Dynamic expression patterns of G protein-regulated inducer of neurite outgrowth 1 (GRIN1) and its colocalization with Galphao implicate significant roles of Galphao-GRIN1 signaling in nervous system.

GRIN1 (Gprin 1) is a signaling molecule coexpression of which with constitutively active form of Galphao can stimulate neurite extensions in Neuro2a cells, yet its in vivo roles remain elusive. Here, we examine expression profiles of GRIN1 during mouse development by in situ hybridization (ISH) and immunohistochemistry. ISH analysis revealed that GRIN1 expression was limited to the nervous system at all developmental stages tested: in the central nervous system, GRIN1 expression occurred within the entire embryonic mantle zones, while it became restricted to sets of nuclei at postnatal to adult stages. Immunohistochemistry using a GRIN1-specific antibody demonstrated that GRIN1 colocalized with Galphao at neuronal dendrites and axons, but it was not detected in glial cells. These results suggest that Galphao-GRIN1 pathway could mediate significant roles in neuronal migration and differentiation at embryonic stages and exert functions in wiring and/or maintenance of specific neural circuitries at postnatal to adult stages.