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At least 469 records · Page 26Linked to original sources
PubMed2005

Targeting gene expression in the mouse somite: adenovirus-mediated gene delivery and whole embryo culture.

We report here a novel approach to direct gene expression in the mouse somite based on the combined application of adenovirus-mediated gene delivery and whole embryo ex vivo culture. As proof of principle, we show functional analysis of somites microinjected with an engineered virus expressing an activated form of Smoothened, the signaling receptor for Sonic Hedgehog (SHH). As adenovirus can infect many embryonic tissues in the mouse, this method may provide an effective alternative to conventional transgenesis for targeted spatial and temporal gene expression.

Adenoviridae↗
PubMed1994

Transformation-associated 86 kDa natural killer target molecule expressed on the mouse, rat and human cell surface.

We previously reported on the 86 kDa natural killer target molecule associated with transformation of the oncogene-transfected rat fibroblasts. This molecule may participate in the lethal hit phase of cytotoxicity by natural killer (NK) cells. Originally, this molecule was defined by mAb109, but mAb109 could react only with rat tumor lines. In this report, to determine whether the 86 kDa molecule could be utilized as a natural killer target molecule in mammalian cells, we developed a polyclonal anti-86 kDa antibody (pAb109). Our data indicated that pAb109 preferentially reacted with NK-susceptible lines such as mouse YAC-1, rat W31 and human K562 cells, but reacted only weakly with NK-resistant mouse EL-4, rat fetal fibroblast WFB and human fetal fibroblast HEPM. In a cytotoxicity experiment, pAb109 F(ab')2 fragments could inhibit the cytolysis by NK cells of W31 and K562 cells. However, these fragments did not inhibit the cytotoxicity of non-NK cells such as CD3+, CD4-, CD8- T cell receptor alpha beta- T cells (presumably gamma delta T cells) to W31 cells. Taken together, these data suggest that the cell transformation-associated 86 kDa molecule may be critical in NK cytotoxicity, and a candidate for the NK target structure in mammalian tumor cells.

3T3 Cells↗
PubMed2006

Inferring direct regulatory targets from expression and genome location analyses: a comparison of transcription factor deletion and overexpression.

BACKGROUND: Effects on gene expression due to environmental or genetic changes can be easily measured using microarrays. However, indirect effects on expression can be substantial. The indirect effects of a perturbation need to be distinguished from the direct effects if we are to understand the structure and behavior of regulatory networks. RESULTS: The most direct way to perturb a transcriptional network is to alter transcription factor activity. Here, for the first time, we compare expression changes and genomic binding in a simple regulon under conditions of both low and high transcription factor activity. Specifically, we assessed the effects on expression and binding due to deletion of the yeast LEU3 transcription factor gene and effects due to elevation of Leu3 activity. Leu3 activity was elevated through overexpression and the introduction of a mutation that renders the protein constitutively active. Genes that are bound and/or regulated by Leu3 under one or both conditions were characterized in terms of their functional annotations and their predicted potential to be bound by Leu3. We also assessed the evolutionary conservation of the predicted binding potential using a novel alignment-independent method. Both perturbations yield genes that are likely to be direct targets of Leu3, including most of the classically defined targets. Additional direct targets are identified by each of the methods. However, experimental and computational criteria suggest that most genes whose expression is affected by the Leu3 genotype are unlikely to be regulated by binding of the protein. CONCLUSION: Most genes that are differentially expressed by Leu3 are not direct targets despite the exceptional simplicity of the regulon, and the unusually direct nature of the perturbations investigated. These conclusions are reached through computational analyses that support and extend chromatin immunoprecipitation data on the identities of direct targets. These results have implications for the interpretation of expression experiments, especially in cases for which chromatin immunoprecipitation data are unavailable, incomplete, or ambiguous.

2-Isopropylmalate Synthase↗
PubMed2002

[In vivo inhibition of hepatitis B virus replication and gene expression by targeted phosphorothioate modified antisense oligodeoxynucleotides].

