A stage-specific protein factor binding to a CACCC motif in both human β-globin gene promoter and 5'-HS2region

The DNasel hypersensitive site 2 (HS2) of human β-globin locus control region (LCR) is required fOr the high level expression of human d-globin genes. In the present study, a stage-specific protein factor (LPF-β) was identified in the nuclear extract prepared from mouse fetal liver at d 18 of gestation, which could bind to the HS2 region of humanβ-globin LCRt We also found that the shift band of LPF-βfactor could be competed by humanβ-globin promoter. However, it couldn’t be competed by human E-globin promoter or by human Aβ-globin promoter. Furthermore, our data demonstrated that the binding-sequence of LPF-d factor is 5’CACACCCTA 3’,which is located at the HS2 region ofβ-LCR (from -10845 to -10853 bp) and humanβ-globin promoter (from -92 to -84 bp). We speculated that these regions containing the CACCC box in both the humallβ-globin promoter and HS2 might function as stage selector elements in the regulation of humanβd-globin switching and the LPF-βfactor might be a stage-specific protein factor involved in the regulation of humanβ-globin gene expression.

Identification of the development stage-specific factors in mouse fetal liver binding to the human β-globin gene promoter

In order to elucidate the molecular mechanisms of globin gene expression during embryonic development, the nuclear extracts from mouse hematopoietic tissue at different stages of development have been prepared. By using DNase I footprinting and gel mobility shift assays, the binding of protein factors in these extracts to the human βglobin promoter was analyzed. The differences in the binding patterns of protein factors during development were observed. An erythroid-specific and stage-specific nuclear protein in the nuclear extract from d 18 mouse fetal liver was identified, which can bind to the sequence (from -66bp to -90bp) of human β-globin promoter. We therefore speculate that the function of this cis-acting element may be similar to stage selector element (SSE) in chieken βA- promoter.

Screening and functional analysis of the long-range interaction elements ofβ-globin genes

Objective:Studies have shown thatβ-globin gene presents a selective expression transformation mechanism during development,and its upstream locus control region(LCR)regulates the expression pattern ofβ-globin gene family.To further explore the molecular network ofβ-globin gene expression regulation,other long-range regulatory elements that may be involved in the regulation ofβ-globin gene expression were screened and the dynamic regulation and transformation mechanism ofβ-globin gene was deeply studied.Methods:Promyelocytic cells were induced to differentiate by all-trans retinoic acid.β-globin gene promoter region and LCR were used as the target sites for circular chromosome conformational capture(4C)analysis.Through sequencing and regulatory element analysis,the sites interacting withβ-globin family loci were screened in the whole genome.Results:According to the results of 4C sequencing,the sites that interact with HBD promoter region and LCR were screened.Verified by chromosome conformational capture(3C),the results were consistent with those of sequencing.The functional analysis of regulatory elements by formaldehyde-assisted separation regulatory elements and Epiregio online website showed that the screening sites AC105129.4,AL354707.17,AC078785.22 and AC021646.35 were all potential regulatory elements involved inβ-globin gene.Conclusion:The interaction between 4C screening site and anchor site showed the complex spatial organization ofβ-globin family loci in the nucleus.

β-Globin Gene Cluster Haplotypes and Clinical Severity in Sickle Cell Anemia Patients in Southern Brazil

Hematopoietic stem cell transplantation(HSCT)has emerged as a curative strategy for sickle cell anemia(SCA);it is necessary to find markers of SCA clinical severity to spare those SCA patients whose clinical course is mild from the morbidity and mortality associated with HSCT. Haplotypes have been correlated with the severity of clinical manifestations in SCA patients, and fetal hemoglobin(HbF)and socioeconomic status(SeS)have also been described as negative factors. We studied these factors and their impact on clinical manifestations in a population of Southern Brazilian patients attending the Center for Sickle Cell Anemia at Hospital de Clínicas de Porto Alegre/RS, Brazil. Clinical severity was defined as two or more veno-occlusive episodes per year. The βS haplotypes were determined by PCR in 75 SCA patients. Among the 150 βS chromosomes analyzed, 99(66%)were identified as Bantu(Ban), 41(27%)asBenin(Ben), and 10(7%)as other haplotypes. Most patients in our sample(62.7%)belonged to lower SeS groups, precluding meaningful statistical analysis of SeS impact on clinical severity. There was no correlation between haplotypes or HbF level and SCA clinical severity. Gene polymorphisms and environmental issues have to be taken into consideration.

