组蛋白去乙酰化酶1/2参与调控小鼠卵子发生的研究进展

卵子发生是雌性哺乳动物的基本生殖过程,是后续受精及胚胎发育的基础.近年来研究表明,表观修饰在调控哺乳动物生殖过程(如卵子发生、精子发生、植入前胚胎发育及性别分化等)中扮演着重要的角色.以组蛋白乙酰化为例,组蛋白乙酰转移酶(histone acetyltransferases,HATs)和去乙酰化酶(histone de...     

小鼠植入前胚胎GCN5和HDAC1表达模式及体外培养对其表达的影响

为探讨小鼠植入前胚胎组蛋白乙酰化酶GCN5（general control of nucleotide synthesis,GCN5）和组蛋白去乙酰化酶1（histone deacetylasel,HDAC1）的表达模式及常规体外培养对它们表达的影响,应用荧光免疫细胞化学技术,检测了体内和体外培养的小鼠2、4、8细胞期卵裂胚胎、桑葚胚和囊胚GCN5和HDAC1的表达。结果显示,GCN5在体内组各细胞期卵裂胚胎和桑葚胚的细胞浆内均呈高表达,细胞核内未见明显表达,而囊胚细胞的细胞浆和细胞核内均无表达：HDACl在体内组小鼠2细胞期胚胎中以细胞浆内表达为主,在其他各期胚胎均以细胞核内表达为主。囊胚期内细胞团部分细胞的细胞核内未见HDAC1表达。GCN5在体外组小鼠植入前各期胚胎均不表达。而HDAC1的表达强度明显低于体内组的。提示体外培养抑制小鼠植入前胚胎GCN5和明显降低HDAC1的表达,影响胚胎基因的正确性表达。     

小鼠植入前胚胎GCN5和HDAC1表达模式及体外培养对其表达的影响

为探讨小鼠植入前胚胎组蛋白乙酰化酶GCN5(general control of nucleotide synthesis,GCN5) 和组蛋白去乙酰化酶1(histone deacetyluse1,HDAC1)的表达模式及常规体外培养对它们表达的影响,应用荧光免疫细胞化学技术,检测了体内和体外培养的小鼠2、4、8细胞期卵裂胚胎、桑葚胚和囊胚GCN5和HDAC1的表达。结果显示,GCN5在体内组各细胞期卵裂胚胎和桑葚胚的细胞浆内均呈高表达,细胞核内未见明显表达,而囊胚细胞的细胞浆和细胞核内均无表达:HDAC1在体内组小鼠2细胞期胚胎中以细胞浆内表达为主,在其他各期胚胎均以细胞核内表达为主．囊胚期内细胞团部分细胞的细胞核内未见HDAC1表达。GCN5在体外组小鼠植入前各期胚胎均不表达,而 HDAC1的表达强度明显低于体内组的。提示体外培养抑制小鼠植入前胚胎GCN5和明显降低 HDAC1的表达,影响胚胎基因的正确性表达。     

靶向调控SIRT1与阿尔茨海默病治疗

沉默信息调节因子1 (silent information regulator 1, SIRT1)是哺乳动物NAD+依赖的去乙酰化酶沉默信息调节因子(sirtuin)家族的七种蛋白质之一。SIRT1具有神经保护作用,且研究揭示SIRT1在阿尔茨海默病(Alzheimer’s disease, AD)中具有潜在神经保护作用。SIRT1调节许多AD相关病理过程,包括调节淀粉样蛋白前体蛋白(amyloid-β precursor protein, APP)剪切、神经炎症、神经退行性变和线粒体功能障碍等。SIRT1在AD中受到了特别的关注,药理学或遗传学手段激活sirtuin通路在AD实验模型中显示出治疗作用。本综述阐述了SIRT1在AD中的病理作用机制最新研究进展,并对SIRT1诱导剂及其在AD中的治疗潜力进行了概述。     

