RESUMO
Hematopoiesis, a process which generates blood and immune cells, changes significantly during mammalian development. Definitive hematopoiesis is marked by the emergence of long-term hematopoietic stem cells (HSCs). Here, we will focus on the post-transcriptional differences between fetal liver (FL) and adult bone marrow (ABM) HSCs. It remains unclear how or why exactly FL HSCs transition to ABM HSCs, but we aim to leverage their differences to revive an old idea: in utero HSC transplantation. Unexpectedly, the expression of certain RNA-binding proteins (RBPs) play an important role in HSC specification, and can be employed to convert or reprogram adult HSCs back to a fetal-like state. Among other features, FL HSCs have a broad differentiation capacity that includes the ability to regenerate both conventional B and T cells, as well as innate-like or unconventional lymphocytes such as B-1a and marginal zone B (MzB) cells. This chapter will focus on RNA binding proteins, namely LIN28B and IGF2BP3, that are expressed during fetal life and how they promote B-1a cell development. Furthermore, this chapter considers a potential clinical application of synthetic co-expression of LIN28B and IGF2BP3 in HSCs.
Assuntos
Linfócitos B , Células-Tronco Hematopoéticas , Proteínas de Ligação a RNA , Humanos , Animais , Proteínas de Ligação a RNA/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Linfócitos B/imunologia , Linfócitos B/metabolismo , Diferenciação Celular , Hematopoese , Processamento Pós-Transcricional do RNA , Linfopoese/genética , Transplante de Células-Tronco HematopoéticasRESUMO
Mitotically stable random monoallelic gene expression (RME) is documented for a small percentage of autosomal genes. We developed an in vivo genetic model to study the role of enhancers in RME using high-resolution single-cell analysis of natural killer (NK) cell receptor gene expression and enhancer deletions in the mouse germline. Enhancers of the RME NK receptor genes were accessible and enriched in H3K27ac on silent and active alleles alike in cells sorted according to allelic expression status, suggesting enhancer activation and gene expression status can be decoupled. In genes with multiple enhancers, enhancer deletion reduced gene expression frequency, in one instance converting the universally expressed gene encoding NKG2D into an RME gene, recapitulating all aspects of natural RME including mitotic stability of both the active and silent states. The results support the binary model of enhancer action, and suggest that RME is a consequence of general properties of gene regulation by enhancers rather than an RME-specific epigenetic program. Therefore, many and perhaps all genes may be subject to some degree of RME. Surprisingly, this was borne out by analysis of several genes that define different major hematopoietic lineages, that were previously thought to be universally expressed within those lineages: the genes encoding NKG2D, CD45, CD8α, and Thy-1. We propose that intrinsically probabilistic gene allele regulation is a general property of enhancer-controlled gene expression, with previously documented RME representing an extreme on a broad continuum.
Assuntos
Subfamília K de Receptores Semelhantes a Lectina de Células NK , Sequências Reguladoras de Ácido Nucleico , Alelos , Animais , Cromossomos , Elementos Facilitadores Genéticos/genética , Regulação da Expressão Gênica , CamundongosRESUMO
Suppressive regulatory T cell (Treg) differentiation is controlled by diverse immunometabolic signaling pathways and intracellular metabolites. Here we show that cell-permeable α-ketoglutarate (αKG) alters the DNA methylation profile of naive CD4 T cells activated under Treg polarizing conditions, markedly attenuating FoxP3+ Treg differentiation and increasing inflammatory cytokines. Adoptive transfer of these T cells into tumor-bearing mice results in enhanced tumor infiltration, decreased FoxP3 expression, and delayed tumor growth. Mechanistically, αKG leads to an energetic state that is reprogrammed toward a mitochondrial metabolism, with increased oxidative phosphorylation and expression of mitochondrial complex enzymes. Furthermore, carbons from ectopic αKG are directly utilized in the generation of fatty acids, associated with lipidome remodeling and increased triacylglyceride stores. Notably, inhibition of either mitochondrial complex II or DGAT2-mediated triacylglyceride synthesis restores Treg differentiation and decreases the αKG-induced inflammatory phenotype. Thus, we identify a crosstalk between αKG, mitochondrial metabolism and triacylglyceride synthesis that controls Treg fate.