胱硫醚β-合酶的研究现状

胱硫醚β-合酶的活性降低是心脑血管系统等系统疾病独立的危险因子。目前研究发现使酶活性降低或丧失的胱硫醚合酶基因的变异在人群中存在多态性。     

贵州少数民族胱硫醚-β-合酶基因C699T的分布

目的 对中国贵州雷山苗族和三都水族群体胱硫醚-β-合酶基因C699T进行多态性分析,计算其基因频率,获取相应的遗传信息.方法 采用nest-PCR和变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术寻找突变基因,对突变基因的PCR产物进行基因直接测序,并与文献报道的各种人群的相应数据进行比较.结果 雷山苗族和三都水族群体的胱硫醚-β-合酶基因699T等位基因频率分别为5.1%和5.4%.结论 雷山苗族和三都水族两个群体间胱硫醚-β-合酶基因699T等位基因差异无统计学意义,但它们均显著低于黑种人和白种人群体.     

贵州苗族CBS基因与MTHFR基因多态性研究

目的对贵州雷山西江苗族胱硫醚合酶（cystathionine beta-synthase,CBS）基因与亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR）基因多态性进行研究。方法采用PCR-限制性片断长度多态性（PCR-RFLP）、PCR-变性梯度凝胶电泳（PCR-DGGE）-基因测序（Gene sequenceing）的方法检测贵州雷山西江苗族CBS基因与MTHFR基因的基因频率及基因型的分布。结果CBS基因的699C→T等位基因频率为5.6%、833 T→C等位基因频率为29.4%。MTHFR基因的677C→T等位基因频率为10.64%、1298 A→C等位基因频率为48.66%。结论同一民族,胱硫醚合酶基因与亚甲基四氢叶酸还原酶基因存在群体差异,这种群体差异可能与人群对多种疾病的群体易感性有关。     

胱硫醚-β-合成酶和胱硫醚-β-裂解酶在颈动脉体中的分布

本研究探讨胱硫醚-β-合成酶(CBS)和胱硫醚-β-裂解酶(CSE)在颈动脉体中的分布.应用组织化学技术检测CBS和CSE在颈动脉体中的表达分布并进一步用激光共聚焦对该酶在细胞中的分布进行定位研究.结果表明小鼠颈动脉体Ⅰ型上皮细胞表达CBS和CSE免疫活性,主要分布在胞浆的近细胞膜部位.结论为颈动脉体中氧感受器细胞表达CBS和CSE,提示内源性H2S可能影响颈动脉体化学感受器功能.     

MTHFR和CBS基因多态性与低出生体重的关系研究

目的探讨母亲亚甲基四氢叶酸还原酶（MTHFR）基因C677T、胱硫醚β-合酶（CBS）基因T833C与子代低出生体重发生之间的关系。方法运用聚合酶链反应（PCR）-限制性片段长度多态性与PCR-扩增阻滞突变体系技术分别检测母亲的MTHFR、CBS基因型,对MTHFR基因型、CBS基因型、基因型的交互作用与低出生体重的关系进行分析。结果MTHFR基因突变型、CBS基因突变型对低出生体重影响无统计学意义（P〉0．05）,但MTHFR基因突变型与CBS基因突变型对低出生体重的影响存在交互作用（OR=3．155,95％CI：1．229—8．528）。结论母亲MTHFR基因C677T、CBS基因T833C,与子代低出生体重发生无关,但MTHFR基因突变型与CBS基因突变型存在交互作用,其能增加子代低出生体重发生的危险。     

反复热性惊厥过程中气体信号分子硫化氢对一氧化氮/一氧化氮合酶体系的影响

目的：探讨硫化氢（H₂S）对热性惊厥（FS）大鼠一氧化氮（NO）/一氧化氮合酶（NOS）体系表达的影响。方法:大鼠随机分为对照组、FS组、FS+NaHS组、FS+HA（hydroxylamine）组。采用热水浴诱导大鼠FS，隔日诱导1次，共10次。采用分光光度计法测定大鼠血浆中H₂S和NO含量；用原位杂交观察nNOS mRNA表达情况；用免疫组化方法观察NOS蛋白表达情况。结果:FS+NaHS组NO含量低于FS组，同时NOS表达也低于FS组；而FS+HA组NO含量高于FS组，同时NOS表达也强于FS组。结论:用H₂S外源性供体NaHS和胱硫醚-β-合成酶抑制剂HA的干预研究表明，反复热性惊厥过程中，H₂S的改变可影响NO/NOS体系的表达。     

