两种方法制备阳离子脂质体包裹蛋白转染法的比较

目的 比较不同方法制备包裹蛋白脂质体的包封率和转染率 ,评价蛋白转染的可行性。方法 采用逆相蒸发法和冻融超声法制备包裹人IgG的阳离子脂质体 ,测定包封率并分别转染小鼠脾细胞 ,用流式细胞术、免疫荧光法、SDS聚丙烯酰胺凝胶电泳法和免疫印迹法检测转染效果。结果 逆相蒸发法制备的脂质体包封率高于冻融超声法 (P <0 .0 1)。两种方法制备的脂质体转染率无显著性差异 (P >0 .0 5 )。

聚乙烯亚胺-蛋白纳米复合体转染蛋白进入骨髓间充质干细胞的应用研究

目的:探索纳米材料聚乙烯亚胺(PEI)携载不同分子量的蛋白质转染进人骨髓间充质干细胞(h BMSCs)的作用及优化其最佳配比条件。方法:利用物理化学作用构建6组PEI-DNase I(DNA酶I)复合体,运用激光散射技术初步摸索其最佳摩尔比,用透射电镜直观复原纳米-蛋白复合体外貌;同时,原代分离培养健康人的骨髓间充质干细胞并进行体外扩增,通过构建成功的4组PEI-GFP(绿色荧光蛋白)纳米蛋白复合体对h BMSCs进行转染,共聚焦荧光显微镜下观察荧光表达情况,再通过MTT法检测该复合体对细胞增殖的毒性影响,并用β-半乳糖苷酶实验验证其转入蛋白的活性表现。结果:当PEI与蛋白质的摩尔比为4∶1时,形成的复合体转染效率最高,β-半乳糖苷酶实验细胞染色变蓝。结论:PEI能与蛋白质形成纳米复合体,并能转染多种蛋白质进入人骨髓间充质干细胞,所转染的蛋白质分子仍具有活性,为细胞重编程技术提供了新途径。

改良鱼精蛋白-脂质体-寡聚核苷酸复合体法转染卵巢癌SKOV3细胞

目的:优化鱼精蛋白-脂质体-寡聚核苷酸(oligodeoxynuleotides,ODN)复合体(liposome—protamine—ODN,LPD)法以提高SKOV3细胞的转染效率,并探讨该转染法对细胞体外增殖能力的影响。方法:参照文献设计核转录因子-κB(NF-κB)诱捕物ODN和对照物Scrambled ODN,并用FITC标记。LPD表面+/-电荷比例设计为1,2,4,6,并按转染液中是否含有小牛血清分成2组。用荧光光度计、流式细胞仪测定转染效率。用MTT法观察LPD法对SKOV3细胞在体外增殖的影响。结果:SKOV3细胞经LPD法转染,+/-电荷比例为4时转染效率最高,达96.41％,而无鱼精蛋白-脂质体的裸露ODN细胞转染效率为12.87％,两者差异有统计学上的高度显著性意义。培养液中10％小牛血清对转染效率无明显影响。结论:适宜电荷比例的LPD法是一种不受血清影响的高效率转染方法,有望用于体内转染。

半滑舌鳎(Cynoglossus semilaevis)雌性特异基因CSW3重组蛋白的表达与应用

CSW3基因序列来源于半滑舌鳎(Cynoglossus semilaevis)全基因组测序项目,是经过筛选得到的雌性特异候选基因之一。本研究探索了半滑舌鳎雌性相关基因CSW3的表达与应用,构建了半滑舌鳎雌性特异CSW3基因重组表达载体,通过大肠杆菌进行了体外重组表达,对基因表达产物进行分离纯化,并通过蛋白转染的方法研究了纯化的蛋白对几个性别相关基因的影响。结果显示,雌性特异CSW3重组蛋白注射鱼体后对半滑舌鳎性腺foxl2、sox9a、amh这3种性别相关基因的表达水平具有显著影响,能够引起雌性相关基因foxl2表达上调、雄性相关基因sox9a和amh表达下降。从蛋白水平对雌性相关基因CSW3的基因功能进行初步研究,为半滑舌鳎性别控制及全雌苗育种提供基因资源及技术方法。