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Ácidos Cetoglutáricos/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacos , Animais , Células Cultivadas , Citocinas/genética , Citocinas/metabolismo , Diacilglicerol O-Aciltransferase/metabolismo , Fibrossarcoma/genética , Fibrossarcoma/imunologia , Fibrossarcoma/metabolismo , Fibrossarcoma/terapia , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Homeostase , Humanos , Imunoterapia Adotiva , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/metabolismo , Fenótipo , Receptores de Antígenos Quiméricos/genética , Receptores de Antígenos Quiméricos/metabolismo , Transdução de Sinais , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Linfócitos T Reguladores/transplante , Células Th1/efeitos dos fármacos , Células Th1/imunologia , Células Th1/metabolismoRESUMO
MicroRNAs are important regulators of immune responses. Here, we show miR-221 and miR-222 modulate the intestinal Th17 cell response. Expression of miR-221 and miR-222 was induced by proinflammatory cytokines and repressed by the cytokine TGF-ß. Molecular targets of miR-221 and miR-222 included Maf and Il23r, and loss of miR-221 and miR-222 expression shifted the transcriptomic spectrum of intestinal Th17 cells to a proinflammatory signature. Although the loss of miR-221 and miR-222 was tolerated for maintaining intestinal Th17 cell homeostasis in healthy mice, Th17 cells lacking miR-221 and miR-222 expanded more efficiently in response to IL-23. Both global and T cell-specific deletion of miR-221 and miR-222 rendered mice prone to mucosal barrier damage. Collectively, these findings demonstrate that miR-221 and miR-222 are an integral part of intestinal Th17 cell response that are induced after IL-23 stimulation to constrain the magnitude of proinflammatory response.
Assuntos
Inflamação/imunologia , Interleucina-23/metabolismo , Mucosa Intestinal/imunologia , MicroRNAs/genética , Células Th17/imunologia , Animais , Retroalimentação Fisiológica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Proto-Oncogênicas c-maf/metabolismo , Receptores de Interleucina/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismoRESUMO
Bone marrow transplantation (BMT) or hematopoietic stem cell transplantation (HSCT) is an archetype of cellular therapy. However, to date BMT still suffers from several complications. Recent technological advances have encouraged us to think about an alternative to traditional BMT. Specifically, we propose in utero HSCT (IUHSCT). For this purpose, we suggest that induced fetal-like hematopoietic stem cells (ifHSCs) might be suitable for IUHSCT, and should be seriously evaluated.
RESUMO
Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) is an oncofetal protein expressed in various cancers including leukemia. In this study, we assessed the role of IGF2BP1 in orchestrating leukemia stem cell properties. Tumor-initiating potential, sensitivity to chemotherapeutic agents, and expression of cancer stem cell markers were assessed in a panel of myeloid, B-, and T-cell leukemia cell lines using gain- and loss-of-function systems, cross-linking immunoprecipitation (CLIP), and photoactivatable ribonucleoside-enhanced cross-linking and immunoprecipitation (PAR-CLIP) techniques. Here, we report that genetic or chemical inhibition of IGF2BP1 decreases leukemia cells' tumorigenicity, promotes myeloid differentiation, increases leukemia cell death, and sensitizes leukemia cells to chemotherapeutic drugs. IGF2BP1 affects proliferation and tumorigenic potential of leukemia cells through critical regulators of self-renewal HOXB4 and MYB and through regulation of expression of the aldehyde dehydrogenase, ALDH1A1. Our data indicate that IGF2BP1 maintains leukemia stem cell properties by regulating multiple pathways of stemness through transcriptional and metabolic factors.
