Bruce R. Conklin, M.D.
Areas of investigation:
The Conklin Lab studies the mechanisms by which hormone receptors direct the development and function of complex tissues, including those found in the cardiovascular system. The focus of our research is on the largest known family of receptors for hormones and drugs, the G protein–coupled receptors (GPCRs), which include over 700 human genes. We combine genetic knockouts, designer GPCRs and bioinformatics techniques in order to gain a basic understanding of hormone signaling in mice and pluripotent embryonic stem (ES) cells.
GPCRs are the target for some of the most widely used pharmaceuticals to treat diseases that involve virtually all tissues in the body. Although our primary focus is on the process of ES cell differentiation into cardiovascular tissues, our work also encompasses the effects of pharmaceutical intervention on bone development, neurobiology and immune cell migration.
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 research utilizes bioinformatics programs, along with receptor engineering and advanced methods for measuring pharmacological responses. Since all GPCRs share a common design, they are ideal for testing synthetic signaling systems and mapping common signaling pathways.
New Receptors to Rewire Signaling Pathways:
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 RASSLs have proven to be catalysts in 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 the major GPCR pathways (see Conklin, PNAS 2007). Internationally, RASSLs are currently used in several laboratories in order to answer basic questions in neurobiological, endocrine and cardiovascular studies.
Stem Cells as a Model System:
Our functional genomic experiments focus on GPCR signaling pathways in pluripotent ES cell-derived cardiac myocytes. We use high-throughput gene inactivation methods, including siRNA and gene trapping in ES cells, and then analyze ES cell-derived cardiomyocytes. We are also studying ES cell differentiation at the level of gene transcription and alternative splicing that guide cell transition from ESCs into cardiomyocytes. We are actively involved with BayGenomics, a large-scale, academic collaboration whose goal is the inactivation of all genes in murine ESCs (www.genetrap.org). The effects of this approach have been demonstrated in a recent study that showed that genetic alterations (AKAP-10 trap) in ESC-derived cardiac myocytes alter the electrical responses to hormones, such as acetylcholine, in a phenotype that was reproduced in mice derived from these ES cells. Additionally, these studies have enabled us to positively identify a common genetic variation in AKAP-10 that is believed to control basal heart rate, a known risk factor for sudden cardiac death. As we move forward with our research, we will continue to focus on studies that have synergy between ES cell biology, mouse genetics and human genetics.
The efforts of our pathway-oriented bioinformatics team have produced a free, publicly distributed software package, GenMAPP (Gene Map Annotator and Pathway Profiler). GenMAPP is now used by researchers world-wide, with over 16,000 unique registrations in 40 countries, and more than 300 publications citing the program. We are in the process of expanding this open source program in order to provide comprehensive genome-wide, pathway-oriented analysis for twenty species and all types of functional genomic data, including genetic variation and disease association studies, in an effort to provide more complete analysis of the data collected in functional genomic experiments. For a more detailed description and additional information regarding this program, please visit our websites:www.GenMAPP.org and www.wikipathways.org
Some questions addressed in ongoing studies:
- What are the GPCR signals that drive growth and differentiation of ES cells into cardiac myocytes, bone, endocrine and other cell types?
- What are the drugs that can be used to control adult cardiac function via GPCRs?
- How can whole-genome SNP and expression data be best visualized in the context of biological pathways in order to provide insights into human disease?