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Iijima K, Ando K, Takeda S, Satoh Y, Seki T, Itohara S, Greengard P, Kirino Y, Nairn AC, Suzuki T. Neuron-specific phosphorylation of Alzheimer's beta-amyloid precursor protein by cyclin-dependent kinase 5. J Neurochem 2000; 75:1085-91. [PMID: 10936190 DOI: 10.1046/j.1471-4159.2000.0751085.x] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mature form of Alzheimer's beta-amyloid precursor protein (APP) is phosphorylated specifically at Thr(668) in neurons. In mature neurons, phosphorylated APP is detected in neurites, with dephosphorylated APP being found mostly in the cell body. In vitro, active cyclin-dependent kinase 5 (Cdk5) phosphorylated the cytoplasmic domain of APP at Thr(668). Treatment of mature neurons with an antisense oligonucleotide to Cdk5 suppressed Cdk5 expression and significantly diminished the level of phosphorylated APP. The expression of APP was unaffected in antisense-treated neurons. These results indicate that in neurons APP is phosphorylated by Cdk5, and that this may play a role in its localization.
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52
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Huang HB, Chen YC, Tsai LH, Wang H, Lin FM, Horiuchi A, Greengard P, Nairn AC, Shiao MS, Lin TH. Backbone 1H, 15N, and 13C resonance assignments of inhibitor-2 -- a protein inhibitor of protein phosphatase-1. JOURNAL OF BIOMOLECULAR NMR 2000; 17:359-360. [PMID: 11014604 DOI: 10.1023/a:1008355428294] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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53
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Feng J, Yan Z, Ferreira A, Tomizawa K, Liauw JA, Zhuo M, Allen PB, Ouimet CC, Greengard P. Spinophilin regulates the formation and function of dendritic spines. Proc Natl Acad Sci U S A 2000; 97:9287-92. [PMID: 10922077 PMCID: PMC16860 DOI: 10.1073/pnas.97.16.9287] [Citation(s) in RCA: 302] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spinophilin, a protein that interacts with actin and protein phosphatase-1, is highly enriched in dendritic spines. Here, through the use of spinophilin knockout mice, we provide evidence that spinophilin modulates both glutamatergic synaptic transmission and dendritic morphology. The ability of protein phosphatase-1 to regulate the activity of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors was reduced in spinophilin knockout mice. Consistent with altered glutamatergic transmission, spinophilin-deficient mice showed reduced long-term depression and exhibited resistance to kainate-induced seizures and neuronal apoptosis. In addition, deletion of the spinophilin gene caused a marked increase in spine density during development in vivo as well as altered filopodial formation in cultured neurons. In conclusion, spinophilin appears to be required for the regulation of the properties of dendritic spines.
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Caporaso GL, Bibb JA, Snyder GL, Valle C, Rakhilin S, Fienberg AA, Hemmings HC, Nairn AC, Greengard P. Drugs of abuse modulate the phosphorylation of ARPP-21, a cyclic AMP-regulated phosphoprotein enriched in the basal ganglia. Neuropharmacology 2000; 39:1637-44. [PMID: 10854908 DOI: 10.1016/s0028-3908(99)00230-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ARPP-21 is a cyclic AMP-regulated phosphoprotein of M(r) 21 kDa that is enriched in the cell bodies and terminals of medium-sized spiny neurons in the basal ganglia. Using a new phosphorylation state-specific antibody selective for the detection of ARPP-21 phosphorylated on Ser(55), we have demonstrated that activation of dopamine D1 receptors increased the level of ARPP-21 phosphorylation in mouse striatal slices. Conversely, activation of D2 receptors caused a large decrease in ARPP-21 phosphorylation. Treatment of mice with either methamphetamine or cocaine resulted in increased ARPP-21 phosphorylation in vivo. Studies using specific inhibitors of protein phosphatases and experiments in mice bearing a targeted deletion of the gene for DARPP-32, a dopamine-activated inhibitor of protein phosphatase-1, indicated that protein phosphatase-2A is primarily responsible for dephosphorylation of ARPP-21 in mouse striatum. These results demonstrate that phosphorylation and dephosphorylation of ARPP-21 are tightly regulated in the striatum. We speculate that ARPP-21 might mediate some of the physiologic effects of dopamine and certain drugs of abuse in the basal ganglia.
