducing motoneuron loss and slowing disease progression in transgenic models of ALS. Nevertheless, the potential beneficial effects of necroptosis-targeting interventions were mostly disproven in the latest studies. In this review we aim to summarize the current view on regulated cell death mechanisms that lead to motoneuronal and pyramidal cell degeneration in ALS and showcase their applicability as future drug targets.

Comprehensive quality evaluation of two different geography originated Angelica sinensis Radix based on potential production area development and resource protection

Angelica sinensis Radix (ASR) is mainly produced in the southern region of Gansu, China, and is a famous edible and medicinal herb. Noticeably, Aba region in Sichuan, China has similar geographical and climatic conditions to the southern region of Gansu, China, and has the potential to further develop the ASR planting industry chain. This study was the first to use an innovative method that combines GC-MS, HPLC-DAD fingerprints, and stoichiometric analysis to compare and explore the feasibility of using the Aba region as a source of high-quality ASR supplements. GC-MS analysis showed that the composition of ASR essential oil(AEO) in these two regions was highly similar (>99%). The HPLC data showed that the main sources of differences in ASR components between the two regions were coniferyl ferulate, E-ligustilide, Z-ligustilide, and Butylidenephthalide, which have great potential in anti-depression, regulating gut microbiota, and other aspects. The ASR in Aba region was rich in these components, and its biological activity might be higher to some extent than that in southern Gansu. This study confirmed the potential of the Aba region in Sichuan to become a high-quality production area for ASR, which was conducive to the expansion of ASR resources and the development of related industrial chains.

Autophagic mechanisms in longevity intervention: role of natural active compounds

The term 'autophagy' literally translates to 'self-eating' and alterations to autophagy have been identified as one of the several molecular changes that occur with aging in a variety of species. Autophagy and aging, have a complicated and multifaceted relationship that has recently come to light thanks to breakthroughs in our understanding of the various substrates of autophagy on tissue homoeostasis. Several studies have been conducted to reveal the relationship between autophagy and age-related diseases. The present review looks at a few new aspects of autophagy and speculates on how they might be connected to both aging and the onset and progression of disease. Additionally, we go over the most recent preclinical data supporting the use of autophagy modulators as age-related illnesses including cancer, cardiovascular and neurodegenerative diseases, and metabolic dysfunction. It is crucial to discover important targets in the autophagy pathway in order to create innovative therapies that effectively target autophagy. Natural products have pharmacological properties that can be therapeutically advantageous for the treatment of several diseases and they also serve as valuable sources of inspiration for the development of possible new small-molecule drugs. Indeed, recent scientific studies have shown that several natural products including alkaloids, terpenoids, steroids, and phenolics, have the ability to alter a number of important autophagic signalling pathways and exert therapeutic effects, thus, a wide range of potential targets in various stages of autophagy have been discovered. In this review, we summarised the naturally occurring active compounds that may control the autophagic signalling pathways.

Potential Diets to Improve Mitochondrial Activity in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease, the pathogenesis of which is based on alternations in the mitochondria of motor neurons, causing their progressive death. A growing body of evidence shows that more efficient mitophagy could prevent and/or treat this disorder by suppressing mitochondrial dysfunction-induced oxidative stress and inflammation. Mitophagy has been considered one of the main mechanisms responsible for mitochondrial quality control. Since ALS is characterized by enormous oxidative stress, several edible phytochemicals that can activate mitophagy to remove damaged mitochondria could be considered a promising option to treat ALS by providing neuroprotection. Therefore, it is of great significance to explore the mechanisms of mitophagy in ALS and to understand the effects and/or molecular mechanisms of phytochemical action, which could translate into a treatment for neurodegenerative diseases, including ALS.

Targeting PSEN1 by lnc-CYP3A43-2/miR-29b-2-5p to Reduce β Amyloid Plaque Formation and Improve Cognition Function

Presenilin-1 (PSEN1) is a crucial subunit within the γ-secretase complex and regulates β-amyloid (Aβ) production. Accumulated evidence indicates that n-butylidenephthalide (BP) acts effectively to reduce Aβ levels in neuronal cells that are derived from trisomy 21 (Ts21) induced pluripotent stem cells (iPSCs). However, the mechanism underlying this effect remains unclear. This article aims to investigate the possible mechanisms through which BP ameliorates the development of Alzheimer's disease (AD) and verify the effectiveness of BP through animal experiments. Results from RNA microarray analysis showed that BP treatment in Ts21 iPSC-derived neuronal cells reduced long noncoding RNA (lncRNA) CYP3A43-2 levels and increased microRNA (miR)-29b-2-5p levels. Bioinformatics tool prediction analysis, biotin-labeled miR-29b-2-5p pull-down assay, and dual-luciferase reporter assay confirmed a direct negative regulatory effect for miRNA29b-2-5p on lnc-RNA-CYP3A43-2 and PSEN1. Moreover, BP administration improved short-term memory and significantly reduced Aβ accumulation in the hippocampus and cortex of 3xTg-AD mice but failed in miR-29b-2-5p mutant mice generated by CRISP/Cas9 technology. In addition, analysis of brain samples from patients with AD showed a decrease in microRNA-29b-2-5p expression in the frontal cortex region. Our results provide evidence that the LncCYP3A43-2/miR29-2-5p/PSEN1 network might be involved in the molecular mechanisms underlying BP-induced Aβ reduction.

The Interplay Between Autophagy and RNA Homeostasis: Implications for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

Amyotrophic lateral sclerosis and frontotemporal dementia are neurodegenerative disorders that lie on a disease spectrum, sharing genetic causes and pathology, and both without effective therapeutics. Two pathways that have been shown to play major roles in disease pathogenesis are autophagy and RNA homeostasis. Intriguingly, there is an increasing body of evidence suggesting a critical interplay between these pathways. Autophagy is a multi-stage process for bulk and selective clearance of malfunctional cellular components, with many layers of regulation. Although the majority of autophagy research focuses on protein degradation, it can also mediate RNA catabolism. ALS/FTD-associated proteins are involved in many stages of autophagy and autophagy-mediated RNA degradation, particularly converging on the clearance of persistent pathological stress granules. In this review, we will summarise the progress in understanding the autophagy-RNA homeostasis interplay and how that knowledge contributes to our understanding of the pathobiology of ALS/FTD.

