The Application of Analytical Techniques to Alpha-Synuclein in Parkinson’s Disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia, as well as non-motor symptoms including cognitive impairment and mood disorders. A hallmark of PD is the accumulation of alpha-synuclein, a presynaptic neuronal protein that aggregates to form Lewy bodies, leading to neuronal dysfunction and cell death. The study of alpha-synuclein and its pathological forms is crucial for understanding the etiology of PD and developing effective diagnostic and therapeutic strategies. Analytical techniques play a pivotal role in elucidating the structure, function, and aggregation mechanisms of alpha-synuclein. Biochemical methods such as Western blotting and enzyme-linked immunosorbent assay (ELISA) are employed to detect and quantify alpha-synuclein in biological samples, offering insights into its expression levels and post-translational modifications. Imaging techniques like immunohistochemistry and positron emission tomography (PET) allow for the visualization of alpha-synuclein aggregates in tissue samples and in vivo, respectively, facilitating the study of its spatial distribution and progression in PD Spectroscopic methods, including nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, provide detailed structural information on alpha-synuclein and its isoforms, aiding in the identification of conformational changes associated with aggregation. Emerging techniques such as cryo-electron microscopy (Cryo-EM) and single-molecule fluorescence enable high-resolution structural analysis and real-time monitoring of alpha-synuclein aggregation dynamics, respectively. The application of these analytical techniques has significantly advanced our understanding of the pathophysiological role of alpha-synuclein in PD. They have contributed to the identification of potential biomarkers for early diagnosis and the evaluation of therapeutic interventions targeting alpha-synuclein aggregation. Despite technical limitations and challenges in clinical translation, ongoing advancements in analytical methodologies hold promise for improving the diagnosis, monitoring, and treatment of Parkinson’s disease through a deeper understanding of alpha-synuclein pathology.

Gut-microbiome-brain axis:the crosstalk between the vagus nerve,alpha-synuclein and the brain in Parkinson's disease

This critical review of the literature shows that there is a close link between the microbiome,the gut,and the brain in Parkinson's disease.The vagus nerve,the main component of the parasympathetic nervous system,is involved in the regulation of immune response,digestion,heart rate,and control of mood.It can detect microbiota metabolites through its afferents,transferring this gut information to the central nervous system.Preclinical and clinical studies have shown the important role played by the gut microbiome and gut-related factors in disease development and progression,as well as treatment responses.These findings suggest that the gut microbiome may be a valuable target for new therapeutic strategies for Parkinson's disease.More studies are needed to better understand the underlying biology and how this axis can be modulated for the patient's benefit.

Subcellular localization of alpha-synuclein aggregates and their interaction with membranes

For more than a decade numerous evidence has been reported on the mechanisms of toxicity of α-synuclein（αS） oligomers and aggregates in α-synucleinopathies.These species were thought to form freely in the cytoplasm but recent reports of αS multimer conformations when bound to synaptic vesicles in physiological conditions,have raised the question about where αS aggregation initiates.In this review we focus on recent literature regarding the impact on membrane binding and subcellular localization of αS toxic species to understand how regular cellular function of αS contributes to pathology.Notably αS has been reported to mainly associate with specific membranes in neurons such as those of synaptic vesicles,ER/Golgi and the mitochondria,while toxic species of αS have been shown to inhibit,among others,neurotransmission,protein trafficking and mitochondrial function.Strategies interfering with αS membrane binding have shown to improve αS-driven toxicity in worms and in mice.Thus,a selective membrane binding that would result in a specific subcellular localization could be the key to understand how aggregation and pathology evolves,pointing out to αS functions that are primarily affected before onset of irreversible damage.

