955 resultados para Expression pattern
Resumo:
The ATP-binding cassette transporter A1 (ABCA1) mediates the transport of cholesterol, phospholipids, and other lipophilic molecules across cellular membranes. Recent data provide evidence that ABCA1 plays an important role in placental function but the exact cellular sites of ABCA1 action in the placenta remain controversial. To clarify this issue, we analyzed the cellular and subcellular localization of ABCA1 with immunocytochemistry, immunofluorescence and subsequent confocal or immunofluorescence microscopy in different types of isolated primary placenta cells: cytotrophoblast cells, amnion epithelial cells, villous macrophages (Hofbauer cells), and mesenchymal cells isolated from chorionic membrane and placental villi. After 12 h of cultivation, primary cytotrophoblast cells showed intensive membrane and cytoplasmic staining for ABCA1. After 24 h, with progressive syncytium formation, ABCA1 staining intensity was markedly reduced and ABCA1 was dispersed in the cytoplasm of the forming syncytial layer. In amnion epithelial cells, placental macrophages and mesenchymal cells, ABCA1 was predominantly localized at the cell membrane and cytoplasmic compartments partially corresponding to the endoplasmic reticulum. In these cell types, the ABCA1 staining intensity was not dependent on the cultivation time. In conclusion, ABCA1 shows marked expression levels in diverse placental cell types. The multitopic localization of ABCA1 in diverse human placental cells not all directly involved in materno-fetal exchange suggests that this protein may not only participate in transplacental lipid transport but could have additional regulatory functions.
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Intravital imaging has revealed that T cells change their migratory behavior during physiological activation inside lymphoid tissue. Yet, it remains less well investigated how the intrinsic migratory capacity of activated T cells is regulated by chemokine receptor levels or other regulatory elements. Here, we used an adjuvant-driven inflammation model to examine how motility patterns corresponded with CCR7, CXCR4, and CXCR5 expression levels on ovalbumin-specific DO11.10 CD4(+) T cells in draining lymph nodes. We found that while CCR7 and CXCR4 surface levels remained essentially unaltered during the first 48-72 h after activation of CD4(+) T cells, their in vitro chemokinetic and directed migratory capacity to the respective ligands, CCL19, CCL21, and CXCL12, was substantially reduced during this time window. Activated T cells recovered from this temporary decrease in motility on day 6 post immunization, coinciding with increased migration to the CXCR5 ligand CXCL13. The transiently impaired CD4(+) T cell motility pattern correlated with increased LFA-1 expression and augmented phosphorylation of the microtubule regulator Stathmin on day 3 post immunization, yet neither microtubule destabilization nor integrin blocking could reverse TCR-imprinted unresponsiveness. Furthermore, protein kinase C (PKC) inhibition did not restore chemotactic activity, ruling out PKC-mediated receptor desensitization as mechanism for reduced migration in activated T cells. Thus, we identify a cell-intrinsic, chemokine receptor level-uncoupled decrease in motility in CD4(+) T cells shortly after activation, coinciding with clonal expansion. The transiently reduced ability to react to chemokinetic and chemotactic stimuli may contribute to the sequestering of activated CD4(+) T cells in reactive peripheral lymph nodes, allowing for integration of costimulatory signals required for full activation.
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We performed a genome-wide analysis of gene expression in primary human CD15+ myeloid progenitor cells. By using the serial analysis of gene expression (SAGE) technique, we obtained quantitative information for the expression of 37,519 unique SAGE-tag sequences. Of these unique tags, (i) 25% were detected at high and intermediate levels, whereas 75% were present as single copies, (ii) 53% of the tags matched known expressed sequences, 34% of which were matched to more than one known expressed sequence, and (iii) 47% of the tags had no matches and represent potentially novel genes. The correct genes were confirmed by application of the generation of longer cDNA fragments from SAGE tags for gene identification (GLGI) technique for high-copy tags with multiple matches. A set of genes known to be important in myeloid differentiation were expressed at various levels and used different spliced forms. This study provides a normal baseline for comparison of gene expression in myeloid diseases. The strategy of using SAGE and GLGI techniques in this study has broad applications to the genome-wide identification of expressed genes.