γ-氨基丁酸受体ρ2亚基重组蛋白构建及表达

目的构建γ-氨基丁酸受体ρ2(GABA_CR ρ2)基因的原核表达载体,诱导重组蛋白GABA_CR ρ2表达,转染SH-SY5Y细胞,实现GABA_CR ρ2亚基重组蛋白一过性表达。方法构建重组质粒p ET-ρ2-GFP-Tat;应用免疫印迹法检测GABA_CR ρ2表达;应用Ni^(2+)亲和层析柱纯化重组蛋白,十二烷基硫酸钠-聚丙烯酰胺凝胶电泳检测GABA_CR ρ2蛋白纯度;荧光显微镜下观察GABA_CR ρ2的转导作用及细胞定位。将SH-SY5Y细胞分为正常组和低氧低糖组,正常组分为正常对照组(高糖培养基培养且无蛋白转染)和正常转染组(高糖培养基培养且进行蛋白转染);低氧低糖组分为处理组(低氧低糖条件下培养)和处理转染组(低氧低糖条件下培养且进行蛋白转染);使用细胞计数试剂盒检测各组细胞活力。结果重组质粒p ET30-ρ2-Tat构建正确。纯化后的重组蛋白ρ2-Tat成功透过细胞膜转染SH-SY5Y细胞。正常对照组、正常转染组、处理组和处理转染组的细胞活力分别为(100.0±6.9)%、(89.3±3.6)%、(51.4±3.6)%和(66.1±8.5)%。正常对照组与正常转染组细胞活力比较差异无统计学意义(P>0.05);处理组细胞活力显著低于正常对照组(P<0.01),处理转染组细胞活力显著高于处理组(P<0.01)。结论重组蛋白ρ2在Tat转导肽介导作用下透过细胞膜,成功建立了一过性表达重组蛋白ρ2的SH-SY5Y细胞株,为研究ρ2亚基的功能提供了新的研究方法。

转染连接蛋白基因对人脑胶质瘤细胞间隙连接通讯及其生长变化的研究

目的 研究连接蛋白 (Cx)基因对人脑胶质瘤细胞的细胞间隙连接通讯 (GJIC)及其增殖的抑制作用 ,探索以Cx43基因治疗胶质瘤的可行性。方法 将含Cx43cDNA的质粒 ,以脂质体介导转染Cx43表达缺失的TJ90 5人胶质母细胞瘤细胞 ,通过Northern印迹杂交、原位杂交及免疫组化染色检测Cx43mRNA及蛋白表达 ,划痕标记荧光染料示踪技术 (SLDT)检测GJIC ,MTT法测定细胞增殖率 ,核仁组成区嗜银蛋白 (AgNOR)染色检测细胞增殖活性 ,TUNEL法检测细胞凋亡。结果 转染后TJ90 5细胞有不同程度的Cx43mRNA和蛋白表达及GJIC恢复。Cx43表达水平高的克隆细胞增殖明显下降 ,细胞凋亡并未增加。结论 Cx43基因及GJIC在恶性胶质瘤的发生发展过程中起重要作用 ,可能成为恶性胶质瘤基因治疗的优选靶的之一。

转染连接蛋白基因对胶质瘤细胞细胞间隙连接通讯及其生长变化的研究

目的 研究连接蛋白 (Cx)基因对C6胶质瘤细胞的增殖抑制及细胞间隙连接通讯(GJIC)的作用 ,探讨以Cx43基因治疗胶质瘤的可行性。方法 将含Cx43cDNA的质粒以Lipofec tamine介导转染Cx43表达缺失的C6胶质瘤细胞 ,通过Northern印迹杂交、原位杂交及免疫组织化学染色检测Cx43mRNA及蛋白表达 ,划痕标记荧光染料示踪技术 (SLDT)检测GJIC ,MTT法测定细胞增殖率 ,核仁组成区嗜银蛋白 (AgNOR)染色检测细胞增殖活性 ,TUNEL法检测细胞凋亡。结果 转染后C6细胞有不同程度的Cx43mRNA及蛋白表达和GJIC恢复。表达Cx43的克隆细胞增殖明显下降 ,培养 2～ 6d时 ,每天除C6组与空载组差异无显著性外 ,其余各组差异均有非常显著性 (P <0 .0 1) ,但细胞凋亡并未增加。结论 Cx43基因及GJIC在恶性胶质瘤的发生发展过程中起重要作用 ,可能成为恶性胶质瘤基因治疗的优选靶的之一。

