转录因子婆罗双树样基因4(SALL4)研究进展

婆罗双树样基因4(sal-like4,SALL4)位于染色体20q13.13-13.2,编码蛋白是1个含有8个锌指基序的转录因子。近年的研究表明,SALL4基因在胚胎早期发育、器官形成以及胚胎干细胞增殖和多能性维持方面发挥着重要作用。SALL4基因不同位点的杂合子突变产生无义突变或移框突变,导致终止密码子提前出现,其与常染色体显性遗传病Okihiro综合征、雅-肾-眼综合征、IVIC综合征发病相关。在生殖细胞肿瘤、肝样胃癌、急性髓系白血病和前驱B淋巴细胞白血病/淋巴瘤中SALL4表达水平增高。本文就SALL4的结构、功能及其与相关疾病的关系进行综述。     

维生素D受体多态性与肠道CYP3A4表达:维生素D受体基因突变在人群中分布有差异吗?

背景:研究表明,维生素D受体可以诱导肠道中CYP3A4的转录表达,维生素D受体基因的突变将涉及到它自身所翻译的蛋白改变,而其相应的下游靶基因的转录表达或功能亦可能会发生改变.目的:确定HT-29肠细胞中维生素D受体Fokl突变在对其下游靶基因CYP3A4转录的影响.方法:取肝胆管结石患者术中切除的肝脏组织,构建重组真核表达载体pcDNA3.1(-)B-myc/his h维生素D受体(野生型和Fok1突变型),利用瞬时转染技术和双荧光素酶报告基因分析系统在体外HT-29细胞中检测转染不同载体后的细胞在给予不同浓度(1,10,100 nmol/L)的药物1,25(OH)2VD3(维生素D受体的天然配体)处理后,CYP3A4的转录表达情况.结果与结论:将野生型和突变型维生素D受体质粒共转染于HT-29细胞中,在1,25(OH)2VD3孵育24 h后,3个浓度代表CYP3A4mRNA转录水平的荧光素酶活性数值分别与溶煤对照组和空载体对照组相比差异具有显著性意义(P<0.05),且转染Fok1突变型的细胞荧光素酶活性数值稍大于转染野生型的细胞荧光素酶活性数值,但两者间差异无显著性意义(P>0.05).维生素D受体Fok Ⅰ突变体对其下游靶基因的转录表达与维生素D受体野生型没有差异.提示在肠细胞中,维生素D通过维生素D受体诱导CYP3A4转录表达,但是维生素D受体Fokl突变体对CYP3A4的转录与野生型相比差异无显著性意义.     

维生素D受体基因多态性与乳腺癌关系

已有大量研究证实,维生素D受体(Vitamin D receptor)能调节细胞增殖、代谢等多种生理过程,与糖尿病、高血压、乳腺癌等多种疾病的发生密切相关。维生素D受体除通过炎症因子的调节影响乳腺癌的进程外,其基因多态性会导致维生素D受体蛋白质功能的改变从而影响乳腺癌的发病风险。本文将对维生素D受体基因多态性与乳腺癌发生机制的关系进行综述。     

DNA聚合酶基因在共济失调毛细血管扩张症家系突变状态的研究

目的通过对一个基因损伤修复缺陷性疾病共济失调毛细血管扩张症(AT)家系DNA聚合酶基因突变分析,初步观察其稳定突变位点,为上述疾病易感基因风险突变位点的进一步确定奠定基础。方法对该家系先征者DNA聚合酶基因家族,polA、polB、polD1、polD2、polE1、polG测序,检测突变位点,分析并筛选有意义突变位点;对该家系成员在先征者有意义突变区域直接测序。结果 AT家系患儿DNA聚合酶基因无外显子突变,但在polE1 12p24.3 132696619AG,该突变位置处于该基因的3′UTR下游;家系中患儿的母亲、外祖母及舅舅发生12p24.3 132696619AG。结论 AT家系先证者在DNA聚合酶基因外显子没有检测到突变位点,但在3′UTR位置检测到一个有意义突变位点,在家系成员中亦有突变,其可能为AT疾病的稳定突变位点。     

