UNIPROT:P02794 - FACTA Search

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Query: UNIPROT:P02794 (ferritin)
17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Considerable attention is directed to a surprising biologic phenomenon wherein tissues exposed to one insult acquire resistance to another. We identify a novel example of acquired resistance to acute renal failure and a mechanism that contributes to such resistance. Nephrotoxic serum, administered to rats 24 h before the induction of glycerol-induced acute renal failure, reduces functional and structural injury that occurs in this model. Since heme oxygenase, the rate-limiting enzyme in heme degradation, protects against heme protein-induced renal injury, we questioned whether induction of heme oxygenase underlies the protection afforded by nephrotoxic serum. Kidney heme oxygenase (HO-1) mRNA was induced 6 h after nephrotoxic serum and renal tubules were identified as the site of expression of heme oxygenase protein. Induction of heme oxygenase was accompanied by increased renal content of ferritin but not by induction of other antioxidant enzymes. Inhibition of heme oxygenase prevented the protection afforded by nephrotoxic serum. Nephrotoxic serum did not protect against ischemic acute renal failure, a model in which heme oxygenase is not induced. Thus, nephrotoxic serum protects against glycerol-induced acute renal failure by inducing heme oxygenase in tubules. This study provides the first demonstration of resistance to tubular injury acquired from glomerular inflammation, uncovers a mechanism for such resistance, and exposes the dialogue that occurs between glomeruli and tubules.
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PMID:Glomerular inflammation induces resistance to tubular injury in the rat. A novel form of acquired, heme oxygenase-dependent resistance to renal injury. 890 34

Treatment of rats with the cancer chemopreventive agent 1,2-dithiole-3-thione (D3T) resulted in a significant increase in hepatic heme oxygenase (HO) activity, which corresponded to increased protein levels of HO-1. Upon further analysis of proteins related to heme metabolism, the level of ferritin, the major iron storage protein in liver, was also found to be elevated. Diminished levels of intracellular free iron were monitored by EPR spectroscopy at times after administration of D3T that suggested that increased ferritin content sequesters intracellular iron. The increased levels of protein were associated with increased levels of steady-state RNA of HO-1 and the light (FL) and heavy (FH) subunits of ferritin. A direct relationship between enhanced rates of gene transcription and elevated levels of HO-1 and ferritin RNA was found. The inductions of FL and FH, but not HO-1, were sensitive to cycloheximide, suggesting that in vivo these genes are regulated by distinct D3T-responsive transcriptional mechanisms. The known protective roles for induced HO-1 and ferritin in cellular stress have been suggested to include increased levels of the antioxidant bilirubin and enhanced sequestration of intracellular iron into ferritin, which can effectively reduce iron-mediated reactive oxygen generation. Thus, protective actions of D3T against the cytotoxic and carcinogenic consequences of chemicals that exert electrophilic or oxidative stresses may be mediated, in part, by the induction of HO-1, FL and FH.
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PMID:Induction of hepatic heme oxygenase-1 and ferritin in rats by cancer chemopreventive dithiolethiones. 896 40

The mechanisms involved and the potentially useful therapeutic strategies in the prevention of acute renal failure (ARF) are briefly reviewed. Factors mentioned are the role of calcium channel blockers, the antioxidant agents, heme oxygenase induction, and ferritin synthesis; and of substances with hemodynamic actions in ARF; such as endothelin, atrial natriuretic peptide, urodilatin, PAF antagonist, prostaglandins, diuretics, and dopamine. The loss of tubular epithelium polarity, the mechanisms involved in this process, and the usefulness of arginine-glycine-aspartic acid peptide and anti-ICAM antibodies in the prevention of tubular obstruction are also reviewed.
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PMID:Therapeutic strategies in the prevention of acute renal failure. 910 98

