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Kimura H, Onozawa M, Hashiguchi J, Hidaka D, Kanaya M, Matsukawa T, Okada H, Kondo T, Matsuno Y, Teshima T. Hereditary thrombocythemia due to splicing donor site mutation of THPO in a Japanese family. Ann Hematol 2024; 103:89-96. [PMID: 37962621 DOI: 10.1007/s00277-023-05523-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 10/25/2023] [Indexed: 11/15/2023]
Abstract
Thrombopoietin (THPO) is an essential factor for platelet production. Hereditary thrombocythemia (HT) is caused by a germline mutation of THPO, MPL, or JAK2 and is inherited in an autosomal-dominant manner. We identified a Japanese family with HT due to a point mutation of the splicing donor site of the THPO gene (THPO c.13 + 1G > A). Bone marrow biopsy showed increased megakaryocytes mimicking essential thrombocythemia. One affected family member developed chronic myeloid leukemia. We cloned the mutation and developed mutated and wild type THPO expression vectors. Molecular analysis showed that the mutation causes an exon 3 skipping transcript of THPO that abrogates a suppressive untranslated upstream open reading frame. Although the transcript levels of THPO mRNA were comparable, mutated transcripts were more efficiently translated and THPO protein expression was significantly higher than that of the wild type.
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Affiliation(s)
- Hiroyuki Kimura
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan
| | - Masahiro Onozawa
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan.
| | - Junichi Hashiguchi
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan
| | - Daisuke Hidaka
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan
| | - Minoru Kanaya
- Blood Disorders Center, Aiiku Hospital, Sapporo, Japan
| | - Toshihiro Matsukawa
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan
| | - Hiromi Okada
- Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Japan
| | - Takeshi Kondo
- Blood Disorders Center, Aiiku Hospital, Sapporo, Japan
| | - Yoshihiro Matsuno
- Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Japan
| | - Takanori Teshima
- Department of Hematology, Hokkaido University Faculty of Medicine, Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo, Japan
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Louzao M, Vargas MT, Meseguer E, Pedrote Amador B, Perez Simón JA, Mingot-Castellano ME. Successful use of thrombopoietin analogs in thrombocytopenia associated with MYH-9 mutation. Ann Hematol 2023; 102:3283-3284. [PMID: 37610462 DOI: 10.1007/s00277-023-05386-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 07/24/2023] [Indexed: 08/24/2023]
Affiliation(s)
- María Louzao
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - María Teresa Vargas
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - Emma Meseguer
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - Begoña Pedrote Amador
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - Jose Antonio Perez Simón
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - María Eva Mingot-Castellano
- Hematology Department, Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla, Seville, Spain.
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Shah A, Kumar C, Shanmukhaiah C, Rajendran A, Mudaliar S, Idicula-Thomas S, Vundinti BR. Genomic and computational analysis of four novel variants of MPL gene in Congenital Amegakaryocytic Thrombocytopenia. Ann Hematol 2023; 102:2683-2693. [PMID: 37438490 DOI: 10.1007/s00277-023-05347-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/29/2023] [Indexed: 07/14/2023]
Abstract
Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, genetic, autosomal recessive disorder characterized by severe thrombocytopenia, due to inefficient bone marrow megakaryopoiesis eventually leading to aplasia. Majority of the cases are due to homozygous or compound heterozygous mutations in MPL gene encoding for thrombopoietin (THPO) receptor protein. CAMT can be diagnosed at early phase of life, with major complication of transfusion dependency and hematopoietic transplantation as only curative treatment. We have investigated the sequence variations in MPL gene of 7 bone marrow failure (BMF) subjects, who presented with clinically diverse phenotypes, through next generation sequencing (NGS). Plasma THPO levels were estimated using ELISA. Insilico sequence and structure-based analyses were performed to understand the structural and functional implications of mutations, identified through NGS. We studied 7 CAMT subjects suspected of BMF, who presented with severe thrombocytopenia followed by pancytopenia, bleeding manifestation and physical anomalies. The plasma THPO levels were significantly elevated (p<0.05) in all the cases. Molecular analysis by NGS identified 9 genomic mutations in MPL gene. These included 7 non-synonymous substitution, 1 nonsense substitution and 1 in-del mutations, of which 4 are novel mutations. Insilico analysis predicted damaging effects on THPO-R and its reduced affinity for THPO for all the identified mutations. CAMT is a rare disorder with diverse clinical phenotypes and diagnosis is challenging. The elevated plasma THPO levels should be considered for the primary diagnosis and prognosis of the disease. However, molecular analysis of MPL gene is important for the diagnosis and management of the disease through genetic counselling. Though the cytokines, THPO-R agonist are used for the treatment of CAMT, HSCT is the only curative therapy.
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Affiliation(s)
- Anjali Shah
- Department of Cytogenetics, ICMR-National Institute of Immunohaematology, 13th floor, New Multi-storeyed building, KEM hospital Campus, Parel, Mumbai, Maharashtra, 400012, India
| | - Chandan Kumar
- Biomedical Informatics Centre, ICMR-National Institute for Research in Reproductive and Child Health, Mumbai, Maharashtra, 400012, India
| | - Chandrakala Shanmukhaiah
- Department of Haematology, KEM Hospital, 10th Floor, New Multistoried Building, Parel, Mumbai, Maharashtra, 400012, India
| | - Aruna Rajendran
- Department of Pediatric Hematology, Institute of Child Health and Hospital for Children, Chennai, India
| | | | - Susan Idicula-Thomas
- Biomedical Informatics Centre, ICMR-National Institute for Research in Reproductive and Child Health, Mumbai, Maharashtra, 400012, India
| | - Babu Rao Vundinti
- Department of Cytogenetics, ICMR-National Institute of Immunohaematology, 13th floor, New Multi-storeyed building, KEM hospital Campus, Parel, Mumbai, Maharashtra, 400012, India.
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Yang L, Wu L, Meng P, Zhang X, Zhao D, Lin Q, Zhang Y. Generation of a thrombopoietin-deficient thrombocytopenia model in zebrafish. J Thromb Haemost 2022; 20:1900-1909. [PMID: 35622056 DOI: 10.1111/jth.15772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/17/2022] [Accepted: 05/21/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND The production of platelets is tightly regulated by thrombopoietin (THPO). Mutations in the THPO gene cause thrombocytopenia. Although mice lacking Thpo present with thrombocytopenia, predicting phenotypes and pathogenicity of novel THPO mutations in mice is limited. Zebrafish can be a powerful tool for fast validation and study of candidate genes of human hematological diseases and have already been used as a model of human thrombocytopenia. OBJECTIVES We aim to investigate the role of Thpo in zebrafish thrombopoiesis and to establish a Thpo-deficient zebrafish model. The model could be applied for illustrating the clinically discovered human THPO variants of which the clinical significance is not known and to evaluate the effect of THPO receptor agonists (THPO-Ras), as well as a screening platform for new drugs. METHODS We generated a thpo loss-of-function zebrafish model using CRISPR/Cas9. After disruption of zebrafish thpo, thposzy6 zebrafish presented with a significant reduction of thpo expression and developed thrombocytopenia. Furthermore, we performed in vivo studies with zebrafish with the thposzy6 mutation and found two human clinical point mutations (c.091C > T and c.112C > T) that were responsible for the thrombocytopenia phenotype. In addition, effects of THPO-RAs used as therapeutics against thrombocytopenia were evaluated in the Tg(mpl:eGFP);thposzy6 line. RESULTS AND CONCLUSIONS Zebrafish with the mutation thposzy6 presented with a significant reduction of thpo expression and developed thrombocytopenia. Thpo loss-of-function zebrafish model can serve as a valuable preclinical model for thrombocytopenia caused by thpo-deficiency, as well as a tool to study human clinical THPO variants and evaluate the effect of THPO-RAs.
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Affiliation(s)
- Lian Yang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Liangliang Wu
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
- Department of Hematology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, China
| | - Panpan Meng
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Xuebing Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Dejian Zhao
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, China
| | - Qing Lin
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Yiyue Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
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Lee Y, DiMaulo-Milk E, Leslie J, Ding L. Hematopoietic stem cells temporally transition to thrombopoietin dependence in the fetal liver. Sci Adv 2022; 8:eabm7688. [PMID: 35294228 PMCID: PMC8926339 DOI: 10.1126/sciadv.abm7688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Tissue stem cells temporally change intrinsic mechanisms to meet physiological demands. However, little is known whether and how stem cells rely on distinct extrinsic maintenance mechanisms over time. Here, we found that hematopoietic stem cells (HSCs) temporally transition to depend on thrombopoietin (TPO), a key extrinsic factor, from E16.5 onward in the developing liver. Deletion of Tpo reduced mTOR activity, induced differentiation gene expression, and preferentially depleted metabolically active HSCs. Ectopic activation of the JAK2 or MAPK pathway did not rescue HSCs in Tpo-/- mice. Enforced activation of the mTOR pathway by conditionally deleting Tsc1 significantly rescued HSCs and their gene expression in Tpo-/- mice. Lin28b intrinsically promoted mTOR activation in HSCs, and its expression diminished over time. Conditional deletion of Lin28b further reduced mTOR activity and strongly exacerbated HSC depletion in Tpo-/- mice. Therefore, HSCs temporally transition from intrinsic LIN28B-dependent to extrinsic TPO-dependent maintenance in the developing liver.
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Gao L, Decker M, Chen H, Ding L. Thrombopoietin from hepatocytes promotes hematopoietic stem cell regeneration after myeloablation. eLife 2021; 10:e69894. [PMID: 34463253 PMCID: PMC8457823 DOI: 10.7554/elife.69894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
The bone marrow niche plays critical roles in hematopoietic recovery and hematopoietic stem cell (HSC) regeneration after myeloablative stress. However, it is not clear whether systemic factors beyond the local niche are required for these essential processes in vivo. Thrombopoietin (THPO) is a key cytokine promoting hematopoietic rebound after myeloablation and its transcripts are expressed by multiple cellular sources. The upregulation of bone marrow-derived THPO has been proposed to be crucial for hematopoietic recovery and HSC regeneration after stress. Nonetheless, the cellular source of THPO in myeloablative stress has never been investigated genetically. We assessed the functional sources of THPO following two common myeloablative perturbations: 5-fluorouracil (5-FU) administration and irradiation. Using a Thpo translational reporter, we found that the liver but not the bone marrow is the major source of THPO protein after myeloablation. Mice with conditional Thpo deletion from osteoblasts and/or bone marrow stromal cells showed normal recovery of HSCs and hematopoiesis after myeloablation. In contrast, mice with conditional Thpo deletion from hepatocytes showed significant defects in HSC regeneration and hematopoietic rebound after myeloablation. Thus, systemic THPO from the liver is necessary for HSC regeneration and hematopoietic recovery in myeloablative stress conditions.
