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Biomarkers such as hormone receptors (HR) and human epidermal growth factor receptor2 (HER2) may change after neoadjuvant chemotherapy (NAC) in breast cancer patients. The aim of this study was to investigate the rates of receptor change after NAC and to evaluate the prognostic impact of change. Patients with breast cancer who received NAC were included in the study. Changes in pathological findings (ER, PR, HER-2, Ki-67, grade) before and after NAC were examined. In addition, the effect of receptor exchange on prognosis was evaluated. Kaplan Meier analysis was used for survival analyses. Study was approved by Ethics Board of Tepecik Training and Research Hospital (Decision number 2021/10-02). We confirm that all methods were performed in accordance with relevant named guidelines and regulations. The study included 203 female patients. When pathological findings before and after NAC were compared, significant regression was found in grade and Ki-67 values (p = 0.003, p < 0.001). ER change rate was 11.8%, PR change rate was 24.6% and HER-2 change rate was 12.5%. No significant correlation was found between ER, PR and HER-2 changes and prognosis. The pathological T stage after NAC being 1 or 2, no lymph nodes detected, and the tumor grade being 1 or 2 were independent variables related to survival (p: 0.002, p: 0.014, p < 0.001). In patients with breast cancer, it would be appropriate to re-evaluate the HER-2 and HR status of the surgical specimen following NAC, especially in initially negative patients. The correlation of receptor discordance with prognosis is not clear and more extensive studies are needed.
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Biomarcadores Tumorais , Neoplasias da Mama , Terapia Neoadjuvante , Receptor ErbB-2 , Receptores de Progesterona , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/mortalidade , Terapia Neoadjuvante/métodos , Pessoa de Meia-Idade , Prognóstico , Biomarcadores Tumorais/metabolismo , Adulto , Receptor ErbB-2/metabolismo , Idoso , Receptores de Progesterona/metabolismo , Imuno-Histoquímica , Receptores de Estrogênio/metabolismo , Antígeno Ki-67/metabolismo , Estimativa de Kaplan-Meier , Quimioterapia AdjuvanteRESUMO
Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle, where it is best known for its role in store-operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focused on a gain-of-function mutation that occurs in humans and mice (STIM1+/D84G mice), in which muscles exhibited constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content, or excitation-contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1+/D84G muscle disrupted nuclear-cytosolic coupling, causing severe derangement in nuclear architecture, DNA damage, and altered lamina A-associated gene expression. Functionally, we found that D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts, resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.
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Debilidade Muscular , Membrana Nuclear , Molécula 1 de Interação Estromal , Animais , Humanos , Camundongos , Cálcio/metabolismo , Sinalização do Cálcio , Debilidade Muscular/genética , Debilidade Muscular/metabolismo , Músculo Esquelético/metabolismo , Mutação , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Membrana Nuclear/genética , Membrana Nuclear/metabolismo , Proteína ORAI1/genética , Molécula 1 de Interação Estromal/genética , Molécula 1 de Interação Estromal/metabolismoRESUMO
Purpose: N3 gastric cancer is characterized by a fairly high lymph node metastasis burden and poor outcome despite optimal therapy. Given the limitations of TNM classification, a comprehensive evaluation tool is necessary to predict the prognosis of patients with N3 gastric cancer who underwent curative surgery. This study aims to explore the outcomes and clinicopathologic prognostic factors affecting the overall survival (OS) of patients with N3 gastric cancer after surgery. Methods: Data on patients with N3 gastric cancer who underwent (sub)total gastrectomy and regional lymph node dissection between November 2005 and September 2018 (n = 169) were analyzed by Cox regression to determine the independent prognostic factors for OS. Results: The multivariable analysis established that gender, patient performance status, metastatic lymph node ratio (MLNR), tumor grade, and adjuvant chemotherapy are significantly associated with OS. The five-year OS of the study population was 15%. Adjuvant chemoradiotherapy was applied to 72% of the patients, which resulted in an improvement in recurrence-free survival but not OS. Recurrence occurred in 103 (75%) patients, in which the most frequent recurrence site was distant metastasis. Conclusion: Male gender, poor performance status, grade 3 tumor, MLNR > 0.37, and not receiving adjuvant chemotherapy are predictors of poor prognosis in N3 gastric cancer after curative resection. Considering the high recurrence rates of this group, prospective studies are needed to optimize treatment strategies.
