1
|
Guo J, Kong Z, Yang S, Da J, Chu L, Han G, Liu J, Tan Y, Zhang J. Therapeutic effects of orexin-A in sepsis-associated encephalopathy in mice. J Neuroinflammation 2024; 21:131. [PMID: 38760784 PMCID: PMC11102217 DOI: 10.1186/s12974-024-03111-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 04/25/2024] [Indexed: 05/19/2024] Open
Abstract
BACKGROUND Sepsis-associated encephalopathy (SAE) causes acute and long-term cognitive deficits. However, information on the prevention and treatment of cognitive dysfunction after sepsis is limited. The neuropeptide orexin-A (OXA) has been shown to play a protective role against neurological diseases by modulating the inflammatory response through the activation of OXR1 and OXR2 receptors. However, the role of OXA in mediating the neuroprotective effects of SAE has not yet been reported. METHODS A mouse model of SAE was induced using cecal ligation perforation (CLP) and treated via intranasal administration of exogenous OXA after surgery. Mouse survival, in addition to cognitive and anxiety behaviors, were assessed. Changes in neurons, cerebral edema, blood-brain barrier (BBB) permeability, and brain ultrastructure were monitored. Levels of pro-inflammatory factors (IL-1β, TNF-α) and microglial activation were also measured. The underlying molecular mechanisms were investigated by proteomics analysis and western blotting. RESULTS Intranasal OXA treatment reduced mortality, ameliorated cognitive and emotional deficits, and attenuated cerebral edema, BBB disruption, and ultrastructural brain damage in mice. In addition, OXA significantly reduced the expression of the pro-inflammatory factors IL-1β and TNF-α, and inhibited microglial activation. In addition, OXA downregulated the expression of the Rras and RAS proteins, and reduced the phosphorylation of P-38 and JNK, thus inhibiting activation of the MAPK pathway. JNJ-10,397,049 (an OXR2 blocker) reversed the effect of OXA, whereas SB-334,867 (an OXR1 blocker) did not. CONCLUSION This study demonstrated that the intranasal administration of moderate amounts of OXA protects the BBB and inhibits the activation of the OXR2/RAS/MAPK pathway to attenuate the outcome of SAE, suggesting that OXA may be a promising therapeutic approach for the management of SAE.
Collapse
Affiliation(s)
- Jing Guo
- GuiZhou University Medical College, Guiyang, 550025, Guizhou Province, China
| | - Zhuo Kong
- Department of Neurosurgery, Guizhou Provincial People's Hospital, Guiyang, China
| | - Sha Yang
- GuiZhou University Medical College, Guiyang, 550025, Guizhou Province, China
| | - Jingjing Da
- Department of Nephrology, Guizhou Provincial People's Hospital, Guiyang, China
| | - Liangzhao Chu
- Department of Neurosurgery, the Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Guoqiang Han
- Department of Neurosurgery, Guizhou Provincial People's Hospital, Guiyang, China
| | - Jian Liu
- Department of Neurosurgery, Guizhou Provincial People's Hospital, Guiyang, China.
| | - Ying Tan
- Department of Neurosurgery, Guizhou Provincial People's Hospital, Guiyang, China.
| | - Jiqin Zhang
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guiyang, China.
| |
Collapse
|
2
|
Sekste EA, Lebedev AA, Bychkov ER, Airapetov MI, Gramota KE, Thyssen IY, Shabanov PD. [Increase in the level of orexin receptor 1 (OX1R) mRNA in the brain structures of rats prone to impulsivity in behavior]. BIOMEDITSINSKAIA KHIMIIA 2021; 67:411-417. [PMID: 34730554 DOI: 10.18097/pbmc20216705411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Orexin and its receptors are involved in the mechanisms of pathological craving for alcohol and psychoactive drugs. The orexin system is also involved in the mechanisms of non-chemical forms of addiction: binge eating and gambling. The aim of this work was to study the level of orexin receptor mRNA in the hypothalamus, hippocampus, and prefrontal cortex of rats prone to impulsivity in behavior in a model for studying the elements of gambling addiction (a variant of the Iowa Gambling Task test). Brain structures were isolated on the 22nd day of the experiment. The expression of the OX1R gene was higher in the hypothalamus by 122% and in the hippocampus by 149% in rats that preferred to receive a high reward, but with a low probability as compared with a group of animals that preferred a low level of reinforcement, but with a 100% probability. In the prefrontal cortex, on the contrary, no significant changes were observed in the level of OX1R mRNA. The level of OX2R mRNA insignificantly changed in the hypothalamus, hippocampus, and prefrontal cortex of rats prone to impulsivity in behavior. The data indicate involvement of OX1R in the hypothalamus and hippocampus in mechanisms mediating impulsive behavior and the choice of the significance of positive reinforcement in terms of its varying strength and probability.