Regulation of neuronal autophagy and the implications in neurodegenerative diseases

Neurons are highly polarized and post-mitotic cells with the specific requirements of neurotransmission accompanied by high metabolic demands that create a unique challenge for the maintenance of cellular homeostasis. Thus, neurons rely heavily on autophagy that constitutes a key quality control system by which dysfunctional cytoplasmic components, protein aggregates, and damaged organelles are sequestered within autophagosomes and then delivered to the lysosome for degradation. While mature lysosomes are predominantly located in the soma of neurons, the robust, constitutive biogenesis of autophagosomes occurs in the synaptic terminal via a conserved pathway that is required to maintain synaptic integrity and function. Following formation, autophagosomes fuse with late endosomes and then are rapidly and efficiently transported by the microtubule-based cytoplasmic dynein motor along the axon toward the soma for lysosomal clearance. In this review, we highlight the recent knowledge of the roles of autophagy in neuronal health and disease. We summarize the available evidence about the normal functions of autophagy as a protective factor against neurodegeneration and discuss the mechanism underlying neuronal autophagy regulation. Finally, we describe how autophagy function is affected in major neurodegenerative diseases with a special focus on Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis.

HEXA-018, a Novel Inducer of Autophagy, Rescues TDP-43 Toxicity in Neuronal Cells

The autophagy-lysosomal pathway is an essential cellular mechanism that degrades aggregated proteins and damaged cellular components to maintain cellular homeostasis. Here, we identified HEXA-018, a novel compound containing a catechol derivative structure, as a novel inducer of autophagy. HEXA-018 increased the LC3-I/II ratio, which indicates activation of autophagy. Consistent with this result, HEXA-018 effectively increased the numbers of autophagosomes and autolysosomes in neuronal cells. We also found that the activation of autophagy by HEXA-018 is mediated by the AMPK-ULK1 pathway in an mTOR-independent manner. We further showed that ubiquitin proteasome system impairment- or oxidative stress-induced neurotoxicity was significantly reduced by HEXA-018 treatment. Moreover, oxidative stress-induced mitochondrial dysfunction was strongly ameliorated by HEXA-018 treatment. In addition, we investigated the efficacy of HEXA-018 in models of TDP-43 proteinopathy. HEXA-018 treatment mitigated TDP-43 toxicity in cultured neuronal cell lines and Drosophila. Our data indicate that HEXA-018 could be a new drug candidate for TDP-43-associated neurodegenerative diseases.

Natural Products in Therapeutic Management of Multineurodegenerative Disorders by Targeting Autophagy

Autophagy is an essential cellular process that involves the transport of cytoplasmic content in double-membraned vesicles to lysosomes for degradation. Neurons do not undergo cytokinesis, and thus, the cell division process cannot reduce levels of unnecessary proteins. The primary cause of neurodegenerative disorders (NDs) is the abnormal deposition of proteins inside neuronal cells, and this could be averted by autophagic degradation. Thus, autophagy is an important consideration when considering means of developing treatments for NDs. Various pharmacological studies have reported that the active components in herbal medicines exhibit therapeutic benefits in NDs, for example, by inhibiting cholinesterase activity and modulating amyloid beta levels, and α-synuclein metabolism. A variety of bioactive constituents from medicinal plants are viewed as promising autophagy controllers and are revealed to recover the NDs by targeting the autophagic pathway. In the present review, we discuss the role of autophagy in the therapeutic management of several NDs. The molecular process responsible for autophagy and its importance in various NDs and the beneficial effects of medicinal plants in NDs by targeting autophagy are also discussed.

N-butylidenephthalide ameliorates high-fat diet-induced obesity in mice and promotes browning through adrenergic response/AMPK activation in mouse beige adipocytes

Thermogenesis (non-exercise activity) in brown adipose tissue (BAT) promotes energy expenditure because of its higher number of mitochondria than white adipose tissue (WAT). The main function of thermogenesis in BAT can counteract obesity through the dissipation of calories as heat. N-butylidenephthalide (BP) is a natural derivative from Angelica sinensis, a Chinese herb that has been used for thousands of years. In this report, we demonstrated that BP improved the metabolic profiles of mice with high fat diet-induced obesity (DIO) by preventing weight gain, improving serum blood parameters, enhancing energy expenditure, stimulating white fat browning, and reversing hepatic steatosis. Further investigations demonstrated that BP administration upregulated the mRNA expression of beige (CD137, TMEM26) and brown fat selected genes (UCP1, PRDM16, PGC-1α, PPARγ) in white adipose tissues. In vitro studies, BP treatment increased multilocular lipid droplet levels, induced β-adrenergic receptor (cAMP/PKA) and AMP-activated protein kinase (AMPK) signaling (AMPK/acetyl-CoA carboxylase/SIRT1), and increased oxygen consumption in murine differentiated beige adipocytes, and the effects of BP were blocked by an AMPK inhibitor. BP promoted the interaction of AMPK with PGC-1α in beige adipocytes. Our findings provide novel insights into the application of BP in regulating energy metabolism and suggest its utility for clinical use in the treatment of obesity and related diseases.

A perspective on therapies for amyotrophic lateral sclerosis: can disease progression be curbed?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease involving both upper and lower motor neurons, leading to paralysis and eventually death. Symptomatic treatments such as inhibition of salivation, alleviation of muscle cramps, and relief of spasticity and pain still play an important role in enhancing the quality of life. To date, riluzole and edaravone are the only two drugs approved by the Food and Drug Administration for the treatment of ALS in a few countries. While there is adequate consensus on the modest efficacy of riluzole, there are still open questions concerning the efficacy of edaravone in slowing the disease progression. Therefore, identification of novel therapeutic strategies is urgently needed. Impaired autophagic process plays a critical role in ALS pathogenesis. In this review, we focus on therapies modulating autophagy in the context of ALS. Furthermore, stem cell therapies, gene therapies, and newly-developed biomaterials have great potentials in alleviating neurodegeneration, which might halt the disease progression. In this review, we will summarize the current and prospective therapies for ALS.