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BACKGROUND: CDK4/6 inhibitors combined with endocrine therapy have significantly improved treatment outcomes for metastatic hormone receptor-positive (HR+) breast cancer patients. However, the impact of low HER2 expression on treatment response and progression-free survival (PFS) remains unclear. METHODS: This multicenter retrospective study included 204 HR+ breast cancer patients treated with a combination of CDK4/6 inhibitor and endocrine therapy. HER2-zero disease was detected in 138 (68%) and HER2-low disease in 66 (32%) patients. Treatment-related characteristics and clinical outcomes were analyzed, with a median follow-up of 22 months. RESULTS: The objective response rate (ORR) was 72.7% in the HER2 low group and 66.6% in the HER2 zero group (p = 0.54). Median PFS was not significantly different between the HER2-low and HER2 zero groups (19 months vs.18 months, p = 0.89), although there was a trend toward longer PFS in the HER2-low group for first-line treatment (24 months progression-free survival rate 63% vs 49%). In recurrent disease, the median PFS was 25 months in the HER2-low group and 12 months in the HER2-zero group (p = 0.08), while in de novo metastatic disease, the median PFS was 18 months in the HER2-low group and 27 months in the HER2-zero group (p = 0.16). The order of CDK4/6 inhibitor use and the presence of visceral metastasis were identified as independent variables affecting PFS. CONCLUSION: Low HER2 expression did not significantly impact treatment response or PFS in HR+ breast cancer patients treated with a CDK4/6 inhibitor and endocrine therapy. Because of the conflicting results in the literature, further prospective studies are needed to evaluate the clinical significance of HER2 expression in HR+ breast cancer.
Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/patologia , Estudos Retrospectivos , Receptor ErbB-2/metabolismo , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Resultado do Tratamento , Quinase 4 Dependente de CiclinaRESUMO
Stromal interaction molecule 1 (STIM1) is a Ca 2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle where it is best known for its role in store operated Ca 2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focus on a gain of function mutation that occurs in humans and mice (STIM1 +/D84G mice) where muscles exhibit constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca 2+ transients, SR Ca 2+ content or excitation contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1 +/D84G muscle disrupts nuclear-cytosolic coupling causing severe derangement in nuclear architecture, DNA damage, and altered lamina A associated gene expression. Functionally, we found D84G STIM1 reduced the transfer of Ca 2+ from the cytosol to the nucleus in myoblasts resulting in a reduction of [Ca 2+ ] N . Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca 2+ signaling to nuclear stability in skeletal muscle.
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OBJECTIVE: To evaluate the effect of pretreatment C-reactive protein (CRP)/Albumin ratio (CAR) on prognosis and its association with IMDC (International metastatic renal cell carcinoma database consortium) risk score and overall survival (OS) in metastatic renal cell carcinoma (mRCC) patients. STUDY DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Department of Medical Oncology, Dokuz Eylul University, Izmir, Turkey, between 2007 and 2020. METHODOLOGY: Clinico-pathological and treatment-related data of mRCC patients were retrospectively evaluated and included in the study. CAR was used as a prognostic inflammatory score. CAR threshold value for OS has been obtained by ROC analysis. The prognostic value of CAR was tested using Kaplan-Meier and Cox-regression models. IMDC-CAR model was created by adding CAR to IMDC risk stratification. RESULTS: OS was 91 months in patients with CAR below the threshold value of 0.072 (<0.072), while OS was 51 months in patients with CAR of 0.072 and above (p=0.005). According to IMDC risk stratification, intermediate and poor risk groups showed similar survival times (p>0.05). However, when CAR was added to the IMDC risk score in the intermediate group, it was divided into 3 subgroups with different prognoses (p=0.02). CONCLUSION: CAR is an independent predictor of OS in mRCC patients. In this study, it has been demonstrated that more accurate prognosis prediction could be made by adding CAR to IMDC indicators in the intermediate risk group, which constitutes a highly heterogeneous group according to IMDC risk stratification. KEY WORDS: Renal cell cancer, Albumin, C-reactive protein, IMDC, Prognosis.
Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Humanos , Carcinoma de Células Renais/patologia , Neoplasias Renais/patologia , Proteína C-Reativa/análise , Estudos Retrospectivos , Prognóstico , Medição de RiscoRESUMO
X chromosome inactivation (XCI) is a dosage compensation phenomenon that occurs in females. Initiation of XCI depends on Xist RNA, which triggers silencing of one of the two X chromosomes, except for XCI escape genes that continue to be biallelically expressed. In the soma XCI is stably maintained with continuous Xist expression. How Xist impacts XCI maintenance remains an open question. Here we conditionally delete Xist in hematopoietic system of mice and report differentiation and cell cycle defects in female hematopoietic stem and progenitor cells (HSPCs). By utilizing female HSPCs and mouse embryonic fibroblasts, we find that X-linked genes show variable tolerance to Xist loss. Specifically, XCI escape genes exhibit preferential transcriptional upregulation, which associates with low H3K27me3 occupancy and high chromatin accessibility that accommodates preexisting binding of transcription factors such as Yin Yang 1 (YY1) at the basal state. We conclude that Xist is necessary for gene-specific silencing during XCI maintenance and impacts lineage-specific cell differentiation and proliferation during hematopoiesis.
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RNA Longo não Codificante , Inativação do Cromossomo X , Animais , Diferenciação Celular/genética , Proliferação de Células/genética , Feminino , Fibroblastos/metabolismo , Hematopoese/genética , Camundongos , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Cromossomo X/metabolismo , Inativação do Cromossomo X/genéticaRESUMO
OBJECTIVE: At the time of diagnosis, approximately 16.5% of prostate cancer patients are metastatic. The main framework of metastatic prostate cancer treatment is androgen deprivation therapy, which is performed surgically or medically. The aim of this study is to evaluate the attitudes of medical oncologists and urologists about orchiectomy as androgen deprivation therapy. MATERIAL AND METHODS: A total of 387 physicians working in the Departments of Urology (n=217) and Medical Oncology (n=170) were included in this descriptive study. Data were collected through an electronic survey. RESULTS: Only 7.5% of participants indicated that they offered surgical castration to their patients. Urologists preferred surgical castration more than oncologists for the treatment of metastatic castration-sensitive prostate carcinoma (P=.003). The reasons why medical oncologists preferred surgical castration less are that it is an invasive procedure, has risk of morbidity and mortality, high cost of hospitalization, and may cause deterioration of the patient's body image (P < .05). CONCLUSION: This study showed that physicians were less likely to perform orchiectomy as an androgen deprivation therapy. Although the most important reason for this is the patient preference, the biased presentation of treatment options to patients, the lack of knowledge of physicians about orchiectomy, and the effect of the pharmaceutical industry should also be kept in mind.
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RBFOX2, which has a well-established role in alternative splicing, is linked to heart diseases. However, it is unclear whether RBFOX2 has other roles in RNA processing that can influence gene expression in muscle cells, contributing to heart disease. Here, we employ both 3'-end and nanopore cDNA sequencing to reveal a previously unrecognized role for RBFOX2 in maintaining alternative polyadenylation (APA) signatures in myoblasts. RBFOX2-mediated APA modulates mRNA levels and/or isoform expression of a collection of genes, including contractile and mitochondrial genes. Depletion of RBFOX2 adversely affects mitochondrial health in myoblasts, correlating with disrupted APA of mitochondrial gene Slc25a4. Mechanistically, RBFOX2 regulation of Slc25a4 APA is mediated through consensus RBFOX2 binding motifs near the distal polyadenylation site, enforcing the use of the proximal polyadenylation site. In sum, our results unveil a role for RBFOX2 in fine-tuning expression of mitochondrial and contractile genes via APA in myoblasts relevant to heart diseases.
