Regulation of the plant micro RNA machinery by a MSS47-mediated epigenetic mechanism

MANAVELLA PA; RÉ DA

Córdoba

Congreso; 52th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2016

Micro RNAs (miRNA) are 21 nucleotides molecules essential for post-transcriptional gene silencing. These molecules are generated from a structured RNA precursor and then incorporated into the RNA induced silencing complex (RISC). DICER-LIKE 1, HYPONASTIC LEAVES 1 and SERRATE are the main proteins involved in miRNA biogenesis but several new cofactors have being described recently. After processing of the miRNA precursors, ARGONAUTE 1 (AGO1) binds the mature miRNAs and inhibits targeted-mRNA translation or induces its cleavage. Using a forward genetic approach we have isolated novel mutants deficient in miRNA activity, from which several cofactors of the pathway, such as CPL1, RCF3 and the THO/TREX complex, have been recently described. Here we describe MIRNA-SILENCING SUPPRESSED 47 (mss47), another miRNA deficient mutant identified in our genetic screening. Small RNA blots and RT-qPCR showed that mss47 mutants present altered level of miRNAs and targets? mRNAs. MSS47 codifies a protein with a histone-methyltransferase domain. This protein does not directly regulate the transcripts levels of MIRNA genes or its targets. Our experiments show that MSS47 epigenetically regulates the abundance of essential factors of the miRNA pathway. Such depletion in the miRNA machinery impairs the production and activity of miRNAs and, therefore, the gene silencing and plant development.