Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43146 (tumour suppressor)
 5,935 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Regulation of the growth and metabolism of large organisms is tightly constrained by the need for precise oxygen homeostasis. Work on control of the haematopoietic growth factor erythropoietin has led to the recognition of a widespread transcriptional response to hypoxia which provides insights into how this is achieved. The central mediator of this response is a DNA binding complex termed hypoxia inducible factor 1 (HIF-1), which plays a key role in the regulation by oxygen of a large and rapidly growing panel of genes. In cancer, activity of the HIF system is up-regulated both by microenvironmental hypoxia and by genetic changes. The clearest example of genetic activation is seen in the hereditary cancer syndrome von Hippel-Lindau (VHL) disease. In normal cells the product of the VHL tumour suppressor gene targets the regulatory HIF subunits (HIF-1alpha and HIF-2alpha) for oxygen-dependent proteolysis, acting as the substrate recognition component of an E3 ubiquitin ligase. In pVHL defective cells this process is blocked leading to constitutive up-regulation of HIF-1alpha subunits, activation of the HIF complex and overexpression of HIF target genes. Using gene array screens we have defined a large number of VHL-regulated genes. The majority of these show hypoxia-inducible responses, supporting the central involvement of pVHL in gene regulation by oxygen. In addition to known HIF target genes involved in angiogenesis, glucose metabolism and vasomotor control, these new targets include examples with functions in matrix metabolism, apoptosis, carbon dioxide metabolism and secondary cascades of transcriptional control. Thus activation of HIF provides insights into the classical metabolic alterations in cancer cells, and into the mechanisms by which microenvironmental hypoxia might influence tumour behaviour. In the case of VHL disease, this activation can be linked to mutations in a defined tumour suppressor gene. Equally regulation of the HIF-1alpha/pVHL interaction in normal cells should provide insights into the physiological mechanisms operating in cellular oxygen sensing.
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PMID:The HIF pathway: implications for patterns of gene expression in cancer. 1172 31

HIFalpha prolyl hydroxylases (PHDs) are a family of enzymes that regulate protein levels of the alpha subunit of the hypoxia inducible transcription factor (HIF) under different oxygen levels. PHDs catalyse the conversion of a prolyl residue, molecular oxygen and alpha-ketoglutarate to hydroxy-prolyl, carbon dioxide and succinate in a reaction dependent on ferrous iron and ascorbate as cofactors. Recently it was shown that pseudo-hypoxia, HIF induction under normoxic conditions, is an important feature of tumours generated as a consequence of inactivation of the mitochondrial tumour suppressor 'succinate dehydrogenase' (SDH). Two models have been proposed to describe the link between SDH inhibition and HIF activation. Both models suggest that a mitochondrial-generated signal leads to the inhibition of PHDs in the cytosol, however, the models differ in the nature of the proposed messenger. The first model postulates that mitochondrial-generated hydrogen peroxide mediates signal transduction while the second model implicates succinate as the molecular messenger which leaves the mitochondrion and inhibits PHDs in the cytosol. Here we show that pseudo-hypoxia can be observed in SDH-suppressed cells in the absence of oxidative stress and in the presence of effective antioxidant treatment.
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PMID:Redox stress is not essential for the pseudo-hypoxic phenotype of succinate dehydrogenase deficient cells. 1679 80

Carbon monoxide (CO) can exert potent anti-inflammatory effects in animal and cell culture models of sepsis, despite well-known lethal effects at high concentration. Endogenous biological CO arises from the enzymatic degradation of haem, mainly from haemoglobin turnover, catalysed by haem oxygenases (HO). The inducible form of HO, haem oxygenase 1 (HO-1) participates in endogenous cellular defence against oxidative stress. HO-1 confers cytoprotection in many models of organ and tissue injury where inflammatory processes are implicated, including sepsis. When applied exogenously at low concentration, CO mimics the cytoprotective potential of HO-1 induction in these models. CO confers protection against endotoxin shock in vitro and in vivo by inhibiting the production of pro-inflammatory cytokines, in a mechanism involving the modulation of p38 mitogen activated protein kinase. CO protection against vascular injury may involve both anti-inflammatory and antiproliferative effects. The protection afforded by CO against liver failure and inflammatory lung injury was associated with the modulation of inducible nitric oxide synthase. Recent in vitro studies indicate that CO inhibits proinflammatory signalling by differentially inhibiting the trafficking of toll-like receptors (TLRs) to lipid rafts. Additional candidate mechanisms in anti-inflammatory effects of CO include the increased expression of heat shock proteins and the tumour suppressor protein caveolin 1.
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PMID:Cytoprotective and anti-inflammatory actions of carbon monoxide in organ injury and sepsis models. 1738 Jul 94