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.     

Necrostatin-1 protection of dopaminergic neurons

Necroptosis is characterized by programmed necrotic cell death and autophagic activation and might be involved in the death process of dopaminergic neurons in Parkinson's disease. We hypothesized that necrostatin-1 could block necroptosis and give protection to dopaminergic neurons. There is likely to be crosstalk between necroptosis and other cell death pathways, such as apoptosis and autophagy. PC12 cells were pretreated with necroststin-1 1 hour before exposure to 6-hydroxydopamine. We examined cell viability, mitochondrial membrane potential and expression patterns of apoptotic and necroptotic death signaling proteins. The results showed that the autophagy/lysosomal pathway is involved in the 6-hydroxydopamine-induced death process of PC12 cells. Mitochondrial disability induced overactive autophagy, increased cathepsin B expression, and diminished Bcl-2 expression. Necrostatin-1 within a certain concentration range(5–30 μM) elevated the viability of PC12 cells, stabilized mitochondrial membrane potential, inhibited excessive autophagy, reduced the expression of LC3-II and cathepsin B, and increased Bcl-2 expression. These findings suggest that necrostatin-1 exerted a protective effect against injury on dopaminergic neurons. Necrostatin-1 interacts with the apoptosis signaling pathway during this process. This pathway could be a new neuroprotective and therapeutic target in Parkinson's disease.     

A possible therapeutic potential of quercetin through inhibition of μ-calpain in hypoxia induced neuronal injury:a molecular dynamics simulation study

The neuroprotective property of quercetin is well reported against hypoxia and ischemia in past studies.This property of quercetin lies in its antioxidant property with blood-brain barrier permeability and anti-inflammatory capabilities.μ-Calpain,a calcium ion activated intracellular cysteine protease causes serious cellular insult,leading to cell death in various pathological conditions including hypoxia and ischemic stroke.Hence,it may be considered as a potential drug target for the treatment of hypoxia induced neuronal injury.As the inhibitory property of μ-calpain is yet to be explored in details,hence,in the present study,we investigated the interaction of quercetin with μ-calpain through a molecular dynamics simulation study as a tool through clarifying the molecular mechanism of such inhibition and determining the probable sites and modes of quercetin interaction with the μ-calpain catalytic domain.In addition,we also investigated the structure-activity relationship of quercetin with μ-calpain.Affinity binding of quercetin with μ-calpain had a value of –28.73 k J/mol and a Ki value of 35.87 μM that may be a probable reason to lead to altered functioning of μ-calpain.Hence,quercetin was found to be an inhibitor of μ-calpain which might have a possible therapeutic role in hypoxic injury.     

The E3 ubiquitin ligase seven in absentia homolog 1 may be a potential new therapeutic target for Parkinson's disease

In this study, we investigated the effect of an antibody against E3 ubiquitin ligase seven in absentia homolog 1(SIAH-1) in PC12 cells. 1-Methyl-4-phenylpyridinium(MPP+) treatment increased α-synuclein, E1 and SIAH-1 protein levels in PC12 cells, and it reduced cell viability; however, there was no significant change in light chain 3 expression. Treatment with an SIAH-1 antibody decreased m RNA expression levels of α-synuclein, light chain 3 and SIAH-1, but increased E1 m RNA expression. It also increased cell viability. Combined treatment with MPP+ and rapamycin reduced SIAH-1 and α-synuclein levels. Treatment with SIAH-1 antibody alone diminished α-synuclein immunoreactivity in PC12 cells, and reduced the colocalization of α-synuclein and light chain 3. These findings suggest that the SIAH-1 antibody reduces the monoubiquitination and aggregation of α-synuclein, promoting its degradation by the ubiquitin-proteasome pathway. Consequently, SIAH-1 may be a potential new therapeutic target for Parkinson's disease.     

