Short-hairpin RNA expressed from polymerase III promoters mediates RNA interference in mosquito cells

Putative U6snRNA polymerase III (PolIII) promoters were cloned from the Anopheles gambiae and Aedes aegypti genomes. The PolIII promoters were tested for their ability to express short-hairpin RNA (shRNA) targeted to firefly luciferase and to mediate RNA interference (RNAi) knockdown of a co-transfected luciferase reporter gene vector in AG-55 Anopheles gambiae and ATC-10 Aedes aegypti cells. Promoters capable of silencing expression of the co-transfected luciferase plasmid by up to 95% in AG-55 cells and up to 75% in ATC-10 cells were identified. RNase protection experiments allowed detection of the 19 nt luciferase short-interfering RNA (siRNA) in transfected cells. These findings indicate that mosquito U6snRNA gene promoters can be used for production of shRNA to induce the RNAi response in mosquito cells.     

Differentiation-specific factors modulate epidermal CYP1-4 gene expression in human skin in response to retinoic acid and classic aryl hydrocarbon receptor ligands

Human epidermal keratinocytes express subsets of cytochromes P450 (P450) (CYP gene products) that are strongly up-regulated, not regulated, or down-regulated by differentiation-specific factors. We investigated how drug exposure affects epidermal expression of CYP1-4 genes, which encode many drug-metabolizing P450s. Real-time polymerase chain reaction (PCR) assays measured CYP1-4 mRNA levels in epidermal keratinocytes differentiated in vitro in the presence of drug or vehicle for 6 days. We confirmed the spinous phenotype at day 6 by changes in cellular morphology and upregulation of cytokeratin 10 and transglutaminase (TGM)1 mRNA in the differentiating keratinocytes. Effects of drug exposure depended on the influence of differentiation-specific factors in controlling epidermal CYP1-4 expression. CYP2C18, 2C19, 2C9, 2W1, 3A4, and 4B1 are up-regulated by cellular differentiation; mRNA levels for these CYP genes were inhibited in differentiating keratinocytes exposed to retinoic acid and aryl hydrocarbon receptor (AhR) ligands. These same drugs effected 相似文献   

Putative link between transcriptional regulation of IgM expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin and the aryl hydrocarbon receptor/dioxin-responsive enhancer signaling pathway

The B-cell, a major cellular component of humoral immunity, has been identified as a sensitive target of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD). The actual molecular mechanism responsible for the immunotoxic effects produced by TCDD is unclear; however, many of the biological effects produced by TCDD are thought to be mediated by the aryl hydrocarbon receptor (AhR). Using the CH12.LX B-cell line, the present studies show that inhibition of mu gene expression and IgM protein secretion by polychlorinated dibenzo-p-dioxin congeners follow a structure-activity relationship for AhR binding. Furthermore, these effects may be mediated by the two dioxin-responsive enhancer (DRE)-like sites that were identified within the Ig heavy chain 3'alpha-enhancer. Electrophoretic mobility shift assay-Western analysis demonstrated TCDD-induced binding of the AhR nuclear complex to both DRE-like sites as well as TCDD-induced binding of several nuclear factor-kappa B/Rel proteins to a kappa B site, which overlaps one of the DRE-like sites. Interestingly, kappa B binding in the AhR-deficient BCL-1 B-cells was also induced by TCDD, demonstrating an AhR-independent effect of TCDD on kappa B binding. Taken together, these results support an AhR/DRE-mediated mechanism for TCDD-induced inhibition of IgM expression.     

