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Lu M, He X, Jiao Z, Hu Z, Guo Z, Dai S, Wang H, Xu D. The upregulation of glutamate decarboxylase 67 against hippocampal excitability damage in male fetal rats by prenatal caffeine exposure. ENVIRONMENTAL TOXICOLOGY 2022; 37:2703-2717. [PMID: 35917217 DOI: 10.1002/tox.23630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/25/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
As a kind of xanthine alkaloid, caffeine is widely present in beverages, food, and analgesic drugs. Our previous studies have shown that prenatal caffeine exposure (PCE) can induce programmed hypersensitivity of the hypothalamic-pituitary-adrenal (HPA) axis in offspring rats, which is involved in developing many chronic adult diseases. The present study further examined the potential molecular mechanism and toxicity targets of hippocampal dysfunction, which might mediate the programmed hypersensitivity of the HPA axis in offspring. Pregnant rats were intragastrically administered with 0, 30, and 120 mg/kg/day caffeine from gestational days (GD) 9-20, and the fetal rats were extracted at GD20. Rat fetal hippocampal H19-7/IGF1R cell line was treated with caffeine, adenosine A2A receptor (A2AR) agonist (CGS-21680) or adenylate cyclase agonist (forskolin) plus caffeine. Compared with the control group, hippocampal neurons of male fetal rats by PCE displayed increased apoptosis and reduced synaptic plasticity, whereas glutamate decarboxylase 67 (GAD67) expression was increased. Moreover, the expression of A2AR was down-regulated, PCE inhibited the cAMP/PKA/CREB/BDNF/TrkB pathway. Furthermore, the results in vitro were consistent with the in vivo study. Both CGS21680 and forskolin could reverse the above alteration caused by caffeine. These results indicated that PCE inhibits the BDNF pathway and mediates the hippocampus's glutamate (Glu) excitotoxicity. The compensatory up-regulation of GAD67 unbalanced the Glu/gamma-aminobutyric acid (GABA)ergic output, leading to the impaired negative feedback to the hypothalamus and hypersensitivity of the HPA axis.
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Affiliation(s)
- Mengxi Lu
- Department of Pharmacology, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Xia He
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Zhexiao Jiao
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Zewen Hu
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Zijing Guo
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Shiyun Dai
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Hui Wang
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| | - Dan Xu
- Department of Pharmacology, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
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Yu Y, Shi Z, Xu D, Li Y, Qin J, Zhang Z, Wang H. Prenatal ethanol exposure increases susceptibility to depression- and anxiety-like behavior in adult female offspring and its underlying mechanism. Reprod Toxicol 2020; 96:36-46. [PMID: 32497709 DOI: 10.1016/j.reprotox.2020.05.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/25/2020] [Accepted: 05/27/2020] [Indexed: 12/19/2022]
Abstract
Epidemiological investigations have found that maternal alcohol intake increases the risk of mental illness in offspring. Our study investigated changes of depression- and anxiety-like behaviors in adult offspring caused by prenatal ethanol exposure (PEE) and explored the potential mechanism. After Wistar rats were intragastrically administered ethanol at a dose of 4 g/kg·d on the 9-20 t h days of pregnancy, the offspring were given 21 days of chronic unpredictable mild stress (CUMS) starting from the 9th week after birth. Before CUMS, the behavioral results showed that the PEE offspring appeared excited and anxious. After CUMS, the PEE offspring rats were more sensitive to the same intensity of stimulation, and then the behavioral disorders aggravated. In adult offspring from the PEE group, the intercellular space was enlarged in the hippocampus, and there was a loss of pyramidal cells. The expression of brain-derived neurotrophic factor (BDNF) decreased; the mRNA expression of the glucocorticoid receptor and synaptic plasticity-related genes decreased; the apoptosis-related genes expressed disrupted. In order to determine whether hippocampal injury and dysfunction resulted from ethanol directly or indirectly, we performed in vitro study. The outcome was accompanied by disrupted gene expression related to neurogenesis and synaptic plasticity. PEE increases the susceptibility of adult female offspring to depression- and anxiety-like behaviors, and its mechanism may be related to the toxic effects of ethanol, both directly and indirectly. The latter inhibits the hippocampal BDNF pathway, leading to the disruption of hippocampal neurogenesis, apoptosis and decreased synaptic plasticity.
