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ADAP1/Centaurin-α1 Negatively Regulates Dendritic Spine Function and Memory Formation in the Hippocampus. eNeuro 2021; 8:ENEURO.0111-20.2020. [PMID: 33139322 PMCID: PMC7808333 DOI: 10.1523/eneuro.0111-20.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 09/25/2020] [Accepted: 10/01/2020] [Indexed: 12/27/2022] Open
Abstract
ADAP1/Centaurin-α1 (CentA1) functions as an Arf6 GTPase-activating protein highly enriched in the brain. Previous studies demonstrated the involvement of CentA1 in brain function as a regulator of dendritic differentiation and a potential mediator of Alzheimer’s disease (AD) pathogenesis. To better understand the neurobiological functions of CentA1 signaling in the brain, we developed Centa1 knock-out (KO) mice. The KO animals showed neither brain development nor synaptic ultrastructure deficits in the hippocampus. However, they exhibited significantly higher density and enhanced structural plasticity of dendritic spines in the CA1 region of the hippocampus compared with non-transgenic (NTG) littermates. Moreover, the deletion of Centa1 improved performance in the object-in-place (OIP) spatial memory task. These results suggest that CentA1 functions as a negative regulator of spine density and plasticity, and of hippocampus-dependent memory formation. Thus, CentA1 and its downstream signaling may serve as a potential therapeutic target to prevent memory decline associated with aging and brain disorders.
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Best MD. Global approaches for the elucidation of phosphoinositide-binding proteins. Chem Phys Lipids 2013; 182:19-28. [PMID: 24220499 DOI: 10.1016/j.chemphyslip.2013.10.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/13/2013] [Accepted: 10/29/2013] [Indexed: 12/22/2022]
Abstract
Phosphoinositide lipids (PIPns) control numerous critical biological pathways, typically through the regulation of protein function driven by non-covalent protein-lipid binding interactions. Despite the importance of these systems, the unraveling of the full scope of protein-PIPn interactions has represented a significant challenge due to the massive complexity associated with these events, including the large number of diverse proteins that bind to these lipids, variations in the mechanisms by which proteins bind to lipids, and the presence of multiple distinct PIPn isomers. As a result of this complexity, global methods in which numerous proteins that bind PIPns can be identified and characterized simultaneously from complex samples, which have been enabled by key technological advancements, have become popular as an efficient means for tackling this challenge. This review article provides an overview of advancements in large-scale methods for profiling protein-PIPn binding, including experimental methods, such as affinity enrichment, microarray analysis and activity-based protein profiling, as well as computational methods, and combined computational/experimental efforts.
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Affiliation(s)
- Michael D Best
- Department of Chemistry, The University of Tennessee, 1420 Circle Drive, Knoxville, TN 37996, United States.
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Borrmann C, Stricker R, Reiser G. Tubulin potentiates the interaction of the metalloendopeptidase nardilysin with the neuronal scaffold protein p42IP4/centaurin-α1 (ADAP1). Cell Tissue Res 2011; 346:89-98. [PMID: 21972134 DOI: 10.1007/s00441-011-1245-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 09/12/2011] [Indexed: 11/25/2022]
Abstract
We found colocalization of the neuronal protein p42(IP4) (centaurin-α1; ArfGAP with dual pleckstrin homology domain [ADAP1]), the metalloendopeptidase nardilysin (NRD; involved in axonal maturation and myelination) and tubulin in the cytosol and at the plasma membrane of SH-SY5Y neuroblastoma cells. To examine the importance of tubulin for the interaction of NRD with p42(IP4), we treated cells with nocodazole, which interferes with tubulin polymerization. Nocodazole did not affect the colocalization of p42(IP4) and tubulin but caused a clear redistribution of the proteins in cells, so that the colocalization of p42(IP4), tubulin and NRD was visible exclusively in multiple foci. To reveal the mechanism of the interaction between NRD, p42(IP4) and tubulin observed in neuronal cells, we performed Far-Western blotting, a technique that directly detects protein-protein interactions on Western blots. This technique demonstrated that tubulin enhanced the binding of NRD to functionally renatured p42(IP4). The mutation of a highly conserved cysteine residue in NRD to alanine abolished the potentiation by tubulin. NRD lacking the characteristic acidic domain was able to bind p42(IP4) but addition of tubulin did not significantly potentiate the binding of this deletion mutant to p42(IP4). A function-abolishing mutation of the Zn(2+)-binding motif of NRD did not affect the potentiation by tubulin. Thus, the capacity of tubulin to enhance the interaction between p42(IP4) and NRD together with the known interaction of p42(IP4) with F-actin support the novel notion that p42(IP4) plays a possible role as a linker between the two networks, actin and tubulin, in neural cells.
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Affiliation(s)
- Claudia Borrmann
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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Galvita A, Grachev D, Azarashvili T, Baburina Y, Krestinina O, Stricker R, Reiser G. The brain-specific protein, p42(IP4) (ADAP 1) is localized in mitochondria and involved in regulation of mitochondrial Ca2+. J Neurochem 2009; 109:1701-13. [PMID: 19383085 DOI: 10.1111/j.1471-4159.2009.06089.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In brain, p42(IP4) (centaurin-alpha1; recently named ADAP 1, which signifies ADP ribosylation factor GTPase activating protein with dual PH domains 1, within the large family of Arf-GTPase activating proteins) is mainly expressed in neurons. p42(IP4) operates as a dual receptor recognising two second messengers, the soluble inositol(1,3,4,5)tetrakisphosphate and the lipid phosphatidylinositol(3,4,5)trisphosphate. We show here for the first time that p42(IP4) is localized in mitochondria, isolated from rat brain and from cells transfected with p42(IP4). In rat brain mitochondria we additionally found interaction of p42(IP4) with 2', 3'-cyclic nucleotide 3'-phosphodiesterase and alpha-tubulin by pull-down binding assay and by immunoprecipitation. In mitochondria from Chinese hamster ovary cells, p42(IP4) is predominantly associated with the intermembrane space and the inner membrane. This localization of p42(IP4) indicates that p42(IP4) might have a still unknown mitochondrial function. We studied whether p42(IP4) is involved in Ca(2+)-induced permeability transition pore opening, which is important in mitochondrial events leading to programmed cell death. We used mouse neuroblastoma cells as a model for the functional studies of p42(IP4) in mitochondria. In mitochondria isolated from p42(IP4)-transfected mouse neuroblastoma cells, over-expression of p42(IP4) significantly decreased Ca(2+) capacity and lag time for Ca(2+) retention. Thus, we suggest that p42(IP4) is involved in the regulation of Ca(2+) transport in mitochondria. We propose that p42(IP4) promotes Ca(2+)-induced permeability transition pore opening and thus destabilizes mitochondria.
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Affiliation(s)
- Anastasia Galvita
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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5
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Bernstein HG, Stricker R, Lendeckel U, Bertram I, Dobrowolny H, Steiner J, Bogerts B, Reiser G. Reduced neuronal co-localisation of nardilysin and the putative alpha-secretases ADAM10 and ADAM17 in Alzheimer's disease and Down syndrome brains. AGE (DORDRECHT, NETHERLANDS) 2009; 31:11-25. [PMID: 19234765 PMCID: PMC2645990 DOI: 10.1007/s11357-008-9076-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 07/29/2008] [Indexed: 05/27/2023]
Abstract
The peptidase nardilysin is involved in degradation of neuropeptides and limited intracellular proteolysis. Recent reports point to an involvement of nardilysin in the pathophysiology of Alzheimer's disease. Nardilysin enhances the alpha-secretase activity of the disintegrin and metalloproteases (ADAMs) 10 and 17, thereby possibly contributing to reduced generation of amyloidogenic fragments from the amyloid precursor protein. A prerequisite for the alpha-secretase-stimulating effect of nardilysin on the activity of ADAMs in vivo is cellular co-expression of nardilysin with ADAM10 and/or ADAM17. We immunolocalised nardilysin, ADAM10, and ADAM17 in cortical regions of normal aged brain, in Alzheimer's disease, and in Down syndrome brains and counted the number of protease-expressing neurons. A considerable portion of neurons co-express nardilysin together with either ADAM10 or ADAM17. Compared to controls, in Alzheimer's disease and in Down syndrome brains there is a decreased cellular expression of all three antigens, and a reduction in the number of those neurons that co-express nardilysin with ADAM10 or with ADAM17. Our data are consistent with the notion that the proposed alpha-secretase-enhancing activity of nardilysin might play a role in human brain pathology.