维生素D缺乏和心血管疾病危险因素关系的研究进展

维生素D与心血管健康和疾病的关系越来越引起人们的重视,研究发现维生素D缺乏与心血管疾病的危险因素,如高血压、内皮功能异常、胰岛素抵抗、代谢综合征和糖尿病等相关,从而增加冠状动脉性疾病的危险性。维生素D与分布于心血管细胞上的维生素D受体结合,调节与心血管疾病过程相关的基因的表达。维生素D低水平状态通过激活促炎症瀑布导致内皮功能异常和动脉壁的硬度增加而增加心血管疾病的危险性。     

核受体FXR与胆汁酸代谢及相关疾病的关系

近年来一种称为代谢综合征的疾病群,包括高脂血症、胰岛素抵抗等逐渐成为危害人类健康的重大疾病.现其发病机制不明,因而对代谢综合征的治疗还缺乏有效的手段.最近的研究发现,某些核受体转录因子可通过对其相应靶基因的调控参与多种代谢通路的调节,其中法尼基衍生物X受体(FXR)的研究进展为多种代谢性疾病的治疗提供了新的思路和方向.     

基因多态性与2型糖尿病

2型糖尿病(T2D)是一种由遗传和环境因素共同作用的多基因位点疾病。迄今为止,已有多个基因多态性位点被发现与T2D密切相关。最近发现的与T2D密切相关的基因包括胰岛素受体底物1(insulin receptor substrate 1,IRS-1)、蛋白酪氨酸磷酸酶受体类型D(protein tyrosine phosphataes,receptor type,PTPRD)、泛素结合酶E2E2(ubiq-uitin-conjugating enzyme E2E2,UBE2E2)。1 IRS-1IRS-1基因位     

玉溪市某特殊教育学校131例青少年耳聋患者耳聋基因分析

目的分析玉溪市某特殊学校131例青少年非综合性耳聋患者的常见耳聋基因突变位点,为检测和治疗耳聋提供病因学依据。方法采用基因芯片技术检测玉溪市某聋哑学校131例非综合征性耳聋患者4个基因的9个位点:包括GJB2基因c.35del G、c.176_191del 6、c.235del C、c.299del AT;GJB3基因c.538CT;SLC26A4基因c.2168AG、c.IVS7-2AG;线粒体12SrRNA基因的m.1494CT、m.1555AG位点。结果携带遗传性耳聋相关突变基因的患者27例(28.3%,27/131)。其中,GJB2突变者20例,包括c.176_191del 6突变1例,为汉族;c.235del C突变17例,其中10例为汉族,2例为彝族,5例为哈尼族;c.299del AT突变2例,均为汉族。SLC26A4突变者8例,均为汉族,包括c.2168AG突变4例,c.IVS7-2AG突变4例;线粒体12SrRNA基因m.1555AG位点突变2例,均为汉族,其他民族中未发现4个基因9个位点的突变对象。结论青少年非综合征性耳聋患者以GJB2基因和SLC26A4基因为最主要的致病基因,其中c.235del C突变为最常见突变位点,其次为c.IVS7-2AG和c.2168AG突变。     

