Nestin (protein)
Encyclopedia
Nestin is a type VI intermediate filament
(IF) protein. These intermediate filament proteins are expressed mostly in nerve cells where they are implicated in the radial growth of the axon. Seven genes encode for the heavy (NF-H), medium (NF-M) and light neurofilament (NF-L) proteins, nestin and α-internexin in nerve cells, synemin α and desmuslin/synemin β (two alternative transcripts of the DMN gene) in muscle cells, and syncoilin (also in muscle cells). Members of this group mostly preferentially coassemble as heteropolymers in tissues. Steinert et al. has shown that nestin forms homodimers and homotetramers but does not form IF by itself in vitro. In mixtures, nestin preferentially co-assembles with purified vimentin or the type IV IF protein -internexin to form heterodimer coiled-coil molecules.
After subcloning the human nestin gene into plasmid vectors, Dahlstrand et al. determined the nucleotide
sequence of all coding regions and parts of the intron
s. In order to establish the boundaries of the introns, they used the polymerase chain reaction
(PCR) to amplify a fragment made from human fetal brain cDNA using two primers
located in the first and fourth exon
, respectively. The resulting 270 base pair (bp) long fragment was then sequenced directly in its entirety, and intron positions precisely located by comparison with the genomic sequence. Putative initiation and stop codon
s for the human nestin gene were found at the same positions as in the rat gene, in regions where overall similarity was very high. Based on this assumption, the human nestin gene encodes a protein with 1618 amino acid
s, i.e. 187 amino acids shorter than the rat protein.
. Nestin is an intermediate filament protein expressed in dividing cells during the early stages of development in the central nervous system (CNS), peripheral nervous system (PNS) and in myogenic and other tissues. Upon differentiation, nestin becomes downregulated and is replaced by tissue-specific intermediate filament proteins. During neuro- and gliogenesis, nestin is replaced by cell type-specific intermediate filaments, e.g. neurofilaments and glial fibrillary acidic protein (GFAP
). Interestingly, nestin expression is reinduced in the adult during pathological situations, such as the formation of the glial scar after CNS injury and during regeneration of injured muscle tissue.
Nestin has recently received attention as a marker for detecting newly formed endothelial cells. In a study, Teranishi et al. examined and came to the conclusion that nestin is a novel angiogenesis marker of proliferating endothelial cells in colorectal cancer tissue.
with Cyclin-dependent kinase 5
.
Intermediate filament
Intermediate filaments are a family of related proteins that share common structural and sequence features. Intermediate filaments have an average diameter of 10 nanometers, which is between that of 7 nm actin , and that of 25 nm microtubules, although they were initially designated...
(IF) protein. These intermediate filament proteins are expressed mostly in nerve cells where they are implicated in the radial growth of the axon. Seven genes encode for the heavy (NF-H), medium (NF-M) and light neurofilament (NF-L) proteins, nestin and α-internexin in nerve cells, synemin α and desmuslin/synemin β (two alternative transcripts of the DMN gene) in muscle cells, and syncoilin (also in muscle cells). Members of this group mostly preferentially coassemble as heteropolymers in tissues. Steinert et al. has shown that nestin forms homodimers and homotetramers but does not form IF by itself in vitro. In mixtures, nestin preferentially co-assembles with purified vimentin or the type IV IF protein -internexin to form heterodimer coiled-coil molecules.
Gene structure
Structurally, nestin has the shortest head domain (N-terminus) and the longest tail domain (C-terminus) of all the IF proteins. Nestin is of high molecular weight (240kDa) with a terminus greater than 500 residues (compared to cytokeratins and lamins with termini less than 50 residues).After subcloning the human nestin gene into plasmid vectors, Dahlstrand et al. determined the nucleotide
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
sequence of all coding regions and parts of the intron
Intron
An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...
s. In order to establish the boundaries of the introns, they used the polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
(PCR) to amplify a fragment made from human fetal brain cDNA using two primers
Primer (molecular biology)
A primer is a strand of nucleic acid that serves as a starting point for DNA synthesis. They are required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA...
located in the first and fourth exon
Exon
An exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA...
, respectively. The resulting 270 base pair (bp) long fragment was then sequenced directly in its entirety, and intron positions precisely located by comparison with the genomic sequence. Putative initiation and stop codon
Stop codon
In the genetic code, a stop codon is a nucleotide triplet within messenger RNA that signals a termination of translation. Proteins are based on polypeptides, which are unique sequences of amino acids. Most codons in messenger RNA correspond to the addition of an amino acid to a growing polypeptide...
s for the human nestin gene were found at the same positions as in the rat gene, in regions where overall similarity was very high. Based on this assumption, the human nestin gene encodes a protein with 1618 amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s, i.e. 187 amino acids shorter than the rat protein.
Expression
Nestin is expressed by many types of cells during development, although its expression is usually transient and does not persist into adulthood. One instance of nestin expression in adult organisms, and perhaps that for which nestin is best known, are the neuronal precursor cells of the subventricular zoneSubventricular 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....
. Nestin is an intermediate filament protein expressed in dividing cells during the early stages of development in the central nervous system (CNS), peripheral nervous system (PNS) and in myogenic and other tissues. Upon differentiation, nestin becomes downregulated and is replaced by tissue-specific intermediate filament proteins. During neuro- and gliogenesis, nestin is replaced by cell type-specific intermediate filaments, e.g. neurofilaments and glial fibrillary acidic protein (GFAP
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...
). Interestingly, nestin expression is reinduced in the adult during pathological situations, such as the formation of the glial scar after CNS injury and during regeneration of injured muscle tissue.
Function
Although it is utilized as a marker of proliferating and migrating cells very little is known about its functions or regulation. In depth studies on the distribution and expression of nestin in mitotically active cells indicate a complex role in regulation of the assembly and disassembly of intermediate filaments which together with other structural proteins, participate in remodeling of the cell. The role of nestin in dynamic cells, particularly structural organization of the cell, appears strictly regulated by phosphorylation, especially its integration into heterogeneous intermediate filaments together with vimentin or α -internexin. Furthermore, nestin expression has been extensively used as a marker for central nervous system (CNS) progenitor cells in different contexts, based on observations indicating a correlation between nestin expression and this cell type in vivo.Recent findings
Nestin, a protein marker for neural stem cells, is also expressed in follicle stem cells and their immediate, differentiated progeny. The hair follicle bulge area is an abundant, easily accessible source of actively growing pluripotent adult stem cells. Green fluorescent protein (GFP), whose expression is driven by the nestin regulatory element in transgenic mice, serves to mark hair follicle stem cells. These cells can differentiate into neurons, glia, keratinocytes, smooth muscle cells and melanocytes in vitro. Thus, hair follicle stem cells provide an effective, accessible, autologous source of stem cells for treatment of peripheral nerve injury.Nestin has recently received attention as a marker for detecting newly formed endothelial cells. In a study, Teranishi et al. examined and came to the conclusion that nestin is a novel angiogenesis marker of proliferating endothelial cells in colorectal cancer tissue.
Interactions
Nestin (protein) has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with Cyclin-dependent kinase 5
Cyclin-dependent kinase 5
Cell division protein kinase 5 is an enzyme that in humans is encoded by the CDK5 gene. The protein encoded by this gene is part of the cyclin-dependent kinase family.-Physiological Role:...
.