1
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Cai DL, Chan Y, Kong YM, Liu YZ, Guo Y, Cai AQ, Zhu BS. Ginsenoside Rg1 promotes fetal hemoglobin production in vitro: A potential therapeutic avenue for β-thalassemia. Eur J Pharmacol 2024; 968:176404. [PMID: 38382804 DOI: 10.1016/j.ejphar.2024.176404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/25/2024] [Accepted: 02/06/2024] [Indexed: 02/23/2024]
Abstract
β-thalassemia, a globally prevalent genetic disorder, urgently requires innovative treatment options. Fetal hemoglobin (HbF) induction stands as a key therapeutic approach. This investigation focused on Ginsenoside Rg1 from the Panax genus for HbF induction. Employing K562 cells and human erythroid precursor cells (ErPCs) derived from neonatal cord blood, the study tested Rg1 at different concentrations. We measured its effects on γ-globin mRNA levels and HbF expression, alongside assessments of cell proliferation and differentiation. In K562 cells, Rg1 at 400 μM significantly increased γ-globin mRNA expression by 4.24 ± 1.08-fold compared to the control. In ErPCs, the 800 μM concentration was most effective, leading to an over 80% increase in F-cells and a marked upregulation in HbF expression. Notably, Rg1 did not adversely affect cell proliferation or differentiation, with the 200 μM concentration showing an increase in γ-globin mRNA by 2.33 ± 0.58-fold, and the 800 μM concentration enhancing HbF expression by 2.59 ± 0.03-fold in K562 cells. Our results underscore Rg1's potential as an effective and safer alternative for β-thalassemia treatment. By significantly enhancing HbF levels without cytotoxicity, Rg1 offers a notable advantage over traditional treatments like Hydroxyurea. While promising, these in vitro findings warrant further in vivo exploration to confirm Rg1's therapeutic efficacy and to unravel its underlying mechanistic pathways.
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Affiliation(s)
- Dong-Ling Cai
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China
| | - Ying Chan
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Department of Medical Genetics, NHC Key Laboratory of Preconception Health Birth in Western China, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, 650032, China
| | - Ya-Min Kong
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Department of Medical Genetics, NHC Key Laboratory of Preconception Health Birth in Western China, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, 650032, China
| | - Yi-Ze Liu
- Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China
| | - Yan Guo
- Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China
| | - Ai-Qi Cai
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Department of Medical Genetics, NHC Key Laboratory of Preconception Health Birth in Western China, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, 650032, China
| | - Bao-Sheng Zhu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Medical School, Kunming University of Science and Technology, Kunming, 650500, Yunnan Province, China; Department of Medical Genetics, NHC Key Laboratory of Preconception Health Birth in Western China, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, 650032, China.
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2
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Elagooz R, Dhara AR, Gott RM, Adams SE, White RA, Ghosh A, Ganguly S, Man Y, Owusu-Ansah A, Mian OY, Gurkan UA, Komar AA, Ramamoorthy M, Gnanapragasam MN. PUM1 mediates the posttranscriptional regulation of human fetal hemoglobin. Blood Adv 2022; 6:6016-6022. [PMID: 35667093 PMCID: PMC9699939 DOI: 10.1182/bloodadvances.2021006730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 05/30/2022] [Indexed: 12/14/2022] Open
Abstract
The fetal-to-adult hemoglobin switching at about the time of birth involves a shift in expression from γ-globin to β-globin in erythroid cells. Effective re-expression of fetal γ-globin can ameliorate sickle cell anemia and β-thalassemia. Despite the physiological and clinical relevance of this switch, its posttranscriptional regulation is poorly understood. Here, we identify Pumilo 1 (PUM1), an RNA-binding protein with no previously reported functions in erythropoiesis, as a direct posttranscriptional regulator of β-globin switching. PUM1, whose expression is regulated by the erythroid master transcription factor erythroid Krüppel-like factor (EKLF/KLF1), peaks during erythroid differentiation, binds γ-globin messenger RNA (mRNA), and reduces γ-globin (HBG1) mRNA stability and translational efficiency, which culminates in reduced γ-globin protein levels. Knockdown of PUM1 leads to a robust increase in fetal hemoglobin (∼22% HbF) without affecting β-globin levels in human erythroid cells. Importantly, targeting PUM1 does not limit the progression of erythropoiesis, which provides a potentially safe and effective treatment strategy for sickle cell anemia and β-thalassemia. In support of this idea, we report elevated levels of HbF in the absence of anemia in an individual with a novel heterozygous PUM1 mutation in the RNA-binding domain (p.(His1090Profs∗16); c.3267_3270delTCAC), which suggests that PUM1-mediated posttranscriptional regulation is a critical player during human hemoglobin switching.
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Affiliation(s)
- Reem Elagooz
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
| | - Anita R. Dhara
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
| | - Rose M. Gott
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
| | - Sarah E. Adams
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
| | - Rachael A. White
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
| | - Arnab Ghosh
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH
| | - Shinjini Ganguly
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH
| | - Yuncheng Man
- Department of Mechanical and Aerospace Engineering, University Hospitals Rainbow Babies and Children’s Hospital, Case Western Reserve University, Cleveland, OH
| | - Amma Owusu-Ansah
- Department of Pediatrics, Division of Hematology and Oncology, University Hospitals Rainbow Babies and Children’s Hospital, Case Western Reserve University, Cleveland, OH
| | - Omar Y. Mian
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH
| | - Umut A. Gurkan
- Department of Mechanical and Aerospace Engineering, University Hospitals Rainbow Babies and Children’s Hospital, Case Western Reserve University, Cleveland, OH
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH
| | - Anton A. Komar
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH
| | - Mahesh Ramamoorthy
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH
| | - Merlin Nithya Gnanapragasam
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH
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3
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Abstract
PURPOSE OF REVIEW HRI is the heme-regulated elF2α kinase that phosphorylates the α-subunit of elF2. Although the role of HRI in inhibiting globin synthesis in erythroid cells is well established, broader roles of HRI in translation have been uncovered recently. This review is to summarize the new discoveries of HRI in stress erythropoiesis and in fetal γ-globin expression. RECENT FINDINGS HRI and activating transcription factor 4 (ATF4) mRNAs are highly expressed in early erythroblasts. Inhibition of protein synthesis by HRI-phosphorylated elF2α (elF2αP) is necessary to maintain protein homeostasis in both the cytoplasm and mitochondria. In addition, HRI-elF2αP specifically enhances translation of ATF4 mRNA leading to the repression of mechanistic target of rapamycin complex 1 (mTORC1) signaling. ATF4-target genes are most highly activated during iron deficiency to maintain mitochondrial function, redox homeostasis, and to enable erythroid differentiation. HRI is therefore a master translation regulator of erythropoiesis sensing intracellular heme concentrations and oxidative stress for effective erythropoiesis. Intriguingly, HRI-elF2αP-ATF4 signaling also inhibits fetal hemoglobin production in human erythroid cells. SUMMARY The primary function of HRI is to maintain protein homeostasis accompanied by the induction of ATF4 to mitigate stress. Role of HRI-ATF4 in γ-globin expression raises the potential of HRI as a therapeutic target for hemoglobinopathy.
