RESUMO
The rates and patterns of somatic mutation in normal tissues are largely unknown outside of humans1-7. Comparative analyses can shed light on the diversity of mutagenesis across species, and on long-standing hypotheses about the evolution of somatic mutation rates and their role in cancer and ageing. Here we performed whole-genome sequencing of 208 intestinal crypts from 56 individuals to study the landscape of somatic mutation across 16 mammalian species. We found that somatic mutagenesis was dominated by seemingly endogenous mutational processes in all species, including 5-methylcytosine deamination and oxidative damage. With some differences, mutational signatures in other species resembled those described in humans8, although the relative contribution of each signature varied across species. Notably, the somatic mutation rate per year varied greatly across species and exhibited a strong inverse relationship with species lifespan, with no other life-history trait studied showing a comparable association. Despite widely different life histories among the species we examined-including variation of around 30-fold in lifespan and around 40,000-fold in body mass-the somatic mutation burden at the end of lifespan varied only by a factor of around 3. These data unveil common mutational processes across mammals, and suggest that somatic mutation rates are evolutionarily constrained and may be a contributing factor in ageing.
Assuntos
Longevidade , Taxa de Mutação , Animais , Humanos , Longevidade/genética , Mamíferos/genética , Mutagênese/genética , MutaçãoRESUMO
Professor Cecília Maria Arraiano directs a research group named 'Control of Gene Expression' at Instituto de Tecnologia Química e Biológica, Universidade NOVA de Lisboa, Oeiras, Portugal. She started her scientific journey at the University of Lisbon, where she graduated in Biology, before completing her PhD in Genetics as a Fulbright-Hays Fellow at the University of Georgia, Athens, USA. After a postdoc in the USA, she returned to Lisbon to establish her own lab. She has authored close to 200 publications mainly in the field of RNA degradation mechanisms, with a focus on enzymes and RNA chaperones that mediate RNA decay in microorganisms. She has received several prizes and is an active member of prestigious organizations. Namely, she is an EMBO member, Fellow of the European Academy of Microbiology, Fellow of the American Academy of Microbiology, and member of the Portuguese Academy of Sciences. In addition, Prof Arraiano has chaired the FEBS Working Group on Women in Science from 2014 to 2022. In this fascinating interview, she discusses her research, her experience working in the USA and Portugal, and the importance of initiatives to support women in science.
Assuntos
Pesquisadores , Humanos , Estados UnidosRESUMO
Iron is mostly devoted to the hemoglobinization of erythrocytes for oxygen transport. However, emerging evidence points to a broader role for the metal in hematopoiesis, including the formation of the immune system. Iron availability in mammalian cells is controlled by iron-regulatory protein 1 (IRP1) and IRP2. We report that global disruption of both IRP1 and IRP2 in adult mice impairs neutrophil development and differentiation in the bone marrow, yielding immature neutrophils with abnormally high glycolytic and autophagic activity, resulting in neutropenia. IRPs promote neutrophil differentiation in a cell intrinsic manner by securing cellular iron supply together with transcriptional control of neutropoiesis to facilitate differentiation to fully mature neutrophils. Unlike neutrophils, monocyte count was not affected by IRP and iron deficiency, suggesting a lineage-specific effect of iron on myeloid output. This study unveils the previously unrecognized importance of IRPs and iron metabolism in the formation of a major branch of the innate immune system.
Assuntos
Medula Óssea , Neutrófilos , Animais , Medula Óssea/metabolismo , Hematopoese , Hemoglobinas/metabolismo , Homeostase , Ferro/metabolismo , Proteína 1 Reguladora do Ferro/metabolismo , Proteínas Reguladoras de Ferro/metabolismo , Mamíferos/metabolismo , Camundongos , Neutrófilos/metabolismo , Oxigênio/metabolismoRESUMO
Quantitative 3D imaging of organ-wide cellular and subcellular components is central for revealing and understanding complex interactions between stem cells and their microenvironment. Here, we present a gentle but fast whole-mount immunofluorescence staining protocol for 3D confocal microscopy (iFAST3D) that preserves the 3D structure of the entire tissue and that of subcellular structures with high fidelity. The iFAST3D protocol enables reproducible and high-resolution 3D imaging of stem cells and various niche components for many mouse organs and tissues. For complete details on the use and execution of this protocol, please refer to Saçma et al. (2019).
