1
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Menon V, Slavinsky M, Hermine O, Ghaffari S. Mitochondrial regulation of erythropoiesis in homeostasis and disease. Br J Haematol 2024. [PMID: 38946206 DOI: 10.1111/bjh.19600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 06/06/2024] [Indexed: 07/02/2024]
Abstract
Erythroid cells undergo a highly complex maturation process, resulting in dynamic changes that generate red blood cells (RBCs) highly rich in haemoglobin. The end stages of the erythroid cell maturation process primarily include chromatin condensation and nuclear polarization, followed by nuclear expulsion called enucleation and clearance of mitochondria and other organelles to finally generate mature RBCs. While healthy RBCs are devoid of mitochondria, recent evidence suggests that mitochondria are actively implicated in the processes of erythroid cell maturation, erythroblast enucleation and RBC production. However, the extent of mitochondrial participation that occurs during these ultimate steps is not completely understood. This is specifically important since abnormal RBC retention of mitochondria or mitochondrial DNA contributes to the pathophysiology of sickle cell and other disorders. Here we review some of the key findings so far that elucidate the importance of this process in various aspects of erythroid maturation and RBC production under homeostasis and disease conditions.
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Affiliation(s)
- Vijay Menon
- Department of Cell, Developmental & Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Mary Slavinsky
- Department of Cell, Developmental & Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Olivier Hermine
- Department Hematology, Hôpital Necker, Assistance Publique Hôpitaux de Paris, University Paris Descartes, Paris, France
- INSERM U1163 and CNRS 8254, Imagine Institute, Université Sorbonne Paris Cité, Paris, France
| | - Saghi Ghaffari
- Department of Cell, Developmental & Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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2
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Myers G, Sun Y, Wang Y, Benmhammed H, Cui S. Roles of Nuclear Orphan Receptors TR2 and TR4 during Hematopoiesis. Genes (Basel) 2024; 15:563. [PMID: 38790192 PMCID: PMC11121135 DOI: 10.3390/genes15050563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/26/2024] Open
Abstract
TR2 and TR4 (NR2C1 and NR2C2, respectively) are evolutionarily conserved nuclear orphan receptors capable of binding direct repeat sequences in a stage-specific manner. Like other nuclear receptors, TR2 and TR4 possess important roles in transcriptional activation or repression with developmental stage and tissue specificity. TR2 and TR4 bind DNA and possess the ability to complex with available cofactors mediating developmental stage-specific actions in primitive and definitive erythrocytes. In erythropoiesis, TR2 and TR4 are required for erythroid development, maturation, and key erythroid transcription factor regulation. TR2 and TR4 recruit and interact with transcriptional corepressors or coactivators to elicit developmental stage-specific gene regulation during hematopoiesis.
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Affiliation(s)
- Greggory Myers
- Departments of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; (G.M.); (Y.W.)
| | - Yanan Sun
- Section of Hematology-Medical Oncology, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston Medical Center, Boston, MA 02118, USA; (Y.S.); (H.B.)
| | - Yu Wang
- Departments of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; (G.M.); (Y.W.)
| | - Hajar Benmhammed
- Section of Hematology-Medical Oncology, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston Medical Center, Boston, MA 02118, USA; (Y.S.); (H.B.)
| | - Shuaiying Cui
- Section of Hematology-Medical Oncology, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston Medical Center, Boston, MA 02118, USA; (Y.S.); (H.B.)
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3
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Pavan AR, Lopes JR, Dos Santos JL. The state of the art of fetal hemoglobin-inducing agents. Expert Opin Drug Discov 2022; 17:1279-1293. [PMID: 36302760 DOI: 10.1080/17460441.2022.2141708] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
INTRODUCTION Sickle cell anemia (SCA) is a hematological genetic disorder caused by a mutation in the gene of the β-globin. Pharmacological treatments will continue to be an important approach, including the strategy to induce fetal hemoglobin (HbF). AREAS COVERED Here, we analyzed the articles described in the literature regarding the drug discovery of HbF inducers. The main approaches for such strategy will be discussed, highlighting those most promising. EXPERT OPINION The comprehension of the mechanisms involved in the β-globin regulation is the main key to design new drugs to induce HbF. Among the strategies, gamma-globin regulation by epigenetic enzymes seems to be a promising approach to be pursued, although the comprehension of the selectivity role for those new drugs is crucial to reduce adverse effects. The low druggability of transcription factors and their vital role in embryonic human development are critical points that should be taken in account for drug design. The guanylate cyclase and the NO/cGMP signaling pathway seem to be promising not only for HbF induction, but also for the protective effects in the cardiovascular system. The association of drugs acting through different mechanisms to induce HbF seems to be promising for the discovery of new drugs.
