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1.
J Hepatol ; 73(4): 896-905, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32376414

RESUMO

BACKGROUND & AIMS: Non-alcoholic steatohepatitis (NASH) is a chronic liver disease characterized by hepatic lipid accumulation, inflammation, and progressive fibrosis. Acetyl-CoA carboxylase (ACC) catalyzes the rate-limiting step of de novo lipogenesis and regulates fatty acid ß-oxidation in hepatocytes. ACC inhibition reduces hepatic fat content and markers of liver injury in patients with NASH; however, the effect of ACC inhibition on liver fibrosis has not been reported. METHODS: A direct role for ACC in fibrosis was evaluated by measuring de novo lipogenesis, procollagen production, gene expression, glycolysis, and mitochondrial respiration in hepatic stellate cells (HSCs) in the absence or presence of small molecule inhibitors of ACC. ACC inhibitors were evaluated in rodent models of liver fibrosis induced by diet or the hepatotoxin, diethylnitrosamine. Fibrosis and hepatic steatosis were evaluated by histological and biochemical assessments. RESULTS: Inhibition of ACC reduced the activation of TGF-ß-stimulated HSCs, as measured by both α-SMA expression and collagen production. ACC inhibition prevented a metabolic switch necessary for induction of glycolysis and oxidative phosphorylation during HSC activation. While the molecular mechanism by which inhibition of de novo lipogenesis blocks glycolysis and oxidative phosphorylation is unknown, we definitively show that HSCs require de novo lipogenesis for activation. Consistent with this direct antifibrotic mechanism in HSCs, ACC inhibition reduced liver fibrosis in a rat choline-deficient, high-fat diet model and in response to chronic diethylnitrosamine-induced liver injury (in the absence of hepatic lipid accumulation). CONCLUSIONS: In addition to reducing lipid accumulation in hepatocytes, ACC inhibition also directly impairs the profibrogenic activity of HSCs. Thus, small molecule inhibitors of ACC may lessen fibrosis by reducing lipotoxicity in hepatocytes and by preventing HSC activation, providing a mechanistic rationale for the treatment of patients with advanced liver fibrosis due to NASH. LAY SUMMARY: Hepatic fibrosis is the most important predictor of liver-related outcomes in patients with non-alcoholic steatohepatitis (NASH). Small molecule inhibitors of acetyl-CoA carboxylase (ACC) reduce hepatic fat content and markers of liver injury in patients with NASH. Herein, we report that inhibition of ACC and de novo lipogenesis also directly suppress the activation of hepatic stellate cells - the primary cell responsible for generating fibrotic scar in the liver - and thus fibrosis. These data provide further evidence for the use of ACC inhibitors to treat patients with NASH and advanced fibrosis.


Assuntos
Acetil-CoA Carboxilase/antagonistas & inibidores , Células Estreladas do Fígado/metabolismo , Lipogênese/efeitos dos fármacos , Cirrose Hepática/metabolismo , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , Animais , Biomarcadores/metabolismo , Linhagem Celular , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Células Estreladas do Fígado/efeitos dos fármacos , Células Estreladas do Fígado/patologia , Humanos , Fígado/metabolismo , Cirrose Hepática/etiologia , Cirrose Hepática/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Ratos , Ratos Wistar
2.
Hepatology ; 68(6): 2197-2211, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29790582

