RESUMO
Proliferation is tightly regulated during T cell development, and is limited to immature CD4-CD8- thymocytes. The major proliferative event is initiated at the 'ß-selection' stage following successful rearrangement of Tcrß, and is triggered by and dependent on concurrent signaling by Notch and the pre-T cell receptor (TCR); however, it is unclear how these signals cooperate to promote cell proliferation. Here, we found that ß-selection-associated proliferation required the combined activity of two Skp-cullin-F-box (SCF) ubiquitin ligase complexes that included as substrate recognition subunits the F-box proteins Fbxl1 or Fbxl12. Both SCF complexes targeted the cyclin-dependent kinase inhibitor Cdkn1b for polyubiquitination and proteasomal degradation. We found that Notch signals induced the transcription of Fbxl1, whereas pre-TCR signals induced the transcription of Fbxl12. Thus, concurrent Notch and pre-TCR signaling induced the expression of two genes, Fbxl1 and Fbxl12, whose products functioned identically but additively to promote degradation of Cdkn1b, cell cycle progression, and proliferation of ß-selected thymocytes.
Assuntos
Proteínas F-Box/metabolismo , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Receptores Notch/metabolismo , Proteínas Ligases SKP Culina F-Box/metabolismo , Linfócitos T/fisiologia , Timócitos/fisiologia , Animais , Diferenciação Celular , Proliferação de Células , Seleção Clonal Mediada por Antígeno , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Proteínas F-Box/genética , Regulação da Expressão Gênica , Genes Codificadores da Cadeia beta de Receptores de Linfócitos T , Camundongos , Camundongos Endogâmicos C57BL , Receptor Cross-Talk , Transdução de SinaisRESUMO
Flexible conductive hydrogels have revolutionized the lives and are widely applied in health monitoring and wearable electronics as a new generation of sensing materials. However, the inherent low mechanical strength, sensitivity, and lack of rapid self-healing capacity results in their short life, poor detection accuracy, and environmental pollution. Inspired by the molecular structure of bone and its chemical characteristics, a novel fully physically cross-linked conductive hydrogel is fabricated by the introduction of nanohydroxyapatite (HAp) as the dynamic junction points. In detail, the dynamically cross-linked network, including multiple physical interactions, provides it with rapid self-healing ability and excellent mechanical properties (elongation at break (>1200%), tensile strength (174kPa), and resilience (92.61%)). Besides, the ions (Cl-, Li+, Ca2+) that move freely within the system impart outstanding electrical conductivity (2.46 ± 0.15 S m-1), high sensitivity (gauge factor, GF>8), good antifreeze (-40.2 °C), and humidity properties. The assembled sensor can be employed to sensitively detect various large human motions and subtle changes in behavior (facial expressions, speech recognition). Meanwhile, the hydrogel sensor can also degrade in phosphate-buffered saline solution without causing any environmental pollution. Therefore, the designed hydrogels may become a promising candidate material in the future potential applications for smart wearable sensors and electronic skin.
RESUMO
The nuclear adaptor Ldb1 functions as a core component of multiprotein transcription complexes that regulate differentiation in diverse cell types. In the hematopoietic lineage, Ldb1 forms a complex with the non-DNA-binding adaptor Lmo2 and the transcription factors E2A, Scl and GATA-1 (or GATA-2). Here we demonstrate a critical and continuous requirement for Ldb1 in the maintenance of both fetal and adult mouse hematopoietic stem cells (HSCs). Deletion of Ldb1 in hematopoietic progenitors resulted in the downregulation of many transcripts required for HSC maintenance. Genome-wide profiling by chromatin immunoprecipitation followed by sequencing (ChIP-Seq) identified Ldb1 complex-binding sites at highly conserved regions in the promoters of genes involved in HSC maintenance. Our results identify a central role for Ldb1 in regulating the transcriptional program responsible for the maintenance of HSCs.
