RESUMO
Although many cytokine pathways are important for dendritic cell (DC) development, it is less clear what cytokine signals promote the function of mature dendritic cells. The signal transducer and activator of transcription 4 (STAT4) promotes protective immunity and autoimmunity downstream of proinflammatory cytokines including IL-12 and IL-23. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), Stat4-/- mice are resistant to the development of inflammation and paralysis. To define whether STAT4 is required for intrinsic signaling in mature DC function, we used conditional mutant mice in the EAE model. Deficiency of STAT4 in CD11c-expressing cells resulted in decreased T cell priming and inflammation in the central nervous system. EAE susceptibility was recovered following adoptive transfer of wild-type bone marrow-derived DCs to mice with STAT4-deficient DCs, but not adoptive transfer of STAT4- or IL-23R-deficient DCs. Single-cell RNA-sequencing (RNA-seq) identified STAT4-dependent genes in DC subsets that paralleled a signature in MS patient DCs. Together, these data define an IL-23-STAT4 pathway in DCs that is key to DC function during inflammatory disease.
Assuntos
Células Dendríticas , Encefalomielite Autoimune Experimental , Interleucina-23 , Fator de Transcrição STAT4 , Transdução de Sinais , Animais , Fator de Transcrição STAT4/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Interleucina-23/metabolismo , Interleucina-23/imunologia , Camundongos , Encefalomielite Autoimune Experimental/imunologia , Encefalomielite Autoimune Experimental/metabolismo , Camundongos Knockout , Esclerose Múltipla/imunologia , Esclerose Múltipla/metabolismo , Esclerose Múltipla/patologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/imunologia , Inflamação/metabolismo , Inflamação/imunologia , Transferência Adotiva , Camundongos Endogâmicos C57BL , Humanos , Linfócitos T/imunologia , Linfócitos T/metabolismoRESUMO
Chromosomal translocations of the nucleoporin 98 (NUP98) gene are found in acute myeloid leukemia (AML) patients leading to very poor outcomes. The oncogenic activity of NUP98 fusion proteins is dependent on the interaction between Mixed Lineage Leukemia 1 and menin. NUP98-rearranged (NUP98-r) leukemia cells also rely on specific kinases, including CDK6 and/or FLT3, suggesting that simultaneous targeting of these kinases and menin could overcome limited sensitivity to single agents. Here, we found that combinations of menin inhibitor, MI-3454, with kinase inhibitors targeting either CDK6 (Palbociclib) or FLT3 (Gilteritinib) strongly enhance the anti-leukemic effect of menin inhibition in NUP98-r leukemia models. We found strong synergistic effects of both combinations on cell growth, colony formation and differentiation in patient samples with NUP98 translocations. These combinations also markedly augmented anti-leukemic efficacy of menin inhibitor in Patient Derived Xenograft models of NUP98-r leukemia. Despite inhibiting two unrelated kinases, when Palbociclib or Gilteritinib were combined with the menin inhibitor, they affected similar pathways relevant to leukemogenesis, including cell cycle regulation, cell proliferation and differentiation. This study provides strong rationale for clinical translation of the combination of menin and kinase inhibitors as novel treatments for NUP98-r leukemia, supporting the unexplored combinations of epigenetic drugs with kinase inhibitors.
Assuntos
Complexo de Proteínas Formadoras de Poros Nucleares , Inibidores de Proteínas Quinases , Proteínas Proto-Oncogênicas , Translocação Genética , Humanos , Animais , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Camundongos , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas/genética , Ensaios Antitumorais Modelo de Xenoenxerto , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Piridinas/farmacologia , Piridinas/uso terapêutico , Quinase 6 Dependente de Ciclina/antagonistas & inibidores , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Proliferação de Células/efeitos dos fármacos , Sinergismo Farmacológico , Tirosina Quinase 3 Semelhante a fms/genética , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidores , Linhagem Celular Tumoral , Compostos de Anilina , PirazinasRESUMO
Umbilical cord blood (CB) is a donor source for hematopoietic cell therapies. Understanding what drives hematopoietic stem and progenitor cell function is critical to our understanding of the usage of CB in hematopoietic cell therapies. Here, we describe how to isolate and analyze the function of human hematopoietic cells from umbilical CB. This protocol demonstrates assays that measure phenotypic properties and hematopoietic cell potency. For complete details on the use and execution of this protocol, please refer to Broxmeyer et al.1.