RESUMO

Pharmacologic inhibition of acetyl-CoA carboxylase (ACC) enzymes, ACC1 and ACC2, offers an attractive therapeutic strategy for nonalcoholic fatty liver disease (NAFLD) through simultaneous inhibition of fatty acid synthesis and stimulation of fatty acid oxidation. However, the effects of ACC inhibition on hepatic mitochondrial oxidation, anaplerosis, and ketogenesis in vivo are unknown. Here, we evaluated the effect of a liver-directed allosteric inhibitor of ACC1 and ACC2 (Compound 1) on these parameters, as well as glucose and lipid metabolism, in control and diet-induced rodent models of NAFLD. Oral administration of Compound 1 preferentially inhibited ACC enzymatic activity in the liver, reduced hepatic malonyl-CoA levels, and enhanced hepatic ketogenesis by 50%. Furthermore, administration for 6 days to high-fructose-fed rats resulted in a 20% reduction in hepatic de novo lipogenesis. Importantly, long-term treatment (21 days) significantly reduced high-fat sucrose diet-induced hepatic steatosis, protein kinase C epsilon activation, and hepatic insulin resistance. ACCi treatment was associated with a significant increase in plasma triglycerides (approximately 30% to 130%, depending on the length of fasting). ACCi-mediated hypertriglyceridemia could be attributed to approximately a 15% increase in hepatic very low-density lipoprotein production and approximately a 20% reduction in triglyceride clearance by lipoprotein lipase (P ≤ 0.05). At the molecular level, these changes were associated with increases in liver X receptor/sterol response element-binding protein-1 and decreases in peroxisome proliferator-activated receptor-α target activation and could be reversed with fenofibrate co-treatment in a high-fat diet mouse model. Conclusion: Collectively, these studies warrant further investigation into the therapeutic utility of liver-directed ACC inhibition for the treatment of NAFLD and hepatic insulin resistance.


Assuntos
Acetil-CoA Carboxilase/metabolismo , Resistência à Insulina , Fígado/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Triglicerídeos/sangue , Acetil-CoA Carboxilase/antagonistas & inibidores , Animais , Ácidos Graxos não Esterificados/sangue , Cetonas/metabolismo , Lipogênese , Lipoproteínas VLDL/sangue , Masculino , Análise do Fluxo Metabólico , PPAR alfa/agonistas , Ratos Sprague-Dawley , Receptores Citoplasmáticos e Nucleares/metabolismo
3.
Bioorg Med Chem ; 27(3): 457-469, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30606676

RESUMO

The bromodomain and extra-terminal (BET) family of proteins, consisting of the bromodomains containing protein 2 (BRD2), BRD3, BRD4, and the testis-specific BRDT, are key epigenetic regulators of gene transcription and has emerged as an attractive target for anticancer therapy. Herein, we describe the discovery of a novel potent BET bromodomain inhibitor, using a systematic structure-based approach focused on improving potency, metabolic stability, and permeability. The optimized dimethylisoxazole aryl-benzimidazole inhibitor exhibited high potency towards BRD4 and related BET proteins in biochemical and cell-based assays and inhibited tumor growth in two proof-of-concept preclinical animal models.


Assuntos
Benzimidazóis/farmacologia , Descoberta de Drogas , Isoxazóis/farmacologia , Mieloma Múltiplo/tratamento farmacológico , Fatores de Transcrição/antagonistas & inibidores , Administração Oral , Animais , Benzimidazóis/química , Benzimidazóis/metabolismo , Disponibilidade Biológica , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Isoxazóis/administração & dosagem , Isoxazóis/química , Isoxazóis/metabolismo , Camundongos , Estrutura Molecular , Mieloma Múltiplo/metabolismo , Mieloma Múltiplo/patologia , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Domínios Proteicos/efeitos dos fármacos , Relação Estrutura-Atividade , Fatores de Transcrição/metabolismo
4.
Proc Natl Acad Sci U S A ; 113(31): E4558-66, 2016 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-27432991

RESUMO

Bromodomain and extraterminal domain protein inhibitors (BETi) hold great promise as a novel class of cancer therapeutics. Because acquired resistance typically limits durable responses to targeted therapies, it is important to understand mechanisms by which tumor cells adapt to BETi. Here, through pooled shRNA screening of colorectal cancer cells, we identified tripartite motif-containing protein 33 (TRIM33) as a factor promoting sensitivity to BETi. We demonstrate that loss of TRIM33 reprograms cancer cells to a more resistant state through at least two mechanisms. TRIM33 silencing attenuates down-regulation of MYC in response to BETi. Moreover, loss of TRIM33 enhances TGF-ß receptor expression and signaling, and blocking TGF-ß receptor activity potentiates the antiproliferative effect of BETi. These results describe a mechanism for BETi resistance and suggest that combining inhibition of TGF-ß signaling with BET bromodomain inhibition may offer new therapeutic benefits.


