Correction of Huntington's Disease Phenotype by Genistein-Induced Autophagy in the Cellular Model

Effectiveness of Flavonoid-Rich Diet in Alleviating Symptoms of Neurodegenerative Diseases

Over the past decades, there has been a significant increase in the burden of neurological diseases, including neurodegenerative disorders, on a global scale. This is linked to a widespread demographic trend in which developed societies are aging, leading to an increased proportion of elderly individuals and, concurrently, an increase in the number of those afflicted, posing one of the main public health challenges for the coming decades. The complex pathomechanisms of neurodegenerative diseases and resulting varied symptoms, which differ depending on the disease, environment, and lifestyle of the patients, make searching for therapies for this group of disorders a formidable challenge. Currently, most neurodegenerative diseases are considered incurable. An important aspect in the fight against and prevention of neurodegenerative diseases may be broadly understood lifestyle choices, and more specifically, what we will focus on in this review, a diet. One proposal that may help in the fight against the spread of neurodegenerative diseases is a diet rich in flavonoids. Flavonoids are compounds widely found in products considered healthy, such as fruits, vegetables, and herbs. Many studies indicated not only the neuroprotective effects of these compounds but also their ability to reverse changes occurring during the progression of diseases such as Alzheimer's, Parkinson's and amyotrophic lateral sclerosis. Here, we present the main groups of flavonoids, discussing their characteristics and mechanisms of action. The most widely described mechanisms point to neuroprotective functions due to strong antioxidant and anti-inflammatory effects, accompanied with their ability to penetrate the blood-brain barrier, as well as the ability to inhibit the formation of protein aggregates. The latter feature, together with promoting removal of the aggregates is especially important in neurodegenerative diseases. We discuss a therapeutic potential of selected flavonoids in the fight against neurodegenerative diseases, based on in vitro studies, and their impact when included in the diet of animals (laboratory research) and humans (population studies). Thus, this review summarizes flavonoids' actions and impacts on neurodegenerative diseases. Therapeutic use of these compounds in the future is potentially possible but depends on overcoming key challenges such as low bioavailability, determining the therapeutic dose, and defining what a flavonoid-rich diet is and determining its potential negative effects. This review also suggests further research directions to address these challenges.

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

Correction of symptoms of Huntington disease by genistein through FOXO3-mediated autophagy stimulation

Huntington disease (HD) is a neurodegenerative disorder caused by a mutation in the HTT gene. The expansion of CAG triplets leads to the appearance of misfolded HTT (huntingtin) forming aggregates and leading to impairment of neuronal functions. Here we demonstrate that stimulation of macroautophagy/autophagy by genistein (4',5,7-trihydroxyisoflavone or 5,7-dihydroxy-3-(4-hydroxyphenyl)-4 H-1-benzopyran-4-one) caused a reduction of levels of mutated HTT in brains of HD mice and correction of their behavior as assessed in a battery of cognitive, anxiety and motor tests, even if the compound was administered after symptoms had developed in the animals. Biochemical and immunological parameters were also improved in HD mice. Studies on molecular mechanisms of genistein-mediated stimulation of autophagy in HD cells indicated the involvement of the FOXO3-related pathway. In conclusion, treatment with genistein stimulates the autophagy process in the brains of HD mice, leading to correction of symptoms of HD, suggesting that it might be considered as a potential drug for this disease. Combined with a very recently published report indicating that impaired autophagy may be a major cause of neurodegenerative changes, these results may indicate the way to the development of effective therapeutic approaches for different neurodegenerative diseases by testing compounds (or possibly combinations of compounds) capable of stimulating autophagy and/or unblocking this process.Abbreviations: CNS: central nervous system; EPM: elevated plus-maze; GOT1/ASPAT: glutamic-oxaloacetic transaminase 1, soluble; GPT/ALAT/ALT: glutamic pyruvic transaminase, soluble; HD: Huntington disease; HTT: huntingtin; IL: interleukin; mHTT: mutant huntingtin; NOR: novel object recognition; MWM: Morris water maze; OF: open field; ROS: reactive oxygen species; TNF: tumor necrosis factor.

Role of Autophagy and Mitophagy in Neurodegenerative Disorders

Autophagy is a self-destructive cellular process that removes essential metabolites and waste from inside the cell to maintain cellular health. Mitophagy is the process by which autophagy causes disruption inside mitochondria and the total removal of damaged or stressed mitochondria, hence enhancing cellular health. The mitochondria are the powerhouses of the cell, performing essential functions such as ATP (adenosine triphosphate) generation, metabolism, Ca2+ buffering, and signal transduction. Many different mechanisms, including endosomal and autophagosomal transport, bring these substrates to lysosomes for processing. Autophagy and endocytic processes each have distinct compartments, and they interact dynamically with one another to complete digestion. Since mitophagy is essential for maintaining cellular health and using genetics, cell biology, and proteomics techniques, it is necessary to understand its beginning, particularly in ubiquitin and receptor-dependent signalling in injured mitochondria. Despite their similar symptoms and emerging genetic foundations, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) have all been linked to abnormalities in autophagy and endolysosomal pathways associated with neuronal dysfunction. Mitophagy is responsible for normal mitochondrial turnover and, under certain physiological or pathological situations, may drive the elimination of faulty mitochondria. Due to their high energy requirements and post-mitotic origin, neurons are especially susceptible to autophagic and mitochondrial malfunction. This article focused on the importance of autophagy and mitophagy in neurodegenerative illnesses and how they might be used to create novel therapeutic approaches for treating a wide range of neurological disorders.

A multi-layered network model identifies Akt1 as a common modulator of neurodegeneration

The accumulation of misfolded and aggregated proteins is a hallmark of neurodegenerative proteinopathies. Although multiple genetic loci have been associated with specific neurodegenerative diseases (NDs), molecular mechanisms that may have a broader relevance for most or all proteinopathies remain poorly resolved. In this study, we developed a multi-layered network expansion (MLnet) model to predict protein modifiers that are common to a group of diseases and, therefore, may have broader pathophysiological relevance for that group. When applied to the four NDs Alzheimer's disease (AD), Huntington's disease, and spinocerebellar ataxia types 1 and 3, we predicted multiple members of the insulin pathway, including PDK1, Akt1, InR, and sgg (GSK-3β), as common modifiers. We validated these modifiers with the help of four Drosophila ND models. Further evaluation of Akt1 in human cell-based ND models revealed that activation of Akt1 signaling by the small molecule SC79 increased cell viability in all models. Moreover, treatment of AD model mice with SC79 enhanced their long-term memory and ameliorated dysregulated anxiety levels, which are commonly affected in AD patients. These findings validate MLnet as a valuable tool to uncover molecular pathways and proteins involved in the pathophysiology of entire disease groups and identify potential therapeutic targets that have relevance across disease boundaries. MLnet can be used for any group of diseases and is available as a web tool at http://ssbio.cau.ac.kr/software/mlnet.