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Mitocôndrias Cardíacas/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas Musculares/metabolismo , Mioblastos Cardíacos/metabolismo , Poliadenilação , Fatores de Processamento de RNA/metabolismo , Translocador 1 do Nucleotídeo Adenina/genética , Translocador 1 do Nucleotídeo Adenina/metabolismo , Animais , Regulação da Expressão Gênica , Células HEK293 , Humanos , Mitocôndrias Cardíacas/genética , Mitocôndrias Cardíacas/ultraestrutura , Proteínas Mitocondriais/genética , Proteínas Musculares/genética , Mioblastos Cardíacos/ultraestrutura , Fatores de Processamento de RNA/genética , Ratos , Tropomiosina/genética , Tropomiosina/metabolismoRESUMO
Nucleoporin proteins (Nups) have been proposed to mediate spatial and temporal chromatin organization during gene regulation. Nevertheless, the molecular mechanisms in mammalian cells are not well understood. Here, we report that Nucleoporin 153 (NUP153) interacts with the chromatin architectural proteins, CTCF and cohesin, and mediates their binding across cis-regulatory elements and TAD boundaries in mouse embryonic stem (ES) cells. NUP153 depletion results in altered CTCF and cohesin binding and differential gene expression - specifically at the bivalent developmental genes. To investigate the molecular mechanism, we utilize epidermal growth factor (EGF)-inducible immediate early genes (IEGs). We find that NUP153 controls CTCF and cohesin binding at the cis-regulatory elements and POL II pausing during the basal state. Furthermore, efficient IEG transcription relies on NUP153. We propose that NUP153 links the nuclear pore complex (NPC) to chromatin architecture allowing genes that are poised to respond rapidly to developmental cues to be properly modulated.
Assuntos
Fator de Ligação a CCCTC/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Animais , Fator de Ligação a CCCTC/química , Proteínas de Ciclo Celular/química , Linhagem Celular , Cromatina/química , Cromatina/genética , Proteínas Cromossômicas não Histona/química , Genes Precoces , Células HeLa , Humanos , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Poro Nuclear/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/deficiência , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , RNA Polimerase II/metabolismo , Elementos Reguladores de Transcrição , CoesinasRESUMO
Long thought to be dispensable after establishing X chromosome inactivation (XCI), Xist RNA is now known to also maintain the inactive X (Xi). To what extent somatic X reactivation causes physiological abnormalities is an active area of inquiry. Here, we use multiple mouse models to investigate in vivo consequences. First, when Xist is deleted systemically in post-XCI embryonic cells using the Meox2-Cre driver, female pups exhibit no morbidity or mortality despite partial X reactivation. Second, when Xist is conditionally deleted in epithelial cells using Keratin14-Cre or in B cells using CD19-Cre, female mice have a normal life span without obvious illness. Third, when Xist is deleted in gut using Villin-Cre, female mice remain healthy despite significant X-autosome dosage imbalance. Finally, when the gut is acutely stressed by azoxymethane/dextran sulfate (AOM/DSS) exposure, both Xist-deleted and wild-type mice develop gastrointestinal tumors. Intriguingly, however, under prolonged stress, mutant mice develop larger tumors and have a higher tumor burden. The effect is female specific. Altogether, these observations reveal a surprising systemic tolerance to Xist loss but importantly reveal that Xist and XCI are protective to females during chronic stress.
Assuntos
Neoplasias Gastrointestinais/fisiopatologia , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/microbiologia , RNA Longo não Codificante/genética , Cromossomo X/genética , Animais , Feminino , Neoplasias Gastrointestinais/etiologia , Neoplasias Gastrointestinais/genética , Neoplasias Gastrointestinais/metabolismo , Trato Gastrointestinal/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/complicações , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Humanos , Masculino , Camundongos , RNA Longo não Codificante/metabolismo , Estresse Fisiológico , Carga Tumoral , Inativação do Cromossomo XRESUMO
Background: In this study, we aimed to investigate the frequency, prognostic effect of codon, and amino acid-specific KRAS mutations in patients with metastatic colorectal cancer (mCRC) and their predictive effect on irinotecan and oxaliplatin during first-line treatment.Methods: The data of 304 mCRC patients were retrospectively evaluated between 2010 and 2018. Patients were categorized according to the most prominent codon and amino acid mutation and their prognostic features were analyzed.Results: In total, 274 patients were included in the study and 128 patients (47%) revealed KRAS mutation. Median follow-up time was 19.8 months (range; 1.6-96). The median overall survival rates for patients with codons 12 and 13 mutations were 25.4 and 22.2 months, respectively (p = 0.4). Moreover, the median overall survival for the codon 12 mutant patients who received irinotecan-based chemotherapy in the first-line treatment was 42.7 months, whereas for the codon 13 mutant and KRAS wild-type patients, it was 18.3 and 23.9 months, respectively (codon 12 vs. codon 13; HR: 0.31, p = 0.03, codon 12 vs. wild-type; HR: 0.45, p = 0.03).Conclusion: The significant survival advantage was observed in patients with codon 12 mutations who received irinotecan-based chemotherapy as a first-line treatment.
