Altered telomeres in tumors with ATRX and DAXX mutations

The proteins encoded by ATRX and DAXX participate in chromatin remodeling at telomeres and other genomic sites. Because inactivating mutations of these genes are common in human pancreatic neuroendocrine tumors (PanNETs), we examined the telomere status of these tumors. We found that 61% of PanNETs displayed abnormal telomeres that are characteristic of a telomerase-independent telomere maintenance mechanism termed ALT (alternative lengthening of telomeres). All of the PanNETs exhibiting these abnormal telomeres had ATRX or DAXX mutations or loss of nuclear ATRX or DAXX protein. ATRX mutations also correlate with abnormal telomeres in tumors of the central nervous system. These data suggest that an alternative telomere maintenance function may operate in human tumors with alterations in the ATRX or DAXX genes.     

Games played by rogue proteins in prion disorders and Alzheimer's disease

The incidence of Alzheimer's disease (AD) and that of prion disorders (PrD) could not be more different. One-third of octogenarians succumb to AD, whereas Creutzfeldt-Jakob disease typically affects one individual in a million each year. However, these diseases have many common features impinging on the metabolism of neuronal membrane proteins: the amyloid precursor protein APP in the case of AD, and the cellular prion protein PrPC in PrD. APP begets the Abeta peptide, whereas PrPC begets the malignant prion protein PrPSc. Both Abeta and PrPSc are associated with disease, but we do not know what triggers their accumulation and neurotoxicity. A great deal has been learned, however, about protein folding, misfolding, and aggregation; an entirely new class of intramembrane proteases has been identified; and unsuspected roles for the immune system have been uncovered. There is reason to expect that prion research will profit from advances in the understanding of AD, and vice versa.     

An oral vaccine against NMDAR1 with efficacy in experimental stroke and epilepsy

The brain is generally considered immunoprivileged, although increasing examples of immunological responses to brain antigens, neuronal expression of major histocompatibility class I genes, and neurological autoimmunity have been recognized. An adeno-associated virus (AAV) vaccine generated autoantibodies that targeted a specific brain protein, the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptor. After peroral administration of the AAV vaccine, transgene expression persisted for at least 5 months and was associated with a robust humoral response in the absence of a significant cell-mediated response. This single-dose vaccine was associated with strong anti-epileptic and neuroprotective activity in rats for both a kainate-induced seizure model and also a middle cerebral artery occlusion stroke model at 1 to 5 months following vaccination. Thus, a vaccination strategy targeting brain proteins is feasible and may have therapeutic potential for neurological disorders.     

棉花晋A细胞质雄性不育系及其保持系差异蛋白质组分析

【目的】对棉花晋A细胞质雄性不育系及其同核异质保持系MB177（JB）雄性败育关键时期的花药进行差异蛋白质组研究,为进一步揭示棉花细胞质雄性不育机理奠定基础。【方法】运用双向电泳技术对晋A细胞质雄性不育系及其保持系小孢子发育的造孢细胞时期和小孢子母细胞时期表达的蛋白质进行分离（考马斯亮蓝染色）;采用PDQuest8.0.1软件进行斑点检测,并经统计学分析确定获得差异表达蛋白质;对这些差异蛋白质斑点进行LC-Chip-ESI-QTOF-MS质谱分析,用Mascot软件搜索NCBInr绿色植物,鉴定差异表达蛋白质;对差异表达蛋白质进行GO和KEGG功能分析。【结果】PDQuest8.0.1软件分析表明,晋A不育系和保持系在花药发育的造孢细胞时期和小孢子母细胞时期的花蕾总蛋白质斑点数分别为1 525、1 540和1 554、1 540,这些蛋白质斑点的分子量分布在10-100 kD,等电点分布在3-10。经差异定量研究和统计学分析,共鉴定到15个在晋A不育系与保持系间显著差异表达的蛋白斑点,15个差异蛋白质斑点都得到了质谱特异峰图。对应的蛋白质H（+）-转运ATP合成酶、谷胱甘肽还原酶、线粒体上的ATP酶亚基、核酮糖-1,5-二磷酸羧化酶/加氧酶大亚基和UDP-D葡萄糖脱氢酶在不育系与保持系花药发育2个阶段均差异表达;膜联蛋白、S-甲酸谷胱甘肽水解酶、momilactone A 合成酶类似物、一个具有丙二烯氧化环化酶活性的未命名蛋白质和一个位于线粒体上的保守预测蛋白质仅在不育系和保持系花药发育的造孢细胞时期差异表达;β-羟酰-ACP脱水酶、丙酮酸脱氢酶-α亚基以及与花粉发育相关的一个预测蛋白质仅在不育系和保持系花药发育的小孢子母细胞时期差异表达。这些差异表达蛋白质主要参与小孢子与绒毡层发育过程,它们的下调或上调表达可能造成发育与代谢过程的不协调性,产生不正常的小孢子和绒毡层提前解体,从而导致雄性不育。采用荧光定量PCR分析核酮糖-1,5-二磷酸羧化酶/加氧酶大亚基基因和H（+）转运ATP合成酶基因的转录变化,它们在转录水平与蛋白质表达的趋势一致。【结论】晋A不育系的小孢子败育可能与能量代谢紊乱、茉莉酸合成途径损害、细胞内大量ROS积累、查尔酮合酶活性下降有关。雄性不育的产生是一个复杂的生物学过程,涉及到多个基因的相互作用,构成了一个复杂的调控网络。     

