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1.
Science ; 369(6502): 397-403, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32703873

RESUMO

Embryonic stem cells can propagate indefinitely in a pluripotent state, able to differentiate into all types of specialized cells when restored to the embryo. What sustains their pluripotency during propagation remains unclear. Here, we show that core pluripotency factors OCT4 and SOX2 suppress chaperone-mediated autophagy (CMA), a selective form of autophagy, until the initiation of differentiation. Low CMA activity promotes embryonic stem cell self-renewal, whereas its up-regulation enhances differentiation. CMA degrades isocitrate dehydrogenases IDH1 and IDH2 and reduces levels of intracellular α-ketoglutarate, an obligatory cofactor for various histone and DNA demethylases involved in pluripotency. These findings suggest that CMA mediates the effect of core pluripotency factors on metabolism, shaping the epigenetic landscape of stem cells and governing the balance between self-renewal and differentiation.


Assuntos
Diferenciação Celular , Autofagia Mediada por Chaperonas , Células-Tronco Embrionárias/fisiologia , Animais , Linhagem Celular , Epigênese Genética , Histonas/fisiologia , Ácidos Cetoglutáricos/metabolismo , Camundongos , Fator 3 de Transcrição de Octâmero/fisiologia , Fatores de Transcrição SOXB1/fisiologia
2.
Immunity ; 51(5): 840-855.e5, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31606264

RESUMO

TCF-1 is a key transcription factor in progenitor exhausted CD8 T cells (Tex). Moreover, this Tex cell subset mediates responses to PD-1 checkpoint pathway blockade. However, the role of the transcription factor TCF-1 in early fate decisions and initial generation of Tex cells is unclear. Single-cell RNA sequencing (scRNA-seq) and lineage tracing identified a TCF-1+Ly108+PD-1+ CD8 T cell population that seeds development of mature Tex cells early during chronic infection. TCF-1 mediated the bifurcation between divergent fates, repressing development of terminal KLRG1Hi effectors while fostering KLRG1Lo Tex precursor cells, and PD-1 stabilized this TCF-1+ Tex precursor cell pool. TCF-1 mediated a T-bet-to-Eomes transcription factor transition in Tex precursors by promoting Eomes expression and drove c-Myb expression that controlled Bcl-2 and survival. These data define a role for TCF-1 in early-fate-bifurcation-driving Tex precursor cells and also identify PD-1 as a protector of this early TCF-1 subset.


Assuntos
Linfócitos T CD8-Positivos/metabolismo , Redes Reguladoras de Genes , Fator 1 de Transcrição de Linfócitos T/metabolismo , Transcrição Genética , Animais , Linfócitos T CD8-Positivos/imunologia , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Doença Crônica , Perfilação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Camundongos , Receptor de Morte Celular Programada 1/metabolismo , Fator 1 de Transcrição de Linfócitos T/genética , Viroses/genética , Viroses/imunologia , Viroses/virologia
3.
J Immunol Methods ; 474: 112629, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31279523

RESUMO

Frataxin is the protein that is down-regulated in Friedreich ataxia (FRDA), an autosomal recessive genetic disease caused by an intronic GAA repeat expansion in intron-1 of the FXN gene. The GAA repeats result in epigenetic silencing of the FXN gene and reduced expression of the cytosolic full-length frataxin (1-210) protein. Full length frataxin translocates to the mitochondria, leading to formation of mature frataxin (81-210) formed by cleavage of the mitochondrial targeting sequence at K-80 of the full-length protein. There are currently no approved treatments for FRDA, although experimental approaches involving up-regulation or replacement of mature frataxin protein through numerous approaches are being tested. Many of the pre-clinical studies of these experimental approaches are conducted in mouse and monkey models as well as in human cell lines. Consequently, well-validated antibodies are required for use in western blot analysis to determine whether levels of various forms of frataxin have been increased. Here we examined the specificity of five commercially available anti-frataxin antibodies and determined whether they detect mature frataxin in mouse heart tissue. Four protein standards of monkey, human, and mouse frataxin as well as mouse heart tissue were examined using polyacrylamide gel electrophoresis (PAGE) in combination with western blot analysis. One antibody failed to detect any of the frataxin standards or endogenous frataxin in mouse heart tissue. Three of the antibodies detected a protein in mouse heart tissue that ran slightly faster on PAGE (at 23.4 kDa) to that predicted for full-length frataxin (23.9 kDa). One antibody detected all four frataxin standards as well as endogenous mouse mature frataxin in mouse tissue. Significantly, this antibody, which will be useful for monitoring mature frataxin levels in monkey, human, and mouse tissues, did not detect a protein in mouse heart tissue at 23.4 kDa. Therefore, antibodies detecting the immunoreactive protein at 23.4 kDa could be misleading when testing for the up-regulation of frataxin in animal models.