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Antineoplásicos/uso terapêutico , Neoplasias do Colo/genética , Irinotecano/uso terapêutico , Mutação , Oxaliplatina/uso terapêutico , Proteínas Proto-Oncogênicas p21(ras)/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/administração & dosagem , Antineoplásicos/efeitos adversos , Biomarcadores Tumorais/genética , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/patologia , Feminino , Humanos , Irinotecano/administração & dosagem , Irinotecano/efeitos adversos , Masculino , Pessoa de Meia-Idade , Oxaliplatina/administração & dosagem , Oxaliplatina/efeitos adversosRESUMO
Nuclear pore complex (NPC)-mediated nucleocytoplasmic trafficking is essential for key cellular processes, such as cell growth, cell differentiation, and gene regulation. The NPC has also been viewed as a nuclear architectural platform that impacts genome function and gene expression by mediating spatial and temporal coordination between transcription factors, chromatin regulatory proteins, and transcription machinery. Recent findings have uncovered differential and cell type-specific expression and distinct chromatin-binding patterns of individual NPC components known as nucleoporins (Nups). Here, we examine recent studies that investigate the functional roles of NPCs and Nups in transcription, chromatin organization, and epigenetic gene regulation in the context of development and disease.
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Cromatina/metabolismo , Regulação da Expressão Gênica/genética , Genoma/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Poro Nuclear/metabolismo , Animais , Cromatina/genética , Estruturas Cromossômicas/genética , Estruturas Cromossômicas/metabolismo , Drosophila/genética , Epigênese Genética , Humanos , Camundongos , Poro Nuclear/genética , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Conformação de Ácido Nucleico , Transcrição Gênica , Leveduras/genéticaRESUMO
In mammals, monoallelic gene expression can result from X-chromosome inactivation, genomic imprinting, and random monoallelic expression (RMAE). Epigenetic regulation of RMAE is not fully understood. Here we analyze allelic imbalance in chromatin state of autosomal genes using ChIP-seq in a clonal cell line. We identify approximately 3.7% of autosomal genes that show significant differences between chromatin states of two alleles. Allelic regulation is represented among several functional gene categories including histones, chromatin modifiers, and multiple early developmental regulators. Most cases of allelic skew are produced by quantitative differences between two allelic chromatic states that belong to the same gross type (active, silent, or bivalent). Combinations of allelic states of different types are possible but less frequent. When different chromatin marks are skewed on the same gene, their skew is coordinated as a result of quantitative relationships between these marks on each individual allele. Finally, combination of allele-specific densities of chromatin marks is a quantitative predictor of allelic skew in gene expression.
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Desequilíbrio Alélico , Cromatina/genética , Alelos , Animais , Linhagem Celular , Epigênese Genética , Feminino , Fibroblastos/metabolismo , Expressão Gênica , Genoma , Impressão Genômica , Masculino , Camundongos , Camundongos da Linhagem 129RESUMO
Hematologic parameters are important markers of disease in human and veterinary medicine. Biomedical research has benefited from mouse models that recapitulate such disease, thus expanding knowledge of pathogenetic mechanisms and investigative therapies that translate across species. Mice in health have many notable hematologic differences from humans and other veterinary species, including smaller erythrocytes, higher percentage of circulating reticulocytes or polychromasia, lower peripheral blood neutrophil and higher peripheral blood and bone marrow lymphocyte percentages, variable leukocyte morphologies, physiologic splenic hematopoiesis and iron storage, and more numerous and shorter-lived erythrocytes and platelets. For accurate and complete hematologic analyses of disease and response to investigative therapeutic interventions, these differences and the unique features of murine hematopathology must be understood. Here we review murine hematology and hematopathology for practical application to translational investigation.