Therapeutic potential of lithium chloride and valproic acid against neuronopathic types of mucopolysaccharidoses through induction of the autophagy process

Mucopolysaccharidoses (MPS) are a group of inherited disorders, caused by mutations in the genes coding for proteins involved (directly or indirectly) in glycosaminoglycan (GAG) degradation. A lack or drastically decreased residual activity of a GAG-degrading enzyme leads to the storage of these compounds, thus damaging proper functions of different cells, including neurons. The disease leads to serious psycho-motor dysfunctions and death before reaching the adulthood. Until now, induction of the autophagy process was considered as one of the therapeutic strategies for treatment of diseases caused by protein aggregation (Alzheimer's, Parkinson's, and Huntington's diseases). However, this strategy has only been recently suggested as a potential therapy for MPS. In this work, we show that the pharmacological stimulation of autophagy, by using valproic acid and lithium chloride, led to accelerated degradation of accumulated GAGs. Cytotoxicity tests indicated the safety of the use of the investigated compounds. We observed an increased number of lysosomes and enhanced degradation of heparan sulfate (one of GAGs). Induction of the autophagy process was confirmed by measuring abundance of the marker proteins, including LC3-II. Moreover, inhibition of this process resulted in abolition of the valproic acid- and LiCl-mediated reduction in GAG levels. This is the first report on the possibility of using valproic acid and lithium chloride for reducing levels of GAGs in neuronopathic forms of MPS.

The Komagatella phaffii ACG1 gene, encoding β-1,6-N-acetylglucosaminyltransferase, is involved in the autophagy of cytosolic and peroxisomal proteins

The methylotrophic yeast Komagataella phaffii is considered one of the most effective producers of recombinant proteins of industrial importance. Effective producers should be characterized by the maximal reduction of degradation of the cytosolic recombinant proteins. The mechanisms of degradation of cytosolic proteins in K. phaffii have not been elucidated; however, data suggest that they are partially degraded in the autophagic pathway. To identify factors that influence this process, a developed system for the selection of recombinant strains of K. phaffii with impaired autophagic degradation of the heterologous model cytosolic protein (yeast β-galactosidase) was used for insertional tagging of the genes involved in cytosolic proteins degradation. In one of the obtained strains, the insertion cassette disrupted the open reading frame of the gene encoding β-1,6-N-acetylglucosaminyltransferase. A recombinant strain with deletion of this gene was also obtained. The rate of degradation of the β-galactosidase enzyme was two times slower in the insertion mutant and 1.5 times slower in the deletion strain as compared to the parental strain with native β-1,6-N-acetylglucosaminyltransferase. The rate of degradation of native K. phaffii cytosolic and peroxisomal enzymes, formaldehyde dehydrogenase, formate dehydrogenase, and alcohol oxidase, respectively, showed similar trends to that of β-galactosidase-slower degradation in the deletion and insertional mutants as compared to the wild-type strain, but faster protein degradation relative to the strain completely defective in autophagy. We conclude that K. phaffii gene designated ACG1, encoding β-1,6-N-acetylglucosaminyltransferase, is involved in autophagy of the cytosolic and peroxisomal proteins.

Autophagy characteristics of phytoestrogens in management and prevention of diseases: A narrative review of in-vivo and in-vitro studies

Phytoestrogens are non-steroid polyphenolic materials present in 300 plants. Regarding their structural similarities to estradiol, phytoestrogens attach to estrogen receptors and display anti- or pro-estrogenic activities. This review explored phytoestrogens' potential advantages and autophagy properties in light of their future application for disease management, highlighting how phytoestrogens could modulate autophagy. Research has examined the prospective benefits of phytoestrogens for the anticipation and management of various conditions, including signs of menopause, tumors, skin deterioration, osteoporosis, heart disease, neurodegenerative conditions, disorders of the immune system, and metabolic syndrome, owing to their therapeutic effects. As phytoestrogens can activate or inhibit autophagy, which has antioxidant, apoptotic, anti-mutagenic, anticancer, transcriptional, and genomic impacts on cancer and aging illnesses, phytoestrogens could influence diseases through the modulation of autophagy. The collaborative research on animal models, utilization of genetic techniques, and administration of pharmacologically active substances has indicated the possible therapeutic benefits of autophagy modulation in various illnesses. Further research is required to illustrate the pathways by which phytoestrogens modulate autophagy and the possible therapeutic effects on these diseases.

Phytotherapeutic targeting of the mitochondria in neurodegenerative disorders

Neurodegenerative diseases are characterized by degeneration or cellular atrophy within specific structures of the brain. Neurons are the major target of neurodegeneration. Neurons utilize 75-80% of the energy produced in the brain. This energy is either formed by utilizing the glucose provided by the cerebrovascular blood flow or by the in-house energy producers, mitochondria. Mitochondrial dysfunction has been associated with neurodegenerative diseases. But recently it has been noticed that neurodegenerative diseases are often associated with cerebrovascular diseases. Cerebral blood flow requires vasodilation which to an extent regulated by mitochondria. We hypothesize that when mitochondrial functioning is disrupted, it is not able to supply energy to the neurons. This disruption also affects cerebral blood flow, further reducing the possibilities of energy supply. Loss of sufficient energy leads to neuronal dysfunction, atrophy, and degeneration. In this chapter, we will discuss the metabolic modifications of mitochondria in aging-related neurological disorders and the potential of phytocompounds targeting them.

Roles of genistein in learning and memory during aging and neurological disorders

Genistein (GEN) is a non-steroidal phytoestrogen that belongs to the isoflavone class. It is abundantly found in soy. Soy and its products are used as food components in many countries including India. The present review is focused to address roles of GEN in brain functions in the context of learning and memory as a function of aging and neurological disorders. Memory decline is one of the most disabling features observed during normal aging and age-associated neurodegenerative disorders namely Alzheimer's disease (AD) and Parkinson's disease (PD), etc. Anatomical, physiological, biochemical and molecular changes in the brain with advancement of age and pathological conditions lead to decline of cognitive functions. GEN is chemically comparable to estradiol and binds to estrogen receptors (ERs). GEN acts through ERs and mimics estrogen action. After binding to ERs, GEN regulates a plethora of brain functions including learning and memory; however detailed study still remains elusive. Due to the neuroprotective, anti-oxidative and anti-inflammatory properties, GEN is used to restore or improve memory functions in different animal models and humans. The present review may be helpful to understand roles of GEN in learning and memory during aging and neurological disorders, its direction of research and therapeutic perspectives.