胱硫醚-γ-裂解酶在三种微血管内皮细胞上的表达

目的鉴定微血管内皮细胞上是否表达生成硫化氢（H2s）的酶,为深入研究硫化氢的心血管作用提供新线索。方法原代培养大鼠心脏微血管内皮细胞（CMEC）,设计相应引物后用RT—PCR的方法检测胱硫醚-1-裂解酶（CSE）和胱硫醚-β-成酶（CBS）基因转录情况,进一步用兔抗大鼠CSE和CBS多克隆抗体对CMEC进行蛋白水平的免疫荧光染色。此外对另两种微血管内皮细胞株RF／6A和bEnd．3也检测了H2S生成酶的表达。结果三种微血管内皮细胞都扩增出CSE基因的特异条带,而CBS基因都未扩增出相应产物。CMEC的免疫荧光染色显示CSE抗体染色为阳性,CBS抗体染色为阴性。结论首次发现了微血管内皮细胞上存在CSE的表达,提示内皮细胞可以通过生成硫化氢调节心血管活动。     

MPP+对PC12细胞内源性H2S生成的影响

目的： 观察1-甲基4-苯基吡啶离子 (MPP+)对PC12细胞内源性硫化氢（H2S）生成的影响,以探讨MPP+损伤PC12细胞的新机制。方法: RT-PCR方法检测PC12细胞胱硫醚-β-合酶（CBS）mRNA 的表达;亚甲基蓝分光光度计法检测PC12细胞内源性H2S的含量及PC12细胞CBS活性;台盼蓝拒染色法观察PC12细胞的存活率。结果：MPP+ 可以抑制PC12细胞CBS的表达及其活性,减少内源性H2S的生成;MPP+可以明显地降低PC12细胞的存活率;H2S的供体硫氢化钠（NaHS）对MPP+诱导的PC12细胞损伤具有显著的拮抗作用。结论: MPP+能抑制CBS的表达和活性,减少内源性H2S生成,这可能与其损伤PC12细胞的机制有关。     

大鼠肢体缺血-再灌注后脑CBS表达的变化及意义

目的:观察肢体缺血-再灌注(IR)后脑组织内胱硫醚β-合酶(CBS)表达的变化及意义。方法:夹闭大鼠腹主动脉下段4 h、开放3~24 h复制肢体IR模型。采用逆转录多聚酶链反应检测脑内CBS mRNA表达的变化;Western blotting法检测脑内CBS蛋白的表达;采用全自动酶标仪测定脑组织中CBS活性和硫化氢含量;采用CBS抑制剂羟胺抑制CBS活性后,光镜观察脑组织的病理学变化。结果:肢体IR后脑组织CBS mRNA和蛋白表达水平明显高于假手术组,再灌12 h表达至峰值(均P0.01),再灌注至24 h与假手术组比较无显著差异(均P0.05)。肢体IR后脑组织中CBS活性及硫化氢浓度的变化与CBS mRNA和蛋白表达的变化一致;与假手术组相比,单纯缺血组上述各指标均没有明显变化(均P0.05);肢体IR后抑制CBS活性,IR组脑组织损伤加重。结论:肢体IR后,脑组织中CBS表达上调,所诱生的CBS对神经元具有保护效应。     

内皮型一氧化氮合酶基因与冠心病的研究进展

由血管内皮产生的一氧化氮（NO）是心血管系统中抗冠状动脉粥样硬化、血栓形成，维持正常血管舒缩反应必不可少的保护因子。一氧化氮合酶作为合成NO的关键酶，其基因发生变异，对NO的生成具有重要的影响。本文将对内皮型一氧化氮合酶基因多态性与冠心病的研究进展作一综述。     

Cancer gene therapy by adenovirus-mediated gene transfer

Cancer arises as a direct result of genetic mutations. It therefore stands to reason that cancer should be well suited for the correction through gene therapy. Recent advances in the understanding of the molecular pathogenesis of cancer and the rapid development of recombinant DNA technology have made cancer gene therapy feasible in the clinical setting. The current efforts for cancer gene therapy mainly focus on immunogene therapy, chemogene therapy, restoration of tumor suppressor gene function, and oncolytic virus therapy. Central to all these therapies is the development of efficient vectors for gene delivery--this remains a work in progress. These vectors can be classified as viral and non-viral vectors. This paper will concentrate on viral vectors because of their practical advantages over non-viral vectors. Of the viral vectors, by far the most important are the human adenoviruses as is reflected by the enormous data and literature accumulated by studies relating to animal tumor models and clinical trials. In this review, we examine the recent progress in adenovirus-mediated cancer gene therapy with regard to cytokine gene, tumor suppressor gene, chemogene, and oncolytic adenovirus. We also discuss the current limitations of the adenoviral vector system and how they may be circumvented in future developments relating to targeted gene delivery.     

