The palmitoylation of the N-terminal extracellular Cys37 mediates the nuclear translocation of VPAC1 contributing to its anti-apoptotic activity
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Rongjie Yu1,2, Hongyu Liu1,2, Xinhe Peng1,2, Yue Cui1,2, Suqin Song1,2, Like Wang1,2, Huahua Zhang3, An Hong1,2 and Tianhong Zhou4
1Institute of Biomedicine, School of Life Science and Technology, Jinan University, Guangzhou, Guangdong, China
2National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou, Guangdong, China
3Department of Medical Genetics, Guangdong Medical University, Dongguan, Guangdong, China
4Department of Bioengineering, School of Life Science and Technology, Jinan University, Guangzhou, Guangdong, China
Rongjie Yu, email: email@example.com
Keywords: vasoactive intestinal peptide receptor 1 (VPAC1), cysteine (Cys), palmitoylation, nuclear translocation, anti-apoptotic activity
Received: March 06, 2017 Accepted: April 14, 2017 Published: April 27, 2017
VPAC1 is class B G protein-coupled receptors (GPCR) shared by pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP). The first cysteine (Cys37) in the N-terminal extracellular domain of mature VPAC1 is a free Cys not involved in the formation of conserved intramolecular disulfide bonds. In order to investigate the biological role of this Cys37 in VPAC1, the wild-type VPAC1 and Cys37/Ala mutant (VPAC1-C37/A) were expressed stably as fusion proteins with enhanced yellow fluorescent protein (EYFP) respectively in Chinese hamster ovary (CHO) cells. Both VPAC1-EYFP and VPAC1-C37/A-EYFP trafficked to the plasma membrane normally, and CHO cells expressing VPAC1-EYFP displayed higher anti-apoptotic activity against camptothecin (CPT) induced apoptosis than the cells expressing VPAC1-C37/A-EYFP, while VPAC1-C37/A-CHO cells showed higher proliferative activity than VPAC1-CHO cells. Confocal microscopic analysis, western blotting and fluorescence quantification assay showed VPAC1-EYFP displayed significant nuclear translocation while VPAC1-C37/A-EYFP did not transfer into nucleus under the stimulation of VIP (0.1 nM). Acyl-biotin exchange assay and click chemistry-based palmitoylation assay confirmed for the first time the palmitoylation of Cys37, which has been predicted by bioinformatics analysis. And the palmitoylation inhibitor 2-bromopalmitate significantly inhibited the nuclear translocation of VPAC1-EYFP and its anti-apoptotic activity synchronously. These results indicated the palmitoylation of the Cys37 in the N-terminal extracellular domain of VPAC1 mediates the nuclear translocation of VPAC1 contributing to its anti-apoptotic activity. These findings reveal for the first time the lipidation-mediating nuclear translocation of VPAC1 produces a novel anti-apoptotic signal pathway, which may help to promote new drug development strategy targeting VPAC1.
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