Assuntos
Família Aldeído Desidrogenase 1/metabolismo , Regulação Leucêmica da Expressão Gênica , Proteínas de Homeodomínio/metabolismo , Leucemia Mieloide Aguda/patologia , Células-Tronco Neoplásicas/patologia , Proteínas Oncogênicas v-myb/metabolismo , Proteínas de Ligação a RNA/metabolismo , Retinal Desidrogenase/metabolismo , Fatores de Transcrição/metabolismo , Família Aldeído Desidrogenase 1/genética , Animais , Antineoplásicos/farmacologia , Apoptose , Biomarcadores Tumorais , Proliferação de Células , Resistencia a Medicamentos Antineoplásicos , Feminino , Proteínas de Homeodomínio/genética , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Camundongos , Camundongos SCID , Células-Tronco Neoplásicas/metabolismo , Proteínas Oncogênicas v-myb/genética , Proteínas de Ligação a RNA/genética , Retinal Desidrogenase/genética , Fatores de Transcrição/genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Fetal hematopoietic stem and progenitor cells (HSPCs) hold promise to cure a wide array of hematological diseases, and we previously found a role for the RNA-binding protein (RBP) Lin28b in respecifying adult HSPCs to resemble their fetal counterparts. Here we show by single-cell RNA sequencing that Lin28b alone was insufficient for complete reprogramming of gene expression from the adult toward the fetal pattern. Using proteomics and in situ analyses, we found that Lin28b (and its closely related paralog, Lin28a) directly interacted with Igf2bp3, another RBP, and their enforced co-expression in adult HSPCs reactivated fetal-like B-cell development in vivo more efficiently than either factor alone. In B-cell progenitors, Lin28b and Igf2bp3 jointly stabilized thousands of mRNAs by binding at the same sites, including those of the B-cell regulators Pax5 and Arid3a as well as Igf2bp3 mRNA itself, forming an autoregulatory loop. Our results suggest that Lin28b and Igf2bp3 are at the center of a gene regulatory network that mediates the fetal-adult hematopoietic switch. A method to efficiently generate induced fetal-like hematopoietic stem cells (ifHSCs) will facilitate basic studies of their biology and possibly pave a path toward their clinical application.
Assuntos
Reprogramação Celular/genética , Proteínas de Ligação a DNA/metabolismo , Redes Reguladoras de Genes , Células-Tronco Hematopoéticas/fisiologia , Proteínas de Ligação a RNA/metabolismo , Animais , Sítios de Ligação , Células Cultivadas , Proteínas de Ligação a DNA/genética , Camundongos , MicroRNAs/metabolismo , Modelos Animais , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genéticaRESUMO
T cell senescence and exhaustion are major barriers to successful cancer immunotherapy. Here we show that miR-155 increases CD8+ T cell antitumor function by restraining T cell senescence and functional exhaustion through epigenetic silencing of drivers of terminal differentiation. miR-155 enhances Polycomb repressor complex 2 (PRC2) activity indirectly by promoting the expression of the PRC2-associated factor Phf19 through downregulation of the Akt inhibitor, Ship1. Phf19 orchestrates a transcriptional program extensively shared with miR-155 to restrain T cell senescence and sustain CD8+ T cell antitumor responses. These effects rely on Phf19 histone-binding capacity, which is critical for the recruitment of PRC2 to the target chromatin. These findings establish the miR-155-Phf19-PRC2 as a pivotal axis regulating CD8+ T cell differentiation, thereby paving new ways for potentiating cancer immunotherapy through epigenetic reprogramming of CD8+ T cell fate.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Melanoma Experimental/imunologia , MicroRNAs/metabolismo , Neoplasias Cutâneas/imunologia , Fatores de Transcrição/metabolismo , Transferência Adotiva/métodos , Animais , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/transplante , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Senescência Celular/genética , Senescência Celular/imunologia , Epigênese Genética/imunologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Melanoma Experimental/genética , Melanoma Experimental/terapia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases/genética , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases/metabolismo , Complexo Repressor Polycomb 2/imunologia , Complexo Repressor Polycomb 2/metabolismo , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/terapia , Fatores de Transcrição/genética , Fatores de Transcrição/imunologiaRESUMO
How a single genome can give rise to many different transcriptomes and thus all the different cell lineages in the human body is a fundamental question in biology. While signaling pathways, transcription factors, and chromatin architecture, to name a few determinants, have been established to play critical roles, recently, there is a growing appreciation of the roles of non-coding RNAs and RNA-binding proteins in controlling cell fates posttranscriptionally. Thus, it is vital that these emerging players are also integrated into models of gene regulatory networks that underlie programs of cellular differentiation. Sometimes, we can leverage knowledge about such posttranscriptional circuits to reprogram patterns of gene expression in meaningful ways. Here, we review three examples from our work.
