More therapeutic drugs target G-protein-coupled receptors (GPCRs) than any other family of proteins. G proteins transduce signals initiated at the cell surface through interactions with GPCRs at the plasma membrane (PM). The long term objective of this research is to identify new G protein interactions that can serve as targets for novel therapeutic agents. G protein heterotrimers consist of alpha, beta, and gamma subunits. Upon G protein activation at the PM, the alpha subunit and beta-gamma dimer both activate downstream signaling cascades. Traditionally, both were thought to remain on the PM during this process. Recently, it was discovered that beta-gamma dimers can move off the PM and translocate to the Golgi and endoplasmic reticulum (ER), with targeting and rates that depend on the specific gamma subunit type. These findings call for a better understanding of the mechanisms behind the rapid and reversible movement of G protein subunits in live cells and its function in specifying a cell's response to stimulation of a GPCR. The gamma-dependent kinetics of beta-gamma translocation presents a unique tool for identifying specific G protein-receptor interactions that control translocation, as well as its physiological role. We will exploit these differential kinetics towards two specific aims.
Aim 1 : Test the hypothesis that interaction between the gamma subunit and the receptor is the primary regulator of receptor-stimulated G-beta-gamma translocation.
Aim 2 : Test the hypothesis that G-beta-gamma translocation to the endoplasmic reticulum (ER) targets inositol trisphosphate receptors and regulates calcium release. These experiments will test the evidence-based hypothesis that gamma subunits contribute to the specificity of G protein signaling by regulating movement of beta-gamma dimers throughout cell following activation of a GPCR. The findings from the experiments have the potential to identify specific interactions between gamma subunits and receptors that can be targeted to alter the initial events in G protein signaling cascades. Controlling these early events will be important in the treatment of a large number of cell signaling related diseases.

Public Health Relevance

G proteins regulate most of the cell signaling pathways targeted in the treatment of human disease. This research will identify new interactions in G protein signaling that will be important targets for novel therapeutics.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32GM099351-03
Application #
8502709
Study Section
Special Emphasis Panel (ZRG1-F05-A (20))
Program Officer
Reddy, Michael K
Project Start
2011-08-01
Project End
2014-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
3
Fiscal Year
2013
Total Cost
$53,942
Indirect Cost
Name
Washington University
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Karunarathne, W K Ajith; O'Neill, Patrick R; Gautam, Narasimhan (2015) Subcellular optogenetics - controlling signaling and single-cell behavior. J Cell Sci 128:15-25
O'Neill, Patrick R; Gautam, N (2014) Subcellular optogenetic inhibition of G proteins generates signaling gradients and cell migration. Mol Biol Cell 25:2305-14
O'Neill, Patrick R; Giri, Lopamudra; Karunarathne, W K Ajith et al. (2014) The structure of dynamic GPCR signaling networks. Wiley Interdiscip Rev Syst Biol Med 6:115-23
Ajith Karunarathne, W K; O'Neill, Patrick R; Martinez-Espinosa, Pedro L et al. (2012) All G protein ?? complexes are capable of translocation on receptor activation. Biochem Biophys Res Commun 421:605-11