STM Studies on Tertiary Structure of a Negative Control Region (NCR1) of Human β-globin Gene

One of the crucial tasks of fundamental studies on modern biology is to explore the regulatory mechanisms of gene expression. Yet so far little has been known about the fine structural changes induced by the interaction between the DNA and the proteins. The major obstacles arise from the fact that it is not easy to crystallize the protein-DNA complex that is generally small in amount. This prevents researchers from gaining knowledge of the local structure with X-ray crystallography. On the other hand, the resolution of the electron microscope is not high enough to reveal structural details in nanometer scale.

Trans-acting factor binding to negative control region (NCR2) in 5' flanking sequence of human β-globin gene

Human β-globin gene family provides an ideal model for studying the expression and regulation of eukaryotic gene. The five transcriptional active genes arranged 5′ε-~Gγ-~Aγ-δ-β 3′ in the order that they are expressed during development. However, the molecular regulatory mechanism of the human globin gene expression remains to be defined. β-globin gene normally expressed in the adult bone marrow, but not in the embryonic stage, which

Interaction Between HMG Proteins (1+2) and the Negative Regulatory Region 1(NCR1) in the 5'-flanking Sequence of the Human β-globin Gene

The pattern of high mobility group proteins 1 and 2 (HMG1,2) interaction with the 5’-flanking sequence of the human β-globin gene has been analyzed by scanning tunnelling microscopy (STM). A 200 bp negative regulatory region in the 5’-flanking sequence of the human β-globin gene can be folded by HMG proteins 1 and 2 into a circular structure (diameter 70±6) with a linear tail which seems to be a left-handed double helix structure.

Binding of HMG Proteins to the 5'_Flanking Sequence of Human β-Globin Gene

Our previous studies have identified that there are at least three regulatory regions (two negative regions and one positive region) in the 5'-flanking sequence of human β-globin gene (-610 to +1 bp). The binding of HMG proteins to both negative regulatory regions was examined by the gel mobility shift and DNase I protection assays.In gel mobility shift assay,we observed that HMG proteins 1 and 2 could bind to both negative regulatory regions (NCR1 and NCR2).Using the gel shift competition assay,we identified that the binding proteins between the two regions are different from each other.DNase I protection analysis shows that HMG proteins 1 and 2 only bind to one site (between-560 and-533 bp) in NCR1.However,two protected regions can be detected in NCR2, one between-272 and-252 bp relative to the cap site, the other between-306 and-329 bp.We also observed that HMG proteins 14 and 17 could not bind to both negative regions, so it seems that HMG proteins 1 and 2 may play an important role in the regulation of β-globin expression through DNA-protein interaction or through protein-protein interaction.

Co-Inheritance of Beta &Delta-Globin Gene (HbYialousa) Mutations in an Iranian <i>β</i>-Thalassemia Carrier

Introduction: Beta-thalassemia is characterized by absence or reduced synthesis of the β-globin. Carriers of β-thalas- semia, typically have microcytic hypochromic anemia and elevated hemoglobin HbA2 and normal HbF level. On the other hand carriers of severe alpha-thalassemia also have similar CBC parameters to that of β-thalassemia with normal HbA2 level. Co-presence of mutations in the β-globin and delta-globin genes (point mutations or deletions) usually give normal HbA2 and elevated HbF level. We report a β-thal carrier with normal level of HbA2 and increased level of HbF who had a point mutation in CD39 on the beta-globin gene and a point mutation in CD27 on the δ-globin gene named Hb-Yialousa. Materials & Methods: An individual with low hematological indices, normal HbA2 and elevated HbF was referred to our center as routine premarital screening program. Mutations in the β-globin and δ-globin genes were screened using ARMS and sequencing methods. Results: The mutation in β- and δ-globin genes were identified as CD39 and CD27 (HbYialousa) respectively. No point mutation or deletion in α-globin gene was identified. Discussion: We showed that normal HBA2 with elevated HbF level is due to co-inheritance of delta-globin gene mutation with mutation in the β-globin gene. When screening for β-thalassemia, one has to either rule out presence of α-globin gene mutation of mutation in the delta-globin gene.

