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In exploring the evolutionary trajectories of both pathogenesis and karyotype dynamics in fungi, we conducted a large-scale comparative genomic analysis spanning the Cryptococcus genus, encompassing both global human fungal pathogens and nonpathogenic species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species, covering virtually all known diversity within these genera. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at preadaptive pathogenic potential, our analysis found evidence of gene gain (via horizontal gene transfer) and gene loss in pathogenic Cryptococcus species, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the 2 genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5, or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes showed reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Overall, our findings advance our understanding of genetic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.
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Cromosomas Fúngicos , Cryptococcus , Evolución Molecular , Genoma Fúngico , Genómica , Cariotipo , Cryptococcus/genética , Cryptococcus/patogenicidad , Cryptococcus/clasificación , Cromosomas Fúngicos/genética , Genómica/métodos , Filogenia , Sintenía , Centrómero/genética , Criptococosis/microbiología , HumanosRESUMEN
A large-scale comparative genomic analysis was conducted for the global human fungal pathogens within the Cryptococcus genus, compared to non-pathogenic Cryptococcus species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species of both genera, resulting in a dataset encompassing virtually all of their known diversity. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at pre-adaptive pathogenic potential, our analysis found evidence in pathogenic Cryptococcus species of specific examples of gene gain (via horizontal gene transfer) and gene loss, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the two genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5 or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes, underwent chromosome reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Taken together, our findings advance our understanding of genomic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.
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BACKGROUND: Histoplasmosis is a systemic mycosis caused by Histoplasma capsulatum (H. capsulatum). Systemic involvement of histoplasmosis usually occurs in immune-compromised patients, patients with AIDS, or those taking immunosuppressive therapy. The present study aims to describe the clinical and laboratory characteristics and treatment outcome of histoplasmosis as the diagnosis is challenging and management protocol differs. METHOD: This retrospective study was done using a data registry at the medicine department of Dhaka Medical College Hospital. Here, patients received the standard treatment of histoplasmosis. Here, patients received the standard treatment of histoplasmosis, and clinical outcome was assessed at 3 months following starting standard treatment. RESULT: A total of nine patients were enrolled, six (66.7%) had systemic histoplasmosis. Three were poultry workers, and the most common comorbidity was diabetes 3 (33.3%). Fever 7 (77.7%), weight loss 6 (66.7%), hyperpigmentation 5 (55.5%), cough 4 (44.4%), oral ulceration 4 (44.4%), lymphadenopathy 4 (44.4%), and hypotension 3 (33.3%) were the most common clinical presentations. Seven (77.7%) out of nine patients were cured of histoplasmosis; however, one died before initiating antifungal medications and another one died due to a hypersensitivity reaction to liposomal amphotericin B. Conclusion: For local histoplasmosis, oral itraconazole is an effective antifungal medication. However, in disseminated Histoplasmosis, liposomal amphotericin B followed by oral itraconazole is still one of the preferable and effective treatment options. Clinicians should be aware of hypersensitivity reactions of liposomal amphotericin B and its management before giving an infusion.
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Chronic lymphocytic leukemia (CLL) is characterized by disordered DNA methylation, suggesting these epigenetic changes might play a critical role in disease onset and progression. The methyltransferase DNMT3A is a key regulator of DNA methylation. Although DNMT3A somatic mutations in CLL are rare, we found that low DNMT3A expression is associated with more aggressive disease. A conditional knockout mouse model showed that homozygous depletion of Dnmt3a from B cells results in the development of CLL with 100% penetrance at a median age of onset of 5.3 months, and heterozygous Dnmt3a depletion yields a disease penetrance of 89% with a median onset at 18.5 months, confirming its role as a haploinsufficient tumor suppressor. B1a cells were confirmed as the cell of origin of disease in this model, and Dnmt3a depletion resulted in focal hypomethylation and activation of Notch and Myc signaling. Amplification of chromosome 15 containing the Myc gene was detected in all CLL mice tested, and infiltration of high-Myc-expressing CLL cells in the spleen was observed. Notably, hyperactivation of Notch and Myc signaling was exclusively observed in the Dnmt3a CLL mice, but not in three other CLL mouse models tested (Sf3b1-Atm, Ikzf3, and MDR), and Dnmt3a-depleted CLL were sensitive to pharmacologic inhibition of Notch signaling in vitro and in vivo. Consistent with these findings, human CLL samples with lower DNMT3A expression were more sensitive to Notch inhibition than those with higher DNMT3A expression. Altogether, these results suggest that Dnmt3a depletion induces CLL that is highly dependent on activation of Notch and Myc signaling. SIGNIFICANCE: Loss of DNMT3A expression is a driving event in CLL and is associated with aggressive disease, activation of Notch and Myc signaling, and enhanced sensitivity to Notch inhibition.
