Neurogranin (Ng) is a brain specific Calmodulin binding protein involved in synaptic transmission and activity-dependent plasticity through Ca2+ homeostasis regulation. In the adult olfactory bulb (OB), Ng is expressed by a large population of GABAergic interneurons in the granule cell layer. Interestingly, during OB development besides granule cells, Ng is also transiently expressed by neurons located at the boundary between the external plexiform layer (EPL) and the glomerular layer (GL). The Ng-positive apical processes of these neurons extensively arborize forming tufts into the developing glomeruli, in coincidence with active synaptogenesis and glomerular circuitry refinement. Ng-positive neurons display morphological and neurochemical (Tbx21 and CCK expression) features of superficial (ST) and external tufted (ET) cells. Downregulation of Ng expression in these cells occurs within 1 month after birth. In the postnatal life, Ng expression in ST/ET cells is modulated by sensory activity, indeed early olfactory deprivation through unilateral naris closure induces a strong increase in Ng-positive cell density in the EPL-GL region, returning to control conditions at around P30. In contrast, olfactory deprivation or reversible deafferentation during adult life do not modulate Ng expression in the EPL-GL area, confirming Ng regulation in these cells is restricted to developmental stages where it might act as a compensatory mechanism to enhance ST/ET cell sensitivity in response to decreased incoming stimuli. In order to evaluate the possible involvement of Ng in glomerular circuits establishment and refinement we are now analysing Ng-knockout (KO) and Heterozygous (HET) mice by electrophysiological recording and morphological analysis of ST/ET cells expressing LacZ reporter gene. These analyses will contribute to the understanding of Ng role in ST/ET synaptogenesis and in their morphological and functional maturation.
Role of post-synaptic protein Neurograning during olfactory bulb ontongenesis: implication for tufted cell maturation
PIGNATELLI, Angela;BELLUZZI, Ottorino;
2011
Abstract
Neurogranin (Ng) is a brain specific Calmodulin binding protein involved in synaptic transmission and activity-dependent plasticity through Ca2+ homeostasis regulation. In the adult olfactory bulb (OB), Ng is expressed by a large population of GABAergic interneurons in the granule cell layer. Interestingly, during OB development besides granule cells, Ng is also transiently expressed by neurons located at the boundary between the external plexiform layer (EPL) and the glomerular layer (GL). The Ng-positive apical processes of these neurons extensively arborize forming tufts into the developing glomeruli, in coincidence with active synaptogenesis and glomerular circuitry refinement. Ng-positive neurons display morphological and neurochemical (Tbx21 and CCK expression) features of superficial (ST) and external tufted (ET) cells. Downregulation of Ng expression in these cells occurs within 1 month after birth. In the postnatal life, Ng expression in ST/ET cells is modulated by sensory activity, indeed early olfactory deprivation through unilateral naris closure induces a strong increase in Ng-positive cell density in the EPL-GL region, returning to control conditions at around P30. In contrast, olfactory deprivation or reversible deafferentation during adult life do not modulate Ng expression in the EPL-GL area, confirming Ng regulation in these cells is restricted to developmental stages where it might act as a compensatory mechanism to enhance ST/ET cell sensitivity in response to decreased incoming stimuli. In order to evaluate the possible involvement of Ng in glomerular circuits establishment and refinement we are now analysing Ng-knockout (KO) and Heterozygous (HET) mice by electrophysiological recording and morphological analysis of ST/ET cells expressing LacZ reporter gene. These analyses will contribute to the understanding of Ng role in ST/ET synaptogenesis and in their morphological and functional maturation.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
