Dataset Information

Homeostatic interactions between chemoprotective functions at the blood-brain barrier

ABSTRACT: The blood-brain barrier (BBB) is an evolutionary conserved tissue interface that possesses potent chemical protection properties functioning to strictly modulate the central nervous system (CNS) microenvironment. These same properties, including tight cellular junctions and efflux transporters, also limit access of CNS-active pharmaceuticals. For this reason, understanding the molecular mechanisms that regulate BBB chemical protection is of great biomedical interest. The BBB of Drosophila consists of two surface glia layers that completely surround the brain. This tissue interface contains both “tight” cellular junctions (termed septate junctions) and drug efflux transporters; thus, the Drosophila BBB can potentially serve as a model for understanding complex regulation of BBB physiology. In this study, we show reciprocal compensatory responses following disruption of critical BBB genes: deletion of the septate junction regulator Moody causes increased drug efflux and up-regulation of the P-glycoprotein ortholog Mdr65; conversely, disruption of Mdr65 expression causes increased septate junction tightness and up-regulation of Moody. We reveal these homeostatic interactions with physiologic observations, gene expression data, and anatomical images of the BBB surface. Whole brain microarray data point to responses that are consistent with our physiologic observations and these responses are likely localized to the BBB. To our knowledge, this is the first observation of a reciprocal compensatory interaction at a tissue barrier. Furthermore, this study paves the way for future studies elucidating the direct pathways that link GPCR signaling and drug transporter regulation at the BBB.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE46550 | GEO | 2013/12/31

SECONDARY ACCESSION(S): PRJNA200957

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:The blood-brain barrier (BBB) is an evolutionary conserved tissue interface that possesses potent chemical protection properties functioning to strictly modulate the central nervous system (CNS) microenvironment. These same properties, including tight cellular junctions and efflux transporters, also limit access of CNS-active pharmaceuticals. For this reason, understanding the molecular mechanisms that regulate BBB chemical protection is of great biomedical interest. The BBB of Drosophila consists of two surface glia layers that completely surround the brain. This tissue interface contains both “tight” cellular junctions (termed septate junctions) and drug efflux transporters; thus, the Drosophila BBB can potentially serve as a model for understanding complex regulation of BBB physiology. In this study, we show reciprocal compensatory responses following disruption of critical BBB genes: deletion of the septate junction regulator Moody causes increased drug efflux and up-regulation of the P-glycoprotein ortholog Mdr65; conversely, disruption of Mdr65 expression causes increased septate junction tightness and up-regulation of Moody. We reveal these homeostatic interactions with physiologic observations, gene expression data, and anatomical images of the BBB surface. Whole brain microarray data point to responses that are consistent with our physiologic observations and these responses are likely localized to the BBB. To our knowledge, this is the first observation of a reciprocal compensatory interaction at a tissue barrier. Furthermore, this study paves the way for future studies elucidating the direct pathways that link GPCR signaling and drug transporter regulation at the BBB. The main comparisons are between WT_new, C17 (Moody null), and PMdr65 (Mdr65 null). Since WT_new were processed on a different day than C17 and PMdr65, we also included another WT sample (WT_old) to control for genes that change depending on batch effects. Since the mutants are also in a different genetic background than WT, we also included a control that is in a similar background (UAS_control).

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:The blood-brain barrier (BBB) consists of specific physical barriers, enzymes and transporters, which together maintain the necessary extracellular environment of the central nervous system (CNS). The main physical barrier is found in the CNS endothelial cell, and depends on continuous complexes of tight junctions combined with reduced vesicular transport. Other possible constituents of the BBB include extracellular matrix, astrocytes and pericytes, but the relative contribution of these different components to the BBB remains largely unknown. Here we demonstrate a direct role of pericytes at the BBB in vivo. Using a set of adult viable pericyte-deficient mouse mutants we show that pericyte deficiency increases the permeability of the BBB to water and a range of low-molecular-mass and high-molecular-mass tracers. The increased permeability occurs by endothelial transcytosis, a process that is rapidly arrested by the drug imatinib. Furthermore, we show that pericytes function at the BBB in at least two ways: by regulating BBB-specific gene expression patterns in endothelial cells, and by inducing polarization of astrocyte end-feet surrounding CNS blood vessels. Our results indicate a novel and critical role for pericytes in the integration of endothelial and astrocyte functions at the neurovascular unit, and in the regulation of the BBB. The brain microvascular fragments were isolated from mice with different genotypes, each represented by 3-4 biological replicates. Genotypes 1-2: Platelet derived growth factor-B (PDGF-B) retention-motif knockout (pdgfbret/ret) represent the pericyte-deficient situation, and the heterozygous mice (pdgfbret/+) are used as controls. Genotypes 3-4: Hypomorphic PDGF-B mutants that rescue pdgfb-/- null mice, in which a one copy of a conditionally silent human PDGF-B transgene targeted to the Rosa 26 locus (R26P) is turned on by endothelial-specific expression of Cre recombinase. In this data set these mice are named as Tie2Cre, R26P+/0, pdgfb-/- (representing the pericyte-deficient situation). Mice wt for pdgfb (pdgfb+/+) and carrying one silent copy of R26P (R26P+/0), are used as controls. Genotype 5: Adult Notch3+/+ wildtype (WT).

Project description:Next-generation sequencing (NGS) has significantly facilitated the analysis of the gene profile and elucidated the molecular mechanisms important for specific cell lineage differentiated from human pluripotent stem cells (hPSCs). Here we report the application of RNA-sequencing technology for transcriptome profile of primary human brain microvascular endothelial cells (BMECs) and hPSC-derived BMECs, and comparison of transcriptomes among cells, including hPSCs, mesodermal progenitors, ectodermal progenitors, endodermal progenitors, hBMECs and hPSC-derived BMECs from hPSCs. Four different BMEC samples differentiated from hPSCs by two different methods and hBMECs were performed in IIIumina HiSeq2500. The resulting sequence reads (about 20 million reads per sample) were mapped to human genome (hg19) using HISAT, and the RefSeq transcript levels (FPKMs) were quantified using the python script rpkmforgenes.py. We next analyzed the expression of a subset of genes that regulate key BBB attributes, including tight junctions and molecular transporters. The gene set comprises 20 tight junction-related genes and an unbiased list of all 25 CLDN genes, all 407 solute carrier (SLC) transporters, and all 53 ATP-binding cassette (ABC) transporters regardless of prior knowledge of BBB association. Primary human BMECs expressed 234 of these genes. BMECs differentiated from hPSCs via the defined method expressed many of these same genes (206 of 234 (88%)) as did BMECs differentiated via the UM method (208 of 234 (89%), indicating a close similarity between hPSC-derived BMECs and primary human BMECs with respect to transcripts having likely relevance to BBB function. RNA sequencing was used to compare global gene expression profiles in the hPSC-derived BMECs with BMECs generated from our previously reported co-differentiation system and primary human BMECs. As expected, hPSC-derived BMECs from three independent differentiations clustered closely and were similar to those generated from the undefined UM platform. Moreover, the hPSC-derived BMECs clustered with primary human BMECs and were distinct from undifferentiated hPSCs and hPSC-derived ectoderm, endoderm and mesodermThis study provides detailed transcriptome comparison between hBMECs and hPSC-derived BMECs and unveils important genes related BMEC phenotypes.

Dataset Information

Homeostatic interactions between chemoprotective functions at the blood-brain barrier

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets