1
|
Bekdash RA. The Cholinergic System, the Adrenergic System and the Neuropathology of Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms22031273. [PMID: 33525357 PMCID: PMC7865740 DOI: 10.3390/ijms22031273] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/23/2021] [Accepted: 01/25/2021] [Indexed: 12/16/2022] Open
Abstract
Neurodegenerative diseases are a major public health problem worldwide with a wide spectrum of symptoms and physiological effects. It has been long reported that the dysregulation of the cholinergic system and the adrenergic system are linked to the etiology of Alzheimer’s disease. Cholinergic neurons are widely distributed in brain regions that play a role in cognitive functions and normal cholinergic signaling related to learning and memory is dependent on acetylcholine. The Locus Coeruleus norepinephrine (LC-NE) is the main noradrenergic nucleus that projects and supplies norepinephrine to different brain regions. Norepinephrine has been shown to be neuroprotective against neurodegeneration and plays a role in behavior and cognition. Cholinergic and adrenergic signaling are dysregulated in Alzheimer’s disease. The degeneration of cholinergic neurons in nucleus basalis of Meynert in the basal forebrain and the degeneration of LC-NE neurons were reported in Alzheimer’s disease. The aim of this review is to describe current literature on the role of the cholinergic system and the adrenergic system (LC-NE) in the pathology of Alzheimer’s disease and potential therapeutic implications.
Collapse
Affiliation(s)
- Rola A Bekdash
- Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA
| |
Collapse
|
2
|
Complex noradrenergic dysfunction in Alzheimer's disease: Low norepinephrine input is not always to blame. Brain Res 2019; 1702:12-16. [PMID: 29307592 PMCID: PMC6855395 DOI: 10.1016/j.brainres.2018.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 11/13/2017] [Accepted: 01/02/2018] [Indexed: 11/24/2022]
Abstract
The locus coeruleus-noradrenergic (LC-NA) system supplies the cerebral cortex with norepinephrine, a key modulator of cognition. Neurodegeneration of the LC is an early hallmark of Alzheimer's disease (AD). In this article, we analyze current literature to understand whether NA degeneration in AD simply leads to a loss of norepinephrine input to the cortex. With reported adaptive changes in the LC-NA system at the anatomical, cellular, and molecular levels in AD, existing evidence support a seemingly sustained level of extracellular NE in the cortex, at least at early stages of the long course of AD. We postulate that loss of the integrity of the NA system, rather than mere loss of NE input, is a key contributor to AD pathogenesis. A thorough understanding of NA dysfunction in AD has a large impact on both our comprehension and treatment of this devastating disease.
Collapse
|
3
|
Copenhaver PF, Kögel D. Role of APP Interactions with Heterotrimeric G Proteins: Physiological Functions and Pathological Consequences. Front Mol Neurosci 2017; 10:3. [PMID: 28197070 PMCID: PMC5281615 DOI: 10.3389/fnmol.2017.00003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/05/2017] [Indexed: 12/27/2022] Open
Abstract
Following the discovery that the amyloid precursor protein (APP) is the source of β-amyloid peptides (Aβ) that accumulate in Alzheimer’s disease (AD), structural analyses suggested that the holoprotein resembles a transmembrane receptor. Initial studies using reconstituted membranes demonstrated that APP can directly interact with the heterotrimeric G protein Gαo (but not other G proteins) via an evolutionarily G protein-binding motif in its cytoplasmic domain. Subsequent investigations in cell culture showed that antibodies against the extracellular domain of APP could stimulate Gαo activity, presumably mimicking endogenous APP ligands. In addition, chronically activating wild type APP or overexpressing mutant APP isoforms linked with familial AD could provoke Go-dependent neurotoxic responses, while biochemical assays using human brain samples suggested that the endogenous APP-Go interactions are perturbed in AD patients. More recently, several G protein-dependent pathways have been implicated in the physiological roles of APP, coupled with evidence that APP interacts both physically and functionally with Gαo in a variety of contexts. Work in insect models has demonstrated that the APP ortholog APPL directly interacts with Gαo in motile neurons, whereby APPL-Gαo signaling regulates the response of migratory neurons to ligands encountered in the developing nervous system. Concurrent studies using cultured mammalian neurons and organotypic hippocampal slice preparations have shown that APP signaling transduces the neuroprotective effects of soluble sAPPα fragments via modulation of the PI3K/Akt pathway, providing a mechanism for integrating the stress and survival responses regulated by APP. Notably, this effect was also inhibited by pertussis toxin, indicating an essential role for Gαo/i proteins. Unexpectedly, C-terminal fragments (CTFs) derived from APP have also been found to interact with Gαs, whereby CTF-Gαs signaling can promote neurite outgrowth via adenylyl cyclase/PKA-dependent pathways. These reports offer the intriguing perspective that G protein switching might modulate APP-dependent responses in a context-dependent manner. In this review, we provide an up-to-date perspective on the model that APP plays a variety of roles as an atypical G protein-coupled receptor in both the developing and adult nervous system, and we discuss the hypothesis that disruption of these normal functions might contribute to the progressive neuropathologies that typify AD.