OBJECTIVE: To investigate the antiviral effect of targeted antisense oligodeoxynucleotides (asODN) in HBV transgenic mice. METHODS: asODN phosphorothioated (5'-CATGCCCCAAAGCCAC-3') targeted to HBV pre-C/C region was synthesized. Gal15-PLL was used as drugs carrier which targeted asODN to mice liver. Twelve mice with positive serum HBsAg, HBV-DNA were divided into the Gal15-PLL-asODN-treated group or the control group randomly. In Gal15-PLL- asODN-treated group, each mouse was injected i.v. asODN 15mug/g weighty/day via tail vein for 12 days successively; while in the control group, each mouse received the same volume normal saline by the same way. RESULTS: In the Gal15-PLL- asODN-treated group, serum HBsAg decreased at the 6th day (P<0.05), and decreased significantly at the 12th day vs pretreatment (P<0.01). The serum HBV DNA of 4/6 mice became negative. Immunohistochemistry test showed lowered HBsAg, HBcAg content in the liver. In contrast, the control group showed no apparent changes. CONCLUSIONS: Gal15-PLL-asODN targeted to pre-C/C region could inhibit HBV replication and gene expression.

Animals↗
PubMed2006

Genetics, gene expression, and targeted therapies in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) represents the most common leukemia among adults in the Western countries. CLL is a remarkably diverse disorder following an extremely variable clinical course. Some patients have an indolent disease that may never require treatment. In others a progressive clinical course is rapidly fatal. CLL affects mainly elderly individuals, but about a third of patients are less than 60 years of age at diagnosis. Traditionally, the therapeutic procedures were aimed at palliation, but over the recent years highly effective and potentially curative approaches such as combined antibody-chemotherapy and autologous or allogeneic stem cell transplantation have been developed. In parallel there has been progress in the understanding of pathogenesis and outcome prediction. The cornerstones to estimate prognosis are the clinical staging systems of Rai and Binet. To refine outcome prediction for individual patients there has been intensive work on biological factors of potential prognostic relevance. Among these, the genetic characteristics of the CLL cells that can be divided into genomic aberrations and the mutation status of the variable segments of immunoglobulin-heavy chain genes (VH) have attained considerable importance. In addition, data on gene expression of CLL cells are accumulating which further characterize the CLL subgroups. In this context, the expression of ZAP-70 has been recognized a useful surrogate marker to predict the VH mutation status and outcome of CLL patients. At present, targeted therapies are focused on humanized antibodies that bind proteins expressed on the surface of CLL cells. The most prominent agents of these are the anti-CD52 antibody alemtuzumab and the anti-CD20 antibody rituximab, which are currently being tested in clinical trials. To identify CLL-specific gene expression products as candidates for targeted therapies will be an important part of CLL research in the next years.

Animals↗
PubMed2005

Target-determined expression of alpha3 isoform of the Na+,K+-ATPase in the somatic nervous system of rat.

Factors that determine the differential expression of isoforms of Na(+),K(+)-ATPase in the nervous system of vertebrates are not understood. To address this question we studied the expression of alpha(3) Na(+),K(+)-ATPase in the L5 dorsal root ganglia (DRG) of developing rat, the normal adult rat, and the adult rat after peripheral axotomy. During development, the first alpha(3) Na(+),K(+)-ATPase-positive DRG neurons appear by embryonic day 21. At birth, the L5 DRG have a full complement (14 +/- 2%) of these neurons. By 15 days after sciatic nerve transection in adult rat, the number of alpha(3) Na(+),K(+)-ATPase-positive DRG neurons and small myelinated L5 ventral root axons decreases to about 35% of control counts. These results combined with data from the literature suggest that the expression of alpha(3) Na(+),K(+)-ATPase by rat somatic neurons is determined by target-muscle spindle-derived factors.

Animals↗
PubMedDate not supplied

Microarray analysis of p53 target gene expression patterns in the spleen and thymus in response to ionizing radiation.

