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Santa-Marinha L, Castanho I, Silva RR, Bravo FV, Miranda AM, Meira T, Morais-Ribeiro R, Marques F, Xu Y, Point du Jour K, Wenk M, Chan RB, Di Paolo G, Pinto V, Oliveira TG. Phospholipase D1 Ablation Disrupts Mouse Longitudinal Hippocampal Axis Organization and Functioning. Cell Rep 2021; 30:4197-4208.e6. [PMID: 32209478 DOI: 10.1016/j.celrep.2020.02.102] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 01/01/2023] Open
Abstract
Phosphatidic acid (PA) is a signaling lipid involved in the modulation of synaptic structure and functioning. Based on previous work showing a decreasing PA gradient along the longitudinal axis of the rodent hippocampus, we asked whether the dorsal hippocampus (DH) and the ventral hippocampus (VH) are differentially affected by PA modulation. Here, we show that phospholipase D1 (PLD1) is a major hippocampal PA source, compared to PLD2, and that PLD1 ablation affects predominantly the lipidome of the DH. Moreover, Pld1 knockout (KO) mice show specific deficits in novel object recognition and social interaction and disruption in the DH-VH dendritic arborization differentiation in CA1/CA3 pyramidal neurons. Also, Pld1 KO animals present reduced long-term depression (LTD) induction and reduced GluN2A and SNAP-25 protein levels in the DH. Overall, we observe that PLD1-derived PA reduction leads to differential lipid signatures along the longitudinal hippocampal axis, predominantly affecting DH organization and functioning.
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Affiliation(s)
- Luísa Santa-Marinha
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Isabel Castanho
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rita Ribeiro Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Francisca Vaz Bravo
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - André Miguel Miranda
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Torcato Meira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rafaela Morais-Ribeiro
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Fernanda Marques
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Yimeng Xu
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Kimberly Point du Jour
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Markus Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
| | - Robin Barry Chan
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Vítor Pinto
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Tiago Gil Oliveira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
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Helassa N, Antonyuk SV, Lian LY, Haynes LP, Burgoyne RD. Biophysical and functional characterization of hippocalcin mutants responsible for human dystonia. Hum Mol Genet 2017; 26:2426-2435. [PMID: 28398555 PMCID: PMC5886089 DOI: 10.1093/hmg/ddx133] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
Dystonia is a neurological movement disorder that forces the body into twisting, repetitive movements or sometimes painful abnormal postures. With the advent of next-generation sequencing technologies, the homozygous mutations T71N and A190T in the neuronal calcium sensor (NCS) hippocalcin were identified as the genetic cause of primary isolated dystonia (DYT2 dystonia). However, the effect of these mutations on the physiological role of hippocalcin has not yet been elucidated. Using a multidisciplinary approach, we demonstrated that hippocalcin oligomerises in a calcium-dependent manner and binds to voltage-gated calcium channels. Mutations T71N and A190T in hippocalcin did not affect stability, calcium-binding affinity or translocation to cellular membranes (Ca2+/myristoyl switch). We obtained the first crystal structure of hippocalcin and alignment with other NCS proteins showed significant variability in the orientation of the C-terminal part of the molecule, the region expected to be important for target binding. We demonstrated that the disease-causing mutations did not affect the structure of the protein, however both mutants showed a defect in oligomerisation. In addition, we observed an increased calcium influx in KCl-depolarised cells expressing mutated hippocalcin, mostly driven by N-type voltage-gated calcium channels. Our data demonstrate that the dystonia-causing mutations strongly affect hippocalcin cellular functions which suggest a central role for perturbed calcium signalling in DYT2 dystonia.
