RESUMO
Gene duplication results in two identical paralogs that diverge through mutation, leading to loss or gain of interactions with other biomolecules. Here, we comprehensively characterize such network rewiring for C. elegans transcription factors (TFs) within and across four newly delineated molecular networks. Remarkably, we find that even highly similar TFs often have different interaction degrees and partners. In addition, we find that most TF families have a member that is highly connected in multiple networks. Further, different TF families have opposing correlations between network connectivity and phylogenetic age, suggesting that they are subject to different evolutionary pressures. Finally, TFs that have similar partners in one network generally do not in another, indicating a lack of pressure to retain cross-network similarity. Our multiparameter analyses provide unique insights into the evolutionary dynamics that shaped TF networks.
Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Caenorhabditis elegans/genética , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Fatores de Transcrição/fisiologia , Animais , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Evolução Molecular , Filogenia , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismoRESUMO
How tumour suppressor p53 bifurcates cell cycle arrest and apoptosis and executes these distinct pathways is not clearly understood. We show that BAX and PUMA promoters harbour an identical MAR element and are transcriptional targets of SMAR1. On mild DNA damage, SMAR1 selectively represses BAX and PUMA through binding to the MAR independently of inducing p53 deacetylation through HDAC1. This generates an anti-apoptotic response leading to cell cycle arrest. Importantly, knockdown of SMAR1 induces apoptosis, which is abrogated in the absence of p53. Conversely, apoptotic DNA damage results in increased size and number of promyelocytic leukaemia (PML) nuclear bodies with consequent sequestration of SMAR1. This facilitates p53 acetylation and restricts SMAR1 binding to BAX and PUMA MAR leading to apoptosis. Thus, our study establishes MAR as a damage responsive cis element and SMAR1-PML crosstalk as a switch that modulates the decision between cell cycle arrest and apoptosis in response to DNA damage.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/fisiologia , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regiões de Interação com a Matriz , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Proteína X Associada a bcl-2/metabolismo , Acetilação , Animais , Apoptose/genética , Proteínas Reguladoras de Apoptose/genética , Sequência de Bases , Ciclo Celular , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Linhagem Celular , DNA/genética , DNA/metabolismo , Dano ao DNA , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Histona Desacetilase 1/metabolismo , Humanos , Camundongos , Modelos Biológicos , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/genética , Regiões Promotoras Genéticas , Proteína da Leucemia Promielocítica , Proteínas Proto-Oncogênicas/genética , RNA Interferente Pequeno/genética , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica , Proteínas Supressoras de Tumor/antagonistas & inibidores , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Proteína X Associada a bcl-2/genéticaRESUMO
A major challenge in systems biology is to understand the gene regulatory networks that drive development, physiology and pathology. Interactions between transcription factors and regulatory genomic regions provide the first level of gene control. Gateway-compatible yeast one-hybrid (Y1H) assays present a convenient method to identify and characterize the repertoire of transcription factors that can bind a DNA sequence of interest. To delineate genome-scale regulatory networks, however, large sets of DNA fragments need to be processed at high throughput and high coverage. Here we present enhanced Y1H (eY1H) assays that use a robotic mating platform with a set of improved Y1H reagents and automated readout quantification. We demonstrate that eY1H assays provide excellent coverage and identify interacting transcription factors for multiple DNA fragments in a short time. eY1H assays will be an important tool for mapping gene regulatory networks in Caenorhabditis elegans and other model organisms as well as in humans.
Assuntos
Redes Reguladoras de Genes , Ensaios de Triagem em Larga Escala , Técnicas do Sistema de Duplo-Híbrido , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , DNA/genética , Regulação da Expressão Gênica , Humanos , Reprodutibilidade dos Testes , Biologia de Sistemas , Fatores de Transcrição/metabolismoRESUMO
BACKGROUND: GAD65 (Glutamic acid decarboxylase 65 KDa isoform) is one of the most important auto-antigens involved in Type 1 diabetes induction. Although it serves as one of the first injury markers of ß-islets, the mechanisms governing GAD65 expression remain poorly understood. Since the regulation of GAD65 is crucial for the proper functioning of insulin secreting cells, we investigated the stress induced regulation of GAD65 transcription. RESULTS: The present study shows that SMAR1 regulates GAD65 expression at the transcription level. Using a novel protein-DNA pull-down assay, we show that SMAR1 binding is very specific to GAD65 promoter but not to the other isoform, GAD67. We show that Streptozotocin (STZ) mediated DNA damage leads to upregulation of SMAR1 and p53 expression, resulting in elevated levels of GAD65, in both cell lines as well as mouse ß-islets. SMAR1 and p53 act synergistically to up-regulate GAD65 expression upon STZ treatment. CONCLUSION: We propose a novel mechanism of GAD65 regulation by synergistic activities of SMAR1 and p53.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Dano ao DNA , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Glutamato Descarboxilase/metabolismo , Proteínas Nucleares/metabolismo , Estreptozocina/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Animais , Sequência de Bases , Linhagem Celular , Imunoprecipitação da Cromatina , Primers do DNA/genética , Ensaio de Desvio de Mobilidade Eletroforética , Citometria de Fluxo , Regulação Enzimológica da Expressão Gênica/genética , Glutamato Descarboxilase/genética , Immunoblotting , Luciferases , Camundongos , Dados de Sequência Molecular , Regiões Promotoras Genéticas/genética , Isoformas de Proteínas/metabolismo , Alinhamento de SequênciaRESUMO
An amendment to this paper has been published and can be accessed via the original article.
RESUMO
Tetrapeptides derived from glycine and beta-alanine were hooked at the C-3beta position of the modified cholic acid to realize novel linear tetrapeptide-linked cholic acid derivatives. All the synthesized compounds were tested against a wide variety of microorganisms (gram-negative bacteria, gram-positive bacteria and fungi) and their cytotoxicity was evaluated against human embryonic kidney (HEK293) and human mammary adenocarcinoma (MCF-7) cell lines. While relatively inactive by themselves, these compounds interact synergistically with antibiotics such as fluconazole and erythromycin to inhibit growth of fungi and bacteria, respectively, at 1-24 microg/mL. The synergistic effect shown by our novel compounds is due to their inherent amphiphilicity. The fractional inhibitory concentrations reported are comparable to those reported for Polymyxin B derivatives.
Assuntos
Antibacterianos/síntese química , Ácido Cólico/química , Peptídeos/química , Antibacterianos/farmacologia , Linhagem Celular , Linhagem Celular Tumoral , Química Farmacêutica/métodos , Desenho de Fármacos , Eritromicina/farmacologia , Fluconazol/farmacologia , Glicina/química , Humanos , Modelos Químicos , Conformação Molecular , Polimixina B/análogos & derivados , Polimixina B/farmacologia , beta-Alanina/químicaRESUMO
We report herein the synthesis and biological evaluation of bile acid dimers linked through 1,2,3-triazole and bis-beta-lactam. The dimers were synthesized using 1,3-dipolar cycloaddition reaction of diazido bis-beta-lactams , and terminal alkynes derived from cholic acid/deoxycholic acid in the presence of Cu(i) catalyst (click chemistry). These novel molecules were evaluated in vitro for their antifungal and antibacterial activity. Most of the compounds exhibited significant antifungal as well as antibacterial activity against all the tested fungal and bacterial strains. Moreover, their in vitro cytotoxicities towards HEK-293 and MCF-7 cells were also established.