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Hwang Y, Kim HC, Shin EJ. Effect of rottlerin on astrocyte phenotype polarization after trimethyltin insult in the dentate gyrus of mice. J Neuroinflammation 2022; 19:142. [PMID: 35690821 PMCID: PMC9188234 DOI: 10.1186/s12974-022-02507-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 06/01/2022] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND It has been demonstrated that reactive astrocytes can be polarized into pro-inflammatory A1 phenotype or anti-inflammatory A2 phenotype under neurotoxic and neurodegenerative conditions. Microglia have been suggested to play a critical role in astrocyte phenotype polarization by releasing pro- and anti-inflammatory mediators. In this study, we examined whether trimethyltin (TMT) insult can induce astrocyte polarization in the dentate gyrus of mice, and whether protein kinase Cδ (PKCδ) plays a role in TMT-induced astrocyte phenotype polarization. METHODS Male C57BL/6 N mice received TMT (2.6 mg/kg, i.p.), and temporal changes in the mRNA expression of A1 and A2 phenotype markers were evaluated in the hippocampus. In addition, temporal and spatial changes in the protein expression of C3, S100A10, Iba-1, and p-PKCδ were examined in the dentate gyrus. Rottlerin (5 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of A1 and A2 transcripts, p-PKCδ, Iba-1, C3, S100A10, and C1q was evaluated 6 days after TMT treatment. RESULTS TMT treatment significantly increased the mRNA expression of A1 and A2 phenotype markers, and the increased expression of A1 markers remained longer than that of A2 markers. The immunoreactivity of the representative A1 phenotype marker, C3 and A2 phenotype marker, S100A10 peaked 6 days after TMT insult in the dentate gyrus. While C3 was expressed evenly throughout the dentate gyrus, S100A10 was highly expressed in the hilus and inner molecular layer. In addition, TMT insult induced microglial p-PKCδ expression. Treatment with rottlerin, a PKCδ inhibitor, decreased Iba-1 and C3 expression, but did not affect S100A10 expression, suggesting that PKCδ inhibition attenuates microglial activation and A1 astrocyte phenotype polarization. Consistently, rottlerin significantly reduced the expression of C1q and tumor necrosis factor-α (TNFα), which has been suggested to be released by activated microglia and induce A1 astrocyte polarization. CONCLUSION We demonstrated the temporal and spatial profiles of astrocyte polarization after TMT insult in the dentate gyrus of mice. Taken together, our results suggest that PKCδ plays a role in inducing A1 astrocyte polarization by promoting microglial activation and consequently increasing the expression of pro-inflammatory mediators after TMT insult.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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Yamada K, Yoshida K. Multiple subcellular localizations and functions of protein kinase Cδ in liver cancer. World J Gastroenterol 2022; 28:188-198. [PMID: 35110944 PMCID: PMC8776529 DOI: 10.3748/wjg.v28.i2.188] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/25/2021] [Accepted: 12/31/2021] [Indexed: 02/06/2023] Open
Abstract
Protein kinase Cδ (PKCδ) is a member of the PKC family, and its implications have been reported in various biological and cancerous processes, including cell proliferation, cell death, tumor suppression, and tumor progression. In liver cancer cells, accumulating reports show the bi-functional regulation of PKCδ in cell death and survival. PKCδ function is defined by various factors, such as phosphorylation, catalytic domain cleavage, and subcellular localization. PKCδ has multiple intracellular distribution patterns, ranging from the cytosol to the nucleus. We recently found a unique extracellular localization of PKCδ in liver cancer and its growth factor-like function in liver cancer cells. In this review, we first discuss the structural features of PKCδ and then focus on the functional diversity of PKCδ based on its subcellular localization, such as the nucleus, cell surface, and extracellular space. These findings improve our knowledge of PKCδ involvement in the progression of liver cancer.