The ability of p53 to induce apoptosis through transactivation of its target genes is critical for its function as a tumor suppressor. To identify the critical p53 target genes that mediate apoptosis through these pathways, we examined p53-dependent apoptosis in vivo where these apoptotic pathways are intact. p53 wild-type and null animals were irradiated and the global p53 gene expression patterns in response to ionizing radiation were examined in two tissues (spleen and thymus) which undergo p53-dependent apoptosis in response to ionizing radiation. We found that the vast majority of genes that increased or decreased in a p53-dependent manner did so in a tissue specific manner. Although the spleen and thymus had similar levels of p53-dependent apoptosis after ionizing radiation, there was very little overlap in the induced or repressed targets. This suggested that distinct targets may mediate apoptosis in these tissues. In addition, these microarray analyses also led to the identification of several novel p53 targets. Several of these targets appear to be involved in known p53 functions such as the induction of apoptosis (bim) or the initiation of DNA repair (DinB). However, some p53 targets (both confirmed and unconfirmed) link p53 to the anti-tumor immune response (MIP 1-alpha). Further characterization of the tissue specific mediators of p53-dependent responses will greatly increase our understanding of p53 function.

Animals↗
PubMed1993

Targeting gene expression to specific cardiovascular cell types in transgenic mice.

Transgenic techniques, which allow the introduction of exogenous genes into the genome of experimental animals, promise to bridge the gap between the in vitro observations made by molecular and cellular biologists on cardiac and vascular cells in tissue culture and the physiology and pathology of the whole organ system. One such application of these techniques is tissue targeting: by genetic manipulation to direct expression of a protein--such as a signaling peptide, a growth factor receptor, or an oncogene involved in cell growth--to a tissue where it normally would not be expressed (or where expression is tightly controlled) by fusing it to the transcriptional control sequences of another gene normally expressed in that tissue. In the cardiovascular system, regulatory sequences for cardiomyocyte-specific proteins, vascular endothelium-specific proteins, and smooth muscle-specific proteins can be used to target heterologous genes to their respective tissues in transgenic animals. The effects that such perturbations have on organ physiology and intracellular and intercellular communication can be observed by applying established physiological and molecular approaches. In this review, we highlight some tissue-specific genes from cardiac and vascular cell types whose regulatory sequences may be used to target heterologous proteins; we discuss neutral "reporter" proteins and signal transduction components as paradigms for the application of this technique; and we briefly touch on the potentials and pitfalls of transgenic approaches to molecular physiology.

Animals↗
PubMed2004

Recognition of facial expressions of emotion by patients with dementia of the Alzheimer type.

Bilateral amygdala damage has been linked with an inability to recognise facial expressions of emotion, particularly the expression of fear. Patients with Alzheimer's disease (AD) suffer from atrophy of the amygdala at an early stage of the disease. It was therefore predicted that AD patients would have more difficulty in two tasks of processing facial expressions of emotion. Thirteen patients diagnosed with probable AD referred to the Oxford Project to Investigate Memory and Ageing (OPTIMA) and 13 age-matched controls enrolled in the programme participated in the study. Participants were shown two tasks, one involved recognising and labelling a target expression, the other matching a target expression with one of four others. The results showed that compared with the controls, the patients were not impaired in recognising any facial expressions of emotion in the labelling task, but were impaired in matching three facial expressions of emotion in the second task. It was speculated that the impairment in the matching task could have been a result of visuospatial dysfunction rather than one of processing emotions.

Aged↗
PubMed2004

Attenuation of SARS coronavirus by a short hairpin RNA expression plasmid targeting RNA-dependent RNA polymerase.

Severe acute respiratory syndrome (SARS) is a highly contagious and sometimes a lethal disease, which spread over five continents in 2002-2003. Laboratory analysis showed that the etiologic agent for SARS is a new type of coronavirus. Currently, there is no specific treatment for this disease. RNA interference (RNAi) is a recently discovered antiviral mechanism in plant and animal cells that induces a specific degradation of double-stranded RNA. Here, we provide evidences that RNAi targeting at coronavirus RNA-dependent RNA polymerase (RDRP) using short hairpin RNA (shRNA) expression plasmids can specifically inhibit expression of extraneous coronavirus RDRP in 293 and HeLa cells. Moreover, this construct significantly reduced the plaque formation of SARS coronaviruses in Vero-E6 cells. The data may suggest a new approach for treatment of SARS patients.