转染干扰素-γ诱导蛋白-10基因构建树突状细胞前列腺癌瘤苗及其抗肿瘤免疫作用的检测

目的 将小鼠前列腺癌细胞株RM-1裂解产物加载树突状细胞(DC)后,转染干扰素-γ诱导蛋白-10(IP-10)基因构建DC瘤苗,探讨该瘤苗对小鼠抗肿瘤免疫反应的诱导作用。方法将RM-1细胞的裂解产物作为肿瘤抗原加载小鼠骨髓来源的DC,并通过脂质体法转染IP-10基因,构建DC瘤苗;检测DC瘤苗的抗前列腺癌免疫治疗作用和免疫保护作用。结果 转染DC强表达IP-10,其上清对淋巴细胞有较强的趋化作用;构建的DC瘤苗能诱导特异性抗前列腺癌免疫反应,经瘤苗处理的荷瘤小鼠瘤体生长减慢,存活期延长;瘤苗还具有明显的免疫保护作用。结论构建的前列腺癌DC瘤苗在体内能有效诱导抗肿瘤免疫反应和免疫保护功能。

Smad3 mediates immediate early induction of Idl by TGF-β

Idl is a member of the inhibitor of differentiation （Id） protein family that regulates a wide range of cell functions. Previous studies have shown that expression of the Idl gene is down-regulated by TGF-β in epithelial cells, whereas it is up-regulated by BMP in a variety of cell types. During our study of the biological function of TGF-β1, we found that Idl can be strongly up-regulated by TGF-β1 in the human mammary gland epithelial cell line MCF10A. Quantitative real-time RT-PCR has revealed as high as 7.5-fold induction ofldl mRNA by TGF-β1 in MCF10A cells after 1 h of TGF-β1 stimulation, and this induction does not require de novo protein synthesis. Using Smad knockdown and knockout approaches, we have identified Smad3 as the responsible R-Smad for mediating transcriptional activation of the Idl gene. Chromatin immunoprecipitation assay confirms that Smad3 and Smad4 bind to the upstream region of the Idl gene. Our results demonstrate that Smad3, but not Smad2, mediates TGF-β1-dependent early transcriptional induction of Idl.

Increased activity of Pgp multidrug transporter in patients with Helicobacter pylori infection

AIM: To determine whether local antibiotic resistance involves P-glycoprotein (Pgp)-mediated active drug outpumping during Helicobacter pylori ( H pylori) infection treatment with classic antibiotic therapy. METHODS: Pgp activity was determined in gastric mucosa biopsy specimens obtained from 53 patients with pathohistologically verified gastritis and microbiologically confirmed H pylori infection, and compared with the Pgp activity in 12 control subjects with normal endoscopic findings. TheH pylori positive patients were treated with short-term 7-d therapy consisting of two antibiotics (amoxicillin and azithromycin/metronidazole and clarithromycin) and a proton pump inhibitor. Pgp activity was determined by flow cytometry in the test of rhodamine dye efflux and quantified as mean fluorescence ratio (RMF).RESULTS: Upon the first cycle,H pylori was successfully eradicated in 20 patients, whereas therapy was continued in 33 patients. In the course of antibiotic therapy, RMF increased (P＜0.05) and gastric cells showed higher rhodamine dye efflux. The mean pre-treatment RMF values were also higher (P＜0.0001) in patients with multiple therapeutic failure than in those with successful H pylorieradication and control subjects.CONCLUSION: Pgp might be one of the causes of therapy failure in patients with H pylori and antibiotic therapy could be chosen and followed up on the basis of the Pgp transporter local activity.

Fascin promotes the motility and invasiveness of pancreatic cancer cells

AIM:To explore the role of actin-bundling protein, fascin during the progression of pancreatic cancer. METHODS:The plasmid expressing human fascin-1 was stably transfected into the pancreatic cancer cell line MIA PaCa-2. The proliferation, cell cycle, motility, scattering, invasiveness and organization of the actin filament system in fascin-transfected MIA PaCa-2 cells and control non-transfected cells were determined. RESULTS:Heterogeneous overexpression of fascin markedly enhanced the motility, scattering, and inva-siveness of MIA PaCa-2 cells. However, overexpression of fascin had minimal effect on MIA PaCa-2 cell pro-liferation and cell cycle. In addition, cell morphology and organization of the actin filament system were distinctly altered in fascin overexpressed cells. When transplanted into BALB/c-nu mice, fascin-transfected pancreatic cancer cells developed solid tumors at a slightly slower rate, but these tumors displayed more aggressive behavior in comparison with control tumors. CONCLUSION: Fascin promotes pancreatic cancer cell migration, invasion and scattering, thus contributes to the aggressive behavior of pancreatic cancer cells.