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Affiliation(s)
- Kohji Yamada
- Department of Biochemistry, The Jikei University School of Medicine, Tokyo 105-8461, Japan
| | - Kiyotsugu Yoshida
- Department of Biochemistry, The Jikei University School of Medicine, Tokyo 105-8461, Japan
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Mai HN, Sharma G, Sharma N, Shin EJ, Kim DJ, Pham DT, Trinh QD, Jang CG, Nah SY, Jeong JH, Kim HC. Genetic depletion of p53 attenuates cocaine-induced hepatotoxicity in mice. Biochimie 2019; 158:53-61. [PMID: 30576773 DOI: 10.1016/j.biochi.2018.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 12/14/2018] [Indexed: 12/13/2022]
Abstract
Cocaine, an addictive drug, is known to induce hepatotoxicity via oxidative damage and proapoptosis. Since p53, a tumor suppressor gene, plays a major role in inducing oxidative stress and apoptosis, we examined the role of p53 inhibition against cocaine-induced hepatotoxicity. Cocaine treatment significantly increased oxidative parameters (i.e., reactive oxygen species, 4-hydroxylnonenal, and protein carbonyl) in the liver of wild type (WT) mice. We found that the pharmacological (i.e. pifithrin-α) and genetic (i.e. p53 knockout) inhibition of p53 significantly attenuates cocaine-induced hepatotoxicity. Cocaine treatment increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the serum of mice, signifying hepatic damage. Consistently, these increases were attenuated by inhibition of p53, implying protection against cocaine-induced hepatic damage. In addition, cocaine treatment significantly increased PKCδ, cleaved PKCδ and p53 levels in the liver of WT mice. These increases were followed by the interaction between p53 and PKCδ, and pro-apoptotic consequences (i.e., cytosolic release of cytochrome c, activation of caspase-3, increase in Bax level and decreases in Bcl-2 and Bcl-xL levels). These changes were attenuated by p53 depletion, reflecting that the critical role of PKCδ in p53-mediated apoptotic potentials. Combined, our results suggest that the inhibition of p53 is important for protection against oxidative burdens, pro-apoptotic events, and hepatic degeneration induced by cocaine.
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Shi L. Structural Identification and Systematic Comparison of Phorbol Ester, Dioleoylglycerol, Alcohol and Sevoflurane Binding Sites in PKCδ C1A Domain. Protein J 2018; 37:539-47. [PMID: 30251087 DOI: 10.1007/s10930-018-9793-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein kinase C (PKC) is a family of signal transducing enzymes that have been implicated in anesthetic preconditioning signaling cascade. Evidences are emerging that certain exogenous neuromodulators such as n-alkanols and general anesthetics can stimulate PKC activity by binding to regulatory C1A domain of the enzyme. However, the accurate binding sites in C1A domain as well as the molecular mechanism underlying binding-stimulated PKC activation still remain unelucidated. Here, we report a systematic investigation of the intermolecular interaction of human PKCδ C1A domain with its natural activator phorbol ester (PE) and co-activator dioleoylglycerol (DOG) as well as exogenous stimulators butanol, octanol and sevoflurane. The domain is computationally identified to potentially have three spatially vicinal ligand-binding pockets 1, 2 and 3, in which the pockets 1 and 2 have previously been determined as the binding sites of PE and DOG, respectively. Systematic cross-binding analysis reveals that long-chain octanol and DOG are well compatible with the flat, nonpolar pocket 2, where the nonspecific hydrophobic contacts and van der Waals packing are primarily responsible for the binding, while the general anesthetic sevoflurane prefer to interact with the rugged, polar pocket 3 through specific hydrogen bonds and electrostatic forces. Short-chain butanol appears to bind effectively none of the three pockets. In addition, the pocket 1 consists of two angled arms 1 and 2 that are also involved in pockets 2 and 3, respectively. Dynamics characterization imparts that binding of long-chain octanol and DOG to pocket 2 or binding of sevoflurane to pocket 3 can induce a conformational displacement in arm 1 or 2, thus further opening the included angle and enlarging pocket 1, which can improve the pocket 1-PE affinity via an allosteric mechanism, consequently stimulating the PE-induced PKCδ activation.