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Svenningsson P, Fienberg AA, Allen PB, Moine CL, Lindskog M, Fisone G, Greengard P, Fredholm BB. Dopamine D(1) receptor-induced gene transcription is modulated by DARPP-32. J Neurochem 2000; 75:248-57. [PMID: 10854268 DOI: 10.1046/j.1471-4159.2000.0750248.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of the dopamine- and cyclic AMP-regulated phosphoprotein of M(r) 32,000 (DARPP-32) in dopaminergic regulation of gene transcription in striatum and globus pallidus was examined. Mice with targeted disruption of the gene encoding DARPP-32, its homologue, inhibitor-1, or both, were used. Pharmacological characterization showed that mutant mice had normal basal levels of dopamine D(1) and D(2) receptors and adenosine A(2A) receptors. Basal expression levels of the striatonigral-specific neuropeptides substance P and prodynorphin and the immediate early genes c-fos and NGFI-A were also unaltered in mutant mice. A full D(1) receptor agonist, SKF 82958, up-regulated the expression of these neuropeptides and immediate early genes significantly more in wild-type mice than in mice lacking DARPP-32. Moreover, the additive stimulation of SKF 82958 and quinelorane, a D(2) receptor agonist, on c-fos mRNA in globus pallidus was significantly decreased in DARPP-32 and DARPP-32/I-1 knockout mice. No changes in dopamine receptor-induced gene expression were found in I-1 knockout mice. These results demonstrate an important involvement of DARPP-32 in dopamine receptor-mediated regulation of gene expression both in striatal neurons, which are enriched in DARPP-32, and in pallidal neurons, which do not contain DARPP-32.
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56
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Snyder GL, Allen PB, Fienberg AA, Valle CG, Huganir RL, Nairn AC, Greengard P. Regulation of phosphorylation of the GluR1 AMPA receptor in the neostriatum by dopamine and psychostimulants in vivo. J Neurosci 2000; 20:4480-8. [PMID: 10844017 PMCID: PMC6772453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
The activation of cAMP-dependent protein kinase regulates the physiological activity of AMPA-type glutamate receptors. In this study, phosphorylation of the AMPA receptor subunit GluR1 at Ser(845) was increased in neostriatal slices by activation of D1-type dopamine receptors and by inhibitors of protein phosphatase 1/protein phosphatase 2A. In contrast, Ser(831), a residue which, when phosphorylated by protein kinase C or calcium/calmodulin-dependent kinase II, increases AMPA receptor channel conductance, was unaffected by either D1 or D2 receptor agonists in neostriatal slices. The phosphorylation of Ser(845), but not Ser(831), was strongly increased in neostriatum in vivo in response to the psychostimulants cocaine and methamphetamine. The effects of dopamine and psychostimulants on the phosphorylation of GluR1 were attenuated in dopamine and cAMP-regulated phosphoprotein M(r) 32 kDa (DARPP-32) knock-out mice. These results identify DARPP-32 and AMPA-type glutamate receptors as likely essential cellular effectors for psychostimulant actions.
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Heyser CJ, Fienberg AA, Greengard P, Gold LH. DARPP-32 knockout mice exhibit impaired reversal learning in a discriminated operant task. Brain Res 2000; 867:122-30. [PMID: 10837805 DOI: 10.1016/s0006-8993(00)02272-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The current study was conducted to examine the performance of mice with a targeted deletion of the gene for DARPP-32 in a discriminated operant task using food reinforcement. DARPP-32 plays a central role in regulating the efficacy of dopaminergic neurotransmission. Initially, wild-type and DARPP-32 knockout mice were trained to nose-poke for food on a continuous reinforcement schedule. The minimum response requirement was increased every 5 days until the animals were responding on an FR-15 schedule of reinforcement. At the completion of extensive operant training, reversal learning was assessed. Wild-type and DARPP-32 knockout mice exhibited equivalent performance during acquisition of this task, with both groups increasing operant responding as the schedule of reinforcement was raised. However, significant differences in discrimination learning were observed during the reversal phase, with DARPP-32 knockout mice requiring significantly more trials to reach criterion than wild-type controls. These results provide evidence for a functional role of DARPP-32 in the mediation of processes underlying learning and memory.