Neuroprotective effects of genistein on SH-SY5Y cells overexpressing A53T mutant α-synuclein

Genistein, a potent antioxidant compound, protects dopaminergic neurons in a mouse model of Parkinson's disease. However, the mechanism underlying this action remains unknown. This study investigated human SH-SY5Y cells overexpressing the A53T mutant of α-synuclein. Four groups of cells were assayed: a control group(without any treatment), a genistein group(incubated with 20 μM genistein), a rotenone group(treated with 50 μM rotenone), and a rotenone + genistein group(incubated with 20 μM genistein and then treated with 50 μM rotenone). A lactate dehydrogenase release test confirmed the protective effect of genistein, and genistein remarkably reversed mitochondrial oxidative injury caused by rotenone. Western blot assays showed that BCL-2 and Beclin 1 levels were markedly higher in the genistein group than in the rotenone group. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling revealed that genistein inhibited rotenone-induced apoptosis in SH-SY5 Y cells. Compared with the control group, the expression of NFE2L2 and HMOX1 was significantly increased in the genistein + rotenone group. However, after treatment with estrogen receptor and NFE2L2 channel blockers(ICI-182780 and ML385, respectively), genistein could not elevate NFE2L2 and HMOX1 expression. ICI-182780 effectively prevented genistein-mediated phosphorylation of NFE2L2 and remarkably suppressed phosphorylation of AKT, a protein downstream of the estrogen receptor. These findings confirm that genistein has neuroprotective effects in a cell model of Parkinson's disease. Genistein can reduce oxidative stress damage and cell apoptosis by activating estrogen receptors and NFE2L2 channels.     

Apelin-13 inhibits apoptosis and excessive autophagy in cerebral ischemia/reperfusion injury

Apelin-13 is a novel endogenous ligand for an angiotensin-like orphan G-protein coupled receptor, and it may be neuroprotective against cerebral ischemia injury. However, the precise mechanisms of the effects of apelin-13 remain to be elucidated. To investigate the effects of apelin-13 on apoptosis and autophagy in models of cerebral ischemia/reperfusion injury, a rat model was established by middle cerebral artery occlusion. Apelin-13(50 μg/kg) was injected into the right ventricle as a treatment. In addition, an SH-SY5 Y cell model was established by oxygen-glucose deprivation/reperfusion, with cells first cultured in sugar-free medium with 95% N2 and 5% CO2 for 4 hours and then cultured in a normal environment with sugar-containing medium for 5 hours. This SH-SY5 Y cell model was treated with 10–7 M apelin-13 for 5 hours. Results showed that apelin-13 protected against cerebral ischemia/reperfusion injury. Apelin-13 treatment alleviated neuronal apoptosis by increasing the ratio of Bcl-2/Bax and significantly decreasing cleaved caspase-3 expression. In addition, apelin-13 significantly inhibited excessive autophagy by regulating the expression of LC3 B, p62, and Beclin1. Furthermore, the expression of Bcl-2 and the phosphatidylinositol-3-kinase(PI3 K)/Akt/mammalian target of rapamycin(mTOR) pathway was markedly increased. Both LY294002(20 μM) and rapamycin(500 nM), which are inhibitors of the PI3 K/Akt/mTOR pathway, significantly attenuated the inhibition of autophagy and apoptosis caused by apelin-13. In conclusion, the findings of the present study suggest that Bcl-2 upregulation and mTOR signaling pathway activation lead to the inhibition of apoptosis and excessive autophagy. These effects are involved in apelin-13-induced neuroprotection against cerebral ischemia/reperfusion injury, both in vivo and in vitro. The study was approved by the Animal Ethical and Welfare Committee of Jining Medical University, China(approval No. 2018-JS-001) in February 2018.     

Protective effect of alpha-synuclein knockdown on methamphetamine-induced neurotoxicity in dopaminergic neurons

The over-expression of α-synuclein is a major factor in the death of dopaminergic neurons in a methamphetamine-induced model of Parkinson's disease. In the present study, α-synuclein knockdown rats were created by injecting α-synuclein-shRNA lentivirus stereotaxically into the right striatum of experimental rats. At 2 weeks post-injection, the rats were injected intraper-itoneally with methamphetamine to establish the model of Parkinson's disease. Expression of α-synuclein mRNA and protein in the right striatum of the injected rats was significantly down-regulated. Food intake and body weight were greater in α-synuclein knockdown rats, and water intake and stereotyped behavior score were lower than in model rats. Striatal dopamine and tyrosine hydroxylase levels were significantly elevated in α-synuclein knockdown rats. Moreover, superoxide dismutase activity was greater in α-synuclein knockdown rat striatum, but the levels of reactive oxygen species, malondialdehyde, nitric oxide synthase and nitrogen monoxide were lower compared with model rats. We also found that α-synuclein knockdown inhibited metham-phetamine-induced neuronal apoptosis. These results suggest that α-synuclein has the capacity to reverse methamphetamine-induced apoptosis of dopaminergic neurons in the rat striatum by inhibiting oxidative stress and improving dopaminergic system function.     