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ADN Metiltransferasa 3A/metabolismo , ADN Metiltransferasa 3A/fisiología , Modelos Animales de Enfermedad , Resistencia a Antineoplásicos , Leucemia Linfocítica Crónica de Células B/patología , Proteínas Proto-Oncogénicas c-myc/metabolismo , Receptores Notch/metabolismo , Animales , Antibacterianos/farmacología , Apoptosis , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Proliferación Celular , ADN Metiltransferasa 3A/genética , Daptomicina/farmacología , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Leucemia Linfocítica Crónica de Células B/metabolismo , Masculino , Ratones , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Pronóstico , Proteínas Proto-Oncogénicas c-myc/genética , RNA-Seq , Receptores Notch/antagonistas & inhibidores , Receptores Notch/genética , Tasa de Supervivencia , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
The integration of DNA methylation and transcriptional state within single cells is of broad interest. Several single-cell dual- and multi-omics approaches have been reported that enable further investigation into cellular heterogeneity, including the discovery and in-depth study of rare cell populations. Such analyses will continue to provide important mechanistic insights into the regulatory consequences of epigenetic modifications. We recently reported a new method for profiling the DNA methylome and transcriptome from the same single cells in a cancer research study. Here, we present details of the protocol and provide guidance on its utility. Our Smart-RRBS (reduced representation bisulfite sequencing) protocol combines Smart-seq2 and RRBS and entails physically separating mRNA from the genomic DNA. It generates paired epigenetic promoter and RNA-expression measurements for ~24% of protein-coding genes in a typical single cell. It also works for micro-dissected tissue samples comprising hundreds of cells. The protocol, excluding flow sorting of cells and sequencing, takes ~3 d to process up to 192 samples manually. It requires basic molecular biology expertise and laboratory equipment, including a PCR workstation with UV sterilization, a DNA fluorometer and a microfluidic electrophoresis system.
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ADN/metabolismo , Análisis de la Célula Individual , Secuencia de Aminoácidos , Antibacterianos/farmacología , ADN (Citosina-5-)-Metiltransferasas/genética , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Doxiciclina/farmacología , Epigenoma , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Humanos , Péptidos y Proteínas de Señalización Intracelular , ARN Mensajero/genética , ARN Mensajero/metabolismo , TranscriptomaRESUMEN
BACKGROUND: Osteoporosis is a gradually recognized health problem with risks related to disease history and living habits. This study aims to establish the optimal prediction model by comparing the performance of four prediction models that incorporated disease history and living habits in predicting the risk of Osteoporosis in Chongqing adults. METHODS: We conduct a cross-sectional survey with convenience sampling in this study. We use a questionnaire From January 2019 to December 2019 to collect data on disease history and adults' living habits who got dual-energy X-ray absorptiometry. We established the prediction models of osteoporosis in three steps. Firstly, we performed feature selection to identify risk factors related to osteoporosis. Secondly, the qualified participants were randomly divided into a training set and a test set in the ratio of 7:3. Then the prediction models of osteoporosis were established based on Artificial Neural Network (ANN), Deep Belief Network (DBN), Support Vector Machine (SVM) and combinatorial heuristic method (Genetic Algorithm - Decision Tree (GA-DT)). Finally, we compared the prediction models' performance through accuracy, sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC) to select the optimal prediction model. RESULTS: The univariate logistic model found that taking calcium tablet (odds ratio [OR] = 0.431), SBP (OR = 1.010), fracture (OR = 1.796), coronary heart disease (OR = 4.299), drinking alcohol (OR = 1.835), physical exercise (OR = 0.747) and other factors were related to the risk of osteoporosis. The AUCs of the training set and test set of the prediction models based on ANN, DBN, SVM and GA-DT were 0.901, 0.762; 0.622, 0.618; 0.698, 0.627; 0.744, 0.724, respectively. After evaluating four prediction models' performance, we selected a three-layer back propagation neural network (BPNN) with 18, 4, and 1 neuron in the input layer, hidden and output layers respectively, as the optimal prediction model. When the probability was greater than 0.330, osteoporosis would occur. CONCLUSIONS: Compared with DBN, SVM and GA-DT, the established ANN model had the best prediction ability and can be used to predict the risk of osteoporosis in physical examination of the Chongqing population. The model needs to be further improved through large sample research.
