Project description:Background: SH-SY5Y cells exhibit a neuronal phenotype when treated with all-trans retinoic acid (RA), but the molecular mechanism of activation in the signaling pathway mediated by phosphatidylinositol 3-kinase (PI3K) is not sufficiently understood. To shed new light on the mechanism, we comprehensively compared the gene expression profiles between SK-N-SH cells and two subtypes of SH-SY5Y cells (SH-SY5Y-A and SH-SY5Y-E), each of which showed a different phenotype during RA-mediated differentiation. Results: SH-SY5Y-A cells differentiated in the presence of RA, whereas RA-treated SH-SY5Y-E cells required additional treatment with brain-derived neurotrophic factor (BDNF) for full differentiation. In combination with perturbation using a PI3K inhibitor, LY294002, we identified 386 genes and categorized them into two clusters dependent on the PI3K signaling pathway during RA-mediated differentiation in SH-SY5Y-A cells. Transcriptional regulation of the gene cluster was greatly reduced in SK-N-SH cells or partially impaired in SH-SY5Y-E cells in coincidence with a defect in the neuronal phenotype of these cell lines. Additional stimulation with BDNF induced a set of neural genes which were down-regulated in RA-treated SH-SY5Y-E cells but were abundant in the differentiated SH-SY5Y-A cells. Conclusions: We identified the gene clusters controlled by PI3K- and TRKB-mediated signaling pathways during differentiation in two subtypes of SH-SY5Y cells. TRKB-mediated bypass pathway compensates for the impaired neural functions generated by defects in several signaling pathways including PI3K in SH-SY5Y-E cells. The expression profiling data are useful for further studies to elucidate the signal transduction-transcriptional network including PI3K and/or TRKB. Experiment Overall Design: Human neuroblastomas, SK-N-SH (HTB-11) and SH-SY5Y-A cells (CRL-2266) were obtained from the American Type Culture Collection (ATCC). We also obtained SH-SY5Y-E cells (EC94030304) from the European Collection of Cell Cultures (ECACC). Tissue culture cells were maintained in D-MEM/F12 1:1 mixture supplemented with 15% FBS (Fetal Bovine Serum) and 1% NEAA (Non-essential amino acid) in a 5% CO2 humidified incubator at 37oC. The culture medium was changed twice a week. For the RA-inducible experiment, random culture cells from two clone subtypes of SH-SY5Y and SK-N-SH were seeded in laminin coated culture dishes (BioCoat Laminin Cellware; BD Biosciences, Billerica, MA, USA) for 1 day and then transferred to a medium containing 10 μM of RA in the presence or the absence of LY294002 (10μM) for five days. For BDNF-induced sequential differentiation of the SH-SY5Y-E strain, cells were washed with D-MEM/F12 twice after five days in the presence of RA and then incubated with 50 ng/ml of BDNF in D-MEM/F12 without serum for three days.

Project description:The Wnt pathway plays a central role in controlling differentiation of epithelial tissues; when Wnt is on, differentiation is suppressed, but when Wnt is off, differentiation is allowed to proceed. Based on this concept, we hypothesized that expression of key genes in the Wnt pathway are suppressed in the human airway epithelium under the stress of cigarette smoking, a stress associated with dysregulation of the differentiated state of the airway epithelium. For this purpose, HG-U133 Plus 2.0 microarrays were used to assess the expression of Wnt-related genes in the small airway (10th-12th generation) epithelium (SAE) obtained via bronchoscopy and brushing of healthy nonsmokers (n=47), healthy smokers (n=58), and smokers with established COPD (n=22). With expression defined as present in >20% of samples, microarray analysis demonstrated that 35 of 57 known Wnt-related genes are expressed in the adult SAE. Wnt pathway downstream targets β-catenin (p<0.05) and the transcription factor 7-like 1 were down-regulated in healthy smokers, and smokers with COPD, as were a number of Wnt target genes, including VEGFA, CCND1, MMP7, CLDN1, SOX9, RHOU (all p<0.05 compared to healthy nonsmokers). As a mechanism to explain this broad, smoking-induced suppression of the Wnt pathway, we assessed expression of the DKK and SFRP families, extracellular regulators that suppress the Wnt pathway. Among these, secreted frizzled-related protein 2 (SFRP2), was up-regulated 4.3-fold (p<0.0001) in healthy smokers and 4.9-fold (p<0.0001) in COPD smokers, an observation confirmed by TaqMan Real-time PCR. AT the protein levels, Western analysis demonstrated SFRP2 up-regulation, and immunohistochemistry demonstrated that the smoking-induced SFRP2 upregulation occurred in differentiated ciliated cells. Finally, cigarette smoke extract mediated up-regulation of SFRP2 and downregulation of Wnt target genes in airway epithelial cells in vitro. These observations are consistent with the hypothesis that the Wnt pathway plays a role in airway epithelial cell differentiation in the adult human airway epithelium, with smoking associated with down-regulation of Wnt pathway, contributing to the dysregulation of airway epithelial differentiation observed in the smoking-related airway disorders. Affymetrix arrays were used to assess gene expression data of genes in the Wnt pathway in small airway epithelium obtained by fiberoptic bronchoscopy of 47 healthy non-smokers and 58 healthy smokers and 22 smokers with COPD.