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Affiliation(s)
- Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK and
| | - Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
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Park SY, Yoon SN, Kang MJ, Lee Y, Jung SJ, Han JS. Hippocalcin Promotes Neuronal Differentiation and Inhibits Astrocytic Differentiation in Neural Stem Cells. Stem Cell Reports 2016; 8:95-111. [PMID: 28017654 PMCID: PMC5233403 DOI: 10.1016/j.stemcr.2016.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 11/23/2022] Open
Abstract
Hippocalcin (HPCA) is a calcium-binding protein that is restricted to nervous tissue and contributes to neuronal activity. Here we report that, in addition to inducing neurogenesis, HPCA inhibits astrocytic differentiation of neural stem cells. It promotes neurogenesis by regulating protein kinase Cα (PKCα) activation by translocating to the membrane and binding to phosphoinositide-dependent protein kinase 1 (PDK1), which induces PKCα phosphorylation. We also found that phospholipase D1 (PLD1) is implicated in the HPCA-mediated neurogenesis pathway; this enzyme promotes dephosphorylation of signal transducer and activator of transcription 3 (STAT3[Y705]), which is necessary for astrocytic differentiation. Moreover, we found that the SH2-domain-containing tyrosine phosphatase 1 (SHP-1) acts upstream of STAT3. Importantly, this SHP-1-dependent STAT3-inhibitory mechanism is closely involved in neurogenesis and suppression of gliogenesis by HPCA. Taken together, these observations suggest that HPCA promotes neuronal differentiation through activation of the PKCα/PLD1 cascade followed by activation of SHP-1, which dephosphorylates STAT3(Y705), leading to inhibition of astrocytic differentiation. Hippocalcin is required for neuronal differentiation in neural stem cells PKCα/PLD1 activation is required for hippocalcin-mediated neuronal differentiation Blocking of STAT3(Y705) activity by hippocalcin decreases astrocytic differentiation Hippocalcin promotes neurogenesis by inhibiting gliogenesis in neural stem cells
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Affiliation(s)
- Shin-Young Park
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Sung Nyo Yoon
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Min-Jeong Kang
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - YunYoung Lee
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Sung Jun Jung
- Department of Physiology, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Joong-Soo Han
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
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Kang MJ, Park SY, Han JS. Hippocalcin Is Required for Astrocytic Differentiation through Activation of Stat3 in Hippocampal Neural Precursor Cells. Front Mol Neurosci 2016; 9:110. [PMID: 27840601 PMCID: PMC5083843 DOI: 10.3389/fnmol.2016.00110] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/13/2016] [Indexed: 01/19/2023] Open
Abstract
Hippocalcin (Hpca) is a neuronal calcium sensor protein expressed in the mammalian brain. However, its function in neural stem/precursor cells has not yet been studied. Here, we clarify the function of Hpca in astrocytic differentiation in hippocampal neural precursor cells (HNPCs). When we overexpressed Hpca in HNPCs in the presence or absence of bFGF, expression levels of nerve-growth factors such as neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5), and brain-derived neurotrophic factor (BDNF), together with the proneural basic helix loop helix (bHLH) transcription factors NeuroD and neurogenin 1 (Ngn1), increased significantly. In addition, there was an increase in the number of cells expressing glial fibrillary acidic protein (GFAP), an astrocyte marker, and in branch outgrowth, indicating astrocytic differentiation of the HNPCs. Downregulation of Hpca by transfection with Hpca siRNA reduced expression of NT-3, NT-4/5, BDNF, NeuroD, and Ngn1 as well as levels of GFAP protein. Furthermore, overexpression of Hpca increased the phosphorylation of STAT3 (Ser727), and this effect was abolished by treatment with a STAT3 inhibitor (S3I-201), suggesting that STAT3 (Ser727) activation is involved in Hpca-mediated astrocytic differentiation. As expected, treatment with Stat3 siRNA or STAT3 inhibitor caused a complete inhibition of astrogliogenesis induced by Hpca overexpression. Taken together, this is the first report to show that Hpca, acting through Stat3, has an important role in the expression of neurotrophins and proneural bHLH transcription factors, and that it is an essential regulator of astrocytic differentiation and branch outgrowth in HNPCs.