Collapse
Affiliation(s)
- E A Sekste
- Institute of Experimental Medicine, St. Petersburg, Russia
| | - A A Lebedev
- Institute of Experimental Medicine, St. Petersburg, Russia
| | - E R Bychkov
- Institute of Experimental Medicine, St. Petersburg, Russia
| | - M I Airapetov
- Institute of Experimental Medicine, St. Petersburg, Russia; St. Petersburg State Medical Pediatric University, St. Petersburg, Russia
| | - K E Gramota
- Institute of Experimental Medicine, St. Petersburg, Russia
| | - I Yu Thyssen
- Institute of Experimental Medicine, St. Petersburg, Russia
| | - P D Shabanov
- Institute of Experimental Medicine, St. Petersburg, Russia; Kirov Military Medical Academy, St. Petersburg, Russia
| |
Collapse
|
3
|
Yaeger JD, Krupp KT, Gale JJ, Summers CH. Counterbalanced microcircuits for Orx1 and Orx2 regulation of stress reactivity. MEDICINE IN DRUG DISCOVERY 2020. [DOI: 10.1016/j.medidd.2020.100059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
|
4
|
Chen J, Chen X, Li S, Jiang Y, Mao H, Zhang R, Ji B, Yan M, Cai X, Wang C. Individual phosphorylation sites at the C-terminus of the apelin receptor play different roles in signal transduction. Redox Biol 2020; 36:101629. [PMID: 32863206 PMCID: PMC7338617 DOI: 10.1016/j.redox.2020.101629] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/24/2020] [Accepted: 06/29/2020] [Indexed: 12/16/2022] Open
Abstract
The apelin and Elabela proteins constitute a spatiotemporal double-ligand system that controls apelin receptor (APJ) signal transduction. Phosphorylation of multiple sites within the C-terminus of APJ is essential for the recruitment of β-arrestins. We sought to determine the precise mechanisms by which apelin and Elabela promote APJ phosphorylation, and to elucidate the influence of β-arrestin phosphorylation on G-protein-coupled receptor (GPCR)/β-arrestin-dependent signaling. We used techniques including mass spectrometry (MS), mutation analysis, and bioluminescence resonance energy transfer (BRET) to evaluate the role of phosphorylation sites in APJ-mediated G-protein-dependent and β-dependent signaling. Phosphorylation of APJ occurred at five serine residues in the C-terminal region (Ser335, Ser339, Ser345, Ser348 and Ser369). We also identified two phosphorylation sites in β-arrestin1 and three in β-arrestin2, including three previously identified residues (Ser412, Ser361, and Thr383) and two new sites, Tyr47 in β-arrestin1 and Tyr48 in β-arrestin2. APJ mutations did not affect the phosphorylation of β-arrestins, but it affects the β-arrestin signaling pathway, specifically Ser335 and Ser339. Mutation of Ser335 decreased the ability of the receptor to interact with β-arrestin1/2 and AP2, indicating that APJ affects the β-arrestin signaling pathway by stimulating Elabela. Mutation of Ser339 abolished the capability of the receptor to interact with GRK2 and β-arrestin1/2 upon stimulation with apelin-36, and disrupted receptor internalization and β-arrestin-dependent ERK1/2 activation. Five peptides act on distinct phosphorylation sites at the APJ C-terminus, differentially regulating APJ signal transduction and causing different biological effects. These findings may facilitate screening for drugs to treat cardiovascular and metabolic diseases.
Collapse
Affiliation(s)
- Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom.
| | - Xiaoyu Chen
- Department of Physiology, Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, Shandong, China
| | - Sheng Li
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| | - Huiling Mao
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| | - Bingyuan Ji
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| | - Maocai Yan
- School of Pharmacy, Jining Medical University, Shandong, China
| | - Xin Cai
- Department of Physiology, Weifang Medical University, Weifang, Shandong, China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, China
| |
Collapse
|
5
|
Li T, Xu W, Ouyang J, Lu X, Sherchan P, Lenahan C, Irio G, Zhang JH, Zhao J, Zhang Y, Tang J. Orexin A alleviates neuroinflammation via OXR2/CaMKKβ/AMPK signaling pathway after ICH in mice. J Neuroinflammation 2020; 17:187. [PMID: 32539736 PMCID: PMC7294616 DOI: 10.1186/s12974-020-01841-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 05/14/2020] [Indexed: 02/07/2023] Open
Abstract
Background Orexins are two neuropeptides (orexin A, OXA; orexin B, OXB) secreted mainly from the lateral hypothalamus, which exert a wide range of physiological effects by activating two types of receptors (orexin receptor 1, OXR1; orexin receptor 2, OXR2). OXA has equal affinity for OXR1 and OXR2, whereas OXB binds preferentially to OXR2. OXA rapidly crosses the blood-brain barrier by simple diffusion. Many studies have reported OXA’s protective effect on neurological diseases via regulating inflammatory response which is also a fundamental pathological process in intracerebral hemorrhage (ICH). However, neuroprotective mechanisms of OXA have not been explored in ICH. Methods ICH models were established using stereotactic injection of autologous arterial blood into the right basal ganglia of male CD-1 mice. Exogenous OXA was administered intranasally; CaMKKβ inhibitor (STO-609), OXR1 antagonist (SB-334867), and OXR2 antagonist (JNJ-10397049) were administered intraperitoneally. Neurobehavioral tests, hematoma volume, and brain water content were evaluated after ICH. Western blot and ELISA were utilized to evaluate downstream mechanisms. Results OXA, OXR1, and OXR2 were expressed moderately in microglia and astrocytes and abundantly in neurons. Expression of OXA decreased whereas OXR1 and OXR2 increased after ICH. OXA treatment significantly improved not only short-term but also long-term neurofunctional outcomes and reduced brain edema in ipsilateral hemisphere. OXA administration upregulated p-CaMKKβ, p-AMPK, and anti-inflammatory cytokines while downregulated p-NFκB and pro-inflammatory cytokines after ICH; this effect was reversed by STO-609 or JNJ-10397049 but not SB-334867. Conclusions OXA improved neurofunctional outcomes and mitigated brain edema after ICH, possibly through alleviating neuroinflammation via OXR2/CaMKKβ/AMPK pathway.