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Affiliation(s)
- Hans-Gert Bernstein
- Department of Psychiatry, Medical Faculty, University of Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany.
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6
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Haase A, Nordmann C, Sedehizade F, Borrmann C, Reiser G. RanBPM, a novel interaction partner of the brain-specific protein p42IP4/centaurin α-1. J Neurochem 2008; 105:2237-48. [DOI: 10.1111/j.1471-4159.2008.05308.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Moore CD, Thacker EE, Larimore J, Gaston D, Underwood A, Kearns B, Patterson SI, Jackson T, Chapleau C, Pozzo-Miller L, Theibert A. The neuronal Arf GAP centaurin alpha1 modulates dendritic differentiation. J Cell Sci 2007; 120:2683-93. [PMID: 17635995 PMCID: PMC2810648 DOI: 10.1242/jcs.006346] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Centaurin alpha1 is an Arf GTPase-activating protein (GAP) that is highly expressed in the nervous system. In the current study, we show that endogenous centaurin alpha1 protein is localized in the synaptosome fraction, with peak expression in early postnatal development. In cultured dissociated hippocampal neurons, centaurin alpha1 localizes to dendrites, dendritic spines and the postsynaptic region. siRNA-mediated knockdown of centaurin alpha1 levels or overexpression of a GAP-inactive mutant of centaurin alpha1 leads to inhibition of dendritic branching, dendritic filopodia and spine-like protrusions in dissociated hippocampal neurons. Overexpression of wild-type centaurin alpha1 in cultured hippocampal neurons in early development enhances dendritic branching, and increases dendritic filopodia and lamellipodia. Both filopodia and lamellipodia have been implicated in dendritic branching and spine formation. Following synaptogenesis in cultured neurons, wild-type centaurin alpha1 expression increases dendritic filopodia and spine-like protrusions. Expression of a GAP-inactive mutant diminishes spine density in CA1 pyramidal neurons within cultured organotypic hippocampal slice cultures. These data support the conclusion that centaurin alpha1 functions through GAP-dependent Arf regulation of dendritic branching and spines that underlie normal dendritic differentiation and development.
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Affiliation(s)
- Carlene D. Moore
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Erin E. Thacker
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jennifer Larimore
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David Gaston
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Alison Underwood
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Brian Kearns
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sean I. Patterson
- IHEM-CONICET, Departmento de Morfo-Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Trevor Jackson
- Departments of Physiology and Dermatology, School of Clinical and Laboratory Sciences, Medical School, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Chris Chapleau
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Anne Theibert
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Author for correspondence ()
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Bernstein HG, Stricker R, Dobrowolny H, Trübner K, Bogerts B, Reiser G. Histochemical evidence for wide expression of the metalloendopeptidase nardilysin in human brain neurons. Neuroscience 2007; 146:1513-23. [PMID: 17442499 DOI: 10.1016/j.neuroscience.2007.02.057] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 02/22/2007] [Accepted: 02/22/2007] [Indexed: 11/17/2022]
Abstract
Nardilysin is a metalloendopeptidase that in vitro cleaves peptides such as dynorphin-A, somatostatin-28, alpha-neoendorphin and glucagon at the N-terminus of arginine and lysine residues in dibasic moieties. The enzyme is highly expressed in many endocrine tissues. Nardilysin has also been found in the brain. Previously, we have detected that nardilysin interacts with brain-specific proteins, i.e. p42(IP4)/centaurin-alpha1 [Stricker R, Chow KM, Walther D, Hanck T, Hersh LB, Reiser G (2006) Interaction of the brain specific protein p42(IP4)/centaurin-alpha1 with the peptidase nardilysin is regulated by the cognate ligands of p42(IP4), PtdIns(3,4,5)P(3) and Ins(1,3,4,5)P(4), with stereospecificity. J Neurochem 98:343-354]. However, very little is known about the distribution of nardilysin in the brain. The aim of the present study was to reveal its regional distribution and cellular localization in developing and adult human brain. Using immunohistochemistry and Western blot analysis we demonstrate that the enzyme is widely, but unevenly, expressed in the human brain. We found high staining intensity in the hypothalamus, neocortex and brain stem nuclei. The cellular localization is almost exclusively confined to neurons. In pre- and perinatal human brain cortex, most neurons express the enzyme. In cortical neurons nardilysin protein was found to be partially co-localized with parvalbumin but not calretinin. No co-expression was seen with somatostatin-28 immunoreactivity. A considerable overlap was revealed between p42(IP4) and nardilysin. Our data support the hypothesis that nardilysin might possibly play a role in brain development, whereas its putative function in brain peptide metabolism remains to be clarified further.
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Affiliation(s)
- H-G Bernstein
- Department of Psychiatry, Medical Faculty of University of Magdeburg, Leipziger Str. 44, D-39120 Magdeburg, Germany.
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9
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Venkateswarlu K, Brandom KG, Yun H. PI-3-kinase-dependent membrane recruitment of centaurin-alpha2 is essential for its effect on ARF6-mediated actin cytoskeleton reorganisation. J Cell Sci 2007; 120:792-801. [PMID: 17284522 DOI: 10.1242/jcs.03373] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
GTPase activating proteins (GAPs) of the centaurin family regulate the actin cytoskeleton and vesicle trafficking through inactivation of the ADP-ribosylation factor (ARF) family of small GTP-binding proteins. We report the functional characterisation of centaurin-alpha(2), which is structurally related to the centaurin-alpha(1) ARF6 GAP. centaurin-alpha(2) contains an N-terminal GAP domain followed by two pleckstrin homology (PH) domains (N-PH and C-PH). In vitro, GFP-centaurin-alpha(2) specifically binds the phosphatidylinositol (PI) 3-kinase lipid products, PI 3,4-P(2) and PI 3,4,5-P(3) (PIP(3)), through its C-terminal PH domain. In agreement with this observation, GFP-centaurin-alpha(2) was recruited to the plasma membrane from the cytosol in EGF-stimulated cells in a PI-3-kinase-dependent manner. Moreover, the C-PH domain is sufficient and necessary for membrane recruitment of centaurin-alpha(2). centaurin-alpha(2) shows sustained kinetics of PI-3-kinase-mediated membrane recruitment in EGF-stimulated cells, owing to its binding to PI 3,4-P(2). centaurin-alpha(2) prevents ARF6 translocation to, and cortical actin formation at, the plasma membrane, which are phenotypic indications for ARF6 activation in EGF-stimulated cells. Moreover, the constitutively active mutant of ARF6 reverses the effect of centaurin-alpha(2) on cortical actin formation. The membrane targeted centaurin-alpha(2) is constitutively active. Together, these studies indicate that centaurin-alpha(2) is recruited in a sustained manner to the plasma membrane through binding to PI 3,4-P(2) and thereby regulates actin reorganisation via ARF6.
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Stricker R, Chow KM, Walther D, Hanck T, Hersh LB, Reiser G. Interaction of the brain-specific protein p42IP4/centaurin-alpha1 with the peptidase nardilysin is regulated by the cognate ligands of p42IP4, PtdIns(3,4,5)P3 and Ins(1,3,4,5)P4, with stereospecificity. J Neurochem 2006; 98:343-54. [PMID: 16805830 DOI: 10.1111/j.1471-4159.2006.03869.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The brain-specific protein p42IP4, also called centaurin-alpha1, specifically binds phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4]. Here, we investigate the interaction of p42IP4/centaurin-alpha1 with nardilysin (NRDc), a member of the M16 family of zinc metalloendopeptidases. Members of this peptidase family exhibit enzymatic activity and also act as receptors for other proteins. We found that p42IP4/centaurin-alpha1 binds specifically to NRDc from rat brain. We further detected that centaurin-alpha2, a protein that is highly homologous to p42IP4/centaurin-alpha1 and expressed ubiquitously, also binds to NRDc. In vivo interaction was demonstrated by co-immunoprecipitation of p42IP4/centaurin-alpha1 with NRDc from rat brain. The acidic domain of NRDc (NRDc-AD), which does not participate in catalysis, is sufficient for the protein interaction with p42IP4. Interestingly, preincubation of p42IP4 with its cognate ligands D-Ins(1,3,4,5)P4 and the lipid diC8PtdIns(3,4,5)P3 negatively modulates the interaction between the two proteins. D-Ins(1,3,4,5)P4 and diC8PtdIns(3,4,5)P3 suppress the interaction with virtually identical concentration dependencies. This inhibition is highly ligand specific. The enantiomer L-Ins(1,3,4,5)P4 is not effective. Similarly, the phosphoinositides diC8PtdIns(3,4)P2, diC8PtdIns(3,5)P2 and diC8PtdIns(4,5)P2 all have no influence on the interaction. Further experiments revealed that endogenous p42IP4 from rat brain binds to glutathione-S-transferase (GST)-NRDc-AD. The proteins dissociate from each other when incubated with D-Ins(1,3,4,5)P4, but not with inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. In summary, we demonstrate that p42IP4 binds to NRDc via the NRDc-AD, and that this interaction is controlled by the cognate cellular ligands of p42IP4/centaurin-alpha1. Thus, specific ligands of p42IP4 can modulate the recruitment of proteins, which are docked to p42IP4, to specific cellular compartments.
