Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
Nat Immunol ; 24(1): 69-83, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36522544

RESUMEN

The molecular regulation of human hematopoietic stem cell (HSC) maintenance is therapeutically important, but limitations in experimental systems and interspecies variation have constrained our knowledge of this process. Here, we have studied a rare genetic disorder due to MECOM haploinsufficiency, characterized by an early-onset absence of HSCs in vivo. By generating a faithful model of this disorder in primary human HSCs and coupling functional studies with integrative single-cell genomic analyses, we uncover a key transcriptional network involving hundreds of genes that is required for HSC maintenance. Through our analyses, we nominate cooperating transcriptional regulators and identify how MECOM prevents the CTCF-dependent genome reorganization that occurs as HSCs differentiate. We show that this transcriptional network is co-opted in high-risk leukemias, thereby enabling these cancers to acquire stem cell properties. Collectively, we illuminate a regulatory network necessary for HSC self-renewal through the study of a rare experiment of nature.


Asunto(s)
Leucemia , Neoplasias , Humanos , Células Madre Hematopoyéticas , Leucemia/genética , Factores de Transcripción/genética , Diferenciación Celular/genética
2.
Cell ; 165(6): 1530-1545, 2016 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-27259154

RESUMEN

Genome-wide association studies (GWAS) have successfully identified thousands of associations between common genetic variants and human disease phenotypes, but the majority of these variants are non-coding, often requiring genetic fine-mapping, epigenomic profiling, and individual reporter assays to delineate potential causal variants. We employ a massively parallel reporter assay (MPRA) to simultaneously screen 2,756 variants in strong linkage disequilibrium with 75 sentinel variants associated with red blood cell traits. We show that this assay identifies elements with endogenous erythroid regulatory activity. Across 23 sentinel variants, we conservatively identified 32 MPRA functional variants (MFVs). We used targeted genome editing to demonstrate endogenous enhancer activity across 3 MFVs that predominantly affect the transcription of SMIM1, RBM38, and CD164. Functional follow-up of RBM38 delineates a key role for this gene in the alternative splicing program occurring during terminal erythropoiesis. Finally, we provide evidence for how common GWAS-nominated variants can disrupt cell-type-specific transcriptional regulatory pathways.


Asunto(s)
Eritrocitos , Técnicas Genéticas , Variación Genética , Empalme Alternativo , Línea Celular , Linaje de la Célula/genética , Eritropoyesis/genética , Biblioteca de Genes , Genes Reporteros , Humanos , Secuencias Reguladoras de Ácidos Nucleicos , Transcripción Genética
3.
Nature ; 586(7831): 769-775, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33057200

RESUMEN

Myeloproliferative neoplasms (MPNs) are blood cancers that are characterized by the excessive production of mature myeloid cells and arise from the acquisition of somatic driver mutations in haematopoietic stem cells (HSCs). Epidemiological studies indicate a substantial heritable component of MPNs that is among the highest known for cancers1. However, only a limited number of genetic risk loci have been identified, and the underlying biological mechanisms that lead to the acquisition of MPNs remain unclear. Here, by conducting a large-scale genome-wide association study (3,797 cases and 1,152,977 controls), we identify 17 MPN risk loci (P < 5.0 × 10-8), 7 of which have not been previously reported. We find that there is a shared genetic architecture between MPN risk and several haematopoietic traits from distinct lineages; that there is an enrichment for MPN risk variants within accessible chromatin of HSCs; and that increased MPN risk is associated with longer telomere length in leukocytes and other clonal haematopoietic states-collectively suggesting that MPN risk is associated with the function and self-renewal of HSCs. We use gene mapping to identify modulators of HSC biology linked to MPN risk, and show through targeted variant-to-function assays that CHEK2 and GFI1B have roles in altering the function of HSCs to confer disease risk. Overall, our results reveal a previously unappreciated mechanism for inherited MPN risk through the modulation of HSC function.


