1
|
Platholi J, Hemmings HC. Modulation of dendritic spines by protein phosphatase-1. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2020; 90:117-144. [PMID: 33706930 DOI: 10.1016/bs.apha.2020.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Protein phosphatase-1 (PP-1), a highly conserved multifunctional serine/threonine phosphatase, is enriched in dendritic spines where it plays a major role in modulating excitatory synaptic activity. In addition to established functions in spine maturation and development, multi-subunit holoenzyme forms of PP-1 modulate higher-order cognitive functions such learning and memory. Mechanisms involved in regulating PP-1 activity and localization in spines include interactions with neurabin and spinophilin, structurally related synaptic scaffolding proteins associated with the actin cytoskeleton. Since PP-1 is a critical element in synaptic development, signaling, and plasticity, alterations in PP-1 signaling in dendritic spines are implicated in various neurological and psychiatric disorders. The effects of PP-1 depend on its isoform-specific association with regulatory proteins and activation of downstream signaling pathways. Here we review the role of PP-1 and its binding proteins neurabin and spinophilin in both developing and established dendritic spines, as well as some of the disorders that result from its dysregulation.
Collapse
Affiliation(s)
- Jimcy Platholi
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, United States; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
| | - Hugh C Hemmings
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, United States; Department of Pharmacology, Weill Cornell Medicine, New York, NY, United States.
| |
Collapse
|
2
|
Allen JD, Bishop JR. A systematic review of genome-wide association studies of antipsychotic response. Pharmacogenomics 2019; 20:291-306. [PMID: 30883267 PMCID: PMC6563266 DOI: 10.2217/pgs-2018-0163] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/07/2019] [Indexed: 12/18/2022] Open
Abstract
Clinical symptom response to antipsychotic medications is highly variable. Genome-wide association studies (GWAS) provide a 'hypothesis-free' method of interrogating the genome for biomarkers of antipsychotic response. We performed a systematic review of GWAS findings for antipsychotic efficacy or effectiveness. 14 studies met our inclusion criteria, ten of which examined antipsychotic response using quantitative rating scales to measure symptom improvement. 15 genome-wide significant loci were identified, seven of which were replicated in other antipsychotic GWAS publications: CNTNAP5, GRID2, GRM7, 8q24 (KCNK9), PCDH7, SLC1A1 and TNIK. Notably, four replicated loci are involved in glutamatergic pathways. Additional validation and evaluation of the biological significance of these markers is warranted. These markers should also be evaluated for clinical utility, especially in the context of other validated pharmacogenomic variants (e.g., CYP450 genes). These findings may generate new avenues for development of novel antipsychotic treatments.
Collapse
Affiliation(s)
- Josiah D Allen
- Department of Experimental & Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
- Medigenics Consulting LLC, Minneapolis, MN 55407, USA
| | - Jeffrey R Bishop
- Department of Experimental & Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| |
Collapse
|
3
|
Cell-type specific increases in female hamster nucleus accumbens spine density following female sexual experience. Brain Struct Funct 2013; 219:2071-81. [PMID: 23934655 DOI: 10.1007/s00429-013-0624-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 08/02/2013] [Indexed: 01/01/2023]
Abstract
Female sexual behavior is an established model of a naturally motivated behavior which is regulated by activity within the mesolimbic dopamine system. Repeated activation of the mesolimbic circuit by female sexual behavior elevates dopamine release and produces persistent postsynaptic alterations to dopamine D1 receptor signaling within the nucleus accumbens. Here we demonstrate that sexual experience in female Syrian hamsters significantly increases spine density and alters morphology selectively in D1 receptor-expressing medium spiny neurons within the nucleus accumbens core, with no corresponding change in dopamine receptor binding or protein expression. Our findings demonstrate that previous life experience with a naturally motivated behavior has the capacity to induce persistent structural alterations to the mesolimbic circuit that can increase reproductive success and are analogous to the persistent structural changes following repeated exposure to many drugs of abuse.