Hb Lepore-Boston-Washington型杂合缺失的诊断分析及文献复习

目的报道国内罕见的Hb Lepore-Boston-Washington杂合缺失病例并探讨毛细管电泳法和高效液相色谱法对其筛查时需要注意的问题,结合文献探讨该病的血液学特点和临床表型,以期为临床诊疗提供参考。方法采集外周血进行血液学分析。采用全自动毛细管电泳系统检测血红蛋白组分。应用PCR-流式荧光杂交法对常见的α-珠蛋白基因3种缺失、3种突变、β-珠蛋白基因17种突变进行检测。应用DNA测序分析HBB突变类型。结果该患者血液学表型为HGB:136 g/L、RBC:5.8×10^(12)/L、MCV:71.4 fL、MCH:23.4 pg。毛细管电泳结果显示:Hb A:84.7%;Hb A_(2):2.3%;Hb F:2.9%;Hb D:10.1%。DNA测序结果显示为Hb Lepore-Boston-Washington型杂合缺失。结论该病例为β珠蛋白基因第二内含子基因序列与δ珠蛋白基因序列发生了融合,不等交换重组位点发生在δ-基因87位与β-基因IVS-II nt 8之间。该类型突变在中国人群中属于罕见型,确诊需要依赖基因诊断。在地中海贫血(地贫)高危人群中,尤其是当其配偶疑似为β-地贫携带者时,要警惕此类地贫基因突变的筛查和检测,避免重型β-地贫患儿的出生。

QPCR技术检测孕妇外周血中胎儿DNA方法的建立

目的:建立QPCR技术检测孕妇外周血中胎儿DNA的方法,并探讨其方法的稳定性、灵敏性与可靠性。方法:通过prime5.0设计出SRY与β-globin的TapMan探针,并对其QPCR反应体系进行优化。结果:分别得到了SRY与β-globin的引物及探针的反应最适浓度比,建立了其最佳QPCR反应体系,并得出所需外周血的最少量。结论:成功建立了QPCR技术检测孕妇外周血中胎儿DNA的方法,该方法将可用于无创性相关产前诊断。

黄芪多糖诱导K562细胞γ-珠蛋白基因表达

目的探讨黄芪多糖(APS)对K562细胞γ-珠蛋白基因表达的诱导作用。方法以K562细胞为模型,以APS诱导的细胞为实验组,未加药细胞为空白对照,丁酸钠(NaB)处理的细胞为阳性对照,分别用联苯胺染色和RT-PCR分析联苯胺染色阳性率、Aγ-和Gγ-珠蛋白基因mRNA表达水平。结果(1)与空白对照组相比,300mg/LAPS诱导48h后联苯胺染色阳性率由(4.37±0.58)%升高至(15.67±1.80)%(P<0.05)。300mg/LAPS诱导K562细胞48h的联苯胺染色阳性细胞总数为(60.40±6.33)×102,与NaB组(42.02±16.42)×102相比差异有显著性意义(P<0.05)。(2)与空白对照组相比,300mg/LAPS诱导48hAγ和Gγ珠蛋白基因mRNA表达分别增加3.59±0.16倍和5.02±0.81倍(P=0.000)。结论APS可诱导K562细胞Aγ和Gγ珠蛋白基因mRNA表达增强,具有治疗β-珠蛋白生成障碍性贫血的潜能。

中药治疗对β-珠蛋白基因簇位点调控区高敏位点2与核蛋白结合作用的影响

目的 探讨中药益髓生血颗粒调控 β- 珠蛋白mRNA的分子机制。 方法 中药治疗 3个月 ,分别提取正常人和患者治疗前后骨髓有核细胞的核蛋白 ;采用凝胶滞后实验 ,将核蛋白与HS2位点序列探针结合后 ,经聚丙烯酰胺凝胶电泳分离 ,观察电泳图谱的改变。结果 患者治疗前的核蛋白与探针结合后的电泳速率与正常人存在明显差异 ,而患者治疗后核蛋白与探针结合后与正常人的电泳图谱接近。结论 中药治疗后影响 β- 珠蛋白基因簇位点调控区HS2位点与核蛋白因子GATA 1的结合作用 ,这可能是中药治疗本病的分子机制之一。

β地中海贫血一个特殊基因突变的家系分析

目的:对一个国人罕见的重型地中海贫血基因突变[CD41/42(-TCTT)·-90(C→T)]及其父母进行基因分析。方法:采用PCR/ASO探针杂交法检测中国人常见17种β-地贫基因突变,β-珠蛋白基因全长DNA克隆测序技术分析其突变基因型。结果:发现先证者父亲携带中国人常见基因突变CD41/42(-TCTT),母亲则为中国少见地中海贫血基因突变-90(C→T),而先证者则为密码子CD41/42(-TCTT)缺失突变复合-90(C→T)转录子突变。结论:-90 (C→T)在我国目前仅发现1例家系突变。

