Implication de tac1 dans les mécanismes de développement embryonnaire des populations neuronales ventrales de la moelle épinière

Details

Supervisors

Clotman, Frédéric

Faculty

Faculté de pharmacie et des sciences biomédicales

Degree label

Master [120] en sciences biomédicales, à finalité approfondie

Abstract

Some of the mechanisms active during embryonic development are reactivated after spinal cord injury in adults. Understanding these mechanisms could highlight some processes allowing spinal cord reparation. During embryonic spinal cord development, distinct neuronal populations are formed from progenitor domains under the control of domain specific combinations of transcription factors, including Onecut factors. Observations in mutant mice lacking Onecut factors in the spinal cord or in motor neurons have shown that those factors are controlling non-cell autonomous mechanisms regulating embryonic development of ventral neuronal populations. Several genes, the expression of which is altered when Onecut factors are missing in the motor neurons, have been revealed as potentially involved in these non-cell autonomous mechanisms. This work will focus on the involvement of one of those genes, tac1, in the non-cell autonomous mechanisms that governs ventral neurons development in the spinal cord and controlled by Onecut factors. Expression of tac1 in mutant and in control mouse embryos and chicken embryos, as well as the expression of tacr1 receptor in chicken embryos, have been assessed by in situ hybridization. A vector increasing the expression of tac1 in the motor neurons, pHb9-Tac1-IRES-GFP, has been elaborated and electroporated in the spinal cord of chicken embryos. Overexpression of tac1 in the motor neurons did not alter the development of ventral neuronal populations in term of number of cells. Vectors inducing partial inhibition of the expression of tac1 have been elaborated and electroporated in the spinal cord of chicken embryos as well. Interestingly, the inhibition of the expression of tac1 induced a decrease of the number of motor neurons, suggesting that tac1 might be involved in mechanisms controlling motor neurons embryonic development. As a conclusion, results obtained in chicken embryos during this work does not suggest any involvement of tac1 in non-cell autonomous mechanisms of development of ventral interneurons coming from motor neurons and regulated by Onecut factors. However, results suggest that tac1 might be involved in mechanisms regulating motor neurons embryonic development.