Netrin-1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''NTN1''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Netrin is included in a
family of laminin-related secreted proteins. The function of this gene has not yet been defined; however, netrin is thought to be involved in
axon guidance
Axon guidance (also called axon pathfinding) is a subfield of neural development concerning the process by which neurons send out axons to reach their correct targets. Axons often follow very precise paths in the nervous system, and how they mana ...
and
cell migration
Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryogenesis, embryonic development, wound healing and immune system, immune responses all require the orchestrated movemen ...
during development. Mutations and loss of expression of netrin suggest that variation in netrin may be involved in cancer development.
Interactions
NTN1 has been shown to
interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization advocating for the legal and human rights of children with intersex traits. The organization was founded in 2006 and fo ...
with
Deleted in Colorectal Cancer
Netrin receptor DCC, also known as DCC, or colorectal cancer suppressor is a protein which in humans is encoded by the ''DCC'' gene. DCC has long been implicated in colorectal cancer and its previous name was ''Deleted in colorectal carcinoma''. ...
,
and components of the extracellular matrix and the tumor microenvironment.
Midline crossing of commissural axons
During the development of the central nervous system, when the dorsal and ventral signaling is being established, the floor plate is an important site for crossing for groups of neural processes at the dorsal midline. Once crossed through the floor plate, these groups are now referred to as commissural axons. These neuronal cell bodies are signaled by Netrin 1 to be attracted to the floor plate from the dorsal half of the neural tube. NTN1 is a gene that encodes for the protein, Netrin-1. In a study done in knockout mice with a depletion of floor plate Netrin-1, it was shown that corticospinal axon tract midline crossing was disrupted. This study was done to show characteristics of patients with human
congenital mirror movement disorder
Congenital mirror movement disorder (CMM disorder) is a rare genetic neurological disorder which is characterized by mirrored movement, sometimes referred to as associated or synkinetic movement, most often in the upper extremity of the body. The ...
.
Afterwards, proper positioning of axons and midline crossing are pioneered by the Slit-Robo system where Slit proteins act as axonal repellents and Robo proteins (Robo-1, Robo-2, Robo-3) act in conjunction with Slit ligands to be their receptors.
Slit with Robo-1 and Robo-2 repel axonal extension at the midline thereby commissural axons expressing Robo-3 cross the midline by interfering with Slit/Robo-1, Robo-2 repulsive activity. After crossing the floor plate, Robo-3 is downregulated and Slit/Robo-1, Robo-2 continue to express their repulsiveness at the midline. Furthermore, mutations in Robo-3 cause horizontal gaze palsy with progressive scoliosis.
References
Further reading
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External links
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Netrins
{{Gene-17-stub