Assuntos
Células-Tronco Adultas/metabolismo , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Embrionárias/metabolismo , Desenvolvimento Fetal , Células-Tronco Hematopoéticas/metabolismo , Transferência Adotiva , Células-Tronco Adultas/citologia , Células-Tronco Adultas/imunologia , Células-Tronco Adultas/transplante , Animais , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Sobrevivência Celular/genética , Sobrevivência Celular/imunologia , Células Cultivadas , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/imunologia , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/imunologia , Células-Tronco Embrionárias/transplante , Feminino , Desenvolvimento Fetal/genética , Desenvolvimento Fetal/imunologia , Regulação da Expressão Gênica no Desenvolvimento/imunologia , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/imunologia , Sequenciamento de Nucleotídeos em Larga Escala , Proteínas com Domínio LIM , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Gravidez , Ligação Proteica , Elementos Reguladores de Transcrição/genética , Elementos Reguladores de Transcrição/imunologia , Ativação Transcricional/genética , Ativação Transcricional/imunologiaRESUMO
We report herein a "bottom-up" approach for the one-step assembly of a MacMillan catalyst-based phenolic-type polymer (Mac-CP). The resulting self-supported polymeric organocatalyst possesses homogeneously distributed and highly concentrated catalytic sites. Furthermore, Mac-CP is soluble in CH3CN but insoluble in hexane. This unique property can be used to employ the polymer as an efficient catalyst in homogeneous organocatalysis and heterogeneous recycling. As a result, Mac-CP possesses comparable catalytic activity and enantioselectivity to its homogeneous counterpart in the asymmetric Diels-Alder reaction (95% yield, 93% enantiomeric excess (ee) for endo and 92% ee for exo).
RESUMO
Prolonged or enhanced expression of the proto-oncogene Lmo2 is associated with a severe form of T-cell acute lymphoblastic leukemia (T-ALL), designated early T-cell precursor ALL, which is characterized by the aberrant self-renewal and subsequent oncogenic transformation of immature thymocytes. It has been suggested that Lmo2 exerts these effects by functioning as component of a multi-subunit transcription complex that includes the ubiquitous adapter Ldb1 along with b-HLH and/or GATA family transcription factors; however, direct experimental evidence for this mechanism is lacking. In this study, we investigated the importance of Ldb1 for Lmo2-induced T-ALL by conditional deletion of Ldb1 in thymocytes in an Lmo2 transgenic mouse model of T-ALL. Our results identify a critical requirement for Ldb1 in Lmo2-induced thymocyte self-renewal and thymocyte radiation resistance and for the transition of preleukemic thymocytes to overt T-ALL. Moreover, Ldb1 was also required for acquisition of the aberrant preleukemic ETP gene expression signature in immature Lmo2 transgenic thymocytes. Co-binding of Ldb1 and Lmo2 was detected at the promoters of key upregulated T-ALL driver genes (Hhex, Lyl1, and Nfe2) in preleukemic Lmo2 transgenic thymocytes, and binding of both Ldb1 and Lmo2 at these sites was reduced following Cre-mediated deletion of Ldb1. Together, these results identify a key role for Ldb1, a nonproto-oncogene, in T-ALL and support a model in which Lmo2-induced T-ALL results from failure to downregulate Ldb1/Lmo2-nucleated transcription complexes which normally function to enforce self-renewal in bone marrow hematopoietic progenitors.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Autorrenovação Celular , Proteínas de Ligação a DNA/fisiologia , Proteínas com Domínio LIM/fisiologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Timócitos/citologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Transferência Adotiva , Animais , Antígenos CD/biossíntese , Transformação Celular Neoplásica , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Deleção de Genes , Técnicas de Introdução de Genes , Proteínas com Domínio LIM/deficiência , Proteínas com Domínio LIM/genética , Linfopoese , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proto-Oncogene Mas , RNA-Seq , Quimera por Radiação , Tolerância a Radiação , Timócitos/metabolismo , Timócitos/efeitos da radiação , Timócitos/transplanteRESUMO
During positive selection, thymocytes transition through a stage during which T cell antigen receptor (TCR) signaling controls CD4-versus-CD8 lineage 'choice' and subsequent maturation. Here we describe a previously unknown T cell-specific protein, Themis, that serves a distinct function during this stage. In Themis(-/-) mice, thymocyte selection was impaired and the number of transitional CD4(+)CD8(int) thymocytes as well as CD4(+) or CD8(+) single-positive thymocytes was lower. Notably, although we detected no overt TCR-proximal signaling deficiencies, Themis(-/-) CD4(+)CD8(int) thymocytes showed developmental defects consistent with attenuated signaling that were reversible by TCR stimulation. Our results identify Themis as a critical component of the T cell developmental program and suggest that Themis functions to sustain and/or integrate signals required for proper lineage commitment and maturation.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Linhagem da Célula/fisiologia , Proteínas/fisiologia , Receptores de Antígenos de Linfócitos T/fisiologia , Animais , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD8-Positivos/citologia , Diferenciação Celular , Sobrevivência Celular , Células Cultivadas , Células-Tronco Embrionárias/metabolismo , Feminino , Citometria de Fluxo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Camundongos , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas/genética , Proteínas/imunologia , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/imunologia , Transdução de SinaisRESUMO