Regulatable gene expression systems for gene therapy

It is feasible to restrict transgene expression to a tissue or region in need of therapy by using promoters that respond to focusable physical stimuli. The most extensively investigated promoters of this type are radiation-inducible promoters and heat shock protein gene promoters that can be activated by directed, transient heat. Temporal regulation of transgenes can be achieved by various two- or three-component gene switches that are triggered by an appropriate small molecule inducer. The most commonly considered gene switches that are reviewed herein are based on small molecule-responsive transactivators derived from bacterial tetracycline repressor, insect or mammalian steroid receptors, or mammalian FKBP12/FRAP. A new generation of gene switches combines a heat shock protein gene promoter and a small molecule-responsive gene switch and can provide for both spatial and temporal regulation of transgene activity.     

Cancer gene therapy through autonomous parvovirus--mediated gene transfer

Parvoviruses are small nuclear replicating DNA viruses. The rodent parvoviruses are usually weakly pathogenic in adult animals, bind to cell surface receptors which are fairly ubiquitously expressed on cells, and do not appear to integrate into host chromosomes during either lytic or persistent infection. The closely related rodent parvoviruses MVM, H-1 and LuIII efficiently infect human cell lines. Most interesting, malignant transformation of human and rodent cells was often found to correlate with a greater susceptibility to parvovirus-induced killing (oncolysis) and with an increase in the cellular capacity for amplifying and / or expressing the incoming parvoviral DNA. These and other interesting properties make these autonomous rodent parvoviruses and recombinant derivatives promising candidate antitumor vectors. Capsid replacement vectors have been produced from MVM or H-1 virus that carry transgenes encoding either therapeutic products (cytokines/chemokines, Apoptin, herpes simplex virus thymidine kinase) or marker proteins (green fluorescent protein, chloramphenicolacetyl transferase, luciferase). This review describes the current state of the art regarding the potential application of wild-type parvoviruses and derived vectors for the treatment of cancer. In particular, recent successes with the development of replication-competent virus-free vector stocks are discussed and results from pre-clinical studies using recombinant parvoviruses transducing various cytokines/chemokines are presented.     

Adenoviral vector-mediated gene transfer for human gene therapy

Human gene therapy promises to change the practice of medicine by treating the causes of disease rather than the symptoms. Since the first clinical trial made its debut ten years ago, there are over 400 approved protocols in the United States alone, most of which have failed to show convincing data of clinical efficacy. This setback is largely due to the lack of efficient and adequate gene transfer vehicles. With the recent progress in elucidating the molecular mechanisms of human diseases and the imminent arrival of the post genomic era, there are increasing numbers of therapeutic genes or targets that are available for gene therapy. Therefore, the urgency and need for efficacious gene therapies are greater than ever. Clearly, the current fundamental obstacle is to develop delivery vectors that exhibit high efficacy and specificity of gene transfer. Recombinant adenoviruses have provided a versatile system for gene expression studies and therapeutic applications. Of late, there has been a remarkable increase in adenoviral vector-based clinical trials. Recent endeavors in the development of recombinant adenoviral vectors have focused on modification of virus tropism, accommodation of larger genes, increase in stability and control of transgene expression, and down-modulation of host immune responses. These modifications and continued improvements in adenoviral vectors will provide a great opportunity for human gene therapy to live up to its enormous potential in the second decade.     