Asunto(s)
Predisposición Genética a la Enfermedad/genética , Células Madre Hematopoyéticas/patología , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/patología , Neoplasias/genética , Neoplasias/patología , Linaje de la Célula/genética , Autorrenovación de las Células , Quinasa de Punto de Control 2/genética , Femenino , Humanos , Leucocitos/patología , Masculino , Proteínas Proto-Oncogénicas/genética , Proteínas Represoras/genética , Riesgo , Homeostasis del Telómero
4.
Nature ; 586(7831): 763-768, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33057201

RESUMEN

Age is the dominant risk factor for most chronic human diseases, but the mechanisms through which ageing confers this risk are largely unknown1. The age-related acquisition of somatic mutations that lead to clonal expansion in regenerating haematopoietic stem cell populations has recently been associated with both haematological cancer2-4 and coronary heart disease5-this phenomenon is termed clonal haematopoiesis of indeterminate potential (CHIP)6. Simultaneous analyses of germline and somatic whole-genome sequences provide the opportunity to identify root causes of CHIP. Here we analyse high-coverage whole-genome sequences from 97,691 participants of diverse ancestries in the National Heart, Lung, and Blood Institute Trans-omics for Precision Medicine (TOPMed) programme, and identify 4,229 individuals with CHIP. We identify associations with blood cell, lipid and inflammatory traits that are specific to different CHIP driver genes. Association of a genome-wide set of germline genetic variants enabled the identification of three genetic loci associated with CHIP status, including one locus at TET2 that was specific to individuals of African ancestry. In silico-informed in vitro evaluation of the TET2 germline locus enabled the identification of a causal variant that disrupts a TET2 distal enhancer, resulting in increased self-renewal of haematopoietic stem cells. Overall, we observe that germline genetic variation shapes haematopoietic stem cell function, leading to CHIP through mechanisms that are specific to clonal haematopoiesis as well as shared mechanisms that lead to somatic mutations across tissues.


Asunto(s)
Hematopoyesis Clonal/genética , Predisposición Genética a la Enfermedad , Genoma Humano/genética , Secuenciación Completa del Genoma , Adulto , África/etnología , Anciano , Anciano de 80 o más Años , Población Negra/genética , Autorrenovación de las Células/genética , Proteínas de Unión al ADN/genética , Dioxigenasas , Femenino , Mutación de Línea Germinal/genética , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Masculino , Persona de Mediana Edad , National Heart, Lung, and Blood Institute (U.S.) , Fenotipo , Medicina de Precisión , Proteínas Proto-Oncogénicas/genética , Proteínas de Motivos Tripartitos/genética , Estados Unidos , alfa Carioferinas/genética
5.
Trends Genet ; 36(8): 563-576, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32534791

RESUMEN

Genome-wide association studies (GWAS) have identified thousands of genetic variants associated with a range of human diseases and traits. However, understanding the mechanisms by which these genetic variants have an impact on associated diseases and traits, often referred to as the variant-to-function (V2F) problem, remains a significant hurdle. Solving the V2F challenge requires us to identify causative genetic variants, relevant cell types/states, target genes, and mechanisms by which variants can cause diseases or alter phenotypic traits. We discuss emerging functional approaches that are being applied to tackle the V2F problem for blood cell traits, illuminating how human genetic variation can impact on key mechanisms in hematopoiesis, as well as highlighting future prospects for this nascent field.


Asunto(s)
Predisposición Genética a la Enfermedad , Variación Genética , Enfermedades Hematológicas/genética , Hematopoyesis , Fenotipo , Sitios de Carácter Cuantitativo , Animales , Estudios de Asociación Genética , Estudio de Asociación del Genoma Completo , Enfermedades Hematológicas/sangre , Enfermedades Hematológicas/diagnóstico , Enfermedades Hematológicas/terapia , Humanos
7.
J Clin Immunol ; 40(4): 554-566, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32303876

RESUMEN

Studies of genetic blood disorders have advanced our understanding of the intrinsic regulation of hematopoiesis. However, such genetic studies have only yielded limited insights into how interactions between hematopoietic cells and their microenvironment are regulated. Here, we describe two affected siblings with infantile myelofibrosis and myeloproliferation that share a common de novo mutation in the Rho GTPase CDC42 (Chr1:22417990:C>T, p.R186C) due to paternal germline mosaicism. Functional studies using human cells and flies demonstrate that this CDC42 mutant has altered activity and thereby disrupts interactions between hematopoietic progenitors and key tissue microenvironmental factors. These findings suggest that further investigation of this and other related disorders may provide insights into how hematopoietic cell-microenvironment interactions play a role in human health and can be disrupted in disease. In addition, we suggest that deregulation of CDC42 may underlie more common blood disorders, such as primary myelofibrosis.