Animals↗
PubMed2002

Expression and targeting of the tight junction protein CLDN1 in CLDN1-negative human breast tumor cells.

Claudins and occludin constitute the major transmembrane proteins of tight junctions (TJs). We have previously identified the human homologue of the murine Cldn1, CLDN1 (SEMP1) that is expressed in normal, mammary gland-derived epithelial cells but is absent in most human breast cancer cell lines. To investigate the potential functions of CLDN1 protein in tumor and normal epithelial cells, we developed an I-NGFR retroviral vector and monoclonal anti-CLDN1 antibody. In subconfluent and confluent breast cancer cells, MDA-MB-435 and MDA-MB-361, endogenous CLDN1 expression was not detected by an anti-CLDN1 monoclonal antibody by Western blot analysis or quantitative RT-PCR. When CLDN1-negative breast cancer cell lines were transduced with a CLDN1 retrovirus the cells express CLDN1 mRNA constitutively as shown by quantitative RT-PCR. Immunofluorescence analyses of the CLDN1 retroviral transduced breast tumor cells using monoclonal antibodies against CLDN1 reveals a subcellular distribution at cell-cell contact sites similar to the CLDN1 homing pattern in T47-D cells, which express endogenous CLDN1. This cell-cell contact co-localization of CLDN1 was evident in CLDN1-transduced breast tumor cells which fail to express occludin protein (MDA-MB-361 and MDA-MB-435) and express relatively little ZO-1 protein (MDA-MB-435), suggesting that other proteins may be responsible for targeting of CLDN1 to cell-cell contact sites. The re-expression of CLDN1 decreases the paracellular flux of 3 and 40 kDa dextran despite the absence of occludin in the MDA-MB-361 tumor cells. Our findings indicate that in CLDN1-negative breast tumor cells, the basal protein partner requirements for physiological homing of the CLDN1 protein are intact, and that CLDN1 gene transfer and protein expression itself might be sufficient to exert a TJ-mediate gate function in metastatic tumor cells even in the absence of other TJ-associated proteins, such as occludin.

Animals↗
PubMed2006

Comparison of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1A1 gene expression profile in lymphocytes from mice, rats, and humans: most potent induction in humans.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exerts its toxicity by binding a transcription factor, the aryl hydrocarbon receptor (AhR). C57BL/6 (C57) mice express AhRs that have high affinity for TCDD, and they strongly express target genes and develop severe toxic effects upon TCDD exposure. By contrast, DBA/2 (DBA) mice have a low-affinity form of AhR, weakly express target genes, and are resistant to TCDD. Although humans express low-affinity AhRs and have been assumed to be refractory to TCDD, their sensitivity to TCDD has yet to be determined. In this study we compared the TCDD-induced CYP1A1 gene expression profiles in lymphocytes from humans, C57 mice, DBA mice, and SD rats to obtain data as a basis for estimating human sensitivity to TCDD. Lymphocyte fractions prepared from the blood of individual humans and animals were cultured with TCDD. Their mRNAs for CYP1A1 and housekeeping genes were measured by RT-PCR or real-time PCR with primers designed for regions that are 100% homologous among each of the genes of all species/strains tested to obtain similar PCR efficiency. TCDD-induced CYP1A1 expression peaked at 2h in DBA mice and SD rats and at 6h in C57 mice and humans. At the peak times human lymphocytes showed the most potent CYP1A1 mRNA induction of the four species/strains tested. These results suggest that human lymphocytes are more sensitive to TCDD than the lymphocytes of mice and rats. Since the AhR-dependent gene expression did not reflect the AhR affinity for TCDD, these results also suggest that AhR-dependent gene expression in lymphocytes is modulated by an as yet unidentified mechanism in addition to the AhR affinity.

Adult↗
PubMed2000

Mice with markedly reduced PACAP (PAC(1)) receptor expression by targeted deletion of the signal peptide.