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Affiliation(s)
- Jane-Jane Chen
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Shuping Zhang
- Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250062, China
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4
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Gee BE, Pearson A, Buchanan-Perry I, Simon RP, Archer DR, Meller R. Whole Blood Transcriptome Analysis in Children with Sickle Cell Anemia. Front Genet 2022; 12:737741. [PMID: 35095995 PMCID: PMC8793691 DOI: 10.3389/fgene.2021.737741] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 10/20/2021] [Indexed: 12/27/2022] Open
Abstract
Whole transcriptome RNA-sequencing was performed to quantify RNA expression changes in whole blood samples collected from steady state sickle cell anemia (SCA) and control subjects. Pediatric SCA and control subjects were recruited from Atlanta (GA)-based hospital(s) systems and consented for RNA sequencing. RNA sequencing was performed on an Ion Torrent S5 sequencer, using the Ion Total RNA-seq v2 protocol. Data were aligned to the hg19 reference genome and analyzed in the Partek Genomics studio package (v7.0). 223 genes were differentially expressed between SCA and controls (± 1.5 fold change FDR p < 0.001) and 441 genes show differential transcript expression (± 1.5 fold FDR p < 0.001). Differentially expressed RNA are enriched for hemoglobin associated genes and ubiquitin-proteasome pathway genes. Further analysis shows higher gamma globin gene expression in SCA (33-fold HBG1 and 49-fold HBG2, both FDR p < 0.05), which did not correlate with hemoglobin F protein levels. eQTL analysis identified SNPs in novel non-coding RNA RYR2 gene as having a potential regulatory role in HBG1 and HBG2 expression levels. Gene expression correlation identified JHDM1D-AS1(KDM7A-DT), a non-coding RNA associated with angiogenesis, enhanced GATA1 and decreased JAK-STAT signaling to correlate with HBG1 and HBG2 mRNA levels. These data suggest novel regulatory mechanisms for fetal hemoglobin regulation, which may offer innovative therapeutic approaches for SCA.
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Affiliation(s)
- Beatrice E. Gee
- Department of Pediatrics, Morehouse School of Medicine, Atlanta, GA, United States
- Morehouse School of Medicine, Cardiovascular Research Institute, Atlanta, GA, United States
- Children’s Healthcare of Atlanta, Atlanta, GA, United States
| | - Andrea Pearson
- Translational Stroke Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, United States
| | - Iris Buchanan-Perry
- Department of Pediatrics, Morehouse School of Medicine, Atlanta, GA, United States
- Children’s Healthcare of Atlanta, Atlanta, GA, United States
| | - Roger P. Simon
- Translational Stroke Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, United States
- Grady Memorial Hospital, Atlanta, GA, United States
- Department of Neurology, Morehouse School of Medicine, Atlanta, GA, United States
| | - David R. Archer
- Aflac Cancer and Blood Disorders Center of Emory University and Children’s Healthcare of Atlanta, Atlanta, GA, United States
| | - Robert Meller
- Translational Stroke Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, United States
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5
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Boontanrart MY, Schröder MS, Stehli GM, Banović M, Wyman SK, Lew RJ, Bordi M, Gowen BG, DeWitt MA, Corn JE. ATF4 Regulates MYB to Increase γ-Globin in Response to Loss of β-Globin. Cell Rep 2021; 32:107993. [PMID: 32755585 DOI: 10.1016/j.celrep.2020.107993] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 05/20/2020] [Accepted: 07/14/2020] [Indexed: 12/26/2022] Open
Abstract
β-Hemoglobinopathies can trigger rapid production of red blood cells in a process known as stress erythropoiesis. Cellular stress prompts differentiating erythroid precursors to express high levels of fetal γ-globin. However, the mechanisms underlying γ-globin production during cellular stress are still poorly defined. Here, we use CRISPR-Cas genome editing to model the stress caused by reduced levels of adult β-globin. We find that decreased β-globin is sufficient to induce robust re-expression of γ-globin, and RNA sequencing (RNA-seq) of differentiating isogenic erythroid precursors implicates ATF4 as a causal regulator of this response. ATF4 binds within the HBS1L-MYB intergenic enhancer and regulates expression of MYB, a known γ-globin regulator. Overall, the reduction of ATF4 upon β-globin knockout decreases the levels of MYB and BCL11A. Identification of ATF4 as a key regulator of globin compensation adds mechanistic insight to the poorly understood phenomenon of stress-induced globin compensation and could inform strategies to treat hemoglobinopathies.
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Affiliation(s)
- Mandy Y Boontanrart
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | | | - Marija Banović
- Department of Biology, ETH Zurich, Zurich 8092, Switzerland
| | - Stacia K Wyman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Rachel J Lew
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Matteo Bordi
- Department of Biology, ETH Zurich, Zurich 8092, Switzerland
| | - Benjamin G Gowen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Mark A DeWitt
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jacob E Corn
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Biology, ETH Zurich, Zurich 8092, Switzerland; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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6
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The methyltransferase PRMT1 regulates γ-globin translation. J Biol Chem 2021; 296:100417. [PMID: 33587951 PMCID: PMC7966866 DOI: 10.1016/j.jbc.2021.100417] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/03/2021] [Accepted: 02/10/2021] [Indexed: 12/30/2022] Open
Abstract
Induction of fetal hemoglobin to overcome adult β-globin gene deficiency is an effective therapeutic strategy to ameliorate human β-hemoglobinopathies. Previous work has revealed that fetal γ-globin can be translationally induced via integrated stress signaling, but other studies have indicated that activating stress may eventually suppress γ-globin expression transcriptionally. The mechanism by which γ-globin expression is regulated at the translational level remains largely unknown, limiting our ability to determine whether activating stress is a realistic therapeutic option for these disorders. In this study, we performed a functional CRISPR screen targeting protein arginine methyltransferases (PRMTs) to look for changes in γ-globin expression in K562 cells. We not only discovered that several specific PRMTs may block γ-globin transcription, but also revealed PRMT1 as a unique family member that is able to suppress γ-globin synthesis specifically at the translational level. We further identified that a non-AUG uORF within the 5' untranslated region of γ-globin serves as a barrier for translation, which is bypassed upon PRMT1 deficiency. Finally, we found that this novel mechanism of γ-globin suppression could be pharmacologically targeted by the PRMT1 inhibitor, furamidine dihydrochloride. These data raise new questions regarding methyltransferase function and may offer a new therapeutic direction for β-hemoglobinopathies.