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Bibb JA, Yan Z, Svenningsson P, Snyder GL, Pieribone VA, Horiuchi A, Nairn AC, Messer A, Greengard P. Severe deficiencies in dopamine signaling in presymptomatic Huntington's disease mice. Proc Natl Acad Sci U S A 2000; 97:6809-14. [PMID: 10829080 PMCID: PMC18747 DOI: 10.1073/pnas.120166397] [Citation(s) in RCA: 231] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Huntington's disease (HD), mutation of huntingtin causes selective neurodegeneration of dopaminoceptive striatal medium spiny neurons. Transgenic HD model mice that express a portion of the disease-causing form of human huntingtin develop a behavioral phenotype that suggests dysfunction of dopaminergic neurotransmission. Here we show that presymtomatic mice have severe deficiencies in dopamine signaling in the striatum. These include selective reductions in total levels of dopamine- and cAMP-regulated phosphoprotein, M(r) 32 kDA (DARPP-32) and other dopamine-regulated phosphoprotein markers of medium spiny neurons. HD mice also show defects in dopamine-regulated ion channels and in the D(1) dopamine/DARPP-32 signaling cascade. These presymptomatic defects may contribute to HD pathology.
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Allen PB, Hvalby O, Jensen V, Errington ML, Ramsay M, Chaudhry FA, Bliss TV, Storm-Mathisen J, Morris RG, Andersen P, Greengard P. Protein phosphatase-1 regulation in the induction of long-term potentiation: heterogeneous molecular mechanisms. J Neurosci 2000; 20:3537-43. [PMID: 10804194 PMCID: PMC6772695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Protein phosphatase inhibitor-1 (I-1) has been proposed as a regulatory element in the signal transduction cascade that couples postsynaptic calcium influx to long-term changes in synaptic strength. We have evaluated this model using mice lacking I-1. Recordings made in slices prepared from mutant animals and also in anesthetized mutant animals indicated that long-term potentiation (LTP) is deficient at perforant path-dentate granule cell synapses. In vitro, this deficit was restricted to synapses of the lateral perforant path. LTP at Schaffer collateral-CA1 pyramidal cell synapses remained normal. Thus, protein phosphatase-1-mediated regulation of NMDA receptor-dependent synaptic plasticity involves heterogeneous molecular mechanisms, in both different dendritic subregions and different neuronal subtypes. Examination of the performance of I-1 mutants in spatial learning tests indicated that intact LTP at lateral perforant path-granule cell synapses is either redundant or is not involved in this form of learning.
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Ferreira A, Kao HT, Feng J, Rapoport M, Greengard P. Synapsin III: developmental expression, subcellular localization, and role in axon formation. J Neurosci 2000; 20:3736-44. [PMID: 10804215 PMCID: PMC6772681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
We have investigated the developmental expression and subcellular localization of synapsin III, the newest member of the synapsin family, in cultured mouse hippocampal neurons. Our results indicate that synapsin III is expressed early during development, with levels peaking 7 d after plating and declining thereafter. Synapsin III is highly concentrated in growth cones. Using specific antisense oligonucleotides, we have also examined the effect of depleting synapsin III on neurite elongation and synaptogenesis. When synapsin III was suppressed immediately after plating, hippocampal neurons extended minor processes but failed to differentiate one of them as the axon. The suppression of synapsin III after axonal elongation did not affect the time course of synapse formation. The results indicate that synapsin III has a developmental time course, a subcellular localization, and a developmental function very different from those of synapsin I and synapsin II.
