Biomedical subjects

Dong-Jing Zou

Publications and source records attributed to Dong-Jing Zou.

4 recordsLinked to original sources

PubMed2007

A G protein/cAMP signal cascade is required for axonal convergence into olfactory glomeruli.

The mammalian odorant receptors (ORs) comprise a large family of G protein-coupled receptors that are critical determinants of both the odorant response profile and the axonal identity of the olfactory sensory neurons in which they are expressed. Although the pathway by which ORs activate odor transduction is well established, the mechanism by which they direct axons into proper glomerular relationships remains unknown. We have developed a gain-of-function approach by using injection of retroviral vectors into the embryonic olfactory epithelium to study the ORs' contribution to axon guidance. By ectopically expressing ORs, we demonstrate that functional OR proteins induce axonal coalescence. Furthermore, ectopic expression of Galpha mutants reveals that activation of the signal transduction cascade is sufficient to cause axonal convergence into glomeruli. Analysis of Galpha subunit expression indicates that development and odorant transduction use separate transduction pathways. Last, we establish that the generation of cAMP through adenylyl cyclase 3 is necessary to establish proper axonal identity. Our data point to a model in which axonal sorting is accomplished by OR stimulation of cAMP production by coupling to Galphas.

Animals↗

PubMed2004

High-throughput microarray detection of olfactory receptor gene expression in the mouse.

The large number of olfactory receptor genes necessitates high throughput methods to analyze their expression patterns. We have therefore designed a high-density oligonucleotide array containing all known mouse olfactory receptor (OR) and V1R vomeronasal receptor genes. This custom array detected a large number of receptor genes, demonstrating specific expression in the olfactory sensory epithelium for approximately 800 OR genes previously designated as ORs based solely on genomic sequences. The array also enabled us to monitor the spatial and temporal distribution of gene expression for the entire OR family. Interestingly, OR genes showing spatially segregated expression patterns were also segregated on the chromosomes. This correlation between genomic location and spatial expression provides unique insights about the regulation of this large family of genes.

Age Factors↗

PubMed2004

Postnatal refinement of peripheral olfactory projections.

Axonal projections from the olfactory epithelium to the olfactory bulb are organized into glomeruli according to the expressed odorant receptor. Using gene-targeted mice, we show that glomerular maturation proceeds along different time courses for two similar receptors and requires sensory input during distinct sensitive periods. During early development, some glomeruli are innervated by axons of neurons that do not express the same receptor. These heterogeneous glomeruli normally disappear with age, but they persist in adults deprived of sensory input by unilateral and permanent naris closure. Persistence may be due, in part, to prolonged survival of olfactory sensory neurons.

Animals↗

PubMed2002

Expression pattern of alpha CaMKII in the mouse main olfactory bulb.

Multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is highly enriched at synapses and has been implicated in regulating the formation and function of several sensory systems, including the visual and the somatosensory systems. Although there is evidence for CaMKII expression in the olfactory system, the cellular localization of CaMKII has not been well studied and its function remains unknown. In this study, we examined the normal expression patterns of the predominant alpha CaMKII in the mouse main olfactory bulb. We showed that alpha CaMKII expression levels were high in the olfactory bulb and were developmentally regulated. Immunoreactivity to alpha CaMKII was heavy in the external plexiform layer and the granule cell layer but minimal in the olfactory nerve layer and the glomerular layer. At the cellular level, alpha CaMKII was selectively expressed in the gamma-aminobutyric acid (GABA)ergic granule cells but not in the GABAergic periglomerular cells. Unexpectedly, alpha CaMKII was not detected in the glutamatergic mitral/tufted cells. At the ultrastructural level, alpha CaMKII immunoreactivity was positive in granule cell spines and dendrites, but negative in mitral/tufted cell dendrites. In contrast, in the piriform cortex, as in the majority of cortical regions, alpha CaMKII was expressed in the glutamatergic neurons but not in the GABAergic neurons. Our results set the stage for ongoing investigations of the roles of CaMKII in the formation and function of the olfactory system.

Animals↗