@article{8d2fe7de3ccd4289b7c2d24503645859,
title = "Polarized hemichannel opening of pannexin 1/connexin 43 contributes to dysregulation of transport function in blood-brain barrier endothelial cells",
abstract = "Dysregulation of blood-brain barrier (BBB) transport exacerbates brain damage in acute ischemic stroke. Here, we aimed to investigate the mechanism of this BBB transport dysregulation by studying the localization and function of pannexin (Px) and connexin (Cx) hemichannels in blood-brain barrier endothelial cells of rat (TR-BBB13 cells) and human (hCMEC/D3 cells) under acute ischemic stroke-mimicking oxygen/glucose deprivation (OGD) and extracellular Ca2+ ([Ca2+]e)-free conditions. TR-BBB13 cells showed increased uptake of hemichannel-permeable sulforhodamine 101, and this increase was markedly inhibited by carbenoxolone, a hemichannel inhibitor. Transcripts of Px1 and Cx43 were detected in TR-BBB13 cells and freshly isolated brain microvascular endothelial cells. The basal compartment-to-cell uptake of hemichannel-permeable propidium iodide was selectively enhanced in hCMEC/D3 cells under [Ca2+]e-free conditions in the basal Transwell chamber. Immunohistochemical analysis revealed the predominant localization of Cx43 on the lateral membranes of hCMEC/D3 cells. [3H]Taurine uptake by hCMEC/D3 cells was significantly reduced in the absence of [Ca2+]e. Functional knock-down of Px1 and Cx43 with mimetic peptides significantly inhibited the increase of ATP release from hCMEC/D3 cells under [Ca2+]e-free conditions. These results suggest that polarized Px1/Cx43 hemichannel opening in brain capillary endothelial cells under acute ischemic stroke-mimicking conditions contributes to dysregulation of BBB transport function, resulting in release of intracellular taurine and ATP.",
keywords = "Acute stroke, Blood-brain barrier, Connexin 43, Hemichannel, Pannexin 1",
author = "Masanori Tachikawa and Koji Murakami and Ryo Akaogi and Akanuma, {Shin ichi} and Tetsuya Terasaki and Hosoya, {Ken ichi}",
note = "Funding Information: We thank Dr. P. O. Couraud (Institut Cochin, Paris, France) for providing the hCMEC/D3 cell line. This study was supported in part by four Grants-in-Aid from the Japanese Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP23790170 , JP25670067 , JP16K15157 , and JP19H03390 , and by the JSPS and Centre National de la Recherche Scientifique (CNRS) under the Japan-France Basic Scientific Cooperation Program . The authors thank A. Niitomi and N. Handa for secretarial assistance. Funding Information: We have shown here that: (i) OGD stimulates hemichannel opening in BBB endothelial cells, (ii) Px1 and Cx43 subtypes are predominantly expressed in isolated BVEC fractions, (iii) hemichannel opening induces selectively the basal compartment-to-endothelial cells transport under extracellular Ca2+-free conditions on the basal side, and (iv) hemichannel opening is functionally involved in the release of taurine and ATP from BBB endothelial cells. These results support the idea that BBB hemichannel opening during the acute stage of ischemia is induced by OGD due to decreased blood flow, as well as by the presence of abnormally low concentrations of extracellular Ca2+ in the brain ISF, and this results in the release of intracellular taurine and ATP from the endothelial cells.We thank Dr. P. O. Couraud (Institut Cochin, Paris, France) for providing the hCMEC/D3 cell line. This study was supported in part by four Grants-in-Aid from the Japanese Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP23790170, JP25670067, JP16K15157, and JP19H03390, and by the JSPS and Centre National de la Recherche Scientifique (CNRS) under the Japan-France Basic Scientific Cooperation Program. The authors thank A. Niitomi and N. Handa for secretarial assistance. Publisher Copyright: {\textcopyright} 2019 Elsevier Ltd",
year = "2020",
month = jan,
doi = "10.1016/j.neuint.2019.104600",
language = "English",
volume = "132",
journal = "Neurochemistry International",
issn = "0197-0186",
publisher = "Elsevier Limited",
}