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7
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The HRI-regulated transcription factor ATF4 activates BCL11A transcription to silence fetal hemoglobin expression. Blood 2021; 135:2121-2132. [PMID: 32299090 DOI: 10.1182/blood.2020005301] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/08/2020] [Indexed: 12/19/2022] Open
Abstract
Reactivation of fetal hemoglobin remains a critical goal in the treatment of patients with sickle cell disease and β-thalassemia. Previously, we discovered that silencing of the fetal γ-globin gene requires the erythroid-specific eIF2α kinase heme-regulated inhibitor (HRI), suggesting that HRI might present a pharmacologic target for raising fetal hemoglobin levels. Here, via a CRISPR-Cas9-guided loss-of-function screen in human erythroblasts, we identify transcription factor ATF4, a known HRI-regulated protein, as a novel γ-globin regulator. ATF4 directly stimulates transcription of BCL11A, a repressor of γ-globin transcription, by binding to its enhancer and fostering enhancer-promoter contacts. Notably, HRI-deficient mice display normal Bcl11a levels, suggesting species-selective regulation, which we explain here by demonstrating that the analogous ATF4 motif at the murine Bcl11a enhancer is largely dispensable. Our studies uncover a linear signaling pathway from HRI to ATF4 to BCL11A to γ-globin and illustrate potential limits of murine models of globin gene regulation.
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8
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Lei J, Paul J, Wang Y, Gupta M, Vang D, Thompson S, Jha R, Nguyen J, Valverde Y, Lamarre Y, Jones MK, Gupta K. Heme Causes Pain in Sickle Mice via Toll-Like Receptor 4-Mediated Reactive Oxygen Species- and Endoplasmic Reticulum Stress-Induced Glial Activation. Antioxid Redox Signal 2021; 34:279-293. [PMID: 32729340 PMCID: PMC7821434 DOI: 10.1089/ars.2019.7913] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aims: Lifelong pain is a hallmark feature of sickle cell disease (SCD). How sickle pathobiology evokes pain remains unknown. We hypothesize that increased cell-free heme due to ongoing hemolysis activates toll-like receptor 4 (TLR4), leading to the formation of reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress. Together, these processes lead to spinal microglial activation and neuroinflammation, culminating in acute and chronic pain. Results: Spinal heme levels, TLR4 transcripts, oxidative stress, and ER stress were significantly higher in sickle mice than controls. In vitro, TLR4 inhibition in spinal cord microglial cells attenuated heme-induced ROS and ER stress. Heme treatment led to a time-dependent increase in the characteristic features of sickle pain (mechanical and thermal hyperalgesia) in both sickle and control mice; this effect was absent in TLR4-knockout sickle and control mice. TLR4 deletion in sickle mice attenuated chronic and hypoxia/reoxygenation (H/R)-evoked acute hyperalgesia. Sickle mice treated with the TLR4 inhibitor resatorvid; selective small-molecule inhibitor of TLR4 (TAK242) had significantly reduced chronic hyperalgesia and had less severe H/R-evoked acute pain with quicker recovery. Notably, reducing ER stress with salubrinal ameliorated chronic hyperalgesia in sickle mice. Innovation: Our findings demonstrate the causal role of free heme in the genesis of acute and chronic sickle pain and suggest that TLR4 and/or ER stress are novel therapeutic targets for treating pain in SCD. Conclusion: Heme-induced microglial activation via TLR4 in the central nervous system contributes to the initiation and maintenance of sickle pain via ER stress in SCD. Antioxid. Redox Signal. 34, 279-293.
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Affiliation(s)
- Jianxun Lei
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Jinny Paul
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ying Wang
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Mihir Gupta
- Department of Neurosurgery, University of California San Diego, La Jolla, California, USA
| | - Derek Vang
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Susan Thompson
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ritu Jha
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Julia Nguyen
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yessenia Valverde
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yann Lamarre
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Michael K Jones
- Division of Hematology/Oncology, Department of Medicine, University of California, Irvine, Irvine, California, USA.,Southern California Institute for Research and Education, Long Beach, California, USA
| | - Kalpna Gupta
- Vascular Biology Center, Division of Hematology, Oncology & Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA.,Division of Hematology/Oncology, Department of Medicine, University of California, Irvine, Irvine, California, USA.,Southern California Institute for Research and Education, Long Beach, California, USA
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9
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HRI stress signaling and HbF production. Blood 2021; 135:2113-2114. [PMID: 32526022 DOI: 10.1182/blood.2020006300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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10
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Hirano T, Tsuruda T, Tanaka Y, Harada H, Yamazaki T, Ishida A. Long noncoding RNA CCDC26 as a modulator of transcriptional switching between fetal and embryonic globins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118931. [PMID: 33340546 DOI: 10.1016/j.bbamcr.2020.118931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/04/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023]
Abstract
The CCDC26 gene is considered to encode a functional noncoding RNA associated with acute myeloid leukemia and other cancers. However, investigations into the physiological roles of CCDC26 are rare. Previously, we reported that CCDC26 regulated proliferation and cell death of leukemia cells through KIT, a receptor tyrosine kinase, by using K562 leukemia cells and their derivative CCDC26-knockdown (KD) cells. Here we propose a new role of CCDC26 in the differentiation of erythroid cells. We showed that expression of embryonic (ε- and ζ-) globins was markedly upregulated in CCDC26-KD cells compared with K562 control cells during hemin-induced differentiation. In contrast, expression of fetal-type γ-globin, a major globin expressed in original K562 cells, was decreased. These changes in the expression of globin genes mainly took place at the transcriptional level, with significant suppression of transcription of adult (β-, δ-) globins in CCDC26-KD cells. Re-introduction of exogenous CCDC26 into the CCDC26-KD cells recovered low-level expression of the embryonal globins. These results suggest CCDC26 has a role in switching transcription of globin genes in the differentiation of erythroid cells. The expression profile of the CCDC26-KD cells and control cells suggests FOG-2, a transcriptional modulator, as a candidate for a mediator of the CCDC26-associated regulation. We showed that both embryonic globins were transcriptionally activated in FOG-2-KD K562 cells. The KIT inhibitor ISCK03 suppressed the production of hemoglobin in K562 cells but did not affect transcription of globin genes. To summarize, FOG-2, but not KIT, is responsible for globin transcriptional regulation by CCDC26.
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Affiliation(s)
- Tetsuo Hirano
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
| | - Tomomi Tsuruda
- School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan
| | - Yuka Tanaka
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan
| | - Hironori Harada
- Laboratory of Oncology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
| | - Takeshi Yamazaki
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
| | - Atsuhiko Ishida
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
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11
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Papayannopoulou T. Control of fetal globin expression in man: new opportunities to challenge past discoveries. Exp Hematol 2020; 92:43-50. [PMID: 32976950 DOI: 10.1016/j.exphem.2020.09.195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 01/01/2023]
Abstract
Decades-old findings supporting origin of F cells in adult life from adult-type progenitors and the in vitro and in vivo enhancement of fetal globin under stress conditions have been juxtaposed against recent mechanistic underpinnings. An updated molecular interrogation did not debunk prior conclusions on the origin of F cells. Although fetal globin reactivation by widely diverse approaches in vitro and in response to anemic stresses in vivo is a work in progress, accumulating evidence converges toward an integrated stress response pathway. The newly uncovered developmental regulators of globin gene switching not only have provided answers to the long-awaited quest of transregulation of switching, they are also reaching a clinical threshold. Although the effect of fetal globin silencers has been robustly validated in adult cells, the response of cells at earlier developmental stages has been unclear and inadequately studied.