Collapse
|
4
|
Muly E, Maddox M, Khan Z. Distribution of D1 and D5 dopamine receptors in the primate nucleus accumbens. Neuroscience 2010; 169:1557-66. [DOI: 10.1016/j.neuroscience.2010.06.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 06/10/2010] [Accepted: 06/12/2010] [Indexed: 10/19/2022]
|
5
|
Regulation of postsynaptic gephyrin cluster size by protein phosphatase 1. Mol Cell Neurosci 2010; 44:201-9. [PMID: 20206270 DOI: 10.1016/j.mcn.2010.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 02/22/2010] [Accepted: 02/23/2010] [Indexed: 01/21/2023] Open
Abstract
The scaffolding protein gephyrin is essential for the clustering of glycine and GABA(A) receptors (GABA(A)Rs) at inhibitory synapses. Here, we provide evidence that the size of the postsynaptic gephyrin scaffold is controlled by dephosphorylation reactions. Treatment of cultured hippocampal neurons with the protein phosphatase inhibitors calyculin A and okadaic acid reduced the size of postsynaptic gephyrin clusters and increased cytoplasmic gephyrin staining. Protein phosphatase 1 (PP1) was found to colocalize with gephyrin at selected postsynaptic sites and to interact with gephyrin in transfected cells and brain extracts. Alanine or glutamate substitution of the two established serine/threonine phosphorylation sites in gephyrin failed to affect its clustering at inhibitory synapses and its ability to recruit gamma2 subunit containing GABA(A)Rs. Our data are consistent with the postsynaptic gephyrin scaffold acting as a platform for PP1, which regulates gephyrin cluster size by dephosphorylation of gephyrin- or cytoskeleton-associated proteins.
Collapse
|
6
|
Glausier JR, Maddox M, Hemmings HC, Nairn AC, Greengard P, Muly EC. Localization of dopamine- and cAMP-regulated phosphoprotein-32 and inhibitor-1 in area 9 of Macaca mulatta prefrontal cortex. Neuroscience 2010; 167:428-38. [PMID: 20156529 DOI: 10.1016/j.neuroscience.2010.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 12/21/2009] [Accepted: 02/09/2010] [Indexed: 01/29/2023]
Abstract
The actions of dopamine D1 family receptors (D1R) depend upon a signal transduction cascade that modulates the phosphorylation state of important effector proteins, such as glutamate receptors and ion channels. This is accomplished both through activation of protein kinase A (PKA) and the inhibition of protein phosphatase-1 (PP1). Inhibition of PP1 occurs through PKA-mediated phosphorylation of dopamine- and cAMP-regulated phosphoprotein 32 kDa (DARPP-32) or the related protein inhibitor-1 (I-1), and the availability of DARPP-32 is essential to the functional outcome of D1R activation in the basal ganglia. While D1R activation is critical for prefrontal cortex (PFC) function, especially working memory, the functional role played by DARPP-32 or I-1 is less clear. In order to examine this more thoroughly, we have utilized immunoelectron microscopy to quantitatively determine the localization of DARPP-32 and I-1 in the neuropil of the rhesus monkey PFC. Both were distributed widely in the different components of the neuropil, but were enriched in dendritic shafts. I-1 label was more frequently identified in axon terminals than was DARPP-32, and DARPP-32 label was more frequently identified in glia than was I-1. We also quantified the extent to which these proteins were found in dendritic spines. DARPP-32 and I-1 were present in small subpopulations of dendritic spines, (4.4% and 7.7% and respectively), which were substantially smaller than observed for D1R in our previous studies (20%). Double-label experiments did not find evidence for colocalization of D1R and DARPP-32 or I-1 in spines or terminals. Thus, at the least, not all prefrontal spines which contain D1R also contain I-1 or DARPP-32, suggesting important differences in D1R signaling in the PFC compared to the striatum.
