scholarly journals Regulation of ferritin H-chain expression in differentiating Friend leukemia cells

Blood ◽  
1995 ◽  
Vol 86 (4) ◽  
pp. 1570-1579 ◽  
Author(s):  
EM Coccia ◽  
E Stellacci ◽  
R Orsatti ◽  
U Testa ◽  
A Battistini
Keyword(s):  
Translational Control ◽  
Translational Regulation ◽  
State Level ◽  
Cell Types ◽  
Coding Region ◽  
Iron Storage ◽  
Human Ferritin ◽  
Responsive Element ◽  
Differentiation Inducers ◽  
Ferritin H

The mechanisms that regulate the expression of ferritin, the iron storage protein, have been investigated in Friend erythroleukemia cells (FLCs) induced to differentiate by several chemical compounds. In differentiating FLCs, administration of hemin increases the steady- state level of ferritin mRNA about 15-fold and the ferritin content about 20- to 25-fold. Conversely, iron salts have only mild stimulatory effects on these parameters and iron chelators only slightly inhibited the stimulatory effect of hemin. Transient transfection experiments with a construct in which the human ferritin H-chain promoter drives the expression of the indicator chloramphenicol acetyltransferase (CAT) gene show that the increase in mRNA content is mainly due to enhanced transcription. In addition to transcriptional effects, translational regulation resulting in the further increase in ferritin synthesis is shown by CAT assays from cells transiently transfected with a construct containing the coding region for the indicator CAT mRNA under the translational control of the mRNA ferritin iron-responsive element. We conclude that, in FLCs induced to differentiate, hemin acts synergistically with the differentiation inducers, increasing ferritin expression. Both transcriptional and translational mechanisms are responsible for this synergistic effect, which appears to be characteristic of differentiated erythroid cells because it is not observed in other cell types (ie, fibroblastic cell lines).

scholarly journals Cryo-EM structures and functional characterization of homo- and heteropolymers of human ferritin variants

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jose Irimia-Dominguez ◽  
Chen Sun ◽  
Kunpeng Li ◽  
Barry B. Muhoberac ◽  
Grace I. Hallinan ◽  
...  
Keyword(s):  
Iron Homeostasis ◽  
Functional Characterization ◽  
Protein Solubility ◽  
Cell Types ◽  
Brain Iron ◽  
Iron Storage ◽  
Human Ferritin ◽  
And Function ◽  
Brain Iron Metabolism

AbstractThe role of abnormal brain iron metabolism in neurodegenerative diseases is still insufficiently understood. Here, we investigate the molecular basis of the neurodegenerative disease hereditary ferritinopathy (HF), in which dysregulation of brain iron homeostasis is the primary cause of neurodegeneration. We mutagenized ferritin’s three-fold pores (3FPs), i.e. the main entry route for iron, to investigate ferritin’s iron management when iron must traverse the protein shell through the disrupted four-fold pores (4FPs) generated by mutations in the ferritin light chain (FtL) gene in HF. We assessed the structure and properties of ferritins using cryo-electron microscopy and a range of functional analyses in vitro. Loss of 3FP function did not alter ferritin structure but led to a decrease in protein solubility and iron storage. Abnormal 4FPs acted as alternate routes for iron entry and exit in the absence of functional 3FPs, further reducing ferritin iron-storage capacity. Importantly, even a small number of MtFtL subunits significantly compromises ferritin solubility and function, providing a rationale for the presence of ferritin aggregates in cell types expressing different levels of FtLs in patients with HF. These findings led us to discuss whether modifying pores could be used as a pharmacological target in HF.

Modulation of ferritin H-chain expression in Friend erythroleukemia cells: transcriptional and translational regulation by hemin

1992 ◽  
Vol 12 (7) ◽  
pp. 3015-3022
Author(s):  
E M Coccia ◽  
V Profita ◽  
G Fiorucci ◽  
G Romeo ◽  
E Affabris ◽  
...  
Keyword(s):  
Translational Regulation ◽  
Protoporphyrin Ix ◽  
Mrna Translation ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Iron Storage ◽  
Erythroleukemia Cells ◽  
Mrna Content ◽  
Friend Erythroleukemia Cells ◽  
Ferritin H

