The Role of Notch Signalling Pathway in Demyelination-Remyelination Process

M. FLORENCIA ALMEIRA GUBIANI; MILAGROS PEREIRA LUPPI; PATRICIA MATHIEU ; ANA ADAMO

Congreso; 44th Annual Meeting of the Society for Neuroscience; 2014

In the CNS the oligodendroglial cell (OL) is responsible for normal myelination. Demyelination is a pathological process characterized by myelin loss around axons. Demyelination is followed by remyelination, the process by which myelin sheets are restored around demyelinated axons resolving the functional deficit. In this work we examined the Notch signaling pathway involvement in the demyelination-remyelination process in a toxic model of demyelination induced by cuprizone (CPZ) ingestion. Twenty-one-day-old Wistar rats were fed with a diet containing 0.6% (w/w) CPZ during 2 weeks. Demyelinated animals were sacrificed 7d before CPZ withdrawal (-7d), the day of CPZ withdrawal (0d), and 7, 14 and 21d after (+7d, +14d and +21d). Control animals were sacrificed at the same time. We characterized Notch signaling in the SVZ and CC throughout Notch intracellular domain (NICD) level and the non canonical Notch ligand F3/Contactin (F3) by WB and by IHC concomitantly with oligodendroglial progenitor cell (OPC) marker NG2 and OL marker Olig2. We also evaluated the expression of Notch downstream genes Hes1, Hes5 and MAG in SVZ and CC of control and demyelinated animals by Real Time-PCR. On the other hand we characterized cell population in primary cell culture of the SVZ from CPZ and control animals at the time points described above. Results showed that Notch signaling pathway is activated in NG2+ OPCs in the CC and SVZ as a consequence of demyelination induced by CPZ. The level of F3 increased significantly in the SVZ of CPZ treated animals at -7d, +7 and +21d while this increase was observed at -7d, 0d and +7d in the CC of demyelinated rats. The number of Olig2+ cells expressing F3 is larger than that of NG2+ cells expressing F3 indicating that non-OPC, further differentiated OLs express Notch?s non-canonical ligand. There is a concomitant increase in the expression of Hes1 in the SVZ in CPZ demyelinated rats at 0d. This result suggests that Notch signaling activation through the non canonical ligand F3 may be involved in OL maturation and, therefore, in remyelination.