OBJECTIVE: Unilateral complete cleft lip and palate (UCCLP) is associated with apparent nasal deformities before the cheilorrhaphy. The aim of this study was to determine whether preoperative correction techniques are effective in the treatment of nasal deformities in infant with unilateral UCCLP used by the systematic review and meta-analysis. METHODS: We searched Medline, Cochrane Library, EMBASE, PubMed, and Chinese BioMedical Literature Database (CBM) until January 31, 2019, to identify studies that compared the effectiveness of preoperative correction techniques in the treatment of nasal deformities in infant with UCCLP. Two authors individually extracted the data and performed the quality assessments. The height of nasal columella, the width of the affected side nasal ala and the inclination of the nasal columella were evaluated. RESULTS: Seven articles were incorporated into the systematic review, and 5 (274 participants) in the meta-analysis according to the inclusion criteria. The preoperative correction could increase the height of nasal columella in children with UCCLP [SMD: 2.64âmm; 95% confidence intervals (CI); (1.35âmm, 3.94âmm); Pâ<â0.0001]. Moreover, the preoperative correction resulted in reduced width of the affected side nasal ala [SMD: -5.14âmm; 95% CI; (-8.96âmm, -1.31 mm); Pâ=â0.008]; However, the evidence was insufficient to determine a significant effect on the inclination of the nasal columella [SMD: -3.48 degrees; 95% CI; (-7.56 degrees, 0.59 degrees); Pâ=â0.09]. CONCLUSIONS: Preoperative correction for children with UCCLP can increase the height of nasal columella, reduce the width of the affected side nasal ala, improve the nasal symmetry, and reduce nasal deformity, however, no significant effect could be observed for the inclination of the nasal columella.
Assuntos
Fenda Labial , Fissura Palatina , Rinoplastia , Criança , Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Humanos , Lactente , Septo Nasal/cirurgia , Nariz/cirurgia , Cuidados Pré-Operatórios , Resultado do TratamentoRESUMO
A practical visible-light-induced aerobic oxidative dehydrogenative coupling reaction of glycine derivatives with olefins has been developed to efficiently synthesize quinoline-2-carboxylates. This metal-free process proceeds smoothly under mild conditions and exhibits good tolerance of functional groups. Given the low cost of the catalyst and feedstock materials, the mild reaction conditions and the absence of hazardous byproducts, this protocol should find broad applications in the synthesis of quinoline-2-carboxylate derivatives.
RESUMO
The Lim domain-binding proteins are key co-factor proteins that assemble with LIM domains of the LMO/LIM-HD family to form functional complexes that regulate cell proliferation and differentiation. Using conditional mutagenesis and comparative phenotypic analysis, we analyze the function of Ldb1 and Ldb2 in mouse retinal development, and demonstrate overlapping and specific functions of both proteins. Ldb1 interacts with Lhx2 in the embryonic retina and both Ldb1 and Ldb2 play a key role in maintaining the pool of retinal progenitor cells. This is accomplished by controlling the expression of the Vsx2 and Rax, and components of the Notch and Hedgehog signaling pathways. Furthermore, the Ldb1/Ldb2-mediated complex is essential for generation of early-born photoreceptors through the regulation of Rax and Crx. Finally, we demonstrate functional redundancy between Ldb1 and Ldb2. Ldb1 can fully compensate the loss of Ldb2 during all phases of retinal development, whereas Ldb2 alone is sufficient to sustain activity of Lhx2 in both early- and late-stage RPCs and in Müller glia. By contrast, loss of Ldb1 disrupts activity of the LIM domain factors in neuronal precursors. An intricate regulatory network exists that is mediated by Ldb1 and Ldb2, and promotes RPC proliferation and multipotency; it also controls specification of mammalian retina cells.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Proteínas com Domínio LIM/fisiologia , Organogênese/genética , Retina/embriologia , Fatores de Transcrição/fisiologia , Animais , Diferenciação Celular/genética , Proliferação de Células/genética , Embrião de Mamíferos , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes/fisiologia , Mamíferos/embriologia , Mamíferos/genética , Camundongos , Camundongos Transgênicos , Retina/citologia , Retina/metabolismo , Células-Tronco/fisiologiaRESUMO
Primary T-cell acute lymphoblastic leukemia (T-ALL) cells require stromal-derived signals to survive. Although many studies have identified cell-intrinsic alterations in signaling pathways that promote T-ALL growth, the identity of endogenous stromal cells and their associated signals in the tumor microenvironment that support T-ALL remains unknown. By examining the thymic tumor microenvironments in multiple murine T-ALL models and primary patient samples, we discovered the emergence of prominent epithelial-free regions, enriched for proliferating tumor cells and dendritic cells (DCs). Systematic evaluation of the functional capacity of tumor-associated stromal cells revealed that myeloid cells, primarily DCs, are necessary and sufficient to support T-ALL survival ex vivo. DCs support T-ALL growth both in primary thymic tumors and at secondary tumor sites. To identify a molecular mechanism by which DCs support T-ALL growth, we first performed gene expression profiling, which revealed up-regulation of platelet-derived growth factor receptor beta (Pdgfrb) and insulin-like growth factor I receptor (Igf1r) on T-ALL cells, with concomitant expression of their ligands by tumor-associated DCs. Both Pdgfrb and Igf1r were activated in ex vivo T-ALL cells, and coculture with tumor-associated, but not normal thymic DCs, sustained IGF1R activation. Furthermore, IGF1R signaling was necessary for DC-mediated T-ALL survival. Collectively, these studies provide the first evidence that endogenous tumor-associated DCs supply signals driving T-ALL growth, and implicate tumor-associated DCs and their mitogenic signals as auspicious therapeutic targets.