组蛋白去乙酰化酶抑制剂的研究进展

核小体是真核生物染色质的基本单位,通过对组蛋白核心的N-端的乙酰化、甲基化、磷酸化、遍在蛋白化的修饰作用而影响细胞的功能。组蛋白乙酰化酶(histone acetylase HAT)及组蛋白去乙酰化酶(Histone Deacetylases HDAC)之间的动态平衡控制着染色质的结构和基因表达。当组蛋白去乙酰化水平增加,乙酰化水平相对降低,即会导致正常的细胞周期与代谢行为的改变而诱发肿瘤,及神经退行性变。组蛋白去乙酰化酶抑制剂(Histone Deacetylases-inhibitor HDACi)目前是国内外研究的热点。其中,曲古霉素A(Trichostatin A TSA),是最早发现的天然组蛋白去乙酰化酶抑制剂;伏立诺他(Suberoylanilide Hydroxamic Acid SAHA)已经美国FDA批准用于治疗皮肤T细胞淋巴瘤。本文就HDACi分类及其功能出发综述HDACi的作用机制及研究进展。     

小鼠组蛋白去乙酰化酶基因序列分析

利用生物信息学方法,通过NCBI和其他生物学数据库及DNAstar、Clustal X等生物信息学软件对小鼠11种去乙酰化酶(histone deacetylase,HDAC)的基因结构、开放阅读框、GC含量、氨基酸序列、同源性及染色体定位等问题进行了分析。结果发现小鼠HDACs外显子从10～29个不等,开放阅读框长度从1044～3450bp不等,GC含量约为50%。序列比对分析后发现HDAC1和HDAC2蛋白质序列之间相似性达89.8%,其余HDACs蛋白质序列之间相似性相对较低,HDAC7和HDAC8之间仅为8.8%。系统发生分析表明小鼠11种HDACs也按照酵母种系发育中不同HDACs的结构聚类为Ⅰ、Ⅱa、Ⅱb和Ⅳ等4个类群,来源于基因复制。染色体定位分析发现除HDAC6和HDAC8位于X染色体外,其余均位于常染色体。研究结果为进一步研究小鼠HDACs转录调控的分子机制和蛋白质功能奠定基础。     

Nucleostemin和HDAC1在卵巢肿瘤中的表达及意义

目的:研究核干细胞因子(Nucleostemin, NS)和组蛋白去乙酰化酶1(HDAC1)在卵巢肿瘤及正常卵巢组织中的表达,并分析其表达与临床指标的关系及两者间的表达相关性。方法:选择2010年至2017年我院卵巢石蜡标本60例,其中卵巢肿瘤50例,正常卵巢组织10例。应用免疫组化法检测NS与HDAC1的表达,并分析它们与年龄、肿瘤分期等临床指标的相关性。结果:在30例卵巢恶性肿瘤、10例卵巢交界性肿瘤、10例卵巢良性肿瘤组织中,NS表达的阳性率分别为93.3%、40%、20%,HDAC1的阳性率分别为90%、60%、20%。在正常卵巢组织中未见NS及HDAC1表达。在卵巢恶性肿瘤组中,NS和HDAC1的阳性表达率显著高于其他三组(P0.05),两者表达呈正相关(r=0.56, P0.05),且均与分化程度呈负相关(r=-0.76, P0.001; r=-0.53, P0.01),而与患者年龄、术前血清CA125水平、临床分期和病理类型无关。结论:NS和HDAC1倾向于卵巢恶性肿瘤中表达,且与卵巢恶性肿瘤的分化程度负相关。     

Sirtuin1:抗炎治疗新靶点

Sirtuin 1(SIRT1)是组蛋白去乙酰化酶的代表性成员,除可调节代谢、衰老、凋亡外,SIRT1还可通过催化组蛋白及核因子κB(NF-κB)、激活蛋白1(AP-1)等的去乙酰化,从而改变染色质构象、降低转录因子活性、下调炎症基因转录。临床研究已揭示SIRT1在某些炎症性疾病中含量明显降低,而动物实验证实白藜芦醇、SRT1720等SIRT1激活剂可有效减轻炎症损伤。因而,SIRT1有望成为抗炎治疗的新靶点。     

Reduced expression of SIRT1 is associated with diminished glucose-induced insulin secretion in islets from calorie-restricted rats