Resumo:
The micronutrient selenium is essential to human physiology. As the amino acid selenocysteine, it is inserted into selenoproteins with a wide range of functions including antioxidant capacity, thyroid hormone metabolism, improvement of immune system, brain function, fertility and reproduction. Low selenium status has been associated with increased risk for chronic diseases, such as cancer, type-2 diabetes and cardiovascular disease. In this context, several studies have been conducted in order to investigate if selenium supplementation could reduce the risk of such diseases. However, genetic variations may interfere in the response of individuals to a dietary intervention and must be considered as a important source of inter-individual variation. Therefore, this study was conducted was conducted to investigate the influence of genetic variations in selenoproteins genes on the response to an intervention with Brazil nuts, the richest source of selenium known in nature. The study included 130 healthy volunteers with both genders, aged 20 to 60 years old selected in University of São Paulo. They received nuts for 8 weeks, eating one nut a day, and did a washout period for more 8 weeks. All volunteers had a blood sampling collection every 4 weeks during 4 months, in a total of 5. The following analysis were done: anthropometric measurements, lipid profile, plasma malondialdehyde, plasma and erythrocyte Se, selenoprotein P, plasma and erythrocyte GPx activity, gene expression of GPX1, SEPP1, SELS and SEP15. The volunteers were also genotyped for SNPs rs1050450, rs3811699, rs1800699, rs713041, rs3877899, rs7579, rs34713741 and rs5845. Each unit of Brazil nut provided an average of 300 µg of selenium. All 130 volunteers completed the protocol. The concentrations of total cholesterol and glucose decreased after 8 weeks of supplementation. Moreover, HDL concentrations were higher for carriers of the variant T allele for GPX4_rs713041. The frequencies of the variant genotypes were 5,4% for rs1050450, rs3811699 e rs1088668, 10% for rs3877899, 19,2% for rs713041 e rs7579, 11,5% for rs5845 and 8,5% for rs34713741. The levels of the five biomarkers increased significantly after supplementation. In addition, erythrocyte GPx activity was influenced by rs1050450, rs713041 and rs5845; erythrocyte selenium was influenced by rs5845 and plasma selenium by rs3877899. Gene expression of GPX1, SEPP1 and SEP15 were higher after supplementation. The SNP rs1050450 influenced GPX1 mRNA expression and rs7579 influenced SEPP1 mRNA expression. Therefore, it can be concluded that the supplementation with one of Brazil nut for 8 weeks was efficient to reduce total cholesterol and glucose levels and to increase the concentrations of the main biomarkers of selenium status in healthy adults. Furthermore, our results suggest that GPX4_rs713041 might interfere on HDL concentrations and GPx1 activity, GPX1_rs1050450 might interfere on GPx1 activity, SEP15_rs5845 might interfere on GPx1 activity and erythrocyte selenium and SEPP1_3877899 might interfere on plasma Se levels. Therefore, the effect of genetic variations should be considered in future nutritional interventions evaluating the response to Brazil nut supplementation.
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TSLC1 (tumor suppressor in lung cancer-1, IGSF4) encodes a member of the immunoglobulin superfamily molecules, which is involved in cell-cell adhesion. TSLC1 is connected to the actin cytoskeleton by DAL-1 (differentially expressed in adenocarcinoma of the lung-1, EPB41L3) and it directly associates with MPP3, one of the human homologues of a Drosophila tumor suppressor gene, Discs large. Recent data suggest that aberrant promoter methylation is important for TSLC1 inactivation in lung carcinomas. However, little is known about the other two genes in this cascade, DAL-1 and MPP3. Thus, we investigated the expression and methylation patterns of these genes in lung cancer cell lines, primary lung carcinomas and nonmalignant lung tissue samples. By reverse transcription-polymerase chain reaction, loss of TSLC1 expression was observed in seven of 16 (44%) non-small-cell lung cancer (NSCLC) cell lines and in one of 11 (9%) small-cell lung cancer (SCLC) cell lines, while loss of DAL- 1 expression was seen in 14 of 16 (87%) NSCLC cell lines and in four of 11 (36%) SCLC cell lines. By contrast, MPP3 expression was found in all tumor cell lines analysed. Similar results were obtained by microarray analysis. TSLC1 methylation was seen in 13 of 39 (33%) NSC LC cell lines, in one of 11 (9%) SCLC cell lines and in 100 of 268 (37%) primary NSCLCs. DAL-1 methylation was observed in 17 of 39 (44%) NSCLC cell lines, in three of 11 (27%) SCLC cell lines and in 147 of 268 (55%) primary NSCLCs. In tumors of NSCLC patients with stage II-III disease, DAL-1 methylation was seen at a statistically significant higher frequency compared to tumors of patients with stage I disease. A significant correlation between loss of expression and methylation of the genes in lung cancer cell lines was found. Overall, 65% of primary NSCLCs had either TSLC1 or DAL-1 methylated. Methylation of one of these genes was detected in 59% of NSCLC cell lines; however, in SCLC cell lines, methylation was much less frequently observed. The majority of nonmalignant lung tissue samples was not TSLC1 and DAL-1 methylated. Re-expression of TSLC1 and DAL-1 was seen after treatment of lung cancer cell lines with 5-aza-2$-deoxy-cytidine. Our results suggest that methylation of TSLC1 and/or DAL-1, leading to loss of their expression, is an important event in the pathogenesis of NSCLC.
