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  • 1
    Online Resource
    Online Resource
    Effects of Mitochondrial Ferritin Expression on Tumor Iron Metabolism and Tumor Growth in Nude Mice Xenografts.
    American Society of Hematology ; 2005
    In:  Blood Vol. 106, No. 11 ( 2005-11-16), p. 3582-3582
    Details
    In: Blood, American Society of Hematology, Vol. 106, No. 11 ( 2005-11-16), p. 3582-3582
    Abstract: Mitochondrial ferritin (MtFt) is a mitochondrial iron storage protein, whose function and regulation is largely unknown. Our previous results have shown that MtFt markedly affects intracellular iron distribution and homeostasis in mammalian cells (Blood105: 2161–2167, 2005). Using tumor xenografts, we examined the effects of expression MtFt on tumor iron metabolism and growth. H1299 parental or MtFt overexpressing cells were implanted into nude mice. As compared to control tumor xenografts, the expression of MtFt dramatically reduced the implanted tumor growth. A cytosolic iron starvation phenotype in MtFt expressing tumors was revealed by increased RNA-binding activity of iron regulatory proteins (IRPs) and, concomitantly, both an increase in transferrin receptor levels and a decrease in cytosolic ferritin. MtFt overexpression also led to a decrease in both total cellular heme content and heme oxygenase-1 levels. In addition, the expression of MtFt in tumors was associated with a decrease in aconitase activity and lower frataxin protein levels. Mitochondrial iron deposition in MtFt expressing tumors was directly observed by transmission electron microscopy. The pattern of iron accumulation in MtFt overexpressing tumor cells is remarkably similar to that observed in the mitochondria of sideroblastic anemia patients. In conclusion, our study shows that MtFt expression significantly affected tumor iron homeostasis by shunting iron into mitochondria; iron scarcity resulted in partial defects in heme and iron-sulfur cluster syntheses. It is likely that deprivation of iron in the cytosol is the cause of the significant inhibition of xenograft tumor growth.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V106.11.3582.3582
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2005
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 2
    Online Resource
    Online Resource
    TfR2 links iron metabolism and erythropoiesis
    American Society of Hematology ; 2015
    In:  Blood Vol. 125, No. 7 ( 2015-02-12), p. 1055-1056
    Details
    In: Blood, American Society of Hematology, Vol. 125, No. 7 ( 2015-02-12), p. 1055-1056
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2014-12-617571
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 3
    Online Resource
    Online Resource
    IRP1 regulates erythropoiesis and systemic iron homeostasis by controlling HIF2α mRNA translation
    American Society of Hematology ; 2013
    In:  Blood Vol. 122, No. 9 ( 2013-08-29), p. 1658-1668
    Details
    In: Blood, American Society of Hematology, Vol. 122, No. 9 ( 2013-08-29), p. 1658-1668
    Abstract: IRP1 controls HIF2α mRNA translation in vivo and thereby acts as an upstream regulator of Epo expression. IRP1 deficiency leads to age-dependent erythropoietic abnormalities and misregulation of body iron metabolism via the HIF2α/Epo pathway.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2013-03-492454
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2013
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 4
    Online Resource
    Online Resource
    eIF2α Kinase PKR Modulates the Hypoxic Response by Stat3-Dependent Transcriptional Suppression of HIF-1α
    American Association for Cancer Research (AACR) ; 2010
    In:  Cancer Research Vol. 70, No. 20 ( 2010-10-15), p. 7820-7829
    Details
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 70, No. 20 ( 2010-10-15), p. 7820-7829
    Abstract: Hypoxia within the tumor microenvironment promotes angiogenesis, metabolic reprogramming, and tumor progression. In addition to activating hypoxia-inducible factor-1α (HIF-1α), cells also respond to hypoxia by globally inhibiting protein synthesis via serine 51 phosphorylation of translation eukaryotic initiation factor 2α (eIF2α). In this study, we investigated potential roles for stress-activated eIF2α kinases in regulation of HIF-1α. Our investigations revealed that the double-stranded RNA–dependent protein kinase R (PKR) plays a significant role in suppressing HIF-1α expression, acting specifically at the level of transcription. HIF-1α transcriptional repression by PKR was sufficient to impair the hypoxia-induced accumulation of HIF-1α and transcriptional induction of HIF-1α–dependent target genes. Inhibition of HIF-1A transcription by PKR was independent of eIF2α phosphorylation but dependent on inhibition of the signal transducer and activator of transcription 3 (Stat3). Furthermore, HIF-1A repression required the T-cell protein tyrosine phosphatase, which acts downstream of PKR, to suppress Stat3. Our findings reveal a novel tumor suppressor function for PKR, which inhibits HIF-1α expression through Stat3 but is independent of eIF2α phosphorylation. Cancer Res; 70(20); 7820–9. ©2010 AACR.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    URL: Article