Assuntos
Células Dendríticas/imunologia , Proteínas de Neoplasias/imunologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/imunologia , Receptores de Somatomedina/imunologia , Transdução de Sinais/imunologia , Microambiente Tumoral/imunologia , Animais , Linhagem Celular Tumoral , Sobrevivência Celular , Células Dendríticas/patologia , Feminino , Humanos , Masculino , Camundongos , Proteínas de Neoplasias/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Receptor IGF Tipo 1 , Receptor beta de Fator de Crescimento Derivado de Plaquetas/genética , Receptor beta de Fator de Crescimento Derivado de Plaquetas/imunologia , Receptores de Somatomedina/genética , Transdução de Sinais/genética , Microambiente Tumoral/genéticaRESUMO
Elucidation of the genetic pathways that control red blood cell development has been a central goal of erythropoiesis research over the past decade. Notably, data from several recent studies have provided new insights into the regulation of erythroid gene transcription. Transcription profiling demonstrates that erythropoiesis is mainly controlled by a small group of lineage-restricted transcription factors [Gata binding protein 1 (Gata1), T cell acute lymphocytic leukemia 1 protein (Tal1), and Erythroid Kruppel-like factor (EKLF; henceforth referred to as Klf1)]. Binding-site mapping using ChIP-Seq indicates that most DNA-bound Gata1 and Tal1 proteins are contained within higher order complexes (Ldb1 complexes) that include the nuclear adapters Ldb1 and Lmo2. Ldb1 complexes regulate Klf1, and Ldb1 complex-binding sites frequently colocalize with Klf1 at erythroid genes and cis-regulatory elements, indicating strong functional synergy between Gata1, Tal1, and Klf1. Together with new data demonstrating that Ldb1 can mediate long-range promoter-enhancer interactions, these findings provide a foundation for the first comprehensive models of the global regulation of erythroid gene transcription.
Assuntos
Eritropoese/genética , Fatores de Transcrição/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Sítios de Ligação/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Repressão Epigenética , Fator de Transcrição GATA1/genética , Fator de Transcrição GATA1/metabolismo , Regulação da Expressão Gênica , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Proteínas com Domínio LIM/genética , Proteínas com Domínio LIM/metabolismo , Camundongos , Modelos Animais , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Análise de Sequência de DNA , Proteína 1 de Leucemia Linfocítica Aguda de Células T , Fatores de Transcrição/genéticaRESUMO
A visible-light induced photocatalytic aerobic oxidative dehydrogenative coupling/aromatization tandem reaction of glycine esters with unactivated alkenes has been accomplished. This visible light-driven protocol has been successfully applied to a broad scope of glycine esters and simple alkenes, giving rise to diverse substituted quinoline derivatives in 18-84% yield under mild (at room temperature under air atmosphere) and operationally simple reaction conditions.
RESUMO
Erythropoiesis is dependent on the lineage-specific transcription factors Gata1, Tal1, and Klf1. Several erythroid genes have been shown to require all 3 factors for their expression, suggesting that they function synergistically; however, there is little direct evidence for widespread cooperation. Gata1 and Tal1 can assemble within higher-order protein complexes (Ldb1 complexes) that include the adapter molecules Lmo2 and Ldb1. Ldb1 proteins are capable of coassociation, and long-range Ldb1-mediated oligomerization of enhancer- and promoter-bound Ldb1 complexes has been shown to be required for ß-globin gene expression. In this study, we generated a genomewide map of Ldb1 complex binding sites that revealed widespread binding at erythroid genes and at known erythroid enhancer elements. Ldb1 complex binding sites frequently colocalized with Klf1 binding sites and with consensus binding motifs for other erythroid transcription factors. Transcriptomic analysis demonstrated a strong correlation between Ldb1 complex binding and Ldb1 dependency for gene expression and identified a large cohort of genes coregulated by Ldb1 complexes and Klf1. Together, these results provide a foundation for defining the mechanism and scope of Ldb1 complex activity during erythropoiesis.