Collapse
Affiliation(s)
- Tao Li
- Department of Neurosurgery, The First People's Hospital of Yunnan Province (Kunhua Hospital/The Affiliated Hospital of Kunming University of Science and Technology), Yunnan, 650032, China.,Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA.,Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang, 310009, Hangzhou, China
| | - Weilin Xu
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA.,Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang, 310009, Hangzhou, China
| | - Jinsong Ouyang
- Department of Neurosurgery, The First People's Hospital of Yunnan Province (Kunhua Hospital/The Affiliated Hospital of Kunming University of Science and Technology), Yunnan, 650032, China
| | - Xiaoyang Lu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang, 310009, Hangzhou, China
| | - Prativa Sherchan
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA
| | - Cameron Lenahan
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA.,Burrell College of Osteopathic Medicine, 3501 Arrowhead Dr, Las Cruces, NM, 88001, USA
| | - Giselle Irio
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA.,Burrell College of Osteopathic Medicine, 3501 Arrowhead Dr, Las Cruces, NM, 88001, USA
| | - John H Zhang
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA
| | - Jianhua Zhao
- Department of Neurosurgery, The First People's Hospital of Yunnan Province (Kunhua Hospital/The Affiliated Hospital of Kunming University of Science and Technology), Yunnan, 650032, China
| | - Yongfa Zhang
- Department of Neurosurgery, The First People's Hospital of Yunnan Province (Kunhua Hospital/The Affiliated Hospital of Kunming University of Science and Technology), Yunnan, 650032, China.
| | - Jiping Tang
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus St, Loma Linda, CA, 92354, USA.
| |
Collapse
|
6
|
Ji B, Shang L, Wang C, Wan L, Cheng B, Chen J. Roles for heterodimerization of APJ and B2R in promoting cell proliferation via ERK1/2-eNOS signaling pathway. Cell Signal 2020; 73:109671. [PMID: 32407761 DOI: 10.1016/j.cellsig.2020.109671] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/09/2020] [Accepted: 05/10/2020] [Indexed: 12/12/2022]
Abstract
Apelin receptor (APJ) and bradykinin B2 receptor (B2R) play an important role in many physiological processes and share multiple similar characteristics in distribution and functions in the cardiovascular system. We first identified the endogenous expression of APJ and B2R in human umbilical vein endothelial cells (HUVECs) and their co-localization on human embryonic kidney (HEK) 293 cells membrane. A suite of bioluminescence and fluorescence resonance energy transfer (BRET and FRET), proximity ligation assay (PLA), and co-immunoprecipitation (Co-IP) was exploited to demonstrate formation of functional APJ and B2R heterodimer in HUVECs and transfected cells. Stimulation with apelin-13 and bradykinin (BK) increased the phosphorylation of the endothelial nitric oxide synthase (eNOS) in HUVECs, which could be inhibited by the silencing of APJ or B2R, indicating the APJ-B2R dimer is critical for eNOS phosphorylation in HUVECs. Furthermore, the increase of NOS and extracellular signal regulated kinases1/2 (ERK1/2) phosphorylation mediated by APJ/B2R dimer can be inhibited by U0126 and U73122, respectively, suggesting that the heterodimer might activate the PLC/ERK1/2/eNOS signaling pathway, and finally leading to a significant increase in cell proliferation. Thus, we uncovered for the first time the existence of APJ-B2R heterodimer and provided a promising new target in cardiovascular therapeutics.
Collapse
Affiliation(s)
- Bingyuan Ji
- Institute of Neurobiology, School of Mental Health, Jining Medical University, Jining 272067, PR China.
| | - Liyan Shang
- Department of Nephrology, Zoucheng People's Hospital, Zoucheng 273500, China
| | - Chunmei Wang
- Institute of Neurobiology, School of Mental Health, Jining Medical University, Jining 272067, PR China
| | - Lei Wan
- Institute of Neurobiology, School of Mental Health, Jining Medical University, Jining 272067, PR China
| | - Baohua Cheng
- Institute of Neurobiology, School of Mental Health, Jining Medical University, Jining 272067, PR China
| | - Jing Chen
- Institute of Neurobiology, School of Mental Health, Jining Medical University, Jining 272067, PR China; Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK.
| |
Collapse
|
7
|
Liu C, Xue Y, Liu MF, Wang Y, Liu ZR, Diao HL, Chen L. Orexins increase the firing activity of nigral dopaminergic neurons and participate in motor control in rats. J Neurochem 2018; 147:380-394. [DOI: 10.1111/jnc.14568] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Cui Liu
- Department of Physiology; Qingdao University; Qingdao China
| | - Yan Xue
- Department of Physiology; Qingdao University; Qingdao China
| | - Mei-Fang Liu
- Department of Physiology; Qingdao University; Qingdao China
| | - Ying Wang
- Department of Physiology; Qingdao University; Qingdao China
| | - Zi-Ran Liu
- Department of Physiology; Qingdao University; Qingdao China
| | - Hui-Ling Diao
- Department of Physiology; Qingdao University; Qingdao China
| | - Lei Chen
- Department of Physiology; Qingdao University; Qingdao China
| |
Collapse
|
8
|
Xue Q, Bai B, Ji B, Chen X, Wang C, Wang P, Yang C, Zhang R, Jiang Y, Pan Y, Cheng B, Chen J. Ghrelin Through GHSR1a and OX1R Heterodimers Reveals a Gαs-cAMP-cAMP Response Element Binding Protein Signaling Pathway in Vitro. Front Mol Neurosci 2018; 11:245. [PMID: 30065627 PMCID: PMC6056640 DOI: 10.3389/fnmol.2018.00245] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 06/25/2018] [Indexed: 01/19/2023] Open
Abstract
Growth hormone secretagogue receptor 1α (GHSR1a) and Orexin 1 receptor (OX1R) are involved in various important physiological processes, and have many similar characteristics in function and distribution in peripheral tissues and the central nervous system. We explored the possibility of heterodimerization between GHSR1a and OX1R and revealed a signal transduction pathway mechanism. In this study, bioluminescence and fluorescence resonance energy transfer and co-immunoprecipitation (Co-IP) analyses were performed to demonstrate the formation of functional GHSR1a/OX1R heterodimers. This showed that a peptide corresponding to the 5-transmembrane domain of OX1R impaired heterodimer construction. We found that ghrelin stimulated GHSR1a/OX1R heterodimer cells to increase the activation of Gαs protein, compared to the cells that express GHSR1a. Stimulation of GHSR1a/OX1R heterodimers with orexin-A did not alter GPCR interactions with Gα protein subunits. GHSR1a/OX1R heterodimers induced Gαs and downstream signaling pathway activity, including increase of cAMP-response element luciferase reporter activity and cAMP levels. In addition, ghrelin induced a higher proliferation rate in SH-SY5Y cells than in controls. This suggests that ghrelin GHSR1a/OX1R heterodimers promotes an upregulation of a Gαs-cAMP-cAMP-responsive element signaling pathway in vitro and an increase in neuroblastoma cell proliferation.