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Affiliation(s)
- Aline Renata Pavan
- São Paulo State University (UNESP), Institute of Chemistry, Araraquara, Brazil
| | - Juliana Romano Lopes
- School of Pharmaceutical Sciences, São Paulo State University (UNESP), Drugs and Medicine Department, Araraquara, Brazil
| | - Jean Leandro Dos Santos
- São Paulo State University (UNESP), Institute of Chemistry, Araraquara, Brazil.,School of Pharmaceutical Sciences, São Paulo State University (UNESP), Drugs and Medicine Department, Araraquara, Brazil
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4
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Sun Y, Habara A, Le CQ, Nguyen N, Chen R, Murphy GJ, Chui DHK, Steinberg MH, Cui S. Pharmacologic induction of PGC-1α stimulates fetal haemoglobin gene expression. Br J Haematol 2022; 197:97-109. [PMID: 35118652 DOI: 10.1111/bjh.18042] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/31/2021] [Accepted: 01/02/2022] [Indexed: 12/13/2022]
Abstract
Sickle cell disease (SCD) is a genetic disorder that affects millions around the world. Enhancement of fetal γ-globin levels and fetal haemoglobin (HbF) production in SCD patients leads to diminished severity of many clinical features of the disease. We recently identified the transcriptional co-activator PGC-1α as a new protein involved in the regulation of the globin genes. Here, we report that upregulation of PGC-1α by infection with a lentivirus expressing PGC-1α or by the small-molecule PGC-1α agonist ZLN005 in human primary erythroid progenitor CD34+ cells induces both fetal γ-globin mRNA and protein expression as well as the percentage of HbF-positive cell (F cells) without significantly affecting cell proliferation and differentiation. We further found that the combination of ZLN005 and hydroxyurea (hydroxycarbamide) exhibited an additive effect on the expression of γ-globin and the generation of F cells from cultured CD34+ cells. In addition, ZLN005 induced robust expression of the murine embryonic βh1-globin gene and to a lesser extent, human γ-globin gene expression in sickle mice. These findings suggest that activation of PGC-1α by ZLN005 might provide a new path for modulating HbF levels with potential therapeutic benefit in β-hemoglobinopathies.
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Affiliation(s)
- Yanan Sun
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA
| | - Alawi Habara
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA.,Department of Clinical Biochemistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Cuong Quang Le
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA
| | - Nicole Nguyen
- Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, Massachusetts, USA
| | - Raymon Chen
- Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, Massachusetts, USA
| | - George J Murphy
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA.,Center for Regenerative Medicine, Boston University, Boston Medical Center, Boston, Massachusetts, USA
| | - David H K Chui
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA
| | - Martin H Steinberg
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA
| | - Shuaiying Cui
- Department of Medicine, Section of Hematology-Medical Oncology, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts, USA
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Decreased PGC1β expression results in disrupted human erythroid differentiation, impaired hemoglobinization and cell cycle exit. Sci Rep 2021; 11:17129. [PMID: 34429458 PMCID: PMC8385110 DOI: 10.1038/s41598-021-96585-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 08/10/2021] [Indexed: 11/08/2022] Open
Abstract
Production of red blood cells relies on proper mitochondrial function, both for their increased energy demands during differentiation and for proper heme and iron homeostasis. Mutations in genes regulating mitochondrial function have been reported in patients with anemia, yet their pathophysiological role often remains unclear. PGC1β is a critical coactivator of mitochondrial biogenesis, with increased expression during terminal erythroid differentiation. The role of PGC1β has however mainly been studied in skeletal muscle, adipose and hepatic tissues, and its function in erythropoiesis remains largely unknown. Here we show that perturbed PGC1β expression in human hematopoietic stem/progenitor cells from both bone marrow and cord blood results in impaired formation of early erythroid progenitors and delayed terminal erythroid differentiation in vitro, with accumulations of polychromatic erythroblasts, similar to MDS-related refractory anemia. Reduced levels of PGC1β resulted in deregulated expression of iron, heme and globin related genes in polychromatic erythroblasts, and reduced hemoglobin content in the more mature bone marrow derived reticulocytes. Furthermore, PGC1β knock-down resulted in disturbed cell cycle exit with accumulation of erythroblasts in S-phase and enhanced expression of G1-S regulating genes, with smaller reticulocytes as a result. Taken together, we demonstrate that PGC1β is directly involved in production of hemoglobin and regulation of G1-S transition and is ultimately required for proper terminal erythroid differentiation.