Alpha-synuclein自身抗体用作帕金森病抗体治疗的探索研究

目的:通过从外周血中分离B细胞并进行培养,对外周血中存在的alpha-synuclein(α-syn)自身抗体进行分析,以探索用α-syn自身抗体开发治疗帕金森病(PD)抗体药物的可行性。方法:采集健康捐赠人的外周血并分离外周血B细胞进行培养,对B细胞培养上清进行ELISA结合活性分析,并用硫黄素T(ThT)法检测B细胞培养上清中α-syn自身抗体的生物学活性。结果:细胞培养13 d后,镜检发现B细胞扩增孔数可以达到90%以上,表明B细胞在实验条件下生长良好并能维持抗体分泌能力。ELISA结果表明检测的10530个样品中有48个可以和α-syn单体结合(OD 450>0.5),其中36个可以同时结合α-syn单体和聚合体(OD 450>0.5),并且该36个样品和α-syn家族蛋白β-synuclein以及γ-synuclein无交叉反应,具有α-syn结合特异性。用硫黄素T(ThT)法对该组样品进行的抑制聚合活性检测,结果表明36个样品中有9个样品能够显著性地抑制α-syn单体聚合,并且其中两个样品25G07和55F02的抑制率可以达到50%。结论:可以通过分离培养外周血B细胞获得具有生物学活性的α-syn自身抗体,用作治疗帕金森病的抗体药物研发。

Pathogenic roles of alpha-synuclein in Parkinson’s disease and multiple system atrophy

Alpha-synucleinopathies(α-synucleinopathies)are a diverse group of neurodegenerative diseases comprising Parkinson’s disease(PD),dementia with Lewy bodies(DLB),and multiple system atrophy(MSA).Although in all these diseases there exist abnormal accumulation of alpha-synuclein(α-syn)aggregates in nerve tissues,the pathological lesions formed byα-syn aggregates and their cellular locations are quite different.In PD and DLB,the hallmark pathological lesions are Lewy bodies(LBs)and Lewy neurites(LNs),which are localized in the neuronal somata and processes.In MSA,the characteristic pathologic structures are glial cytoplasmic inclusions,which are deposited in the cytoplasm of oligodendrocytes.The fact that PD and MSA have distinct pathologicalα-syn lesions suggest that different mechanisms play a role in the pathogenesis of the two diseases.In this review article,we compare the clinical manifestations and pathological features of PD and MSA,the two common synucleinopathies,and discuss the potential mechanisms for the formation ofα-syn aggregates and their pathologic roles in PD and MSA.

Implications of alpha-synuclein nitration at tyrosine 39 in methamphetamine-induced neurotoxicity in vitro and in vivo

Methamphetamine is an amphetamine-type psychostimulant that can damage dopaminergic neurons and cause characteristic pathological changes similar to neurodegenerative diseases such as Parkinson's disease. However, its specific mechanism of action is still unclear. In the present study, we established a Parkinson's disease pathology model by exposing SH-SY5 Y cells and C57 BL/6 J mice to methamphetamine. In vitro experiments were performed with 0, 0.5, 1.0, 1.5, 2.0 or 2.5 mM methamphetamine for 24 hours or 2.0 mM methamphetamine for 0-, 2-, 4-, 8-, 16-, and 24-hour culture of SH-SY5 Y cells. Additional experimental groups of SH-SY5 Y cells were administered a nitric oxide inhibitor, 0.1 mM N-nitro-L-arginine, 1 hour before exposure to 2.0 mM methamphetamine for 24 hours. In vivo experiments: C57 BL/6 J mice were intraperitoneally injected with N-nitro-L-arginine(8 mg/kg), eight times, at intervals of 12 hours. Methamphetamine 15 mg/kg was intraperitoneally injected eight times, at intervals of 12 hours, but 0.5-hour after each N-nitro-L-arginine injection in the combined group. Western blot assay was used to determine the expression of nitric oxide synthase, α-synuclein(α-Syn), 5 G4, nitrated α-synuclein at the residue Tyr39(nT39 α-Syn), cleaved caspase-3, and cleaved poly ADP-ribose polymerase(PARP) in cells and mouse brain tissue. Immunofluorescence staining was conducted to measure the positive reaction of NeuN, nT39 α-Syn and 5 G4. Enzyme linked immunosorbent assay was performed to determine the dopamine levels in the mouse brain. After methamphetamine exposure, α-Syn expression increased; the aggregation of α-Syn 5 G4 increased; nT39 α-Syn, nitric oxide synthase, cleaved caspase-3, and cleaved PARP expression increased in the cultures of SH-SY5 Y cells and in the brains of C57 BL/6 J mice; and dopamine levels were reduced in the mouse brain. These changes were markedly reduced when N-nitro-L-arginine was administered with methamphetamine in both SH-SY5 Y cells and C57 BL/6 J mice. These results suggest that nT39 α-Syn aggregation is involved in methamphetamine neurotoxicity.

