Role of Ccr4-Not complex in heterochromatin formation at meiotic genes and subtelomeres in fission yeast

摘要: Heterochromatin is essential for chromosome segregation, gene silencing and genome integrity. The fission yeast Schizosaccharomyces pombe contains heterochromatin at centromeres, subtelomeres, mating type genes, as well small islands of meiotic genes dispersed across the genome. This generated by partially redundant mechanisms, including production interfering RNAs (siRNAs) that are incorporated into RITS protein complex (RNAi-Induced Transcriptional Silencing). assembly requires function RNA-binding Mmi1, which recruits to its mRNA targets islands. In addition, Mmi1 directs an exosome-dependent RNA elimination pathway. Ccr4-Not a conserved multiprotein regulates expression multiple levels, degradation translation. We show here recruited targets. Surprisingly, Ccr4 Caf1 (the deadenylase catalytic subunits complex) not necessary or translation targets, but integrity Mmi1-dependent and, independently subtelomeric regions. Both roles require activity Mot2/Not4 protein, ubiquitin ligase also part complex. Genetic evidence shows Ccr4-mediated normal cell growth, indicating this novel regulation physiologically relevant. Moreover, interacts with components in Mmi1-independent manner. Taken together, our results demonstrate required both pathways.