The National Institute of Diabetes & Digestive & Kidney Diseases

My laboratory focuses on the following two major lines of work:

I. G protein-coupled receptors (GPCRs): Molecular basis of activation and function and structural studies

II. Generation and analysis of GPCR mutant mice to explore the roles of distinct GPCR signaling pathways in the regulation of energy and glucose homeostasis, as well as other physiological functions

I. G PROTEIN-COUPLED RECEPTORS (GPCRs): MOLECULAR BASIS OF ACTIVATION AND FUNCTION AND STRUCTURAL STUDIES
One major focus of my group is to understand how GPCRs function at the molecular level. GPCRs, one of the largest protein families found in nature, are cell surface receptors that mediate the functions of an extraordinarily large number of extracellular ligands (neurotransmitters, hormones, etc.). The human genome contains ~800 distinct GPCR genes, corresponding to ~3-4% of all human genes. Strikingly, ~30-40% of drugs in current clinical use act on specific GPCRs. Understanding how GPCRs function at the molecular level is therefore of considerable therapeutic relevance. My lab uses different molecular genetic and biochemical strategies to address the following fundamental questions regarding the structure and function of these receptors: 1. How to GPCRs interact with G proteins and other GPCR-associated proteins? 2. Which conformational changes do activating ligands induce in the receptor protein? 3. What is the structural basis and functional relevance of GPCR dimerization? My lab is also engaged in efforts, in collaboration with Dr. Brian Kobilka's lab, to obtain high-resolution X-ray structures for members of the muscarinic receptor family of GPCRs. These studies should eventually lead to novel therapeutic approaches aimed at modulating the function of specific GPCRs.

II. GENERATION AND ANALYSIS OF GPCR MUTANT MICE
Many of the important physiological functions of the neurotransmitter acetylcholine are caused by the interaction of acetylcholine with a group of GPCRs referred to as muscarinic receptors. Molecular cloning studies have revealed the existence of five molecularly distinct muscarinic receptor subtypes which are referred to as M1-M5. The M1-M5 receptors are abundantly expressed in most cells and tissues and are critically involved in regulating many fundamental physiological processes including, for example, the regulation of body weight and food intake, the release of insulin from pancreatic beta cells, and many key functions of the CNS including most cognitive processes. To elucidate the physiological roles of the individual muscarinic receptor subtypes, we are using gene targeting techniques, including Cre/loxP technology, to generate mouse lines lacking functional M1-M5 muscarinic receptors either throughout the body or only in certain tissues or cell types. Current phenotyping studies are focusing on the potential roles of the different muscarinic receptor subtypes in regulating energy and glucose homeostasis in various peripheral and central tissues.

In a related line of work, we are generating and analyzing transgenic mice expressing mutationally modified designer GPCRs in specific, metabolically relevant cell types such pancreatic beta and alpha cells, adipocytes, hepatocytes, myocytes, and certain subsets of hypothalamic neurons. These designer GPCRs are unable to bind endogenous ligands but can be efficiently activated by an exogenously administered drug (clozapine-N-oxide; CNO). This drug is otherwise pharmacologically inert. For this work, we are using several CNO-sensitive designer GPCRs that differ in their G protein-coupling properties (Gq, Gs, Gi, etc.). This novel approach makes it possible to selectively activate (in vivo!) distinct GPCR signaling pathways in a cell type-specific and drug-dependent fashion. These studies, which are being carried out in collaboration with the NIDDK metabolic phenotyping, transgenic, and mouse knockout core facilities, are likely to identify novel therapeutic targets for the treatment of various pathophysiological conditions including type 2 diabetes and obesity.