The mechanisms that regulate the expression of the H chain of the iron storage protein ferritin in Friend erythroleukemia cells (FLCs) after exposure to hemin (ferric protoporphyrin IX), protoporphyrin IX, and ferric ammonium citrate (FAC) have been investigated. Administration of hemin increases the steady-state level of ferritin mRNA about 10-fold and that of ferritin protein expression 20-fold. Experiments with the transcriptional inhibitor actinomycin D and transfection studies demonstrate that the increment in cytoplasmic mRNA content results from enhanced transcription of the ferritin H-chain gene and cannot be attributed to stabilization of preexisting mRNAs. In addition to transcriptional effects, translational regulation induces the recruitment of stored mRNAs into functional polyribosomes after hemin and FAC administration, resulting in a further increase in ferritin synthesis. Administration of protoporphyrin IX to FLCs produces divergent transcriptional and translational effects. It increases transcription but appears to suppress ferritin mRNA translation. FAC treatment increases the mRNA content slightly (about twofold), and the ferritin levels rise about fivefold over the control values. We conclude that in FLCs, hemin induces ferritin H-chain biosynthesis by multiple mechanisms: a transcriptional mechanism exerted also by protoporphyrin IX and a translational one, not displayed by protoporphyrin IX but shared with FAC.

scholarly journals Hemin-Mediated Regulation of an Antioxidant-Responsive Element of the Human Ferritin H Gene and Role of Ref-1 during Erythroid Differentiation of K562 Cells

2006 ◽  
Vol 26 (7) ◽  
pp. 2845-2856 ◽  
Author(s):  
Kenta Iwasaki ◽  
Elizabeth L. MacKenzie ◽  
Kiros Hailemariam ◽  
Kensuke Sakamoto ◽  
Yoshiaki Tsuji
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
K562 Cells ◽  
Erythroid Differentiation ◽  
Luciferase Reporter ◽  
H Gene ◽  
Human Ferritin ◽  
Responsive Element ◽  
Ferritin H ◽  
Antioxidant Responsive Element

ABSTRACT An effective utilization of intracellular iron is a prerequisite for erythroid differentiation and hemoglobinization. Ferritin, consisting of 24 subunits of H and L, plays a crucial role in iron homeostasis. Here, we have found that the H subunit of the ferritin gene is activated at the transcriptional level during hemin-induced differentiation of K562 human erythroleukemic cells. Transfection of various 5′ regions of the human ferritin H gene fused to a luciferase reporter into K562 cells demonstrated that hemin activates ferritin H transcription through an antioxidant-responsive element (ARE) that is responsible for induction of a battery of phase II detoxification genes by oxidative stress. Gel retardation and chromatin immunoprecipitation assays demonstrated that hemin induced binding of cJun, JunD, FosB, and Nrf2 b-zip transcription factors to AP1 motifs of the ferritin H ARE, despite no significant change in expression levels or nuclear localization of these transcription factors. A Gal4-luciferase reporter assay did not show activation of these b-zip transcription factors after hemin treatment; however, redox factor 1 (Ref-1), which increases DNA binding of Jun/Fos family members via reduction of a conserved cysteine in their DNA binding domains, showed induced nuclear translocation after hemin treatment in K562 cells. Consistently, Ref-1 enhanced Nrf2 binding to the ARE and ferritin H transcription. Hemin also activated ARE sequences of other phase II genes, such as GSTpi and NQO1. Collectively, these results suggest that hemin activates the transcription of the ferritin H gene during K562 erythroid differentiation by Ref-1-mediated activation of these b-zip transcription factors to the ARE.

scholarly journals Novel Translational Control through an Iron-Responsive Element by Interaction of Multifunctional Protein YB-1 and IRP2

2002 ◽  
Vol 22 (18) ◽  
pp. 6375-6383 ◽  
Author(s):  
Megumi Ashizuka ◽  
Takao Fukuda ◽  
Takanori Nakamura ◽  
Kanemitsu Shirasuna ◽  
Kazuhiro Iwai ◽  
...  
Keyword(s):  
Translational Control ◽  
Ribosomal Proteins ◽  
Translational Regulation ◽  
Regulatory Protein ◽  
Direct Interaction ◽  
In Vitro Translation ◽  
High Concentration ◽  
Iron Responsive Element ◽  
Responsive Element