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Affiliation(s)
- Longfei Gao
- Columbia Stem Cell Initiative, Columbia University Medical CenterNew YorkUnited States
- Department of Rehabilitation and Regenerative Medicine, Columbia University Medical CenterNew YorkUnited States
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, United StatesNew YorkUnited States
| | - Matthew Decker
- Columbia Stem Cell Initiative, Columbia University Medical CenterNew YorkUnited States
- Department of Rehabilitation and Regenerative Medicine, Columbia University Medical CenterNew YorkUnited States
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, United StatesNew YorkUnited States
| | - Haidee Chen
- Columbia Stem Cell Initiative, Columbia University Medical CenterNew YorkUnited States
- Department of Rehabilitation and Regenerative Medicine, Columbia University Medical CenterNew YorkUnited States
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, United StatesNew YorkUnited States
| | - Lei Ding
- Columbia Stem Cell Initiative, Columbia University Medical CenterNew YorkUnited States
- Department of Rehabilitation and Regenerative Medicine, Columbia University Medical CenterNew YorkUnited States
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, United StatesNew YorkUnited States
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Spivak JL, Merchant A, Williams DM, Rogers O, Zhao W, Duffield A, Resar LS, Moliterno AR, Zhao ZJ. Thrombopoietin is required for full phenotype expression in a JAK2V617F transgenic mouse model of polycythemia vera. PLoS One 2020; 15:e0232801. [PMID: 32479500 PMCID: PMC7263591 DOI: 10.1371/journal.pone.0232801] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/21/2020] [Indexed: 12/30/2022] Open
Abstract
The myeloproliferative neoplasms, polycythemia vera, essential thrombocytosis and primary myelofibrosis are hematopoietic stem cell disorders and share driver mutations that either directly activate the thrombopoietin receptor, MPL, or activate it indirectly through gain-of-function mutations in the gene for JAK2, its cognate tyrosine kinase. Paradoxically, MPL surface expression in hematopoietic stem cells is also reduced in the myeloproliferative neoplasms due to abnormal post-translational glycosylation and premature destruction of JAK2, suggesting that the myeloproliferative neoplasms are disorders of MPL processing since MPL is the only hematopoietic growth factor receptor in hematopoietic stem cells. To examine this possibility, we genetically manipulated MPL expression and maturation in a JAK2V617F transgenic mouse model of polycythemia vera. Elimination of MPL expression completely abrogated the polycythemia vera phenotype in this JAK2V617F transgenic mouse model, which could only be partially restored by expression of one MPL allele. Most importantly, elimination of thrombopoietin gene expression abrogated the polycythemia vera phenotype in this JAK2V617F transgenic mouse model, which could be completely restored by expression of a single thrombopoietin allele. These data indicate that polycythemia vera is in part a thrombopoietin-dependent disorder and that targeting the MPL-thrombopoietin axis could be an effective, nonmyelotoxic therapeutic strategy in this disorder.
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Affiliation(s)
- Jerry L. Spivak
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - Akil Merchant
- Samuel Oschin Comprehensive Cancer Institute, Blood and Marrow Transplant Program, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Donna M. Williams
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ophelia Rogers
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Wanke Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Amy Duffield
- Department of Pathology, Hematologic Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Linda S. Resar
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Alison R. Moliterno
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zhizhuang J. Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
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Cho J, Kim H, Song J, Cheong JW, Shin JW, Yang WI, Kim HO. Platelet storage induces accelerated desialylation of platelets and increases hepatic thrombopoietin production. J Transl Med 2018; 16:199. [PMID: 30021591 PMCID: PMC6052694 DOI: 10.1186/s12967-018-1576-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/13/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Stored platelets undergo deleterious changes, referred to as platelet storage lesions (PSLs), which accelerate the desialylation of platelets and result in their phagocytosis and clearance by hepatic macrophages. Recent studies have reported that Ashwell-Morell receptor binds to desialylated platelets, thereby inducing hepatic thrombopoietin (TPO) production in a mouse model. Therefore, this study aimed to demonstrate these relationships between PSL and hepatic TPO production in human study. METHODS Platelet concentrates (PCs) were obtained from 5 healthy volunteers and the remaining were discarded samples from the blood bank. PCs were divided into two halves, and stored either at 22 or 4 °C. Experiments were conducted using serial samples. Desialylation was assessed using flow cytometry, and structural changes were visualized using electron microscopy. Following co-culture of HepG2 cells (HB-8065, ATCC) with isolated platelets, hepatic TPO production was determined using real-time quantitative polymerase chain reaction and the supernatant TPO level was measured using a Luminex kit. RESULTS For 5 days of storage duration, platelet counts were not influenced by the storage conditions, but the degree of desialylation was proportional to the storage duration. Significant changes in the platelet surface and structure according to storage conditions were noted in electron microscopy. HepG2 cells incubated with aged platelets expressed more TPO mRNA, and supernatant TPO levels were proportional to the storage duration. Refrigeration also influenced on the results of this study, but they were not statistically significant. CONCLUSIONS This is the first study to demonstrate that, in vitro, aging and refrigeration affect the integrity of human platelets, resulting in induction of hepatic TPO mRNA and protein expression.
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Affiliation(s)
- Jooyoung Cho
- Department of Laboratory Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722 South Korea
- Department of Laboratory Medicine, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Hyunkyung Kim
- Department of Obstetrics and Gynecology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
| | - Jaewoo Song
- Department of Laboratory Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722 South Korea
| | - June-Won Cheong
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Jeong Won Shin
- Department of Laboratory Medicine, Soonchunhyang University School of Medicine, Seoul, South Korea
| | - Woo Ick Yang
- Department of Pathology, Yonsei University College of Medicine, Seoul, South Korea
| | - Hyun Ok Kim
- Department of Laboratory Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722 South Korea
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Wu Z, Wei D, Gao W, Xu Y, Hu Z, Ma Z, Gao C, Zhu X, Li Q. TPO-Induced Metabolic Reprogramming Drives Liver Metastasis of Colorectal Cancer CD110+ Tumor-Initiating Cells. Cell Stem Cell 2016; 17:47-59. [PMID: 26140605 DOI: 10.1016/j.stem.2015.05.016] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 04/26/2015] [Accepted: 05/29/2015] [Indexed: 02/07/2023]
Abstract
Liver metastasis is a leading cause of death in patients with colorectal cancer. We previously found that colorectal cancer tumor-initiating cells (TICs) expressing CD110, the thrombopoietin (TPO)-binding receptor, mediate liver metastasis. Here, we show that TPO promotes metastasis of CD110+ TICs to the liver by activating lysine degradation. Lysine catabolism generates acetyl-CoA, which is used in p300-dependent LRP6 acetylation. This triggers tyrosine phosphorylation of LRP6, ultimately activating Wnt signaling to promote self-renewal of CD110+ TICs. Lysine catabolism also generates glutamate, which modulates the redox status of CD110+ TICs to promote liver colonization and drug resistance. Mechanistically, TPO-mediated induction of c-myc orchestrates recruitment of chromatin modifiers to regulate metabolic gene expression. Our findings, therefore, establish TPO as a component of the physiological environment critical for metastasis of colorectal cancer to the liver.
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Affiliation(s)
- ZhengMing Wu
- Department of Pathology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Dong Wei
- Department of Anus and Intestine Surgery, PLA Central Hospital 150, Luoyang, Henan 471031, China
| | - WenChao Gao
- Department of General Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - YuTing Xu
- Department of Pathology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - ZhiQian Hu
- Department of General Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - ZhenYu Ma
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - ChunFang Gao
- Department of Anus and Intestine Surgery, PLA Central Hospital 150, Luoyang, Henan 471031, China
| | - XiaoYan Zhu
- Department of Traditional Chinese Medicine, Shanghai Cancer Hospital, Fudan University, Shanghai 200032, China
| | - QingQuan Li
- Department of Pathology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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10
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Tanizaki Y, Ichisugi M, Obuchi-Shimoji M, Ishida-Iwata T, Tahara-Mogi A, Meguro-Ishikawa M, Kato T. Thrombopoietin induces production of nucleated thrombocytes from liver cells in Xenopus laevis. Sci Rep 2015; 5:18519. [PMID: 26687619 PMCID: PMC4685256 DOI: 10.1038/srep18519] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/06/2015] [Indexed: 12/29/2022] Open
Abstract
The development of mammalian megakaryocytes (MKs) and platelets, which are thought to be absent in non-mammals, is primarily regulated by the thrombopoietin (TPO)/Mpl system. Although non-mammals possess nucleated thrombocytes instead of platelets, the features of nucleated thrombocyte progenitors remain to be clarified. Here, we provide the general features of TPO using Xenopus laevis TPO (xlTPO). Hepatic and splenic cells were cultured in liquid suspension with recombinant xlTPO. These cells differentiated into large, round, polyploid CD41-expressing cells and were classified as X. laevis MKs, comparable to mammalian MKs. The subsequent culture of MKs after removal of xlTPO produced mature, spindle-shaped thrombocytes that were activated by thrombin, thereby altering their morphology. XlTPO induced MKs in cultured hepatic cells for at least three weeks; however, this was not observed in splenic cells; this result demonstrates the origin of early haematopoietic progenitors in the liver rather than the spleen. Additionally, xlTPO enhanced viability of peripheral thrombocytes, indicating the xlTPO-Mpl pathway stimulates anti-apoptotic in peripheral thrombocytes. The development of thrombocytes from MKs via the TPO-Mpl system in X. laevis plays a crucial role in their development from MKs, comparable to mammalian thrombopoiesis. Thus, our results offer insight into the cellular evolution of platelets/MKs in vertebrates. (200/200).
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Affiliation(s)
- Yuta Tanizaki
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan
| | - Megumi Ichisugi
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Miyako Obuchi-Shimoji
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Takako Ishida-Iwata
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Ayaka Tahara-Mogi
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Mizue Meguro-Ishikawa
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Takashi Kato
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
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Katakura F, Katzenback BA, Belosevic M. Recombinant goldfish thrombopoietin up-regulates expression of genes involved in thrombocyte development and synergizes with kit ligand A to promote progenitor cell proliferation and colony formation. Dev Comp Immunol 2015; 49:157-169. [PMID: 25450454 DOI: 10.1016/j.dci.2014.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/31/2014] [Accepted: 11/01/2014] [Indexed: 06/04/2023]
Abstract
Thrombopoietin (TPO) is the principal regulator of thrombopoiesis and promotes the proliferation, differentiation and maturation of megakaryocytic progenitor cells in mammals. In this study we report on the molecular and functional characterization of goldfish TPO. Quantitative expression analysis of goldfish tpo revealed the highest mRNA levels in heart, followed by spleen, liver, brain, intestine and kidney tissues. Significant decrease of tpo and c-mpl expressions in goldfish primary kidney macrophage (PKM) cultures, as progenitor to macrophage development progressed, indicates that TPO is not involved in monopoiesis. Recombinant goldfish TPO (rgTPO) alone did not induce significant proliferation of progenitor cells, but TPO in cooperation with recombinant goldfish kit ligand A (rgKITLA) supported proliferation of progenitor cells in a dose-dependent manner. In response to rgTPO or a combination of rgTPO and rgKITLA, the mRNA levels of thrombopoietic markers cd41 and c-mpl as well as thrombo/erythropoietic transcription factors gata1 and lmo2 in sorted progenitor cells were up-regulated, while the mRNA levels of granulopoietic markers (cebpα and gcsfr) and the lymphoid transcription factor gata3 were down-regulated. Furthermore, rgTPO and rgKITLA synergistically stimulated thrombocytic colony-formation. Our results demonstrate that goldfish TPO has similar functions to mammalian TPO as a regulator of thrombopoiesis, and suggests a highly conserved molecular mechanism of thrombocyte development throughout evolution of vertebrates.