Tubulin Cytoskeleton in Neurodegenerative Diseases–not Only Primary Tubulinopathies

Neurodegenerative diseases represent a large group of disorders characterized by gradual loss of neurons and functions of the central nervous systems. Their course is usually severe, leading to high morbidity and subsequent inability of patients to independent functioning. Vast majority of neurodegenerative diseases is currently untreatable, and only some symptomatic drugs are available which efficacy is usually very limited. To develop novel therapies for this group of diseases, it is crucial to understand their pathogenesis and to recognize factors which can influence the disease course. One of cellular structures which dysfunction appears to be relatively poorly understood in the light of neurodegenerative diseases is tubulin cytoskeleton. On the other hand, its changes, both structural and functional, can considerably influence cell physiology, leading to pathological processes occurring also in neurons. In this review, we summarize and discuss dysfunctions of tubulin cytoskeleton in various neurodegenerative diseases different than primary tubulinopathies (caused by mutations in genes encoding the components of the tubulin cytoskeleton), especially Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, prion diseases, and neuronopathic mucopolysaccharidoses. It is also proposed that correction of these disorders might attenuate the progress of specific diseases, thus, finding newly recognized molecular targets for potential drugs might become possible.

Rosemary Extract-Induced Autophagy and Decrease in Accumulation of Collagen Type I in Osteogenesis Imperfecta Skin Fibroblasts

Osteogenesis imperfecta (OI) is a heterogeneous connective tissue disease mainly caused by structural mutations in type I collagen. Mutant collagen accumulates intracellularly, causing cellular stress that has recently been shown to be phenotype-related. Therefore, the aim of the study was to search for potential drugs reducing collagen accumulation and improving OI fibroblast homeostasis. We found that rosemary extract (RE), which is of great interest to researchers due to its high therapeutic potential, at concentrations of 50 and 100 µg/mL significantly reduced the level of accumulated collagen in the fibroblasts of four patients with severe and lethal OI. The decrease in collagen accumulation was associated with RE-induced autophagy as was evidenced by an increase in the LC3-II/LC3-I ratio, a decrease in p62, and co-localization of type I collagen with LC3-II and LAMP2A by confocal microscopy. The unfolded protein response, activated in three of the four tested cells, and the level of pro-apoptotic markers (Bax, CHOP and cleaved caspase 3) were attenuated by RE. In addition, the role of RE-modulated proteasome in the degradation of unfolded procollagen chains was investigated. This study provides new insight into the beneficial effects of RE that may have some implications in OI therapy targeting cellular stress.

Oxidative stress-mediated memory impairment during aging and its therapeutic intervention by natural bioactive compounds

Aging and associated neurodegenerative diseases are accompanied by the decline of several brain functions including cognitive abilities. Progressive deleterious changes at biochemical and physiological levels lead to the generation of oxidative stress, accumulation of protein aggregates, mitochondrial dysfunctions, loss of synaptic connections, and ultimately neurodegeneration and cognitive decline during aging. Oxidative stress that arises due to an imbalance between the rates of production and elimination of free radicles is the key factor for age-associated neurodegeneration and cognitive decline. Due to high energy demand, the brain is more susceptible to free radicals-mediated damages as they oxidize lipids, proteins, and nucleic acids, thereby causing an imbalance in the homeostasis of the aging brain. Animal, as well as human subject studies, showed that with almost no or few side effects, dietary interventions and plant-derived bioactive compounds could be beneficial to recovering the memory or delaying the onset of memory impairment. As the plant-derived bioactive compounds have antioxidative properties, several of them were used to recover the oxidative stress-mediated changes in the aging brain. In the present article, we review different aspects of oxidative stress-mediated cognitive change during aging and its therapeutic intervention by natural bioactive compounds.

Genistein: A focus on several neurodegenerative diseases

Neurodegenerative diseases are caused by the progressive loss of function or structure of nerve cells in the central nervous system. The most common neurodegenerative diseases include Alzheimer's disease, Huntington's disease, motor neuron disease, and Parkinson's disease. Although the physical or mental symptoms of neurodegenerative disease may be relieved by various treatment combinations, there are currently no strategies to directly slow or prevent neurodegeneration. Given the demographic evidence of a rapidly growing aging population and the associated prevalence of these common neurodegenerative diseases, it is paramount to develop safe and effective ways to protect against neurodegenerative diseases. Most neurodegenerative diseases share some common etiologies such as oxidative stress, neuroinflammation, and mitochondrial dysfunction. Genistein is an isoflavone found in soy products that have been shown to exhibit antioxidant, anti-inflammation, and estrogenic properties. Increasing evidence indicates the protective potential of genistein in neurodegenerative disorders. In this review, we aim to provide an overview of the role that genistein plays in delaying the development of neurodegenerative disease. PRACTICAL APPLICATIONS: Genistein is a naturally occurring isoflavone found mainly in soybean, but also green peas, legumes, and peanuts. Genistein is found to pass through the blood-brain barrier and possess a neuroprotective effect. In this review, we discuss studies in support of these actions and the underlying biological mechanisms. Together, these data indicate that genistein may hold neuroprotective effects in either delaying the onset or relieving the symptoms of neurodegenerative disease.

A review on Huntington protein Insight into protein aggregation and therapeutic interventions

Huntington disease (HD) is a distressing, innate neurodegenerative disease that descends from CAG repeat expansion in the huntingtin gene causing behavioral changes, motor dysfunction, and dementia in children and adults. Mutation in huntingtin (HTT) protein has been suggested to cause neuron loss in the cortex and striatum through various mechanisms including abnormal regulation of transcription, proteasomal dysfunction, post-translational modification, and other events, regulating toxicity. Pathogenesis of HD involves cleavage of the huntingtin protein followed by the neuronal accumulation of its aggregated form. Several research groups made possible efforts to reduce huntingtin gene expression, protein accumulation, and protein aggregation using inhibitors and molecular chaperones as developing drugs against HD. Herein, we review the mechanism proposed towards the formation of HTT protein aggregation and the impact of therapeutic strategies for the treatment of HD.