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6
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Heart failure and the glutathione cycle: an integrated view. Biochem J 2021; 477:3123-3130. [PMID: 32886767 DOI: 10.1042/bcj20200429] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 12/15/2022]
Abstract
Heart failure results from the heart's inability to carryout ventricular contraction and relaxation, and has now become a worldwide problem. During the onset of heart failure, several signatures are observed in cardiomyocytes that includes fetal reprogramming of gene expression where adult genes are repressed and fetal genes turned on, endoplasmic reticulum stress and oxidative stress. In this short review and analysis, we examine these different phenomenon from the viewpoint of the glutathione cycle and the role of the recently discovered Chac1 enzyme. Chac1, which belongs to the family of γ-glutamylcyclotransferases, is a recently discovered member of the glutathione cycle, being involved in the cytosolic degradation of glutathione. This enzyme is induced during the Endoplasmic Stress response, but also in the developing heart. Owing to its exclusive action on reduced glutathione, its induction leads to an increase in the oxidative redox potential of the cell that also serves as signaling mechanism for calcium ions channel activation. The end product of Chac1 action is 5-oxoproline, and studies with 5-oxoprolinase (OPLAH), an enzyme of the glutathione cycle has revealed that down-regulation of OPLAH can lead to the accumulation of 5-oxproline which is an important factor in heart failure. With these recent findings, we have re-examined the roles and regulation of the enzymes in the glutathione cycle which are central to these responses. We present an integrated view of the glutathione cycle in the cellular response to heart failure.
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7
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Sánchez-de-Diego C, Pedrazza L, Pimenta-Lopes C, Martinez-Martinez A, Dahdah N, Valer JA, Garcia-Roves P, Rosa JL, Ventura F. NRF2 function in osteocytes is required for bone homeostasis and drives osteocytic gene expression. Redox Biol 2020; 40:101845. [PMID: 33373776 PMCID: PMC7773566 DOI: 10.1016/j.redox.2020.101845] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022] Open
Abstract
Osteocytes, the most abundant bone cell type, are derived from osteoblasts through a process in which they are embedded in an osteoid. We previously showed that nutrient restriction promotes the osteocyte transcriptional program and is associated with increased mitochondrial biogenesis. Here, we show that increased mitochondrial biogenesis increase reactive oxygen species (ROS) levels and consequently, NRF2 activity during osteocytogenesis. NRF2 activity promotes osteocyte-specific expression of Dmp1, Mepe, and Sost in IDG-SW3 cells, primary osteocytes, and osteoblasts, and in murine models with Nfe2l2 deficiency in osteocytes or osteoblasts. Moreover, ablation of Nfe2l2 in osteocytes or osteoblasts generates osteopenia and increases osteoclast numbers with marked sexual dimorphism. Finally, treatment with dimethyl fumarate prevented the deleterious effects of ovariectomy in trabecular bone masses of mice and restored osteocytic gene expression. Altogether, we uncovered the role of NRF2 activity in osteocytes during the regulation of osteocyte gene expression and maintenance of bone homeostasis. ROS levels and NRF2 activity are increased during osteocytogenesis. NRF2 drives osteocyte specification and activate the transcription of osteocyte-specific genes. NRF2 in osteocytes has a fundamental role in bone homeostasis and its deletion induces osteopenia. Activation of NRF2 with dimethyl fumarate prevents osteopenia induced by ovariectomy.
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Affiliation(s)
- Cristina Sánchez-de-Diego
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Leonardo Pedrazza
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Carolina Pimenta-Lopes
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Arturo Martinez-Martinez
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Norma Dahdah
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - José Antonio Valer
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Pablo Garcia-Roves
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Jose Luis Rosa
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain.