Methylprednisolone exerts neuroprotective effects by regulating autophagy and apoptosis

Methylprednisolone markedly reduces autophagy and apoptosis after secondary spinal cord injury. Here, we investigated whether pretreatment of cells with methylprednisolone would protect neuron-like cells from subsequent oxidative damage via suppression of autophagy and apoptosis. Cultured N_2 a cells were pretreated with 10 μM methylprednisolone for 30 minutes, then exposed to 100 μM H_2O_2 for 24 hours. Inverted phase contrast microscope images, MTT assay, flow cytometry and western blot results showed that, compared to cells exposed to 100 μM H_2O_2 alone, cells pretreated with methylprednisolone had a significantly lower percentage of apoptotic cells, maintained a healthy morphology, and showed downregulation of autophagic protein light chain 3B and Beclin-1 protein expression. These findings indicate that methylprednisolone exerted neuroprotective effects against oxidative damage by suppressing autophagy and apoptosis.     

Angiotensin-(1–7)reducesα-synuclein aggregation by enhancing autophagic activity in Parkinson's disease

Abnormal accumulation ofα-synuclein contributes to the formation of Lewy bodies in the substantia nigra,which is considered the typical pathological hallmark of Parkinson's disease.Recent research indicates that angiotensin-(1-7)plays a crucial role in several neurodegenerative disorders,including Parkinson's disease,but the underlying mechanisms remain elusive.In this study,we used intraperitoneal administration of rotenone to male Sprague-Dawley rats for 4 weeks to establish a Parkinson's disease model.We investigated whether angiotensin-(1-7)is neuroprotective in this model by continuous administration of angiotensin-(1-7)into the right substantia nigra for 4 weeks.We found that angiotensin-(1-7)infusion relieved characteristic parkinsonian behaviors and reducedα-synuclein aggregation in the substantia nigra.Primary dopaminergic neurons were extracted from newborn Sprague-Dawley rat substantia nigras and treated with rotenone,angiotensin-(1-7),and/or the Mas receptor blocker A-779 for 24 hours.After binding to the Mas receptor,angiotensin-(1-7)attenuated apoptosis andα-synuclein aggregation in rotenone-treated cells.Primary dopaminergic neurons were also treated with angiotensin-(1-7)and/or the autophagy inhibitor 3-methyladenine for 24 hours.Angiotensin-(1-7)increasedα-synuclein removal and increased the autophagy of rotenone-treated cells.We conclude that angiotensin-(1-7)reducesα-synuclein aggregation by alleviating autophagy dysfunction in Parkinson's disease.Therefore,the angiotensin-(1-7)/Mas receptor axis plays an important role in the pathogenesis of Parkinson's disease and angiotensin-(1-7)has potential therapeutic value for Parkinson's disease.All experiments were approved by the Biological Research Ethics Committee of Nanjing First Hospital(approval No.DWSY-2000932)in January 2020.     

Effect of moxibustion on mTOR-mediated autophagy in rotenone-induced Parkinson's disease model rats

Defects in autophagy-mediated clearance of α-synuclein may be one of the key factors leading to progressive loss of dopaminergic neurons in the substantia nigra. Moxibustion therapy for Parkinson's disease has been shown to have a positive effect, but the underlying mechanism remains unknown. Based on this, we explored whether moxibustion could protect dopaminergic neurons by promoting autophagy mediated by mammalian target of rapamycin(m TOR), with subsequent elimination of α-syn. A Parkinson's disease model was induced in rats by subcutaneous injection of rotenone at the back of their necks, and they received moxibustion at Zusanli(ST36), Guanyuan(CV4) and Fengfu(GV16), for 10 minutes at every point, once per day, for 14 consecutive days. Model rats without any treatment were used as a sham control. Compared with the Parkinson's disease group, the moxibustion group showed significantly greater tyrosine hydroxylase immunoreactivity and expression of light chain 3-Ⅱ protein in the substantia nigra, and their behavioral score, α-synuclein immunoreactivity, the expression of phosphorylated m TOR and phosphorylated ribosomal protein S6 kinase(p-p70S6K) in the substantia nigra were significantly lower. These results suggest that moxibustion can promote the autophagic clearance of α-syn and improve behavioral performance in Parkinson's disease model rats. The protective mechanism may be associated with suppression of the m TOR/p70S6K pathway.     