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61
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Flores-Hernandez J, Hernandez S, Snyder GL, Yan Z, Fienberg AA, Moss SJ, Greengard P, Surmeier DJ. D(1) dopamine receptor activation reduces GABA(A) receptor currents in neostriatal neurons through a PKA/DARPP-32/PP1 signaling cascade. J Neurophysiol 2000; 83:2996-3004. [PMID: 10805695 DOI: 10.1152/jn.2000.83.5.2996] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dopamine is a critical determinant of neostriatal function, but its impact on intrastriatal GABAergic signaling is poorly understood. The role of D(1) dopamine receptors in the regulation of postsynaptic GABA(A) receptors was characterized using whole cell voltage-clamp recordings in acutely isolated, rat neostriatal medium spiny neurons. Exogenous application of GABA evoked a rapidly desensitizing current that was blocked by bicuculline. Application of the D(1) dopamine receptor agonist SKF 81297 reduced GABA-evoked currents in most medium spiny neurons. The D(1) dopamine receptor antagonist SCH 23390 blocked the effect of SKF 81297. Membrane-permeant cAMP analogues mimicked the effect of D(1) dopamine receptor stimulation, whereas an inhibitor of protein kinase A (PKA; Rp-8-chloroadenosine 3',5' cyclic monophosphothioate) attenuated the response to D(1) dopamine receptor stimulation or cAMP analogues. Inhibitors of protein phosphatase 1/2A potentiated the modulation by cAMP analogues. Single-cell RT-PCR profiling revealed consistent expression of mRNA for the beta1 subunit of the GABA(A) receptor-a known substrate of PKA-in medium spiny neurons. Immunoprecipitation assays of radiolabeled proteins revealed that D(1) dopamine receptor stimulation increased phosphorylation of GABA(A) receptor beta1/beta3 subunits. The D(1) dopamine receptor-induced phosphorylation of beta1/beta3 subunits was attenuated significantly in neostriata from DARPP-32 mutants. Voltage-clamp recordings corroborated these results, revealing that the efficacy of the D(1) dopamine receptor modulation of GABA(A) currents was reduced in DARPP-32-deficient medium spiny neurons. These results argue that D(1) dopamine receptor stimulation in neostriatal medium spiny neurons reduces postsynaptic GABA(A) receptor currents by activating a PKA/DARPP-32/protein phosphatase 1 signaling cascade targeting GABA(A) receptor beta1 subunits.
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62
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Walaas SI, Hilfiker S, Li L, Chin LS, Greengard P. Decrease in phorbol ester-induced potentiation of noradrenaline release in synapsin I-deficient mice. Synapse 2000; 36:114-9. [PMID: 10767058 DOI: 10.1002/(sici)1098-2396(200005)36:2<114::aid-syn4>3.0.co;2-q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Synapsin I is involved in regulating amino acid neurotransmitter release, but has a less clear role in noradrenergic nerve terminals. To better understand the role of synapsin I in the function of noradrenergic nerve terminals, we compared noradrenaline release in wild-type and synapsin I-deficient mice. No difference was found in the accumulation or in the Ca(2+)-independent release of [(3)H]noradrenaline in cerebrocortical synaptosomes from wild-type and synapsin I-deficient mice. Synaptosomes lacking synapsin I also displayed no gross alterations in either the time course or the Ca(2+)-dependency of [(3)H]noradrenaline release when stimulated by depolarizing secretagogues or ionophore treatment. In wild-type synaptosomes, activation of protein kinase C by phorbol ester treatment resulted in a Ca(2+)-dependent increase in [(3)H]noradrenaline release evoked by depolarizing secretagogues and ionophore treatment. The phorbol ester-mediated enhancement of [(3)H]noradrenaline release evoked by depolarizing secretagogues, but not by ionophore treatment, was greatly reduced in synapsin I-deficient synaptosomes. These results indicate that synapsin I plays a role in regulating noradrenaline release.
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63
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Jovanovic JN, Czernik AJ, Fienberg AA, Greengard P, Sihra TS. Synapsins as mediators of BDNF-enhanced neurotransmitter release. Nat Neurosci 2000; 3:323-9. [PMID: 10725920 DOI: 10.1038/73888] [Citation(s) in RCA: 438] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We examined enhancement of synaptic transmission by neurotrophins at the presynaptic level. In a synaptosomal preparation, brain-derived neurotrophic factor (BDNF) increased mitogen-activated protein (MAP) kinase-dependent synapsin I phosphorylation and acutely facilitated evoked glutamate release. PD98059, used to inhibit MAP kinase activity, markedly decreased synapsin I phosphorylation and concomitantly reduced neurotransmitter release. The stimulation of glutamate release by BDNF was strongly attenuated in mice lacking synapsin I and/or synapsin II. These results indicate a causal link of synapsin phosphorylation via BDNF, TrkB receptors and MAP kinase with downstream facilitation of neurotransmitter release.
