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Author Song, Han ♦ Zheng, Gang ♦ Liu, Yang ♦ Shen, Xue-Feng ♦ Zhao, Zai-Hua ♦ Aschner, Michael ♦ Luo, Wen-Jing ♦ Chen, Jing-Yuan
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ ABSORPTION SPECTROSCOPY ♦ BLOOD ♦ BLOOD-BRAIN BARRIER ♦ BRAIN ♦ CEREBROSPINAL FLUID ♦ CESIUM FLUORIDES ♦ CONCENTRATION RATIO ♦ PHOSPHORS ♦ PHOSPHORYLATION ♦ PROTEINS ♦ UPTAKE ♦ UVEA
Abstract As the structural basis of blood-cerebrospinal fluid barrier (BCB), epithelial cells in the choroid plexus (CP) are targets for lead (Pb). Pb is known to accumulate in the CP; however, the mechanism of Pb uptake in the choroidal epithelial cells remains unknown. Recently, hemichannels of Connexin 43 (Cx43), the most ubiquitously expressed gap junction proteins in the CP, were found to be important pathways for many substances. This study was designed to investigate the roles of Cx43 in Pb uptake in the epithelial cells. Autometallography was used to outline Pb's subcellular location, and the characteristics of Pb transport into CP cells, including concentration- and time-dependence were analyzed by atomic absorption spectroscopy. Knockdown/overexpression of Cx43 with transient siRNA/plasmids transfections before Pb exposure diminished/increased the Pb accumulation. In the Z310 cell-based doxycycline-inducible Cx43 expression cell line (iZCx43), doxycycline induced a significant increase (3-fold) in Pb uptake, corresponding to the increased Cx43 levels. Activation of Cx43 hemichannels by reduced serum conditions caused an increase of Pb concentrations. Cx43-induced Pb uptake was attenuated after blockage of Cx43 hemichannels with its inhibitor, carbenoxolone. Additionally, down-regulation of Cx43 protein levels by Pb exposure paralleled cellular Pb concentrations in the time study. Concomitantly, expressions of phosphor-Src and phosphor-Erk were both significantly increased by Pb. However, inactivation of Erk, not Src pathway, reversed Pb-induced downregulation of Cx43. Taken together, these data establish that Pb can accumulate in the BCB and validate the role of Cx43 hemichannel in Pb uptake and its regulations through Erk phosphorylation. - Highlights: • Pb is sequestrated in choroid plexus both in vivo and in vitro. • Cx43 knockdown/overexpression prevents/increases Pb accumulations. • Cx43 hemichannels are required for Pb uptake. • Pb-induced Erk activation causes reduction of Cx43.
ISSN 0041008X
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-04-15
Publisher Place United States
Journal Toxicology and Applied Pharmacology
Volume Number 297


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