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Affiliation(s)
- Ying Yu
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071, China
| | - Zhaokun Shi
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Dan Xu
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071, China; Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China
| | - Ying Li
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Jun Qin
- Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Zhaohui Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Hui Wang
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071, China; Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China.
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Bcl-2 Overexpression Induces Neurite Outgrowth via the Bmp4/Tbx3/NeuroD1 Cascade in H19-7 Cells. Cell Mol Neurobiol 2019; 40:153-166. [PMID: 31493044 DOI: 10.1007/s10571-019-00732-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/29/2019] [Indexed: 12/25/2022]
Abstract
Bcl-2 is overexpressed in the nervous system during neural development and plays an important role in modulating cell survival. In addition to its anti-apoptotic function, it has been suggested previously that Bcl-2 might act as a mediator of neuronal differentiation. However, the mechanism by which Bcl-2 might influence neurogenesis is not sufficiently understood. In this study, we aimed to determine the non-apoptotic functions of Bcl-2 during neuronal differentiation. First, we used microarrays to analyze the whole-genome expression patterns of rat neural stem cells overexpressing Bcl-2 and found that Bcl-2 overexpression induced the expression of various neurogenic genes. Moreover, Bcl-2 overexpression increased the neurite length as well as expression of Bmp4, Tbx3, and proneural basic helix-loop-helix genes, such as NeuroD1, NeuroD2, and Mash1, in H19-7 rat hippocampal precursor cells. To determine the hierarchy of these molecules, we selectively depleted Bmp4, Tbx3, and NeuroD1 in Bcl-2-overexpressing cells. Bmp4 depletion suppressed the upregulation of Tbx3 and NeuroD1 as well as neurite outgrowth, which was induced by Bcl-2 overexpression. Although Tbx3 knockdown repressed Bcl-2-mediated neurite elaboration and downregulated NeuroD1 expression, it did not affect Bcl-2-induced Bmp4 expression. While the depletion of NeuroD1 had no effect on the expression of Bcl-2, Bmp4, or Tbx3, Bcl-2-mediated neurite outgrowth was suppressed. Taken together, these results demonstrate that Bcl-2 regulates neurite outgrowth through the Bmp4/Tbx3/NeuroD1 cascade in H19-7 cells, indicating that Bcl-2 may have a direct role in neuronal development in addition to its well-known anti-apoptotic function in response to environmental insults.
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Huang S, Dong W, Jiao Z, Liu J, Li K, Wang H, Xu D. Prenatal Dexamethasone Exposure Induced Alterations in Neurobehavior and Hippocampal Glutamatergic System Balance in Female Rat Offspring. Toxicol Sci 2019; 171:369-384. [PMID: 31518422 DOI: 10.1093/toxsci/kfz163] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Epidemiological investigations have suggested that periodic use of dexamethasone during pregnancy is a risk factor for abnormal behavior in offspring, but the potential mechanism remains unclear. In this study, we investigated the changes in the glutamatergic system and neurobehavior in female offspring with prenatal dexamethasone exposure (PDE) to explore intrauterine programing mechanisms. Compared with the control group, rat offspring with PDE exhibited spatial memory deficits and anxiety-like behavior. The expression of hippocampal glucocorticoid receptors (GR) and histone deacetylase 2 (HDAC2) increased, whereas histone H3 lysine 14 acetylation (H3K14ac) of brain-derived neurotrophic factor (BDNF) exon IV (BDNF IV) and expression of BDNF decreased. The glutamatergic system also changed. We further observed that changes in the fetal hippocampus were consistent with those in adult offspring. In vitro, the administration of 0.5 μM dexamethasone to the H19-7 fetal hippocampal neuron cells directly led to a cascade of changes in the GR/HDAC2/BDNF pathway, whereas the GR antagonist RU486 and the HDAC2 inhibitor romidepsin (Rom) reversed changes caused by dexamethasone to the H3K14ac level of BDNF IV and to the expression of BDNF. The increase in HDAC2 can be reversed by RU486, and the changes in the glutamatergic system can be partially reversed after supplementation with BDNF. It is suggested that PDE increases the expression of HDAC2 by activating GR, reducing the H3K14ac level of BDNF IV, inducing alterations in neurobehavior and hippocampal glutamatergic system balance. The findings suggest that BDNF supplementation and glutamatergic system improvement are potential therapeutic targets for the fetal origins of abnormal neurobehavior.