Defective repair of topoisomerase I induced chromosomal damage in Huntington's disease

Topoisomerase1 (TOP1)-mediated chromosomal breaks are endogenous sources of DNA damage that affect neuronal genome stability. Whether TOP1 DNA breaks are sources of genomic instability in Huntington's disease (HD) is unknown. Here, we report defective 53BP1 recruitment in multiple HD cell models, including striatal neurons derived from HD patients. Defective 53BP1 recruitment is due to reduced H2A ubiquitination caused by the limited RNF168 activity. The reduced availability of RNF168 is caused by an increased interaction with p62, a protein involved in selective autophagy. Depletion of p62 or disruption of the interaction between RNAF168 and p62 was sufficient to restore 53BP1 enrichment and subsequent DNA repair in HD models, providing new opportunities for therapeutic interventions. These findings are reminiscent to what was described for p62 accumulation caused by C9orf72 expansion in ALS/FTD and suggest a common mechanism by which protein aggregation perturb DNA repair signaling.

Antibacterial, Antifungal and Anticancer Activities of Compounds Produced by Newly Isolated Streptomyces Strains from the Szczelina Chochołowska Cave (Tatra Mountains, Poland)

Resistance of bacteria, fungi and cancer cells to antibiotics and other drugs is recognized as one of the major problems in current medicine. Therefore, a search for new biologically active compounds able to either kill pathogenic cells or inhibit their growth is mandatory. Hard-to-reach habitats appear to be unexplored sources of microorganisms producing previously unknown antibiotics and other molecules revealing potentially therapeutic properties. Caves belong to such habitats, and Actinobacteria are a predominant group of microorganisms occurring there. This group of bacteria are known for production of many antibiotics and other bioactive compounds. Interestingly, it was demonstrated previously that infection with bacteriophages might enhance production of antibiotics by them. Here, we describe a series of newly isolated strains of Actinobacteria that were found in caves from the Tatra Mountains (Poland). Phage induction tests indicated that some of them may bear active prophages able to produce virions upon treatment with mitomycin C or UV irradiation. Among all the examined bacteria, two newly isolated Streptomyces sp. strains were further characterized to demonstrate their ability to inhibit the growth of pathogenic bacteria (strains of Staphylococcus aureus, Salmonella enterica, Enterococcus sp., Escherichia coli, and Pseudomonas aeruginosa) and fungi (different species and strains from the genus Candida). Moreover, extracts from these Streptomyces strains reduced viability of the breast-cancer cell line T47D. Chemical analyses of these extracts indicated the presence of isomers of dichloranthrabenzoxocinone and 4,10- or 10,12-dichloro-3-O-methylanthrabenzoxocinone, which are putative antimicrobial compounds. Moreover, various previously unknown (unclassified) molecules were also detected using liquid chromatography-mass spectrometry, suggesting that tested Streptomyces strains may synthesize a battery of bioactive compounds with antibacterial, antifungal, and anticancer activities. These results indicate that further studies on the newly isolated Actinobacteria might be a promising approach to develop novel antibacterial, antifungal, and/or anticancer drugs.

A phenolic-rich extract from Ugni molinae berries reduces abnormal protein aggregation in a cellular model of Huntington's disease

Accumulation of misfolded proteins in the brain is a common hallmark of most age-related neurodegenerative diseases. Previous studies from our group identified the presence of anti-inflammatory and antioxidant compounds in leaves derived from the Chilean berry Ugni molinae (murtilla), in addition to show a potent anti-aggregation activity in models of Alzheimer´s disease. However, possible beneficial effects of berry extracts of murtilla was not investigated. Here we evaluated the efficacy of fruit extracts from different genotypes of Chilean-native U. molinae on reducing protein aggregation using cellular models of Huntington´s disease and assess the correlation with their chemical composition. Berry extraction was performed by exhaustive maceration with increasing-polarity solvents. An unbiased automatic microscopy platform was used for cytotoxicity and protein aggregation studies in HEK293 cells using polyglutamine-EGFP fusion proteins, followed by secondary validation using biochemical assays. Phenolic-rich extracts from murtilla berries of the 19-1 genotype (ETE 19-1) significantly reduced polyglutamine peptide aggregation levels, correlating with the modulation in the expression levels of autophagy-related proteins. Using LC-MS and molecular network analysis we correlated the presence of flavonoids, phenolic acids, and ellagitannins with the protective effects of ETE 19-1 effects on protein aggregation. Overall, our results indicate the presence of bioactive components in ethanolic extracts from U. molinae berries that reduce the load of protein aggregates in living cells.

Natural compounds modulate the autophagy with potential implication of stroke

Stroke is considered a leading cause of mortality and neurological disability, which puts a huge burden on individuals and the community. To date, effective therapy for stroke has been limited by its complex pathological mechanisms. Autophagy refers to an intracellular degrading process with the involvement of lysosomes. Autophagy plays a critical role in maintaining the homeostasis and survival of cells by eliminating damaged or non-essential cellular constituents. Increasing evidence support that autophagy protects neuronal cells from ischemic injury. However, under certain circumstances, autophagy activation induces cell death and aggravates ischemic brain injury. Diverse naturally derived compounds have been found to modulate autophagy and exert neuroprotection against stroke. In the present work, we have reviewed recent advances in naturally derived compounds that regulate autophagy and discussed their potential application in stroke treatment.

Genistein Activates Transcription Factor EB and Corrects Niemann-Pick C Phenotype

Niemann-Pick type C disease (NPCD) is a lysosomal storage disease (LSD) characterized by abnormal cholesterol accumulation in lysosomes, impaired autophagy flux, and lysosomal dysfunction. The activation of transcription factor EB (TFEB), a master lysosomal function regulator, reduces the accumulation of lysosomal substrates in LSDs where the degradative capacity of the cells is compromised. Genistein can pass the blood-brain barrier and activate TFEB. Hence, we investigated the effect of TFEB activation by genistein toward correcting the NPC phenotype. We show that genistein promotes TFEB translocation to the nucleus in HeLa TFEB-GFP, Huh7, and SHSY-5Y cells treated with U18666A and NPC1 patient fibroblasts. Genistein treatment improved lysosomal protein expression and autophagic flux, decreasing p62 levels and increasing those of the LC3-II in NPC1 patient fibroblasts. Genistein induced an increase in β-hexosaminidase activity in the culture media of NPC1 patient fibroblasts, suggesting an increase in lysosomal exocytosis, which correlated with a decrease in cholesterol accumulation after filipin staining, including cells treated with U18666A and NPC1 patient fibroblasts. These results support that genistein-mediated TFEB activation corrects pathological phenotypes in NPC models and substantiates the need for further studies on this isoflavonoid as a potential therapeutic agent to treat NPCD and other LSDs with neurological compromise.

