U7 snRNA-mediated correction of aberrant splicing caused by activation of cryptic splice sites

A considerable fraction of mutations associated with hereditary disorders and cancers affect splicing. Some of them cause exon skipping or the inclusion of an additional exon, whereas others lead to the inclusion of intronic sequences or deletion of exonic sequences through the activation of cryptic splice sites. We focused on the latter cases and have designed a series of vectors that express modified U7 small nuclear RNAs (snRNAs) containing a sequence antisense to the cryptic splice site. Three cases of such mutation were investigated in this study. In two of them, which occurred in the PTCH1 and BRCA1 genes, canonical splice donor sites had been partially impaired by mutations that activated nearby intronic cryptic splice donor sites. Another mutation found in exonic region in CYP11A created a novel splice donor site. Transient expression of the engineered U7 snRNAs in HeLa cells restored correct splicing in a sequence-specific and dose-dependent manner in the former two cases. In contrast, the third case, in which the cryptic splice donor site in the exonic sequence was activated, the expression of modified U7 snRNA resulted in exon skipping. The correction of aberrant splicing by suppressing intronic cryptic splice sites with modified U7 is expected be a promising alternative to gene replacement therapy. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

COL 2A1基因突变致SEDC的产前分子诊断

目的本研究对COL2A1基因（typeⅡcollagen gene）G504S突变导致的先天性脊柱骨骺发育不良（SEDC）家系的1例中期妊娠者进行产前分子诊断,从而预防SEDC的发生。方法患者妻于20孕周在B超下进行羊膜囊穿刺,抽取羊水10ml,提取羊水细胞基因组DNA。选择3个多态性STR位点,即D3S1358、D16S539和D21S11,排除母体细胞污染。在此基础上,对COL2A1基因外显子23进行扩增,PCR产物进行正、反向测序。结果该例胎儿COL2A1的外显子23测序结果显示,胎儿未带有与父亲同样的COL2A1基因突变。胎儿产前基因诊断结果与B超监测结果一致。结论对于有SEDC风险的胎儿进行产前分子诊断非常重要,可以在B超诊断前了解胎儿基因型并明确诊断。     

DMRT1单倍体不足导致性发育异常

目的增加对DMRT1基因单倍体不足导致性发育异常的认识,提高性发育异常疾病的诊断水平。方法描述1例染色体为46XY性发育异常患者的临床特点;对患者及其父母的静脉血进行淋巴细胞培养和染色体核型分析;抽取患者外周血,提取基因组DNA,进行微阵列比较基因组杂交技术(a CGH)扫描。结果 1)患者表现为女性外阴,超声未见子宫和卵巢组织;伴随发育延迟和运动迟缓;临床表现符合9p缺失综合征;2)染色体结果:患者母亲46XX,t(7;9)(q35,p24);父亲46XY;患儿46XY,der(9)t(7;9)(q35,p24);3)a CGH扫描结果:患儿第7号染色体长臂部分(144741153-159098761)重复,长约14.37 Mb;第9号染色体短臂部分(10001-9733061)缺失,长约9.72 Mb,缺失部分包含EZH2、MNX1、DMRT1、DMRT2、SHH、SMARCA2、GLDC、VLDLR、DOCK8和GLIS3基因。结论 DMRT1在性腺发育过程中发挥重要作用。母亲染色体发生平衡易位,因无遗传物质丢失,故不导致疾病发生。在产生配体过程中,因DMRT1单倍体剂量不足,导致子代睾丸发育障碍。     

FLNA基因变异致额骨干骺端发育不良1型一例

目的:探讨 FLNA基因变异所致额骨干骺端发育不良1型(frontometaphyseal dysplasia 1,FMD1)的临床及遗传学特点。 方法:分析患儿的临床表型,应用全外显子测序技术对先证者进行致病基因变异筛查,用Sanger测序法对其父母进行验证。结果:先证者男性,2岁9个月,表现为...     

HEXIM1在先天性心脏病室间隔缺损中的突变及表达研究

目的通过筛查HEXIM1基因在室间隔缺损(ventricular septal defect,VSD)外周血中的突变和心肌组织中的表达情况,探讨HEXIM1基因与VSD发病机制的关系。方法采用PCR-DNA测序技术对100例单纯性室间隔缺损的患儿外周血进行基因编码序列突变筛查;以β-actin为内对照,用RT-PCR方法检测HEXIM1基因在14例室间隔缺损引产胎儿中mRNA的表达情况。结果所有研究对象的HEXIM1基因测序后同GenBank人类HEXIM1编码序列进行比较,有3例患儿(单纯性室间隔缺损)分别存在单核苷酸的多态性(SNP);与正常心肌组织相比,VSD引产胎儿心肌组织中HEXIM1基因mRNA表达呈下降趋势(P<0.05)。结论本实验收集的病例标本中没有发现HEXIM1基因编码区的突变,基因转录水平异常可能是该基因参与VSD形成的一种潜在机制。     

Influence of far upstream element binding protein 1 gene on chemotherapy sensitivity in human U251 glioblastoma cells

Introduction

The aim of this study was to determine the influence of the far upstream element binding protein 1 gene (FUBP1) on chemotherapy sensitivity in human U251 glioblastoma cells.

