Microbiology
Mycobacterium tuberculosis EsxL inhibits MHC-II expression by promoting hypermethylation in class-II transactivator loci in macrophages
Mycobacterium tuberculosis is known to modulate the host immune responses to facilitate its persistence inside the host cells. One of the key mechanisms includes repression of class-II transactivator (CIITA) and MHC-II expression in infected macrophages. However, the precise mechanism of CIITA and MHC-II down-regulation is not well studied. M. tuberculosis 6-kDa early secretory antigenic target (ESAT-6) is a known potent virulence and antigenic determinant. The M. tuberculosis genome encodes 23 such ESAT-6 family proteins.Dimethylated H3K27 Is a Repressive Epigenetic Histone Mark in the Protist Entamoeba histolytica and Is Significantly Enriched in Genes Silenced via the RNAi Pathway
Background: Entamoeba histolytica has an RNAi-mediated TGS pathway but the epigenetic marks are not known.Results: H3K27Me2 is an inducible repressive histone modification enriched in loci silenced by small RNAs.Conclusion: Transcriptional gene silencing and chromatin modification are coupled to maintain prolonged gene silencing.Significance: This work identifies the first repressive histone mark in Entamoeba and links it to RNAi.