Mammalian/mechanistic target of rapamycin (mTOR) complexes in neurodegeneration

Novel targets to arrest neurodegeneration in several dementing conditions involving misfolded protein accumulations may be found in the diverse signaling pathways of the Mammalian/mechanistic target of rapamycin (mTOR). As a nutrient sensor, mTOR has important homeostatic functions to regulate energy metabolism and support neuronal growth and plasticity. However, in Alzheimer's disease (AD), mTOR alternately plays important pathogenic roles by inhibiting both insulin signaling and autophagic removal of β-amyloid (Aβ) and phospho-tau (ptau) aggregates. It also plays a role in the cerebrovascular dysfunction of AD. mTOR is a serine/threonine kinase residing at the core in either of two multiprotein complexes termed mTORC1 and mTORC2. Recent data suggest that their balanced actions also have implications for Parkinson's disease (PD) and Huntington's disease (HD), Frontotemporal dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). Beyond rapamycin; an mTOR inhibitor, there are rapalogs having greater tolerability and micro delivery modes, that hold promise in arresting these age dependent conditions.

n-Butylidenephthalide Modulates Autophagy to Ameliorate Neuropathological Progress of Spinocerebellar Ataxia Type 3 through mTOR Pathway

Spinocerebellar ataxia type 3 (SCA3), a hereditary and lethal neurodegenerative disease, is attributed to the abnormal accumulation of undegradable polyglutamine (polyQ), which is encoded by mutated ataxin-3 gene (ATXN3). The toxic fragments processed from mutant ATXN3 can induce neuronal death, leading to the muscular incoordination of the human body. Some treatment strategies of SCA3 are preferentially focused on depleting the abnormal aggregates, which led to the discovery of small molecule n-butylidenephthalide (n-BP). n-BP-promoted autophagy protected the loss of Purkinje cell in the cerebellum that regulates the network associated with motor functions. We report that the n-BP treatment may be effective in treating SCA3 disease. n-BP treatment led to the depletion of mutant ATXN3 with the expanded polyQ chain and the toxic fragments resulting in increased metabolic activity and alleviated atrophy of SCA3 murine cerebellum. Furthermore, n-BP treated animal and HEK-293GFP-ATXN3-84Q cell models could consistently show the depletion of aggregates through mTOR inhibition. With its unique mechanism, the two autophagic inhibitors Bafilomycin A1 and wortmannin could halt the n-BP-induced elimination of aggregates. Collectively, n-BP shows promising results for the treatment of SCA3.

Stimulation of mTOR-independent autophagy and mitophagy by rilmenidine exacerbates the phenotype of transgenic TDP-43 mice

Autophagy, which mediates the delivery of cytoplasmic substrates to the lysosome for degradation, is essential for maintaining proper cell homeostasis in physiology, ageing, and disease. There is increasing evidence that autophagy is defective in neurodegenerative disorders, including motor neurons affected in amyotrophic lateral sclerosis (ALS). Restoring impaired autophagy in motor neurons may therefore represent a rational approach for ALS. Here, we demonstrate autophagy impairment in spinal cords of mice expressing mutant TDP-43^Q331K or co-expressing TDP-43^WTxQ331K transgenes. The clinically approved anti-hypertensive drug rilmenidine was used to stimulate mTOR-independent autophagy in double transgenic TDP-43^WTxQ331K mice to alleviate impaired autophagy. Although rilmenidine treatment induced robust autophagy in spinal cords, this exacerbated the phenotype of TDP-43^WTxQ331K mice, shown by truncated lifespan, accelerated motor neuron loss, and pronounced nuclear TDP-43 clearance. Importantly, rilmenidine significantly promoted mitophagy in spinal cords TDP-43^WTxQ331K mice, evidenced by reduced mitochondrial markers and load in spinal motor neurons. These results suggest that autophagy induction accelerates the phenotype of this TDP-43 mouse model of ALS, most likely through excessive mitochondrial clearance in motor neurons. These findings also emphasise the importance of balancing autophagy stimulation with the potential negative consequences of hyperactive mitophagy in ALS and other neurodegenerative diseases.

Characterization of the role of autophagy in retinal ganglion cell survival over time using a rat model of chronic ocular hypertension

Autophagy is an essential cellular process for the degradation and recycling of cellular components, and its dysregulation has been linked to neuronal cell death and neurodegeneration. In glaucoma, the role of autophagy in retinal ganglion cell (RGC) survival remains contradictory. Moreover, the effects of autophagy modulation at different time-points on RGC survival in a glaucoma model have not been investigated. In this study, we assessed the time-dependent role of autophagy in RGC survival in a circumlimbal suture-induced ocular hypertensive (OHT) rat model. Intraocular pressure (IOP) elevation led to a gradual autophagy induction, which reached a maximum between 1 and 4 weeks after OHT induction. On the other hand, early autophagy was impaired between 1 and 3 days after circumlimbal suturing, indicated by increased p62 levels due to reduced autophagosomal turnover. The intravitreal administration of rapamycin at different time-points after the application of the circumlimbal suture indicated that autophagy induction early during OHT development had potent survival-promoting effects in RGCs. In conclusion, our findings suggest that the role of autophagy in RGCs during OHT development might differ in a time-dependent manner. Modulating autophagy at the appropriate time might serve as a potential therapeutic approach to enhance RGC survival in OHT.

Enhancement of cytotoxicity and induction of apoptosis by cationic nano-liposome formulation of n-butylidenephthalide in breast cancer cells

Breast cancer is the second most common malignancy in women. Current clinical therapy for breast cancer has many disadvantages, including metastasis, recurrence, and poor quality of life. Furthermore, it is necessary to find a new therapeutic drug for breast cancer patients to meet clinical demand. n-Butylidenephthalide (BP) is a natural and hydrophobic compound that can inhibit several tumors. However, BP is unstable in aqueous or protein-rich environments, which reduces the activity of BP. Therefore, we used an LPPC (Lipo-PEG-PEI complex) that can encapsulate both hydrophobic and hydrophilic compounds to improve the limitation of BP. The purpose of this study is to investigate the anti-tumor mechanisms of BP and BP/LPPC and further test the efficacy of BP encapsulated by LPPC on SK-BR-3 cells. BP inhibited breast cancer cell growth, and LPPC encapsulation (BP/LPPC complex) enhanced the cytotoxicity on breast cancer by stabilizing the BP activity and offering endocytic pathways. Additionally, BP and LPPC-encapsulated BP induced cell cycle arrest at the G₀/G₁ phase and might trigger both extrinsic as well as intrinsic cell apoptosis pathway, resulting in cell death. Moreover, the BP/LPPC complex had a synergistic effect with doxorubicin of enhancing the inhibitory effect on breast cancer cells. Consequently, LPPC-encapsulated BP could improve the anti-cancer effects on breast cancer in vitro. In conclusion, BP exhibited an anti-cancer effect on breast cancer cells, and LPPC encapsulation efficiently improved the cytotoxicity of BP via an acceleration of entrapment efficiency to induce cell cycle block and apoptosis. Furthermore, BP/LPPC exhibited a synergistic effect in combination with doxorubicin.