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Affiliation(s)
- Songqiang Huang
- *Department of Pharmacology, School of Basic Medical Sciences
| | - Wanting Dong
- *Department of Pharmacology, School of Basic Medical Sciences
| | - Zhexiao Jiao
- *Department of Pharmacology, School of Basic Medical Sciences
| | - Jie Liu
- *Department of Pharmacology, School of Basic Medical Sciences
| | - Ke Li
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, Hubei Province, China
| | - Hui Wang
- *Department of Pharmacology, School of Basic Medical Sciences
- Demonstration Center for Experimental Basic Medicine Education, Wuhan University
| | - Dan Xu
- *Department of Pharmacology, School of Basic Medical Sciences
- Demonstration Center for Experimental Basic Medicine Education, Wuhan University
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Park SY, Kang MJ, Han JS. Interleukin-1 beta promotes neuronal differentiation through the Wnt5a/RhoA/JNK pathway in cortical neural precursor cells. Mol Brain 2018; 11:39. [PMID: 29973222 PMCID: PMC6033214 DOI: 10.1186/s13041-018-0383-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/26/2018] [Indexed: 02/07/2023] Open
Abstract
Pro-inflammatory cytokine interleukin-1 beta (IL-1β) is a key mediator of inflammation and stress in the central nervous system (CNS), and is highly expressed in the developing brain. In this study, we investigated the possible role of IL-1β in neuronal differentiation of cortical neural precursor cells (NPCs). We showed that stimulation with IL-1β increased expression levels of neurotrophin-3 (NT3) and neurogenin 1 (Ngn1) and promoted neurite outgrowth. We also found that IL-1β increased mRNA and protein levels of Wnt5a. Knockdown of Wnt5a by transfection with Wnt5a siRNA inhibited IL-1β-induced neuronal differentiation. Moreover, IL-1β-induced Wnt5a expression was regulated by nuclear factor kappa B (NF-κB) activation, which is involved in IL-1β-mediated neuronal differentiation. To examine the role of Wnt5a in neuronal differentiation of NPCs, we exogenously added Wnt5a. We found that exogenous Wnt5a promotes neuronal differentiation, and activates the RhoA/Rho-associated kinase (ROCK)/c-jun N-terminal kinase (JNK) pathway. In addition, Wnt5a-induced neuronal differentiation was blocked by RhoA siRNA, as well as by a specific Rho-kinase inhibitor (Y27632) or a SAPK/JNK inhibitor (SP600125). Furthermore, treatment with RhoA siRNA, Y27632, or SP600125 suppressed the IL-1β-induced neuronal differentiation. Therefore, these results suggest that the sequential Wnt5a/RhoA/ROCK/JNK pathway is involved in IL-1β-induced neuronal differentiation of NPCs.
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Affiliation(s)
- Shin-Young Park
- Biomedical Research Institute and Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea
| | - Min-Jeong Kang
- Biomedical Research Institute and Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea
| | - Joong-Soo Han
- Biomedical Research Institute and Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.