Asunto(s)
Mutación/genética , Mielofibrosis Primaria/diagnóstico , Proteína de Unión al GTP cdc42/genética , Ciclo Celular , Microambiente Celular , Células HEK293 , Hematopoyesis/genética , Humanos , Lactante , Recién Nacido , Mielofibrosis Primaria/genética , Hermanos , Secuenciación del Exoma
8.
Proc Natl Acad Sci U S A ; 114(3): E327-E336, 2017 01 17.
Artículo en Inglés | MEDLINE | ID: mdl-28031487

RESUMEN

Genetic variants affecting hematopoiesis can influence commonly measured blood cell traits. To identify factors that affect hematopoiesis, we performed association studies for blood cell traits in the population-based Estonian Biobank using high-coverage whole-genome sequencing (WGS) in 2,284 samples and SNP genotyping in an additional 14,904 samples. Using up to 7,134 samples with available phenotype data, our analyses identified 17 associations across 14 blood cell traits. Integration of WGS-based fine-mapping and complementary epigenomic datasets provided evidence for causal mechanisms at several loci, including at a previously undiscovered basophil count-associated locus near the master hematopoietic transcription factor CEBPA The fine-mapped variant at this basophil count association near CEBPA overlapped an enhancer active in common myeloid progenitors and influenced its activity. In situ perturbation of this enhancer by CRISPR/Cas9 mutagenesis in hematopoietic stem and progenitor cells demonstrated that it is necessary for and specifically regulates CEBPA expression during basophil differentiation. We additionally identified basophil count-associated variation at another more pleiotropic myeloid enhancer near GATA2, highlighting regulatory mechanisms for ordered expression of master hematopoietic regulators during lineage specification. Our study illustrates how population-based genetic studies can provide key insights into poorly understood cell differentiation processes of considerable physiologic relevance.


Asunto(s)
Proteínas Potenciadoras de Unión a CCAAT/genética , Hematopoyesis/genética , Secuencia de Bases , Basófilos/citología , Diferenciación Celular/genética , Linaje de la Célula/genética , Mapeo Cromosómico , Bases de Datos de Ácidos Nucleicos , Elementos de Facilitación Genéticos , Epigénesis Genética , Estonia , Femenino , Factor de Transcripción GATA2/genética , Regulación del Desarrollo de la Expresión Génica , Estudio de Asociación del Genoma Completo , Humanos , Recuento de Leucocitos , Masculino , Polimorfismo de Nucleótido Simple , Secuenciación Completa del Genoma
9.
Br J Haematol ; 173(2): 206-18, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26846448

RESUMEN

Red blood cells (RBCs) are generated from haematopoietic stem and progenitor cells (HSPCs) through the step-wise process of differentiation known as erythropoiesis. In this review, we discuss our current understanding of erythropoiesis and highlight recent advances in this field. During embryonic development, erythropoiesis occurs in three distinct waves comprising first, the yolk sac-derived primitive RBCs, followed sequentially by the erythro-myeloid progenitor (EMP) and HSPC-derived definitive RBCs. Recent work has highlighted the complexity and variability that may exist in the hierarchical arrangement of progenitors responsible for erythropoiesis. Using recently defined cell surface markers, it is now possible to enrich for erythroid progenitors and precursors to a much greater extent than has been possible before. While a great deal of knowledge has been gained on erythropoiesis from model organisms, our understanding of this process is currently being refined through human genetic studies. Genes mutated in erythroid disorders can now be identified more rapidly by the use of next-generation sequencing techniques. Genome-wide association studies on erythroid traits in healthy populations have also revealed new modulators of erythropoiesis. All of these recent developments have significant promise not only for increasing our understanding of erythropoiesis, but also for improving our ability to intervene when RBC production is perturbed in disease.


Asunto(s)
Eritropoyesis/fisiología , Animales , Comunicación Celular/fisiología , Diferenciación Celular/fisiología , Desarrollo Embrionario/fisiología , Eritropoyesis/genética , Enfermedades Hematológicas/fisiopatología , Células Madre Hematopoyéticas/fisiología , Hemoglobinas/fisiología , Xenoinjertos/fisiología , Humanos , Ratones , Modelos Biológicos , Transcripción Genética/fisiología , Pez Cebra
10.
Nat Commun ; 14(1): 5536, 2023 09 08.
Artículo en Inglés | MEDLINE | ID: mdl-37684235

RESUMEN

Clonal hematopoiesis (CH)-age-related expansion of mutated hematopoietic clones-can differ in frequency and cellular fitness by CH type (e.g., mutations in driver genes (CHIP), gains/losses and copy-neutral loss of chromosomal segments (mCAs), and loss of sex chromosomes). Co-occurring CH raises questions as to their origin, selection, and impact. We integrate sequence and genotype array data in up to 482,378 UK Biobank participants to demonstrate shared genetic architecture across CH types. Our analysis suggests a cellular evolutionary trade-off between different types of CH, with LOY occurring at lower rates in individuals carrying mutations in established CHIP genes. We observed co-occurrence of CHIP and mCAs with overlap at TET2, DNMT3A, and JAK2, in which CHIP precedes mCA acquisition. Furthermore, individuals carrying overlapping CH had high risk of future lymphoid and myeloid malignancies. Finally, we leverage shared genetic architecture of CH traits to identify 15 novel loci associated with leukemia risk.


