巨大舌-脐膨出综合征与基因组印记

基因组印记（genomic imprinting）是不符合孟德尔遗传定律的特殊遗传现象，巨大舌－脐膨出综合征（Beckwith-Wiedemann symdrone,BWS）的致病基因位于印记基因聚集的11p15.5，并且其发病与基因组印记的机理有关，印记基因p57^KIP2、IGF2／H19、LIT1在BWS时出现了变异或印记丢失（loss of imprinting,LOI）。作者对最近几年国内外在这方面的最新研究进展进行了综述，这些研究结果为最终阐述BWS的发病机理和基因组印记的遗传学特征与生物学意义提供了重要依据。     

转录因子MAZ对c1orf109基因转录表达调控的体外研究

目的:本文旨在研究转录因子Myc相关锌指蛋白(MAZ)在体外对人类1号染色体开放阅读框109(c1orf109)基因的转录表达调控。方法:体外条件下,采用凝胶电泳迁移实验筛选c1orf109基因启动子区MAZ的结合位点,并利用本室构建的由c1orf109启动子驱动的增强型绿色荧光蛋白报告载体与MAZ和转录因子特化蛋白1(Sp1)的表达质粒共转染He La细胞,24 h后,用激光共聚焦显微镜和流式细胞术检测c1orf109基因的转录表达情况。结果:c1orf109启动子区可与MAZ结合,且有与Sp1共享的结合位点;MAZ与Sp1皆可抑制c1orf109的转录表达,且Sp1的抑制作用大于MAZ(P0.05)。结论:MAZ与Sp1两个转录因子共同调控c1orf109基因在生理及病理条件的表达,且调控方向一致。这种冗余机制调控方式的存在提示该基因的精确表达调控对于细胞行使其生物学功能可能具有重要意义     

Noonan综合征患者PTPN11基因突变分析

目的 研究中国人Noonan综合征患者非受体型蛋白酪氨酸磷酸酯酶(protein-tyrosine phosphatase,nonreceptor-type 11,PTPN11)基因的突变.方法 收集遗传咨询门诊3例散发的Noonan综合征患者及其无症状父母,外周血提取基因组DNA,PCR产物直接测序法对患者PTPN11基因的全部15个编码区外显子及其邻接的内含子区域进行测序,检出突变后再对其父母的相应外显子区域进行测序,并通过限制性内切酶检测100名无亲缘关系的正常人相应碱基改变以排除多态性,利用网上ClustalW工具分析突变位点所在氨基酸在多个物种中的保守性.结果 在1例患者的第3外显子区域检出一杂合的c.181G＞A碱基取代,导致第61位的天冬氨酸改变为天冬酰胺(p.D61N),在其无症状父母和100名正常个体中无此突变;该位点在多个物种中高度保守.另外2例患者PTPN11基因的编码区未检到突变.结论 p.D61N突变在文献中已有报道,本例患者为新生突变.本研究进一步肯定了 p.D61N为Noonan综合征的致病突变,基因诊断的结果验证了该患者的临床诊断.另外两例Noonan综合征患者可能由其他基因的突变所致,反映了该病的遗传异质性.     

CYP11B2/CYP11B1融合基因致11β羟化酶缺乏症1例的遗传学分析

目的探讨1例CYP11B2/CYP11B1融合基因所致11β羟化酶缺乏症(11β-OHD)患儿的遗传学特征, 并为其父母提供产前遗传咨询。方法选取1例2020年8月24日就诊于河南省儿童医院内分泌科的患儿为研究对象。收集患儿临床资料, 采集患儿及其父母的外周血样, 对患儿进行全外显子组测序(WES), 对候选变异进行Sanger测序家系验证。用RT-PCR及Long-PCR确定患儿的融合基因。结果患儿为5岁男性, 第二性征发育提前, 生长加速, 诊断为21羟化酶缺乏症(21-OHD)。WES检测提示患儿CYP11B1基因存在杂合错义变异c.1385T>C(p.L462P),同时染色体8q24.3区存在37.02 kb的杂合缺失。根据美国医学遗传学与基因组学学会(ACMG)相关指南, 将c.1385T>C(p.L462P)评级为可能致病变异(PM2_Supporting+PP3_Moderate+PM3+PP4)。RT-PCR及Long-PCR联合检测结果提示为CYP11B1和CYP11B2基因重组, 形成CYP11B2 exon 1～...     