Schwann cells differentiated from skin-derived precursors provide neuroprotection via autophagy inhibition in a cellular model of Parkinson’s disease

Autophagy has been shown to play an important role in Parkinson’s disease.We hypothesized that skin-derived precursor cells exhibit neuroprotective effects in Parkinson’s disease through affecting autophagy.In this study,6-hydroxydopamine-damaged SH-SY5Y cells were pretreated with a culture medium containing skin-derived precursors differentiated into Schwann cells(SKP-SCs).The results showed that the SKP-SC culture medium remarkably enhanced the activity of SH-SY5Y cells damaged by 6-hydroxydopamine,reduced excessive autophagy,increased tyrosine hydroxylase expression,reducedα-synuclein expression,reduced the autophagosome number,and activated the PI3K/AKT/mTOR pathway.Autophagy activator rapamycin inhibited the effects of SKP-SCs,and autophagy inhibitor 3-methyladenine had the opposite effect.These findings confirm that SKP-SCs modulate the PI3K/AKT/mTOR pathway to inhibit autophagy,thereby exhibiting a neuroprotective effect in a cellular model of Parkinson’s disease.This study was approved by the Animal Ethics Committee of Laboratory Animal Center of Nantong University(approval No.S20181009-205)on October 9,2018.     

Targeting the noradrenergic system for anti-inflammatory and neuroprotective effects: implications for Parkinson's disease

Degeneration of the locus coeruleus noradrenergic system is thought to play a key role in the pathogenesis of Parkinson's disease(PD), whereas pharmacological approaches to increase noradrenaline bioavailability may provide neuroprotection. Noradrenaline inhibits microglial activation and suppresses pro-inflammatory mediator production(e.g., tumor necrosis factor-α, interleukin-1β inducible nitric oxide synthase activity), thus limiting the cytotoxicity of midbrain dopaminergic neurons in response to an inflammatory stimulus. Neighbouring astrocyte populations promote a neurotrophic environment in response to β_2-adrenoceptor(β_2-AR) stimulation via the production of growth factors(e.g., brain derived neurotrophic factor, cerebral dopamine neurotrophic factor glial cell derived neurotrophic factor which have shown promising neuroprotective and neuro-restorative effects in the nigrostriatal dopaminergic system. More recent findings have demonstrated a role for the β_2-AR in down-regulating expression levels of the human α-synuclein gene SNCA and relative α-synuclein protein abundance. Given that α-synuclein is a major protein constituent of Lewy body pathology, a hallmark neuropathological feature in Parkinson's disease, these findings could open up new avenues for pharmacological intervention strategies aimed at alleviating the burden of α-synucleinopathies in the Parkinsonian brain. In essence, the literature reviewed herein supports our hypothesis of a tripartite neuroprotective role for noradrenaline in combating PD-related neuropathology and motor dysfunction via(1) inhibiting nigral microglial activation pro-inflammatory mediator production,(2) promoting the synthesis of neurotrophic factors from midbrain astrocytes and(3) downregulating α-synuclein gene expression and protein abundance in a β_2-AR-dependent manner. Thus, taken together, either pharmacologically enhancing extra-synaptic noradrenaline bioavailability or targeting glial β_2-ARs directly makes itself as a promising treatment option aimed at slowing/halting PD progression.     

PC12细胞突变型a-突触核蛋白与自噬性降解途径

Several studies have demonstrated that overexpression of mutant α-synuclein in PC12 cells is related to occurrence of autophagy.The present study established mutant α-synuclein(A30P)-transfected PC12 cells and treated them with the autophagy inducer rapamycin and autophagy inhibitor wortmannin,respectively.Results demonstrated that mutantα-synuclein resulted in cell death via autophagy and involved α-synuclein accumulation,membrane lipid oxidation,and loss of plasma membrane integrity.Mutant α-synuclein(A30P)also mediated toxicity of 1-methyl-4-phenylpyridinium ion.Moreover,rapamycin inhibited α-synuclein aggregation,while wortmannin promoted α-synuclein aggregation and cell death.To further determine the role of autophagy due to mutant α-synuclein,the present study measured expression of microtubule-associated protein light chain 3.Results revealed that wortmannin and 1-methyl-4-phenylpyridinium ion inhibited expression of microtubule-associated protein light chain 3,while rapamycin promoted its expression.These findings suggested that abnormal aggregation of α-synuclein induced autophagic programmed cell death in PC12 cells.     