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The base composition pattern (BCP) in the putative promoter region (PPRs) up to 5 Kb lengths of 682 human genes on Chromosome 22 (Chr22) was examined. Two-dimensional (2D) and three-dimensional (3D) functions were designed to delineate the DNA base composition, with four major patterns identified. It is found that 17.6% genes include TATA box, 28.0% GC box, 18.9% CAAT box and 38.4% CpG islands, and approximately 10% genes have one of four putative initiator (Inr) motifs. The occurrence of the promoter elements is tightly associated with the base composition features in the promoter regions, and the associations of the base composition features with occurrence of the promoter elements in the promoter regions mediate tissue-wide expression of the genes in human. The occurrence of two or more promoter elements in the promoter regions is required for the medium- and wide-range expression profiles of the human genes on Chr22. Thus, the reported data shed light on the characteristics of the PPRs of the human genes on Chr22, which may improve our understanding of regulatory roles of the PPRs with occurrence of the promoter elements in gene expression.
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This paper describes a novel framework for facial expression recognition from still images by selecting, optimizing and fusing ‘salient’ Gabor feature layers to recognize six universal facial expressions using the K nearest neighbor classifier. The recognition comparisons with all layer approach using JAFFE and Cohn-Kanade (CK) databases confirm that using ‘salient’ Gabor feature layers with optimized sizes can achieve better recognition performance and dramatically reduce computational time. Moreover, comparisons with the state of the art performances demonstrate the effectiveness of our approach.
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Gabor representations have been widely used in facial analysis (face recognition, face detection and facial expression detection) due to their biological relevance and computational properties. Two popular Gabor representations used in literature are: 1) Log-Gabor and 2) Gabor energy filters. Even though these representations are somewhat similar, they also have distinct differences as the Log-Gabor filters mimic the simple cells in the visual cortex while the Gabor energy filters emulate the complex cells, which causes subtle differences in the responses. In this paper, we analyze the difference between these two Gabor representations and quantify these differences on the task of facial action unit (AU) detection. In our experiments conducted on the Cohn-Kanade dataset, we report an average area underneath the ROC curve (A`) of 92.60% across 17 AUs for the Gabor energy filters, while the Log-Gabor representation achieved an average A` of 96.11%. This result suggests that small spatial differences that the Log-Gabor filters pick up on are more useful for AU detection than the differences in contours and edges that the Gabor energy filters extract.
Resumo:
When classifying a signal, ideally we want our classifier to trigger a large response when it encounters a positive example and have little to no response for all other examples. Unfortunately in practice this does not occur with responses fluctuating, often causing false alarms. There exists a myriad of reasons why this is the case, most notably not incorporating the dynamics of the signal into the classification. In facial expression recognition, this has been highlighted as one major research question. In this paper we present a novel technique which incorporates the dynamics of the signal which can produce a strong response when the peak expression is found and essentially suppresses all other responses as much as possible. We conducted preliminary experiments on the extended Cohn-Kanade (CK+) database which shows its benefits. The ability to automatically and accurately recognize facial expressions of drivers is highly relevant to the automobile. For example, the early recognition of “surprise” could indicate that an accident is about to occur; and various safeguards could immediately be deployed to avoid or minimize injury and damage. In this paper, we conducted initial experiments on the extended Cohn-Kanade (CK+) database which shows its benefits.
Resumo:
In automatic facial expression detection, very accurate registration is desired which can be achieved via a deformable model approach where a dense mesh of 60-70 points on the face is used, such as an active appearance model (AAM). However, for applications where manually labeling frames is prohibitive, AAMs do not work well as they do not generalize well to unseen subjects. As such, a more coarse approach is taken for person-independent facial expression detection, where just a couple of key features (such as face and eyes) are tracked using a Viola-Jones type approach. The tracked image is normally post-processed to encode for shift and illumination invariance using a linear bank of filters. Recently, it was shown that this preprocessing step is of no benefit when close to ideal registration has been obtained. In this paper, we present a system based on the Constrained Local Model (CLM) which is a generic or person-independent face alignment algorithm which gains high accuracy. We show these results against the LBP feature extraction on the CK+ and GEMEP datasets.