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Affiliation(s)
- Min-Jeong Kang
- Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering, Hanyang University Seoul, South Korea
| | - Shin-Young Park
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University Seoul, South Korea
| | - Joong-Soo Han
- Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering, Hanyang UniversitySeoul, South Korea; Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang UniversitySeoul, South Korea
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Mutations in HPCA cause autosomal-recessive primary isolated dystonia. Am J Hum Genet 2015; 96:657-65. [PMID: 25799108 PMCID: PMC4385177 DOI: 10.1016/j.ajhg.2015.02.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 02/06/2015] [Indexed: 12/20/2022] Open
Abstract
Reports of primary isolated dystonia inherited in an autosomal-recessive (AR) manner, often lumped together as “DYT2 dystonia,” have appeared in the scientific literature for several decades, but no genetic cause has been identified to date. Using a combination of homozygosity mapping and whole-exome sequencing in a consanguineous kindred affected by AR isolated dystonia, we identified homozygous mutations in HPCA, a gene encoding a neuronal calcium sensor protein found almost exclusively in the brain and at particularly high levels in the striatum, as the cause of disease in this family. Subsequently, compound-heterozygous mutations in HPCA were also identified in a second independent kindred affected by AR isolated dystonia. Functional studies suggest that hippocalcin might play a role in regulating voltage-dependent calcium channels. The identification of mutations in HPCA as a cause of AR primary isolated dystonia paves the way for further studies to assess whether “DYT2 dystonia” is a genetically homogeneous condition or not.
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Visinin-like proteins (VSNLs): interaction partners and emerging functions in signal transduction of a subfamily of neuronal Ca2+ -sensor proteins. Cell Tissue Res 2008; 335:301-16. [PMID: 18989702 DOI: 10.1007/s00441-008-0716-3] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 09/29/2008] [Indexed: 10/21/2022]
Abstract
The visinin-like protein (VSNL) subfamily, including VILIP-1 (the founder protein), VILIP-2, VILIP-3, hippocalcin, and neurocalcin delta, constitute a highly homologous subfamily of neuronal calcium sensor (NCS) proteins. Comparative studies have shown that VSNLs are expressed predominantly in the brain with restricted expression patterns in various subsets of neurons but are also found in peripheral organs. In addition, the proteins display differences in their calcium affinities, in their membrane-binding kinetics, and in the intracellular targets to which they associate after calcium binding. Even though the proteins use a similar calcium-myristoyl switch mechanism to translocate to cellular membranes, they show calcium-dependent localization to various subcellular compartments when expressed in the same neuron. These distinct calcium-myristoyl switch properties might be explained by specificity for defined phospholipids and membrane-bound targets; this enables VSNLs to modulate various cellular signal transduction pathways, including cyclic nucleotide and MAPK signaling. An emerging theme is the direct or indirect effect of VSNLs on gene expression and their interaction with components of membrane trafficking complexes, with a possible role in membrane trafficking of different receptors and ion channels, such as glutamate receptors of the kainate and AMPA subtype, nicotinic acetylcholine receptors, and Ca(2+)-channels. One hypothesis is that the highly homologous VSNLs have evolved to fulfil specialized functions in membrane trafficking and thereby affect neuronal signaling and differentiation in defined subsets of neurons. VSNLs are involved in differentiation processes showing a tumor-invasion-suppressor function in peripheral organs. Finally, VSNLs play neuroprotective and neurotoxic roles and have been implicated in neurodegenerative diseases.
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Hippocalcin signaling via site-specific translocation in hippocampal neurons. Neurosci Lett 2008; 442:152-7. [PMID: 18634855 PMCID: PMC2572729 DOI: 10.1016/j.neulet.2008.06.089] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 06/16/2008] [Accepted: 06/24/2008] [Indexed: 11/22/2022]
Abstract
Hippocalcin is a Ca(2+)-binding protein, which belongs to the family of neuronal Ca(2+) sensors. It is highly expressed in the hippocampus but molecular mechanisms underlying its action in this part of the brain have not been investigated in detail. To study whether intrinsic neuronal activity could result in hippocalcin-mediated signal transduction we examined spontaneous and action potential (AP)-dependent changes in fluorescence of yellow fluorescent protein-tagged hippocalcin (HPCA-YFP) in transiently transfected hippocampal cultured neurons. In 6-12 DIV neurons HPCA-YFP spontaneously translocated longitudinally to specific sites within diffusionally confined domains of neuronal processes. The translocations to these sites were expressed as fast, reversible increases in HPCA-YFP fluorescence coincided with a decrease in adjacent sites indicating genuine protein translocation. Physiologically relevant neuronal stimulation with short trains of action potentials also resulted in fast, simultaneous, reversible, and [Ca(2+)](i)-dependent translocations of HPCA-YFP to several sites synchronizing hippocalcin signaling in different parts of neuronal processes. The amount of translocated protein increased with the number of action potentials in a train decoding the number of APs into the amount of translocated protein. We conclude that hippocalcin may signal within diffusionally restricted domains of neuronal processes in which it might play a physiological role in Ca(2+)-dependent local activation of specific molecular targets.