Assuntos
Sangue Fetal , Células-Tronco Hematopoéticas , Humanos , Sangue Fetal/citologia , Células-Tronco Hematopoéticas/citologia , Separação Celular/métodosRESUMO
PURPOSE OF REVIEW: Here, we review classic and emerging uses of umbilical cord blood and highlight strategies to improve its utility, focusing on selection of the appropriate units and cell types for the intended applications. RECENT LITERATURE: Recent studies have shown advancements in cord blood cell utility in a variety of cellular therapies and have made strides in elucidating manners to select the best units for therapy and target new ways to improve the various cell subpopulations for their respective applications. SUMMARY: Umbilical cord blood is a proven source of cells for hematopoietic cell transplantation and research and is an important potential source for additional cellular therapies. However, cord blood utility is limited by low "doses" of potent cells that can be obtained from individual units, a limitation that is specific to cord blood as a donor source. In addition to traditional CD34 + progenitor cells, cord blood lymphocytes are being pursued as therapeutic entities with their own unique properties and characteristics. Thus, selection of ideal units depends on the intended therapeutic entity and target, and identification of differential potency parameters is critical to drive effective banking strategies accommodating successful clinical use of cord blood in broader cell therapy settings.
Assuntos
Transplante de Células-Tronco de Sangue do Cordão Umbilical , Sangue Fetal , Humanos , Sangue Fetal/citologia , Transplante de Células-Tronco de Sangue do Cordão Umbilical/métodos , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismoRESUMO
Umbilical cord blood transplantation is a life-saving treatment for malignant and non-malignant hematologic disorders. It remains unclear how long cryopreserved units remain functional, and the length of cryopreservation is often used as a criterion to exclude older units. We demonstrate that long-term cryopreserved cord blood retains similar numbers of hematopoietic stem and progenitor cells compared with fresh and recently cryopreserved cord blood units. Long-term cryopreserved units contain highly functional cells, yielding robust engraftment in mouse transplantation models. We also leverage differences between units to examine gene programs associated with better engraftment. Transcriptomic analyses reveal that gene programs associated with lineage determination and oxidative stress are enriched in high engrafting cord blood, revealing potential molecular markers to be used as potency markers for cord blood unit selection regardless of length of cryopreservation. In summary, cord blood units cryopreserved for extended periods retain engrafting potential and can potentially be used for patient treatment.
Assuntos
Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas , Animais , Camundongos , Humanos , Sangue Fetal , CriopreservaçãoRESUMO
Acute myeloid leukemia (AML) is an aggressive blood cancer with poor prognosis. FMS-like tyrosine kinase receptor-3 (FLT3) is one of the major oncogenic receptor tyrosine kinases aberrantly activated in AML. Although protein tyrosine phosphatase PRL2 is highly expressed in some subtypes of AML compared with normal human hematopoietic stem and progenitor cells, the mechanisms by which PRL2 promotes leukemogenesis are largely unknown. We discovered that genetic and pharmacological inhibition of PRL2 significantly reduce the burden of FLT3-internal tandem duplications-driven leukemia and extend the survival of leukemic mice. Furthermore, we found that PRL2 enhances oncogenic FLT3 signaling in leukemia cells, promoting their proliferation and survival. Mechanistically, PRL2 dephosphorylates the E3 ubiquitin ligase CBL at tyrosine 371 and attenuates CBL-mediated ubiquitination and degradation of FLT3, leading to enhanced FLT3 signaling in leukemia cells. Thus, our study reveals that PRL2 enhances oncogenic FLT3 signaling in leukemia cells through dephosphorylation of CBL and will likely establish PRL2 as a novel druggable target for AML.