Amyotrophic Lateral Sclerosis and Autophagy: Dysfunction and Therapeutic Targeting

Over the past 20 years, there has been a drastically increased understanding of the genetic basis of Amyotrophic Lateral Sclerosis. Despite the identification of more than 40 different ALS-causing mutations, the accumulation of neurotoxic misfolded proteins, inclusions, and aggregates within motor neurons is the main pathological hallmark in all cases of ALS. These protein aggregates are proposed to disrupt cellular processes and ultimately result in neurodegeneration. One of the main reasons implicated in the accumulation of protein aggregates may be defective autophagy, a highly conserved intracellular "clearance" system delivering misfolded proteins, aggregates, and damaged organelles to lysosomes for degradation. Autophagy is one of the primary stress response mechanisms activated in highly sensitive and specialised neurons following insult to ensure their survival. The upregulation of autophagy through pharmacological autophagy-inducing agents has largely been shown to reduce intracellular protein aggregate levels and disease phenotypes in different in vitro and in vivo models of neurodegenerative diseases. In this review, we explore the intriguing interface between ALS and autophagy, provide a most comprehensive summary of autophagy-targeted drugs that have been examined or are being developed as potential treatments for ALS to date, and discuss potential therapeutic strategies for targeting autophagy in ALS.

SOD1-interacting proteins: Roles of aggregation cores and protein degradation systems

Cu/Zn superoxide dismutase (SOD1) mutations are associated with amyotrophic lateral sclerosis (ALS). SOD1-positive aggregates in motor neurons, as well as proteins that interact with the aggregates are presumably involved in ALS neurotoxicity. We used a proteomics approach to compare differences in protein expression in spinal cord homogenates from non-transgenic (NTG) and ALS model mice. Using the homogenates, we identified proteins that interacted with SOD1 seeds in vitro. We assessed differences in SOD1-interacting proteins in cell cultures treated with proteasome or autophagy inhibitor. In the first experiment, intermediate filamentous and small heat shock proteins were upregulated in glial cells. We identified 26 protein types that interacted with aggregation cores in ALS model homogenates, and unexpectedly, 40 proteins in were detected in NTG mice. In cell cultures treated with proteasome and autophagy inhibitors, we identified 16 and 11 SOD1-interacting proteins, respectively, and seven proteins in untreated cells. These SOD1-interacting proteins were involved in multiple cellular functions such as protein quality control, cytoskeletal organization, and pathways involved in growth factor signaling and their downstream cascades. The complex interactions between pathways could cause further dysregulation, ultimately leading to fatal cellular dysfunction in ALS.

Identifying Therapeutic Targets for Spinocerebellar Ataxia Type 3/Machado-Joseph Disease through Integration of Pathological Biomarkers and Therapeutic Strategies

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a progressive motor disease with no broadly effective treatment. However, most current therapies are based on symptoms rather than the underlying disease mechanisms. In this review, we describe potential therapeutic strategies based on known pathological biomarkers and related pathogenic processes. The three major conclusions from the current studies are summarized as follows: (i) for the drugs currently being tested in clinical trials; a weak connection was observed between drugs and SCA3/MJD biomarkers. The only two exceptions are the drugs suppressing glutamate-induced calcium influx and chemical chaperon. (ii) For most of the drugs that have been tested in animal studies, there is a direct association with pathological biomarkers. We further found that many drugs are associated with inducing autophagy, which is supported by the evidence of deficient autophagy biomarkers in SCA3/MJD, and that there may be more promising therapeutics. (iii) Some reported biomarkers lack relatively targeted drugs. Low glucose utilization, altered amino acid metabolism, and deficient insulin signaling are all implicated in SCA3/MJD, but there have been few studies on treatment strategies targeting these abnormalities. Therapeutic strategies targeting multiple pathological SCA3/MJD biomarkers may effectively block disease progression and preserve neurological function.

PACAP Modulates the Autophagy Process in an In Vitro Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of complex etiology leading to motor neuron degeneration. Many gene alterations cause this pathology, including mutation in Cu, Zn superoxide dismutase (SOD1), which leads to its gain of function. Mutant SOD1 proteins are prone to aberrant misfolding and create aggregates that impair autophagy. The hypoxic stress is strictly linked to the disease progression since it induces uncontrolled autophagy activation and the consequent high rates of cell death. Previously, we showed that pituitary adenylate cyclase-activating polypeptide (PACAP) exerts neurotrophic activity in cultured mSOD1 motor neurons exposed to serum deprivation. To date, no studies have examined whether the protective effect of PACAP on mSOD1 cells exposed to hypoxic insult is mediated through the regulation of the autophagy process. In the present study, we used the neuroblastoma-spinal cord-34 (NSC-34) cell line, stably expressing human wild type or mutant SOD1 G93A, to represent a well characterized in vitro model of a familial form of ALS. These cells were exposed to 100-µM desferrioxamine mesylate salt for 24h, to mimic the hypoxic stress affecting motor neurons during the disease progression. Our results showed that PACAP treatment significantly reduced cell death and hypoxia-induced mSOD1 accumulation by modulating the autophagy process in G93A motor neurons, as revealed by the decreased LC3II and the increased p62 levels, two autophagy indicators. These results were also confirmed by evaluating the vacuole formation detected through light chain 3 (LC3) immunofluorescence. Furthermore, the PACAP effects on autophagy seem to be mediated through the activation of the MAPK/ERK signaling pathway. Overall, our data demonstrated that PACAP exerts an ameliorative effect on the mSOD1 motor neuron viability by modulating a hypoxia-induced autophagy process through activation of MAPK/ERK signaling cascade.

Pathomechanism Heterogeneity in the Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Disease Spectrum: Providing Focus Through the Lens of Autophagy

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) constitute aggressive neurodegenerative pathologies that lead to the progressive degeneration of upper and lower motor neurons and of neocortical areas, respectively. In the past decade, the identification of several genes that cause these disorders indicated that the two diseases overlap in a multifaceted spectrum of conditions. The autophagy-lysosome system has been identified as a main intersection for the onset and progression of neurodegeneration in ALS/FTD. Genetic evidence has revealed that several genes with a mechanistic role at different stages of the autophagy process are mutated in patients with ALS/FTD. Moreover, the three main proteins aggregating in ALS/FTD, including in sporadic cases, are also targeted by autophagy and affect this process. Here, we examine the varied dysfunctions and degrees of involvement of the autophagy-lysosome system that have been discovered in ALS/FTD. We argue that these findings shed light on the pathological mechanisms in the ALS/FTD spectrum and conclude that they have important consequences both for treatment options and for the basic biomolecular understanding of how this process intersects with RNA metabolism, the other major cellular process reported to be dysfunctional in part of the ALS/FTD spectrum.

