Neuron-secreted factors induce astrocytic expression of the glutamate transporter, GLT-1 (excitatory amino acid transporter 2). In addition to their elaborate anatomic relationships with neurons, astrocytes also have processes that extend to and envelop the vasculature. Although previous studies have demonstrated that brain endothelia contribute to astrocyte differentiation and maturation, the effects of brain endothelia on astrocytic expression of GLT-1 have not been examined. In this study, we tested the hypothesis that endothelia induce expression of GLT-1 by co-culturing astrocytes from mice that utilize non-coding elements of the GLT-1 gene to control expression of reporter proteins with the mouse endothelial cell line, bEND.3. We found that endothelia increased steady state levels of reporter and GLT-1 mRNA/protein. Co-culturing with primary rat brain endothelia also increases reporter protein, GLT-1 protein, and GLT-1-mediated glutamate uptake. The Janus kinase/signal transducer and activator of transcription 3, bone morphogenic protein/transforming growth factor β, and nitric oxide pathways have been implicated in endothelia-to-astrocyte signaling; we provide multiple lines of evidence that none of these pathways mediate the effects of endothelia on astrocytic GLT-1 expression. Using transwells with a semi-permeable membrane, we demonstrate that the effects of the bEND.3 cell line are dependent upon contact. Notch has also been implicated in endothelia-astrocyte signaling in vitro and in vivo. The first step of Notch signaling requires cleavage of Notch intracellular domain by γ-secretase. We demonstrate that the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester blocks endothelia-induced increases in GLT-1. We show that the levels of Notch intracellular domain are higher in nuclei of astrocytes co-cultured with endothelia, an effect also blocked by N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester. Finally, infection of co-cultures with shRNA directed against recombination signal binding protein for immunoglobulin kappa J, a Notch effector, also reduces endothelia-dependent increases in enhanced green fluorescent protein and GLT-1. Together, these studies support a novel role for Notch in endothelia-dependent induction of GLT-1 expression. Cover Image for this issue: doi. 10.1111/jnc.13825.
Pubmed ID: 28771710 RIS Download
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View all literature mentionsThis polyclonal targets Mouse IgG (H+L)
View all literature mentionsThis polyclonal secondary targets IgG (H+L)
View all literature mentionsThis polyclonal secondary targets IgG (H+L)
View all literature mentionsThis polyclonal targets activated Notch1
View all literature mentionsThis monoclonal targets GFAP
View all literature mentionsThis monoclonal targets beta-actin
View all literature mentionsThis monoclonal targets RBPSUH
View all literature mentionsThis monoclonal targets Phospho-Stat3 (Tyr705)
View all literature mentionsThis monoclonal targets GLAST (ACSA-1)
View all literature mentionsThis monoclonal targets Stat3
View all literature mentionsThis monoclonal targets GFP (green fluorescent protein)
View all literature mentionsCell line HEK293T/17 is a Transformed cell line with a species of origin Homo sapiens (Human)
View all literature mentionsCell line bEnd.3 is a Transformed cell line with a species of origin Mus musculus (Mouse)
View all literature mentionsRattus norvegicus with name Crl:CD(SD) from RGD.
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