Potential roles of natural products in the targeting of proteinopathic neurodegenerative diseases

Defective proteostasis is associated with the gradual accumulations of misfolded proteins and is a hallmark of many age-associated neurodegenerative diseases. In the aged brain, maintenance of the proteostasis network presents a substantial challenge, and its loss contributes to the onset and progression of neurological diseases associated with cognitive decline due to the generation of toxic protein aggregates, a process termed 'proteinopathy'. Emerging evidence suggests that reversing proteinopathies by boosting proteostasis might provide an effective means of preventing neurodegeneration. From this perspective, phytochemicals may play significant roles as potent modulators of the proteostasis network, as previous reports have suggested they can interact with various network components to modify pathologies and confer neuroprotection. This review focuses on some potent phytochemicals that directly or indirectly modulate the proteostasis network and on their possible molecular targets. In addition, we propose strategies for the natural product-based modulation of proteostasis machinery that target proteinopathies.

Homozygosity of BACHD rats not only causes strong behavioral deficits in young female rats but also a reduced breeding success

Huntington's disease is known to be a purely genetic disease based on an expansion of a CAG base triplet repeat in the coding region of the Huntingtin gene. Some years ago, researchers were able to introduce the extensive full-length gene sequence of the mutant huntingtin gene into a rodent model. The resulting BACHD rat is already well characterized for behavioral deficits. So far, all analyses in this preclinical rat model were performed in male hemizygous animals. As homozygosity of transgenic models often causes an amplification of the phenotype and female HD patients present a stronger phenotype compared to men, we established a homozygous breeding colony and tested 2 and 5 months old homozygous male and female BACHD rats in a behavioral test battery. The tests included the grip strength test, Rota Rod, elevated plus maze, passive avoidance, and Barnes maze test. Our results show strong deficits in young female homozygous BACHD rats including increased body weight, motor deficits, muscle weakness, reduced anxiety and hypoactivity, as well as learning and memory deficits. Analysis of male homozygous BACHD rats showed only weak disease symptoms, similar compared to male hemizygous BACHD rats of already published studies. Evaluation of the breeding success showed that homozygous BACHD have a reduced number of pups at the time of birth that even decreases until weaning. Our results suggest that the phenotype of homozygous male BACHD rats barely differs from already published results of hemizygous BACHD rats while female homozygous BACHD rats display strong and early alterations.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

One drug to treat many diseases: unlocking the economic trap of rare diseases

There are two major problems with the development of therapies for rare diseases. First, among over 7000 such diseases, the vast majority are caused by genetic defects and/or include neurodegeneration, making them very difficult to treat. Second, drugs for rare diseases, so-called orphan drugs, are extremely expensive, as only a small number of patients are interested in purchasing them. This results in the appearance of a specific economic trap of rare diseases; namely, despite high biomedical, pharmaceutical and technological potential, the development of new orphan drugs is blocked by the economic reality. The purpose of this work was to find a potential solution that might resolve this economic trap of rare diseases. A literature review was conducted, and a hypothesis was formulated assuming that the use of one drug for the treatment of many rare diseases might overcome the economic trap. We provide examples showing that finding such drugs is possible. Thus, a possible solution for the problem of developing orphan drugs is presented. Further preclinical and clinical studies, although neither easy nor inexpensive, should verify whether the hypothesis regarding the possibility of unlocking the economic trap of rare diseases is valid.

Proteasome Composition and Activity Changes in Cultured Fibroblasts Derived From Mucopolysaccharidoses Patients and Their Modulation by Genistein

In this study, we have asked whether proteasome composition and function are affected in cells derived from patients suffering from all types of mucopolysaccharidosis (MPS), an inherited metabolic disease caused by accumulation of undegraded glycosaminoglycans (GAGs). Moreover, we have tested if genistein, a small molecule proposed previously as a potential therapeutic agent in MPS, can modulate proteasomes, which might shed a new light on the molecular mechanisms of action of this isoflavone as a potential drug for macromolecule storage diseases. Significant changes in expression of various proteasome-linked genes have been detected during transcriptomic (RNA-seq) analyses in vast majority of MPS types. These results were corroborated by demonstration of increased proteasomal activities in MPS cells. However, GAGs were not able to stimulate the 26S proteasome in vitro, suggesting that the observed activation in cells is indirect rather than arising from direct GAG-proteasome interactions. Genistein significantly reduced proteasomal activities in fibroblasts derived from patients suffering from all MPS types, while its effects on in vitro 26S proteasome activity were negligible. Unexpectedly, levels of many proteasomal subunits were increased in genistein-treated MPS cells. On the other hand, this ostensible discrepancy between results of experiments designed for estimation of effects of genistein on proteasome activities and abundance of proteasomal subunits can be explained by demonstration that in the presence of this isoflavone, levels of ubiquitinated proteins were decreased. The genistein-mediated reduction of proteasomal activities might have beneficial effects in cells of MPS patients due to potential increasing of residual activities of defective lysosomal enzymes which would otherwise be subjected to efficient ubiquitination and proteasomal degradation as misfolded proteins. These results indicate another activity of genistein (apart from previously demonstrated reduction of GAG synthesis efficiency, stimulation of lysosomal biogenesis, and activation of the autophagy process) which can be beneficial in the use of this small molecule in treatment of MPS.

Hair dysmorphology in the R6/1 and R6/2 mouse models of Huntington's disease

Huntington's disease (HD), caused by expansion of CAG repeats in the 1st exon of the HTT gene, is a disorder inherited in an autosomal dominant manner. HD symptoms include chorea, behavioral disturbances and cognitive decline. Although it is described as a neurodegenerative disease, due to expression of HTT in all types of cells, peripheral symptoms also occur. R6/1 and R6/2 mouse lines, which demonstrate many different phenotypical disturbances, are among the most commonly used HD animal models. Nevertheless, in this report, we underlined, for the first time, a previously undescribed R6/1 and R6/2 feature, hair dysmorphology. We observed changes in the general view of pelage, as well as specific changes in the shape of hair, assessed under electron microscope (deep cavity and hilly hair surface or concave and convex areas on the long hair axis with an appearance of the hair as flat). Hair diameter was significantly increased in both HD mouse models relative to control animals. Moreover, loosened contact between the scales and loosened scale texture were observed in R6/1 and R6/2. Thus, this study highlighted that the hair morphology might be a useful, noninvasive and simple marker of a widely used HD mouse models, R6/1 and R6/2 lines, particularly in testing effects of potential therapeutics or disease progression.

