Erythroid expression of the heme-regulated eIF-2 alpha kinase

1994 ◽  
Vol 14 (6) ◽  
pp. 3906-3914
Author(s):  
J S Crosby ◽  
K Lee ◽  
I M London ◽  
J J Chen
Keyword(s):  
Protein Synthesis ◽  
K562 Cells ◽  
Cell Types ◽  
Erythroid Cell ◽  
Induction Medium ◽  
Mrna Accumulation ◽  
Mrna Induction ◽  
Specific Manner ◽  
Low Levels

The role of heme-regulated eIF-2 alpha kinase (HRI) in the regulation of protein synthesis in rabbit reticulocytes is well documented. Inhibitors of protein synthesis with properties similar to those of HRI have been described in some nonerythroid cell types, but it has not yet been determined whether these eIF-2 alpha kinase activities are mediated by HRI or one or more as yet uncharacterized kinases. We have studied the expression of mRNA, polypeptide, and kinase activities of HRI in various tissues from both nonanemic and anemic rabbits. Our results indicate that HRI is expressed in an erythroid cell-specific manner. HRI is present in the bone marrow and peripheral blood of both nonanemic and anemic rabbits but not in any of the other tissues tested. HRI mRNA is present at low levels in uninduced mouse erythroleukemic (MEL) cells and human K562 cells and accumulates to higher levels upon induction. The accumulation of HRI mRNA in differentiating MEL cells is dependent upon the presence of heme. The addition of 3-amino-1,2,4-triazole (AT), an inhibitor of heme biosynthesis, to the induction medium markedly reduced HRI mRNA accumulation. Simultaneous addition of hemin and AT to the dimethyl sulfoxide induction medium largely prevented the inhibition of HRI mRNA induction by AT. These findings indicate that HRI is expressed in an erythroid cell-specific manner and that the major physiologic role of HRI is in adjusting the synthesis of globins to the availability of heme.

scholarly journals Erythroid expression of the heme-regulated eIF-2 alpha kinase.

1994 ◽  
Vol 14 (6) ◽  
pp. 3906-3914 ◽  
Author(s):  
J S Crosby ◽  
K Lee ◽  
I M London ◽  
J J Chen
Keyword(s):  
Protein Synthesis ◽  
K562 Cells ◽  
Cell Types ◽  
Erythroid Cell ◽  
Induction Medium ◽  
Mrna Accumulation ◽  
Mrna Induction ◽  
Specific Manner ◽  
Low Levels

The role of heme-regulated eIF-2 alpha kinase (HRI) in the regulation of protein synthesis in rabbit reticulocytes is well documented. Inhibitors of protein synthesis with properties similar to those of HRI have been described in some nonerythroid cell types, but it has not yet been determined whether these eIF-2 alpha kinase activities are mediated by HRI or one or more as yet uncharacterized kinases. We have studied the expression of mRNA, polypeptide, and kinase activities of HRI in various tissues from both nonanemic and anemic rabbits. Our results indicate that HRI is expressed in an erythroid cell-specific manner. HRI is present in the bone marrow and peripheral blood of both nonanemic and anemic rabbits but not in any of the other tissues tested. HRI mRNA is present at low levels in uninduced mouse erythroleukemic (MEL) cells and human K562 cells and accumulates to higher levels upon induction. The accumulation of HRI mRNA in differentiating MEL cells is dependent upon the presence of heme. The addition of 3-amino-1,2,4-triazole (AT), an inhibitor of heme biosynthesis, to the induction medium markedly reduced HRI mRNA accumulation. Simultaneous addition of hemin and AT to the dimethyl sulfoxide induction medium largely prevented the inhibition of HRI mRNA induction by AT. These findings indicate that HRI is expressed in an erythroid cell-specific manner and that the major physiologic role of HRI is in adjusting the synthesis of globins to the availability of heme.