Hemoglobin (Hb) induces heme oxygenase-1 (HO-1), which catalyzes the breakdown of heme to bilirubin, and ferritin. Rats pretreated with Hb have been shown to survive lethal doses of lipopolysaccharide (LPS; see L. Otterbein, S. L. Sylvester, and A. M. Choi. Am. J. Respir. Cell Mol. Biol. 13: 595-601, 1995). The physiological basis of this increased survival and the mechanism(s) involved in the protection against LPS by Hb are unknown. Here we investigated 1) the effects of Hb on the hemodynamic and biochemical parameters of LPS-induced tissue injury and 2) the mechanism(s) by which Hb conferred protection against shock and tissue injury. Hb-treated rats maintained normal mean arterial blood pressure, whereas control rats experienced cardiovascular collapse after a lethal dose of LPS. Hepatic and renal functions, peripheral white blood cells, serum lactate dehydrogenase, and phosphate also remained normal after LPS in Hb-treated rats. Hb also attenuated LPS-induced neutrophil alveolitis and tumor necrosis factor-alpha levels. Pretreatment with both desferoxamine, which, like ferritin, can bind iron, and with exogenous apoferritin failed to protect against LPS. In contrast, treatment with Hb plus desferoxamine, which induced HO-1 but not ferritin, did protect against LPS. Treatment with iron-dextran, which induced ferritin but not HO-1, did not protect against LPS. We conclude that Hb pretreatment reduces the inflammatory and physiological consequences of LPS and that the Hb-induced protection against LPS is dependent on HO-1 and not ferritin induction.
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PMID:Mechanism of hemoglobin-induced protection against endotoxemia in rats: a ferritin-independent pathway. 912 78

In the liver, CCl4 induces cell necrosis followed by regeneration. Cell injury is caused by free radical damage and may be due, at least in part, to oxidative stress and the subsequent formation of reactive oxygen intermediates (ROIs). In a rat model of acute CCl4-induced hepatic injury, we examined the expression of genes involved in cellular response to different kinds of stress, including oxidative stress (hsp 70 family, heme oxygenase), in free radical detoxification (Mn superoxide dismutase and Cu/ Zn superoxide dismutase), in iron homeostasis (H and L ferritin subunits) and in the cell cycle (c-fos, c-jun, histone H3). As an experimental approach, we first analysed the pattern of protein synthesised by liver slices in vitro. Then we studied the mechanisms regulating the expression of different genes, by analysing both mRNA steady state levels and transcription rates. Activation of the specific heat shock transcription factor (HSF) by CCl4 was also investigated. We observed that different members of the hsp70 family (hsp70, hsc73, grp78) are activated by different kinetics and are regulated mainly at the transcriptional level. Induction of the hsp70 gene occurs rapidly and transiently and is preceded by the activation of HSF DNA-binding activity. We demonstrated an increase in the steady-state levels of mRNAs for heme oxygenase, Mn and Cu/Zn superoxide dismutases and H and L ferritin subunits. However, different kinetics and regulatory mechanisms occurred with different genes. We showed that induction of c-fos and c-jun protooncogenes is the earliest event after CCl4 administration, whereas histone H3 expression peaked at 24-48 h. The results of this study are interpreted as evidence that activation of specific stress response genes is primarily related to the defence against the rapidly occurring cell damage, but may also be related to subsequent processes of tissue inflammation and cell proliferation.
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PMID:Gene expression in liver after toxic injury: analysis of heat shock response and oxidative stress-inducible genes. 929 88

We showed previously that treatment of cultured rabbit lens epithelial cells (LECs) with hyperbaric oxygen (HBO) produced DNA strand-breaks, caused reversible inhibition of protein synthesis and induced the synthesis of a 32 kD protein. In the present work, we employed immunostaining procedures to identify the 32 kD protein as heme oxygenase-1 (HO-1). Increased synthesis of the enzyme was observed as early as 12 hr after HBO-treatment, reached a maximum at 18 hr and was not detectable at 36 hr. Exposure of the cells to hemin also increased the synthesis of HO-1. An HBO-induced inhibition of protein synthesis and the subsequent induction of HO-1 was also observed in the capsule-epithelium of cultured rabbit lenses. For both LECs and the cultured lens, only HO-1 and not heme oxygenase-2 was HBO-inducible. Use of the antioxidant dimethylthiourea with HBO-treated lenses or LECs did not alter the observed effects on protein synthesis or the induction of HO-1. In contrast to results obtained with 50 atm O2, a pressure of 25 atm O2 inhibited protein synthesis only slightly and failed to induce synthesis of the 32 kD protein (although, as shown previously, identical exposure of LECs to 25 atm O2 significantly damaged DNA). Inhibition of protein synthesis in LECs and cultured lenses with the use of puromycin also induced synthesis of HO-1. Both hemin (10 micron), a source of iron, and 50 atm O2 produced a three-fold increase in the concentration of ferritin, a natural iron chelator, in LECs two days after exposure; no effects on ferritin levels were observed after 1 or 3 days. The finding that the increase in ferritin concentration occurred in the cells significantly after hemin- or HBO-induced synthesis of heme oxygenase indicates that chelatable iron rather than the heme molecule itself may have been the primary agent responsible for inducing ferritin synthesis. The data suggest that HBO-induced synthesis of HO-1 in the lens epithelium may be the result of an inhibition of protein synthesis, possibly leading to an accumulation of heme, rather than a direct protective response against oxidative stress.
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PMID:Heme oxygenase synthesis is induced in cultured lens epithelium by hyperbaric oxygen or puromycin. 929 80