ABSTRACT The eukaryotic Y-box-binding protein YB-1 functions in various biological processes, including DNA repair, cell proliferation, and transcriptional and translational controls. To gain further insight into how human YB-1 plays its role in pleiotropic functions, we here used two-hybrid screenings to identify partners of this protein; the results showed that YB-1 itself, iron-regulatory protein 2 (IRP2), and five ribosomal proteins each served as partners to YB-1. We then examined the biological effect of the interaction of YB-1 and IRP2 on translational regulation. Both in vitro binding and coimmunoprecipitation assays showed the direct interaction of YB-1 and IRP2 in the presence of a high concentration of iron. RNA gel shift assays showed that YB-1 reduced the formation of the IRP2-mRNA complex when the iron-responsive element of the ferritin mRNA 5′ untranslated region (UTR) was used as a probe. By using an in vitro translation assay using luciferase mRNA ligated to the ferritin mRNA 5′UTR as a reporter construct, we showed that both YB-1 and IRP2 inhibited the translation of the mRNA. However, coadministration of YB-1 and IRP2 proteins abrogated the inhibition of protein synthesis by each protein. An In vivo coimmunoprecipitation assay showed that IRP2 bound to YB-1 in the presence of iron and a proteasome inhibitor. The direct interaction of YB-1 and IRP2 provides the first evidence of the involvement of YB-1 in the translational regulation of an iron-related protein.

scholarly journals Translational regulation of ferritin synthesis in rat liver. Effects of chronic dietary iron overload

1989 ◽  
Vol 264 (3) ◽  
pp. 925-928 ◽  
Author(s):  
G Cairo ◽  
L Tacchini ◽  
L Schiaffonati ◽  
E Rappocciolo ◽  
E Ventura ◽  
...  
Keyword(s):  
Iron Overload ◽  
Translational Regulation ◽  
Dietary Iron ◽  
Iron Storage ◽  
Subunit Mrna ◽  
Ferritin Synthesis ◽  
Parenteral Iron ◽  
Liver Ferritin ◽  
Ferritin H

In rats with chronic dietary iron overload, a higher amount of liver ferritin L-subunit mRNA was found mainly engaged on polysomes, whereas in control rats ferritin L-subunit mRNA molecules were largely stored in ribonucleoprotein particles. On the other hand, ferritin H-subunit mRNA was unchanged by chronic iron load and remained in the inactive cytoplasmic pool. In agreement with previous reports, in rats acutely treated with parenteral iron, only the ferritin L-subunit mRNA increased in amount, whereas both ferritin subunit mRNAs shifted to polysomes. This may indicate that, whereas in acute iron overload the hepatocyte operates a translation shift of both ferritin mRNAs to confront rapidly the abrupt entry of iron into the cell, during chronic iron overload it responds to the slow iron influx by translating a greater amount of L-subunit mRNA to synthesize isoferritins more suitable for long-term iron storage.

scholarly journals Detecting translational regulation by change point analysis of ribosome profiling datasets

2014 ◽  
Author(s):  
Anze Zupanic ◽  
Catherine Meplan ◽  
Sushma N Grellscheid ◽  
John C Mathers ◽  
Tom BL Kirkwood ◽  
...  
Keyword(s):  
Translational Control ◽  
Change Point ◽  
Translational Regulation ◽  
Embryonic Stem ◽  
Ribosome Profiling ◽  
Change Point Analysis ◽  
Coding Region ◽  
Ribosome Density ◽  
Point Analysis ◽  
Post Transcriptional Regulation

Ribo-Seq maps the location of translating ribosomes on mature mRNA transcripts. While ribosome density is constant along the length of the mRNA coding region, it can be altered by translational regulatory events. In this study, we developed a method to detect translational regulation of individual mRNAs from their ribosome profiles, utilizing changes in ribosome density. We used mathematical modelling to show that changes in ribosome density should occur along the mRNA at the point of regulation. We analyzed a Ribo-Seq dataset obtained for mouse embryonic stem cells and showed that normalization by corresponding RNA-Seq can be used to improve the Ribo-Seq quality by removing bias introduced by deep-sequencing and alignment artefacts. After normalization, we applied a change point algorithm to detect changes in ribosome density present in individual mRNA ribosome profiles. Additional sequence and gene isoform information obtained from the UCSC Genome Browser allowed us to further categorize the detected changes into different mechanisms of regulation. In particular, we detected several mRNAs with known post-transcriptional regulation, e.g. premature termination for selenoprotein mRNAs and translational control of Atf4, but also several more mRNAs with hitherto unknown translational regulation. Additionally, our approach proved useful for identification of new gene isoforms.