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Näslund J, Haroutunian V, Mohs R, Davis KL, Davies P, Greengard P, Buxbaum JD. Correlation between elevated levels of amyloid beta-peptide in the brain and cognitive decline. JAMA 2000; 283:1571-7. [PMID: 10735393 DOI: 10.1001/jama.283.12.1571] [Citation(s) in RCA: 890] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Alzheimer disease (AD) is characterized neuropathologically by the presence of amyloid beta-peptide (Abeta)-containing plaques and neurofibrillary tangles composed of abnormal tau protein. Considerable controversy exists as to whether the extent of accumulation of Abeta correlates with dementia and whether Abeta alterations precede or follow changes in tau. OBJECTIVES To determine whether accumulation of Abeta correlates with the earliest signs of cognitive deterioration and to define the relationship between Abeta accumulation and early tau changes. DESIGN, SETTING, AND PATIENTS Postmortem cross-sectional study of 79 nursing home residents with Clinical Dementia Rating (CDR) scale scores of 0.0 to 5.0 who died between 1986 and 1997, comparing the levels of Abeta variants in the cortices of the subjects with no (CDR score, 0.0 [n = 16]), questionable (CDR score, 0.5 [n = 11]), mild (CDR score, 1.0 [n = 22]), moderate (CDR score, 2.0 [n = 15]), or severe (CDR score, 4.0 or 5.0 [n = 15]) dementia. MAIN OUTCOME MEASURES Levels of total Abeta peptides with intact or truncated amino termini and ending in either amino acid 40 (A(beta)x-40) or 42 (A(beta)x-42) in 5 neocortical brain regions as well as levels of tau protein undergoing early conformational changes in frontal cortex, as a function of CDR score. RESULTS The levels of both A(beta)x-40 and A(beta)x-42 were elevated even in cases classified as having questionable dementia (CDR score = 0.5), and increases of both peptides correlated with progression of dementia. Levels of the more fibril-prone A(beta)x-42 peptide were higher than those of A(beta)x-40 in nondemented cases and remained higher throughout progression of disease in all regions examined. Finally, increases in A(beta)x-40 and A(beta)x-42 precede significant tau pathology at least in the frontal cortex, an area chosen for examination because of the absence of neuritic changes in the absence of disease. CONCLUSIONS In this study, levels of total A(beta)x-40 and A(beta)x-42 were elevated early in dementia and levels of both peptides were strongly correlated with cognitive decline. Of particular interest, in the frontal cortex, Abeta was elevated before the occurrence of significant tau pathology. These results support an important role for Abeta in mediating initial pathogenic events in AD dementia and suggest that treatment strategies targeting the formation, accumulation, or cytotoxic effects of Abeta should be pursued.
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65
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Aizman O, Brismar H, Uhlén P, Zettergren E, Levey AI, Forssberg H, Greengard P, Aperia A. Anatomical and physiological evidence for D1 and D2 dopamine receptor colocalization in neostriatal neurons. Nat Neurosci 2000; 3:226-30. [PMID: 10700253 DOI: 10.1038/72929] [Citation(s) in RCA: 323] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Despite the importance of dopamine signaling, it remains unknown if the two major subclasses of dopamine receptors exist on the same or distinct populations of neurons. Here we used confocal microscopy to demonstrate that virtually all striatal neurons, both in vitro and in vivo, contained dopamine receptors of both classes. We also provide functional evidence for such colocalization: in essentially all neurons examined, fenoldopam, an agonist of the D1 subclass of receptors, inhibited both the Na+/K+ pump and tetrodotoxin (TTX)-sensitive sodium channels, and quinpirole, an agonist of the D2 subclass of receptors, activated TTX-sensitive sodium channels. Thus D1 and D2 classes of ligands may functionally interact in virtually all dopamine-responsive neurons within the basal ganglia.