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Redes Neurales de la Computación , Osteoporosis , Adulto , China/epidemiología , Estudios Transversales , Hábitos , Humanos , Osteoporosis/epidemiología , Examen FísicoRESUMEN
Most human cancers converge to a deregulated methylome with reduced global levels and elevated methylation at select CpG islands. To investigate the emergence and dynamics of the cancer methylome, we characterized genome-wide DNA methylation in pre-neoplastic monoclonal B cell lymphocytosis (MBL) and chronic lymphocytic leukemia (CLL), including serial samples collected across disease course. We detected the aberrant tumor-associated methylation landscape at CLL diagnosis and found no significantly differentially methylated regions in the high-count MBL-to-CLL transition. Patient methylomes showed remarkable stability with natural disease and post-therapy progression. Single CLL cells were consistently aberrantly methylated, indicating a homogeneous transition to the altered epigenetic state, and a distinct expression profile together with MBL cells compared to normal B cells. Our longitudinal analysis reveals the cancer methylome to emerge early, which may provide a platform for subsequent genetically-driven growth dynamics and together with its persistent presence suggests a central role in the normal-to-cancer transition.
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Epigenoma , Leucemia Linfocítica Crónica de Células B , Islas de CpG/genética , Metilación de ADN/genética , Progresión de la Enfermedad , Humanos , Leucemia Linfocítica Crónica de Células B/diagnósticoRESUMEN
Leukemic relapse remains a major barrier to successful allogeneic hematopoietic stem cell transplantation (allo-HSCT) for aggressive hematologic malignancies. The basis for relapse of advanced lymphoid malignancies remains incompletely understood and may involve escape from the graft-versus-leukemia (GvL) effect. We hypothesized that for patients with chronic lymphocytic leukemia (CLL) treated with allo-HSCT, leukemic cell-intrinsic features influence transplant outcomes by directing the evolutionary trajectories of CLL cells. Integrated genetic, transcriptomic, and epigenetic analyses of CLL cells from 10 patients revealed that the clinical kinetics of post-HSCT relapse are shaped by distinct molecular dynamics. Early relapses after allo-HSCT exhibited notable genetic stability; single CLL cell transcriptional analysis demonstrated a cellular heterogeneity that was static over time. In contrast, CLL cells relapsing late after allo-HSCT displayed notable genetic evolution and evidence of neoantigen depletion, consistent with marked single-cell transcriptional shifts that were unique to each patient. We observed a greater rate of epigenetic change for late relapses not seen in early relapses or relapses after chemotherapy alone, suggesting that the selection pressures of the GvL bottleneck are unlike those imposed by chemotherapy. No selective advantage for human leukocyte antigen (HLA) loss was observed, even when present in pretransplant subpopulations. Gain of stem cell modules was a common signature associated with leukemia relapse regardless of posttransplant relapse kinetics. These data elucidate the biological pathways that underlie GvL resistance and posttransplant relapse.
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Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Leucemia Linfocítica Crónica de Células B , Efecto Injerto vs Leucemia , Antígenos HLA , Humanos , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfocítica Crónica de Células B/terapia , Trasplante HomólogoRESUMEN
PURPOSE: NUSAP1 has been reported to be involved in the progression of several types of cancer. However, its expression and exact role in bladder cancer (BLCA) remains elusive. The aim of this study was to determine the expression and role of NUSAP1 in BLCA. METHODS: Tissue microarray, real-time PCR, Western blot and immunohistochemistry assays were carried out to determine NUSAP1 expression in BLCA tissues and cells. The biological roles of NUSAP1 were investigated using CCK-8, EdU labeling, flow cytometry, Transwell, and wound healing assays. Additionally, the effect of NUSAP1 on epithelial-mesenchymal transition (EMT) was investigated by Western blotting and real-time PCR. RESULTS: We found that NUSAP1 was upregulated in BLCA, and its expression was closely related to the poor prognosis of patients. Subsequently, we transfected 5637 and T24 cell lines with NUSAP1 siRNA and an NUSAP1 overexpression plasmid, respectively. NUSAP1 downregulation in 5637 cells inhibited cell proliferation, migration, and invasiveness and enhanced chemosensitivity to gemcitabine, while NUSAP1 overexpression in T24 cells resulted in the inverse effects. Moreover, NUSAP1 regulated EMT via the TGF-ß signaling pathway, and when TGF-beta receptor 1 (TGFBR1) was inhibited with the inhibitor SB525334, the invasion and metastasis ability of BLCA cells was significantly suppressed, as well as p-Smad2/3 and vimentin expression. CONCLUSION: Our above data demonstrate that NUSAP1 contributes to BLCA progression via the TGF-ß signaling pathway.