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12
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Heme-regulated eIF2α kinase in erythropoiesis and hemoglobinopathies. Blood 2020; 134:1697-1707. [PMID: 31554636 DOI: 10.1182/blood.2019001915] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 09/11/2019] [Indexed: 12/12/2022] Open
Abstract
As essential components of hemoglobin, iron and heme play central roles in terminal erythropoiesis. The impairment of this process in iron/heme deficiency results in microcytic hypochromic anemia, the most prevalent anemia globally. Heme-regulated eIF2α kinase, also known as heme-regulated inhibitor (HRI), is a key heme-binding protein that senses intracellular heme concentrations to balance globin protein synthesis with the amount of heme available for hemoglobin production. HRI is activated during heme deficiency to phosphorylate eIF2α (eIF2αP), which simultaneously inhibits the translation of globin messenger RNAs (mRNAs) and selectively enhances the translation of activating transcription factor 4 (ATF4) mRNA to induce stress response genes. This coordinated translational regulation is a universal hallmark across the eIF2α kinase family under various stress conditions and is termed the integrated stress response (ISR). Inhibition of general protein synthesis by HRI-eIF2αP in erythroblasts is necessary to prevent proteotoxicity and maintain protein homeostasis in the cytoplasm and mitochondria. Additionally, the HRI-eIF2αP-ATF4 pathway represses mechanistic target of rapamycin complex 1 (mTORC1) signaling, specifically in the erythroid lineage as a feedback mechanism of erythropoietin-stimulated erythropoiesis during iron/heme deficiency. Furthermore, ATF4 target genes are most highly activated during iron deficiency to maintain mitochondrial function and redox homeostasis, as well as to enable erythroid differentiation. Thus, heme and translation regulate erythropoiesis through 2 key signaling pathways, ISR and mTORC1, which are coordinated by HRI to circumvent ineffective erythropoiesis (IE). HRI-ISR is also activated to reduce the severity of β-thalassemia intermedia in the Hbbth1/th1 murine model. Recently, HRI has been implicated in the regulation of human fetal hemoglobin production. Therefore, HRI-ISR has emerged as a potential therapeutic target for hemoglobinopathies.
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13
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Romero AM, Ramos-Alonso L, Alepuz P, Puig S, Martínez-Pastor MT. Global translational repression induced by iron deficiency in yeast depends on the Gcn2/eIF2α pathway. Sci Rep 2020; 10:233. [PMID: 31937829 PMCID: PMC6959253 DOI: 10.1038/s41598-019-57132-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/16/2019] [Indexed: 11/09/2022] Open
Abstract
Iron is an essential element for all eukaryotic organisms because it participates as a redox active cofactor in a wide range of biological processes, including protein synthesis. Translation is probably the most energy consuming process in cells. Therefore, one of the initial responses of eukaryotic cells to stress or nutrient limitation is the arrest of mRNA translation. In first instance, the budding yeast Saccharomyces cerevisiae responds to iron deficiency by activating iron acquisition and remodeling cellular metabolism in order to prioritize essential over non-essential iron-dependent processes. We have determined that, despite a global decrease in transcription, mRNA translation is actively maintained during a short-term exposure to iron scarcity. However, a more severe iron deficiency condition induces a global repression of translation. Our results indicate that the Gcn2-eIF2α pathway limits general translation at its initiation step during iron deficiency. This bulk translational inhibition depends on the uncharged tRNA sensing Gcn1-Gcn20 complex. The involvement of the Gcn2-eIF2α pathway in the response to iron deficiency highlights its central role in the eukaryotic response to stress or nutritional deprivation, which is conserved from yeast to mammals.
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Affiliation(s)
- Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Paula Alepuz
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.,ERI Biotecmed, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain.
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.
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14
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Theodorou A, Phylactides M, Katsantoni E, Vougas K, Garbis SD, Fanis P, Sitarou M, Thein SL, Kleanthous M. Proteomic Studies for the Investigation of γ-Globin Induction by Decitabine in Human Primary Erythroid Progenitor Cultures. J Clin Med 2020; 9:jcm9010134. [PMID: 31947809 PMCID: PMC7019605 DOI: 10.3390/jcm9010134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/17/2019] [Accepted: 12/26/2019] [Indexed: 11/16/2022] Open
Abstract
Reactivation of γ-globin is considered a promising approach for the treatment of β-thalassemia and sickle cell disease. Therapeutic induction of γ-globin expression, however, is fraught with lack of suitable therapeutic targets. The aim of this study was to investigate the effects that treatment with decitabine has on the proteome of human primary erythroid cells from healthy and thalassemic volunteers, as a means of identifying new potential pharmacological targets. Decitabine is a known γ-globin inducer, which is not, however, safe enough for clinical use. A proteomic approach utilizing isobaric tags for relative and absolute quantitation (iTRAQ) analysis, in combination with high-pH reverse phase peptide fractionation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), was employed to investigate the effects of decitabine treatment. Bioinformatics analysis making use of the Database for Annotation, Visualization and Integrated Discovery (DAVID) was employed for functional annotation of the 192 differentially expressed proteins identified. The data are available via ProteomeXchange with identifier PXD006889. The proteins fall into various biological pathways, such as the NF-κB signaling pathway, and into many functional categories including regulation of cell proliferation, transcription factor and DNA binding, protein stabilization, chromatin modification and organization, and oxidative stress proteins.
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Affiliation(s)
- Andria Theodorou
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Marios Phylactides
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Correspondence: ; Tel.: +357-22-392657
| | - Eleni Katsantoni
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
| | - Kostas Vougas
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
| | - Spyros D. Garbis
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
- Division for Cancer Sciences, Southampton General Hospital, University of Southampton, Southampton SO16 6YD, UK
- Centre for Proteomics Research, Institute for Life Sciences, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
| | - Pavlos Fanis
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Molecular Genetics Function and Therapy Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Maria Sitarou
- Thalassaemia Centre, Larnaca General Hospital, Larnaca 6043, Cyprus
| | - Swee Lay Thein
- Sickle cell branch, National Heart, Lung and Blood Institute, The National Institutes of Health, Bethesda, MD 20814, USA
| | - Marina Kleanthous
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
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15
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Abstract
Cell oxidative status, which represents the balance between oxidants and antioxidants, is involved in normal functions. Under pathological conditions, there is a shift toward the oxidants, leading to oxidative stress, which is cytotoxic, causing oxidation of cellular components that result in cell death and organ damage. Thalassemia is a hereditary hemolytic anemia caused by mutations in globin genes that cause reduced or complete absence of specific globin chains (commonly, α or β). Although oxidative stress is not the primary etiology of thalassemia, it mediates several of its pathologies. The main causes of oxidative stress in thalassemia are the degradation of the unstable hemoglobin and iron overload-both stimulate the production of excess free radicals. The symptoms aggravated by oxidative stress include increased hemolysis, ineffective erythropoiesis and functional failure of vital organs such as the heart and liver. The oxidative status of each patient is affected by multiple internal and external factors, including genetic makeup, health conditions, nutrition, physical activity, age, and the environment (e.g., air pollution, radiation). In addition, oxidative stress is influenced by the clinical manifestations of the disease (unpaired globin chains, iron overload, anemia, etc.). Application of personalized (theranostics) medicine principles, including diagnostic tests for selecting targeted therapy, is therefore important for optimal treatment of the oxidative stress of these patients. We summarize the role of oxidative stress and the current and potential antioxidative therapeutics in β-thalassemia and describe some methodologies, mostly cellular, that might be helpful for application of a theranostics approach to therapy.
