Excitatory amino acid transporter 1 supports adult hippocampal neural stem cell self-renewal.

Within the adult mammalian dentate gyrus (DG) of the hippocampus, glutamate stimulates neural stem cell (NSC) self-renewing proliferation, providing a link between adult neurogenesis and local circuit activity. Here, we show that glutamate-induced self-renewal of adult DG NSCs requires glutamate transport via excitatory amino acid transporter 1 (EAAT1) to stimulate lipogenesis. Loss of EAAT1 prevented glutamate-induced self-renewing proliferation of NSCs in vitro and in vivo, with little role evident for canonical glutamate receptors. Transcriptomics and further pathway manipulation revealed that glutamate simulation of NSCs relied on EAAT1 transport-stimulated lipogenesis, likely secondary to intracellular Ca2+ release and glutamate metabolism. Our findings demonstrate a critical, direct role for EAAT1 in stimulating NSCs to support neurogenesis in adulthood, thereby providing insights into a non-canonical mechanism by which NSCs sense and respond their niche. NSCs of passage 4 were plated 75,000 cells per well in a 12 well plate and treated with 1 µM TFB-TBOA or vehicle for 15 minutes prior to the addition of 100 µM glutamate or vehicle (n = 3 wells per treatment). After 48 hours, cells were harvested with Accutase (StemCell technologies) and a subset (approximately 75,000 cells) was pelleted prior to RNA extraction using the NucleoSpin RNA Plus XS kit (Takara) following manufacturer protocol. Assessment of RNA quality with Qubit RNA HS assay kit (Invitrogen) revealed RIN values of at least 8 for all samples.