    DOI: 10.1158/0008-5472.CAN-10-0215
    RVK:
    XA 36000
    RVK:
    XA 10000
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2010
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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  • 5
    Online Resource
    Online Resource
    Liver sinusoidal endothelial cells induce BMP6 expression in response to non–transferrin-bound iron
    American Society of Hematology ; 2023
    In:  Blood Vol. 141, No. 3 ( 2023-01-19), p. 271-284
    Details
    In: Blood, American Society of Hematology, Vol. 141, No. 3 ( 2023-01-19), p. 271-284
    Abstract: Homeostatic adaptation to systemic iron overload involves transcriptional induction of bone morphogenetic protein 6 (BMP6) in liver sinusoidal endothelial cells (LSECs). BMP6 is then secreted to activate signaling of the iron hormone hepcidin (HAMP) in neighboring hepatocytes. To explore the mechanism of iron sensing by LSECs, we generated TfrcTek-Cre mice with endothelial cell–specific ablation of transferrin receptor 1 (Tfr1). We also used control Tfrcfl/fl mice to characterize the LSEC-specific molecular responses to iron using single-cell transcriptomics. TfrcTek-Cre animals tended to have modestly increased liver iron content (LIC) compared with Tfrcfl/fl controls but expressed physiological Bmp6 and Hamp messenger RNA (mRNA). Despite a transient inability to upregulate Bmp6, they eventually respond to iron challenges with Bmp6 and Hamp induction, yet occasionally to levels slightly lower relative to LIC. High dietary iron intake triggered the accumulation of serum nontransferrin bound iron (NTBI), which significantly correlated with liver Bmp6 and Hamp mRNA levels and elicited more profound alterations in the LSEC transcriptome than holo-transferrin injection. This culminated in the robust induction of Bmp6 and other nuclear factor erythroid 2–related factor 2 (Nrf2) target genes, as well as Myc target genes involved in ribosomal biogenesis and protein synthesis. LSECs and midzonal hepatocytes were the most responsive liver cells to iron challenges and exhibited the highest expression of Bmp6 and Hamp mRNAs, respectively. Our data suggest that during systemic iron overload, LSECs internalize NTBI, which promotes oxidative stress and thereby transcriptionally induces Bmp6 via Nrf2. Tfr1 appears to contribute to iron sensing by LSECs, mostly under low iron conditions.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.2022016987
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2023
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 6
    Online Resource
    Online Resource
    Transferrin receptor 1 controls systemic iron homeostasis by fine-tuning hepcidin expression to hepatocellular iron load
    American Society of Hematology ; 2019
    In:  Blood Vol. 133, No. 4 ( 2019-01-24), p. 344-355
    Details
    In: Blood, American Society of Hematology, Vol. 133, No. 4 ( 2019-01-24), p. 344-355
    Abstract: Transferrin receptor 1 (Tfr1) mediates uptake of circulating transferrin-bound iron to developing erythroid cells and other cell types. Its critical physiological function is highlighted by the embryonic lethal phenotype of Tfr1-knockout (Tfrc−/−) mice and the pathologies of several tissue-specific knockouts. We generated TfrcAlb-Cre mice bearing hepatocyte-specific ablation of Tfr1 to explore implications in hepatocellular and systemic iron homeostasis. TfrcAlb-Cre mice are viable and do not display any apparent liver pathology. Nevertheless, their liver iron content (LIC) is lower compared with that of control Tfrcfl/fl littermates as a result of the reduced capacity of Tfr1-deficient hepatocytes to internalize iron from transferrin. Even though liver Hamp messenger RNA (mRNA) and serum hepcidin levels do not differ between TfrcAlb-Cre and Tfrcfl/fl mice, Hamp/LIC and hepcidin/LIC ratios are significantly higher in the former. Importantly, this is accompanied by modest hypoferremia and microcytosis, and it predisposes TfrcAlb-Cre mice to iron-deficiency anemia. TfrcAlb-Cre mice appropriately regulate Hamp expression following dietary iron manipulations or holo-transferrin injection. Holo-transferrin also triggers proper induction of Hamp mRNA, ferritin, and Tfr2 in primary TfrcAlb-Cre hepatocytes. We further show that these cells can acquire 59Fe from 59Fe-transferrin, presumably via Tfr2. We conclude that Tfr1 is redundant for basal hepatocellular iron supply but essential for fine-tuning hepcidin responses according to the iron load of hepatocytes. Our data are consistent with an inhibitory function of Tfr1 on iron signaling to hepcidin via its interaction with Hfe. Moreover, they highlight hepatocellular Tfr1 as a link between cellular and systemic iron-regulatory pathways.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2018-05-850404
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2019
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 7
    Online Resource
    Online Resource
    Hepcidin-mediated hypoferremic response to acute inflammation requires a threshold of Bmp6/Hjv/Smad signaling
    American Society of Hematology ; 2018
    In:  Blood Vol. 132, No. 17 ( 2018-10-25), p. 1829-1841