Assuntos
Leucemia Mieloide Aguda , Ubiquitina-Proteína Ligases , Humanos , Animais , Camundongos , Ubiquitina-Proteína Ligases/metabolismo , Monoéster Fosfórico Hidrolases/genética , Transdução de Sinais/genética , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Proteínas Proto-Oncogênicas c-cbl/genética , Proteínas Proto-Oncogênicas c-cbl/metabolismo , Tirosina Quinase 3 Semelhante a fms/genética , Tirosina Quinase 3 Semelhante a fms/metabolismo , MutaçãoRESUMO
MLL (KMT2a) translocations are found in ~10% of acute leukemia patients, giving rise to oncogenic MLL-fusion proteins. A common MLL translocation partner is ENL and associated with a poor prognosis in t(11;19) patients. ENL contains a highly conserved N-terminal YEATS domain that binds acetylated histones and interacts with the PAF1c, an epigenetic regulator protein complex essential for MLL-fusion leukemogenesis. Recently, wild-type ENL, and specifically the YEATS domain, was shown to be essential for leukemic cell growth. However, the inclusion and importance of the YEATS domain in MLL-ENL-mediated leukemogenesis remains unexplored. We found the YEATS domain is retained in 84.1% of MLL-ENL patients and crucial for MLL-ENL-mediated leukemogenesis in mouse models. Mechanistically, deletion of the YEATS domain impaired MLL-ENL fusion protein binding and decreased expression of pro-leukemic genes like Eya1 and Meis1. Point mutations that disrupt YEATS domain binding to acetylated histones decreased stem cell frequency and increased MLL-ENL-mediated leukemia latency. Therapeutically, YEATS containing MLL-ENL leukemic cells display increased sensitivity to the YEATS inhibitor SGC-iMLLT compared to control AML cells. Our results demonstrate that the YEATS domain is important for MLL-ENL fusion protein-mediated leukemogenesis and exposes an "Achilles heel" that may be therapeutically targeted for treating t(11;19) patients.
Assuntos
Histonas , Leucemia Mieloide Aguda , Camundongos , Animais , Histonas/metabolismo , Proteína de Leucina Linfoide-Mieloide/genética , Proteína de Leucina Linfoide-Mieloide/metabolismo , Leucemia Mieloide Aguda/genética , Translocação Genética , Epigênese Genética , Células-Tronco/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismoRESUMO
Hematopoietic stem cells (HSCs) manifest impaired recovery and self-renewal with a concomitant increase in differentiation when exposed to ambient air as opposed to physioxia. Mechanism(s) behind this distinction are poorly understood but have the potential to improve stem cell transplantation. Single-cell RNA sequencing of HSCs in physioxia revealed upregulation of HSC self-renewal genes and downregulation of genes involved in inflammatory pathways and HSC differentiation. HSCs under physioxia also exhibited downregulation of the epigenetic modifier Tet2. Tet2 is α-ketoglutarate, iron- and oxygen-dependent dioxygenase that converts 5-methylcytosine to 5-hydroxymethylcytosine, thereby promoting active transcription. We evaluated whether loss of Tet2 affects the number and function of HSCs and hematopoietic progenitor cells (HPCs) under physioxia and ambient air. In contrast to wild-type HSCs (WT HSCs), a complete nonresponsiveness of Tet2-/- HSCs and HPCs to changes in oxygen tension was observed. Unlike WT HSCs, Tet2-/- HSCs and HPCs exhibited similar numbers and function in either physioxia or ambient air. The lack of response to changes in oxygen tension in Tet2-/- HSCs was associated with similar changes in self-renewal and quiescence genes among WT HSC-physioxia, Tet2-/- HSC-physioxia and Tet2-/- HSC-air. We define a novel molecular program involving Tet2 in regulating HSCs under physioxia.
Assuntos
5-Metilcitosina , Dioxigenases , 5-Metilcitosina/metabolismo , Diferenciação Celular/fisiologia , Dioxigenases/metabolismo , Regulação para Baixo , Células-Tronco Hematopoéticas/metabolismo , Ferro/metabolismo , Ácidos Cetoglutáricos , Oxigênio/metabolismoRESUMO
Hematopoietic cells are regulated in part by extracellular cues from cytokines. Leukemia inhibitory factor (LIF) promotes survival, self-renewal, and pluripotency of mouse embryonic stem cells (mESC). While genetic deletion of LIF affects hematopoietic progenitor cells (HPCs), the direct effect of LIF protein exposure on HPC survival is not known. Furthermore, post-translational modifications (PTM) of LIF and their effects on its function have not been evaluated. We demonstrate that treatment with recombinant LIF preserves mouse and human HPC numbers in stressed conditions when growth factor addition is delayed ex vivo. We show that Lif is upregulated in response to irradiation-induced stress. We reveal novel PTM of LIF where it is cleaved twice by dipeptidyl peptidase 4 (DPP4) protease so that it loses its 4 N-terminal amino acids. This truncation of LIF down-modulates LIF's ability to preserve functional HPC numbers ex vivo following delayed growth factor addition. DPP4-truncated LIF blocks the ability of full-length LIF to preserve functional HPC numbers. This LIF role and its novel regulation by DPP4 have important implications for normal and stress hematopoiesis, as well as for other cellular contexts in which LIF and DPP4 are implicated.