scholarly journals Platelet and Erythrocyte Extravasation across Inflamed Corneal Venules Depend on CD18, Neutrophils and Mast Cell Degranulation

2021 ◽  
Vol 22 (14) ◽  
pp. 7360
Author(s):  
Angie De La Cruz ◽  
Aubrey Hargrave ◽  
Sri Magadi ◽  
Justin A. Courson ◽  
Paul T. Landry ◽  
...  
Keyword(s):  
Mast Cell ◽  
Cell Types ◽  
Mast Cell Degranulation ◽  
Wild Type ◽  
Delayed Wound Healing ◽  
Corneal Epithelial ◽  
Corneal Abrasion ◽  
Low Levels ◽  
Endothelial Pores

Platelet extravasation during inflammation is under-appreciated. In wild-type (WT) mice, a central corneal epithelial abrasion initiates neutrophil (PMN) and platelet extravasation from peripheral limbal venules. The same injury in mice expressing low levels of the β2-integrin, CD18 (CD18hypo mice) shows reduced platelet extravasation with PMN extravasation apparently unaffected. To better define the role of CD18 on platelet extravasation, we focused on two relevant cell types expressing CD18: PMNs and mast cells. Following corneal abrasion in WT mice, we observed not only extravasated PMNs and platelets but also extravasated erythrocytes (RBCs). Ultrastructural observations of engorged limbal venules showed platelets and RBCs passing through endothelial pores. In contrast, injured CD18hypo mice showed significantly less venule engorgement and markedly reduced platelet and RBC extravasation; mast cell degranulation was also reduced compared to WT mice. Corneal abrasion in mast cell-deficient (KitW-sh/W-sh) mice showed less venule engorgement, delayed PMN extravasation, reduced platelet and RBC extravasation and delayed wound healing compared to WT mice. Finally, antibody-induced depletion of circulating PMNs prior to corneal abrasion reduced mast cell degranulation, venule engorgement, and extravasation of PMNs, platelets, and RBCs. In summary, in the injured cornea, platelet and RBC extravasation depends on CD18, PMNs, and mast cell degranulation.

Control of Hemoglobin Synthesis in Erythroid Differentiating K562 Cells I. Role of Iron in Erythroid Cell Heme Synthesis

1996 ◽  
Vol 328 (2) ◽  
pp. 289-294 ◽  
Author(s):  
Nana Kawasaki ◽  
Kazushige Morimoto ◽  
Tsuyoshi Tanimoto ◽  
Takao Hayakawa
Keyword(s):  
K562 Cells ◽  
Erythroid Cell ◽  
Hemoglobin Synthesis ◽  
Heme Synthesis

scholarly journals Atypical Cristae Morphology of Human Syncytiotrophoblast Mitochondria

2011 ◽  
Vol 286 (27) ◽  
pp. 23911-23919 ◽  
Author(s):  
Daniela De Los Rios Castillo ◽  
Mariel Zarco-Zavala ◽  
Sofia Olvera-Sanchez ◽  
Juan Pablo Pardo ◽  
Oscar Juarez ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Physiological Function ◽  
Cell Types ◽  
Dimeric Complex ◽  
Inhibitory Protein ◽  
Low Levels ◽  
Mitochondrial Complexes

Mitochondrial complexes I, III2, and IV from human cytotrophoblast and syncytiotrophoblast associate to form supercomplexes or respirasomes, with the following stoichiometries: I1:(III2)1 and I1:(III2)1–2:IV1–4. The content of respirasomes was similar in both cell types after isolating mitochondria. However, syncytiotrophoblast mitochondria possess low levels of dimeric complex V and do not have orthodox cristae morphology. In contrast, cytotrophoblast mitochondria show normal cristae morphology and a higher content of ATP synthase dimer. Consistent with the dimerizing role of the ATPase inhibitory protein (IF1) (García, J. J., Morales-Ríos, E., Cortés-Hernandez, P., and Rodríguez-Zavala, J. S. (2006) Biochemistry 45, 12695–12703), higher relative amounts of IF1 were observed in cytotrophoblast when compared with syncytiotrophoblast mitochondria. Therefore, there is a correlation between dimerization of complex V, IF1 expression, and the morphology of mitochondrial cristae in human placental mitochondria. The possible relationship between cristae architecture and the physiological function of the syncytiotrophoblast mitochondria is discussed.