Project description:The apical junctional complex (AJC), composed of tight junctions and adherens junctions, is essential for maintaining epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are both associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating AJC integrity in the small airway epithelium (SAE), the primary site of pathological changes in COPD. Transcriptome analysis revealed a global down-regulation of physiological AJC gene expression in the SAE of healthy smokers (n=53) compared to healthy nonsmokers (n=59), an observation associated with changes in molecular pathways regulating epithelial differentiation such as PTEN signaling and accompanied by induction of cancer-related AJC genes. Genome-wide co-expression analysis identified a smoking-sensitive AJC transcriptional network. The overall expression of AJC-associated genes was further decreased in COPD smokers (n=23). Exposure of human airway epithelial cells to cigarette smoke extract in vitro resulted in down-regulation of several AJC-related genes, accompanied by decreased transepithelial resistance. Thus, cigarette smoking alters the AJC gene expression architecture in the human airway epithelium, providing a molecular basis for the dysregulation of airway epithelial barrier function during the development of smoking-induced lung disease. The apical junctional complex (AJC), composed of tight junctions and adherens junctions, is essential for maintaining epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are both associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating AJC integrity in the small airway epithelium (SAE), the primary site of pathological changes in COPD. In this study, microarray analysis of the SAE obtained from 53 healthy nonsmokers, 59 healthy smokers, and 23 smokers with COPD was performed to determine physiological AJC gene expression architecture in the SAE and its modification by cigarette smoking and during the development of COPD.

Project description:We have addressed the question of how different rodent species cope with the life-threatening homeostatic challenge of dehydration at the level of transcriptome modulation in the supraoptic nucleus (SON), a specialised hypothalamic neurosecretory apparatus responsible for the production of the antidiuretic peptide hormone arginine vasopressin (AVP). AVP maintains water balance by promoting water conservation at the level of the kidney. Dehydration evokes a massive increase in the regulated release of AVP from SON axon terminals located in the posterior pituitary, and this is accompanied by a plethora of changes in the morphology, electrophysiological properties, biosynthetic and secretory activity of this structure. Microarray analysis was used to generate a definitive catalogue of the genes expressed in the mouse SON, and to describe how the gene expression profile changes in response to dehydration. Comparison of the genes differentially expressed in the mouse SON as a consequence of dehydration with those of the rat has revealed many similarities, pointing to common processes underlying the function-related plasticity in this nucleus. In addition we have identified many genes that are differentially expressed in a species-specific manner. However, in many cases, we have found that the hyperosmotic cue can induce species-specific alterations in the expression of different genes in the same pathway. The same functional end can be served by different means, via differential modulation, in different species, of different molecules in the same pathway. We suggest that pathways, rather than specific genes, should be the focus of integrative physiological studies based on transcriptome data. Animals. Adult male C57BL/6 mice (Harlan Sera-Lab, Loughborough, UK) were group housed (4 per cage) under controlled temperature (21+ 2ºC) and diurnal light conditions (14-h light, 10-h dark, lights on at 05.00). Food and water were available ad libitum until the experiment commenced. Complete fluid deprivation was imposed for 48 hours starting at 11.00 a.m. Control animals maintained free access to drinking water, and both groups had access to standard laboratory rodent chow. Experiments on adult male rats described previously (27). All procedures were conducted in strict accordance with the Animal Scientific Procedures Act (1986), UK, and were approved by the local University of Bristol Ethical Review Process. Tissue collection. Mice were killed using cervical dislocation and the brain was carefully removed from the cranium and snap frozen using powdered dry ice and stored at -80oC for no more than 14 days. Sections of brain (14μm) were cut using an RNase free cryostat and mounted onto RNase free membrane coated glass slides (P.A.L.M. Membrane slides; P.A.L.M. Microlaser Technologies). Immediately after sectioning, frozen sections were thawed and fixed (30s; in 95% [v/v] EtOH), rehydrated (30s in each of 75% [v/v] and 50% [v/v] EtOH) before being stained (60s 1% [v/v] cresyl violet). Sections were then dehydrated in a graded EtOH series (30s in each of 50% [v/v], 75% [v/v] and 95% [v/v]. then 2x 30s in 100% [v/v]). Laser microdissection was performed using a P.A.L.M. MicrolaserSystem (P.A.L.M. Microlaser Technologies). The SON was identified with reference to Franklin and Paxinos (28) and the tissue from each animal was independently pooled into collection vials containing RNAlater® (Ambion, Huntingdon, UK). A single operative carried out all dissections. Total RNA was isolated without delay (within 24h) according to standard procedures that accompany the Ambion RNAqueous MicroKit (Ambion). Microarray analysis. Separate microarrays (n=4) were probed using independently generated target. For each completely independent replicate, tissue from 1 mouse was used for RNA extraction.

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Whole genome expression in human tissues

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