Human-Induced Pluripotent Stem Cells and Herbal Small-Molecule Drugs for Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) is characterized by extracellular amyloid plaques composed of the β-amyloid peptides and intracellular neurofibrillary tangles and associates with progressive declines in memory and cognition. Several genes play important roles and regulate enzymes that produce a pathological accumulation of β-amyloid in the brain, such as gamma secretase (γ-secretase). Induced pluripotent stem cells from patients with Alzheimer’s disease with different underlying genetic mechanisms may help model different phenotypes of Alzheimer’s disease and facilitate personalized drug screening platforms for the identification of small molecules. We also discuss recent developments by γ-secretase inhibitors and modulators in the treatment of AD. In addition, small-molecule drugs isolated from Chinese herbal medicines have been shown effective in treating Alzheimer’s disease. We propose a mechanism of small-molecule drugs in treating Alzheimer’s disease. Combining therapy with different small-molecule drugs may increase the chance of symptomatic treatment. A customized strategy tailored to individuals and in combination with therapy may be a more suitable treatment option for Alzheimer’s disease in the future.

Inhibition of MEK5 suppresses TDP-43 toxicity via the mTOR-independent activation of the autophagy-lysosome pathway

The most prominent hallmarks of many neurodegenerative diseases are the accumulation of misfolded protein aggregates and the death of certain neuronal populations. Autophagy is the major intracellular mechanism that degrades protein aggregates and damaged cellular components. Many studies have reported that the dysfunction of autophagy is associated with several neurodegenerative diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and Parkinson's disease. Here, we identified a novel mechanism of autophagy regulation. Inhibition of MEK5 reduced the level of p62 and increased the ratio of LC3-II to LC3-I, which is a marker for the activation of the autophagy-lysosome pathway (ALP). One of the most well-known regulators of the ALP is mTOR, and previous studies have reported that the major substrate of MEK5 is ERK5. However, we found that MEK5 modulates the autophagy-lysosome pathway in an mTOR- and ERK5-independent manner. Moreover, MEK5 inhibition alleviated the mislocalization of TDP-43 (an ALS-associated protein) and cell death in TDP-43-GFP-expressing neuronal cells. Taken together, these findings suggest that MEK5 is a novel autophagy modulator and that this kinase could be a therapeutic target for neurodegenerative diseases such as amyotrophic lateral sclerosis.

Autophagy as a common pathway in amyotrophic lateral sclerosis

Age-dependent neurodegenerative diseases are associated with a decline in protein quality control systems including autophagy. Amyotrophic lateral sclerosis (ALS) is a motor neuron degenerative disease of complex etiology with increasing connections to other neurodegenerative conditions such as frontotemporal dementia. Among the diverse genetic causes for ALS, a striking feature is the common connection to autophagy and its associated pathways. There is a recurring theme of protein misfolding as in other neurodegenerative diseases, but importantly there is a distinct common thread among ALS genes that connects them to the cascade of autophagy. However, the roles of autophagy in ALS remain enigmatic and it is still unclear whether activation or inhibition of autophagy would be a reliable avenue to ameliorate the disease. The main evidence that links autophagy to different genetic forms of ALS is discussed.

A Combination of Intrathecal and Intramuscular Application of Human Mesenchymal Stem Cells Partly Reduces the Activation of Necroptosis in the Spinal Cord of SOD1G93A Rats

An increasing number of studies have demonstrated the beneficial effects of human mesenchymal stem cells (hMSC) in the treatment of amyotrophic lateral sclerosis (ALS). We compared the effect of repeated intrathecal applications of hMSC or their conditioned medium (CondM) using lumbar puncture or injection into the muscle (quadriceps femoris), or a combination of both applications in symptomatic SOD1^G93A rats. We further assessed the effect of the treatment on three major cell death pathways (necroptosis, apoptosis, and autophagy) in the spinal cord tissue. All the animals were behaviorally tested (grip strength test, Basso Beattie Bresnahan (BBB) test, and rotarod), and the tissue was analyzed immunohistochemically, by qPCR and Western blot. All symptomatic SOD1 rats treated with hMSC had a significantly increased lifespan, improved motor activity and reduced number of Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells. Moreover, a combined hMSC delivery increased motor neuron survival, maintained neuromuscular junctions in quadriceps femoris and substantially reduced the levels of proteins involved in necroptosis (Rip1, mixed lineage kinase‐like protein, cl‐casp8), apoptosis (cl‐casp 9) and autophagy (beclin 1). Furthermore, astrogliosis and elevated levels of Connexin 43 were decreased after combined hMSC treatment. The repeated application of CondM, or intramuscular injections alone, improved motor activity; however, this improvement was not supported by changes at the molecular level. Our results provide new evidence that a combination of repeated intrathecal and intramuscular hMSC applications protects motor neurons and neuromuscular junctions, not only through a reduction of apoptosis and autophagy but also through the necroptosis pathway, which is significantly involved in cell death in rodent SOD1^G93A model of ALS. stem cells translational medicine2019;8:535–547

Antitumor Effect of n-Butylidenephthalide Encapsulated on B16/F10 Melanoma Cells In Vitro with a Polycationic Liposome Containing PEI and Polyethylene Glycol Complex

Advanced melanoma can metastasize to distal organs from the skin and yield an aggressive disease and poor prognosis even after treatment with chemotherapeutic agents. The compound n-Butylidenephthalide (BP) is isolated from Angelica sinensis, which is used to treat anemia and gynecological dysfunction in traditional Chinese medicine. Studies have indicated that BP can inhibit cancers, including brain, lung, prostate, liver, and colon cancers. However, because BP is a natural hydrophobic compound, it is quickly metabolized by the liver within 24 h, and thus has limited potential for development in cancer therapy. This study investigated the anticancer mechanisms of BP through encapsulation with a novel polycationic liposome containing polyethylenimine (PEI) and polyethylene glycol complex (LPPC) in melanoma cells. The results demonstrated that BP/LPPC had higher cytotoxicity than BP alone and induced cell cycle arrest at the G₀/G₁ phase in B16/F10 melanoma cells. The BP/LPPC-treated cell indicated an increase in subG₁ percentage and TUNEL positive apoptotic morphology through induction of extrinsic and intrinsic apoptosis pathways. The combination of BP and LPPC and clinical drug 5-Fluorouracil had a greater synergistic inhibition effect than did a single drug. Moreover, LPPC encapsulation improved the uptake of BP values through enhancement of cell endocytosis and maintained BP cytotoxicity activity within 24 h. In conclusion, BP/LPPC can inhibit growth of melanoma cells and induce cell arrest and apoptosis, indicating that BP/LPPC has great potential for development of melanoma therapy agents.