SOX11、miR-15b-5p在子宫内膜癌组织中表达及与患者临床病理特征的关系

目的 探讨转录因子性别决定区Y框蛋白11(SOX11)、微小RNA-15b-5p(miR-15b-5p)在子宫内膜癌组织中表达及与患者临床病理特征的关系。方法 选取2015年10月至2016年10月120例惠州市第一人民医院行手术治疗的子宫内膜癌患者癌组织及癌旁组织标本。采用免疫组化法检测组织中SOX11的表达,采用实时荧光定量PCR(qRT-PCR)法检测组织中SOX11mRNA、miR-15b-5p的表达水平;Pearson法分析子宫内膜癌组织中SOX11mRNA与miR-15b-5p表达水平相关性;Kaplan-Meier法分析SOX11和miR-15b-5p表达水平与子宫内膜癌患者5年生存率的关系;Cox回归分析影响子宫内膜癌患者总生存的危险因素。结果 子宫内膜癌组织中miR-15b-5p表达水平低于癌旁组织,SOX11蛋白阳性率、SOX11 mRNA表达水平高于癌旁组织（P<0.05）。SOX11蛋白及miR-15b-5p表达与患者淋巴结转移、FIGO分期、肌层浸润有关（P<0.05）。miR-15b-5p在SOX11的3’UTR存在相应的结合位点,子宫内膜癌组织...     

STK11基因突变在中国人Peutz—Jeghers综合征中的特征

目的 明确STK11基因在中国人Peutz-Jeghers(PJ）综合征的突变特征,为建立基因诊断奠定基础。方法 用DNA直接测序方法,对18个家系的PJ综合征患者STK11基因9个外显子进行研究。结果 在6个家系中发现6个命名基因产物发生改变的突变,推测最终导致产生截短型蛋白,结论 在中国人PJ综合征患者中STK11;基因突变的检出率为6／18,突变位点比较广泛,2／3集中在第1外显子,两代以上发病的家系突变率为66．7％,散发病例突变率为16．7％。     

遗传性FⅪ缺陷症一家系的F11基因新复合杂合变异分析

目的对1个复合杂合变异导致的遗传性凝血因子Ⅺ(coagulation factorⅪ,FⅪ)缺陷症家系进行表型和基因变异分析,探讨其发病的分子机制。方法检测先证者及其家系成员(共3代11人)的活化部分凝血活酶时间(activated partial thromboplastin time,APTT)、凝血酶原时间(prothrombin time,PT)、纤维蛋白原(fibrinogen,FIB)、血浆FⅪ活性(FⅪactivity,FⅪ∶C)及FⅪ抗原(FⅪantigen,FⅪ∶Ag)等指标以明确诊断;用Sanger测序法分析先证者F11基因的所有外显子及侧翼序列、5′和3′非翻译区及家系成员相应的变异位点区域,用反向测序予以证实。用PolyPhen-2和SIFT软件分析变异对蛋白质功能的影响;用Swiss-PdbViewer软件对变异位点进行蛋白模型和氨基酸相互作用分析。结果先证者和其姐姐APTT、FⅪ∶C、FⅪ∶Ag均明显异常,分别为73.0 s、10.0%、15.0%和87.1 s、2.0%、11.5%;其部分家系成员的APTT稍有延长,FⅪ∶C和FⅪ∶Ag也均有不同程度的下降。基因分析发现先证者及其姐姐F11基因第7外显子存在c.738G>A杂合变异(p.Trp228stop),第9外显子存在c.938G>T杂合变异(p.Ser295Ile);其父亲、妹妹、女儿均为p.Trp228stop的杂合子,而母亲、外甥则为p.Ser295Ile的杂合子。p.Ser295Ile变异PolyPhen-2评分结果为0.840分,预示此变异很可能是有害变异;SIFT评分结果为0.00分,预示此变异为有害变异,可影响蛋白质功能;模型分析显示p.Ser295Ile变异破坏了氨基酸间其中一个氢键的联系,使蛋白结构发生变化,不稳定性增加。结论该先证者的F11基因第7外显子存在c.738G>A(p.Trp228stop)杂合变异及第9外显子存在c.938G>T(p.Ser295Ile)杂合变异;p.Trp228stop遗传自父亲,p.Ser295Ile遗传自母亲,且与该家系FⅪ水平降低有关。     