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Affiliation(s)
- Fumihiko Katakura
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Barbara A Katzenback
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Miodrag Belosevic
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
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Reiff RE, Ali BR, Baron B, Yu TW, Ben-Salem S, Coulter ME, Schubert CR, Hill RS, Akawi NA, Al-Younes B, Kaya N, Evrony GD, Al-Saffar M, Felie JM, Partlow JN, Sunu CM, Schembri-Wismayer P, Alkuraya FS, Meyer BF, Walsh CA, Al-Gazali L, Mochida GH. METTL23, a transcriptional partner of GABPA, is essential for human cognition. Hum Mol Genet 2014; 23:3456-66. [PMID: 24501276 DOI: 10.1093/hmg/ddu054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Whereas many genes associated with intellectual disability (ID) encode synaptic proteins, transcriptional defects leading to ID are less well understood. We studied a large, consanguineous pedigree of Arab origin with seven members affected with ID and mild dysmorphic features. Homozygosity mapping and linkage analysis identified a candidate region on chromosome 17 with a maximum multipoint logarithm of odds score of 6.01. Targeted high-throughput sequencing of the exons in the candidate region identified a homozygous 4-bp deletion (c.169_172delCACT) in the METTL23 (methyltransferase like 23) gene, which is predicted to result in a frameshift and premature truncation (p.His57Valfs*11). Overexpressed METTL23 protein localized to both nucleus and cytoplasm, and physically interacted with GABPA (GA-binding protein transcription factor, alpha subunit). GABP, of which GABPA is a component, is known to regulate the expression of genes such as THPO (thrombopoietin) and ATP5B (ATP synthase, H+ transporting, mitochondrial F1 complex, beta polypeptide) and is implicated in a wide variety of important cellular functions. Overexpression of METTL23 resulted in increased transcriptional activity at the THPO promoter, whereas knockdown of METTL23 with siRNA resulted in decreased expression of ATP5B, thus revealing the importance of METTL23 as a regulator of GABPA function. The METTL23 mutation highlights a new transcriptional pathway underlying human intellectual function.
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Affiliation(s)
- Rachel E Reiff
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Harvard-Massachusetts Institute of Technology (MIT) Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Bassam R Ali
- Department of Pathology, College of Medicine and Health Sciences
| | - Byron Baron
- Department of Anatomy, Faculty of Medicine and Surgery, University of Malta, Msida MSD2080, Malta
| | - Timothy W Yu
- Division of Genetics and Genomics, Department of Medicine Department of Pediatrics Pediatric Neurology Unit, Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA Program in Medical and Population Genetics, Broad Institute of MIT and Harvard University, Cambridge, MA 02142, USA
| | - Salma Ben-Salem
- Department of Pathology, College of Medicine and Health Sciences
| | - Michael E Coulter
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Harvard-Massachusetts Institute of Technology (MIT) Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Christian R Schubert
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Department of Pediatrics Research Laboratory of Electronics and Department of Electrical Engineering and Computer Science, Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - R Sean Hill
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Nadia A Akawi
- Department of Pathology, College of Medicine and Health Sciences
| | - Banan Al-Younes
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Namik Kaya
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Gilad D Evrony
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Program in Biological and Biomedical Sciences and
| | - Muna Al-Saffar
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Department of Paediatrics, College of Medicine and Health Sciences, United Arab Emirates University, PO Box 17666, Al-Ain, United Arab Emirates
| | - Jillian M Felie
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jennifer N Partlow
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Christine M Sunu
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Pierre Schembri-Wismayer
- Department of Anatomy, Faculty of Medicine and Surgery, University of Malta, Msida MSD2080, Malta
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Christopher A Walsh
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA Department of Pediatrics Department of Neurology, Harvard Medical School, Boston, MA 02115, USA Program in Medical and Population Genetics, Broad Institute of MIT and Harvard University, Cambridge, MA 02142, USA
| | - Lihadh Al-Gazali
- Department of Paediatrics, College of Medicine and Health Sciences, United Arab Emirates University, PO Box 17666, Al-Ain, United Arab Emirates
| | - Ganeshwaran H Mochida
- Division of Genetics and Genomics, Department of Medicine Manton Center for Orphan Disease Research and Department of Pediatrics Pediatric Neurology Unit, Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
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Rozhdestvenskiĭ LM. [Actual problems of searching and studying radiation countermeasures]. Radiats Biol Radioecol 2013; 53:513-520. [PMID: 25434173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The state of radiation counterdrug elaboration has been analyzed. The main criterion of estimation is how various possible radiation incidents are provided with radiation countermeasures. The latter are differentiated in 3 principal groups: radioprotectors, radiomodificators (these are able to have a positive effect when administered preliminary, before the exposure, or provide a delayed nonspecific protection after the exposure--urgent therapy) and hemopoietic growth factors demanding course administration. It should be underlined that the list ofofficinal radiation countermeasures is rather short. The most dynamic now are investigations aimed at developing a home preparation of recombinant human interleukine-1beta named betaleukine, and the preparation CBLB502, a modified microbe polypeptide elaborated in the USA. Also elaborated is a scheme of emergency exposure treatment. It includes urgent administration of the cytokine combination (betaleukine and thrombopoietin) with subsequent supportive therapy and a hemopoietic growth factors course. In the case of medical radiation- and chemotherapy the preparations betaleukine and thiol compound amifostine are used rather seldom. Official countermeasures for protection against low dose rate prolonged exposure are still absent. The problem of an indicator/marker of the radioresistance induced by a radioprotector or radiomodificator still remains unsolved. Reliable indicators/markers are needed to provide the 2nd stage of clinical trials of radioprotectors/modificators.
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Matsubara Y, Ono Y, Suzuki H, Arai F, Suda T, Murata M, Ikeda Y. OP9 bone marrow stroma cells differentiate into megakaryocytes and platelets. PLoS One 2013; 8:e58123. [PMID: 23469264 PMCID: PMC3585802 DOI: 10.1371/journal.pone.0058123] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/31/2013] [Indexed: 01/04/2023] Open
Abstract
Platelets are essential for hemostatic plug formation and thrombosis. The mechanisms of megakaryocyte (MK) differentiation and subsequent platelet production from stem cells remain only partially understood. The manufacture of megakaryocytes (MKs) and platelets from cell sources including hematopoietic stem cells and pluripotent stem cells have been highlighted for studying the platelet production mechanisms as well as for the development of new strategies for platelet transfusion. The mouse bone marrow stroma cell line OP9 has been widely used as feeder cells for the differentiation of stem cells into MK lineages. OP9 cells are reported to be pre-adipocytes. We previously reported that 3T3-L1 pre-adipocytes differentiated into MKs and platelets. In the present study, we examined whether OP9 cells differentiate into MKs and platelets using MK lineage induction (MKLI) medium previously established to generate MKs and platelets from hematopoietic stem cells, embryonic stem cells, and pre-adipocytes. OP9 cells cultured in MKLI medium had megakaryocytic features, i.e., positivity for surface markers CD41 and CD42b, polyploidy, and distinct morphology. The OP9-derived platelets had functional characteristics, providing the first evidence for the differentiation of OP9 cells into MKs and platelets. We then analyzed gene expressions of critical factors that regulate megakaryopoiesis and thrombopoiesis. The gene expressions of p45NF-E2, FOG, Fli1, GATA2, RUNX1, thrombopoietin, and c-mpl were observed during the MK differentiation. Among the observed transcription factors of MK lineages, p45NF-E2 expression was increased during differentiation. We further studied MK and platelet generation using p45NF-E2-overexpressing OP9 cells. OP9 cells transfected with p45NF-E2 had enhanced production of MKs and platelets. Our findings revealed that OP9 cells differentiated into MKs and platelets in vitro. OP9 cells have critical factors for megakaryopoiesis and thrombopoiesis, which might be involved in a mechanism of this differentiation. p45NF-E2 might also play important roles in the differentiation of OP9 cells into MK lineages cells.
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Affiliation(s)
- Yumiko Matsubara
- Department of Laboratory Medicine, Keio University School of Medicine, Tokyo, Japan.
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Graziano C, David M, Magini P, Superti-Furga A, Seri M. An additional family with association of hereditary thrombocytosis and transverse limb deficiency: confirmation of a rare clinical spectrum. Am J Med Genet A 2012; 158A:3211-3. [PMID: 23165915 DOI: 10.1002/ajmg.a.35656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 08/22/2012] [Indexed: 12/23/2022]
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Abstract
BACKGROUND Most physiologic processes exhibit diurnal fluctuations controlled by the circadian regulation of sleep-wake behavior and feeding cycles. In addition, many cell types express endogenous circadian rhythms that affect cell-specific processes. Independent reports support the hypothesis that thrombopoietin (TPO) is under circadian control. OBJECTIVES The current study tested the hypothesis that CLOCK, a circadian transcription factor, may regulate Thpo, the gene encoding TPO. METHODS Circadian gene expression patterns were analyzed in mice and in human cell lines, Small interfering RNA was used to knock down CLOCK expression in cell lines, and gene expression was also examined in Clock(Δ19/Δ19) mutant mice. RESULTS It was found that there was a diurnal rhythm in the expression of Thpoin vivo in mice, and that this was associated with concomitant rhythms of protein abundance. Thpo was rhythmically expressed in human cell lines, consistent with the gene being directly or indirectly regulated by the circadian clock. Silencing of CLOCK in the Huh7 human hepatoma cell line led to a significant reduction in the rhythmicity of Thpo expression. The expression of Mpl in murine marrow also displayed diurnal rhythmicity in vivo. In Clock(Δ19/Δ19) mutant mice, Thpo and Mpl expression was disrupted and there was an increase in the number of mature megakaryocytes, but no change in the ploidy distribution within the megakaryocyte population. CONCLUSIONS These findings establish that Clock regulates Thpo and Mpl expression in vivo, and demonstrate an important link between the body's circadian timing mechanisms and megakaryopoiesis.
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Affiliation(s)
- C J Tracey
- University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
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Li QJ, Zou LP, Wang JW. [Signal transduction pathway mediated by thrombopoietin in the inflammation model of microglia]. Zhongguo Dang Dai Er Ke Za Zhi 2011; 13:340-343. [PMID: 21507308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVE To explore the signal transduction pathway mediated by thrombopoietin (TPO) in the inflammation model of microglia induced by lipopolysaccharide (LPS). METHODS The inflammation model of microglia BV2 cells was prepared by LPS of 0.5 and 1.0 μg/mL stimulation. The expression of TPO and ERK mRNA in BV2 cells was detected by real time quantitative PCR. Western blot was used to evaluate the expression of TPO and ERK protein in BV2 cells. TPO and IL-6 contents in the culture supernatant fluid were measured using ELISA. RESULTS LPS stimulation increased significantly the mRNA and protein expression of TPO and ERK in BV2 cells, especially at the concentration of 1.0 μg/mL for 12 hrs stimulation. There was a significant positive correlation between the mRNA and protein expression of TPO and ERK. CONCLUSIONS Signal transduction pathway of ERK1/2 participates in the activation of TPO in inflammatory injury of BV2 cells.
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Affiliation(s)
- Qiao-Jun Li
- Department of Pediatrics, First Affiliated Hospital of the People's Liberation Army General Hospital, Beijing 100048, China.
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Abstract
INTRODUCTIONIn the protocol presented here, hematopoietic stem cells (HSCs) are specifically transduced with a vector displaying the HSC-activating polypeptides, stem cell factor (SCF) and thrombopoietin (TPO). Targeted HSC transduction is evaluated in the non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse model.
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Abstract
Familial and acquired erythrocytosis and thrombocytosis are characterized by myeloid lineage hyperproliferation, which is either single or multi-lineage in origin. The single lineage disorders exhibit Mendelian inheritance with polyclonal hematopoiesis and often arise from a single genetic defect. In contrast, the multi-lineage disorders exhibit complex patterns of inheritance with multi-genetic origins and clonal hematopoiesis. They have the potential to acquire JAK2 somatic mutations, but this is not the primary event. Identification of the disease-causing genes will enable better classification of familial and acquired erythrocytosis and thrombocytosis. Furthermore, it will provide an insight into the mechanisms regulating myeloid cell proliferation.