Assuntos
Azepinas/farmacologia , Proteínas/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-myc/metabolismo , Fatores de Transcrição/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Triazóis/farmacologia , Azepinas/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Resistência a Medicamentos/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células HCT116 , Células HEK293 , Humanos , Estrutura Molecular , Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Interferência de RNA , Receptores de Fatores de Crescimento Transformadores beta/genética , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Fatores de Transcrição/genética , Fator de Crescimento Transformador beta/genética , Triazóis/química
5.
Nature ; 477(7365): 424-30, 2011 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-21909113

RESUMO

Immunoglobulin heavy chain (IgH) variable region exons are assembled from V(H), D and J(H) gene segments in developing B lymphocytes. Within the 2.7-megabase mouse Igh locus, V(D)J recombination is regulated to ensure specific and diverse antibody repertoires. Here we report in mice a key Igh V(D)J recombination regulatory region, termed intergenic control region 1 (IGCR1), which lies between the V(H) and D clusters. Functionally, IGCR1 uses CTCF looping/insulator factor-binding elements and, correspondingly, mediates Igh loops containing distant enhancers. IGCR1 promotes normal B-cell development and balances antibody repertoires by inhibiting transcription and rearrangement of D(H)-proximal V(H) gene segments and promoting rearrangement of distal V(H) segments. IGCR1 maintains ordered and lineage-specific V(H)(D)J(H) recombination by suppressing V(H) joining to D segments not joined to J(H) segments, and V(H) to DJ(H) joins in thymocytes, respectively. IGCR1 is also required for feedback regulation and allelic exclusion of proximal V(H)-to-DJ(H) recombination. Our studies elucidate a long-sought Igh V(D)J recombination control region and indicate a new role for the generally expressed CTCF protein.


Assuntos
DNA Intergênico/genética , Rearranjo Gênico de Cadeia Pesada de Linfócito B/genética , Recombinação Genética/genética , Sequências Reguladoras de Ácido Nucleico/genética , Proteínas Repressoras/metabolismo , Éxons VDJ/genética , Animais , Linfócitos B/citologia , Linfócitos B/metabolismo , Fator de Ligação a CCCTC , Linhagem da Célula/genética , Cromossomos de Mamíferos/genética , Cromossomos de Mamíferos/metabolismo , Elementos Facilitadores Genéticos/genética , Retroalimentação Fisiológica , Células Germinativas/metabolismo , Cadeias Pesadas de Imunoglobulinas/genética , Região Variável de Imunoglobulina/genética , Camundongos , Mutação/genética , Timo/citologia , Transcrição Gênica/genética
6.
EJHaem ; 4(2): 370-380, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37206279

RESUMO

Signal regulatory protein alpha (SIRPα) is the receptor for cluster of differentiation (CD)47, a potent "don't eat me" signal for macrophages. Disruption of CD47-SIRPα signaling in the presence of prophagocytic signals can lead to enhanced phagocytosis of tumor cells, resulting in a direct antitumor effect; agents targeting this pathway have shown efficacy in non-Hodgkin lymphoma (NHL) and other tumor types. GS-0189 is a novel anti-SIRPα humanized monoclonal antibody. Here we report: (1) clinical safety, preliminary activity, and pharmacokinetics of GS-0189 as monotherapy and in combination with rituximab from a phase 1 clinical trial in patients with relapsed/refractory NHL (NCT04502706, SRP001); (2) in vitro characterization of GS-0189 binding to SIRPα; and (3) in vitro phagocytic activity. Clinically, GS-0189 was well tolerated in patients with relapsed/refractory NHL with evidence of clinical activity in combination with rituximab. Receptor occupancy (RO) of GS-0189 was highly variable in NHL patients; binding affinity studies showed significantly higher affinity for SIRPα variant 1 than variant 2, consistent with RO in patient and healthy donor samples. In vitro phagocytosis induced by GS-0189 was also SIRPα variant-dependent. Although clinical development of GS-0189 was discontinued, the CD47-SIRPα signaling pathway remains a promising therapeutic target and should continue to be explored.