Collapse
Affiliation(s)
- Philip F Copenhaver
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Sciences University, Portland OR, USA
| | - Donat Kögel
- Experimental Neurosurgery, Goethe University Frankfurt Frankfurt am Main, Germany
| |
Collapse
|
4
|
Simpson JE, Ince PG, Shaw PJ, Heath PR, Raman R, Garwood CJ, Gelsthorpe C, Baxter L, Forster G, Matthews FE, Brayne C, Wharton SB. Microarray analysis of the astrocyte transcriptome in the aging brain: relationship to Alzheimer's pathology and APOE genotype. Neurobiol Aging 2011; 32:1795-807. [PMID: 21705112 DOI: 10.1016/j.neurobiolaging.2011.04.013] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 03/21/2011] [Accepted: 04/20/2011] [Indexed: 12/31/2022]
Abstract
Astrocytes contribute to a variety of functions in the brain, including homeostasis, synapse formation, plasticity, and metabolism. Astrocyte dysfunction may disrupt their normal role, including neuronal support, thereby contributing to neurodegenerative pathologies, including Alzheimer's disease (AD). To understand the role of astrocytes in the pathogenesis of age-related disorders, we isolated astrocytes by laser capture microdissection, using glial fibrillary acidic protein (GFAP) as a marker, and characterized the astrocyte transcriptome at different Braak neurofibrillary tangle stages in postmortem temporal cortex samples derived from the Medical Research Council Cognitive Function and Ageing Study (MRC CFAS) cohort, using microarray analysis. The largest number of significant, differentially expressed genes were identified when the expression profile of astrocytes from isocortical stages of neurofibrillary tangle pathology (Braak stages V-VI) were compared with entorhinal stages (Braak stages I-II). Dysregulation of genes associated with the actin cytoskeleton, proliferation, apoptosis, and ubiquitin-mediated proteolysis occurred at low Braak stages, while altered regulation of intracellular signaling pathways, including insulin, phosphatidylinositol 3-kinase (PI3K)/Akt, and mitogen-activated protein kinase (MAPK) pathways were primarily associated with high levels of Alzheimer-type pathology, and occurred at lower Braak stages in individuals with the APOEε4 allele. Our findings implicate astrocyte dysfunction in the pathogenesis of neurodegenerative pathology in the aging brain, and provide a basis for future candidate studies based on specific pathways.
Collapse
Affiliation(s)
- Julie E Simpson
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Wang D, Xiang YK. β-adrenergic receptor, amyloid β-peptide, and Alzheimer's disease. CURRENT TOPICS IN MEMBRANES 2011; 67:205-28. [PMID: 21771492 DOI: 10.1016/b978-0-12-384921-2.00010-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Dayong Wang
- Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | | |
Collapse
|
6
|
Abstract
Tau is an abundant microtubule-associated protein which regulates the stability of the cytoskeleton. Tau binds microtubules directly through microtubule-binding domains in its C-terminus. However, tau is not only located in the cytosol of cells, but also associated with other intracellular domains, including the plasma membrane, suggesting that tau may have additional functions other than stabilizing the neuronal cytoskeleton. Localization of tau at the cell surface appears to be dependent on interactions of the N-terminal projection domain of tau. Furthermore, membrane-associated tau is dephosphorylated at serine/threonine residues, suggesting that the phosphorylation state of tau regulates its intracellular trafficking. Dephosphorylation of tau may increase the association of tau with trafficking proteins which target tau to the plasma membrane. Thus it is possible that the hyperphosphoryation of tau may contribute to the pathogenesis of Alzheimer's disease by promoting the formation of neurofibrillary tangles from cytosolic tau, and also by inhibiting additional tau functions through disruption of its targeting to the plasma membrane.