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8
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Packer M. Cardioprotective Effects of Sirtuin-1 and Its Downstream Effectors: Potential Role in Mediating the Heart Failure Benefits of SGLT2 (Sodium-Glucose Cotransporter 2) Inhibitors. Circ Heart Fail 2020; 13:e007197. [PMID: 32894987 DOI: 10.1161/circheartfailure.120.007197] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The cardioprotective effects of SGLT2 (sodium-glucose cotransporter 2) inhibitors may be related to their ability to induce a fasting-like paradigm, which triggers the activation of nutrient deprivation pathways to promote cellular homeostasis. The most distinctive metabolic manifestations of this fasting mimicry are enhanced gluconeogenesis and ketogenesis, which are not seen with other antihyperglycemic drugs. The principal molecular stimulus to gluconeogenesis and ketogenesis is activation of SIRT1 (sirtuin-1) and its downstream mediators: PGC-1α (proliferator-activated receptor gamma coactivator 1-alpha) and FGF21 (fibroblast growth factor 21). These three nutrient deprivation sensors exert striking cardioprotective effects in a broad range of experimental models. This benefit appears to be related to their actions to alleviate oxidative stress and promote autophagy-a lysosome-dependent degradative pathway that disposes of dysfunctional organelles that are major sources of cellular injury. Nutrient deprivation sensors are suppressed in states of perceived energy surplus (ie, type 2 diabetes mellitus and chronic heart failure), but SGLT2 inhibitors activate SIRT1/PGC-1α/FGF21 signaling and promote autophagy. This effect may be related to their action to trigger the perception of a system-wide decrease in environmental nutrients, but SGLT2 inhibitors may also upregulate SIRT1, PGC-1α, and FGF21 by a direct effect on the heart. Interestingly, metformin-induced stimulation of AMP-activated protein kinase (a nutrient deprivation sensor that does not promote ketogenesis) has not been shown to reduce heart failure events in clinical trials. Therefore, promotion of ketogenic nutrient deprivation signaling by SGLT2 inhibitors may explain their cardioprotective effects, even though SGLT2 is not expressed in the heart.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, TX;and Imperial College, London, United Kingdom
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9
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Packer M. Role of ketogenic starvation sensors in mediating the renal protective effects of SGLT2 inhibitors in type 2 diabetes. J Diabetes Complications 2020; 34:107647. [PMID: 32534886 DOI: 10.1016/j.jdiacomp.2020.107647] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/15/2020] [Accepted: 05/28/2020] [Indexed: 02/08/2023]
Abstract
Sodium-glucose cotransporter 2 (SGLT2) inhibitors ameliorate the progression of diabetic chronic kidney disease, but the mechanisms underlying this nephroprotective effect have not been fully elucidated. These drugs induce a fasting-like transcriptional paradigm, which includes activation of sirtuin-1 (SIRT1) and its downstream effectors, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and fibroblast growth factor 21 (FGF21). This triad of enzymes and transcription factors serve as master regulators of nutrient and cellular homeostasis, and each acts to enhance gluconeogenesis, fatty acid oxidation and ketogenesis, the hallmarks of treatment with SGLT2 inhibitors. At the same time, SIRT1/PGC-1α/FGF21 signaling also promotes autophagy, a lysosome-dependent degradative pathway that cleanses the cytosol of dysfunctional organelles. This action alleviates cellular stress, ameliorates inflammation, and is strikingly nephroprotective. Interestingly, type 2 diabetes is characterized by both a deficiency of SIRT1/PGC-1α signaling and an impairment of autophagic flux, thus explaining the high levels of oxidative stress in the diabetic kidney. SIRT1 gene polymorphisms have been linked with an increased risk of diabetic nephropathy in several epidemiological studies. Importantly, there is an inverse relationship between the activity of SGLT2 and signaling through the SIRT1/PGC-1α/FGF21 pathway, and SGLT2 inhibition leads to activation of these ketogenic nutrient deprivation sensors. Therefore, activation of SIRT1/PGC-1α/FGF21 may explain the effect of SGLT2 inhibitors not only to promote ketogenesis, but also to preserve renal function in type 2 diabetes.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, TX, USA; Imperial College, London, UK.
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10
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La P, Oved JH, Ghiaccio V, Rivella S. Mitochondria Biogenesis Modulates Iron-Sulfur Cluster Synthesis to Increase Cellular Iron Uptake. DNA Cell Biol 2020; 39:756-765. [PMID: 32282232 DOI: 10.1089/dna.2019.5123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Iron-sulfur (Fe-S) clusters are required for mitochondrial function. Fe-S cluster synthesis occurs in the mitochondria and iron uptake is required for mitochondrial biogenesis. However, Fe-S clusters inhibit the expression of the iron importer transferrin receptor 1 (TfR1), whereas lack of the Fe-S cluster stimulates TfR1 expression. Yet, it is unclear whether Fe-S cluster synthesis increases with mitochondria biogenesis and, in turn, whether this negatively modulates TfR1 expression. We manipulated peroxisome proliferator-activated receptor-gamma coactivator-1α expression to control mitochondrial biogenesis in a variety of cell types, including erythroid cells. We demonstrated that Fe-S cluster synthesis increases with mitochondria biogenesis but does not interfere with increasing TfR1 expression. In fact, TfR1 expression is stimulated through alternative means to meet iron requirement for mitochondria biogenesis. Furthermore, under enhanced mitochondria biogenesis, increased Fe-S cluster synthesis inhibits the function of iron-regulating protein (IRP)1 and hence stimulates the expression of 5'-aminolevulinate synthase 2 (ALAS2), a target of IRP1 and rate-limiting enzyme in erythroid heme biogenesis. Increased ALAS2 expression leads to enhanced heme production, hemoglobinization, and erythropoiesis. Therefore, our study also provides a mechanism to link mitochondrial biogenesis with erythropoiesis and has a potential therapeutic value in the treatment of blood disorders.
