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Lee JK, Kamran H, Lee KY. L-asparaginase induces IP3R-mediated ER Ca 2+ release by targeting µ-OR1 and PAR2 and kills acute lymphoblastic leukemia cells. Cell Death Discov 2024; 10:366. [PMID: 39147734 PMCID: PMC11327372 DOI: 10.1038/s41420-024-02142-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 08/06/2024] [Accepted: 08/08/2024] [Indexed: 08/17/2024] Open
Abstract
L-asparaginase is a standard therapeutic option for acute lymphoblastic leukemia (aLL), a hematologic cancer that claims the most lives of pediatric cancer patients. Previously, we demonstrated that L-asparaginase kills aLL cells via a lethal rise in [Ca2+]i due to IP3R-mediated ER Ca2+ release followed by calpain-1-Bid-caspase-3/12 activation (Blood, 133, 2222-2232). However, upstream targets of L-asparaginase that trigger IP3R-mediated ER Ca2+ release remain elusive. Here, we show that L-asparaginase targets µ-OR1 and PAR2 and induces IP3R-mediated ER Ca2+ release in aLL cells. In doing so, µ-OR1 plays a major role while PAR2 plays a minor role. Utilizing PAR2- and µ-OR1-knockdown cells, we demonstrate that L-asparaginase stimulation of µ-OR1 and PAR2 relays its signal via Gαi and Gαq, respectively. In PAR2-knockdown cells, stimulation of adenylate cyclase with forskolin or treatment with 8-CPT-cAMP reduces L-asparaginase-induced µ-OR1-mediated ER Ca2+ release, suggesting that activation of µ-OR1 negatively regulates AC and cAMP. In addition, the PKA inhibitor 14-22 amide (myr) alone evokes ER Ca2+ release, and subsequent L-asparaginase treatment does not induce further ER Ca2+ release, indicating the involvement of PKA inhibition in L-asparaginase-induced µ-OR1-mediated ER Ca2+ release, which can bypass the L-asparaginase-µ-OR1-AC-cAMP loop. This coincides with (a) the decreases in PKA-dependent inhibitory PLCβ3 Ser1105 phosphorylation, which prompts PLCβ3 activation and ER Ca2+ release, and (b) BAD Ser118 phosphorylation, which leads to caspase activation and apoptosis. Thus, our findings offer new insights into the Ca2+-mediated mechanisms behind L-asparaginase-induced aLL cell apoptosis and suggest that PKA may be targeted for therapeutic intervention for aLL.
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Affiliation(s)
- Jung Kwon Lee
- Department of Cell Biology & Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada
| | - Hamza Kamran
- Department of Cell Biology & Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada
| | - Ki-Young Lee
- Department of Cell Biology & Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada.
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2
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Ding Y, Gui X, Chu X, Sun Y, Zhang S, Tong H, Ju W, Li Y, Sun Z, Xu M, Li Z, Andrews RK, Gardiner EE, Zeng L, Xu K, Qiao J. MTH1 protects platelet mitochondria from oxidative damage and regulates platelet function and thrombosis. Nat Commun 2023; 14:4829. [PMID: 37563135 PMCID: PMC10415391 DOI: 10.1038/s41467-023-40600-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 07/31/2023] [Indexed: 08/12/2023] Open
Abstract
Human MutT Homolog 1 (MTH1) is a nucleotide pool sanitization enzyme that hydrolyzes oxidized nucleotides to prevent their mis-incorporation into DNA under oxidative stress. Expression and functional roles of MTH1 in platelets are not known. Here, we show MTH1 expression in platelets and its deficiency impairs hemostasis and arterial/venous thrombosis in vivo. MTH1 deficiency reduced platelet aggregation, phosphatidylserine exposure and calcium mobilization induced by thrombin but not by collagen-related peptide (CRP) along with decreased mitochondrial ATP production. Thrombin but not CRP induced Ca2+-dependent mitochondria reactive oxygen species generation. Mechanistically, MTH1 deficiency caused mitochondrial DNA oxidative damage and reduced the expression of cytochrome c oxidase 1. Furthermore, MTH1 exerts a similar role in human platelet function. Our study suggests that MTH1 exerts a protective function against oxidative stress in platelets and indicates that MTH1 could be a potential therapeutic target for the prevention of thrombotic diseases.
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Affiliation(s)
- Yangyang Ding
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Xiang Gui
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Xiang Chu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Yueyue Sun
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Sixuan Zhang
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Huan Tong
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Wen Ju
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Yue Li
- School of Medical Technology, Xuzhou Medical University, Xuzhou, China
| | - Zengtian Sun
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Mengdi Xu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Zhenyu Li
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China
| | - Robert K Andrews
- Division of Genome Science and Cancer, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Elizabeth E Gardiner
- Division of Genome Science and Cancer, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Lingyu Zeng
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China.
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China.
- School of Medical Technology, Xuzhou Medical University, Xuzhou, China.
| | - Kailin Xu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China.
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China.
| | - Jianlin Qiao
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China.
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
- Key Laboratory of Bone Marrow Stem Cell, Xuzhou, Jiangsu Province, China.
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3
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Reyes-García J, Díaz-Hernández V, Carbajal-García A, Casas-Hernández MF, Sommer B, Montaño LM. Theophylline-Induced Relaxation Is Enhanced after Testosterone Treatment via Increased K V1.2 and K V1.5 Protein Expression in Guinea Pig Tracheal Smooth Muscle. Int J Mol Sci 2023; 24:ijms24065884. [PMID: 36982957 PMCID: PMC10059212 DOI: 10.3390/ijms24065884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/16/2023] [Accepted: 02/25/2023] [Indexed: 03/30/2023] Open
Abstract
Theophylline is a drug commonly used to treat asthma due to its anti-inflammatory and bronchodilatory properties. Testosterone (TES) has been suggested to reduce the severity of asthma symptoms. This condition affects boys more than girls in childhood, and this ratio reverses at puberty. We reported that guinea pig tracheal tissue chronic exposure to TES increases the expression of β2-adrenoreceptors and enhances salbutamol-induced K+ currents (IK+). Herein, we investigated whether the upregulation of K+ channels can enhance the relaxation response to methylxanthines, including theophylline. Chronic incubation of guinea pig tracheas with TES (40 nM, 48 h) enhanced the relaxation induced by caffeine, isobutylmethylxanthine, and theophylline, an effect that was abolished by tetraethylammonium. In tracheal myocytes, chronic incubation with TES increased theophylline-induced IK+; flutamide reversed this effect. The increase in IK+ was blocked by 4-aminopyridine by ~82%, whereas iberiotoxin reduced IK+ by ~17%. Immunofluorescence studies showed that chronic TES exposure increased the expression of KV1.2 and KV1.5 in airway smooth muscle (ASM). In conclusion, chronic exposure to TES in guinea pig ASM promotes upregulation of KV1.2 and KV1.5 and enhances theophylline relaxation response. Therefore, gender should be considered when prescribing methylxanthines, as teenage boys and males are likely to respond better than females.
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Affiliation(s)
- Jorge Reyes-García
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Verónica Díaz-Hernández
- Departamento de Embriología y Genética, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Abril Carbajal-García
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - María F Casas-Hernández
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Bettina Sommer
- Laboratorio de Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Mexico City 14080, Mexico
| | - Luis M Montaño
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
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4
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Arige V, Yule DI. Spatial and temporal crosstalk between the cAMP and Ca 2+ signaling systems. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119293. [PMID: 35588944 DOI: 10.1016/j.bbamcr.2022.119293] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 12/31/2022]
Abstract
The ubiquitous secondary messengers, Ca2+ and cAMP, play a vital role in shaping a diverse array of physiological processes. More significantly, accumulating evidence over the past several decades underpin extensive crosstalk between these two canonical messengers in discrete sub-cellular nanodomains across various cell types. Within such specialized nanodomains, each messenger fine-tunes signaling to maintain homeostasis by manipulating the activities of cellular machinery accountable for the metabolism or activity of the complementary pathway. Interaction between these messengers is ensured by scaffolding proteins which tether components of the signaling machinery in close proximity. Disruption of dynamic communications between Ca2+ and cAMP at these loci consequently is linked to several pathological conditions. This review summarizes recent novel mechanisms underlying effective crosstalk between Ca2+ and cAMP in such nanodomains.
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Affiliation(s)
- Vikas Arige
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA..
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5
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Li D, Liu X, Li T, Wang X, Jia S, Wang P, Wang YF. Involvement of Protein Kinase A in Oxytocin Neuronal Activity in Rat Dams with Pup Deprivation. Neurochem Res 2021; 46:980-991. [PMID: 33611682 DOI: 10.1007/s11064-020-03218-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/20/2020] [Accepted: 12/27/2020] [Indexed: 10/22/2022]
Abstract
Oxytocin (OT) neuronal activity is the key factor for breastfeeding and it can be disrupted by mother-baby separation. To explore cellular mechanisms underlying OT neuronal activity, we studied the role of protein kinase A (PKA) in OT neuronal activity in the supraoptic nucleus (SON) using a rodent model of pup deprivation (PD) Intermittent (IPD) or continuous (CPD) PD significantly reduced suckling duration and number of milk ejections in lactating rats, particularly those with CPD. In Western blots of the SON, PD increased expressions of OT receptor (OTR) and its immediate downstream effectors, Gαq and Gβ subunits, particularly IPD, but reduced the expression of catalytic subunit of PKA (cPKA). In brain slices, inhibition of PKA blocked prostaglandin E2-evoked increase in firing activity including burst firing in OT neurons. In IPD dams, filamentous actin formed ring-like structures in the cytoplasmic region of OT neurons, which was reduced in CPD. Moreover, molecular association between actin and cPKA also reduced in PD dams. Incubation of brain slices with OT reduced the expression of cPKA, which was blocked by pretreatment with atosiban, an antagonist of OTR. These results indicate that PD disrupts OT neuronal activity through dissociating the Gq proteins and PKA in OTR-associated signaling cascade, which couples with reduced interactions between filamentous actin and PKA in OT neurons in the SON. This study highlights that PKA can be a novel target treating abnormal OT neuronal activity and its associated diseases.
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Affiliation(s)
- Dongyang Li
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
- Department of Physiology, Hainan Medical University, Haikou, China
| | - Xiaoyu Liu
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
| | - Tong Li
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
| | - Xiaoran Wang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
| | - Shuwei Jia
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
| | - Ping Wang
- Department of Genetics, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China
| | - Yu-Feng Wang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, 150081, China.
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6
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Butler TA, Paul JW, Smith R. Non-conventional signalling in human myometrium by conventional pathways: looking back for a synergistic future. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2019.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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7
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Lian HM, Guo JY, Sun Y, Zhang MH, Piao LH, Jin Z, Cai YL. Mechanism of CNP-mediated DG-PKC and IP4 signaling pathway in diabetic rats with gastric motility disorder. Mol Biol Rep 2019; 47:141-149. [PMID: 31583569 DOI: 10.1007/s11033-019-05115-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 09/26/2019] [Indexed: 11/26/2022]
Abstract
In the precedent research conducted by the same team, it concluded that the activities in C-type natriuretic peptide (CNP)/cyclic guanosine monophosphate (cGMP)/cyclic adenosine monophosphate (cAMP)/β-type phospholipase C (PLCβ) pathways of rat antral smooth muscle were changed due to diabetes, which was the key pathogenetic mechanism for diabetic gastric dysmotility. As the follow-on step, this study was designed to probe into the downstream signaling pathway of CNP/PLCβ. The results showed that level of α-type protein kinase C (PKCα),cell membrane to cytoplasm ratio of PKCα, cell membrane to cytoplasmic ratio of βI-type protein kinase C (PKCβI) and level of Phosphor-PKCα (P-PKCα) were significantly reduced in diabetes rat antral smooth muscle samples. The content of tetraphosphate inositol (IP4) in gastric antral smooth muscle of diabetic rats reduced, and the content of diacyl-glycerol (DG) was unchanged. CNP significantly decreased the content of IP4 and DG, this effect was more obvious in diabetic rats. Subsequent to the addition of protein kinase A (PKA) blocker N-[2- (p-Bromocin-namylamino)ethyl]-5 -isoquinolinesulfonamide dihydrochloride (H-89) before CNP treatment, the inhibitory effect of CNP was reduced; subsequent to the addition of protein kinase G (PKG) blocker KT5823 before CNP treatment, the inhibitory effect of CNP was also reduced. With the addition of the combination of H-89 and KT5823 before CNP treatment, the inhibition by CNP could be offset. These results were concluded that CNP inhibited the activity of PKC family in rat smooth muscle and reduced the levels of IP4 and DG through the PKG/PKA-PLCβ pathways, causing inhibited muscular contractions, which may be a key pathogenetic factor for diabetic gastroparesis.