Collapse
|
7
|
Romanitan MO, Popescu BO, Spulber S, Băjenaru O, Popescu LM, Winblad B, Bogdanovic N. Altered expression of claudin family proteins in Alzheimer's disease and vascular dementia brains. J Cell Mol Med 2010; 14:1088-100. [PMID: 20041969 PMCID: PMC3822746 DOI: 10.1111/j.1582-4934.2009.00999.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Claudins (Cls) are a multigene family of transmembrane proteins with different tissue distribution, which have an essential role in the formation and sealing capacity of tight junctions (TJs). At the level of the blood–brain barrier (BBB), TJs are the main molecular structures which separate the neuronal milieu from the circulatory space, by a restriction of the paracellular flow of water, ions and larger molecules into the brain. Different studies suggested recently significant BBB alterations in both vascular and degenerative dementia types. In a previous study we found in Alzheimer’s disease (AD) and vascular dementia (VaD) brains an altered expression of occludin, a molecular partner of Cls in the TJs structure. Therefore in this study, using an immunohistochemical approach, we investigated the expression of Cl family proteins (Cl-2, Cl-5 and Cl-11) in frontal cortex of aged control, AD and VaD brains. To estimate the number of Cl-expressing cells, we applied a random systematic sampling and the unbiased optical fractionator method. We found selected neurons, astrocytes, oligodendrocytes and endothelial cells expressing Cl-2, Cl-5 and Cl-11 at detectable levels in all cases studied. We report a significant increase in ratio of neurons expressing Cl-2, Cl-5 and Cl-11 in both AD and VaD as compared to aged controls. The ratio of astrocytes expressing Cl-2 and Cl-11 was significantly higher in AD and VaD as compared to aged controls. The ratio of oligodendrocytes expressing Cl-11 was significantly higher in AD and the ratio of oligodendrocytes expressing Cl-2 was significantly higher in VaD as compared to aged controls. Within the cerebral cortex, Cls were selectively expressed by pyramidal neurons, which are the ones responsible for cognitive processes and affected by AD pathology. Our findings suggest a new function of Cl family proteins which might be linked to response to cellular stress.
Collapse
Affiliation(s)
- Mihaela O Romanitan
- Laboratory of Molecular Medicine, 'Victor Babeş' National Institute of Pathology, Spl Independenţei, Bucharest, Romania
| | | | | | | | | | | | | |
Collapse
|
8
|
Mitochondrial mislocalization underlies Abeta42-induced neuronal dysfunction in a Drosophila model of Alzheimer's disease. PLoS One 2009; 4:e8310. [PMID: 20016833 PMCID: PMC2790372 DOI: 10.1371/journal.pone.0008310] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 11/21/2009] [Indexed: 11/19/2022] Open
Abstract
The amyloid-beta 42 (Abeta42) is thought to play a central role in the pathogenesis of Alzheimer's disease (AD). However, the molecular mechanisms by which Abeta42 induces neuronal dysfunction and degeneration remain elusive. Mitochondrial dysfunctions are implicated in AD brains. Whether mitochondrial dysfunctions are merely a consequence of AD pathology, or are early seminal events in AD pathogenesis remains to be determined. Here, we show that Abeta42 induces mitochondrial mislocalization, which contributes to Abeta42-induced neuronal dysfunction in a transgenic Drosophila model. In the Abeta42 fly brain, mitochondria were reduced in axons and dendrites, and accumulated in the somata without severe mitochondrial damage or neurodegeneration. In contrast, organization of microtubule or global axonal transport was not significantly altered at this stage. Abeta42-induced behavioral defects were exacerbated by genetic reductions in mitochondrial transport, and were modulated by cAMP levels and PKA activity. Levels of putative PKA substrate phosphoproteins were reduced in the Abeta42 fly brains. Importantly, perturbations in mitochondrial transport in neurons were sufficient to disrupt PKA signaling and induce late-onset behavioral deficits, suggesting a mechanism whereby mitochondrial mislocalization contributes to Abeta42-induced neuronal dysfunction. These results demonstrate that mislocalization of mitochondria underlies the pathogenic effects of Abeta42 in vivo.