Collapse
Affiliation(s)
- J R Glausier
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA 30329, USA
| | | | | | | | | | | |
Collapse
|
7
|
Muly EC, Senyuz M, Khan ZU, Guo JD, Hazra R, Rainnie DG. Distribution of D1 and D5 dopamine receptors in the primate and rat basolateral amygdala. Brain Struct Funct 2009; 213:375-93. [PMID: 19669160 DOI: 10.1007/s00429-009-0214-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 07/23/2009] [Indexed: 01/12/2023]
Abstract
Dopamine, acting at the D1 family receptors (D1R) is critical for the functioning of the amygdala, including fear conditioning and cue-induced reinstatement of drug self administration. However, little is known about the different contributions of the two D1R subtypes, D(1) and D(5). We identified D(1)-immunoreactive patches in the primate that appear similar to the intercalated cell masses reported in the rodent; however, both receptors were present across the subdivisions of the primate amygdala including the basolateral amygdala (BLA). Using immunoelectron microscopy, we established that both receptors have widespread distributions in BLA. The D1R subtypes colocalize in dendritic spines and terminals, with D(1) predominant in spines and D(5) in terminals. Single-cell RT-PCR confirmed that individual BLA projection neurons express both D(1) and D(5) mRNA. The responses of primate BLA neurons to dopamine and D1R drugs were studied using in vitro slices. We found that responses were similar to those previously reported in rat BLA neurons and included a mixture of postsynaptic and presynaptic actions. We investigated the distribution of D1R in the rat BLA and found that there were similarities between the species, such as more prominent D(5) localization to presynaptic structures. The higher affinity of D(5) for dopamine suggests that presynaptic actions may predominate in the BLA at low levels of dopamine, while postsynaptic effects increase and dominate as dopaminergic drive increases. The results presented here suggest a complex action of dopamine on BLA circuitry that may evolve with different degrees of dopaminergic stimulation.
Collapse
Affiliation(s)
- E Chris Muly
- Atlanta Department of Veterans Affairs Medical Center, Decatur, GA, USA.
| | | | | | | | | | | |
Collapse
|
8
|
Glausier JR, Khan ZU, Muly EC. Dopamine D1 and D5 receptors are localized to discrete populations of interneurons in primate prefrontal cortex. Cereb Cortex 2008; 19:1820-34. [PMID: 19020206 DOI: 10.1093/cercor/bhn212] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Working memory (WM) is a core cognitive process that depends upon activation of D1 family receptors (D1R) and inhibitory interneurons in the prefrontal cortex (PFC). D1R are comprised of the D(1) and D(5) subtypes, and D(5) has a 10-fold higher affinity for dopamine. Parvalbumin (PV) and calretinin (CR) are 2 interneuron populations that are differentially affected by D1R stimulation and have discrete postsynaptic targets, such that PV interneurons provide strong inhibition to pyramidal cells, whereas CR interneurons inhibit other interneurons. The distinct properties of both the D1R and interneuron subtypes may contribute to the "inverted-U" relationship of D1R stimulation and WM ability. To determine the prevalence of D(1) and D(5) in PV and CR interneurons, we performed quantitative double-label immunoelectron microscopy in layer III of macaque area 9. We found that D(1) was the predominant D1R subtype in PV interneurons and was found mainly in dendrites. In contrast, D(5) was the predominant D1R subtype in CR interneurons and was found mainly in dendrites. Integrating these findings with previously published electrophysiological data, we propose a circuitry model as a framework for understanding the inverted-U relationship between dopamine stimulation of D1R and WM performance.
