New Paper: Human microRNAs transcribed by polymerase III November 14, 2006Posted by Sacha in Evolution, Genetics, microRNA, Research, Science.
A new paper out this week in Nature Structural and Molecular Biology presents evidence that Polymerase III is associated with miRNA genomic sequence and sufficient for transcription. This is as opposed to the privious view that Pol II was required in mammals for expression. The miRNAs they analyzed (miR-515-1, 517a, 517c, 519a-1) were interspersed among the Alu repeats, which are transcribed through Pol III recruitment.
Now, I had to ask myself after I read the abstract for this article, “What are Alu repeats?” and “Why do I care if they hang out on the chain with miRs?” If Wikipedia is accurate, and I hope it is, the Alu family is a family of polymorphisms in the human genome, about 300 bp long. Their repetitive sequences are the most abundant mobile units on the human genome and have been implemented in diseases, such as cancer. As for the second question, this connection suggests that repetitive elements play an important role in human miRNA origin and expression, according to this new paper.