Collapse
Affiliation(s)
- Qingjie Xue
- Neurobiology Institute, Jining Medical University, Jining, China.,Department of Pathogenic Biology, Jining Medical University, Jining, China
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Bingyuan Ji
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Xiaoyu Chen
- Department of Physiology, Taishan Medical University, Taian, China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Peixiang Wang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Chunqing Yang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Yanyou Pan
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Baohua Cheng
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, China.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| |
Collapse
|
9
|
Wang C, Wang Q, Ji B, Pan Y, Xu C, Cheng B, Bai B, Chen J. The Orexin/Receptor System: Molecular Mechanism and Therapeutic Potential for Neurological Diseases. Front Mol Neurosci 2018; 11:220. [PMID: 30002617 PMCID: PMC6031739 DOI: 10.3389/fnmol.2018.00220] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/06/2018] [Indexed: 12/25/2022] Open
Abstract
Orexins, also known as hypocretins, are two neuropeptides secreted from orexin-containing neurons, mainly in the lateral hypothalamus (LH). Orexins orchestrate their effects by binding and activating two G-protein–coupled receptors (GPCRs), orexin receptor type 1 (OX1R) and type 2 (OX2R). Orexin/receptor pathways play vital regulatory roles in many physiological processes, especially feeding behavior, sleep–wake rhythm, reward and addiction and energy balance. Furthermore several reports showed that orexin/receptor pathways are involved in pathological processes of neurological diseases such as narcolepsy, depression, ischemic stroke, drug addiction and Alzheimer’s disease (AD). This review article summarizes the expression patterns, physiological functions and potential molecular mechanisms of the orexin/receptor system in neurological diseases, providing an overall framework for considering these pathways from the standpoints of basic research and clinical treatment of neurological diseases.
Collapse
Affiliation(s)
- Chunmei Wang
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Qinqin Wang
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Bingyuan Ji
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Yanyou Pan
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Chao Xu
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Baohua Cheng
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Bo Bai
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China
| | - Jing Chen
- Neurobiology Key Laboratory of Jining Medical University in Colleges of Shandong, Jining Medical University, Jining, China.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| |
Collapse
|
10
|
Wang L, Kang Y, Liang S, Chen D, Zhang Q, Zeng L, Luo J, Jiang F. Synergistic effect of co-exposure to cadmium (II) and 4-n-nonylphenol on growth inhibition and oxidative stress of Chlorella sorokiniana. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 154:145-153. [PMID: 29459164 DOI: 10.1016/j.ecoenv.2018.02.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 02/03/2018] [Accepted: 02/12/2018] [Indexed: 05/22/2023]
Abstract
Toxicological effect of freshwater algae co-exposure to Cd and 4-n-nonylphenol (4-n-NP) was seldom reported. In the present study, Chlorella sorokiniana was selected for testing the single and combined effect of Cd and 4-n-NP by detecting the growth inhibition and oxidative stress after exposure for 48 h, 72 h, and 96 h. The combined effects were evaluated by using toxic units (TU) method and concentration addition(CA)model. The synergistic effect of mixture on algal growth inhibition was both observed at 48 h and 72 h, and the additive effect was observed at 96 h. In addition, the significant alterations of superoxide, thiobarbituric acid reactive substances and antioxidant defenses (superoxide dismutase, catalase, glutathione) have been detected. It could be observed that the mixture predominantly lead to synergistic effects in superoxide induction, and the antagonistic effects in the GSH induction. A similar trend between the superoxide induction and growth inhibition were observed, which may indicate that the oxidative effects of Chlorella sorokiniana contributed to the growth inhibition after exposure to Cd and 4-n-NP. These findings may have important implications in the risk assessments of heavy metals and endocrine disruptors in the aquatic environment.