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Oh DY, Cho JH, Park SY, Kim YS, Yoon YJ, Yoon SH, Chung KC, Lee KS, Han JS. A novel role of hippocalcin in bFGF-induced neurite outgrowth of H19-7 cells. J Neurosci Res 2008; 86:1557-65. [PMID: 18183620 DOI: 10.1002/jnr.21602] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hippocalcin is a Ca2+-binding protein that is expressed mainly in pyramidal nerve cells of the hippocampus. However, its functions and mechanism in the brain remain unclear. To elucidate the role of hippocalcin, we used a conditionally immortalized hippocampal cell line (H19-7) and showed that bFGF treatment increased the expression of hippocalcin during bFGF-induced neurite outgrowth of H19-7 cells. Overexpression of hippocalcin dramatically elongated neurites and increased the expression of basic helix-loop-helix transcription factor, that is, NeuroD without bFGF stimulation. Treatment of the cells with hippocalcin siRNA completely blocked bFGF-induced neurite outgrowth and NeuroD expression. bFGF stimulation resulted in activation of phospholipase C-gamma (PLC-gamma) and an increased level of intracellular Ca2+. Hippocalcin expression by bFGF stimulation was fully blocked by both the PLC-gamma inhibitor U73122 and BAPTA-AM, a chelator of intracellular Ca2+, suggesting that hippocalcin expression by bFGF is dependent on PLC-gamma and Ca2+. Moreover, both U73122 and BAPTA-AM completely blocked bFGF-induced neurite outgrowth and NeuroD expression. Taken together, these results suggest for the first time that bFGF induces hippocalcin expression in H19-7 cells through PLC-gamma activation, which leads to neurite outgrowth.
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Affiliation(s)
- Doo-Yi Oh
- Institute of Biomedical Science and Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul, Korea
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Uys JDK, Hattingh SM, Stein DJ, Daniels WMU. Large scale hippocampal cellular distress may explain the behavioral consequences of repetitive traumatic experiences--a proteomic approach. Neurochem Res 2008; 33:1724-34. [PMID: 18307038 DOI: 10.1007/s11064-008-9615-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 01/30/2008] [Indexed: 01/22/2023]
Abstract
Early life traumatic experiences are associated with psychopathology in adulthood. This may be due in part to the effects of trauma on hippocampal development and protein expression. The purpose of the study was to investigate the effects of early life trauma and adult re-stress on ventral hippocampal protein expression. Adolescent rats (n = 19) were subjected to a triple stressor on post-natal day 28 followed 7 days later by the first re-stress session and 25 days later (post-natal day 60 = adulthood) by the second re-stress session. Ventral hippocampi were collected on post-natal day 68 for protein expression determinations using protein arrays and 2D-gel electrophoresis with liquid chromatography tandem mass spectrometry. Compared to controls, traumatized animals showed an increase in Ca(2+) homeostatic proteins, dysregulated signaling pathways and energy metabolism enzymes, cytoskeletal protein changes, a decrease in neuroplasticity regulators, energy metabolism enzymes and an increase in apoptotic initiator proteins. These results indicate the extensive impact of trauma on adult brain development and behavior.
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Affiliation(s)
- Joachim D K Uys
- Division of Medical Physiology, Department of Biomedical Sciences, University of Stellenbosch, Tygerberg Campus, Francie van Zijl Avenue, Parow Valley, 7505, Cape Town, Western Cape, South Africa
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Burgoyne RD. Neuronal calcium sensor proteins: generating diversity in neuronal Ca2+ signalling. Nat Rev Neurosci 2007; 8:182-93. [PMID: 17311005 PMCID: PMC1887812 DOI: 10.1038/nrn2093] [Citation(s) in RCA: 426] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In neurons, intracellular calcium signals have crucial roles in activating neurotransmitter release and in triggering alterations in neuronal function. Calmodulin has been widely studied as a Ca(2+) sensor that has several defined roles in neuronal Ca(2+) signalling, but members of the neuronal calcium sensor protein family have also begun to emerge as key components in a number of regulatory pathways and have increased the diversity of neuronal Ca(2+) signalling pathways. The differing properties of these proteins allow them to have discrete, non-redundant functions.
