Radial glia
Encyclopedia
Radial glial cells are a pivotal cell
type in the developing central nervous system
(CNS) involved in key developmental processes, from patterning and neuronal migration to their recently discovered role as precursor
s during neurogenesis
. They arise early in development from neuroepithelial cell
s. Radial phenotype is typically transient, but some cells, such as Bergmann glia in the cerebellum
and Muller glia
in the retina
, retain radial glia-like morphology postnatally. According to recent research, during the late stages of cortical development, radial glial cells divide asymmetrically in the ventricular zone to generate radial glial cells, postmitotic neurons and intermediate progenitor cells. Intermediate progenitor cells then divide symmetrically in the subventricular zone
to generate neurons. During gliogenesis
, radial glial cells differentiate into astrocytes.
The term 'radial glial cell' refers to their two major characteristics, their long radial processes
extending from the ventricular zone (VZ) to the pial surface
and their glial properties, such as the content of glycogen
granules or the expression of the astrocyte
-specific glutamate transporter or the glial fibrillary acidic protein
(GFAP). Another radial glia-specific protein is the brain lipid binding protein
(FABP7), expression of which could be induced by Notch-1 activation, in particular, when acted upon by reelin
. Interestingly, Notch 1, then activated before birth, induces radial glia differentiation, but postnatally induces the differentiation into astrocyte
s.
Studies show that radial glial cells characterized by long radial processes and astroglial
properties constitute the majority of precursors during neurogenesis
. Indeed, all radial glial cells divide throughout neurogenesis and give rise to the majority of projection neurons in the cerebral cortex
.
Expression of the PAX6
, a transcription factor
, was found to be the key feature of neurogenic radial glia.
Fgf10 has been shown to regulate the differentiation of radial glia from norepithelial cells.
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
type in the developing central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(CNS) involved in key developmental processes, from patterning and neuronal migration to their recently discovered role as precursor
Progenitor cell
A progenitor cell is a biological cell that, like a stem cell, has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target" cell...
s during neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...
. They arise early in development from neuroepithelial cell
Neuroepithelial cell
Neuroepithelial cells are the "stem cells" of the nervous system, deriving from actual stem cells in several different stages of development and differentiating further into multiple types of cells...
s. Radial phenotype is typically transient, but some cells, such as Bergmann glia in the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
and Muller glia
Muller glia
Müller glia, or Müller cells, are glial cells found in the vertebrate retina, which normally serve the functions of any normal glial cells. However, following injury to the retina, it has been seen that Müller glia undergo dedifferentiation into multipotent progenitor cells...
in the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
, retain radial glia-like morphology postnatally. According to recent research, during the late stages of cortical development, radial glial cells divide asymmetrically in the ventricular zone to generate radial glial cells, postmitotic neurons and intermediate progenitor cells. Intermediate progenitor cells then divide symmetrically in the subventricular zone
Subventricular zone
The subventricular zone is a paired brain structure situated throughout the lateral walls of the lateral ventricles. It has been associated with having four distinct layers of variable thickness and cell density, as well as cellular composition....
to generate neurons. During gliogenesis
Gliogenesis
Gliogenesis is the generation of non-neuronal glia populations derived from multipotent neural stem cells.-Overview:Gliogenesis results in the formation of non-neuronal glia populations derived from multipotent neural stem cells. In this capacity, glial cells provide multiple functions to both the...
, radial glial cells differentiate into astrocytes.
The term 'radial glial cell' refers to their two major characteristics, their long radial processes
Process (anatomy)
In anatomy, a process is a projection or outgrowth of tissue from a larger body. The vertebra has several kinds of processes,such as: transverse process, prezygapophysis, postzygapophysis.-Examples:Examples of processes include:...
extending from the ventricular zone (VZ) to the pial surface
Pia mater
Pia mater often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. The word finds its roots in Latin, meaning literally "tender mother." The other two meningeal membranes are the dura mater and the arachnoid mater....
and their glial properties, such as the content of glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
granules or the expression of the astrocyte
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
-specific glutamate transporter or the glial fibrillary acidic protein
Glial fibrillary acidic protein
Glial fibrillary acidic protein is an intermediate filament protein that was thought to be specific for astrocytes in the central nervous system . Later, it was shown that GFAP is also expressed by other cell types in CNS, including ependymal cells...
(GFAP). Another radial glia-specific protein is the brain lipid binding protein
FABP7
Fatty acid binding protein 7, brain , is a human gene.FABP7 is expressed, during development, in radial glia by the activation of Notch receptors...
(FABP7), expression of which could be induced by Notch-1 activation, in particular, when acted upon by reelin
Reelin
Reelin is a large secreted extracellular matrix protein that helps regulate processes of neuronal migration and positioning in the developing brain by controlling cell–cell interactions. Besides this important role in early development, reelin continues to work in the adult brain. It modulates the...
. Interestingly, Notch 1, then activated before birth, induces radial glia differentiation, but postnatally induces the differentiation into astrocyte
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
s.
Studies show that radial glial cells characterized by long radial processes and astroglial
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
properties constitute the majority of precursors during neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...
. Indeed, all radial glial cells divide throughout neurogenesis and give rise to the majority of projection neurons in the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
.
Expression of the PAX6
PAX6
Paired box protein Pax-6 also known as aniridia type II protein or oculorhombin is a protein that in humans is encoded by the PAX6 gene.- Function :PAX6 is a member of the Pax gene family...
, a transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
, was found to be the key feature of neurogenic radial glia.
Fgf10 has been shown to regulate the differentiation of radial glia from norepithelial cells.
See also
- Bergmann glia
- Glia
- GliogenesisGliogenesisGliogenesis is the generation of non-neuronal glia populations derived from multipotent neural stem cells.-Overview:Gliogenesis results in the formation of non-neuronal glia populations derived from multipotent neural stem cells. In this capacity, glial cells provide multiple functions to both the...
- Muller gliaMuller gliaMüller glia, or Müller cells, are glial cells found in the vertebrate retina, which normally serve the functions of any normal glial cells. However, following injury to the retina, it has been seen that Müller glia undergo dedifferentiation into multipotent progenitor cells...
- NeurogenesisNeurogenesisNeurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...
- ventricular zone