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Affiliation(s)
- Eitan Fibach
- Department of Hematology, Hadassah-Hebrew University Medical Center, Ein-Kerem, POB 12,000, 91120, Jerusalem, Israel.
| | - Mutaz Dana
- Department of Hematology, Hadassah-Hebrew University Medical Center, Ein-Kerem, POB 12,000, 91120, Jerusalem, Israel
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16
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Oseghale AR, Zhu X, Li B, Peterson KR, Nudelman A, Rephaeli A, Xu H, Pace BS. Conjugate prodrug AN-233 induces fetal hemoglobin expression in sickle erythroid progenitors and β-YAC transgenic mice. Blood Cells Mol Dis 2019; 79:102345. [PMID: 31351219 DOI: 10.1016/j.bcmd.2019.102345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 12/24/2022]
Abstract
Pharmacologic induction of fetal hemoglobin (HbF) is an effective strategy for treating sickle cell disease (SCD) by ameliorating disease severity. Hydroxyurea is the only FDA-approved agent that induces HbF, but significant non-responders and requirement for frequent monitoring of blood counts for drug toxicity limit clinical usefulness. Therefore, we investigated a novel prodrug conjugate of butyric acid (BA) and δ-aminolevulinate (ALA) as a potential HbF inducing agent, using erythroid precursors and a preclinical β-YAC mouse model. We observed significantly increased γ-globin gene transcription and HbF expression mediated by AN-233 in K562 cells. Moreover, AN-233 stimulated mild heme biosynthesis and inhibited expression of heme-regulated eIF2α kinase involved in silencing γ-globin expression. Studies using primary erythroid precursors generated from sickle peripheral blood mononuclear cells verified the ability of AN-233 to induce HbF, increase histone H3 and H4 acetylation levels at the γ-globin promoter and reduce erythroid precursor sickling by 50%. Subsequent drug treatment of β-YAC transgenic mice confirmed HbF induction in vivo by AN-233 through an increase in the percentage of HbF positive red blood cells and HbF levels measured by flow cytometry. These data support the potential development of AN-233 for the treatment of SCD.
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Affiliation(s)
| | - Xingguo Zhu
- Department of Pediatrics, Augusta University, Augusta, GA, USA
| | - Biaoru Li
- Department of Pediatrics, Augusta University, Augusta, GA, USA
| | - Kenneth R Peterson
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | | | - Ada Rephaeli
- Felsenstein Medical Research Center, Sackler Medical School, Tel Aviv University, Petach Tikva, Israel
| | - Hongyan Xu
- Department of Population Health Sciences, Augusta University, Augusta, GA, USA
| | - Betty S Pace
- Vascular Biology Center, Augusta University, Augusta, GA, USA; Department of Pediatrics, Augusta University, Augusta, GA, USA; Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA, USA.
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17
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Tran H, Mittal A, Sagi V, Luk K, Nguyen A, Gupta M, Nguyen J, Lamarre Y, Lei J, Guedes A, Gupta K. Mast Cells Induce Blood Brain Barrier Damage in SCD by Causing Endoplasmic Reticulum Stress in the Endothelium. Front Cell Neurosci 2019; 13:56. [PMID: 30837844 PMCID: PMC6389721 DOI: 10.3389/fncel.2019.00056] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 02/05/2019] [Indexed: 12/21/2022] Open
Abstract
Endothelial dysfunction underlies the pathobiology of cerebrovascular disease. Mast cells are located in close proximity to the vasculature, and vasoactive mediators released upon their activation can promote endothelial activation leading to blood brain barrier (BBB) dysfunction. We examined the mechanism of mast cell-induced endothelial activation via endoplasmic reticulum (ER) stress mediated P-selectin expression in a transgenic mouse model of sickle cell disease (SCD), which shows BBB dysfunction. We used mouse brain endothelial cells (mBECs) and mast cells-derived from skin of control and sickle mice to examine the mechanisms involved. Compared to control mouse mast cell conditioned medium (MCCM), mBECs incubated with sickle mouse MCCM showed increased, structural disorganization and swelling of the ER and Golgi, aggregation of ribosomes, ER stress marker proteins, accumulation of galactose-1-phosphate uridyl transferase, mitochondrial dysfunction, reactive oxygen species (ROS) production, P-selectin expression and mBEC permeability. These effects of sickle-MCCM on mBEC were inhibited by Salubrinal, a reducer of ER stress. Histamine levels in the plasma, skin releasate and in mast cells of sickle mice were higher compared to control mice. Compared to control BBB permeability was increased in sickle mice. Treatment of mice with imatinib, Salubrinal, or P-selectin blocking antibody reduced BBB permeability in sickle mice. Mast cells induce endothelial dysfunction via ER stress-mediated P-selectin expression. Mast cell activation contributes to ER stress mediated endothelial P-selectin expression leading to increased endothelial permeability and impairment of BBB. Targeting mast cells and/or ER stress has the potential to ameliorate endothelial dysfunction in SCD and other pathobiologies.
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Affiliation(s)
- Huy Tran
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Aditya Mittal
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Varun Sagi
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Kathryn Luk
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Aithanh Nguyen
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Mihir Gupta
- Department of Neurosurgery, University of California, San Diego, San Diego, CA, United States
| | - Julia Nguyen
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Yann Lamarre
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Jianxun Lei
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Alonso Guedes
- Anesthesia and Pain Medicine, Veterinary Clinical Science Department, College of Veterinary Medicine, University of Minnesota Twin Cities, St. Paul, MN, United States
| | - Kalpna Gupta
- Vascular Biology Center, Division of Hematology, Oncology and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN, United States
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18
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Zanette DL, Santiago RP, Leite IPR, Santana SS, da Guarda C, Maffili VV, Ferreira JRD, Adanho CSA, Yahouedehou SCMA, Menezes IL, Goncalves MS. Differential gene expression analysis of sickle cell anemia in steady and crisis state. Ann Hum Genet 2019; 83:310-317. [PMID: 30698275 DOI: 10.1111/ahg.12290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/21/2018] [Accepted: 09/25/2018] [Indexed: 11/27/2022]
Abstract
Sickle cell anemia is one of the most prevalent genetic diseases worldwide, showing great clinical heterogeneity. This study compared the gene expression patterns between sickle cell anemia pediatric patients in steady state and in crisis state, as compared to age-paired, healthy individuals. RNA sequencing was performed from these groups of patients/controls using Illumina HiSeq 2500 equipment. The resulting differentially expressed genes were loaded into QIAGEN's ingenuity pathway analysis. The results showed that EIF2 pathway and NRF2-mediated oxidative stress-response pathways were more highly activated both in steady state and in crisis patients, as compared to healthy individuals. In addition, we found increased activation of eIF4 and p70S6K signaling pathways in crisis state compared to healthy individuals. The transcription factor GATA-1 was found exclusively in steady state while SPI was found exclusively in crisis state. IL6 and VEGFA were found only in crisis state, while IL-1B was found exclusively in steady state. The regulator effects analysis revealed IgG1 as an upstream regulator in steady state compared to healthy individuals, resulting in invasion of prostate cancer cell lines as the disease/function outcome. For crisis-state patients versus healthy individuals, two networks of regulator effects revealed STAT1, CD40LG, TGM2, IRF7, IRF4, and IRF1 acting as upstream regulators, resulting in disease/function outcomes, including engulfment of cells and aggregation of blood cells and inflammation of joints. Our results indicated genes and pathways that can provide clues on the molecular events involved in the severity of sickle cell disease.