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PURPOSE: To share experience in managing ureteral strictures following ureteroscopic lithotripsy. METHODS: Ninety five patients diagnosed as ureteral strictures after ureteroscopic lithotripsy between January 2013 and January 2018 were included. 53 received endourological treatment, 34 underwent reconstruction, 6 underwent nephrectomy for severe renal impairment, and 2 chose routine ureteral stent replacement. Therapeutic success was defined as absence of clinical symptoms and radiologic relief of obstruction. RESULTS: The follow-up time ranged from 13 to 57 months, with a median time of 24. It lasted more than 13 months in all patients, exception for 2 nephrectomies. Two patient groups including 69 endourological procedures and 37 reconstructions were used to compare therapeutic effects and complications. The overall success rate was 60.9% (42/69) in endourological intervention vs. 97.3% (36/37) in reconstruction (p < 0.001), while 74.4% (29/39) patients with stricture less than 1 cm and 68.8% (33/48) patients with mild-to-moderate hydronephrosis achieved success in endourological group. All except 1 failure appeared within the first year postoperatively. Subgroup analyses for endourological procedures revealed significant differences in the success rate of different stricture lengths and hydronephrosis (p = 0.004 and p = 0.043). Multivariate Cox regression analysis indicated that reconstruction was significantly related to a more successful outcome, compared with endourological procedures (HR 0.052, 95% CI 0.007-0.394, p = 0.004). CONCLUSION: Reconstruction performs better than endourological procedures in surgical outcome. Endourological procedure provides an acceptable success rate in patients with stricture shorter than 1 cm and slight hydronephrosis. Most stricture recurrence appeared within the first year postoperatively.
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Complicaciones Posoperatorias/cirugía , Obstrucción Ureteral/cirugía , Ureteroscopía , Adulto , Anciano , Constricción Patológica/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Cálculos Ureterales/cirugía , Adulto JovenRESUMEN
The biological characteristics of bladder cancer include enhanced invasion and migration, which are the main causes of death in patients. Starvation is a typical feature of the bladder cancer microenvironment and can induce autophagy. Autophagy has an important relationship with the invasion and migration of tumors. However, the role of autophagy in the invasion and migration of bladder cancer cells remains unclear. Hence, the aim of the current study was to clarify this role and underlying mechanism. In this study, we found that starvation enhanced the epithelial-mesenchymal transition (EMT)-mediated invasion and migration of T24 and 5637 cells while inducing autophagy. The inhibition of autophagy with chloroquine (CQ) or 3-methyladenine (3MA) decreased EMT-mediated invasion and migration. In addition, the expression of transforming growth factor 1 (TGF-ß1) and phosphorylated Smad3 (p-Smad3) increased after starvation. The inhibition of autophagy with CQ or 3MA also decreased the expression of TGF-ß1 and p-Smad3. The inhibitor of TGF-ß receptor sb431542 also inhibited the invasion, migration, and EMT of T24 and 5637 cells during starvation. Furthermore, recombinant TGF-ß1 induced autophagy and inhibition of the TGF-ß/Smad signaling pathway with sb431542 suppressed autophagy. In summary, our results suggested that autophagy promotes the invasion and migration of bladder cancer cells by inducing EMT through the TGF-ß1/Smad3 signaling pathway. Moreover, autophagy and TGF-ß1 can form a positive feedback loop to synergistically promote invasion and migration. Thus, our findings may provide a theoretical basis for the prevention of invasion and migration in bladder cancer.
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Autofagia , Movimiento Celular , Transición Epitelial-Mesenquimal , Proteína smad3/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Neoplasias de la Vejiga Urinaria/metabolismo , Neoplasias de la Vejiga Urinaria/patología , Línea Celular Tumoral , Humanos , Invasividad Neoplásica , Transducción de SeñalRESUMEN
Cystadenomas of the seminal vesicles are extremely rare. Here, we report a large seminal vesicle cystadenoma. A 37-year-old man presented a 6-month history of haemospermia, 10 days of Lower Urinary Tract symptoms (LUTSs) and gross haematuria. Transabdominal ultrasonography, computed tomography and magnetic resonance imaging were performed and revealed a large solid-cystic pelvic mass morphometrically measured 7.0 cm × 11.9 cm × 8.6 cm on the right seminal vesicle, which caused hydronephrosis of the right kidney. The prostate-specific antigen of the patient was 27.860 ng/dl. Laparoscopic exploration found the capsule of tumour was complete and the tumour came from the right seminal vesicle, in addition, the mass had a certain space with the bladder and prostate, which could be separated. So a nerve-sparing Laparoscopic Vesiculectomy was performed at last, even though the intraoperative frozen section analysis could not make sure the nature of the tumour either. The postoperative pathology revealed cystadenoma of the seminal vesicle.