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Affiliation(s)
- Ping La
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph H Oved
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Cell Therapy and Transplant Section, Division of Oncology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Valentina Ghiaccio
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stefano Rivella
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Cell and Molecular Biology Affinity Group (CAMB)-Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Penn Center for Musculoskeletal Disorders, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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11
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Glucose Restriction Promotes Osteocyte Specification by Activating a PGC-1α-Dependent Transcriptional Program. iScience 2019; 15:79-94. [PMID: 31039455 PMCID: PMC6488568 DOI: 10.1016/j.isci.2019.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 01/16/2019] [Accepted: 04/08/2019] [Indexed: 12/16/2022] Open
Abstract
Osteocytes, the most abundant of bone cells, differentiate while they remain buried within the bone matrix. This encasement limits their access to nutrients and likely affects their differentiation, a process that remains poorly defined. Here, we show that restriction in glucose supply promotes the osteocyte transcriptional program while also being associated with increased mitochondrial DNA levels. Glucose deprivation triggered the activation of the AMPK/PGC-1 pathway. AMPK and SIRT1 activators or PGC-1α overexpression are sufficient to enhance osteocyte gene expression in IDG-SW3 cells, murine primary osteoblasts, osteocytes, and organotypic/ex vivo bone cultures. Conversely, osteoblasts and osteocytes deficient in Ppargc1a and b were refractory to the effects of glucose restriction. Finally, conditional ablation of both genes in osteoblasts and osteocytes generate osteopenia and reduce osteocytic gene expression in mice. Altogether, we uncovered a role for PGC-1 in the regulation of osteocyte gene expression.
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12
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Yu L, Jearawiriyapaisarn N, Lee MP, Hosoya T, Wu Q, Myers G, Lim KC, Kurita R, Nakamura Y, Vojtek AB, Rual JF, Engel JD. BAP1 regulation of the key adaptor protein NCoR1 is critical for γ-globin gene repression. Genes Dev 2018; 32:1537-1549. [PMID: 30463901 PMCID: PMC6295165 DOI: 10.1101/gad.318436.118] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/02/2018] [Indexed: 12/31/2022]
Abstract
Human globin gene production transcriptionally "switches" from fetal to adult synthesis shortly after birth and is controlled by macromolecular complexes that enhance or suppress transcription by cis elements scattered throughout the locus. The DRED (direct repeat erythroid-definitive) repressor is recruited to the ε-globin and γ-globin promoters by the orphan nuclear receptors TR2 (NR2C1) and TR4 (NR2C2) to engender their silencing in adult erythroid cells. Here we found that nuclear receptor corepressor-1 (NCoR1) is a critical component of DRED that acts as a scaffold to unite the DNA-binding and epigenetic enzyme components (e.g., DNA methyltransferase 1 [DNMT1] and lysine-specific demethylase 1 [LSD1]) that elicit DRED function. We also describe a potent new regulator of γ-globin repression: The deubiquitinase BRCA1-associated protein-1 (BAP1) is a component of the repressor complex whose activity maintains NCoR1 at sites in the β-globin locus, and BAP1 inhibition in erythroid cells massively induces γ-globin synthesis. These data provide new mechanistic insights through the discovery of novel epigenetic enzymes that mediate γ-globin gene repression.
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Affiliation(s)
- Lei Yu
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Natee Jearawiriyapaisarn
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Mary P Lee
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Tomonori Hosoya
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Qingqing Wu
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Greggory Myers
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Kim-Chew Lim
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Ryo Kurita
- Cell Engineering Division, RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan
| | - Yukio Nakamura
- Cell Engineering Division, RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan
| | - Anne B Vojtek
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Jean-François Rual
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - James Douglas Engel
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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13
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Chambers JM, Poureetezadi SJ, Addiego A, Lahne M, Wingert RA. ppargc1a controls nephron segmentation during zebrafish embryonic kidney ontogeny. eLife 2018; 7:40266. [PMID: 30475208 PMCID: PMC6279350 DOI: 10.7554/elife.40266] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/23/2018] [Indexed: 02/06/2023] Open
Abstract
Nephron segmentation involves a concert of genetic and molecular signals that are not fully understood. Through a chemical screen, we discovered that alteration of peroxisome proliferator-activated receptor (PPAR) signaling disrupts nephron segmentation in the zebrafish embryonic kidney (Poureetezadi et al., 2016). Here, we show that the PPAR co-activator ppargc1a directs renal progenitor fate. ppargc1a mutants form a small distal late (DL) segment and an expanded proximal straight tubule (PST) segment. ppargc1a promotes DL fate by regulating the transcription factor tbx2b, and restricts expression of the transcription factor sim1a to inhibit PST fate. Interestingly, sim1a restricts ppargc1a expression to promote the PST, and PST development is fully restored in ppargc1a/sim1a-deficient embryos, suggesting Ppargc1a and Sim1a counterbalance each other in an antagonistic fashion to delineate the PST segment boundary during nephrogenesis. Taken together, our data reveal new roles for Ppargc1a during development, which have implications for understanding renal birth defects.