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Affiliation(s)
- Dalila L Zanette
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil
| | - Rayra P Santiago
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil
| | - Ivana Paula Ribeiro Leite
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil.,Hospital Pediátrico Professor Hosannah de Oliveira, Universidade Federal da Bahia, Salvador, Bahia, Brazil
| | - Sanzio S Santana
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil
| | - Caroline da Guarda
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil
| | - Vitor V Maffili
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil
| | | | | | | | - Isa Lyra Menezes
- Hospital Pediátrico Professor Hosannah de Oliveira, Universidade Federal da Bahia, Salvador, Bahia, Brazil
| | - Marilda Souza Goncalves
- Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz - Fiocruz/BA, 40296710, Salvador, Bahia, Brazil.,Faculdade de Farmácia, Universidade Federal da Bahia, 40170115, Salvador, Bahia, Brasil
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19
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Grevet JD, Lan X, Hamagami N, Edwards CR, Sankaranarayanan L, Ji X, Bhardwaj SK, Face CJ, Posocco DF, Abdulmalik O, Keller CA, Giardine B, Sidoli S, Garcia BA, Chou ST, Liebhaber SA, Hardison RC, Shi J, Blobel GA. Domain-focused CRISPR screen identifies HRI as a fetal hemoglobin regulator in human erythroid cells. Science 2018; 361:285-290. [PMID: 30026227 PMCID: PMC6257981 DOI: 10.1126/science.aao0932] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 04/15/2018] [Accepted: 06/13/2018] [Indexed: 12/14/2022]
Abstract
Increasing fetal hemoglobin (HbF) levels in adult red blood cells provides clinical benefit to patients with sickle cell disease and some forms of β-thalassemia. To identify potentially druggable HbF regulators in adult human erythroid cells, we employed a protein kinase domain-focused CRISPR-Cas9-based genetic screen with a newly optimized single-guide RNA scaffold. The screen uncovered the heme-regulated inhibitor HRI (also known as EIF2AK1), an erythroid-specific kinase that controls protein translation, as an HbF repressor. HRI depletion markedly increased HbF production in a specific manner and reduced sickling in cultured erythroid cells. Diminished expression of the HbF repressor BCL11A accounted in large part for the effects of HRI depletion. Taken together, these results suggest HRI as a potential therapeutic target for hemoglobinopathies.
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Affiliation(s)
- Jeremy D Grevet
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xianjiang Lan
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Nicole Hamagami
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Christopher R Edwards
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | - Xinjun Ji
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Saurabh K Bhardwaj
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carolyne J Face
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David F Posocco
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Osheiza Abdulmalik
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Cheryl A Keller
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Belinda Giardine
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Simone Sidoli
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ben A Garcia
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stella T Chou
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Stephen A Liebhaber
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ross C Hardison
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Junwei Shi
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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20
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Abstract
Thalassemia (thal) is an autosomal recessive, hereditary, chronic hemolytic anemia due to a partial or complete deficiency in the synthesis of α-globin chains (α-thal) or β-globin chains (β-thal) that compose the major adult hemoglobin (α 2β 2). It is caused by one or more mutations in the corresponding genes. The unpaired globin chains are unstable; they precipitate intracellularly, resulting in hemolysis, premature destruction of red blood cell [RBC] precursors in the bone marrow, and a short life-span of mature RBCs in the circulation. The state of anemia is treated by frequent RBC transfusions. This therapy results in the accumulation of iron (iron overload), a condition that is exacerbated by the breakdown products of hemoglobin (heme and iron) and the increased iron uptake for the chronic accelerated, but ineffective, RBC production. Iron catalyzes the generation of reactive oxygen species, which in excess are toxic, causing damage to vital organs such as the heart and liver and the endocrine system. Herein, we review recent findings regarding the pathophysiology underlying the major symptoms of β-thal and potential therapeutic modalities for the amelioration of its complications, as well as new modalities that may provide a cure for the disease.
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Affiliation(s)
- Eitan Fibach
- Department of Hematology, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
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21
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He Y, Luo J, Chen Y, Zhou X, Yu S, Jin L, Xiao X, Jia S, Liu Q. ARHGAP18 is a novel gene under positive natural selection that influences HbF levels in β-thalassaemia. Mol Genet Genomics 2017; 293:207-216. [DOI: 10.1007/s00438-017-1377-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 09/25/2017] [Indexed: 10/18/2022]
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22
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Zhu X, Hu T, Ho MH, Wang Y, Yu M, Patel N, Pi W, Choi JH, Xu H, Ganapathy V, Kutlar F, Kutlar A, Tuan D. Hydroxyurea differentially modulates activator and repressors of γ-globin gene in erythroblasts of responsive and non-responsive patients with sickle cell disease in correlation with Index of Hydroxyurea Responsiveness. Haematologica 2017; 102:1995-2004. [PMID: 28971909 PMCID: PMC5709098 DOI: 10.3324/haematol.2017.175646] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 09/29/2017] [Indexed: 01/24/2023] Open
Abstract
Hydroxyurea (HU), the first of two drugs approved by the US Food and Drug Administration for treating patients with sickle cell disease (SCD), produces anti-sickling effect by re-activating fetal γ-globin gene to enhance production of fetal hemoglobin. However, approximately 30% of the patients do not respond to HU therapy. The molecular basis of non-responsiveness to HU is not clearly understood. To address this question, we examined HU-induced changes in the RNA and protein levels of transcription factors NF-Y, GATA-1, -2, BCL11A, TR4, MYB and NF-E4 that assemble the γ-globin promoter complex and regulate transcription of γ-globin gene. In erythroblasts cultured from peripheral blood CD34+ cells of patients with SCD, we found that HU-induced changes in the protein but not the RNA levels of activator GATA-2 and repressors GATA-1, BCL11A and TR4 correlated with HU-induced changes in fetal hemoglobin (HbF) levels in the peripheral blood of HU high and low responders. However, HU did not significantly induce changes in the protein or RNA levels of activators NF-Y and NF-E4. Based on HU-induced changes in the protein levels of GATA-2, -1 and BCL11A, we calculated an Index of Hydroxyurea Responsiveness (IndexHU-3). Compared to the HU-induced fold changes in the individual transcription factor protein levels, the numerical values of IndexHU-3 statistically correlated best with the HU-induced peripheral blood HbF levels of the patients. Thus, IndexHU-3 can serve as an appropriate indicator for inherent HU responsiveness of patients with SCD.