scholarly journals Identification of the iron-responsive element for the translational regulation of human ferritin mRNA

Science ◽  
1987 ◽  
Vol 238 (4833) ◽  
pp. 1570-1573 ◽  
Author(s):  
M. Hentze ◽  
S. Caughman ◽  
T. Rouault ◽  
J. Barriocanal ◽  
A Dancis ◽  
...  
Keyword(s):  
Translational Regulation ◽  
Iron Responsive Element ◽  
Human Ferritin ◽  
Responsive Element

scholarly journals Ferritin translation by interleukin-6: the role of sequences upstream of the start codons of the heavy and light subunit genes

Blood ◽  
1996 ◽  
Vol 87 (6) ◽  
pp. 2525-2537 ◽  
Author(s):  
JT Rogers
Keyword(s):  
Translational Regulation ◽  
Umbilical Vein ◽  
Start Codon ◽  
Moderate Increase ◽  
Human Hepatoma Cells ◽  
Iron Storage ◽  
Translational Enhancer ◽  
Umbilical Vein Endothelial Cells ◽  
Ferritin H

Interleukin-1beta (IL-1beta) elevates H- and L-ferritin subunit synthesis in both human hepatoma cells (HepG2) and primary human umbilical vein endothelial cells. Ferritin induction is greater than the increase in total HepG2 protein synthesis in response to IL-1. IL-6 causes a moderate increase in L-subunit synthesis. The levels of the mRNAs for the ferritin H-subunits (H-mRNA) and light subunits (L-mRNA) remain unchanged, indicating that expression of the iron storage protein, ferritin, is regulated by translational mechanisms during inflammation. We have found a translational enhancer region in the L- ferritin mRNA 5′UTR that confers two-fold baseline and twofold IL-1- dependent translational regulation to a CAT reporter message. The L- mRNA motif is related to a 61 nucleotide (nt) G+C-rich translational enhancer within 70 nt of the H-ferritin start codon. Sequences upstream of the start codons (SUS elements) in both H-mRNA and L-mRNAs confer IL- 1beta but not IL-6-dependent translation to hybrid ferritin/CAT reporter mRNAs. The H- and L-ferritin mRNA SUS elements contain a motif similar to a consensus reported for the 5′ leaders of other acute phase response mRNAs. Transfected hybrid H-mRNA SUS/CAT mRNAs with a three nucleotide deleted version of the H-mRNA SUS displays an eightfold reduced level of translation and no longer confer IL-1beta-dependent translation.

scholarly journals Modulation of ferritin H-chain expression in Friend erythroleukemia cells: transcriptional and translational regulation by hemin.

1992 ◽  
Vol 12 (7) ◽  
pp. 3015-3022 ◽  
Author(s):  
E M Coccia ◽  
V Profita ◽  
G Fiorucci ◽  
G Romeo ◽  
E Affabris ◽  
...  
Keyword(s):  
Translational Regulation ◽  
Protoporphyrin Ix ◽  
Mrna Translation ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Iron Storage ◽  
Erythroleukemia Cells ◽  
Mrna Content ◽  
Friend Erythroleukemia Cells ◽  
Ferritin H

The mechanisms that regulate the expression of the H chain of the iron storage protein ferritin in Friend erythroleukemia cells (FLCs) after exposure to hemin (ferric protoporphyrin IX), protoporphyrin IX, and ferric ammonium citrate (FAC) have been investigated. Administration of hemin increases the steady-state level of ferritin mRNA about 10-fold and that of ferritin protein expression 20-fold. Experiments with the transcriptional inhibitor actinomycin D and transfection studies demonstrate that the increment in cytoplasmic mRNA content results from enhanced transcription of the ferritin H-chain gene and cannot be attributed to stabilization of preexisting mRNAs. In addition to transcriptional effects, translational regulation induces the recruitment of stored mRNAs into functional polyribosomes after hemin and FAC administration, resulting in a further increase in ferritin synthesis. Administration of protoporphyrin IX to FLCs produces divergent transcriptional and translational effects. It increases transcription but appears to suppress ferritin mRNA translation. FAC treatment increases the mRNA content slightly (about twofold), and the ferritin levels rise about fivefold over the control values. We conclude that in FLCs, hemin induces ferritin H-chain biosynthesis by multiple mechanisms: a transcriptional mechanism exerted also by protoporphyrin IX and a translational one, not displayed by protoporphyrin IX but shared with FAC.

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