Assuntos
Dipeptidil Peptidase 4/metabolismo , Hematopoese , Animais , Dipeptidil Peptidase 4/genética , Células-Tronco Hematopoéticas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Fator Inibidor de Leucemia/metabolismo , Fator Inibidor de Leucemia/farmacologia , CamundongosRESUMO
Little is known about a regulatory role of CaMKK2 for hematopoietic stem (HSC) and progenitor (HPC) cell function. To assess this, we used Camkk2-/- and wild type (WT) control mouse bone marrow (BM) cells. BM cells were collected/processed and compared under hypoxia (3% oxygen; physioxia) vs. ambient air (~21% oxygen). Subjecting cells collected to ambient air, even for a few minutes, causes a stress that we termed Extra Physiological Shock/Stress (EPHOSS) that causes differentiation of HSCs and HPCs. We consider physioxia collection/processing a more relevant way to assess HSC/HPC numbers and function, as the cells remain in an oxygen tension closer physiologic conditions. Camkk2-/- cells collected/processed at 3% oxygen had positive and negative effects respectively on HSCs (by engraftment using competitive transplantation with congenic donor and competitor cells and lethally irradiated congenic recipient mice), and HPCs (by colony forming assays of CFU-GM, BFU-E, and CFU-GEMM) compared to WT cells processed in ambient air. Thus, with cells collected/processed under physioxia, and therefore never exposed and naïve to ambient air conditions, CaMKK2 not only appears to act as an HSC to HPC differentiation fate determinant, but as we found for other intracellular mediators, the Camkk-/- mouse BM cells were relatively resistant to effects of EPHOSS. This information is of potential use for modulation of WT BM HSCs and HPCs for future clinical advantage.
Assuntos
Transplante de Células-Tronco Hematopoéticas , Oxigênio , Animais , Células da Medula Óssea , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/genética , Camundongos , Camundongos Knockout , Oxigênio/farmacologiaRESUMO
Few cytokines/growth modulating proteins are known to be chemoattractants for hematopoietic stem (HSC) and progenitor cells (HPC); stromal cell-derived factor 1α (SDF1α/CXCL12) being the most potent known such protein. DEK, a nuclear DNA-binding chromatin protein with hematopoietic cytokine-like activity, is a chemotactic factor attracting mature immune cells. Transwell migration assays were performed to test whether DEK serves as a chemotactic agent for HSC/HPC. DEK induced dose- and time-dependent directed migration of lineage negative (Lin- ) Sca-1+ c-Kit+ (LSK) bone marrow (BM) cells, HSCs and HPCs. Checkerboard assays demonstrated that DEK's activity was chemotactic (directed), not chemokinetic (random migration), in nature. DEK and SDF1α compete for HSC/HPC chemotaxis. Blocking CXCR2 with neutralizing antibodies or inhibiting Gαi protein signaling with Pertussis toxin pretreatment inhibited migration of LSK cells toward DEK. Thus, DEK is a novel and rare chemotactic agent for HSC/HPC acting in a direct or indirect CXCR2 and Gαi protein-coupled signaling-dependent manner.
Assuntos
Células-Tronco Hematopoéticas , Proteínas Nucleares , Células da Medula Óssea/metabolismo , Quimiotaxia , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Proteínas Nucleares/metabolismo , Receptores de Interleucina-8B/metabolismoRESUMO
Little is known of hematopoietic stem (HSC) and progenitor (HPC) cell self-renewal. The role of Brahma (BRM), a chromatin remodeler, in HSC function is unknown. Bone marrow (BM) from Brm-/- mice manifested increased numbers of long- and short-term HSCs, GMPs, and increased numbers and cycling of functional HPCs. However, increased Brm-/- BM HSC numbers had decreased secondary and tertiary engraftment, suggesting BRM enhances HSC self-renewal. Valine was elevated in lineage negative Brm-/- BM cells, linking intracellular valine with Brm expression. Valine enhanced HPC colony formation, replating of human cord blood (CB) HPC-derived colonies, mouse BM and human CB HPC survival in vitro, and ex vivo expansion of normal mouse BM HSCs and HPCs. Valine increased oxygen consumption rates of WT cells. BRM through CD98 was linked to regulated import of branched chain amino acids, such as valine, in HPCs. Brm-/- LSK cells exhibited upregulated interferon response/cell cycle gene programs. Effects of BRM depletion are less apparent on isolated HSCs compared to HSCs in the presence of HPCs, suggesting cell extrinsic effects on HSCs. Thus, intracellular valine is regulated by BRM expression in HPCs, and the BRM/valine axis regulates HSC and HPC self-renewal, proliferation, and possibly differentiation fate decisions.