Collapse
|
9
|
Olive Oils Modulate Fatty Acid Content and Signaling Protein Expression in Apolipoprotein E Knockout Mice Brain. Lipids 2009; 45:53-61. [DOI: 10.1007/s11745-009-3370-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 10/19/2009] [Indexed: 02/02/2023]
|
10
|
Shaked GM, Chauv S, Ubhi K, Hansen LA, Masliah E. Interactions between the amyloid precursor protein C-terminal domain and G proteins mediate calcium dysregulation and amyloid beta toxicity in Alzheimer's disease. FEBS J 2009; 276:2736-51. [PMID: 19368557 DOI: 10.1111/j.1742-4658.2009.06997.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease is characterized by neuropathological accumulations of amyloid beta(1-42) [A beta(1-42)], a cleavage product of the amyloid precursor protein (APP). Recent studies have highlighted the role of APP in A beta-mediated toxicity and have implicated the G-protein system; however, the exact mechanisms underlying this pathway are as yet undetermined. In this context, we sought to investigate the role of calcium upregulation following APP-dependent, A beta-mediated G-protein activation. Initial studies on the interaction between APP, A beta and Go proteins demonstrated that the interaction between APP, specifically its C-terminal -YENPTY- region, and Go was reduced in the presence of A beta. Cell death and calcium influx in A beta-treated cells were shown to be APP dependent and to involve G-protein activation because these effects were blocked by use of the G-protein inhibitor, pertussis toxin. Collectively, these results highlight a role for the G-protein system in APP-dependent, A beta-induced toxicity and calcium dysregulation. Analysis of the APP:Go interaction in human brain samples from Alzheimer's disease patients at different stages of the disease revealed a decrease in the interaction, correlating with disease progression. Moreover, the reduced interaction between APP and Go was shown to correlate with an increase in membrane A beta levels and G-protein activity, showing for first time that the APP:Go interaction is present in humans and is responsive to A beta load. The results presented support a role for APP in A beta-induced G-protein activation and suggest a mechanism by which basal APP binding to Go is reduced under pathological loads of A beta, liberating Go and activating the G-protein system, which may in turn result in downstream effects including calcium dysregulation. These results also suggest that specific antagonists of G-protein activity may have a therapeutic relevance in Alzheimer's disease.
Collapse
Affiliation(s)
- Gideon M Shaked
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093-0624, USA
| | | | | | | | | |
Collapse
|
11
|
Jefremov V, Rakitin A, Mahlapuu R, Zilmer K, Bogdanovic N, Zilmer M, Karelson E. 17beta-Oestradiol stimulation of G-proteins in aged and Alzheimer's human brain: comparison with phytoestrogens. J Neuroendocrinol 2008; 20:587-96. [PMID: 18363809 DOI: 10.1111/j.1365-2826.2008.01696.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The neuroprotective action of oestrogens and oestrogen-like compounds is in the focus of basic and clinical research. Although such action has been shown to be associated with neuronal plasma membranes, the implication of G-proteins remains to be elucidated. This study revealed that micromolar concentrations (microM) of 17beta-oestradiol and phytoestrogens, genistein and daidzein, significantly (P < 0.05) stimulate G-proteins ([(35)S]GTP gamma S binding) in the post-mortem hippocampal membranes of age-matched control women with the respective maximum effects of 28, 20 and 15% at 10 microM. In the frontocortical membranes, the stimulation of G-proteins did not differ significantly from that in hippocampal membranes. Although in the hippocampus and frontal cortex of the Alzheimer's disease (AD) women's brain, 10 microM 17beta-oestradiol produced significantly (P < 0.05) lower stimulation of G-proteins than in the control regions, stimulation by phytoestrogens revealed no remarkable decline. 