Using primary human fibroblasts we have observed the existence of an acquired refractoriness of the heme oxygenase-1 gene to induction by a second dose of UVA (320-380 nm) radiation. We studied the kinetics of development of refractoriness over a time interval of up to 72 h between the first inducing event and the second (challenge) dose. Complete refractoriness was observed at 48 h. We also studied development of refractoriness after UVA, sodium arsenite and H2O2 treatment in all possible combinations and demonstrated that only UVA led to refractoriness. Ultraviolet radiation induced partial refractoriness to H2O2 induction but did not change the response to sodium arsenite. In an investigation of the mechanism of development of refractoriness we used the heme oxygenase inhibitor, tin-protoporphyrin IX and showed that induction of heme oxygenase enzymatic activity is a crucial step. However, the induction of ferritin, which is known to play a key role in protection against oxidative stress, did not appear to be involved. Damage to membranes is also probably not involved in the refractoriness mechanism. Because either hemin alone or UVA radiation are able to lead to a refractoriness of the heme oxygenase-1 gene to reinduction by a second exposure to one or the other agent in human fibroblasts, we conclude that heme, or an as yet unidentified heme derivative, is involved in the refractoriness response.
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PMID:Development of refractoriness of induced human heme oxygenase-1 gene expression to reinduction by UVA irradiation and hemin. 933 16

Toxicosis syndrome of fasting pregnant ewes has a close similarity to human preeclampsia (hypertension, albuminuria). The common etiological factor might be oxidative hemolysis and heme-induced endothelial damage. Ewes (5 starving, 5 control) at 130-135 gestational days with a 96-h fasting period followed by refeeding were used. Blood pressure, platelet count, electrolytes, kidney and liver function parameters, as well as plasma glucose, hemoglobin/heme, free thiol groups and Trolox equivalent antioxidant capacity, and plasma iron and ferritin levels were measured. Statistical significance was assessed using Student's t test (P < 0.05). Besides hypertension and renal disturbances, hemolysis, elevated liver enzymes and low platelet count, characteristic of human HELLP syndrome, were also present. In the first 24 h of glucose deprivation there was a significant rise in both the plasma hemoglobin/heme and indirect bilirubin concentrations. The antioxidant free thiol levels decreased significantly the next day, without any change in the total antioxidant capacity of the plasma. While the loss of calcium and magnesium levels related to the similarity to preeclampsia, reduced plasma iron concentrations referred to species differences in iron homeostasis. An oxidative stress causing hemolysis in a glucose-6-phosphate dehydrogenase-deficient animal model was proven by the loss of free thiols after glucose deprivation. The activation of the oxidative stress protein heme oxygenase was a signal of endothelial cell injury, the primary cause of pregnancy-induced hypertension.
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PMID:The pathogenetic role of heme in pregnancy-induced hypertension-like disease in ewes. 936 99