Mitochondrial division inhibitor 1 protects cortical neurons from excitotoxicity:a mechanistic pathway

Mitochondrial division inhibitor 1(Mdivi-1) is a selective cell-permeable inhibitor of dynamin-related protein-1(Drp1) and mitochondrial division.To investigate the effect of Mdivi-1 on cells treated with glutamate,cerebral cortex neurons isolated from neonatal rats were treated with 10 m M glutamate for 24 hours.Normal cultured cells and dimethyl sulfoxide-cultured cells were considered as controls.Apoptotic cells were detected by flow cytometry.Changes in mitochondrial morphology were examined by electron microscopy.Drp1,Bax,and casp ase-3 expression was evaluated by western blot assays and immunocytochemistry.Mitochondrial membrane potential was detected using the JC-1 probe.Twenty-four hours after 10 m M glutamate treatment,Drp1,Bax and caspase-3 expression was upregulated,Drp1 and Bax were translocated to mitochondria,mitochondrial membrane potential was decreased and the rate of apoptosis was increased.These effects were inhibited by treatment with 50 μM Mdivi-1 for 2 hours.This finding indicates that Mdivi-1 is a candidate neuroprotective drug that can potentially mitigate against neuronal injury caused by glutamate-induced excitotoxicity.     

1-methyl-4-phenylpyridinium ion induced autophagic stress and caused autophagic clearance impairment of α-synuclein in pheochromocytoma cells

Objective To investigate the role of autophagie stress induced by 1-methyl-4-phenylpyridinium (MPP+) in pheochromocytoma (PC12) cell injury,and the mechanism of autophagic clearance impairment and abnormal aggregation of α-synuelein.Methods Before and after treatment of MPP+,the viability was measured through the MTT assay,and the expression of α-synuclein and microtubule-associated protein light chsin 3-Ⅱ(LC3.Ⅱ)in the level of protein was detected through Western blot.In addition,MDC staining and immunofluorescence microscopy were performed to observe the alterations of autophagy and the signals for α-synuelein,LC3-Ⅱ,lysosomal-associated membrane protein 1(LAMP-1)and their co-localization in PC12 and A30P cells.Results After treatment of MPP+ for 24 h,cell viability decreased in PC12 + MPP+ group and A30P + MPP+ group.Theincrease in α-synuelein was significant in the level of protein in PC12 + MPP+ group (0.66±0.07,t=5.7271,P＝0.0023) and A30P + MPP+ group(1.71±0.40,t=8.6100,P=0.0005),especially in A30P + MPP+ group,compared with the untreated groups (PC12 group:0.20±0.08;A30P:O.76±0.09).In MPP+ -treated groups,LC3-Ⅱ protein and the average number of late autophagic vacuoles per cell increased compared with untreated ones.Besides,the signals for LC3-Ⅱ and α-synuclein and the extent of their co-localization increased in MPP+ -treated groups.Though the signals for LAMP-1 that labeles lysosome increased,the extent of co-localization between LAMP-1 and LC3-Ⅱ was reduced after treated with MPP+ for 24 h.Conclusions MPP+impaires the fusion of autophagosomes and lysosomes,leading to the autophagicclearance impairment of α-synuclein and autophagic stress,and finally causes the cell damage even death.     

Neuroprotective effects of rapamycin on spinal cord injury in rats by increasing autophagy and Akt signaling

Rapamycin treatment has been shown to increase autophagy activity and activate Akt phosphorylation, suppressing apoptosis in several models of ischemia reperfusion injury. However, little has been studied on the neuroprotective effects on spinal cord injury by activating Akt phosphorylation. We hypothesized that both effects of rapamycin, the increased autophagy activity and Akt signaling, would contribute to its neuroprotective properties. In this study, a compressive spinal cord injury model of rat was created by an aneurysm clip with a 30 g closing force. Rat models were intraperitoneally injected with rapamycin 1 mg/kg, followed by autophagy inhibitor 3-methyladenine 2.5 mg/kg and Akt inhibitor IV 1 μg/kg. Western blot assay, immunofluorescence staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay were used to observe the expression of neuronal autophagy molecule Beclin 1, apoptosis-related molecules Bcl-2, Bax, cytochrome c, casp ase-3 and Akt signaling. Our results demonstrated that rapamycin inhibited the expression of mTOR in injured spinal cord tissue and up-regulated the expression of Beclin 1 and phosphorylated-Akt. Rapamycin prevented the decrease of bcl-2 expression in injured spinal cord tissue, reduced Bax, cytochrome c and caspase-3 expression levels and reduced the number of apoptotic neurons in injured spinal cord tissue 24 hours after spinal cord injury. 3-Methyladenine and Akt inhibitor IV intervention suppressed the expression of Beclin-1 and phosphorylated-Akt in injured spinal cord tissue and reduced the protective effect of rapamycin on apoptotic neurons. The above results indicate that the neuroprotective effect of rapamycin on spinal cord injury rats can be achieved by activating autophagy and the Akt signaling pathway.     