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Affiliation(s)
- Joseph M Chambers
- Department of Biological Sciences, University of Notre Dame, Indiana, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Indiana, United States.,Center for Zebrafish Research, University of Notre Dame, Indiana, United States
| | - Shahram Jevin Poureetezadi
- Department of Biological Sciences, University of Notre Dame, Indiana, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Indiana, United States.,Center for Zebrafish Research, University of Notre Dame, Indiana, United States
| | - Amanda Addiego
- Department of Biological Sciences, University of Notre Dame, Indiana, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Indiana, United States.,Center for Zebrafish Research, University of Notre Dame, Indiana, United States
| | - Manuela Lahne
- Department of Biological Sciences, University of Notre Dame, Indiana, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Indiana, United States.,Center for Zebrafish Research, University of Notre Dame, Indiana, United States
| | - Rebecca A Wingert
- Department of Biological Sciences, University of Notre Dame, Indiana, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Indiana, United States.,Center for Zebrafish Research, University of Notre Dame, Indiana, United States
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14
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Habara AH, Shaikho EM, Steinberg MH. Fetal hemoglobin in sickle cell anemia: The Arab-Indian haplotype and new therapeutic agents. Am J Hematol 2017; 92:1233-1242. [PMID: 28736939 PMCID: PMC5647233 DOI: 10.1002/ajh.24872] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/18/2017] [Accepted: 07/21/2017] [Indexed: 12/28/2022]
Abstract
Fetal hemoglobin (HbF) has well-known tempering effects on the symptoms of sickle cell disease and its levels vary among patients with different haplotypes of the sickle hemoglobin gene. Compared with sickle cell anemia haplotypes found in patients of African descent, HbF levels in Saudi and Indian patients with the Arab-Indian (AI) haplotype exceed that in any other haplotype by nearly twofold. Genetic association studies have identified some loci associated with high HbF in the AI haplotype but these observations require functional confirmation. Saudi patients with the Benin haplotype have HbF levels almost twice as high as African patients with this haplotype but this difference is unexplained. Hydroxyurea is still the only FDA approved drug for HbF induction in sickle cell disease. While most patients treated with hydroxyurea have an increase in HbF and some clinical improvement, 10 to 20% of adults show little response to this agent. We review the genetic basis of HbF regulation focusing on sickle cell anemia in Saudi Arabia and discuss new drugs that can induce increased levels of HbF.
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Affiliation(s)
- Alawi H Habara
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Elmutaz M Shaikho
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Martin H Steinberg
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, 02118
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15
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Zamora M, Pardo R, Villena JA. Pharmacological induction of mitochondrial biogenesis as a therapeutic strategy for the treatment of type 2 diabetes. Biochem Pharmacol 2015. [PMID: 26212547 DOI: 10.1016/j.bcp.2015.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Defects in mitochondrial oxidative function have been associated with the onset of type 2 diabetes. Although the causal relationship between mitochondrial dysfunction and diabetes has not been fully established, numerous studies indicate that improved glucose homeostasis achieved via lifestyle interventions, such as exercise or calorie restriction, is tightly associated with increased mitochondrial biogenesis and oxidative function. Therefore, it is conceivable that potentiating mitochondrial biogenesis by pharmacological means could constitute an efficacious therapeutic strategy that would particularly benefit those diabetic patients who cannot adhere to comprehensive programs based on changes in lifestyle or that require a relatively rapid improvement in their diabetic status. In this review, we discuss several pharmacological targets and drugs that modulate mitochondrial biogenesis as well as their potential use as treatments for insulin resistance and diabetes.
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Affiliation(s)
- Mònica Zamora
- Cell Biology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, CIBER on Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - Rosario Pardo
- Laboratory of Metabolism and Obesity, Vall d'Hebron-Institut de Recerca, Universitat Autònoma de Barcelona, CIBER on Diabetes and Associated Metabolic Diseases (CIBERDEM), Barcelona, Spain
| | - Josep A Villena
- Laboratory of Metabolism and Obesity, Vall d'Hebron-Institut de Recerca, Universitat Autònoma de Barcelona, CIBER on Diabetes and Associated Metabolic Diseases (CIBERDEM), Barcelona, Spain.