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Doenças Hematológicas/sangue , Hematologia , Camundongos/sangue , Patologia Veterinária , Animais , Medula Óssea/patologia , Modelos Animais de Doenças , Doenças Hematológicas/etiologia , Doenças Hematológicas/terapia , Hematologia/métodos , Hematopoese , Humanos , Patologia Veterinária/métodos , Pesquisa Translacional Biomédica/métodosRESUMO
In mammals, several classes of monoallelic genes have been identified, including those subject to X-chromosome inactivation (XCI), genomic imprinting, and random monoallelic expression (RMAE). However, the extent to which these epigenetic phenomena are influenced by underlying genetic variation is unknown. Here we perform a systematic classification of allelic imbalance in mouse hybrids derived from reciprocal crosses of divergent strains. We observe that deviation from balanced biallelic expression is common, occurring in â¼20% of the mouse transcriptome in a given tissue. Allelic imbalance attributed to genotypic variation is by far the most prevalent class and typically is tissue-specific. However, some genotype-based imbalance is maintained across tissues and is associated with greater genetic variation, especially in 5' and 3' termini of transcripts. We further identify novel random monoallelic and imprinted genes and find that genotype can modify penetrance of parental origin even in the setting of large imprinted regions. Examination of nascent transcripts in single cells from inbred parental strains reveals that genes showing genotype-based imbalance in hybrids can also exhibit monoallelic expression in isogenic backgrounds. This surprising observation may suggest a competition between alleles and/or reflect the combined impact of cis- and trans-acting variation on expression of a given gene. Our findings provide novel insights into gene regulation and may be relevant to human genetic variation and disease.
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Desequilíbrio Alélico , Transcriptoma , Alelos , Animais , Análise por Conglomerados , Cruzamentos Genéticos , Perfilação da Expressão Gênica , Variação Genética , Impressão Genômica , Genótipo , Camundongos , Especificidade de Órgãos/genéticaRESUMO
In the thoracolumbar region, between 7% and 30% of spinal fusion failures are at risk for pseudarthrosis. From a biomechanical perspective, the nonconformity of the intervertebral graft to the endplate surface could contribute to pseudarthrosis, given suboptimal stress distributions. The objective of this study was to quantify the effect of endplate-graft conformation on endplate stress distribution, maximum Von Mises stress development, and stability. The study design used an experimentally validated finite element (FE) model of the L4-L5 functional spinal unit to simulate two types of interbody grafts (cortical bone and polycaprolactone (PCL)-hydroxyapatite (HA) graft), with and without endplate-conformed surfaces. Two case studies were completed. In Case Study I, the endplate-conformed grafts and nonconformed grafts were compared under without posterior instrumentation condition, while in Case Study II, the endplate-conformed and nonconformed grafts were compared with posterior instrumentation. In both case studies, the results suggested that the increased endplate-graft conformity reduced the maximum stress on the endplate, created uniform stress distribution on endplate surfaces, and reduced the range of motion of L4-L5 segments by increasing the contact surface area between the graft and the endplate. The stress distributions in the endplate suggest that the load sharing is greater with the endplate-conformed PCL-HA graft, which might reduce the graft subsidence possibility.