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Affiliation(s)
- Robert D Burgoyne
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, UK.
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Noguchi H, Kobayashi M, Miwa N, Takamatsu K. Lack of hippocalcin causes impairment in Ras/extracellular signal-regulated kinase cascade via a Raf-mediated activation process. J Neurosci Res 2007; 85:837-44. [PMID: 17279541 DOI: 10.1002/jnr.21180] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hippocalcin (Hpca) is a member of the neuronal calcium sensor protein family and is highly expressed in hippocampal neurons. Hpca-deficient (Hpca(-/-)) mice display a defect in cAMP response element-binding protein (CREB) activation associated with impaired spatial and associative memory. Here we examine the involvement of Hpca in the extracellular signal-regulated kinase (ERK) cascade leading to CREB activation, because application of PD98059, a broad ERK cascade inhibitor, has resulted in similar levels of CREB activation in Hpca(-/-) hippocampus. N-methyl-D-aspartate (NMDA)- and KCl-induced phosphorylation of ERK was significantly attenuated in Hpca(-/-) hippocampal slices, as was ionomycin-induced phosphorylation of ERK, whereas forskolin and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulation yielded indistinguishable levels of ERK phosphorylation in both wild-type and Hpca(-/-) slices. In an in vitro reconstitution assay system, recombinant Hpca affected neither Raf-1 protein kinase activity with recombinant MEK-1 as a substrate nor MEK-1 kinase activity with ERK2 as a substrate. Activation of Ras by NMDA and KCl stimulation of hippocampal slices showed no obvious changes between the two genotypes; however, phosphorylation of Raf-1 was significantly lower in Hpca(-/-) slices. These results suggest that Hpca plays an important role in the activation of Raf conducted by Ras.
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Affiliation(s)
- Hajime Noguchi
- Department of Physiology, Toho University School of Medicine, Ohta-ku, Tokyo, Japan
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Masuo Y, Ogura A, Kobayashi M, Masaki T, Furuta Y, Ono T, Takamatsu K. Hippocalcin protects hippocampal neurons against excitotoxin damage by enhancing calcium extrusion. Neuroscience 2006; 145:495-504. [PMID: 17257765 DOI: 10.1016/j.neuroscience.2006.12.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 11/20/2006] [Accepted: 12/05/2006] [Indexed: 11/22/2022]
Abstract
Hippocalcin, which is a member of the neuronal calcium-sensor protein family, is highly expressed in hippocampal pyramidal cells. Recently, it was demonstrated that hippocalcin deficit caused an increase in neuronal cell death in the field CA3 of Ammon's horn (CA3) region of the hippocampus following the systemic injection of kainic acid. Treatment with kainic acid results in seizure-induced cell death in CA3. In the present study, we injected quinolinic acid, which is an N-methyl-d-aspartate receptor agonist, into the hippocampal field CA1 of Ammon's horn (CA1) region in hippocalcin-knockout (-/-) mice, a procedure which mimics transient ischemia. Although significant pyknotic changes were observed at the injected site in wild-type (+/+) mice 24 h after injection, the area of pyknotic cells extended throughout the hippocampus in -/- mice. The quantification of cell numbers in Nissl-stained sections indicated that the cell damage in -/- mice was more severe than that in +/+ mice. The density of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling-positive cells roughly paralleled that of Nissl-stained pyknotic cells. Primary cultures of hippocampal neurons showed that the number of surviving neurons from -/- mice after 7 days in culture was smaller than the number from +/+ mice. The measurement of intracellular calcium concentrations in single cells revealed that the calcium extrusion from -/- neurons was slower than that from +/+ neurons. The involvement of hippocalcin in the upkeep of calcium extrusion was confirmed using hippocalcin-expressing COS7 cells. These results suggest that hippocalcin plays an important role in calcium extrusion from neurons and, in turn, helps to protect them against calcium-dependent excitotoxin damage in the hippocampus.
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Affiliation(s)
- Y Masuo
- Department of Physiology, Toho University School of Medicine, 5-21-16 Ohmori-nishi, Ohta-ku, Tokyo 143-8540, Japan.
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