title: Aryl hydrocarbon receptor negatively regulates expression of the plakoglobin gene (jup).
abstract: Plakoglobin is an important component of intercellular junctions, including both desmosomes and adherens junctions, which is known as a tumor suppressor. Although mutations in the plakoglobin gene (Jup) and/or changes in its protein levels have been observed in various disease states, including cancer progression or cardiovascular defects, the information about endogenous or exogenous stimuli orchestrating Jup expression is limited. Here we show that the aryl hydrocarbon receptor (AhR) may regulate Jup expression in a cell-specific manner. We observed a significant suppressive effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a model toxic exogenous activator of the AhR signaling, on Jup expression in a variety of experimental models derived from rodent tissues, including contact-inhibited rat liver progenitor cells (where TCDD induces cell proliferation), rat and mouse hepatoma cell models (where TCDD inhibits cell cycle progression), cardiac cells derived from the mouse embryonic stem cells, or cardiomyocytes isolated from neonatal rat hearts. The small interfering RNA (siRNA)-mediated knockdown of AhR confirmed its role in both basal and TCDD-deregulated Jup expression. The analysis of genomic DNA located ~2.5kb upstream of rat Jup gene revealed a presence of evolutionarily conserved AhR binding motifs, which were confirmed upon their cloning into luciferase reporter construct. The siRNA-mediated knockdown of Jup expression affected both proliferation and attachment of liver progenitor cells. The present data indicate that the AhR may contribute to negative regulation of Jup gene expression in rodent cellular models, which may affect cell adherence and proliferation.
authors.affiliation: Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, 61265 Brno, Czech Republic.
authors.forename: Jiřina
authors.initials: J
authors.lastname: Procházková
authors.forename: Markéta
authors.initials: M
authors.lastname: Kabátková
authors.forename: Lenka
authors.initials: L
authors.lastname: Šmerdová
authors.forename: Jiří
authors.initials: J
authors.lastname: Pacherník
authors.forename: Dominika
authors.initials: D
authors.lastname: Sykorová
authors.forename: Jiří
authors.initials: J
authors.lastname: Kohoutek
authors.forename: Pavlína
authors.initials: P
authors.lastname: Šimečková
authors.forename: Eva
authors.initials: E
authors.lastname: Hrubá
authors.forename: Alois
authors.initials: A
authors.lastname: Kozubík
authors.forename: Miroslav
authors.initials: M
authors.lastname: Machala
authors.forename: Jan
authors.initials: J
authors.lastname: Vondráček
mesh_terms: D000818:Animals; D001483:Base Sequence; D002448:Cell Adhesion; D002460:Cell Line; D049109:Cell Proliferation; D003001:Cloning, Molecular; D017931:DNA Primers; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000502:physiology*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D051381:Rats; D011916:Rats, Inbred F344; D060888:Real-Time Polymerase Chain Reaction; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology*; D051185:gamma Catenin / Q000235:genetics*
chemical_list: D017931:DNA Primers; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D051185:gamma Catenin
keywords: aryl hydrocarbon receptor; cardiomyocytes.; cell proliferation; desmosomes; dioxin; liver progenitor cells; plakoglobin