Project description:Amino acid transporters are expressed in the brain capillary endothelial cells, which form the blood-brain barrier, and their expression levels change during the neonatal period. This study aimed to investigate the molecular mechanisms regulating the amino acid transporter levels in mouse brain capillary endothelial cells. Proteomic analysis revealed arginine depletion-dependent induction of the amino acid transporters, Slc1a4, Slc3a2, Slc7a1, Slc7a5, and Slc38a1. These effects were also inhibited by GCN2iB, suggesting the involvement of eIF2K4 activation. In contrast, expression levels of Slc2a1, Slc16a1, Abcb1b, Abcg2, transferrin receptor, insulin receptor, claudin-1, Zo-1, and Jam1 were not suppressed by GCN2iB.
Project description:Tight homeostatic control of brain amino acids (AA) depends on transport via solute family carrier proteins expressed by the Blood-Brain Barrier (BBB) microvascular endothelial cells (BMEC). To characterize the mouse BMEC transcriptome and probe culture-induced changes microarray analyses of PECAM-1+ endothelial cells (ppMBMECs) were compared with primary MBMECs (pMBMEC) cultured in the presence or absence of glial cells, and with b.End5 endothelioma cell-line. Selected cell marker and AA transporter mRNA levels were further verified by real-time RT PCR. Regardless of glial co-culture expression of a large subset of genes was strongly altered by a brief culture step. This is consistent with the known dependence of BMECs on in vivo interactions to maintain physiological functions, e.g. tight barrier formation, and their consequent de-differentiation in culture. Seven (4F2hc, Lat1, Taut, Snat3, Snat5, Xpct, Cat1) of nine highly in vivo expressed AA transporter mRNAs were strongly down-regulated for all cultures and two (Snat2, Eaat3) were variably regulated. In contrast, five AA transporter mRNAs with low in vivo expression, including y+Lat2, xCT, and Snat1, were strongly up-regulated by culture. We hypothesized that the AA transporters highly expressed in ppMBMECs and strongly down-regulated in culture play a major in vivo role for BBB transendothelial transport. Keywords: culture vs non-cultured RNA was prepared from 4 sources of endothelial cells: 1) isolated mouse brain microvascular endothelial cells that were cultured in transwells with and 2) without non-contact co-culture with glial cultures or 3) further purified using anti-PECAM1 magnetic bead sorting and 4) the endothelioma b.End5 cell-line.
Project description:Tight homeostatic control of brain amino acids (AA) depends on transport via solute family carrier proteins expressed by the Blood-Brain Barrier (BBB) microvascular endothelial cells (BMEC). To characterize the mouse BMEC transcriptome and probe culture-induced changes microarray analyses of PECAM-1+ endothelial cells (ppMBMECs) were compared with primary MBMECs (pMBMEC) cultured in the presence or absence of glial cells, and with b.End5 endothelioma cell-line. Selected cell marker and AA transporter mRNA levels were further verified by real-time RT PCR. Regardless of glial co-culture expression of a large subset of genes was strongly altered by a brief culture step. This is consistent with the known dependence of BMECs on in vivo interactions to maintain physiological functions, e.g. tight barrier formation, and their consequent de-differentiation in culture. Seven (4F2hc, Lat1, Taut, Snat3, Snat5, Xpct, Cat1) of nine highly in vivo expressed AA transporter mRNAs were strongly down-regulated for all cultures and two (Snat2, Eaat3) were variably regulated. In contrast, five AA transporter mRNAs with low in vivo expression, including y+Lat2, xCT, and Snat1, were strongly up-regulated by culture. We hypothesized that the AA transporters highly expressed in ppMBMECs and strongly down-regulated in culture play a major in vivo role for BBB transendothelial transport. Keywords: culture vs non-cultured
Project description:The Blood-Brain Barrier (BBB) is a crucial, selective barrier that regulates the entry of molecules including nutrients, environmental toxins, and therapeutic medications into the brain. This function relies heavily on brain endothelial cell proteins, particularly transporters and tight junction proteins. The BBB continues to develop postnatally, adapting its selective barrier function across different developmental phases, and alters with aging and disease. Here we present a global proteomics analysis focused on the ontogeny and aging of proteins in human brain microvessels (BMVs), predominantly composed of brain endothelial cells. Our proteomic profiling quantified 6,223 proteins and revealed possible age-related alteration in BBB permeability due to basement membrane component changes through the early developmental stage and age-dependent changes in transporter expression. Notable changes in expression levels were observed with development and age in nutrient transporters and transporters that play critical roles in drug disposition. This research 1) provides important information on the mechanisms that drive changes in the metabolic content of the brain with age and 2) enables the creation of physiologically based pharmacokinetic models for CNS drug distribution across different life stages.
