Poster abstracts
Poster number 91 submitted by Ileanexis Rosado-Burgos
Glutamate Transport Through Excitatory Amino Acid Transporter 1 is Essential for Neural Stem Cell Proliferation, Maintenance and Neurogenesis
Ileanexis Rosado-Burgos (Neuroscience Graduate Program, The Ohio State University), Joshua D. Rieskamp (Neuroscience Graduate Program, The Ohio State University), Liz D. Kirby (Psychology Department, Neuroscience Graduate Program, The Ohio State University)
Abstract:
The generation of new neurons in mammalian adulthood is limited to a small number of discrete areas, most notably the sub granular zone (SGZ) of the hippocampus and the subventricular zone. These new neurons originate from populations of neural stem cells (NSC) that must balance cell division with self-renewal to maintain their own populations throughout life. In the SGZ of the hippocampus, the neurotransmitter glutamate is well known to stimulate self-renewing NSC proliferation and neurogenesis. However, the mechanism of glutamate induced NSC proliferation is unknown. NSCs express glutamate receptors and transporters, but their roles in NSC proliferation is unclear. We identified that glutamate transport through excitatory amino acid transporter 1 (EAAT1) into NSCs, and not stimulation of glutamate receptors, is essential for proliferation of isolated adult NSCs in-vitro. We sought to test the hypothesis that EAAT1 is cell-autonomously essential for proliferation of NSCs in the SGZ in-vivo. To do this, we inhibited EAAT1 expression in adult SGZ NSCs by infusing a lentiviral vector into the DG of adult mice. This vector expressed CRISPR interference (CRISPRi) targeting the EAAT1 gene or a non-targeted (NT) control. A T2A-linked GFP allowed us to differentiate CRISPRi knockdown NSCs from intact neighboring cells within the same mouse. Immunofluorescent labeling revealed effective knockdown of EAAT1 in GFP+ cells by 3 weeks after viral infusion. At that timepoint, we also found that total GFP+ NSCs and proliferating GFP+ NSCs were reduced in EAAT1 knockdown compared to GFP+ NSCs in NT-treated mice. However, GFP- NSCs were not reduced in EAAT1 knockdown vs NT mice, indicating that EAAT1 affects NSC proliferation and maintenance cell-autonomously. In addition, there were fewer total and proliferating immediate progenitor cells and newborn neurons obtained from these GFP+ NSCs in EAAT1 knockdown vs NT mice 2 months after infusion. These findings imply that intracellular transport of glutamate is not only involved in NSC proliferation, but it is also essential for NSC maintenance, and therefore, neurogenesis in a cell-autonomous manner. NSC maintenance throughout life is important as it improves hippocampal-dependent behaviors, such as learning and memory, and emotional regulation.
References:
Rieskamp, JD., Rosado-Burgos, I., Christofi, JE., Ansar, E., Einstein, D., Walters, AE., Valentini, V., Bruno, J., Kirby, ED. (2022). Excitatory amino acid transporter 1 supports adult hippocampal neural stem cell self-renewal. Preprint. 10.1101/2022.10.31.514562.
Keywords: neurogenesis, proliferation, glutamate