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Affiliation(s)
- Hui-Ming Lian
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Jun-Yu Guo
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Yan Sun
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Mo-Han Zhang
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Li-Hua Piao
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Zheng Jin
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China
| | - Ying-Lan Cai
- Department of Histology and Embryology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji, 133002, China.
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8
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Liu Z, Wang Y, Yao Y, Fang Z, Miao QR, Ye M. Quantitative proteomic and phosphoproteomic studies reveal novel 5-fluorouracil resistant targets in hepatocellular carcinoma. J Proteomics 2019; 208:103501. [PMID: 31454556 DOI: 10.1016/j.jprot.2019.103501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/12/2019] [Accepted: 08/21/2019] [Indexed: 02/07/2023]
Abstract
The development of chemoresistance remains the major obstacles to successful chemotherapy of hepatocellular carcinoma. The molecular mechanisms of drug resistance are complex. Identifying the key markers is crucial for development of therapeutic strategies to overcome resistance. In this study, we employed a cell-line model consisting of the 5-fluorouracil resistant Bel/5-Fu cell line and its parental Bel cell line. Using stable isotope dimethyl labeling combined with high-resolution mass spectrometry, in total, 8272 unique proteins and 22,095 phosphorylation sites with high localization confidence were identified. Our data indicated that the GnRH signaling pathway was involved in acquiring drug resistance, which has not been well elucidated. The western blotting results confirmed that the expression levels of PLCβ3 and PLCβ3 pS1105 in Bel/5-Fu cells were increased as compared to Bel cells. Furthermore, the protein levels of SRC and PKCδ, which could phosphorylate PLCβ3 at ser1105, were higher in Bel/5-Fu cells than in Bel cells. The knockdown of SRC, PKCδ and PLCβ3 increased the susceptibility of Bel/5-Fu cells to 5-Fu. Besides, the increased transcription levels of PLCβ3, PKCδ and SRC were significantly associated with decreased overall survival. Together, our deep proteomic and phosphoproteomic data reveal novel therapeutic targets for attenuating 5-Fu resistance in anti-cancer therapy. SIGNIFICANCE: It was reported that many hepatocellular carcinoma patients are resistance to 5-Fu. Although some studies related to drug resistance have been reported, the underlying mechanisms were not well elucidated. Unlike many single molecular studies, we focused on the global proteome and phosphoproteome analysis of Bel and Bel5-/Fu cell line using stable isotope dimethyl labeling to identify the previously unrecognized signaling pathway for causing 5-Fu resistance. Our results showed that the phosphorylation levels of PLCβ3 pS1105 and the protein levels of PLCβ3, PKCδ and SRC, which are major components of GnRH signaling pathway were higher in Bel/5-Fu cells than in Bel cells. Furthermore, knockdown of PLCβ3, PKCδ and SRC increased the susceptibility of Bel/5-Fu cells to 5-Fu. Overall, this is the first comprehensive proteomic and phosphoproteomic studies on 5-Fu resistant cell line Bel/5-Fu to identify the potential targets of attenuating chemoresistance in hepatocellular carcinoma.
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Affiliation(s)
- Zhen Liu
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Wang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yating Yao
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Fang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qing R Miao
- Divisions of Pediatric Surgery and Pediatric Pathology, Departments of Surgery and Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, United States of America; New York University Winthrop Hospital, Mineola, NY 11501, United States of America.
| | - Mingliang Ye
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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9
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Guo JY, Zhang MH, Jiang JZ, Piao LH, Fang XS, Jin Z, Cai YL. The role of CNP-mediated PKG/PKA-PLCβ pathway in diabetes-induced gastric motility disorder. Peptides 2018; 110:47-55. [PMID: 30391424 DOI: 10.1016/j.peptides.2018.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/30/2018] [Accepted: 10/30/2018] [Indexed: 12/18/2022]
Abstract
Our previous work demonstrated that the C-type natriuretic peptide (CNP)/cyclic guanosine monophosphate (cGMP)/cyclic adenosine monophosphate (cAMP) pathway in gastric antrum smooth muscle of rats with diabetes was upregulated and played an important role in the development of diabetic gastric dysmotility. Our goal for this study was to explore the downstream signaling pathways of CNP. We found that the expressions of protein kinase G (PKG) and protein kinase A (PKA) in gastric smooth muscle tissue of rats with diabetes were significantly upregulated. The expressions of β-type phospholipase C 3(PLCβ3) and β-type phospholipase C 1(PLCβ1) protein were reduced, whereas Phosphor-PLCβ3Ser1105 (P-PLCβ3Ser1105) was increased. The inhibitory effect of CNP on gastric antral smooth muscle in diabetic rats was significantly greater than in the normal group. The content of trisphosphate inositol (IP3) in the gastric antral smooth muscle of rats with diabetes was significantly lower than that of the normal group. After blocking PKA with N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H-89, a blockage PKA), the effect of CNP on the production of IP3 was decreased, while blocking PKG with KT5823 (a blockage PKG) simultaneously, and CNP can no longer reduce the IP3 production. CNP promoted the phosphorylation of PLCβ3Ser1105, thereby inhibiting the activity of PLCβ3 in gastric smooth muscle tissue of rats with diabetes; this effect can be abolished by blocking PKA and PKG. These results suggested that CNP can decrease IP3 level in gastric smooth muscle cells and thus inhibit gastric smooth muscle contraction through PKG/PKA-PLCβ pathway, which may play an important role in the development of diabetic gastroparesis.
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Affiliation(s)
- Jun-Yu Guo
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Mo-Han Zhang
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Jing-Zhi Jiang
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Li-Hua Piao
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Xue-Sen Fang
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Zheng Jin
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China
| | - Ying-Lan Cai
- Department of Physiology, Yanbian University School of Medicine, 977 Gongyuan, Road, Jilin, Yanji 133002, China.
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10
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Zou QY, Zhao YJ, Zhou C, Liu AX, Zhong XQ, Yan Q, Li Y, Yi FX, Bird IM, Zheng J. G Protein α Subunit 14 Mediates Fibroblast Growth Factor 2-Induced Cellular Responses in Human Endothelial Cells. J Cell Physiol 2018; 234:10184-10195. [PMID: 30387149 DOI: 10.1002/jcp.27688] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/09/2018] [Indexed: 12/20/2022]
Abstract
During pregnancy, a tremendous increase in fetoplacental angiogenesis is associated with elevated blood flow. Aberrant fetoplacental vascular function may lead to pregnancy complications including pre-eclampsia. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are crucial regulators of fetoplacental endothelial function. G protein α subunit 14 (GNA14), a member of Gαq/11 subfamily is involved in mediating hypertensive diseases and tumor vascularization. However, little is known about roles of GNA14 in mediating the FGF2- and VEGFA-induced fetoplacental endothelial function. Using human umbilical vein endothelial cells (HUVECs) cultured under physiological chronic low oxygen (3% O2 ) as a cell model, we show that transfecting cells with adenovirus carrying GNA14 complementary DNA (cDNA; Ad-GNA14) increases (p < 0.05) protein expression of GNA14. GNA14 overexpression blocks (p < 0.05) FGF2-stimulated endothelial migration, whereas it enhances (p < 0.05) endothelial monolayer integrity (maximum increase of ~35% over the control at 24 hr) in response to FGF2. In contrast, GNA14 overexpression does not significantly alter VEGFA-stimulated cell migration, VEGFA-weakened cell monolayer integrity, and intracellular Ca++ mobilization in response to adenosine triphosphate (ATP), FGF2, and VEGFA. GNA14 overexpression does not alter either FGF2- or VEGFA-induced phosphorylation of ERK1/2. However, GNA14 overexpression time-dependently elevates (p < 0.05) phosphorylation of phospholipase C-β3 (PLCβ3) at S1105 in response to FGF2, but not VEGFA. These data suggest that GNA14 distinctively mediates fetoplacental endothelial cell migration and permeability in response to FGF2 and VEGFA, possibly in part by altering activation of PLCβ3 under physiological chronic low oxygen.
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Affiliation(s)
- Qing-Yun Zou
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Ying-Jie Zhao
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Rheumatology, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Chi Zhou
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Ai-Xia Liu
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Reproductive Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xin-Qi Zhong
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Pediatrics, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Qin Yan
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yan Li
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Fu-Xian Yi
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Ian M Bird
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jing Zheng
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin.,Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
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11
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Zou Q, Zhao Y, Li H, Wang X, Liu A, Zhong X, Yan Q, Li Y, Zhou C, Zheng J. GNA11 differentially mediates fibroblast growth factor 2- and vascular endothelial growth factor A-induced cellular responses in human fetoplacental endothelial cells. J Physiol 2018; 596:2333-2344. [PMID: 29659033 PMCID: PMC6002203 DOI: 10.1113/jp275677] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/09/2018] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Fetoplacental vascular growth is critical to fetal growth. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are two major regulators of fetoplacental vascular growth. G protein α subunit 11 (GNA11) transmits signals from many external stimuli to the cellular interior and may mediate endothelial function. It is not known whether GNA11 mediates FGF2- and VEGFA-induced endothelial cell responses under physiological chronic low O2 . In the present study, we show that knockdown of GNA11 significantly decreases FGF2- and VEGFA-induced fetoplacental endothelial cell migration but not proliferation and permeability. Such decreases in endothelial migration are associated with increased phosphorylation of phospholipase C-β3. The results of the present study suggest differential roles of GNA11 with respect to mediating FGF2- and VEGFA-induced fetoplacental endothelial function. ABSTRACT During pregnancy, fetoplacental angiogenesis is dramatically increased in association with rapidly elevated blood flow. Any disruption of fetoplacental angiogenesis may lead to pregnancy complications such as intrauterine growth restriction. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are crucial regulators of fetoplacental angiogenesis. G protein α subunits q (GNAq) and 11 (GNA11) are two members of the Gαq/11 subfamily involved in mediating vascular growth and basal blood pressure. However, little is known about the roles of GNA11 alone with respect to mediating the FGF2- and VEGFA-induced fetoplacental endothelial function. Using a cell model of human umbilical cord vein endothelial cells cultured under physiological chronic low O2 (3% O2 ), we showed that GNA11 small interfering RNA (siRNA) dramatically inhibited (P < 0.05) FGF2- and VEGFA-stimulated fetoplacental endothelial migration (by ∼36% and ∼50%, respectively) but not proliferation and permeability. GNA11 siRNA also elevated (P < 0.05) FGF2- and VEGFA-induced phosphorylation of phospholipase C-β3 (PLCβ3) at S537 in a time-dependent fashion but not mitogen-activated protein kinase 3/1 (ERK1/2) and v-akt murine thymoma viral oncogene homologue 1 (AKT1). These data suggest that GNA11 mediates FGF2- and VEGFA-stimulated fetoplacental endothelial cell migration partially via altering the activation of PLCβ3.
