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a cell from which a nerve cell develops

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/10/26 13:26:53」(JST)

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A neuroblast is a dividing cell that will develop into a neuron often after a migration phase.^[1] Neuroblasts differentiate from neural stem cells and are committed to the neuronal fate.^[2] The main difference between a neuroblast and a neuron is the ability to divide; neuroblasts can still undergo mitosis, whereas neurons are postmitotic.

Neuroblasts are mainly present as precursors of neurons during embryonic development, however, they also constitute one of the cell types involved in adult neurogenesis. Adult neurogenesis is characterized by neural stem cell differentiation and integration in the mature adult mammalian brain. This process occurs in the dentate gyrus of the hippocampus and in the subventricular zones of the adult mammalian brain. Neuroblasts are formed when a neural stem cell, which can differentiate into any type of mature neural cell (i.e. neurons, oligodendrocytes, astrocytes, etc.), divides and becomes a transit amplifying cell. Transit amplifying cells are slightly more differentiated than neural stem cells and can divide asymmetrically to produce postmitotic neuroblasts or glioblasts, as well as other transit amplifying cells. A neuroblast, a daughter cell of a transit amplifying cell, is initially a neural stem cell that has reached the "point of no return." A neuroblast has differentiated such that it will mature into a neuron and not any other neural cell type.^[3] Neuroblasts are being studied extensively as they have the potential to be used therapeutically to combat cell loss due to injury or disease in the brain, although their potential effectiveness is debated.

In humans, neuroblasts produced by stem cells in the adult subventricular zone migrate into damaged areas after brain injuries. However, they are restricted to the subtype of small interneuron-like cells, and it is unlikely that they contribute to functional recovery of striatial circuits.^[4]

The characterisation of neuroblasts and their development in Drosophila melanogaster was widely achieved by Chris Doe, Corey Goodman and Mike Bate.

Neuroblasts development in Drosophila

In the neuroectoderm, small clusters of equivalent cells acquire the potential to become neuroblasts, through the expression of proneural genes. From there, one particular cell from each cluster is selected to become a neuroblast, through the action of the Notch signaling pathway. Once the future neuroblast cells are selected, they delaminate, then carry on dividing for a pre-programmed number of divisions.

Neuroblasts divide asymmetrically at every stage, creating one cell that continues being a neuroblast, and one cell that becomes the Ganglion Mother Cell (GMC), which goes on to divide into 4 differentiated cells (neurons or glia). The switch from pluripotent neuroblast to differentiated cell fate is facilitated by the proteins Prospero, Numb, and Miranda. Prospero is a transcription factor that triggers differentiation. It is expressed in neuroblasts, but is kept out of the nucleus by Miranda, which tethers it to the cell basal cortex. This also results in asymmetric division, where Prospero localizes in only one out of the two daughter cells. After division, Prospero enters the nucleus, and the cell it is present in becomes the GMC.

Each neuroblast goes on to create a specific sequence of cells with particular identities. This is partly based on the position of the neuroblast along the Anterior/Posterior and Dorsal/Ventral axes, and partly on a temporal sequence of transcription factors that are expressed in a specific order as neuroblasts undergo sequential divisions.

References

^ Purves, D (2001). "The Initial Differentiation of Neurons and Glia". Neuroscience. Sinauer Associates.
^ "wberesford.hsc.wvu.edu". Retrieved 2010-04-08.
^ Purves, D; et al. (2007). Neuroscience. (4th ed.). New York: W. H. Freeman. ISBN 978-0-87893-697-7.
^ Liu, F; You, Y; Li, X; Ma, T; Nie, Y; Wei, B; Li, T; Lin, H; Yang, Z (April 2009). "Brain Injury Does Not Alter the Intrinsic Differentiation Potential of Adult Neuroblasts". The Journal of Neuroscience. 29 (16): 5075–5087. doi:10.1523/JNEUROSCI.0201-09.2009. PMID 19386903.

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Moore SW, Sidler D, Schubert PA.SourceDivision of Pediatric Surgery, Department of Surgical Sciences, Faculty of Health Sciences, University of Stellenbosch, P.O. Box 19063, Tygerberg, 7505, South Africa, SWM@sun.ac.za.
Pediatric surgery international.Pediatr Surg Int.2013 Mar 2. [Epub ahead of print]
INTRODUCTION: There is accumulating evidence that "skip" lesions or zonal aganglionosis do occur in HSCR disease, albeit rarely. They are of interest because it may cause confusion in interpreting surgical margins as well as understanding the pathophysiology of HSCR disease. Normally described as "a
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Ependymal ciliary dysfunction and reactive astrocytosis in a reorganized subventricular zone after stroke.

Young CC, van der Harg JM, Lewis NJ, Brooks KJ, Buchan AM, Szele FG.SourceDepartment of Physiology, Anatomy and Genetics.
Cerebral cortex (New York, N.Y. : 1991).Cereb Cortex.2013 Mar;23(3):647-59. doi: 10.1093/cercor/bhs049. Epub 2012 Mar 13.
Subventricular zone (SVZ) astrocytes and ependymal cells are both derived from radial glia and may have similar gliotic reactions after stroke. Diminishing SVZ neurogenesis worsens outcomes in mice, yet the effects of stroke on SVZ astrocytes and ependymal cells are poorly understood. We used mouse
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Caenorhabditis elegans PIG-1/MELK Acts in a Conserved PAR-4/LKB1 Polarity Pathway to Promote Asymmetric Neuroblast Divisions.

Chien SC, Brinkmann EM, Teuliere J, Garriga G.SourceDepartment of Molecular and Cell Biology University of California, Berkeley, California 94720.
Genetics.Genetics.2013 Mar;193(3):897-909. doi: 10.1534/genetics.112.148106. Epub 2012 Dec 24.
Asymmetric cell divisions produce daughter cells with distinct sizes and fates, a process important for generating cell diversity during development. Many Caenorhabditis elegans neuroblasts, including the posterior daughter of the Q cell (Q.p), divide to produce a larger neuron or neuronal precursor
PMID 23267054