Suppression of cytochrome P450 2E1 promoter activity by interferon-gamma and loss of response due to the -71G>T nucleotide polymorphism of the CYP2E1*7B allele

The CYP2E1*7B allele is defined by two nucleotide sequence polymorphisms, -71G>T and -333T>A. The CYP2E1 promoter sequence flanking the -71G nucleotide is consistent with a gamma-interferon activated sequence. Inflammation and interferon (IFN)-gamma suppress expression of CYP2E1 in vivo; however, the exact mechanism is not known. The objectives of this study were to determine whether the CYP2E1 promoter is regulated by IFN-gamma and to examine the influence of the nucleotide substitutions on this function. Treatment of HepG2 cells with IFN-gamma, after transient transfection with a luciferase reporter gene bearing the native CYP2E1 (-71G) promoter sequence resulted, in a dose-dependent reduction of luciferase activity. In contrast, no suppression was observed in cells transfected with the *7B allele promoter (-333A and -71T) nor a CYP2E1 plasmid containing only the -71T polymorphism. These data indicate that IFN-gamma suppresses native CYP2E1 promoter activity and that the -71G is critical for this response.     

kir3dl1启动子表达调控载体的构建及其在K562细胞中的活性

为了分析kir3dl1基因核心启动子区域的功能并明确其表达调控机制，构建了kir3dl1基因启动子．荧光素酶报告载体，分析其在K562细胞中的活性。采用PCR方法从含有kit3dl1基因转录起始位点5’侧翼区的质粒中扩增kir3dl1基因核心启动子序列，插入经Bg1II和NcoI双酶切的荧光素酶报告载体pGL3-Basic；采用阳离子脂质体SuperFect包裹荧光素酶报告重组子转染K562细胞，应用双荧光素酶检测试剂盒测定荧光素酶活性；采用MTT法检测脂质体-DNA复合物对细胞存活率的影响。结果表明：成功构建了含有254bp的kir3dl1基因核心启动子序列的荧光素酶报告重组子3DL1-luc254并通过酶切及基因测序方法的鉴定；荧光素酶报告重组子在K562细胞中的荧光素酶活性明显高于阴性对照，且荧光素酶活性、相对活性持续3天无明显衰减。转染了3DLl-luc254报告质粒的K562细胞存活率在76％-92％之间。结论：成功构建了kir3dl1基因启动子-荧光素酶报告载体，本研究采用的转染系统能够有效地在K562细胞中进行基因转染，kir3dl1基因核心启动子在K562细胞中具有较高活性。     

Differential role of organic anion-transporting polypeptides in estrone-3-sulphate uptake by breast epithelial cells and breast cancer cells

The purpose of this study was to investigate the differential expression and function of organic anion-transporting polypeptides (OATPs) in breast epithelial and breast cancer cells. Estrone-3-sulfate (E3S), a substrate for 7 of 11 OATPs, is a predominant source of tumor estrogen in postmenopausal, hormone-dependent patients with breast cancer. Overexpression of certain OATPs (e.g., OATP1A2) reported in breast tumor tissues compared with surrounding normal tissues could contribute toward two to three times higher tumoral E3S concentration. Little is known about expression and function of other OATP family members among breast epithelial and breast cancer cells. We therefore compared gene and protein expression of seven OATPs (OATP1A2, OATP1B1, OATP1B3, OATP1C1, OATP2B1, OATP3A1, and OATP4A1) in immortalized breast epithelial cells (MCF10A), hormone-dependent breast cancer cells (MCF7), and hormone-independent breast cancer cells (MDA/LCC6-435, MDA-MB-231, and MDA-MB-468) by quantitative polymerase chain reaction and immunoblotting, respectively. Expression of solute carrier superfamily encoding for OATPs (SLCO) 1A2, 1B1, 1B3, 2B1, and 3A1 is exclusive, similar, or significantly higher in cancer cells compared with MCF10A cells. Protein expression of OATPs is found to be either exclusive or higher in cancer cells compared with MCF10A cells. Specificity of OATP-mediated E3S uptake is observed only in cancer cells, with the highest total uptake in MCF7 cells. Transport kinetics of E3S uptake demonstrates transport efficiency that is 10 times greater in the MCF7 cells than in the hormone-independent cells. These data suggest that OATPs could be a novel therapeutic target for hormone-dependent breast cancers, particularly in postmenopausal patients, where the major source of tumor estrogen is E3S.     