胰腺癌转移相关基因C14orf166的真核表达及其蛋白相互作用的蛋白质组学筛选

目的旨在对胰腺癌转移相关基因C14orf166进行真核重组表达,并在此基础上结合蛋白质组学方法初步筛选其相互作用蛋白,为进一步研究C14orf166在肿瘤转移中的作用提供研究基础。方法构建人C14orf166的带双标签的真核表达载体pcDNA3.1-Flag-C14orf166-His,通过脂质体将其转染至人胚肾293T细胞。采用Ni-agrose进行His标签蛋白的pull-down纯化,分离C14orf166的蛋白结合复合体,对蛋白混合物进行SDS-PAGE分析,选择差异条带,进行MALDI-TOF-TOF质谱鉴定。结果在293T细胞中重组表达了C14orf166蛋白,对C14orf166蛋白复合体进行分离鉴定后,筛选出RS8、EFCB9和NRAP3个可能与C14orf166相互作用的蛋白。结论基因重组表达结合pull-down和蛋白质组学方法可以发现新的相互作用蛋白,为进一步了解C14orf166在肿瘤发病机制中的作用提供了新的线索。     

丙型肝炎双移位F蛋白抑制肝癌细胞p16、p21的表达

目的:探讨丙型肝炎双移位F(DF)蛋白对肝癌细胞抑癌基因p16、p21转录与表达的影响。方法:PCR扩增HCV1b型DF基因,构建pCDNA3.0/HCV-DF真核表达载体。再转染至肝癌细胞HepG2中,G418筛选稳定表达细胞株,Western blot检测p16、p21蛋白表达及半定量RT-PCR法检测p16、p21基因转录,并以pCDNA3.0空质粒作为阴性对照。结果:重组质粒pCDNA3.0/HCV-DF蛋白在HepG2细胞中稳定表达,pCDNA3.0/HCV-DF转染细胞中p16、p21 mR-NA转录水平和蛋白表达水平较空质粒转染的细胞明显下降。结论:HCV-DF蛋白能够抑制p16、p21表达,提示可能参与肝细胞癌变发生发展。     

E4orf4蛋白诱导肿瘤细胞凋亡的研究与应用

 腺病毒早期基因编码产物在病毒感染宿主细胞后，广泛参与对宿主细胞周期的调控，以利于病毒自身的复制及释放。其中，腺病毒基因早期转录区4第4开放读码框（Adenovirus early region 4 open reading frame 4，E4orf4）编码的E4orf4蛋白，近几年来逐渐引起人们的重视。E4orf4蛋白是由114个氨基酸组成的小分子蛋白，实验证明，通过基因转染在哺乳动物细胞内表达的E4orf4蛋白在细胞质、细胞骨架和细胞核均有聚集。E4orf4蛋白作为一种多功能蛋白，可以下调病毒诱导的细胞信号传导、在转录和转录后水平调节宿主细胞及病毒蛋白的表达并诱导不依赖于p53的细胞凋亡。目前，对E4orf4蛋白诱导细胞凋亡的作用机制的研究，主要有3个方面：①通过结合和激活蛋白磷酸酶2A（protein phosphatase 2 A，PP2A）来引起细胞凋亡；②通过对Src家族激酶的调节激活胞质凋亡信号；③对肿瘤细胞选择性诱导凋亡的作用。本文主要对E4orf4蛋白诱导细胞凋亡作用的研究进展，以及这种诱导作用对肿瘤细胞的特异性进行综述。......     

Microdissection of chromosome band 11p15.5: characterization of probes mapping distal to the HBBC locus.

Both cytogenetic and molecular genetic analyses of the 11p15.5 subband suggest it may contain loci important in the genesis of a wide variety of tumors such as rhabdomyosarcomas and Wilms' tumors as well as the congenital tumors associated with the Beckwith-Wiedemann syndrome. As a first step in further defining the involvement of this chromosomal region in these various maladies, a library was constructed from the specific microdissection of chromosomal fragments representing 11p15.5-pter. Of 98 microclones analyzed, 31 identified single copy human DNA sequences, 21 of which mapped to 11p15.5 while 10 mapped proximal to the HBBC locus. Five of the 11p15.5-positioned microprobes detected restriction fragment length polymorphisms at their homologous genomic loci for various enzymes. These microprobes are now being utilized in several ways in order to address the underlying basis of the Beckwith-Wiedemann syndrome and its associated tumors.     

