Identificação de proteínas reguladoras do <i>splicing</i> associadas à microRNAs.

Abstract

Pre-mRNA splicing is the process of intron removal and exon ligation in eukaryotes. It is performed by the spliceosome, a multi-megadalton machinery composed of RNAs and more than a hundred proteins. Most of these are core components of the complex being important for assembly and splicing catalysis. Some proteins are required for specific pre-mRNA substrates, defining an important regulatory feature of this complex. Intronic microRNAs (miRNAs) must be processed from the host gene to generate mature molecules. miR-17-92 is an intronic cluster composed of seven miRNAs which have been associated to the development of different tumors, in several different cells. In this work, we analyzed the splicing of two miRNAs belonging to this cluster in three different cell lines. Interestingly, we observed miR19a is more efficiently spliced than miR18a in all three cells analyzed. We also searched for specific proteins that can be involved in their respective splicing process. We observed hnRNP proteins are especially concentrated in spliceosomes assembled in introns containing these miRNAs, based on results of mass spectrometry. These results are important to understand how these miRNAs are spliced and matured and also can explain their different expression levels in different cells.