Assuntos
Diferenciação Celular/genética , Reprogramação Celular/genética , Processamento Pós-Transcricional do RNA , Células-Tronco/citologia , Células-Tronco/metabolismo , Animais , Cromatina , Hematopoese/genética , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Células Th17/citologia , Células Th17/imunologia , Células Th17/metabolismoRESUMO
Recognition and elimination of tumor cells by the immune system is crucial for limiting tumor growth. Natural killer (NK) cells become activated when the receptor NKG2D is engaged by ligands that are frequently upregulated in primary tumors and on cancer cell lines. However, the molecular mechanisms driving NKG2D ligand expression on tumor cells are not well defined. Using a forward genetic screen in a tumor-derived human cell line, we identified several novel factors supporting expression of the NKG2D ligand ULBP1. Our results show stepwise contributions of independent pathways working at multiple stages of ULBP1 biogenesis. Deeper investigation of selected hits from the screen showed that the transcription factor ATF4 drives ULBP1 gene expression in cancer cell lines, while the RNA-binding protein RBM4 supports ULBP1 expression by suppressing a novel alternatively spliced isoform of ULBP1 mRNA. These findings offer insight into the stress pathways that alert the immune system to danger.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Células Matadoras Naturais/imunologia , Ativação Linfocitária , Fator 4 Ativador da Transcrição/metabolismo , Linhagem Celular Tumoral , Proteínas Ligadas por GPI/genética , Proteínas Ligadas por GPI/metabolismo , Testes Genéticos , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Subfamília K de Receptores Semelhantes a Lectina de Células NK/metabolismo , Proteínas de Ligação a RNA/metabolismoRESUMO
Differentiation of CD4(+) helper and CD8(+) cytotoxic αß T cells from CD4(+)CD8(+) thymocytes involves upregulation of lineage-specifying transcription factors and transcriptional silencing of CD8 or CD4 coreceptors, respectively, in MHC class II or I (MHCII or I)-restricted thymocytes. In this study, we demonstrate that inactivation of the Dicer RNA endonuclease in murine thymocytes impairs initiation of Cd4 and Cd8 silencing, leading to development of positively selected MHCI- and MHCII-restricted mature CD4(+)CD8(+) thymocytes. Expression of the antiapoptotic BCL2 protein or inactivation of the p53 proapoptotic protein rescues these thymocytes from apoptosis, increasing their frequency and permitting accumulation of CD4(+)CD8(+) αß T cells in the periphery. Dicer-deficient MHCI-restricted αß T cells fail to normally silence Cd4 and display impaired induction of the CD8 lineage-specifying transcription factor Runx3, whereas Dicer-deficient MHCII-restricted αß T cells show impaired Cd8 silencing and impaired induction of the CD4 lineage-specifying transcription factor Thpok. Finally, we show that the Drosha RNA endonuclease, which functions upstream of Dicer in microRNA biogenesis, also regulates Cd4 and Cd8 silencing. Our data demonstrate a previously dismissed function for the microRNA biogenesis machinery in regulating expression of lineage-specifying transcription factors and silencing of Cd4 and Cd8 during αß T cell differentiation.
Assuntos
RNA Helicases DEAD-box/genética , MicroRNAs/genética , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Ribonuclease III/genética , Linfócitos T Citotóxicos/citologia , Linfócitos T Auxiliares-Indutores/citologia , Animais , Apoptose/imunologia , Antígenos CD4/genética , Antígenos CD4/imunologia , Antígenos CD8/genética , Antígenos CD8/imunologia , Diferenciação Celular/imunologia , Linhagem da Célula/imunologia , Subunidade alfa 3 de Fator de Ligação ao Core/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Camundongos , Camundongos Knockout , MicroRNAs/biossíntese , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Linfócitos T Citotóxicos/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Fatores de Transcrição/imunologia , Proteína Supressora de Tumor p53/metabolismo , Regulação para CimaRESUMO
Being a well-characterized pathway, JAK-STAT signaling serves as a valuable paradigm for studying the architecture of gene regulatory networks. The discovery of untranslated or non-coding RNAs, namely microRNAs and long non-coding RNAs, provides an opportunity to elucidate their roles in such networks. In principle, these regulatory RNAs can act as downstream effectors of the JAK-STAT pathway and/or affect signaling by regulating the expression of JAK-STAT components. Examples of interactions between signaling pathways and non-coding RNAs have already emerged in basic cell biology and human diseases such as cancer, and can potentially guide the identification of novel biomarkers or drug targets for medicine.