Assuntos
Autorrenovação Celular , Montagem e Desmontagem da Cromatina , Células-Tronco Hematopoéticas/citologia , Fatores de Transcrição/metabolismo , Valina/metabolismo , Animais , Células Cultivadas , Deleção de Genes , Células-Tronco Hematopoéticas/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Transcrição/genéticaRESUMO
Acute myeloid leukaemia (AML) is an aggressive form of blood cancer that carries a dismal prognosis. Several studies suggest that the poor outcome is due to a small fraction of leukaemic cells that elude treatment and survive in specialised, oxygen (O2 )-deprived niches of the bone marrow. Although several AML drug targets such as FLT3, IDH1/2 and CD33 have been established in recent years, survival rates remain unsatisfactory, which indicates that other, yet unrecognized, mechanisms influence the ability of AML cells to escape cell death and to proliferate in hypoxic environments. Our data illustrates that Carbonic Anhydrases IX and XII (CA IX/XII) are critical for leukaemic cell survival in the O2 -deprived milieu. CA IX and XII function as transmembrane proteins that mediate intracellular pH under low O2 conditions. Because maintaining a neutral pH represents a key survival mechanism for tumour cells in O2 -deprived settings, we sought to elucidate the role of dual CA IX/XII inhibition as a novel strategy to eliminate AML cells under hypoxic conditions. Our findings demonstrate that the dual CA IX/XII inhibitor FC531 may prove to be of value as an adjunct to chemotherapy for the treatment of AML.
Assuntos
Antineoplásicos/farmacologia , Anidrase Carbônica IX/antagonistas & inibidores , Inibidores da Anidrase Carbônica/farmacologia , Anidrases Carbônicas/metabolismo , Hipóxia Tumoral/efeitos dos fármacos , Adulto , Idoso , Animais , Antígenos de Neoplasias/genética , Anidrase Carbônica IX/genética , Anidrases Carbônicas/genética , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Modelos Animais de Doenças , Sinergismo Farmacológico , Feminino , Duplicação Gênica , Expressão Gênica , Humanos , Concentração de Íons de Hidrogênio , Imuno-Histoquímica , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/etiologia , Leucemia Mieloide Aguda/metabolismo , Masculino , Pessoa de Meia-Idade , Hipóxia Tumoral/genética , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/genética , Ensaios Antitumorais Modelo de Xenoenxerto , Adulto Jovem , Tirosina Quinase 3 Semelhante a fms/genéticaRESUMO
Cytokines/chemokines regulate hematopoiesis, most having multiple cell actions. Numerous but not all chemokine family members act as negative regulators of hematopoietic progenitor cell (HPC) proliferation, but very little is known about such effects of the chemokine, CXCL15/Lungkine. We found that CXCL15/Lungkine-/- mice have greatly increased cycling of multi cytokine-stimulated bone marrow and spleen hematopoietic progenitor cells (HPCs: CFU-GM, BFU-E, and CFU-GEMM) and CXCL15 is expressed in many bone marrow progenitor and other cell types. This suggests that CXCL15/Lungkine acts as a negative regulator of the cell cycling of these HPCs in vivo. Recombinant murine CXCL15/Lungkine, decreased numbers of functional HPCs during cytokine-enhanced ex-vivo culture of lineage negative mouse bone marrow cells. Moreover, CXCL15/Lungkine, through S-Phase specific actions, was able to suppress in vitro colony formation of normal wildtype mouse bone marrow CFU-GM, CFU-G, CFU-M, BFU-E, and CFU-GEMM. This clearly identifies the negative regulatory activity of CXCL15/Lungkine on proliferation of multiple types of mouse HPCs.
