?1D-adrenergic receptors (ARs) are essential G protein-coupled receptors (GPCRs) of the sympathetic nervous system, and are a promising therapeutic target for an array of diseases. In the central nervous system, the ?1D- AR tightly regulates stimulus-induced locomotor activity, and is 1 of 13 hypermethylated genes associated with decreased brain volume in schizophrenic patients. The ?1D-AR is critical for blood pressure regulation and stenosis of damaged blood vessels; and negatively impacts urine flow by contracting the prostate in patients suffering from benign prostatic hypertrophy (BPH). Thus, ?1-AR antagonists (??-blockers?) are often used to treat hypertension, urinary incontinence, and most recently with promising success, to prevent reoccurring nightmares in combat veterans afflicted with Post-Traumatic Stress Disorder. Unfortunately, major toxicities can often occur in patients taking ?-blockers. During the ALLHAT trial, ?-blocker therapy was discontinued due to increased patient morbidity. Accordingly, a clearer picture of how the ?1D-AR engages with its cellular environment will provide critical insights towards the further development of small molecule ?1D-AR modulators beneficial for the treatment of PTSD, BPH, and cardiovascular disease. Surprisingly, our basic knowledge of ?1D-AR biochemical processes is lacking within human contexts, primarily because no human cell lines have been identified that express endogenous ?1D-ARs. Without adequate cell culture models and human model cell systems to examine their discrete biochemical interactions, it will continue to be challenging to develop new small molecules targeting ?1D-ARs and to understand their essential molecular and cellular functions. We have made significant progress towards solving some of these mysteries. First, we discovered that ?1D-ARs interact with multiple PSD95/DLG1/Zo-1 (PDZ) domain-containing proteins. Second, we found these interactions are essential for ?1D-ARs to be expressed as functional receptors at the plasma membrane. Remarkably, we found that ?1D-ARs interact with two PDZ-proteins, syntrophin and scribble, in all human cell lines we examined. This novel discovery provides an opportunity to develop small molecule allosteric ligands targeting ?1D-AR:PDZ- protein interaction-interfaces. However, this first requires a thorough characterization of ?1D-AR:PDZ-protein architecture and function. The initial aims we that were proposed were the following:
Aim 1 : Determine whether scribble organizes ?1D-ARs into signaling clusters.
Aim 2 : Identify ?1D-AR:PDZ-protein complex(es) in human cells.
This proposal will be used to obtain cutting-edge cell imaging equipment that can be used to identify cellular mechanisms responsible for trafficking and degrading membrane proteins. This approach can be used as a basis for obtaining information that will spur the development of drugs with novel mechanisms of action for treating human disease.
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| Kountz, Timothy S; Lee, Kyung-Soon; Aggarwal-Howarth, Stacey et al. (2016) Endogenous N-terminal Domain Cleavage Modulates ?1D-Adrenergic Receptor Pharmacodynamics. J Biol Chem 291:18210-21 |
| Camp, Nathan D; Lee, Kyung-Soon; Cherry, Allison et al. (2016) Dynamic mass redistribution reveals diverging importance of PDZ-ligands for G protein-coupled receptor pharmacodynamics. Pharmacol Res 105:13-21 |
| Camp, Nathan D; Lee, Kyung-Soon; Wacker-Mhyre, Jennifer L et al. (2015) Individual protomers of a G protein-coupled receptor dimer integrate distinct functional modules. Cell Discov 1: |