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Affiliation(s)
- Melanie J Percy
- Department of Haematology, Belfast City Hospital, Belfast, Northern Ireland, UK.
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Abstract
Major progress in understanding the pathogenesis in patients with thrombocytosis has been made by identifying mutations in the key regulators of thrombopoietin: the thrombopoietin receptor MPL and JAK2. Together, these mutations can be found in 50% to 60% of patients with essential thrombocythemia or primary myelofibrosis and in 10% to 20% of hereditary thrombocytosis. A decrease in expression of the Mpl protein can cause thrombocytosis even in the absence of mutations in the coding sequence, due to a shift in the balance between stimulation of signaling in megakaryopoiesis and removal of thrombopoietin by receptor mediated internalization in platelets. When present in a heterozygous state the JAK2-V617F mutation preferentially stimulates megakaryopoiesis and in most cases manifests as essential thrombocythemia (ET), whereas homozygous JAK2-V617F reduces megakaryopoiesis in favor of increased erythropoiesis, resulting in polycythemia vera and/or myelofibrosis. In 30% to 40% of patients with ET or primary myelofibrosis (PMF) and in 80% to 90% of pedigrees with hereditary thrombocytosis the disease-causing gene remains unknown. Ongoing genetic and genomic screens have identified genes that, when mutated, can cause thrombocytosis in mouse models. A more complete picture of the pathways that regulate megakaryopoisis and platelet production will be important for finding new ways of controlling platelet production in patients with thrombocytosis.
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Affiliation(s)
- Radek C Skoda
- Experimental Hematology, Department of Biomedicine, University Hospital Basel, Basel, Switzerland.
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Marcucci R, Romano M. Thrombopoietin and its splicing variants: structure and functions in thrombopoiesis and beyond. Biochim Biophys Acta Mol Basis Dis 2008; 1782:427-32. [PMID: 18433726 DOI: 10.1016/j.bbadis.2008.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 03/21/2008] [Accepted: 03/25/2008] [Indexed: 11/18/2022]
Abstract
Since its cloning in 1994, several studies have reported that thrombopoietin (THPO) presents several alternative splicing products that differ from the full-length protein in its 5' UTR, N- or C-terminal regions. Most of these splice variants are evolutionarily conserved and have been detected in different tissues as well as in cell lines. Although the possible functions of the THPO isoforms are still elusive, different clues link them to the peculiar mechanism that regulates THPO production. Moreover, novel fields to explore possible roles of the THPO variants are opened by observations that this hormone can influence the formation of hematopoietic progenitors and its expression occurs in some tumors as well as in tissues not directly related to the thrombopoiesis. In this review, we summarize the structure and functions of THPO through the published evidence on its splicing isoforms and discuss about their involvement with physiopathologic phenomena.
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Affiliation(s)
- Roberto Marcucci
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34012, Trieste, Italy
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Cho SK, Kim JH, Park JY, Choi YJ, Bang JI, Hwang KC, Cho EJ, Sohn SH, Uhm SJ, Koo DB, Lee KK, Kim T, Kim JH. Serial cloning of pigs by somatic cell nuclear transfer: restoration of phenotypic normality during serial cloning. Dev Dyn 2008; 236:3369-82. [PMID: 17849457 DOI: 10.1002/dvdy.21308] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Somatic cell nuclear transfer (scNT) is a useful way to create cloned animals. However, scNT clones exhibit high levels of phenotypic instability. This instability may be due to epigenetic reprogramming and/or genomic damage in the donor cells. To test this, we produced transgenic pig fibroblasts harboring the truncated human thrombopoietin (hTPO) gene and used them as donor cells in scNT to produce first-generation (G1) cloned piglets. In this study, 2,818 scNT embryos were transferred to 11 recipients and five G1 piglets were obtained. Among them, a clone had a dimorphic facial appearance with severe hypertelorism and a broad prominent nasal bridge. The other clones looked normal. Second-generation (G2) scNT piglets were then produced using ear cells from a G1 piglet that had an abnormal nose phenotype. We reasoned that, if the phenotypic abnormality of the G1 clone was not present in the G2 and third-generation (G3) clones, or was absent in the G2 clones but reappeared in the G3 clones, the phenotypic instability of the G1 clone could be attributed to faulty epigenetic reprogramming rather than to inherent/accidental genomic damage to the donor cells. Blastocyst rates, cell numbers in blastocyst, pregnancy rates, term placenta weight and ponderal index, and birth weight between G1 and G2 clones did not differ, but were significantly (P < 0.05) lower than control age- and sex-matched piglets. Next, we analyzed global methylation changes during development of the preimplantation embryos reconstructed by donor cells used for the production of G1 and G2 clones and could not find any significant differences in the methylation patterns between G1 and G2 clones. Indeed, we failed to detect the phenotypic abnormality in the G2 and G3 clones. Thus, the phenotypic abnormality of the G1 clone is likely to be due to epigenetic dysregulation. Additional observations then suggested that expression of the hTPO gene in the transgenic clones did not appear to be the cause of the phenotypic abnormality in the G1 clones and that the abnormality was acquired by only a few of the G1 clone's cells during its gestational development.
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Affiliation(s)
- Seong-Keun Cho
- Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University, Jinju, GyeongNam, South Korea
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Zhang L, Yu J, Mo S, Yang G, Li X, Xian Y, Jin XQ. [Effect of fibronectin-thrombopoietin gene modification on human bone marrow mesenchymal stem cells]. Zhonghua Xue Ye Xue Za Zhi 2007; 28:832-836. [PMID: 18476596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
OBJECTIVE To observe the effect of Fn-TPO gene modification on human bone marrow mesenchymal stem cells (MSCs). METHODS Retroviral vector containing Fn-TPO gene was constructed and bone marrow MSCs was modified by this vector. The transcription of Fn-TPO gene in MSCs was observed. The proliferation capacities, hematopoietic cells adhering capacities and TPO secretion capacities of gene modified MSCs were assayed respectively. Cord blood CD34 cells were seeded on the gene modified MSCs layers and several essential growth factors were added. After co-culturing in vitro for 7 days, the number of CD34 cells and their colony forming capacities were assayed by flow cytometry and semisolid culture assay. RESULTS Retroviral vector containing Fn-TPO gene was successfully constructed and bone marrow MSCs were modified by this vector. Fn-TPO gene was expressed by bone marrow MSCs after gene modification. The viability of MSCs had no significant difference between pre- and post-gene-modification [(7.18 +/- 0.89) 10(4)/ml vs. (6.92 +/- 0.77) 10(4)/ml, P > 0.05]. The hematopoietic cells adhering ability of gene modified bone marrow MSCs was reinforced(0. 188 +/- 0.018 vs. 0.167 +/- 0.017, P < 0.01). The concentration of TPO in the MSCs culture supernatant raised from (5.58 +/- 0.37) ng/ml to (7.46 +/- 0.59) ng/ml (P < 0.01) and did not significantly decline in a short-time period, but influenced by the growth status of MSCs. After co-culturing with gene modified MSCs for 7 days, the absolute number of nucleated cells, the percentage of CD34+ cells and the colony numbers of BFU-E, CFU-GM, CFU-GEMM were (29.9 +/- 2.7) x 10(4), (33.3 +/- 2.8)% , 109.3 +/- 4.1, 163.7 +/- 7.1, 13.3 +/- 1.5, respectively, being significantly higher than that co-cultured with non-modified MSCs. CONCLUSIONS Fn-TPO gene modification can improve the capacity of human bone marrow MSCs for hematopoietic cells adhering, TPO secretion and cord blood CD34 cells amplification.
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Affiliation(s)
- Lei Zhang
- Department of Hematology, Children's Hospital, Chongqing Medical University, Chongqing 400014, China
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Mohan C, Park SH, Chung JY, Lee GM. Effect of doxycycline-regulated protein disulfide isomerase expression on the specific productivity of recombinant CHO cells: thrombopoietin and antibody. Biotechnol Bioeng 2007; 98:611-5. [PMID: 17421043 DOI: 10.1002/bit.21453] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Protein disulfide isomerase (PDI), one of the ER-resident molecular chaperones, forms and isomerizes disulfide bonds. This study attempts to investigate the effect of PDI expression level on specific productivity (q) of recombinant Chinese hamster ovary (rCHO) cells producing thrombopoietin (TPO) and antibody (Ab). To regulate the PDI expression level, the Tet-Off system was introduced in TPO and Ab producing CHO cells, and stable Tet-Off cells (TPO-Tet-Off and Ab-Tet-Off) were screened using the luciferase assay. The doxycycline-regulated PDI expression system in Tet-Off rCHO cells (Tet-TPO-PDI and Tet-Ab-PDI) was established by the cotransfection of pTRE-PDI and pTK-Hyg expression vector into TPO-Tet-Off and Ab-Tet-Off cells, respectively. Subsequent screening was done by Western blot analysis of PDI and an enzyme-linked immunosorbent assay of the secreted TPO and antibody. We cultured two Tet-TPO-PDI and two Tet-Ab-PDI clones, and all these clones showed an average of 2.5-fold increase in PDI expression when compared to the basal level. In both these cell lines the PDI expression was tightly controlled by various concentrations of doxycycline. The q of TPO (q(TPO)) was unaffected but that of antibody producing cells was increased by 15-27% due to the PDI expression level.
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Affiliation(s)
- Chaya Mohan
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Daejon 305-701, Korea
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Zang Y, Zhang Y, Peng W, Chen B, Zhu J, Zhang C, Ouyang J, Qin J. A novel thrombopoietin–stem-cell factor fusion protein possesses enhanced potential in stimulating megakaryocyte proliferation and differentiation. Biotechnol Appl Biochem 2007; 48:135-42. [PMID: 17516919 DOI: 10.1042/ba20070063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TPO (thrombopoietin) and SCF (stem-cell factor) are functionally related cytokines with overlapping but distinct haematopoietic effects. In the present study, a novel TPO-SCF fusion protein that combined the complementary biological effects of TPO and SCF into a single molecule was expressed in, and purified from, Sf9 [Spodoptera frugiperda (fall armyworm)] insect cells. The specific activity of rhTPO (recombinant human TPO)-SCF in megakaryoblastic Mo7e cell proliferation assays was 2.90+/-0.35 x 10(7) units/micromol, approx. 1.7 times as high as that of rhTPO. The specific activity of rhTPO-SCF in TF-1 cells proliferation assays was 7.10+/-0.95 x 10(6) units/micromol, approx. 1.2 times as high as that of rhSCF (recombinant human SCF). In a megakaryocyte-colony-forming assay using human peripheral-blood CD34(+) cells, the SCF moiety of rhTPO-SCF worked in a synergistic way to augment the colony number and exhibited a higher potential to stimulate megakaryocyte colony growth. According to the results of EMSA (electrophoretic mobility-shift assay) and semi-quantitative RT (reverse transcriptase)-PCR, the synergistic effects of the SCF moiety were also reflected in increased STAT5 (signal transducer and activator of transcription 5) DNA binding and enhanced up-regulation of p21 expression in Mo7e cells treated by rhTPO-SCF, suggesting that rhTPO-SCF could be more potent in promoting megakaryocyte proliferation and differentiation.
