Download Ciliated dendrite mRNA may control olfactory sensory neuron

Ciliated dendrite mRNA may control olfactory sensory neuron survival and death
Marie-Annick Persuy (INRA NOPA), Monique Caillol (INRA NOPA), P Benesh (Genenoscience), Christine
Formisano-Tréziny (UII. ERT MEIDIA), Jean Gabert (UMAGT), Jean-Jacques Remy (USC INRA-Phase NICN CNRS
UMR 6184)
Important to both developmental and neurobiological function, localized translation of specific sets of mRNA allows
for asymetric distribution of gene products. Local translation in neuron dendritic or axonal endings, is though to control
neurite growth, formation of synapses and rapid responses to external stimuli.
Olfactory sensory neurons (OSN) are the only neurons exposed to the external environment via their ciliated dendrites
that express the odor receptors. Since there is no blood-brain barrier in the olfactory region, OSN participate to the brain
protection against airborne toxic chemicals, infectious agents and parasitic genetic elements.
OSN are short living cells constantly renewed from progenitors. The life-long regeneration of OSN represents one of
the only few instances of adult neurogenesis in the central nervous system. It has raised high interest in dissecting the
pathways for neural development, differentiation and survival.
Odorant stimulation protects OSN from dying. OSN survival thus depends on an efficient defense against external
aggressions but also on odor-induced activation of “survival” genes.
A cDNA library, named ONCL for Olfactory Neuron Ciliae Library, was generated from purified rat OSN ciliated
dendrites. Sequencing of the library led to the identification of more than 300 genes that might be locally translated
within OSN ciliae.
We then purified OSN ciliae RNA from seven different animals and analysed expression levels of several ONCL genes
in each individual.
Using quantitative PCR, we evaluated OSN cilia expression of the five following ONCL genes : PP1 (Phosphatase 1),
CIRBP (Cold-Inducible RNA Binding Protein), APP (Amyloid Precursor Protein), Tsn (Translin) and Ssr3 (member of
the translocon complex). We found that the five genes expressed at the same levels in OSN cilia from seven different
animals.
Consistent with the unique features of OSN, i.e. brain-environment interface and activity-dependent survival, functional
analysis of all ONCL genes revealed that more than half of them encode “survival” proteins.
Interestingly, a large set of ONCL genes belong to the odor-evoked p38/MAPK pathway, which is also a conserved
innate immunity pathway. Besides a number of expected immune and defense genes, we identified a number of tumor
promoter and cell cycle control genes, suggesting the existence of new links between activity and survival via
oncogenic and antiapoptotic mechanisms.