mdr1和GSTπ基因缄默逆转K562/A02细胞多药耐药性的研究

目的研究短发夹状小分子干扰RNA(short hairpin RNA,shRNA)对白血病多药耐药细胞株K562/A02mdr1和谷胱甘肽S-转移酶(GST)π基因的表达和功能的影响。方法根据mdr1mRNA第79~99位和GSTπmRNA第308~327位核苷酸为作用靶点,合成针对靶区域序列的shRNA,克隆入pSilencer2.1-U6neo,克隆产物为pSilence-mdr1和pSilence-GSTπ,转染K562/A02细胞株。用实时荧光定量PCR检测K562/A02细胞mdr1和GSTπmRNA的表达;MTT法检测阿霉素对K562/A02细胞半数抑制浓度(IC50)。结果经pSilence-mdr1转染后的K562/A02细胞mdr1mRNA表达量下降了71.5%,从(2.80±1.65)×108拷贝/μg RNA下降至(3.90±2.37)×107拷贝/μg RNA(P<0.01);同时pSilence-GSTπ作用后,K562/A02细胞GSTπmRNA表达量较对照组下降了39.8%,从(2.30±1.14)×105拷贝/μg RNA下降至(5.40±2.45)×104拷贝/μg RNA(P<0.01);空载体转染后阿霉素的耐药指数为23,pSilence-mdr1转染后为8,pSilence-GSTπ转染后为10,差异有统计学意义(P<0.01)。结论shRNA可有效逆转K562/A02细胞mdr1和GSTπ的多药耐药性。     

miR-335 通过下调Fra-1 表达抑制人乳腺癌细胞增殖机制的实验研究

目的　探讨微小核糖核酸（microRNA,miR）-335 对人乳腺癌细胞增殖能力的影响,以及其可能存在的机制。方法　体外培养乳腺癌细胞及正常乳腺组织细胞,检测miR-335 及Fros 相关抗原1(fros related antigent-1,Fra-1) 的表达量;体外转染miR-335 mimics 后,通过细胞活力检测试剂盒(cell counting kit-8,CCK-8) 检测细胞的增殖能力,检测Fra-1 的表达变化及下游细胞增殖相关蛋白分子基质金属蛋白酶9（matrix metalloproteinase-9,MMP-9）、血管内皮生长因子C(vascular endothelial growth factor- C,VEGF-C) 的表达量;生物信息学预测及双荧光霉素报告基因验证Fra-1 为miR-335作用靶基因。结果　乳腺癌细胞中miR-335 的表达量（0.755±0.034）低于正常乳腺细胞（1.495±0.029）,Fra-1 蛋白的表达量（2..347±0.120）高于正常乳腺细胞（1.319±0.038）,差异均有统计学意义（t=0.075,4.191, 均P ＜ 0.001）。转染miR-335 mimic 后48,72 h 乳腺癌细胞增殖能力（0.881±0.062,0.887±0.082）低于对照组细胞（1.326±0.051,1.493±0.038）,差异均有统计学意义（t=44.096,59.307, 均P ＜ 0.001）;转染miR-335 mimic 后乳腺癌细胞中Fra-1的蛋白表达量（0.567±0.091）低于未转染细胞（2.347±0.204）,差异有统计学意义（t=3.763, P<0.001）;转染miR-335 mimic 后细胞中MMP-9（0.469±0.027）,VEGF-C（0.540±0.041）的蛋白表达量低于对照组（0.958±0.058,1.024±0.171）,差异均有统计学意义（t=1.953,7.856, 均P ＜ 0.001）;荧光霉素报告基因实验结果显示miR-335 下调Fra-1 启动子核心转录区域（-164 ～ -52nt）的转录活性。结论　miR-335 通过抑制MMP-9 和VEGF-C 的表达,并下调Fra-1 启动子转录活性,抑制了体外乳腺癌细胞的增殖。     