1例罕见β地中海贫血基因突变及其家系分析

目的鉴定1种罕见的β地中海贫血突变类型。方法血液学分析采用血细胞分析仪及全自动快速电泳分析系统;α珠蛋白常规突变检测采用Gap-PCR;β珠蛋白常规突变检测采用反向点杂交法;样品的基因突变及基因型用β珠蛋白基因全长测序技术确定。结果先证者具有典型的β地中海贫血临床特点和血液学特性,HbF为5.8%,其父母各项指标均正常。未发现先证者及其家庭成员有已知的α-/β-地中海贫血基因突变,测序发现先证者及其母亲均为CD2(CAT-CAC)杂合子,父亲为CAC纯合子;先证者有β珠蛋白exon1 CD27(GCC-GAC)突变,编码的氨基酸由丙氨酸变为天冬氨酸,未发现其父母有CD27突变。结论 CD27(GCC-GAC)突变是罕见的β珠蛋白基因点突变,有助于指导人群筛查、遗传咨询和临床诊断。

3种鲤科鱼β珠蛋白基因的比较研究

根据 β珠蛋白的N末端和C末端氨基酸序列的保守性设计 2 0bp长的简并引物 ,用RT PCR方法扩增并克隆了鲤、草鱼、鲫的 β珠蛋白基因cDNA。结果显示克隆 3种鱼的 β珠蛋白基因cDNA全长为 4 4 1bp。对它们所编码的氨基酸序列的比较可以看出虽然它们都属于鲤科但氨基酸的组成却有较大的差异。根据所克隆的cDNA分别设计特异引物用PCR方法克隆了 3种鱼的基因组DNA全长 ;从起始密码子到终止密码子的长度分别为鲤 6 6 7bp、草鱼6 2 9bp、鲫 6 6 7bp。 3种鱼中均含有 3个外显子和 2个内含子且内含子的插入位置相同。内含子的碱基序列差异很大。鲫与鲤内含子 1和 2的长度完全相同 ,而与草鱼的内含子长度则相差较大。

β-珠蛋白基因新突变导致的β-珠蛋白生成障碍性贫血

本研究对1例轻型β-珠蛋白生成障碍性贫血患者的β-珠蛋白基因进行序列分析,寻找基因的致病突变。提取患者外周血基因组DNA,扩增全长β-珠蛋白基因,然后对扩增产物进行DNA测序。结果显示,患者的β-珠蛋白基因1号内含子存在杂合IVS-I-129(A→G)突变。结论:IVS-I-129(A→G)突变为剪接突变使未成熟的β-珠蛋白基因mRNA产生剪接异常,导致其后的β-珠蛋白基因翻译错误。该突变为首次报道。

基因座控制区元件HS2、HS3对β-珠蛋白基因表达的调控

用增强型绿色荧光蛋白 (EGFP)为报道基因 ,通过构建不同的真核表达载体 ,并用脂质体转染法将其转染到K5 6 2及MEL细胞中 ,经流式细胞仪检测、半定量RT PCR及荧光倒置显微镜下观察荧光表达情况 ,以研究HS2、HS3、HS2 HS3及近侧元件在瞬时表达中对 β 珠蛋白基因启动子驱动下的EGFP表达调控情况。结果显示 ,3 2kb的HS2元件在K5 6 2及MEL细胞中均可增强 β 启动子活性 ,而 3kb的HS3仅在MEL细胞中有增强作用 。

中国牦牛β-珠蛋白基因的克隆和序列分析

根据黄牛β-珠蛋白基因的序列设计引物,扩增了中国牦牛的β-珠蛋白基因,并对其进行了克隆测序和氨基酸序列比较分析。结果显示,其与黄牛β-珠蛋白基因的同源性很高,达到97%以上;检测到中国牦牛β-珠蛋白基因的2个等位基因7β3A sn和1β35A sn,其中67号牦牛个体中检测到2个等位基因7β3A sn和1β35A sn,64号牦牛个体中检测到等位基因1β35A sn,1078号牦牛个体中检测到等位基因7β3A sn;等位基因1β35A sn是中国牦牛特有的一个等位基因,推测该等位基因编码的第135位氨基酸天冬酰胺,可能会降低牦牛血红蛋白的氧亲和力。

氯化高铁血红素诱导K562细胞中β-珠蛋白基因表达的研究

以绿色荧光蛋白（EGFP）基因为报道基因,构建了在β-珠蛋白启动子驱动及HS2元件调控下的重组表达载体HG,用脂质体转染法将其转染到K562细胞中,并用RT-PCR方法及流式细胞仪检测氯化高铁血红素（Hm）对K562细胞中β-珠蛋白基因表达及重组载体HG在K562细胞中瞬时表达的影响。结果显示:用30μmol/L Hm诱导K562细胞24、28及72h后,不仅其γ-珠蛋白mRNA水平升高,其β-珠蛋白mRNA水平也明显上升,而且这种诱导作用在诱导24、48h后比较明显;Hm还可增强重组表达载体HG在K562细胞中的瞬时表达。提示Hm诱导红系分化的机理可能与γ-β-珠蛋白基因的转换机制相关。