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16
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Blobel GA, Bodine D, Brand M, Crispino J, de Bruijn MFTR, Nathan D, Papayannopoulou T, Porcher C, Strouboulis J, Zon L, Higgs DR, Stamatoyannopoulos G, Engel JD. An international effort to cure a global health problem: A report on the 19th Hemoglobin Switching Conference. Exp Hematol 2015; 43:821-37. [PMID: 26143582 DOI: 10.1016/j.exphem.2015.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 06/04/2015] [Accepted: 06/05/2015] [Indexed: 12/24/2022]
Abstract
Every 2 years since 1978, an international group of scientists, physicians, and other researchers meet to discuss the latest developments in the underlying etiology, mechanisms of action, and developmental acquisition of cellular and systemic defects exhibited and elicited by the most common inherited human disorders, the hemoglobinopathies. The 19th Hemoglobin Switching Conference, held in September 2014 at St. John's College in Oxford, once again exceeded all expectations by describing cutting edge research in cellular, molecular, developmental, and genomic advances focused on these diseases. The conference comprised about 60 short talks over 3 days by leading investigators in the field. This meeting report describes the highlights of the conference.
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Affiliation(s)
- Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David Bodine
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Marjorie Brand
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - John Crispino
- Division of Hematology/Oncology, Robert H Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA
| | - Marella F T R de Bruijn
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital University of Oxford, Oxford, UK; BRC Blood Theme, NIHR Oxford Biomedical Centre, Oxford University Hospital, Oxford, UK
| | - David Nathan
- Division of Hematology and Oncology, Boston Children's Hospital, Departments of Pediatrics and Medicine, Harvard Medical School, Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | | | - Catherine Porcher
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital University of Oxford, Oxford, UK; BRC Blood Theme, NIHR Oxford Biomedical Centre, Oxford University Hospital, Oxford, UK
| | - John Strouboulis
- Division of Molecular Oncology, Biomedical Sciences Research Center "Alexander Fleming", Vari, Greece
| | - Len Zon
- Boston Children's Hospital/HHMI, Boston, MA, USA
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital University of Oxford, Oxford, UK; BRC Blood Theme, NIHR Oxford Biomedical Centre, Oxford University Hospital, Oxford, UK
| | | | - James Douglas Engel
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.
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17
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Raval A, Behbehani GK, Nguyen LXT, Thomas D, Kusler B, Garbuzov A, Ramunas J, Holbrook C, Park CY, Blau H, Nolan GP, Artandi SE, Mitchell BS. Reversibility of Defective Hematopoiesis Caused by Telomere Shortening in Telomerase Knockout Mice. PLoS One 2015; 10:e0131722. [PMID: 26133370 PMCID: PMC4489842 DOI: 10.1371/journal.pone.0131722] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/04/2015] [Indexed: 01/08/2023] Open
Abstract
Telomere shortening is common in bone marrow failure syndromes such as dyskeratosis congenita (DC), aplastic anemia (AA) and myelodysplastic syndromes (MDS). However, improved knowledge of the lineage-specific consequences of telomere erosion and restoration of telomere length in hematopoietic progenitors is required to advance therapeutic approaches. We have employed a reversible murine model of telomerase deficiency to compare the dependence of erythroid and myeloid lineage differentiation on telomerase activity. Fifth generation Tert-/- (G5 Tert-/-) mice with shortened telomeres have significant anemia, decreased erythroblasts and reduced hematopoietic stem cell (HSC) populations associated with neutrophilia and increased myelopoiesis. Intracellular multiparameter analysis by mass cytometry showed significantly reduced cell proliferation and increased sensitivity to activation of DNA damage checkpoints in erythroid progenitors and in erythroid-biased CD150hi HSC, but not in myeloid progenitors. Strikingly, Cre-inducible reactivation of telomerase activity restored hematopoietic stem and progenitor cell (HSPC) proliferation, normalized the DNA damage response, and improved red cell production and hemoglobin levels. These data establish a direct link between the loss of TERT activity, telomere shortening and defective erythropoiesis and suggest that novel strategies to restore telomerase function may have an important role in the treatment of the resulting anemia.
