The cell‐to‐cell transfer of α‐synuclein (α‐Syn) greatly contributes to Parkinson's disease (PD) pathogenesis and underlies the spread of α‐Syn pathology. During this process, extracellular α‐Syn can ...activate microglia and neuroinflammation, which plays an important role in PD. However, the effect of extracellular α‐Syn on microglia autophagy is poorly understood. In the present study, we reported that extracellular α‐Syn inhibited the autophagy initiation, as indicated by LC3‐II reduction and p62 protein elevation in BV2 and cultured primary microglia. The in vitro findings were verified in microglia‐enriched population isolated from α‐Syn‐overexpressing mice induced by adeno‐associated virus (AAV2/9)‐encoded wildtype human α‐Syn injection into the substantia nigra (SN). Mechanistically, α‐Syn led to microglial autophagic impairment through activating toll‐like receptor 4 (Tlr4) and its downstream p38 and Akt‐mTOR signaling because Tlr4 knockout and inhibition of p38, Akt as well as mTOR prevented α‐Syn‐induced autophagy inhibition. Moreover, inhibition of Akt reversed the mTOR activation but failed to affect p38 phosphorylation triggered by α‐Syn. Functionally, the in vivo evidence showed that lysozyme 2 Cre (Lyz2cre)‐mediated depletion of autophagy‐related gene 5 (Atg5) in microglia aggravated the neuroinflammation and dopaminergic neuron losses in the SN and exacerbated the locomotor deficit in α‐Syn‐overexpressing mice. Taken together, the results suggest that extracellular α‐Syn, via Tlr4‐dependent p38 and Akt‐mTOR signaling cascades, disrupts microglial autophagy activity which synergistically contributes to neuroinflammation and PD development.
Autophagy‐dependent and independent machinery synergistically contribute to hα‐Syn‐caused neuroinflammation in PD. The basal autophagy activity restricts microglia inflammation. Extracellular hα‐Syn interacts with and activates Tlr4, resulting in inflammatory responses, as well as autophagy suppression in microglia via Tlr4‐dependent p38 and Akt/mTOR signaling cascades. This impairs the inhibitory effect of autophagy on inflammation, and thus aggravating hα‐Syn‐induced inflammatory responses.
Microglia are the resident innate immune cells in the central nervous system (CNS) that serve as the first line innate immunity in response to pathogen invasion, ischemia and other pathological ...stimuli. Once activated, they rapidly release a variety of inflammatory cytokines and phagocytose pathogens or cell debris (termed neuroinflammation), which is beneficial for maintaining brain homeostasis if appropriately activated. However, excessive or uncontrolled neuroinflammation may damage neurons and exacerbate the pathologies in neurological disorders. Microglia are highly dynamic cells, dependent on energy supply from mitochondria. Moreover, dysfunctional mitochondria can serve as a signaling platform to facilitate innate immune responses in microglia. Mitophagy is a means of clearing damaged or redundant mitochondria, playing a critical role in the quality control of mitochondrial homeostasis and turnover. Mounting evidence has shown that mitophagy not only limits the inflammatory response in microglia but also affects their phagocytosis, whereas mitochondria dysfunction and mitophagy defects are associated with aging and neurological disorders. Therefore, targeting microglial mitophagy is a promising therapeutic strategy for neurological disorders. This article reviews and highlights the role and regulation of mitophagy in microglia in neurological conditions, and the research progress in manipulating microglial mitophagy and future directions in this field are also discussed.
