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Siew JJ, Chen HM, Chiu FL, Lee CW, Chang YM, Chen HL, Nguyen TNA, Liao HT, Liu M, Hagar HT, Sun YC, Lai HL, Kuo MH, Blum D, Buée L, Jin LW, Chen SY, Ko TM, Huang JR, Kuo HC, Liu FT, Chern Y. Galectin-3 aggravates microglial activation and tau transmission in tauopathy. J Clin Invest 2024; 134:e165523. [PMID: 37988169 PMCID: PMC10786694 DOI: 10.1172/jci165523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/16/2023] [Indexed: 11/23/2023] Open
Abstract
Alzheimer's disease is characterized by the accumulation of amyloid-β plaques, aggregation of hyperphosphorylated tau (pTau), and microglia activation. Galectin-3 (Gal3) is a β-galactoside-binding protein that has been implicated in amyloid pathology. Its role in tauopathy remains enigmatic. Here, we showed that Gal3 was upregulated in the microglia of humans and mice with tauopathy. pTau triggered the release of Gal3 from human induced pluripotent stem cell-derived microglia in both its free and extracellular vesicular-associated (EV-associated) forms. Both forms of Gal3 increased the accumulation of pathogenic tau in recipient cells. Binding of Gal3 to pTau greatly enhanced tau fibrillation. Besides Gal3, pTau was sorted into EVs for transmission. Moreover, pTau markedly enhanced the number of EVs released by iMGL in a Gal3-dependent manner, suggesting a role of Gal3 in biogenesis of EVs. Single-cell RNA-Seq analysis of the hippocampus of a mouse model of tauopathy (THY-Tau22) revealed a group of pathogenic tau-evoked, Gal3-associated microglia with altered cellular machineries implicated in neurodegeneration, including enhanced immune and inflammatory responses. Genetic removal of Gal3 in THY-Tau22 mice suppressed microglia activation, reduced the level of pTau and synaptic loss in neurons, and rescued memory impairment. Collectively, Gal3 is a potential therapeutic target for tauopathy.
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Affiliation(s)
| | | | - Feng-Lan Chiu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | | | | | | | | | | | - Mengyu Liu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Hsiao-Tien Hagar
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Yung-Chen Sun
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | | | - Min-Hao Kuo
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - David Blum
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France
- Alzheimer & Tauopathies, LabEx DISTALZ, LiCEND, Lille, France
| | - Luc Buée
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France
- Alzheimer & Tauopathies, LabEx DISTALZ, LiCEND, Lille, France
| | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine, University of California Davis, Sacramento, California, USA
| | | | - Tai-Ming Ko
- Institute of Biomedical Sciences
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Jie-Rong Huang
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hung-Chih Kuo
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
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Lee YH, Tsai YS, Chang CC, Ho CC, Shih HM, Chen HM, Lai HL, Lee CW, Lee YC, Liao YC, Yang UC, Cheng TH, Chern Y, Soong BW. A PIAS1 Protective Variant S510G Delays polyQ Disease Onset by Modifying Protein Homeostasis. Mov Disord 2021; 37:767-777. [PMID: 34951052 DOI: 10.1002/mds.28896] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/18/2021] [Accepted: 12/09/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Polyglutamine (polyQ) diseases are dominant neurodegenerative diseases caused by an expansion of the polyQ-encoding CAG repeats in the disease-causing gene. The length of the CAG repeats is the major determiner of the age at onset (AO) of polyQ diseases, including Huntington's disease (HD) and spinocerebellar ataxia type 3 (SCA3). OBJECTIVE We set out to identify common genetic variant(s) that may affect the AO of polyQ diseases. METHODS Three hundred thirty-seven patients with HD or SCA3 were enrolled for targeted sequencing of 583 genes implicated in proteinopathies. In total, 16 genes were identified as containing variants that are associated with late AO of polyQ diseases. For validation, we further investigate the variants of PIAS1 because PIAS1 is an E3 SUMO (small ubiquitin-like modifier) ligase for huntingtin (HTT), the protein linked to HD. RESULTS Biochemical analyses revealed that the ability of PIAS1S510G to interact with mutant huntingtin (mHTT) was less than that of PIAS1WT , resulting in lower SUMOylation of mHTT and lower accumulation of insoluble mHTT. Genetic knock-in of PIAS1S510G in a HD mouse model (R6/2) ameliorated several HD-like deficits (including shortened life spans, poor grip strength and motor coordination) and reduced neuronal accumulation of mHTT. CONCLUSIONS Our findings suggest that PIAS1 is a genetic modifier of polyQ diseases. The naturally occurring variant, PIAS1S510G , is associated with late AO in polyQ disease patients and milder disease severity in HD mice. Our study highlights the possibility of targeting PIAS1 or pathways governing protein homeostasis as a disease-modifying approach for treating patients with HD.
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Affiliation(s)
- Yan Hua Lee
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Shuen Tsai
- Center for Systems and Synthetic Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Che-Chang Chang
- The Ph.D. Program for Translational Medicine and International Ph.D. Program for Translational Science, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Chun-Chen Ho
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsiu-Ming Shih
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chia-Wei Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Taipei Veterans General Hospital, and Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, Taipei Veterans General Hospital, and Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ueng-Cheng Yang
- Center for Systems and Synthetic Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Tzu-Hao Cheng
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Institute of Biochemistry and Molecular Biology, and Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yijuang Chern
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Bing-Wen Soong
- Department of Neurology, Taipei Veterans General Hospital, and Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Neurology, Shuang Ho Hospital, and Taipei Neuroscience Institute, Taipei Medical University, Taipei, Taiwan
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3
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Lin CY, Lai HL, Chen HM, Siew JJ, Hsiao CT, Chang HC, Liao KS, Tsai SC, Wu CY, Kitajima K, Sato C, Khoo KH, Chern Y. Functional roles of ST8SIA3-mediated sialylation of striatal dopamine D 2 and adenosine A 2A receptors. Transl Psychiatry 2019; 9:209. [PMID: 31455764 PMCID: PMC6712005 DOI: 10.1038/s41398-019-0529-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 01/20/2023] Open
Abstract
Sialic acids are typically added to the end of glycoconjugates by sialyltransferases. Among the six ST8 α-N-acetyl-neuraminide α-2,8-sialyltransferases (ST8SIA) existing in adult brains, ST8SIA2 is a schizophrenia-associated gene. However, the in vivo substrates and physiological functions of most sialyltransferases are currently unknown. The ST8SIA3 is enriched in the striatum. Here, we showed that ablation of St8sia3 in mice (St8sia3-KO) led to fewer disialylated and trisialylated terminal glycotopes in the striatum of St8sia3-KO mice. Moreover, the apparent sizes of several striatum-enriched G-protein-coupled receptors (GPCRs) (including the adenosine A2A receptor (A2AR) and dopamine D1/D2 receptors (D1R and D2R)) were smaller in St8sia3-KO mice than in WT mice. A sialidase treatment removed the differences in the sizes of these molecules between St8sia3-KO and WT mice, confirming the involvement of sialylation. Expression of ST8SIA3 in the striatum of St8sia3-KO mice using adeno-associated viruses normalized the sizes of these proteins, demonstrating a direct role of ST8SIA3. The lack of ST8SIA3-mediated sialylation altered the distribution of these proteins in lipid rafts and the interaction between D2R and A2AR. Locomotor activity assays revealed altered pharmacological responses of St8sia3-KO mice to drugs targeting these receptors and verified that a greater population of D2R formed heteromers with A2AR in the striatum of St8sia3-KO mice. Since the A2AR-D2R heteromer is an important drug target for several basal ganglia diseases (such as schizophrenia and Parkinson's disease), the present study not only reveals a crucial role for ST8SIA3 in striatal functions but also provides a new drug target for basal ganglia-related diseases.
