MiR18a and miR19a recruit specific proteins for splicing in thyroid cancer cells

Abstract

Background: Thyroid cancer is one of the most frequent types of endocrine cancers. In most cases, thyroid cancers are caused by deregulated miRNA expression, especially involving the miR17-92 cluster. miR17-92 transcription is altered in several different tumor types including lymphoma, leukemia, and of the breast and thyroid. As an intronic cluster, miR17-92 must be processed during splicing and therefore interaction between microprocessor and spliceosome machineries is of major importance in understanding its expression. Materials and Methods: We investigated the protein composition of spliceosomes assembled on pre-RNAs containing intronic miR18a and miR19a, components of the miR17-92 cluster, using mass spectrometry. Results: Interestingly, we observed that proteins associated with intronic miR18a and miR19a are cell-specific, and are similar for both miRNAs analyzed. The only exception is the group of heterogeneous nuclear proteins that are commonly recruited by different cells. Conclusion: miRNA processing depends on cell-specific proteins and heterogeneous nuclear proteins have a general role in miRNA processing from introns.