Project description:In the present study, the transcriptional analysis of CD biopsies reveals profound alterations in the ileum transportome profile. More than 60 SLC transporters showed different expression pattern compared with the healthy donors, being mostly decreased. Changes were confirmed in almost all the eighteen altered SLCs analyzed by RT-PCR. The results obtained display alterations in amino acid transporters, purinome members, Zn transporters and metallothioneins. All together, these alterations which mainly involve transporters localized at the apical membrane of the enterocyte anticipate impaired amino acid uptake and purinergic responses. Remarkably, incubation of explants with specific commensal bacteria restored almost all CD transportome alterations.
Project description:Cryptococcus neoformans is the most common cause of fungal meningitis, with high mortality and morbidity. The reason for the frequent occurrence of Cryptococcus infection in the central nervous system (CNS) is poorly understood. In this study, we find that inositol plays an important role in the transversal of Cryptococcus across the blood-brain barrier (BBB) both in an in vitro human BBB model and in vivo animal models. The inositol stimulation of BBB crossing is dependent upon fungal inositol transporters. The upregulation of genes involved in the inositol catabolism pathway is evident in a microarray analysis. The expression of CPS1, a gene encoding the hyaluronic acid synthase in Cryptococcus, is also upregulated by the inositol treatment. The production of hyaluronic acid increased in cells treated with inositol, which leads to the enhanced binding ability of Cryptococcus cells to the human brain microvascular endothelial cells (HBMECs) constituting the BBB. Overall, our studies provide a mechanism for inositol-dependent Cryptococcus transversal of the BBB, supporting our hypothesis that host inositol utilization by the fungus contributes to Cryptococcus CNS infection. To understand the effect of inositol on gene expression profiles during cell development, microarray experiments were performed to monitor the genes regulated by inositol. H99 overnight culture was washed with dH2O once, and cells were inoculated on SD medium with or without inositol. Cells were collected from SD plates 24 hr post-inoculation, washed with dH2O, and total RNA was purified. Total RNAs were extracted using Trizol Reagents (Invitrogen) and purified using the Qiagen RNeasy cleanup kit (Qiagen). Cy3 and Cy5-labeled cDNA were generated by incorporating amino-allyl-dUTP during reverse transcription of 5 µg of total RNA as described previously and competitively hybridized to a JEC21 whole-genome array generated previously at Washington University in Saint Louis. After hybridization, arrays were scanned with a GenePix 4000B scanner (Axon Instruments, http://www.axon.com) and analyzed by using GenePix Pro version 4.0 and BRB array tools (developed by Richard Simon and Amy Peng Lam at the National Cancer Institute; http://linus.nci.nih.gov/BRB-ArrayTools.html)
Project description:In the present study, the transcriptional analysis of CD biopsies reveals profound alterations in the ileum transportome profile. More than 60 SLC transporters showed different expression pattern compared with the healthy donors, being mostly decreased. Changes were confirmed in almost all the eighteen altered SLCs analyzed by RT-PCR. The results obtained display alterations in amino acid transporters, purinome members, Zn transporters and metallothioneins. All together, these alterations which mainly involve transporters localized at the apical membrane of the enterocyte anticipate impaired amino acid uptake and purinergic responses. Remarkably, incubation of explants with specific commensal bacteria restored almost all CD transportome alterations. Genome wide transcriptomic profile of Ileal mucosa from five healthy and six Chron's disease samples .
Project description:Brain exposure of systemically administered biotherapeutics is highly restricted by the blood-brain barrier (BBB). Here, we report the engineering and characterization of a BBB transport vehicle targeting the CD98 heavy chain (CD98hc or SLC3A2) of heterodimeric amino acid transporters (TV^CD98hc). The pharmacokinetic and biodistribution properties of a CD98hc antibody transport vehicle (ATV^CD98hc) are assessed in humanized CD98hc knock-in mice and cynomolgus monkeys. Compared to most existing BBB platforms targeting the transferrin receptor, peripherally administered ATVCD98hc demonstrates differentiated brain delivery with markedly slower and more prolonged kinetic properties. Specific biodistribution profiles within the brain parenchyma can be modulated by introducing Fc mutations on ATV^CD98hc that impact FcgR engagement, changing the valency of CD98hc binding, and by altering the extent of target engagement with Fabs. Our study establishes TV^CD98hc as a modular brain delivery platform with favorable kinetic, biodistribution, and safety properties distinct from previously reported BBB platforms.