Research Topics
Department of Plant Biology
Ph.D. (1982) Michigan State University
Research Topics
Research Interests
Passage of proliferating eukaryotic cells from one stage of the cell cycle to the next is subject to a strict control program largely mediated by protein kinases. On the other hand, passage of cell populations into and out of the proliferative state is subject to a completely different set of signaling factors and pathways. We study both of these regulatory aspects of cell division. We use the tools of molecular biology, immunology, and cell biology to investigate biochemical cell division and signal transduction functions at the level of genes, messenger RNAs, proteins, organelles, cells, and tissues.
Our cell cycle work is focused on cyclin dependent kinases (CDKs) and their regulatory subunits, the cyclins. We have cloned three CDKs and three cyclin genes from Pisum sativum, the garden pea. With these DNA clones, and proteins expressed from them, we are studying cycling and post-mitotic cells of the maturing pea root, in an effort to understand how developmental controls are superimposed upon cell cycle regulatory elements in a higher plant. We have more recently begun to use these tools to search for additional cell cycle regulatory elements with which CDK and cyclin proteins physically interact.
Our signal transduction interest is presently confined to the pathways that connect extracellular and developmental signals to the mitotic engine per se. In this context, we are studying the MAP kinase pathway of higher plants, currently alfalfa and Arabidopsis. The ubiquitous MAP kinase pathway consists of, at its core, a module of three protein kinases that serially activate each other. At its upstream end, this module is ultimately activated by receptors for growth regulators and sensors for a wide variety of cellular parameters. Downstream, the MAP kinase pathway activates transcription factors and other signaling intermediates, thus profoundly altering the physiological state of the cell. Eventually, we expect to characterize the connections between the MAP kinase signaling pathway and CDK/cyclin-driven mitotic control machinery.
Key Words Recombinant DNA, Introduction of DNA into Plant Cells, Gene
Expression Systems, Protein-Protein Interaction, Site-Directed Mutagenesis,
Protein Purification and Characterization, Plant Cell and/or Tissue Culture,
Plant Transformation