Our Research | Dohlman Lab

Mechanisms of Cell Desensitization: Regulators of G protein Signaling

Research in the Dohlman Lab is focused on G proteins and G protein-coupled receptors (GPCRs). These receptors are the target for two-thirds of hormones and neurotransmitters, many pharmaceuticals, and most environmental signals. Generally speaking, persistent stimulation of G proteins leads to desensitization. Familiar examples include desensitization to light, odors and drugs of abuse, including opioids.

The research strategy relies on large-scale genomic, proteomic, and metabolomic analysis to identify G protein variants with altered signaling and desensitization properties. Mutants are then characterized biochemically and in cells. This effort led to the identification of the first RGS protein, which inactivates G proteins by accelerating their intrinsic GTPase activity. The lab was also the first to use mass spectrometry to map a site of protein ubiquitination in vivo, and the first to demonstrate signaling by G proteins at internal cellular compartments.

Mutations in G proteins are responsible for disease; the best-known examples are uveal melanoma and developmental epileptic encephalopathies. The lab is currently investigating how these disease mutations impose an ensemble of conformational states on the G protein α subunit, and how these states differ among the four major subclasses of Gα subtypes. Following a systematic analysis of mutations in Gα_o, all linked to epileptic encephalopathies, the lab identified several that block or lock key steps of the G protein activation cycle. Most of the mutations act at a distance, by imposing or disrupting important allosteric communication networks. These studies are revealing new ways by which G proteins are activated and desensitized. In the longer term it is likely that specific conformational states can be imposed by using existing approved drugs that target GPCRs.

SELECTED PUBLICATIONS

Knight, K. M., Krumm, B. E., Kapolka, N. J., Ludlam, W. G., Cui, M., Mani, S., Prytkova, I., Obarow, E. G., Lefevre, T. J., Wei, W., Ma, N., Huang, X-P., Fay, J. F., Vaidehi, N., Smrcka, A. V., Slesinger, P. A., Logothetis, D. E., Martemyanov, K. A., Roth, B. L., and Dohlman, H. G., A neurodevelopmental disorder mutation locks G proteins in the transitory pre-activated state. Nature Communications, 15, 6643. doi.org/10.1038/s41467-024-50964-z2024, 2024.
Knight, K. M., Obarow, E. G., Wei, W., Mani, S., Esteller, M. I., Cui, M., Ma, N., Martin, S. A., Brinson, E., Hewitt, N., Soden, G. M., Logothetis, D. E., Vaidehi, N., Dohlman, H. G., Molecular annotation of G protein variants in a neurological disorder. Cell Reports, 42:113462, 2023.
Hewitt, N., Ma, N., Arang, N., Martin, S. A., Prakash, A., DiBerto, J. F., Knight, K. M., Ghosh, S., Olsen, R. H. J., Roth, B. L., Gutkind, J. S., Vaidehi, N., Campbell, S. L., and Dohlman, H. G., Catalytic-site mutations confer multiple states of G protein activation. Science Signaling, 16:771:eabq7842, 2023.
Knight, K. M., Ghosh, S., Campbell, S. L., Lefevre, T., Olsen, R. H. J., Smrcka, A. V., Valentin, H. V., Yin, G., Vaidehi, N., and Dohlman, H. G., A universal allosteric mechanism for G protein activation. Molecular Cell, 81:1-13, 2021.
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 8:359:ra5, 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.
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.
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
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.