title: An investigation of gene expression in single cells derived from Nestin-expressing cells in the adult mouse midbrain in vivo.
abstract: Generation of new dopamine (DA) neurons in the adult midbrain is a controversial issue in development of better treatments for Parkinson's disease (PD). Previous research suggests Nestin-expressing neural precursor cells (NPCs) have a propensity to differentiate into neurons here, including DA neurons. In the present study we sought confirmation of this by studying gene expression in single Nestin-expressing cells and their progeny/ontogeny within the adult mouse midbrain. Cells were identified by administering a pulse of Tamoxifen to adult Nestin-CreERT2×R26eYFP transgenic mice. Samples of cytoplasm were harvested 4 days to 8 months later from individual eYFP+ cells in acutely prepared midbrain slices and analysed by RT-qPCR for gene expression. Remarkably, most eYFP+ cells co-expressed genes associated with mature (including DA) neurons (i.e. NeuN, Gad1, Gad2, vGlut2, TH and/or D2R) and neurogenesis (i.e. Ki67, Dcx, Ncam, Pax6, Ngn2 and/or Msx1), and this was true at all time-points following Tamoxifen. Indeed, cell proliferation genes (Nestin, Ki67) were exclusively expressed by eYFP+ cells with mature neuronal morphology and gene expression, and only at early time-points after Tamoxifen. Expression of proneuronal genes (Pax6, Msx1, Ngn2) was, however, higher in eYFP+ cells with immature morphology compared with mature morphology. Gene expression bore no relationship to cell location indicating that, in contrast to development, Nestin-expressing cells arise throughout the midbrain parenchyma and do not migrate long distances. On the other hand, gene expression did change with time after Tamoxifen, although not in a way consistent with neurogenesis. Overall, our results suggest that Nestin expression in the adult midbrain occurs in mature neurons, casting doubt on the premise of neurogenesis from Nestin+ NPCs here.
authors.affiliation: Florey Institute for Neuroscience & Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: parisa.farzanehfar@florey.edu.au.
authors.forename: Parisa
authors.initials: P
authors.lastname: Farzanehfar
authors.affiliation: Florey Institute for Neuroscience & Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Malcolm K
authors.initials: MK
authors.lastname: Horne
authors.affiliation: Florey Institute for Neuroscience & Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Tim D
authors.initials: TD
authors.lastname: Aumann
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism; D000089662:Doublecortin Protein; D015870:Gene Expression / Q000187:drug effects; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D064231:Nestin / Q000378:metabolism*; D055495:Neurogenesis; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D013629:Tamoxifen / Q000008:administration & dosage
chemical_list: C000714847:Dcx protein, mouse; D000089662:Doublecortin Protein; C577485:Nes protein, mouse; D064231:Nestin; D013629:Tamoxifen
keywords: Adult neurogenesis; Dopamine; Parkinson's disease; Substantia nigra