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Affiliation(s)
- Rolf Stricker
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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Centaurin-alpha1 and KIF13B kinesin motor protein interaction in ARF6 signalling. Biochem Soc Trans 2005; 33:1279-81. [PMID: 16246098 DOI: 10.1042/bst0331279] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The ARF (ADP-ribosylation factor) family of small GTPases regulate intracellular membrane trafficking by cycling between an inactive GDP- and an active GTP-bound form. Among the six known mammalian ARFs (ARF1-ARF6), ARF6 is the least conserved and plays critical roles in membrane trafficking and cytoskeletal dynamics near the cell surface. Since ARFs have undetectable levels of intrinsic GTP binding and hydrolysis, they are totally dependent on extrinsic GEFs (guanine nucleotide-exchange factors) for GTP binding and GAPs (GTPase-activating proteins) for GTP hydrolysis. We have recently isolated a novel KIF (kinesin) motor protein (KIF13B) that binds to centaurin-alpha1, an ARF6GAP that binds to the second messenger PIP3 [PtdIns(3,4,5)P3]. KIFs transport intracellular vesicles and recognize their cargo by binding to proteins (receptors) localized on the surface of the cargo vesicles. Identification of centaurin-alpha1 as a KIF13B interactor suggests that KIF13B may transport ARF6 and/or PIP3 using centaurin-alpha1 as its receptor. This paper reviews the studies carried out to assess the interaction and regulation of centaurin-alpha1 by KIF13B.
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Sedehizade F, von Klot C, Hanck T, Reiser G. p42IP4/Centaurin α1, a Brain-specific PtdIns(3,4,5)P3/Ins(1,3,4,5)P4-binding Protein: Membrane Trafficking Induced by Epidermal Growth Factor is Inhibited by Stimulation of Phospholipase C-coupled Thrombin Receptor. Neurochem Res 2005; 30:1319-30. [PMID: 16341594 DOI: 10.1007/s11064-005-8804-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2005] [Indexed: 10/25/2022]
Abstract
The brain-specific 42-kDa protein, p42(IP4), contains a N-terminal zinc finger (ZF) motif and a tandem of two pleckstrin homology (PH) domains. p42(IP4) binds in vitro the second messengers phosphatidylinositol(3,4,5)trisphosphate (PtdIns(3,4,5)P3) and inositol(1,3,4,5)tetrakisphosphate (Ins(1,3,4,5)P4). We observed by confocal microscopy in live HEK 293 cells the GFP-p42(IP4), a chimera of human p42(IP4) and green fluorescence protein (GFP). There, we studied the influence of thrombin, which raises Ins(1,3,4,5)P4, on membrane translocation of GFP-p42(IP4), induced by epidermal growth factor (EGF). Thrombin in the presence of LiCl inhibited the EGF-induced membrane recruitment of GFP-p42(IP4). In the absence of LiCl, thrombin weakened the EGF-mediated membrane recruitment of GFP-p42(IP4). Furthermore, the participation of p42(IP4) protein domains on the EGF-mediated membrane translocation was analyzed. We used several p42(IP4) variants, in which one of the domains was deleted. Alternatively, single p42(IP4) domain-GFP fusion proteins were generated. Only the p42(IP4) variant lacking the ZF domain showed a very weak membrane translocation in response to EGF stimulation, but all the other p42(IP4) variants did not translocate. Thus, we conclude that the combination of both PH domains with ZF is required for membrane translocation of p42(IP4).
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Affiliation(s)
- Fariba Sedehizade
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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Venkateswarlu K, Hanada T, Chishti AH. Centaurin-α1 interacts directly with kinesin motor protein KIF13B. J Cell Sci 2005; 118:2471-84. [PMID: 15923660 DOI: 10.1242/jcs.02369] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Centaurin-α1 is a phosphatidylinositol 3,4,5-trisphosphate binding protein as well as a GTPase activating protein (GAP) for the ADP-ribosylation factor (ARF) family of small GTPases. To further understand its cellular function, we screened a rat brain cDNA library using centaurin-α1 as bait to identify centaurin-α1 interacting proteins. The yeast two-hybrid screen identified a novel kinesin motor protein as a centaurin-α1 binding partner. The motor protein, termed KIF13B, encoded by a single ∼9.5-kb transcript, is widely expressed with high levels observed in brain and kidney. Yeast two-hybrid and GST pull-down assays showed that the interaction between centaurin-α1 and KIF13B is direct and mediated by the GAP domain of centaurin-α1 and the stalk domain of KIF13B. Centaurin-α1 and KIF13B form a complex in vivo and the KIF13B interaction appears to be specific to centaurin-α1 as other members of the ARF GAP family did not show any binding activity. We also show that KIF13B and centaurin-α1 colocalize at the leading edges of the cell periphery whereas a deletion mutant of centaurin-α1 that lacks the KIF13B binding site, failed to colocalize with KIF13B in vivo. Finally, we demonstrate that KIF13B binding suppresses the ARF6 GAP activity of centaurin-α1 in intact cells. Together, our data suggest a mechanism where direct binding between centaurin-α1 and KIF13B could concentrate centaurin-α1 at the leading edges of cells, thus modulating ARF6 function.
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Affiliation(s)
- Kanamarlapudi Venkateswarlu
- Department of Pharmacology, School of Medical Sciences, The University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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Reiser G, Bernstein HG. Altered expression of protein p42IP4/centaurin-alpha 1 in Alzheimer's disease brains and possible interaction of p42IP4 with nucleolin. Neuroreport 2004; 15:147-8. [PMID: 15106847 DOI: 10.1097/00001756-200401190-00028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The protein p42IP4 (centaurin-alpha1) is a brain-specific InsP4/PtdIns3 (PIP)-binding protein, whish is localized in neurons of the human brain. In Alzheimer's disease (AD) the intraneuronal expression of the protein was shown to be elevated. In addition, p42IP4 immunostaining decorated neuritic plaques. Attempting to explain the putative role of the protein in AD, we have concentrated on its well-known interactions with casein kinase I, which is known to be prominently involved in AD pathophysiology. Meanwhile, specific interaction of p42IP4 with nucleolin, another player in AD pathology, has been revealed. Based on these data, we propose alternative concepts of how p42IP4 might act in AD pathomechanisms.
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Affiliation(s)
- Georg Reiser
- Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Medizinische Fakultät, Germany.
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Thacker E, Kearns B, Chapman C, Hammond J, Howell A, Theibert A. The Arf6 GAP centaurin α-1 is a neuronal actin-binding protein which also functions via GAP-independent activity to regulate the actin cytoskeleton. Eur J Cell Biol 2004; 83:541-54. [PMID: 15679100 DOI: 10.1078/0171-9335-00416] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Centaurin alpha-1 is a high-affinity PtdIns(3,4,5)P3-binding protein enriched in brain. Sequence analysis indicates centaurin alpha-1 contains two pleckstrin homology domains, ankyrin repeats and an Arf GAP homology domain, placing it in the AZAP family of phosphoinositide-regulated Arf GAPs. Other members of this family are involved in actin cytoskeletal and focal adhesion organization. Recently, it was reported that centaurin alpha-1 expression diminishes cortical actin and decreases Arf6GTP levels consistent with it functioning as an Arf6 GAP in vivo. In the current report, we show that centaurin alpha-1 binds Arfs in vitro and colocalizes with Arf6 and Arf5 in vivo, further supporting an interaction with Arfs. Centaurin alpha-1 expression produces dramatic effects on the actin cytoskeleton, decreasing stress fibers, diminishing cortical actin, and enhancing membrane ruffles and filopodia. Expression of centaurin alpha-1 also enhances cell spreading and disrupts focal adhesion protein localization. The effects of centaurin alpha-1 on stress fibers and cell spreading are reminiscent of those of Arf6GTP. Consistent with this, we show that many of the centaurin alpha-1-induced effects on the actin cytoskeleton and actin-dependent activities do not require GAP activity. Thus, centaurin alpha-1 likely functions via both GAP-dependent and GAP-independent mechanisms to regulate the actin cytoskeleton. Furthermore, we demonstrate that in vitro, centaurin alpha-1 binds F-actin directly, with actin binding activity localized to the PtdIns(3,4,5)P3-binding PH domain. Our data suggest that centaurin alpha-1 may be a component of the neuronal PI 3-kinase cascade that leads to regulation of the neuronal actin cytoskeleton.