Assuntos
Imageamento Tridimensional , Células-Tronco , Animais , Imageamento Tridimensional/métodos , Camundongos , Microscopia Confocal/métodos , Coloração e RotulagemRESUMO
Hematopoietic stem cells (HSCs) mediate regeneration of the hematopoietic system following injury, such as following infection or inflammation. These challenges impair HSC function, but whether this functional impairment extends beyond the duration of inflammatory exposure is unknown. Unexpectedly, we observed an irreversible depletion of functional HSCs following challenge with inflammation or bacterial infection, with no evidence of any recovery up to 1 year afterward. HSCs from challenged mice demonstrated multiple cellular and molecular features of accelerated aging and developed clinically relevant blood and bone marrow phenotypes not normally observed in aged laboratory mice but commonly seen in elderly humans. In vivo HSC self-renewal divisions were absent or extremely rare during both challenge and recovery periods. The progressive, irreversible attrition of HSC function demonstrates that temporally discrete inflammatory events elicit a cumulative inhibitory effect on HSCs. This work positions early/mid-life inflammation as a mediator of lifelong defects in tissue maintenance and regeneration.
Assuntos
Hematopoese , Células-Tronco Hematopoéticas , Idoso , Envelhecimento , Animais , Medula Óssea , Humanos , Inflamação , CamundongosRESUMO
In social mammalian species, social stress can arise from different social interactions. Repeated exposure to social stressors can lead to neuropathology and psychiatric disorders. In this issue, Sakamoto et al. report on alterations in extracellular vesicles (EVs) in a mouse model of chronic social defeat stress (CSDS). The data suggest that mice susceptible to CSDS have alterations in the miRNA content of circulating EVs, which influences the expression of pro-inflammatory cytokines in microglia cells.
Assuntos
Derrota Social , Estresse Psicológico , Animais , Camundongos , Camundongos Endogâmicos C57BLRESUMO
The proliferative activity of aging hematopoietic stem cells (HSCs) is controversially discussed. Inducible fluorescent histone 2B fusion protein (H2B-FP) transgenic mice are important tools for tracking the mitotic history of murine HSCs in label dilution experiments. A recent study proposed that primitive HSCs symmetrically divide only four times to then enter permanent quiescence. We observed that background fluorescence due to leaky H2B-FP expression, occurring in all H2B-FP transgenes independent of label induction, accumulated with age in HSCs with high repopulation potential. We argue that this background had been misinterpreted as stable retention of induced label. We found cell division-independent half-lives of H2B-FPs to be short, which had led to overestimation of HSC divisional activity. Our data do not support abrupt entry of HSCs into permanent quiescence or sudden loss of regeneration potential after four divisions, but show that primitive HSCs of adult mice continue to cycle rarely.
Assuntos
Envelhecimento/fisiologia , Células-Tronco Hematopoéticas/citologia , Mitose , Animais , Fluorescência , Regulação da Expressão Gênica , Células-Tronco Hematopoéticas/metabolismo , Histonas/metabolismo , Cinética , Camundongos Endogâmicos C57BL , Modelos Biológicos , Proteólise , Proteínas Recombinantes de Fusão/metabolismoRESUMO
With ageing, intrinsic haematopoietic stem cell (HSC) activity decreases, resulting in impaired tissue homeostasis, reduced engraftment following transplantation and increased susceptibility to diseases. However, whether ageing also affects the HSC niche, and thereby impairs its capacity to support HSC function, is still widely debated. Here, by using in-vivo long-term label-retention assays we demonstrate that aged label-retaining HSCs, which are, in old mice, the most quiescent HSC subpopulation with the highest regenerative capacity and cellular polarity, reside predominantly in perisinusoidal niches. Furthermore, we demonstrate that sinusoidal niches are uniquely preserved in shape, morphology and number on ageing. Finally, we show that myeloablative chemotherapy can selectively disrupt aged sinusoidal niches in the long term, which is linked to the lack of recovery of endothelial Jag2 at sinusoids. Overall, our data characterize the functional alterations of the aged HSC niche and unveil that perisinusoidal niches are uniquely preserved and thereby protect HSCs from ageing.