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Affiliation(s)
- Xingguo Zhu
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA
| | - Tianxiang Hu
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA
| | - Meng Hsuan Ho
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA.,School of Dentistry, Meharry Medical College, Nashville, TN, USA
| | - Yongchao Wang
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Miao Yu
- Georgia Cancer Research Center, Augusta University, GA, USA
| | - Niren Patel
- Division of Hematology/Oncology, Augusta University, GA, USA
| | - Wenhu Pi
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA.,Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jeong-Hyeon Choi
- Georgia Cancer Research Center, Augusta University, GA, USA.,Department of Biostatistics, Augusta University, GA, USA
| | - Hongyan Xu
- Department of Biostatistics, Augusta University, GA, USA
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA.,Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Ferdane Kutlar
- Division of Hematology/Oncology, Augusta University, GA, USA
| | - Abdullah Kutlar
- Division of Hematology/Oncology, Augusta University, GA, USA
| | - Dorothy Tuan
- Department of Biochemistry and Molecular Biology, Augusta University, GA, USA
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Makis A, Hatzimichael E, Papassotiriou I, Voskaridou E. 2017 Clinical trials update in new treatments of β-thalassemia. Am J Hematol 2016; 91:1135-1145. [PMID: 27502996 DOI: 10.1002/ajh.24530] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 07/28/2016] [Accepted: 08/05/2016] [Indexed: 01/01/2023]
Abstract
The underlying basis of β-thalassemia pathology is the diminished β-globin synthesis leading to α-globin accumulation and premature apoptotic destruction of erythroblasts, causing oxidative stress-induced ineffective erythropoiesis, bone marrow hyperplasia, splenomegaly, and increased intestinal iron absorption with progressive iron overload. Better understanding of the molecular mechanisms underlying this disease led to the recognition of new targets with potential therapeutic utility. Agents such as JAK2 inhibitors and TGF-β ligand traps that reduce the ineffective erythropoiesis process are already being tested in clinical trials with promising results. Other agents that aim to reduce oxidative stress (activators of Foxo3, HRI-eIF2aP, Prx2, Hsp70, and PK anti-oxidant systems and inhibitors of HO-1) and to decrease iron overload (hepcidin agonists, erythroferrone inhibitors and exogenous transferrin) are also under experimental investigation. Significant progress has also been made in the area of allogeneic hematopoietic stem cell transplantation with several ongoing clinical trials examining new condition regimens as well as different donor selection and stem cell source options. Gene therapy has reached a critical point and phase 1 clinical trials have recently been launched to examine the effectiveness and especially long term safety. Epigenetic manipulation and genomic editing of the γ- or β-globin gene are novel and promising experimental gene therapy approaches for β-thalassemia giving hope for cure for this chronic disease. This review outlines the key points of the molecular mechanisms underlying β-thalassemia in relation to the development of new therapies and an update is given both at the pre-clinical and clinical level. Am. J. Hematol. 91:1135-1145, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexandros Makis
- Child Health Department, Faculty of Medicine; University of Ioannina; Ioannina Greece
| | | | - Ioannis Papassotiriou
- Department of Clinical Biochemistry; “Aghia Sophia” Children's Hospital; Athens Greece
| | - Ersi Voskaridou
- Department of Clinical Biochemistry; “Aghia Sophia” Children's Hospital; Athens Greece
- “Laikon” General Hospital; Thalassemia Center; Athens Greece
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Pule GD, Mowla S, Novitzky N, Wonkam A. Hydroxyurea down-regulates BCL11A, KLF-1 and MYB through miRNA-mediated actions to induce γ-globin expression: implications for new therapeutic approaches of sickle cell disease. Clin Transl Med 2016; 5:15. [PMID: 27056246 PMCID: PMC4824700 DOI: 10.1186/s40169-016-0092-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 03/29/2016] [Indexed: 12/29/2022] Open
Abstract
Background The major therapeutic benefit of hydroxyurea, the only FDA-approved pharmacologic treatment for sickle cell disease (SCD), is directly related to fetal hemoglobin (HbF) production that leads to significant reduction of morbidity and mortality. However, potential adverse effects such as infertility, susceptibility to infections, or teratogenic effect have been subject of concerns. Therefore, understanding HU molecular mechanisms of action, could lead to alternative therapeutic agents to increase HbF with less toxicity. This paper investigated whether HU-induced HbF could operate through post-transcriptional miRNAs regulation of BCL11A, KLF-1 and MYB, potent negative regulators of HbF. Both ex vivo differentiated primary erythroid cells from seven unrelated individuals, and K562 cells were treated with hydroxyurea (100 μM) and changes in BCL11A, KLF-1, GATA-1, MYB, β- and γ-globin gene expression were investigated. To explore potential mechanisms of post-transcriptional regulation, changes in expression of seven targeted miRNAs, previously associated with basal γ-globin expression were examined using miScript primer assays. In addition, K562 cells were transfected with miScript miRNA inhibitors/anti-miRNAs followed by Western Blot analysis to assess the effect on HbF protein levels. Direct interaction between miRNAs and the MYB 3′-untranslated region (UTR) was also investigated by a dual-luciferase reporter assays. Results Down-regulation of BCL11A and MYB was associated with a sevenfold increase in γ-globin expression in both primary and K562 cells (p < 0.003). Similarly, KLF-1 was down-regulated in both cell models, corresponding to the repressed expression of BCL11A and β-globin gene (p < 0.04). HU induced differential expression of all miRNAs in both cell models, particularly miR-15a, miR-16, miR-26b and miR-151-3p. An HU-induced miRNAs-mediated mechanism of HbF regulation was illustrated with the inhibition of miR-26b and -151-3p resulting in reduced HbF protein levels. There was direct interaction between miR-26b with the MYB 3′-untranslated region (UTR). Conclusions These experiments have shown the association between critical regulators of γ-globin expression (MYB, BCL11A and KLF-1) and specific miRNAs; in response to HU, and demonstrated a mechanism of HbF production through HU-induced miRNAs inhibition of MYB. The role of miRNAs-mediated post-transcriptional regulation of HbF provides potential targets for new treatments of SCD that may minimize alterations to the cellular transcriptome. Electronic supplementary material The online version of this article (doi:10.1186/s40169-016-0092-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gift Dineo Pule
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, Republic of South Africa
| | - Shaheen Mowla
- Division of Hematology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, Republic of South Africa
| | - Nicolas Novitzky
- Division of Hematology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, Republic of South Africa
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, Republic of South Africa.
