IDH2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | IDH2 , D2HGA2, ICD-M, IDH, IDHM, IDP, IDPM, mNADP-IDH, isocitrate dehydrogenase (NADP(+)) 2, mitochondrial, isocitrate dehydrogenase (NADP(+)) 2, IDH-2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 147650 MGI: 96414 HomoloGene: 37590 GeneCards: IDH2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Isocitrate dehydrogenase [NADP], mitochondrial is an enzyme that in humans is encoded by the IDH2 gene. [5]
Isocitrate dehydrogenases are enzymes that catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. These enzymes belong to two distinct subclasses, one of which utilizes NAD(+) as the electron acceptor and the other NADP(+). Five isocitrate dehydrogenases have been reported: three NAD(+)-dependent isocitrate dehydrogenases, which localize to the mitochondrial matrix, and two NADP(+)-dependent isocitrate dehydrogenases, one of which is mitochondrial and the other predominantly cytosolic. Each NADP(+)-dependent isozyme is a homodimer. The protein encoded by the IDH2 gene is the NADP(+)-dependent isocitrate dehydrogenase found in the mitochondria. It plays a role in intermediary metabolism and energy production. This protein may tightly associate or interact with the pyruvate dehydrogenase complex. [5] Somatic mosaic mutations of this gene have also been found associated to Ollier disease and Maffucci syndrome. [6]
Isocitrate dehydrogenase is composed of 3 subunits, allosterically regulated, and requires an integrated Mg2+ or Mn2+ ion. The mitochondrial form of IDH, like most isoforms, is a homodimer, in which two identical monomer subunits form one unit. The structure of Mycobacterium tuberculosis IDH-1 bound with NADPH and Mn2+ has been solved by X-ray crystallography. It is a homodimer in which each subunit has a Rossmann fold, and a common top domain of interlocking β sheets. Mtb IDH-1 is most structurally similar to the R132H mutant human IDH found in certain glioblastomas. Similar to human R132H ICDH, Mtb ICDH-1 also catalyzes the formation of α-hydroxyglutarate. [7]
Isocitrate dehydrogenase is a digestive enzyme that is used in the citric acid cycle. Its main function is to catalyze the oxidative decarboxylation of isocitrate into alpha-ketoglutarate. Human isocitrate dehydrogenase regulation is not fully understood however, it is known that NADP and Ca2+ bind in the active site to create three different conformations. These conformations form in the active site and are as follows: a loop is form in the inactive enzyme, a partially unraveled alpha helix in the semi open form, and an alpha helix in the active form. [8]
The mitochondrial form of IDH2 is correlated with many diseases. Mutations in IDH2 are associated with 2-hydroxyglutaric aciduria, a condition that causes progressive damage to the brain. The major types of this disorder are called D-2-hydroxyglutaric aciduria (D-2-HGA), L-2-hydroxyglutaric aciduria (L-2-HGA), and combined D,L-2-hydroxyglutaric aciduria (D,L-2-HGA). The main features of D-2-HGA are delayed development, seizures, weak muscle tone (hypotonia), and abnormalities in the largest part of the brain (the cerebrum), which controls many important functions such as muscle movement, speech, vision, thinking, emotion, and memory. Researchers have described two subtypes of D-2-HGA, type I and type II. The two subtypes are distinguished by their genetic cause and pattern of inheritance, although they also have some differences in signs and symptoms. Type II tends to begin earlier and often causes more severe health problems than type I. Type II may also be associated with a weakened and enlarged heart (cardiomyopathy), a feature that is typically not found with type I. L-2-HGA particularly affects a region of the brain called the cerebellum, which is involved in coordinating movements. As a result, many affected individuals have problems with balance and muscle coordination (ataxia). Additional features of L-2-HGA can include delayed development, seizures, speech difficulties, and an unusually large head (macrocephaly). Typically, signs and symptoms of this disorder begin during infancy or early childhood. The disorder worsens over time, usually leading to severe disability by early adulthood. Combined D,L-2-HGA causes severe brain abnormalities that become apparent in early infancy. Affected infants have severe seizures, weak muscle tone (hypotonia), and breathing and feeding problems. They usually survive only into infancy or early childhood. [5]
