RNA synthesis by nuclei and nucleoli from ischemic liver cells

Schiaffonati, Luisa; Cairo, Gaetano; Bernelli‐Zazzera, Aldo

doi:10.1002/jcp.1040970324

Cited by 23 publications

(13 citation statements)

References 43 publications

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“…In fact, Teoh et al applied Isc for 90 min, hence seriously damaging the liver and probably causing extensive necrosis [48], resulting in turn in a regenerative response that may benefit from increased cyclin levels. In contrast, after 60 min of Isc, as applied in our experimental model, the damage to the liver is limited [8,49] and consequently, no regeneration ensues as demonstrated by the absence of changes in PCNA levels (this study) and thymidine incorporation [50].…”

Section: Discussionmentioning

confidence: 86%

RETRACTED ARTICLE: Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: Association with reduction of oxidative stress

Tacchini

Cairo

Ponti

et al. 2006

Free Radical Research

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Section: Discussionmentioning

confidence: 86%

RETRACTED ARTICLE: Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: Association with reduction of oxidative stress

Tacchini

Cairo

Ponti

et al. 2006

Free Radical Research

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“…The molecular basis underlying this constantly high expression of TfR depends on different events occurring during both ischemia and reperfusion. Binding of HIF-1 to the HRE in the promoter region of the TfR gene is induced by oxygen deprivation during ischemia, but, because of the impairment of the liver RNA synthesizing machinery during ischemia, 41 active synthesis of TfR mRNA occurs only after reestablishment of the blood supply. Given the instability of HIF-1 under aerobic conditions, 36 electrophoretic mobility shift assay did not show binding activity after reperfusion, but it seems possible to conceive that HIF-1 already engaged in transcription complexes remains stable and allows elongation of TfR transcripts initiated during ischemia at early times of reperfusion.…”

Section: Discussionmentioning

confidence: 99%

Transferrin receptor gene expression and transferrin-bound iron uptake are increased during postischemic rat liver reperfusion

et al. 2002

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Iron-catalyzed production of reactive oxygen species is a cause of liver injury after ischemia/ reperfusion (I/R). The aim of the present study was to address the regulation of transferrin receptor (TfR), which mediates cellular iron uptake, during I/R. The molecular mechanisms controlling TfR gene expression in vivo during I/R of rat liver were investigated by molecular biology procedures. We also analyzed transferrin-bound iron uptake into surviving liver slices. Increased amounts of TfR protein and messenger RNA (mRNA) were found 2 to 6 hours after reestablishment of blood supply. RNA bandshift analysis showed that iron regulatory protein (IRP) activity was decreased in the first hours of reperfusion, thus indicating that IRP-mediated mRNA stabilization was not involved in early TfR upregulation. On the contrary, increased transcription of the TfR gene in isolated nuclei was observed during reperfusion; during the ischemic phase this was preceded by enhanced binding of hypoxia inducible factor (HIF-1) to a DNA sequence derived from the TfR promoter. TfR2 mRNA levels were also enhanced after reperfusion. The increased expression of TfR at the cell surface resulted in increased uptake of transferrin-bound-iron into surviving liver slices; however, iron was not incorporated into ferritin. T he cell has to constantly face the difficult task of balancing the need for iron with the toxicity of this metal. The maintenance of intracellular iron homeostasis depends on the balanced expression of ferritin, which stores iron in a soluble nontoxic form, and transferrin receptor (TfR), which mediates iron uptake. 1,2 The tight reciprocal regulation of these 2 proteins ensures that the levels of the metal are adequate for cellular iron needs but remain below the threshold required to become a source of toxic reactive oxygen species (ROS). Ferritin and TfR expression is controlled at multiple levels, 1,2 but intracellular iron homeostasis is mainly regulated by means of post-transcriptional mechanisms. 3,4 In fact, in addition to individual transcriptional controls, 1,2 the genes for ferritin and TfR share a common regulatory pathway mediated by iron regulatory proteins (IRP-1 and IRP-2). When iron inside the cell is scarce, iron regulatory elements (IRE) in ferritin and TfR messenger RNAs (mRNAs) are bound by iron regulatory proteins (IRP-1 and 2), which block their translation and degradation, respectively (see reviews [3][4][5][6][7][8][9] ). This determines a simultaneous increase in iron uptake and decrease in iron sequestration that results in the formation of a pool of free iron available for metabolic use. Conversely, when iron is abundant, IRP-1 assembles a 4Fe-4S cluster, loses its RNA-binding activity and acquires enzymatic activity as a cytoplasmic aconitase, whereas IRP-2 is degraded via the ubiquitin-proteasome pathway. Under the latter condi-

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“…synthesis of DNA and RNA [17,25] and ribosomal structure and function [9], It remains to be determined by which mechanism(s) protein synthesis is re duced following the different experimental procedures described in the present study.…”

Section: Discussionmentioning

confidence: 99%

Changes of Protein Synthesis in Liver Tissue following Ligation of Hepatic Artery or Portal Vein in Rats

J¹,

Seeman²,

Hasselgren³

1985

Eur Surg Res

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The effects of short-term (1 h) complete liver ischemia, hepatic artery ligation (HAL) and portal vein ligation (PVL) on protein synthesis and ATP in liver tissue were studied in rats. Protein synthesis was measured by determining rate of amino acid incorporation into protein in incubated liver slices and was reduced to 34% of the control value after 1 h of complete liver ischemia. ATP was reduced from 3.2 to 0.28 µmol × g-¹ wet weight. Following HAL for 1 h, protein synthesis was reduced to 63% of control value and ATP to 2.4 µmol × g-¹ wet weight. No significant changes of protein synthesis or ATP were noticed 1 h after PVL. The results indicate that deprivation of hepatic arterial blood plays a greater role than exclusion of portal blood for impairment of protein synthesis in short-lasting liver ischemia. The effect of complete ischemia was more pronounced than the sum effect of HAL and PVL, suggesting that accumulation of metabolites and tissue acidosis might contribute to the consequences of abolished blood supply in liver ischemia. In another series of experiments the effects of HAL and PVL on protein synthesis and ATP in liver tissue were studied after 1, 3 and 7 days. Protein synthesis was reduced 1 day after HAL but normalized after 3 days, probably reflecting development of collaterals. Following PVL, protein synthesis was reduced after 1 day and remained depressed up to 7 days at which time it was 55% of the control value. ATP in liver tissue was not significantly different from the control value 1 day after HAL of PVL but was slightly reduced 7 days after PVL. Thus, the results demonstrated that hepatic protein synthesis was rapidly reduced after HAL but returned to normal after a few days. The effects of PVL developed more slowly but were more pronounced and protracted. The effects of HAL are probably caused by hypoxia while reduced protein synthesis following PVL might reflect decreased inflow to the liver of other factors of importance for protein synthesis than oxygen, e.g., amino acids and hormones.

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RNA synthesis by nuclei and nucleoli from ischemic liver cells

Cited by 23 publications

References 43 publications

RETRACTED ARTICLE: Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: Association with reduction of oxidative stress

RETRACTED ARTICLE: Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: Association with reduction of oxidative stress

Transferrin receptor gene expression and transferrin-bound iron uptake are increased during postischemic rat liver reperfusion

Changes of Protein Synthesis in Liver Tissue following Ligation of Hepatic Artery or Portal Vein in Rats

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