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67
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Svenningsson P, Lindskog M, Ledent C, Parmentier M, Greengard P, Fredholm BB, Fisone G. Regulation of the phosphorylation of the dopamine- and cAMP-regulated phosphoprotein of 32 kDa in vivo by dopamine D1, dopamine D2, and adenosine A2A receptors. Proc Natl Acad Sci U S A 2000; 97:1856-60. [PMID: 10677546 PMCID: PMC26526 DOI: 10.1073/pnas.97.4.1856] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dopamine D(1), dopamine D(2), and adenosine A(2A) receptors are highly expressed in striatal medium-sized spiny neurons. We have examined, in vivo, the influence of these receptors on the state of phosphorylation of the dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32). DARPP-32 is a potent endogenous inhibitor of protein phosphatase-1, which plays an obligatory role in dopaminergic transmission. A dose-dependent increase in the state of phosphorylation of DARPP-32 occurred in mouse striatum after systemic administration of the D(2) receptor antagonist eticlopride (0.1-2.0 mg/kg). This effect was abolished in mice in which the gene coding for the adenosine A(2A) receptor was disrupted by homologous recombination. A reduction was also observed in mice that had been pretreated with the selective A(2A) receptor antagonist SCH 58261 (10 mg/kg). The eticlopride-induced increase in DARPP-32 phosphorylation was also decreased by pretreatment with the D(1) receptor antagonist SCH 23390 (0.125 and 0.25 mg/kg) and completely reversed by combined pretreatment with SCH 23390 (0.25 mg/kg) plus SCH 58261 (10 mg/kg). SCH 23390, but not SCH 58261, abolished the increase in DARPP-32 caused by cocaine (15 mg/kg). The results indicate that, in vivo, the state of phosphorylation of DARPP-32 and, by implication, the activity of protein phosphatase-1 are regulated by tonic activation of D(1), D(2), and A(2A) receptors. The results also underscore the fact that the adenosine system plays a role in the generation of responses to dopamine D(2) antagonists in vivo.
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68
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Mani SK, Fienberg AA, O'Callaghan JP, Snyder GL, Allen PB, Dash PK, Moore AN, Mitchell AJ, Bibb J, Greengard P, O'Malley BW. Requirement for DARPP-32 in progesterone-facilitated sexual receptivity in female rats and mice. Science 2000; 287:1053-6. [PMID: 10669419 DOI: 10.1126/science.287.5455.1053] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
DARPP-32, a dopamine- and adenosine 3',5'-monophosphate (cAMP)-regulated phosphoprotein (32 kilodaltons in size), is an obligate intermediate in progesterone (P)-facilitated sexual receptivity in female rats and mice. The facilitative effect of P on sexual receptivity in female rats was blocked by antisense oligonucleotides to DARPP-32. Homozygous mice carrying a null mutation for the DARPP-32 gene exhibited minimal levels of P-facilitated sexual receptivity when compared to their wild-type littermates. P significantly increased hypothalamic cAMP levels and cAMP-dependent protein kinase activity. These increases were not inhibited by a D1 subclass dopamine receptor antagonist. P also enhanced phosphorylation of DARPP-32 on threonine 34 in the hypothalamus of mice. DARPP-32 activation is thus an obligatory step in progestin receptor regulation of sexual receptivity in rats and mice.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Dopamine/pharmacology
- Dopamine Agonists/pharmacology
- Dopamine and cAMP-Regulated Phosphoprotein 32
- Female
- Hypothalamus/metabolism
- Injections, Intraventricular
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nerve Tissue Proteins
- Oligonucleotides, Antisense/pharmacology
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Phosphorylation
- Posture
- Progesterone/pharmacology
- Proteins/genetics
- Proteins/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Progesterone/metabolism
- Serotonin/pharmacology
- Sexual Behavior, Animal/drug effects
- Signal Transduction
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69
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Gouras GK, Xu H, Gross RS, Greenfield JP, Hai B, Wang R, Greengard P. Testosterone reduces neuronal secretion of Alzheimer's beta-amyloid peptides. Proc Natl Acad Sci U S A 2000; 97:1202-5. [PMID: 10655508 PMCID: PMC15568 DOI: 10.1073/pnas.97.3.1202] [Citation(s) in RCA: 220] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by the age-related deposition of beta-amyloid (Abeta) 40/42 peptide aggregates in vulnerable brain regions. Multiple levels of evidence implicate a central role for Abeta in the pathophysiology of AD. Abeta peptides are generated by the regulated cleavage of an approximately 700-aa Abeta precursor protein (betaAPP). Full-length betaAPP can undergo proteolytic cleavage either within the Abeta domain to generate secreted sbetaAPPalpha or at the N- and C-terminal domain(s) of Abeta to generate amyloidogenic Abeta peptides. Several epidemiological studies have reported that estrogen replacement therapy protects against the development of AD in postmenopausal women. We previously reported that treating cultured neurons with 17beta-estradiol reduced the secretion of Abeta40/42 peptides, suggesting that estrogen replacement therapy may protect women against the development of AD by regulating betaAPP metabolism. Increasing evidence indicates that testosterone, especially bioavailable testosterone, decreases with age in older men and in postmenopausal women. We report here that treatment with testosterone increases the secretion of the nonamyloidogenic APP fragment, sbetaAPPalpha, and decreases the secretion of Abeta peptides from N2a cells and rat primary cerebrocortical neurons. These results raise the possibility that testosterone supplementation in elderly men may be protective in the treatment of AD.