Collapse
Affiliation(s)
- Lu Wang
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Yuan Kang
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China; Guangdong Engineering Technology Research Center for Drinking Water Safety, School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China.
| | - Siyun Liang
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Danying Chen
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Qiuyun Zhang
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China; Guangdong Engineering Technology Research Center for Drinking Water Safety, School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Lixuan Zeng
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China; Guangdong Engineering Technology Research Center for Drinking Water Safety, School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Jiwen Luo
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China; Guangdong Engineering Technology Research Center for Drinking Water Safety, School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| | - Feng Jiang
- School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China; Guangdong Engineering Technology Research Center for Drinking Water Safety, School of Chemistry and Environment, South China Normal University, Higher Education Mega Center, Guangzhou 510006, People's Republic of China
| |
Collapse
|
11
|
Global analysis of gene expression mediated by OX1 orexin receptor signaling in a hypothalamic cell line. PLoS One 2017; 12:e0188082. [PMID: 29145494 PMCID: PMC5690679 DOI: 10.1371/journal.pone.0188082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 10/31/2017] [Indexed: 01/23/2023] Open
Abstract
The orexins and their cognate G-protein coupled receptors have been widely studied due to their associations with various behaviors and cellular processes. However, the detailed downstream signaling cascades that mediate these effects are not completely understood. We report the generation of a neuronal model cell line that stably expresses the OX1 orexin receptor (OX1) and an RNA-Seq analysis of changes in gene expression seen upon receptor activation. Upon treatment with orexin, several families of related transcription factors are transcriptionally regulated, including the early growth response genes (Egr), the Kruppel-like factors (Klf), and the Nr4a subgroup of nuclear hormone receptors. Furthermore, some of the transcriptional effects observed have also been seen in data from in vivo sleep deprivation microarray studies, supporting the physiological relevance of the data set. Additionally, inhibition of one of the most highly regulated genes, serum and glucocorticoid-regulated kinase 1 (Sgk1), resulted in the diminished orexin-dependent induction of a subset of genes. These results provide new insight into the molecular signaling events that occur during OX1 signaling and support a role for orexin signaling in the stimulation of wakefulness during sleep deprivation studies.
Collapse
|
12
|
Thompson MD, Sakurai T, Rainero I, Maj MC, Kukkonen JP. Orexin Receptor Multimerization versus Functional Interactions: Neuropharmacological Implications for Opioid and Cannabinoid Signalling and Pharmacogenetics. Pharmaceuticals (Basel) 2017; 10:ph10040079. [PMID: 28991183 PMCID: PMC5748636 DOI: 10.3390/ph10040079] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/29/2017] [Accepted: 09/29/2017] [Indexed: 12/17/2022] Open
Abstract
Orexins/hypocretins are neuropeptides formed by proteolytic cleavage of a precursor peptide, which are produced by neurons found in the lateral hypothalamus. The G protein-coupled receptors (GPCRs) for these ligands, the OX₁ and OX₂ orexin receptors, are more widely expressed throughout the central nervous system. The orexin/hypocretin system has been implicated in many pathways, and its dysregulation is under investigation in a number of diseases. Disorders in which orexinergic mechanisms are being investigated include narcolepsy, idiopathic sleep disorders, cluster headache and migraine. Human narcolepsy has been associated with orexin deficiency; however, it has only rarely been attributed to mutations in the gene encoding the precursor peptide. While gene variations within the canine OX₂ gene hcrtr2 have been directly linked with narcolepsy, the majority of human orexin receptor variants are weakly associated with diseases (the idiopathic sleep disorders, cluster headache and polydipsia-hyponatremia in schizophrenia) or are of potential pharmacogenetic significance. Evidence for functional interactions and/or heterodimerization between wild-type and variant orexin receptors and opioid and cannabinoid receptors is discussed in the context of its relevance to depression and epilepsy.
Collapse
Affiliation(s)
- Miles D Thompson
- Department of Pediatrics, University of California, San Diego 92093, CA, USA.
| | - Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University, Kanazawa 920-8620, Japan.
| | - Innocenzo Rainero
- Department of Neuroscience, University of Turin, Torino 10124, Italy.
| | - Mary C Maj
- Department of Biochemistry, School of Medicine, Saint George's University, Saint George's 11739, Grenada.
| | - Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, Helsinki 11739, Finland.
- Department of Physiology, Institute of Biomedicine, Biomedicum Helsinki, University of Helsinki, Helsinki 00100, Finland.
| |
Collapse
|
13
|
Abstract
Orexin/hypocretin peptide (orexin-A and orexin-B) signaling is believed to take place via the two G-protein-coupled receptors (GPCRs), named OX1 and OX2 orexin receptors, as described in the previous chapters. Signaling of orexin peptides has been investigated in diverse endogenously orexin receptor-expressing cells - mainly neurons but also other types of cells - and in recombinant cells expressing the receptors in a heterologous manner. Findings in the different systems are partially convergent but also indicate cellular background-specific signaling. The general picture suggests an inherently high degree of diversity in orexin receptor signaling.In the current chapter, I present orexin signaling on the cellular and molecular levels. Discussion of the connection to (potential) physiological orexin responses is only brief since these are in focus of other chapters in this book. The same goes for the post-synaptic signaling mechanisms, which are dealt with in Burdakov: Postsynaptic actions of orexin. The current chapter is organized according to the tissue type, starting from the central nervous system. Finally, receptor signaling pathways are discussed across tissues, cell types, and even species.