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In automatic facial expression recognition, an increasing number of techniques had been proposed for in the literature that exploits the temporal nature of facial expressions. As all facial expressions are known to evolve over time, it is crucially important for a classifier to be capable of modelling their dynamics. We establish that the method of sparse representation (SR) classifiers proves to be a suitable candidate for this purpose, and subsequently propose a framework for expression dynamics to be efficiently incorporated into its current formulation. We additionally show that for the SR method to be applied effectively, then a certain threshold on image dimensionality must be enforced (unlike in facial recognition problems). Thirdly, we determined that recognition rates may be significantly influenced by the size of the projection matrix \Phi. To demonstrate these, a battery of experiments had been conducted on the CK+ dataset for the recognition of the seven prototypic expressions - anger, contempt, disgust, fear, happiness, sadness and surprise - and comparisons have been made between the proposed temporal-SR against the static-SR framework and state-of-the-art support vector machine.
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The use of adherent monolayer cultures have produced many insights into melanoma cell growth and differentiation, but often novel therapeutics demonstrated to act on these cells are not active in vivo. It is imperative that new methods of growing melanoma cells that reflect growth in vivo are investigated. To this end, a range of human melanoma cell lines passaged as adherent cultures or induced to form melanoma spheres (melanospheres) in stem cell media have been studied to compare cellular characteristics and protein expression. Melanoma spheres and tumours grown from cell lines as mouse xenografts had increased heterogeneity when compared with adherent cells and 3D-spheroids in agar (aggregates). Furthermore, cells within the melanoma spheres and mouse xenografts each displayed a high level of reciprocal BRN2 or MITF expression, which matched more closely the pattern seen in human melanoma tumours in situ, rather than the propensity for co-expression of these important melanocytic transcription factors seen in adherent cells and 3D-spheroids. Notably, when the levels of the BRN2 and MITF proteins were each independently repressed using siRNA treatment of adherent melanoma cells, members of the NOTCH pathway responded by decreasing or increasing expression, respectively. This links BRN2 as an activator, and conversely, MITF as a repressor of the NOTCH pathway in melanoma cells. Loss of the BRN2-MITF axis in antisense-ablated cell lines decreased the melanoma sphere-forming capability, cell adhesion during 3D-spheroid formation and invasion through a collagen matrix. Combined, this evidence suggests that the melanoma sphere-culture system induces subpopulations of cells that may more accurately portray the in vivo disease, than the growth as adherent melanoma cells.
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Large margin learning approaches, such as support vector machines (SVM), have been successfully applied to numerous classification tasks, especially for automatic facial expression recognition. The risk of such approaches however, is their sensitivity to large margin losses due to the influence from noisy training examples and outliers which is a common problem in the area of affective computing (i.e., manual coding at the frame level is tedious so coarse labels are normally assigned). In this paper, we leverage the relaxation of the parallel-hyperplanes constraint and propose the use of modified correlation filters (MCF). The MCF is similar in spirit to SVMs and correlation filters, but with the key difference of optimizing only a single hyperplane. We demonstrate the superiority of MCF over current techniques on a battery of experiments.
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To examine matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinases (TIMP) mRNA levels in archival breast cancer biopsies, we employed microdissection to separate tumour tissue from the surrounding breast tissue, or stroma and RT-PCR to determine gross qualitative and small quantitative differences in the patterns of expression. In this study, a significant correlation (p < 0.05, by Mann-Whitney U analysis) between TIMP-2 expression and lymph node involvement was identified, while MMP-11 and TIMP-1 expression patterning also significantly (p < 0.05) differed between those tumours showing calcification and those that did not. When compared by Spearmans’ ρ correlation analysis, a significant association (p < 0.05, ρ = 0.404) was identified in the pattern of MMP-2 and MMP-9 gene expression. In this study, the use of microdissection and a systematic strategy of RT-PCR analysis have allowed us to investigate localized MMP and MMP inhibitor expression within breast tumours. We have identified patterns of gene expression that may further reveal aspects of breast carcinogenesis, and a robust method for examining changes in clinically important genes using archival biopsies and across stroma-tumour boundaries.