The genetics of adult-onset neuropsychiatric disease: complexities and conundra?

Genetic factors play a major role in the etiology of adult-onset neurodegenerative and neuropsychiatric disorders. Several highly penetrant genes have been cloned for rare, autosomal-dominant, early-onset forms of neurodegenerative diseases. These genes have provided important insights into the mechanisms of these diseases (often altering neuronal protein processing). However, the genes associated with inherited susceptibility to late-onset neurodegenerative diseases, schizophrenia, and bipolar disorder appear to have smaller effects and are likely to interact with each other (and with nongenetic factors) to modulate susceptibility and/or disease phenotype. Several strategies have recently been applied to address this complexity, leading to the identification of a number of candidate susceptibility loci/genes.     

A century of Alzheimer's disease

One hundred years ago a small group of psychiatrists described the abnormal protein deposits in the brain that define the most common neurodegenerative diseases. Over the past 25 years, it has become clear that the proteins forming the deposits are central to the disease process. Amyloid-beta and tau make up the plaques and tangles of Alzheimer's disease, where these normally soluble proteins assemble into amyloid-like filaments. Tau inclusions are also found in a number of related disorders. Genetic studies have shown that dysfunction of amyloid-beta or tau is sufficient to cause dementia. The ongoing molecular dissection of the neurodegenerative pathways is expected to lead to a true understanding of disease pathogenesis.     

Spongiform degeneration in mahoganoid mutant mice

mahoganoid is a mouse coat-color mutation whose pigmentary phenotype and genetic interactions resemble those of Attractin (Atrn). Atrn mutations also cause spongiform neurodegeneration. Here, we show that a null mutation for mahoganoid causes a similar age-dependent neuropathology that includes many features of prion diseases but without accumulation of protease-resistant prion protein. The gene mutated in mahoganoid encodes a RING-containing protein with E3 ubiquitin ligase activity in vitro. Similarities in phenotype, expression, and genetic interactions suggest that mahoganoid and Atrn genes are part of a conserved pathway for regulated protein turnover whose function is essential for neuronal viability.     

The molecular control of blood cell development

The establishment of a cell culture system for the clonal development of blood cells has made it possible to identify the proteins that regulate the growth and differentiation of different blood cell lineages and to discover the molecular basis of normal and abnormal cell development in blood forming tissues. A model system with myeloid blood cells has shown that (i) normal blood cells require different proteins to induce cell multiplication (growth inducers) and cell differentiation (differentiation inducers), (ii) there is a hierarchy of growth inducers as cells become more restricted in their developmental program, and (iii) a cascade of interactions between proteins determines the correct balance between immature and mature cells in normal blood cell development. Gene cloning has shown that there is a family of different genes for these proteins. Normal protein regulators of blood cell development can control the abnormal growth of certain types of leukemic cells and suppress malignancy by inducing differentiation to mature nondividing cells. Chromosome abnormalities that give rise to malignancy in these leukemic cells can be bypassed and their effects nullified by inducing differentiation, which stops cells from multiplying. These blood cell regulatory proteins are active in culture and in the body, and they can be used clinically to correct defects in blood cell development.     

Detecting and measuring cotranslational protein degradation in vivo

Nascent polypeptides emerging from the ribosome and not yet folded may at least transiently present degradation signals similar to those recognized by the ubiquitin system in misfolded proteins. The ubiquitin sandwich technique was used to detect and measure cotranslational protein degradation in living cells. More than 50 percent of nascent protein molecules bearing an amino-terminal degradation signal can be degraded cotranslationally, never reaching their mature size before their destruction by processive proteolysis. Thus, the folding of nascent proteins, including abnormal ones, may be in kinetic competition with pathways that target these proteins for degradation cotranslationally.     

