Functional expression of the ecto‐ATPase NTPDase2 and of nucleotide receptors by neuronal progenitor cells in the adult murine hippocampus

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Abstract
An astrocyte‐like cell population corresponding to residual radial glia represents the neuronal progenitors of the adult mammalian hippocampus. We show that radial glia‐like cells of the dentate gyrus express surface‐located ATP‐hydrolyzing activity and are immunopositive for NTPDase2. This enzyme hydrolyzes extracellular nucleoside triphosphates such as ATP and UTP to their nucleoside diphosphates and is thus involved in the control of signaling via P2 receptors. NTPDase2 is expressed from embryonic day 17 onward. In the hippocampus, the embryonic pattern of NTPDase2 expression mirrors that of the dentate migration of neuroblasts. Double‐immunolabeling revealed that NTPDase2 is associated with subpopulations of glial fibrillary acidic protein‐, nestin‐ and doublecortin‐positive radial cells. It is absent from mature granule cells or S100‐positive astrocytes. NTPDase2‐positive cells proliferate. Furthermore, after mitosis, progenitor cells preferentially reveal an NTPDase2‐positive phenotype. Patch‐clamp analysis demonstrates functional nucleotide receptors in progenitor cells expressing nestin promotor‐driven green fluorescent protein. Our results identify the ecto‐nucleotidase NTPDase2 and functional P2X receptors at hippocampal progenitor cells. We infer that signaling pathways via extracellular nucleotides may play a role in the control of hippocampal neurogenesis.