email hernande@cshl.edu, phone (516) 367-8421, fax (516) 367-6801

With the sequencing of entire genomes from a growing number of organisms, biology is faced with the challenge of understanding how individual genes are specifically expressed, and how this expression is regulated. A large part of the regulation occurs at the transcriptional level. We are interested in understanding fundamental mechanisms of transcription and transcription regulation. As a model system, we use the human small nuclear RNA (snRNA) genes. These genes are unusual because some of them are transcribed by RNA polymerase II and some by RNA polymerase III, yet they all share very similar promoter structures. They constitute, therefore, an ideal model system to study how RNA polymerase specificity is determined. Another advantage is that in the case of the RNA polymerase III snRNA genes, we have recently been able to reconstitute transcription with well-defined factors. Because the basal transcription machinery is the ultimate target of signal transduction pathways, this gives us a unique opportunity to study mechanisms of regulation.

Transcription from the human RNA polymerase III U6 promoter can be reconstituted in vitro with a set of eight recombinant factors and RNA polymerase III highly purified from human cultured cells. We find that the highly purified RNA polymerase III contains associated CK2. In the reconstituted transcription system, treatment of RNA polymerase III with CK2 is required for transcription, whereas treatment of Bdp1, one of the factors required for promoter recognition by RNA polymerase III, is inhibitory. This leads to a model in which CK2 can either activate or repress U6 transcription depending on which target it phosphorylates. Some of our present studies are aimed at understanding how CK2 is directed to either activate or repress transcription.

Selected Publications