Alterations in food intake such as caloric restriction modulate the expression of SIRT1 and SIRT4 proteins that are involved in pancreatic β-cell function. Here, we search for a possible relationship between insulin secretion and the expression of SIRT1, SIRT4, PKC and PKA in islets from adult rats submitted to CR for 21 days. Rats were fed with an isocaloric diet (CTL) or received 60% (CR) of the food ingested by CTL. The dose-response curve of insulin secretion to glucose was shifted to the right in the CR compared with CTL islets (EC₅₀ of 15.1±0.17 and 10.5±0.11 mmol/L glucose). Insulin release by the depolarizing agents arginine and KCl was reduced in CR compared with CTL islets. Total islet insulin content and glucose oxidation were also reduced in CR islets. Leucine-stimulated secretion was similar in both groups, slightly reduced in CR islets stimulated by leucine plus glutamine but higher in CR islets stimulated by ketoisocaproate (KIC). Insulin secretion was also higher in CR islets stimulated by carbachol, compared with CTL islets. No differences in the rise of cytosolic Ca²⁺ concentrations stimulated by either glucose or KCl were observed between groups of islets. Finally, SIRT1, but not SIRT4, protein expression was lower in CR compared with CTL islets, whereas no differences in the expression of PKC and PKA proteins were observed. In conclusion, the lower insulin secretion in islets from CR rats was, at least in part, due to an imbalance between the expression of SIRT1 and SIRT4.     

去乙酰化酶SIRT1的表达及活性调控机制

SIRT1是哺乳动物中重要的NAD+依赖性去乙酰化酶,参与许多重要的生理和病理过程,如衰老、细胞死亡和肿瘤发生。如何精确调节SIRT1的表达和活性对SIRT1执行其生物学功能至关重要。文章以基因表达的不同阶段为切入点,对调控SIRT1表达及活性的机制进行了论述。     

SIRT1 and SIRT5 activity expression and behavioral responses to calorie restriction

To investigate the effects of calorie restriction (CR) on behavioral performance and expression of SIRT1 and SIRT5 in rat cerebral tissues. Beginning at 18 months of age, 60 rats were randomly divided into a CR group (n = 30) and a group that remained fed ad libitum (AL; n = 30). CR rats were restricted to a diet of 60% of their daily food consumption. After 6 months of CR, CR rats displayed a maximum 50% reduction in escape latency (AL 20 ± 0.3 s vs. CR 10 ± 0.2 s) and a 3.2 s decrease in time and distance to target when evaluated in Morris water maze tests. The levels of SIRT1 and SIRT5 protein in cerebral tissues of CR rats were elevated compared to AL rats (P < 0.05). CR retarded declines in cognitive ability and enhanced the expression of both SIRT1 and SIRT5 proteins in the cerebral tissue of CR rats compared with AL rats.     

SIRT1与神经变性疾病

SIRT1(silent mating type information regulation2homolog1)是Sirtuins脱乙酰基酶家族中的一员,是酵母沉默信息调节因子SIR2(silence information regulator)的同源物,因其能在许多生物体模型中作为寿命延长调节子调控细胞生命周期而受到特别关注。SIRT1蛋白存在于哺乳动物细胞质和细胞核中,是老化相关蛋白。SIRT1作用于基因转录因子能加强基因组的稳定性。神经系统发生变性疾病时SIRT1表达量上调,起到一定的神经保护作用。但有实验验证神经元损伤SIRT1过表达导致记忆缺失,并没有起到神经保护作用。SIRT1诱导剂,可以是Sirtuin的激动剂也可以是能量限制状态。目前在生命科学领域里SIRT1已经凸显其科学价值地位,该文就SIRT1及其与神经变性疾病之间的关系做一综述。     

Function of SIRT1 in physiology

Sirtuins were originally defined as a family of oxidized nicotinamide adenine nucleotide (NAD⁺)-dependent enzymes that deacetylate lysine residues on various proteins. The sirtuins are remarkably conserved throughout evolution from archae to eukaryotes. They were named after their homology to the Saccharomyces cerevisiae gene silent information regulator 2 (Sir2). The mammalian sirtuins, SIRT1-7, are implicated in a variety of cellular functions ranging from gene silencing, control of the cell cycle and apoptosis, and energy homeostasis. As SIRT1 is a nuclear protein and is the mammalian homolog most highly related to Sir2, it has been the focus of a large number of recent studies. Here we review some of the current data related to SIRT1 and discuss its mode of action and biological role in cellular and organismal models. Published in Russian in Biokhimiya, 2009, Vol. 74, No. 7, pp. 869–876.     