Hydrogen sulfide (H2S) serves as a neuromodulator and regulator of neuroinflammation. It is reported to be therapeutic for Parkinson's disease (PD) animal and cellular models. However, whether it ...affects α-synuclein accumulation in dopaminergic cells, the key pathological feature in PD, is poorly understood. In this study we reported that exogenous H2S donors NaHS and GYY4137 (GYY) enhanced the autophagy activity, as indicated by the increases of autophagy marker LC3-II expression and LC3 dots formation even during lysosome inhibition in dopaminergic cell lines and HEK293 cells. The enhancement of H2S donors on autophagic flux was mediated by adenosine 5′-monophosphate-activated protein kinase (AMPK)-dependent mammalian target of rapamycin (mTOR) inhibition, as H2S donors activated AMPK but reduced the mTOR activity and H2S donors-induced LC3-II increase was diminished by mTOR activator. Moreover, point mutation of Cys302 into alanine (C302A) in AMPKα2 subunit abolished the AMPK activation and mTOR inhibition, as well as autophagic flux increase elicited by NaHS. Interestingly, NaHS triggered AMPK S-sulfuration, which was not observed in AMPK C302A-transfected cells. Further, NaHS was able to attenuate α-synuclein accumulation in a cellular model induced by dopamine oxidized metabolite 3, 4-dihydroxyphenylacetaldehyde (DOPAL), and this effect was interfered by autophagy inhibitor wortmannin and also eliminated in AMPK Cys302A-transfected cells. In sum, the findings identified a role of Cys302 S-sulfuration in AMPK activation induced by exogenous H2S and demonstrated that H2S donors could enhance the autophagic flux via AMPK-mTOR signaling and thus reduce α-synuclein accumulation in vitro.
•H2S enhanced the autophagic flux in dopaminergic cells.•AMPK-mTOR signaling mediated the effect of H2S on autophagy.•H2S triggered AMPK S-sulfuration at Cys302.•AMPK S-sulfuration contributed to H2S-induced autophagy activation.•H2S donor attenuated α-syn aggregation in vitro by activating AMPK-dependent autophagy.
Serum urate levels are reported to be significantly lowered in patients with Parkinson's disease (PD) and inversely correlated to the risk and progression of PD. However, the mechanism by which urate ...affects PD is poorly understood. Here we showed that treatment with uric acid (UA) resulted in an autophagy activity enhancement in PC12 cells in dose- and time-dependent manners, as indicated by LC3-II increase and P62 decrease. Moreover, UA was still able to increase the LC3-II level and the number of LC3 puncta in the presence of Bafilomycin A1, a lysosomal inhibitor. These changes of autophagic markers were preceded by mTOR inhibition and ULK1 activation. Co-treatment with 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO), an mTOR activator, abolished the UA-induced LC3-II increase. More importantly, UA reduced SNCA/α-synuclein accumulation in PC12 cells that overexpress wildtype or A53T mutant SNCA, and this was blocked by Bafilomycin A1 co-treatment. The in vivo study showed that UA administration was able to modulate the levels of autophagy markers, increase the autophagosome/autolysosome formation, and reduce SNCA accumulation in the midbrain of SNCAA53T transgenic mice. Taken together, our findings suggest that UA could induce autophagy activation via an mTOR-dependent signaling and ameliorate SNCA accumulation. This implicates that urate-elevating agent may become a potential strategy for PD therapy.
•Uric acid enhances macroautophagy activity in dopaminergic cells.•Uric acid induces autophagy activation dependent on mTOR inhibition.•Uric acid promotes α-synuclein degradation via the autophagy-lysosome pathway.•Uric acid treatment reduces α-synuclein accumulation in SNCAA53T transgenic mice.
The molecular mechanisms for the discrepancy in outcome of initiating estrogen therapy (ET) around peri-menopause or several years after menopause in women are unknown. We hypothesize that the level ...of expression of a dominant negative estrogen receptor (ER) β variant, ERβ2, may be a key factor determining the effectiveness of ET in post-menopausal women. We tested this hypothesis in ovariectomized nine month-old (an age when irregular estrous cycles occur) female Sprague Dawley rats. Estradiol treatment was initiated either 6 days (Early ET, analogous to 4 months post-menopause in humans), or 180 days (Late ET, analogous to 11 years post-menopause in humans) after ovariectomy. Although ERβ2 expression increased in all OVX rats, neurogenic and neuroprotective responses to estradiol differed in Early and Late ET. Early ET reduced ERβ2 expression in both hippocampus and white blood cells, increased the hippocampal cell proliferation as assessed by Ki-67 expression, and improved mobility in the forced swim test. Late ET resulted in either no or modest effects on these parameters. There was a close correlation between the degree of ERβ2 expression and the preservation of neural effects by ET after OVX in rats, supporting the hypothesis that persistent elevated levels of ERβ2 are a molecular basis for the diminished effectiveness of ET in late post-menopausal women. The correlation between the expression of ERβ2 in circulating white blood cells and brain cells suggests that ERβ2 expression in peripheral blood cells may be an easily accessible marker to predict the effective window for ET in the brain.