Nanomolar concentration of alpha-synuclein enhances dopaminergic neuronal survival via Akt pathway

Although alpha-synuclein is generally thought to have a pathological role in Parkinson＇s disease, accumulative evidence exists that alpha-synuclein has a neuroprotective effect. The aim of this study was to evaluate the effect of extracellular alpha-synuclein on dopaminergic cell survival. We assessed cell viability using the 3-（4,5-dimethyt-thiazol-2-yt）-2,5-diphenyltertazolium bromide （MTT） assay both in undifferentiated SH-SY5Y （SHSY） cells and neuronally-differentiated SH-SY5Y （ndSHSY） cells after 24 hour treatment with monomeric alpha-synuclein at various concentrations （0 [control], 50, 100 nmol/L, 1 IJmol/L）. To determine whether cell viability assessed by MTT assay was affected by cell proliferation, 5-bromo-2＇-deoxyuridine （BrdU） incorporation assay was per- formed. Level of both Akt and phosphorylated Akt was measured using western blot method in ndSHSY cells with or without 24 hour alpha-synuclein treatment. Cell viability was increased in ndSHSY cells at the nanomolar concentration of alpha-synuclein, but not in SHSY cells. Proportion of BrdU-positive ndSHSY cells was decreased in alpha-synuclein-treated group compared with control group. Level of phosphorylated Akt in alpha-synuclein-treated group was higher compared with the control group. Our study shows that extracellular alpha-synuclein at nanomolar concentra- tion benefits dopaminergic cell survival via Akt pathway.

Navigating the dynamic landscape of alpha-synuclein morphology: a review of the physiologically relevant tetrameric conformation

N-acetylatedα-synuclein(αSyn)has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson’s disease.In recent years,a physiologically relevant,higher order conformation has been identified as a helical tetramer that is tailored by buried hydrophobic interactions and is distinctively aggregation resistant.The canonical mechanism by which the tetramer assembles remains elusive.As novel biochemical approaches,computational methods,pioneering purification platforms,and powerful imaging techniques continue to develop,puzzling information that once sparked debate as to the veracity of the tetramer has now shed light upon this new counterpart inαSyn neurobiology.Nuclear magnetic resonance and computational studies on multimericαSyn structure have revealed that the protein folding propensity is controlled by small energy barriers that enable large scale reconfiguration.Alternatively,familial mutations ablate tetramerization and reconfigure polymorphic fibrillization.In this review,we will discuss the dynamic landscape ofαSyn quaternary structure with a focus on the tetrameric conformation.

A novel computational method for protein-protein interaction networks prediction of alpha-synuclein

Alpha-synuclein plays an important role in Parkinson's disease(PD).The current study of alpha-synuclein mainly concentrates at the gene level.However, it is found that the study at the protein level has special significance.Meanwhile, there is free information on the Internet, such as databases and algorithms of protein-protein interactions(PPIs).In this paper, a novel method which integrates distributed heterogeneous data sources and algorithms to predict PPIs for alpha-synuclein in silico is proposed.The PPIs generated by the method take advantage of various experimental data, and indicate new information about PPIs for alpha-synuclein.In the end of this paper, the result illustrates that the method is practical.It is hoped that the prediction result obtained by this method can provide guidance for biological experiments of PPIs for alpha-synuclein to reveal possible mechanisms of PD.

Alpha-synuclein truncation and disease

Alpha-synuclein is the major component of Lewy bodies, insoluble protein aggregates, found in patients with Parkinson’s disease, diffuse Lewy body disease, and the Lewy body variant of Alzheimer’s disease. Alpha-synuclein has been found within Lewy bodies to contain many different modifications, including nitration, phosphorylation, ubiquitination, and truncation. C-terminally truncated forms of alpha-synuclein aggregate faster than the full-length protein in vitro, and are thus believed to play a role in Lewy body formation and disease progression. Pathological studies of post mortem brain tissue and the generation of transgenic mouse models further support a role of C-terminally truncated forms of alpha-synuclein in disease. Several enzymes, some of which function extracellularly, have been implicated in the production of these C-terminally truncated forms of alpha-synuclein. However, the enzymes responsible for alphasynuclein truncation in vivo have not yet been firmly established.