17beta-Oestradiol, genistein and daidzein revealed a selective effect on various G-proteins (G(alphas), G(alpha o), G(alpha i1) or G(alpha 11) plus G(beta 1 gamma 2)) expressed in Sf9 cells. At a concentration of 10 microM, 17beta-oestradiol suppressed the H(2)O(2) and homocysteine stimulated G-proteins in the frontocortical membranes of control women to a greater extent than phytoestrogens. In AD, the suppressing effect of each compound was lower than in the controls. In the cell-free systems, micromolar concentrations of phytoestrogens scavenged OH(*) and the 2.2-diphenyl-1-picrylhydrazyl free radical (DPPH(*)) more than 17beta-oestradiol did. In the frontocortical membranes of control women, the 20 microM 17beta-oestradiol stimulated adenylate cyclase with 20% maximal effect, whereas, in AD, the effect was insignificant. Genistein did not stimulate enzyme either in control or AD frontocortical membranes. Our data confirm that the agents stimulate G-proteins in control and AD women's brains, although 17beta-oestradiol and phytoestrogens have similarities and differences in this respect. We suggest that, besides the ER-dependent one, the ER-independent antioxidant mechanism is responsible for the oestrogen stimulation of G-proteins in the brain membranes. Both of these mechanisms could be involved in the neuroprotective signalling of oestrogens that contributes to their preventive/therapeutic action against postmenopausal neurological disorders.
Collapse
Affiliation(s)
- V Jefremov
- Department of Biochemistry, Tartu University, Tartu, Estonia
| | | | | | | | | | | | | |
Collapse
|
12
|
Aguado-Llera D, Arilla-Ferreiro E, Chowen JA, Argente J, Puebla-Jiménez L, Frago LM, Barrios V. 17β-Estradiol protects depletion of rat temporal cortex somatostatinergic system by β-amyloid. Neurobiol Aging 2007; 28:1396-409. [PMID: 16843571 DOI: 10.1016/j.neurobiolaging.2006.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 05/31/2006] [Accepted: 06/12/2006] [Indexed: 01/23/2023]
Abstract
Estradiol prevents amyloid-beta peptide (Abeta)-induced cell death through estrogen receptors (ERs) and modulates somatostatin (SRIF) responsiveness in the rat brain. As intracerebroventricular (ICV) Abeta25-35 administration reduces SRIFergic tone in the temporal cortex of ovariectomized (Ovx) rats, we asked whether 17beta-estradiol (E2) treatment can restore the Abeta25-35 induced changes in SRIF content, SRIF receptor density and adenylyl cyclase (AC) activity, as well as if these effects are mediated by ERs. E2 treatment did not change Abeta25-35 levels in the temporal cortex, but partially restored the SRIFergic parameters affected by Abeta insult and decreased cell death, which was correlated with Akt activation. The ER antagonist ICI 182,780 prevented the protective effect of E2 on sst2 levels, but did not modify SRIF levels. Furthermore, ICI 182,780 treatment further decreased sst2 protein and mRNA levels when administered alone to Abeta25-35-treated rats, suggesting that it may block the effects of endogenous estrogens. These findings indicate that E2 protects the temporal cortical SRIFergic system from Abeta-induced depletion independently of Abeta accumulation.
Collapse
Affiliation(s)
- David Aguado-Llera
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Universidad Autónoma de Madrid, Avda. Menéndez Pelayo, Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
13
|
Jefremov V, Zilmer M, Zilmer K, Bogdanovic N, Karelson E. Antioxidative effects of plant polyphenols: from protection of G protein signaling to prevention of age-related pathologies. Ann N Y Acad Sci 2007; 1095:449-57. [PMID: 17404057 DOI: 10.1196/annals.1397.048] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The antioxidant potency of three natural polyphenols, resveratrol, curcumin, and genistein, was compared by using the two human models: oxymodified with H(2)O(2) and homocysteine (Hcy) G proteins in the postmortem frontal cortex (FC) membranes of age-matched control and Alzheimer's disease (AD) subjects; and Cu(2+)-induced oxidation of plasma low-density lipoproteins (LDL). In Co, 3-10 microM polyphenols dose-dependently depressed the G protein 25% stimulation induced by 10 microM H(2)O(2) or 500 microM Hcy. Resveratrol revealed significantly higher antioxidativity than curcumin or genistein. In AD, the antioxidativity of polyphenols showed no significant differences. Polyphenols (1 microM) significantly increased the LDL oxidation lag time (oxyresistance) as compared with control, the effect of resveratrol being most potent. Due to the dual antioxidant mechanism, the investigated polyphenols, particularly resveratrol, should have preferences for the preventive-therapeutic use in age-related oxidative stress-based pathologies.