scholarly journals Synthesis of eosinophil-associated enzymes in HL-60 promyelocytic leukemia cells

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 185-192 ◽  
Author(s):  
SA Fischkoff ◽  
GE Brown ◽  
A Pollak
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Promyelocytic Leukemia ◽  
Leukemia Cells ◽  
Acute Myelomonocytic Leukemia ◽  
Granule Morphology ◽  
Synthesis And Processing ◽  
Low Levels ◽  
Myelomonocytic Leukemia

Abstract Eosinophils derived from HL-60 cells share many of the abnormalities of granule histochemistry and morphology frequently seen in eosinophils of patients with certain malignancies, especially those seen in acute myelomonocytic leukemia with abnormal eosinophils (FAB class M4eo). In order to understand the pathogenesis of these abnormalities, four enzymes, characteristic of the eosinophil, were studied in HL-60 promyelocytic leukemia cells at various stages of eosinophilic differentiation. Using biochemical and ultrahistochemical techniques, the following differences from normal eosinophil development were demonstrated. First, both myeloperoxidase and eosinophil peroxidase coexisted in the population of maturing HL-60 eosinophils. Second, the granules formed from the condensation of material in vacuoles which were derived from dilated segments of the endoplasmic reticulum; the role of the Golgi apparatus in processing of peroxidase appeared minimal. Third, low levels of lysophospholipase and arylsulfatase were present in the cells compared to normal eosinophils. Finally, crystallizations resembling precursor structures of Auer rods appeared in the granules of about 5% of the cells. These findings suggest that several disorders of the control of protein synthesis and processing exist in HL-60 eosinophils which may be responsible for the abnormal granule morphology and histochemistry.

scholarly journals A Tailor-Made Protein Synthesis Program Drives Erythroid Development and Disease

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3581-3581
Author(s):  
Craig M Forester ◽  
Zhen Shi ◽  
Maria Barna ◽  
Davide Ruggero
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Cell Function ◽  
Conflicts Of Interest ◽  
Erythroid Cell ◽  
Translation Control ◽  
Erythroid Progenitors ◽  
Erythroid Precursor ◽  
Erythroid Development

Abstract Erythropoiesis constitutes the largest demand on the hematopoietic system due to its extraordinary production on a daily basis. The erythroid proteome requires an integration of multiple external cues to coordinate programs of differentiation as well as maintenance of erythroid precursors. The biomedical relevance of this critical process is underscored by recent findings showing impaired ribosome function in an entire class of clinical disorders with severe impairments in erythroid differentiation, known as ribosomopathies, which remain poorly understood. One of the main signaling pathways controlling post-transcriptional gene expression during erythropoiesis is the mTOR pathway. mTOR activation downstream of SCF/Epo in erythroid progenitors controls the activity of the major cap-binding protein eIF4E. However, the functional role of eIF4E during erythropoiesis and protein synthesis control in this cell type remains unexplored. Here we show that eIF4E activity, through mTOR-dependent phosphorylation of its inhibitory protein 4EBP1, unexpectedly undergoes a dynamic switch between early erythroid precursor populations and during terminal erythrocyte maturation, where eIF4E becomes progressively silenced. Employing a unique eIF4E transgenic mouse model, we strikingly show that overexpression of eIF4E in the bone marrow compartment results in an early accumulation of erythrocyte precursors and a block in erythrocyte differentiation. Surprisingly, this new role of eIF4E in erythropoiesis is independent from control of global protein synthesis but instead may promote a specialized program of translation control that is customized for erythroid cell function. Employing state of the art unbiased proteomics, our work is uncovering distinct networks of proteins, whose expression levels are controlled by eIF4E dosage during specific phases of erythrocyte maturation. Together, our research highlights a novel molecular program linking exquisite regulation of eIF4E activity to specialized translational control underlying erythroid development, providing unprecedented insight into the etiology of erythroid dysfunction in ribosomopathies. Disclosures No relevant conflicts of interest to declare.