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Affiliation(s)
- Chien-Yu Lin
- 0000 0001 2287 1366grid.28665.3fInstitute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- 0000 0001 2287 1366grid.28665.3fInstitute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hui-Mei Chen
- 0000 0001 2287 1366grid.28665.3fInstitute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jian-Jing Siew
- 0000 0001 2287 1366grid.28665.3fInstitute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan ,0000 0001 0425 5914grid.260770.4Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
| | - Cheng-Te Hsiao
- 0000 0001 2287 1366grid.28665.3fInstitute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hua-Chien Chang
- 0000 0001 2287 1366grid.28665.3fInstitute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Kuo-Shiang Liao
- 0000 0001 2287 1366grid.28665.3fGenomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Shih-Chieh Tsai
- grid.36020.37Department of Research and Development, National Laboratory Animal Center, National Applied Research Laboratories, Taipei and Tainan, Taipei, Taiwan
| | - Chung-Yi Wu
- 0000 0001 2287 1366grid.28665.3fGenomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Ken Kitajima
- 0000 0001 0943 978Xgrid.27476.30Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-860 Japan
| | - Chihiro Sato
- 0000 0001 0943 978Xgrid.27476.30Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-860 Japan
| | - Kay-Hooi Khoo
- 0000 0001 2287 1366grid.28665.3fInstitute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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Lee CC, Chang CP, Lin CJ, Lai HL, Kao YH, Cheng SJ, Chen HM, Liao YP, Faivre E, Buée L, Blum D, Fang JM, Chern Y. Adenosine Augmentation Evoked by an ENT1 Inhibitor Improves Memory Impairment and Neuronal Plasticity in the APP/PS1 Mouse Model of Alzheimer's Disease. Mol Neurobiol 2018; 55:8936-8952. [PMID: 29616397 DOI: 10.1007/s12035-018-1030-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/20/2018] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive impairment and synaptic dysfunction. Adenosine is an important homeostatic modulator that controls the bioenergetic network in the brain through regulating receptor-evoked signaling pathways, bioenergetic machineries, and epigenetic-mediated gene regulation. Equilibrative nucleoside transporter 1 (ENT1) is a major adenosine transporter that recycles adenosine from the extracellular space. In the present study, we report that a small adenosine analogue (designated J4) that inhibited ENT1 prevented the decline in spatial memory in an AD mouse model (APP/PS1). Electrophysiological and biochemical analyses further demonstrated that chronic treatment with J4 normalized the impaired basal synaptic transmission and long-term potentiation (LTP) at Schaffer collateral synapses as well as the aberrant expression of synaptic proteins (e.g., NR2A and NR2B), abnormal neuronal plasticity-related signaling pathways (e.g., PKA and GSK3β), and detrimental elevation in astrocytic A2AR expression in the hippocampus and cortex of APP/PS1 mice. In conclusion, our findings suggest that modulation of adenosine homeostasis by J4 is beneficial in a mouse model of AD. Our study provides a potential therapeutic strategy to delay the progression of AD.
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Affiliation(s)
- Chia-Chia Lee
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Ching-Pang Chang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chun-Jung Lin
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Yu-Han Kao
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Sin-Jhong Cheng
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan.,Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Yu-Ping Liao
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Emilie Faivre
- Université de Lille, Inserm, CHU-Lille, LabEx DISTALZ, Jean-Pierre Aubert research centre UMR-S1172, Lille, France
| | - Luc Buée
- Université de Lille, Inserm, CHU-Lille, LabEx DISTALZ, Jean-Pierre Aubert research centre UMR-S1172, Lille, France
| | - David Blum
- Université de Lille, Inserm, CHU-Lille, LabEx DISTALZ, Jean-Pierre Aubert research centre UMR-S1172, Lille, France
| | - Jim-Min Fang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan.
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Lai CY, Liu YJ, Lai HL, Chen HM, Kuo HC, Liao YP, Chern Y. The D2 Dopamine Receptor Interferes With the Protective Effect of the A 2A Adenosine Receptor on TDP-43 Mislocalization in Experimental Models of Motor Neuron Degeneration. Front Neurosci 2018; 12:187. [PMID: 29615863 PMCID: PMC5869924 DOI: 10.3389/fnins.2018.00187] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/07/2018] [Indexed: 12/13/2022] Open
Abstract
The A2A adenosine receptor (A2AR) and D2 dopamine receptor (D2R) are two G-protein-coupled receptors that can form dimers and negatively regulate their partners. TAR DNA-binding protein (TDP-43) is a nuclear protein that has been implicated in amyotrophic lateral sclerosis (ALS). Mislocalization of TDP-43 from the nucleus to the cytoplasm is an early step of TDP-43 proteinopathy. Our previous studies indicated that A2AR is a potential drug target for ALS because treatment with an A2AR agonist (JMF1907; a T1-11 analog) prevents reactive oxygen species (ROS)-induced TDP-43 mislocalization in a motor neuron cell line (NSC34) and delays motor impairment in a TDP-43 transgenic ALS mouse model. Here, we set out to assess whether activation of D2R interferes with the beneficial effects of an A2AR agonist on motor neurons. We first demonstrated that A2AR and D2R are both located in motor neurons of mouse and human spinal cords and human iPSC-derived motor neurons. Expression of A2AR and D2R in NSC34 cells led to dimer formation without affecting the binding affinity of A2AR toward T1-11. Importantly, activation of D2R reduced T1-11-mediated activation of cAMP/PKA signaling and subsequent inhibition of TDP-43 mislocalization in NSC34 cells. Treatment with quinpirole (a D2 agonist) blunted the rescuing effect of T1-11 on TDP-43 mislocalization and impaired grip strength in a mouse model of ALS. Our findings suggest that D2R activation may limit the beneficial responses of an A2AR agonist in motor neurons and may have an important role in ALS pathogenesis.
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Affiliation(s)
- Chia-You Lai
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Ju Liu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hung-Chi Kuo
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Yu-Ping Liao
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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Chien T, Weng YT, Chang SY, Lai HL, Chiu FL, Kuo HC, Chuang DM, Chern Y. GSK3β negatively regulates TRAX, a scaffold protein implicated in mental disorders, for NHEJ-mediated DNA repair in neurons. Mol Psychiatry 2018; 23:2375-2390. [PMID: 29298990 PMCID: PMC6294740 DOI: 10.1038/s41380-017-0007-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/28/2017] [Accepted: 10/30/2017] [Indexed: 12/27/2022]
Abstract
Translin-associated protein X (TRAX) is a scaffold protein with various functions and has been associated with mental illnesses, including schizophrenia. We have previously demonstrated that TRAX interacts with a Gsα protein-coupled receptor, the A2A adenosine receptor (A2AR), and mediates the function of this receptor in neuritogenesis. In addition, stimulation of the A2AR markedly ameliorates DNA damage evoked by elevated oxidative stress in neurons derived from induced pluripotent stem cells (iPSCs). Here, we report that glycogen synthase kinase 3 beta (GSK3β) and disrupted-in-schizophrenia 1 (DISC1) are two novel interacting proteins of TRAX. We present evidence to suggest that the stimulation of A2AR markedly facilitated DNA repair through the TRAX/DISC1/GSK3β complex in a rat neuronal cell line (PC12), primary mouse neurons, and human medium spiny neurons derived from iPSCs. A2AR stimulation led to the inhibition of GSK3β, thus dissociating the TRAX/DISC1/GSK3β complex and facilitating the non-homologous end-joining pathway (NHEJ) by enhancing the activation of a DNA-dependent protein kinase via phosphorylation at Thr2609. Similarly, pharmacological inhibition of GSK3β by SB216763 also facilitated the TRAX-mediated repair of oxidative DNA damage. Collectively, GSK3β binds with TRAX and negatively affects its ability to facilitate NHEJ repair. The suppression of GSK3β by A2AR activation or a GSK3β inhibitor releases TRAX for the repair of oxidative DNA damage. Our findings shed new light on the molecular mechanisms underlying diseases associated with DNA damage and provides a novel target (i.e., the TRAX/DISC1/GSK3β complex) for future therapeutic development for mental disorders.
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Affiliation(s)
- Ting Chien
- 0000 0004 0634 0356grid.260565.2Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan ,0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Ting Weng
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan ,0000 0001 2287 1366grid.28665.3fProgram in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
| | - Shu-Yung Chang
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan ,0000 0001 0425 5914grid.260770.4Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Hsing-Lin Lai
- 0000 0004 0633 7958grid.482251.8Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Feng-Lan Chiu
- 0000 0001 2287 1366grid.28665.3fInstitute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Chih Kuo
- 0000 0001 2287 1366grid.28665.3fInstitute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - De-Maw Chuang
- 0000 0004 0464 0574grid.416868.5Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan. .,Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan. .,Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.
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Kao YH, Lin MS, Chen CM, Wu YR, Chen HM, Lai HL, Chern Y, Lin CJ. Targeting ENT1 and adenosine tone for the treatment of Huntington's disease. Hum Mol Genet 2017; 26:467-478. [PMID: 28069792 DOI: 10.1093/hmg/ddw402] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/21/2016] [Indexed: 11/14/2022] Open
Abstract
Huntington's disease (HD) is caused by an abnormal CAG expansion in the exon 1 of huntingtin gene. The treatment of HD is an unmet medical need. Given the important role of adenosine in modulating brain activity, in this study, levels of adenosine and adenine nucleotides in the cerebral spinal fluid of patients with HD and in the brain of two mouse models of HD (R6/2 and Hdh150Q) were analysed. The expression and activity of ENT1 in the striatum of mice with HD were measured. Targeting adenosine tone for treating HD was examined in R6/2 mice by genetic removal of ENT1 and by giving an ENT1 inhibitor, respectively. The results showed that the adenosine homeostasis is dysregulated in the brain of patients and mice with HD. In patients, the ratio of adenosine/ATP in the cerebral spinal fluid was negatively correlated with the disease duration, and tended to have a positive correlation with independence scale and functional capacity. In comparison to controls, mRNA level of ENT1 was higher in the striatum of R6/2 and Hdh150Q mice. Intrastriatal administration of ENT1 inhibitors increased extracellular level of adenosine in the striatum of R6/2 mice to a much higher level than controls. Chronic inhibition of ENT1 or by genetic removal of ENT1 enhanced the survival of R6/2 mice. Collectively, adenosine homeostasis and ENT1 expression are altered in HD. The inhibition of ENT1 can enhance extracellular adenosine level and be a potential therapeutic approach for treating HD.