In an attempt to study the pituitary adenylate cyclase-activating polypeptide (PACAP) type 1 (PAC(1)) receptor (PAC(1)R) function in vivo and to produce a mouse model with altered expression of PAC(1)R, we have used gene targeting in embryonic stem cells to disrupt exon 2 of the PAC(1)R gene, which contains the ATG translation start site and the signal peptide. Un-expectedly, active transcription of PAC(1)R mRNA was detected in the mutant mice; however, exon 1 was spliced to exon 3 (skipping exon 2), and (125)I-PACAP27 binding in brain was greatly reduced. PAC(1)R exon 2(-/-) mice were viable, fertile, and morphologically and histologically indistinguishable from their wild-type counterparts. We next examined the ligand binding and cell surface expression of the mutant receptor lacking the signal peptide in transfected COS-7 cells. (125)I-PACAP27 binding of the mutant receptor was approximately one-tenth of that in the wild-type receptor. Although the wild-type receptor was expressed abundantly in both the plasma membrane and the cytoplasm around the nucleus, the mutant receptor was expressed in the plasma membrane with a markedly reduced level. Digestion of the membranes with endoglycosidase F greatly reduced the size of the wild-type receptor but only slightly reduced that of the mutant receptor. These results demonstrate that the signal peptide is required for efficient cell surface expression and N-linked glycosylation of the PAC(1)R. However, the mutant receptors still functionally coupled to adenylate cyclase in COS-7 cells, suggesting the presence of sufficient spare receptors such that the mutant receptors are capable of activating the second messenger system. We suggest that the mutant mice with markedly reduced PAC(1)R expression can serve as a useful animal model or cell culture system for further studies in PAC(1)R function.

Animals↗
PubMed1998

Glucocorticoids stimulate p21 gene expression by targeting multiple transcriptional elements within a steroid responsive region of the p21waf1/cip1 promoter in rat hepatoma cells.

Glucocorticoids can induce a G1 arrest in the cell cycle progression of BDS1 rat hepatoma cells. In these cells, dexamethasone, a synthetic glucocorticoid, stimulated a rapid and selective increase in expression of the p21 cyclin-dependent kinase (CDK) inhibitor mRNA and protein and virtually abolished CDK2 phosphorylation of the retinoblastoma protein. Expression of the p27 CDK inhibitor, and other G1-acting cell cycle proteins, remained unaffected. Dexamethasone stimulated p21 promoter activity in a p53-independent manner that required functional glucocorticoid receptors. Transforming growth factor-beta, which also induced a G1 cell cycle arrest of the hepatoma cells, failed to elicit this response. Analysis of 5' deletions of the p21 promoter uncovered a glucocorticoid responsive region between nucleotides -1481 and -1184, which does not contain a canonical glucocorticoid response element but which can confer dexamethasone responsiveness to a heterologous promoter. Fine mapping of this region uncovered three distinct 50-60-base pair transcriptional elements that likely function as targets of glucocorticoid receptor signaling. Finally, ectopic expression of p21 had no effect on hepatoma cell growth in the absence of glucocorticoids but facilitated the ability of dexamethasone to inhibit cell proliferation. Thus, our results have established a direct transcriptional link between glucocorticoid receptor signaling and the regulated promoter activity of a CDK inhibitor gene that is involved in the cell cycle arrest of hepatoma cells.

Animals↗
PubMed2006

Expression and targeting of CX3CL1 (fractalkine) in renal tubular epithelial cells.