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Cistoadenoma/cirugía , Neoplasias de los Genitales Masculinos/cirugía , Laparoscopía/métodos , Vesículas Seminales/cirugía , Procedimientos Quirúrgicos Urogenitales/métodos , Cistoadenoma/diagnóstico por imagen , Neoplasias de los Genitales Masculinos/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Masculino , Vesículas Seminales/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , UltrasonografíaRESUMEN
CTLA-4 immune checkpoint blockade is clinically effective in a subset of patients with metastatic melanoma. We identify a subcluster of MAGE-A cancer-germline antigens, located within a narrow 75 kb region of chromosome Xq28, that predicts resistance uniquely to blockade of CTLA-4, but not PD-1. We validate this gene expression signature in an independent anti-CTLA-4-treated cohort and show its specificity to the CTLA-4 pathway with two independent anti-PD-1-treated cohorts. Autophagy, a process critical for optimal anti-cancer immunity, has previously been shown to be suppressed by the MAGE-TRIM28 ubiquitin ligase in vitro. We now show that the expression of the key autophagosome component LC3B and other activators of autophagy are negatively associated with MAGE-A protein levels in human melanomas, including samples from patients with resistance to CTLA-4 blockade. Our findings implicate autophagy suppression in resistance to CTLA-4 blockade in melanoma, suggesting exploitation of autophagy induction for potential therapeutic synergy with CTLA-4 inhibitors.
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Antígeno CTLA-4/genética , Antígeno CTLA-4/inmunología , Epigénesis Genética , Mutación de Línea Germinal , Neoplasias/genética , Neoplasias/inmunología , Animales , Anticuerpos Monoclonales/uso terapéutico , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/inmunología , Autofagia , Línea Celular Tumoral , Metilación de ADN , Femenino , Perfilación de la Expresión Génica , Humanos , Inmunoterapia , Ipilimumab/farmacología , Masculino , Melanoma/genética , Melanoma/inmunología , Antígenos Específicos del Melanoma/genética , Antígenos Específicos del Melanoma/inmunología , Ratones , Ratones Transgénicos , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/inmunologíaRESUMEN
In normal mammalian development cytosine methylation is essential and is directed to specific regions of the genome. Despite notable advances through mapping its genome-wide distribution, studying the direct contribution of DNA methylation to gene and genome regulation has been limited by the lack of tools for its precise manipulation. Thus, combining the targeting capability of the CRISPR-Cas9 system with an epigenetic modifier has attracted interest in the scientific community. In contrast to profiling the genome-wide cleavage of a nuclease competent Cas9, tracing the global activity of a dead Cas9 (dCas9) methyltransferase fusion protein is challenging within a highly methylated genome. Here, we report the generation and use of an engineered, methylation depleted but maintenance competent mouse ES cell line and find surprisingly ubiquitous nuclear activity of dCas9-methyltransferases. Subsequent experiments in human somatic cells refine these observations and point to an important difference between genetic and epigenetic editing tools that require unique experimental considerations.
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Línea Celular , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Células Madre Embrionarias/enzimología , Animales , Proteínas Bacterianas , Proteína 9 Asociada a CRISPR , Endonucleasas , Edición Génica , Humanos , RatonesRESUMEN
Concomitant activation of the Wnt pathway and suppression of Mapk signalling by two small molecule inhibitors (2i) in the presence of leukaemia inhibitory factor (LIF) (hereafter termed 2i/L) induces a naive state in mouse embryonic stem (ES) cells that resembles the inner cell mass (ICM) of the pre-implantation embryo. Since the ICM exists only transiently in vivo, it remains unclear how sustained propagation of naive ES cells in vitro affects their stability and functionality. Here we show that prolonged culture of male mouse ES cells in 2i/L results in irreversible epigenetic and genomic changes that impair their developmental potential. Furthermore, we find that female ES cells cultured in conventional serum plus LIF medium phenocopy male ES cells cultured in 2i/L. Mechanistically, we demonstrate that the inhibition of Mek1/2 is predominantly responsible for these effects, in part through the downregulation of DNA methyltransferases and their cofactors. Finally, we show that replacement of the Mek1/2 inhibitor with a Src inhibitor preserves the epigenetic and genomic integrity as well as the developmental potential of ES cells. Taken together, our data suggest that, although short-term suppression of Mek1/2 in ES cells helps to maintain an ICM-like epigenetic state, prolonged suppression results in irreversible changes that compromise their developmental potential.