scholarly journals Synthesis of eosinophil-associated enzymes in HL-60 promyelocytic leukemia cells

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 185-192
Author(s):  
SA Fischkoff ◽  
GE Brown ◽  
A Pollak
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Promyelocytic Leukemia ◽  
Leukemia Cells ◽  
Acute Myelomonocytic Leukemia ◽  
Granule Morphology ◽  
Synthesis And Processing ◽  
Low Levels ◽  
Myelomonocytic Leukemia

Eosinophils derived from HL-60 cells share many of the abnormalities of granule histochemistry and morphology frequently seen in eosinophils of patients with certain malignancies, especially those seen in acute myelomonocytic leukemia with abnormal eosinophils (FAB class M4eo). In order to understand the pathogenesis of these abnormalities, four enzymes, characteristic of the eosinophil, were studied in HL-60 promyelocytic leukemia cells at various stages of eosinophilic differentiation. Using biochemical and ultrahistochemical techniques, the following differences from normal eosinophil development were demonstrated. First, both myeloperoxidase and eosinophil peroxidase coexisted in the population of maturing HL-60 eosinophils. Second, the granules formed from the condensation of material in vacuoles which were derived from dilated segments of the endoplasmic reticulum; the role of the Golgi apparatus in processing of peroxidase appeared minimal. Third, low levels of lysophospholipase and arylsulfatase were present in the cells compared to normal eosinophils. Finally, crystallizations resembling precursor structures of Auer rods appeared in the granules of about 5% of the cells. These findings suggest that several disorders of the control of protein synthesis and processing exist in HL-60 eosinophils which may be responsible for the abnormal granule morphology and histochemistry.

scholarly journals A Highly Conserved Shh Enhancer Coordinates Hypothalamic and Craniofacial Development

2021 ◽  
Vol 9 ◽  
Author(s):  
Zoe Crane-Smith ◽  
Jeffrey Schoenebeck ◽  
Katy A. Graham ◽  
Paul S. Devenney ◽  
Lorraine Rose ◽  
...  
Keyword(s):  
Null Allele ◽  
Neural Tissue ◽  
Neuronal Population ◽  
Craniofacial Development ◽  
Evolutionary Time ◽  
Enhancer Activity ◽  
Specific Manner ◽  
Low Levels ◽  
Anterior Posterior

Enhancers that are conserved deep in evolutionary time regulate characteristics held in common across taxonomic classes. Here, deletion of the highly conserved Shh enhancer SBE2 (Shh brain enhancer 2) in mouse markedly reduced Shh expression within the embryonic brain specifically in the rostral diencephalon; however, no abnormal anatomical phenotype was observed. Secondary enhancer activity was subsequently identified which likely mediates low levels of expression. In contrast, when crossing the SBE2 deletion with the Shh null allele, brain and craniofacial development were disrupted; thus, linking SBE2 regulated Shh expression to multiple defects and further enabling the study of the effects of differing levels of Shh on embryogenesis. Development of the hypothalamus, derived from the rostral diencephalon, was disrupted along both the anterior-posterior (AP) and the dorsal-ventral (DV) axes. Expression of DV patterning genes and subsequent neuronal population induction were particularly sensitive to Shh expression levels, demonstrating a novel morphogenic context for Shh. The role of SBE2, which is highlighted by DV gene expression, is to step-up expression of Shh above the minimal activity of the second enhancer, ensuring the necessary levels of Shh in a regional-specific manner. We also show that low Shh levels in the diencephalon disrupted neighbouring craniofacial development, including mediolateral patterning of the bones along the cranial floor and viscerocranium. Thus, SBE2 contributes to hypothalamic morphogenesis and ensures there is coordination with the formation of the adjacent midline cranial bones that subsequently protect the neural tissue.