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High expression of hippocampal glutamic acid decarboxylase 67 mediates hypersensitivity of the hypothalamic-pituitary-adrenal axis in response to prenatal caffeine exposure in rats. Toxicol Lett 2018; 283:39-51. [DOI: 10.1016/j.toxlet.2017.10.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 10/19/2017] [Accepted: 10/26/2017] [Indexed: 01/14/2023]
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Luo LD, Li G, Wang Y. PLD1 promotes dendritic spine development by inhibiting ADAM10-mediated N-cadherin cleavage. Sci Rep 2017; 7:6035. [PMID: 28729535 PMCID: PMC5519554 DOI: 10.1038/s41598-017-06121-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
Synapses are the basic units of information transmission, processing and integration in the nervous system. Dysfunction of the synaptic development has been recognized as one of the main reasons for mental dementia and psychiatric diseases such as Alzheimer’s disease and autism. However, the underlying mechanisms of the synapse formation are far from clear. Here we report that phospholipase D1 (PLD1) promotes the development of dendritic spines in hippocampal neurons. We found that overexpressing PLD1 increases both the density and the area of dendritic spines. On the contrary, loss of function of PLD1, including overexpression of the catalytically-inactive PLD1 (PLD1ci) or knocking down PLD1 by siRNAs, leads to reduction in the spine density and the spine area. Moreover, we found that PLD1 promotes the dendritic spine development via regulating the membrane level of N-cadherin. Further studies showed that the regulation of surface N-cadherin by PLD1 is related with the cleavage of N-cadherin by a member of the disintegrin and metalloprotease family-ADAM10. Taking together, our results indicate a positive role of PLD1 in synaptogenesis by inhibiting the ADAM10 mediated N-cadherin cleavage and provide new therapeutic clues for some neurological diseases.
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Affiliation(s)
- Li-Da Luo
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, 100191, China
| | - Gang Li
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, 100191, China
| | - Yun Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, 100191, China. .,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
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Prenatal nicotine exposure induces HPA axis-hypersensitivity in offspring rats via the intrauterine programming of up-regulation of hippocampal GAD67. Arch Toxicol 2017; 91:3927-3943. [DOI: 10.1007/s00204-017-1996-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/18/2017] [Indexed: 12/24/2022]
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PLD1 participates in BDNF-induced signalling in cortical neurons. Sci Rep 2015; 5:14778. [PMID: 26437780 PMCID: PMC4594037 DOI: 10.1038/srep14778] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/09/2015] [Indexed: 01/07/2023] Open
Abstract
The brain-derived neurotrophic factor BDNF plays a critical role in neuronal development and the induction of L-LTP at glutamatergic synapses in several brain regions. However, the cellular and molecular mechanisms underlying these BDNF effects have not been firmly established. Using in vitro cultures of cortical neurons from knockout mice for Pld1 and Rsk2, BDNF was observed to induce a rapid RSK2-dependent activation of PLD and to stimulate BDNF ERK1/2-CREB and mTor-S6K signalling pathways, but these effects were greatly reduced in Pld1(-/-) neurons. Furthermore, phospho-CREB did not accumulate in the nucleus, whereas overexpression of PLD1 amplified the BDNF-dependent nuclear recruitment of phospho-ERK1/2 and phospho-CREB. This BDNF retrograde signalling was prevented in cells silenced for the scaffolding protein PEA15, a protein which complexes with PLD1, ERK1/2, and RSK2 after BDNF treatment. Finally PLD1, ERK1/2, and RSK2 partially colocalized on endosomal structures, suggesting that these proteins are part of the molecular module responsible for BDNF signalling in cortical neurons.
