During formation of the brain in mammals, neural stem cells (NSCs) transit through sequential periods of expansion, neurogenesis and gliogenesis. Notch signaling maintains NSCs and blocks transcription of pro-neurogenic factors. Notch ligands are expressed by differentiating progenitors and activate lateral inhibition signals through Notch. It has long been proposed that Notch signaling occurs bi-directionally through ligands such as Jagged1 (Jag1), which are also type I membrane proteins. However, the molecular mechanisms controlling the transition from stem cell division, where Notch plays a maintenance role, to daughter cell differentiation are poorly understood. To study the role of Jag1, in niche maintenance I began by transducing NSCs lining the subventricular zone (SVZ) with full length Jag1 (Jag1FL). Surprisingly, Jag1 induced a fate switch to Sox10+ oligodendrocyte precursors. NSCs grown under differentiating conditions in vitro recapitulated this phenotype to some degree. RNA-Sequencing analysis was performed to study the transcriptome changes of Jag1FL-IRES-GFP transduced NSCs. This screen revealed an upregulation (induction) of key genes involved in oligodendroctye maturation and myelination, which were further confirmed by qRT-PCR. Ongoing NSC grafting experiments are being performed to analyze the effects of Jag1FL-IRES-GFP+ NSCs on mice exhibiting focal myelin lesions. These proof of concept experiments hold promise for elucidating an, as of yet unknown role of Jag1 in remyelination. Through biochemical analyses, we have demonstrated that the Jag1 intracellular domain (JICD) can act as a transcription factor signaling in a cell autonomous fashion upon activation. Through chromatin immunoprecipitation, I have identified potential genomic regions and Wnt signaling target genes, directly bound by nuclear JICD. Taken together with the in vivo data, this proposes a new role for Jag1 in NSCs maintenance, and displays its potential for regulating fate switch to an oligodendrocytic lineage.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:631432 |
| Date | January 2014 |
| Creators | Beattie, Robert |
| Contributors | Verdon, Taylor |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/7326/ |
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