Abstract 32: EBP50 and NF-κB: A Feed-Forward Regulation of Vascular Inflammation

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Kristen Leslie ◽  
GyunJee Song ◽  
Stacey Barrick ◽  
Alessandro Bisello
Keyword(s):  
Macrophage Activation ◽  
Nuclear Translocation ◽  
Vascular Inflammation ◽  
Cell Types ◽  
Dominant Negative ◽  
Scaffolding Protein ◽  
Vsmc Proliferation ◽  
Multiple Cell ◽  
Low Levels

Inflammation plays a fundamental role in the development of cardiovascular diseases such as atherosclerosis and restenosis. The vascular response to inflammation in these diseases requires communication between multiple cell types such as vascular smooth muscle cells (VSMC) and macrophages. We have identified a scaffolding protein, Ezrin Binding Protein 50 (EBP50, also known as NHERF-1), which is expressed at very low levels in normal vessels but is up-regulated following vascular injury. EBP50 promotes VSMC proliferation and neointima formation after wire injury in mouse femoral arteries. In the current study, we hypothesized that EBP50 functions as a central mediator linking macrophage activation and the response of vessels to inflammation. Similar to the observations in vessels, treatment of primary VSMC and macrophages with LPS or TNFα increased EBP50 expression. This increase was dependent on NF-κB signaling because pharmacological inhibition of NF-κB and expression of a dominant negative IκBα abolished the induction of EBP50. Interestingly, LPS-induced activation of NF-κB (determined by phosphorylation of IKKα/β, degradation of IκBα, and p65 phosphorylation) was impaired in EBP50 null VSMC and macrophages. Moreover, nuclear translocation of the p65 subunit of NF-κB was also reduced in EBP50 -/- VSMC. Consistent with the role of EBP50 on NF-κB, LPS- and TNFα-induced macrophage activation (determined by the expression of the inflammatory markers iNOS, TNFα, and IL-1β) was reduced in EBP50 -/- macrophages and mice. Similarly, the expression of iNOS, VCAM-1, and ICAM-1 in VSMC was decreased in EBP50 -/- VSMC and mice. Collectively, these observations indicate that EBP50 and NF-κB participate in a positive feedback loop leading to increased macrophage activation and enhanced response of VSMC to inflammation, suggesting its involvement in vascular remodeling.

scholarly journals Role of transcription factors in the transdifferentiation of pancreatic islet cells

2015 ◽  
Vol 54 (2) ◽  
pp. R103-R117 ◽  
Author(s):  
Talitha van der Meulen ◽  
Mark O Huising
Keyword(s):  
Islet Cells ◽  
Hormone Secretion ◽  
Cell Types ◽  
Glucose Sensing ◽  
Glucose Disposal ◽  
Pancreatic Islet Cells ◽  
Β Cells ◽  
Transcription Factor Networks ◽  
Low Levels

The α and β cells act in concert to maintain blood glucose. The α cells release glucagon in response to low levels of glucose to stimulate glycogenolysis in the liver. In contrast, β cells release insulin in response to elevated levels of glucose to stimulate peripheral glucose disposal. Despite these opposing roles in glucose homeostasis, α and β cells are derived from a common progenitor and share many proteins important for glucose sensing and hormone secretion. Results from recent work have underlined these similarities between the two cell types by revealing that β-to-α as well as α-to-β transdifferentiation can take place under certain experimental circumstances. These exciting findings highlight unexpected plasticity of adult islets and offer hope of novel therapeutic paths to replenish β cells in diabetes. In this review, we focus on the transcription factor networks that establish and maintain pancreatic endocrine cell identity and how they may be perturbed to facilitate transdifferentiation.

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