Collapse
Affiliation(s)
- Jill R Glausier
- Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, GA 30329, USA
| | | | | |
Collapse
|
9
|
Bordelon-Glausier JR, Khan ZU, Muly EC. Quantification of D1 and D5 dopamine receptor localization in layers I, III, and V of Macaca mulatta prefrontal cortical area 9: coexpression in dendritic spines and axon terminals. J Comp Neurol 2008; 508:893-905. [PMID: 18399540 DOI: 10.1002/cne.21710] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
D1 family receptors (D1R) in prefrontal cortex (PFC) are critical for normal cognition and are implicated in pathological states such as schizophrenia. The two D1R subtypes, D1 and D5, cannot be pharmacologically distinguished but have important functional differences. To understand their contributions to cortical function, we quantified their localization in the neuropil of primate PFC. We identified different patterns of distribution for the two receptors that showed variation across cortical laminae. Although D1 was enriched in spines and D5 in dendrites, there was considerable overlap in their distribution within neuronal compartments. To determine whether the D1 and D5 receptors are localized to separate populations of synapses, we employed double-labeling methods. We found the two receptors colocalized and quantified the overlap of their distribution in spines and axon terminals of prefrontal cortical area 9 in the Macaca mulatta monkey. The two receptors are found in partially overlapping populations, such that the D5 receptor is found in a subpopulation of those spines and terminals that contain D1. These results indicate that dopamine activation of the two D1R subtypes does not modulate disparate populations of synapses onto dendritic spines in prefrontal cortical area 9; rather, dopamine can activate D1 and D5 receptors on the same spines, plus an additional group of spines that contains only D1. The implications of these results for the dose-dependent relationship between D1R activation and PFC function are discussed.
Collapse
|
10
|
|
11
|
Mansuy IM, Shenolikar S. Protein serine/threonine phosphatases in neuronal plasticity and disorders of learning and memory. Trends Neurosci 2006; 29:679-86. [PMID: 17084465 DOI: 10.1016/j.tins.2006.10.004] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 07/28/2006] [Accepted: 10/19/2006] [Indexed: 01/12/2023]
Abstract
Phosphorylation and dephosphorylation of cellular proteins by protein kinases and phosphatases represent important mechanisms for controlling major biological events. In the nervous system, protein phosphatases are contained in highly dynamic complexes localized within specialized subcellular compartments and they ensure timely dephosphorylation of multiple neuronal phosphoproteins. This modulates the responsiveness of individual synapses to neural activity and controls synaptic plasticity. These enzymes in turn play a key role in many forms of learning and memory, and their dysfunction contributes to cognitive deficits associated with aging and dementias or neurodegenerative diseases. Here, we review key modes of regulation of neuronal protein serine/threonine phosphatases and their contribution to disorders of learning and memory.
Collapse
Affiliation(s)
- Isabelle M Mansuy
- Brain Research Institute, Medical Faculty of the University Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
| | | |
Collapse
|
12
|
Bordelon JR, Smith Y, Nairn AC, Colbran RJ, Greengard P, Muly EC. Differential localization of protein phosphatase-1alpha, beta and gamma1 isoforms in primate prefrontal cortex. ACTA ACUST UNITED AC 2005; 15:1928-37. [PMID: 15758197 PMCID: PMC2586106 DOI: 10.1093/cercor/bhi070] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Prefrontal cortical functioning depends on D1 family receptors and their complex signal transduction cascade, including protein phosphatase-1 (PP1). Three PP1 isoforms are prominent in the brain: PP1alpha, PP1beta and PP1gamma1. PP1 localization by a variety of scaffolding proteins is critical for dopamine-mediated modulation of glutamatergic neurotransmission. We have quantified the subcellular distribution of each isoform in primate prefrontal cortex using immunoelectron microscopy. All three are found in spines, dendrites, axon terminals, axons and glia. However, PP1alpha and PP1gamma1 labeling is enriched in spines, whereas PP1beta label is enriched in dendrites. Using post-embedding immunogold labeling, we further examined the distribution of PP1alpha and PP1gamma1 within spines. PP1gamma1 is highly and specifically concentrated in the postsynaptic density (PSD) of these spines, while PP1alpha is enriched in the PSD but also found subjacent to the PSD in moderate amounts. Thus, PP1 isoforms are heterogeneously distributed in the cortical neuropil and within spines. These results suggest that each PP1 isoform has access to a different set of substrates and, furthermore, they demonstrate that the composition of signal transduction proteins varies in different parts of the neuron and even in different regions of a dendritic spine in the primate PFC.
