The laboratory uses a broad range of molecular, biochemical and biophysical research tools centered around X-ray crystal structure determination to understand the mechanism of chromatin recognition and assembly and post-translational histone and protein modification in the regulation of gene expression; and kinase signaling pathways. The laboratory is particularly interested in gene regulatory proteins and their upstream signaling kinases that are aberrantly regulated in cancer and age-related metabolic disorders such as type II diabetes and obesity, and the use of high-throughput small molecule screening and structure-based design strategies towards the development of protein-specific small-molecule probes to be used to further interrogate protein function and for development into therapeutic agents.
Chromatin recognition and assembly and histone modification in gene regulation. DNA within the eukaryotic nucleus is compacted into chromatin containing histone proteins and its appropriate regulation orchestrates all DNA-templated reactions such as DNA transcription, replication, repair, mitosis, and apoptosis. Among the many proteins that regulate chromatin, the proteins that recognize DNA, assemble chromatin, called histone chaperones, and that modify the histones through the addition or removal of functional groups such as acetyl, methyl or phosphate play important roles. We are studying the DNA binding proteins p53, FoxO and the Gal4 family; the histone chaperones HIRA, Asf1, Vps75 and their associated factors; and the family of histone acetyltransferase (HAT) and histone deacetylase (HDAC) enzymes. We are particularly interested in how DNA binding proteins navigate the recognition of their cognate DNA targets, how histone chaperones coordinate the assembly of distinct chromatin complexes correlated with different DNA regulatory processes, and how histone modification enzymes link catalysis to their substrate specific activities for their respective biological activities. More recently, we have been studying how the binding of accessory and regulatory protein subunits regulates the various activities of these proteins and in some cases we are developing small molecule protein specific inhibitors.
Enzymes associated with aging and age-related disorders.Sirtuin enzymes are NAD+-dependent histone and protein deactylases and/or ADP-ribotransferases that have been implicated in the regulation of gene expression, cellular aging, adipogenesis, type II diabetes and several neurodegenerative disorders. We have determined the structure of these enzymes in several liganded forms and have developed novel small molecule sirtuin inhibitors. Together with associated biochemical studies, these studies have provided insights into the mode of catalysis and substrate-specific recognition by this protein family and have illuminated new avenues for small molecule effector design. We are currently working towards understanding the factors that distinguish different sirtuin proteins and how the functions of these proteins are modulated by other protein factors. We are also pursuing structure/function studies of other proteins that are implicated in aging and age-related disorders.
Tumor suppressors and oncoproteins. We are carrying out biochemical and structural studies on the tumor suppressor proteins pRb, p53 and p300/CBP, both alone and in complex with their relevant protein targets. We are also interested in the mode of inactivation of these tumor suppressors by the viral oncoproteins E7 and E6 from human papillomavirus (HPV), the etiological agent for cervical cancer, and Adenovirus (Ad) E1A. We are also combining structural studies with small molecule screening to prepare small molecule HPV-E7 and for HPV-E6 inhibitors. Most recently we have begun to exploit structure-based design strategies to develop inhibitors of oncogenic kinases, such as PI3K, BRAF and PAK1 implicated in melanoma and other cancers. Our goal for these studies is to derive functional and structural information that will lead to the design of small molecule compounds that may have therapeutic applications.
Tumor suppressors and viral oncoproteins- We are pursuing biochemical and structural studies on the tumor suppressor proteins p18INK4c, pRb, p53 and p300/CBP, both alone and in complex with their relevant protein targets. The activity of pRb is inhibited by several known DNA viral oncoproteins, including human papillomavirus (HPV) E7, the etiological agent for cervical cancer, and Adenovirus (Ad) E1A. We have most recently characterized the binding properties of pRb to HPV-E7 and Ad-E1a and are now determining their structures both alone and in complex with pRb. Our goal for these studies is to derive functional and structural information that will lead to the design of small molecule compounds that may have clinical applications against cancer.
Protein-DNA recognition- As a model to understand sequence-specific DNA recognition by transcriptional regulatory proteins, we are studying the structure and function of three families of DNA binding proteins, the fungal specific Zn2Cys6 binuclear cluster proteins, the higher eukaryotic Ets proteins and p53. We have determined several structures of these proteins either alone or in complex with their associated DNA targets and are continuing to use these proteins as a model to understand DNA recognition by protein and protein complexes. With regard to p53, we are studying its unique mode of DNA recognition and are developing structure-based strategies for the repair of tumor-derived p53 mutations.
- B.S. University of California at Davis (1984)
- M.S. University of Chicago (1989)
- Ph.D. University of Chicago (1989)
- Postdoctoral Fellow, Harvard University (1989-1994)