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Affiliation(s)
- Yuhui Zang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing 210093, People's Republic of China
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Teofili L, Giona F, Martini M, Cenci T, Guidi F, Torti L, Palumbo G, Amendola A, Leone G, Foà R, Larocca LM. The revised WHO diagnostic criteria for Ph-negative myeloproliferative diseases are not appropriate for the diagnostic screening of childhood polycythemia vera and essential thrombocythemia. Blood 2007; 110:3384-6. [PMID: 17644735 DOI: 10.1182/blood-2007-06-094276] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Abstract
In the proposed revised World Health Organization (WHO) criteria for the diagnosis of BCR-ABL− myeloproliferative diseases (MPDs), exclusion criteria have been replaced by the presence of JAK2 mutations. We applied these criteria to 45 children with MPDs: 13 with polycythemia vera (PV) and 32 with essential thrombocythemia (ET). Among these 45 patients, 12 with ET and 5 with PV had a familial history of MPD, and had been investigated for hereditary mutations of the erythropoietin receptor, thrombopoietin, or MPL genes. We found that the JAK2V617F mutation in children occurs less frequently than in adults, and that exon 12 JAK2 mutations are absent. On the basis of the revised WHO criteria, a significant proportion of childhood PVs were misdiagnosed. Furthermore, all familial ET, including patients carrying the hereditary MPLSer505Asn activating mutation, were erroneously diagnosed as MPDs. Our observations suggest that childhood MPDs require a set of specific diagnostic criteria.
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Affiliation(s)
- Luciana Teofili
- Department of Hematology, Catholic University, Largo Gemelli 8, 00168 Rome, Italy
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27
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Sung YH, Lee JS, Park SH, Koo J, Lee GM. Influence of co-down-regulation of caspase-3 and caspase-7 by siRNAs on sodium butyrate-induced apoptotic cell death of Chinese hamster ovary cells producing thrombopoietin. Metab Eng 2007; 9:452-64. [PMID: 17892962 DOI: 10.1016/j.ymben.2007.08.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 08/07/2007] [Accepted: 08/10/2007] [Indexed: 11/28/2022]
Abstract
Previously, the expression of caspase-3 siRNA could not effectively inhibit sodium butyrate (NaBu)-induced apoptotic cell death of recombinant Chinese hamster ovary (rCHO) cells producing human thrombopoietin (hTPO). Caspase-3 siRNA expressing cells appeared to compensate for the lack of caspase-3 by increasing active caspase-7 levels. For the successful inhibition of NaBu-induced apoptosis of rCHO cells, both caspase-3 and caspase-7 were down-regulated using the siRNA expression vector system. Co-down-regulation of caspase-3 and caspase-7 increased cell viability and extended culture longevity in serum-free culture in the presence or absence of 1mM NaBu addition. In the cultures with 1mM NaBu addition, the maximum hTPO concentration in rCHO cells with down-regulation of both caspases was approximately 55% higher than that in rCHO cells without down-regulation of caspases and approximately 16% higher than rCHO cells with down-regulation of only caspase-3. However, in the culture with 3mM NaBu, this strategy could not dramatically enhance the culture longevity and hTPO production, compared to Bcl-2 overexpression. The different result in hTPO production between down-regulation of caspases and Bcl-2 overexpression may be because the down-regulation of caspase-3 and caspase-7, unlike Bcl-2 overexpression, could not maintain mitochondrial membrane potential in the presence of 3mM NaBu. Taken together, co-down-regulation of caspase-3 and caspase-7 is effective in regard to extension of culture longevity and enhancement of hTPO production in a serum-free culture in the presence or absence of 1mM NaBu addition.
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Affiliation(s)
- Yun Hee Sung
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Daejon 305-701, Republic of Korea
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Savoia A, Dufour C, Locatelli F, Noris P, Ambaglio C, Rosti V, Zecca M, Ferrari S, di Bari F, Corcione A, Di Stazio M, Seri M, Balduini CL. Congenital amegakaryocytic thrombocytopenia: clinical and biological consequences of five novel mutations. Haematologica 2007; 92:1186-93. [PMID: 17666371 DOI: 10.3324/haematol.11425] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 06/27/2007] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, autosomal recessive disorder induced by mutations of the gene coding for thrombopoietin (TPO) receptor (c-MPL). Patients initially present with isolated thrombocytopenia that subsequently progresses into pancytopenia. Although the mechanisms leading to aplasia are unknown, the age of onset has been reported to depend on the severity of the c-MPL functional defect. To improve our knowledge in this field, we studied clinical and biological features of five new patients. DESIGN AND METHODS We diagnosed five CAMT patients, identified c-MPL mutations, including five novel alterations and investigated relationships between mutations and their clinical-biological consequences. RESULTS In all cases, platelet c-MPL and bone marrow colonies were reduced, while serum TPO levels were elevated. We also documented that the percentage of bone marrow cells expressing tumor necrosis factor-a and interferon-g was increased during pancytopenia as compared to in controls, suggesting that, as in other bone marrow failure diseases, these inhibitory cytokines contributed to the pancytopenia. Contrary to previously published data, we found no evidence of correlations between different types of mutations and the clinical course. INTERPRETATION AND CONCLUSIONS These results suggest that therapies, such as hematopoietic stem cell transplantation, which are potentially curative although associated with a risk of treatment-related mortality, should not be postponed even in those CAMT patients whose c-MPL mutations might predict residual activity of the TPO receptor.
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Affiliation(s)
- Anna Savoia
- Medical Genetics, Department of Reproductive and Developmental Science, IRCCS Burlo Garofolo Children's Hospital, University of Trieste, Italy
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Shimoda HK, Yamamoto M, Shide K, Kamezaki K, Matsuda T, Ogawa K, Harada M, Shimoda K. Chronic thrombopoietin overexpression induces mesangioproliferative glomerulopathy in mice. Am J Hematol 2007; 82:802-6. [PMID: 17546634 DOI: 10.1002/ajh.20970] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We previously reported that mice transgenic (Tg) for thrombopoietin (TPO) developed progressive fibrosis and osteosclerosis of the bone marrow. Here, we show that TPO-overexpressing mice also exhibited notable histological changes in the kidneys, including an increased number of mesangial cells, expansion of the mesangial matrix in the glomerulus, and atrophy of the renal tubuli. Plasma transforming growth factor (TGF)-beta1 and platelet-derived growth factor (PDGF)-BB, which could induce mesangioproliferative responses in glomeruli, were both elevated in TPO Tg mice, even though TPO itself has no effect on mesangial cells due to their lack of c-Mpl. The mesangial proliferative change in TPO Tg mice was thought to be induced by the elevation of these cytokines. In conclusion, our finding that TPO-overexpressing mice developed mesangioproliferative glomerulopathy might represent an undesirable effect of chronically elevated TPO in vivo, which should be taken into consideration before new TPO-like growth factors become available in clinical practice.
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Affiliation(s)
- Haruko K Shimoda
- Department of Internal Medicine, Gastroenterology and Hematology, Faculty of Medicine, Miyazaki University, Kiyotake, Miyazaki, Japan.
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Zhiyi H, Wenshan L, Wenze Z, Ning D, Chi Z, Kenan Y, Ping W, Qianqian W, Qing Z. Secretion expression and activity assay of a novel fusion protein of thrombopoietin and interleukin-6 in Pichia pastoris. J Biochem 2007; 142:17-24. [PMID: 17517790 DOI: 10.1093/jb/mvm111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Thrombopoietin (TPO) is an important haematopoietic factor in megakaryocytic activities as well as in platelet production. Interleukin 6 (IL-6) can co-stimulate TPO-dependent formation of colony forming unit of megakaryocyte (CFU-Meg) growth which could be responsible for residual platelet formation in TPO-deficient or c-mpl-deficient animals. In this report, we demonstrated the development of a high-level expression system to produce a 78-kDa human fusion protein IL-6/TPO (named ZH646). This was achieved by constructing the expression vector pPICZalpha-A-IL-6-linker-TPO, and obtained the recombinant yeast GS115, which then efficiently secreted into a medium with a yield of 30 mg/l from the supernatant of the yeast culture in flask. ZH646 was then purified using two steps via DEAE-Sephacel chromatography and Mono Q columns. Activity assay showed that ZH646 could significantly stimulate the formation of CFU-Meg and the proliferation of Dami cells in vitro in a dose-dependent manner. In addition, ZH646 also showed thrombopoietic effect in normal mice, and the ability to enhance recovery of normal platelet counts after myelosuppression mice. These results suggested that ZH646 is a novel protein, and its activities are much stronger than that of TPO or IL-6 alone. ZH646 therefore has a broad spectrum of megakaryopoiesis activity associated with platelet production.
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Affiliation(s)
- Hu Zhiyi
- National Key Discipline Department of Internal Medicine, The First School of Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, China
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31
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Zetterberg E, Vannucchi AM, Migliaccio AR, Vainchenker W, Tulliez M, Dickie R, Hasselbalch H, Rogers R, Palmblad J. Pericyte coverage of abnormal blood vessels in myelofibrotic bone marrows. Haematologica 2007; 92:597-604. [PMID: 17488682 DOI: 10.3324/haematol.11013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Myelofibrotic bone marrow displays abnormal angiogenesis but the pathogenic mechanisms of this are poorly understood. Since pericyte abnormalities are described on solid tumor vessels we studied whether vessel morphology and pericyte coverage in bone marrow samples from patients with myelofibrosis differed from that in samples from controls. DESIGN AND METHODS We assessed the microvascular density (MVD), vessel morphology and pericyte coverage in bone marrows from 19 myelofibrosis patients and nine controls. We also studied the same parameters in two mouse models of myelofibrosis, with genetic alterations affecting megakaryocyte differentiation (i.e. one model with low GATA-1 expression and the other with over-expression of thrombopoietin). RESULTS In myelofibrotic marrows, MVD was 3.8-fold greater than in controls (p<0.001) and vessels displayed 5.9-fold larger mean perimeters (p<0.001). MVD was 1.8-fold greater in JAK2 V617F-positive than in negative patients (p=0.026). Moreover, 92+/-11 % of vessels in patients with myelofibrosis were pericyte-coated but only 51+/-20 % of vessels in controls (p<0.001). In the two mouse models of myelofibrosis caused by targeting megakaryocytopoesis, wide, pericyte-coated and morphologically aberrant vessels were detected. MVD was significantly greater in bone marrow and spleen samples from animals with myelofibrosis than in wild-type mice. INTERPRETATION AND CONCLUSIONS We conclude that angiogenesis is similarly abnormal in human and murine myelofibrosis with intense pericyte coating, presumably related to abnormal megakaryocytopoiesis.
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Affiliation(s)
- Eva Zetterberg
- Division of Hematology and Center for Inflammation and Hematology Research, Department of Medicine, The Karolinska Institutet at Karolinska University Hospital, Huddinge, Stockholm, Sweden
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32
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Zhou XY, Tan MQ. Effect of Human Thrombopoietin-Modified Bone Marrow Mesenchymal Stem Cells Mediated by Recombinant Adeno-Associated Virus on Megakaryocytopoiesis. Stem Cells Dev 2007; 16:243-52. [PMID: 17521236 DOI: 10.1089/scd.2006.0111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recently, the research of recombinant thrombopoietin (TPO) and its subsequent use in treating thrombocytopenia following radiation therapy and chemotherapy have become more important in clinics. Our study was to determine the feasibility of recombinant adeno-associated virus (rAAV)-mediated TPO gene transfer into bone marrow-derived mesenchymal stem cells (MSCs) and to evaluate the conditioned medium (CM) obtained from TPO-transduced human (h) hMSCs for promoting the process of megakaryocytopoiesis. We constructed recombinant adeno-associated viruses expressing TPO successfully, and TPO mRNA and protein were both strongly expressed in TPO-transduced hMSCs. There was no decrease in green fluorescent protein (GFP) fluorescence expression of the transduced cells with continuous passaged culturing in vitro. The CM of TPO-transduced hMSCs has been shown to enhance the number of CD41(+) cells and megakaryocytic progenitors (colony-forming unit-megakaryocyte) significantly as compared to the nontransduced control. In this study, a novel safe and efficient method of promoting the megakaryocytopoiesis was established following the TPO-transduced hMSCs. These results provide a basis for the future studies on hematopoietic regulation by hMSCs transfected with TPO.
