Arno Lee Greenleaf

      My laboratory studies the mechanisms by which different activities in the cell nucleus are connected to the transcription machinery via interactions with the hyper-phosphorylated C-terminal repeat domain (PCTD) of elongating RNA polymerase II. Differential phosphorylation of the CTD, as the RNAP proceeds through successive stages of transcription, orchestrates sequential recruitment of factors to the transcriptase; this serves to coordinate RNA processing events and mRNA nuclear export with gene transcription. To gain a thorough understanding of relevant phosphorylation events on the PCTD, we identified the principal elongation-phase CTD kinase activities in three different eukaryotes, yeast (yCtk1), Drosophila (dCDK12) and humans (hCDK12 & 13).  In addition, we described a novel set of phosphoCTD-associating proteins (“PCAPs”) that we now are investigating primarily in human cells. Our results revealed novel roles for elongating RNAPII, and they engendered several totally new lines of investigation.         

      Recently hCDK12 was shown to be a tumor suppressor for ovarian cancer, and our investigations of this kinase will illuminate its features that, when mutated, can lead to ovarian cancer.

      In another cancer-related project, we are identifying drug targets for a new class of drugs to be aimed at ovarian and breast cancers.