    Details
    In: Blood, American Society of Hematology, Vol. 132, No. 17 ( 2018-10-25), p. 1829-1841
    Abstract: Systemic iron balance is controlled by hepcidin, a liver hormone that limits iron efflux to the bloodstream by promoting degradation of the iron exporter ferroportin in target cells. Iron-dependent hepcidin induction requires hemojuvelin (HJV), a bone morphogenetic protein (BMP) coreceptor that is disrupted in juvenile hemochromatosis, causing dramatic hepcidin deficiency and tissue iron overload. Hjv−/− mice recapitulate phenotypic hallmarks of hemochromatosis but exhibit blunted hepcidin induction following lipopolysaccharide (LPS) administration. We show that Hjv−/− mice fail to mount an appropriate hypoferremic response to acute inflammation caused by LPS, the lipopeptide FSL1, or Escherichia coli infection because residual hepcidin does not suffice to drastically decrease macrophage ferroportin levels. Hfe−/− mice, a model of milder hemochromatosis, exhibit almost wild-type inflammatory hepcidin expression and associated effects, whereas double Hjv−/−Hfe−/− mice phenocopy single Hjv−/− counterparts. In primary murine hepatocytes, Hjv deficiency does not affect interleukin-6 (IL-6)/Stat, and only slightly inhibits BMP2/Smad signaling to hepcidin; however, it severely impairs BMP6/Smad signaling and thereby abolishes synergism with the IL-6/Stat pathway. Inflammatory induction of hepcidin is suppressed in iron-deficient wild-type mice and recovers after the animals are provided overnight access to an iron-rich diet. We conclude that Hjv is required for inflammatory induction of hepcidin and controls the acute hypoferremic response by maintaining a threshold of Bmp6/Smad signaling. Our data highlight Hjv as a potential pharmacological target against anemia of inflammation.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2018-03-841197
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2018
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 8
    Online Resource
    Online Resource
    Increased serum fibroblast growth factor 23 predicts mortality in people with HIV/HCV coinfection
    Ovid Technologies (Wolters Kluwer Health) ; 2023
    In:  JAIDS Journal of Acquired Immune Deficiency Syndromes Vol. Publish Ahead of Print ( 2023-06-27)
    Details
    In: JAIDS Journal of Acquired Immune Deficiency Syndromes, Ovid Technologies (Wolters Kluwer Health), Vol. Publish Ahead of Print ( 2023-06-27)
    Type of Medium: Online Resource
    ISSN: 1525-4135
    URL: Article
    DOI: 10.1097/QAI.0000000000003245
    RVK:
    XA 10000
    RVK:
    XA 51942
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2023
    detail.hit.zdb_id: 2038673-4
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  • 9
    Online Resource
    Online Resource
    Macrophage checkpoint for iron absorption
    American Society of Hematology ; 2023
    In:  Blood Vol. 141, No. 23 ( 2023-06-08), p. 2791-2793
    Details
    In: Blood, American Society of Hematology, Vol. 141, No. 23 ( 2023-06-08), p. 2791-2793
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.2023020167
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2023
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 10
    Online Resource
    Online Resource
    In vivo tumor growth is inhibited by cytosolic iron deprivation caused by the expression of mitochondrial ferritin
    American Society of Hematology ; 2006
    In:  Blood Vol. 108, No. 7 ( 2006-10-01), p. 2428-2434
    Details
    In: Blood, American Society of Hematology, Vol. 108, No. 7 ( 2006-10-01), p. 2428-2434
    Abstract: Mitochondrial ferritin (MtFt) is a mitochondrial iron-storage protein whose function and regulation is largely unknown. Our previous results have shown that MtFt overexpression markedly affects intracellular iron homeostasis in mammalian cells. Using tumor xenografts, we examined the effects of MtFt overexpression on tumor iron metabolism and growth. The expression of MtFt dramatically reduced implanted tumor growth in nude mice. Mitochondrial iron deposition in MtFt-expressing tumors was directly observed by transmission electron microscopy. A cytosolic iron starvation phenotype in MtFt-expressing tumors was revealed by increased RNA-binding activity of iron regulatory proteins, and concomitantly both an increase in transferrin receptor levels and a decrease in cytosolic ferritin. MtFt overexpression also led to decreases in total cellular heme content and heme oxygenase-1 levels. In addition, elevated MtFt in tumors was also associated with a decrease in total aconitase activity and lower frataxin protein level. In conclusion, our study shows that high MtFt levels can significantly affect tumor iron homeostasis by shunting iron into mitochondria; iron scarcity resulted in partially deficient heme and iron-sulfur cluster synthesis. It is likely that deprivation of iron in the cytosol is the cause for the significant inhibition of xenograft tumor growth.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2006-04-018341
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2006
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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