Neurite outgrowth is a complex mechanism that is still the subject of intense investigation. Current given helped to highlight the involvement of three main mechanisms in neurite growth : i) the dynamics of the cytoskeleton, ii) the intracellular membrane trafficking and membrane supply at the growth cone and iii) cell signaling , mainly via the MAPK-ERK1 / 2, which resulted in the regulation of transcription. The PLD1 and its product the phosphatidic acid (PA) appear to be at the center of the major pathways involved in neuronal development. My work has deepened our understanding of the cellular role of PLD1 during neurite outgrowth. I showed that PLD1 together with the protein kinase RSK2 regulates the fusion of vesicles positive for Ti-VAMP/VAMP7 during neurite outgrowth. On the other hand, I have determined that PLD1 plays an important role in maintaining the endosomal signaling pathwayMAPK-ERK1/2-RSK2-CREB induced by neurotrophin. I also showed that PLD1 regulates the activation of mTOR/p70S6K in response to BDNF. Deregulation of MAP -ERK1 / 2 and mTOR/p70-S6K pathways could be the basis for the reduction of dendritic arborization and maturation of dendritic spines observed in cortical neurons Pld1-/- culture. In addition to the involvement of RSK2 in the regulation of PLD1, I also showed that PLD1 regulates RSK2 activation in response to neurotrophin, possibly via a feedback loop. Thus given obtained suggest a strong link between the two proteins during neuronal development. In the light of these data, alteration of this mechanism could explain the mental retardation observed in patients with Coffin -Lowry syndrome caused by loss of the kinase activity of RSK2. On the other hand, our results suggest a role for PLD1 in exocytosis of vesicles.