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Affiliation(s)
- Qing‐yun Zou
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Ying‐jie Zhao
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Rheumatology, Qilu HospitalShandong UniversityJinanShandongChina
| | - Hua Li
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Rheumatology and ImmunologyAffiliated Hospital of Qingdao UniversityQingdaoShandongChina
| | - Xiang‐zhen Wang
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Obstetrics and GynecologyNanshan District Maternal and Child Healthcare HospitalShenzhenGuangdongChina
| | - Ai‐xia Liu
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Reproductive EndocrinologyZhejiang UniversityHangzhouZhejiangChina
| | - Xin‐qi Zhong
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Pediatrics3rd Affiliated Hospital of Guangzhou Medical UniversityGuangzhouGuangdongChina
| | - Qin Yan
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Gynecology, Shanghai First Maternity and Infant HospitalTongji University School of MedicineShanghaiChina
| | - Yan Li
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Chi Zhou
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Jing Zheng
- Department of Obstetrics and GynecologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Cardiovascular Medicine CenterAffiliated Hospital of Guangdong Medical UniversityZhanjiangGuangdongChina
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12
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Sánchez G, Estrada O, Acha G, Cardozo A, Peña F, Ruiz MC, Michelangeli F, Alvarado-Castillo C. The norpurpureine alkaloid from Annona purpurea inhibits human platelet activation in vitro. Cell Mol Biol Lett 2018; 23:15. [PMID: 29713353 PMCID: PMC5905151 DOI: 10.1186/s11658-018-0082-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 04/09/2018] [Indexed: 01/01/2023] Open
Abstract
Background The leaves of Annona purpurea have yielded several alkaloids with anti-aggregation activities against rabbit platelets. This is promising in the search for agents that might act against platelets and reduce the incidence of cardiovascular diseases. Since significant differences in platelet function have been reported between human and animal platelets, a study focusing on the effect of A. purpurea extracts against human platelet activation is necessary. Methods The compounds in an A. purpurea ethanolic extract underwent bio-guided fractionation and were used for in vitro human platelet aggregation assays to isolate the compounds with anti-platelet activity. The bioactive compounds were identified by spectroscopic analysis. Additional platelet studies were performed to characterize their action as inhibitors of human platelet activation. Results The benzylisoquinoline alkaloid norpurpureine was identified as the major anti-platelet compound. The IC50 for norpurpureine was 80 μM against platelets when stimulated with adenosine 5′-diphosphate (ADP), collagen and thrombin. It was pharmacologically effective from 20 to 220 μM. Norpurpureine (220 μM) exhibited its in vitro effectiveness in samples from 30 healthy human donors who did not take any drugs during the 2 weeks prior to the collection. Norpurpureine also gradually inhibited granule secretion and adhesion of activated platelets to immobilized fibrinogen. At the intra-platelet level, norpurpureine prevented agonist-stimulated calcium mobilization and cAMP reduction. Structure–activity relationship analysis indicates that the lack of a methyl group at the nitrogen seems to be key in the ability of the compound to interact with its molecular target. Conclusion Norpurpureine displays a promising in vitro pharmacological profile as an inhibitor of human platelet activation. Its molecular target could be a common effector between Ca2+ and cAMP signaling, such as the PLC-PKC-Ca2+ pathway and PDEs. This needs further evaluation at the protein isoform level. Electronic supplementary material The online version of this article (10.1186/s11658-018-0082-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gabriela Sánchez
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Omar Estrada
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Giovana Acha
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Alfonso Cardozo
- 2Laboratorio de Botánica Sistemática, Facultad de Agronomía, Universidad Central de Venezuela (UCV), Maracay, Bolivarian Republic of Venezuela
| | - Franshelle Peña
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Marie Christine Ruiz
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Fabián Michelangeli
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Claudia Alvarado-Castillo
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela.,3Laboratorio de Hemostasia y Genética Vascular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, K11 de la Carretera Panamericana, Caracas, 1020-A Bolivarian Republic of Venezuela
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13
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Makhoul S, Walter E, Pagel O, Walter U, Sickmann A, Gambaryan S, Smolenski A, Zahedi RP, Jurk K. Effects of the NO/soluble guanylate cyclase/cGMP system on the functions of human platelets. Nitric Oxide 2018; 76:71-80. [PMID: 29550521 DOI: 10.1016/j.niox.2018.03.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/03/2018] [Accepted: 03/12/2018] [Indexed: 02/07/2023]
Abstract
Platelets are circulating sentinels of vascular integrity and are activated, inhibited, or modulated by multiple hormones, vasoactive substances or drugs. Endothelium- or drug-derived NO strongly inhibits platelet activation via activation of the soluble guanylate cyclase (sGC) and cGMP elevation, often in synergy with cAMP-elevation by prostacyclin. However, the molecular mechanisms and diversity of cGMP effects in platelets are poorly understood and sometimes controversial. Recently, we established the quantitative human platelet proteome, the iloprost/prostacyclin/cAMP/protein kinase A (PKA)-regulated phosphoproteome, and the interactions of the ADP- and iloprost/prostacyclin-affected phosphoproteome. We also showed that the sGC stimulator riociguat is in vitro a highly specific inhibitor, via cGMP, of various functions of human platelets. Here, we review the regulatory role of the cGMP/protein kinase G (PKG) system in human platelet function, and our current approaches to establish and analyze the phosphoproteome after selective stimulation of the sGC/cGMP pathway by NO donors and riociguat. Present data indicate an extensive and diverse NO/riociguat/cGMP phosphoproteome, which has to be compared with the cAMP phosphoproteome. In particular, sGC/cGMP-regulated phosphorylation of many membrane proteins, G-proteins and their regulators, signaling molecules, protein kinases, and proteins involved in Ca2+ regulation, suggests that the sGC/cGMP system targets multiple signaling networks rather than a limited number of PKG substrate proteins.
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Affiliation(s)
- Stephanie Makhoul
- University Medical Center Mainz, Center for Thrombosis and Hemostasis (CTH), Mainz, Germany
| | - Elena Walter
- University Medical Center Mainz, Center for Thrombosis and Hemostasis (CTH), Mainz, Germany
| | - Oliver Pagel
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e. V., Dortmund, Germany
| | - Ulrich Walter
- University Medical Center Mainz, Center for Thrombosis and Hemostasis (CTH), Mainz, Germany
| | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e. V., Dortmund, Germany; Ruhr Universität Bochum, Medizinisches Proteom Center, Medizinische Fakultät, Bochum, Germany; Department of Chemistry, College of Physical Sciences, University of Aberdeen, Aberdeen, UK
| | - Stepan Gambaryan
- University Medical Center Mainz, Center for Thrombosis and Hemostasis (CTH), Mainz, Germany; Russian Academy of Sciences, Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia; St. Petersburg State University, Department of Cytology and Histology, St. Petersburg, Russia
| | - Albert Smolenski
- Conway Institute of Biomolecular & Biomedical Research, Univ. College Dublin, Dublin, Ireland; Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - René P Zahedi
- Gerald Bronfman Department of Oncology, Jewish General Hospital, McGill University , Montreal, Quebec H4A 3T2, Canada; Segal Cancer Proteomics Centre, Lady Davis Institute, Jewish General Hospital, McGill University , Montreal, Quebec H3T 1E2, Canada
| | - Kerstin Jurk
- University Medical Center Mainz, Center for Thrombosis and Hemostasis (CTH), Mainz, Germany.
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14
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Pradhan S, Khatlani T, Nairn AC, Vijayan KV. The heterotrimeric G protein Gβ 1 interacts with the catalytic subunit of protein phosphatase 1 and modulates G protein-coupled receptor signaling in platelets. J Biol Chem 2017; 292:13133-13142. [PMID: 28615442 DOI: 10.1074/jbc.m117.796656] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/13/2017] [Indexed: 11/06/2022] Open
Abstract
Thrombosis is caused by the activation of platelets at the site of ruptured atherosclerotic plaques. This activation involves engagement of G protein-coupled receptors (GPCR) on platelets that promote their aggregation. Although it is known that protein kinases and phosphatases modulate GPCR signaling, how serine/threonine phosphatases integrate with G protein signaling pathways is less understood. Because the subcellular localization and substrate specificity of the catalytic subunit of protein phosphatase 1 (PP1c) is dictated by PP1c-interacting proteins, here we sought to identify new PP1c interactors. GPCRs signal via the canonical heterotrimeric Gα and Gβγ subunits. Using a yeast two-hybrid screen, we discovered an interaction between PP1cα and the heterotrimeric G protein Gβ1 subunit. Co-immunoprecipitation studies with epitope-tagged PP1c and Gβ1 revealed that Gβ1 interacts with the PP1c α, β, and γ1 isoforms. Purified PP1c bound to recombinant Gβ1-GST protein, and PP1c co-immunoprecipitated with Gβ1 in unstimulated platelets. Thrombin stimulation of platelets induced the dissociation of the PP1c-Gβ1 complex, which correlated with an association of PP1c with phospholipase C β3 (PLCβ3), along with a concomitant dephosphorylation of the inhibitory Ser1105 residue in PLCβ3. siRNA-mediated depletion of GNB1 (encoding Gβ1) in murine megakaryocytes reduced protease-activated receptor 4, activating peptide-induced soluble fibrinogen binding. Thrombin-induced aggregation was decreased in PP1cα-/- murine platelets and in human platelets treated with a small-molecule inhibitor of Gβγ. Finally, disruption of PP1c-Gβ1 complexes with myristoylated Gβ1 peptides containing the PP1c binding site moderately decreased thrombin-induced human platelet aggregation. These findings suggest that Gβ1 protein enlists PP1c to modulate GPCR signaling in platelets.
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Affiliation(s)
- Subhashree Pradhan
- From the Departments of Medicine.,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC), Houston, Texas 77030 and
| | - Tanvir Khatlani
- From the Departments of Medicine.,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC), Houston, Texas 77030 and
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
| | - K Vinod Vijayan
- From the Departments of Medicine, .,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC), Houston, Texas 77030 and.,Pediatrics.,Molecular Physiology and Biophysics, Baylor College of Medicine and
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15
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Cerny O, Anderson KE, Stephens LR, Hawkins PT, Sebo P. cAMP Signaling of Adenylate Cyclase Toxin Blocks the Oxidative Burst of Neutrophils through Epac-Mediated Inhibition of Phospholipase C Activity. THE JOURNAL OF IMMUNOLOGY 2016; 198:1285-1296. [PMID: 28039302 DOI: 10.4049/jimmunol.1601309] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/16/2016] [Indexed: 01/08/2023]
Abstract
The adenylate cyclase toxin-hemolysin (CyaA) plays a key role in immune evasion and virulence of the whooping cough agent Bordetella pertussis. CyaA penetrates the complement receptor 3-expressing phagocytes and ablates their bactericidal capacities by catalyzing unregulated conversion of cytosolic ATP to the key second messenger molecule cAMP. We show that signaling of CyaA-generated cAMP blocks the oxidative burst capacity of neutrophils by two converging mechanisms. One involves cAMP/protein kinase A-mediated activation of the Src homology region 2 domain-containing phosphatase-1 (SHP-1) and limits the activation of MAPK ERK and p38 that are required for assembly of the NADPH oxidase complex. In parallel, activation of the exchange protein directly activated by cAMP (Epac) provokes inhibition of the phospholipase C by an as yet unknown mechanism. Indeed, selective activation of Epac by the cell-permeable analog 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate counteracted the direct activation of phospholipase C by 2,4,6-trimethyl-N-[3-(trifluoromethyl)phenyl]benzenesulfonamide. Hence, by inhibiting production of the protein kinase C-activating lipid, diacylglycerol, cAMP/Epac signaling blocks the bottleneck step of the converging pathways of oxidative burst triggering. Manipulation of neutrophil membrane composition by CyaA-produced signaling of cAMP thus enables B. pertussis to evade the key innate host defense mechanism of reactive oxygen species-mediated killing of bacteria by neutrophils.