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Affiliation(s)
- Yu-Han Kao
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Meng-Syuan Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chiung-Mei Chen
- Department of Neurology, Chang Gung Memorial Hospital Linkou Medical Center and College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan
| | - Yih-Ru Wu
- Department of Neurology, Chang Gung Memorial Hospital Linkou Medical Center and College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chun-Jung Lin
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
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8
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Wu YS, Chen CC, Chien CL, Lai HL, Jiang ST, Chen YC, Lai LP, Hsiao WF, Chen WP, Chern Y. The type VI adenylyl cyclase protects cardiomyocytes from β-adrenergic stress by a PKA/STAT3-dependent pathway. J Biomed Sci 2017; 24:68. [PMID: 28870220 PMCID: PMC5584049 DOI: 10.1186/s12929-017-0367-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/11/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The type VI adenylyl cyclase (AC6) is a main contributor of cAMP production in the heart. The amino acid (aa) sequence of AC6 is highly homologous to that of another major cardiac adenylyl cyclase, AC5, except for its N-terminus (AC6-N, aa 1-86). Activation of AC6, rather than AC5, produces cardioprotective effects against heart failure, while the underlying mechanism remains to be unveiled. Using an AC6-null (AC6-/-) mouse and a knockin mouse with AC6-N deletion (AC6 ΔN/ΔN), we aimed to investigate the cardioprotective mechanism of AC6 in the heart. METHODS Western blot analysis and immunofluorescence staining were performed to determine the intracellular distribution of AC6, AC6-ΔN (a truncated AC6 lacking the first 86 amino acids), and STAT3 activation. Activities of AC6 and AC6-ΔN in the heart were assessed by cAMP assay. Apoptosis of cardiomyocytes were evaluated by the TUNEL assay and a propidium iodine-based survival assay. Fibrosis was examined by collagen staining. RESULTS Immunofluorescence staining revealed that cardiac AC6 was mainly anchored on the sarcolemmal membranes, while AC6-ΔN was redistributed to the sarcoplasmic reticulum. AC6ΔN/ΔN and AC6-/- mice had more apoptotic myocytes and cardiac remodeling than WT mice in experimental models of isoproterenol (ISO)-induced myocardial injury. Adult cardiomyocytes isolated from AC6ΔN/ΔN or AC6-/- mice survived poorly after exposure to ISO, which produced no effect on WT cardiomyocytes under the condition tested. Importantly, ISO treatment induced cardiac STAT3 phosphorylation/activation in WT mice, but not in AC6ΔN/ΔN and AC6-/- mice. Pharmacological blockage of PKA-, Src-, or STAT3- pathway markedly reduced the survival of WT myocytes in the presence of ISO, but did not affect those of AC6ΔN/ΔN and AC6-/- myocytes, suggesting an important role of AC6 in mediating cardioprotective action through the activation of PKA-Src-STAT3-signaling. CONCLUSIONS Collectively, AC6-N controls the anchorage of cardiac AC6 on the sarcolemmal membrane, which enables the coupling of AC6 with the pro-survival PKA-STAT3 pathway. Our findings may facilitate the development of novel therapies for heart failure.
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Affiliation(s)
- Yu-Shuo Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chien-Chang Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chen-Li Chien
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Si-Tse Jiang
- National Laboratory Animal Center, National Applied Research Laboratories, Tainan, Taiwan
| | - Yong-Cyuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Lin-Ping Lai
- Institute of Internal Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Fan Hsiao
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Pin Chen
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan.
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9
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Liu YJ, Lee LM, Lai HL, Chern Y. Aberrant activation of AMP-activated protein kinase contributes to the abnormal distribution of HuR in amyotrophic lateral sclerosis. FEBS Lett 2015; 589:432-9. [DOI: 10.1016/j.febslet.2014.12.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/08/2014] [Accepted: 12/26/2014] [Indexed: 10/24/2022]
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10
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Liu YJ, Ju TC, Chen HM, Jang YS, Lee LM, Lai HL, Tai HC, Fang JM, Lin YL, Tu PH, Chern Y. Activation of AMP-activated protein kinase α1 mediates mislocalization of TDP-43 in amyotrophic lateral sclerosis. Hum Mol Genet 2014; 24:787-801. [DOI: 10.1093/hmg/ddu497] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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11
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Chien CL, Lin MS, Lai HL, Wu YS, Chang CP, Chen HM, Chang C, Su CK, Chern Y. Lack of type VI adenylyl cyclase (AC6) leads to abnormal sympathetic tone in neonatal mice. Exp Neurol 2013; 248:10-5. [DOI: 10.1016/j.expneurol.2013.05.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 02/07/2023]
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12
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Wu YC, Lai HL, Chang WC, Lin JT, Liu YJ, Chern Y. A novel Gαs-binding protein, Gas-2 like 2, facilitates the signaling of the A2A adenosine receptor. Biochim Biophys Acta 2013; 1833:3145-3154. [PMID: 23994616 DOI: 10.1016/j.bbamcr.2013.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 12/13/2022]
Abstract
The A2A adenosine receptor (A2AR) is a G-protein-coupled receptor that contains a long cytoplasmic carboxyl terminus (A2AR-C). We report here that Gas-2 like 2 (G2L2) is a new interacting partner of A2AR-C. The interaction between A2AR and G2L2 was verified by GST pull-down, co-immunoprecipitation, immunocytochemical staining, and fluorescence resonance energy transfer. Expression of G2L2 increased the intracellular cAMP content evoked by A2AR in an A2AR-C-dependent manner. Immunoprecipitation and pull-down assays demonstrated that G2L2 selectively bound to A2AR-C and the inactive form of Gαs to facilitate the recruitment of the trimeric G protein complex to the proximal position of A2AR for efficient activation. Collectively, G2L2 is a new effector that controls the action of A2AR by modulating its ability to regulate the Gαs-mediated cAMP contents.
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Affiliation(s)
- Yi-Chih Wu
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan; Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Wei-Cheng Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jiun-Tsai Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Ju Liu
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Yijuang Chern
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
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13
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Huang NK, Lin JH, Lin JT, Lin CI, Liu EM, Lin CJ, Chen WP, Shen YC, Chen HM, Chen JB, Lai HL, Yang CW, Chiang MC, Wu YS, Chang C, Chen JF, Fang JM, Lin YL, Chern Y. A new drug design targeting the adenosinergic system for Huntington's disease. PLoS One 2011; 6:e20934. [PMID: 21713039 PMCID: PMC3119665 DOI: 10.1371/journal.pone.0020934] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 05/13/2011] [Indexed: 02/01/2023] Open
Abstract
Background Huntington's disease (HD) is a neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The expanded CAG repeats are translated into polyglutamine (polyQ), causing aberrant functions as well as aggregate formation of mutant Htt. Effective treatments for HD are yet to be developed. Methodology/Principal Findings Here, we report a novel dual-function compound, N6-(4-hydroxybenzyl)adenine riboside (designated T1-11) which activates the A2AR and a major adenosine transporter (ENT1). T1-11 was originally isolated from a Chinese medicinal herb. Molecular modeling analyses showed that T1-11 binds to the adenosine pockets of the A2AR and ENT1. Introduction of T1-11 into the striatum significantly enhanced the level of striatal adenosine as determined by a microdialysis technique, demonstrating that T1-11 inhibited adenosine uptake in vivo. A single intraperitoneal injection of T1-11 in wildtype mice, but not in A2AR knockout mice, increased cAMP level in the brain. Thus, T1-11 enters the brain and elevates cAMP via activation of the A2AR in vivo. Most importantly, addition of T1-11 (0.05 mg/ml) to the drinking water of a transgenic mouse model of HD (R6/2) ameliorated the progressive deterioration in motor coordination, reduced the formation of striatal Htt aggregates, elevated proteasome activity, and increased the level of an important neurotrophic factor (brain derived neurotrophic factor) in the brain. These results demonstrate the therapeutic potential of T1-11 for treating HD. Conclusions/Significance The dual functions of T1-11 enable T1-11 to effectively activate the adenosinergic system and subsequently delay the progression of HD. This is a novel therapeutic strategy for HD. Similar dual-function drugs aimed at a particular neurotransmitter system as proposed herein may be applicable to other neurotransmitter systems (e.g., the dopamine receptor/dopamine transporter and the serotonin receptor/serotonin transporter) and may facilitate the development of new drugs for other neurodegenerative diseases.