Asunto(s)
Evolución Biológica , Hematopoyesis Clonal , Humanos , Hematopoyesis Clonal/genética , Genotipo , Células Clonales , Metilasas de Modificación del ADN
11.
Nat Commun ; 12(1): 4991, 2021 08 17.
Artículo en Inglés | MEDLINE | ID: mdl-34404810

RESUMEN

Key mechanisms of fetal hemoglobin (HbF) regulation and switching have been elucidated through studies of human genetic variation, including mutations in the HBG1/2 promoters, deletions in the ß-globin locus, and variation impacting BCL11A. While this has led to substantial insights, there has not been a unified understanding of how these distinct genetically-nominated elements, as well as other key transcription factors such as ZBTB7A, collectively interact to regulate HbF. A key limitation has been the inability to model specific genetic changes in primary isogenic human hematopoietic cells to uncover how each of these act individually and in aggregate. Here, we describe a single-cell genome editing functional assay that enables specific mutations to be recapitulated individually and in combination, providing insights into how multiple mutation-harboring functional elements collectively contribute to HbF expression. In conjunction with quantitative modeling and chromatin capture analyses, we illustrate how these genetic findings enable a comprehensive understanding of how distinct regulatory mechanisms can synergistically modulate HbF expression.


Asunto(s)
Edición Génica , Hemoglobinas/genética , Hemoglobinas/metabolismo , Sistemas CRISPR-Cas , Cromatina , Cromosomas , Proteínas de Unión al ADN/metabolismo , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Expresión Génica , Globinas , Humanos , Mutación , Proteínas Represoras , Factores de Transcripción/metabolismo , Globinas beta/genética
12.
Nat Genet ; 52(12): 1333-1345, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33230299

RESUMEN

Genome-wide association studies identify genomic variants associated with human traits and diseases. Most trait-associated variants are located within cell-type-specific enhancers, but the molecular mechanisms governing phenotypic variation are less well understood. Here, we show that many enhancer variants associated with red blood cell (RBC) traits map to enhancers that are co-bound by lineage-specific master transcription factors (MTFs) and signaling transcription factors (STFs) responsive to extracellular signals. The majority of enhancer variants reside on STF and not MTF motifs, perturbing DNA binding by various STFs (BMP/TGF-ß-directed SMADs or WNT-induced TCFs) and affecting target gene expression. Analyses of engineered human blood cells and expression quantitative trait loci verify that disrupted STF binding leads to altered gene expression. Our results propose that the majority of the RBC-trait-associated variants that reside on transcription-factor-binding sequences fall in STF target sequences, suggesting that the phenotypic variation of RBC traits could stem from altered responsiveness to extracellular stimuli.


Asunto(s)
Eritrocitos/fisiología , Regulación de la Expresión Génica/genética , Fenotipo , Polimorfismo de Nucleótido Simple/genética , Factores de Transcripción/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Elementos de Facilitación Genéticos/genética , Eritrocitos/citología , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Humanos , Sitios de Carácter Cuantitativo/genética , Proteína Smad1/genética , Proteína Smad1/metabolismo , Factores de Transcripción/metabolismo , Transcripción Genética/genética
13.
Cell Rep ; 27(11): 3228-3240.e7, 2019 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-31189107

RESUMEN

Human erythropoiesis serves as a paradigm of physiologic cellular differentiation. This process is also of considerable interest for better understanding anemias and identifying new therapies. Here, we apply deep transcriptomic and accessible chromatin profiling to characterize a faithful ex vivo human erythroid differentiation system from hematopoietic stem and progenitor cells. We reveal stage-specific transcriptional states and chromatin accessibility during various stages of erythropoiesis, including 14,260 differentially expressed genes and 63,659 variably accessible chromatin peaks. Our analysis suggests differentiation stage-predominant roles for specific master regulators, including GATA1 and KLF1. We integrate chromatin profiles with common and rare genetic variants associated with erythroid cell traits and diseases, finding that variants regulating different erythroid phenotypes likely act at variable points during differentiation. In addition, we identify a regulator of terminal erythropoiesis, TMCC2, more broadly illustrating the value of this comprehensive analysis to improve our understanding of erythropoiesis in health and disease.