Genome-wide gene–gene interaction analysis for next-generation sequencing

The critical barrier in interaction analysis for next-generation sequencing (NGS) data is that the traditional pairwise interaction analysis that is suitable for common variants is difficult to apply to rare variants because of their prohibitive computational time, large number of tests and low power. The great challenges for successful detection of interactions with NGS data are (1) the demands in the paradigm of changes in interaction analysis; (2) severe multiple testing; and (3) heavy computations. To meet these challenges, we shift the paradigm of interaction analysis between two SNPs to interaction analysis between two genomic regions. In other words, we take a gene as a unit of analysis and use functional data analysis techniques as dimensional reduction tools to develop a novel statistic to collectively test interaction between all possible pairs of SNPs within two genome regions. By intensive simulations, we demonstrate that the functional logistic regression for interaction analysis has the correct type 1 error rates and higher power to detect interaction than the currently used methods. The proposed method was applied to a coronary artery disease dataset from the Wellcome Trust Case Control Consortium (WTCCC) study and the Framingham Heart Study (FHS) dataset, and the early-onset myocardial infarction (EOMI) exome sequence datasets with European origin from the NHLBI''s Exome Sequencing Project. We discovered that 6 of 27 pairs of significantly interacted genes in the FHS were replicated in the independent WTCCC study and 24 pairs of significantly interacted genes after applying Bonferroni correction in the EOMI study.     

Nuclear inheritance of a gene affecting mitochondrial gene expression

Due to a deficiency in mitochondrial protein synthesis, Chinese hamster lung (CHL) cell mutant Gal⁻ 32 does not grow in galactose or fructose. This report examines the nuclear or cytoplasmic inheritance of this single, recessive mutation. In a control experiment, fusion of Gal⁺TG^sTK⁻ cells with Gal⁻32TG^RTK⁺ cells resulted in tetraploid hybrids (as verified by karyotyping) that were selected in hypoxanthine/aminopterin/thymidine medium. The majority (2/3) of the control hybrids grew in galactose as expected since Gal⁻ is dominant over Gal⁻. Fusion of Rhodamine 6-G treated Gal⁺TG^STK⁻ cells with Gal⁻32TG^RTK⁺ cells resulted in Rhodamine 6-G-tetraploid hybrids that were selected in hypoxanthine/aminopterin/thymidine medium. The majority (7/12) of the Rhodamine 6-G-hybrids grew in galactose as expected for a nuclearly encoded gene considering that Rhodamine 6-G interferes with transmission of mtDNA but not nuclear DNA. Therefore, these results are compelling in their demonstration of the nuclear origin of the Gal⁻ 32 mutation.     

Immunoglobulin lambda gene rearrangement can precede kappa gene rearrangement

Immunoglobulin genes are generated during differentiation of B lymphocytes by joining gene segments. A mouse pre-B cell contains a functional immunoglobulin heavy-chain gene, but no light-chain gene. Although there is only one heavy-chain locus, there are two light-chain loci: kappa and lambda. It has been reported that kappa loci in the germ-line configuration are never (in man) or very rarely (in the mouse) present in cells with functionally rearranged lambda-chain genes. Two explanations have been proposed to explain this: (a) the ordered rearrangement theory, which postulates that light-chain gene rearrangement in the pre-B cell is first attempted at the kappa locus, and that only upon failure to produce a functional kappa chain is there an attempt to rearrange the lambda locus; and (b) the stochastic theory, which postulates that rearrangement at the lambda locus proceeds at a rate that is intrinsically much slower than that at the kappa locus. We show here that lambda-chain genes are generated whether or not the kappa locus has lost its germ-line arrangement, a result that is compatible only with the stochastic theory.     

Dual gene targeted multimeric siRNA for combinatorial gene silencing

Simultaneous silencing of multiple up-regulated genes is an attractive and viable strategy to treat many incurable diseases including cancer. Herein we report that multimerized siRNA conjugate composed of two different siRNA sequences in the same backbone shows more efficient inhibition of the two corresponding target genes at one time than physically mixed multimerized siRNA conjugates. Two model siRNAs against VEGF and GFP gene were chemically crosslinked via cleavable and noncleavable linkages for the preparation of dual gene targeted multimeric siRNA conjugates (DGT multi-siRNA). Cleavable DGT multi-siRNA with reducible disulfide linkages exhibited significantly higher gene silencing efficiencies at mRNA and protein expression levels than noncleavable DGT multi-siRNA, the physical mixture of naked siRNA, and that of single gene targeted multimeric siRNA (SGT multi-siRNA) with eliciting negligible immune response. DGT multi-siRNAs against two therapeutic siRNAs, anti-survivin and anti-bcl-2 targeted siRNA, also showed greatly enhanced apoptotic effect. This approach for concurrent suppression of combinatorial therapeutic target genes using cleavable multimeric siRNA structure can be potentially used for improved therapeutic efficacy.