乙酰化肌细胞增强因子2D调节Nur77基因对T细胞凋亡的影响

目的:Nur77是介导T细胞凋亡的重要基因,它的激活需要第二信使钙离子,而Nur77基因启动子的钙反应元件是转录因子肌细胞增强因子2D的结合位点.探讨在Nur77诱导T细胞凋亡过程中肌细胞增强因子2D是否可以被乙酰化,以及通过调节Nur77基因乙酰化对T细胞凋亡的影响.方法:实验于2006-11/2007-09在吉林大学第一医院血液肿瘤科完成.①材料:大肠杆菌DH5α、pcDNA3质粒由吉林大学第一医院中心研究室保存.pET32M质粒、Flag-p300质粒、pSilencerTM-p300 RNAi质粒由香港科技大学Zhengguo Wu博士馈赠.NFATp质粒由哈佛大学Yun Chen博士馈赠.Jurkat细胞由吉林大学第一医院血液肿瘤科提供.②实验方法:PCR法产生全长的Nur77和依赖Nur77的荧光报告基因被亚克隆到pcDNA质粒中,产生的肌细胞增强因子2D(1-514)、(1-121)、(1-300)、(301-514)各片段以及含4个赖氨酸(K245/K250/K267/K279)位点突变为精氨酸位点的肌细胞增强因子2D (4KR)突变体亚克隆到pcDNA后在氨基端含有Flag抗原簇,于细菌表达载体上进行质粒构建,验证正确的质粒使用脂质体DMRIE-C进行转染.③实验评估:将Nur77荧光报告基因与肌细胞增强因子2D、p300、NFATp共转染到Jurkat细胞中,检测p300对肌细胞增强因子2D促进Nur77转录的影响.免疫沉淀法检测内源性肌细胞增强因子2D是否能够被乙酰化,以及阻滞p300表达后是否影响其乙酰化.体外乙酰化法检测肌细胞增强因子2D的乙酰化位点.荧光素报告分析法检测肌细胞增强因子2D的乙酰化功能缺失对Nur77转录活性的影响.采用流式细胞仪检测其功能缺陷对Nur77诱导T细胞凋亡的影响.结果:①肌细胞增强因子2D与NFATp的二聚体虽然不能促进Nur77的转录,但p300、NFAT、肌细胞增强因子2D的三聚体却能明显促进Nur77的转录,且p300与肌细胞增强因子2D的二聚体也明显促进Nur77的转录.②PMA/Iono活化钙信号传导通路后,肌细胞增强因子2D被乙酰化.当内源性p300RNAi后,p300的表达被阻滞时,肌细胞增强因子2D的乙酰化水平显著下降.③K245,K250,K267,K279氨基酸同时突变可以使肌细胞增强因子2D乙酰化程度大部分丧失,说明在体外这4个赖氨酸位点是肌细胞增强因子2D的主要乙酰化位点.④与空载体比较,转染乙酰化缺陷的肌细胞增强因子2D可使Nur77转录功能提高2.48倍;与转染野生型的肌细胞增强因子2D比较,转染乙酰化缺陷的肌细胞增强因子2D能降低Nur77基因70.4%的转录功能.⑤与空载体比较,Nur77表达能够促进T细胞凋亡,早晚期凋亡之和从4.3%提高至16.3%;共表达野生型肌细胞增强因子2D与Nur77能够进一步促进T细胞的凋亡,早晚期凋亡之和从16.3%提高到31.0%;但肌细胞增强因子2D乙酰化功能缺失的突变体肌细胞增强因子2D明显降低Nur77介导的T细胞凋亡,早晚期凋亡之和从16.3%降低到9.2%.结论:p300对肌细胞增强因子2D促进Nur77的转录起主要作用.肌细胞增强因子2D在Nur77诱导的T细胞凋亡过程中可以被乙酰化,乙酰化的肌细胞增强因子2D通过上调Nur77基因的转录来促进T细胞凋亡.     

A frequent polymorphism in the coding exon of the human cannabinoid receptor (CNR1) gene.

The central cannabinoid receptor (CB1) mediates the pharmacological activities of cannabis, the endogenous agonist anandamide and several synthetic agonists. The cloning of the human cannabinoid receptor (CNR1) gene facilitates molecular genetic studies in disorders like Gilles de la Tourette syndrome (GTS), obsessive compulsive disorder (OCD), Parkinsons disease, Alzheimers disease or other neuro psychiatric or neurological diseases, which may be predisposed or influenced by mutations or variants in the CNR1 gene. We detected a frequent silent mutation (1359G-->A) in codon 453 (Thr) of the CNR1 gene that turned out to be a common polymorphism in the German population. Allele frequencies of this polymorphism are 0.76 and 0.24, respectively. We developed a simple and rapid polymerase chain reaction (PCR)-based assay by artificial creation of a Msp I restriction site in amplified wild-type DNA (G-allele), which is destroyed by the silent mutation (A-allele). The intragenic CNR1 polymorphism 1359(G/A) should be useful for association studies in neuro psychiatric disorders which may be related to anandamide metabolism disturbances.     

Fibronectin receptor on polymorphonuclear leukocytes in families of Ehlers-Danlos syndrome and other hereditary connective tissue diseases

Studies were made on the fibronectin receptor on polymorphonuclear leukocytes of patients with hereditary connective tissue diseases and of healthy members of their families. In four patients with Ehlers-Danlos syndrome type II (family E) and type VI (family M), the maximum number of binding sites (Bmax) of fibronectin receptor was significantly decreased to 2.2 to 2.9 x 10(3) sites/cell (normal range 6.3 +/- 1.5 x 10(3) sites/cell). The Bmax values of healthy members of their families were normal or moderately decreased to 3.8 to 5.1 x 10(3) sites/cell. In a patient with osteogenesis imperfecta type III (family K) the Bmax was significantly decreased to 1.1 x 10(3) sites/cell, but healthy members of his family had normal Bmax values. In a patient with Marfan syndrome (family A) the Bmax was decreased to 4.3 x 10(3) sites/cell. The dissociation constant of the fibronectin receptor was normal in all subjects examined. Some healthy members of the families of the patients with Ehlers-Danlos syndrome had moderately decreased Bmax values, suggesting that they are carriers of an abnormal gene causing this disorder. These data suggest that fibronectin receptor is closely related to the pathogenesis of hereditary connective tissue diseases.     

