PositionJames B. Duke Professor of Pharmacology and Cancer Biology
Our lab is interested in the regulation of complex cellular processes, including entry into mitosis and apoptosis (programmed cell death). We are particularly interested in understanding cellular mechanisms which prevent the onset of mitosis prior to the completion of DNA replication and in the tyrosine kinase signaling pathways which impinge upon the decision to apoptose. To address these problems, we use cell-free extracts prepared from eggs of the frog Xenopus laevis which can recapitulate cell cycle events and apoptotic processes in vitro. For the study of cell cycle events, extracts are prepared which can undergo multiple rounds of DNA replication and mitosis in vitro. Progression through the cell cycle can be monitored by microscopic observation of nuclear morphology and by biochemically assaying the activity of serine/threonine kinases which control cell cycle transitions. For the study of apoptosis, modifications in extract preparation have allowed us to produce extracts which can apoptotically fragment nuclei and can accurately reproduce the biochemical events of apoptosis, including internucleosomal DNA cleavage and activation of caspases, the apoptotic proteases. These powerful in vitro extracts allow us to examine and dissect critical signaling events by: 1) immunodepletion of cellular components from the extracts 2) addition of exogenously produced recombinant proteins and 3) direct biochemical purification of regulatory proteins. Using these molecular and biochemical approaches, we are working towards the elucidation of signaling pathways required for cell proliferation and cell death.
Duke University Medical Center