Asunto(s)
Ensamble y Desensamble de Cromatina , Eritropoyesis , Transcriptoma , Anciano , Células Cultivadas , Cromatina/química , Cromatina/metabolismo , Células Precursoras Eritroides/citología , Células Precursoras Eritroides/metabolismo , Femenino , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Células HEK293 , Humanos , Factores de Transcripción de Tipo Kruppel/genética , Factores de Transcripción de Tipo Kruppel/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple
14.
Elife ; 82019 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-31070582

RESUMEN

Genome-wide association studies (GWAS) have identified thousands of variants associated with human diseases and traits. However, the majority of GWAS-implicated variants are in non-coding regions of the genome and require in depth follow-up to identify target genes and decipher biological mechanisms. Here, rather than focusing on causal variants, we have undertaken a pooled loss-of-function screen in primary hematopoietic cells to interrogate 389 candidate genes contained in 75 loci associated with red blood cell traits. Using this approach, we identify 77 genes at 38 GWAS loci, with most loci harboring 1-2 candidate genes. Importantly, the hit set was strongly enriched for genes validated through orthogonal genetic approaches. Genes identified by this approach are enriched in specific and relevant biological pathways, allowing regulators of human erythropoiesis and modifiers of blood diseases to be defined. More generally, this functional screen provides a paradigm for gene-centric follow up of GWAS for a variety of human diseases and traits.


Asunto(s)
Enfermedades Genéticas Congénitas , Predisposición Genética a la Enfermedad , Hematopoyesis/genética , Sitios de Carácter Cuantitativo/genética , Eritrocitos/metabolismo , Eritrocitos/patología , Estudio de Asociación del Genoma Completo , Humanos , Polimorfismo de Nucleótido Simple/genética
15.
Exp Hematol ; 43(7): 565-77.e1-10, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25907033

RESUMEN

The transcription factor GATA2 is highly expressed in hematopoietic stem cells and is downregulated during lineage maturation. Gain of function mutations, loss of function mutations, and overexpression of GATA2 have been reported in acute myeloid leukemia. In previous studies, we and others showed that GATA2 overexpression at high levels, similar to that seen in hematopoietic stem cells, blocked differentiation of hematopoietic stem cells and progenitors. To better understand the effects of GATA2, we designed a Tamoxifen-inducible GATA2-estrogen receptor (ERT) vector. In the absence of Tamoxifen, small amounts of GATA2-ERT were still able to enter the nucleus in mouse bone marrow (BM) cells, providing us with a tool to test the effects of low-level GATA2 overexpression. We observed that this low-level GATA2 overexpression enhanced self-renewal of myeloid progenitors in vitro and resulted in immortalization of BM cells to myeloid cell lines. Continuous GATA2-ERT expression was required for the proliferation of these immortalized lines. Myeloid expansion and a block in T and B lineage differentiation were observed in mice transplanted with GATA2-ERT-expressing BM cells. Myeloid expansion occurred after the granulocyte monocyte progenitor stage, and lymphoid block was distal to the common lymphoid progenitor in transgenic mice. GATA2 appeared to induce growth via downstream activation of Nmyc and Hoxa9. Our results demonstrate that GATA2 overexpression at low level confers self-renewal capacity to myeloid progenitors and is relevant to myeloid leukemia development.


Asunto(s)
Células de la Médula Ósea/patología , Transformación Celular Neoplásica/genética , Factor de Transcripción GATA2/fisiología , Regulación Leucémica de la Expresión Génica , Linfopoyesis/genética , Células Mieloides/patología , Mielopoyesis/genética , Animales , Linfocitos B/patología , Células de la Médula Ósea/metabolismo , División Celular , Núcleo Celular/metabolismo , Células Cultivadas , Ensayo de Unidades Formadoras de Colonias , Factor de Transcripción GATA2/genética , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Genes Sintéticos , Genes myc , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Proteínas de Homeodominio/genética , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación , Células Mieloides/metabolismo , Receptores de Estrógenos/genética , Proteínas Recombinantes de Fusión/metabolismo , Linfocitos T/patología , Tamoxifeno/farmacología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA