Alvarez Buylla, A.

Obernier, K.

Ponti, Giovanna

English

PubMed

Institutional Research Information System University of Turin

This article was downloaded by: [Universita degli Studi di Torino]On: 27 November 2014, At: 02:45Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UKCell CyclePublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/kccy20Lineage progression from stem cells to new neurons inthe adult brain ventricular-subventricular zoneGiovanna Pontia, Kirsten Obernierb & Arturo Alvarez-Buyllaba Department of Neuroscience “Rita Levi-Montalcini” and Neuroscience Institute CavalieriOttolenghi (NICO); University of Turin; Turin, Italyb Department of Neurosurgery and The Eli and Edythe Broad Center of RegenerationMedicine and Stem Cell Research; University of California, San Francisco; San Francisco, CAUSAPublished online: 10 May 2013.To cite this article: Giovanna Ponti, Kirsten Obernier & Arturo Alvarez-Buylla (2013) Lineage progression from stem cells tonew neurons in the adult brain ventricular-subventricular zone, Cell Cycle, 12:11, 1649-1650, DOI: 10.4161/cc.24984To link to this article:  http://dx.doi.org/10.4161/cc.24984PLEASE SCROLL DOWN FOR ARTICLETaylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained inthe publications on our platform. Taylor & Francis, our agents, and our licensors make no representations orwarranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Versionsof published Taylor & Francis and Routledge Open articles and Taylor & Francis and Routledge Open Selectarticles posted to institutional or subject repositories or any other third-party website are without warrantyfrom Taylor & Francis of any kind, either expressed or implied, including, but not limited to, warranties ofmerchantability, fitness for a particular purpose, or non-infringement. Any opinions and views expressed in thisarticle are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. Theaccuracy of the Content should not be relied upon and should be independently verified with primary sourcesof information. Taylor & Francis shall not be liable for any losses, actions, claims, proceedings, demands,costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly inconnection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Terms & Conditions of access anduse can be found at http://www.tandfonline.com/page/terms-and-conditions It is essential that you check the license status of any given Open and Open Select article to confirmconditions of access and use.www.landesbioscience.com Cell Cycle 1649Cell Cycle 12:11, 1649–1650; June 1, 2013; © 2013 Landes Bioscience EditoriaLs: CELL CyCLE FEaturEs EditoriaLs: CELL CyCLE FEaturEsIt has been estimated that ~10,000 new neurons are generated daily in the mouse ventricular-subventricular zone (V-SVZ),1 an extensive germinal niche present in the walls of the lateral brain ventricles in many adult mammals. Neural stem cells, a subpopulation of GFAP-expressing astrocytes (B1 cells),2 contact the ventricle with a small apical process surrounded by ependymal cells forming pinwheel-like structures.1 B1 cells generate intermedi-ate progenitors (C cells), which differen-tiate into neuroblasts (A cells).2 A cells also divide and migrate out of the V-SVZ along the rostral migratory stream into the olfactory bulb, where they differenti-ate into local interneurons.3,4 A full under-standing of this process requires precise information of the dynamics of prolif-eration of V-SVZ progenitor populations and how many times each divides. This information is now available for the adult mouse brain.5The reporter protein in hGFAP::GFP mice was used to identify B1 cells and immunolabeling for Ascll, and DCX was used to identify C and A cells, respectively. Of the Ascll + cells, only 3.1+/−0.6% were also GFP+, while 15.9+/−1.6% were DCX+, indicating a small overlap between populations, pos-sibly associated to transitional stages between cell types. We used whole-mount preparations, which provide an en face view of the lateral ventricular surface, to analyze the entire neurogenic niche, minimizing the effect of rostral migra-tion of proliferating progenitors on our quantifications. Using a combination of thymidine analogs (CldU and EdU) and Lineage progression from stem cells  to new neurons in the adult brain  ventricular-subventricular zoneGiovanna Ponti,1 Kirsten obernier2 and arturo alvarez-Buylla2,*1department of Neuroscience “rita Levi-Montalcini” and Neuroscience institute Cavalieri ottolenghi (NiCo); university of turin; turin, italy; 2department of Neurosurgery and the Eli and Edythe Broad Center of regeneration Medicine and stem Cell research; university of California, san Francisco; san