RESUMEN
CSL proteins [named after the homologs CBF1 (RBP-Jκ in mice), Suppressor of Hairless and LAG-1] are conserved transcription factors found in animals and fungi. In the fission yeast Schizosaccharomyces pombe, they regulate various cellular processes, including cell cycle progression, lipid metabolism and cell adhesion. CSL proteins bind to DNA through their N-terminal Rel-like domain and central ß-trefoil domain. Here, we investigated the importance of DNA binding for CSL protein functions in fission yeast. We created CSL protein mutants with disrupted DNA binding and found that the vast majority of CSL protein functions depend on intact DNA binding. Specifically, DNA binding is crucial for the regulation of cell adhesion, lipid metabolism, cell cycle progression, long non-coding RNA expression and genome integrity maintenance. Interestingly, perturbed lipid metabolism leads to chromatin structure changes, potentially linking lipid metabolism to the diverse phenotypes associated with CSL protein functions. Our study highlights the critical role of DNA binding for CSL protein functions in fission yeast.
Asunto(s)
Proteínas de Ciclo Celular , Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces , Factores de Transcripción , Schizosaccharomyces/metabolismo , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Unión Proteica , Metabolismo de los Lípidos/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Ciclo Celular/genética , Regulación Fúngica de la Expresión Génica , ADN de Hongos/metabolismo , ADN de Hongos/genéticaRESUMEN
N6-methyl adenosine (m6A) is a widespread internal mRNA modification impacting the expression of numerous genes. Here, we characterize auxin-related defects among the pleiotropic phenotypes of hypomorphic Arabidopsis thaliana mutants with impaired m6A status and reveal that they show strong resistance to exogenously applied auxin. By combining major published m6A datasets, we propose that among high-confidence target transcripts emerge those encoding the main components required for auxin signaling, including the TIR1/AFB auxin receptors and ARF transcriptional regulators. We also observe subtle changes in endogenous levels of indole-3-acetic acid metabolites in these hypomorphic lines, which correlate with the methylation status of indole-3-acetic acid amidohydrolase transcripts. In addition, we reveal that reduced m6A levels lead to defects in endodermal patterning in the primary root arising from impaired timing of periclinal cell divisions. These defects can be reverted by inhibition of auxin signaling. Together, our data underline that m6A likely affects auxin-dependent processes at multiple levels.
RESUMEN
Epithelial-mesenchymal transition (EMT) is a cellular mechanism used by cancer cells to acquire migratory and stemness properties. In this study, we show, through in vitro, in vivo, and 3D culture experiments, that the mitochondrial protein LACTB manifests tumor suppressor properties in ovarian cancer. We show that LACTB is significantly down-regulated in epithelial ovarian cancer cells and clinical tissues. Re-expression of LACTB negatively effects the growth of cancer cells but not of non-tumorigenic cells. Mechanistically, we show that LACTB leads to differentiation of ovarian cancer cells and loss of their stemness properties, which is achieved through the inhibition of the EMT program and the LACTB-dependent down-regulation of Snail2/Slug transcription factor. This study uncovers a novel role of LACTB in ovarian cancer and proposes new ways of counteracting the oncogenic EMT program in this model system.