Sulforaphane from Cruciferous Vegetables: Recent Advances to Improve Glioblastoma Treatment

Sulforaphane (SFN), an isothiocyanate (ITC) derived from cruciferous vegetables, particularly broccoli and broccoli sprouts, has been widely investigated due to its promising health-promoting properties in disease, and low toxicity in normal tissue. Although not yet fully understood, many mechanisms of anticancer activity at each step of cancer development have been attributed to this ITC. Given the promising data available regarding SFN, this review aimed to provide an overview on the potential activities of SFN related to the cellular mechanisms involved in glioblastoma (GBM) progression. GBM is the most frequent malignant brain tumor among adults and is currently an incurable disease due mostly to its highly invasive phenotype, and the poor efficacy of the available therapies. Despite all efforts, the median overall survival of GBM patients remains approximately 1.5 years under therapy. Therefore, there is an urgent need to provide support for translating the progress in understanding the molecular background of GBM into more complex, but promising therapeutic strategies, in which SFN may find a leading role.

Protective effects of Withania somnifera extract in SOD1G93A mouse model of amyotrophic lateral sclerosis

Withania somnifera (WS; commonly known as Ashwagandha or Indian ginseng) is a medicinal plant whose extracts have been in use for centuries in various regions of the world as a rejuvenator. There is now a growing body of evidence documenting neuroprotective functions of the plant extracts or its purified compounds in several models of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Based on the extract's beneficial effect in a mouse model of ALS with TDP-43 proteinopathy, the current study was designed to test its efficacy in another model of familial ALS. Our results show that administration of WS extracts by gavage to mice expressing G93A mutant form of superoxide dismutase (SOD1) resulted in increased longevity, improved motor performance and increased number of motor neurons in lumbar spinal cord. The WS treatment caused substantial reduction in levels of misfolded SOD1whereas it enhanced expression of cellular chaperons in spinal cord of SOD1^G93A mice. WS markedly reduced glial activation and prevented phosphorylation of nuclear factor kappaB (NF-κB). The overall immunomodulatory effect of WS was further evidenced by changes in expression of multiple cytokines/chemokines. WS also served as an autophagy inducer which may be beneficial at early stages of the disease. These results suggest that WS extracts might constitute promising therapeutics for treatment of ALS with involvement of misfolded SOD1.

Advances in Patient-Specific Induced Pluripotent Stem Cells Shed Light on Drug Discovery for Amyotrophic Lateral Sclerosis

Induced pluripotent stem cells (iPSCs), which are generated through reprogramming adult somatic cells by expressing specific transcription factors, can differentiate into derivatives of the three embryonic germ layers and accelerate rapid advances in stem cell research. Neurological diseases such as amyotrophic lateral sclerosis (ALS) have benefited enormously from iPSC technology. This approach can be particularly important for creating iPSCs from patients with familial or sporadic forms of ALS. Motor neurons differentiated from the ALS-patient-derived iPSC can help to determine the relationship between cellular phenotype and genotype. Patient-derived iPSCs facilitate the development of new drugs and/or drug screening for ALS treatment and allow the exploration of the possible mechanism of ALS disease. In this article, we reviewed ALS-patient-specific iPSCs with various genetic mutations, progress in drug development for ALS disease, functional assays showing the differentiation of iPSCs into mature motor neurons, and promising biomarkers in ALS patients for the evaluation of drug candidates.

Association Between Autophagy and Neurodegenerative Diseases

Autophagy is a phylogenetically conserved mechanism that controls the degradation of subcellular constituents, including misfolded proteins, and damaged organelles. The progression of many neurodegenerative diseases is thought to be driven by the aggregation of misfolded proteins; therefore, autophagic activity is thought to affect disease severity to some extent. In some neurodegenerative diseases, the suppression of autophagic activity accelerates disease progression. Given that the induction of autophagy can potentially mitigate disease severity, various autophagy-inducing compounds have been developed and their efficacy has been evaluated in several rodent models of neurodegenerative diseases.

Autophagy and lysosomal pathways in nervous system disorders

Autophagy is an evolutionarily conserved pathway for delivering cytoplasmic cargo to lysosomes for degradation. In its classically studied form, autophagy is a stress response induced by starvation to recycle building blocks for essential cellular processes. In addition, autophagy maintains basal cellular homeostasis by degrading endogenous substrates such as cytoplasmic proteins, protein aggregates, damaged organelles, as well as exogenous substrates such as bacteria and viruses. Given their important role in homeostasis, autophagy and lysosomal machinery are genetically linked to multiple human disorders such as chronic inflammatory diseases, cardiomyopathies, cancer, and neurodegenerative diseases. Multiple targets within the autophagy and lysosomal pathways offer therapeutic opportunities to benefit patients with these disorders. Here, I will summarize the mechanisms of autophagy pathways, the evidence supporting a pathogenic role for disturbed autophagy and lysosomal degradation in nervous system disorders, and the therapeutic potential of autophagy modulators in the clinic.

The Molecular Mechanisms of Plant-Derived Compounds Targeting Brain Cancer

Glioblastoma multiforme (GBM) is one of the most aggressive and malignant forms of brain tumors. Despite recent advances in operative and postoperative treatments, it is almost impossible to perform complete resection of these tumors owing to their invasive and diffuse nature. Several natural plant-derived products, however, have been demonstrated to have promising therapeutic effects, such that they may serve as resources for anticancer drug discovery. The therapeutic effects of one such plant product, n-butylidenephthalide (BP), are wide-ranging in nature, including impacts on cancer cell apoptosis, cell cycle arrest, and cancer cell senescence. The compound also exhibits a relatively high level of penetration through the blood-brain barrier (BBB). Taken together, its actions have been shown to have anti-proliferative, anti-chemoresistance, anti-invasion, anti-migration, and anti-dissemination effects against GBM. In addition, a local drug delivery system for the subcutaneous and intracranial implantation of BP wafers that significantly reduce tumor size in xenograft models, as well as orthotopic and spontaneous brain tumors in animal models, has been developed. Isochaihulactone (ICL), another kind of plant product, possesses a broad spectrum of pharmacological activities, including impacts on cancer cell apoptosis and cell cycle arrest, as well as anti-proliferative and anti-chemoresistance effects. Furthermore, these actions have been specifically shown to have cancer-fighting effects on GBM. In short, the results of various studies reviewed herein have provided substantial evidence indicating that BP and ICH are promising novel anticancer compounds with good potential for clinical applications.

