miR-513a-5p慢病毒载体的构建及其对人骨肉瘤细胞放疗敏感性的影响

目的:构建miR-513a-5p慢病毒过表达载体，转染人骨肉瘤细胞株，观察miR-513a-5p对人骨肉瘤细胞放疗敏感性的影响。方法:PCR法扩增人miR-513a-5p基因，克隆入pLentis-CMV-GFP-MCS-PGK-PURO载体获得重组质粒pLentis-miR513a，双酶切鉴定并测序后将正确的重组质粒和对照质粒转染293FT细胞制备慢病毒，分别转染骨肉瘤HOS和U2OS细胞，qRT-PCR法及荧光显微镜鉴定转染结果。克隆形成实验、MTT法检测miR-513a-5p高表达HOS和U2OS细胞在X射线照射下细胞存活情况。结果:双酶切及测序结果确定成功构建miR-513a-5p慢病毒载体pLentis-miR513a。qRT-PCR结果提示，转染骨肉瘤细胞株后miR-513a-5p表达显著升高。克隆形成实验结果显示miR-513a-5p高表达后骨肉瘤细胞在X射线照射下细胞增殖减慢。MTT结果提示miR-513a-5p高表达骨肉瘤细胞经X射线照射后细胞存活减少。结论:成功构建了miR-513a-5p慢病毒载体，建立了高效稳定表达miR-513a-5p的骨肉瘤细胞株，高表达miR-513a-5p能显著增加X射线照射后骨肉瘤细胞的放疗敏感性。     

人乳腺癌MDR1基因稳定沉默细胞的筛选及其生物学特性

目的筛选MDR1沉默的人乳腺癌细胞并比较其生物学特性。方法采用BLOCK-iT Lentiviral RNAi Expres-sion System生产表达MDR1基因shRNA的慢病毒载体,转导敏感人乳腺癌细胞MCF-7和耐阿霉素人乳腺癌细胞MCF-7/ADM,杀稻瘟菌素(blasticidin)筛选获得MDR1稳定沉默细胞MCF-7/RNAi和MCF-7/ADM/RNAi。定量RT-PCR检测MDR1mRNA表达,流式细胞术检测P-GP蛋白表达和功能,MTT法检测药物敏感性。结果经10 mg/L blasticidin筛选12 d获得MCF-7/RNAi和MCF-7/ADM/RNAi细胞。MCF-7、MCF-7/RNAi、MCF-7/ADM和MCF-7/ADM/RNAi细胞的MDR1mRNA相对表达水平分别为1、0.13、17.14和2.01;P-GP表达分别为(1.5±0.3)%、(1.2±0.2)%、(89.4±3.6)%和(16.3±1.9)%;细胞内Rh123的潴留分别为(92.4±3.1)%、(90.6±4.0)%、(13.6±1.6)%、(72.4±2.8)%;IC50值分别为0.90、0.92、19.61和4.04 mg/L。结论应用慢病毒载体稳定沉默MDR1基因可有效逆转人乳腺癌细胞耐药性。     

微小RNAmiR-26a的克隆及其慢病毒表达载体的构建

目的克隆微小RNAhsa-miR-26a并构建其慢病毒表达载体。方法将PCR扩增得到的miR-26。前体序列和pIVTHM载体经双酶切后连接产生pIVTHM-miR-26a慢病毒表达载体，双酶切后测序鉴定。筛选阳性克隆。用pIVTHM-miR-26a、psPAX2和pMD2-G3质粒共转染包装细胞293FT，包装产生慢病毒，以293FT细胞绿色荧光蛋白（green fluorescent protein，GFP）的表达水平测定病毒滴度。结果经双酶切鉴定和测序证实，成功构建了miR-26a的慢病毒表达载体pIVTHM—miR-26a。倒置荧光显微镜下观察可见包装细胞293FT呈绿色荧光．并测得病毒滴度为5×10^5TU／ml。成功构建hsa—miR-26a的慢病毒表达载体，为深入研究miR-26a的生物学功能奠定了基础．     