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Shin EJ, Hwang YG, Sharma N, Tran HQ, Dang DK, Jang CG, Jeong JH, Nah SY, Nabeshima T, Kim HC. Role of protein kinase Cδ in dopaminergic neurotoxic events. Food Chem Toxicol 2018; 121:254-261. [PMID: 30195712 DOI: 10.1016/j.fct.2018.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [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: 07/16/2018] [Revised: 08/31/2018] [Accepted: 09/03/2018] [Indexed: 12/13/2022]
Abstract
The pro-apoptotic role of Protein kinase Cδ (PKCδ), a member of the novel PKC subfamily, has been well-documented in various pathological conditions. In the central nervous system, the possible role of PKCδ has been studied, mainly in the condition of dopaminergic loss. It has been suggested that the phosphorylation of PKCδ at tyrosine 311 residue (Tyr311) by redox-sensitive Src family kinases (SFKs) is critical for the caspase-3-mediated proteolytic cleavage, which produces the constitutively active cleaved form of PKCδ. Mitochondrial translocation of cleaved PKCδ has been suggested to facilitate mitochondria-derived apoptosis and oxidative burdens. Moreover, it has been suggested that PKCδ contribute to neuroinflammation through the transformation of microglia into the pro-inflammatory M1 phenotype and the assembly of membrane NADPH oxidase in dopaminergic impairments. Interestingly, mitochondrial respiratory chain inhibitors or neuroinflammogens have shown to induce PKCδ activation in dopaminergic systems. Thus, PKCδ activation may be one of the pivotal causes of neuropathologic events, and could amplify these processes further in a positive feedback manner. Furthermore, PKCδ may play an intermediary role in connecting each neuropathologic event. This review affords insight into the role of PKCδ in various dopaminergic neurotoxic models, which could provide a potential target for mitigating dopaminergic neurotoxicity.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Young Gwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Naveen Sharma
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Duy-Khanh Dang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul, 05029, Republic of Korea
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake, 470-1192, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Kim SJ, Song YS, Pham TH, Bak Y, Lee HP, Hong JT, Yoon DY. (E)-2-Methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol attenuates PMA-induced inflammatory responses in human monocytic cells through PKCδ/JNK/AP-1 pathways. Eur J Pharmacol 2018; 825:19-27. [PMID: 29371085 DOI: 10.1016/j.ejphar.2018.01.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 10/13/2017] [Revised: 01/11/2018] [Accepted: 01/17/2018] [Indexed: 12/20/2022]
Abstract
(E)-2-Methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol (MMPP), a new (E)-2,4-bis(p-hydroxyphenyl)-2 - butenal derivative, reportedly has therapeutic effects such as anti-arthritic properties. Although previous studies showed that MMPP has anti-arthritic effects on rheumatoid arthritis (RA), the anti-inflammation mechanism of MMPP remains unclear. In this study, phorbol-12-myristate 13-acetate (PMA) was used as an inflammatory stimulus to evaluate the detailed mechanism of the MMPP-mediated anti-inflammatory effect in human monocytic THP-1 cells. We investigated the effects of MMPP on inflammation-related pathways including protein kinase Cδ (PKCδ), mitogen-activated protein kinase, and activator protein-1 (AP-1). PMA induced the translocation of PKCs from the cytosol to the membrane and phosphorylated JNK. MMPP inhibited PMA-induced membrane translocation of PKCδ, phosphorylation of JNK, and nuclear translocation of AP-1, resulting in downregulation of cyclooxygenase-2 and chemokine ligand 5 production. These findings indicate that MMPP inhibits inflammatory responses in THP-1 cells by mitigating PMA-induced activation of PKCδ and JNK and nuclear translocation of AP-1. Therefore, MMPP may be useful as an anti-inflammatory drug.
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Affiliation(s)
- Soo-Jin Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Republic of Korea
| | - Yong-Seok Song
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Republic of Korea
| | - Thu-Huyen Pham
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Republic of Korea
| | - Yesol Bak
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Republic of Korea
| | - Hee-Pom Lee
- College of Pharmacy and Medical Research Center, Chungbuk National University, 194-31 Osongsaemgmyeong 1-ro, Osong-eup, Heungdeok-gu, Cheongju, Chungbuk 28160, Republic of Korea
| | - Jin-Tae Hong
- College of Pharmacy and Medical Research Center, Chungbuk National University, 194-31 Osongsaemgmyeong 1-ro, Osong-eup, Heungdeok-gu, Cheongju, Chungbuk 28160, Republic of Korea
| | - Do-Young Yoon
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Republic of Korea.
