Signals from noncoding RNAs: unconventional roles for conventional pol III transcripts.

A range of noncoding RNAs are transcribed by pol III. A lot of them such as tRNA, 7SL RNA, 7SK RNA, 5S RNA, MRP RNA, Y RNAs, H1 RNA, and vault RNAs are considered as "house keeping" RNAs essential for eukaryotic cells. In recent years, researchers started to recognize the existence of unconventional functions of many pol III transcripts other than classical "house keeping" roles. Therefore, these ncRNAs could now be viewed as molecules with functional regulatory signals as well as cellular building blocks. These noncoding RNAs, all transcribed by pol III, may assemble regulatory networks with analogy to signaling pathways in eukaryotic cells. In this review we discuss these unconventional roles of pol III transcripts.