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Hypoxia-inducible factor-1 (HIF-1), identified as one of the transcription factors, has been found to play an essential role in cellular and systemic oxygen homeostasis. HIF-1 is a heterodimer composed of HIF-1b subunit and one of three subunits (Hif-1a, Hif-2 (or Hif-3)). The activation of Hif-1 (is closely associated with a variety of tumors and oncogenic pathways. Hif-1 (consists of DNA binding domain (DBD domain), Dimerization domain and C-terminal regulatory domains, including two transactivation domains (TAD), an oxygen-dependent degradation (ODD) domain, and inhibitory domains. Under hypoxic conditions HIF1A activates the transcription of more than 40 genes, including, erythropoietin, glucose transporters, glycolytic enzymes, VEGF, and other genes whose protein products increase oxygen delivery or facilitate metabolic adaptation to hypoxia. HIF-1A also plays a crucial role in embryonic vascularization, tumor angiogenesis and pathophysiology of ischemic disease. It binds to core DNA sequence 5'-[AG]CGTG-3' within the hypoxia response element (HRE) of target gene promoters. Activation involves recruitment of transcriptional coactivators such as CREBPB and EP300. Its activity is improved by interaction with both, NCOA1 or NCOA2. Interaction with redox regulatory protein APEX appears to activate CTAD and potentiates activation by NCOA1 and CREBBP. The induction is under reduced oxygen tension. HIF1A is also induced by a variety of receptor-mediated factors such as growth factors, cytokines, and circulatory factors for example PDGF, EGF, FGF-2, IGF-2, TGF-1 beta, HGF, TNF alpha, IL-1 beta, angiotensin-2 and thrombin. Nevertheless, this induction is less intense than that stimulated by hypoxia.

Overexpression of the HIF1AN is linked with tumor aggressiveness in pancreatic endocrine tumors. HIF1AN hydroxylates Notch ICD at two residues that are crucial for the function of Notch ICD as a transactivator within cells and during neurogenesis and myogenesis. HIF1AN is commonly expressed in invasive breast carcinoma. The hypoxic response and survival recommends that tumour regulation of HIF1AN is an additional important mechanism for HIF pathway activation. HIF1AN is an asparaginyl hydroxylase enzyme that controls the transcriptional activity of hypoxia-inducible factor. FIH1 is a part of the Fe2+ and 2-oxoglutarate-dependent dioxygenase superfamily, FIH1 is protein that hydoxylates a specific asparagine residue (Asn-803) within the HIF1A C-terminal transactivation domain. In normoxia, the HIF1AN-mediated hydroxylation of the HIF1? transactivation domain which results in blockage of the HIF1A-p300/CBP interaction and represses transcriptional activity of HIF1A targeted genes.

HIF1A has a role as a master transcriptional monitor of the adaptive response to hypoxia. Under hypoxic conditions HIF1A activates the transcription of over 40 genes, including, erythropoietin, glucose transporters, glycolytic enzymes, vascular endothelial growth factor, and genes whose protein products increase oxygen release or facilitate metabolic adaptation to hypoxia. HIF1A functions as an essential role in embryonic vascularization, tumor angiogenesis and pathophysiology of ischemic disease.

HIF1A has a role as a master transcriptional monitor of the adaptive response to hypoxia. Under hypoxic conditions HIF1A activates the transcription of over 40 genes, including, erythropoietin, glucose transporters, glycolytic enzymes, vascular endothelial growth factor, and genes whose protein products increase oxygen release or facilitate metabolic adaptation to hypoxia. HIF1A functions as an essential role in embryonic vascularization, tumor angiogenesis and pathophysiology of ischemic disease.

Egl Nine Homolog 3 (EGLN3) belongs to the EGLN family of prolyl hydroxylases. EGLN3 catalyzes hydroxylation of the ? subunit of hypoxia-inducible factor-?, which targets hypoxia-inducible factor-? for ubiquitination by a ubiquitin ligase complex containing the von Hippel-Lindau (VHL) tumor suppressor. EGLN3 is the most significant isozyme in limiting physiological activation of HIFs (especially HIF2A) in hypoxia. EGLN3 is activated in cardiovascular cells and Hela cells after exposure to hypoxia. In addition, EGLN3 hydroxylates PKM2 in hypoxia, thus limiting glycolysis. Under normoxia, EGLN3 hydroxylates and regulates the stability of ADRB2. EGLN3 is inhibited by polynitrogen compounds possibly by chelation to Fe2+ ions.

