Visit our Expo - Redox and Inflammation signaling 2012

Session II : Receptor signaling and G proteins Poster II, 46
5-HT2B and alpha1D receptors control redox equilibrium and TNF-alpha shedding in
bioaminergic neuronal cells.
Benoit Schneider1, Mathéa Pietri1, Sophie Mouillet-Richard1, Myriam Ermonval1,
Vincent Mutel2, Jean-Marie Launay3 and Odile Kellermann1
1Institut André Lwoff-Institut Pasteur, CNRS UPR 1983, Laboratoire Différenciation
Cellulaire et Prions, Villejuif Cedex, France. 2Pharma Research Department, F.
Hoffman-La-Roche Ltd., Base, Switzerland. 3Service de Biochimie, EA3621 Hôpital
Lariboisière, Faculté de Pharmacie, Université apris V, Paris, France. E-mail:
bschneid@vjf.cnrs.fr.
Loss of neuronal homeostasis in neurodegenerative disorders, such as Alzheimer’s,
Parkinson or Prion diseases, may arise from dysregulations of physiological signaling
pathways due to the accumulation of aggregation-prone proteins. For instance, alterations
with serotonin (5-hydroxytryptamine, 5-HT)- or norepinephrine (NE)- dependent signaling
pathways have been reported in these pathologies. In addition, oxidative stress is also widely
suspected to be a major cause of neuronal cell dysfunction or death, since post-mortem brain
studies from affected patients exhibit enhanced indices of reactive oxygen species (ROS). A
possible origin of oxidative stress could hence relate to deviation of ROS-coupled signaling
pathways that normally take part in the control of neuronal functions.
We took advantage of a neuroectodermal progenitor, 1C11, endowed with the capacity
to differentiate into serotonergic or noradrenergic neuronal cells to probe the possible
involvement of 5-HT or NE in regulating the cellular redox state in neurons. Upon induction
by Bt2cAMP, almost 100% of 1C11 cells acquire, within 4 days, a complete serotonergic
phenotype (1C115-HT) including 5-HT synthesis, storage and uptake as well as three Gprotein
coupled receptors of the 5-HT1B/1D, 5-HT2B and 5-HT2A subtypes. Under
combined addition of Bt2cAMP and DMSO, 100% of 1C11 cells convert within 12 days into
fully functional noradrenergic neurons (1C11NE) able to synthesize, store and take up NE.
1C11NE cells transduce NE signals through a single alphalpha1D adrenoceptor. Along either
differentiation program, the bioaminergic receptors act as autoreceptors and mediate the effect
of 5-HT or NE in the coordination and/or onset of all neurotransmitter-associated functions.
By using a panel of specific agonists towards each receptor subclass, we establish that
5-HT2B receptors and alphalpha1D adrenoceptors are functionally coupled to ROS synthesis
through NADPH oxidase activation in 1C115-HT and 1C11NE cells. The ROS response
imparted by each receptor is restricted to 1C11-derived progenies that have implemented a
complete serotonergic or noradrenergic phenotype. These observations indicate that 5-HT2B
and alphalpha1D autoreceptors take part in the control of the cellular redox equilibrium in
neuronal cells. In addition, our data identify TACE (TNF-alphalpha Converting Enzyme), a
member of a disintegrin and metalloproteinase (ADAM) family, as a downstream target of the
5-HT2B and alphalpha1D receptor-NADPH oxidase signaling pathway. Upon 5-HT2B or
alphalpha1D receptor stimulation, ROS act as second message signals that fully govern TNFalphalpha
shedding in the surrounding milieu of 1C115-HT and 1C11NE cells. TNFalphalpha
may in turn contribute to neuronal homeostasis. Eventually, our study may have
implications regarding the origin of oxidative stress as well as up-regulated expression of
proinflammatory cytokines in neurodegenerative disorders, which may relate to the deviation
of normal signaling pathways coupled to neurotransmitters.
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