Has resveratrol a potential for mucopolysaccharidosis treatment?

Mucopolysaccharidoses (MPS) represent a devastating group of lysosomal storage diseases (LSD) affecting approximately 1 in 25,000 individuals, where degradation of glycosaminoglycans (GAG) by lysosomal enzymes is impaired due to mutations causing defects in one of GAG-degrading enzymes. The most commonly used therapy for MPS is enzyme replacement therapy, consisting of application of an active form of the missing enzyme. However, supply of the missing enzyme is not enough in case of MPS types whose symptoms are expressed in central nervous system (CNS), as enzyme does not cross the blood-brain barrier. Moreover, even though enzyme replacement therapy for non-neuronopathic MPS IVA type is approved, it has a limited impact on bone abnormalities, that are one of main symptoms in the disease. Therefore, research into alternative therapeutic approaches for these types of MPS is highly desirable. One such alternative strategy is accelerated degradation of GAG by induction of autophagy. Autophagy is a process of lysosomal degradation of macromolecules that become abnormal or unnecessary for cells. One of the latest discoveries is that GAGs can also be such molecules. Potential drug should also cross blood-brain barrier and be safe in long-term therapy. It seems that one of the polyphenols, resveratrol, can meet the requirements. The mechanism of its action in autophagy stimulation is pleiotropic. Therefore, in this review, we will briefly discuss potential of resveratrol treatment for mucopolysaccharidosis through autophagy stimulation based on research in diseases with similar outcome.

Genistein Induces Adipogenic and Autophagic Effects in Rainbow Trout (Oncorhynchus mykiss) Adipose Tissue: In Vitro and In Vivo Models

Soybeans are one of the most used alternative dietary ingredients in aquafeeds. However, they contain phytoestrogens like genistein (GE), which can have an impact on fish metabolism and health. This study aimed to investigate the in vitro and in vivo effects of GE on lipid metabolism, apoptosis, and autophagy in rainbow trout (Oncorhynchus mykiss). Primary cultured preadipocytes were incubated with GE at different concentrations, 10 or 100 μM, and 1 μM 17β-estradiol (E2). Furthermore, juveniles received an intraperitoneal injection of GE at 5 or 50 µg/g body weight, or E2 at 5 µg/g. In vitro, GE 100 μM increased lipid accumulation and reduced cell viability, apparently involving an autophagic process, indicated by the higher LC3-II protein levels, and higher lc3b and cathepsin d transcript levels achieved after GE 10 μM. In vivo, GE 50 µg/g upregulated the gene expression of fatty acid synthase (fas) and glyceraldehyde-3-phosphate dehydrogenase in adipose tissue, suggesting enhanced lipogenesis, whereas it increased hormone-sensitive lipase in liver, indicating a lipolytic response. Besides, autophagy-related genes increased in the tissues analyzed mainly after GE 50 µg/g treatment. Overall, these findings suggest that an elevated GE administration could lead to impaired adipocyte viability and lipid metabolism dysregulation in rainbow trout.

Mechanisms of Mitochondrial Dysfunction in Lysosomal Storage Disorders: A Review

Mitochondrial dysfunction is emerging as an important contributory factor to the pathophysiology of lysosomal storage disorders (LSDs). The cause of mitochondrial dysfunction in LSDs appears to be multifactorial, although impaired mitophagy and oxidative stress appear to be common inhibitory mechanisms shared amongst these heterogeneous disorders. Once impaired, dysfunctional mitochondria may impact upon the function of the lysosome by the generation of reactive oxygen species as well as depriving the lysosome of ATP which is required by the V-ATPase proton pump to maintain the acidity of the lumen. Given the reported evidence of mitochondrial dysfunction in LSDs together with the important symbiotic relationship between these two organelles, therapeutic strategies targeting both lysosome and mitochondrial dysfunction may be an important consideration in the treatment of LSDs. In this review we examine the putative mechanisms that may be responsible for mitochondrial dysfunction in reported LSDs which will be supplemented with morphological and clinical information.

2-Hydroxypropyl-gamma-cyclodextrin overcomes NPC1 deficiency by enhancing lysosome-ER association and autophagy

Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder caused by mutations in NPC1 and NPC2 genes that result in an accumulation of cholesterol in lysosomes. The majority of children with NPC die in adolescence. Currently, no FDA-approved therapies exist for NPC and the mechanisms of NPC disease are not fully understood. Our recent study and the reports from other laboratories showed that 2-hydroxypropyl-γ-cyclodextrin (HPγCD) alleviates cholesterol accumulation in NPC1-deficient cells in spite of its low binding affinity for cholesterol. In this study, we explored the cellular changes that are induced upon HPγCD treatment in NPC1 patient-derived fibroblasts. We show that HPγCD treatment increases lysosome-ER association and enhances autophagic activity. Our study indicates that HPγCD induces an activation of the transcription factor EB (TFEB), a master regulator of lysosomal functions and autophagy. Lysosome-ER association could potentially function as conduits for cholesterol transport from lysosomes to the ER. Accumulating evidence suggests a role for autophagy in rescuing the cholesterol accumulation in NPC and other degenerative diseases. Collectively, our findings suggest that HPγCD restores cellular homeostasis in NPC1-deficient cells via enhancing lysosomal dynamics and functions. Understanding the mechanisms of HPγCD-induced cellular pathways could contribute to effective NPC therapies.

The cholesterol 24-hydroxylase activates autophagy and decreases mutant huntingtin build-up in a neuroblastoma culture model of Huntington's disease

OBJECTIVE

Compromised brain cholesterol turnover and altered regulation of brain cholesterol metabolism have been allied with some neurodegenerative diseases, including Huntington's disease (HD). Following our previous studies in HD, in this study we aim to investigate in vitro in a neuroblastoma cellular model of HD, the effect of CYP46A1 overexpression, an essential enzyme in cholesterol metabolism, on huntingtin aggregation and levels.

RESULTS

We found that CYP46A1 reduces the quantity and size of mutant huntingtin aggregates in cells, as well as the levels of mutant huntingtin protein. Additionally, our results suggest that the observed beneficial effects of CYP46A1 in HD cells are linked to the activation of autophagy. Taken together, our results further demonstrate that CYP46A1 is a pertinent target to counteract HD progression.