Collapse
Affiliation(s)
- Jill R. Bordelon
- Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, GA, USA
| | - Yoland Smith
- Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, GA, USA
- Department of Neurology, Emory University, Atlanta, GA, USA
| | - Angus C. Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, 1230 York Ave, New York, NY, USA
| | - Roger J. Colbran
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, 1230 York Ave, New York, NY, USA
| | - E. Chris Muly
- Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA, USA
| |
Collapse
|
13
|
Gong JP, Liu QR, Zhang PW, Wang Y, Uhl GR. Mouse brain localization of the protein kinase C-enhanced phosphatase 1 inhibitor KEPI (Kinase C-Enhanced PP1 Inhibitor). Neuroscience 2005; 132:713-27. [PMID: 15837133 DOI: 10.1016/j.neuroscience.2004.11.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2004] [Indexed: 10/25/2022]
Abstract
We recently identified the protein kinase C-enhanced protein phosphatase 1 (PP1) inhibitor KEPI based on its morphine-induced upregulation in striatum. Regulation of protein serine/threonine dephosphorylation by PP1 can modulate important brain signaling pathways. To improve understanding of KEPI's role in the brain, we have developed anti-KEPI sera in rabbits immunized with a hemocyanin conjugate of KEPI residues 66-80, characterized the specificity that this serum provides, mapped the distribution of immunoreactive KEPI (iKEPI) in mouse brain, rat dorsal root ganglia and striatal cultures and documented KEPI binding to PP1 in vitro. Staining is found in apparently neuronal processes and, often less intensely, in neuronal perikarya in primary cultures and in neurons and neuronal elements from a number of brain regions. iKEPI fiber/terminal patterns are relatively densely distributed in striatum, nucleus accumbens, septum, bed nucleus of the stria terminalis, hippocampus, paraventricular thalamus, ventromedial hypothalamus, interpeduncular nucleus, raphe nuclei, nucleus caudalis of the spinal tract of the trigeminal and dorsal horn of the spinal cord. iKEPI-positive cell bodies lie in the nucleus accumbens, striatum, lateral septal nucleus, granular layer of dentate gyrus, interpeduncular nucleus, dorsal root ganglia and cerebellar vermis. These expression patterns point to possible roles for KEPI in regulating protein dephosphorylation by inhibiting PP1 activities in a number of brain pathways likely to use several different neurotransmitters and to participate in a number of brain functions. Dense KEPI immunoreactivity in nucleus accumbens perikarya, combined with evidence for its regulation by opiates, supports possible roles for KEPI in molecular signal transduction pathways important for drug reward and addiction.
Collapse
Affiliation(s)
- J-P Gong
- Molecular Neurobiology, NIDA-IRP, NIH, DHHS, 333 Cassell Drive, Baltimore, MD 21224, USA
| | | | | | | | | |
Collapse
|
14
|
|
15
|
Liu QR, Gong JP, Uhl GR. Families of Protein Phosphatase 1 Modulators Activated by Protein Kinases A and C: Focus on Brain. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2005; 79:371-404. [PMID: 16096033 DOI: 10.1016/s0079-6603(04)79008-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Qing-Rong Liu
- Molecular Neurobiology Branch, NIDA-IRP, National Institute of Health, Baltimore, Maryland 21224, USA
| | | | | |
Collapse
|
16
|
Lontay B, Serfozo Z, Gergely P, Ito M, Hartshorne DJ, Erdodi F. Localization of myosin phosphatase target subunit 1 in rat brain and in primary cultures of neuronal cells. J Comp Neurol 2004; 478:72-87. [PMID: 15334650 DOI: 10.1002/cne.20273] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Myosin phosphatase (PP1M) is composed of the delta isoform of the PP1 catalytic subunit (PP1cdelta), the myosin phosphatase target subunit (MYPT), and a 20 kDa subunit. Western blots detected higher amounts of the MYPT1 isoform compared to MYPT2 in whole brain extracts. The localization of MYPT1 was studied in rat brain and in primary cell cultures of neurons using specific antibodies. Analysis of lysates of brain regions for MYPT1 and PP1M by Western blots using anti-MYPT1 antibodies and by phosphatase assays with myosin as substrate suggested a ubiquitous distribution. Immunohistochemistry of tissue sections revealed that MYPT1 was distributed in all areas of the brain, with staining observed in many different cell types. Depending on the method used for fixation, the MYPT1 appeared with varying intensity in nuclei, in nucleoli, and in the cytoplasm. In primary hippocampal cultures, MYPT1 was identified by confocal microscopy in the cytoplasm and in the nucleus, whereas a predominantly cytoplasmic localization was found in cochlear nucleus cells. In cultured cells, MYPT1 and PP1cdelta colocalized with synaptophysin. PP1M activity was high in synaptosomes isolated from the cerebral cortex, but was relatively low in the postsynaptic densities. The interaction of MYPT1 with synaptophysin and with known partners (Rho-kinase, PP1cdelta) in brain extracts was shown by immunoprecipitation with anti-MYPT1. Pull-down assays from synaptosomes, using GST-MYPT1, also confirmed these interactions. In conclusion, the widespread cellular and subcellular localization of MYPT1 implies that PP1M may play an important role in the dephosphorylation of key regulatory proteins in neuronal cells.