Meteorin (METRN) is involved in both glial cell differentiation and axonal network formation during neurogenesis. METRN promotes astrocyte differentiation and transforms cerebellar astrocytes into radial glia. Moreover, the METRN protein stimulates axonal extension in small and intermediate neurons of sensory ganglia by activating nearby satellite glia.

The somatomedins, or insulin-like growth factors (IGFs), comprise a family of peptides that play important roles in mammalian growth and development. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed 'sulfation factor,' which later became known as 'somatomedin' (Daughaday et al., 1972). Three main somatomedins have been characterized: somatomedin C (IGF1), somatomedin A (IGF2; MIM 147470), and somatomedin B (MIM 193190) (Rotwein, 1986; Rosenfeld, 2003).

The cytokine Macrophage migration inhibitory factor (MIF) has been identified to be secreted by the pituitary gland and the monocyte/macrophage and to play an important role in endotoxic shock. MIF has the unique property of being released from macrophages and T cells in response to physiological concentrations of glucocorticoids. The secretion of MIF is tightly regulated and decreases at high, anti-inflammatory steroid concentration.

The cytokine Macrophage migration inhibitory factor (MIF) has been identified to be secreted by the pituitary gland and the monocyte/macrophage and to play an important role in endotoxic shock. MIF has the unique property of being released from macrophages and T cells in response to physiological concentrations of glucocorticoids. The secretion of MIF is tightly regulated and decreases at high, anti-inflammatory steroid concentration.

TGFB-Induced Factor Homeobox 2-Like, X-Linked (TGIF2LX) belongs to the TALE/TGIF homeobox family of transcription factors and takes part in spermatogenesis. A homolog of TGIF2LX is located in the male specific region of chromosome Y, in a block of sequence which is the outcome of a large X-to-Y transposition.

Hepatocyte Growth Factor (HGF) is a multifunctional growth factor which regulates both cell growth and cell motility. It exerts a strong mitogenic effect on hepatocytes and primary epithelial cells. HGF synergizes with Interleukin-3 and GM-CSF to stimulate colony formation of hematopoietic progenitor cells in vitro and may, therefore, also modulate hematopoiesis.

Nuclear Apoptosis Inducing Factor 1 (NAIF1) is a part of the NAIF1 family. NAIF1 Interacts with HARBI1 and Induces apoptosis.

Inositol oxygenase is a non-heme di-iron enzyme which oxidizes myo-inositol to glucuronic acid. In addition, inositol oxygenase oxidizes the less abundant chiro isomer of inositol. MIOX enzyme is a component of the only known pathway for the catabolism of inositol in humans. MIOX is expressed mostly in the kidneys. Reduction of Inositol Oxygenase and accumulation of polyols, such as inositol and xylitol, have been implicated as contributing factors in complications linked with diabetes.

IFNI30 inducible lysosomal thiol reductase (IFI30), is a part of the GILT family. IFI30 is a lysosomal thiol reductase which at low pH is capable of decreasing protein’s disulfide bonds. IFI30 is expressed constitutively in antigen-presenting cells and induced by gamma-IFN in other cell types. Also, IFI30 plays an important role in MHC class II-restricted antigen processing. IFI30 facilitates the generation of MHC class II-restricted epitopes from disulfide bond-containing antigen by the endocytic reduction of disulfide bonds and Also facilitates MHC class I-restricted recognition of exogenous antigens containing disulfide bonds by CD8+ T-cells or cross-presentation.

Intrinsic Factor is a member of the cobalamin transport protein family. It encodes a glycoprotein secreted by parietal cells of the gastric mucosa and is required for adequate absorption of vitamin B12 in the terminal ileum. Vitamin B12 is essential for erythrocyte maturation and mutations in the Intrinsic Factor may lead to congenital pernicious anemia. Upon entry into the stomach, vitamin B12 binds to one of two B12 binding proteins present in the gastric fluid. In the less acidic environment of the small intestine, these proteins dissociate from the vitamin, allowing it to bind to intrinsic factor and enter the portal circulation through a receptor in the ileal mucosa specific for the B12-intrinsic factor complex.

FGF8 is part of the fibroblast growth factor family. FGF family members have wide mitogenic and cell survival activities, and participate in a variety of biological processes, including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion. FGF8 supports androgen and anchorage independent growth of mammary tumor cells. FGF8 over expression increases tumor growth and angiogensis. The adult expression of FGF-8 gene is restricted to testes and ovaries. FGF8 functions as an embryonic epithelial factor. FGF8 takes part in midbrain and limb development, organogenesis, embryo gastrulation and left-right axis determination.