A novel nonsense variant in MED12 associated with malformations in a female fetus

Pathogenic variants in the MED12 gene located on the X‐chromosome have primarily been reported in males with Lujan‐Fryns syndrome, Ohdo syndrome and the Opits‐Kaveggia syndrome. However, earlier reports of female patients and female mice suggest that MED12 deficiency causes severe malformations. We report a novel example of a MED12 de novo nonsense variant in a female fetus with severe malformations identified by trio‐exome sequencing. This finding further expands the clinical spectrum of MED12‐related disorders, which is vital for prenatal diagnosis and genetic counselling of couples.     

Digenic mutations account for variable phenotypes in idiopathic hypogonadotropic hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) due to defects of gonadotropin-releasing hormone (GnRH) secretion and/or action is a developmental disorder of sexual maturation. To date, several single-gene defects have been implicated in the pathogenesis of IHH. However, significant inter- and intrafamilial variability and apparent incomplete penetrance in familial cases of IHH are difficult to reconcile with the model of a single-gene defect. We therefore hypothesized that mutations at different IHH loci interact in some families to modify their phenotypes. To address this issue, we studied 2 families, one with Kallmann syndrome (IHH and anosmia) and another with normosmic IHH, in which a single-gene defect had been identified: a heterozygous FGF receptor 1 (FGFR1) mutation in pedigree 1 and a compound heterozygous gonadotropin-releasing hormone receptor (GNRHR) mutation in pedigree 2, both of which varied markedly in expressivity within and across families. Further candidate gene screening revealed a second heterozygous deletion in the nasal embryonic LHRH factor (NELF) gene in pedigree 1 and an additional heterozygous FGFR1 mutation in pedigree 2 that accounted for the considerable phenotypic variability. Therefore, 2 different gene defects can synergize to produce a more severe phenotype in IHH families than either alone. This genetic model could account for some phenotypic heterogeneity seen in GnRH deficiency.     

The genetic disorders responsible for sudden cardiac death

Sudden cardiac death is defined as an unpredictable death within 24 hours. It is estimated to occur with a frequency of more than 50,000 per year in Japan. The inherited arrhythmogenic diseases associated with the transmembranous ionic channels, anchoring proteins or intracellular calcium regulating proteins are thought to be responsible for sudden cardiac death in infants, children, and young adults who have structurally normal hearts. Recent genetic analyses have identified congenital diseases such as the long-QT syndrome (LQTS), the Jervell and Lange-Nielsen syndrome (JLNS), the Brugada syndrome (BrS), the short-QT syndrome (SQTS), the arrhythmogenic right ventricular cardiomyopathy type 2 (ARVC2), and the catecholamine-induced polymorphic ventricular tachycardia (CPVT) /familial polymorphic ventricular tachycardia (FPVT). Loss of function in the slow component of the delayed rectifier potassium current (I(Ks)) channels (KCNQ1, KCNE1), the rapid component of the potassium current (I(Kr)) channels (KCNH2, KCNE2) and the inward rectifier potassium current (I(Kl), Kir2.1) channel (KCNJ2) is linked to the LQTSs (type 1, 2, 5, 6, and 7 (Andersen syndrome)) and the JLNSs (type 1 and 2). Changes of function in the alpha-subunit of cardiac sodium channels (SCN5A) is also linked to the LQTS type 3 and the BrS. A mutation in the ankyrin-B, anchoring proteins, has been identified as cause of the LQTS type 4. The SQTS is caused by gain of function in the KCNH2. Further, the missense mutations in the gene encoding ryanodine receptor 2 (RyR2) or calsequestrin 2 (CASQ2) that regulate intra-cardiac calcium handling is possibly implicated in the ARVC2 and the CPVT/FPVT. Herein, we present a review of the literature regarding the genetic mechanisms of the inherited arrhythmogenic diseases.