Material and methods

Real-time polymerase chain reaction (PCR) was used to determine the expression of the FUBP1 gene in 43 cases of human brain gliomas. Western blot analysis was used to determine the inhibitory effect of RNA interference on FUBP1 gene expression. Methyl thiazolyl tetrazolium assay (MTT) and flow cytometry methods were used to determine the growth inhibitory rate and apoptosis rate of the U251 cells with FUBP1 silencing. The growth inhibitory rate and apoptosis rate were further determined after treatment of those U251 cells with cisplatin (DDP).

Results

The expression of FUBP1 mRNA was up-regulated significantly in gliomas, 177.65% as much as in peri-cancerous tissues (p < 0.05). The expression of FUBP1 protein was inhibited significantly with siRNA-FUBP1 (p < 0.05). In FUBP1-silenced cells, the growth inhibitory rate increased from 1.4% to 29.5%, and the apoptosis rate increased from 2.68% to 5.84% (p < 0.05 for both). After treating with DDP at various concentrations (1, 3, 5 µg/ml), the growth inhibitory rate of FUBP1-silenced cells increased from 14.42%, 17.46% and 23.55% to 21.69%, 27.51% and 37.57%; the apoptosis rate increased from 8.85%, 14.37% and 18.21% to 13.25%, 18.46% and 26.52%.

Conclusions

The up-regulation of FUBP1 relates to the carcinogenesis of gliomas. FUBP1 silencing increases the growth inhibitory rate and apoptosis rate of the U251 cells, and enhances the chemotherapy sensitivity of U251 cells to DDP.     

非同位素PCR及Southern印迹杂交分析检测脆性X综合征FMR-1基因突变

目的建立一种非同位素的检测脆性X综合征智力缺陷基因(FMR-1)突变的方法.方法采用PCR技术结合Southern 印迹杂交技术对FMR-1基因进行分析,进而确定其突变类型.结果共对190例样本进行了检测,其中2例为女性前突变携带者,1例为女性全突变患者.结论非同位素PCR方法可以简便、安全、可靠地检测FMR-1基因中(CGG)n 重复拷贝数,可作为临床上对脆性X综合征的筛查的首选方法;而非同位素Southern印迹杂交可对结果不确定者进一步进行检测.     

一例TRNT1基因复合杂合新变异导致儿童SIFD综合征CSCD

目的对1例铁粒幼红细胞性贫血伴B细胞免疫缺乏、周期性发烧和发育迟缓患儿进行TRNT1基因变异分析,明确其可能的遗传学病因。方法应用外显子组检测对患儿及父母进行基因分析,对与临床表型相关的可疑变异位点进行Sanger验证及相关生物信息学预测分析其生物危害性,并通过同源结构预测变异危害性。结果基因检测结果显示患儿TRNT1基因存在c.88A>G(p.Met30Val)和c.363G>T(p.Glu121Asp)复合杂合变异,经Sanger测序验证父亲携带c.88A>G(p.Met30Val)杂合变异,母亲携带c.363G>T(p.Glu121Asp)杂合变异。检索PubMed等数据库两个变异均未见报道。通过对p.Glu121Asp蛋白结构预测分析变异可能会影响TRNT1蛋白与tRNA的结合稳定性。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南,TRNT1基因c.88A>G和c.363G>T变异分别判定为意义不明确(PM2+PP3+PP4)和可能致病性变异(PM1+PM2+PP3+PP4)。结论TRNT1基因c.88A>G(p.Met30Val)和c.363G>T(p.Glu121Asp)复合杂合变异可能为该患儿发病原因,新变异的检出拓展了TRNT1基因的变异谱。     

Dominant Leber congenital amaurosis,cone‐rod degeneration,and retinitis pigmentosa caused by mutant versions of the transcription factor CRX

We summarize 18 mutations in the human CRX gene that have been associated with Leber congenital amaurosis (congenital retinal blindness), cone‐rod degeneration, or retinitis pigmentosa. Except for one obviously null allele not definitely associated with a phenotype (a frameshift in codon 9), all CRX mutations appear to be completely penetrant and cause disease in heterozygotes. These dominant alleles fall into two categories. In one group are missense mutations and short, in‐frame deletions; in the second group are frameshift mutations, all of which are in the last exon. All of these dominant mutations are likely to produce stable mRNA that is translated. Mutations in the missense group preferentially affect the conserved homeobox (codons 39–98), and all frameshift mutations leave the homeodomain intact but alter the OTX motif encoded by codons 284–295 at the carboxy terminus. We could not uncover any correlation between type of disease (congenital amaurosis vs. cone‐rod degeneration or retinitis pigmentosa) and the type of mutation (missense vs. frameshift). Four of the 18 mutations (～20%) were de novo mutations, and all of these were found in isolate cases of Leber congenital amaurosis. Dominant CRX mutations have not been associated with mental retardation or developmental delay that has sometimes been found in Leber congenital amaurosis caused by other genes. Implications regarding potential future therapies are discussed. Hum Mutat 18:488–498, 2001. © 2001 Wiley‐Liss, Inc.