Ameliorated stress related proteins are associated with improved cardiac function by sarcoplasmic reticulum calcium ATPase gene transfer in heart failure

Background Previous studies showed that overexpression of sarco-endoplasmic retieulum calcium ATPase （SERCA2a） in a variety of heart failure （HF） models was associated with greatly enhanced cardiac performance. However, it still undefined the effect of SERCA2a overexpression on the systemic inflammatory response and neuro-hormonal factors. Methods A rapid right ventricular pacing model of experimental HF was used in beagles. Then the animals underwent recombinant adeno-associated vires 1 （rAAV1） mediated gene trans- fection by direct intra-myocardium injection. HF animals were randomized to receive the SERCA2a gene, enhanced green fluorescent protein （control） gene, or equivalent phosphate buffered saline. Thirty days after gene delivery, the cardiac function was evaluated by echocardiographic testing. The protein level of SERCA2a was measured by western blotting. The proteomic analysis of left ventricular （LV） sample was determined using two-dimensional （2-D） gel el^ctrophoresis and MALDI-TOF-MS. The serum levels of the systemic inflammatory and neuro-hormonal factors were assayed using radioimmunoassay kits. Results The cardiac function improved after SERCA- 2a gene transfer due to the significantly increased SERCA2a protein level. Beagles treated with SERCA2a had significantly decreased serum levels of the inflammatory markers （interleukin-6 and tumor necrosis factor-a） and neuro-hormonal factors （brain natriuretic peptide, endothelin-1 and angiotensin II） compared with HF animals. The myocardial proteomic analysis showed that haptoglobin heavy chain, heat shock protein （alpha-crystallin-related, B6） were down-regulated, and galectin-1 was up-regulated in SERCA2a group compared with HF group, companied by up-regulated contractile proteins and NADH dehydrogenase. Conclusions These findings demonstrate that regional intramyocardial injections of rAAV 1-SERCA2a vectors may improve global LV function, correlating with reverse activation of the systemic inflammatory, excessive neuroendocrine factors and the stress-associated myocardial proteins, suggesting that the beneficial effects of SERCA2a gene transfer may involve the attenuation of stress-associated reaction.

The developmental fate of green fluorescent mouse embryonic germ cells in chimeric embryos

Primordial germ cells (PGCs), as precursors of mam-malian germ lineage, have been gaining more attention as anew resource of pluripotent stem cells, which bring a greatpossibility to study developmental events of germ cell invitro and at animal level. EG4 cells derived from 10.5 dayspost coitum (dpc) PGCs of l29/svJ strain mouse wereestablished and maintained in an undifferentiated state.With an attempt to study the differentiation capability ofEG4 cells with a reporter protein: green fluorescence pro-tein, and the possible application of EG4 cells in the re-search of germ cell development, we have generated severalEG4-GFP cell lines expressing enhanced green fluorescenceprotein (EGFP) and still maintaining typicaI characteris-tics of pluripotent stem cells. Then, the differentiation ofEG4-GFP cells in vitro as well as their developmental fatein chimeric embryos which were produced by aggregatingEG4-GFP cells to 8-cell stage embryos were studied. Theresults showed that EG4 cells carrying green fluorescencehave a potential use in the research of germ cell develop-ment and other related studies.