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Kim Y, Lee SE, Park J, Kim M, Lee B, Hwang D, Chang S. ADP-ribosylation factor 6 (ARF6) bidirectionally regulates dendritic spine formation depending on neuronal maturation and activity. J Biol Chem 2015; 290:7323-35. [PMID: 25605715 DOI: 10.1074/jbc.m114.634527] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Recent studies have reported conflicting results regarding the role of ARF6 in dendritic spine development, but no clear answer for the controversy has been suggested. We found that ADP-ribosylation factor 6 (ARF6) either positively or negatively regulates dendritic spine formation depending on neuronal maturation and activity. ARF6 activation increased the spine formation in developing neurons, whereas it decreased spine density in mature neurons. Genome-wide microarray analysis revealed that ARF6 activation in each stage leads to opposite patterns of expression of a subset of genes that are involved in neuronal morphology. ARF6-mediated Rac1 activation via the phospholipase D pathway is the coincident factor in both stages, but the antagonistic RhoA pathway becomes involved in the mature stage. Furthermore, blocking neuronal activity in developing neurons using tetrodotoxin or enhancing the activity in mature neurons using picrotoxin or chemical long term potentiation reversed the effect of ARF6 on each stage. Thus, activity-dependent dynamic changes in ARF6-mediated spine structures may play a role in structural plasticity of mature neurons.
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Affiliation(s)
- Yoonju Kim
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and
| | - Sang-Eun Lee
- From the Department of Physiology and Biomedical Sciences, Biomembrane Plasticity Research Center, and
| | - Joohyun Park
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and
| | - Minhyung Kim
- School of Interdisciplinary Bioscience and Bioengineering and Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, South Korea, and
| | - Boyoon Lee
- Interdisciplinary Program in Neuroscience, Seoul National University College of Medicine, Seoul 110-799, South Korea
| | - Daehee Hwang
- School of Interdisciplinary Bioscience and Bioengineering and Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, South Korea, and Center for Systems Biology of Plant Senescence and Life History, Institute for Basic Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 711-873, South Korea
| | - Sunghoe Chang
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and Interdisciplinary Program in Neuroscience, Seoul National University College of Medicine, Seoul 110-799, South Korea,
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Phospholipase D1 increases Bcl-2 expression during neuronal differentiation of rat neural stem cells. Mol Neurobiol 2014; 51:1089-102. [PMID: 24986006 DOI: 10.1007/s12035-014-8773-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 06/01/2014] [Indexed: 12/12/2022]
Abstract
We studied the possible role of phospholipase D1 (PLD1) in the neuronal differentiation, including neurite formation of neural stem cells. PLD1 protein and PLD activity increased during neuronal differentiation. Bcl-2 also increased. Downregulation of PLD1 by transfection with PLD1 siRNA or a dominant-negative form of PLD1 (DN-PLD1) inhibited both neurite outgrowth and Bcl-2 expression. PLD activity was dramatically reduced by a PLCγ (phospholipase Cγ) inhibitor (U73122), a Ca(2+)chelator (BAPTA-AM), and a PKCα (protein kinase Cα) inhibitor (RO320432). Furthermore, treatment with arachidonic acid (AA) which is generated by the action of PLA2 (phospholipase A2) on phosphatidic acid (a PLD1 product), increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, indicating that PLA2 is involved in the differentiation process resulting from PLD1 activation. PGE2 (prostaglandin E2), a cyclooxygenase product of AA, also increased during neuronal differentiation. Moreover, treatment with PGE2 increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, and this effect was inhibited by a PKA inhibitor (Rp-cAMP). As expected, inhibition of p38 MAPK resulted in loss of CREB activity, and when CREB activity was blocked with CREB siRNA, Bcl-2 production also decreased. We also showed that the EP4 receptor was required for the PKA/p38MAPK/CREB/Bcl-2 pathway. Taken together, these observations indicate that PLD1 is activated by PLCγ/PKCα signaling and stimulate Bcl-2 expression through PLA2/Cox2/EP4/PKA/p38MAPK/CREB during neuronal differentiation of rat neural stem cells.
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