7.
Hepatol Commun ; 6(9): 2298-2309, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35735253

RESUMO

Dysregulated hepatocyte lipid metabolism is a hallmark of hepatic lipotoxicity and contributes to the pathogenesis of nonalcoholic steatohepatitis (NASH). Acetyl CoA carboxylase (ACC) inhibitors decrease hepatocyte lipotoxicity by inhibiting de novo lipogenesis and concomitantly increasing fatty acid oxidation (FAO), and firsocostat, a liver-targeted inhibitor of ACC1/2, is under evaluation clinically in patients with NASH. ACC inhibition is associated with improvements in indices of NASH and reduced liver triglyceride (TG) content, but also increased circulating TG in subjects with NASH and preclinical rodent models. Here we evaluated whether enhancing hepatocyte FAO by combining ACC inhibitors with peroxisomal proliferator-activated receptor (PPAR) or thyroid hormone receptor beta (THRß) agonists could drive greater liver TG reduction and NASH/antifibrotic efficacy, while ameliorating ACC inhibitor-induced hypertriglyceridemia. In high-fat diet-fed dyslipidemic rats, the addition of PPAR agonists fenofibrate (Feno), elafibranor (Ela), lanifibranor (Lani), seladelpar (Sela) or saroglitazar (Saro), or the THRb agonist resmetirom (Res), to an analogue of firsocostat (ACCi) prevented ACCi-induced hypertriglyceridemia. However, only PPARα agonists (Feno and Ela) and Res provided additional liver TG reduction. In the choline-deficient high-fat diet rat model of advanced liver fibrosis, neither PPARα (Feno) nor THRß (Res) agonism augmented the antifibrotic efficacy of ACCi. Conclusion: These data suggest that combination therapies targeting hepatocyte lipid metabolism may have beneficial effects on liver TG reduction; however, they may not be sufficient to drive fibrosis regression.


Assuntos
Fenofibrato , Hipertrigliceridemia , Hepatopatia Gordurosa não Alcoólica , Acetatos , Acetil-CoA Carboxilase , Animais , Fenofibrato/farmacologia , Humanos , Cirrose Hepática/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , PPAR alfa/uso terapêutico , Ratos , Triglicerídeos/uso terapêutico
8.
PLoS One ; 17(8): e0270273, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35925919

RESUMO

Chronic hepatitis B virus (HBV) infection is characterized by the presence of high circulating levels of non-infectious lipoprotein-like HBV surface antigen (HBsAg) particles thought to contribute to chronic immune dysfunction in patients. Lipid and metabolomic analysis of humanized livers from immunodeficient chimeric mice (uPA/SCID) revealed that HBV infection dysregulates several lipid metabolic pathways. Small molecule inhibitors of lipid biosynthetic pathway enzymes acetyl-CoA carboxylase (ACC), fatty acid synthase, and subtilisin kexin isozyme-1/site-1 protease in HBV-infected HepG2-NTCP cells demonstrated potent and selective reduction of extracellular HBsAg. However, a liver-targeted ACC inhibitor did not show antiviral activity in HBV-infected liver chimeric mice, despite evidence of on-target engagement. Our study suggests that while HBsAg production may be dependent on hepatic de novo lipogenesis in vitro, this may be overcome by extrahepatic sources (such as lipolysis or diet) in vivo. Thus, a combination of agents targeting more than one lipid metabolic pathway may be necessary to reduce HBsAg levels in patients with chronic HBV infection.


Assuntos
Hepatite B Crônica , Hepatite B , Animais , Antivirais/metabolismo , Antivirais/farmacologia , Antivirais/uso terapêutico , DNA Viral/metabolismo , Antígenos de Superfície da Hepatite B/metabolismo , Vírus da Hepatite B/genética , Hepatite B Crônica/tratamento farmacológico , Lipídeos/uso terapêutico , Camundongos , Camundongos SCID
9.
Sci Transl Med ; 13(616): eabe8939, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34669440