(since 2006):

Ruiz de Azua I, Nakajima K, Rossi M, Cui Y, Jou W, Gavrilova O, Wess J. Spinophilin as a novel regulator of M3 muscarinic receptor-mediated insulin release in vitro and in vivo. FASEB J. 26, 4275-4286, 2012

Kruse AC, Hu J, Pan AC, Arlow DH, Rosenbaum DM, Rosemond E, Green HF, Liu T, Chae PS, Dror RO, Shaw DE, Weis WI, Wess* J, Kobilka*. Structure and dynamics of the M3 muscarinic acetylcholine receptor. Nature 482, 552-556, 2012 (*Co-corresponding authors)

Hu J, Thor D, Zhou Y, Liu T, Wang Y, McMillin SM, Mistry R, Challiss RA, Costanzi S, Wess J. Structural aspects of M₃ muscarinic acetylcholine receptor dimer formation and activation. FASEB J. 26, 604-616, 2012

Ruiz de Azua I, Gautam D, Guettier JM, Wess J. Novel insights into the function of β-cell M3 muscarinic acetylcholine receptors: therapeutic implications. Trends Endocrinol. Metab. 22, 74-80, 2011

Hu J, Wang Y, Zhang X, Lloyd JR, Li JH, Karpiak J, Costanzi S, Wess J. Structural basis of G protein-coupled receptor-G protein interactions. Nat. Chem. Biol. 6, 541-548, 2010

Ruiz de Azua I, Scarselli M, Rosemond E, Gautam D, Jou W, Gavrilova O, Ebert PJ, Levitt P, Wess J. RGS4 is a negative regulator of insulin release from pancreatic beta-cells in vitro and in vivo. Proc. Natl. Acad. Sci. U.S.A. 107, 7999-8004, 2010

Jeon J, Dencker D, Wörtwein G, Woldbye DP, Cui Y, Davis AA, Levey AI, Schütz G, Sager TN, Mørk A, Li C, Deng CX, Fink-Jensen A, Wess J. A subpopulation of neuronal M4 muscarinic acetylcholine receptors plays a critical role in modulating dopamine-dependent behaviors. J. Neurosci. 30, 2396-2405, 2010

Guettier JM, Gautam D, Scarselli M, Ruiz de Azua I, Li JH, Rosemond E, Ma X, Gonzalez FJ, Armbruster BN, Lu H, Roth BL, Wess J. A chemical-genetic approach to study G protein regulation of beta-cell function in vivo. Proc. Natl. Acad. Sci. U.S.A. 106, 19197-19202, 2009

Li JH, Chou CL, Li B, Gavrilova O, Eisner C, Schnermann J, Anderson SA, Deng CX, Knepper MA, Wess J. A selective EP4 PGE2 receptor agonist alleviates disease in a new mouse model of X-linked nephrogenic diabetes insipidus. J. Clin. Invest. 119, 3115-3126, 2009

Gautam D, Jeon J, Starost MF, Han SJ, Hamdan FF, Cui Y, Parlow AF, Gavrilova O, Szalayova I, Mezey E, Wess J. Neuronal M3 muscarinic acetylcholine receptors are essential for somatotroph proliferation and normal somatic growth. Proc. Natl. Acad. Sci. USA 106, 6398-6403, 2009

Wess J, Han SJ, Kim SK, Jacobson KA, Li JH. Conformational changes involved in G-protein-coupled-receptor activation. Trends Pharmacol. Sci. 29, 616-625, 2008.

Wess J, Eglen RM, Gautam D. Muscarinic acetylcholine receptors: mutant mice provide new insights for drug development Nat. Revs. Drug Discov. 6, 721-733, 2007.

Li B, Scarselli M , Knudsen CD, Kim SK, Jacobson KA, McMillin S., Wess J. Rapid identification of functionally critical amino acids in a G protein-coupled receptor. Nature Methods 4, 169-174, 2007.

Gautam D, Gavrilova O, Jeon J., Pack S., Jou W, Cui Y, Li JH, Wess, J. Beneficial metabolic effects of M3 muscarinic acetylcholine receptor deficiency. Cell Metabolism 4, 363-75, 2006.

Gautam D, Han SJ, Hamdan FF, Jeon J, Li B, Li JH, Cui Y, Mears D, Lu H, Deng C, Heard T, Wess J. A critical role for beta cell M3 muscarinic acetylcholine receptors in regulating insulin release and blood glucose homeostasis in vivo. Cell Metabolism 3, 449-61, 2006.