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Shin EJ, Tran HQ, Nguyen PT, Jeong JH, Nah SY, Jang CG, Nabeshima T, Kim HC. Role of Mitochondria in Methamphetamine-Induced Dopaminergic Neurotoxicity: Involvement in Oxidative Stress, Neuroinflammation, and Pro-apoptosis-A Review. Neurochem Res 2017; 43:66-78. [PMID: 28589520 DOI: 10.1007/s11064-017-2318-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/08/2023]
Abstract
Methamphetamine (MA), an amphetamine-type psychostimulant, is associated with dopaminergic toxicity and has a high abuse potential. Numerous in vivo and in vitro studies have suggested that impaired mitochondria are critical in dopaminergic toxicity induced by MA. Mitochondria are important energy-producing organelles with dynamic nature. Evidence indicated that exposure to MA can disturb mitochondrial energetic metabolism by inhibiting the Krebs cycle and electron transport chain. Alterations in mitochondrial dynamic processes, including mitochondrial biogenesis, mitophagy, and fusion/fission, have recently been shown to contribute to dopaminergic toxicity induced by MA. Furthermore, it was demonstrated that MA-induced mitochondrial impairment enhances susceptibility to oxidative stress, pro-apoptosis, and neuroinflammation in a positive feedback loop. Protein kinase Cδ has emerged as a potential mediator between mitochondrial impairment and oxidative stress, pro-apoptosis, or neuroinflammation in MA neurotoxicity. Understanding the role and underlying mechanism of mitochondrial impairment could provide a molecular target to prevent or alleviate dopaminergic toxicity induced by MA.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Phuong-Tram Nguyen
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul, 05029, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake, 470-1192, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Liu M, Shi G, Yang KC, Gu L, Kanthasamy AG, Anantharam V, Dudley SC. Role of protein kinase C in metabolic regulation of the cardiac Na + channel. Heart Rhythm 2016; 14:440-447. [PMID: 27989687 DOI: 10.1016/j.hrthm.2016.12.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND The reduced form of nicotinamide adenine dinucleotide (NADH) increases in cardiomyopathy, activates protein kinase C (PKC), up-regulates mitochondrial reactive oxygen species (mitoROS), and down-regulates the cardiac Na+ channel (NaV1.5). OBJECTIVE The purpose of this study was to determine how NADH signals down-regulation of NaV1.5. METHODS Isolated mouse cardiomyocytes were used for patch-clamp recording and for monitoring mitoROS with MitoSOX Red. HEK293 cells were used for transient transfections. HEK293 cells stably expressing human NaV1.5 were used for single channel recording, whole-cell patch-clamp recording, activity measurements of phospholipase C and phospholipase D (PLD), channel protein purification, and co-immunoprecipitation with PKC isoforms. HL-1 cells were used for mitochondria isolation. RESULTS NADH enhanced PLD activity (1.6- ± 0.1-fold, P <.01) and activated PKCδ. Activated PKCδ translocated to mitochondria and up-regulated mitoROS (2.8- ± 0.3-fold, P <.01) by enhancing the activities of mitochondrial complexes I, II, and IV (1.1- to 1.5-fold, P <.01). PKCδ also interacted with NaV1.5 to down-regulate Na+ current (INa). Reduction in INa by activated PKCδ was prevented by antioxidants and by mutating the known PKC phosphorylation site S1503. At the single channel level, the mechanism of current reduction by PKC and recovery by protein kinase A was a change in single channel conductance. CONCLUSION NADH activated PKCδ by enhancing PLD activity. PKCδ modulated both mitoROS and NaV1.5. PKCδ elevated mitoROS by enhancing mitochondrial oxidative phosphorylation complex activities. PKCδ-mediated channel phosphorylation and mitoROS were both required to down-regulate NaV1.5 and alter single channel conductance.
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Affiliation(s)
- Man Liu
- Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island
| | - Guangbin Shi
- Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island
| | - Kai-Chien Yang
- Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island; Graduate Institute of Pharmacology, National Taiwan University School of Medicine, Taipei City, Taiwan
| | - Lianzhi Gu
- Section of Cardiology, University of Illinois at Chicago, Chicago, Illinois
| | - Anumantha G Kanthasamy
- Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa
| | - Vellareddy Anantharam
- Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa
| | - Samuel C Dudley
- Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island; Providence VA Medical Center, Providence, Rhode Island.
