Abstracts - Association for Chemoreception Sciences

odor responses. Recently, transient receptor potential channel M5
(trpM5) has been shown to express in a population of mature
OSNs in mice (Lin et al 2007). trpM5 is an essential downstream
effector of the PLC pathway for taste transduction. Here we
investigate PLC, trpM5 and internal Ca 2+ stores in freshly
isolated mouse OSNs using single cell Ca 2+ imaging.
We found that OSNs responded to a PLC activator m-3M3FBS
in a concentration dependent manner with a higher percentage
of responding cells and greater amplitudes after an increase in
concentration (78%, n=23 at 15µM, 90.3%, n=52 at 25µM).
In contrast, only one out of 9 OSNs responded to the inactive
analog o-3M3FBS (25µM). Eliminating extracellular Ca 2+ did
not reduce the percent of responding OSNs to m-3M3FBS and
only the response amplitudes were moderately reduced (n=7).
In addition, The PLC inhibitor U73122 (5-10µM) greatly reduced
the percent of OSNs responding to m-3M3FBS (37.5%, n=8)
and the response amplitudes. Further, using OSNs isolated
from trpM5-GFP and trpM5 knockout-GFP mice, we found
that trpM5-expressing OSNs responded to m-3M3FBS with a
significantly larger amplitude and calcium load than the trpM5-
null OSNs (n= 6 to 9 for each group). Our data suggest that
most OSNs are capable of utilizing the PLC pathway to release
Ca 2+ from internal Ca 2+ stores and that subsequent activation of
trpM5 in trpM5-expressing OSNs leads to additional increases
in intracellular Ca 2+ loads. Acknowledgements: Supported by
research grants NIH/NIDCD 009269, 012831 and ARRA
administrative supplement to WL
#P51 POSTER SESSION I:
MULTIMODAL RECEPTION; CHEMOSENSATION
AND DISEASE; OLFACTION PERIPHERY
mouse model to understand the functional role of Q8BH53 in
the olfactory system. In addition, we are taking a biochemical
approach to identify binding partners of Q8BH53 in OSN cilia.
Acknowledgements: NIH DC007395
#P52 POSTER SESSION I:
MULTIMODAL RECEPTION; CHEMOSENSATION
AND DISEASE; OLFACTION PERIPHERY
Expression of Several Odorant Receptors Outside the
Olfactory System
Crystal M. Wall, Marsalis Brown, Haiqing Zhao
Johns Hopkins University/Biology Baltimore, MD, USA
Over one thousand G-protein coupled receptors have been
classified as odorant receptors in the mouse genome based
on sequence similarities with receptors found in the olfactory
system. Recent studies have identified odorant receptors
expressed outside of the olfactory system, and growing evidence
supports a role for these receptors in extra-olfactory functions.
We have examined expression of the odorant receptors M71,
M72, I7, P2, MOR28, whose expression patterns have been
well characterized in the olfactory system. We screened for
expression of these receptors in extra-olfactory tissues by
RT-PCR and then tested positive results by in situ hybridization,
immunohistochemistry, or through the use of established
reporter mouse lines. Identification of novel expression outside
the olfactory system suggests a function for odorant receptors in
these tissues. Future research will be aimed toward uncovering
functions and identifying putative endogenous ligands.
Acknowledgements: NIH DC007395
Analysis of the novel protein Q8BH53 in olfactory
sensory neuron cilia
Anna K Talaga 1 , Aaron B Stephan 2 , Varun Chokshi 1 , Haiqing Zhao 1
1
Johns Hopkins University/Biology Baltimore, MD, USA,
2
UCSD/Division of Biological Sciences La Jolla, CA, USA
The cilia of olfactory sensory neurons (OSNs) are specialized
for encoding and transducing odor information. Among the
proteins found in the cilia, many are critical for mediating
and/or modulating olfactory signal transduction. We detected
a novel protein, Q8BH53, from a proteomic screen of OSN
cilial membrane preparations. Q8BH53 is conserved among
eukaryotes and is a unique protein, as no other paralogs exist
in the mouse genome. Bioinformatic analysis suggested that
the majority of the Q8BH53 sequence is composed of ARMdomains.
Although the function of Q8BH53 is unknown, the
presence of these ARM-repeat domains signifies that it may
be important for establishing protein-protein interactions.
q8bh53 transcripts are abundant in the mouse olfactory
epithelium and are also found in several other tissues. Using
immunohistochemistry, we found that Q8BH53 localizes
specifically to OSN cilia but is largely excluded from the
respiratory epithelium cilia in adult mice. Furthermore, we found
that Q8BH53 expression begins around embryonic day E13.5
in the olfactory epithelium. We are currently using a knock-out
#P53 POSTER SESSION I:
MULTIMODAL RECEPTION; CHEMOSENSATION
AND DISEASE; OLFACTION PERIPHERY
M3-R inhibits b-arrestin2 recruitment and desensitization of
mammalian odorant receptors to potentiate their activation
Yue Jiang 1 , Yun R. Li 2 , Hiroaki Matsunami 1,3
1
Duke University Durham, NC, USA, 2 University of Pennsylvania,
Perelman School of Medicine Philadelphia, PA, USA, 3 Duke University
Medical Center Durham, NC, USA
Adjusting sensitivity of sensory stimuli needed by an animal at
any given time is crucial for animals’ survival. In mammals, the
activation of odorant receptors (ORs), which are expressed in the
olfactory sensory neurons (OSNs) in the olfactory epithelium,
mediates the perception of smell. These ORs belong to the
large family of G protein-coupled receptors (GPCRs), which
also include the muscarinic acetylcholine receptors that are
key mediators of the parasympathetic nervous system output.
Previously, we showed that activation of the muscarinic receptor
M3-R has been shown to potentiate OR-mediated cAMP
response, and the functional interaction between the M3-R
and ORs suggests that odorant detection may be modulated
by the neurotransmitter at the peripheral level. However, the
mechanisms underlying this modulation were not understood.
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
48