代谢改造重组谷氨酸棒杆菌C4途径高效合成5-氨基乙酰丙酸

5-氨基乙酰丙酸(5-aminolevulinic acid,5-ALA)在医药和农业等领域有着广泛作用,目前主要采用大肠杆菌或谷氨酸棒杆菌以微生物发酵法合成.为了进一步提高谷氨酸棒杆菌合成5-ALA的能力,对其C4代谢途径进行了系统代谢改造.首先分别在谷氨酸棒杆菌中异源表达荚膜红杆菌和沼泽红假单胞菌的5-氨基乙酰丙酸...     

Neuroimmune dysfunction in frontotemporal dementia: Insights from progranulin and C9orf72 deficiency

Neuroimmune dysfunction is a cardinal feature of neurodegenerative diseases. But how immune dysregulation in the brain and peripheral organs contribute to neurodegeneration remains unclear. Here, we discuss the recent advances highlighting neuroimmune dysfunction as a key disease-driving factor in frontotemporal dementia (FTD). We provide an overview of the clinical observations supporting a high prevalence of autoimmune diseases in FTD patients with mutations in GRN or C9orf72. We then focus on a myriad of evidence from human genetic studies, mouse models, in vitro assays, and multi-omics platform, which indicate that haploinsufficiency in GRN and C9orf72 promotes neuroimmune dysfunction and contributes to neurodegeneration and premature death. These compelling data provide key insights to disease mechanisms, biomarker discovery, and therapeutic interventions for FTD (120 words).     

"调神畅志"针刺法对帕金森伴便秘模型大鼠结肠组织5-HT4R及CaM-MLCK信号通路影响的研究

摘要 目的：探讨"调神畅志"针刺法对帕金森伴便秘(Parkinson''s disease with constipation)模型大鼠结肠组织中5-羟色胺4受体（5-HT4R）及钙调蛋白（CaM）-肌球蛋白轻链激酶（MLCK）信号通路影响的研究,并探讨其可能作用机制。方法：采用随机数字表将60只大鼠分为空白组、假手术组、模型组、西药组、常规针刺组、调神畅志针刺组,每组10只。模型组、常规针刺组、调神畅志针刺组颈背部皮下注射鱼藤酮的方法制造PDD大鼠模型,并用阿扑吗啡（APO）诱导检测。常规针刺组选取天枢、足三里、上巨虚及舞蹈震颤控制区,接电针,连续波频率15Hz,刺激强度2 mA,留针30分钟,1日1次,连续4周;调神畅志针刺组：选取王顺教授 " 调神畅志 " 三六九针法,百会透太阳、中脘、气海、足三里、太冲,采用连续波,头针频率45Hz,腹针频率30Hz,肢体针频率15Hz（体现调神畅志三六九针法的头针重、腹针中、四肢针轻的量化刺激）,刺激强度约2 mA,留针30 min,1日1次,连续4周;西药组采用美多芭、莫沙必利每日灌胃,连续治疗4周;模型组、假手术组：每日2 mL生理盐水灌胃,连续4周;空白组不予处理。采用Western blot法检测各组近端结肠组织中5-HT4R、CaM及MLCK蛋白表达以及含量水平。结果：与空白组相比,模型组大鼠近端结肠组织中5-HT4R、CaM及MLCK蛋白表达水平显著降低(P<0.01),与模型组比较,三个治疗组（西药组、常规针刺组、调神畅志针刺组）近端结肠组织5-HT4R、CaM及MLCK蛋白表达水平显著升高(P<0.01)。与常规针刺组相比,调神畅志组5-HT4R、CaM及MLCK蛋白表达水平明显升高(P<0.05)。结论：针刺可改善PD伴便秘大鼠模型便秘症状,且调神畅志针刺组优于常规针刺组,其作用机理可能通过调节大鼠结肠组织中5-HT4R蛋白表达以及激活CaM-MLCK信号通路来实现的。     

Evaluation of the oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to toxic pyridinium cations by monoamine oxidase (MAO) enzymes and its use to search for new MAO inhibitors and protective agents

Monoamine oxidase (MAO) enzymes catalyze the oxidative deamination of amines and neurotransmitters and inhibitors of MAO are useful as neuroprotectants. This work evaluates the human MAO-catalyzed oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a dopaminergic neurotoxin, to the directly-acting neurotoxic metabolites, 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP⁺) and 1-methyl-4-phenylpyridinium (MPP⁺) measured by High-Performance Liquid Chromatography (HPLC), and this approach is subsequently used as a new method for screening of MAO inhibitors and protective agents. Oxidation of MPTP by human MAO-B was more efficient than by MAO-A. R-Deprenyl, a known neuroprotectant, norharman (β-carboline), 5-nitroindazole and menadione (vitamin K3) inhibited MAO-B and reduced the formation of toxic pyridinium cations. Clorgyline and the β-carbolines, harman and norharman, inhibited the oxidation of MPTP by MAO-A. Cigarette smoke, as well as the naturally occurring β-carbolines (norharman and harman) isolated from smoke and coffee inhibited the oxidation of MPTP by MAO-B and/or MAO-A, suggesting protective effects against MPTP. The results show the suitability of the approach used to search for new MAO inhibitors with eventual neuroprotective activity.     

Characterization of the C584R variant in the mtDNA depletion syndrome gene FBXL4, reveals a novel role for FBXL4 as a regulator of mitochondrial fusion

Mutations in FBXL4 (F-Box and Leucine rich repeat protein 4), a nuclear-encoded mitochondrial protein with an unknown function, cause mitochondrial DNA depletion syndrome. We report two siblings, from consanguineous parents, harbouring a previously uncharacterized homozygous variant in FBXL4 (c.1750 T > C; p.Cys584Arg). Both patients presented with encephalomyopathy, lactic acidosis and cardiac hypertrophy, which are reported features of FBXL4 impairment. Remarkably, dichloroacetate (DCA) administration to the younger sibling improved metabolic acidosis and reversed cardiac hypertrophy. Characterization of FBXL4 patient fibroblasts revealed severe bioenergetic defects, mtDNA depletion, fragmentation of mitochondrial networks, and abnormalities in mtDNA nucleoids. These phenotypes, observed with other pathogenic FBXL4 variants, confirm the pathogenicity of the p.Cys584Arg variant. Although treating FBXL4 fibroblasts with DCA improved extracellular acidification, in line with reduced lactate levels in patients, DCA treatment did not improve any of the other mitochondrial functions. Nonetheless, we highlight DCA as a potentially effective drug for the management of elevated lactate and cardiomyopathy in patients with pathogenic FBXL4 variants. Finally, as the exact mechanism through which FBXL4 mutations lead to mtDNA depletion was unknown, we tested the hypothesis that FBXL4 promotes mitochondrial fusion. Using a photo-activatable GFP fusion assay, we found reduced mitochondrial fusion rates in cells harbouring a pathogenic FBXL4 variant. Meanwhile, overexpression of wildtype FBXL4, but not the p.Cys584Arg variant, promoted mitochondrial hyperfusion. Thus, we have uncovered a novel function for FBXL4 in promoting mitochondrial fusion, providing important mechanistic insights into the pathogenic mechanism underlying FBXL4 dysfunction.