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Affiliation(s)
- Xiao-Ying Zhou
- Experimental Hematology Laboratory, Department of Physiology, Xiangya School of Medicine, Central South University, Changsha 410078, China
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33
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Teofili L, Giona F, Martini M, Cenci T, Guidi F, Torti L, Palumbo G, Amendola A, Foà R, Larocca LM. Markers of Myeloproliferative Diseases in Childhood Polycythemia Vera and Essential Thrombocythemia. J Clin Oncol 2007; 25:1048-53. [PMID: 17369568 DOI: 10.1200/jco.2006.08.6884] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Purpose Polycythemia vera (PV) and essential thrombocythemia (ET) can present in pediatric age as sporadic or familial diseases. To define the biologic profile of childhood PV and ET, we evaluated specific markers in a cohort of pediatric patients affected by PV and ET, including cases with familial occurrence. Patients and Methods Thirty-eight children with PV and ET were investigated. The control group included 58 adults with PV and ET. Endogenous erythroid colonies, qualitative reverse transcriptase polymerase chain reaction for polycythemia rubra vera-1 (PRV-1) RNA expression, human androgen receptor assay and allele specific polymerase chain reaction for JAK2 V617F mutation were undertaken in all patients. Thrombopoietin, thrombopoietin receptor (c-mpl), and erythropoietin receptor mutation analysis was performed by direct sequencing in familial cases. Results The JAK2 V617F mutation in children with PV was significantly less frequent than in adult PV. The most common myeloproliferative marker found in these patients was PRV-1 RNA overexpression. Children and adults with sporadic ET showed a similar proportion of patients with PRV-1 RNA overexpression, JAK2 V617F mutation, and clonality, while none of the familial ET showed JAK2 V617F mutation and clonality. Also, PRV-1 RNA overexpression was significantly less common. Furthermore, most patients with familial ET exhibited the dominant-positive activating mutation of c-mpl. Finally, children with PV and ET had a significant lower incidence of thrombosis than adults. Conclusion This study demonstrates that familial and sporadic ET recognize different pathogenetic mechanisms. Myeloproliferative markers are specific tests for the diagnosis of ET in children with sporadic forms, while a significant proportion of children with PV can prove negative.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Biomarkers/blood
- Child
- Cohort Studies
- Erythroid Precursor Cells/pathology
- Female
- Follow-Up Studies
- GPI-Linked Proteins
- Humans
- Incidence
- Isoantigens/blood
- Isoantigens/genetics
- Janus Kinase 2/blood
- Janus Kinase 2/genetics
- Male
- Membrane Glycoproteins/blood
- Membrane Glycoproteins/genetics
- Middle Aged
- Mutation
- Myeloproliferative Disorders/blood
- Myeloproliferative Disorders/genetics
- Pedigree
- Polycythemia Vera/blood
- Polycythemia Vera/complications
- Polycythemia Vera/genetics
- Polycythemia Vera/pathology
- RNA, Messenger/blood
- Receptors, Androgen/blood
- Receptors, Androgen/genetics
- Receptors, Cell Surface/blood
- Receptors, Cell Surface/genetics
- Receptors, Erythropoietin/blood
- Receptors, Erythropoietin/genetics
- Receptors, Thrombopoietin/blood
- Receptors, Thrombopoietin/genetics
- Rome/epidemiology
- Thrombocythemia, Essential/blood
- Thrombocythemia, Essential/complications
- Thrombocythemia, Essential/genetics
- Thrombocythemia, Essential/pathology
- Thrombopoietin/blood
- Thrombopoietin/genetics
- Thrombosis/epidemiology
- Thrombosis/etiology
- Time Factors
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Zang Y, Zhang X, Jiang X, Li H, Zhu J, Zhang C, Peng W, Qin J. Expression, refolding, and characterization of recombinant thrombopoietin/stem cell factor fusion protein in Escherichia coli. Appl Microbiol Biotechnol 2007; 74:836-42. [PMID: 17123074 DOI: 10.1007/s00253-006-0734-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 10/23/2006] [Accepted: 10/25/2006] [Indexed: 10/23/2022]
Abstract
Thrombopoietin/stem cell factor (TPO/SCF) is a novel fusion protein that combines the complementary biological effects of TPO and SCF into a single molecule. In this study, TPO/SCF gene was cloned into pET32a and expressed as a thioredoxin (Trx) fusion protein with a C-terminal 6His-tag in Escherichia coli BL21(DE3) under the control of T7 promoter. Trx-TPO/SCF protein approximately accounted for 20% of the total bacterial proteins and was found to accumulate in inclusion bodies. Inclusion bodies were separated from cellular debris, washed with buffer containing 2 M urea, and solubilized with 8 M urea. The refolding of Trx-TPO/SCF was then carried out by an on-column method. Soluble Trx-TPO/SCF was characterized for its dose-dependent effects on promoting cells proliferation in both TF1 and Mo7e cell lines. rhTPO/SCF was released by thrombin digestion and further purified by Ni(2+) affinity chromatography. Western blot analysis confirmed the identities of Trx-TPO/SCF and rhTPO/SCF.
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Affiliation(s)
- Yuhui Zang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing, PR China
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35
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Kosone T, Takagi H, Horiguchi N, Toyoda M, Sohara N, Kakizaki S, Sato K, Nishiyama U, Kuwaki T, Mori M. Hepatocyte growth factor accelerates thrombopoiesis in transgenic mice. J Transl Med 2007; 87:284-91. [PMID: 17260004 DOI: 10.1038/labinvest.3700514] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Hepatocyte growth factor (HGF) is one of the potent growth factors for liver regeneration and has a strong effect on epithelial and nonepithelial cells. As one of the pleiotropic functions, HGF acts as a hematopoietic regulator in the proliferation and differentiation of hematopoietic progenitors. However, the effect of HGF on the thrombopoietic function remains unclear. The correlation between HGF and thrombopoiesis was investigated in transgenic (TG) mice overexpressing murine HGF controlled by the murine HGF by the metallothionein promoter. Furthermore, the mechanism of thrombocytosis induced by HGF in vitro was analyzed in hepatoma cell line HepG2. Both the platelet count and the serum thrombopoietin (TPO) concentration were significantly higher in TG than in the wild type (WT) control mice. In the liver and spleen, the expression of TPOmRNA in TG was higher than that in WT by real-time polymerase chain reaction. The expressions of transcriptional factor of TPO, GABP-alpha/beta were more increased in TG liver compared to WT. In an in vitro study, HGF induced TPO and GABP-alpha/beta expression and enhanced TPO promoter activity. Therefore, HGF induced thrombopoiesis accompanied with the overexpression of TPO through GABP stimulation.
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Affiliation(s)
- Takashi Kosone
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Kopp HG, Hooper AT, Broekman MJ, Avecilla ST, Petit I, Luo M, Milde T, Ramos CA, Zhang F, Kopp T, Bornstein P, Jin DK, Marcus AJ, Rafii S. Thrombospondins deployed by thrombopoietic cells determine angiogenic switch and extent of revascularization. J Clin Invest 2007; 116:3277-91. [PMID: 17143334 PMCID: PMC1679710 DOI: 10.1172/jci29314] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 10/24/2006] [Indexed: 11/17/2022] Open
Abstract
Thrombopoietic cells may differentially promote or inhibit tissue vascularization by releasing both pro- and antiangiogenic factors. However, the molecular determinants controlling the angiogenic phenotype of thrombopoietic cells remain unknown. Here, we show that expression and release of thrombospondins (TSPs) by megakaryocytes and platelets function as a major antiangiogenic switch. TSPs inhibited thrombopoiesis, diminished bone marrow microvascular reconstruction following myelosuppression, and limited the extent of revascularization in a model of hind limb ischemia. We demonstrate that thrombopoietic recovery following myelosuppression was significantly enhanced in mice deficient in both TSP1 and TSP2 (TSP-DKO mice) in comparison with WT mice. Megakaryocyte and platelet levels in TSP-DKO mice were rapidly restored, thereby accelerating revascularization of myelosuppressed bone marrow and ischemic hind limbs. In addition, thrombopoietic cells derived from TSP-DKO mice were more effective in supporting neoangiogenesis in Matrigel plugs. The proangiogenic activity of TSP-DKO thrombopoietic cells was mediated through activation of MMP-9 and enhanced release of stromal cell-derived factor 1. Thus, TSP-deficient thrombopoietic cells function as proangiogenic agents, accelerating hemangiogenesis within the marrow and revascularization of ischemic hind limbs. As such, interference with the release of cellular stores of TSPs may be clinically effective in augmenting neoangiogenesis.
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Affiliation(s)
- Hans-Georg Kopp
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Andrea T. Hooper
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - M. Johan Broekman
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Scott T. Avecilla
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Isabelle Petit
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Min Luo
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Till Milde
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Carlos A. Ramos
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Fan Zhang
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Tabitha Kopp
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Paul Bornstein
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - David K. Jin
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Aaron J. Marcus
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
| | - Shahin Rafii
- Howard Hughes Medical Institute, Department of Genetic Medicine, Weill Medical College of Cornell University (WMCCU), New York, New York, USA.
Department of Hematology-Oncology, Eberhard-Karls University, Tubingen, Germany.
Divisions of Hematology/Medical Oncology, Medical and Research Service, VA New York Harbor Healthcare System, and Hematology/Medical Oncology, Department of Medicine, WMCCU, New York, New York, USA.
Department of Cell and Developmental Biology, WMCCU, New York, New York, USA.
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Departments of Biochemistry and Medicine, University of Washington, Seattle, Washington, USA.
Department of Pathology and Laboratory Medicine, WMCCU, New York, New York, USA
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37
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Gastinne T, Vigant F, Lavenu-Bombled C, Wagner-Ballon O, Tulliez M, Chagraoui H, Villeval JL, Lacout C, Perricaudet M, Vainchenker W, Benihoud K, Giraudier S. Adenoviral-mediated TGF-β1 inhibition in a mouse model of myelofibrosis inhibit bone marrow fibrosis development. Exp Hematol 2007; 35:64-74. [PMID: 17198875 DOI: 10.1016/j.exphem.2006.08.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 07/27/2006] [Accepted: 08/21/2006] [Indexed: 11/25/2022]
Abstract
Myelofibrosis is characterized by excessive deposits of extracellular matrix proteins, which occur as a marrow microenvironment reactive response to cytokines released from the clonal malignant myeloproliferation. The observation that mice exposed to high systemic levels of thrombopoietin (TPO) invariably developing myelofibrosis has allowed demonstration of the crucial role of transforming growth factor (TGF)-beta1 released by hematopoietic cells in the onset of myelofibrosis. The purpose of this study was to investigate whether TGF-beta1 inhibition could directly inhibit fibrosis development in a curative approach of this mice model. An adenovirus encoding for TGF-beta1 soluble receptor (TGF-beta-RII-Fc) was injected either shortly after transplantation (preventive) or 30 days post-transplantation (curative). Mice were transplanted with syngenic bone marrow cells transduced with a retrovirus encoding for murine TPO. All mice developed a myeloproliferative syndrome. TGF-beta-RII-Fc was detected in the blood of all treated mice, leading to a dramatic decrease in TGF-beta1 level. Histological analysis show that the two approaches (curative or preventive) were successful enough to inhibit bone marrow and spleen fibrosis development in this model. However, lethality of TPO overexpression was not decreased after treatment, indicating that in this mice model, myeloproliferation rather than fibrosis was probably responsible for the lethality induced by the disorder.