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Affiliation(s)
- Erin Thacker
- Department of Neurobiology and Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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16
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Hanck T, Stricker R, Sedehizade F, Reiser G. Identification of gene structure and subcellular localization of human centaurin α2, and p42IP4, a family of two highly homologueous, Ins 1,3,4,5-P4-/PtdIns 3,4,5-P3-binding, adapter proteins. J Neurochem 2003; 88:326-36. [PMID: 14690521 DOI: 10.1046/j.1471-4159.2003.02143.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proteins which recognize the two messengers phosphatidylinositol 3,4,5-trisphosphate (PtdInsP3), a membrane lipid, and inositol 1,3,4,5-tetrakisphosphate (InsP4), a water-soluble ligand, play important roles by integrating external stimuli, which lead to differentiation, cell death or survival. p42IP4, a PtdInsP3/InsP4-binding protein, is predominantly expressed in brain. The recently described centaurin alpha2 of similar molecular mass which is 58% identical and 75% homologous to the human p42IP4 orthologue, is expressed rather ubiquitously in many tissues. Here, elucidating the gene structure for both proteins, we found the human gene for centaurin alpha2 located on chromosome 17, position 17q11.2, near to the NF1 locus, and human p42IP4 on chromosome 7, position 7p22.3. The two isoforms, which both have 11 exons and conserved exon/intron transitions, seem to result from gene duplication. Furthermore, we studied binding of the two second messengers, PtdInsP3 and InsP4, and subcellular localization of the two proteins. Using recombinant baculovirus we expressed centaurin alpha2 and p42IP4 in Sf9 cells and purified the proteins to homogeneity. Recombinant centaurin alpha2 bound both InsP4 and PtdInsP3 equally well in vitro. Furthermore, fusion proteins of centaurin alpha2 and p42IP4, respectively, with the green fluorescent protein (GFP) were expressed in HEK 293 cells to visualize subcellular distribution. In contrast to p42IP4, which was distributed throughout the cell, centaurin alpha2 was concentrated at the plasma membrane already in unstimulated cells. The protein centaurin alpha2 was released from the membrane upon addition of wortmannin, which inhibits PI3-kinase. p42IP4, however, translocated to plasma membrane upon growth factor stimulation. Thus, in spite of the high homology between centaurin alpha2 and p42IP4 and comparable affinities for InsP4 and PtdInsP3, both proteins showed clear differences in subcellular distribution. We suggest a model, which is based on the difference in phosphoinositide binding stoichiometry of the two proteins, to account for the difference in subcellular localization.
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Affiliation(s)
- Theodor Hanck
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke Universität Magdeburg, Magdeburg, Germany
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17
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Stricker R, Vandekerckhove J, Krishna MU, Falck JR, Hanck T, Reiser G. Oligomerization controls in tissue-specific manner ligand binding of native, affinity-purified p42IP4/centaurin α1 and cytohesins—proteins with high affinity for the messengers d-inositol 1,3,4,5-tetrakisphosphate/phosphatidylinositol 3,4,5-trisphosphate. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2003; 1651:102-15. [PMID: 14499594 DOI: 10.1016/s1570-9639(03)00241-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Several distinct receptor proteins for the second messengers Ins(1,3,4,5)P(4) and PtdIns(3,4,5)P(3) are already known, such as the brain-specific p42(IP4), which we have previously cloned from different species, and cytohesins. However, it is still unclear whether proteins interacting with phosphoinositide and inositolpolyphosphate second messengers are regulated differently in different tissues. Here, we investigated these native proteins for comparison also from rat lung cytosol and purified them by PtdIns(3,4,5)P(3) affinity chromatography. Proteins selectively binding Ins(1,3,4,5)P(4) with high affinity also showed high affinity and specificity towards PtdIns(3,4,5)P(3). In lung cytosol, two prominent protein bands were found in the eluate from a PtdIns(3,4,5)P(3) affinity column. We identified these proteins by mass spectrometry as the cytohesin family of Arf guanosine nucleotide exchange factors (cytohesin 1, ARNO, GRP-1) and as Bruton's tyrosine kinase. Western blot analysis indicated that p42(IP4) was present in lung only at very low concentrations. Applying the affinity purification scheme established for rat lung cytosol to cytosol from rat brain, however, yielded only p42(IP4). We identified cytohesins in rat brain by Western blotting and PCR, but cytohesins surprisingly did not bind to the PtdIns(3,4,5)P(3)-affinity column. Gel filtration experiments of brain cytosol revealed that brain cytohesins are bound to large molecular weight complexes (150 to more than 500 kDa). Thus, we hypothesize that this finding explains why brain cytohesins apparently do not bind the inositolphosphate ligand. In lung cytosol, on the other hand, cytohesins occur as dimers. Gel filtration also showed that p42(IP4) in brain cytosol occurs as a monomer. Thus, oligomerization (homomeric or heteromeric) of InsP(4)/PtdInsP(3) binding proteins can modulate their function in a tissue-dependent manner because it can modify their ability to interact with the ligands.
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Affiliation(s)
- Rolf Stricker
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, 39120 Magdeburg, Germany
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18
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Aggensteiner M, Reiser G. Expression of the brain-specific membrane adapter protein p42IP4/centaurin alpha, a Ins(1,3,4,5)P4/PtdIns(3,4,5)P3 binding protein, in developing rat brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 142:77-87. [PMID: 12694946 DOI: 10.1016/s0165-3806(03)00033-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Inositolphosphates and phosphatidylinositides are important second messengers. Previously p42(IP4), a protein with high affinity for both Ins(1,3,4,5)P(4) and PtdIns(3,4,5)P(3) has been characterized in our laboratory. In the present study mRNA levels of p42(IP4) were quantified during development (ages: 7, 14, 21 days and adult) by means of ribonuclease protection assay in various rat brain regions (cerebellum, cortex, striatum, thalamus, hypothalamus, olfactory bulb, hippocampus and tectum (superior and inferior colliculus)). A high level of p42(IP4) mRNA was detected in the cortex (ca. 1 pg specific RNA per microg of total RNA) which stayed highly independent of the age of the animals. In hippocampus and in the thalamus, p42(IP4) mRNA levels were comparable to those in the cortex in the first and second week postnatally, but decreased to lower levels in the adult brain. In striatum, the mRNA increased, albeit less intensely than in hippocampus and thalamus, until day 21 postnatally, and then decreased in the adult rat brain. Cerebellar p42(IP4) mRNA showed a slow increase within the first 3 weeks postnatally, and remained rather high in the adult brain. The protein expression of p42(IP4), tested within the same samples by Western blot staining, was consistent with mRNA values. For comparison, glutamic acid decarboxylase (isoforms GAD65/GAD67), an enzyme, for which some regional brain specific distribution is already known, was also examined. The mRNA levels of GAD and its developmental regulation clearly differed from that of p42(IP4). In summary, p42(IP4) expressed in several neuronal cell types, did not seem to be restricted to specific developmental stages, but the high absolute expression levels at all developmental stages indicated that p42(IP4) is a protein fundamental for neuronal functioning.