The chemokine CX3CL1 plays a key role in glomerulonephritis and can act as both chemoattractant and adhesion molecule. CX3CL1 also is upregulated in tubulointerstitial injury, but little is known about the subcellular distribution and function of CX3CL1 in renal tubular epithelial cells (RTEC). Unexpectedly, it was found that CX3CL1 is expressed predominantly on the apical surface of tubular epithelium in human renal transplant biopsy specimens with acute rejection or acute tubular necrosis. For studying the targeting of CX3CL1 in polarized RTEC, MDCK cells that expressed untagged or green fluorescent protein-tagged CX3CL1 were generated. The chemokine was present on the apical membrane and in subapical vesicles. Apical targeting of CX3CL1 was not due to signals that were conferred by its intracellular domain, to associations with lipid rafts, or to O-glycosylation but, rather, depended on N-linked glycosylation of the protein. With the use of fluorescence recovery after photobleaching, it was found that CX3CL1 is immobile in the apical membrane. However, CX3CL1 partitioned with the triton-soluble rather than -insoluble cellular fraction, indicating that it is not associated directly with the actin cytoskeleton or with lipid rafts. Accordingly, disruption of rafts through cholesterol depletion did not render CX3CL1 mobile. For exploration of potential functions of apical CX3CL1, binding of CX3CR1-expressing leukocytes to polarized RTEC was examined. Leukocyte adhesion to the luminal surface was enhanced significantly when CX3CL1 was present. These data demonstrate that CX3CL1 is expressed preferentially on the apical membrane of RTEC and suggest a novel function for the chemokine in recruitment and retention of leukocytes in tubulointerstitial inflammation.

Animals↗
PubMed1997

Congestive heart failure in rats is associated with increased expression and targeting of aquaporin-2 water channel in collecting duct.

We tested whether severe congestive heart failure (CHF), a condition associated with excess free-water retention, is accompanied by altered regulation of the vasopressin-regulated water channel, aquaporin-2 (AQP2), in the renal collecting duct. CHF was induced by left coronary artery ligation. Compared with sham-operated animals, rats with CHF had severe heart failure with elevated left ventricular end-diastolic pressures (LVEDP): 26.9 +/- 3.4 vs. 4.1 +/- 0.3 mmHg, and reduced plasma sodium concentrations (142.2 +/- 1. 6 vs. 149.1 +/- 1.1 mEq/liter). Quantitative immunoblotting of total kidney membrane fractions revealed a significant increase in AQP2 expression in animals with CHF (267 +/- 53%, n = 12) relative to sham-operated controls (100 +/- 13%, n = 14). In contrast, immunoblotting demonstrated a lack of an increase in expression of AQP1 and AQP3 water channel expression, indicating that the effect on AQP2 was selective. Furthermore, postinfarction animals without LVEDP elevation or plasma Na reduction showed no increase in AQP2 expression (121 +/- 28% of sham levels, n = 6). Immunocytochemistry and immunoelectron microscopy demonstrated very abundant labeling of the apical plasma membrane and relatively little labeling of intracellular vesicles in collecting duct cells from rats with severe CHF, consistent with enhanced trafficking of AQP2 to the apical plasma membrane. The selective increase in AQP2 expression and enhanced plasma membrane targeting provide an explanation for the development of water retention and hyponatremia in severe CHF.

Animals↗
PubMed2006

[Construction and selection of siRNA expression cassettes targeting human telomerase reverse transcriptase gene in vitro].

OBJECTIVE: To determine whether the human telomerase reverse transcriptase (hTERT) gene silencing could be effectively induced by PCR-derived siRNA expression cassettes (SEC) transfected by the fifth generation polyamidoamine dendrimer (G5 PAMAM-D) in Tca8113 cells. METHODS: Four SEC were rationally designed and constructed based on a two-step PCR reaction. The SEC were then transferred into Tca8113 cells using G5 PAMAM-D, and hTERT expression was investigated by real-time fluorescence-quantitative reverse transcriptase-PCR and western blot analysis. RESULTS: The RNA interference effects of the SEC targeted for varying hTERT mRNA positions showed a significant disparity. Among them, SEC-A revealed the most potent inhibitory effects (above 95% of reduction), followed by SEC-D and SEC-C, and SEC-B had no effect on hTERT expression (P > 0.05). That the endogenous hTERT gene silencing induced by G5 PAMAM dendrimer-mediated SEC-A was highly sequence-specific, and multiple transfection as well as properties of the vectors were routinely attributable to the specific suppression. CONCLUSIONS: Specific inhibition of endogenous hTERT expression by use of a PCR-based short hairpin siRNA technique and dendrimer transfer system may serve as a novel strategy for treatment of tongue cancers expressing hTERT in vitro.

Carcinoma, Squamous Cell↗