Journal of Neuroscience, Vol 15, 4827-4837, Copyright © 1995 by Society for Neuroscience
Olfactory marker protein mRNA is found in axons of olfactory receptor neurons
CH Wensley, DM Stone, H Baker, JS Kauer, FL Margolis and DM Chikaraishi
Molecular Biology and Microbiology Department, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
The separation between the cell bodies of olfactory receptor neurons in the
nasal cavity and their axon terminals in the olfactory bulb make them
attractive for studying axonal transport. Although high molecular weight
RNAs are generally believed to be excluded from axons of mature neurons, we
demonstrate here that mRNA for olfactory marker protein (OMP), an abundant
cytoplasmic protein selectively expressed in mature receptor cells, is
present in rodent olfactory receptor axons. OMP RNA was detected by in situ
hybridization at the light microscope level in axons and in terminals. By
nuclease protection, the level of OMP RNA in the olfactory bulb was 5-10%
of that in the olfactory epithelium where the cell bodies reside. In
contrast to axonally transported vasopressin and oxytocin mRNAs, which are
deficient in their 3' polyA tails, axonal OMP RNA fractionated as polyA+.
OMP RNA was lost from axons and terminals after deafferentation, suggesting
that OMP RNA was synthesized in receptor cell bodies in the epithelium and
was transported into axons and terminals in the olfactory bulb. RNA for
G(olf), a G-protein highly expressed in dendrites of mature olfactory
receptor neurons, was not detected in the olfactory bulb. We hypothesize
that the immature nature of the cytoskeleton and, specifically, the lack of
tightly bundled microtubules allows transport of particular mRNAs in
olfactory receptor axons.
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