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Affiliation(s)
- Ondrej Cerny
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the CAS, v.v.i., 142 20 Prague, Czech Republic; and
| | - Karen E Anderson
- Signalling Programme, Babraham Institute, Babraham, Cambridge CB22 3AT, United Kingdom
| | - Len R Stephens
- Signalling Programme, Babraham Institute, Babraham, Cambridge CB22 3AT, United Kingdom
| | - Phillip T Hawkins
- Signalling Programme, Babraham Institute, Babraham, Cambridge CB22 3AT, United Kingdom
| | - Peter Sebo
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the CAS, v.v.i., 142 20 Prague, Czech Republic; and
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16
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Ayres AW, Carr DW, McConnell DS, Lieberman RW, Smith GD. Expression and Intracellular Localization of Protein Phosphatases 2A and 2B, Protein Kinase A, A-Kinase Anchoring Protein (AKAP79), and Binding of the Regulatory (RII) Subunit of Protein Kinase A to AKAP79 in Human Myometrium. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/s1071-55760300136-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
| | | | | | - Richard W. Lieberman
- Oregon Health & Sciences University, Veterans Affairs Medical Center, Portland, Oregon; Reproductive Science Program; Departments of Obstetrics and Gynecology, Pathology, and Physiology and Urology, University of Michigan, Ann Arbor, Michigan
| | - Gary D. Smith
- Oregon Health & Sciences University, Veterans Affairs Medical Center, Portland, Oregon; Reproductive Science Program; Departments of Obstetrics and Gynecology, Pathology, and Physiology and Urology, University of Michigan, Ann Arbor, Michigan; University of Michigan, 6428 Med Sci 1, 1301 E. Catherine Street, Ann Arbor, MI 48109-0617
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17
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Ku CY, Word RA, Sanborn BM. Differential Expression of Protein Kinase A, AKAP 79, and PP2B in Pregnant Human Myometrial Membranes Prior to and During Labor. ACTA ACUST UNITED AC 2016; 12:421-7. [PMID: 15914039 DOI: 10.1016/j.jsgi.2005.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We have previously shown that the association of protein kinase A (PKA) with purified myometrial plasma membrane declined at the end of pregnancy in the rat. This study was designed to determine if a similar decline in PKA occurred in pregnant human myometrium. METHODS Myometrial plasma membranes were isolated from lower uterine segment tissues from not-in-labor (NIL) and in-labor (IL) patients undergoing cesarean delivery. Membrane proteins were subjected to Western blot analysis to detect PKA-catalytic (PKA-cat) and PKA-regulatory (PKA-reg) subunits, the PKA binding protein A-kinase anchoring protein 79 (AKAP79), protein phosphatase 2B (PP2B), and Galphaq, a guanosine triphosphate (GTP)-binding protein. Protein levels were expressed relative to caveolin-1, which was invariant between the two groups. RESULTS The amount of PKA-cat, PKA-reg, AKAP79, and PP2B in plasma membranes from myometrium of women in early labor decreased significantly compared with that in tissues from women not in labor. In contrast, Galphaq did not change. All proteins were localized to myometrial smooth muscle cells by immunohistochemistry. CONCLUSIONS Expression of PKA, PP2B, and AKAP79 is consistent with the presence of a functional AKAP-mediated signaling complex in pregnant human myometrial membranes. A small but significant decrease in PKA, AKAP79, and PP2B in myometrial tissues from women in labor may contribute to a decrease in negative feedback on and enhancement of contractant signals at term.
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Affiliation(s)
- Chun-Ying Ku
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
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18
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Abstract
Gαq signals with phospholipase C-β (PLC-β) to modify behavior in response to an agonist-bound GPCR. While the fundamental steps which prime Gαq to interact with PLC-β have been identified, questions remain concerning signal strength with PLC-β and other effectors. Gαq is generally viewed to function as a simple ON and OFF switch for its effector, dependent on the binding of GTP or GDP. However, Gαq does not have a single effector, Gαq has many different effectors. Furthermore, select effectors also regulate Gαq activity. PLC-β is a lipase and a GTPase activating protein (GAP) selective for Gαq. The contribution of G protein regulating activity to signal amplitude remains unclear. The unique PLC-β coiled-coil domain is essential for maximum Gαq response, both lipase and GAP. Nonetheless, coiled-coil domain associations necessary to maximum response have not been revealed by the structural approach. This review discusses progress towards understanding the basis for signal strength with PLC-β and other effectors. Shared and effector-specific interactions have been identified. Finally, the evidence for allosteric regulation of lipase stimulation by protein kinase C, the membrane, phosphatidic acid, phosphatidylinositol-4, 5-bisphosphate and GPCR is explored. Endogenous allosteric regulators can suppress or enhance maximum lipase stimulation dependent on the PLC-β coiled-coil domain. A better understanding of allosteric modulation may therefore identify a wealth of new targets to regulate signal strength and behavior.
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Affiliation(s)
- Irene Litosch
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine University of Miami, Miami, FL 33101-6189, USA.
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19
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Litosch I. Regulating G protein activity by lipase-independent functions of phospholipase C. Life Sci 2015; 137:116-24. [DOI: 10.1016/j.lfs.2015.07.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/18/2015] [Accepted: 07/22/2015] [Indexed: 11/27/2022]
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20
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Regulation of Gβγi-dependent PLC-β3 activity in smooth muscle: inhibitory phosphorylation of PLC-β3 by PKA and PKG and stimulatory phosphorylation of Gαi-GTPase-activating protein RGS2 by PKG. Cell Biochem Biophys 2015; 70:867-80. [PMID: 24777815 DOI: 10.1007/s12013-014-9992-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In gastrointestinal smooth muscle, agonists that bind to Gi-coupled receptors activate preferentially PLC-β3 via Gβγ to stimulate phosphoinositide (PI) hydrolysis and generate inositol 1,4,5-trisphosphate (IP3) leading to IP3-dependent Ca(2+) release and muscle contraction. In the present study, we identified the mechanism of inhibition of PLC-β3-dependent PI hydrolysis by cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG). Cyclopentyl adenosine (CPA), an adenosine A1 receptor agonist, caused an increase in PI hydrolysis in a concentration-dependent fashion; stimulation was blocked by expression of the carboxyl-terminal sequence of GRK2(495-689), a Gβγ-scavenging peptide, or Gαi minigene but not Gαq minigene. Isoproterenol and S-nitrosoglutathione (GSNO) induced phosphorylation of PLC-β3 and inhibited CPA-induced PI hydrolysis, Ca(2+) release, and muscle contraction. The effect of isoproterenol on all three responses was inhibited by PKA inhibitor, myristoylated PKI, or AKAP inhibitor, Ht-31, whereas the effect of GSNO was selectively inhibited by PKG inhibitor, Rp-cGMPS. GSNO, but not isoproterenol, also phosphorylated Gαi-GTPase-activating protein, RGS2, and enhanced association of Gαi3-GTP and RGS2. The effect of GSNO on PI hydrolysis was partly reversed in cells (i) expressing constitutively active GTPase-resistant Gαi mutant (Q204L), (ii) phosphorylation-site-deficient RGS2 mutant (S46A/S64A), or (iii) siRNA for RGS2. We conclude that PKA and PKG inhibit Gβγi-dependent PLC-β3 activity by direct phosphorylation of PLC-β3. PKG, but not PKA, also inhibits PI hydrolysis indirectly by a mechanism involving phosphorylation of RGS2 and its association with Gαi-GTP. This allows RGS2 to accelerate Gαi-GTPase activity, enhance Gαβγi trimer formation, and inhibit Gβγi-dependent PLC-β3 activity.
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Ito M, Matsuoka I. Inhibition of P2Y6 receptor-mediated phospholipase C activation and Ca(2+) signalling by prostaglandin E2 in J774 murine macrophages. Eur J Pharmacol 2015; 749:124-32. [PMID: 25614334 DOI: 10.1016/j.ejphar.2014.12.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/16/2014] [Accepted: 12/18/2014] [Indexed: 12/20/2022]
Abstract
Extracellular nucleotides act as inflammatory mediators through activation of multiple purinoceptors. Under inflammatory conditions, the purinergic signalling is affected by various inflammatory mediators. We previously showed that prostaglandin (PG) E2 suppressed the elevation of intracellular Ca(2+) concentration ([Ca(2+)]i) stimulated by P2X4, P2Y2, and P2Y6 receptors in J774 murine macrophages. In this study, we examined the mechanism of PGE2 inhibitory effects on P2Y6 receptor-mediated function in J774 cells. The P2Y6 receptor agonist UDP induced a sustained elevation of [Ca(2+)]i by stimulating the phospholipase C (PLC) signalling pathway. PGE2 inhibited [Ca(2+)]i elevation and phosphatidylinositol (PI) hydrolysis in a concentration-dependent manner. J774 cells highly expressed the E-type prostanoid 2 (EP2) receptor subtype, a Gs-coupled receptor. PGE2 and a selective EP2 receptor agonist caused cyclic AMP (cAMP) accumulation in J774 cells. The inhibitory effects of PGE2 on P2Y6 receptor-mediated responses were mimicked by the selective EP2 receptor agonist. Although EP2 receptor is linked to adenylyl cyclase activation, PGE2-induced inhibition of Ca(2+) response and PI hydrolysis could not be mimicked by a lipophilic cAMP derivative, dibutyryl cAMP, or an adenylyl cyclase activator, forskolin. The inhibition of UDP-induced PLC activation by PGE2 was not affected by down-regulation of protein kinase C by phorbol-12-myristate-13-acetate treatment. PGE2 inhibited PLC activation induced by aluminium fluoride, but not by the Ca(2+)-ionophore, ionomycin. Finally, the inhibition of UDP-induced PLC activation by PGE2 was impaired by Gs knockdown using siRNA. These results suggest that EP2 receptor activation in macrophages negatively controls the Gq/11-PLC signalling through a Gs-mediated, but cAMP-independent signalling mechanism.
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Affiliation(s)
- Masaaki Ito
- Laboratory of Pharmacology, Faculty of Pharmacy, Takasaki University of Health and Welfare, 60 Nakaorui-machi, Takasaki-shi, Gunma 370-0033, Japan.
| | - Isao Matsuoka
- Laboratory of Pharmacology, Faculty of Pharmacy, Takasaki University of Health and Welfare, 60 Nakaorui-machi, Takasaki-shi, Gunma 370-0033, Japan.
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Heindorff K, Baumann O. Calcineurin is part of a negative feedback loop in the InsP3/Ca²⁺ signalling pathway in blowfly salivary glands. Cell Calcium 2014; 56:215-24. [PMID: 25108568 DOI: 10.1016/j.ceca.2014.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 07/01/2014] [Accepted: 07/17/2014] [Indexed: 02/02/2023]
Abstract
The ubiquitous InsP3/Ca(2+) signalling pathway is modulated by diverse mechanisms, i.e. feedback of Ca(2+) and interactions with other signalling pathways. In the salivary glands of the blowfly Calliphora vicina, the hormone serotonin (5-HT) causes a parallel rise in intracellular [Ca(2+)] and [cAMP] via two types of 5-HT receptors. We have shown recently that cAMP/protein kinase A (PKA) sensitizes InsP3-induced Ca(2+) release. We have now identified the protein phosphatase that counteracts the effect of PKA on 5-HT-induced InsP3/Ca(2+) signalling. We demonstrate that (1) tautomycin and okadaic acid, inhibitors of protein phosphatases PP1 and PP2A, have no effect on 5-HT-induced Ca(2+) signals; (2) cyclosporin A and FK506, inhibitors of Ca(2+)/calmodulin-activated protein phosphatase calcineurin, cause an increase in the frequency of 5-HT-induced Ca(2+) oscillations; (3) the sensitizing effect of cyclosporin A on 5-HT-induced Ca(2+) responses does not involve Ca(2+) entry into the cells; (4) cyclosporin A increases InsP3-dependent Ca(2+) release; (5) inhibition of PKA abolishes the effect of cyclosporin A on the 5-HT-induced Ca(2+) responses, indicating that PKA and calcineurin act antagonistically on the InsP3/Ca(2+) signalling pathway. These findings suggest that calcineurin provides a negative feedback on InsP3/Ca(2+) signalling in blowfly salivary glands, counteracting the effect of PKA and desensitizing the signalling cascade at higher 5-HT concentrations.
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Affiliation(s)
- Kristoffer Heindorff
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany
| | - Otto Baumann
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.
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Abstract
Rapid progress has recently been made regarding how phospholipase C (PLC)-β functions downstream of G protein-coupled receptors and how PLC-β functions in the nucleus. PLC-β has also been shown to interplay with tyrosine kinase-based signaling pathways, specifically to inhibit Stat5 activation by recruiting the protein-tyrosine phosphatase SHP-1. In this regard, a new multimolecular signaling platform, named SPS complex, has been identified. The SPS complex has important regulatory roles in tumorigenesis and immune cell activation. Furthermore, a growing body of work suggests that PLC-β also participates in the differentiation and activation of immune cells that control both the innate and adaptive immune systems.
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Affiliation(s)
- Wenbin Xiao
- Department of Pathology, University Hospital Case Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA.