Mutations in the IDH2 gene, along with mutations in the IDH1 gene, are also strongly correlated with the development of glioma, acute myeloid leukemia (AML), chondrosarcoma, intrahepatic cholangiocarcinoma (ICC), and angioimmunoblastic T-cell lymphoma cancers. They also cause D-2-hydroxyglutaric aciduria and Ollier and Maffucci syndromes. IDH2 mutations may allow prolonged survival of glioma and ICC cancer cells, but not AML cells. The reason for this is unknown. Missense mutations in the active site of these IDH2 induce a neo-enzymatic reaction wherein NADPH reduces αKG to D-2-hydroxyglutarate, which accumulates and leads to the inhibition of hypoxia-inducible factor 1α (HIF1α) degradation (inhibition of the HIF prolyl-hydroxylase), as well as changes in epigenetics and extracellular matrix homeostasis. Such mutations also imply less NADPH production capacity. [9] Tumors of various tissue types with IDH1/2 mutations show improved responses to radiation and chemotherapy. [10] [11]
Inhibitors of the neomorphic activity of mutant IDH1 and IDH2 are currently in Phase I/II clinical trials for both solid and blood tumors. As IDH1 and IDH2 represent key enzymes within the tricarboxylic acid (TCA) cycle, mutations have significant impact on intermediary metabolism. The loss of some wild-type metabolic activity is an important, potentially deleterious and therapeutically exploitable consequence of oncogenic IDH mutations and requires continued investigation in the future. [12]
Drugs that target mutated forms of IDH2 include :
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
A glioma is a type of tumor that starts in the glial cells of the brain or the spine. Gliomas comprise about 30 percent of all brain tumors and central nervous system tumours, and 80 percent of all malignant brain tumours.
Isocitrate dehydrogenase (IDH) (EC 1.1.1.42) and (EC 1.1.1.41) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a secondary alcohol) to oxalosuccinate (a ketone), followed by the decarboxylation of the carboxyl group beta to the ketone, forming alpha-ketoglutarate. In humans, IDH exists in three isoforms: IDH3 catalyzes the third step of the citric acid cycle while converting NAD+ to NADH in the mitochondria. The isoforms IDH1 and IDH2 catalyze the same reaction outside the context of the citric acid cycle and use NADP+ as a cofactor instead of NAD+. They localize to the cytosol as well as the mitochondrion and peroxisome.
2-hydroxyglutaric aciduria is a rare neurometabolic disorder characterized by the significantly elevated levels of hydroxyglutaric acid in one's urine. It is either autosomal recessive or autosomal dominant.
The study of the tumor metabolism, also known as tumor metabolome describes the different characteristic metabolic changes in tumor cells. The characteristic attributes of the tumor metabolome are high glycolytic enzyme activities, the expression of the pyruvate kinase isoenzyme type M2, increased channeling of glucose carbons into synthetic processes, such as nucleic acid, amino acid and phospholipid synthesis, a high rate of pyrimidine and purine de novo synthesis, a low ratio of Adenosine triphosphate and Guanosine triphosphate to Cytidine triphosphate and Uridine triphosphate, low Adenosine monophosphate levels, high glutaminolytic capacities, release of immunosuppressive substances and dependency on methionine.
Ollier disease is a rare sporadic nonhereditary skeletal disorder in which typically benign cartilaginous tumors (enchondromas) develop near the growth plate cartilage. This is caused by cartilage rests that grow and reside within the metaphysis or diaphysis and eventually mineralize over time to form multiple enchondromas. Key signs of the disorder include asymmetry and shortening of the limb as well as an increased thickness of the bone margin. These symptoms are typically first visible during early childhood with the mean age of diagnosis being 13 years of age. Many patients with Ollier disease are prone to develop other malignancies including bone sarcomas that necessitate treatment and the removal of malignant bone neoplasm. Cases in patients with Ollier disease has shown a link to IDH1, IDH2, and PTH1R gene mutations. Currently, there are no forms of treatment for the underlying condition of Ollier disease but complications such as fractures, deformities, malignancies that arise from it can be treated through surgical procedures. The prevalence of this condition is estimated at around 1 in 100,000. It is unclear whether the men or women are more affected by this disorder due to conflicting case studies.