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Affiliation(s)
- Nai-Kuei Huang
- National Research Institute of Chinese Medicine, Taipei, Taiwan
| | - Jung-Hsin Lin
- Division of Mechanics, Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Jiun-Tsai Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chia-I Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Eric Minwei Liu
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Chun-Jung Lin
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Wan-Ping Chen
- National Research Institute of Chinese Medicine, Taipei, Taiwan
| | - Yuh-Chiang Shen
- National Research Institute of Chinese Medicine, Taipei, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jhih-Bin Chen
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chieh-Wen Yang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Ming-Chang Chiang
- Graduate Institute of Biotechnology, Chinese Culture University, Taipei, Taiwan
| | - Yu-Shuo Wu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chen Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Jim-Min Fang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- The Genomics Research Center, Academia Sinica, Taipei, Taiwan
- * E-mail: (YC); (YLL); (JMF)
| | - Yun-Lian Lin
- National Research Institute of Chinese Medicine, Taipei, Taiwan
- * E-mail: (YC); (YLL); (JMF)
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- * E-mail: (YC); (YLL); (JMF)
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14
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Chien CL, Wu YS, Lai HL, Chen YH, Jiang ST, Shih CM, Lin SS, Chang C, Chern Y. Impaired water reabsorption in mice deficient in the type VI adenylyl cyclase (AC6). FEBS Lett 2010; 584:2883-90. [PMID: 20466003 DOI: 10.1016/j.febslet.2010.05.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 04/21/2010] [Accepted: 05/01/2010] [Indexed: 01/27/2023]
Abstract
Adenylyl cyclase (AC) type VI (AC6) is a calcium-inhibitable enzyme which produces cAMP upon stimulation. Herein, we characterized the specific role of AC6 in the kidneys using two AC6-knockout mouse lines. Immunohistochemical staining revealed that AC6 exists in the tubular parts of the nephron and collecting duct. Activities of AC evoked by forskolin or a selective agonist of the V2 vasopressin receptor were lower in the kidneys of AC6-null mice compared to those of wildtype mice. Results of a metabolic cage assay and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) showed for the first time that AC6 plays a critical role in regulating water homeostasis.
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Affiliation(s)
- Chen-Li Chien
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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15
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Chiang MC, Chen HM, Lai HL, Chen HW, Chou SY, Chen CM, Tsai FJ, Chern Y. The A2A adenosine receptor rescues the urea cycle deficiency of Huntington's disease by enhancing the activity of the ubiquitin-proteasome system. Hum Mol Genet 2009; 18:2929-42. [PMID: 19443488 DOI: 10.1093/hmg/ddp230] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The resultant mutant Htt protein (mHtt) forms aggregates in the brain and several peripheral tissues (e.g. the liver) and causes devastating neuronal degeneration. Metabolic defects resulting from Htt aggregates in peripheral tissues also contribute to HD pathogenesis. Simultaneous improvement of defects in both the CNS and peripheral tissues is thus the most effective therapeutic strategy and is highly desirable. We earlier showed that an agonist of the A(2A) adenosine receptor (A(2A) receptor), CGS21680 (CGS), attenuates neuronal symptoms of HD. We found herein that the A(2A) receptor also exists in the liver, and that CGS ameliorated the urea cycle deficiency by reducing mHtt aggregates in the liver. By suppressing aggregate formation, CGS slowed the hijacking of a crucial transcription factor (HSF1) and two protein chaperons (Hsp27 and Hsp70) into hepatic Htt aggregates. Moreover, the abnormally high levels of high-molecular-mass ubiquitin conjugates in the liver of an HD mouse model (R6/2) were also ameliorated by CGS. The protective effect of CGS against mHtt-induced aggregate formation was reproduced in two cells lines and was prevented by an antagonist of the A(2A) receptor and a protein kinase A (PKA) inhibitor. Most importantly, the mHtt-induced suppression of proteasome activity was also normalized by CGS through PKA. Our findings reveal a novel therapeutic pathway of A(2A) receptors in HD and further strengthen the concept that the A(2A) receptor can be a drug target in treating HD.
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Affiliation(s)
- Ming-Chang Chiang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, Republic of China
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16
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Abstract
In the present study, we demonstrate that AC5 (type V adenylate cyclase) interacts with Ric8a through directly interacting at its N-terminus. Ric8a was shown to be a GEF (guanine nucleotide exchange factor) for several alpha subunits of heterotrimeric GTP binding proteins (Galpha proteins) in vitro. Selective Galpha targets of Ric8a have not yet been revealed in vivo. An interaction between AC5 and Ric8a was verified by pull-down assays, co-immunoprecipitation analyses, and co-localization in the brain. Expression of Ric8a selectively suppressed AC5 activity. Treating cells with pertussis toxin or expressing a dominant negative Galphai mutant abolished the suppressive effect of Ric8a, suggesting that interaction between the N-terminus of AC5 and a GEF (Ric8a) provides a novel pathway to fine-tune AC5 activity via a Galphai-mediated pathway.
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Affiliation(s)
- Shyi-Chyi Wang
- *Institute of Life Sciences, National Defence Medical Center, Taipei 104, Taiwan
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Hsing-Lin Lai
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ting Chiu
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
| | - Ren Ou
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
| | - Chuen-Lin Huang
- §Cardinal Tien Hospital, Hsintien Taipei Hsien 23137, Taiwan
| | - Yijuang Chern
- *Institute of Life Sciences, National Defence Medical Center, Taipei 104, Taiwan
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
- To whom correspondence should be addressed (email )
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Sun CN, Cheng HC, Chou JL, Lee SY, Lin YW, Lai HL, Chen HM, Chern Y. Rescue of p53 Blockage by the A2AAdenosine Receptor via a Novel Interacting Protein, Translin-Associated Protein X. Mol Pharmacol 2006; 70:454-66. [PMID: 16617164 DOI: 10.1124/mol.105.021261] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Blockage of the p53 tumor suppressor has been found to impair nerve growth factor (NGF)-induced neurite outgrowth in PC-12 cells. We report herein that such impairment could be rescued by stimulation of the A(2A) adenosine receptor (A(2A)-R), a G protein-coupled receptor implicated in neuronal plasticity. The A(2A)-R-mediated rescue occurred in the presence of protein kinase C (PKC) inhibitors or protein kinase A (PKA) inhibitors and in a PKA-deficient PC-12 variant. Thus, neither PKA nor PKC was involved. In contrast, expression of a truncated A(2A)-R mutant harboring the seventh transmembrane domain and its C terminus reduced the rescue effect of A(2A)-R. Using the cytoplasmic tail of the A(2A)-R as bait, a novel-A(2A)-R-interacting protein [translin-associated protein X (TRAX)] was identified in a yeast two-hybrid screen. The authenticity of this interaction was verified by pull-down experiments, coimmunoprecipitation, and colocalization of these two molecules in the brain. It is noteworthy that reduction of TRAX using an antisense construct suppressed the rescue effect of A(2A)-R, whereas overexpression of TRAX alone caused the same rescue effect as did A(2A)-R activation. Results of [(3)H]thymidine and bromodeoxyuridine incorporation suggested that A(2A)-R stimulation inhibited cell proliferation in a TRAX-dependent manner. Because the antimitotic activity is crucial for NGF function, the A(2A)-R might exert its rescue effect through a TRAX-mediated antiproliferative signal. This antimitotic activity of the A(2A)-R also enables a mitogenic factor (epidermal growth factor) to induce neurite outgrowth. We demonstrate that the A(2A)-R modulates the differentiation ability of trophic factors through a novel interacting protein, TRAX.
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Affiliation(s)
- Chung-Nan Sun
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
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Chou SY, Lee YC, Chen HM, Chiang MC, Lai HL, Chang HH, Wu YC, Sun CN, Chien CL, Lin YS, Wang SC, Tung YY, Chang C, Chern Y. CGS21680 attenuates symptoms of Huntington's disease in a transgenic mouse model. J Neurochem 2005; 93:310-20. [PMID: 15816854 DOI: 10.1111/j.1471-4159.2005.03029.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in exon 1 of the Huntingtin (Htt) gene. We show herein that in an HD transgenic mouse model (R6/2), daily administration of CGS21680 (CGS), an A(2A) adenosine receptor (A(2A)-R)-selective agonist, delayed the progressive deterioration of motor performance and prevented a reduction in brain weight. 3D-microMRI analysis revealed that CGS reversed the enlarged ventricle-to-brain ratio of R6/2 mice, with particular improvements in the left and right ventricles. (1)H-MRS showed that CGS significantly reduced the increased choline levels in the striatum. Immunohistochemical analyses further demonstrated that CGS reduced the size of ubiquitin-positive neuronal intranuclear inclusions (NIIs) in the striatum of R6/2 mice and ameliorated mutant Htt aggregation in a striatal progenitor cell line overexpressing mutant Htt with expanded polyQ. Moreover, chronic CGS treatment normalized the elevated blood glucose levels and reduced the overactivation of a major metabolic sensor [5'AMP-activated protein kinase (AMPK)] in the striatum of R6/2 mice. Since AMPK is a master switch for energy metabolism, modulation of energy dysfunction caused by the mutant Htt might contribute to the beneficial effects of CGS. Collectively, CGS is a potential drug candidate for the treatment of HD.