Collapse
Affiliation(s)
- Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, POB 66, FIN-00014, Helsinki, Finland.
| |
Collapse
|
14
|
Dual-agonist occupancy of orexin receptor 1 and cholecystokinin A receptor heterodimers decreases G-protein–dependent signaling and migration in the human colon cancer cell line HT-29. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1153-1164. [DOI: 10.1016/j.bbamcr.2017.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 01/14/2023]
|
15
|
Cai X, Bai B, Zhang R, Wang C, Chen J. Apelin receptor homodimer-oligomers revealed by single-molecule imaging and novel G protein-dependent signaling. Sci Rep 2017; 7:40335. [PMID: 28091541 PMCID: PMC5238433 DOI: 10.1038/srep40335] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 12/05/2016] [Indexed: 12/24/2022] Open
Abstract
The apelin receptor (APJ) belongs to family A of the G protein-coupled receptors (GPCRs) and is a potential pharmacotherapeutic target for heart failure, hypertension, and other cardiovascular diseases. There is evidence APJ heterodimerizes with other GPCRs; however, the existence of APJ homodimers and oligomers remains to be investigated. Here, we measured APJ monomer-homodimer-oligomer interconversion by monitoring APJ dynamically on cells and compared their proportions, spatial arrangement, and mobility using total internal reflection fluorescence microscopy, resonance energy transfer, and proximity biotinylation. In cells with <0.3 receptor particles/μm2, approximately 60% of APJ molecules were present as dimers or oligomers. APJ dimers were present on the cell surface in a dynamic equilibrium with constant formation and dissociation of receptor complexes. Furthermore, we applied interference peptides and MALDI-TOF mass spectrometry to confirm APJ homo-dimer and explore the dimer-interfaces. Peptides corresponding to transmembrane domain (TMD)1, 2, 3, and 4, but not TMD5, 6, and 7, disrupted APJ dimerization. APJ mutants in TMD1 and TMD2 also decreased bioluminescence resonance energy transfer of APJ dimer. APJ dimerization resulted in novel functional characteristics, such as a distinct G-protein binding profile and cell responses after agonist stimulation. Thus, dimerization may serve as a unique mechanism for fine-tuning APJ-mediated functions.
Collapse
Affiliation(s)
- Xin Cai
- Department of Physiology, School of Medicine, Shandong University, Jinan, Shandong, 250012 P.R. China.,Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067 P.R. China
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067 P.R. China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067 P.R. China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067 P.R. China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067 P.R. China.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| |
Collapse
|
16
|
Zhang Y, Wu S, Song S, Lv J, Feng C, Lin X. Generation and characterization of a potentially applicable Vero cell line constitutively expressing the Schmallenberg virus nucleocapsid protein. Cytotechnology 2017; 69:145-156. [PMID: 28083834 DOI: 10.1007/s10616-016-0046-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/22/2016] [Indexed: 01/17/2023] Open
Abstract
Schmallenberg virus (SBV) is a Culicoides-transmitted orthobunyavirus that poses a threat to susceptible livestock species such as cattle, sheep and goats. The nucleocapsid (N) protein of SBV is an ideal diagnostic antigen for the detection of viral infection. In this study, a stable Vero cell line, Vero-EGFP-SBV-N, constitutively expressing the SBV-N protein was established using a lentivirus system combined with puromycin selection. This cell line spontaneously emitted green fluorescent signals distributed throughout the cytoplasm, in which the expression of SBV-N fusion protein was confirmed by western blot analysis. The expression of SBV-N protein in Vero-EGFP-SBV-N cells was stable for more than fifty passages without puromycin pressure. The SBV-N fusion protein contained both an N-terminal enhanced green fluorescent protein (EGFP) tag and a C-terminal hexa-histidine (6 × His) tag, by which the N protein was successfully purified using Ni-NTA affinity chromatography. The cell line was further demonstrated to be reactive with SBV antisera and an anti-SBV monoclonal antibody in indirect immunofluorescence assays. Taken together, our results demonstrate that the Vero-EGFP-SBV-N cell line has potential for application in the serological diagnosis of SBV infection.
Collapse
Affiliation(s)
- Yongning Zhang
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China
| | - Shaoqiang Wu
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China
| | - Shanshan Song
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China
| | - Jizhou Lv
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China
| | - Chunyan Feng
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China
| | - Xiangmei Lin
- Institute of Animal Quarantine, Chinese Academy of Inspection and Quarantine, Building No. 241 Huixinli, Chaoyang District, Beijing, 100029, China.
| |
Collapse
|
17
|
Liu H, Tian Y, Ji B, Lu H, Xin Q, Jiang Y, Ding L, Zhang J, Chen J, Bai B. Heterodimerization of the kappa opioid receptor and neurotensin receptor 1 contributes to a novel β-arrestin-2-biased pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2719-2738. [PMID: 27523794 DOI: 10.1016/j.bbamcr.2016.07.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 07/28/2016] [Accepted: 07/29/2016] [Indexed: 12/17/2022]
Abstract
Together with its endogenous ligands (dynorphin), the kappa opioid receptor (KOR) plays an important role in modulating various physiological and pharmacological responses, with a classical G protein-coupled pathway mediating analgesia and non-G protein-dependent pathway, especially the β-arrestin-dependent pathway, eliciting side effects of dysphoria, aversion, drug-seeking in addicts, or even relapse to addiction. Although mounting evidence has verified a functional overlap between dynorphin/KOR and neurotensin/neurotensin receptor 1 (NTSR1) systems, little is known about direct interaction between the two receptors. Here, we showed that KOR and NTSR1 form a heterodimer that functions as a novel pharmacological entity, and this heterodimer, in turn, brings about a switch in KOR-mediated signal transduction, from G protein-dependent to β-arrestin-2-dependent. This was simultaneously verified by analyzing a KOR mutant (196th residue) that lost the ability to dimerize with NTSR1. We also found that dual occupancy of the heterodimer forced the β-arrestin-2-dependent pathway back into Gi protein-dependent signaling, according to KOR activation. These data provide new insights into the interaction between KOR and NTSR1, and the newly discovered role of NTSR1 acting as a switch between G protein- and β-arrestin-dependent pathways of KOR also suggests a new approach for utilizing pathologically elevated dynorphin/KOR system into full play for its analgesic effect with limited side effects.
