Maturation of postnatally generated olfactory bulb granule cells depends on functional γ-protocadherin expression

gamma-protocadherins (gamma-pcdhs) are transmembrane receptor proteins ubiquitously expressed in the postnatal and adult mouse brain. gamma-pcdhs are required for normal neuronal development as shown for spinal cord interneurons, retinal ganglion cells and cortical neurons. To test the role of gamma-pcdhs during development of subventricular zone progenitor cells and their subsequent differentiation into olfactory granule cells we generated a conditional gamma-pcdh(lox/lox) allele(gamma-pcdh(lox/lox)) allowing for functional gamma-pcdh inactivation upon lentivirus-mediated Cre-recombinase expression selectively in subventricular zone progenitor cells. While gamma-pcdh loss did not alter the proliferation of subventricular zone progenitors, gamma-pcdh ko progenitors that reached the main olfactory bulb showed a significant reduction in dendritic arborization and failed to develop dendritic spines. Our results suggest that olfactory bulb granule cell maturation necessitates functional gamma-pcdh expression.