RESUMO

Noninvasive detection of nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease, promises to improve patient screening, accelerate drug trials, and reduce health care costs. On the basis of protease dysregulation of the biological pathways of fibrotic NASH, we developed the Glympse Bio Test System (GBTS) for multiplexed quantification of liver protease activity. GBTS-NASH comprises a mixture of 19 mass-barcoded PEGylated peptides that is administered intravenously and senses liver protease activity by releasing mass-barcoded reporters into urine for analysis by mass spectrometry. To identify a protease signature of NASH, transcriptomic analysis of 355 human liver biopsies identified a 13-protease panel that discriminated clinically relevant NASH ≥F2 fibrosis from F0-F1 with high classification accuracy across two independent patient datasets. We screened 159 candidate substrates to identify a panel of 19 peptides that exhibited high activity for our 13-protease panel. In the choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) mouse model, binary classifiers trained on urine samples discriminated fibrotic NASH from simple steatosis and healthy controls across a range of nondisease conditions and indicated disease regression upon diet change [area under receiver operating characteristics (AUROCs) > 0.97]. Using a hepatoprotective triple combination treatment (FXR agonist, ACC and ASK1 inhibitors) in a rat model of NASH, urinary classification distinguished F0-F1 from ≥F2 animals and indicated therapeutic response as early as 1 week on treatment (AUROCs >0.91). Our results support GBTS-NASH to diagnose fibrotic NASH via an infusion of peptides, monitor changes in disease severity, and indicate early treatment response.


Assuntos
Hepatopatia Gordurosa não Alcoólica , Fibrose , Humanos , Peptídeos
10.
Cell Metab ; 29(1): 174-182.e5, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30244972

RESUMO

The incidence of hepatocellular carcinoma (HCC) is rapidly increasing due to the prevalence of obesity and non-alcoholic fatty liver disease, but the molecular triggers that initiate disease development are not fully understood. We demonstrate that mice with targeted loss-of-function point mutations within the AMP-activated protein kinase (AMPK) phosphorylation sites on acetyl-CoA carboxylase 1 (ACC1 Ser79Ala) and ACC2 (ACC2 Ser212Ala) have increased liver de novo lipogenesis (DNL) and liver lesions. The same mutation in ACC1 also increases DNL and proliferation in human liver cancer cells. Consistent with these findings, a novel, liver-specific ACC inhibitor (ND-654) that mimics the effects of ACC phosphorylation inhibits hepatic DNL and the development of HCC, improving survival of tumor-bearing rats when used alone and in combination with the multi-kinase inhibitor sorafenib. These studies highlight the importance of DNL and dysregulation of AMPK-mediated ACC phosphorylation in accelerating HCC and the potential of ACC inhibitors for treatment.


Assuntos
Acetil-CoA Carboxilase , Carcinoma Hepatocelular/metabolismo , Lipogênese , Neoplasias Hepáticas/metabolismo , Acetil-CoA Carboxilase/antagonistas & inibidores , Acetil-CoA Carboxilase/fisiologia , Animais , Células Hep G2 , Humanos , Masculino , Camundongos , Fosforilação , Ratos , Ratos Wistar
11.
PLoS One ; 7(8): e43805, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22928038

RESUMO

Regulated expression of miRNAs influences development in a wide variety of contexts. We report here that miR290-5p (100049710) and miR292-5p (100049711) are induced at the pre-B stage of murine B cell development and that they influence assembly of the Igκ light chain gene (243469) by contributing to the activation of germline Igκ transcription (κGT). We found that upon forced over-expression of miR290-5p/292-5p in Abelson Murine Leukemia Virus (AMuLV) transformed pro-B cells, two known activators of κGT, E2A (21423) and NF-κB (19697), show increased chromosomal binding to the kappa intronic enhancer. Conversely, knockdown of miR290-5p/292-5p in AMuLV pro-B cells blunts drug-induced activation of κGT. Furthermore, miR290-5p/292-5p knockdown also diminishes κGT activation, but not Rag1/2 (19373, 19374) expression, in an IL-7 dependent primary pro-B cell culture system. In addition, we identified a deficiency in κGT induction in miR290 cluster knockout mice. We hypothesize that increased expression of miR290-5p and miR292-5p contributes to the induction of κGT at the pre-B stage of B cell development through increased binding of NF-κB and E2A to kappa locus regulatory sequences.