Assuntos
Quimiocinas CXC/metabolismo , Células Eritroides/citologia , Granulócitos/citologia , Macrófagos/citologia , Células-Tronco/citologia , Animais , Proliferação de Células , Células Cultivadas , Células Eritroides/metabolismo , Granulócitos/metabolismo , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Pontos de Checagem da Fase S do Ciclo Celular , Células-Tronco/metabolismoRESUMO
ASH1L histone methyltransferase plays a crucial role in the pathogenesis of different diseases, including acute leukemia. While ASH1L represents an attractive drug target, developing ASH1L inhibitors is challenging, as the catalytic SET domain adapts an inactive conformation with autoinhibitory loop blocking the access to the active site. Here, by applying fragment-based screening followed by medicinal chemistry and a structure-based design, we developed first-in-class small molecule inhibitors of the ASH1L SET domain. The crystal structures of ASH1L-inhibitor complexes reveal compound binding to the autoinhibitory loop region in the SET domain. When tested in MLL leukemia models, our lead compound, AS-99, blocks cell proliferation, induces apoptosis and differentiation, downregulates MLL fusion target genes, and reduces the leukemia burden in vivo. This work validates the ASH1L SET domain as a druggable target and provides a chemical probe to further study the biological functions of ASH1L as well as to develop therapeutic agents.
Assuntos
Antineoplásicos/farmacologia , Proteínas de Ligação a DNA/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Histona-Lisina N-Metiltransferase/antagonistas & inibidores , Leucemia/tratamento farmacológico , Leucemia/enzimologia , Animais , Antineoplásicos/química , Domínio Catalítico/efeitos dos fármacos , Domínio Catalítico/genética , Linhagem Celular Tumoral , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Cristalografia por Raios X , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Desenho de Fármacos , Descoberta de Drogas , Inibidores Enzimáticos/química , Feminino , Histona-Lisina N-Metiltransferase/química , Histona-Lisina N-Metiltransferase/genética , Humanos , Leucemia/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Moleculares , Proteína de Leucina Linfoide-Mieloide/genética , Oncogenes , Domínios Proteicos , Proteínas Recombinantes de Fusão/genéticaRESUMO
PURPOSE OF REVIEW: In recent history there have been three outbreaks of betacoronavirus infections in humans, with the most recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; causing Coronavirus disease 2019 [COVID-19]) outbreak leading to over two million deaths, with a rapidly rising death toll. Much remains unknown about host cells and tissues affected by coronavirus infections, including the hematopoietic system. Here, we discuss the recent findings examining effects that coronavirus infection or exposure has on hematopoietic cells and the clinical implications for these effects. RECENT FINDINGS: Recent studies have centered on SARS-CoV-2, demonstrating that hematopoietic stem and progenitor cells and mature immune cells may be susceptible to infection and are impacted functionally by exposure to SARS-CoV-2 Spike protein. These findings have important implications regarding hematologic complications arising from COVID-19 and other coronavirus-induced disease, which we discuss here. SUMMARY: Infection with coronaviruses sometimes leads to hematologic complications in patients, and these hematologic complications are associated with poorer prognosis. These hematologic complications may be caused by coronavirus direct infection or impact on primitive hematopoietic cells or mature immune cells, by indirect effects on these cells, or by a combination thereof. It is important to understand how hematologic complications arise in order to seek new treatments to improve patient outcomes.
Assuntos
COVID-19/metabolismo , Células-Tronco Hematopoéticas/metabolismo , SARS-CoV-2/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , COVID-19/mortalidade , COVID-19/patologia , Células-Tronco Hematopoéticas/patologia , HumanosRESUMO
MLL1 (KMT2a) gene rearrangements underlie the pathogenesis of aggressive MLL-driven acute leukemia. AF9, one of the most common MLL-fusion partners, recruits the histone H3K79 methyltransferase DOT1L to MLL target genes, constitutively activating transcription of pro-leukemic targets. DOT1L has emerged as a therapeutic target in patients with MLL-driven leukemia. However, global DOT1L enzymatic inhibition may lead to off-target toxicities in non-leukemic cells that could decrease the therapeutic index of DOT1L inhibitors. To bypass this problem, we developed a novel approach targeting specific protein-protein interactions (PPIs) that mediate DOT1L recruitment to MLL target genes, and compared the effects of enzymatic and PPIs inhibition on leukemic and non-leukemic hematopoiesis. MLL-AF9 cell lines were engineered to carry mutant DOT1L constructs with a defective AF9 interaction site or lacking enzymatic activity. In cell lines expressing a DOT1L mutant with defective AF9 binding, we observed complete disruption of DOT1L recruitment to critical target genes and inhibition of leukemic cell growth. To evaluate the overall impact of DOT1L loss in non-leukemic hematopoiesis, we first assessed the impact of acute Dot1l inactivation in adult mouse bone marrow. We observed a rapid reduction in myeloid progenitor cell numbers within 7 days, followed by a loss of long-term hematopoietic stem cells. Furthermore, WT and PPI-deficient DOT1L mutants but not an enzymatically inactive DOT1L mutant were able to rescue sustained hematopoiesis. These data show that the AF9-DOT1L interaction is dispensable in non-leukemic hematopoiesis. Our findings support targeting of the MLL-AF9-DOT1L interaction as a promising therapeutic strategy that is selectively toxic to MLL-driven leukemic cells.
