Rather, it appeared uniformly throughout the OE (i.e. glomeruli Dvl-1 expression. White dashed lines demark where positive Dvl-1 glomeruli were observed.(TIF) pone.0056561.s002.tif (1.8M) GUID:?8D77896B-43F5-490D-9BD0-C3BB6F2E0282 Figure S3: Dvl-2 is usually observed in OSN axons and dendritic processes in the glomeruli. Most of Dvl-2 puncta was observed in OSN axon, as evidenced for the colocalization in OMP-GFP expressing mice (circle in A).Nonetheless, some of RGB-286638 them did not colocalized (dashed circle in A). To analyze which cell type expressed these puncta, we stained for Dvl-2 in Thy1-YFP (to label projection neurons, B) and GAD-67-GFP (to label inhibitory interneurons, C), and in both cases we were able to detect some colocalization (arrows in B and C). Expression of Dvl-2 in the OB of GAD-67-GFP mice showed higher levels of colocalization in the EPL (D, E) than in the glomerular layer (D, F). D: green channel was removed in the left part of the image to show the difference in Dvl-2 expression. Nuclei were counterstained with DRAQ5 (blue). Level bar ?=?10 m in A-C, E, F; 20 m in D.(TIF) pone.0056561.s003.tif (9.0M) GUID:?78918A09-03D7-44ED-B5F8-A1D21BCB26F6 Table S1: (DOC) pone.0056561.s004.doc (31K) GUID:?5E925A72-E94E-4F8A-8A11-29C878958EDD Abstract Olfactory sensory neurons (OSNs) project their axons from your olfactory epithelium toward the olfactory bulb (OB) in a heterogeneous and unsorted arrangement. However, as the axons approach the glomerular layer of the OB, axons from OSNs expressing the same odorant receptor (OR) sort and converge to form molecularly homogeneous glomeruli. Axon guidance cues, cell adhesion molecules, and OR induced activity have been implicated in the final targeting of OSN axons to specific glomeruli. Less comprehended, and often controversial, are the mechanisms used by OSN axons to in the beginning navigate from your OE toward the OB. We previously exhibited a role for Wnt and Frizzled (Fz) molecules in OSN axon extension and organization within the olfactory nerve. Building on that we now switched our attention to the downstream signaling cascades from Wnt-Fz RGB-286638 interactions. Dishevelled (Dvl) is usually a key molecule downstream of Fz receptors. Three isoforms of Dvl with specific as well as overlapping functions are found in mammals. Here, we show RGB-286638 that Dvl-1 expression is restricted to OSNs in the dorsal recess of the nasal cavity, and labels a unique subpopulation of glomeruli. Dvl-2 and Dvl-3 have a common distribution in both the OE and OB. Both Dvl-1 and Dvl-2 are associated with intra-glomerular pre-synaptic OSN terminals, suggesting a role in synapse formation/stabilization. Moreover, because Dvl proteins were observed in all OSN axons, we hypothesize that they are important determinants of OSN cell differentiation and axon extension. Introduction Olfactory sensory neuron (OSN) axons face a challenging starting in establishing their final synapse location in the olfactory bulb (OB). Each OSN expresses 1 odorant receptor out of a repertoire of 1200 [1]. OSNs expressing the same odorant receptor are distributed through the olfactory epithelium (OE), intermingled with OSNs expressing different odorant receptors, but the axons from OSNs expressing the same odorant receptor converge in a reduced quantity of glomeruli (1C3 per OB). How this amazing specificity is usually achieved remains controversial and accordingly, myriad molecules have been implicated in the process. Axon guidance molecules [2]C[6], cell adhesion molecules [7]C[9], extracellular molecules [10], [11], odorant receptors [12], [13], and odorant receptor induced electrical activity [14]C[16] have been shown to influence OSN axons and their specific glomerular location. A comprehensive model of how the OSN axons navigate and converge in a specific glomerulus has not yet emerged. Wnts are secreted glycoproteins and Frizzleds (Fz) are 7 transmembrane receptors, together encoding for 29 proteins in the mammalian genome. First described as morphogens, users of the Wnt/Fz family are also implicated in axon guidance and synapse formation, among other processes. We as well as others previously explained the expression pattern of several users of these families in the developing olfactory system [6], [17], and the existence of a subpopulation of olfactory ensheathing cells that activate the Wnt canonical pathway during development, and injury-induced regeneration [6], [17]C[19]. Moreover, we showed that addition of Wnt-5a to dissociated cultured Rabbit Polyclonal to PTTG OSNs induces significant changes in growth cone morphology and concomitant increases in neurite length leading us to suggest that Wnt-Fz interactions may be an important determinant of OSN axon extension [6]. Considering the variety of processes in which Wnt/Fz molecules are involved, and.