Francisco, Ca usa*Correspondence to: Arturo Alvarez-Buylla; Email: abuylla@stemcell.ucsf.eduSubmitted: 04/08/13; Accepted: 04/13/13http://dx.doi.org/10.4161/cc.24984Comment on: Ponti G, et al. Proc Natl Acad Sci USA 2013; 110:E1045-54; PMID:23431204; http://dx.doi.org/10.1073/pnas.1219563110three protocols (CL, cumulative labeling; DA, double analogs and PLM, percentage of labeled mitosis methods), we calculated the growth fraction (GF) and the short-est and longest cell cycle (TC) for each cell population. We also estimated the length of the different phase of the cell cycle: S (TS), mitosis (TM), G2 (TG2), and G1 (TG1) for B1, C and A cells. These three meth-ods were used to minimize effects of cave-ats associated to each one; e.g., CL and PLM estimates may be influenced by cell migration and differentiation.PLM relies on mitotic cells which are a small subset of the proliferating popu-lation and may be too small for reliable quantifications of populations with a low GF such as B1 cells. Importantly, we also found that EdU was toxic as labeled cells attempted a second division. EdU was therefore only used for experiments shorter than TC.Interestingly, we found that as many as 8.6% of B1 cells proliferate with a relatively short TC (<< 17 h) and a short TS (<< 4.5 h) compared to intermediate progenitors (see below). Given the aver-age number of B1 cells in one mouse (6,200+/−200), we can extrapolate that = 700 B1 cells proliferate daily. This sug-gests that a sizable fraction of the primary progenitors or stem cells are dividing at any one time, and they do so quite rapidly.We observed that the majority of the intermediate precursors or transit-ampli-fying C cells are actively cycling (87%). They have a TC that varies between 18 and 25 h with a surprisingly long TS of 12–17 h and a short TG1 (2 h). From the quantification of Ascl1+ CldU+ cells at different survival times and their ratio of mitotic cells, we estimated that C cells divide on average three times before dif-ferentiating. The population of Ascl1+ cells that we observed (~8,000 cells) is composed of C cells generated by the divi-sion of a B1 cell and the ones generated by the three subsequent divisions of these intermediate progenitors.Neuroblasts account for almost half of all actively dividing cells in the V-SVZ. About 55% of A cells divide at least once in the V-SVZ (TC = 18 h, TS = 9 h, TG1 = 4 h) resulting in the << 10,000 new neuro-blasts generated daily.It took 3–4 d for the generation of A cells from B1 cells. Interestingly, B1 cells had a relatively short S phase and long G1 phase, similar to the cell cycle dynamics of radial glial during embryonic develop-ment.7 Another important finding is the observation of heterogeneity in cell cycle dynamics of C cells. This heterogeneity was not related to changes with the circa-dian rhythm or the localization of C cells within different subregions of the V-SVZ. It may be due to differences in cell cycle dynamics depending on whether they are generated from a B1 cell or from other C cells. Consistently, an elongation of the cell cycle as intermediate progenitors progress through the lineage in vitro has been reported.8Our study provides the first overall estimation of cell cycle times of different neural progenitors and the dynamics of progression from stem cells to neuroblasts. This is fundamental new information to understand the mechanisms by which the Downloaded by [Universita degli Studi di Torino] at 02:45 27 November 2014 1650 Cell Cycle Volume 12 issue 11V-SVZ continues to supply the olfactory bulb with thousands of new neurons every day. This knowledge, in turn, would be important to the overall understanding of how new neurons are produced in an adult brain.References1. Alvarez-Buylla A, et al. J Neurosci 2002; 22:629-34; PMID:118260912. Doetsch F, et al. Cell 1999; 97:703-16; PMID:10380923; http://dx.doi.org/10.1016/S0092-8674(00)80783-73. Luskin MB. Neuron 1993; 11:173-89; PMID:8338665; http://dx.doi.org/10.1016/0896-6273(93)90281-U4. Lois C, et al. Science 1996; 271:978-81; PMID:8584933; http://dx.doi.org/10.1126/sci-ence.271.5251.9785. Ponti G, et al. Proc Natl Acad Sci USA 2013; 110:E1045-54; PMID:23431204; http://dx.doi.org/10.1073/pnas.12195631106. Cai L, et al. J Neurosci 1997; 17:2079-87; PMID:90457357. Takahashi T, et al. J Neurosci 1995; 15:6046-57; PMID:76661888. Costa MR, et al. Development 2011; 138:1057-68; PMID:21343361; http://dx.doi.org/10.1242/dev.061663Downloaded by [Universita degli Studi di Torino] at 02:45 27 November 2014 

Lineage progression from stem cells to new neurons in the adult brain ventricular-subventricular zone

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