Collapse
Affiliation(s)
- Haiqing Liu
- School of Life Science, Shandong Agricultural University, Taian, Shandong 271018, PR China; Department of Physiology, Taishan Medical College, Taian, Shandong 271000, PR China.
| | - Yanjun Tian
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Bingyuan Ji
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Hai Lu
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Qing Xin
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Liangcai Ding
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Jingmei Zhang
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China; Division of Translational and Systems, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China.
| |
Collapse
|
18
|
Chen J, Zhang R, Chen X, Wang C, Cai X, Liu H, Jiang Y, Liu C, Bai B. Heterodimerization of human orexin receptor 1 and kappa opioid receptor promotes protein kinase A/cAMP-response element binding protein signaling via a Gαs-mediated mechanism. Cell Signal 2015; 27:1426-38. [PMID: 25866368 DOI: 10.1016/j.cellsig.2015.03.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 01/14/2023]
Abstract
Orexin and dynorphin are co-expressed in the same synaptic vesicles of hypothalamic neurons and play opposing roles in cocaine self-administration, brain stimulation reward, and impulsivity in ventral tegmental area (VTA), where dopamine neurons express both OX1R and KORs. However, detailed mechanisms of how the coreleased peptides and both receptors fine-tune their signalings and physiological/behavioral effects together remain unclear. Here we explore the possibility of heterodimerization between OX1R and KOR and reveal novel signal transduction mechanisms. First, we demonstrated co-expression of OX1R and KOR in rat hippocampal neurons by single-cell PCR. Furthermore, heterodimerization between OX1R and KOR was examined using bioluminescence and fluorescence resonance energy transfer (BRET and FRET). Our data revealed that human OX1R and KOR heterodimerize, and this heterodimer associates with Gαs, leading to increased protein kinase A (PKA) signaling pathway activity, including upregulation of intracellular cAMP levels and cAMP-response element (CRE) luciferase reporter activity, resulting in increased cAMP-response element binding protein (CREB) phosphorylation. These results support the view that OX1R and KOR heterodimerization might have an anti-depressive role.
Collapse
Affiliation(s)
- Jing Chen
- Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK; Neurobiology Institute, Jining Medical University, Jining 272067, PR China.
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Xiaoyu Chen
- Department of Physiology, Taishan Medical University, Taian 271000, PR China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Xin Cai
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Haiqing Liu
- Department of Physiology, Taishan Medical University, Taian 271000, PR China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Chuanxin Liu
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China.
| |
Collapse
|
19
|
Chen X, Bai B, Tian Y, Du H, Chen J. Identification of serine 348 on the apelin receptor as a novel regulatory phosphorylation site in apelin-13-induced G protein-independent biased signaling. J Biol Chem 2014; 289:31173-87. [PMID: 25271156 DOI: 10.1074/jbc.m114.574020] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Phosphorylation plays vital roles in the regulation of G protein-coupled receptor (GPCR) functions. The apelin and apelin receptor (APJ) system is involved in the regulation of cardiovascular function and central control of body homeostasis. Here, using tandem mass spectrometry, we first identified phosphorylated serine residues in the C terminus of APJ. To determine the role of phosphorylation sites in APJ-mediated G protein-dependent and -independent signaling and function, we induced a mutation in the C-terminal serine residues and examined their effects on the interaction between APJ with G protein or GRK/β-arrestin and their downstream signaling. Mutation of serine 348 led to an elimination of both GRK and β-arrestin recruitment to APJ induced by apelin-13. Moreover, APJ internalization and G protein-independent ERK signaling were also abolished by point mutation at serine 348. In contrast, this mutant at serine residues had no demonstrable impact on apelin-13-induced G protein activation and its intracellular signaling. These findings suggest that mutation of serine 348 resulted in inactive GRK/β-arrestin. However, there was no change in the active G protein thus, APJ conformation was biased. These results provide important information on the molecular interplay and impact of the APJ function, which may be extrapolated to design novel drugs for cardiac hypertrophy based on this biased signal pathway.
Collapse
Affiliation(s)
- Xiaoyu Chen
- From the Department of Physiology, Shandong University School of Medicine, Jinan, Shandong 250012, People's Republic of China, the Department of physiology, Taishan Medical College, Taian, Shandong 271000, People's Republic of China
| | - Bo Bai
- the Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, People's Republic of China,
| | - Yanjun Tian
- the Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, People's Republic of China
| | - Hui Du
- the Department of physiology, Taishan Medical College, Taian, Shandong 271000, People's Republic of China
| | - Jing Chen
- the Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, People's Republic of China, the Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom, and
| |
Collapse
|
20
|
Perin M, Longordo F, Massonnet C, Welker E, Lüthi A. Diurnal inhibition of NMDA-EPSCs at rat hippocampal mossy fibre synapses through orexin-2 receptors. J Physiol 2014; 592:4277-95. [PMID: 25085886 DOI: 10.1113/jphysiol.2014.272757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Diurnal release of the orexin neuropeptides orexin-A (Ox-A, hypocretin-1) and orexin-B (Ox-B, hypocretin-2) stabilises arousal, regulates energy homeostasis and contributes to cognition and learning. However, whether cellular correlates of brain plasticity are regulated through orexins, and whether they do so in a time-of-day-dependent manner, has never been assessed. Immunohistochemically we found sparse but widespread innervation of hippocampal subfields through Ox-A- and Ox-B-containing fibres in young adult rats. The actions of Ox-A were studied on NMDA receptor (NMDAR)-mediated excitatory synaptic transmission in acute hippocampal slices prepared around the trough (Zeitgeber time (ZT) 4-8, corresponding to 4-8 h into the resting phase) and peak (ZT 23) of intracerebroventricular orexin levels. At ZT 4-8, exogenous Ox-A (100 nm in bath) inhibited NMDA receptor-mediated excitatory postsynaptic currents (NMDA-EPSCs) at mossy fibre (MF)-CA3 (to 55.6 ± 6.8% of control, P = 0.0003) and at Schaffer collateral-CA1 synapses (70.8 ± 6.3%, P = 0.013), whereas it remained ineffective at non-MF excitatory synapses in CA3. Ox-A actions were mediated postsynaptically and blocked by the orexin-2 receptor (OX2R) antagonist JNJ10397049 (1 μm), but not by orexin-1 receptor inhibition (SB334867, 1 μm) or by adrenergic and cholinergic antagonists. At ZT 23, inhibitory effects of exogenous Ox-A were absent (97.6 ± 2.9%, P = 0.42), but reinstated (87.2 ± 3.3%, P = 0.002) when endogenous orexin signalling was attenuated for 5 h through i.p. injections of almorexant (100 mg kg(-1)), a dual orexin receptor antagonist. In conclusion, endogenous orexins modulate hippocampal NMDAR function in a time-of-day-dependent manner, suggesting that they may influence cellular plasticity and consequent variations in memory performance across the sleep-wake cycle.