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Kao HT, Porton B, Hilfiker S, Stefani G, Pieribone VA, DeSalle R, Greengard P. Molecular evolution of the synapsin gene family. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1999; 285:360-77. [PMID: 10578110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Synapsins, a family of synaptic vesicle proteins, play a crucial role in the regulation of neurotransmission and synaptogenesis. They have been identified in a variety of invertebrate and vertebrate species, including human, rat (Rattus norvegicus), cow (Bos taurus), longfin squid (Loligo pealei), and fruit fly (Drosophila melanogaster). Here, synapsins were cloned from three additional species: frog (Xenopus laevis), lamprey (Lampetra fluviatilis), and nematode (Caenorhabditis elegans). Synapsin protein sequences from all these species were then used to explore the molecular phylogeny of these important neuronal phosphoproteins. The ancestral condition of a single synapsin gene probably gave rise to the vertebrate synapsin gene family comprised of at least three synapsin genes (I, II, and III) in higher vertebrates. Synapsins possess multiple domains, which have evolved at different rates throughout evolution. In invertebrate synapsins, the most conserved domains are C and E. During the evolution of vertebrates, at least two gene duplication events are hypothesized to have given rise to the synapsin gene family. This was accompanied by the emergence of an additional conserved domain, termed A. J. Exp. Zool. ( Mol. Dev. Evol. ) 285:360-377, 1999.
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Bibb JA, Snyder GL, Nishi A, Yan Z, Meijer L, Fienberg AA, Tsai LH, Kwon YT, Girault JA, Czernik AJ, Huganir RL, Hemmings HC, Nairn AC, Greengard P. Phosphorylation of DARPP-32 by Cdk5 modulates dopamine signalling in neurons. Nature 1999; 402:669-71. [PMID: 10604473 DOI: 10.1038/45251] [Citation(s) in RCA: 467] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The physiological state of the cell is controlled by signal transduction mechanisms which regulate the balance between protein kinase and protein phosphatase activities. Here we report that a single protein can, depending on which particular amino-acid residue is phosphorylated, function either as a kinase or phosphatase inhibitor. DARPP-32 (dopamine and cyclic AMP-regulated phospho-protein, relative molecular mass 32,000) is converted into an inhibitor of protein phosphatase 1 when it is phosphorylated by protein kinase A (PKA) at threonine 34. We find that DARPP-32 is converted into an inhibitor of PKA when phosphorylated at threonine 75 by cyclin-dependent kinase 5 (Cdk5). Cdk5 phosphorylates DARPP-32 in vitro and in intact brain cells. Phospho-Thr 75 DARPP-32 inhibits PKA in vitro by a competitive mechanism. Decreasing phospho-Thr 75 DARPP-32 in striatal slices, either by a Cdk5-specific inhibitor or by using genetically altered mice, results in increased dopamine-induced phosphorylation of PKA substrates and augmented peak voltage-gated calcium currents. Thus DARPP-32 is a bifunctional signal transduction molecule which, by distinct mechanisms, controls a serine/threonine kinase and a serine/threonine phosphatase.
