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1.
Science ; 351(6274): aad5510, 2016 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-26797145

RESUMO

Differentiated macrophages can self-renew in tissues and expand long term in culture, but the gene regulatory mechanisms that accomplish self-renewal in the differentiated state have remained unknown. Here we show that in mice, the transcription factors MafB and c-Maf repress a macrophage-specific enhancer repertoire associated with a gene network that controls self-renewal. Single-cell analysis revealed that, in vivo, proliferating resident macrophages can access this network by transient down-regulation of Maf transcription factors. The network also controls embryonic stem cell self-renewal but is associated with distinct embryonic stem cell-specific enhancers. This indicates that distinct lineage-specific enhancer platforms regulate a shared network of genes that control self-renewal potential in both stem and mature cells.


Assuntos
Diferenciação Celular/genética , Linhagem da Célula/genética , Células-Tronco Embrionárias/citologia , Elementos Facilitadores Genéticos/fisiologia , Regulação da Expressão Gênica , Macrófagos/citologia , Animais , Proliferação de Células , Células Cultivadas , Regulação para Baixo , Redes Reguladoras de Genes , Fator de Transcrição MafB/metabolismo , Camundongos , Proteínas Proto-Oncogênicas c-maf/metabolismo , Análise de Célula Única , Ativação Transcricional
2.
EMBO J ; 24(12): 2096-103, 2005 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-15920484

RESUMO

Bax promotes cell death by permeabilizing mitochondrial outer membranes by an unresolved mechanism. However, in cells lacking the gene c-myc, membrane permeabilization by Bax is blocked by changes in the mitochondria that prevent Bax oligomerization. Drug-treated c-myc null cells and cells expressing Myc were used to map the topology of Bax in membranes prior to and after mitochondrial permeabilization. Chemical labeling of single cysteine mutants of Bax using a membrane bilayer impermeant cysteine-specific modifying agent revealed that Bax inserted both the 'pore domain' (helices alpha5-alpha6), and the tail-anchor (helix alpha9) into membranes prior to oligomerization and membrane permeabilization. Additional topology changes for Bax were not required in Myc-expressing cells to promote oligomerization and cytochrome c release. Our results suggest that unlike most pore-forming proteins, Bax membrane permeabilization results from oligomerization of transmembrane monomers rather than concerted insertion of the pore domains of a preformed oligomer.


Assuntos
Apoptose/fisiologia , Membranas Intracelulares/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/química , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3 , Proteínas de Transporte/metabolismo , Cisteína/genética , Cisteína/metabolismo , Citocromos c/metabolismo , Humanos , Immunoblotting , Mitocôndrias/metabolismo , Mutação , Permeabilidade , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteína X Associada a bcl-2
3.
EMBO J ; 22(20): 5459-70, 2003 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-14532118

RESUMO

Bcl-x(L) and Bcl-2 inhibit both apoptosis and proliferation. In investigating the relationship between these two functions of Bcl-x(L) and Bcl-2, an analysis of 24 Bcl-x(L) and Bcl-2 mutant alleles, including substitutions at residue Y28 previously reported to selectively abolish the cell cycle activity, showed that cell cycle delay and anti-apoptosis co-segregated in all cases. In determining whether Bcl-2 and Bcl-x(L) act in G(0) or G(1), forward scatter and pyronin Y fluorescence measurements indicated that Bcl-2 and Bcl-x(L) cells arrested more effectively in G(0) than controls, and were delayed in G(0)-G(1) transition. The cell cycle effects of Bcl-2 and Bcl-x(L) were reversed by Bad, a molecule that counters the survival function of Bcl-2 and Bcl-x(L). When control and Bcl-x(L) cells of equivalent size and pyronin Y fluorescence were compared, the kinetics of cell cycle entry were similar, demonstrating that the ability of Bcl-x(L) and Bcl-2 cells to enhance G(0) arrest contributes significantly to cell cycle delay. Our data suggest that cell cycle effects and increased survival both result from intrinsic functions of Bcl-2 and Bcl-x(L).


Assuntos
Apoptose/fisiologia , Ciclo Celular/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Alelos , Animais , Proteínas de Transporte/metabolismo , Divisão Celular , Linhagem Celular , Inibição de Contato , Fase G1 , Cinética , Mutagênese , Proteínas Proto-Oncogênicas c-bcl-2/genética , Ratos , Proteínas Recombinantes/metabolismo , Fase de Repouso do Ciclo Celular , Proteína de Morte Celular Associada a bcl , Proteína bcl-X
4.
Adv Cancer Res ; 84: 81-154, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11885563

RESUMO

The activated product of the myc oncogene deregulates both cell growth and death check points and, in a permissive environment, rapidly accelerates the affected clone through the carcinogenic process. Advances in understanding the molecular mechanism of Myc action are highlighted in this review. With the revolutionary developments in molecular diagnostic technology, we have witnessed an unprecedented advance in detecting activated myc in its deregulated, oncogenic form in primary human cancers. These improvements provide new opportunities to appreciate the tumor subtypes harboring deregulated Myc expression, to identify the essential cooperating lesions, and to realize the therapeutic potential of targeting Myc. Knowledge of both the breadth and depth of the numerous biological activities controlled by Myc has also been an area of progress. Myc is a multifunctional protein that can regulate cell cycle, cell growth, differentiation, apoptosis, transformation, genomic instability, and angiogenesis. New insights into Myc's role in regulating these diverse activities are discussed. In addition, breakthroughs in understanding Myc as a regulator of gene transcription have revealed multiple mechanisms of Myc activation and repression of target genes. Moreover, the number of reported Myc regulated genes has expanded in the past few years, inspiring a need to focus on classifying and segregating bona fide targets. Finally, the identity of Myc-binding proteins has been difficult, yet has exploded in the past few years with a plethora of novel interactors. Their characterization and potential impact on Myc function are discussed. The rapidity and magnitude of recent progress in the Myc field strongly suggests that this marvelously complex molecule will soon be unmasked.


Assuntos
Neoplasias/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-myc/fisiologia , Animais , Apoptose , Ciclo Celular , Cromatina/metabolismo , Humanos , Modelos Biológicos , Neoplasias/genética , Neovascularização Patológica , Isoformas de Proteínas , Transcrição Gênica
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