Choline acetyltransferase activity in striatum of neonatal rats increased by nerve growth factor

Some neurodegenerative disorders may be caused by abnormal synthesis or utilization of trophic molecules required to support neuronal survival. A test of this hypothesis requires that trophic agents specific for the affected neurons be identified. Cholinergic neurons in the corpus striatum of neonatal rats were found to respond to intracerebroventricular administration of nerve growth factor with prominent, dose-dependent, selective increases in choline acetyltransferase activity. Cholinergic neurons in the basal forebrain also respond to nerve growth factor in this way. These actions of nerve growth factor may indicate its involvement in the normal function of forebrain cholinergic neurons as well as in neurodegenerative disorders involving such cells.     

大豆品质调控基因克隆和功能研究进展

大豆(Glycine max L.)是世界上重要的经济作物,为人类生活提供所需的食用油和植物蛋白。大豆油脂、蛋白质和异黄酮含量决定了大豆的经济价值,大豆品质的优劣直接关系到食用者的身体健康,因此,越来越受到广大科研工作者的关注。大豆油脂脂肪酸组成对油的营养价值、耐储性及加工工艺等都有很大影响。油脂的组成和积累受脂肪酸合成途径中多种酶活性的影响,这些基因的表达还受到转录前、转录和转录后水平的调控,有许多相关基因参与此过程。目前大豆油脂的转录调控研究较多。研究表明,GmDOF4和GmDOF11类转录因子可以激活乙酰辅酶A羧化酶和长链脂酰辅酶A合成酶,从而提高了种子油分含量。转录因子GmMYB73可以通过抑制GL2进而促进磷脂酶D的活性,增加了转基因种子的油含量。转录因子GmbZIP123主要通过诱导蔗糖转运蛋白基因(AtSUC1、AtSUC5)和细胞壁转化酶基因(AtcwINV1、AtcwINV3和AtcwINV6)的表达,促进蔗糖从叶片到种子的运输,为油脂合成提供更多原料和能量,从而提高种子油脂含量。转录因子GmNFYA通过激活WRI及油脂合成相关基因,从而提高了种子油含量。大豆籽粒富含蛋白质,占籽粒干物质的40%左右(31%—55%)。大豆蛋白含有8种人体必需的氨基酸,是一种品质优良的植物性蛋白质,在膳食中可以代替部分动物性蛋白质。植物中油分和蛋白质往往是负相关的,GmDOF4和GmDOF11类转录因子可以提高植物油份含量,但其直接结合CRA1启动子,从而下调储藏蛋白的表达。大豆异黄酮是大豆生长过程中形成次生代谢产物,具有多种生物活性,在动植物体内有着广泛的生理作用。近年来大豆异黄酮已成为大豆最引人注目功能成分之一,也是食品与营养学研究热点之一。类黄酮类物质可能通过调节结节的产生从而调控植物的根瘤发育、生长繁殖和固氮作用。大豆异黄酮对乳腺癌、前列腺癌、心血管疾病和骨质疏松症的治疗也表现出其他一些有益的效应。目前研究表明,GmMYB176可以调控CHS8的表达,而干扰GmMYB176的表达降低了大豆根毛中异黄酮的水平,这表明GmMYB176对于异黄酮的生物合成是必需的。本文综述了大豆种子油分、蛋白以及异黄酮含量相关基因的研究进展,并对大豆种子油分、蛋白及异黄酮在转录水平和/或其他方面所受到的调控进行阐述。     

谷子MRP蛋白家族序列特征、分子进化及表达模式分析

本研究旨在深入了解谷子叶酸转运家族成员的基因结构和表达模式,为谷子体内叶酸转运分子机制的研究奠定基础。使用Phytozome、Clustal X、MEGA7.0等在线工具和软件,对谷子MRP家族成员进行生物信息学分析;基于谷子谷穗有参转录组测序数据,分析谷子MRP家族成员表达模式。结果显示,谷子MRP蛋白家族成员共21个,在7号染色体分布最多,有8个基因;17个谷子MRP蛋白偏碱性和4个偏酸性,根据疏水值判断其均为亲水性蛋白;成员SiMRP7、SiMRP12基因的表达量与谷子组织中的总叶酸含量表现出协同降低的趋势,推测这两个蛋白可能对谷子叶酸的积累起到调控作用。本研究有助于进一步鉴定叶酸转运相关蛋白,为后续研究叶酸代谢途径及谷子基因挖掘提供了理论基础。     

A role for peroxisomes in photomorphogenesis and development of Arabidopsis

The nuclear protein DET1 is a central repressor of photomorphogenesis in plants. We have identified the molecular lesion in ted3, a mutation that dominantly suppresses the phenotypes of det1-1. TED3 encodes a peroxisomal protein (AtPex2p) essential for Arabidopsis growth. Developmental defects and the abnormal expression of many genes in det1 are rescued by ted3. ted3 also partially suppresses another pleiotropic de-etiolated mutant cop1. Thus, peroxisomes, whose functions are still largely unexplored, play a key role in a photomorphogenetic pathway negatively regulated by the DET1 and COP proteins.     