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Heierhorst J, Mitchelhill KI, Mann RJ, Tiganis T, Czernik AJ, Greengard P, Kemp BE. Synapsins as major neuronal Ca2+/S100A1-interacting proteins. Biochem J 1999; 344 Pt 2:577-83. [PMID: 10567243 PMCID: PMC1220678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
The mammalian S100A1 protein can activate the invertebrate myosin-associated giant protein kinase twitchin in a Ca(2+)-dependent manner by more than 1000-fold in vitro; however, no mammalian S100-dependent protein kinases are known. In an attempt to identify novel mammalian Ca(2+)/S100A1-regulated protein kinases, brain extracts were subjected to combined Ca(2+)-dependent affinity chromatography with S100A1 and an ATP analogue. This resulted in the purification to near-homogeneity of the four major synapsin isoforms Ia, Ib, IIa and IIb. All four synapsins were specifically affinity-labelled with the ATP analogue 5'-p-fluorosulphonylbenzoyladenosine. S100A1 bound to immobilized synapsin IIa in BIAcore experiments in a Ca(2+)-dependent and Zn(2+)-enhanced manner with submicromolar affinity; this interaction could be competed for with synthetic peptides of the proposed S100A1-binding sites of synapsin. Double-labelling confocal immunofluorescence microscopy demonstrated that synapsins and S100A1 are both present in the soma and neurites of PC12 cells, indicating their potential to interact in neurons in vivo.
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Abstract
Synapsin III, the most recently described member of the synapsin gene family, displays a gene structure and protein domain structure similar to those of synapsins I and II. In this report, however, we describe major differences in the temporal- and tissue-specific expressions of synapsin III. Whereas synapsins I and II each give rise to two isoforms that are expressed predominantly in adult brain, there are at least six synapsin III transcripts (synapsin IIIa-IIIf) that differ with respect to tissue- and developmental stage-specific expression. Three of the neuronal transcripts are detected in fetal and to a lesser extent in adult brain (IIa-IIIc), whereas one (IIId) is detected only in fetal brain. Two additional transcripts (IIIe and IIIf) are detected only in nonneuronal tissues. A putative second promoter, which is contained within an intron in the synapsin III gene locus, appears to generate the nonneuronal synapsin IIIe and IIIf transcripts. This level of genome complexity is far greater than that described previously for the synapsin I and II genes and suggests that synapsin III may have functions distinct from those described for synapsins I and II.
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Greenfield JP, Xu H, Greengard P, Gandy S, Seeger M. Generation of the amyloid-beta peptide N terminus in Saccharomyces cerevisiae expressing human Alzheimer's amyloid-beta precursor protein. J Biol Chem 1999; 274:33843-6. [PMID: 10567340 DOI: 10.1074/jbc.274.48.33843] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Alzheimer's amyloid-beta precursor protein (betaAPP) is a type 1 membrane-spanning protein from which the Alzheimer's disease amyloid-beta peptide (Abeta) is proteolytically derived. To date, attempts to identify the enzymes responsible for Abeta generation have failed. Here we report the accumulation of Abeta-immunoreactive peptides in yeast expressing human betaAPP. Characterization of these peptides by metabolic labeling, immunoprecipitation with Abeta-specific antibodies, and N-terminal radiosequencing indicates that these peptides include the Abeta peptide at their N termini. The Abeta-like peptides generated in yeast were recovered predominantly as 8- and 12-14-kDa species. A 4-kDa species was recovered either when a protease-deficient strain was used to prevent breakdown or when the 8- and 12-14-kDa species were treated with disaggregating agents. The likely existence in yeast of enzymes generating the Abeta N terminus indicates that the molecular identification of yeast beta-secretase-like enzymes may be accomplished using genetic screens or empirical approaches based upon the sequenced genome of Saccharomyces cerevisiae.
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Porton B, Kao HT, Greengard P. Cloning of cDNAs encoding human synapsins IIa and IIb. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1999; 10:49-54. [PMID: 10565545 DOI: 10.3109/10425179909033936] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The synapsins are a family of neuronal phosphoproteins that are specifically associated with the cytoplasmic surface of synaptic vesicles. In mammals, distinct genes for synapsins I, II, and III give rise to members of the synapsin family. The synapsins are implicated in neurotransmitter release and synaptogenesis, processes believed to be aberrant in several neuropsychiatric diseases. The characterization of human synapsins is therefore important for evaluating the possible role of synapsins in human neuropathology. In this report, we describe the cloning and sequence of human synapsins IIa and IIb, products of the synapsin II gene. Human synapsins IIa and IIb conform to the previously described domain model of the synapsins, and the most conserved protein domains are A, C, and E.
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