Collapse
Affiliation(s)
- Viktor Jefremov
- Department of Biochemistry, University of Tartu, Ravila 19, 50411 Tartu, Estonia
| | | | | | | | | |
Collapse
|
14
|
Burgos-Ramos E, Hervás-Aguilar A, Puebla-Jiménez L, Boyano-Adánez MC, Arilla-Ferreiro E. Chronic but not acute intracerebroventricular administration of amyloid beta-peptide(25-35) decreases somatostatin content, adenylate cyclase activity, somatostatin-induced inhibition of adenylate cyclase activity, and adenylate cyclase I levels in the rat hippocampus. J Neurosci Res 2007; 85:433-42. [PMID: 17086550 DOI: 10.1002/jnr.21115] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although alterations in adenylate cyclase (AC) activity and somatostatin (SRIF) receptor density have been reported in Alzheimer's disease, the effects of amyloid beta-peptide (Abeta) on these parameters in the hippocampus are unknown. Our aim was to investigate whether the peptide fragment Abeta(25-35) can affect the somatostatinergic system in the rat hippocampus. Hence, Abeta(25-35) was injected intracerebroventricularly (i.c.v.) to Wistar rats in a single dose or infused via an osmotic minipump connected to a cannula implanted in the right lateral ventricle during 14 days. The animals were decapitated 7 or 14 days after the single injection and 14 days after chronic infusion of the peptide. Chronic i.c.v. infusion of Abeta(25-35) decreased SRIF-like immunoreactive content without modifying the SRIF receptor density, SRIF receptor expression, or the Gialpha(1), Gialpha(2), and Gialpha(3) protein levels in the hippocampus. This treatment, however, caused a decrease in basal and forskolin-stimulated AC activity as well as in the capacity of SRIF to inhibit AC activity. Furthermore, the protein levels of the neural-specific AC type I were significantly decreased in the hippocampus of the treated rats, whereas an increase in the levels of AC V/VI was found, with no alterations in type VIII AC. A single i.c.v. dose of Abeta(25-35) exerted no effect on SRIF content or SRIF receptors but induced a slight decrease in forskolin-stimulated AC activity and its inhibition by SRIF. Because chronic Abeta(25-35) infusion impairs learning and memory whereas SRIF facilitates these functions, the alterations described here might be physiologically important given the decreased cognitive behavior previously reported in Abeta-treated rats.
Collapse
Affiliation(s)
- E Burgos-Ramos
- Grupo de Neurobioquímica, Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | | | | | | | | |
Collapse
|
15
|
Emilsson L, Saetre P, Jazin E. Low mRNA levels of RGS4 splice variants in Alzheimer's disease: association between a rare haplotype and decreased mRNA expression. Synapse 2006; 59:173-6. [PMID: 16358332 DOI: 10.1002/syn.20226] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Regulator of G-protein signaling 4 (RGS4) showed decreased mRNA levels in Alzheimer's disease in a large collection of human brain autopsies from prefrontal cortex. The expression levels of three RGS4 splice variants were examined in the same samples, and the association between RGS4 gene expression and/or the disease with single nucleotide polymorphisms located in this gene was explored. We show that all splice variants are down-regulated in patients. We also demonstrate that one rare haplotype (ATAG) is associated with decreased mRNA levels in both cases and controls. Our results suggest that an altered regulation in transcription initiation may be an important mechanism for low RGS4 protein levels in Alzeimer's disease.