Heme oxygenase (HO) proteins are members of the HSP30 family and consist of 2 isozymes identified to date, termed HO-1 and HO-2. Separate genes encode the isozymes and protein products which are immunochemically distinct, share less than 50% similarity at the amino acid sequence level. Each form, however, shows greater than 90% similarity among species, including human and the rat (reviewed in ref.). Furthermore, these isozymes function in a well-defined role to carry out oxidation of the heme molecule (Fe-protoporphyrin IX) in concert with NADPH-cytochrome P450 reductase. The oxidation of heme is isomer specific and results in the formation of bile pigments, carbon monoxide, and iron. The heme molecule constitutes the prosthetic moiety of hemoproteins, such as hemoglobin, myoglobin, catalase, soluble guanylate cyclase, cytochrome b5, cytochromes P450 and NO synthase. HO-1 also known as heat shock protein (HSP) 32 is encoded by a gene which is exquisitely stress-responsive and a host of stimuli that mediate oxidative stress cause induction of the protein both in vivo and in vitro. The HO-2 form shows a unique pattern of regulation from that of HO-1. HO-2 is a constitutive protein and its expression is not affected by the inducers of HO-1 tested to date; rather, the only known regulator of HO-2 yet identified is adrenal glucocorticoids. The two isozymes display vast differences in tissue distribution and under normal conditions HO-1 is present in the whole brain at the limit of immunodetection and is discreetly localized in select neuronal populations. HO-1 protein (approximately 32 kDa) and its approximately 1.8 kb transcript are increased, however, in response to stressful stimuli primarily in non-neuronal cell populations. The heme oxygenase system serves in both a catabolic and anabolic capacity in the cell. In the former capacity, it down-regulates cellular heme and hemoprotein levels. And, as such it inactivates the most effective catalyst for formation of free radicals, the heme molecule. In its anabolic role, as noted above, heme oxygenase produces bile pigments, carbon monoxide, and iron, all of which are biologically active: bile pigments function as antioxidants; the carbon monoxide generated by HO activity has been correlated with the generation of cGMP; and iron regulates expression of various genes, including that of HO-1 itself, as well as transferrin receptors, ferritin, and NO synthase. We used rabbit anti-rat HO-2 polyclonal antibody and HO-2 cDNA to localize HO-2 immunoreactive protein and the 1.3- and 1.9 kb homologous transcripts, respectively, in rodent brain as visualized by histochemical staining procedures. These protocols provide the first detailed description of methodologies successfully used to define the pattern of HO-2 expression at the transcriptional and translational levels in the adult rat brain and glucocorticoid-treated newborn rats. The procedures described herein have the virtue of being non-radioactive, as well as applicability to the systemic organs, such as the cardiovascular system and the male reproductive organs. Visualization of cellular HO-2 expression aids in assessment of potential sites of carbon monoxide, iron, and bilirubin production within the nervous system.
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PMID:Histochemical localization of heme oxygenase-2 protein and mRNA expression in rat brain. 938 81

Oxidant stress plays a key role in hepatic fibrogenesis. This study was undertaken to assess whether, during iron overload-associated liver fibrosis in vivo, oxidant stress occurs in hepatic stellate cells (HSC) during active fibrogenesis. Gerbils were treated with iron-dextran, and, after hepatic fibrosis developed, livers were subjected to various combination of in situ hybridization and immunocytochemistry analyses. In iron-treated animals, no specific accumulation of ferritin protein was found in collagen mRNA-expressing cells. Moreover, the activity of the iron regulatory protein, the main sensor of cellular iron status, was unchanged in HSC from iron-treated animals. Although a significant amount of malondialdehyde-protein adducts was detected in gerbil liver during fibrogenesis, accumulation of these lipid peroxidation by-products was restricted to iron-laden cells adjacent to activated HSC. In cultured gerbil HSC, iron, aldehydes, and other pro-oxidants were able to enhance the expression of an oxidant stress-responsive gene, heme oxygenase (HO), with no change in collagen mRNA accumulation. In keeping with these findings, we found that, in vivo, activation of HO gene was present in iron-filled nonparenchymal cell aggregates, but absent in HSC. In conclusion, the data indicate that during iron overload-associated fibrogenesis, HSC are not directly subjected to oxidant stress, but are likely to be activated by paracrine signals arising in neighboring cells.
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PMID:Hepatic stellate cells are not subjected to oxidant stress during iron-induced fibrogenesis in rodents. 962 Mar 35

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