RESUMO
Reactivation of fetal hemoglobin (HbF) holds therapeutic potential for sickle cell disease and ß-thalassemias. In human erythroid cells and hematopoietic organs, LIN28B and its targeted let-7 microRNA family, demonstrate regulated expression during the fetal-to-adult developmental transition. To explore the effects of LIN28B in human erythroid cell development, lentiviral transduction was used to knockdown LIN28B expression in erythroblasts cultured from human umbilical cord CD34+ cells. The subsequent reduction in LIN28B expression caused increased expression of let-7 and significantly reduced HbF expression. Conversely, LIN28B overexpression in cultured adult erythroblasts reduced the expression of let-7 and significantly increased HbF expression. Cellular maturation was maintained including enucleation. LIN28B expression in adult erythroblasts increased the expression of γ-globin, and the HbF content of the cells rose to levels >30% of their hemoglobin. Expression of carbonic anhydrase I, glucosaminyl (N-acetyl) transferase 2, and miR-96 (three additional genes marking the transition from fetal-to-adult erythropoiesis) were reduced by LIN28B expression. The transcription factor BCL11A, a well-characterized repressor of γ-globin expression, was significantly down-regulated. Independent of LIN28B, experimental suppression of let-7 also reduced BCL11A expression and significantly increased HbF expression. LIN28B expression regulates HbF levels and causes adult human erythroblasts to differentiate with a more fetal-like phenotype.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Eritroblastos/citologia , Eritrócitos/citologia , Hemoglobina Fetal/metabolismo , Regulação da Expressão Gênica , Antígenos CD34/metabolismo , Anidrase Carbônica I/metabolismo , Técnicas de Cultura de Células , Sangue Fetal/citologia , Hemoglobina A/metabolismo , Humanos , MicroRNAs/metabolismo , N-Acetilglucosaminiltransferases/metabolismo , Fenótipo , Proteínas de Ligação a RNARESUMO
The discovery of microRNAs has renewed interest in posttranscriptional modes of regulation, fueling an emerging view of a rich RNA world within our cells that deserves further exploration. Much work has gone into elucidating genetic regulatory networks that orchestrate gene expression programs and direct cell fate decisions in the hematopoietic system. However, the focus has been to elucidate signaling pathways and transcriptional programs. To bring us one step closer to reverse engineering the molecular logic of cellular differentiation, it will be necessary to map posttranscriptional circuits as well and integrate them in the context of existing network models. In this regard, RNA-binding proteins (RBPs) may rival transcription factors as important regulators of cell fates and represent a tractable opportunity to connect the RNA world to the proteome. ChIP-seq has greatly facilitated genome-wide localization of DNA-binding proteins, helping us to understand genomic regulation at a systems level. Similarly, technological advances such as CLIP-seq allow transcriptome-wide mapping of RBP binding sites, aiding us to unravel posttranscriptional networks. Here, we review RBP-mediated posttranscriptional regulation, paying special attention to findings relevant to the immune system. As a prime example, we highlight the RBP Lin28B, which acts as a heterochronic switch between fetal and adult lymphopoiesis.
Assuntos
Proteínas de Ligação a DNA/imunologia , Hematopoese , Linfócitos/imunologia , MicroRNAs/imunologia , Proteínas de Ligação a RNA/imunologia , Animais , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Hematopoese/genética , Humanos , MicroRNAs/genética , Interferência de RNA , Transdução de Sinais , TranscriptomaRESUMO
MicroRNAs (miRNAs) regulate the function of several immune cells, but their role in promoting CD8(+) T cell immunity remains unknown. Here we report that miRNA-155 is required for CD8(+) T cell responses to both virus and cancer. In the absence of miRNA-155, accumulation of effector CD8(+) T cells was severely reduced during acute and chronic viral infections and control of virus replication was impaired. Similarly, Mir155(-/-) CD8(+) T cells were ineffective at controlling tumor growth, whereas miRNA-155 overexpression enhanced the antitumor response. miRNA-155 deficiency resulted in accumulation of suppressor of cytokine signaling-1 (SOCS-1) causing defective cytokine signaling through STAT5. Consistently, enforced expression of SOCS-1 in CD8(+) T cells phenocopied the miRNA-155 deficiency, whereas SOCS-1 silencing augmented tumor destruction. These findings identify miRNA-155 and its target SOCS-1 as key regulators of effector CD8(+) T cells that can be modulated to potentiate immunotherapies for infectious diseases and cancer.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Coriomeningite Linfocítica/imunologia , Vírus da Coriomeningite Linfocítica/fisiologia , Melanoma Experimental/imunologia , MicroRNAs/metabolismo , Transferência Adotiva , Animais , Apoptose/genética , Proliferação de Células , Células Cultivadas , Citocinas/metabolismo , Citotoxicidade Imunológica/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , MicroRNAs/genética , RNA Interferente Pequeno/genética , Fator de Transcrição STAT6/metabolismo , Proteína 1 Supressora da Sinalização de Citocina , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Replicação Viral/genéticaRESUMO
Distinct CD4(+) T cell subsets are critical for host defense and immunoregulation. Although these subsets can act as terminally differentiated lineages, they have been increasingly noted to demonstrated plasticity. MicroRNAs are factors that control T cell stability and plasticity. Here we report that naturally occurring regulatory T cells (T(reg) cells) had high expression of the microRNA miR-10a and that miR-10a was induced by retinoic acid and transforming growth factor-ß (TGF-ß) in inducible T(reg) cells. By simultaneously targeting the transcriptional repressor Bcl-6 and the corepressor Ncor2, miR-10a attenuated the phenotypic conversion of inducible T(reg) cells into follicular helper T cells. We also found that miR-10a limited differentiation into the T(H)17 subset of helper T cells and therefore represents a factor that can fine-tune the plasticity and fate of helper T cells.