IMPROVING P-gp EXPRESSION IN HUMAN MONONUCLEAR CELLS IN VITRO TRANSFECTED BY MULTIDRUG RESISTANCE-1 mRNA

Objective To evaluate the expression and function activity of P-glycoprotein (P-gp) in human mononuclear cells (MNCs) in vitro transfected by multidrug resistance-1(MDR1) mRNA. Methods Two MDR1 cDNA vectors, pT7TS_MDR1 and pGEM5Zf(+)_MDR1, were constructed and transcripted in vitro. Vector pGEM5Zf(+)_MDR1 only contained the coding region of mdr1 cDNA, and pT7TS_MDR1 also included Xeponus β-globin 5’ and 3’ untranslated region. MNCs were prepared from peripheral blood of parvicellular lung cancer patient. The two human mdr1 mRNAs were then transferred into human MNCs in vitro by DOTAP. And the expression efficiency and pump function of P-gp were measured with flow cytometry. Results Expression of P-gp significantly elevated in both transferred cells compared with untransferred cells (P < 0.01). And pT7TS_MDR1 showed higher capability in elevating the expression of P-gp than pGEM5Zf(+)_MDR1 (P < 0.01). The P-gp function was elevated in both pT7TS_MDR1 and pGEM5Zf(+)_MDR1 groups. The survival ratio of MNCs in erythrocyte-lysis-solution (ELS, 86.07%) and lymphocyte-isolation-solution (LIS, 83.67%) had no significant difference. The CD34+ cells content of the MNCs used for transfection was 2.65% and 1.01% in ELS and LIS group, respectively (P < 0.01).Conclusions It is a feasible approach to improve P-gp expression in human MNCs by transfection of MDR-1 mRNA. And the ELS may be more suitable for purifing MNCs for mRNA transfection than LIS.

PREDOMINANT EXPRESSION OF HUMAN Aγ-IN CONTRAST WITH β-GLOBIN GENE IN MEL CELLS TRANSFECTED WITH THE CONSTRUCT μLCRAγψβδ

A cosmid construct μLCRAγψβδβ were induced into mouse erythroleukemia cell lines 585 that expresses murine adult globin only and MEL GM 979 that expresses both murine embryonic and adult globins.Similar patterns of human globin gene expression were displayed in the two MEL cell lines transfected with the construct.Inducible expression of the Aγ and β gene was observed during induced cell differentiation.However,the expression level of the Aγ globin gene is much higher than that of the β globin gene in either uninduced or induced MEL transformants.No γ to β switching happened in the stable MEL transformants following a continuous culture.The much more effective enhance of the μLCR on the Aγ globin gene than that on the β globin gene is resulted probably from the fact that the distance between the LCR and the β globin gene is much longer than that between the LCR and the Aγ globin gene in the construct,in comparison with other constructs containing HS2 or μLCR linked to both of γ and β globin genes in different order.Two suggestions can be derived from these results:1) A competition between the γ and β globin gene for interaction with the LCR may indeed present,but only an enough long distance difference between the LCR to the γ and to the β gene can effectively influence the competition;2) Unlike transgenic mice,MEL cells are incapable of reconstructing the regulatory information involved in developmental control when it is provided by a fragment of the β globin gene cluster with limited length.

Human bone morphogenetic protein-2 gene transfer induces human mesenchymal stem cell proliferation and differentiation in vitro

Objective: To identify eukaryotic expression vector of human bone morphogenetic protein 2 pcDNA3/BMP2, verify its expression in transfected human mesenchymal stem cells (hMSCs) and the effect on hMSCs differentiation. Methods: The BMP2 gene was cloned into a eukaryotic expression vector pcDNA3. Transfected the recombinant into hMSCs by liposome. Immunnohistochemistry and in situ hybridization methods were used to identify the expression of BMP2 mRNA and protein; ALP and Von Kossa stains were performed to identify the BMP2 gene differentiated effect on the hMSCs. Results: The pcDNA3/BMP2 fragments were as large as theory. BMP2 mRNA and protein were expressed and synthesized both in 48 h and 4 weeks after transfection, the ALP and Ca deposit exhibition, which marked the osteogenic lineage of hMSCs, were enhanced and sped. Conclusion: Transfection of pcDNA3/BMP2 is able to provide transient and persistent expression in hMSCs, and promote the MSCs differentiation to osteogenic lineage.

Effect of breast-cancer metastasis suppressor 1 (BRMS1) on growth and metastasis of human gastric cancer cells in vivo

Objective： The aim of the study was to investigate inhibitory effects of breast-cancer metastasis suppressor 1 protein （BRMS1） on primary tumor growth and metastasis of human gastric cancer （GC） cells in nude mice. Methods： We compared the expression of BRMS1 in the primary gastric tumor and metastatic gastric tumor by immunohistochemistry. Expression of BRMS1 also was detected in the GC cells by RT-PCR and Western blot. Three groups of cultured human GC cell line SGC-7901, were maintained： transfected cells with pcDNA3.1（-）B/myc-BRMS1; negative control cells with pcD- NA3.1/myc-his（-）B; and blank control ceils without any transfection. Histologically intact samples of the cells, maintained by passage in the subcutis of nude mice, were transplanted orthotopically into stomach walls of nude mice to establish a nude mouse model of human gastric carcinoma. Their primary tumor growth and metastasis were then observed. Results： The expression of BRMS1 was markedly stronger in the primary gastric tumor compared with metastatic gastric tumor. We also detected BRMS1 gene and protein in the gastric cancer cell tines. Numbers of metastasis tumors significantly differed among mice infected with transfected cells, with negative controls and with blank controls （4.38 ± 0.60, 7.75 ± 0.59, and 7.63± 0.65, respectively; P 〈 0.05）. However, there were no significant differences in the size of orthotopic tumors among mice infected with transfected, negative control and blank control cells [（12.02 ± 0.70）, （12.71 ± 0.63） and （12.89 ± 0.71） mm, respectively; P 〉 0.05]. Conclusion： BRMS1 suppresses metastasis of GC cells, but does not inhibit growth of gastric tumors.

Combined transfection of Bcl-2 siRNA and miR-15a oligonucleotides enhanced methotrexate-induced apoptosis in Raji cells

Objective: B-cell lymphoma 2 (Bcl-2) is an important member of the Bcl-2 family of proteins that regulate the induction of apoptosis. This study aims to investigate whether Bcl-2 small interfering RNA (siRNA) combined with miR-15a oligonucleotides (ODN) could enhance methotrexate (MTX)-induced apoptosis in Raji cells. Methods: Chemically synthesized miR-15a ODN and Bcl-2 siRNA were transfected in Raji cells by using a HiPerFect Transfection Reagent and then combined with MTX. Expression levels of Bcl-2 protein were detected by Western blot. Cell proliferation was determined by CCK8 assay. The rate of cell apoptosis was determined by Annexin V/PI double staining. The morphology of apoptotic cells was observed by Hoechst-33 258 staining. Results: After the cells were transfected with miR-15a ODN combined with Bcl-2 siRNA, Bcl-2 protein levels were evidently decreased. CCK8 assay showed that cell proliferation was significantly decreased and was significantly lower in miR-15a ODN combined with Bcl-2 siRNA plus MTX group than in miR-15a ODN with methotrexate group, Bcl- 2 siRNA with MTX group, and single MTX group (P<0.05). Hoechst 33258 staining revealed numerous apoptotic cells. AnnexinV/PI double staining showed that the apoptotic rates were (13.13±1.60)%, (34.47±2.96)%, (32.87±3.48)%, and (45.47±2.16)% in MTX, Bcl-2 siRNA plus MTX, miR-15a ODN plus MTX, and miR-15a ODN combined with Bcl- 2 siRNA plus MTX groups, respectively. Among these groups, the apoptotic rate of miR-15a ODN combined with Bcl-2 siRNA plus MTX group was the highest; this apoptotic rate was also significantly different from that of miR-15a ODN or Bcl-2 siRNA plus MTX (P<0.05). Conclusions: Bcl-2 siRNA combined with miR-15a ODN could enhance MTX-induced apoptosis in Raji cells. Bcl-2 siRNA and miR-15a combined with MTX may be a useful approach to improve the treatment effects on lymphoma.

Polymerase chain reaction-single strand conformational polymorphism analysis of rearranged during transfection proto-oncogene in Chinese familial hirschsprung's disease

AIM: To investigate the relationship between mutations of rearranged during transfection (RET) proto-oncogene and Chinese patients with Hirschsprung's disease (HD), and to elucidate the genetic mechanism of familial HD patient at the molecular level.METHODS: Genomic DNA was extracted from venous blood of probands and their relatives in two genealogies.Polymerase chain reaction (PCR) products, which were amplified using specific primers (RET, exons 11, 13, 15and 17), were electrophoresed to analyze the single-strand conformational polymorphism (SSCP) patterns. The positive amplified products were sequenced. Forty-eight sporadic HD patients and 30 normal children were screened for mutations of RET proto-oncogene simultaneously.RESULTS: Three cases with HD in one family were found to have a G heterozygous insertion at nucleotide 18 974 in exon 13 of RET cDNA (18 974insG), which resulted in a frameshift mutation. In another family, a heterozygosity for T to G transition at nucleotide 18 888 in the same exon which resulted in a synonymous mutation of Leu at codon 745 was detected in the proband and his father. Eight RET mutations were confirmed in 48 sporadic HD patients.CONCLUSION: Mutations of RET proto-oncogene may play an important role in the pathogenesis of Chinese patients with HD. Detection of mutated RET proto-oncogene carriers may be used for genetic counseling of potential risk for HD in the affected families.