Effects of lead exposure on alpha-synuclein and p53 transcription

Objective: Epidemiological studies have found that lead exposure increases the risk for Park-inson’s disease and patients with Parkinson’s disease have lower odds of developing non-smoking-related cancer (1). It would be inter-esting therefore to find the molecular links be-tween Parkinson’s disease and cancer. To do this, we studied mRNA expression of alpha-synuclein gene, a promising genetic marker for Parkinson’s disease, and expression of the tu-mor suppressor gene p53 after oxidative stress induced by lead. Methods: We used ATDC5 cell line as a model of tumor and treated by lead nitrate for 0, 2, 4, 16, 24 and 48 hours. The mRNAs of alpha-synuclein and p53 were quan-tified by reverse transcriptase polymerase chain reaction and expressed as mean (±SD) for 3 samples at each time point. Results: Ex-pression of both of alpha-synuclein and p53 mRNA increased with increasing exposure of lead treatment. The levels of alpha-synuclein and p53 mRNA were correlated with each other (r=0.9830;P<0.001). Conclusion: We propose that lead’s neurotoxicity in PD is caused by al-pha-synuclein expression and aggregation, which releases the inhibitory influence of al-pha-synuclein on p53 expression, thereby al-lowing p53 to act as the cell’s guardian of the genome and reduce tumorigenic potential. Treatments that reduce alpha-synuclein aggre-gation may need to account for a concomitant reduction in p53’s protective effect.

Unfolded annealing molecular dynamics conformers for wild-type and disease-associated variants of alpha-synuclein show no propensity for beta-sheetformation

Aggregation of alpha-synuclein leads to the formation of Lewy bodies in the brains of patients affected by Parkinson's disease (PD). Native human alpha-synuclein is unfolded in solution but assumes a partial alpha-helical conformation upon transient binding to lipid membranes. Annealing Molecular Dynamics (AMD) was used to generate a diverse set of unfolded conformers of free monomeric wild-type alpha-synuclein and PD-associated mutants A30P and A53T. The AMD conformers were compared in terms of secondary structure, hydrogen bond network, solvent-accessible surface per residue, and molecular volume. The objective of these simulations was to identify structural properties near mutation sites and the non-amyloid component (NAC) region that differ between wild- type and disease-associated variants and may be associated to aggregation of alpha- synuclein. Based on experimental evidence, a hypothesis exists that aggregation involves the formation of intermolecular beta sheets. According to our results, disease-associated mutants of alpha-synuclein are no more propense to contain extended beta regions than wild-type alpha-synuclein. Moreover, extended beta structures (necessary for beta sheet formation) were not found at or around positions 30 and 53, or the NAC region in any unfolded conformer of wild-type, A30P or A53T alpha-synuclein, under the conditions of the simulations. These results do not support the hypothesis that the mutant's higher propensity to aggregation results solely from changes in amino acid sequence leading to changes in secondary structure folding propensity.

内源性神经毒素Salsolinol和N-甲基-(R)-salsolinol诱导共培养SH-SY5Y细胞中Alpha-synuclein的聚集

路易氏小体是帕金森病(PD)患者典型的病理特征,其主要由alpha-synuclein(α-syn)蛋白组成。α-syn蛋白在PD患者脑内的聚集通常伴随着T细胞的浸润和神经元细胞的退化。已有的研究表明1-甲基-4-苯基-1,2,3,4-四氢异喹啉(Salsolinol,Sal)N-甲基转移酶与内源性神经毒素1(R),2(N)-二甲基-6,7-二羟基-1,2,3,4-四氢异喹啉(N-甲基-(R)-salsolinol,NMSal)在PD患者淋巴细胞中的升高有关。本文采用稳定转染EGFP的人母细胞瘤SH-SY5Y(SH-EGFP)细胞和人多形性胶质母细胞瘤U87细胞和外周T淋巴细胞Jurkat三种细胞共培养模型来研究内源性神经毒素Sal和NMSal对共同培养体系中SH-EGFP细胞中α-syn蛋白的聚集作用。结果表明,Sal和NMSal可以诱导三细胞共培养体系中SH-EGFP细胞中α-syn的聚集,但不会引起与U87或是Jurkat共培养中SH-EGFP细胞中α-syn的聚集。同时我们还发现Sal和NMSal处理的三细胞共培养体系中SH-EGFP细胞中自噬蛋白LC3表达水平的升高,而自噬诱导剂雷帕霉素可以减少α-syn的聚集。以上结果表明,Jurkat细胞可以影响Sal和NMSal诱导的共培养体系SH-EGFP细胞中α-syn的聚集,并且自噬可能通过清除错误折叠的α-syn蛋白来保护神经元细胞。

