research / Motor Neuron pool specification / Patterning Motor neuron pools


Propagation of a neuronal cell fate in the developing spinal cord


We are interested in the stepwise acquisition of neuronal identity that distinguishes motor neuron subtypes from each other. These events include early patterning of the spinal cord, where environmental signals instruct neural precursors and influence the type of progeny they can give rise to. These early signals are involved in the hierarchic definition of all MN subclasses, defining columns, subtypes and pools. Additional signals from target muscles also act on motor neurons themselves and refine late aspects of the definition of cell identities.


One such late event is illustrated by the events governing the specification of one group of motor neurons, defined by expression of the fate-determining the transcription factor PEA3. This population is located at brachial levels of the spinal cord. We have shown that establishment of PEA3 expression domain involves the sequential action of two peripheral factors (GDNF and HGF) and the long range action of a presently unknown central factor. This long-range patterning mechanism leads to the propagation in the spinal cord of a neuronal identity.





Establishment of Pea3 expression domain in the spinal cord:

Two peripheral factors, HGF and GDNF, act on the same «pioneer »neurons, to induce pea3 expression, and to trigger a long-range signalingmechanism involved in the propagation of PEA3 expression. While Pea3 is induced by GDNF in a group of pioneer neurons, HGF acts on the same neurons, once they express its receptor Met, to trigger a long-range signalingmechanism leading to the recruitment of additional neurons from more anterior segments, and thereby, to the rostralpropagation of PEA3 expression.


Publications:


Caruso N., Herberth B., Lamballe F., Arce-Gorvel V., Maina F., and Helmbacher F. Plasticity versus specificity in RTK signalling modalities for distinct biological outcomes in motor neurons. BMC Biology, in press (2014)

Caruso BMC Biol 2014 (pdf 3.1Mb)

Helmbacher, F., Dessaud, E., Arber, S., deLapeyriere, O., Henderson, C. E., Klein, R. and Maina, F. (2003). Met Signaling Is Required for Recruitment of Motor Neurons to PEA3-Positive Motor Pools. Neuron 39, 767-77.

Helmbacher 2003 (pdf, 601 Ko)


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last updated 28.06.2015