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Shin EJ, Dang DK, Tran HQ, Nam Y, Jeong JH, Lee YH, Park KT, Lee YS, Jang CG, Hong JS, Nabeshima T, Kim HC. PKCδ knockout mice are protected from para-methoxymethamphetamine-induced mitochondrial stress and associated neurotoxicity in the striatum of mice. Neurochem Int 2016; 100:146-158. [PMID: 27623093 DOI: 10.1016/j.neuint.2016.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [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: 04/19/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 12/16/2022]
Abstract
Para-methoxymethamphetamine (PMMA) is a para-ring-substituted amphetamine derivative sold worldwide as an illegal psychotropic drug. Although PMMA use has been reported to lead to severe intoxication and even death, little is known about the mechanism(s) by which PMMA exerts its neurotoxic effects. Here we found that PMMA treatment resulted in phosphorylation of protein kinase Cδ (PKCδ) and subsequent mitochondrial translocation of cleaved PKCδ. PMMA-induced oxidative stress was more pronounced in mitochondria than in the cytosol. Moreover, treatment with PMMA consistently resulted in significant reductions in mitochondrial membrane potential, mitochondrial complex I activity, and mitochondrial Mn superoxide dismutase-immunoreactivity. In contrast, PMMA treatment led to a significant increase in intramitochondrial Ca2+ level. Treatment with PMMA also significantly increased ionized calcium binding adaptor molecule 1 (Iba-1)-labeled microglial activation and upregulated tumor necrosis factor alpha (TNF-α) gene expression. PKCδ knockout attenuated these mitochondrial effects and dampened the neurotoxic effects of PMMA. Importantly, TNF-α knockout mice were significantly protected from PMMA-induced increases in phospho-PKCδ expression, mitochondrial translocation of cleaved PKCδ, and Iba-1-labeled microgliosis. Both rottlerin, a pharmacological inhibitor of PKCδ, and etanercept, a pharmacological inhibitor of TNF-α, significantly protected against PMMA-mediated induction of apoptosis, as assessed by terminal deoxynucleotidyl transferase dUDP nick end labeling (TUNEL) assays. In addition, PKCδ knockout and TNF-α knockout both resulted in decreased PMMA-mediated induction of dopaminergic loss. Therefore, our results suggest that PKCδ mediates PMMA-induced neurotoxicity by facilitating oxidative stress (mitochondria > cytosol), mitochondrial dysfunction, microglial activation, and pro-apoptotic signaling. Our results also indicate that PMMA-induced PKCδ activation requires the proinflammatory cytokine TNF-α.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Duy-Khanh Dang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Yunsung Nam
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Young Hun Lee
- Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Kyung Tae Park
- Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Yong Sup Lee
- Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jau-Shyong Hong
- Neuropharmacology Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Toshitaka Nabeshima
- Nabeshima Laboratory, Graduate School of Pharmaceutical Sciences, Meijo University, Nagoya, 468-8503, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Abstract
Platelets upon activation change their shape, aggregate and secrete alpha and dense granule contents among which ADP acts as a feedback activator. Different Protein Kinase C (PKC) isoforms have specific non-redundant roles in mediating platelet responses including secretion and thrombus formation. Murine platelets lacking specific PKC isoforms have been used to evaluate the isoform specific functions. Novel PKC isoform δ has been shown to play an important role in some pathological processes. Lack of specific inhibitors for PKCδ has restricted analysis of its role in various cells. The current study was carried out to evaluate a novel small molecule PKCδ inhibitor, CGX1037 in platelets. Platelet aggregation, dense granule secretion and western blotting experiments were performed to evaluate CGX1037. In human platelets, CGX1037 inhibited PAR4-mediated phosphorylation on PKD2, a PKCδ-specific substrate. Pre-treatment of human or murine platelets with CGX1037 inhibited PAR4-mediated dense granule secretion whereas it potentiated GPVI-mediated dense granule secretion similar to the responses observed in murine platelets lacking PKCδ· Furthermore, pre-treatment of platelets from PKCδ(-/-) mice with CGX1037 had no significant additive effect on platelet responses suggesting the specificity of CGX1037. Hence, we show that CGX1037 is a selective small molecule inhibitor of PKCδ in platelets.
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Affiliation(s)
- Dheeraj Bhavanasi
- Department of Physiology, Temple University School of Medicine , Philadelphia, PA , USA
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