Two distinct tumor suppressor loci within chromosome 11p15 implicated in breast cancer progression and metastasis

Chromosome 11p15 has attracted considerable attention because of the biological importance of this region to human disease. Apart from being an important tumor suppressor locus showing loss of heterozygosity (LOH) in several adult and childhood cancers, 11p15 has been shown by linkage analysis to harbor the gene(s) for the Beckwith-Wiedemann syndrome. Furthermore, the clustering of known imprinted genes in the 11p15.5 region suggests that the target gene may also be imprinted. However, positional cloning efforts to identify the target genes have been complicated by the large size (approximately 10 Mb) and complexity of LOH at 11p15. Here, we have analyzed 94 matched normal and breast tumor samples using 17 polymorphic markers that map to 11p15.5-15.4. We have defined precisely the location of a breast tumor suppressor gene between the markers D11S1318 and D11S4088 (approximately 500 kb) within 11p15.5. LOH at this region occurred in approximately 35-45% of breast tumors analyzed. In addition, we have fine-mapped a second, critical region of LOH, that spans the markers D11S1338-D11S1323 (approximately 336 kb) at 11p15.5-p15.4, that is lost in approximately 55-60% of breast tumors. There is a striking correlation between the loss of the two 11p loci and the clinical and histopathological features of breast tumors. LOH at region 1 correlated significantly (P = 0.016) with early events in malignancy and invasiveness. In contrast, the loss of the more proximal region 2, is highly predictive (P = 0.012) of aggressive metastatic disease. Thus, two distinct tumor suppressor loci on chromosome 11p15 may contribute to tumor progression and metastasis in breast cancer. The fine mapping of this intriguing chromosomal region should facilitate the cloning of the target genes and provide critical clues to understanding the mechanisms that contribute to the evolution of adult and childhood cancers.      

Three non-overlapping regions of chromosome arm 11p allele loss identified in infantile tumors of adrenal and liver

Tumor and constitutional chromosome arm 11p genotypes were compared in 6 hepatoblastoma (HB) patients and 2 adrenal adenoma (AA) patients, with one HB patient and both AA patients displaying clinical features associated with the Beckwith-Wiedemann syndrome (BWS). Using up to 14 chromosome 11 polymorphic markers, loss of constitutional heterozygosity (LOH) was demonstrated in both AA patients and in 4 of 6 HB patients. This identified three distinct and non-overlapping regions of 11p within which LOH occurred, which were defined as lying distal to the gamma-globin locus (11p15.5), proximal to the gamma-globin locus but distal to 11p13 (LOH being detected at 11p15.1), and restricted to the 11p13 region. Specific LOH within each 11p15 region was observed in HB, and this represents the first demonstration by a single study of LOH clearly affecting separate regions of chromosome band 11p15 in a particular tumor type. One AA showed LOH restricted to 11p13 loci, implicating the involvement of the WT1 gene. The second AA patient presented with genitourinary abnormalities and we therefore examined sequences coding for 3 zinc finger domains of WT1 in both AAs. No point mutations were identified in sequence from either patient. Nonetheless our results indicate that 3 separate 11p loci may be significant in the development of tumors which arise in association with BWS. © 1993 Wiley-Liss, Inc.     

Beckwith-Wiedemann syndrome due to 11p15.5 paternal duplication associated with Klinefelter syndrome and a "de novo" pericentric inversion of chromosome Y

We report on an infant who had been prenatally diagnosed with Klinefelter syndrome associated with a "de novo" pericentric inversion of the Y chromosome. A re-evaluation at 3 years of age suggested that he was also affected by Beckwith-Wiedemann syndrome (BWS). Karyotype was repeated and fluorescence in situ hybridisation (FISH) analysis revealed trisomy for 11p15.5-->11pter and a distal monosomy 18q (18q23-->qter). Parental cytogenetic studies showed that the father carried a balanced cryptic translocation between chromosomes 11p and 18q. Furthermore, the child had an extra X chromosome and a "de novo" structural abnormality of chromosome Y. Thus, his karyotype was 47,XX, inv (Y) (p11.2 q11.23), der(18) t (11;18) (p15.5;q23) pat. ish der(18) (D11S2071+, D18S1390-). Two markers on the X chromosome showed that the extra X of the child was paternally inherited. No deletions were observed on the structurally abnormal Y chromosome from any of the microsatellites studied. Clinical findings of patients with BWS due to partial trisomy 11p reveal that there is a distinct pattern of dysmorphic features associated with an increased incidence of mental retardation when comparing patients with normal chromosomes. This fact reinforces that FISH study have to be performed in all BWS patients, specially in those with mental retardation since small rearrangements cannot be detected by conventional cytogenetic techniques.     