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Abstract
AbstractThe Gq-linked G protein coupled receptors (GPCRs) and their signaling pathways are important clinical targets for the dementia of Alzheimer’s disease and cognitive decline with aging. Gq stimulates phospholipase C-β1 (PLC-β1) activity, increasing levels of inositol-1, 4, 5-trisphosphate (IP3) and diacylglycerol, to initiate mobilization of intracellular Ca2+ and activation of protein kinase C, respectively. While high concentrations of ligand typically evoke large sustained increases in cytosolic Ca2+ levels, it has long been appreciated that the dynamics of the Ca2+ increase are more complex and consistent with multiple levels of regulation. Physiologically relevant concentrations of Gq-ligands evoke rhythmic fluctuations or an oscillation in the level of cytosolic Ca2+. Downstream targets are tuned to respond to the frequency of the Ca2+ oscillations which in turn, reflect the oscillations in IP3 levels. Oscillatory behavior depends on the assembly of self-organizing interactions. The components that contribute to and regulate the Ca2+ oscillator have been unclear, precluding transfer of this fundamental knowledge from bench to bedside. Many GPCRs that signal with Gq also co-signal with G12. G protein co-signaling could therefore regulate the Ca2+ oscillator. This letter explores the potential relationship between Ca2+ oscillations, G protein co-signaling and cellular response in the context of our recent observations. We found that Gq efficacy is synergistic with phosphatidic acid, (PA), a signaling mediator generated downstream of activated G12 and RhoA. Regulation by PA depends on interaction with the unique PLC-β1 PA binding region. G protein co-signaling is therefore a mechanism for GPCRs to collectively assemble self-organizing interactions that regulate the Ca2+ oscillator.
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Abstract
Phospholipase C (PLC) converts phosphatidylinositol 4,5-bisphosphate (PIP(2)) to inositol 1,4,5-trisphosphate (IP(3)) and diacylglycerol (DAG). DAG and IP(3) each control diverse cellular processes and are also substrates for synthesis of other important signaling molecules. PLC is thus central to many important interlocking regulatory networks. Mammals express six families of PLCs, each with both unique and overlapping controls over expression and subcellular distribution. Each PLC also responds acutely to its own spectrum of activators that includes heterotrimeric G protein subunits, protein tyrosine kinases, small G proteins, Ca(2+), and phospholipids. Mammalian PLCs are autoinhibited by a region in the catalytic TIM barrel domain that is the target of much of their acute regulation. In combination, the PLCs act as a signaling nexus that integrates numerous signaling inputs, critically governs PIP(2) levels, and regulates production of important second messengers to determine cell behavior over the millisecond to hour timescale.
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Affiliation(s)
- Ganesh Kadamur
- Department of Pharmacology, Molecular Biophysics Graduate Program and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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You X, Gao L, Liu J, Xu C, Liu C, Li Y, Hui N, Gu H, Ni X. CRH activation of different signaling pathways results in differential calcium signaling in human pregnant myometrium before and during labor. J Clin Endocrinol Metab 2012; 97:E1851-61. [PMID: 22869609 DOI: 10.1210/jc.2011-3383] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Our previous study has demonstrated that CRH has differential effects on human uterine contractility before and after onset of labor. Intracellular Ca2+ concentration ([Ca2+]i) mobilization plays an important role in the control of uterine contraction. OBJECTIVE Our objective was to investigate the effects of CRH on [Ca2+]i homeostasis in laboring and nonlaboring myometrial cells and determine subsequent signaling involved in [Ca2+]i regulation by CRH. DESIGN The myometrial tissues were obtained from pregnant women who were undergoing or not undergoing labor at term. [Ca2+]i was determined by Ca2+ imaging system using the fluorescent dye fura-2-acetoxymethyl ester. Western blot analysis, ELISA, and RIA were used to determine the signaling pathways induced by CRH. RESULTS CRH induced Ca2+ transient in laboring cells, which was blocked by CRH receptor type 1 (CRHR1) antagonist antalarmin. CRHR1 knockdown impaired this effect of CRH. CRH activated Gi protein, decreased cAMP production, and induced phosphorylated phospholipase C-β3 and inositol-1,4,5-triphosphate production. Phospholipase C and inositol-1,4,5-triphosphate receptor inhibitors blocked the CRH-induced Ca2+ transient in laboring cells. CRH did not induce whereas antalarmin induced the Ca2+ transient in nonlaboring cells. Knockdown of CRHR1 impaired the effect of antalarmin. CRH acted on CRHR1 to activate Gs in nonlaboring cells. Forskolin blocked antalarmin-induced Ca2+ transient. CONCLUSIONS CRH acts on CRHR1 to activate different signaling pathways before and after onset of labor, thereby resulting in differential calcium signaling in response to CRH. The signaling pathways of CRHR1 might serve as a target for the development of new therapeutic strategies for preterm birth.
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Affiliation(s)
- Xingji You
- Department of Physiology, Second Military Medical University, and Department of Obsetrics and Gynecology, Changhai Hospital, 800 Xiangyin Road, Shanghai 200433, PR China
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Van Hook MJ, Wong KY, Berson DM. Dopaminergic modulation of ganglion-cell photoreceptors in rat. Eur J Neurosci 2012; 35:507-18. [PMID: 22304466 DOI: 10.1111/j.1460-9568.2011.07975.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A novel class of photoreceptors, the intrinsically photosensitive retinal ganglion cells (ipRGCs), express the photopigment melanopsin and drive non-image-forming responses to light such as circadian photoentrainment, the pupillary light reflex and suppression of nocturnal melatonin production in the pineal. Because dendrites from one subclass of these cells - the M1-type ipRGCs - make presumptive synaptic contacts at sites of dopamine release from dopaminergic amacrine cells, they are prime targets for modulation by dopamine, a neuromodulator implicated in retinal circadian rhythms and light adaptation. In patch-clamp recordings from ipRGCs in intact rat retinas, dopamine attenuated the melanopsin-based photocurrent. We confirmed that this was the result of direct action on ipRGCs by replicating the effect in dissociated ipRGCs that were isolated from influences of other retinal neurons. In these recordings, the D1-family dopamine receptor agonist SKF38393 attenuated the photocurrent, caused a modest depolarization, and reduced the input resistance of ipRGCs. The D2-family agonist quinpirole had no effect on the photocurrent. Single-cell reverse-transcriptase polymerase chain reaction revealed that the majority of ipRGCs tested expressed drd1a, the gene coding for the D1a dopamine receptor. This finding was supported by immunohistochemical localization of D1a receptor protein in melanopsin-expressing ganglion cells. Finally, the adenylate cyclase activator forskolin, applied in combination with the phosphodiesterase inhibitor IBMX (isobutylmethylxanthine), mimicked the effects of SKF38393 on the ipRGC photocurrent, membrane potential and input resistance, consistent with a D1-receptor signaling pathway. These data suggest that dopamine, acting via D1-family receptors, alters the responses of ipRGCs and thus of non-image-forming vision.
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Affiliation(s)
- Matthew J Van Hook
- Department of Neuroscience, Brown University, Box G-LN, Providence, RI, USA
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Hatziapostolou M, Koukos G, Polytarchou C, Kottakis F, Serebrennikova O, Kuliopulos A, Tsichlis PN. Tumor progression locus 2 mediates signal-induced increases in cytoplasmic calcium and cell migration. Sci Signal 2011; 4:ra55. [PMID: 21868363 DOI: 10.1126/scisignal.2002006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mitogen-activated protein kinase kinase kinase (MAPKKK or MAP3K) tumor progression locus 2 (Tpl2) is required for the transduction of signals initiated by the thrombin-activated G protein-coupled receptor (GPCR) protease-activated receptor-1 (PAR1), which promote reorganization of the actin cytoskeleton and cell migration. Here, we show that Tpl2 is activated through Gα(i2)-transduced GPCR signals. Activated Tpl2 promoted the phosphorylation and activation of phospholipase C-β3 (PLCβ(3)); consequently, Tpl2 was required for thrombin-dependent production of inositol 1,4,5-trisphosphate (IP(3)), IP(3)-mediated cytoplasmic calcium ion (Ca(2+)) signals, and the activation of classical and novel members of the protein kinase C (PKC) family. A PKC-mediated feedback loop facilitated extracellular signal-regulated kinase (ERK) activation in response to Tpl2 and contributed to the coordinate regulation of the ERK and Ca(2+) signaling pathways. Pharmacological and genetic studies revealed that stimulation of cell migration by Tpl2 depends on both of these pathways. Tpl2 also promoted Ca(2+) signals and cell migration from sphingosine 1-phosphate-responsive GPCRs, which also couple to Gα(i); from Wnt5a; and from the interleukin-1β (IL-1β) receptor, a member of the Toll-IL-1R (TIR) domain family. Our data provide new insights into the role of Tpl2 in GPCR-mediated Ca(2+) signaling and cell migration.
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Affiliation(s)
- Maria Hatziapostolou
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, MA 02111, USA
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Cyclic AMP-mediated immune regulation--overview of mechanisms of action in T cells. Cell Signal 2010; 23:1009-16. [PMID: 21130867 DOI: 10.1016/j.cellsig.2010.11.018] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 11/23/2010] [Accepted: 11/25/2010] [Indexed: 01/21/2023]
Abstract
The canonical second messenger cAMP is well established as a potent negative regulator of T cell immune function. Through protein kinase A (PKA) it regulates T cell function at the level of transcription factors, members of the mitogen-activated protein kinase pathway, phospholipases (PLs), Ras homolog (Rho)A and proteins involved in the control of cell cycle progression. Type I PKA is the predominant PKA isoform in T cells. Furthermore, whereas type II PKA is located at the centrosome, type I PKA is anchored close to the T cell receptor (TCR) in lipid rafts by the Ezrin-ERM-binding phosphoprotein of 50 kDa (EBP50)-phosphoprotein associated with glycosphingolipid-enriched microdomains (PAG) scaffold complex. The most TCR-proximal target for type I PKA is C-terminal Src kinase (Csk), which upon activation by raft recruitment and phosphorylation inhibits the Src family tyrosine kinases Lck and Fyn and thus functions to maintain T cell homeostasis. Recently, induction of cAMP levels in responder T cells has emerged as one of the mechanisms by which regulatory T (T(R)) cells execute their suppressive action. Thus, the cAMP-type I PKA-Csk pathway emerges as a putative target for therapeutic intervention in autoimmune disorders as well as in cancer, where T(R) cell-mediated suppression contributes to suboptimal local immune responses.
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Press D, Mutlu S, Güçlü B. Evidence of fast serotonin transmission in frog slowly adapting type 1 responses. Somatosens Mot Res 2010; 27:174-85. [PMID: 20937000 DOI: 10.3109/08990220.2010.516670] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Merkel cell-neurite (MCN) complex generates slowly adapting type 1 (SA1) response when mechanically stimulated. Both serotonin (5-HT) and glutamate have been implicated in the generation of normal SA1 responses, but previous studies have been inconclusive as to what their roles are or how synaptic transmission occurs. In this study, excised dorsal skin patches from common water frogs (Rana ridibunda) were stimulated by von Frey hairs during perfusion in a tissue bath, and single-unit spike activity was recorded from SA1 fibres. Serotonin had no significant effect on the SA1 response at low (10 µM) concentration, significantly increased activity in a force-independent manner at 100 µM, but decreased activity with reduced responsiveness to force at 1 mM. Glutamate showed no effect on the responsiveness to force at 100 µM. MDL 72222 (100 µM), an ionotropic 5-HT3 receptor antagonist, completely abolished the responsiveness to force, suggesting that serotonin is released from Merkel cells as a result of mechanical stimulation, and activated 5-HT3 receptors on the neurite. The metabotropic 5-HT2 receptor antagonist, ketanserin, greatly reduced the SA1 fibre's responsiveness to force, as did the non-specific glutamate receptor antagonist, kynurenic acid. This supports a role for serotonin and glutamate as neuromodulators in the MCN complex, possibly by activation and/or inhibition of signalling cascades in the Merkel cell associated with vesicle release. Additionally, it was observed that SA1 responses contained a force-independent component, similar to a dynamic response observed during mechanical vibrations.