Collapse
Affiliation(s)
- Beáta Lontay
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, H-4012 Debrecen, Bem tér 18/B, Hungary
| | | | | | | | | | | |
Collapse
|
17
|
Allen PB, Greenfield AT, Svenningsson P, Haspeslagh DC, Greengard P. Phactrs 1-4: A family of protein phosphatase 1 and actin regulatory proteins. Proc Natl Acad Sci U S A 2004; 101:7187-92. [PMID: 15107502 PMCID: PMC406487 DOI: 10.1073/pnas.0401673101] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Protein phosphatase 1 (PP1) is a multifunctional enzyme with diverse roles in the nervous system, including regulation of synaptic activity and dendritic morphology. PP1 activity is controlled via association with a family of regulatory subunits that govern subcellular localization and substrate specificity. A previously undescribed class of PP1-binding proteins was detected by interaction cloning. Family members were also found to bind to cytoplasmic actin via Arg, Pro, Glu, and Leu repeat-containing sequences. The prototypical member of this family, phosphatase and actin regulator (phactr) 1 was a potent modulator of PP1 activity in vitro. Phactr-1 protein is selectively expressed in brain, where high levels were found in cortex, hippocampus, and striatum, with enrichment of the protein at synapses. Additional family members displayed highly distinct mRNA transcript expression patterns within rat brain. The current findings present a mechanism by which PP1 may be directed toward neuronal substrates associated with the actin cytoskeleton.
Collapse
Affiliation(s)
- Patrick B Allen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06508, USA.
| | | | | | | | | |
Collapse
|
18
|
Muly EC, Smith Y, Allen P, Greengard P. Subcellular distribution of spinophilin immunolabeling in primate prefrontal cortex: localization to and within dendritic spines. J Comp Neurol 2004; 469:185-97. [PMID: 14694533 DOI: 10.1002/cne.11001] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Signal transduction in the nervous system depends on kinases and phosphatases, whose localization is regulated by a large group of scaffolding proteins. In particular, protein phosphatase-1 mediates dopamine's actions on a variety of substrates, including glutamate receptors, and this, in turn, depends on the binding of protein phosphatase-1 to its binding protein spinophilin. To better understand spinophilin's role in targeting protein phosphatase-1 within neurons, we used a combination of preembedding immunoperoxidase and postembedding immunogold labeling and electron microscopy to determine the localization of this scaffolding protein in macaque prefrontal cortex. Consistent with previous reports, spinophilin was found predominantly in dendritic spines, but a significant number of labeled dendritic shafts and, less frequently, glia and preterminal axons were also identified. By using the postembedding immunogold method, we further examined the distribution of spinophilin within dendritic spines. Spinophilin immunoreactivity was present throughout the spine, but the density of label was heterogeneous and defined two domains. The highest density of label was associated with the postsynaptic density and the 100 nm immediately subjacent to it. The deeper region of the spine, further than 100 nm from the postsynaptic density, had a lower density of spinophilin label. The distribution of spinophilin reported in this study supports its role in modulating glutamatergic neurotransmission but also suggests the possibility that spinophilin may target protein phosphatase-1 to other sites within the spine or to other neuronal or glial compartments.