A constitutional bws-related t(11;16) chromosome translocation occurring in the same region of chromosome 16 implicated in wilms' tumors

Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth disorder with a varying spectrum of clinical manifestations including macroglossia, omphalocele, hemihypertrophy, and a predisposition to a subset of embryonal tumors, most frequently Wilms' tumor (WT). A variety of cytogenetic, genetic linkage, and molecular mapping data implicate a gene or genes on chromosome band 11p15.5 in BWS and its related tumors. However, some families with BWS do not show linkage to 11p15, and other alterations have been found in Wilms' tumors as well. One such alteration is loss of heterozygosity (LOH) for chromosome arm 16q. Here we have analyzed a balanced t(11;16)(p15;q13) chromosomal translocation associated with the BWS phenotype and mapped the breakpoint positions for both chromosomes 11 and 16 by using somatic cell hybrids and polymorphic markers. The chromosome 11 breakpoint was found to lie distal to the D11S12 locus, but proximal to TH on 11p15.5, a region shown previously to contain other BWS-related chromosomal events. The chromosome 16 breakpoint was distal to D16S290 in 16q13, but proximal to loci D16S265, D16S267, and D16S164 in band 16q21. This area encompasses the region of LOH occurring through mitotic recombination in sporadic WT. This raises interesting possibilities for the genetic and epigenetic involvement of both chromosomal regions (11p15 and 16q13) in the pathogenesis of BWS and Wilms' tumor.     

Parental allele specific methylation of the human insulin-like growth factor II gene and Beckwith-Wiedemann syndrome.

In an attempt to elucidate the role of methylation in parental imprinting at the IGF-II gene locus, for which imprinting has already been described in the mouse, we undertook an allele specific methylation study of the human IGF-II gene (mapped to 11p15.5) in a control population and in patients with Beckwith-Wiedemann syndrome. In control leucocyte DNA (16 unrelated adults and eight families), the maternal allele of the IGF-II gene was specifically hypomethylated, whereas no such allele specific methylation was found for either the insulin or the calcitonin genes which are located in 11p15.5 and 11p15.1, respectively. Furthermore, the IGF-II gene specific hypomethylation was localised on the 5' portion of exon 9. In the patients with Beckwith-Wiedemann syndrome in which the IGF-II gene is thought to be involved and where paternal isodisomy has been described, hypomethylation of the maternal allele was conserved in leucocyte DNA, but abnormal methylation was detected in malformed tissues where the paternal allele was also demethylated. Some specific mechanism linked to methylation therefore seems to be involved in the pathogenesis of Beckwith-Wiedemann syndrome.     

Excess functional copy of allele at chromosomal region 11p15 may cause Widemann-Beckwith (EMG) syndrome

Wiedemann-Beckwith syndrome (WBS) is a genetic disorder with overgrowth and predisposition to Wilms' tumor. The putative locus of the gene responsible for this syndrome is assigned to chromosome region 11p15.5, and genomic imprinting in this region has been proposed: the paternally derived gene(s) at 11p15.5 is selectively expressed, while the maternally transmitted gene(s) is inactive. We examined 18 patients for the parental origin of their 11p15 regions. DNA polymorphism analyses using 6 loci on chromosome 11 showed that 2 patients with duplications of 11p15 regions from their respective fathers and one from the mother, indicating the transmission of an excessive paternal gene at 11p15 to each patient. Our results, together with the previous findings in karyotypically normal or abnormal patients and in overgrowth mouse experiments, are consistent with imprinting hypothesis that overexpression of paternally derived gene(s) at 11p15.5, probably the human insulin-like growth factor II (IGF-II) gene, may cause the phenotype. Total constitutional uniparental paternal disomy (UPD) or segmental UPD for the 6 loci examined of chromosome 11 was not observed in our 12 sporadic patients. In order to explain completely the inheritance of this syndrome in patients with various chromosomal constitutions, we propose an alternative imprinting mechanism involving the other locus that may be paternally imprinted and may suppress the expression of this gene. © 1994 Wiley-Liss, Inc.     

Genomic imprinting of human p57KIP2 and its reduced expression in Wilms' tumors

p57KIP2 is a potent tight-binding inhibitor of several G1 cyclin complexes, and is a negative regulator of cell proliferation. The gene encoding human p57KIP2 is located on chromosome 11p15.5, a region implicated in both sporadic cancers and Beckwith-Wiedemann syndrome (BWS), a cancer syndrome, making it a tumor suppressor candidate. Several types of childhood tumors including Wilms' tumor, adrenocortical carcinoma and rhabdomyosarcoma display a specific loss of maternal 11p15 alleles, suggesting that genomic imprinting plays an important part. Genetic analysis of the familial BWS has indicated maternal carriers and suggested a role in genomic imprinting. Previously, we demonstrated that p57KIP2 is imprinted in the mouse. Here we describe the genomic imprinting of human p57KIP2 and the reduction of its expression in Wilms' tumors. High resolution mapping locates p57KIP2 in the region responsible for both tumor suppressivity and BWS.