title: Occludin as direct target for glucocorticoid-induced improvement of blood-brain barrier properties in a murine in vitro system.
abstract: Homeostasis of the central nervous system (CNS) microenvironment is essential for its normal function. It is maintained by the blood-brain barrier (BBB) which regulates the transport of molecules from blood into brain and backwards. The integrity of the BBB is compromised in many disorders of the human CNS; therapeutical strategies for several of these diseases include treatment with glucocorticoids, but the molecular basis of how glucocorticoids regulate BBB permeability is not understood. Here, we report the generation and characterization of a murine immortalized brain (cerebral) capillary endothelial (cEND) cell line which expresses the BBB marker occludin at intercellular tight junctions (TJ). Hydrocortisone at physiological concentrations induced upregulation of occludin, accompanied by a threefold enhancement of transendothelial electrical resistance to values up to 1000 Omegacm2. Insulin enhanced the glucocorticoid response. At the molecular level, hydrocortisone induces increase of occludin at protein and mRNA levels by activation of the glucocorticoid receptor (GR) and its binding to putative glucocorticoid responsive elements in the occludin promoter. At the same time, insulin potentiated the ligand-dependent GR transactivation via induction of the GR in this in vitro system. This study thus provides insights into the molecular processes of barrier genesis, and may help to elucidate mechanisms of brain pathology at the microvascular level.
authors.affiliation: Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstrasse 6, D-97070 Würzburg, Germany. carola.foerster@mail.uni-wuerzburg.de
authors.forename: Carola
authors.initials: C
authors.lastname: Förster
authors.forename: Christine
authors.initials: C
authors.lastname: Silwedel
authors.forename: Nikola
authors.initials: N
authors.lastname: Golenhofen
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Burek
authors.forename: Silke
authors.initials: S
authors.lastname: Kietz
authors.forename: Joachim
authors.initials: J
authors.lastname: Mankertz
authors.forename: Detlev
authors.initials: D
authors.lastname: Drenckhahn
mesh_terms: D000818:Animals; D001483:Base Sequence; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000502:physiology*; D019556:COS Cells; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D004357:Drug Synergism; D017097:Electric Impedance; D042783:Endothelial Cells / Q000166:cytology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007668:Kidney / Q000166:cytology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D062793:Occludin; D011401:Promoter Regions, Genetic / Q000235:genetics; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D005938:Glucocorticoids; D007004:Hypoglycemic Agents; D007328:Insulin; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; D011965:Receptors, Glucocorticoid