Targeting Cellular Stress Mechanisms and Metabolic Homeostasis by Chinese Herbal Drugs for Neuroprotection

Traditional Chinese medicine has been practiced for centuries in East Asia. Herbs are used to maintain health and cure disease. Certain Chinese herbs are known to protect and improve the brain, memory, and nervous system. To apply ancient knowledge to modern science, some major natural therapeutic compounds in herbs were extracted and evaluated in recent decades. Emerging studies have shown that herbal compounds have neuroprotective effects or can ameliorate neurodegenerative diseases. To understand the mechanisms of herbal compounds that protect against neurodegenerative diseases, we summarize studies that discovered neuroprotection by herbal compounds and compound-related mechanisms in neurodegenerative disease models. Those compounds discussed herein show neuroprotection through different mechanisms, such as cytokine regulation, autophagy, endoplasmic reticulum (ER) stress, glucose metabolism, and synaptic function. The interleukin (IL)-1β and tumor necrosis factor (TNF)-α signaling pathways are inhibited by some compounds, thus attenuating the inflammatory response and protecting neurons from cell death. As to autophagy regulation, herbal compounds show opposite regulatory effects in different neurodegenerative models. Herbal compounds that inhibit ER stress prevent neuronal death in neurodegenerative diseases. Moreover, there are compounds that protect against neuronal death by affecting glucose metabolism and synaptic function. Since the progression of neurodegenerative diseases is complicated, and compound-related mechanisms for neuroprotection differ, therapeutic strategies may need to involve multiple compounds and consider the type and stage of neurodegenerative diseases.

Rilmenidine promotes MTOR-independent autophagy in the mutant SOD1 mouse model of amyotrophic lateral sclerosis without slowing disease progression

Macroautophagy/autophagy is the main intracellular catabolic pathway in neurons that eliminates misfolded proteins, aggregates and damaged organelles associated with ageing and neurodegeneration. Autophagy is regulated by both MTOR-dependent and -independent pathways. There is increasing evidence that autophagy is compromised in neurodegenerative disorders, which may contribute to cytoplasmic sequestration of aggregation-prone and toxic proteins in neurons. Genetic or pharmacological modulation of autophagy to promote clearance of misfolded proteins may be a promising therapeutic avenue for these disorders. Here, we demonstrate robust autophagy induction in motor neuronal cells expressing SOD1 or TARDBP/TDP-43 mutants linked to amyotrophic lateral sclerosis (ALS). Treatment of these cells with rilmenidine, an anti-hypertensive agent and imidazoline-1 receptor agonist that induces autophagy, promoted autophagic clearance of mutant SOD1 and efficient mitophagy. Rilmenidine administration to mutant SOD1G93A mice upregulated autophagy and mitophagy in spinal cord, leading to reduced soluble mutant SOD1 levels. Importantly, rilmenidine increased autophagosome abundance in motor neurons of SOD1G93A mice, suggesting a direct action on target cells. Despite robust induction of autophagy in vivo, rilmenidine worsened motor neuron degeneration and symptom progression in SOD1G93A mice. These effects were associated with increased accumulation and aggregation of insoluble and misfolded SOD1 species outside the autophagy pathway, and severe mitochondrial depletion in motor neurons of rilmenidine-treated mice. These findings suggest that rilmenidine treatment may drive disease progression and neurodegeneration in this mouse model due to excessive mitophagy, implying that alternative strategies to beneficially stimulate autophagy are warranted in ALS.

Autophagy: The spotlight for cellular stress responses

Autophagy is an essential cellular mechanism which plays "housekeeping" role in normal physiological processes including removing of long lived, aggregated and misfolded proteins, clearing damaged organelles, growth regulation and aging. Autophagy is also involved in a variety of biological functions like development, cellular differentiation, defense against pathogens and nutritional starvation. The integration of autophagy into these biological functions and other stress responses is determined by the transcriptional factors that undertake the regulatory mechanism. This review discusses the machinery of autophagy, the molecular web that connects autophagy to various stress responses like inflammation, hypoxia, ER stress, and various other pathologic conditions. Defects in autophagy regulation play a central role in number of diseases, including neurodegenerative diseases, cancer, pathogen infection and metabolic diseases. Similarly, inhibiting autophagy would contribute in the treatment of cancer. However, understanding the biology of autophagy regulation requires pharmacologically active compounds which modulate the autophagy process. Inducers of autophagy are currently receiving considerable attention as autophagy upregulation may be a therapeutic benefit for certain neurodegenerative diseases (via removal of protein aggregates) while the inhibitors are being investigated for the treatment of cancers. Both induction and inhibition of autophagy have been proven to be beneficial in the treatment of cancer. This dual role of autophagy in cancers is now getting uncovered by the advancement in the research findings and development of effective autophagy modulators.

Autophagy Dysregulation in ALS: When Protein Aggregates Get Out of Hand

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that results from the loss of upper and lower motor neurons. One of the key pathological hallmarks in diseased neurons is the mislocalization of disease-associated proteins and the formation of cytoplasmic aggregates of these proteins and their interactors due to defective protein quality control. This apparent imbalance in the cellular protein homeostasis could be a crucial factor in causing motor neuron death in the later stages of the disease in patients. Autophagy is a major protein degradation pathway that is involved in the clearance of protein aggregates and damaged organelles. Abnormalities in autophagy have been observed in numerous neurodegenerative disorders, including ALS. In this review, we discuss the contribution of autophagy dysfunction in various in vitro and in vivo models of ALS. Furthermore, we examine the crosstalk between autophagy and other cellular stresses implicated in ALS pathogenesis and the therapeutic implications of regulating autophagy in ALS.

n-butylidenephthalide treatment prolongs life span and attenuates motor neuron loss in SOD1G93A mouse model of amyotrophic lateral sclerosis

AIMS

To evaluate the therapeutic effects of n-butylidenephthalide (BP) in SOD1G93A mouse model of amyotrophic lateral sclerosis and explore the possible mechanisms.