Aim： Parkin has been shown to exert protective effects against 6-hydroxydopamine （6-OHDA）-induced neurotoxicity in different models of Parkinson disease. In the present study we investigated the ...molecular mechanisms underlying the neuroprotective action of parkin in vitro. Methods. HEK293, HeLa and PC12 cells were transfected with parkin, parkin mutants, p62 or si-p62. Protein expression and ubiquitination were assessed using immunoblot analysis. Immunoprecipitation assay was performed to identify the interaction between parkin and scaffold protein p62. PC12 and SH-SY5Y cells were treated with 6-OHDA （200 pmol/L）, and cell apoptosis was detected using PI and Hoechst staining. Results： In HEK293 cells co-transfected with parkin and p62, parkin was co-immunoprecipitated with p62, and parkin overexpression increased p62 protein levels. In parkin-deficient HeLa cells, transfection with wild-type pakin, but not with ligase activity-deficient pakin mutants, significantly increased p62 levels, suggesting that parkin stabilized p62 through its E3 ligase activity. Transfection with parkin or p62 significantly repressed ERK1/2 phosphorylation in HeLa cells, but transfection with parkin did not repress ERK1/2 phosphorylation in p62-knockdown HeLa cells, suggesting that p62 was involved in parkin-induced inhibition on ERK1/2 phosphorylation. Overexpression of parkin or p62 significantly repressed 6-OHDA-induced ERK1/2 phosphorylation in PC12 cells, and parkin overexpression inhibited 6-OHDA-induced apoptosis in PC12 and SH-SY5Y cells. Conclusion： Parkin protects PC12 cells against 6-OHDA-induced apoptosis via ubiquitinating and stabilizing scaffold protein p62, and repressing ERK1/2 activation.
Cigarette smoking is irrefutably the strongest risk factor for lung cancer; however, approximately 25% of cases worldwide occur among nonsmokers. The age-adjusted annual incidence rate of lung cancer ...in Shanghai, a region where relatively few women smoke cigarettes, is one of the highest in the world. To help further elucidate the etiology of lung cancer among nonsmokers, the authors examined hormonal factors among women who were lifetime nonsmokers. They analyzed data from the prospective Shanghai Women's Health Study, which recruited Chinese women aged 40–70 years between 1996 and 2000 from selected urban communities. The current analysis included 71,314 women (n = 220 cases) who were lifetime nonsmokers and had no history of cancer at baseline. Later age at menopause (≥51 vs. <46 years; hazard ratio (HR) = 0.63, 95% confidence interval (CI): 0.40, 1.00), longer reproductive period (≥36 vs. <31 years; HR = 0.60, 95% CI: 0.39, 0.93), higher parity (≥4 vs. 0 children; HR = 0.42, 95% CI: 0.19, 0.90), and intrauterine device use (HR = 0.59, 95% CI: 0.41, 0.86) were associated with decreased risks of lung cancer. This large prospective study suggests a potential role for hormonal factors in the etiology of lung cancer among nonsmoking women.
Background
Human leukocyte antigen (HLA) genes play critical roles in immune surveillance, an important defence against tumors. Imputing HLA genotypes from existing single-nucleotide polymorphism ...datasets is low-cost and efficient. We investigate the relevance of the major histocompatibility complex region in breast cancer susceptibility, using imputed class I and II HLA alleles, in 25,484 women of Asian ancestry.
