Search results for DAO

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Pathway (4 results from a total of 4)

Identifier: R-HSA-5628897
Species: Homo sapiens
While the p53 tumor suppressor protein (TP53) is known to inhibit cell growth by inducing apoptosis, senescence and cell cycle arrest, recent studies have found that p53 is also able to influence cell metabolism to prevent tumor development. TP53 regulates transcription of many genes involved in the metabolism of carbohydrates, nucleotides and amino acids, protein synthesis and aerobic respiration.

TP53 stimulates transcription of TIGAR, a D-fructose 2,6-bisphosphatase. TIGAR activity decreases glycolytic rate and lowers ROS (reactive oxygen species) levels in cells (Bensaad et al. 2006). TP53 may also negatively regulate the rate of glycolysis by inhibiting the expression of glucose transporters GLUT1, GLUT3 and GLUT4 (Kondoh et al. 2005, Schwartzenberg-Bar-Yoseph et al. 2004, Kawauchi et al. 2008).

TP53 negatively regulates several key points in PI3K/AKT signaling and downstream mTOR signaling, decreasing the rate of protein synthesis and, hence, cellular growth. TP53 directly stimulates transcription of the tumor suppressor PTEN, which acts to inhibit PI3K-mediated activation of AKT (Stambolic et al. 2001). TP53 stimulates transcription of sestrin genes, SESN1, SESN2, and SESN3 (Velasco-Miguel et al. 1999, Budanov et al. 2002, Brynczka et al. 2007). One of sestrin functions may be to reduce and reactivate overoxidized peroxiredoxin PRDX1, thereby reducing ROS levels (Budanov et al. 2004, Papadia et al. 2008, Essler et al. 2009). Another function of sestrins is to bind the activated AMPK complex and protect it from AKT-mediated inactivation. By enhancing AMPK activity, sestrins negatively regulate mTOR signaling (Budanov and Karin 2008, Cam et al. 2014). The expression of DDIT4 (REDD1), another negative regulator of mTOR signaling, is directly stimulated by TP63 and TP53. DDIT4 prevents AKT-mediated inactivation of TSC1:TSC2 complex, thus inhibiting mTOR cascade (Cam et al. 2014, Ellisen et al. 2002, DeYoung et al. 2008). TP53 may also be involved, directly or indirectly, in regulation of expression of other participants of PI3K/AKT/mTOR signaling, such as PIK3CA (Singh et al. 2002), TSC2 and AMPKB (Feng et al. 2007).

TP53 regulates mitochondrial metabolism through several routes. TP53 stimulates transcription of SCO2 gene, which encodes a mitochondrial cytochrome c oxidase assembly protein (Matoba et al. 2006). TP53 stimulates transcription of RRM2B gene, which encodes a subunit of the ribonucleotide reductase complex, responsible for the conversion of ribonucleotides to deoxyribonucleotides and essential for the maintenance of mitochondrial DNA content in the cell (Tanaka et al. 2000, Bourdon et al. 2007, Kulawiec et al. 2009). TP53 also transactivates mitochondrial transcription factor A (TFAM), a nuclear-encoded gene important for mitochondrial DNA (mtDNA) transcription and maintenance (Park et al. 2009). Finally, TP53 stimulates transcription of the mitochondrial glutaminase GLS2, leading to increased mitochondrial respiration rate and reduced ROS levels (Hu et al. 2010).

The great majority of tumor cells generate energy through aerobic glycolysis, rather than the much more efficient aerobic mitochondrial respiration, and this metabolic change is known as the Warburg effect (Warburg 1956). Since the majority of tumor cells have impaired TP53 function, and TP53 regulates a number of genes involved in glycolysis and mitochondrial respiration, it is likely that TP53 inactivation plays an important role in the metabolic derangement of cancer cells such as the Warburg effect and the concomitant increased tumorigenicity (reviewed by Feng and Levine 2010). On the other hand, some mutations of TP53 in Li-Fraumeni syndrome may result in the retention of its wild-type metabolic activities while losing cell cycle and apoptosis functions (Wang et al. 2013). Consistent with such human data, some mutations of p53, unlike p53 null state, retain the ability to regulate energy metabolism while being inactive in regulating its classic gene targets involved in cell cycle, apoptosis and senescence. Retention of metabolic and antioxidant functions of p53 protects p53 mutant mice from early onset tumorigenesis (Li et al. 2012).

Identifier: R-HSA-1169408
Species: Homo sapiens
Compartment: cytosol
Interferon-stimulated gene 15 (ISG15) is a member of the ubiquitin-like (Ubl) family. It is strongly induced upon exposure to type I Interferons (IFNs), viruses, bacterial LPS, and other stresses. Once released the mature ISG15 conjugates with an array of target proteins, a process termed ISGylation. ISGylation utilizes a mechanism similar to ubiquitination, requiring a three-step enzymatic cascade. UBE1L is the ISG15 E1 activating enzyme which specifically activates ISG15 at the expense of ATP. ISG15 is then transfered from E1 to the E2 conjugating enzyme UBCH8 and then to the target protein with the aid of an ISG15 E3 ligase, such as HERC5 and EFP. Hundreds of target proteins for ISGylation have been identified. Several proteins that are part of antiviral signaling pathways, such as RIG-I, MDA5, Mx1, PKR, filamin B, STAT1, IRF3 and JAK1, have been identified as targets for ISGylation. ISG15 also conjugates some viral proteins, inhibiting viral budding and release. ISGylation appears to act either by disrupting the activity of a target protein and/or by altering its localization within the cell.
Identifier: R-HSA-5339716
Species: Homo sapiens
Compartment: cytosol
GSK3beta is subject to in-frame missplicing in CML stem cells resulting in the production of mutant protein that lacks the AXIN and FRAT binding domains. Cells containing this mutant GSK3beta show elevated levels of nuclear beta-catenin and enhanced TCF-dependent reporter activity (Jamieson et al, 2008; Abrahamsson et al, 2009).
Identifier: R-HSA-9703465
Species: Homo sapiens
Compartment: cytosol
In addition to internal tandem duplications and activating point mutations, FLT3 is also subject at low frequency to translocations that generate fusion proteins. These fusion proteins occur in some chronic myeloid leukemias as well as myeloid neoplasms with eosinophilia, and generate constitutively active proteins by virtue of fusing a N-terminal partner encoding a dimerization domain with the intracellular region of FLT3 (reviewed in Reiter and Gotlib, 2017; Kazi and Roonstrand, 2019). To date, 6 fusion partner genes of FLT3 have been identified: ETV6, TRIP11, MYO18A, SPTBN1, GOLGB1 and ZMYM2 (Balwin et al, 2007; Vu et al, 2006; Walz et al, 2011; Falchi et al, 2014; Chung et al, 2017; Troadec et al, 2017; Grand et al, 2007; Jawhar et al, 2017; Zhang et al, 2018).
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