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Affiliation(s)
- Szu-Yi Chou
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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Abstract
In the present study, we used the N terminus (amino acids 1 approximately 160) of type VI adenylyl cyclase (ACVI) as bait to screen a mouse brain cDNA library and identified Snapin as a novel ACVI-interacting molecule. Snapin is a binding protein of SNAP25, a component of the SNARE complex. Co-immunoprecipitation analyses confirmed the interaction between Snapin and full-length ACVI. Mutational analysis revealed that the interaction domains of ACVI and Snapin were located within amino acids 1 approximately 86 of ACVI and 33-51 of Snapin, respectively. Co-localization of ACVI and Snapin was observed in primary hippocampal neurons. Moreover, expression of Snapin specifically eliminated protein kinase C (PKC)-mediated suppression of ACVI, but not that of cAMP-dependent protein kinase (PKA) or calcium. Mutation of the potential PKC and PKA phosphorylation sites of Snapin did not affect the ability of Snapin to reverse the PKC inhibitory effect on ACVI. Phosphorylation of Snapin by PKC or PKA therefore might not be crucial for Snapin action on ACVI. In contrast, Snapin(Delta33-51), which harbors an internal deletion of amino acids 33-51 did not affect PKC-mediated inhibition of ACVI, supporting that amino acids 33-51 of Snapin comprises the ACVI-interacting region. Consistently, Snapin exerted no effect on PKC-mediated inhibition of an ACVI mutant (ACVI-DeltaA87), which lacked the Snapin-interacting region (amino acids 1-86). Snapin thus reverses its action via direct interaction with the N terminus of ACVI. Collectively, we demonstrate herein that in addition to its association with the SNARE complex, Snapin also functions as a regulator of an important cAMP synthesis enzyme in the brain.
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Affiliation(s)
- Jui-Ling Chou
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
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20
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Kao YY, Lai HL, Hwang MJ, Chern Y. An Important Functional Role of the N Terminus Domain of Type VI Adenylyl Cyclase in Gαi-mediated Inhibition. J Biol Chem 2004; 279:34440-8. [PMID: 15192109 DOI: 10.1074/jbc.m401952200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We show herein that removal of the first 86 amino acids (aa) of the N terminus (designated N) of type VI adenylyl cyclase (ACVI) caused the resultant ACVI mutant (ACVI-DeltaA87) to be more greatly inhibited by a Galpha(i)-coupled receptor or activated Galpha(i) protein. Moreover, in vitro binding of the full-length N and C1a domain (designated C1a), which interacts with Galpha(i), was detected. A truncated N terminus (aa 1-86) also interacted with C1a, suggesting that the C1a-interacting region is located within aa 1-86. Mutation analyses further revealed that N might interact with C1a in the region (aa 434-505) where Galpha(i) is bound. Mutations of two residues (Leu-472 and Val-476) located in this N-binding region of C1a suppressed the interaction between recombinant N and C1a and markedly reduced Galpha(i)-mediated inhibition of ACVI-DeltaA87. Further biochemical analyses of the effect of internal mutations of Leu-472/Val-476 on Galpha(i)-mediated inhibition of wild-type ACVI and ACVI-DeltaA87 suggested that N modulates the Galpha(i)-mediated inhibition of ACVI via binding to C1a when the level of Galpha(i) is low (i.e. around the IC(50) value) and that a more complicated interfering mode results when the level of Galpha(i) is high (i.e. approximately 10- to 20-fold of the IC(50) value). Collectively, data presented herein suggest a novel function of the N terminus of ACVI in Galpha(i)-mediated regulation.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Blotting, Western
- CHO Cells
- Catalytic Domain
- Cell Line
- Cell Membrane/metabolism
- Cricetinae
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Humans
- Inhibitory Concentration 50
- Leucine/chemistry
- Models, Biological
- Models, Molecular
- Mutagenesis, Site-Directed
- Mutation
- Plasmids/metabolism
- Polymerase Chain Reaction
- Protein Binding
- Protein Conformation
- Protein Isoforms
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proto-Oncogene Proteins/metabolism
- Rats
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Transfection
- Valine/chemistry
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Affiliation(s)
- Yu-Ya Kao
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC
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Lee YC, Chien CL, Sun CN, Huang CL, Huang NK, Chiang MC, Lai HL, Lin YS, Chou SY, Wang CKL, Tai MH, Liao WL, Lin TN, Liu FC, Chern Y. Characterization of the rat A2A adenosine receptor gene: a 4.8-kb promoter-proximal DNA fragment confers selective expression in the central nervous system. Eur J Neurosci 2003; 18:1786-96. [PMID: 14622213 DOI: 10.1046/j.1460-9568.2003.02907.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We isolated and characterized a 4.8-kb 5' flanking region of the rat A2A adenosine receptor (A2A-R) gene in the present study. Promoter activity was observed with this DNA fragment in PC12 cells and C6 cells which contain endogenous A2A-Rs. A fusion fragment consisting of the 4.8-kb promoter-proximal DNA fragment of the A2A-R gene, and the coding region of lacZ was utilized to produce mice harbouring the fusion gene. In three independent founder lines, proteins and transcripts of the transgene were found in many areas of the central nervous system (CNS), but not in three peripheral tissues examined. Double immunohistochemical analyses revealed that the transgene was coexpressed with endogenous A2A-R and proper neuronal markers in the brain. Specifically, the transgene in the striatum was found in the enkephalin-containing GABAergic neurons and in the cholinergic neurons as was found for the endogenous A2A-R. However, a selectively enriched striatal expression of the transgene was not found as was observed for the endogenous A2A-R. Collectively, the 4.8-kb promoter-proximal DNA fragment of the rat A2A-R gene contains important element(s) to direct its expression in the CNS where functional A2A-R are found, but were not sufficient to confer the highly concentrated expression of the striatal A2A-R. Furthermore, expressions of A2A-R and the transgene were found in both neurons and astrocytes, suggesting that adenosine might mediate its function through A2A-R in both cell types.
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Affiliation(s)
- Yi-Chao Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
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Lin TH, Lai HL, Kao YY, Sun CN, Hwang MJ, Chern Y. Protein kinase C inhibits type VI adenylyl cyclase by phosphorylating the regulatory N domain and two catalytic C1 and C2 domains. J Biol Chem 2002; 277:15721-8. [PMID: 11877398 DOI: 10.1074/jbc.m111537200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously showed that phosphorylation of Ser(10) of the N terminus domain of the type VI adenylyl cyclase (ACVI) partly mediated protein kinase C (PKC)-induced inhibition of ACVI. We now report that phosphorylation of the other two cytosolic domains (C1 and C2), which form the catalytic core complex of ACVI, also contributes to PKC-mediated inhibition. In vitro phosphorylation by PKC of the recombinant C1a and C2 domains, and of the synthetic peptides representing potential PKC phosphorylation sites, suggests that Ser(568) and Ser(674) of the C1 domain and Thr(931) of the C2 domain might act as substrates for PKC. We next created several full-length ACVI mutants in which one or more of the four likely PKC phosphorylation sites (Ser(10), Ser(568), Ser(674), and Thr(931)) were mutated to alanine. Simultaneous mutation of at least two of the three likely residues located in the N and C1 domains (Ser(10), Ser(568), and Ser(674)) was required to render ACVI variants completely insensitive to PKC treatment. In contrast, a single mutation of Thr(931) was sufficient to create a functional ACVI mutant that exhibited no detectable PKC-mediated inhibition, demonstrating the essentiality of Thr(931) to PKC-mediated regulation. Based on these results, we propose that the three cytosolic domains of ACVI might form a regulatory complex. Phosphorylation of this regulatory complex at different sites might induce a fine-tuning of the catalytic core complex and subsequently lead to alternation in the catalytic activity of ACVI.
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Affiliation(s)
- Ting-Hui Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, Republic of China
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Wu GC, Lai HL, Lin YW, Chu YT, Chern Y. N-glycosylation and residues Asn805 and Asn890 are involved in the functional properties of type VI adenylyl cyclase. J Biol Chem 2001; 276:35450-7. [PMID: 11461898 DOI: 10.1074/jbc.m009704200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we demonstrate that type VI adenylyl cyclase (ACVI) is glycosylated in vivo. Treating HEK293 cells expressing ACVI with tunicamycin to block the addition of N-linked oligosaccharide or removing the N-linked oligosaccharide by in vitro peptidyl-N-glycosidase F digestion reduced the molecular mass of ACVI. Furthermore, tunicamycin treatment suppressed the forskolin-stimulated activity of ACVI. Mutation of either one or both potential N-glycosylation sites (Asn(805) and Asn(890), located on extracellular loops 5 and 6, respectively) also reduced the molecular mass of ACVI. Therefore, ACVI was glycosylated at both Asn(805) and Asn(890). Confocal analysis indicated that glycosylation was not required for the delivery of ACVI to the cell surface. Although no significant alterations in K(m) values for ATP or sensitivity to divalent cations were detected, the glycosylation-deficient ACVI mutant N805Q/N890Q-ACVI exhibited much lower forskolin-, Mn(2+)-, and Mg(2+)-stimulated cyclase activities than did wild-type ACVI. By contrast, the Galpha(s)-stimulated cyclase activities of wild-type ACVI and N805Q/N890Q-ACVI were indistinguishable. Furthermore, compared with wild-type ACVI, N805Q/N890Q-ACVI was less sensitive to inhibition mediated by dopamine D2 receptors or by protein kinase C. Collectively, glycosylation of ACVI not only affected its catalytic activity in an activator-dependent manner, but also altered its ability to be regulated by a Galpha(i) protein-coupled receptor or by protein kinase C.