Methods
A total of 12,901 breast cancer cases and 12,583 controls from 12 case–control studies were included in our pooled analysis. HLA imputation was performed using SNP2HLA on 10,886 quality-controlled variants within the 15–55 Mb region on chromosome 6. HLA alleles (
n
= 175) with info scores greater than 0.8 and frequencies greater than 0.01 were included (resolution at two-digit level: 71; four-digit level: 104). We studied the associations between HLA alleles and breast cancer risk using logistic regression, adjusting for population structure and age. Associations between HLA alleles and the risk of subtypes of breast cancer (ER-positive, ER-negative, HER2-positive, HER2-negative, early-stage, and late-stage) were examined.
Results
We did not observe associations between any HLA allele and breast cancer risk at
P
< 5e−8; the smallest p value was observed for HLA-C*12:03 (OR = 1.29,
P
= 1.08e−3). Ninety-five percent of the effect sizes (OR) observed were between 0.90 and 1.23. Similar results were observed when different subtypes of breast cancer were studied (95% of ORs were between 0.85 and 1.18).
Conclusions
No imputed HLA allele was associated with breast cancer risk in our large Asian study. Direct measurement of HLA gene expressions may be required to further explore the associations between HLA genes and breast cancer risk.
Purpose Gallstone disease is more common among overweight individuals, particularly in women. We conducted a cross-sectional case-control study of Chinese women nested in the Shanghai Women's Health ...Study (SWHS) to evaluate the association of gallstone disease with body mass index (BMI), waist to hip ratio (WHR), and physical activity (PA). Methods The study included 8,485 women with self-reported, physician-diagnosed, prevalent gallstone disease and 16,970 frequency-matched controls by birth year and age at gallstone diagnosis (4-year intervals). Information on height, weight history, waist and hip circumferences, physical activities, and other exposures was obtained by in-person interview. Results : Usual BMI ( p trend < 0.001) and WHR ( p trend < 0.001) were both related to a high prevalence of gallstone disease, and a significant interaction between BMI and WHR on gallstone risk was found (odds ratio OR = 3.82, 95%CI 95% confidence interval 2.47–5.23 for those with both highest BMI and WHR relative to those with lowest BMI and WHR, p interaction = 0.03). Gallstone risk was positively associated with cumulative occupational sitting time ( p trend = 0.01) and inversely associated with occupational cumulative energy expenditure ( p trend = 0.03) as well as with household PA ( p trend = 0.02). Conclusions Our findings further support that overall and central excessive adiposity is an independent risk factor for gallstones in women. In addition, regardless of adiposity level, being physically active may ameliorate the risk of this disease.
The mode of action of 2-(7-fluoro-3-oxo-3,4-dihydro-2H-benzob1,4oxazin-6-yl)-4,5,6,7-tetrahydro-2H-isoindoline-1,3-diones, including the commercial herbicide flumioxazin, had been identified as ...inhibition of protoporphyrinogen oxidase (protox). As part of continuous efforts to search for new herbicides with high efficacy, broad-spectrum activity, and safety to crops, flumioxazin and its iodo analogue (B2055) were used as lead compounds for further optimization. Series of novel compounds were prepared by multistep synthetic procedures starting from 5-fluoro-2-nitrophenol. All of the test compounds were structurally confirmed by 1H NMR, IR, mass spectroscopy, and elemental analysis. Preliminary bioassay data showed that some of them possess commercial levels of herbicidal activity comparable to those of other protox-inhibiting herbicides. One of the best compounds, 5-fluoro-2-(7-fluoro-3-oxo-4-(prop-2-ynyl)-3,4-dihydro-2H-benzob1,4oxazin-6-yl)isoindoline-1,3-dione (8e), has IC50 values for velvetleaf (Abutilon theophrasti Medic) and crabgrass (Digitaria sanguinalis) comparable to thos of B2055. With respect to crop selectivity, compound 8e is similar to flumioxazin. Compound 8e is safe to cotton and maize at a rate of 150 g of active ingredient (ai)/ha or less when applied at pre-emergent stage, and it has the best safety to wheat among the tested crops, showing no injury after post-emergent application at 7.5−30 g of ai/ha. Keywords: Benzob1,4oxazin-6-yl-isoindoline-1,3-dione; protox inhibitor; synthesis; herbicidal activity; Digitaria sanguinalis; Abutilon theophrasti Medic
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