RESUMO
Bone marrow (BM) hematopoietic stem cells (HSCs) become dysfunctional during aging (i.e., they are increased in number but have an overall reduction in long-term repopulation potential and increased myeloid differentiation) compared with young HSCs, suggesting limited use of old donor BM cells for hematopoietic cell transplantation (HCT). BM cells reside in an in vivo hypoxic environment yet are evaluated after collection and processing in ambient air. We detected an increase in the number of both young and aged mouse BM HSCs collected and processed in 3% O2 compared with the number of young BM HSCs collected and processed in ambient air (~21% O2). Aged BM collected and processed under hypoxic conditions demonstrated enhanced engraftment capability during competitive transplantation analysis and contained more functional HSCs as determined by limiting dilution analysis. Importantly, the myeloid-to-lymphoid differentiation ratio of aged BM collected in 3% O2 was similar to that detected in young BM collected in ambient air or hypoxic conditions, consistent with the increased number of common lymphoid progenitors following collection under hypoxia. Enhanced functional activity and differentiation of old BM collected and processed in hypoxia correlated with reduced "stress" associated with ambient air BM collection and suggests that aged BM may be better and more efficiently used for HCT if collected and processed under hypoxia so that it is never exposed to ambient air O2.
Assuntos
Células-Tronco Hematopoéticas/metabolismo , Consumo de Oxigênio , Oxigênio/metabolismo , Animais , Hipóxia Celular , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Despite evidence that SARS-CoV-2 infection is systemic in nature, there is little known about the effects that SARS-CoV-2 infection or exposure has on many host cell types, including primitive and mature hematopoietic cells. The hematopoietic system is responsible for giving rise to the very immune cells that defend against viral infection and is a source of hematopoietic stem cells (HSCs) and progenitor cells (HPCs) which are used for hematopoietic cell transplantation (HCT) to treat hematologic disorders, thus there is a strong need to understand how exposure to the virus may affect hematopoietic cell functions. We examined the expression of ACE2, to which SARS-CoV-2 Spike (S) protein binds to facilitate viral entry, in cord blood derived HSCs/HPCs and in peripheral blood derived immune cell subtypes. ACE2 is expressed in low numbers of immune cells, higher numbers of HPCs, and up to 65% of rigorously defined HSCs. We also examined effects of exposing HSCs/HPCs and immune cells to SARS-CoV-2 S protein ex vivo. HSCs and HPCs expand less effectively and have less functional colony forming capacity when grown with S protein, while peripheral blood monocytes upregulate CD14 expression and show distinct changes in size and granularity. That these effects are induced by recombinant S protein alone and not the infectious viral particle suggests that simple exposure to SARS-CoV-2 may impact HSCs/HPCs and immune cells via S protein interactions with the cells, regardless of whether they can be infected. These data have implications for immune response to SARS-CoV-2 and for HCT. Graphical Abstract ⢠Human HSCs, HPCs, and immune cells express ACE2 on the cell surface, making them potentially susceptible to SARS-CoV-2 infection. ⢠SARS-CoV-2 S protein, which binds to ACE2, induces defects in the colony forming capacity of human HPC and inhibits the expansion of HSC/HPC subpopulations ex vivo. These effects can be at least partially neutralized by treatment with SARS-CoV-2 targeting antibody, recombinant human ACE2, or Angiotensin1-7. ⢠S protein also induces aberrant morphological changes in peripheral blood derived monocytes ex vivo. ⢠Thus, there are many different manners in which SARS-CoV-2 virus may impact the functional hematopoietic system, which has important implications for hematological manifestations of COVID-19 (i.e. thrombocytopenia and lymphopenia), immune response, and hematopoietic stem cell transplant in the era of COVID-19.