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Affiliation(s)
- G C Wu
- Institute of Life Sciences, National Defense Medical Center, Taipei 104, Taiwan, Republic of China
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24
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Abstract
AIMS We investigated the effects of relaxation, music, and the combination of relaxation and music on postoperative pain, across and between two days and two activities (ambulation and rest) and across ambulation each day. This secondary analysis of a randomized controlled trial was conducted from 1995 to 1997. BACKGROUND After surgery, patients do not always receive sufficient relief from opioids and may have undesired side-effects. More complete relief (10-30%) was found recently with adjuvant interventions of relaxation, music, and their combination. Comparison of effects between days and treatments have not been examined longitudinally. METHODS With a repeated measures design, abdominal surgery patients (n = 468) in five US hospitals were assigned randomly to one of four groups; relaxation, music, their combination, and control. With institutional approval and written informed consent, subjects were interviewed and taught interventions preoperatively. Postoperative testing was at ambulation and rest on days 1 and 2 using visual analogue (VAS) sensation and distress of pain scales. RESULTS Multivariate analysis indicated that although pain decreased by day 2, interventions were not different between days and activities. They were effective for pain across ambulation on each day, across ambulation and across rest over both days (all P < 0.001), and had similar effects by day and by activity. CONCLUSION Nurses can safely recommend any of these interventions for pain on both postoperative days and at both ambulation and rest.
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Affiliation(s)
- M Good
- Frances Payne Bolton School of Nursing, Case Western Reserve University, Cleveland, Ohio, USA.
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Lu L, Peter SJ, Lyman MD, Lai HL, Leite SM, Tamada JA, Uyama S, Vacanti JP, Langer R, Mikos AG. In vitro and in vivo degradation of porous poly(DL-lactic-co-glycolic acid) foams. Biomaterials 2000; 21:1837-45. [PMID: 10919687 DOI: 10.1016/s0142-9612(00)00047-8] [Citation(s) in RCA: 529] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This study investigated the in vitro degradation of porous poly(DL-lactic-co-glycolic acid) (PLGA) foams during a 20-week period in pH 7.4 phosphate-buffered saline (PBS) at 37 degrees C and their in vivo degradation following implantation in rat mesentery for up to 8 weeks. Three types of PLGA 85 : 15 and three types of 50 : 50 foams were fabricated using a solvent-casting, particulate-leaching technique. The two types had initial salt weight fraction of 80 and 90%, and a salt particle size of 106-150 microm, while the third type had 90% initial weight fraction of salt in the size range 0-53 microm. The porosities of the resulting foams were 0.82, 0.89, and 0.85 for PLGA 85 : 15, and 0.73, 0.87, and 0.84 for PLGA 50 : 50 foams, respectively. The corresponding median pore diameters were 30, 50, and 17 microm for PLGA 85: 15, and 19, 17, and 17 microm for PLGA 50 : 50. The in vitro and in vivo degradation kinetics of PLGA 85: 15 foams were independent of pore morphology with insignificant variation in foam weight, thickness, pore distribution, compressive creep behavior, and morphology during degradation. The in vitro foam half-lives based on the weight average molecular weight were 11.1 +/- 1.8 (80%, 106-150 microm), 12.0 +/- 2.0 (90%, 106-150 microm), and 11.6 +/- 1.3 (90%, 0-53 microm) weeks, similar to the corresponding values of 9.4 +/- 2.2, 14.3 +/- 1.5, and 13.7 +/- 3.3 weeks for in vivo degradation. In contrast, all PLGA 50 : 50 foams exhibited significant change in foam weight, water absorption, and pore distribution after 6-8 weeks of incubation with PBS. The in vitro foam half-lives were 3.3 +/- 0.3 (80%, 106-150 microm), 3.0 +/- 0.3 (90%, 106-150 microm), and 3.2 +/- 0.1 (90%, 0-53 microm) weeks, and the corresponding in vivo half-lives were 1.9 micro 0.1, 2.2 +/- 0.2, and 2.4 +/- 0.2 weeks. The significantly shorter half-lives of PLGA 50: 50 compared to 85: 15 foams indicated their faster degradation both in vitro and in vivo. In addition, PLGA 50: 50 foams exhibited significantly faster degradation in vivo as compared to in vitro conditions due to an autocatalytic effect of the accumulated acidic degradation products in the medium surrounding the implants. These results suggest that the polymer composition and environmental conditions have significant effects on the degradation rate of porous PLGA foams.
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Affiliation(s)
- L Lu
- Department of Bioengineering, Rice University, Houston, TX 77005-1892, USA
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26
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Hemstrom M, Ambrose M, Donahue G, Glick L, Lai HL, Preechawong S. The clinical specialist in community health nursing: a solution for the 21st century. Public Health Nurs 2000; 17:386-91. [PMID: 11013001 DOI: 10.1046/j.1525-1446.2000.00386.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The clinical specialist (CS) in community health nursing (CHN) addresses health problems in populations and communities in ways that are different from and complimentary to strategies used by practitioners of individualized patient care. Four programs based on comprehensive assessments, systematic program planning, deliberate implementation, and both formative and summative evaluation are presented. The programs were developed by graduate students in the CHN clinical specialization major at the Frances Payne Bolton School of Nursing. With expert faculty guidance and a competency-driven program of study, strategies were implemented to promote the health of community-dwelling well elderly people, home health care nurses who provide service to patients with respiratory problems, and high school students in a private religious school. Experienced parish nurses also benefited from a program designed to enhance their skills in theological reflection. This article also describes the curricular design developed to educate this clinician for the 21st century. Lastly, continued attention to the dynamic criteria of the American Nurses Association Standards of Community Health Nursing Practice is recommended as crucial to the further development of this clinical specialization.
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Affiliation(s)
- M Hemstrom
- Frances Payne Bolton School of Nursing, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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Abstract
Although the glucose-lowering properties of metformin are well-established, its effects on glucose metabolism in skeletal muscle have not been clearly defined. We tested the effects of metformin in young adult male Sprague-Dawley rats, which have a documented reduced response to insulin in skeletal muscle. Rats were treated with metformin for 20 days (320 mg/kg/day) in the drinking water. During this period, metformin completely prevented the increase in food intake and decreased adiposity by 30%. Metformin also reduced insulin secretion by 37% following an intra-peritoneal injection of glucose. Finally, metformin enhanced transport of [3H]-2-deoxyglucose in isolated strips of soleus muscle. Metformin substantially increased insulin-stimulated transport, while having no effect on basal transport. In control rats, a maximal concentration of insulin stimulated transport 77% above basal. In metformin-treated rats, insulin stimulated transport 206% above basal. We conclude that in the Sprague-Dawley rat model, metformin causes a significant increase in insulin-responsiveness.
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Affiliation(s)
- S E Borst
- Department of Pharmacology, University of Florida and Geriatric Research, Education and Clinical Center, VA Medical Center, Gainesville 32608-1197, USA.
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Abstract
This study investigated the in vitro degradation of porous poly(L-lactic acid) (PLLA) foams during a 46-week period in pH 7.4 phosphate-buffered saline at 37 degrees C. Four types of PLLA foams were fabricated using a solvent-casting, particulate-leaching technique. The three types had initial salt weight fraction of 70, 80, and 90%, and a salt particle size of 106-150 microm, while the fourth type had 90% initial weight fraction of salt in the size range 0-53 microm. The porosities of the resulting foams were 0.67, 0.79, 0.91, and 0.84, respectively. The corresponding median pore diameters were 33, 52, 91, and 34 microm. The macroscopic degradation of PLLA foams was independent of pore morphology with insignificant variation in foam weight, thickness, pore distribution, compressive creep behavior, and morphology during degradation. However, decrease in melting temperature and slight increase in crystallinity were observed at the end of degradation. The foam half-lives based on the weight average molecular weight were 11.6+/-0.7 (70%, 106-150 microm), 15.8+/-1.2 (80%, 106-150 microm), 21.5+/-1.5 (90%, 106-150 microm), and 43.0+/-2.7 (90%, 0-53 microm) weeks. The thicker pore walls of foams prepared with 70 or 80% salt weight fraction as compared to those with 90% salt weight fraction contributed to an autocatalytic effect resulting in faster foam degradation. Also, the increased pore surface/volume ratio of foams prepared with salt in the range 0-53 microm enhanced the release of degradation products thus diminishing the autocatalytic effect and resulting in slower foam degradation compared to those with salt in the range 106-150 microm. Formation and release of crystalline PLLA particulates occurred for foams fabricated with 90% salt weight fraction at early stages of degradation. These results suggest that the degradation rate of porous foams can be engineered by varying the pore wall thickness and pore surface/volume ratio.