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Affiliation(s)
- Michael Aggensteiner
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
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19
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Dubois T, Zemlickova E, Howell S, Aitken A. Centaurin-alpha 1 associates in vitro and in vivo with nucleolin. Biochem Biophys Res Commun 2003; 301:502-8. [PMID: 12565890 DOI: 10.1016/s0006-291x(02)03010-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Centaurin-alpha(1) was originally described as a binding partner for phosphoinositides. In spite of the presence of a putative ADP-ribosylation factor (ARF) GTPase-activating protein (GAP) domain, no ARF-GAP activity has been attributed to centaurin-alpha(1) so far. Thus the function of this protein remains to be determined. In order to better understand its intracellular role, we aimed to identify centaurin-alpha(1) partners. Using affinity chromatography followed by mass spectrometry analysis, we identified several potential centaurin-alpha(1) protein partners. Nucleolin, a nucleolar protein involved in ribosome biosynthesis, was the main centaurin-alpha(1) interacting protein. The interaction between centaurin-alpha(1) and nucleolin was confirmed by Western blot analysis and GST pull down assays. Moreover, we have shown that ectopically expressed centaurin-alpha(1) associates in vivo with endogenous nucleolin in human embryonic kidney 293 cells. In addition, the association between nucleolin and centaurin-alpha(1) was disrupted by RNAse treatment, indicating that RNA integrity was necessary for their binding. This suggested that centaurin-alpha(1) was part of a ribonucleoprotein complex.
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Affiliation(s)
- Thierry Dubois
- Division of Biomedical and Clinical Laboratory Sciences, The University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK.
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20
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Reiser G, Bernstein HG. Neurons and plaques of Alzheimer's disease patients highly express the neuronal membrane docking protein p42IP4/centaurin alpha. Neuroreport 2002; 13:2417-9. [PMID: 12499840 DOI: 10.1097/00001756-200212200-00008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The protein p42(IP4) (also called centaurin alpha), identified as a brain-specific InsP4/PtdInsP3 (PIP3)-binding protein, has been shown to be localized in human brain, specifically expressed in neurons. Several casein kinases have been found to be involved in Alzheimer's disease (AD) pathology. Since casein kinase I was reported to possess a binding domain for p42(IP4), we here investigated the expression and localization of p42(IP4) in AD brains. In cortical neurons of AD brains intracellular immunostaining for p42(IP4) exceeded the level seen in these neurons of normal brain. Statistically, significantly more p42(IP4)-immunoreactive neurons were found in temporal and angular cortex of AD patients as compared to control brain. Mostly impressively, neuritic plaques displayed a very prominent signal. Thus, we suggest that the up-regulated p42(IP4) in AD neurons may serve as a docking protein to recruit signaling molecules such as different subtypes of casein kinase I to the plasma membrane. This is the first indication for a functional interaction of these protein in possible neuronal damage. Therefore proteins such as p42(IP4), central players in signaling, may be appropriate targets for preventing neurodegenerative processes.
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Affiliation(s)
- Georg Reiser
- Klinik für Psychiatrie, Psychotherapie und Psychosomatische Medizin, Medizinische Fakultät, Leipziger Strasse 44, 39120 Magdeburg, Germany
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21
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Neri LM, Borgatti P, Capitani S, Martelli AM. The nuclear phosphoinositide 3-kinase/AKT pathway: a new second messenger system. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1584:73-80. [PMID: 12385889 DOI: 10.1016/s1388-1981(02)00300-1] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipid second messengers, particularly those derived from the polyphosphoinositide cycle, play a pivotal role in several cell signaling networks. Phosphoinositide 3-kinases (PI3Ks) generate specific inositol lipids that have been implicated in a plethora of cell functions. One of the best-characterized targets of PI3K lipid products is the serine/threonine protein kinase Akt. Recent findings have implicated Akt in cancer progression because it stimulates cell proliferation and suppresses apoptosis. Evidence accumulated over the past 15 years has highlighted the presence of an autonomous nuclear inositol lipid metabolism, and suggests that lipid molecules are important components of signaling pathways operating within the nucleus. PI3Ks, their lipid products, and Akt have also been identified at the nuclear level. In this review, we shall summarize the most updated findings about these molecules in relationship with the nuclear compartment and provide an overview of the possible mechanisms by which they regulate important cell functions.
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Affiliation(s)
- Luca M Neri
- Dipartimento di Morfologia ed Embriologia, Sezione di Anatomia Umana, Università di Ferrara, via Fossato di Mortara 66, 44100 Ferrara, Italy.
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22
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Sly BJ, Hazel JC, Popodi EM, Raff RA. Patterns of gene expression in the developing adult sea urchin central nervous system reveal multiple domains and deep-seated neural pentamery. Evol Dev 2002; 4:189-204. [PMID: 12054292 DOI: 10.1046/j.1525-142x.2002.02002.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The adult sea urchin central nervous system (CNS) is composed of five radial nerve cords connected to a circular nerve ring. Although much is known about the molecular mechanisms underlying the development and function of the nervous systems of many invertebrate and vertebrate species, virtually nothing is known about these processes in echinoderms. We have isolated a set of clones from a size-selected cDNA library prepared from the nervous system of the sea urchin Heliocidaris erythrogramma for use as probes. A total of 117 expressed sequence clones were used to search the GenBank database. Identified messages include genes that encode signaling proteins, cytoskeletal elements, cell surface proteins and receptors, cell proliferation and differentiation factors, transport and channel proteins, and a RNA DEAD box helicase. Expression was analyzed by RNA gel blot hybridization to document expression through development. Many of the genes have apparently neural limited expression and function, but some have been co-opted into new roles, notably associated with exocytotic events at fertilization. Localization of gene expression by whole-mount in situ hybridization shows that the morphologically simple sea urchin radial CNS exhibits complex organization into localized transcriptional domains. The transcription patterns reflect the morphological pentamery of the echinoderm CNS and provide no indication of an underlying functional bilateral symmetry in the CNS.
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Affiliation(s)
- Belinda J Sly
- Indiana Molecular Biology Institute and Department of Biology, Indiana University, Bloomington 47405, USA
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23
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Whitley P, Gibbard AM, Koumanov F, Oldfield S, Kilgour EE, Prestwich GD, Holman GD. Identification of centaurin-alpha2: a phosphatidylinositide-binding protein present in fat, heart and skeletal muscle. Eur J Cell Biol 2002; 81:222-30. [PMID: 12018390 DOI: 10.1078/0171-9335-00242] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe here the cloning, expression and characterisation of centaurin-alpha2 from a rat adipocyte cDNA library. The centaurin-alpha2 cDNA contains an open reading frame, which codes for a protein of 376 amino acids with predicted mass of 43.5 kDa. Centaurin-alpha2 shares 51-59% identity with centaurin-alpha1 proteins and has the same domain organisation, consisting of a predicted N-terminal ArfGAP domain followed by two successive pleckstrin homology domains. Despite the sequence similarity, there are a number of notable differences between the previously characterised centaurin-alpha1 proteins and the newly described centaurin-alpha2: (i) in vitro lipid binding experiments with centaurin-alpha2 do not reveal the same selectivity for phosphatidylinositol 3,4,5-trisphosphate over phosphatidylinositol 4,5-bisphosphate that has been shown for centaurin-alpha; (ii) unlike centaurin-alpha1 which is expressed mainly in the brain, centaurin-alpha2 has a broad tissue distribution, being particularly abundant in fat, heart and skeletal muscle; (iii) in contrast to centaurin-alpha1 which is found in both membrane and cytosolic fractions, endogenous centaurin-alpha2 is exclusively present in the dense membrane fractions of cell extracts, suggesting a constitutive membrane association. Insulin stimulation, which stimulates phosphatidylinositol 3,4,5-trisphosphate production, does not alter the subcellular distribution of centaurin-alpha2 between adipocyte membrane fractions. This observation is consistent with the lack of specificity of centaurin-alpha2 for phosphatidylinositol 3,4,5-trisphosphate over phosphatidylinositol 4,5-bisphosphate.
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Affiliation(s)
- Paul Whitley
- Department of Biology and Biochemistry, University of Bath, United Kingdom
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24
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Sedehizade F, Hanck T, Stricker R, Horstmayer A, Bernstein HG, Reiser G. Cellular expression and subcellular localization of the human Ins(1,3,4,5)P(4)-binding protein, p42(IP4), in human brain and in neuronal cells. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 99:1-11. [PMID: 11869802 DOI: 10.1016/s0169-328x(01)00335-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this study we describe for the human inositol-(1,3,4,5)-tetrakisphosphate (InsP4)-binding protein, p42IP4, the cellular distribution and subcellular localization in human brain and in transfected neuronal cells. The cDNA sequence of the human p42IP4 containing a single open reading frame yields a peptide of 374 amino acids with a calculated molecular mass of 43.4 kDa with a zinc-finger motif at the N-terminus, followed by two pleckstrin homology (PH) domains. Using a peptide-specific antiserum, p42IP4 protein was localized in a majority of neuronal cells of human brain sections. In the hypothalamus a subpopulation of paraventricular and infundibular nucleus neurons were strongly immunoreactive for p42IP4. In cortical areas the protein was predominantly found in large pyramidal cells. Some immunoreactivity for p42IP4 was also observed in the pyramidal cells of the hippocampal formation. Functional expression of p42IP4 protein in neuronal (NG108-15) and non-neuronal (CHO-K1) cells stably transfected with GFP-p42IP4 was shown in all cell fractions (homogenate, cytosol and membranes) by specific [3H]Ins(1,3,4,5)P4 binding activity, which correlated with p42IP4 protein detection by Western blot analysis. Using confocal laser scanning microscopy we showed that in NG108-15 and CHO-K1 cells stably transfected with GFP-p42IP4 the full length p42IP4 protein was localized in the cytoplasm, at the plasma membrane and in the nucleus. A deletion mutant of p42IP4 lacking the zinc finger domain resulted in solely a cytosolic and membrane localization but was not found in the nucleus. Thus we can conclude that human p42IP4 shows a region-specific localization in the human brain and the zinc finger motif within the protein is responsible for the localization of the protein in the cell nucleus.