Role of alpha-synuclein in neuronal apoptosis induced by rotenone

BACKGROUND： Aggregation of α-synuclein is the major component of Lewy bodies, which are the pathological hallmarks of Parkinson disease （PD）. Although the mechanism of this protein aggregates is unclear, previous study showed that environmental toxins such as rotenone could induce the expression and aggregation of α-synuclein. OBJECTIVE： To observe the role of α-synuclein in PD.DESIGN ： A randomized controlled trial.SETTING ： Beijing Institute for Neuroscience, Capital University of Medical Sciences.MATERIALS ： This study was performed from July 2005 to January 2006 at the Beijing Institute for Neuroscience, Capital University of Medical Sciences. Human dopaminergic neuroblastoma SH-SY5Y cells were provided by Beijing Institute for Neuroscience, Capital University of Medical Sciences. METHODS： Human dopaminergic neuroblastoma SH-SY5Y cells were treated to make α-synuclein over express. Rotenone was added into the medium of cultured both native SH-SY5Y cells and α-synuclein-overexpression SH-SY5Y cells. Lactate dehydrogenase （LDH） assay was used to detect with the cell viability. Flow cytometry and electrophoresis were adopted to measure the cell apoptosis. MAIN OUTCOME MEASURES ： Cell viability, DNA fragmentation, and the number of cell apoptosis.RESULTS： After being treated with rotenone, LDH activity of α-synuclein overexpressed SH-SY5Y cells was （76.625±6.34） μkat/L, which was significantly lower than that of control group （P 〈 0.05）. As compared with normal SH-SY5Y cell, α-synuclein over-expressed SH-SY5Y cells had less DNA fragments and apoptotic cells, α-synuclein might play a role in cell apoptosis induced by rotenone, which was also confirmed by using of antioxidant reagent. CONCLUSION： α-synuclein may partially protect against cell apoptosis induced by rotenone in SH-SY5Y cells.

Alpha-synuclein in body fluids as a diagnostic biomarker for Parkinson’s disease

Parkinson’s disease(PD)is a common neurodegenerative disease,characterized clinically by both motor and non-motor symptoms.Pathologically,PD is hallmarked by the loss of dopaminergic neurons in the substantia nigra(SN)and the formation ofα-synuclein(α-syn)containing inclusion bodies(Lewy pathology)in the surviving neurons.Diagnosis of PD is still based on clinical features.However,owing to the complexity,heterogeneity,and overlapping of its symptoms with other Parkinsonian disorders,correct diagnosis of PD remains a challenge,especially in the early stages.Therefore,there is an urgent need for biomarkers that can help correctly diagnose PD,differentiate PD from other Parkinsonian disorders,monitor the progression of the disease,and evaluate the therapeutic efficacy.Various molecules have been investigated for their utility in diagnosing PD,among whichα-syn is the most extensively investigated one due to its close implication in the etiology and pathogenesis of PD and related diseases.During the past decade,various species ofα-syn,including total,oligomeric,and phosphorylatedα-syn in various tissues,have been investigated for their utility as a potential biomarker for PD diagnosis and differential diagnosis.Various forms ofα-syn in body fluids,including cerebrospinal fluid(CSF),blood plasma,and saliva,are among the ones that are extensively investigated,since the body fluids are relatively accessible compared to the peripheral tissues.The aim of this review is to summarize the progress of studies on the utility ofα-syn in body fluid as a biomarker for PD diagnosis and differential diagnosis.