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Affiliation(s)
- Aparna Raval
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Gregory K. Behbehani
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
| | - Le Xuan Truong Nguyen
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Daniel Thomas
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Brenda Kusler
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Alina Garbuzov
- Department of Genetics, Stanford University, Stanford, CA, 94305, United States of America
| | - John Ramunas
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Colin Holbrook
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Christopher Y. Park
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, United States of America
| | - Helen Blau
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Garry P. Nolan
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
| | - Steven E. Artandi
- Departments of Medicine and Biochemistry, Stanford University, Stanford, CA, 94305, United States of America
| | - Beverly S. Mitchell
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- * E-mail:
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18
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The LSD1 inhibitor RN-1 induces fetal hemoglobin synthesis and reduces disease pathology in sickle cell mice. Blood 2015; 126:386-96. [PMID: 26031919 DOI: 10.1182/blood-2015-02-626259] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 05/22/2015] [Indexed: 12/30/2022] Open
Abstract
Inhibition of lysine-specific demethylase 1 (LSD1) has been shown to induce fetal hemoglobin (HbF) levels in cultured human erythroid cells in vitro. Here we report the in vivo effects of LSD1 inactivation by a selective and more potent inhibitor, RN-1, in a sickle cell disease (SCD) mouse model. Compared with untreated animals, RN-1 administration leads to induced HbF synthesis and to increased frequencies of HbF-positive cells and mature erythrocytes, as well as fewer reticulocytes and sickle cells, in the peripheral blood of treated SCD mice. In keeping with these observations, histologic analyses of the liver and spleen of treated SCD mice verified that they do not exhibit the necrotic lesions that are usually associated with SCD. These data indicate that RN-1 can effectively induce HbF levels in red blood cells and reduce disease pathology in SCD mice, and may therefore offer new therapeutic possibilities for treating SCD.
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19
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Villena JA. New insights into PGC-1 coactivators: redefining their role in the regulation of mitochondrial function and beyond. FEBS J 2015; 282:647-72. [DOI: 10.1111/febs.13175] [Citation(s) in RCA: 252] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/31/2014] [Accepted: 12/10/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Josep A. Villena
- Laboratory of Metabolism and Obesity; Vall d'Hebron-Institut de Recerca; Universitat Autònoma de Barcelona; Spain
- CIBERDEM (CIBER de Diabetes y Enfermedades Metabólicas Asociadas); Instituto de Salud Carlos III; Barcelona Spain
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20
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Compound loss of function of nuclear receptors Tr2 and Tr4 leads to induction of murine embryonic β-type globin genes. Blood 2015; 125:1477-87. [PMID: 25561507 DOI: 10.1182/blood-2014-10-605022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The orphan nuclear receptors TR2 and TR4 have been shown to play key roles in repressing the embryonic and fetal globin genes in erythroid cells. However, combined germline inactivation of Tr2 and Tr4 leads to periimplantation lethal demise in inbred mice. Hence, we have previously been unable to examine the consequences of their dual loss of function in adult definitive erythroid cells. To circumvent this issue, we generated conditional null mutants in both genes and performed gene inactivation in vitro in adult bone marrow cells. Compound Tr2/Tr4 loss of function led to induced expression of the embryonic εy and βh1 globins (murine counterparts of the human ε- and γ-globin genes). Additionally, TR2/TR4 function is required for terminal erythroid cell maturation. Loss of TR2/TR4 abolished their occupancy on the εy and βh1 gene promoters, and concurrently impaired co-occupancy by interacting corepressors. These data strongly support the hypothesis that the TR2/TR4 core complex is an adult stage-specific, gene-selective repressor of the embryonic globin genes. Detailed mechanistic understanding of the roles of TR2/TR4 and their cofactors in embryonic and fetal globin gene repression may ultimately enhance the discovery of novel therapeutic agents that can effectively inhibit their transcriptional activity and be safely applied to the treatment of β-globinopathies.
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21
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Fetal globin gene repressors as drug targets for molecular therapies to treat the β-globinopathies. Mol Cell Biol 2014; 34:3560-9. [PMID: 25022757 DOI: 10.1128/mcb.00714-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human β-globin locus is comprised of embryonic, fetal, and adult globin genes that are expressed in a developmental stage-specific manner. Mutations in the globin locus give rise to the β-globinopathies, β-thalassemia and sickle cell disease, which begin to manifest symptoms around the time of birth. Although the fetal globin genes are autonomously silenced in adult-stage erythroid cells, mutations lying both within and outside the locus lead to natural variations in the level of fetal globin gene expression, and some of these significantly ameliorate the clinical symptoms of the β-globinopathies. Multiple reports have now identified several transcription factors that are involved in fetal globin gene repression in definitive (adult)-stage erythroid cells (the TR2/TR4 heterodimer, MYB, KLFs, BCL11A, and SOX6). To carry out their repression functions, chromatin-modifying enzymes (such as DNA methyltransferase, histone deacetylases, and lysine-specific histone demethylase 1) are additionally involved as a consequence of forming large macromolecular complexes with the DNA-binding subunits of these cellular machines. This review focuses on the molecular mechanisms underlying fetal globin gene silencing and possible near-future molecularly targeted therapies for treating the β-globinopathies.
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