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Ward CM, Li B, Pace BS. Original Research: Stable expression of miR-34a mediates fetal hemoglobin induction in K562 cells. Exp Biol Med (Maywood) 2016; 241:719-29. [PMID: 26940952 PMCID: PMC4950382 DOI: 10.1177/1535370216636725] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sickle cell anemia is a common genetic disorder caused by a point mutation in the sixth codon of the β-globin gene affecting people of African descent worldwide. A wide variety of clinical phenotypes ranging from mild to severe symptoms and complications occur due to hemoglobin S polymerization, red blood cell sickling, and vaso-occlusion. Research efforts are ongoing to develop strategies of fetal hemoglobin (HbF; α2γ2) induction to inhibit sickle hemoglobin polymerization and improve clinical outcomes. Insights have been gained from investigating mutations in the β-globin locus or transcription factors involved in the mechanisms of hemoglobin switching. Recent efforts to expand molecular targets that modulate γ-globin expression involve microRNAs that work through posttranscriptional gene regulation. Therefore, the goal of our study was to identify novel microRNA genes involved in fetal hemoglobin expression. Using in silico analysis, we identified a miR-34a binding site in the γ-globin mRNA which was tested for functional relevance. Stable expression of the shMIMIC miR-34a lentivirus vector increased fetal hemoglobin levels in single cell K562 clones consistent with silencing of a γ-globin gene repressor. Furthermore, miR-34a promoted cell differentiation supported by increased expression of KLF1, glycophorin A, and the erythropoietin receptor. Western blot analysis of known negative regulators of γ-globin including YY1, histone deacetylase 1, and STAT3, which are regulated by miR-34a showed no change in YY1 and histone deacetylase 1 levels; however, total- and phosphorylated-STAT3 levels were decreased in single cell miR-34a K562 clones. These data support a mechanism of fetal hemoglobin activation by miR-34a involving STAT3 gene silencing.
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Affiliation(s)
- Christina M Ward
- Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA 30912, USA Department of Pediatrics, Augusta University, Augusta, GA 30912, USA
| | - Biaoru Li
- Department of Pediatrics, Augusta University, Augusta, GA 30912, USA
| | - Betty S Pace
- Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA 30912, USA Department of Pediatrics, Augusta University, Augusta, GA 30912, USA
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Rivella S. β-thalassemias: paradigmatic diseases for scientific discoveries and development of innovative therapies. Haematologica 2015; 100:418-30. [PMID: 25828088 DOI: 10.3324/haematol.2014.114827] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
β-thalassemias are monogenic disorders characterized by defective synthesis of the β-globin chain, one of the major components of adult hemoglobin. A large number of mutations in the β-globin gene or its regulatory elements have been associated with β-thalassemias. Due to the complexity of the regulation of the β-globin gene and the role of red cells in many physiological processes, patients can manifest a large spectrum of phenotypes, and clinical requirements vary from patient to patient. It is important to consider the major differences in the light of potential novel therapeutics. This review summarizes the main discoveries and mechanisms associated with the synthesis of β-globin and abnormal erythropoiesis, as well as current and novel therapies.
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Affiliation(s)
- Stefano Rivella
- Department of Pediatrics Hematology-Oncology Department of Cell and Developmental Biology Weill Cornell Medical College New York, NY, USA
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Pule GD, Mowla S, Novitzky N, Wiysonge CS, Wonkam A. A systematic review of known mechanisms of hydroxyurea-induced fetal hemoglobin for treatment of sickle cell disease. Expert Rev Hematol 2015; 8:669-79. [PMID: 26327494 DOI: 10.1586/17474086.2015.1078235] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
AIM To report on molecular mechanisms of fetal hemoglobin (HbF) induction by hydroxyurea (HU) for the treatment of sickle cell disease. STUDY DESIGN Systematic review. RESULTS Studies have provided consistent associations between genomic variations in HbF-promoting loci and variable HbF level in response to HU. Numerous signal transduction pathways have been implicated, through the identification of key genomic variants in BCL11A, HBS1L-MYB, SAR1 or XmnI polymorphism that predispose the response to the treatment, and signal transduction pathways that modulate γ-globin expression (cAMP/cGMP; Giα/c-Jun N-terminal kinase/Jun; methylation and miRNA). Three main molecular pathways have been reported: i) Epigenetic modifications, transcriptional events and signaling pathways involved in HU-mediated response, ii) Signaling pathways involving HU-mediated response and iii) Post-transcriptional pathways (regulation by miRNAs). CONCLUSIONS The complete picture of HU-mediated mechanisms of HbF production in Sickle Cell Disease remains elusive. Research on post-transcriptional mechanisms could lead to therapeutic targets that may minimize alterations to the cellular transcriptome.
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Affiliation(s)
- Gift D Pule
- a 1 Department of Medicine, Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, Republic of South Africa
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Finotti A, Bianchi N, Fabbri E, Borgatti M, Breveglieri G, Gasparello J, Gambari R. Erythroid induction of K562 cells treated with mithramycin is associated with inhibition of raptor gene transcription and mammalian target of rapamycin complex 1 (mTORC1) functions. Pharmacol Res 2014; 91:57-68. [PMID: 25478892 PMCID: PMC4309890 DOI: 10.1016/j.phrs.2014.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/21/2014] [Accepted: 11/24/2014] [Indexed: 12/21/2022]
Abstract
Rapamycin, an inhibitor of mTOR activity, is a potent inducer of erythroid differentiation and fetal hemoglobin production in β-thalassemic patients. Mithramycin (MTH) was studied to see if this inducer of K562 differentiation also operates through inhibition of mTOR. We can conclude from the study that the mTOR pathway is among the major transcript classes affected by mithramycin-treatment in K562 cells and a sharp decrease of raptor protein production and p70S6 kinase is detectable in mithramycin treated K562 cells. The promoter sequence of the raptor gene contains several Sp1 binding sites which may explain its mechanism of action. We hypothesize that the G + C-selective DNA-binding drug mithramycin is able to interact with these sequences and to inhibit the binding of Sp1 to the raptor promoter due to the following results: (a) MTH strongly inhibits the interactions between Sp1 and Sp1-binding sites of the raptor promoter (studied by electrophoretic mobility shift assays, EMSA); (b) MTH strongly reduces the recruitment of Sp1 transcription factor to the raptor promoter in intact K562 cells (studied by chromatin immunoprecipitation experiments, ChIP); (c) Sp1 decoy oligonucleotides are able to specifically inhibit raptor mRNA accumulation in K562 cells. In conclusion, raptor gene expression is involved in mithramycin-mediated induction of erythroid differentiation of K562 cells and one of its mechanism of action is the inhibition of Sp1 binding to the raptor promoter.
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Affiliation(s)
- Alessia Finotti
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Nicoletta Bianchi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Enrica Fabbri
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Monica Borgatti
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Giulia Breveglieri
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Jessica Gasparello
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy.
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