表达alpha-synuclein A53T神经干细胞系的建立

目的建立表达alpha-synuleinA53T突变体的神经干细胞。方法采用Xho I/Hpa I双酶切paSynA53T-DsRed,将含SynA53T-DsRed片段连接到pBudCE4.1-1X-aSynA53T-DsRed的Xho I/PmeI位点构建pBudCE4.1-2X-aSynA53T-DsRed质粒。利用Lipofectamine2000介导转染2μg的pBudCE4.1-2X-aSynA53T-DsRed到鼠源性神经干细胞(mNSCs)后24 h和72 h观察转染结果。结果成功构建重组质粒pBudCE4.1-2X-aSynA53T-DsRed,转染24 h后其表达率达到(57±3.52)%,72 h的表达率达到了(27.14±3.21)%。结论通过质粒重组及转染技术,成功获得了表达aSynA53T的神经干细胞,为揭示α-synA53T导致帕金森氏症的病理过程提供了平台。

Pathological and physiological functional cross-talks ofα-synuclein and tau in the central nervous system

α-Synuclein and tau are abundant multifunctional brain proteins that are mainly expressed in the presynaptic and axonal compartments of neurons,respectively.Previous works have revealed that intracellular deposition ofα-synuclein and/or tau causes many neurodegenerative disorders,including Alzheimer’s disease and Parkinson’s disease.Despite intense investigation,the normal physiological functions and roles ofα-synuclein and tau are still unclear,owing to the fact that mice with knockout of either of these proteins do not present apparent phenotypes.Interestingly,the co-occurrence ofα-synuclein and tau aggregates was found in post-mortem brains with synucleinopathies and tauopathies,some of which share similarities in clinical manifestations.Furthermore,the direct interaction ofα-synuclein with tau is considered to promote the fibrillization of each of the proteins in vitro and in vivo.On the other hand,our recent findings have revealed thatα-synuclein and tau are cooperatively involved in brain development in a stage-dependent manner.These findings indicate strong cross-talk between the two proteins in physiology and pathology.In this review,we provide a summary of the recent findings on the functional roles ofα-synuclein and tau in the physiological conditions and pathogenesis of neurodegenerative diseases.A deep understanding of the interplay betweenα-synuclein and tau in physiological and pathological conditions might provide novel targets for clinical diagnosis and therapeutic strategies to treat neurodegenerative diseases.

A systematic review of salivary biomarkers in Parkinson's disease

The search fo r reliable and easily accessible biomarkers in Parkinson's disease is receiving a growing emphasis,to detect neurodegeneration from the prodromal phase and to enforce disease-modifying therapies.Despite the need for non-invasively accessible biomarke rs,the majo rity of the studies have pointed to cerebrospinal fluid or peripheral biopsies biomarkers,which require invasive collection procedures.Saliva represents an easily accessible biofluid and an incredibly wide source of molecular biomarkers.In the present study,after presenting the morphological and biological bases for looking at saliva in the search of biomarkers for Parkinson's disease,we systematically reviewed the results achieved so far in the saliva of different cohorts of Parkinson's disease patients.A comprehensive literature search on PubMed and SCOPUS led to the discovery of 289articles.After screening and exclusion,34 relevant articles were derived fo r systematic review.Alpha-synuclein,the histopathological hallmark of Parkinson's disease,has been the most investigated Parkinson's disease biomarker in saliva,with oligomeric alphasynuclein consistently found increased in Parkinson's disease patients in comparison to healthy controls,while conflicting results have been reported regarding the levels of total alpha-synuclein and phosphorylated alpha-synuclein,and few studies described an increased oligomeric alpha-synuclein/total alpha-synuclein ratio in Parkinson's disease.Beyond alpha-synuclein,other biomarkers to rgeting diffe rent molecular pathways have been explored in the saliva of Parkinson's disease patients:total tau,phosphorylated tau,amyloid-β1-42(pathological protein aggregation biomarkers);DJ-1,heme-oxygenase-l,metabolites(alte red energy homeostasis biomarkers);MAPLC-3beta(aberrant proteostasis biomarker);cortisol,tumor necrosis factor-alpha(inflammation biomarkers);DNA methylation,miRNA(DNA/RNA defects biomarkers);acetylcholinesterase activity(synaptic and neuronal network dysfunction biomarkers);Raman spectra,proteome,and caffeine.Despite a few studies investigating biomarkers to rgeting molecular pathways different from alpha-synuclein in Parkinson's disease,these results should be replicated and observed in studies on larger cohorts,considering the potential role of these biomarkers in determining the molecular variance among Parkinson's disease subtypes.Although the need fo r standardization in sample collection and processing,salivary-based biomarkers studies have reported encouraging results,calling for large-scale longitudinal studies and multicentric assessments,given the great molecular potentials and the non-invasive accessibility of saliva.