Assuntos
MicroRNAs/biossíntese , Proteínas Proto-Oncogênicas c-bcl-6/metabolismo , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacos , Fator de Crescimento Transformador beta/farmacologia , Tretinoína/farmacologia , Animais , Diferenciação Celular/imunologia , Regulação para Baixo/imunologia , Citometria de Fluxo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/imunologia , Correpressor 2 de Receptor Nuclear/imunologia , Fenótipo , Proteínas Proto-Oncogênicas c-bcl-6/imunologia , RNA Mensageiro/biossíntese , RNA Mensageiro/química , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas com Domínio T/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/fisiologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/fisiologia , Transcrição GênicaRESUMO
The immune system develops in waves during ontogeny; it is initially populated by cells generated from fetal hematopoietic stem cells (HSCs) and later by cells derived from adult HSCs. Remarkably, the genetic programs that control these two distinct stem cell fates remain poorly understood. We report that Lin28b is specifically expressed in mouse and human fetal liver and thymus, but not in adult bone marrow or thymus. We demonstrate that ectopic expression of Lin28 reprograms hematopoietic stem/progenitor cells (HSPCs) from adult bone marrow, which endows them with the ability to mediate multilineage reconstitution that resembles fetal lymphopoiesis, including increased development of B-1a, marginal zone B, gamma/delta (γδ) T cells, and natural killer T (NKT) cells.
Assuntos
Células-Tronco Adultas/fisiologia , Linfócitos B/fisiologia , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Hematopoéticas/fisiologia , Linfopoese , Linfócitos T/fisiologia , Animais , Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/fisiologia , Linfócitos B/citologia , Células da Medula Óssea/metabolismo , Linhagem da Célula , Proteínas de Ligação a DNA/genética , Sangue Fetal/citologia , Feto , Citometria de Fluxo , Humanos , Fígado/embriologia , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , MicroRNAs/metabolismo , Células T Matadoras Naturais/citologia , Células T Matadoras Naturais/imunologia , Células T Matadoras Naturais/fisiologia , Proteínas de Ligação a RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/fisiologia , Linfócitos T/citologia , Timo/embriologia , Timo/metabolismo , Transdução GenéticaRESUMO
Abelson murine leukemia virus-transformed cell lines have provided a critical model system for studying the regulation of B cell development. However, transformation by v-Abl blocks B cell development, resulting in the arrest of these transformants in an early pre-B cell-like state. We report here that treatment of Abelson virus-transformed pre-B cell lines with the small molecule Abl kinase inhibitor (STI571) results in their differentiation to a late pre-B cell-like state characterized by induction of immunoglobulin (Ig) light chain gene rearrangement. DNA microarray analyses enabled us to identify two genes inhibited by v-Abl that encode the Igk 3' enhancer-binding transcription factors Spi-B and IRF-4. We show that enforced expression of these two factors is sufficient to induce germline Igk transcription in Abelson-transformed pro-B cell lines. This suggests a key role for these factors, and perhaps for c-Abl itself, in the regulated activation of Ig light chain gene rearrangement.