Collapse
Affiliation(s)
- E Chris Muly
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia 30329, USA.
| | | | | | | |
Collapse
|
19
|
Muly EC, Maddox M, Smith Y. Distribution of mGluR1? and mGluR5 immunolabeling in primate prefrontal cortex. J Comp Neurol 2003; 467:521-35. [PMID: 14624486 DOI: 10.1002/cne.10937] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) mediate important modulatory glutamatergic influences throughout the brain. However, the specific localization and functions of group I mGluR subtypes (mGluR1alpha and mGluR5) in cortical neurotransmission are not well known, particularly in primates. To address this issue, we used immunoelectron microscopy to compare the subcellular localizations of mGluR1alpha and mGluR5 in the prefrontal cortex of macaque monkeys. Both receptor subtypes were found in a variety of subcellular compartments, including spines, dendrites, preterminal axons, axon terminals, and glia; however, quantitative differences were found in the relative abundance of labeled elements for each receptor. The mGluR1alpha-immunoreactive (-IR) elements were overwhelmingly the spines and dendrites, with labeled terminals, axons, and glia seen more rarely. The mGluR5-IR elements were also mostly spines and dendrites, but the proportion of labeled unmyelinated axons, terminals, and glia was higher than for mGluR1alpha-IR elements. Double labeling with SMI-32 and parvalbumin confirmed that both receptors were found in pyramidal cell and interneuron dendrites. The localization of mGluR1alpha to pyramidal cells in primate cortex contrasts with reports that mGluR1alpha is found almost exclusively in interneurons in rodent cortex. By using double labeling, we found no evidence for mGluR1alpha or mGluR5 in dopaminergic afferents to prefrontal cortex. The data presented here provide an anatomical substrate for a differential role of mGluR1alpha and mGluR5 in post-and presynaptic actions of glutamate in primate prefrontal cortex. They further suggest differences in the cortical distribution of group I mGluRs between primates and rodents.
Collapse
Affiliation(s)
- E Chris Muly
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia 30329, USA.
| | | | | |
Collapse
|
20
|
Terry-Lorenzo RT, Carmody LC, Voltz JW, Connor JH, Li S, Smith FD, Milgram SL, Colbran RJ, Shenolikar S. The neuronal actin-binding proteins, neurabin I and neurabin II, recruit specific isoforms of protein phosphatase-1 catalytic subunits. J Biol Chem 2002; 277:27716-24. [PMID: 12016225 DOI: 10.1074/jbc.m203365200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurabins are protein phosphatase-1 (PP1) targeting subunits that are highly concentrated in dendritic spines and post-synaptic densities. Immunoprecipitation of neurabin I and neurabin II/spinophilin from rat brain extracts sedimented PP1gamma1 and PP1alpha but not PP1beta. In vitro studies showed that recombinant peptides representing central regions of neurabins also preferentially bound PP1gamma1 and PP1alpha from brain extracts and associated poorly with PP1beta. Analysis of PP1 binding to chimeric neurabins suggested that sequences flanking a conserved PP1-binding motif altered their selectivity for PP1beta and their activity as regulators of PP1 in vitro. Assays using recombinant PP1 catalytic subunits and a chimera of PP1 and protein phosphatase-2A indicated that the C-terminal sequences unique to the PP1 isoforms contributed to their recognition by neurabins. Collectively, the results from several different in vitro assays established the rank order of PP1 isoform selection by neurabins to be PP1gamma1 > PP1alpha > PP1beta. This PP1 isoform selectivity was confirmed by immunoprecipitation of neurabin I and II from brain extracts from wild type and mutant PP1gamma null mice. In the absence of PP1gamma1, both neurabins showed enhanced association with PP1alpha but not PP1beta. These studies identified some of the structural determinants in PP1 and neurabins that together contribute to preferential targeting of PP1gamma1 and PP1alpha to the mammalian synapse.
Collapse
Affiliation(s)
- Ryan T Terry-Lorenzo
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | | | | | | | | | | | | | | |
Collapse
|