Olfactory perception of intraspecific chemosignals provides sensory information about social and sexual status, genetic makeup, and species identity. In this proposal we describe experiments to investigate activities induced by these chemosignals and their underlying transduction mechanisms. Previously we have shown that the main olfactory system employs both cAMP- and phospholipase C- mediated pathways in pheromone signaling. Genetic knockout of the cyclic nucleotide-gated channel subunit 2 (CNGA2), which eliminates the cAMP signaling, does not eliminate pheromone-induced activation. In our preliminary study, we find that a novel signaling component, Transient Receptor Potential channel M5 (TRPM5), is present in a subset of mouse mature OSNs involved in olfactory signaling of pheromones and urinary components. Knockout of both CNGA2 and TRPM5 results in profound aberration in the main olfactory epithelium and bulbs, indicating the functional importance of TRPM5 in olfactory signaling. We hypothesize that TRPM5 is involved in signaling of intraspecific chemical cues in the main olfactory system. The proposed experiments fall into 3 aims. 1) We will test whether functional TRPM5 is crucial for intraspecific signal-evoked glomerular activation patterns. We will examine intraspecific chemosignals-induced activation in olfactory bulbs use immunolabeling of Fos protein as a neuronal activation marker and construct glomerular activation maps using a glomerular mapping program. We will then determine whether activated glomeruli receive input from the TRPM5-expressing OSNs, and whether knockout of TRPM5 alters the activation patterns. 2) We will test whether TRPM5-expressing OSNs provide sensory input to sustain tyrosine hydroxylase activity found in single CNGA2 knockout mice and whether double- knockouts of both CNGA2 and TRPM5 result in abnormality and neuronal death in the main olfactory system using anatomical and immunocytochemical approaches. 3) We will test whether TRPM5 is involved in signal transduction of intraspecific chemosignals in OSNs. We will characterize electrical and Ca2+ responses to pheromones and urine components in OSNs from TRPM5-GFP, TRPM5 knockout-GFP, CNGA2 knockout-TRPM5GFP mice and determine the functions of TRPM5 and associated pathways using Ca2+ imaging and electrophysiological recording methods. Taken together, the proposed studies will provide fundamental knowledge on signaling processing of intraspecific chemical cues and functional roles of TRPM5 in the main olfactory system.

Public Health Relevance

In this application, we propose to investigate olfactory signaling mechanisms and the abnormality resulted from dysfunction of ion channels in the olfactory epithelium. Olfactory deficits are known to associate with aging and diseases. Our studies will provide knowledge ultimately useful for clinical treatment of olfactory dysfunctions.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC009269-05
Application #
8246439
Study Section
Somatosensory and Chemosensory Systems Study Section (SCS)
Program Officer
Sullivan, Susan L
Project Start
2008-04-01
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2014-03-31
Support Year
5
Fiscal Year
2012
Total Cost
$350,067
Indirect Cost
$110,487
Name
University of Maryland Balt CO Campus
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
061364808
City
Baltimore
State
MD
Country
United States
Zip Code
21250
Yamaguchi, Tatsuya; Yamashita, Junpei; Ohmoto, Makoto et al. (2014) Skn-1a/Pou2f3 is required for the generation of Trpm5-expressing microvillous cells in the mouse main olfactory epithelium. BMC Neurosci 15:13
Krosnowski, K; Ashby, S; Sathyanesan, A et al. (2012) Diverse populations of intrinsic cholinergic interneurons in the mouse olfactory bulb. Neuroscience 213:161-78
Slotnick, Burton; Restrepo, Diego; Schellinck, Heather et al. (2010) Accessory olfactory bulb function is modulated by input from the main olfactory epithelium. Eur J Neurosci 31:1108-16
Ogura, Tatsuya; Krosnowski, Kurt; Zhang, Lana et al. (2010) Chemoreception regulates chemical access to mouse vomeronasal organ: role of solitary chemosensory cells. PLoS One 5:e11924