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Affiliation(s)
- Fariba Sedehizade
- Institut für Neurobiochemie, Otto-von-Guericke Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
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25
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Krugmann S, Anderson KE, Ridley SH, Risso N, McGregor A, Coadwell J, Davidson K, Eguinoa A, Ellson CD, Lipp P, Manifava M, Ktistakis N, Painter G, Thuring JW, Cooper MA, Lim ZY, Holmes AB, Dove SK, Michell RH, Grewal A, Nazarian A, Erdjument-Bromage H, Tempst P, Stephens LR, Hawkins PT. Identification of ARAP3, a novel PI3K effector regulating both Arf and Rho GTPases, by selective capture on phosphoinositide affinity matrices. Mol Cell 2002; 9:95-108. [PMID: 11804589 DOI: 10.1016/s1097-2765(02)00434-3] [Citation(s) in RCA: 230] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We show that matrices carrying the tethered homologs of natural phosphoinositides can be used to capture and display multiple phosphoinositide binding proteins in cell and tissue extracts. We present the mass spectrometric identification of over 20 proteins isolated by this method, mostly from leukocyte extracts: they include known and novel proteins with established phosphoinositide binding domains and also known proteins with surprising and unusual phosphoinositide binding properties. One of the novel PtdIns(3,4,5)P3 binding proteins, ARAP3, has an unusual domain structure, including five predicted PH domains. We show that it is a specific PtdIns(3,4,5)P3/PtdIns(3,4)P2-stimulated Arf6 GAP both in vitro and in vivo, and both its Arf GAP and Rho GAP domains cooperate in mediating PI3K-dependent rearrangements in the cell cytoskeleton and cell shape.
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Affiliation(s)
- S Krugmann
- Inositide Laboratory, The Babraham Institute, Cambridge, CB2 4AT, United Kingdom
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26
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Dubois T, Kerai P, Zemlickova E, Howell S, Jackson TR, Venkateswarlu K, Cullen PJ, Theibert AB, Larose L, Roach PJ, Aitken A. Casein kinase I associates with members of the centaurin-alpha family of phosphatidylinositol 3,4,5-trisphosphate-binding proteins. J Biol Chem 2001; 276:18757-64. [PMID: 11278595 DOI: 10.1074/jbc.m010005200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian casein kinases I (CKI) belong to a family of serine/threonine protein kinases involved in diverse cellular processes including cell cycle progression, membrane trafficking, circadian rhythms, and Wnt signaling. Here we show that CKIalpha co-purifies with centaurin-alpha(1) in brain and that they interact in vitro and form a complex in cells. In addition, we show that the association is direct and occurs through the kinase domain of CKI within a loop comprising residues 217-233. These residues are well conserved in all members of the CKI family, and we show that centaurin-alpha(1) associates in vitro with all mammalian CKI isoforms. To date, CKIalpha represents the first protein partner identified for centaurin-alpha(1). However, our data suggest that centaurin-alpha(1) is not a substrate for CKIalpha and has no effect on CKIalpha activity. Centaurin-alpha(1) has been identified as a phosphatidylinositol 3,4,5-trisphosphate-binding protein. Centaurin-alpha(1) contains a cysteine-rich domain that is shared by members of a newly identified family of ADP-ribosylation factor guanosine trisphosphatase-activating proteins. These proteins are involved in membrane trafficking and actin cytoskeleton rearrangement, thus supporting a role for CKIalpha in these biological events.
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Affiliation(s)
- T Dubois
- University of Edinburgh, Division of Biomedical and Clinical Laboratory Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD
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27
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Cocco L, Martelli AM, Gilmour RS, Rhee SG, Manzoli FA. Nuclear phospholipase C and signaling. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1530:1-14. [PMID: 11341954 DOI: 10.1016/s1388-1981(00)00169-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- L Cocco
- Cellular Signaling Laboratory, Department of Anatomical Sciences and Skeletal Muscle Pathophysiology, University of Bologna, Italy.
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28
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Jackson TR, Kearns BG, Theibert AB. Cytohesins and centaurins: mediators of PI 3-kinase-regulated Arf signaling. Trends Biochem Sci 2000; 25:489-95. [PMID: 11050434 DOI: 10.1016/s0968-0004(00)01644-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Receptor-activated phosphoinositide (PI) 3-kinases produce PtdIns(3, 4,5)P(3) and its metabolite PtdIns(3,4)P(2) that function as second messengers in membrane recruitment and activation of target proteins. The cytohesin and centaurin protein families are potential targets for PtdIns(3,4,5)P(3) that also regulate and interact with Arf GTPases. Consequently, these families are poised to transduce PI 3-kinase activation into coordinated control of Arf-dependent pathways. Proposed downstream events in PI 3-kinase-regulated Arf cascades include modulation of vesicular trafficking and the actin cytoskeleton.
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Affiliation(s)
- T R Jackson
- Dept of Haematology, Royal Free and University College Medical School, Royal Free Campus, Rowland Hill St, NW3 2PF, London, UK.
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29
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Rao VR, Corradetti MN, Chen J, Peng J, Yuan J, Prestwich GD, Brugge JS. Expression cloning of protein targets for 3-phosphorylated phosphoinositides. J Biol Chem 1999; 274:37893-900. [PMID: 10608855 DOI: 10.1074/jbc.274.53.37893] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI 3'-K) family of lipid kinases play a critical role in cell proliferation, survival, vesicle trafficking, motility, cytoskeletal rearrangements, and oncogenesis. To identify downstream effectors of PI 3'-K, we developed a novel screen to isolate proteins that bind to the major products of PI 3'-K: phosphatidylinositol-3,4-bisphosphate (PtdIns-3,4-P(2)) and PtdIns-3,4,5-trisphosphate (PtdIns-3,4,5-P(3)). This screen uses synthetic biotinylated analogs of these lipids in conjunction with libraries of radiolabeled proteins that are produced by coupled in vitro transcription/translation reactions. The feasibility of the screen was initially demonstrated using avidin-coated beads prebound to biotinylated PtdIns-3,4-P(2) and PtdIns-3,4,5-P(3) to specifically isolate the pleckstrin homology domain of the serine/threonine kinase Akt. We then demonstrated the utility of this technique in isolating novel 3'-phosphorylated phosphatidylinositol (3'-PPI)-binding proteins through the preliminary screening of in vitro transcribed/translated cDNAs from a small pool expression library derived from mouse spleen. Three proteins were isolated that bound specifically to 3'PPIs. Two of these proteins have been previously characterized as PIP3BP/p42(IP4) and the PtdIns-3,4,5-P(3)-dependent serine/threonine kinase phosphoinositide-dependent kinase 1. The third protein is a novel protein that contains only a Src homology 2 domain and a pleckstrin homology domain; this protein has a higher specificity for both PtdIns-3,4,5-P(3) and PtdIns-3,4-P(2) than for PtdIns-4, 5-bisphosphate. Transcripts of this novel gene are present in every tissue analyzed but are most prominently expressed in spleen. We have renamed this new protein PHISH for 3'-phosphoinositide-interacting Src homology-containing protein. This report demonstrates the utility of this technique for isolating and characterizing 3'-PPI-binding proteins and has broad applicability for the isolation of binding domains for other lipid products.
