NT5E

NT5E
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 4H2B, 4H1Y, 4H2F, 4H2I, 4H1S, 4H2G
Identifiers
Aliases	NT5E, CALJA, CD73, E5NT, NT, NT5, NTE, eN, eNT, 5'-nucleotidase ecto
External IDs	OMIM: 129190; MGI: 99782; HomoloGene: 1895; GeneCards: NT5E; OMA:NT5E - orthologs
Gene location (Human) Chr. Chromosome 6 (human)[1] Band 6q14.3 Start 85,449,584 bp[1] End 85,495,791 bp[1]
Gene location (Mouse) Chr. Chromosome 9 (mouse)[2] Band 9|9 E3.1 Start 88,209,250 bp[2] End 88,254,145 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in stromal cell of endometrium Achilles tendon jejunal mucosa synovial joint cartilage tissue smooth muscle tissue canal of the cervix tendon of biceps brachii germinal epithelium tibia Top expressed in epithelium of stomach lumbar spinal ganglion left colon right kidney seminal vesicula granulocyte neural layer of retina retinal pigment epithelium proximal tubule skin of external ear More reference expression data BioGPS More reference expression data
Gene ontology Molecular function metal ion binding nucleotide binding hydrolase activity, acting on ester bonds hydrolase activity 5'-nucleotidase activity Cellular component anchored component of membrane extracellular exosome membrane plasma membrane cytosol cell surface nucleoplasm Biological process pyrimidine nucleoside catabolic process negative regulation of inflammatory response purine nucleotide catabolic process AMP catabolic process adenosine biosynthetic process dephosphorylation DNA metabolic process leukocyte cell-cell adhesion nucleotide catabolic process NAD metabolic process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 4907 23959 Ensembl ENSG00000135318 ENSMUSG00000032420 UniProt P21589 Q61503 RefSeq (mRNA) NM_002526 NM_001204813 NM_011851 RefSeq (protein) NP_001191742 NP_002517 NP_035981 Location (UCSC) Chr 6: 85.45 – 85.5 Mb Chr 9: 88.21 – 88.25 Mb PubMed search [3] [4]
Wikidata
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5′-nucleotidase (5′-NT), also known as ecto-5′-nucleotidase or CD73 (cluster of differentiation 73), is an enzyme that in humans is encoded by the NT5E gene.^[5] CD73 commonly serves to convert AMP to adenosine.^[6]

NT5E contains binding sites for transcription factors AP-2, SMAD proteins, SP-1 and elements responsive to c-AMP, which can be found in c-AMP promoter parts. SMADs 2, 3, 4 and 5 and SP-1 are binding to the NT5E promoter in rats, as was proven in chromatin immunoprecipitation assays. Due to the fact, that the human and rat NT5E transcripts are 89% identical, human NT5E could be also regulated by SMAD proteins.^[7]

Ecto-5-prime-nucleotidase (5-prime-ribonucleotide phosphohydrolase; EC 3.1.3.5) catalyzes the conversion at neutral pH of purine 5-prime mononucleotides to nucleosides, the preferred substrate being AMP. The enzyme consists of a dimer of 2 identical 70-kD subunits bound by a glycosyl phosphatidyl inositol linkage to the external face of the plasma membrane. The enzyme is used as a marker of lymphocyte differentiation. Consequently, a deficiency of NT5 occurs in a variety of immunodeficiency diseases (e.g., see MIM 102700, MIM 300300). Other forms of 5-prime nucleotidase exist in the cytoplasm and lysosomes and can be distinguished from ecto-NT5 by their substrate affinities, requirement for divalent magnesium ion, activation by ATP, and inhibition by inorganic phosphate.^[8] Rare allelic variants are associated with a syndrome of adult-onset calcification of joints and arteries (CALJA) affecting the iliac, femoral, and tibial arteries reducing circulation in the legs and the joints of the hands and feet causing pain.^[9][10][11]

NT5E (CD73) is a surface enzyme which is expressed on multiple cells. This enzyme mediates the gradual hydrolysis of the autocrine and paracrine danger signals of ATP and ADP to anti-inflammatory adenosine. Immune suppression mediated by adenosinergic pathways is very important for maintaining immune system homeostasis. Immune suppressive functions of T regulatory cells are also dependent on CD73 expression. Treg's generally suppress the immune response. They affect proliferation and function of T cell.^[12] CD73 also occurs on anergic CD4 + T cells, thereby maintaining self tolerance to healthy tissues as well as protecting the fetus from the mother's immune system during pregnancy. Also described was adenosine generated by NT5E, which limits the inflammatory immune response by negative feedback in neutrophil which express the adenosine receptor.^[13]

Some tumours have upregulation and overexpression of CD73 so it has been proposed as a drug target for cancer therapy.^[14][15][16]

An anti-CD73 antibody CPI-006 has started early stage clinical trials as a treatment for advanced cancers.^[17]

Specialized immune cells such as myeloid-derived suppressor cells and regulatory T cells also mediate their effects via adenosine generated by local ectonucleotidase. In some cases of lupus patients, adequate T cell expression of CD73 is missing, which shows an impaired regulatory function of T cells.^[18]

NT5E can act as an immune inhibitory control molecule. Free adenosine generated by NT5E inhibits cellular immune responses and thereby promotes immune escape of tumor cells.^[13] Due to enzymatic and non-enzymatic properties, CD73 is involved in cancer-related processes and is upregulated in many cancers such as leukemia, glioblastoma, melanoma, oesophageal, prostate, ovarian and breast cancer. It is an important key molecule in cancer regulation and development and is involved in tumor progression. In addition, NT5E functions as an adhesion and signaling molecule and can regulate cellular signaling with extracellular matrix components such as fibronectin and laminin. This can mediate the metastatic and invasive properties of cancer.^[19] In mouse breast and prostate cancer tumor models as well as in breast cancer xenograft model, NT5E was confirmed to support tumor angiogenesis. His expression promotes invasion and metastasis of murine and human melanoma cells and human breast cancer cells. Tumor infiltration by cells which express NT5E such as myeloid derived suppressor cells (MDSC), Treg's, dendritic cells (DC) leads to accumulation of adenosine. Subsequently, cAMP signaling is triggered in T cell that express the adenosine A2A receptor.^[20] Adenosine receptor are also expressed on macrophage, DCs, MDSC and natural killer cell(NK). Thus, adenosine may inhibit the function of these immune cells. In addition, the tumor cells may also express adenosine A1 and A3 receptors associated with Gαi proteins, promoting both the migration and proliferation of tumor cells.^[13][19][21] Especially due to its beneficial effects in mouse tumor model, anti-CD73 therapy is now a promising approach to cancer treatment in the future. CD73 inhibitor are currently being tested in clinical trials for the cancer treatment.^[19]

MicroRNA are small non-coding RNA molecules which regulate gene expression at posttranscriptional level via binding to mRNA. This leads to degradation of the target mRNA molecule or translational repression. In tumor cells the miRNA expression pattern often change and therefore affect the surface NT5E, which as result interfere the anti-tumor immune response.^[22][23] For example, studies confirm the role of the miR30 family in NT5E regulation. Upon miR-30a-5p expression, NT5E expression was decreased.^[13]

• Cluster of differentiation
• Arterial calcification due to CD73 deficiency

• NT5E+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Overview of all the structural information available in the PDB for UniProt: P21589 (5′-nucleotidase) at the PDBe-KB.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.