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Affiliation(s)
- Daniel Press
- Biomedical Engineering Institute, Boğaziçi University, İstanbul, Turkey
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Fujii M, Yi KS, Kim MJ, Ha SH, Ryu SH, Suh PG, Yagisawa H. Phosphorylation of phospholipase C-delta 1 regulates its enzymatic activity. J Cell Biochem 2009; 108:638-50. [PMID: 19681039 DOI: 10.1002/jcb.22297] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Phosphorylation of phospholipase C-delta(1) (PLC-delta(1)) in vitro and in vivo was investigated. Of the serine/threonine kinases tested, protein kinase C (PKC) phosphorylated the serine residue(s) of bacterially expressed PLC-delta(1) most potently. It was also demonstrated that PLC-delta(1) directly bound PKC-alpha via its pleckstrin homology (PH) domain. Using deletion mutants of PLC-delta(1) and synthetic peptides, Ser35 in the PH domain was defined as the PKC mediated in vitro phosphorylation site of PLC-delta(1). In vitro phosphorylation of PLC-delta(1) by PKC stimulated [(3)H]PtdIns(4,5)P(2) hydrolyzing activity and [(3)H]Ins(1,4,5)P(3)-binding of the PLC-delta(1). On the other hand, endogenous PLC-delta(1) was constitutively phosphorylated and phosphoamino acid analysis revealed that major phosphorylation sites were threonine residues in quiescent cells. The phosphorylation level and the species of phosphoamino acid were not changed by various stimuli such as PMA, EGF, NGF, and forskolin. Using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, we determined that Thr209 of PLC-delta(1) is one of the constitutively phosphorylated sites in quiescent cells. The PLC activity was potentiated when constitutively phosphorylated PLC-delta(1) was dephosphorylated by endogenous phosphatase(s) in vitro. Additionally, coexpression with PKC-alpha reduced serine phosphorylation of PLC-delta(1) detected by an anti-phosphoserine antibody and PLC-delta(1)-dependent basal production of inositol phosphates in NIH-3T3 cells, suggesting PKC-alpha activates phosphatase or inactivates another kinase involved in PLC-delta(1) serine phosphorylation to modulate the PLC-delta(1) activity in vivo. Taken together, these results suggest that PLC-delta(1) has multiple phosphorylation sites and phosphorylation status of PLC-delta(1) regulates its activity positively or negatively depends on the phosphorylation sites.
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Affiliation(s)
- Makoto Fujii
- Graduate School of Life Science, University of Hyogo, Harima Science Garden City, Hyogo 678-1297, Japan
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Matsuoka I, Ito M. [Negative regulatory mechanism of phospholipase C signaling triggered by G protein-coupled receptor]. Nihon Yakurigaku Zasshi 2009; 134:254-258. [PMID: 19915284 DOI: 10.1254/fpj.134.254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Siso-Nadal F, Fox JJ, Laporte SA, Hébert TE, Swain PS. Cross-talk between signaling pathways can generate robust oscillations in calcium and cAMP. PLoS One 2009; 4:e7189. [PMID: 19844582 PMCID: PMC2760754 DOI: 10.1371/journal.pone.0007189] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 09/03/2009] [Indexed: 11/18/2022] Open
Abstract
Background To control and manipulate cellular signaling, we need to understand cellular strategies for information transfer, integration, and decision-making. A key feature of signal transduction is the generation of only a few intracellular messengers by many extracellular stimuli. Methodology/Principal Findings Here we model molecular cross-talk between two classic second messengers, cyclic AMP (cAMP) and calcium, and show that the dynamical complexity of the response of both messengers increases substantially through their interaction. In our model of a non-excitable cell, both cAMP and calcium concentrations can oscillate. If mutually inhibitory, cross-talk between the two second messengers can increase the range of agonist concentrations for which oscillations occur. If mutually activating, cross-talk decreases the oscillation range, but can generate ‘bursting’ oscillations of calcium and may enable better filtering of noise. Conclusion We postulate that this increased dynamical complexity allows the cell to encode more information, particularly if both second messengers encode signals. In their native environments, it is unlikely that cells are exposed to one stimulus at a time, and cross-talk may help generate sufficiently complex responses to allow the cell to discriminate between different combinations and concentrations of extracellular agonists.
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Affiliation(s)
- Fernando Siso-Nadal
- Gene Network Sciences, Cambridge, Massachusetts, United States of America
- Centre for Non-linear Dynamics, McGill University, Montreal, Canada
| | - Jeffrey J. Fox
- Centre for Applied Mathematics, Cornell University, Ithaca, New York, United States of America
| | - Stéphane A. Laporte
- Department of Medicine, McGill University, Montreal, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Terence E. Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Peter S. Swain
- Centre for Non-linear Dynamics, McGill University, Montreal, Canada
- Centre for Systems Biology at Edinburgh, University of Edinburgh, Edinburgh, Scotland
- * E-mail:
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Tawfeek HAW, Abou-Samra AB. Negative regulation of parathyroid hormone (PTH)-activated phospholipase C by PTH/PTH-related peptide receptor phosphorylation and protein kinase A. Endocrinology 2008; 149:4016-23. [PMID: 18450967 PMCID: PMC2488210 DOI: 10.1210/en.2007-1375] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PTH binding to the PTH/PTHrP receptor activates adenylate cyclase/protein kinase A (PKA) and phospholipase C (PLC) pathways and increases receptor phosphorylation. The mechanisms regulating PTH activation of PLC signaling are poorly understood. In the current study, we explored the role of PTH/PTHrP receptor phosphorylation and PKA in PTH activation of PLC. When treated with PTH, LLCPK-1 cells stably expressing a green fluorescent protein (GFP)-tagged wild-type (WT) PTH/PTHrP receptor show a small dose-dependent increase in PLC signaling as measured by inositol trisphosphate accumulation assay. In contrast, PTH treatment of LLCPK-1 cells stably expressing a GFP-tagged receptor mutated in its carboxyl-terminal tail so that it cannot be phosphorylated (PD-GFP) results in significantly higher PLC activation (P<0.001). The effects of PTH on PLC activation are dose dependent and reach maximum at the 100 nm PTH dose. When WT receptor-expressing cells are pretreated with H89, a specific inhibitor of PKA, PTH activation of PLC signaling is enhanced in a dose-dependent manner. H89 pretreatment in PD-GFP cells causes a further increase in PLC activation in response to PTH treatment. Interestingly, PTH and forskolin (adenylate cyclase/PKA pathway activator) treatment causes an increase in PLCbeta3 phosphorylation at the Ser1105 inhibitory site and that increase is blocked by the PKA inhibitor, H89. Expression of a mutant PLCbeta3 in which Ser1105 was mutated to alanine (PLCbeta3-SA), in WT or PD cells increases PTH stimulation of inositol 1,4,5-trisphosphate formation. Altogether, these data suggest that PTH signaling to PLC is negatively regulated by PTH/PTHrP receptor phosphorylation and PKA. Furthermore, phosphorylation at Ser1105 is demonstrated as a regulatory mechanism of PLCbeta3 by PKA.
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Affiliation(s)
- Hesham A W Tawfeek
- Endocrine Unit, Massachusetts General Hospital, 55 Fruit Street, Thier 1051, Boston, Massachusetts 02114, USA.
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Zhong M, Murtazina DA, Phillips J, Ku CY, Sanborn BM. Multiple signals regulate phospholipase CBeta3 in human myometrial cells. Biol Reprod 2008; 78:1007-17. [PMID: 18322273 DOI: 10.1095/biolreprod.107.064485] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Phospholipase CB3 (PLCB3) serine(1105) (S(1105)), a substrate for multiple protein kinases, represents a potential point of convergence of several signaling pathways in the myometrium. To explore this hypothesis, the regulation of PLCB3-S(1105) phosphorylation (P-S(1105)) was studied in immortalized and primary human myometrial cells. 8-[4-chlorophenylthio] (CPT)-cAMP and calcitonin gene-related peptide (CALCA) transiently increased P-S(1105). Relaxin also stimulated P-S(1105); this effect was partially blocked by the protein kinase A (PRKA) inhibitor, Rp-8-CPT-cAMPS. Oxytocin, which stimulates Galphaq-mediated pathways, also rapidly increased P-S(1105), as did prostaglandin F2alpha and ATP. Oxytocin-stimulated phosphorylation was blocked by protein kinase C (PRKC) inhibitor Go6976 and by pretreatment overnight with a phorbol ester. Cypermethrin, a PP2B phosphatase inhibitor, but not okadaic acid, a PP1/PP2A inhibitor, prolonged the effect of CALCA on P-S(1105), whereas the reverse was the case for the oxytocin-stimulated increase in P-S(1105). PLCB3 was the predominant PLC isoform expressed in the myometrial cells and PLCB3 short hairpin RNA constructs significantly attenuated oxytocin-stimulated increases in intracellular calcium. oxytocin-induced phosphatidylinositol (PI) turnover was inhibited by CPT-cAMP and okadaic acid, but was enhanced by pretreatment with Go6976. CPT-cAMP inhibited oxytocin-stimulated PI turnover in the presence of overexpressed PLCB3, but not overexpressed PLCB3-S(1105)A. These data demonstrate that both negative crosstalk from the cAMP/PRKA pathway and a negative feedback loop in the oxytocin/G protein/PLCB pathway involving PRKC operate in myometrial cells and suggest that different protein phosphatases predominate in mediating P-S(1105) dephosphorylation in these pathways. The integration of multiple signal components at the level of PLCB3 may be important to its function in the myometrium.
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Affiliation(s)
- Miao Zhong
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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Burelout C, Thibault N, Harbour D, Naccache PH, Bourgoin SG. The PGE2-induced inhibition of the PLD activation pathway stimulated by fMLP in human neutrophils is mediated by PKA at the PI3-Kgamma level. Biochem Pharmacol 2007; 74:730-41. [PMID: 17631865 DOI: 10.1016/j.bcp.2007.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 06/07/2007] [Accepted: 06/11/2007] [Indexed: 11/21/2022]
Abstract
Prostaglandin E2 (PGE2), an eicosanoid that modulates inflammation, inhibits several chemoattractant-elicited functions in neutrophils such as chemotaxis, production of superoxide anions, adhesion, secretion of cytotoxic enzymes and synthesis of leukotriene B4. We previously reported that PGE2 inhibits the fMLP signaling pathway that leads to PLD activation through suppression of PI3-Kgamma activity and the decreased recruitment to membranes of PLD activation factors, PKC, Rho and Arf-GTPases. This effect is mediated via the EP2 receptors known to raise cAMP in cells. The inhibition of most fMLP-induced functional responses by PGE2 via EP2 receptors is mediated by PKA, except the chemotactic response. We have investigated the role of PKA in the EP2-mediated inhibition of the PLD activation pathway. H-89, a selective PKA pharmacological inhibitor suppressed the inhibitory effects of PGE2 at all stages of the PLD pathway activated by fMLP, i.e. PLD activity, translocation to membranes of PKCalpha, Rho and Arf-GTPases, calcium influx, tyrosine phosphorylation of proteins and finally translocation of p110gamma catalytic subunit of PI3-K to membranes. However, neither PLD nor PI3-Kgamma was substrate of PKA. These data provide evidence that PGE2-stimulated PKA activity regulates the PLD pathway stimulated by fMLP at the level of PI3-Kgamma and that the inhibition of PI3-Kgamma activation by PKA is a complex mechanism that remains to be completely elucidated.
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Affiliation(s)
- Chantal Burelout
- Centre de Recherche en Rhumatologie-Immunologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Département d'Anatomie-Physiologie, Québec, Canada
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Yuan W, López Bernal A. Cyclic AMP signalling pathways in the regulation of uterine relaxation. BMC Pregnancy Childbirth 2007; 7 Suppl 1:S10. [PMID: 17570154 PMCID: PMC1892051 DOI: 10.1186/1471-2393-7-s1-s10] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Studying the mechanism(s) of uterine relaxation is important and will be helpful in the prevention of obstetric difficulties such as preterm labour, which remains a major cause of perinatal mortality and morbidity. Multiple signalling pathways regulate the balance between maintaining relative uterine quiescence during gestation, and the transition to the contractile state at the onset of parturition. Elevation of intracellular cyclic AMP promotes myometrial relaxation, and thus quiescence, via effects on multiple intracellular targets including calcium channels, potassium channels and myosin light chain kinase. A complete understanding of cAMP regulatory pathways (synthesis and hydrolysis) would assist in the development of better tocolytics to delay or inhibit preterm labour. Here we review the enzymes involved in cAMP homoeostasis (adenylyl cyclases and phosphodiesterases) and possible myometrial substrates for the cAMP dependent protein kinase. We must emphasise the need to identify novel pharmacological targets in human pregnant myometrium to achieve safe and selective uterine relaxation when this is indicated in preterm labour or other obstetric complications.
