Project description:The low permeability and high selectivity of the blood vessels of the brain and central nervous system (CNS) characterize the blood-brain barrier (BBB). Tight junctions, a lack of fenestrations, and low rates of transcytosis in the endothelial cells of the vasculature prevent passive diffusion of most molecules other than water, gases and some lipid soluble molecules (Obermeier, Daneman, & Ransohoff, 2013). Any additional nutrients must be transported across the barrier with the help of transporter proteins. Two protein families account for most transporters. ABC transporters use ATP to power primary-active transport to move molecules across the BBB against an electrochemical gradient, frequently excluding drugs from entering the brain. Some SLC transporters facilitate transport of solutes along an electrochemical gradient, while others permit secondary-active transport by coupling the flow of a solute traveling down the electrochemical gradient to power another solute against its electrochemical gradient. Brain microvessel endothelial cells (BMEC) from human cerebral cortex were enriched through a homogenization and centrifugation procedure. Two BMEC and two tissue were sequenced with paired-end reads on a SOLiD 5500 Wildfire. Raw data was aligned using LifeScope Genomic Analysis, gene expression determined through Cufflinks, and splice junctions identified by aligning to a custom database of known to known and known to novel junctions. We found numerous examples of transporters with enriched expression in the isolated BMECs compared to whole brain tissue. In total, 131 transporter genes or pseudogenes (109 SLC, 22 ABC) are enriched at least 1.25 fold in BMEC enriched samples, and 57 of these are enriched over 2-fold (50 SLC, 7 ABC). Thirteen genes were found to have at least twice as many counts in BMEC enriched samples than in whole tissue for at least one alternative splice junction. Inversely, 23 genes were found to have at least one alternative splice junction with half as many counts in BMEC enriched samples than in whole tissue.
Project description:Krohn2011 - Cerebral amyloid-β
proteostasis regulated by membrane transport protein ABCC1
This model is described in the article:
Cerebral amyloid-β
proteostasis is regulated by the membrane transport protein
ABCC1 in mice.
Krohn M, Lange C, Hofrichter J,
Scheffler K, Stenzel J, Steffen J, Schumacher T, Brüning T,
Plath AS, Alfen F, Schmidt A, Winter F, Rateitschak K, Wree A,
Gsponer J, Walker LC, Pahnke J.
J. Clin. Invest. 2011 Oct; 121(10):
3924-3931
Abstract:
In Alzheimer disease (AD), the intracerebral accumulation of
amyloid-β (Aβ) peptides is a critical yet poorly understood
process. Aβ clearance via the blood-brain barrier is reduced by
approximately 30% in AD patients, but the underlying mechanisms
remain elusive. ABC transporters have been implicated in the
regulation of Aβ levels in the brain. Using a mouse model of AD
in which the animals were further genetically modified to lack
specific ABC transporters, here we have shown that the
transporter ABCC1 has an important role in cerebral Aβ
clearance and accumulation. Deficiency of ABCC1 substantially
increased cerebral Aβ levels without altering the expression of
most enzymes that would favor the production of Aβ from the Aβ
precursor protein. In contrast, activation of ABCC1 using
thiethylperazine (a drug approved by the FDA to relieve nausea
and vomiting) markedly reduced Aβ load in a mouse model of AD
expressing ABCC1 but not in such mice lacking ABCC1. Thus, by
altering the temporal aggregation profile of Aβ,
pharmacological activation of ABC transporters could impede the
neurodegenerative cascade that culminates in the dementia of
AD.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000618.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:The blood-brain barrier (BBB) represents a major challenge when developing central nervous system (CNS)-active therapeutics. The non-human primate (NHP)-brain endothelium constitutes an essential alternative to human in the prediction of molecule trafficking across the BBB and in the search of new brain-specific transport mechanisms. This study presents a comparison between the NHP transcriptome of freshly isolated brain microcapillaries and in vitro-selected brain endothelial cells (BECs), focusing on important BBB features – tight junctions, receptors mediating transcytosis (RMT), ABC and SLC transporters. In vitro BECs conserved most of the BBB key elements for barrier integrity and control of molecular trafficking. We also assessed the function of RMT via the Transferrin Receptor (TFRC) in the characterized NHP-BBB model, where both human transferrin and anti-hTFRC antibody showed increased apical-to-basolateral passage in comparison to control molecules. In parallel, we investigated eventual BBB-related regional differences in 7-day in vitro-selected BECs from 5 brain structures: brainstem, cerebellum, cortex, hippocampus and striatum. Our analysis retrieved very few differences in the brain endothelium from these 5 brain regions, suggesting a rather homogeneous BBB role and function across the brain parenchyma. In conclusion, the presently established NHP-derived BBB model closely mimics the physiological BBB, therefore representing a ready-to-use tool for assessment of the penetration of biotherapeutics into the human CNS.