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Affiliation(s)
- V R Rao
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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30
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Stricker R, Adelt S, Vogel G, Reiser G. Translocation between membranes and cytosol of p42IP4, a specific inositol 1,3,4,5-tetrakisphosphate/phosphatidylinositol 3,4, 5-trisphosphate-receptor protein from brain, is induced by inositol 1,3,4,5-tetrakisphosphate and regulated by a membrane-associated 5-phosphatase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 265:815-24. [PMID: 10504414 DOI: 10.1046/j.1432-1327.1999.00795.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The highly conserved 42-kDa protein, p42IP4 was identified recently from porcine brain. It has also been identified similarly in bovine, rat and human brain as a protein with two pleckstrin homology domains that binds Ins(1,3,4,5)P4 and PtdIns(3,4,5)P3 with high affinity and selectivity. The brain-specific p42IP4 occurs both as membrane-associated and cytosolic protein. Here, we investigate whether p42IP4 can be translocated from membranes by ligand interaction. p42IP4 is released from cerebellar membranes by incubation with Ins(1,3,4,5)P4. This dissociation is concentration-dependent (> 100 nM), occurs within a few minutes and and is ligand-specific. p42IP4 specifically associates with PtdIns(3, 4,5)P3-containing lipid vesicles and can dissociate from these vesicles by addition of Ins(1,3,4,5)P4. p42IP4 is only transiently translocated from the membranes as Ins(1,3,4,5)P4 can be degraded by a membrane-associated 5-phosphatase to Ins(1,3,4)P3. Then, p42IP4 re-binds to the membranes from which it can be re-released by re-addition of Ins(1,3,4,5)P4. Thus, Ins(1,3,4,5)P4 specifically induces the dissociation from membranes of a PtdIns(3,4,5)P3 binding protein that can reversibly re-associate with the membranes. Quantitative analysis of the inositol phosphates in rat brain tissue revealed a concentration of Ins(1,3,4,5)P4 comparable to that required for p42IP4 translocation. Thus, in vivo p42IP4 might interact with membranes in a ligand-controlled manner and be involved in physiological processes induced by the two second messengers Ins(1,3,4,5)P4 and PtdIns(3,4,5)P3.
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Affiliation(s)
- R Stricker
- Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Germany
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31
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Venkateswarlu K, Cullen PJ. Molecular cloning and functional characterization of a human homologue of centaurin-alpha. Biochem Biophys Res Commun 1999; 262:237-44. [PMID: 10448098 DOI: 10.1006/bbrc.1999.1065] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report here the molecular cloning, expression, and characterisation of a human homologue of rat centaurin-alpha, which we have termed centaurin-alpha(1). The cDNA contains a single open reading frame, which encodes a 373-amino-acid protein with a calculated molecular weight of 43,429 Daltons. Centaurin-alpha(1) shows high identity at the amino acid level with the other centaurin-alpha homologues, p42(IP4) and PIP(3)BP. Northern analysis revealed that centaurin-alpha(1) expresses as a single 2.5-kb transcript, mainly in the brain. Recombinant centaurin-alpha(1) binds the inositol head group of PtdIns(3,4,5)P(3) and Ins(1,3,4, 5)P(4), with high affinity (K(d) 139.7 +/- 10.5 nM) and inositol phosphate specificity, consistent with it functioning as a putative PtdIns(3,4,5)P(3) receptor. In keeping with this conclusion, we have shown that GFP-tagged centaurin-alpha(1) recruits to the plasma membrane in a PI 3-kinase-dependent manner and the recruitment is inhibited by the PI 3-kinase inhibitor wortmannin. These results suggest that centaurin-alpha(1) can function as an in vivo PtdIns(3, 4,5)P(3) receptor.
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Affiliation(s)
- K Venkateswarlu
- School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, United Kingdom
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32
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Adelt S, Plettenburg O, Stricker R, Reiser G, Altenbach HJ, Vogel G. Enzyme-assisted total synthesis of the optical antipodes D-myo-inositol 3,4,5-trisphosphate and D-myo-inositol 1,5, 6-trisphosphate: aspects of their structure-activity relationship to biologically active inositol phosphates. J Med Chem 1999; 42:1262-73. [PMID: 10197969 DOI: 10.1021/jm981113k] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Unambiguous total syntheses of both optical antipodes of the enantiomeric pair D-myo-inositol 3,4,5-trisphosphate (Ins(3,4,5)P3) and D-myo-inositol 1,5,6-trisphosphate (Ins(1,5,6)P3) are described. The ring system characteristic of myo-inositol was constructed de novo from p-benzoquinone. X-ray data for the enzymatically resolved (1S,2R,3R,4S)-1,4-diacetoxy-2,3-dibromocyclohex-5-ene enabled the unequivocal assignment of the absolute configuration. Subsequent transformations under stereocontrolled conditions led to enantiopure C2-symmetrical 1,4-(di-O-benzyldiphospho)conduritol B derivatives. Their synthetic potential was exploited to prepare Ins(3,4,5,6)P4 and Ins(1,4,5,6)P4 in three steps. With a recently identified and partially purified InsP5/InsP4 phosphohydrolase from Dictyostelium discoideum, these enantiomers could be converted to the target compounds, Ins(3,4,5)P3 and Ins(1,5,6)P3, on a preparative scale. An HPLC system employed for both purification of the inositol phosphates and analytical runs ensured that the products were isomerically homogeneous. The sensitivity of detection achieved by a complexometric postcolumn derivatization method indicates that the complexation properties of Ins(3,4,5)P3/Ins(1,5,6)P3 resemble those of Ins(1,2,3)P3, a compound with antioxidant potential. The set of inositol phosphates synthesized was used to clarify structural motifs important for molecular recognition by p42(IP4), a high-affinity Ins(1,3,4,5)P4/PtdIns(3,4,5)P3-specific binding protein from pig cerebellum.
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Affiliation(s)
- S Adelt
- Institute für Biochemie und Organische Chemie, Bergische Universität Wuppertal, Gaussstrasse 20, 42097 Wuppertal
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33
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Hanck T, Stricker R, Krishna UM, Falck JR, Chang YT, Chung SK, Reiser G. Recombinant p42IP4, a brain-specific 42-kDa high-affinity Ins(1,3,4,5)P4 receptor protein, specifically interacts with lipid membranes containing Ptd-Ins(3,4,5)P3. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 261:577-84. [PMID: 10215872 DOI: 10.1046/j.1432-1327.1999.00326.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have recently cloned the cDNA of p42IP4, a membrane-associated and cytosolic inositol (1,3,4,5)tetrakisphosphate receptor protein [Stricker, R., Hülser, E., Fischer, J., Jarchau, T., Walter, U., Lottspeich, F. & Reiser, G. (1997) FEBS Lett. 405, 229-236.] p42IP4 is a protein of 374 amino acids with Mr of 42 kDa. The p42IP4 protein has a zinc finger motif at its N-terminus, followed by two pleckstrin homology domains. To characterize further the biochemical and functional properties of p42IP4, it was expressed as a glutathione-S-transferase fusion protein in Sf9 cells using a recombinant baculovirus vector. The protein was affinity adsorbed on glutathione beads, cleaved from glutathione-S-transferase with the protease factor-Xa and purified on heparin agarose. The recombinant purified protein is active because it shows binding affinities similar to those of the native p42IP4, purified from pig cerebellum or rat brain (Ki for inositol(1,3,4,5)P4 of 4.1 nm and 2.2 nm, respectively). Moreover the ligand specificity of the recombinant protein for various inositol polyphosphates is similar to that of the native protein purified from brain. Importantly, we show here that p42IP4 binds phosphatidylinositol(3,4,5)P3 specifically, as the recombinant protein can associate with lipid membranes (vesicles) containing phosphatidylinositol(3,4,5)P3; this binding occurs in a concentration-dependent manner and is blocked by inositol(1,3,4,5)P4. This specific association and the possibility that endogenous p42IP4 can be converted from a membrane-associated state to a soluble state support the hypothesis that p42IP4 might be redistributed between cellular compartments upon hormonal stimulation.