Granulocyte/Macrophage Colony-Stimulating Factors are cytokines that act in hematopoiesis by controlling the production, differentiation, and function of 2 related white cell populations of the blood, the granulocytes and the monocytes-macrophages. CSF-1 induces cells of the monocyte/macrophage lineage. It plays a role in immunological defenses, bone metabolism, lipoproteins clearance, fertility and pregnancy.

TGFB-Induced Factor Homeobox 2-Like Y-Linked (TGIF2LY) is a part of the TALE/TGIF homeobox family of transcription factors. TGIF2LY is located in the male specific region of chromosome Y, in a block of sequence which is the outcome of a large X-to-Y transposition. TGIF2LY act as a regulator of TGIF2LX due to the fact that the C-terminus of TGIF2LY is different from that of its chromosome X homolog (TGIF2LX). TGIF2LY has also a transcription role in testis.

ATPase inhibitory factor 1 (ATPIF1) attaches to the C-terminal region of a beta subunit of the F1-ATPase at low pH values and, through interference of the beta and gamma subunit interaction, ATPIF1 controls the activity of the F1 (the hydrophilic catalytic core), F0 (the membrane embedded protein channel) ATPase. ATPIF1 overexpression in a number of human carcinomas additionally reinforces its participation in oncogenesis and offers insight into the transformed metabolism of cancer cells, including the reprogramming of energy metabolism in relation to glycolysis. Endogenous F1F(o)-ATPase inhibitor curbing ATP depletion when the mitochondrial membrane potential drops below a threshold and the F1F(o)-ATP synthase begins hydrolyzing ATP to pump protons out of the mitochondrial matrix.

ICOS (inducible T-cell costimulatory) belongs to the CD28 family of immune-assisted stimulatory receptors. ICOS forms homodimers and takes a significant part in immune responses, cell-cell signaling, as well as regulation of cell proliferation. The interaction of B7-H2 / ICOS takes a vital role in T-cell differentiation, T-B cell interaction in addition to humoral immune response is essential for the formation of reproductive centers as well as the production of cytokine IL-4. Moreover, ICOS is more effective in inducing IL-10 production, a cytokine which is important for the inhibitory function of T regulatory cells. The ICOS-B7RP-1 and B7-1 / B7-2-CD28 / CTLA-4 pathways offer a significant second signal which can regulate the inhibition, activation and fine regulation of T-lymphocyte responses. ICOS stimulates the production of Th1 and Th2 cytokines, however it can also participate in the generation of Th2 cells.

TIGAR is a p53-inducible enzyme which catalyzes the hydrolysis of fructose-2-6 bisphosphate (F-2-6-BP) to fructose-6-phosphate and inorganic phosphate. F-2-6-BP is an influential activator of 6-phosphofructose-1 kinase (the rate limiting enzyme of glycolysis). By lowering the intracellular level of F-2-6-BP, TIGAR expression leads to increased glucose processing through the pentose phosphate pathway, the main cellular source for NADPH.

SDF-1 (stromal cell-derived factor-1) is small cytokine belonging to the chemokine family that is officially designated Chemokine (C-X-C motif) ligand 12 (CXCL12). It is produced in two forms, SDF-1a/CXCL12a and SDF-1b/CXCL12b, by alternate splicing of the same gene. Chemokines are characterized by the presence of four conserved cysteines, which form two disulfide bonds. The CXCL12 proteins belong to the group of CXC chemokines, whose initial pair of cysteines are separated by one intervening amino acid. CXCL12 is strongly chemotactic for lymphocytes and has been implicated as an important cell co-ordinator during development. During embryogenesis it directs the migration of hematopoietic cells from foetal liver to bone marrow. Mice which were knocked-out for CXCL12 gene were lethal before the birth or within just 1 hour of life. As another role, CXCL12a alters also the electrophysiology of neurons. CXCL12 was shown to be expressend in many tissues in mice (including brain, thymus, heart, lung, liver, kidney, spleen and bone marrow).
The receptor for this chemokine is CXCR4, which was previously called fusin. This CXCL12-CXCR4 interaction used to be considered exclusive (unlike for other chemokines and their receptors), but recently it was suggested that CXCL12 is also bound by CXCR7 receptor.
The gene for CXCL12 is located on human chromosome 10. In human and mouse both CXCL12 and CXCR4 show high identity of sequence: 99% and 90%, respectively.