METHODS

The SOD1G93A mice were treated by oral administration of BP (q.d., 400 mg/kg d) starting from 60 days of age and continuing until death. The rotarod test was performed to assess the disease onset. The expression levels of apoptosis-related proteins, inflammatory molecules, and autophagy-associated proteins were determined. The number of apoptotic motor neurons and the extent of microglial and astroglial activation were also assessed in the lumbar spinal cords of BP-treated mice. Grip strength test, hematoxylin-eosin staining, nicotinamide adenine dinucleotide hydrogen staining, and malondialdehyde assay were conducted to evaluate the muscle function and pathology.

RESULTS

Although BP treatment did not delay the disease onset, it prolonged the life span and thereafter extended the disease duration in SOD1G93A mouse model of ALS. BP treatment also reduced the motor neuron loss through inhibiting apoptosis. We further demonstrated that the neuroprotective effects of BP might be resulted from the inhibition of inflammatory, oxidative stress, and autophagy.

CONCLUSION

Our study suggests that BP may be a promising candidate for the treatment of ALS.

Forward Genetic Screen in Caenorhabditis elegans Suggests F57A10.2 and acp-4 As Suppressors of C9ORF72 Related Phenotypes

An abnormally expanded GGGGCC repeat in C9ORF72 is the most frequent causal mutation associated with amyotrophic lateral sclerosis (ALS)/frontotemporal lobar degeneration (FTLD). Both gain-of-function (gf) and loss-of-function (lf) mechanisms have been involved in C9ORF72 related ALS/FTLD. The gf mechanism of C9ORF72 has been studied in various animal models but not in C. elegans. In the present study, we described mutant C9ORF72 modeling in C. elegans and report the finding of two suppressor genes. We made transgenes containing 9 or 29 repeats of GGGGCC in C9ORF72, driven by either the hsp-16 promoters or the unc-119 promoter. Transgenic worms were made to carry such transgenes. Phenotypic analysis of those animals revealed that P_hsp−16::(G4C2)₂₉::GFP transgenic animals (EAB 135) displayed severe paralysis by the second day of adulthood, followed by lethality, which phenotypes were less severe in P_hsp−16::(G4C2)₉::GFP transgenic animals (EAB242), and absent in control strains expressing empty vectors. Suppressor genes of this locomotor phenotype were pursued by introducing mutations with ethyl methanesulfonate in EAB135, screening mutant strains that moved faster than EAB135 by a food-ring assay, identifying mutations by whole-genome sequencing and testing the underlying mechanism of the suppressor genes either by employing RNA interference studies or C. elegans genetics. Three mutant strains, EAB164, EAB165 and EAB167, were identified. Eight suppressor genes carrying nonsense/canonical splicing site mutations were confirmed, among which a nonsense mutation of F57A10.2/VAMP was found in all three mutant strains, and a nonsense mutation of acp-4/ACP2 was only found in EAB164. Knock down/out of those two genes in EAB135 animals by feeding RNAi/introducing a known acp-4 null allele phenocopied the suppression of the C9ORF72 variant related movement defect in the mutant strains. Translational conformation in a mammalian system is required, but our worm data suggest that altering acp-4/ACP2 encoding lysosomal acid phosphatase may provide a potential therapeutic method of reducing acp-4/ACP2 levels, as opposed or complementary to directly reducing C9ORF72, to relieve C9ORF72-ALS phenotypes. It also suggests that the C9ORF72-ALS/FTLD may share a pathophysiologic mechanism with vesicle-associated membrane protein-associated protein B, a homolog of F57A10.2/VAMP, which is a proven ALS8 gene.

Actions of the antihistaminergic clemastine on presymptomatic SOD1-G93A mice ameliorate ALS disease progression

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a disease with a strong neuroinflammatory component sustained by activated microglia contributing to motoneuron death. However, how to successfully balance neuroprotective versus neurotoxic actions by the use of antinflammatory agents is still under scrutiny. We have recently shown that the antihistamine clemastine, an FDA-approved drug, can influence the M1/M2 switch occurring in SOD1-G93A ALS microglia.

METHODS

Here, we have chronically treated female SOD1-G93A mice with clemastine, evaluated disease progression and performed mice lumbar spinal cord analysis at symptomatic and end stage of the disease. Moreover, we have studied the mechanism of action of clemastine in primary adult spinal SOD1-G93A microglia cultures and in NSC-G93A motor neuron-like cells.

RESULTS

We found that a short treatment with clemastine (50 mg/kg) from asymptomatic (postnatal day 40) to symptomatic phase (postnatal day 120) significantly delayed disease onset and extended the survival of SOD1-G93A mice by about 10 %. Under these conditions, clemastine induced protection of motor neurons, modulation of inflammatory parameters, reduction of SOD1 protein levels and SQSTM1/p62 autophagic marker, when analysed immediately at the end of the treatment (postnatal day 120). A long treatment with clemastine (from asymptomatic until the end stage) instead failed to ameliorate ALS disease progression. At the end stage of the disease, we found that clemastine short treatment decreased microgliosis and SOD1 protein and increased LC3-II autophagic marker, while the long treatment produced opposite effects. Finally, in spinal microglia cultures from symptomatic SOD1-G93A mice clemastine activated inflammatory parameters, stimulated autophagic flux via the mTOR signalling pathway and decreased SOD1 levels. Modulation of autophagy was also demonstrated in NSC34 SOD1-G93A motor neuron-like cells.

CONCLUSIONS

By gaining insights into the ameliorating actions of an antihistaminergic compound in ALS disease, our findings might represent an exploitable therapeutic approach for familial forms of ALS.

Disrupted autophagy undermines skeletal muscle adaptation and integrity

This review assesses the importance of proteostasis in skeletal muscle maintenance with a specific emphasis on autophagy. Skeletal muscle appears to be particularly vulnerable to genetic defects in basal and induced autophagy, indicating that autophagy is co-substantial to skeletal muscle maintenance and adaptation. We discuss emerging evidence that tension-induced protein unfolding may act as a direct link between mechanical stress and autophagic pathways. Mechanistic links between protein damage, autophagy and muscle hypertrophy, which is also induced by mechanical stress, are still poorly understood. However, some mouse models of muscle disease show ameliorated symptoms upon effective targeting of basal autophagy. These findings highlight the importance of autophagy as therapeutic target and suggest that elucidating connections between protein unfolding and mTOR-dependent or mTOR-independent hypertrophic responses is likely to reveal specific therapeutic windows for the treatment of muscle wasting disorders.