Effect of rifampicin pre- and post-treatment on rotenone-induced dopaminergic neuronal apoptosis and alpha-synuclein expression

BACKGROUND: Rifampicin inhibits the formation of α-synuclein multimer and protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyritine (MPTP)-induced PC12 cell apoptosis.OBJECTIVE: To compare the effect of rifampicin pre-and post-treatment on tyrosine hydroxylase and α-synuclein expression in substantia nigra pars compacta in a rat model of Parkinson’s disease.DESIGN,TIME AND SETTING: A randomized,controlled experiment was performed at the Experimental Animal Center of Sun Yat-sen University North Campus (...     

Quercetin protects against diabetic retinopathy in rats by inducing heme oxygenase-1 expression

Quercetin is a widely-occurring flavonoid that protects against cancer, and improves memory and cardiovascular functions.However, whether quercetin exhibits therapeutic effects in diabetic retinopathy remains unclear.In this study, we established a rat model of streptozocininduced diabetic retinopathy.Seventy-two hours later, the rats were intraperitoneally administered 150 mg/kg quercetin for 16 successive weeks.Quercetin markedly increased the thickness of the retinal cell layer, increased the number of ganglion cells, and decreased the overexpression of the pro-inflammatory factors interleukin-1β, interleukin-18, interleukin-6 and tumor necrosis factor-α in the retinal tissue as well as the overexpression of high mobility group box-1 and the overactivation of the NLRP3 inflammasome.Furthermore, quercetin inhibited the overexpression of TLR4 and NF-κBp65, reduced the expression of the pro-angiogenic vascular endothelial growth factor and soluble intercellular adhesion molecule-1, and upregulated the neurotrophins brain-derived neurotrophic factor and nerve growth factor.Intraperitoneal injection of the heme oxygenase-1 inhibitor zinc protoporphyrin blocked the protective effect of quercetin.These findings suggest that quercetin exerts therapeutic effects in diabetic retinopathy possibly by inducing heme oxygenase-1 expression.This study was approved by the Animal Ethics Committee of China Medical University, China(approval No.2016 PS229K) on April 8, 2016.     

One ring is sufficient to inhibit α-synuclein aggregation

Parkinson's disease,the second most prevalent neurodegenerative disorder worldwide,is characterized by a progressive loss of dopaminergic neurons in substantia nigra pars compacta,causing motor symptoms.This disorder's main hallmark is the formation of intraneuronal protein inclusions,named Lewy bodies and neurites.The major component of these arrangements is α-synuclein,an intrinsically disordered and soluble protein that,in pathological conditions,can form toxic and cell-to-cell transmissible amyloid structures.Preventing α-synuclein aggregation has attracted significant effort in the search for a disease-modifying therapy for Parkinson's disease.Small molecules like Synu Clean-D,epigallocatechin gallate,trodusquemine,or anle138 b exemplify this therapeutic potential.Here,we describe a subset of compounds containing a single aromatic ring,like dopamine,ZPDm,gallic acid,or entacapone,which act as molecular chaperones against α-synuclein aggregation.The simplicity of their structures contrasts with the complexity of the aggregation process,yet the block efficiently α-synuclein assembly into amyloid fibrils,in many cases,redirecting the reaction towards the formation of non-toxic off-pathway oligomers.Moreover,some of these compounds can disentangle mature α-synuclein amyloid fibrils.Their simple structures allow structure-activity relationship analysis to elucidate the role of different functional groups in the inhibition of α-synuclein aggregation and fibril dismantling,making them informative lead scaffolds for the rational development of efficient drugs.