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Affiliation(s)
- L Lu
- Department of Bioengineering, Rice University, Houston, TX 77005-1892, USA
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29
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Lee YC, Chang CW, Su CW, Lin TN, Sun SH, Lai HL, Chern Y. The 5' untranslated regions of the rat A2A adenosine receptor gene function as negative translational regulators. J Neurochem 1999; 73:1790-8. [PMID: 10537036 DOI: 10.1046/j.1471-4159.1999.0731790.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The rat A2A adenosine receptor (A2A-R) gene contains two promoters, P1 and P2, which produce transcript 1 and transcript 2, respectively. These transcripts differ in the lengths of their 5' untranslated regions (5'UTR1: 514 bp, initiated from P1; 5'UTR2: 221 bp, initiated from P2) but encode the same protein. In the present study, we demonstrate that transcript 2 is present in various tissues at different levels, whereas transcript 1 is found only in the striatum. In the striatum, the level of transcript 2 is approximately 300-fold higher than that of transcript 1. The 5'UTR of both transcripts suppresses the expression of A2A-R and a firefly luciferase reporter gene at the translational level; this suppression is not observed after mutational inactivation of an "out-of-frame" upstream AUG codon. Translational suppression by the 5'UTR was also confirmed in cells using a bicistronic strategy. Collectively, these data suggest that P2 is the major promoter of the rat A2A-R gene. The 5'UTR of the rat A2A-R gene exerts an inhibitory effect on translation by an upstream open reading frame. Because the 5'UTR of the A2A-R gene possesses strong interspecies homology, translational suppression may be a general mechanism by which the expression of the A2A-R gene is regulated.
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Affiliation(s)
- Y C Lee
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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30
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Lai HL, Lin TH, Kao YY, Lin WJ, Hwang MJ, Chern Y. The N terminus domain of type VI adenylyl cyclase mediates its inhibition by protein kinase C. Mol Pharmacol 1999; 56:644-50. [PMID: 10462552 DOI: 10.1124/mol.56.3.644] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous results from our laboratory have shown that phosphorylation of type VI adenylyl cyclase (ACVI) by protein kinase C (PKC) caused suppression of adenylyl cyclase activity. In the present study, we investigated the role of the N terminus cytosolic domain of ACVI in this PKC-mediated inhibition of ACVI. Removal of amino acids 1 to 86 of ACVI or mutation of Ser(10) (a potential PKC phosphorylation site) into alanine significantly relieved the PKC-mediated inhibition and markedly reduced the PKC-evoked protein phosphorylation. PKC also effectively phosphorylated a recombinant N terminus cytosolic domain (amino acids 1-160) protein of ACVI and a synthetic peptide representing Ser(10). In addition, the amino acids 1 to 86 truncated mutant exhibited kinetic properties similar to those of the wild type. Taken together, these data demonstrate that the highly variable N terminus cytoplasmic domain of ACVI is a regulatory domain with a critical role in PKC-mediated suppression, which is a hallmark of this adenylyl cyclase isozyme. In addition, Ser(10) was found to serve as an acceptor for the PKC-mediated phosphorylating transfer of ACVI.
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Affiliation(s)
- H L Lai
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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31
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Huang CL, Chen HC, Huang NK, Yang DM, Kao LS, Chen JC, Lai HL, Chern Y. Modulation of dopamine transporter activity by nicotinic acetylcholine receptors and membrane depolarization in rat pheochromocytoma PC12 cells. J Neurochem 1999; 72:2437-44. [PMID: 10349853 DOI: 10.1046/j.1471-4159.1999.0722437.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To elucidate the regulation of the rat dopamine transporter (rDAT), we established several PC12 variants overexpressing the rDAT. Treating these cells with a nicotinic agonist (1,1-dimethyl-4-phenylpiperazinium iodide, 30 microM) depolarized the plasma membrane potential from -31 +/- 2 to 43 +/- 5 mV and inhibited rDAT activity significantly in a calcium- and protein kinase C-independent manner. Membrane depolarization by a high external K+ concentration or two K+ channel blockers (tetraethylammonium hydroxide and BaCl2) also resulted in a marked inhibition of rDAT activity. Such inhibition of dopamine uptake is due to a reduction in Vmax, with no marked effect on the Km for dopamine. The potency of cocaine in inhibiting dopamine uptake was not significantly altered, whereas that of amphetamine was slightly enhanced by membrane depolarization. Removing extracellular Ca2+ or blocking the voltage-sensitive L-type calcium channels using nifedipine did not exert any significant effect on the inhibition of rDAT activity by depolarization. These data confirm that calcium influx on depolarization is not required for inhibition of the rDAT. Collectively, our data suggest that rDAT activity can be altered by a neurotransmitter that modulates the membrane potential, thus suggesting an exquisite mechanism for the fine-tuning of dopamine levels in the synapse.
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Affiliation(s)
- C L Huang
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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32
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Liu FC, Wu GC, Hsieh ST, Lai HL, Wang HF, Wang TW, Chern Y. Expression of type VI adenylyl cyclase in the central nervous system: implication for a potential regulator of multiple signals in different neurotransmitter systems. FEBS Lett 1998; 436:92-8. [PMID: 9771900 DOI: 10.1016/s0014-5793(98)01098-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The aim of this study was to investigate the distribution of a calcium-inhibitable adenylyl cyclase type VI (type VI AC) in the central nervous system using an antiserum directed against the N-terminus of type VI AC. Our results indicate that type VI AC immunoreactivity is generally expressed in many brain regions with different levels of intensity. Most interestingly, the majority of the detected type VI AC immunoreactivity is present in cells of neuronal phenotype. Double immunostaining of type VI AC and markers of various neurotransmitter systems suggest that type VI AC might participate in regulation of the classical neurotransmitter systems and therefore appeared to play a very important role in the central nervous system.
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Affiliation(s)
- F C Liu
- Department of Life Science, Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
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33
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Chang YH, Conti M, Lee YC, Lai HL, Ching YH, Chern Y. Activation of phosphodiesterase IV during desensitization of the A2A adenosine receptor-mediated cyclic AMP response in rat pheochromocytoma (PC12) cells. J Neurochem 1997; 69:1300-9. [PMID: 9282956 DOI: 10.1046/j.1471-4159.1997.69031300.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Prolonged activation of an A2A adenosine receptor significantly inhibits the cellular response to subsequent stimulation (A2A desensitization). We have reported previously that activation of phosphodiesterase (PDE) contributes to A2A desensitization in PC12 cells. In the present study, we show that a type IV PDE (PDE4)-selective inhibitor (Ro 20-1724) effectively blocks the increase in PDE activity in desensitized cells. Thus, PDE4 appears to be the PDE specifically activated during A2A desensitization in PC12 cells. Prolonged treatment of PC12 cells with an A2A-selective agonist (CGS21680) leads to increased PDE4 activity in a dose-dependent manner, which can be blocked by an A2A-selective antagonist [8-(3-chlorostyryl)caffeine]. Using two PDE4 antibodies, we were able to demonstrate that the levels of two PDE4-immunoreactive bands (72 and 79 kDa) were increased significantly during A2A desensitization. Prolonged treatment with forskolin to elevate intracellular cyclic AMP contents also resulted in increased PDE4 activity. In addition, activation of PDE4 activity during A2A desensitization could be blocked by a protein kinase A (PKA)-selective inhibitor (H89) and was not observed in a PKA-deficient PC12 cell line (A123). Taken together, activation of PDE4 via a cyclic AMP/PKA-dependent pathway plays a critical role in dampening the signal of the A2A receptor.
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Affiliation(s)
- Y H Chang
- Institute of Neuroscience, National Yang-Ming Medical College, Taipei, Taiwan, R.O.C
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34
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Lai HL, Yang TH, Messing RO, Ching YH, Lin SC, Chern Y. Protein kinase C inhibits adenylyl cyclase type VI activity during desensitization of the A2a-adenosine receptor-mediated cAMP response. J Biol Chem 1997; 272:4970-7. [PMID: 9030558 DOI: 10.1074/jbc.272.8.4970] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have previously reported that phosphorylation of adenylyl cyclase type VI (AC6) may result in the suppression of adenylyl cyclase activity during desensitization of the A2a-adenosine receptor-mediated cAMP response (A2a desensitization) in rat pheochromocytoma PC12 cells. In the present study, we demonstrate that protein kinase C (PKC) is responsible for the phosphorylation and inhibition of AC6 during A2a desensitization. Inhibition of PKC by several independent methods markedly blocked the suppression of AC6 during A2a desensitization. Purified PKC from rat brain directly phosphorylated and inhibited recombinant AC6 expressed in Sf21 cells. Substantially lower AC6 activities were also observed in PC12 cells overexpressing PKCdelta or PKCepsilon. Stimulation of A2a-R in PC12 cells under the same conditions as those required for A2a desensitization resulted in an increase in Ca2+-independent PKC activity. Most importantly, exogenous PKC did not further suppress AC6 activity in A2a-desensitized membranes. In vitro PKC phosphorylation of AC6 isolated from A2a-desensitized cells was also profoundly lower than that from control cells, suggesting a specific role for PKC in regulating AC6 during A2a desensitization in PC12 cells. Taken together, our data demonstrate that a calcium-independent, novel PKC inhibits AC6 activity during A2a desensitization in PC12 cells. Independent regulation of AC6 by calcium-independent PKC and by Ca2+ provides an exquisite mechanism for integrating signaling pathways to fine-tune cAMP synthesis.