miR-152通过调控FOXR2表达抑制人前列腺癌细胞增殖的研究

目的探讨人前列腺癌PC-3细胞中miR-152调控叉头框蛋白R2(FOXR2)对细胞增殖的影响。方法采用实时荧光定量PCR检测人正常前列腺上皮细胞RWPE-1和前列腺癌PC-3细胞中miR-152、FOXR2 mRNA的相对表达水平,Western blot检测FOXR2蛋白水平。miR-152 mimics、miR-152 inhibitor或FOXR2-siRNA转染PC-3细胞后,观察细胞增殖能力的变化。miR-152 mimics、miR-152 inhibitor分别与FOXR23′UTR双荧光素报告基因质粒共转染PC-3细胞,检测荧光素酶活性。miR-152 mimics和miR-152 inhibitor转染PC-3细胞后,检测miR-152、FOXR2 mRNA的相对表达水平及FOXR2蛋白水平。结果与RWPE-1细胞比较,PC-3细胞中miR-152的相对表达水平显著降低(P=0.001),而FOXR2 mRNA的相对表达水平及蛋白水平显著升高(P=0.003、0.003)。miR-152 mimics、miR-152 inhibitor或FOXR2-siRNA转染PC-3细胞后,细胞增殖能力分别显著降低、升高、降低(P=0.022、0.029、0.006)。miR-152 mimics和FOXR23′UTR野生型质粒共转染后荧光素酶活性被显著抑制(P=0.001),而共转染miR-152 inhibitor可显著增加荧光素酶活性(P=0.001)。与对照组比较,miR-152 mimics转染PC-3细胞后,miR-152的相对表达水平显著升高(P<0.001),而FOXR2 mRNA的相对表达水平及蛋白水平显著降低(P<0.001、0.001),细胞活性显著降低(P=0.013);miR-152 inhibitor转染PC-3细胞后,miR-152的相对表达水平显著降低(P<0.001),而FOXR2 mRNA的相对表达水平及蛋白水平显著升高(P<0.001、P=0.007),细胞活性显著升高(P=0.018)。结论miR-152可通过负调控FOXR2表达发挥抑制人前列腺癌PC-3细胞增殖的作用。     

Developmental expression of aryl, estrogen, and hydroxysteroid sulfotransferases in pre- and postnatal human liver

Aryl- (SULT1A1), estrogen- (SULT1E1), and hydroxysteroid- (SULT2A1) sulfotransferases (SULTs) are active determinants of xenobiotic detoxication and hormone metabolism in the adult human liver. To investigate the role of these conjugating enzymes in the developing human liver, the ontogeny of immunoreactive SULT1A1, SULT1E1, and SULT2A1 expression was characterized in a series of 235 pre- and postnatal human liver cytosols ranging in age from early gestation to a postnatal age of 18 years. Interindividual variability in expression levels was apparent for all three SULTs in pre- and postnatal liver samples. Expression of the three SULTs displayed distinctly different developmental profiles. Semiquantitative Western blot analyses indicated that SULT1A1 and SULT2A1 immunoreactive protein levels were readily detectable in the majority of developmental human liver cytosols throughout the prenatal period. Whereas SULT1A1 expression did not differ significantly among the various developmental stages, SULT2A1 expression increased during the third trimester of gestation and continued to increase during postnatal life. By contrast, SULT1E1, a cardinal estrogen-inactivating enzyme, achieved the highest levels of expression during the earliest periods of gestation in prenatal male livers, indicating a requisite role for estrogen inactivation in the developing male. The present analysis suggests that divergent regulatory mechanisms are responsible for the differential patterns of hepatic SULT1A1, SULT1E1, and SULT2A1 immunoreactive protein levels that occur during pre- and postnatal human development, and implicates a major role for sulfotransferase expression in the developing fetus.