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Affiliation(s)
- T Hanck
- Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Germany
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34
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Blader IJ, Cope MJ, Jackson TR, Profit AA, Greenwood AF, Drubin DG, Prestwich GD, Theibert AB. GCS1, an Arf guanosine triphosphatase-activating protein in Saccharomyces cerevisiae, is required for normal actin cytoskeletal organization in vivo and stimulates actin polymerization in vitro. Mol Biol Cell 1999; 10:581-96. [PMID: 10069805 PMCID: PMC25189 DOI: 10.1091/mbc.10.3.581] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Recent cloning of a rat brain phosphatidylinositol 3,4, 5-trisphosphate binding protein, centaurin alpha, identified a novel gene family based on homology to an amino-terminal zinc-binding domain. In Saccharomyces cerevisiae, the protein with the highest homology to centaurin alpha is Gcs1p, the product of the GCS1 gene. GCS1 was originally identified as a gene conditionally required for the reentry of cells into the cell cycle after stationary phase growth. Gcs1p was previously characterized as a guanosine triphosphatase-activating protein for the small guanosine triphosphatase Arf1, and gcs1 mutants displayed vesicle-trafficking defects. Here, we have shown that similar to centaurin alpha, recombinant Gcs1p bound phosphoinositide-based affinity resins with high affinity and specificity. A novel GCS1 disruption strain (gcs1Delta) exhibited morphological defects, as well as mislocalization of cortical actin patches. gcs1Delta was hypersensitive to the actin monomer-sequestering drug, latrunculin-B. Synthetic lethality was observed between null alleles of GCS1 and SLA2, the gene encoding a protein involved in stabilization of the actin cytoskeleton. In addition, synthetic growth defects were observed between null alleles of GCS1 and SAC6, the gene encoding the yeast fimbrin homologue. Recombinant Gcs1p bound to actin filaments, stimulated actin polymerization, and inhibited actin depolymerization in vitro. These data provide in vivo and in vitro evidence that Gcs1p interacts directly with the actin cytoskeleton in S. cerevisiae.
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Affiliation(s)
- I J Blader
- Departments of Neurobiology and Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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35
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Cullen PJ. Bridging the GAP in inositol 1,3,4,5-tetrakisphosphate signalling. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1436:35-47. [PMID: 9838034 DOI: 10.1016/s0005-2760(98)00149-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- P J Cullen
- Lister Institute Research Fellow, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
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36
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Aggensteiner M, Stricker R, Reiser G. Identification of rat brain p42(IP4), a high-affinity inositol(1,3,4, 5)tetrakisphosphate/phosphatidylinositol(3,4,5)trisphosphate binding protein. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1387:117-28. [PMID: 9748531 DOI: 10.1016/s0167-4838(98)00113-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inositol(1,3,4,5)tetrakisphosphate (InsP4) and phosphatidylinositol(3,4,5)trisphosphate (PtdInsP3) are two potential second messengers with a still largely unknown mode of action. We recently cloned the 42 kDa protein p42IP4 previously purified from pig cerebellum, which binds InsP4 (Kd approximately 2 nM) and PtdInsP3 with comparable affinities (Stricker et al., FEBS Lett. 405 (1997) 229). The protein p42IP4 (pig) is highly homologous to centaurin-alpha, a larger protein of 46 kDa, derived from a rat brain cDNA library clone (Hammonds-Odie et al., J. Biol. Chem. 271 (1996) 18859). Here we investigated whether also p42IP4 is expressed in rat brain and how it might be related to centaurin-alpha. When we carried out RT-PCR using mRNA from brain of rats of different ages we obtained several clones corresponding to p42IP4, but not to centaurin-alpha. The existence of p42IP4 in rat brain is supported by the following findings: (1) biochemical analysis of the purified rat brain protein shows inositol phosphate ligand affinities identical to those of the protein from other species; (2) Western blot analysis of rat brain membrane fractions using a peptide-specific antiserum revealed only the 42 kDa protein (p42IP4), but did not give evidence for the occurrence of a larger 46 kDa centaurin-alpha-like protein in rat brain; and (3) the amino acid sequences deduced from p42IP4 cDNA are highly homologous in several species and are confirmed by protein fragment microsequences. Thus, p42IP4 from rat brain which has two pleckstrin homology domains is a protein largely conserved between different species and most likely has an important function in inositol phosphate or inositol lipid signal transduction.
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Affiliation(s)
- M Aggensteiner
- Institut für Neurobiochemie der Otto-von Guericke-Universität Magdeburg, Medizinische Fakultät, Leipziger Str. 44, 39120 Magdeburg, Germany
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Shepherd PR, Withers DJ, Siddle K. Phosphoinositide 3-kinase: the key switch mechanism in insulin signalling. Biochem J 1998; 333 ( Pt 3):471-90. [PMID: 9677303 PMCID: PMC1219607 DOI: 10.1042/bj3330471] [Citation(s) in RCA: 727] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Insulin plays a key role in regulating a wide range of cellular processes. However, until recently little was known about the signalling pathways that are involved in linking the insulin receptor with downstream responses. It is now apparent that the activation of class 1a phosphoinositide 3-kinase (PI 3-kinase) is necessary and in some cases sufficient to elicit many of insulin's effects on glucose and lipid metabolism. The lipid products of PI 3-kinase act as both membrane anchors and allosteric regulators, serving to localize and activate downstream enzymes and their protein substrates. One of the major ways these lipid products of PI 3-kinase act in insulin signalling is by binding to pleckstrin homology (PH) domains of phosphoinositide-dependent protein kinase (PDK) and protein kinase B (PKB) and in the process regulating the phosphorylation of PKB by PDK. Using mechanisms such as this, PI 3-kinase is able to act as a molecular switch to regulate the activity of serine/threonine-specific kinase cascades important in mediating insulin's effects on endpoint responses.
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Affiliation(s)
- P R Shepherd
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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38
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Antonny B, Huber I, Paris S, Chabre M, Cassel D. Activation of ADP-ribosylation factor 1 GTPase-activating protein by phosphatidylcholine-derived diacylglycerols. J Biol Chem 1997; 272:30848-51. [PMID: 9388229 DOI: 10.1074/jbc.272.49.30848] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Disassembly of the coatomer from Golgi vesicles requires that the small GTP-binding protein ADP-ribosylation factor 1 (ARF1) hydrolyzes its bound GTP by the action of a GTPase-activating protein. In vitro, the binding of the ARF1 GTPase-activating protein to lipid vesicles and its activity on membrane-bound ARF1GTP are increased by diacylglycerols with monounsaturated acyl chains, such as those arising in vivo as secondary products from the hydrolysis of phosphatidylcholine by ARF-activated phospholipase D. Thus, the phospholipase D pathway may provide a feedback mechanism that promotes GTP hydrolysis on ARF1 and the consequent uncoating of vesicles.
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Affiliation(s)
- B Antonny
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France.
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39
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Kreutz MR, Böckers TM, Sabel BA, Hülser E, Stricker R, Reiser G. Expression and subcellular localization of p42IP4/centaurin-alpha, a brain-specific, high-affinity receptor for inositol 1,3,4,5-tetrakisphosphate and phosphatidylinositol 3,4,5-trisphosphate in rat brain. Eur J Neurosci 1997; 9:2110-24. [PMID: 9421171 DOI: 10.1111/j.1460-9568.1997.tb01378.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recently emerging evidence suggests important roles for inositol polyphosphates and inositol phospholipids in neuronal Ca2+ signalling, membrane vesicle trafficking and cytoskeletal rearrangement. A prerequisite for a detailed physiological characterization of the signalling of both potential second messengers inositol-(1,3,4,5)-tetrakisphosphate (InsP4) and phosphatidylinositol-3,4,5-trisphosphate (PtdInsP3) in the nervous system is the precise cellular localization of their receptors. Based on the cDNA sequence of a recently cloned brain-specific receptor with high affinity for both InsP4 and PtdInsP3 (InsP4-PtdInsP3R), p42IP4/centaurin-alpha, we localized the mRNA and the protein in rat brain. In situ hybridization revealed a widespread expression of the InsP4-PtdInsP3R with prominent labelling in cerebellum, hippocampus, cortex and thalamus, which moreover is developmentally regulated. Using peptide-specific antibodies, the immunoreactivity was localized in the adult brain in the vast majority of neuronal cell types and probably also in some glial cells. Prominent immunoreactivity was found in axonal processes and in cell types characterized by extensive neurites. In the hypothalamus a subpopulation of parvocellular neurons in the peri- and paraventricular nuclei was most heavily labelled. This was confined by strong immunoreactivity in the lamina externa of the median eminence in close proximity to portal plexus blood vessels. Electron microscopy revealed that the InsP4-PtdInsP3R was frequently associated with presynaptic vesicular structures. Further studies should identify the role of the InsP4-PtdInsP3R in cellular neural processes.
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Affiliation(s)
- M R Kreutz
- AG Molekulare und Zelluläre Neurobiologie, Institut für Medizinische Psychologie, Otto-von-Guericke Universität Magdeburg, Germany
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