Unknown,Transcriptomics,Genomics,Proteomics

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SiRNA profiling of human HepG2 cells with jam-A Knockdown

ABSTRACT: Hepatocytes are polarized epithelial cells whose function depends upon their ability to distinguish between the apical and basolateral surfaces that are located at intercellular tight junctions. It has been proposed that the signaling cascades that originate at these junctions influence cellular activity by controlling gene expression in the cell nucleus. To assess the validity of this proposal with regard to hepatocytes, we depleted expression of the tight junction protein junctional adhesion molecule-A (JAM-A) in the HepG2 human hepatocellular carcinoma cell line. Reduction of JAM-A resulted in a striking change in cell morphology, with cells forming single-layered sheets instead of the normal multi-layered clusters. In the absence of JAM-A, other tight junction proteins were mislocalized, and canaliculi, which form the apical face of the hepatocyte, were consequently absent. While most changes in gene expression were modest, there was a strong transcriptional induction of the adherens junction protein E-cadherin in cells with reduced levels of JAM-A. This increase in E-cadherin was partially responsible for the observed alterations in cell morphology and mislocalization of tight junction proteins. We therefore propose that we have uncovered a novel mechanism for crosstalk between specific components of tight and adherens junctions that can be utilized to regulate adhesion between hepatic cells and to maintain hepatocyte cell polarity. Experiment Overall Design: HepG2 cells were transduced with lentiviruses and stably selected using puromycin. Comparison of four controls and five JAM-A knockdown samples.

ORGANISM(S): Homo sapiens

SUBMITTER: Stephen Duncan

PROVIDER: E-GEOD-6080 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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.

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SiRNA profiling of human HepG2 cells with jam-A Knockdown

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