慢病毒介导的外源基因体外投递系统的建立

目的针对不同哺乳类细胞建立相应的慢病毒体外感染体系，以建立慢病毒介导的外源基因体外投递系统。方法按Invitrogen公司推荐的标准程序进行慢病毒（携带EGFP基因）包装（脂质体介导的瞬时转染）、超速离心浓缩和保存等，随后用病毒上清或浓缩后的病毒感染293FT细胞，24—48h后荧光显微镜下观察是否见绿色荧光以证实慢病毒是否成功生产；将携带EGFP基因的病毒上清或浓缩后的病毒分别加入内含293FF细胞、小鼠ES细胞、小鼠胚胎成纤维细胞（MEFs）或小鼠睾丸生殖细胞的培养板孔内，感染6—12h后，用相应培养基替换感染液，数天后荧光显微镜下观察是否见绿色荧光以证实慢病毒是否成功感染不同哺乳类细胞。结果按标准程序生产的携带EGFP基因慢病毒（病毒上清或浓缩后的病毒）成功高效率感染293FF细胞、MEFs或小鼠睾丸生殖细胞；用浓缩后的病毒（携带EGFP基因）感染小鼠ES细胞，亦可获得EGFP阳性的ES细胞克隆。结论熟练掌握了慢病毒包装、浓缩及鉴定等技术，同时针对不同哺乳类细胞建立了相应的慢病毒介导的外源基因体外传递系统，这些为相关后续研究打下了良好的基础。     

Hypothalamic Corticotropin-Releasing Factor is Centrally Involved in Learning Under Moderate Stress

The corticotropin-releasing factor (CRF) neuropeptide is found to have a pivotal role in the regulation of the behavioral and neuroendocrine responses to stressful challenges. Here, we studied the involvement of the hypothalamic CRF in learning under stressful conditions. We have used a site-specific viral approach to knockdown (KD) CRF expression in the paraventricular nucleus of the hypothalamus (PVN). The two-way shuttle avoidance (TWSA) task was chosen to assess learning and memory under stressful conditions. Control animals learned to shuttle from one side to the other to avoid electrical foot shock by responding to a tone. Novel object and social recognition tasks were used to assess memory under less stressful conditions. KD of PVN-CRF expression decreased the number of avoidance responses in a TWSA session under moderate (0.8 mA), but not strong (1.5 mA), stimulus intensity compared to control rats. On the other hand, KD of PVN-CRF had no effect on memory performance in the less stressful novel object or social recognition tasks. Interestingly, basal or stress-induced corticosterone levels in CRF KD rats were not significantly different from controls. Taken together, the data suggest that the observed impairment was not a result of alteration in HPA axis activity, but rather due to reduced PVN-CRF activity on other brain areas. We propose that hypothalamic CRF is centrally involved in learning under moderate stressful challenge. Under ‘basal'' (less stressful) conditions or when the intensity of the stress is more demanding, central CRF ceases to be the determinant factor, as was indicated by performances in the TWSA with higher stimulus intensity or in the less stressful tasks of object and social recognition.     

Novel lentiviral vectors for human gene therapy

This review summarises an emerging viral vector system for use in human gene therapy - lentiviral vectors. Lentiviral vectors have several advantages over existing viral vectors. They can stably express transgenes in non-dividing cells in vivo without provoking a significant immune response. They can be produced to a high titre and can be pseudotyped with heterologous envelope proteins to confer broad tropism. Although not without safety concerns, the properties of lentiviral vectors makes them an attractive choice for human gene therapy.     

Development of packaging cell lines for generation of adeno-associated virus vectors by lentiviral gene transfer of trans-complementary components

Adeno-associated virus (AAV) vector system has several useful advantages with regard to in vitro and in vivo gene transfer. However, their usages have been limited by cumbersome and labor-intensive vector production in the traditional method. To overcome limitations in AAV production, in this report, we explored the possibility of generating AAV packaging cell line, 293T R/C.VA.E2A.E4. cells, by using lentivirus-mediated transduction of Rep/Cap gene of AAV-2, VA RNA, E2A, and E4 genes of Ad5 into 293T cells. In packaging cell lines, it is important that supply of the AAV vector can be stably performed for long time. We showed that the 293T R/C.VA.E2A.E4. cells have stably maintained the transduced components after more than 10 passages and yielded high-titer AAV vectors, and the titer of AAV vectors did not decline even if culture of the packaging cells was continued for long time. The Rep/Cap and E4 gene products caused no remarkable cytotoxicity. The 293T R/C.VA.E2A.E4. cells might be able to tolerate the Rep/Cap and E4 gene products, or have less copy numbers of the Rep/Cap and E4 genes than the traditional method. Moreover, we showed that the AAV vectors derived from 293T R/C.VA.E2A.E4. cells infected the primary human CD34+ haematopoietic progenitor cells with high efficiency (50-70%). In the 293T R/C.VA.E2A.E4. cells, the AAV vectors can be generated by the transfection of one AAV vector plasmid, and large-scale AAV production can be easily achieved. It is important that cumbersome, variable, and costly transfection is avoided.     

