Educational background:

1. A Levels in Physics, Chemistry and Biology, Worthing College, Worthing England 1979
2. B.S. Biochemistry, Eastern Michigan University, Ypsilanti, Michigan 1984
3. M.S. Biochemistry and Molecular Biology, Wayne State University Medical School, Detroit MI 1986
4. Ph.D. Biochemistry and Molecular Biology, Wayne State University Medical School, Detroit, MI 1992
5. Postdoctoral Fellow, Biochemistry, Universite Pierre et Marie Curie (University of Paris VI), Paris, France 1992-94

Research Interests:

I am interested in the signal transduction pathways involved in the regulation of cell growth and proliferation in normal and neoplastic cells. The MAP kinase cascade, a coupled series of regulatory proteins, transmits signals induced by the binding of growth factors to receptors on the surface of cells. The signals are relayed to intracellular targets that promote cell proliferation. We would like to understand the interplay or crosstalk between the MAP kinase signal transduction pathway and the cAMP-dependent protein kinase (PKA) cascade that antagonizes growth in many types of cells. We discovered that CAD, a multifunctional protein that initiates and controls pyrimidine biosynthesis is one of the targets of MAP kinase. The flux through the pathway is precisely controlled by CAD and its activation is a prerequisite for the growth of tumors and neoplastic tissues. Phosphorylation of a specific threonine residue of CAD, Thr456, by MAP kinase activates CAD and promotes an increase in pyrimidine biosynthesis just prior to the onset of S phase of the cell cycle when the demands for pyrimidine nucleotides for DNA synthesis is the greatest. Once DNA replication is completed, Thr456 is dephosphorylated, PKA phosphorylates CAD Ser1406 and the pathway is down-regulated. Interestingly, we recently found that the elevated rate of pyrimidine biosynthesis in human MCF7 breast cancer cells is a consequence of elevated levels of CAD in the cell and a breakdown of the normal up and down regulation of the pathway. Differences in the CAD phosphorylation state are responsible for the defective control of pyrimidine biosynthesis. Elevated MAP kinase activity results in persistent phosphorylation of CAD Thr456 while the PKA site remains unphosphorylated. Using recombinant DNA methods, we have constructed chimeric proteins in which CAD is fused to the green fluorescent protein, an intensely fluorescent protein isolated from a jelly fish. These constructs have allowed us to track the movement of CAD in living cells by fluorescence microscopy. Coincident with the MAP kinase mediated activation of CAD during S phase, the protein moves from the cytoplasm into the nucleus where it binds to nuclear substructures such as the nuclear matrix and specific sites on the chromosomes. This is a new area of research, but we have all of the tools necessary to decipher the signals that trigger nucleocytoplasmic translocation and the physiological significance of the intracellular dynamics of CAD.

A second project is an investigation of the structure and the adaptive mechanisms of proteins isolated from hyperthermophilic organisms that flourish near deep-ocean hydrothermal vents or other extreme marine environments at temperatures close to 100oC. We have cloned several of the pyrimidine biosynthetic enzymes from two of these organisms, Pyrrococcus abyssi and Aquifex aeolicus. As expected, these proteins are extremely stable and have interesting functional characteristics just now being discovered that allow them to function efficiently at elevated temperature and to preserve unstable intermediates from thermal degradation. These mechanisms are of special interest, not only because they represent an important aspect of the biology of these fascinating organisms, but also because they should have important biotechnological implications in the design of new or stable enzyme variants for medical or industrial applications.

Courses Taught at EMU:

General Biochemistry (Chem 351)
Biochemistry (Chem 451-453)

Professional Affiliations:

Managing Editor, Intracellular Signaling and Metabolic Control, Frontiers in Bioscience, 2003–present
The American Society for Biochemistry and Molecular Biology (ASBMB), 2002–present
The American Chemical Society (ACS), 2006-present
Council of undergraduate research (CUR), 2006-present

Selected Publications:

Nuclear localization of the multifunctional protein CAD phosphorylated by the MAP kinase cascade, Frederic D. Sigoillot, Damian H. Kotsis, Valerie Serre, Severine M. Sigoillot, David R. Evans and Hedeel I. Guy (2005) J. Biol. Chem. 280, 25611-25620.

The Crystal Structure of a Novel, Latent Dihydroorotase from Aquifex aeolicus at 1.7 A Resolution. Philip I. Martin, Cristina Purcarea, Pengfei Zhang, Asmita Vaishnav, Sharon Sadecki, Hedeel I. Guy-Evans, David R. Evans and Brian F. P. Edwards (2005) J. Mol. Biol. 348:535-47.

Protein Kinase A Phosphorylation of the Multifunctional Protein CAD Antagonizes Activation by the MAP Kinase Cascade. Damian H. Kotsis, Elizabeth M. Masko, Frederic D. Sigoillot, Roberto Di Gregorio, Hedeel I. Guy-Evans and David R. Evans (2007) Molecular Cellular Biochem. Jul; 301(1-2):69-81.

Protein Kinase C modulates the upregulation of the pyrimidine biosynthetic complex, CAD, by MAP kinase. Frederic D. Sigoillot, Damian H. Kotsis, Elizabeth M. Masko, Monica Bame, David R. Evans, Hedeel Guy Evans (2007) Front. Biosci. 12: 3892-3898.