Assuntos
Envelhecimento/genética , Capilares/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Homeostase/genética , Nicho de Células-Tronco/genética , Envelhecimento/metabolismo , Animais , Medula Óssea/efeitos dos fármacos , Medula Óssea/metabolismo , Capilares/citologia , Capilares/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Polaridade Celular/efeitos dos fármacos , Rastreamento de Células/métodos , Doxiciclina/farmacologia , Fluoruracila/farmacologia , Regulação da Expressão Gênica , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Histonas/genética , Histonas/metabolismo , Homeostase/efeitos dos fármacos , Proteína Jagged-2/genética , Proteína Jagged-2/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Agonistas Mieloablativos/farmacologia , Nicho de Células-Tronco/efeitos dos fármacosRESUMO
Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.
Assuntos
Plaquetas/metabolismo , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Animais , Plaquetas/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Citocinas/metabolismo , Grânulos Citoplasmáticos/efeitos dos fármacos , Grânulos Citoplasmáticos/metabolismo , Endotélio/efeitos dos fármacos , Endotélio/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/patologia , Humanos , Receptores de Hialuronatos/metabolismo , Ácido Hialurônico/metabolismo , Células de Kupffer/efeitos dos fármacos , Células de Kupffer/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Camundongos Transgênicos , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacologia , Contagem de PlaquetasAssuntos
Neoplasias Encefálicas/genética , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica , Genes Homeobox , Glioma/genética , Células-Tronco Neoplásicas/metabolismo , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Feminino , Glioma/patologia , Glioma/terapia , HumanosRESUMO
Within regenerating tissues, aging is characterized by a progressive general deterioration of organ function, thought to be driven by the gradual depletion of functional adult stem cells. Although there are probably multifactorial mechanisms that result in compromized stem cell functionality with advancing age, the accumulation of DNA damage within the stem cell compartment is likely to make a major contribution to this process. However, the physiologic source of DNA damage within the different tissue specific stem cell compartments remains to be determined, as does the fate of stem cells exposed to such damage. Using the haematopoietic system as a model organ, we have recently shown that certain forms of physiologic stress, such as infection-associated inflammation and extensive blood loss, leads to the induction of biologically relevant levels of DNA damage in haematopoietic stem cells (HSCs) by dramatically increasing the proliferative index of this normally quiescent cell population. (1) We were also able to demonstrate that such stress-associated DNA damage was sufficient to completely deplete HSCs and promote severe aplastic anemia (SAA) in the Fanconi anemia (FA) knockout mouse model, which has compromized replication-associated DNA repair. In this "Extra Views" article, we extend this previous work to show that FA mice do not spontaneously develop a haematopoietic phenotype consistent with SAA, even at extreme old age. This suggests that HSC quiescence restricts the acquisition of DNA damage during aging and preserves the functional integrity of the stem cell pool. In line with this hypothesis, we provide an extended time course analysis of the response of FA knockout mice to chronic inflammatory stress and show that enforced HSC proliferation leads to a highly penetrant SAA phenotype, which closely resembles the progression of the disease in FA patients.