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Affiliation(s)
- Wei Yuan
- University of Bristol, Clinical Science at South Bristol (Obstetrics and Gynaecology), St Michael's Hospital and Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Andrés López Bernal
- University of Bristol, Clinical Science at South Bristol (Obstetrics and Gynaecology), St Michael's Hospital and Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
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Blanks AM, Shmygol A, Thornton S. Preterm labour. Myometrial function in prematurity. Best Pract Res Clin Obstet Gynaecol 2007; 21:807-19. [PMID: 17446138 DOI: 10.1016/j.bpobgyn.2007.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The primary function of the uterus during gestation is to harbour the growing conceptus in a largely quiescent environment. Upon maturation of the fetus to a point sufficient for extrauterine survival, the uterus must remodel itself sufficiently to generate forceful contractions during labour. During preterm delivery, the process of remodelling of the myometrium occurs early due to a number of different causes, although the underlying basis for myometrial contraction remains the same. This review summarises the anatomical, physiological and molecular basis for contraction. We describe the fibre structure of the human uterus and how this relates to the spread of electrical excitation during a contraction. The process of excitation within a single myometrial cell is described, as well as how this relates to contraction. We then focus on how excitation-contraction coupling is modulated by intercellular communication, pharmacomechanical-coupling and hormonal milieu. Lastly, we consider the actions of the commonly accepted uterine agonists oxytocin, prostaglandin F(2alpha), and prostaglandin E(2), and the tocolytic ritodrine.
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Affiliation(s)
- Andrew M Blanks
- Clinical Sciences Research Institute, University of Warwick, University Hospitals of Coventry and Warwickshire, Clifford Bridge Road, Coventry CV2 2DX, UK.
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Chen L, Bohanick JD, Nishihara M, Seamans JK, Yang CR. Dopamine D1/5 receptor-mediated long-term potentiation of intrinsic excitability in rat prefrontal cortical neurons: Ca2+-dependent intracellular signaling. J Neurophysiol 2007; 97:2448-64. [PMID: 17229830 DOI: 10.1152/jn.00317.2006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prefrontal cortex (PFC) dopamine D1/5 receptors modulate long- and short-term neuronal plasticity that may contribute to cognitive functions. Synergistic to synaptic strength modulation, direct postsynaptic D1/5 receptor activation also modulates voltage-dependent ionic currents that regulate spike firing, thus altering the neuronal input-output relationships in a process called long-term potentiation of intrinsic excitability (LTP-IE). Here, the intracellular signals that mediate this D1/5 receptor-dependent LTP-IE were determined using whole cell current-clamp recordings in layer V/VI rat pyramidal neurons from PFC slices. After blockade of all major amino acid receptors (V(hold) = -65 mV) brief tetanic stimulation (20 Hz) of local afferents or application of the D1 agonist SKF81297 (0.2-50 microM) induced LTP-IE, as shown by a prolonged (>40 min) increase in depolarizing pulse-evoked spike firing. Pretreatment with the D1/5 antagonist SCH23390 (1 microM) blocked both the tetani- and D1/5 agonist-induced LTP-IE, suggesting a D1/5 receptor-mediated mechanism. The SKF81297-induced LTP-IE was significantly attenuated by Cd(2+), [Ca(2+)](i) chelation, by inhibition of phospholipase C, protein kinase-C, and Ca(2+)/calmodulin kinase-II, but not by inhibition of adenylate cyclase, protein kinase-A, MAP kinase, or L-type Ca(2+) channels. Thus this form of D1/5 receptor-mediated LTP-IE relied on Ca(2+) influx via non-L-type Ca(2+) channels, activation of PLC, intracellular Ca(2+) elevation, activation of Ca(2+)-dependent CaMKII, and PKC to mediate modulation of voltage-dependent ion channel(s). This D1/5 receptor-mediated modulation by PKC coexists with the previously described PKA-dependent modulation of K(+) and Ca(2+) currents to dynamically regulate overall excitability of PFC neurons.
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Affiliation(s)
- Long Chen
- National Standard Lab of Pharmacology for Chinese Materia Medica, Research Center of Acupuncture and Pharmacology, Nanjing University of Traditional Chinese Medicine, Nanjing, China
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McCullar JS, Malencik DA, Vogel WK, Crofoot KM, Anderson SR, Filtz TM. Calmodulin potentiates G beta gamma activation of phospholipase C-beta3. Biochem Pharmacol 2007; 73:270-8. [PMID: 17118346 PMCID: PMC1866284 DOI: 10.1016/j.bcp.2006.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 10/05/2006] [Accepted: 10/09/2006] [Indexed: 11/25/2022]
Abstract
Phospholipase C-beta (PLC-beta) isozymes (EC 3.1.4.11) hydrolyze the membrane phospholipid phosphatidylinositol-4,5-bisphosphate to generate intracellular second messenger signaling molecules inositol-1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) in response to receptor activation and other cellular stimuli. PLCbeta1 and PLCbeta3 isozymes were previously demonstrated to bind the calcium-sensitive molecule calmodulin [McCullar JS, Larsen SA, Millimaki RA, Filtz TM. Calmodulin is a phospholipase C-{beta} interacting protein. J Biol Chem 2003;278(36):33708-13]. We have now shown through fluorescence anisotropy that calmodulin/PLCbeta3 affinities increase with increasing calcium in a physiologically relevant concentration range. The bimolecular affinity constants for calmodulin interaction with PLCbeta1 or PLCbeta3 were estimated as 260 and 200 nM, respectively, from fluorescence anisotropy data. There was no effect of calmodulin on basal or G alpha q-stimulated catalytic activity for either isozyme. However, the interaction between calmodulin and PLCbeta3 leads to potentiation of activation by the G-protein beta gamma dimer in an in vitro assay. 1321N1 cells treated with calmodulin inhibitors concurrent with and post-stimulation of muscarinic receptors significantly reduced [3H]PIP hydrolysis. Together these data are suggestive of cooperative role for calmodulin in the G-protein beta gamma dimer-stimulated activity of PLCbeta3.
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Affiliation(s)
- Jennifer S McCullar
- Molecular and Cellular Biology Graduate Program, Oregon State University, Corvallis, OR 97331, USA
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Huang J, Zhou H, Mahavadi S, Sriwai W, Murthy KS. Inhibition of Gαq-dependent PLC-β1 activity by PKG and PKA is mediated by phosphorylation of RGS4 and GRK2. Am J Physiol Cell Physiol 2007; 292:C200-8. [PMID: 16885398 DOI: 10.1152/ajpcell.00103.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In smooth muscle of the gut, Gq-coupled receptor agonists activate preferentially PLC-β1 to stimulate phosphoinositide (PI) hydrolysis and inositol 1,4,5-trisphosphate (IP3) generation and induce IP3-dependent Ca2+ release. Inhibition of Ca2+ mobilization by cAMP- (PKA) and cGMP-dependent (PKG) protein kinases reflects inhibition of PI hydrolysis by both kinases and PKG-specific inhibitory phosphorylation of IP3 receptor type I. The mechanism of inhibition of PLC-β1-dependent PI hydrolysis has not been established. Neither Gq nor PLC-β1 was directly phosphorylated by PKA or PKG in gastric smooth muscle cells. However, both kinases 1) phosphorylated regulator of G protein signaling 4 (RGS4) and induced its translocation from cytosol to plasma membrane, 2) enhanced ACh-stimulated association of RGS4 and Gαq·GTP and intrinsic Gαq·GTPase activity, and 3) inhibited ACh-stimulated PI hydrolysis. RGS4 phosphorylation and inhibition of PI hydrolysis were blocked by selective PKA and PKG inhibitors. Expression of RGS4(S52A), which lacks a PKA/PKG phosphorylation site, blocked the increase in GTPase activity and the decrease in PI hydrolysis induced by PKA and PKG. Blockade of PKA-dependent effects was only partial. Selective phosphorylation of G protein-coupled receptor kinase 2 (GRK2), which contains a RGS domain, by PKA augmented ACh-stimulated GRK2:Gαq·GTP association; both effects were blocked in cells expressing GRK2(S685A), which lacks a PKA phosphorylation site. Inhibition of PI hydrolysis induced by PKA was partly blocked in cells expressing GRK2(S685A) and completely blocked in cells coexpressing GRK2(S685A) and RGS4(S52A) or Gαq(G188S), a Gαq mutant that binds GRK2 but not RGS4. The results demonstrate that inhibition of PLC-β1-dependent PI hydrolysis by PKA is mediated via stimulatory phosphorylation of RGS4 and GRK2, leading to rapid inactivation of Gαq·GTP. PKG acts only via phosphorylation of RGS4.
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Affiliation(s)
- Jiean Huang
- Medical College of Virginia Campus, Virginia Commonwealth University, PO Box 980551, Richmond, VA 23298, USA
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Kim YH, Song M, Oh YS, Heo K, Choi JW, Park JM, Kim SH, Lim S, Kwon HM, Ryu SH, Suh PG. Inhibition of phospholipase C-beta1-mediated signaling by O-GlcNAc modification. J Cell Physiol 2006; 207:689-96. [PMID: 16538662 DOI: 10.1002/jcp.20609] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Here we report inhibition of phospholipase C-beta1 (PLC-beta1)-mediated signaling by post-translational glycosylation with beta-N-acetylglucosamine (O-GlcNAc modification). In C2C12 myoblasts, isoform-specific knock-down experiments using siRNA showed that activation of bradykinin (BK) receptor led to stimulation of PLC-beta1 and subsequent intracellular Ca2+ mobilization. In C2C12 myotubes, O-GlcNAc modification of PLC-beta1 was markedly enhanced in response to treatment with glucosamine (GlcNH2), an inhibitor of O-GlcNAase (PUGNAc) and hyperglycemia. This was associated with more than 50% inhibition of intracellular production of IP3 and Ca2+ mobilization in response to BK. Since the abundance of PLC-beta1 remained unchanged, these data suggest that O-GlcNAc modification of PLC-beta1 led to inhibition of its activity. Moreover, glucose uptake stimulated by BK was significantly blunted by treatment with PUGNAc. These data support the notion that O-GlcNAc modification negatively modulates the activity of PLC-beta1.
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Affiliation(s)
- Yun-Hee Kim
- Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, Korea
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Hillhouse EW, Grammatopoulos DK. The molecular mechanisms underlying the regulation of the biological activity of corticotropin-releasing hormone receptors: implications for physiology and pathophysiology. Endocr Rev 2006; 27:260-86. [PMID: 16484629 DOI: 10.1210/er.2005-0034] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The CRH receptor (CRH-R) is a member of the secretin family of G protein-coupled receptors. Wide expression of CRH-Rs in the central nervous system and periphery ensures that their cognate agonists, the family of CRH-like peptides, are capable of exerting a wide spectrum of actions that underpin their critical role in integrating the stress response and coordinating the activity of fundamental physiological functions, such as the regulation of the cardiovascular system, energy balance, and homeostasis. Two types of mammal CRH-R exist, CRH-R1 and CRH-R2, each with unique splicing patterns and remarkably distinct pharmacological properties, but similar signaling properties, probably reflecting their distinct and sometimes contrasting biological functions. The regulation of CRH-R expression and activity is not fully elucidated, and we only now begin to fully understand the impact on mammalian pathophysiology. The focus of this review is the current and evolving understanding of the molecular mechanisms controlling CRH-R biological activity and functional flexibility. This shows notable tissue-specific characteristics, highlighted by their ability to couple to distinct G proteins and activate tissue-specific signaling cascades. The type of activating agonist, receptor, and target cell appears to play a major role in determining the overall signaling and biological responses in health and disease.
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Affiliation(s)
- Edward W Hillhouse
- The Leeds Institute of Genetics, Health and Therapeutics, The University of Leeds, Leeds LS2 9NL, UK.