Brief Report: Divergent low-density lipoprotein receptor (LDLR) linked to low VSV G-dependent viral infectivity and unique serum lipid profile in zebra finches

The low-density lipoprotein receptor (LDLR) is key to cellular cholesterol uptake and is also the main receptor for the vesicular stomatitis virus glycoprotein (VSV G). Here we show that in songbirds LDLR is highly divergent and lacks domains critical for ligand binding and cellular trafficking, inconsistent with universal structure conservation and function across vertebrates. Linked to the LDLR functional domain loss, zebra finches show inefficient infectivity by lentiviruses (LVs) pseudotyped with VSV G, which can be rescued by the expression of human LDLR. Finches also show an atypical plasma lipid distribution that relies largely on high-density lipoprotein (HDL). These findings provide insights into the genetics and evolution of viral infectivity and cholesterol transport mechanisms in vertebrates.     

Lentiviral vector delivery of parkin prevents dopaminergic degeneration in an alpha-synuclein rat model of Parkinson's disease

Parkinson's disease (PD) is characterized by a progressive loss of midbrain dopamine neurons and the presence of cytoplasmic inclusions called Lewy bodies. Mutations in several genes including alpha-synuclein and parkin have been linked to familial PD. The loss of parkin's E3-ligase activity leads to dopaminergic neuronal degeneration in early-onset autosomal recessive juvenile parkinsonism, suggesting a key role of parkin for dopamine neuron survival. To evaluate the potential neuroprotective role of parkin in the pathogenesis of PD, we tested whether overexpression of wild-type rat parkin could protect against the toxicity of mutated human A30P alpha-synuclein in a rat lentiviral model of PD. Animals overexpressing parkin showed significant reductions in alpha-synuclein-induced neuropathology, including preservation of tyrosine hydroxylase-positive cell bodies in the substantia nigra and sparing of tyrosine hydroxylase-positive nerve terminals in the striatum. The parkin-mediated neuroprotection was associated with an increase in hyperphosphorylated alpha-synuclein inclusions, suggesting a key role for parkin in the genesis of Lewy bodies. These results indicate that parkin gene therapy may represent a promising candidate treatment for PD.     

S100PshRNA慢病毒载体的构建及其对胃癌MGC-803细胞生物学行为的影响

目的：：构建针对S100P基因的shRNA慢病毒载体,并在胃癌MGC-803细胞上鉴定沉默效率,观察其对细胞生物学行为的影响。方法：筛选的S100P基因特异性siRNA靶点,合成短发卡结构shRNA,并与GV115-GFP慢病毒载体重组形成shRNA表达载体,与pHelper 1.0和pHelper 2.0质粒共转染293T细胞,产生慢病毒。用病毒感染MGC-803细胞,RT-PCR和Western blot检测靶基因的沉默效率、克隆形成情况、细胞周期变化和凋亡实验观察靶基因沉默对MGC-803的影响。结果：构建的重组shRNA慢病毒载体,经293T细胞包装获得病毒颗粒,和阴性对照相比,慢病毒感染组S100 P mRNA表达下降了83.4%,蛋白表达也明显受到抑制。 S100 P沉默后MGC-803的克隆形成能力明显减弱,细胞周期发生S期阻滞,细胞凋亡明显增加。结论：成功地构建了S100P基因shRNA慢病毒表达载体,该载体能够在MGC-803细胞中沉默S100P基因的表达,导致胃癌细胞克隆形成能力降低,细胞周期阻滞,诱导细胞凋亡,表明S100 P基因有可能具有影响胃癌发生发展的作用。