Roles of neuronal lysosomes in the etiology of Parkinson’s disease

Therapeutic progress in neurodegenerative conditions such as Parkinson’s disease has been hampered by a lack of detailed knowledge of its molecular etiology.The advancements in genetics and genomics have provided fundamental insights into specific protein players and the cellular processes involved in the onset of disease.In this respect,the autophagy-lysosome system has emerged in recent years as a strong point of convergence for genetics,genomics,and pathologic indications,spanning both familial and idiopathic Parkinson’s disease.Most,if not all,genes linked to familial disease are involved,in a regulatory capacity,in lysosome function(e.g.,LRRK2,alpha-synuclein,VPS35,Parkin,and PINK1).Moreover,the majority of genomic loci associated with increased risk of idiopathic Parkinson’s cluster in lysosome biology and regulation(GBA as the prime example).Lastly,neuropathologic evidence showed alterations in lysosome markers in autoptic material that,coupled to the alpha-synuclein proteinopathy that defines the disease,strongly indicate an alteration in functionality.In this Brief Review article,I present a personal perspective on the molecular and cellular involvement of lysosome biology in Parkinson’s pathogenesis,aiming at a larger vision on the events underlying the onset of the disease.The attempts at targeting autophagy for therapeutic purposes in Parkinson’s have been mostly aimed at“indiscriminately”enhancing its activity to promote the degradation and elimination of aggregate protein accumulations,such as alpha-synuclein Lewy bodies.However,this approach is based on the assumption that protein pathology is the root cause of disease,while pre-pathology and pre-degeneration dysfunctions have been largely observed in clinical and pre-clinical settings.In addition,it has been reported that unspecific boosting of autophagy can be detrimental.Thus,it is important to understand the mechanisms of specific autophagy forms and,even more,the adjustment of specific lysosome functionalities.Indeed,lysosomes exert fine signaling capacities in addition to their catabolic roles and might participate in the regulation of neuronal and glial cell functions.Here,I discuss hypotheses on these possible mechanisms,their links with etiologic and risk factors for Parkinson’s disease,and how they could be targeted for disease-modifying purposes.

Constipation,deficit in colon contractions and alpha-synuclein inclusions within the colon precede motor abnormalities and neurodegeneration in the central nervous system in a mouse model of alphasynucleinopathy

Background:Gastrointestinal dysfunction can affect Parkinson’s disease(PD)patients long before the onset of motor symptoms.However,little is known about the relationship between gastrointestinal abnormalities and the development of PD.Contrary to other animal models,the human A53T alpha-synuclein(αS)transgenic mice,Line G2–3,developsαS-driven neurological and motor impairments after 9 months of age,displaying a long presymptomatic phase free of central nervous system(CNS)dysfunction.Methods:To determine whether this line can be suitable to study constipation as it occurs in prodromal PD,gastrointestinal functionality was assessed in young mice through a multidisciplinary approach,based on behavioral and biochemical analysis combined with electrophysiological recordings of mouse intestinal preparations.Results:We found that the A53TαS mice display remarkable signs of gastrointestinal dysfunction that precede motor abnormalities andαS pathology in the CNS by at least 6 months.YoungαS mice show a drastic delay in food transit along the gastrointestinal tract,of almost 2 h in 3 months old mice that increased to more than 3 h at 6 months.Such impairment was associated with abnormal formation of stools that resulted in less abundant but longer pellets excreted,suggesting a deficit in the intestinal peristalsis.In agreement with this,electrically evoked contractions of the colon,but not of the ileum,showed a reduced motor response in both longitudinal and circular muscle layers inαS mice already at 3 months of age,that was mainly due to an impaired cholinergic transmission of the underlying enteric nervous system.Interestingly,the presence of insoluble and aggregatedαS was found in enteric neurons in both myenteric and submucosal plexi only in the colon of 3 months oldαS mice,but not in the small intestine,and exacerbated with age,mimicking the increase in transit delay and the contraction deficit showed by behavioral and electrical recordings data.Conclusions:Gastrointestinal dysfunction in A53TαS mice represents an early sign ofαS-driven pathology without concomitant CNS involvement.We believe that this model can be very useful to study disease-modifying strategies that could extend the prodromal phase of PD and haltαS pathology from reaching the brain.