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Bruce Conklin, MD

Bruce Conklin, MD
Senior Investigator, Gladstone Institute of Cardiovascular Disease
Professor, Department of Medicine
Research Summary:

Receptors, Stem Cells and Pharmacology

Conklin Lab Mission Statement:
The Conklin Lab studies the mechanisms by which hormone receptors direct the development and function of complex tissues, including the cardiovascular system. Our primary focus is on the largest known family of receptors for hormones and drugs, the G protein coupled receptors (GPCRs), which are essential for the actions of over half the world¹s pharmaceuticals. Our model system is tissue derived from patient-specific induced pluripotent (iPS) cells. We differentiate iPS cells and selectively activate signaling pathways with activated G proteins or designer GPCRs.  Our goal is to use signal engineering to open new avenues for biological investigation and develop novel therapeutic strategies.

Approaches and Contributions:
The late Richard Feynman once said, "What I cannot create, I do not understand." Although this principle is well known in the field of engineering, we are just beginning to understand its application in biology.

Our approach focuses on building new controls for pharmacological signaling pathways, in order to understand how endogenous hormone signaling pathways can be used for therapeutic purposes.  Just as an electrician tests connection with current and rewires as needed, we test signaling connections with activated G proteins and designer receptors. By using iPS cells from patients with defined genetic diseases we can rewire signaling pathways in models of human disease.

We have engineered GPCRs called RASSLs (receptors activated by small synthetic ligands, see Coward et al 1998) that are unresponsive to endogenous natural hormones, but can still be activated via synthetic small-molecule drugs. We have successfully expressed RASSLs in a wide variety of tissues, and have experienced success in controlling responses such as heart rate (Redfern 1999). These first generation RASSLs have proven to be powerful tools for the examination of GPCR signaling in complex systems, including bone development, taste, and olfactory development. In recent years, we have been able to develop RASSLs that can activate all of the major GPCR pathways (see Conklin, 2008). RASSLs are widely used to answer basic questions in neurobiological, endocrine, and cardiovascular studies.

Our primary experimental system is human iPS cells from patients with known genetic diseases or matched controls.  We are investigating how signaling can enhance iPS cell formation, maintain pluripotency, enhance differentiation, and alter human disease phenotypes.  By using in vitro models that match human disease, we hope to identify pharmacological approaches to treat disease. Current human iPS studies involve genetic diseases of cardiac conduction, contraction, as well as the innervation of the cardiac and visceral organs.  In each case, we are defining the role of signaling pathways.

To gain insights into human disease, our work is highly collaborative and interdisciplinary. To analyze large-scale gene expression studies (RNA-seq) we have developed or contributed to various powerful, open platforms (WikiPathways.org, GenMAPP.org, AltAnalyze.org and Cytoscape.org).  We helped to pioneer large scale gene trapping with BayGenomics, an effort that helped inspire the international Knockout Mouse Project (KOMP).  We work closely with cell biologists, medicinal chemists, clinical specialists, tissue engineers, and developmental biologists.  Our own work is focused on making new models of disease, and finding new drug targets for treating these diseases.

Selected Publications

Tingley WG, Pawlikowska L, Zaroff JG, Kim T, Nguyen T, Young SG, Vranizan K, Kwok PY, Whooley MA, and Conklin BR (2007) Gene-trapped mouse embryonic stem cell-derived cardiac myocytes and human genetics implicate AKAP10 in heart rhythm regulation. Proc Natl Acad Sci U S A 104:8461-8466.

Conklin BR, Hsiao EC, Claeysen S, Dumuis A, Srinivasan S, Forsayeth JR, Guettier JM, Chang WC, Pei Y, McCarthy KD, Nissenson RA, Wess J, Bockaert J, Roth BL (2008) Engineering GPCR signaling pathways with RASSLs. Nat. Methods 5:673­678.

Pico AR, Kelder T, van Iersel MP, Hanspers K, Conklin BR, and Evelo C (2008) WikiPathways: pathway editing for the people. PLoS Biol 6:e184 (PMC2475545).

Nakamura K, Salomonis N, Tomoda K, Yamanaka S, Conklin BR (2009) Gi-coupled GPCR signaling controls the formation and organization of human pluripotent colonies. PLoS One 4:e7780.

Hsiao EC, Millard SM, Louie A, Huang Y, Conklin BR, and Nissenson RA (2010) Ligand-mediated activation of an engineered Gs G protein-coupled receptor in osteoblasts increases trabecular bone formation. Mol Endocrinol 24:621-631.

Salomonis N, Schlieve CR, Pereira L, Wahlquist C, Colas A, Zambon AC, Vranizan K, Spindler MJ, Pico AR, Cline MS, Clark TA, Williams A, Blume JE, Samal E, Mercola M, Merrill BJ, and Conklin BR (2010) Alternative splicing regulates mouse embryonic stem cell pluripotency and differentiation. Proc Natl Acad Sci U S A 107:10514-10519.