Assuntos
Anticorpos/imunologia , Western Blotting , Proteínas de Ligação ao Ferro/análise , Miocárdio/química , Animais , Especificidade de Anticorpos , Eletroforese em Gel de Poliacrilamida , Humanos , Proteínas de Ligação ao Ferro/imunologia , Macaca fascicularis , Camundongos Endogâmicos C57BL , Peso Molecular , Miocárdio/imunologia , Isoformas de Proteínas , Reprodutibilidade dos Testes , Especificidade da Espécie
4.
J Biol Chem ; 294(1): 130-141, 2019 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-30413534

RESUMO

RNA polymerase III (Pol III) is responsible for the production of small noncoding RNA species, including tRNAs and 5S rRNA. Pol III-dependent transcription is generally enhanced in transformed cells and tumors, but the underlying mechanisms remain not well-understood. It has been demonstrated that the BRF1 subunit of TFIIIB is essential for the accurate initiation of Pol III-dependent transcription. However, it is not known whether BRF1 undergoes ubiquitin modification and whether BRF1 ubiquitination regulates Pol III-dependent transcription. Here, we show that RNF12, a RING domain-containing ubiquitin E3 ligase, physically interacts with BRF1. Via direct interaction, RNF12 catalyzes Lys27- and Lys33-linked polyubiquitination of BRF1. Furthermore, RNF12 is able to negatively regulate Pol III-dependent transcription and cell proliferation via BRF1. These findings uncover a novel mechanism for the regulation of BRF1 and reveal RNF12 as an important regulator of Pol III-dependent transcription.


Assuntos
Proliferação de Células , RNA Polimerase III/metabolismo , Fatores Associados à Proteína de Ligação a TATA/metabolismo , Transcrição Genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação , Células HEK293 , Células HeLa , Humanos , RNA Polimerase III/genética , Fatores Associados à Proteína de Ligação a TATA/genética , Ubiquitina-Proteína Ligases/genética
5.
Immunity ; 49(1): 178-193.e7, 2018 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-29958801

RESUMO

The biological and functional heterogeneity between tumors-both across and within cancer types-poses a challenge for immunotherapy. To understand the factors underlying tumor immune heterogeneity and immunotherapy sensitivity, we established a library of congenic tumor cell clones from an autochthonous mouse model of pancreatic adenocarcinoma. These clones generated tumors that recapitulated T cell-inflamed and non-T-cell-inflamed tumor microenvironments upon implantation in immunocompetent mice, with distinct patterns of infiltration by immune cell subsets. Co-injecting tumor cell clones revealed the non-T-cell-inflamed phenotype is dominant and that both quantitative and qualitative features of intratumoral CD8+ T cells determine response to therapy. Transcriptomic and epigenetic analyses revealed tumor-cell-intrinsic production of the chemokine CXCL1 as a determinant of the non-T-cell-inflamed microenvironment, and ablation of CXCL1 promoted T cell infiltration and sensitivity to a combination immunotherapy regimen. Thus, tumor cell-intrinsic factors shape the tumor immune microenvironment and influence the outcome of immunotherapy.


Assuntos
Adenocarcinoma/terapia , Fatores Imunológicos/imunologia , Imunoterapia , Subpopulações de Linfócitos/imunologia , Linfócitos do Interstício Tumoral/imunologia , Neoplasias Pancreáticas/terapia , Microambiente Tumoral/imunologia , Adenocarcinoma/imunologia , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Animais , Linfócitos T CD8-Positivos/imunologia , Epigenômica , Feminino , Perfilação da Expressão Gênica , Humanos , Fatores Imunológicos/genética , Masculino , Camundongos , Pessoa de Meia-Idade , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/patologia , Cultura Primária de Células
6.
Cell Rep ; 20(11): 2584-2597, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-28903040

RESUMO

MicroRNAs play an important role in T cell responses. However, how microRNAs regulate CD8 T cell memory remains poorly defined. Here, we found that miR-150 negatively regulates CD8 T cell memory in vivo. Genetic deletion of miR-150 disrupted the balance between memory precursor and terminal effector CD8 T cells following acute viral infection. Moreover, miR-150-deficient memory CD8 T cells were more protective upon rechallenge. A key circuit whereby miR-150 repressed memory CD8 T cell development through the transcription factor c-Myb was identified. Without miR-150, c-Myb was upregulated and anti-apoptotic targets of c-Myb, such as Bcl-2 and Bcl-xL, were also increased, suggesting a miR-150-c-Myb survival circuit during memory CD8 T cell development. Indeed, overexpression of non-repressible c-Myb rescued the memory CD8 T cell defects caused by overexpression of miR-150. Overall, these results identify a key role for miR-150 in memory CD8 T cells through a c-Myb-controlled enhanced survival circuit.


Assuntos
Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Memória Imunológica , MicroRNAs/metabolismo , Proteínas Proto-Oncogênicas c-myb/metabolismo , Animais , Apoptose/genética , Feminino , Imunidade , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética
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