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Affiliation(s)
- H L Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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35
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Lai HL. [A report about palliative care in Japan]. Hu Li Za Zhi 1997; 44:98-102. [PMID: 9355392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Huston J, Kovacs E, Kuhlmann S, Lai HL, Owens JF, Soper D, Tung WK. Large Transverse Momentum Jet Production and the Gluon Distribution inside the Proton. Phys Rev Lett 1996; 77:444-447. [PMID: 10062814 DOI: 10.1103/physrevlett.77.444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
In the present study, we demonstrate that the Ca(2+)-inhibitable adenylyl cyclase (AC) activity in the striatum exhibits a daily oscillation with a peak occurring around 10:00 h. A circadian fluctuation of the AC activity evoked by an A2a adenosine-selective agonist was also observed. Intrastriatal injection of an A2a-selective adenosine agonist or antagonist during the interval in which the Ca(2+)-inhibitable AC activity was at its peak resulted in a more significant alteration of locomotor activity than those observed at a later interval. The marked circadian variation in the Ca(2+)-inhibitable AC activity in the striatum appears to cause a circadian fluctuation in the action of at least one neuromodulator.
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Affiliation(s)
- Y Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
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Abstract
To understand the molecular basis for the regulation of rat A2a adenosine receptor (A2a-R) expression, we have characterized the rat A2a-R gene and defined its promoter regions. Through a combination of restriction mapping and sequence analysis, we have demonstrated that the rat A2a-R gene is composed of two exons interrupted by a 7.2-kb intron. Primer extension and RNase protection on RNA isolated from PC12 cells suggested that the A2a-R gene encoded two clusters of alternative transcripts. The most upstream transcription start site was designated as +1. The sequence of the proximal 1.5 kb of 5'-flanking region demonstrated no potential TATA box, CCAAT box, or initiator element in the appropriate location. Varying lengths of 5'-flanking regions were inserted into a transient expression vector (pGL2-basic), which contained bacterial luciferase as the reporter gene, to determine its promoter region(s) in PC12 cells, CHOP cells, and C6 cells. Consistent with two clusters of transcription start sites, two independent functional promoter regions (designated P1, -67/-1; and P2, +272/+304) for the rat A2a-R gene were identified. Although both promoters are in use in PC12 cells, only P2 is active in CHOP cells, indicating possible cell line-specific usage of these two promoters.
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Affiliation(s)
- Y Y Chu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C
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Chern Y, Chiou JY, Lai HL, Tsai MH. Regulation of adenylyl cyclase type VI activity during desensitization of the A2a adenosine receptor-mediated cyclic AMP response: role for protein phosphatase 2A. Mol Pharmacol 1995; 48:1-8. [PMID: 7623763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We reported earlier that inhibition of adenylyl cyclase activity is a mechanism involved in desensitization of the A2a adenosine receptor-mediated cAMP response (A2a desensitization) in rat pheochromocytoma PC-12 cells. Here, we investigated the molecular mechanism that modulates adenylyl cyclase activity during A2a desensitization. Reversible inhibition of forskolin-evoked adenylyl cyclase activity in desensitized cells occurred after incubation with an A2a-selective adenosine agonist (CGS21680). However, when okadaic acid (a relatively protein phosphatase 2A-specific phosphatase inhibitor) was added after agonist removal, adenylyl cyclase activity did not recover. Okadaic acid caused significant dose-dependent inhibition of adenylyl cyclase activity in intact PC-12 cells. Prolonged exposure of okadaic acid-treated PC-12 cells to adenosine agonists did not evoke further inhibition, suggesting that the inhibition of adenylyl cyclase activity during A2a desensitization may operate through a pathway that overlaps with the increased phosphorylation caused by okadaic acid. Inclusion of calcium in the adenylyl cyclase assay significantly inhibited cyclase activity. indicating that PC-12 cells contain Ca(2+)-inhibitable type VI adenylyl cyclase (AC6). This was confirmed by polymerase chain reaction-based detection of AC6 cDNA. Furthermore, incubation of PC-12 cell membrane fractions with purified protein phosphatase 2A or coexpression of protein phosphatase 2A with AC6 in COS-1 cells significantly increased AC6 activity. To reduce the possible influence of Gs alpha protein, we substituted guanosine-5'-O-(2-thio)diphosphate and MnCl2 for GTP and MgCl2, respectively, in some cyclase assays and found that the suppression of AC6 during A2a desensitization and okadaic acid treatment remained largely unchanged. Taken together, these data suggest that phosphorylation of AC6 might account for the inhibition of adenylyl cyclase activity during A2a desensitization in PC-12 cells.
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Affiliation(s)
- Y Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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Huston J, Kovacs E, Kuhlmann S, Lai HL, Owens JF, Tung WK. Global QCD study of direct photon production. Phys Rev D Part Fields 1995; 51:6139-6145. [PMID: 10018378 DOI: 10.1103/physrevd.51.6139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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41
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Lai HL, Botts J, Huston J, Morfin JG, Owens JF, Qiu JW, Tung WK, Weerts H. Global QCD analysis and the CTEQ parton distributions. Phys Rev D Part Fields 1995; 51:4763-4782. [PMID: 10018953 DOI: 10.1103/physrevd.51.4763] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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42
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Chern Y, Lai HL, Fong JC, Liang Y. Multiple mechanisms for desensitization of A2a adenosine receptor-mediated cAMP elevation in rat pheochromocytoma PC12 cells. Mol Pharmacol 1993; 44:950-8. [PMID: 8246918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
To understand the regulation of A2a adenosine receptor (A2a-R) response, we examined the molecular mechanisms underlying the desensitization of A2a response in rat pheochromocytoma PC12 cells, which possess an A2a-R identical with the A2a receptor we recently cloned from rat brain. Prolonged exposure of PC12 cells to adenosine agonists significantly inhibited the response of the cells to subsequent stimulation with an A2a-selective adenosine agonist (CGS21680). No significant change in the number of binding sites and affinity for CGS21680 was observed in desensitized cells, nor did we find any significant change in the transcript level of A2a-R in cells pretreated with adenosine agonists. However, the basal adenylyl cyclase activity and the cyclase activities stimulated by adenosine agonists, by GTP gamma S, and by forskolin were reduced in desensitized cells. Prolonged exposure of PC12 cells to dibutyryl-cAMP did not significantly change either the basal or the adenosine agonist-evoked adenylyl cyclase activity. Therefore, elevation of cellular cAMP content is by itself not sufficient to produce the observed reductions of adenylyl cyclase activity with A2a desensitization. Inhibition of adenylyl cyclase activity in desensitized cells occurred after short-term (30 min) incubation with CGS21680 and could be blocked by the adenosine antagonist 8-cyclopentyl-1,3-dipropylxanthine. Gs alpha protein levels did not significantly change after a 30-min exposure to CGS21680. In contrast, long-term exposure (12-20 hr) of PC12 cells to adenosine agonists resulted in a slight further reduction of adenylyl cyclase activity and a consistent decline in the Gs alpha protein level. In addition, long-term incubation with adenosine agonists or with forskolin-enhanced phosphodiesterase (PDE) activity in the cytosolic and membrane fractions by 57 +/- 9% and 53 +/- 18%, respectively. Hydrolysis of cAMP was significantly faster in agonist-desensitized cells than in control cells. PDE might therefore play an important role in desensitization of the A2a response in PC12 cells. Polymerase chain reaction-based analysis of the mRNA for A2a-R and A2b-R indicated that both A2a-R and A2b-R were present in PC12 cells; the A2b response was also diminished in A2a-desensitized cells. Our data suggest that inhibition of adenylyl cyclase after short-term agonist treatment, down-regulation of Gs alpha protein level after long-term agonist treatment, and activation of PDE after long-term agonist treatment account for desensitization of the A2a-mediated response in PC12 cells.
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Affiliation(s)
- Y Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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Abstract
We have isolated an adenosine receptor gene (RA2) from a rat brain cDNA library. This novel rat adenosine receptor has 410 amino acids, as deduced from its base sequence, and shows 82% amino acid identity with the dog A2 receptor. Amino acid sequence analysis indicates that RA2 protein contains seven transmembrane domains and belongs to the G protein-coupled receptor family. The variations in amino acid sequences between RA2 protein and the dog A2 receptor are largely confined to the extracellular second loop and the carboxyl terminus.
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Affiliation(s)
- Y Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C
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