The ? opioid receptor (KOPR) is one of the three major types (?, ? and ?) of opioid receptors that mediate effects of opioids in vivo. Activation of KOPR produces analgesia, dysphoria, water diuresis, hypothermia and modulation of immune responses. KOPR antagonists may be potentially useful for curbing cocaine craving and as anti-depressants and anti-anxiety agents. KOPR, a member of the 7TMR family, is coupled through pertussis toxin-sensitive G proteins to a variety of effectors. For 7TMRs. the capacity of agonists to modulate downstream signaling molecules depends on the availability of the receptors on cell surface. The number of cell surface 7TMRs reflects a balance between biosynthesis and endocytosis pathways. The post-activation endocytic events have been well-documented;however, regulation along the biosynthesis pathway is much less understood. The focus of this grant application is to characterize the regulation of the KOPR trafficking along the biosynthesis pathway, in particular by the proteins GEC1, sortilin and 14-3-3 proteins, which we found to interact with the KOPR and to be involved in KOPR export trafficking. The central hypothesis is that the export trafficking is regulated by molecules interacting with the KOPR.
The specific aims are as follows. (1) To delineate mechanisms underlying GEC1-promoted expression and trafficking of the KOPR. The hypothesis that GEC1 enhances KOPR expression by enhancing ATPase activity of NSF, but not by membrane association by lipid conjugation will be tested. (2) To investigate the role of 14-3-3 in the trafficking and cellular pharmacology of the KOPR. The hypothesis is that 14-3-3 proteins bind to KOPR C-terminal domain and/or i3 loop, which masks COPI binding, allowing the KOPR to sort to plasma membranes. (3) To examine the interaction of the KOPR with sortilin and its functional consequences. The hypothesis to be tested is that sortilin binding to the KOPR sorts the receptor to endosomes and lysosomes and this represents a novel post-ER quality control mechanism. We will also examine if the interactions of the KOPR with these proteins affect signaling and regulation. The proposed studies will provide better understanding of cell biology of the KOPR and provide mechanistic insights into regulation of export of the KOPR. In addition, such understanding will have important implications for other membrane bound receptors since these regulatory mechanisms of export are likely to be applicable to some other proteins.
Program narrative The proposed research will provide better understanding on how cell surface receptor numbers are regulated, which play important roles in response to external stimuli, including drugs and neurotransmitters.
|Dimattio, K M; Yakovleva, T V; Aldrich, J V et al. (2014) Zyklophin, a short-acting kappa opioid antagonist, induces scratching in mice. Neurosci Lett 563:155-9|
|Huang, Peng; Chiu, Yi-Ting; Chen, Chongguang et al. (2013) A G protein-coupled receptor (GPCR) in red: live cell imaging of the kappa opioid receptor-tdTomato fusion protein (KOPR-tdT) in neuronal cells. J Pharmacol Toxicol Methods 68:340-5|
|Xu, Wei; Chen, Chongguang; Li, Jian-Guo et al. (2013) PKA and ERK1/2 are involved in dopamine Dýýý receptor-induced heterologous desensitization of the ýý opioid receptor. Life Sci 92:1101-9|
|Xu, Wei; Wang, Yujun; Ma, Zhongze et al. (2013) L-isocorypalmine reduces behavioral sensitization and rewarding effects of cocaine in mice by acting on dopamine receptors. Drug Alcohol Depend 133:693-703|
|Wang, Y-J; Huang, P; Ung, A et al. (2012) Reduced expression of the mu opioid receptor in some, but not all, brain regions in mice with OPRM1 A112G. Neuroscience 205:178-84|
|Woodruff-Pak, Diana S; Lehr, Melissa A; Li, Jian-Guo et al. (2010) Young and older good learners have higher levels of brain nicotinic receptor binding. Neurobiol Aging 31:1032-43|
|Huang, Peng; Liu-Chen, Lee-Yuan; Kirby, Lynn G (2010) Anxiety-like effects of SR141716-precipitated delta9-tetrahydrocannabinol withdrawal in mice in the elevated plus-maze. Neurosci Lett 475:165-8|
|Beguin, Cecile; Duncan, Katharine K; Munro, Thomas A et al. (2009) Modification of the furan ring of salvinorin A: identification of a selective partial agonist at the kappa opioid receptor. Bioorg Med Chem 17:1370-80|
|Mague, Stephen D; Isiegas, Carolina; Huang, Peng et al. (2009) Mouse model of OPRM1 (A118G) polymorphism has sex-specific effects on drug-mediated behavior. Proc Natl Acad Sci U S A 106:10847-52|
|Huang, Peng; Liu-Chen, Lee-Yuan; Unterwald, Ellen M et al. (2009) Hyperlocomotion and paw tremors are two highly quantifiable signs of SR141716-precipitated withdrawal from delta9-tetrahydrocannabinol in C57BL/6 mice. Neurosci Lett 465:66-70|
Showing the most recent 10 out of 33 publications