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Affiliation(s)
- Thomas Gastinne
- INSERM U790, Pavillon de recherche 1, Institut Gustave Roussy, Villejuif Cedex, France
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38
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Abstract
The human thrombopoietin (THPO) gene displays a series of alternative splicing events that provide valuable models for studying splicing mechanisms. The THPO region spanning exon 1–4 presents both alternative splicing of exon 2 and partial intron 2 (IVS2) retention following the activation of a cryptic 3′ splice site 85 nt upstream of the authentic acceptor site. IVS2 is particularly rich in stretches of 3–5 guanosines (namely, G1–G10) and we have characterized the role of these elements in the processing of this intron. In vivo studies show that runs G7–G10 work in a combinatorial way to control the selection of the proper 3′ splice site. In particular, the G7 element behaves as the splicing hub of intron 2 and its interaction with hnRNP H1 is critical for the splicing process. Removal of hnRNP H1 by RNA interference promoted the usage of the cryptic 3′ splice site so providing functional evidence that this factor is involved in the selection of the authentic 3′ splice site of THPO IVS2.
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Affiliation(s)
- Roberto Marcucci
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99I-34012, Trieste, Italy
| | - Francisco E. Baralle
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99I-34012, Trieste, Italy
- To whom correspondence should be addressed. Tel: +39 040 375 7337; Fax: +39 040 375 7361;
| | - Maurizio Romano
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99I-34012, Trieste, Italy
- Department of Physiology and Pathology, University of TriesteVia A. Fleming 22, 34127, Trieste, Italy
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39
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Abstract
Hereditary thrombocythaemia (HT) is an inherited autosomal dominant disorder. Recent studies reported six different mutations, four within the thrombopoietin (TPO) gene and two within c-Mpl (TPO receptor) gene in six unrelated families with HT. This study investigated the molecular basis of hereditary thrombocythaemia in an Israeli-Jewish family. We screened the genes for TPO and c-Mpl by amplification and sequencing of all the corresponding exons including exon/intron boundaries and promoters. In addition, plasma levels of TPO and erythropoietin (EPO) were measured. No abnormality in the TPO/c-Mpl genes has been identified in affected HT family members. Plasma TPO and EPO levels were found to be normal/low or normal respectively in the individuals affected. In conclusion, lack of a molecular lesion within either TPO or cMpl genes indicate that HT may be caused by factors other than TPO-cMpl axis in this family.
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Affiliation(s)
- N Tecuceanu
- Thrombosis and Haemostasis Unit, Beilinson Hospital, Rabin Medical Centre, Petah Tikva, Israel
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40
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Wagner-Ballon O, Chagraoui H, Prina E, Tulliez M, Milon G, Raslova H, Villeval JL, Vainchenker W, Giraudier S. Monocyte/macrophage dysfunctions do not impair the promotion of myelofibrosis by high levels of thrombopoietin. J Immunol 2006; 176:6425-33. [PMID: 16709799 DOI: 10.4049/jimmunol.176.11.6425] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Several lines of evidence indicate that the megakaryocyte/platelet lineage is crucial in myelofibrosis induction. The demonstration that NOD/SCID mice with functionally deficient monocytes do not develop fibrotic changes when exposed to thrombopoietin (TPO) also suggests an important role for monocyte/macrophages. However, in this animal model, the development of myelofibrosis is dependent on the level of TPO. This study was conducted to investigate whether NOD/SCID mice exposed to high TPO levels mediated by a retroviral vector would be refractory to the development of bone marrow fibrosis. We show that TPO and TGF-beta1 in plasma from NOD/SCID and SCID mice engrafted with TPO-overexpressing hemopoietic cells reach levels similar to the ones reached in immunocompetent mice, and all animals develop a myeloproliferative disease associated with a dense myelofibrosis at 8 wk posttransplantation. Monocytes in NOD/SCID mice are functionally deficient to secrete cytokines such as IL-1alpha in response to stimuli, even under TPO expression. Surprisingly, the plasma of these mice displays high levels of IL-alpha, which was demonstrated to originate from platelets. Together, these data suggest that completely functional monocytes are not required to develop myelofibrosis and that platelets are able, under TPO stimulation, to synthesize inflammatory cytokines, which may be involved in the pathogenesis of myelofibrosis and osteosclerosis.
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Affiliation(s)
- Orianne Wagner-Ballon
- Institut National de la Sante et de la Recherche Medicale (INSERM) U790, Pavillon de Recherche 1, Institut Gustave Roussy, Villejuif, France
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41
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Xie C, Jia B, Xiang Y, Wang L, Wang G, Huang G, McNiece IK, Wang J. Support of hMSCs transduced with TPO/FL genes to expansion of umbilical cord CD34+ cells in indirect co-culture. Cell Tissue Res 2006; 326:101-10. [PMID: 16685532 DOI: 10.1007/s00441-006-0203-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Accepted: 03/14/2006] [Indexed: 11/27/2022]
Abstract
A novel indirect co-culture system was established to support ex vivo expansion of hematopoietic progenitors in umbilical cord blood (UCB) by using thrombopoietin (TPO)/Flt-3 ligand (FL)-transduced human-marrow-derived mesenchymal stem cells (tfhMSCs) as a feeder. UCB CD34+ cells were isolated and cultured by using five culture systems in serum-containing or serum-free medium. Suitable aliquots of cultured cells were taken to monitor cell production, clonogenic activity, and long-term culture-initiating culture (LTC-IC) output. Finally, the severe-combined immunodeficient mouse (SCID) repopulating cell (SRC) assay was performed to confirm the ability of the indirect co-cultured cells from the tfhMSCs system to reconstitute long-term hematopoiesis. Results showed significant differences in the number of total nucleated cells (TNCs) among the culture systems with respect to serum-containing medium or serum-free medium during 14-day culture. In addition, on day 14, the outputs of CD34+ cells, the colony-forming units (CFUs) in culture, and the CFUs in mixed colonies containing erythroid and myeloid cells and megakaryocytes in the tfhMSC indirect co-culture system were significantly enhanced. The LTC-IC assay demonstrated that the tfhMSCs indirect co-culture system had the strongest activity. The SCID-SRC assay confirmed the extensive ability of the expanded cells from the tfhMSCs indirect co-culture systems to reconstitute long-term hematopoiesis. Furthermore, polymerase chain reaction analysis demonstrated the presence of human hematopoietic cells in the bone marrow and peripheral blood cells of non-obese diabetic/SCID mice. Thus, hMSCs transduced with TPO/FL, in combination with additive cytokines, can effectively expand hematopoietic progenitors from UCB in vitro. The tfhMSC indirect co-culture system may therefore be a suitable system for ex vivo manipulation of primitive progenitor cells under non-contact culture conditions.
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Affiliation(s)
- Chungang Xie
- College of Life Sciences, Zhejiang University, 232 Wen San Road, Hangzhou, Zhejiang Province, 310012, People's Republic of China
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42
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Stockklausner C, Breit S, Neu-Yilik G, Echner N, Hentze MW, Kulozik AE, Gehring NH. The uORF-containing thrombopoietin mRNA escapes nonsense-mediated decay (NMD). Nucleic Acids Res 2006; 34:2355-63. [PMID: 16679454 PMCID: PMC1458284 DOI: 10.1093/nar/gkl277] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Platelet production is induced by the cytokine thrombopoietin (TPO). It is physiologically critical that TPO expression is tightly regulated, because lack of TPO causes life-threatening thrombocytopenia while an excess of TPO results in thrombocytosis. The plasma concentration of TPO is controlled by a negative feedback loop involving receptor-mediated uptake of TPO by platelets. Furthermore, TPO biosynthesis is limited by upstream open reading frames (uORFs) that curtail the translation of the TPO mRNA. uORFs are suggested to activate RNA degradation by nonsense-mediated decay (NMD) in a number of physiological transcripts. Here, we determine whether NMD affects TPO expression. We show that reporter mRNAs bearing the seventh TPO uORF escape NMD. Importantly, endogenously expressed TPO mRNA from HuH7 cells is unaffected by abrogation of NMD by RNAi. Thus, regulation of TPO expression is independent of NMD, implying that mRNAs bearing uORFs cannot generally be considered to represent NMD targets.
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Affiliation(s)
- Clemens Stockklausner
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, 69120 Heidelberg, Germany
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43
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Jin DK, Shido K, Kopp HG, Petit I, Shmelkov SV, Young LM, Hooper AT, Amano H, Avecilla ST, Heissig B, Hattori K, Zhang F, Hicklin DJ, Wu Y, Zhu Z, Dunn A, Salari H, Werb Z, Hackett NR, Crystal RG, Lyden D, Rafii S. Cytokine-mediated deployment of SDF-1 induces revascularization through recruitment of CXCR4+ hemangiocytes. Nat Med 2006; 12:557-67. [PMID: 16648859 PMCID: PMC2754288 DOI: 10.1038/nm1400] [Citation(s) in RCA: 500] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Accepted: 03/31/2006] [Indexed: 12/29/2022]
Abstract
The mechanisms through which hematopoietic cytokines accelerate revascularization are unknown. Here, we show that the magnitude of cytokine-mediated release of SDF-1 from platelets and the recruitment of nonendothelial CXCR4+ VEGFR1+ hematopoietic progenitors, 'hemangiocytes,' constitute the major determinant of revascularization. Soluble Kit-ligand (sKitL), thrombopoietin (TPO, encoded by Thpo) and, to a lesser extent, erythropoietin (EPO) and granulocyte-macrophage colony-stimulating factor (GM-CSF) induced the release of SDF-1 from platelets, enhancing neovascularization through mobilization of CXCR4+ VEGFR1+ hemangiocytes. Although revascularization of ischemic hindlimbs was partially diminished in mice deficient in both GM-CSF and G-CSF (Csf2-/- Csf3-/-), profound impairment in neovascularization was detected in sKitL-deficient Mmp9-/- as well as thrombocytopenic Thpo-/- and TPO receptor-deficient (Mpl-/-) mice. SDF-1-mediated mobilization and incorporation of hemangiocytes into ischemic limbs were impaired in Thpo-/-, Mpl-/- and Mmp9-/- mice. Transplantation of CXCR4+ VEGFR1+ hemangiocytes into Mmp9-/- mice restored revascularization, whereas inhibition of CXCR4 abrogated cytokine- and VEGF-A-mediated mobilization of CXCR4+ VEGFR1+ cells and suppressed angiogenesis. In conclusion, hematopoietic cytokines, through graded deployment of SDF-1 from platelets, support mobilization and recruitment of CXCR4+ VEGFR1+ hemangiocytes, whereas VEGFR1 is essential for their angiogenic competency for augmenting revascularization. Delivery of SDF-1 may be effective in restoring angiogenesis in individuals with vasculopathies.