Expression of D2 dopamine receptor in the mouse brain

The neurotransmitter, dopamine, binds to dopamine receptor (DR), and is involved in several functions of the brain, such as initiation and execution of movement, emotion, prolactin secretion, etc. Of all the five DRs, D2 dopamine receptor has maximal affinity for dopamine. D2 has a short isoform, D2S, and a long isoform D2L. D2L is longer than D2S by 29 amino acid residues. We studied the expression of the gene and protein of D2 receptor in the cerebral and cerebellar cortices of the brain of new born, developing, adult, and old male mice to find out: (i) at what stage of development, expression of the gene peaks and (ii) if it undergoes any changes as the animal ages, which may account for the neurodegenerative changes and symptoms of Parkinson's and other diseases seen in old age. RT-PCR and Western blot studies show that peak expression of D2 gene occurs in the cerebral and cerebellar cortices around 15-day after birth. We speculate that the majority of dopaminergic synapses are established and possibly become functional in the brain around 15-day after birth. The expression of D2 receptor is upregulated in the cerebral cortex in old mice. However, it is down-regulated in the cerebellar cortex.     

Metformin overcomes high glucose-induced insulin resistance of podocytes by pleiotropic effects on SIRT1 and AMPK

Podocyte insulin sensitivity is critical for glomerular function, and the loss of appropriate insulin signaling leads to alterations and disorders featuring diabetic nephropathy. Energy-sensing pathways, such as AMP-dependent protein kinase (AMPK) and protein deacetylase SIRT1, have been shown to play an important role in insulin resistance. The absence of a stimulating effect of insulin on glucose uptake into podocytes after exposure to hyperglycemic conditions has been demonstrated to be related to a decreased level and activity of SIRT1 protein, leading to reduced AMPK phosphorylation.The present work was undertaken to investigate metformin's ability to restore the insulin responsiveness of podocytes by regulating SIRT1 and AMPK activities.Primary rat podocytes cultured with standard or high glucose concentrations for 5 days were transfected with siRNAs targeting SIRT1, AMPKα1, or AMPKα2. SIRT1 activity was measured by a fluorometric method. Insulin-stimulated changes in glucose uptake were used to detect insulin resistance. Podocyte permeability was measured by a transmembrane albumin flux assay to examine podocytes functioning.Our results demonstrated that metformin activated SIRT1 and AMPK, prevented hyperglycemia-induced reduction of SIRT1 protein levels, ameliorated glucose uptake into podocytes, and decreased glomerular filtration barrier permeability. Furthermore, metformin activated AMPK in a SIRT1-independent manner, as the increase in AMPK phosphorylation after metformin treatment was not affected by SIRT1 downregulation. Therefore, the potentiating effect of metformin on insulin-resistant podocytes seemed to be dependent on AMPK, as well as SIRT1 activity, establishing multilateral effects of metformin action.     

Leptin induces IL-1 receptor antagonist expression in the brain

Fructose has been shown to protect hepatocyte viability during hypoxia or exposure to mitochondrial electron transport inhibitors. We report here that the fructose metabolite D-glyceraldehyde (D-GA) is a good inhibitor of the mitochondrial permeability transition pore (PTP) in isolated rat liver mitochondria. We propose that a substantial portion of the protective effect of fructose on hepatocytes is due to D-GA inhibition of the permeability transition. Aldehydes which are substrates of the mitochondrial aldehyde dehydrogenase (mALDH) afford protection, while poor substrates do not. Protection is prevented by the ALDH inhibitor chloral hydrate. We propose that the NADH/NAD(+) ratio is the key to protection. The aldehydes phenylglyoxal (PGO) and 4-hydroxynonenal (4-HNE), which have previously been shown to inhibit the PTP, apparently function by a different mechanism independent of mALDH activity. Both PGO or 4-HNE are themselves potent inhibitors of ALDH, and their protective effect cannot be blocked by an ALDH inhibitor.