The long term aim of this project is to identify axon guidance molecules involved in establishing the complex topography of the primary olfactory pathway. We previously identified critical time points in development where axon behavior indicates that guidance molecules are acting. Olfactory sensory neuron (OSN) axons grow from the olfactory placode to the telencephalic vesicle in early embryonic development. Axons penetrate the telencephalon, forming a presumptive olfactory nerve layer (pONL). A small subset of axons grow to the ventricular surface which has been suggested to induce the formation of olfactory bulb (OB). The majority of axons remain restricted to the pONL for up to 4 days, presumably sorting out into molecularly defined subsets. After 4 days, some axons grow deeper into the OB, initiating glomerular formation. A pivotal question in understanding olfactory pathway formation is which cue(s) are present in the OB that prevent(s) axon ingrowth prior to glomerular formation? One way to answer this key question is to examine the distributions of candidate guidance molecules within the developing pathway. We hypothesize that the stalling of axons within the pONL may be due to inhibitory guidance molecules within the developing OB. One potential source of inhibitory cues in the OB are components of the extracellular matrix (ECM). We have identified members of the tenascin and chondroitin sulfate proteoglycans (CSPGs) as good candidates for the inhibitory cues that regulate axon ingrowth and glomerular formation.
The specific aims of the current proposal are to: 1) test the hypothesis that components of the ECM are key regulators of OSN axon spatio-temporal dynamics in the developing olfactory pathway, and to functionally test the ability of these molecules to inhibit OSN neurite outgrowth in vitro; 2) to test the hypothesis that both integrin and non-integrin ECM receptors facilitate cell surface - matrix interactions in the developing olfactory system and to functionally test their ability to modulate OSN neurite outgrowth on ECM substrates in vitro; 3) to test the hypothesis that the matrix metallooroteases play an important role in sculpting the ECM environment during development of the olfactory system. These studies will greatly enhance our knowledge of how axons establish connections in the olfactory system and may have implications for diseases such as Kallman's syndrome. Moreover these results will be broadly applicable to other CNS regions where work continues towards understanding the formation of boundaries and topographic maps.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
1R01DC007600-01
Application #
6958377
Study Section
Somatosensory and Chemosensory Systems Study Section (SCS)
Program Officer
Davis, Barry
Project Start
2005-07-01
Project End
2010-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
1
Fiscal Year
2005
Total Cost
$286,125
Indirect Cost
Name
Yale University
Department
Neurosurgery
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Ray, Arundhati; Treloar, Helen B (2012) IgSF8: a developmentally and functionally regulated cell adhesion molecule in olfactory sensory neuron axons and synapses. Mol Cell Neurosci 50:238-49
Miller, Alexandra M; Treloar, Helen B; Greer, Charles A (2010) Composition of the migratory mass during development of the olfactory nerve. J Comp Neurol 518:4825-41
Rodriguez-Gil, Diego J; Treloar, Helen B; Zhang, Xiaohong et al. (2010) Chromosomal location-dependent nonstochastic onset of odor receptor expression. J Neurosci 30:10067-75
Rodriguez-Gil, Diego J; Treloar, Helen B; Miller, Alexandra et al. (2009) Onset of odorant receptors. Ann N Y Acad Sci 1170:18-20
Treloar, Helen B; Ray, Arundhati; Dinglasan, Lu Anne et al. (2009) Tenascin-C is an inhibitory boundary molecule in the developing olfactory bulb. J Neurosci 29:9405-16
Shay, Elaine L; Greer, Charles A; Treloar, Helen B (2008) Dynamic expression patterns of ECM molecules in the developing mouse olfactory pathway. Dev Dyn 237:1837-50