Haplotyping by CRISPR-mediated DNA circularization (CRISPR-hapC) broadens allele-specific gene editing

Allele-specific protospacer adjacent motif (asPAM)-positioning SNPs and CRISPRs are valuable resources for gene therapy of dominant disorders. However, one technical hurdle is to identify the haplotype comprising the disease-causing allele and the distal asPAM SNPs. Here, we describe a novel CRISPR-based method (CRISPR-hapC) for haplotyping. Based on the generation (with a pair of CRISPRs) of extrachromosomal circular DNA in cells, the CRISPR-hapC can map haplotypes from a few hundred bases to over 200 Mb. To streamline and demonstrate the applicability of the CRISPR-hapC and asPAM CRISPR for allele-specific gene editing, we reanalyzed the 1000 human pan-genome and generated a high frequency asPAM SNP and CRISPR database (www.crispratlas.com/knockout) for four CRISPR systems (SaCas9, SpCas9, xCas9 and Cas12a). Using the huntingtin (HTT) CAG expansion and transthyretin (TTR) exon 2 mutation as examples, we showed that the asPAM CRISPRs can specifically discriminate active and dead PAMs for all 23 loci tested. Combination of the CRISPR-hapC and asPAM CRISPRs further demonstrated the capability for achieving highly accurate and haplotype-specific deletion of the HTT CAG expansion allele and TTR exon 2 mutation in human cells. Taken together, our study provides a new approach and an important resource for genome research and allele-specific (haplotype-specific) gene therapy.

Expression of genes involved in apoptosis is dysregulated in mucopolysaccharidoses as revealed by pilot transcriptomic analyses

Mucopolysaccharidoses (MPS), a group of lysosomal storage diseases (LSD), are inherited disorders caused by mutations in genes coding for enzymes involved in the degradation of glycosaminoglycans (GAGs). Therefore, accumulated GAGs in lysosomes lead to severe symptoms in patients and significantly shortened life span. Although GAG accumulation in cells is the primary cellular defect in MPS, recent reports indicated that severe changes in cellular processes occur there as secondary or tertiary effects, which may contribute significantly to the disease pathomechanism. Apoptosis is one of such process, while mechanisms leading to dysregulation of this process in MPS remain largely unknown. To learn about these mechanisms, we have performed transcriptomic studies using cultures of fibroblasts derived from patients suffering from all types and subtypes of MPS, and assessed genes related to apoptosis. We found that there are significant changes in expression levels of many such genes relative to control fibroblasts (Human Dermal Fibroblasts-adult cell line), and the number of down- or up-regulated transcripts was between 19 and 73 in different MPS types. We have identified apoptosis-related genes, which were considerably dysregulated in many MPS types, as well as those in which expression was significantly changed in specific MPS types. BNIP3, C1D, CLU, GPER1, KREMEN1, and PRKCD genes displayed the most changed expression profiles in most MPS types relative to control cells. Caspase 3/7 activity was increased in MPS IVA and IX. These results indicate that changes in apoptosis, observed in MPS, may arise, at least partially, from dysregulation of genes coding for proteins involved in this process.

Mucopolysaccharidosis and Autophagy: Controversies on the Contribution of the Process to the Pathogenesis and Possible Therapeutic Applications

Mucopolysaccharidosis (MPS) consists of a group of 11 enzymatic defects which result in accumulation of undegraded glycosaminoglycans (GAG) in lysosomes. MPS is a severe metabolic disease for which only bone marrow/hematopoietic stem cell transplantation and enzyme replacement therapy are current therapeutic options. However, they are available for only a few of MPS types, and are ineffective in treatment of central nervous system. Recent studies indicated that the autophagy process can be impaired in MPS, but various contradictory conclusions have been published in this matter. Nevertheless, stimulation of autophagy has been proposed as a potential therapeutic option for MPS, and very recent results suggest that such approach might be effective in improving MPS symptoms. Still the mechanisms of autophagy changes in MPS are not clear, and efficiency of autophagy activation in clearing the storage material requires further investigation. These problems are summarized and discussed in this review.

Genistein induces degradation of mutant huntingtin in fibroblasts from Huntington's disease patients

Mutations in the HTT gene, consisting of expansion of CAG triplets, cause the Huntington's disease (HD), one of the major neurodegenerative disorders. Formation of aggregates of mutant huntingtin (mHTT, the product of the mutant HTT gene) leads to cellular dysfunctions, and subsequent neurodegeneration which manifest clinically as motor abnormalities and cognitive deficits. We recently used immortalized HEK-293 cells expressing the 1st exon of the mutant HTT gene as a cellular model of HD, and showed that the stimulation of autophagy by genistein corrected the mutant phenotype. However, effects of genistein on HD patient-derived cells remained unknown. In this report, we demonstrated that genistein also instigated degradation of mHTT in fibroblasts derived from HD patients. This was assessed as a significant decrease in the levels of HTT in HD fibroblasts measured by Western-blotting, and the disappearance of intracellular mHTT aggregates in cells observed by fluorescent microscopy. Fibroblasts derived from control persons were not affected by genistein treatment. These results indicate that genistein can improve HD phenotype in patient-derived cells, and substantiates the need for further studies of this isoflavone as a potential therapeutic agent.

Protein Misfolding and ER Stress in Huntington's Disease

Increasing evidence in recent years indicates that protein misfolding and aggregation, leading to ER stress, are central factors of pathogenicity in neurodegenerative diseases. This is particularly true in Huntington's disease (HD), where in contrast with other disorders, the cause is monogenic. Mutant huntingtin interferes with many cellular processes, but the fact that modulation of ER stress and of the unfolded response pathways reduces the toxicity, places these mechanisms at the core and gives hope for potential therapeutic approaches. There is currently no effective treatment for HD and it has a fatal outcome a few years after the start of symptoms of cognitive and motor impairment. Here we will discuss recent findings that shed light on the mechanisms of protein misfolding and aggregation that give origin to ER stress in neurodegenerative diseases, focusing on Huntington's disease, on the cellular response and on how to use this knowledge for possible therapeutic strategies.