Assuntos
Dano ao DNA/fisiologia , Reparo do DNA/fisiologia , Anemia de Fanconi/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Estresse Oxidativo/fisiologia , Transdução de Sinais/fisiologia , Animais , Anemia de Fanconi/genética , Anemia de Fanconi/patologia , Células-Tronco Hematopoéticas/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
The molecular etiology of polycythemia vera (PV) remains incompletely understood. Patients harbor increased numbers of hematopoietic stem cells and display Epo-independent erythroid maturation. However, the molecular mechanism underlying Epo hypersensitivity and stem cell expansion is unclear. We have previously shown that the transcription factor nuclear factor erythroid-2 (NF-E2) is overexpressed in the majority of PV patients. Here we demonstrated that elevation of NF-E2 expression in healthy CD34(+) cells to levels observed in PV caused Epo-independent erythroid maturation and expansion of hematopoietic stem cell (HSC) and common myeloid progenitor (CMP) cell numbers. Silencing NF-E2 in PV patients reverted both aberrancies, demonstrating for the first time that NF-E2 overexpression is both required and sufficient for Epo independence and HSC/CMP expansion in PV.
Assuntos
Eritropoese/fisiologia , Células-Tronco Hematopoéticas/patologia , Células Progenitoras Mieloides/patologia , Subunidade p45 do Fator de Transcrição NF-E2/genética , Policitemia Vera/etiologia , Antígenos CD34/metabolismo , Proliferação de Células , Células Cultivadas , Eritropoetina/metabolismo , Citometria de Fluxo , Expressão Gênica/fisiologia , Inativação Gênica , Humanos , Subunidade p45 do Fator de Transcrição NF-E2/metabolismo , Policitemia Vera/genética , Policitemia Vera/patologiaRESUMO
The molecular etiology of myeloproliferative neoplasms (MPNs) remains incompletely understood, despite recent advances incurred through the discovery of several different mutations in MPN patients. We have recently described overexpression of the transcription factor NF-E2 in MPN patients and shown that elevated NF-E2 levels in vivo cause an MPN phenotype and predispose to leukemic transformation in transgenic mice. We report the presence of acquired insertion and deletion mutations in the NF-E2 gene in MPN patients. These result in truncated NF-E2 proteins that enhance wild-type (WT) NF-E2 function and cause erythrocytosis and thrombocytosis in a murine model. NF-E2 mutant cells acquire a proliferative advantage, witnessed by clonal dominance over WT NF-E2 cells in MPN patients. Our data underscore the role of increased NF-E2 activity in the pathophysiology of MPNs.
Assuntos
Neoplasias da Medula Óssea/genética , Mutação/genética , Transtornos Mieloproliferativos/genética , Subunidade p45 do Fator de Transcrição NF-E2/genética , Animais , Neoplasias da Medula Óssea/patologia , Transplante de Medula Óssea , Linhagem da Célula/genética , Proliferação de Células , Células Clonais , DNA/metabolismo , Células HEK293 , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Humanos , Janus Quinase 2/metabolismo , Camundongos , Proteínas Mutantes/metabolismo , Transtornos Mieloproliferativos/patologia , Subunidade p45 do Fator de Transcrição NF-E2/metabolismo , Ligação Proteica/genética , Estabilidade Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ativação Transcricional/genéticaRESUMO
The molecular pathophysiology of myeloproliferative neoplasms (MPNs) remains poorly understood. Based on the observation that the transcription factor NF-E2 is often overexpressed in MPN patients, independent of the presence of other molecular aberrations, we generated mice expressing an NF-E2 transgene in hematopoietic cells. These mice exhibit many features of MPNs, including thrombocytosis, leukocytosis, Epo-independent colony formation, characteristic bone marrow histology, expansion of stem and progenitor compartments, and spontaneous transformation to acute myeloid leukemia. The MPN phenotype is transplantable to secondary recipient mice. NF-E2 can alter histone modifications, and NF-E2 transgenic mice show hypoacetylation of histone H3. Treatment of mice with the histone deacetylase inhibitor (HDAC-I) vorinostat restored physiological levels of histone H3 acetylation, decreased NF-E2 expression, and normalized platelet numbers. Similarly, MPN patients treated with an HDAC-I exhibited a decrease in NF-E2 expression. These data establish a role for NF-E2 in the pathophysiology of MPNs and provide a molecular rationale for investigating epigenetic alterations as novel targets for rationally designed MPN therapies.