Mechanisms of Cell Desensitization: Regulators of G protein Signaling
The Dohlman lab has for 25+ years invested in the education and training of new research scientists. We welcome individuals from diverse backgrounds, many of whom bring new perspectives to the research endeavor. Most of all we strive to promote a culture of cooperation and shared responsibility. In 2019 Dr. Dohlman was awarded the Office of Graduate Education Excellence in Basic Science Mentoring Award.
The lab’s research is centered on G proteins and G protein-coupled receptors (GPCRs). GPCRs respond to hormones and neurotransmitters, and are the target of one third of all pharmaceuticals. Generally speaking, persistent stimulation of these receptors leads to desensitization. Familiar examples include desensitization to light, odors and chemical stimulants such as caffeine.
Receptors, G proteins, and effector MAP kinases are conserved in evolution and are even found in the simplest eukaryotes such as yeast. The lab has long been conducting large-scale genomic and proteomic analysis in yeast to identify mutants with altered signaling and desensitization properties. These mutants are then characterized biochemically in yeast as well as in animal cells using homologous components. This approach led to the identification and characterization of the first RGS proteins (Dohlman et al. Mol Cell Biol 1995). RGS proteins inactivate G proteins by accelerating their intrinsic GTPase activity. Thus, RGS proteins work in opposition to GPCRs and serve as the molecular ‘brakes’ in cellular responses to neurotransmitters, environmental signals, and many pharmaceuticals.
Efforts in collaboration with Tim Elston‘s systems biology group seek to construct computational models of signaling networks and pathways; a long term objective is to devise predictive models of signal transduction in more complex systems, and ultimately determine how specific stimuli or drugs will influence the signaling network, in addition to specific target enzymes or receptors.
Apart from RGS proteins, the lab has pioneered the use of mass spectrometry to map sites of ubiquitination (Marotti et al. Biochemistry 2002), demonstrated endomembrane signaling by G proteins (Slessareva, et al. Cell 2006), and showed that physiological changes in intracellular pH (Isom et al. Mol Cell 2013) as well as 2-hydroxy branched chain amino acids (Shellhammer et al. PLoS Genetics 2017) serve as second messengers of glucose limitation and osmotic stress, respectively. These novel second messengers share the ability to trigger G protein phosphorylation and dampen signaling. 2-hydroxy branched chain amino acids are elevated in patients with maple syrup urine disease and cause defects in neurotransmitter function.
- English, J. G., Shellhammer, J. P., Malahe, M., McCarter, P. C., Elston, T. C. and Dohlman, H. G., MAPK feedback encodes a switch and timer for tunable stress adaptation in yeast. Science Signaling 8:ra5, 2015.
- Schrage, R., et al. (45 additional authors), A plant-derived peptide to explore the role of Gq proteins in biological systems, Nature Communications, 6:10156, 2015.
- Isom, D. G. and Dohlman, H. G., Buried ionizable networks are an ancient hallmark of G protein-coupled receptor activation. Proceedings of the National Academies of Sciences USA, 112:5702-7. 2015.
- Dixit, G., Kelley, J. B., Houser, J. R., Elston, T. C. and Dohlman, H. G., Cellular noise suppression by the regulator of G protein signaling Sst2. Molecular Cell 55:85-96, 2014.
- Isom, D. G., Sridharan, V., Baker, R., Clement, S. T., Smalley, D. M. and Dohlman, H. G., Protons as second messenger regulators of G protein signaling. Molecular Cell 51:531-538, 2013.
- Clement, S. T., Dixit, G. and Dohlman, H. G., Regulation of yeast G protein signaling by the kinases that activate the AMPK homolog Snf1.Science Signaling 6:ra78, 2013.
- Baker, R., Lewis, S. M., Wilkerson, E. M., Sasaki, A. T., Cantley, L. C., Kuhlman, B., Dohlman, H. G. and Campbell, S. L., Site-specific monoubiquitination activates Ras by impeding GTPase activating protein function. Nature Structural & Molecular Biology 20:46-52, 2013.
- Jones, J. C., Jones, A. M., Temple, B. R. S. and Dohlman, H. G., Differences in intradomain and interdomain motion confer distinct activation properties to structurally similar Ga proteins. Proceedings of the National Academies of Sciences USA 109:7275-9, 2012.
- Jin, M., Errede, B., Behar, M., Mather, W., Nayak, S., Hasty, J., Dohlman H. G. and Elston, T. C., Yeast dynamically modify their environment to achieve better mating efficiency. Science Signaling 4:ra54, 2011.
- Jones, J. C., Duffy, J. W., Machius, M., Temple, B. R. S., Dohlman, H. G. and Jones, A. M., The crystal structure of a self-activating G protein a-subunit reveals its distinct mechanism of signal initiation. Science Signaling 4:ra8, 2011.
- Cappell, S. D., Baker, R., Skowyra, D. and Dohlman, H. G., Systematic analysis of essential genes reveals important regulators of G protein signaling. Molecular Cell 38:746-57, 2010.
- Hao, N., Nayak, S., Behar, M., Shanks, R. H., Nagiec, M. J., Errede, B., Hasty, J., Elston, T. C. and Dohlman, H. G., Regulation of cell signaling dynamics by the protein kinase-scaffold Ste5. Molecular Cell 30:649-56, 2008.
- Behar, M., Dohlman, H. G. and Elston, T. C. From the Cover: Kinetic insulation as an effective mechanism for achieving pathway specificity in intracellular signaling networks. Proceedings of the National Academy of Sciences USA104:16146-51, 2007.
- Slessareva, J. E., Routt S. M., Temple, B., Bankaitis, V. A. and Dohlman, H. G., Activation of the phosphatidylinositol 3-kinase Vps34 by a G protein a subunit at the endosome. Cell 126:191-203, 2006.
- Ballon, D. R., Flanary, P. L., Gladue, D. P., Konopka, J. B., Dohlman, H. G. and Thorner, J., DEP-domain-mediated regulation of GPCR signaling responses. Cell 126:1079-93, 2006
- Guo, M., Aston, C., Burchett, S. A., Dyke, C., Fields, S., Rajarao, S. J. R., Uetz, P, Wang, Y., Young, K. and Dohlman, H. G., The yeast G protein a subunit Gpa1 transmits a signal through an RNA-binding effector protein Scp160. Molecular Cell 12:517-24, 2003.
- Ehrhard, K., Jacoby, J. J., Fu, X-Y., Jahn, R. and Dohlman, H. G., Use of G protein fusions to monitor integral membrane protein-protein interactions in yeast. Nature Biotechnology 18:1075-9, 2000.
- King, K. K., Dohlman, H. G., Thorner, J., Caron, M. G. and Lefkowitz, R. J., Control of yeast mating signal transduction by a mammalian beta2-adrenergic receptor and Gs alpha subunit. Science 250:121-3, 1990.
- Dixon, R. A. F., Kobilka, B. K., Strader, D. J., Benovic, J. L., Dohlman, H. G., Frielle, T., Bolanowski, M. A., Bennett, C. D., Rands, E., Diehl, R. E., Mumford, R. A., Slater, E. E., Sigal, I. S., Caron, M. G., Lefkowitz, R. J. and Strader, C. D., Cloning of the gene and cDNA for mammalian beta-adrenergic receptor and homology with rhodopsin. Nature 321:75-9, 1986.