Assuntos
Linfócitos B/citologia , Linfócitos B/metabolismo , Loci Gênicos/genética , Cadeias kappa de Imunoglobulina/genética , MicroRNAs/metabolismo , Vírus da Leucemia Murina de Abelson/fisiologia , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/virologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Benzamidas , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Transformação Celular Viral/efeitos dos fármacos , Transformação Celular Viral/genética , DNA/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Técnicas de Silenciamento de Genes , Mesilato de Imatinib , Íntrons/genética , Camundongos , MicroRNAs/genética , NF-kappa B/metabolismo , Piperazinas/farmacologia , Pirimidinas/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/genética
12.
PLoS One ; 7(5): e37108, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22693568

RESUMO

To what extent might the regulation of translation contribute to differentiation programs, or to the molecular pathogenesis of cancer? Pre-B cells transformed with the viral oncogene v-Abl are suspended in an immortalized, cycling state that mimics leukemias with a BCR-ABL1 translocation, such as Chronic Myelogenous Leukemia (CML) and Acute Lymphoblastic Leukemia (ALL). Inhibition of the oncogenic Abl kinase with imatinib reverses transformation, allowing progression to the next stage of B cell development. We employed a genome-wide polysome profiling assay called Gradient Encoding to investigate the extent and potential contribution of translational regulation to transformation and differentiation in v-Abl-transformed pre-B cells. Over half of the significantly translationally regulated genes did not change significantly at the level of mRNA abundance, revealing biology that might have been missed by measuring changes in transcript abundance alone. We found extensive, gene-specific changes in translation affecting genes with known roles in B cell signaling and differentiation, cancerous transformation, and cytoskeletal reorganization potentially affecting adhesion. These results highlight a major role for gene-specific translational regulation in remodeling the gene expression program in differentiation and malignant transformation.


Assuntos
Linfócitos B/metabolismo , Linfócitos B/patologia , Diferenciação Celular/genética , Transformação Celular Viral/genética , Proteínas Oncogênicas v-abl/metabolismo , Biossíntese de Proteínas , Transcriptoma , Linfócitos B/efeitos dos fármacos , Benzamidas , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Transformação Celular Viral/efeitos dos fármacos , Humanos , Mesilato de Imatinib , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Oncogênicas v-abl/antagonistas & inibidores , Proteínas Oncogênicas v-abl/genética , Piperazinas/farmacologia , Polirribossomos/efeitos dos fármacos , Polirribossomos/genética , Células Precursoras de Linfócitos B/efeitos dos fármacos , Células Precursoras de Linfócitos B/metabolismo , Células Precursoras de Linfócitos B/patologia , Biossíntese de Proteínas/efeitos dos fármacos , Pirimidinas/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Transcriptoma/efeitos dos fármacos , Transcriptoma/genética
13.
J Exp Med ; 204(13): 3247-56, 2007 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-18056289

RESUMO

Complete IgHC gene rearrangement occurs only in B cells in a stage-specific and ordered manner. We used gene targeting to reposition a distal V(H) gene segment to a region just 5' of the D(H) gene cluster and found its activation to be highly dependent on the chromosomal domain within which it resides. The targeted V(H) gene segment rearranged at a higher frequency than its endogenous counterpart, its rearrangement was no longer ordered, and its ability to be silenced by allelic exclusion was lost. Additionally, the targeted V(H) gene segment lost lineage specificity, as VDJ(H) rearrangement was observed in thymocytes. These data suggest that locus contraction, mimicked by proximal targeting, can override any regulation imposed by DNA sequences immediately surrounding V(H) gene segments.


Assuntos
Rearranjo Gênico , Genes de Imunoglobulinas/genética , Cadeias Pesadas de Imunoglobulinas/genética , VDJ Recombinases/genética , Alelos , Animais , Linfócitos B/metabolismo , Linhagem da Célula , Mapeamento Cromossômico , Cromossomos , Camundongos , Camundongos Transgênicos , Modelos Genéticos , Transdução de Sinais , Timo/metabolismo
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