Project description:Maintenance of central nervous system (CNS) homeostasis requires tight regulation over the metabolites, drugs, cells, and pathogens entering the brain. The blood-brain barrier (BBB) carries out these functions, but the regulatory mechanisms underlying BBB physiology are not completely understood. In addition, the BBB has long been an obstacle to the pharmacologic treatment of CNS diseases, thus molecular model systems that can parse BBB functions and understand the complex integration of sophisticated cellular anatomy and highly polarized chemical protection physiology are desperately needed. In this study, we developed FACS isolation methods for the purification of the surface glia that form the Drosophila BBB. By comparing the transcriptomes (via microarray analyses) of surface glia, FACS isolated neurons, and whole brains, we present a complete catalog of transcripts enriched at the Drosophila BBB. The surface glia transcriptome contains many ABC and SLC transporters, cell adhesion molecules, xenobiotic metabolism pathways, metabolic enzymes, and signaling molecules. Using gene set enrichment analyses and sequence-based comparisons, we compare the Drosophila surface glia to the vertebrate vascular endothelial BBB.
Project description:Knowing the gene expression profiles of drug-metabolizing enzymes and transporters throughout gestation is important for understanding the mechanisms of pregnancy-induced changes in drug pharmacokinetics. In this study, we compared gene expression of drug-metabolizing enzymes and transporters in the maternal liver, kidney, small intestine, and placenta of pregnant mice throughout gestation by microarray analysis. Specifically, we investigated cytochrome P450 (Cyp), UDP-glucuronosyltranserase (Ugt), and sulfotransferase (Sult), as well as ATP-binding cassette (Abc) and solute carrier (Slc) transporters. We found that relatively few Ugt and Sult genes were impacted by pregnancy in maternal tissues and placenta. Cyp1a2, most Cyp2 isoforms, Cyp3a11, and Cyp3a13 in the liver were down-regulated, with the greatest changes occurring on gestation days (gd) 15 and 19 compared to non-pregnant controls (gd 0). However, Cyp2d40, Cyp3a16, Cyp3a41a, Cyp3a41b, and Cyp3a44 in the liver were induced throughout pregnancy. Cyp expression in mid-gestation placenta (gd 10 and 15) was generally greater than that in term placenta (gd 19). There were also notable changes in Abc and Slc transporters. Abcc3 in the liver was down-regulated by 60%, and Abcb1a, Abcc4, and Slco4c1 in the kidney were down-regulated by 30-60% on gd 15 and 19 versus gd 0. Abcc5 in the placenta was induced 3-fold on gd 10 versus gd 15 and 19, whereas Slc22a3 expression in the placenta on gd 10 was 90% lower than that on gd 15 and 19. Overall, this study demonstrates important gestational age-dependent expression of drug-metabolizing enzymes and transporter genes, which may have mechanistic relevance to human pregnancy. Ninety pregnant mice at gestational days 0, 7.5, 10, 15, and 19 (n = 5-6 per gestational age) were used for the maternal liver, kidney, small intestine and placenta. The placentas were collected on gestational days 10, 15, and 19.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.