Calmodulin (CaM) is an intracellular calcium sensor that is a critical participant in many signaling pathways including almost every aspect of olfactory signal transduction. However, CaM is too important to be allowed to function by itself. Mechanisms exist to regulate the accessibility of CaM and Ca/CaM at each step in intracellular signaling cascades. We propose that the olfactory marker protein (OMP) is a key member of such a CaM regulatory process in olfactory transduction. We hypothesize that OMP is a pivotal participant in a novel mechanism that, in concert with the Bex proteins, regulates the participation and targeting of Ca/CaM to multiple effectors in the olfactory sensory neuron (OSN) signal transduction cascade. This novel OMP/Bex/CaM hypothesis linking the function of OMP to CaM provides a testable framework to explain all the behavioral and electrophysiological phenotypes of the OMP-KO mouse. Furthermore, this proposal positions OMP as a key, integral component at multiple steps throughout the entire olfactory transduction cascade from Ca2+ entry to elimination. This novel OMP/Bex/Ca/CaM hypothesis is supported by several empirical observations from my lab: 1-Ca2+ efflux from OSNs via Na+/Ca2+ exchanger (NCX) activity is compromised in the OMP-KO mouse;2-OMP forms a short lived dimer that binds to Bex1 and 2;3-Bex1 and 2, the intracellular protein partners of OMP, interact with Ca/CaM;4-the intracellular loops of Na+/Ca2+ exchangers NCX1, 2 and 3 each have a Ca/CaM binding site;5-the Bex1-KO mouse has EOG and behavioral deficits similar to those of the OMP-KO mouse;6-NCX1 binds to CaM-agarose;7-NCX1 activity is inhibited by pharmacological CaM antagonists. We now propose to apply a coordinated, multidisciplinary approach to characterize this OMP/Bex/CaM hypothesis at the molecular, cellular and whole animal levels to increase our understanding of the basic mechanisms regulating the olfactory transduction cascade. To achieve this we will address the following hypotheses:1-The Na+/Ca2+ exchanger (NCX) activity that returns elevated intracellular Ca2+ to prestimulus levels in OSNs is modulated by its intracellular interactions with Ca/CaM, Bex1 and 2 and OMP;2-The efficacy of Ca/CaM on the Ca2+-activated chloride channel (Ca/ClC) in olfactory transduction is modulated by the interactions among CaM, OMP and Bex1 and 2;3-The interactions among OMP and Bex1 and 2 proteins that modulate the efficacy of intracellular Ca/CaM and influence NCX activity cause in vivo alterations in behavior and electrophysiology of OSNs.These coordinated analyses will provide new insights to the molecular mechanisms by which the olfactory transduction cascade is regulated and will have broad impact on understanding CaM regulation of signal transduction mechanisms.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
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Somatosensory and Chemosensory Systems Study Section (SCS)
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Sullivan, Susan L
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University of Maryland Baltimore
Anatomy/Cell Biology
Schools of Medicine
United States
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Khazaei, Mohammad R; Halfter, Hartmut; Karimzadeh, Fereshteh et al. (2010) Bex1 is involved in the regeneration of axons after injury. J Neurochem 115:910-20
Bovolin, P; Bovetti, S; Fasolo, A et al. (2009) Developmental regulation of metabotropic glutamate receptor 1 splice variants in olfactory bulb mitral cells. J Neurosci Res 87:369-79
Senut, Marie-Claude; Azher, Seema; Margolis, Frank L et al. (2009) Distribution of carnosine-like peptides in the nervous system of developing and adult zebrafish (Danio rerio) and embryonic effects of chronic carnosine exposure. Cell Tissue Res 337:45-61
Cockerham, Renee E; Margolis, Frank L; Munger, Steven D (2009) Afferent activity to necklace glomeruli is dependent on external stimuli. BMC Res Notes 2:31
Kwon, Hyun J; Koo, Jae Hyung; Zufall, Frank et al. (2009) Ca extrusion by NCX is compromised in olfactory sensory neurons of OMP mice. PLoS One 4:e4260
Hamilton, Kathryn A; Parrish-Aungst, Stephanie; Margolis, Frank L et al. (2008) Sensory deafferentation transsynaptically alters neuronal GluR1 expression in the external plexiform layer of the adult mouse main olfactory bulb. Chem Senses 33:201-10
Reisert, Johannes; Yau, King-Wai; Margolis, Frank L (2007) Olfactory marker protein modulates the cAMP kinetics of the odour-induced response in cilia of mouse olfactory receptor neurons. J Physiol 585:731-40
Koo, Jae Hyung; Smiley, Mark A; Lovering, Richard M et al. (2007) Bex1 knock out mice show altered skeletal muscle regeneration. Biochem Biophys Res Commun 363:405-10
Bettini, Ezio; Margolis, Frank L (2007) Expression of an intron-containing beta-tubulin mRNA in catfish olfactory epithelium. J Mol Histol 38:571-9
Pyrski, Martina; Koo, Jae Hyung; Polumuri, Swamy K et al. (2007) Sodium/calcium exchanger expression in the mouse and rat olfactory systems. J Comp Neurol 501:944-58

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