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Affiliation(s)
- David K Jin
- Department of Genetic Medicine, Division of Hematology-Medical Oncology, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10021, USA
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44
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Garner C, Best S, Menzel S, Rooks H, Spector TD, Thein SL. Two candidate genes for low platelet count identified in an Asian Indian kindred by genome-wide linkage analysis: glycoprotein IX and thrombopoietin. Eur J Hum Genet 2006; 14:101-8. [PMID: 16251900 DOI: 10.1038/sj.ejhg.5201499] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A genome-wide linkage analysis of platelet count was carried out in a large Asian Indian kindred. Linkage analysis showed one marker (D3S1309) on chromosome 3q with a lod score of 3.26 and another (D3S1282) approximately 30 cM centromeric, with a lod score of 2.52. Multipoint analysis of chromosome 3q identified two peaks with maximum multipoint lod scores of 3.52 and 4.11 under markers D3S1309 and D3S1282, respectively. Two strong candidate genes for platelet variation were identified in the linked region; thrombopoietin (THPO) and glycoprotein IX (GPIX). Resequencing of four individuals revealed five single-nucleotide polymorphisms (SNPs) in THPO and one mutation in the transmembrane region of GPIX. Analysis of variance showed that the GPIX mutation and one THPO SNP accounted for 6 and 4% of the variation in platelet count, respectively. The THPO SNP lies in the 3' untranslated region of the gene and has not been previously reported. The G to A transition at nucleotide 653 resulted in an Ala 156 (GCC) to Thr (ACC) replacement in the GPIX protein. The GPIX mutation was recently identified in a Chinese patient with Bernard-Soulier syndrome (BSS), a rare recessive bleeding disorder characterized by thrombocytopenia and giant platelets. One copy of the GPIX mutation was found in 300 European individuals with platelet counts within the normal range. The results suggest that two QTLs on chromosome 3q influence platelet count variation in the Asian Indian kindred, with the GPIX transmembrane mutation and the 3' UTR SNP in THPO being strong candidates.
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Affiliation(s)
- Chad Garner
- Epidemiology Division, Department of Medicine, University of California, Irvine, CA 92697-7550, USA.
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45
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Xie CG, Wang JF, Xiang Y, Qiu LY, Jia BB, Wang LJ, Wang GZ, Huang GP. Cocultivation of umbilical cord blood CD34 + cells with retro-transduced hMSCs leads to effective amplification of long-term culture-initiating cells. World J Gastroenterol 2006; 12:393-402. [PMID: 16489638 PMCID: PMC4066057 DOI: 10.3748/wjg.v12.i3.393] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To establish a novel coculture system for ex vivo expansion of umbilical cord blood(UCB) hematopoietic progenitors using thrombopoietin (TPO)/Flt-3 ligand (FL)-transduced human marrow-derived mesenchymal stem cells (tfhMSCs) as feeder.
METHODS: UCB CD34+ cells were isolated and cultured using four culture systems in serum-containing or serum-free medium. Suitable aliquots of cultured cells were used to monitor cell production, clonogenic activity, and long-term culture-initiating culture (LTC-IC) output. Finally, the severe-combined immunodeficient (SCID) mouse-repopulating cell (SRC) assay was performed to confirm ability of the cultured cells to reconstitute long-term hematopoiesis.
RESULTS: There were no significant differences in the number of total nucleated cells among different culture systems in serum-containing medium during 21-d culture. However, on d 14, the outputs of CD34+ cells, CFU-C and CFU-GEMM in tfhMSCs coculture system were significantly enhanced. LTC-IC assay demonstrated that the tfhMSCs coculture system had the most powerful activity. The severe-combined immunodeficient (SCID) mouse repopulating cell (SRC) assay confirmed extensive ability of the expanded cells to reconstitute long-term hematopoiesis. Furthermore, PCR analysis demonstrated the presence of human hematopoietic cells in the bone marrow and peripheral blood cells of NOD/SCID mice.
CONCLUSION: The TPO/FL-transduced hMSCs, in combination with additive cytokines, can effectively expand hematopoietic progenitors from UCB in vitro and the tfhMSCs coculture system may be a suitable system for ex vivo manipulation of primitive progenitor cells under contact culture conditions.
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Affiliation(s)
- Chun-Gang Xie
- College of Life Sciences, Zhejiang University, 232 Wen San Road, Hangzhou 310012, Zhejiang Province, China
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46
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Xie CG, Wang JF, Xiang Y, Jia BB, Qiu LY, Wang LJ, Wang GZ, Huang GP. Marrow mesenchymal stem cells transduced with TPO/FL genes as support for ex vivo expansion of hematopoietic stem/progenitor cells. Cell Mol Life Sci 2006; 62:2495-507. [PMID: 16231087 DOI: 10.1007/s00018-005-5274-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A new marrow-derived mesenchymal stem cell (hMSC) line that could support expansion of hematopoietic stem/progenitor cells (HSPCs) was developed. Primary hMSCs were infected with retrovirus containing Flt-3 ligand and thrombopoietin genes. CD34+ cells from cord blood were expanded with primary hMSCs or transduced hMSCs. The expansion of total nucleated cells, CD34+ cells and mixed colonies containing erythroid and myeloid cells and megakaryocytes for 2 weeks coculture with transduced hMSCs was remarkably increased. The outputs of long-term culture-initiating cells for 2 and 4 weeks coculture with transduced hMSCs were also largely increased. The expansion rates of HSPCs with transduced hMSCs were unchanged for 6 weeks. In contrast, the expansion rates of HSPCs with primary hMSCs declined drastically through 6 weeks. SCID-repopulating cell expansion with transduced hMSCs for 4 weeks was significantly higher than that of uncultured CD34,+ cells and HSPCs expanded with primary hMSCs.
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Affiliation(s)
- C-G Xie
- Institute of Stem Cell Biology, College of Life Sciences, Zhejiang University, 232 Wen San Road, Hangzhou 310012, P. R. China
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47
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Verhoeyen E, Wiznerowicz M, Olivier D, Izac B, Trono D, Dubart-Kupperschmitt A, Cosset FL. Novel lentiviral vectors displaying “early-acting cytokines” selectively promote survival and transduction of NOD/SCID repopulating human hematopoietic stem cells. Blood 2005; 106:3386-95. [PMID: 16076865 DOI: 10.1182/blood-2004-12-4736] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractA major limitation of current lentiviral vectors (LVs) is their inability to govern efficient gene transfer into quiescent cells, such as human CD34+ cells, that reside in the G0 phase of the cell cycle and that are highly enriched in hematopoietic stem cells. This hampers their application for gene therapy of hematopoietic cells. Here, we designed novel LVs that overcome this restriction by displaying “early-acting cytokines” on their surface. Display of thrombopoietin, stem cell factor, or both cytokines on the LV surface allowed efficient gene delivery into quiescent cord blood CD34+ cells. Moreover, these surface-engineered LVs preferentially transduced and promoted survival of resting CD34+ cells rather than cycling cells. Finally, and most importantly, these novel LVs allowed superior gene transfer in the most immature CD34+ cells as compared to conventional LVs, even when the latter vectors were used to transduce cells in the presence of recombinant cytokines. This was demonstrated by their capacity to promote selective transduction of CD34+ cell in in vitro derived long-term culture-initiating cell (LTC-IC) colonies and of long-term NOD/SCID repopulating cells (SRCs) in vivo.
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Lee DE, Son W, Ha BJ, Oh MS, Yoo OJ. The prolonged half-lives of new erythropoietin derivatives via peptide addition. Biochem Biophys Res Commun 2005; 339:380-5. [PMID: 16314154 DOI: 10.1016/j.bbrc.2005.11.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 11/07/2005] [Indexed: 11/29/2022]
Abstract
Erythropoietin, or Epo, is a hematopoietic cytokine that promotes erythropoiesis, and recombinant human Epo has been used in the treatment of anemia in various chronic diseases. Here, we have constructed novel Epo derivatives with prolonged half-lives by adding peptides to the carboxy terminus of Epo without using linkers. The fused peptides were selected from the carboxy terminal region of human chorionic gonadotropin (hCG) or human thrombopoietin (hTpo), which promote the proper folding, secretion, and stabilization of bioactive glycoproteins. Addition of these peptides did not interfere with secretion or receptor binding, and significantly increased the in vivo half-life of human Epo, as measured by intravenous administration in rats. The plasma half-life of the Epo constructs was longest when the carboxy terminal 28 aa of the beta subunit of hCG was added (Epo-CGC), a half-life that was slightly longer than NESP (Aranesp), which is the most effective Epo product in current clinical use. The transformation of four Ser glycosylation sites to Ala on the CGC sequence also lengthened the plasma half-life of Epo, indicating that the in vivo stabilizing effect of the hCG peptide was due to both structures within the peptide itself and its O-glycosylations. The application of the carboxy terminal half of hTpo also resulted in remarkably reduced elimination of the Epo chimera (Epo-TpC), possibly due to protection by the TpC sequence. The in vivo hematopoietic activity of Epo derivatives in mice was consistent with their pharmacokinetic profiles. Therefore, these derivatives with prolonged half-lives may provide opportunities for developing new Epo therapeutics with less frequent administration.
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Affiliation(s)
- Dong Eok Lee
- Biomedical Research Center, Department of Biological Science, Korea Advanced Institute of Science and Technology, Taejon 305-701, Republic of Korea
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Solberg LA. Biologic aspects of thrombopoietins and the development of therapeutic agents. Curr Hematol Rep 2005; 4:423-8. [PMID: 16232377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Thrombopoiesis is a multistage process beginning with pluripotent hematopoietic stem cells, progressing through proliferating cells committed to megakaryocytopoiesis, to megakaryocytes, and eventually ending with the shedding of platelets from megakaryocytes. Many growth factors stimulate thrombopoiesis; this review addresses those that act through binding to the thrombopoietin receptor. The cloning of thrombopoietin in 1994 greatly accelerated progress in understanding the biology of thrombopoiesis and of hematopoiesis in general. Detailed structural and functional studies of the thrombopoietin receptor, coupled with novel molecular pharmacology approaches, have led to new classes of thrombopoietic mimetics. Initial clinical trials with recombinant thrombopoietins faltered as they encountered significant neutralizing antibodies or difficulty finding a significant clinical niche in support of chemotherapy. Ongoing studies with the new thrombopoietic agents have invigorated the field, with positive results now reported in idiopathic thrombocytopenic purpura.
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Affiliation(s)
- Lawrence A Solberg
- Division of Hematology-Oncology, Comprehensive Cancer Center, Mayo Clinic, Jacksonville, FL 32224, USA.
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Abstract
The primary genetic lesion(s), as well as the biological processes responsible for the typical structural changes of the bone marrow microenvironment in idiopathic myelofibrosis, are still poorly understood, although a central role in disease pathogenesis has been attributed to the clonal proliferation and defective maturation of megakaryocytes. Two animal models of the disease have been described, that in the last few years significantly contributed to the elucidation of some of the pathogenetic steps of the human disease; these are represented by mice genetically modified to overexpress thrombopoietin and by knock-down mice with defective GATA-1 expression in megakaryocytes (GATA-1(low) mice). This review will outline these murine models, both characterized by extensive accumulation of megakaryocytes in hematopoietic tissues, and illustrate how they provided insights into the identification of some of the molecules and mechanisms responsible for the development of fibrosis and osteosclerosis that present major similarities with those observed in patients with idiopathic myelofibrosis.
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