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Sanborn BM, Ku CY, Shlykov S, Babich L. Molecular signaling through G-protein-coupled receptors and the control of intracellular calcium in myometrium. ACTA ACUST UNITED AC 2006; 12:479-87. [PMID: 16202924 DOI: 10.1016/j.jsgi.2005.07.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Indexed: 11/30/2022]
Abstract
Cellular mechanisms regulating myometrial intracellular free calcium (Ca2+(i)) are addressed in this review, with emphasis on G-protein-coupled receptor pathways. An increase in myometrial Ca2+(i) results in phosphorylation of myosin light chain, an increase in myosin adenosine monophosphatase (ATPase) activity and contraction. Dephosphorylation of myosin light chain and a decline in Ca2+(i) are associated with relaxation. Increases in Ca2+(i) are controlled by multiple signaling pathways, including receptor-mediated activation of phospholipase Cbeta (PLCbeta), leading to release of Ca2+ from intracellular stores. Ca2+ also enters myometrial cells through plasma membrane Ca2+ channels. Conversely, adenosine triphosphate (ATP)-dependent Ca2+ pumps lower Ca2+(i) concentrations and potassium channels promote hyperpolarization that can decrease Ca2+ entry. Receptor-coupled pathways that promote uterine relaxation primarily involve activation of cyclic adenosine monophosphate (cAMP)- or cyclic guanosine monophosphate (cGMP)-stimulated protein kinases that phosphorylate proteins regulating Ca2+ homeostasis. cAMP has inhibitory effects on myometrial contractile activity, agonist-stimulated phosphatidylinositide turnover and increases in Ca2+(i). Some of these effects require association of protein kinase A (PKA) with a plasma membrane-associated A-kinase-anchoring-protein (AKAP). Near term in the rat, there is a decline in the plasma membrane localization of PKA associated with this anchoring protein. This correlates with changes in the regulation of signaling pathways controlling Ca2+(i). L-type voltage-operated Ca2+ entry is an important regulator of myometrial contraction. In addition, putative signal-regulated or capacitative Ca2+ channel proteins, TrpCs, are expressed in myometrium, and signal-regulated Ca2+ entry is observed in human myometrial cells. This Ca2+ entry mechanism may play a significant role in the control of myometrial Ca2+(i) dynamics and myometrial contraction. The regulation of myometrial Ca2+(i) is complex. Understanding the mechanisms involved may lead to design of tocolytics that target multiple pathways and achieve improved suppression of premature labor.
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Affiliation(s)
- Barbara M Sanborn
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
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Bai Y, Sanderson MJ. Airway smooth muscle relaxation results from a reduction in the frequency of Ca2+ oscillations induced by a cAMP-mediated inhibition of the IP3 receptor. Respir Res 2006; 7:34. [PMID: 16504084 PMCID: PMC1459146 DOI: 10.1186/1465-9921-7-34] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 02/23/2006] [Indexed: 01/08/2023] Open
Abstract
Background It has been shown that the contractile state of airway smooth muscle cells (SMCs) in response to agonists is determined by the frequency of Ca2+ oscillations occurring within the SMCs. Therefore, we hypothesized that the relaxation of airway SMCs induced by agents that increase cAMP results from the down-regulation or slowing of the frequency of the Ca2+ oscillations. Methods The effects of isoproterenol (ISO), forskolin (FSK) and 8-bromo-cAMP on the relaxation and Ca2+ signaling of airway SMCs contracted with methacholine (MCh) was investigated in murine lung slices with phase-contrast and laser scanning microscopy. Results All three cAMP-elevating agents simultaneously induced a reduction in the frequency of Ca2+ oscillations within the SMCs and the relaxation of contracted airways. The decrease in the Ca2+ oscillation frequency correlated with the extent of airway relaxation and was concentration-dependent. The mechanism by which cAMP reduced the frequency of the Ca2+ oscillations was investigated. Elevated cAMP did not affect the re-filling rate of the internal Ca2+ stores after emptying by repetitive exposure to 20 mM caffeine. Neither did elevated cAMP limit the Ca2+ available to stimulate contraction because an elevation of intracellular Ca2+ concentration induced by exposure to a Ca2+ ionophore (ionomycin) or by photolysis of caged-Ca2+ did not reverse the effect of cAMP. Similar results were obtained with iberiotoxin, a blocker of Ca2+-activated K+ channels, which would be expected to increase Ca2+ influx and contraction. By contrast, the photolysis of caged-IP3 in the presence of agonist, to further elevate the intracellular IP3 concentration, reversed the slowing of the frequency of the Ca2+ oscillations and relaxation of the airway induced by FSK. This result implied that the sensitivity of the IP3R to IP3 was reduced by FSK and this was supported by the reduced ability of IP3 to release Ca2+ in SMCs in the presence of FSK. Conclusion These results indicate that the relaxant effect of cAMP-elevating agents on airway SMCs is achieved by decreasing the Ca2+ oscillation frequency by reducing internal Ca2+ release through IP3 receptors.
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Affiliation(s)
- Yan Bai
- Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Michael J Sanderson
- Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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Atzori M, Kanold PO, Pineda JC, Flores-Hernandez J, Paz RD. Dopamine prevents muscarinic-induced decrease of glutamate release in the auditory cortex. Neuroscience 2005; 134:1153-65. [PMID: 16019151 DOI: 10.1016/j.neuroscience.2005.05.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Revised: 05/07/2005] [Accepted: 05/11/2005] [Indexed: 10/25/2022]
Abstract
Acetylcholine and dopamine are simultaneously released in the cortex at the occurrence of novel stimuli. In addition to a series of excitatory effects, acetylcholine decreases the release of glutamate acting on presynaptic muscarinic receptors. By recording evoked excitatory postsynaptic currents in layers II/III neurons of the auditory cortex, we found that activation of muscarinic receptors by oxotremorine reduces the amplitude of glutamatergic current (A(oxo)/A(ctr) = 0.53 +/- 0.17) in the absence but not in the presence of dopamine (A(oxo)/A(ctr) = 0.89 +/- 0.12 in 20 microM dopamine). These data suggested that an excessive sensitivity to dopamine, such as postulated in schizophrenia, could prevent the decrease of glutamate release associated with the activation of cholinergic corticopetal nuclei. Thus, a possible mechanism of action of antipsychotic drugs could be through a depression of the glutamatergic signal in the auditory cortex. We tested the capability of haloperidol, clozapine and lamotrigine to affect glutamatergic synaptic currents and their muscarinic modulation. We found that antipsychotics not only work as dopamine receptor antagonists in re-establishing muscarinic modulation, but also directly depress glutamatergic currents. These results suggest that presynaptic modulation of glutamate release can account for a dual route of action of antipsychotic drugs.
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Affiliation(s)
- M Atzori
- University of Texas at Dallas, School for Behavioral and Brain Sciences, Richardson, 75080, USA.
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Abstract
Relaxin exhibits pleiotropic effects on reproductive and nonreproductive tissues; the signaling mechanisms underlying these functions are still not well understood. Activation of protein kinase A and several other signal-regulated protein kinases results in the phosphorylation of phospholipase C (PLC)-beta3 and inhibit Galpha(q)-stimulated PLC activity. Therefore, PLCbeta3 may be targeted by both contractant and relaxant signaling pathways in myometrium and play a critical role in the balance between them. PHM1 cells express mRNA for relaxin receptor LGR7, and relaxin inhibits oxytocin-stimulated PLC activity in these cells. Thus, this model system may be useful in delineating signaling pathways used by relaxin. Here, we present evidence that relaxin stimulates phosphorylation of PLCbeta3 in PHM1 cells.
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Affiliation(s)
- Miao Zhong
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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Tintinger G, Steel HC, Anderson R. Taming the neutrophil: calcium clearance and influx mechanisms as novel targets for pharmacological control. Clin Exp Immunol 2005; 141:191-200. [PMID: 15996182 PMCID: PMC1809444 DOI: 10.1111/j.1365-2249.2005.02800.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neutrophils are relatively insensitive to the anti-inflammatory actions of conventional chemotherapeutic agents, including corticosteroids, emphasizing the requirement for novel pharmacological strategies to control the potentially harmful proinflammatory activities of these cells. In the case of commonly-occurring inflammatory diseases of the airways, the neutrophil is the primary mediator of inflammation in conditions such as chronic obstructive pulmonary disease, cystic fibrosis, acute respiratory distress syndrome, bronchiectasis and non-eosinophilic bronchial asthma. Recent insights into the mechanisms utilized by neutrophils to restore Ca(2+) homeostasis following activation with Ca(2+)-mobilizing, proinflammatory stimuli have facilitated the identification of novel targets for anti-inflammatory chemotherapy in these cells. The most amenable of these from a chemotherapeutic perspective, is the cyclic AMP-dependent protein kinase-modulated endomembrane Ca(2+)-ATPase which promotes clearance of the cation from the cytosol of activated neutrophils. Second generation type 4 phosphodiesterase inhibitors and adenosine receptor agonists operative at the level of subtype A2A adenosine receptors, which are currently undergoing clinical and preclinical assessment respectively, hold promise as pharmacologic modulators during the restoration of Ca(2+) homeostasis. If this promise is realized, it may result in novel chemotherapeutic strategies for the control of hyperacute and chronic inflammatory conditions in which neutrophils are primary offenders. Alternative, potential future targets include the Na(+), Ca(2+)-exchanger and store-operated Ca(2+) channels, which cooperate in the refilling of intracellular Ca(2+) stores.
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Affiliation(s)
- G Tintinger
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, Faculty of Health Sciences, University of Pretoria, South Africa
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Agassandian M, Zhou J, Tephly LA, Ryan AJ, Carter AB, Mallampalli RK. Oxysterols inhibit phosphatidylcholine synthesis via ERK docking and phosphorylation of CTP:phosphocholine cytidylyltransferase. J Biol Chem 2005; 280:21577-87. [PMID: 15788406 DOI: 10.1074/jbc.m412409200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Surfactant deficiency contributes to acute lung injury and may result from the elaboration of bioactive lipids such as oxysterols. We observed that the oxysterol 22-hydroxycholesterol (22-HC) in combination with its obligate partner, 9-cis-retinoic acid (9-cis-RA), decreased surfactant phosphatidylcholine (PtdCho) synthesis by increasing phosphorylation of the regulatory enzyme CTP:phosphocholine cytidylyltransferase-alpha (CCTalpha). Phosphorylation of CCTalpha decreased its activity. 22-HC/9-cis-RA inhibition of PtdCho synthesis was blocked by PD98059 or dominant-negative ERK (p42 kinase). Overexpression of constitutively active MEK1, the kinase upstream of p42 kinase, increased CCTalpha phosphorylation. Expression of truncated CCTalpha mutants lacking proline-directed sites within the C-terminal phosphorylation domain partially blocked oxysterol-mediated inhibition of PtdCho synthesis. Mutagenesis of Ser315 within CCTalpha was both required and sufficient to confer significant resistance to 22-HC/9-cis-RA inhibition of PtdCho synthesis. A novel putative ERK-docking domain N-terminal to this phosphoacceptor site was mapped within the CCTalpha membrane-binding domain (residues 287-300). The results are the first demonstration of a physiologically relevant phosphorylation site and docking domain within CCTalpha that serve as targets for ERKs, resulting in inhibition of surfactant synthesis.
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Affiliation(s)
- Marianna Agassandian
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City 52242, USA
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Saito SY, Maruyama Y, Kamiyama S, Nakahata N, Ohizumi Y. Ephedrae herba in Mao-Bushi-Saishin-To inhibits IgE-mediated histamine release and increases cAMP content in RBL-2H3 cells. J Pharmacol Sci 2005; 95:41-6. [PMID: 15153649 DOI: 10.1254/jphs.95.41] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Acute effect of Mao-Bushi-Saishin-To (Ma-Huang-Fu-Zi-Xi-Xin-Tang in Chinese: MBS) on histamine release was investigated. The IgE-mediated anaphylaxic response in Wistar rats was significantly suppressed by MBS and Mao. However, Saishin and Bushi had no or little effect on the antigen-mediated anaphylaxic reaction. Mao as well as MBS but not Saishin nor Bushi inhibited IgE-mediated histamine release from rat basophilic leukemia (RBL-2H3) cells. Consistently, MBS and Mao but not Bushi nor Saishin increased cAMP levels in RBL-2H3 cells. However, ephedrine, methylephedrine, and pseudoephedrine, the main components in Mao, did not affect histamine release. From these results, increase of cAMP levels may account for the inhibitory effect of Mao on histamine release. Furthermore, these inhibitory actions of MBS were mainly due to Mao with an ingredient(s) different from ephedrines.
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Affiliation(s)
- Shin-ya Saito
- Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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