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Florida Faculty and Professional Staff
Patrick Griffin
Chairman
Department of Molecular Therapeutics
TSRI - 2004
Joint Appointments Director and Head, Translational Research Institute
Education
B.S. - Syracuse University, Syracuse NY,1985, Chemistry
Ph.D. - University of Virginia, Charlottesville, VA, 1989, Chemistry
Postdoc - California Institute of Technology, Pasadena, CA, 1991, Biotechnology
Research Focus
Structural and Chemical Biology of Enzymes and Receptors
Our group combines chemical and cell biology with structural biology to study mechanism and structure-function of enzymes and receptors; particularly kinases, G-protein coupled receptors (GPCRs) and nuclear receptors (NRs). During the past few years we have focused on developing hydrogen/deuterium exchange (HDX) technology for probing the mechanism of activation of intact nuclear receptor complexes. Specifically we have used HDX, chemical libraries and cell-based assays to better understand ligand activation and co-receptor/co-factor interaction within the vitamin D receptor (VDR) and the peroxisome proliferator-activated receptor (PPAR) complex. We have applied HDX and chemical approaches to the study of the orphan nuclear receptors LRH-1 and RORA (in collaboration with Thomas Burris) which have been implicated in cancer and metabolic disorders. Our HDX platform is part of the center based initiative of the Scripps Research Institute Molecular Screening Center (SRIMSC) and is being applied to several chemical probe development projects. Also as part of the SRIMSC initiative and in collaboration with Juliana Conkright, we have developed novel screening platforms to facilitate the discovery of potent and selective nuclear receptor modulators. Finally, to broaden the application of HDX we have initiated collaborations with the Rosen and Stevens’ laboratories, TSRI CA, to study the dynamics of GPCRs upon ligand interaction.
Mechanistic studies of ligand activation of VDR/RXR full length heterodimer complex
Here we are applying HDX towards the characterization of ligand activation of the vitamin D receptor (VDR) in complex with its co-receptor retinoid X receptor alpha (RXRa). This project is driving further development of our HDX platform to facilitate the analysis of large transcriptional complexes. We have successfully probed the dynamics of the functional domains of both VDR and RXR within this complex as a function of both ligand and DNA interaction. Our data clearly demonstrates the role of DNA interaction in the functional state of the VDR/RXR heterodimer complex by directly controlling dynamics of surfaces of the receptor complex that interact with co-activators.
Probing GPCRs by HDX
GPCRs are an important family of trans-membrane signaling proteins and are therapeutic targets in many disorders. The characterization of the structure and dynamics of these receptors present a considerable analytical challenge due to the hydrophobic nature of their transmembrane domains. The Stevens’ lab recently solved the structure of the beta-2 adrenergic receptor at 2.4 Å resolution and in collaboration with their lab we have initiated studies to probe beta-2 adrenergic receptor-ligand interactions.
Structural and Chemical Biology of the orphan nuclear receptor LRH-1
Our laboratory has taken a multi-pronged approach to understanding the biology of the orphan nuclear receptor LRH-1 (liver receptor homolog-1). Modulation of LRH-1 activity has been implicated in breast cancer, cholesterol homeostasis, and in intestinal inflammation. We have developed several HTS ready assays to facilitate screening for small molecules that positively modulate (agonize) or negatively modulate (inverse agonize) the activity of the receptor. More importantly, we have developed several functional assays to better understand the potential utility of small molecule modulators of LRH-1 for treatment of breast cancer and metabolic disorders.
Novel modulators of RORα
Using a unique human nuclear receptor library we have discovered novel modulators of RORα. In collaboration with William Roush and the SRIMSC, we have generated structure-activity-relationships around this molecule in an effort to improve potency and selectivity. HDX is being employed to guide SAR studies in this project. In addition, we have developed several cell-based assays to examine the effects of these molecules in biological pathways controlled by RORα; such as the control of adipogenesis and it role in insulin sensitization.
Selected References
Dai SY, Chalmers MJ, Bruning J, Bramlett KS, Osborne HE, Montrose-Rafizadeh C, Barr RJ, Wang M, Burris TP, Dodge JA, and Griffin PR, Prediction of the tissue-specificity of selective estrogen receptor modulators using a single biochemical method, Proc. Nat. Acad. Sci, USA 105: 7171, 2008.
Pascal BD, Chalmers MJ, Busby SA, and Griffin PR, HD Desktop: an integrated platform for the analysis and visualization of H/D exchange data,JASMS, 20:601-10, 2009.
Lauer-Fields JL, Chalmers MJ, Busby SA, Visse R, Minond D, Nagase H, Griffin PR, and Fields GB, Identification of Specific Hemopexin-like Domain Residues That Facilitate Matrix Metalloproteinase Collagenolytic Activity, J. Biol. Chem. 2009, (available online).
Avvaru BS, Busby SA, Chalmers MJ, Griffin PR, Venkatakrishnan B, Silverman DN, and McKenna R, Apo-human carbonic anhydrase II revisited: Implications of the loss of a metal in protein structure, ability and solvent network, Biochemistry, 2009, (available online).
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