Una Ullada a les transformacions epigenètiques del DNA en la reproducció

Es presenta un resum de les transformacions epigenètiques que experimenta el DNA en el procés de diferenciació dels gàmetes i en el desenvolupament de l'embrió.The epigenetic transformations of DNA during the differenciation of gametes and the development of the embryo are briefly presented

Myeloid C/EBPβ deficiency reshapes microglial gene expression and is protective in experimental autoimmune encephalomyelitis

Background CCAAT/enhancer binding protein β (C/EBPβ) is a transcription factor that regulates the expression of important pro-inflammatory genes in microglia. Mice deficient for C/EBPβ show protection against excitotoxic and ischemic CNS damage, but the involvement in this neuroprotective effect of the various C/EBPβ-expressing cell types is not solved. Since C/EBPβ-deficient microglia show attenuated neurotoxicity in culture, we hypothesized that specific C/EBPβ deficiency in microglia could be neuroprotective in vivo. In this study, we have tested this hypothesis by generating mice with myeloid C/EBPβ deficiency. Methods Mice with myeloid C/EBPβ deficiency were generated by crossing LysMCre and C/EBPβfl/fl mice. Primary microglial cultures from C/EBPβfl/fl and LysMCre-C/EBPβfl/fl mice were treated with lipopolysaccharide ± interferon γ (IFNγ) for 6 h, and gene expression was analyzed by RNA sequencing. Gene expression and C/EBPβ deletion were analyzed in vivo in microglia isolated from the brains of C/EBPβfl/fl and LysMCre-C/EBPβfl/fl mice treated systemically with lipolysaccharide or vehicle. Mice of LysMCre-C/EBPβfl/fl or control genotypes were subjected to experimental autoimmune encephalitis and analyzed for clinical signs for 52 days. One- or two-way ANOVA or Kruskal-Wallis with their appropriate post hoc tests were used. Results LysMCre-C/EBPβfl/fl mice showed an efficiency of C/EBPβ deletion in microglia of 100 and 90% in vitro and in vivo, respectively. These mice were devoid of female infertility, perinatal mortality and reduced lifespan that are associated to full C/EBPβ deficiency. Transcriptomic analysis of C/EBPβ-deficient primary microglia revealed C/EBPβ-dependent expression of 1068 genes, significantly enriched in inflammatory and innate immune responses GO terms. In vivo, microglial expression of the pro-inflammatory genes Cybb, Ptges, Il23a, Tnf and Csf3 induced by systemic lipopolysaccharide injection was also blunted by C/EBPβ deletion. CNS expression of C/EBPβ was upregulated in experimental autoimmune encephalitis and in multiple sclerosis samples. Finally, LysMCre-C/EBPβfl/fl mice showed robust attenuation of clinical signs in experimental autoimmune encephalitis. Conclusion This study provides new data that support a central role for C/EBPβ in the biology of activated microglia, and it offers proof of concept for the therapeutic potential of microglial C/EBPβ inhibition in multiple sclerosis

Crystal Structure of a Complex of DNA with One AT-Hook of HMGA1

We present here for the first time the crystal structure of an AT-hook domain. We show the structure of an AT-hook of the ubiquitous nuclear protein HMGA1, combined with the oligonucleotide d(CGAATTAATTCG)2, which has two potential AATT interacting groups. Interaction with only one of them is found. The structure presents analogies and significant differences with previous NMR studies: the AT-hook forms hydrogen bonds between main-chain NH groups and thymines in the minor groove, DNA is bent and the minor groove is widened