Maffucci syndrome is a very rare disorder in which multiple benign tumors of cartilage develop within the bones. The tumors most commonly appear in the bones of the hands, feet, and limbs, causing bone deformities and short limbs.
Glutaryl-CoA dehydrogenase (GCDH) is an enzyme encoded by the GCDH gene on chromosome 19. The protein belongs to the acyl-CoA dehydrogenase family (ACD). It catalyzes the oxidative decarboxylation of glutaryl-CoA to crotonyl-CoA and carbon dioxide in the degradative pathway of L-lysine, L-hydroxylysine, and L-tryptophan metabolism. It uses electron transfer flavoprotein as its electron acceptor. The enzyme exists in the mitochondrial matrix as a homotetramer of 45-kD subunits. Mutations in this gene result in the metabolic disorder glutaric aciduria type 1, which is also known as glutaric acidemia type I. Alternative splicing of this gene results in multiple transcript variants.
In enzymology, an L-2-hydroxyglutarate dehydrogenase is an enzyme that catalyzes the chemical reaction
In enzymology, a [isocitrate dehydrogenase (NADP+)] kinase (EC 2.7.11.5) is an enzyme that catalyzes the chemical reaction:
Phosphoglycerate dehydrogenase (PHGDH) is an enzyme that catalyzes the chemical reactions
Isocitrate dehydrogenase [NAD] subunit alpha, mitochondrial (IDH3α) is an enzyme that in humans is encoded by the IDH3A gene.
Isocitrate dehydrogenase [NAD] subunit gamma, mitochondrial is an enzyme that in humans is encoded by the IDH3G gene.
D-2-hydroxyglutarate dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the D2HGDH gene.
Isocitrate dehydrogenase [NAD] subunit beta, mitochondrial is an enzyme that in humans is encoded by the IDH3B gene.
L-2-hydroxyglutarate dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the L2HGDH gene, also known as C14orf160, on chromosome 14.
α-Hydroxyglutaric acid is an alpha hydroxy acid form of glutaric acid.
Isocitrate dehydrogenase 1 (NADP+), soluble is an enzyme that in humans is encoded by the IDH1 gene on chromosome 2. Isocitrate dehydrogenases catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. These enzymes belong to two distinct subclasses, one of which uses NAD+ as the electron acceptor and the other NADP+. Five isocitrate dehydrogenases have been reported: three NAD+-dependent isocitrate dehydrogenases, which localize to the mitochondrial matrix, and two NADP+-dependent isocitrate dehydrogenases, one of which is mitochondrial and the other predominantly cytosolic. Each NADP+-dependent isozyme is a homodimer. The protein encoded by this gene is the NADP+-dependent isocitrate dehydrogenase found in the cytoplasm and peroxisomes. It contains the PTS-1 peroxisomal targeting signal sequence. The presence of this enzyme in peroxisomes suggests roles in the regeneration of NADPH for intraperoxisomal reductions, such as the conversion of 2,4-dienoyl-CoAs to 3-enoyl-CoAs, as well as in peroxisomal reactions that consume 2-oxoglutarate, namely the alpha-hydroxylation of phytanic acid. The cytoplasmic enzyme serves a significant role in cytoplasmic NADPH production. Alternatively spliced transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Sep 2013]
In molecular biology, the isocitrate/isopropylmalate dehydrogenase family is a protein family consisting of the evolutionary related enzymes isocitrate dehydrogenase, 3-isopropylmalate dehydrogenase and tartrate dehydrogenase.
Enasidenib is a medication used to treat relapsed or refractory acute myeloid leukemia in people with specific mutations of the isocitrate dehydrogenase 2 (IDH2) gene, determined by an FDA-approved IDH2 companion diagnostic test. It is an inhibitor of IDH2. It was developed by Agios Pharmaceuticals and is licensed to Celgene for further development.
Ivosidenib, sold under the brand name Tibsovo, is an anti-cancer medication for the treatment of acute myeloid leukemia (AML) and cholangiocarcinoma. It is a small molecule inhibitor of isocitrate dehydrogenase-1 (IDH1), which is mutated in several forms of cancer. Ivosidenib is an isocitrate dehydrogenase-1 inhibitor that works by decreasing abnormal production of the oncometabolite 2-hydroxyglutarate (2-HG), leading to differentiation of malignant cells.