Down syndrome critical region gene 1, also known as DSCR1, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that in humans is encoded by the ''RCAN1''

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Gene location and organization

DSCR1 in human is located at the centromeric border of the DSCR and encodes an inhibitor of calcineurin/

NFAT Nuclear factor of activated T-cells (NFAT) is a family of transcription factors shown to be important in immune response. One or more members of the NFAT family is expressed in most cells of the immune system. NFAT is also involved in the developme ...

(nuclear factor activated T cells) signalling. DSCR1 genomic sequence of total 45 kb contain 7 exons and 6

introns An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e. a region inside a gene."The notion of the cistron .e., gene ...

, different cDNA analysis yield first four exons are alternative and code for two isoforms of 197 amino acids, and one isoform code for 171 amino acids which differ in their

N terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amin ...

. While the rest of the 168 residues are common. There is also alternative promoter region with about 900 bp between exon 3 and 4 suggesting that the fourth isoform might be penetrated from another promoter.

Function

The

encoded by this gene interacts with calcineurin A and inhibits calcineurin-dependent

signaling pathways Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellula ...

of genetic transcription, possibly affecting

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

development. Three transcript variants encoding three different

isoforms A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some iso ...

have been found for this gene. In

endothelial The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...

cells,

VEGF Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors ...

stimulates RCAN1.4 expression which regulates gene expression, cell migration and tubular morphogenesis.

Structure

DSCR1 Consist of putative functional motifs and calcineurin binding domain. DSCR1 contains two proline-rich SH3 binding domain, usually named proline-rich domain (PRD), which defines the protein family.

SH3 domain The SRC Homology 3 Domain (or SH3 domain) is a small protein domain of about 60 amino acid residues. Initially, SH3 was described as a conserved sequence in the viral adaptor protein v-Crk. This domain is also present in the molecules of phos ...

s or PRD are very important to allow the binding of the protein to endocytosis-related proteins such as

ITSN1 Intersectin-1 is a protein that, in humans, is encoded by the ''ITSN1'' gene. Function The protein encoded by this gene is a cytoplasmic membrane-associated protein that indirectly coordinates endocytic membrane traffic with the actin assembly ...

and

amphiphysin Amphiphysin is a protein that in humans is encoded by the ''AMPH'' gene. Function This gene encodes a protein associated with the cytoplasmic surface of synaptic vesicles. A subset of patients with stiff person syndrome who were also affected ...

1 and 2.

Clinical significance

This gene is located in the minimal candidate region for the

Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...

, and is overexpressed in the brain of Down syndrome fetuses. Chronic overexpression of this gene may lead to

neurofibrillary tangles Neurofibrillary tangles (NFTs) are aggregates of hyperphosphorylated tau protein that are most commonly known as a primary biomarker of Alzheimer's disease. Their presence is also found in numerous other diseases known as tauopathies. Little is ...

such as those associated with Alzheimer's disease. RCAN1 helps coordinate whole-body metabolism and can be an important target in treatment of obesity.

Associated diseases

Central nervous system

All Down syndrome (DS) patients develop neuropathological changes identical to the pathogenesis of Alzheimer's disease (AD) in middle age, such as

neuritic plaque Amyloid plaques (also known as neuritic plaques, amyloid beta plaques or senile plaques) are extracellular deposits of the amyloid beta (Aβ) protein mainly in the grey matter of the brain. Degenerative neuronal elements and an abundance of mi ...

s and neuronal loss. Therefore, DS patients are perfect models to study AD pathogenesis. Chronic DSCR1 overexpression is related with DS and AD, while its shortage is reported in

Huntington’s disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an unst ...

. DSCR1 expressed excessively in the Central Nervous System of embryos, and the protein is later overexpressed in brains of DS patients. However, neurotrophic peptide

PACAP Pituitary adenylate cyclase-activating polypeptide also known as PACAP is a protein that in humans is encoded by the ''ADCYAP1'' gene. pituitary adenylate cyclase-activating polypeptide is similar to vasoactive intestinal peptide. One of its effect ...

(or Pituitary adenylate cyclase-activating peptide) which is responsible for the development, differentiation, and survival, and various parts of memory and learning, targets RCAN1, a Down syndrome related gene, induces the expression of regulator of calcineurin 1, through activation of the PKA-CREB pathway, and this is important to understand the mechanisms of neural differentiation and aim for proper expression of RCAN1.

Cancer

It is suggested that the reason patients with

are less predisposed to certain cancers is due to the impact of this gene of reducing blood supply to tumour cells. It is also proposed by epidemiological studies that DS patients are in greater risk of

leukaemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...

, on the other hand they are at lower risk of cancer and other angiogenesis related diseases such as

diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease), is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 perc ...

and

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually no s ...

, indicating that one or more trisomic genes on chromosome 21 is responsible for protecting DS patients against cancer, and this cancer defence could be a result of angiogenesis suppression.

Interactions

DSCR1 has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...

with

Calcineurin Calcineurin (CaN) is a calcium and calmodulin dependent serine/threonine protein phosphatase (also known as protein phosphatase 3, and calcium-dependent serine-threonine phosphatase). It activates the T cells of the immune system and can be block ...

. Hydrogen peroxide (H₂O₂) increases the overexpression of protein RCAN1. However, anti-oxidants and inhibitors of

mitogen-activated protein kinases A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses ...

(MAPK) treatment block the increased expression of RCAN1 by H₂O₂. Demonstrating that the increased expression is a result of generating reactive oxygen species and activation of MAPK. Furthermore, phosphorylation is important to regulator RCAN1 protein expression. Because phosphorylation of RCAN1 expression by H₂O₂ increases of the half-life of the protein.