Timing Neurogenesis and Differentiation: Insights from Quantitative Clonal Analyses of Cerebellar Granule Cells

Howard Hughes Medical Institute and Department of Biology, Neurosciences Program, Stanford University, Stanford, California 94305, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 04/2008; 28(10):2301-12. DOI: 10.1523/JNEUROSCI.5157-07.2008
Source: PubMed


The cerebellum is an excellent model system to study how developmental programs give rise to exquisite neuronal circuits in the adult brain. Here, we describe our findings regarding granule cell neurogenesis and differentiation using the MADM method (mosaic analysis with double markers) in mice. By following the development of individual granule cell clones, we show that (1) granule cell precursors (GCPs) undergo predominantly symmetric division during postnatal development; (2) clonally related granule cells (GCs) exit the cell cycle within a narrow time window and stack their axons in the molecular layer in chronological order from deep to superficial sublayers; and (3) whereas the average GCP proliferation in the external granular layer is progressively slower as development proceeds, there is a rapid expansion of GCPs shortly before clonally related GCs exit the cell cycle. These properties produce GC clones that are distinct, each having a restricted axonal projection, but that are on average similar in cell number. We discuss possible developmental mechanisms and functional implications of these findings.

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    • "In the rat most granule cells are formed during the second postnatal week, but due to the time required for their migration and the formation of dendrites , few glomerular synapses are formed with mossy fibers before the beginning of the third postnatal week (Altman, 1972). In the mouse, a similar pattern, but with somewhat faster dynamics is observed (Espinosa and Luo, 2008). Therefore, the developmental increase in total DNA recombination (Fig. 1 B) must be interpreted as recombination in GCs newly arriving in the IGL over a protracted period of time rather than as a delayed recombination of DNA in a constant number of GCs during the time of synapse formation. "
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    • "The factors governing how individual progenitors navigate this environment and terminate transit amplification are less clear and yet equally important in development and disease. The lack of an internal cell division clock (Espinosa and Luo, 2008) has focussed attention on cell non-autonomous factors such Wnt and bone morphogenetic protein (BMP) pathway signals in the EGL. For example, non-canonical Wnt signalling via Wnt3 has recently been shown to be capable of decreasing proliferation independently of BMP signalling (Anne et al., 2013). "
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    ABSTRACT: The cerebellum is a pre-eminent model for the study of neurogenesis and circuit assembly. Increasing interest in the cerebellum as a participant in higher cognitive processes and as a locus for a range of disorders and diseases make this simple yet elusive structure an important model in a number of fields. In recent years, our understanding of some of the more familiar aspects of cerebellar growth, such as its territorial allocation and the origin of its various cell types, has undergone major recalibration. Furthermore, owing to its stereotyped circuitry across a range of species, insights from a variety of species have contributed to an increasingly rich picture of how this system develops. Here, we review these recent advances and explore three distinct aspects of cerebellar development - allocation of the cerebellar anlage, the significance of transit amplification and the generation of neuronal diversity - each defined by distinct regulatory mechanisms and each with special significance for health and disease.
    Development 11/2014; 141(21):4031-4041. DOI:10.1242/dev.106559 · 6.46 Impact Factor
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    • "For example, MADM was first used to study normal cerebellar development, in particular to examine the relationship between lineage and axonal wiring of granule cells [1] and to analyze cell division patterns in the granule neuron lineage [2]. Later MADM has also been applied to study genetic control of neuronal morphogenesis, migration and proliferation/survival [2-4], cell cycle regulation [5], the identification of the cell of origin for glioma [6], and the effects of loss of imprinting (LOI) in somatic cells [7]. "
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    ABSTRACT: Mosaic Analysis with Double Markers (MADM) is a mouse genetic system that allows simultaneous gene knockout and fluorescent labeling of sparse, clonally-related cells within an otherwise normal mouse, thereby circumventing embryonic lethality problems and providing single-cell resolution for phenotypic analysis in vivo. The clonal efficiency of MADM is intrinsically low because it relies on Cre/loxP-mediated mitotic recombination between two homologous chromosomes rather than within the same chromosome, as in the case of conditional knockout (CKO). Although sparse labeling enhances in vivo resolution, the original MADM labels too few or even no cells when a low-expressing Cre transgene is used or a small population of cells is studied. Recently, we described the usage of a new system, MADM-ML, which contains three mutually exclusive, self-recognizing loxP variant sites as opposed to a single loxP site present in the original MADM system (referred to as MADM-SL in this paper). Here we carefully compared the recombination efficiency between MADM-SL and MADM-ML using the same Cre transgene, and found that the new system labels significantly more cells than the original system does. When we established mouse medulloblastoma models with both the original and the new MADM systems, we found that, while the MADM-SL model suffered from varied tumor progression and incomplete penetrance, the MADM-ML model had consistent tumor progression and full penetrance of tumor formation. Therefore MADM-ML, with its higher recombination efficiency, will broaden the applicability of MADM for studying many biological questions including normal development and disease modeling at cellular resolution in vivo.
    PLoS ONE 10/2013; 8(10):e77672. DOI:10.1371/journal.pone.0077672 · 3.23 Impact Factor
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