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Transplante Ósseo/métodos , Durapatita/química , Análise de Elementos Finitos , Vértebras Lombares/cirurgia , Fenômenos Mecânicos , Poliésteres/química , Fusão Vertebral/métodos , Fenômenos Biomecânicos , Vértebras Lombares/fisiologia , Movimento , Reprodutibilidade dos Testes , Estresse Mecânico , Propriedades de SuperfícieRESUMO
Gene expression is controlled by coordinated action of many epigenetic mechanisms including covalent histone modifications. Although numerous recurrent patterns of colocalized histone modifications have been associated with specific gene expression states, interrelationships between individual modifications are largely unknown. Here, we analyze quantitative relationships between colocalized histone marks during embryonic stem cell (ESC) differentiation and find that, for autosomal genes, these densities follow bimodal patterns. Analysis of repressive H3K27me3 and activating H3K4me3 modifications reveals the expected anticorrelation between them at active promoters but an unexpected positive correlation at inactive promoters. The two trends connect in a region corresponding to bivalent genes. Interestingly, this region is characterized by maximal H3K27 methylation. Resolving gene bivalency during ESC differentiation does not conform to the expected model of two marks as counteracting and competing forces. Although activated genes acquire H3K4me3 and lose H3K27me3, repressed genes lose H3K4me3 without gaining H3K27me3. The behavior of X-linked genes also deviates from expected models. Allele-specific analysis of chromatin modifications during X-chromosome inactivation (XCI) suggests that the silencing machinery focuses on active genes and depletion of H3K4me3 and that H3K27me3 is most significant during establishment of gene silencing. Our analysis reveals nontrivial relationships between H3K4me3 and H3K27me3, reveals unique aspects of gene bivalency, and demonstrates that XCI does not conform neatly to autosomal models.
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Diferenciação Celular/fisiologia , Células-Tronco Embrionárias/fisiologia , Epigênese Genética/fisiologia , Genes Ligados ao Cromossomo X/genética , Loci Gênicos/genética , Histonas/metabolismo , Animais , Imunoprecipitação da Cromatina , Sequenciamento de Nucleotídeos em Larga Escala , Histonas/genética , Modelos Lineares , Camundongos , Modelos Genéticos , Inativação do Cromossomo X/genéticaRESUMO
X chromosome aneuploidies have long been associated with human cancers, but causality has not been established. In mammals, X chromosome inactivation (XCI) is triggered by Xist RNA to equalize gene expression between the sexes. Here we delete Xist in the blood compartment of mice and demonstrate that mutant females develop a highly aggressive myeloproliferative neoplasm and myelodysplastic syndrome (mixed MPN/MDS) with 100% penetrance. Significant disease components include primary myelofibrosis, leukemia, histiocytic sarcoma, and vasculitis. Xist-deficient hematopoietic stem cells (HSCs) show aberrant maturation and age-dependent loss. Reconstitution experiments indicate that MPN/MDS and myelofibrosis are of hematopoietic rather than stromal origin. We propose that Xist loss results in X reactivation and consequent genome-wide changes that lead to cancer, thereby causally linking the X chromosome to cancer in mice. Thus, Xist RNA not only is required to maintain XCI but also suppresses cancer in vivo.
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Genes Supressores de Tumor , Síndromes Mielodisplásicas/genética , Transtornos Mieloproliferativos/genética , RNA Longo não Codificante/genética , Animais , Medula Óssea/fisiopatologia , Feminino , Genes Letais , Células-Tronco Hematopoéticas/metabolismo , Masculino , Camundongos , Mielofibrose Primária/genética , Esplenomegalia/metabolismo , Inativação do Cromossomo XRESUMO
X chromosome inactivation (XCI) achieves dosage balance in mammals by repressing one of two X chromosomes in females. During XCI, the long noncoding Xist RNA and Polycomb proteins spread along the inactive X (Xi) to initiate chromosome-wide silencing. Although inactivation is known to commence at the X-inactivation center (Xic), how it propagates remains unknown. Here, we examine allele-specific binding of Polycomb repressive complex 2 (PRC2) and chromatin composition during XCI and generate a chromosome-wide profile of Xi and Xa (active X) at nucleosome-resolution. Initially, Polycomb proteins are localized to â¼150 strong sites along the X and concentrated predominantly within bivalent domains coinciding with CpG islands ("canonical sites"). As XCI proceeds, â¼4000 noncanonical sites are recruited, most of which are intergenic, nonbivalent, and lack CpG islands. Polycomb sites are depleted of LINE repeats but enriched for SINEs and simple repeats. Noncanonical sites cluster around the â¼150 strong sites, and their H3K27me3 levels reflect a graded concentration originating from strong sites. This suggests that PRC2 and H3K27 methylation spread along a gradient unique to XCI. We propose that XCI is governed by a hierarchy of defined Polycomb stations that spread H3K27 methylation in cis.