Autophagy-dependent mechanism of genistein-mediated elimination of behavioral and biochemical defects in the rat model of sporadic Alzheimer's disease

Alzheimer's disease is one of severe neurological diseases for which no effective treatment is currently available. The use of genistein (5,7-dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) has been proposed previously as one of approaches to improve the disease symptoms, as some positive effects of this compound in cellular and animal models were reported. Inhibition of apoptosis and antioxidative functions were suggested as causes of these effects. Here, we demonstrate that high genistein dose (150 mg/kg/day; the dose significantly higher than those used previously in AD studies by others) can activate autophagy in the streptozotocin-induced rat model of the sporadic form of AD. We found that this dose of genistein led to complete degradation of β-amyloid and hyperphosphorylated tau protein in the brain, while experiments with cell cultures demonstrated that these effects require autophagy stimulation, which has never been shown before. Importantly, behavior of high dose genistein-treated AD rats was completely corrected, i.e. it was indistinguishable from that of healthy animals. This was observed in all performed behavioral tests: Morris water maze test, elevated plus-maze test, open field test, and locomotor measurements in an actometer. We conclude that autophagy-dependent mechanism is responsible for genistein-mediated correction of AD when this isoflavone is used at the high dose.

Characterization of adenine nucleotide metabolism in the cellular model of Huntington's disease

Huntington's disease (HD) is a neurodegenerative disorder that is caused by expanded CAG repeats within the exon-1 of the huntingtin (HTT) gene. It has been shown that HTT interacts with the proteins involved in the gene transcription, endocytosis and metabolism, nevertheless the biochemical pathways by which mutant HTT causes a cellular dysfunction remain unclear. Thus, this study aimed to establish the role of mutant HTT expansion in energy and nucleotide metabolism deteriorations. We examined HEK 293 T cell line transfected with plasmids expressing wild-type (control) or mutant exon 1 of the HTT gene (HD). Analysis of intracellular concentration of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NAD⁺), as well as activities of intra- and extracellular enzymes of nucleotide catabolism (such as adenine monophosphate deaminase (AMPD), adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and ectonucleoside triphosphate diphosphohydrolase (eNTPD), ecto-5'-nucleotidase (e5NT), ecto-adenosine deaminase (eADA) were performed with high pressure liquid chromatography. Protein concentration was measured with Bradford method. We found diminished intracellular ATP concentration (22.5 ± 1.7 in HD; 29.3 ± 1.4 nmol/mg protein in control), increased ADA activity (27.9 ± 1.0 in HD; 21.1 ± 1.6 nmol/min/mg protein in control) and reduced activities of eNTPD (2.4 ± 0.5 in HD; 5.8 ± 0.7 nmol/min/mg protein in control), e5NT (0.1 ± 0.01 in HD; 0.2 ± 0.01 nmol/min/mg protein in control) and eADA (0.3 ± 0.03 in HD; 0.4 ± 0.04 nmol/min/mg protein in control) while NAD⁺ concentration, AMPD and PNP activities remained unchanged. This study highlights that the mutant HTT expansion resulted in depletion of cellular ATP concentration and reduced rates of extracellular nucleotide breakdown. In conclusion, such changes may contribute to the pathology of HD.

Mitochondrial alterations accompanied by oxidative stress conditions in skin fibroblasts of Huntington's disease patients

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder manifesting as progressive impairment of motor function and different neuropsychiatric symptoms caused by an expansion of CAG repeats in huntingtin gene (HTT). Mitochondrial dysfunction and bioenergetic defects can contribute to the course of the disease, however, the molecular mechanism underlying this process is still largely unknown. In this study, we aimed to determine several mitochondrial parameters in HD fibroblasts and assess their relevance to the disease progression as well as to value mitochondrial pathology in peripheral cells as disease potential biomarker. We showed that HD fibroblasts demonstrate significantly lower growth rate compared to control fibroblasts despite the lack of cell cycle perturbations. In order to investigate mitochondrial contribution to cell growth differences between HD and healthy cells, we provided insight into various mitochondrial parameters. Conducted experiments have revealed a significant reduction of the ATP level in HD fibroblasts accompanied by a decrease in mitochondrial metabolic activity in relation to the cells from healthy donors. Importantly, there were no differences in the mitochondrial membrane potential (mtΔΨ) and OXPHOS complexes' levels. Slightly increased level of mitochondrial superoxide (mt. O2•-), but not cytosolic reactive oxygen species (cyt. ROS), has been demonstrated. We have also observed significantly elevated levels of some antioxidant enzymes (SOD2 and GR) which may serve as an indicator of antioxidant defense system in HD patients. Thus, we suggest that mitochondrial alterations in skin fibroblasts of Huntington's disease patients might be helpful in searching for novel disease biomarkers.

Exploring the Mechanism of Flavonoids Through Systematic Bioinformatics Analysis

Flavonoids are the largest class of plant polyphenols, with common structure of diphenylpropanes, consisting of two aromatic rings linked through three carbons and are abundant in both daily diets and medicinal plants. Fueled by the recognition of consuming flavonoids to get better health, researchers became interested in deciphering how flavonoids alter the functions of human body. Here, systematic studies were performed on 679 flavonoid compounds and 481 corresponding targets through bioinformatics analysis. Multiple human diseases related pathways including cancers, neuro-disease, diabetes, and infectious diseases were significantly regulated by flavonoids. Specific functions of each flavonoid subclass were further analyzed in both target and pathway level. Flavones and isoflavones were significantly enriched in multi-cancer related pathways, flavan-3-ols were found focusing on cellular processing and lymphocyte regulation, flavones preferred to act on cardiovascular related activities and isoflavones were closely related with cell multisystem disorders. Relationship between chemical constitution fragment and biological effects indicated that different side chain could significantly affect the biological functions of flavonoids subclasses. Results will highlight the common and preference functions of flavonoids and their subclasses, which concerning their pharmacological and biological properties.

Autophagy stimulation as a promising approach in treatment of neurodegenerative diseases

Autophagy is a process of degradation of macromolecules in the cytoplasm, particularly proteins of a long half-life, as well as whole organelles, in eukaryotic cells. Lysosomes play crucial roles during this degradation. Autophagy is a phylogenetically old, and evolutionarily conserved phenomenon which occurs in all eukaryotic cells. It can be found in yeast Saccharomyces cerevisiae, insect Drosophila melanogaster, and mammals, including humans. Its high importance for cell physiology has been recognized, and in fact, dysfunctions causing impaired autophagy are associated with many severe disorders, including cancer and metabolic brain diseases. The types and molecular mechanisms of autophagy have been reviewed recently by others, and in this paper they will be summarized only briefly. Regulatory networks controlling the autophagy process are usually described as negative regulations. In contrast, here, we focus on different ways by which autophagy can be stimulated. In fact, activation of this process by different factors or processes can be considered as a therapeutic strategy in metabolic neurodegenerative diseases. These aspects are reviewed and discussed in this article.