Thg‐1pit gene expression in granule cells of the developing mouse brain and in their synaptic targets, mature Purkinje, and mitral cells

We have studied the expression of Thg‐1pit in developing and adult mouse brain by in situ hybridization analysis. We show that, at day 12.5 of embryo development, Thg‐1pit expression is restricted to the rhombic lip, subventricular neuroepithelium/mantle zone, and lateral ganglionic eminence, namely the embryonic brain areas where granule cell precursors originate. Thereafter, Thg‐1pit expression landmarks both differentiative steps and the mature function of granule/interneuron cells in several brain districts, including cerebellum, basal forebrain, olfactory bulb, and hippocampus. In the adult, Thg‐1pit becomes also activated in mitral cells of olfactory bulb and in Purkinje cells of cerebellum, in concomitance with full development of the synaptic contacts that Purkinje and mitral cells establish with granule cells. We conclude that Thg‐1pit is relevant to specification, proliferation/migration, differentiation, and mature function of granule/interneuron cells in different brain districts, as well as to the function of mature, but not immature, Purkinje cells and mitral cells. Developmental Dynamics 234:689–697, 2005. © 2005 Wiley‐Liss, Inc.