Antagonistic control of disease resistance protein stability in the plant immune system

Pathogen recognition by the plant immune system is governed by structurally related, polymorphic products of disease resistance (R) genes. RAR1 and/or SGT1b mediate the function of many R proteins. RAR1 controls preactivation R protein accumulation by an unknown mechanism. We demonstrate that Arabidopsis SGT1b has two distinct, genetically separable functions in the plant immune system: SGT1b antagonizes RAR1 to negatively regulate R protein accumulation before infection, and SGT1b has a RAR1-independent function that regulates programmed cell death during infection. The balanced activities of RAR1 and SGT1, in concert with cytosolic HSP90, modulate preactivation R protein accumulation and signaling competence.     

三七根差异基因表达序列标签生物信息学分析

本研究利用生物信息学方法,对从三七根抑制消减杂交cDNA文库中随机挑选的91个EST序列进行了分析。结果表明:91个克隆组装分析后有4个重叠群和83个单拷贝EST,代表了87个基因。已知功能的基因序列共58个,占66%,按基因功能分类为10类,其中大多基因与代谢途径和分泌途径有关。未知功能基因序列29个,占33%。对33个氨基酸序列可通读的EST进行跨膜结构和信号肽分析,结果表明:9个克隆有信号肽,其中3个克隆有跨膜结构,可能为膜蛋白,6个克隆可能为分泌蛋白。功能位点分析结果表明:大多数基因与胞外分泌,调节细胞凋亡和细胞周期,信号传导有关。功能结构域分析结果表明:除9个克隆没有预测到功能结构域外,其它克隆的结构域与信号传导,转录调控,电子传递,协迫,光合作用,蛋白折叠等有关。亚细胞定位大多数位于细胞质和细胞核。     

Identification of the protein encoded by the E6 transforming gene of bovine papillomavirus

Papillomaviruses (PV) contain several conserved genes that may encode nonstructural proteins; however, none of these predicted gene products have been identified. Papillomavirus E6 genes are retained and expressed as RNA in PV-associated human and animal carcinomas and cell lines. This suggests that the E6 gene product may be important in the maintenance of the malignant phenotype. The E6 open reading frame of the bovine papillomavirus (BPV) genome has been identified as one of two BPV genes that can independently transform mouse cells in vitro. A polypeptide encoded by this region of BPV was produced in a bacterial expression vector and used to raise antisera. The antisera specifically immunoprecipitated the predicted 15.5-kilodalton BPV E6 protein from cells transformed by the E6 gene. The E6 protein was identified in both the nuclear and membrane fractions of these transformed cells.     

基于转录组的油茶DHHC型锌指蛋白基因家族的鉴定及分析

DHHC型锌指蛋白参与细胞内蛋白质的棕榈酰化修饰,对植物的生长发育、器官形成、生殖发育及胁迫响应等生命活动具有重要的调控作用。基于油茶叶片转录组数据,筛选出23个DHHC型锌指蛋白基因,应用生物信息学方法对其蛋白理化性质、结构域、系统进化等进行了分析。结果表明,23个DHHC型锌指蛋白的序列大小为195~725 aa,均包含一个保守的DHHC-CRD结构域,大部分DHHC型锌指蛋白具有4个跨膜区,主要定位于细胞核和细胞膜中。系统进化分析将其分为4类,与拟南芥和水稻均有不同程度的同源关系,DHHC型锌指蛋白在不同物种间具有遗传保守性。23个DHHC型锌指蛋白基因在结实量大和结实量小的单株的不同发育时期叶片中均有不同程度的表达。CoDHHC9、CoDHHC13、CoDHHC22在油茶抽梢生长期的叶片中表达上调;CoDHHC6、CoDHHC12、CoDHHC18、CoDHHC23在花芽分化时期和果实成熟时期的叶片中表达量较高,且在结实量较小而开花较多的单株中表达上调更为明显,这些基因可能参与油茶花芽分化及花朵发育过程;CoDHHC5、CoDHHC11、CoDHHC15在不同时期的叶片中表达量均较低。研究结果为进一步对油茶DHHC型锌指蛋白家族基因的克隆和功能分析提供依据,有助于进一步研究该基因家族在油茶生殖发育中的调控功能。