Collapse
Affiliation(s)
- Martina Perin
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Fabio Longordo
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Christine Massonnet
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Egbert Welker
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| |
Collapse
|
21
|
Bai B, Liu L, Zhang N, Wang C, Jiang Y, Chen J. Heterodimerization of human apelin and bradykinin 1 receptors: novel signal transduction characteristics. Cell Signal 2014; 26:1549-59. [PMID: 24686079 DOI: 10.1016/j.cellsig.2014.03.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/14/2014] [Indexed: 01/17/2023]
Abstract
Apelin receptor (APJ) and bradykinin 1 receptor (B1R) are involved in a variety of important physiological processes, which share many similar characteristics in distribution and functions in the cardiovascular system. This study explored the possibility of heterodimerization between APJ and B1R, and investigated the impact of heterodimer on the signal transduction characteristics and the physiological functions in human endothelial cells after stimulation with their agonists. We first identified the endogenous expression of APJ and B1R in HUVECs and their co-localization on HEK293 membrane. The constitutive heterodimerization between the APJ and B1R was then demonstrated by BRET and FRET assays. Stimulation with Apelin-13 and des -Arg(9)-BK enhanced the phosphorylation of eNOS in HUVECs, which could be dampened by the knockdown of APJ or B1R, indicating the co-existence of APJ and B1R is critical for eNOS phosphorylation in HUVECs. Furthermore, APJ/B1R heterodimers were found to enhance the activity of PKC signaling pathway and increase intracellular Ca(2+) concentration in HEK293 cells, which might be the mechanism of APJ/B1R heterodimers promoting the phosphorylation of eNOS and leads to increased Gαq, PKC signal pathway activities and a significant increase in cell proliferation. The results provide a new theoretical and experimental base for revealed intracellular molecular mechanisms of physiological function involved in the APJ and B1R and provide potential new targets for the development of drugs and treating cardiovascular disease.
Collapse
Affiliation(s)
- Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China
| | - Lulu Liu
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China
| | - Ning Zhang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong, PR China; Division of Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry, UK.
| |
Collapse
|
22
|
Jäntti MH, Mandrika I, Kukkonen JP. Human orexin/hypocretin receptors form constitutive homo- and heteromeric complexes with each other and with human CB1 cannabinoid receptors. Biochem Biophys Res Commun 2014; 445:486-90. [PMID: 24530395 DOI: 10.1016/j.bbrc.2014.02.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 02/06/2014] [Indexed: 12/17/2022]
Abstract
Human OX1 orexin receptors have been shown to homodimerize and they have also been suggested to heterodimerize with CB1 cannabinoid receptors. The latter has been suggested to be important for orexin receptor responses and trafficking. In this study, we wanted to assess the ability of the other combinations of receptors to also form similar complexes. Vectors for expression of human OX1, OX2 and CB1 receptors, C-terminally fused with either Renilla luciferase or GFP(2) green fluorescent protein variant, were generated. The constructs were transiently expressed in Chinese hamster ovary cells, and constitutive dimerization between the receptors was assessed by bioluminescence energy transfer (BRET). Orexin receptor subtypes readily formed homo- and hetero(di)mers, as suggested by significant BRET signals. CB1 receptors formed homodimers, and they also heterodimerized with both orexin receptors. Interestingly, BRET efficiency was higher for homodimers than for almost all heterodimers. This is likely to be due to the geometry of the interaction; the putatively symmetric dimers may place the C-termini in a more suitable orientation in homomers. Fusion of luciferase to an orexin receptor and GFP(2) to CB1 produced more effective BRET than the opposite fusions, also suggesting differences in geometry. Similar was seen for the OX1-OX2 interaction. In conclusion, orexin receptors have a significant propensity to make homo- and heterodi-/oligomeric complexes. However, it is unclear whether this affects their signaling. As orexin receptors efficiently signal via endocannabinoid production to CB1 receptors, dimerization could be an effective way of forming signal complexes with optimal cannabinoid concentrations available for cannabinoid receptors.
Collapse
Affiliation(s)
- Maria H Jäntti
- Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki, Finland.
| | - Ilona Mandrika
- Latvian Biomedical Research and Study Centre, Ratsupites Str. 1, Riga LV 1067, Latvia.
| | - Jyrki P Kukkonen
- Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki, Finland.
| |
Collapse
|