Collapse
Affiliation(s)
- L Emilsson
- Department of Evolution, Genomics and Systematics, Uppsala University, Norbyvagen 18D, 75236 Uppsala, Sweden
| | | | | |
Collapse
|
16
|
Lumbreras M, Baamonde C, Martínez-Cué C, Lubec G, Cairns N, Sallés J, Dierssen M, Flórez J. Brain G protein-dependent signaling pathways in Down syndrome and Alzheimer's disease. Amino Acids 2006; 31:449-56. [PMID: 16583316 DOI: 10.1007/s00726-005-0272-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Accepted: 11/02/2005] [Indexed: 10/24/2022]
Abstract
Premature aging and neuropathological features of Alzheimer's disease (AD) are commonly observed in Down syndrome (DS). Based on previous findings in a DS mouse model, the function of signaling pathways associated with adenylyl cyclase (AC) and phospholipase C (PLC) was assessed in cerebral cortex and cerebellum of age-matched adults with DS, AD, and controls. Basal production of cAMP was reduced in DS but not in AD cortex, and in both, DS and AD cerebellum. Responses to GTPgammaS, noradrenaline, SKF 38393 and forskolin were more depressed in DS than in AD cortex and cerebellum. Although no differences in PLC activity among control, DS and AD cortex were observed under basal and GTPgammaS- or Ca-stimulated conditions, the response of DS cortex to serotonergic and cholinergic stimulation was depressed, and that of AD was only impaired at cholinergic stimulation. No differences were documented in cerebellum. Our results demonstrate that PLC and AC were severely disturbed in the aged DS and AD brains, but the alterations in DS were more severe, and differed to some extent from those observed in AD.
Collapse
Affiliation(s)
- M Lumbreras
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, Santander, Spain
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Cai D, Zhong M, Wang R, Netzer WJ, Shields D, Zheng H, Sisodia SS, Foster DA, Gorelick FS, Xu H, Greengard P. Phospholipase D1 corrects impaired betaAPP trafficking and neurite outgrowth in familial Alzheimer's disease-linked presenilin-1 mutant neurons. Proc Natl Acad Sci U S A 2006; 103:1936-40. [PMID: 16449385 PMCID: PMC1413666 DOI: 10.1073/pnas.0510710103] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Presenilins (PS1/PS2) regulate proteolysis of beta-amyloid precursor protein (betaAPP) and affect its intracellular trafficking. Here, we demonstrate that a PS1-interacting protein, phospholipase D1 (PLD1), affects intracellular trafficking of betaAPP. Overexpression of PLD1 in PS1wt cells promotes generation of betaAPP-containing vesicles from the trans-Golgi network. Conversely, inhibition of PLD1 activity by 1-butanol decreases betaAPP trafficking in both wt and PS1-deficient cells. The subcellular localization of PLD1 is altered, and PLD enzymatic activity is reduced in cells expressing familial Alzheimer's disease (FAD) PS1 mutations compared with PS1wt cells. Overexpression of wt, but not catalytically inactive, PLD1 increases budding of betaAPP-containing vesicles from the trans-Golgi network in FAD mutant cells. Surface delivery of betaAPP is also increased by PLD1 in these cells. The impaired neurite outgrowth capacity in FAD mutant neurons was corrected by introducing PLD1 into these cells. The results indicate that PLD1 may represent a therapeutic target for rescuing compromised neuronal function in AD.
Collapse
Affiliation(s)
- Dongming Cai
- *Laboratory of Molecular and Cellular Neuroscience, and Fisher Center for Research on Alzheimer Disease, The Rockefeller University, 1230 York Avenue, New York, NY 10021
| | - Minghao Zhong
- Department of Biological Sciences, Hunter College of City University of New York, New York, NY 10021
| | - Runsheng Wang
- Huffington Center on Aging, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - William J. Netzer
- *Laboratory of Molecular and Cellular Neuroscience, and Fisher Center for Research on Alzheimer Disease, The Rockefeller University, 1230 York Avenue, New York, NY 10021
| | - Dennis Shields
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York, NY 10461
| | - Hui Zheng
- Huffington Center on Aging, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Sangram S. Sisodia
- Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, IL 60637
| | - David A. Foster
- Department of Biological Sciences, Hunter College of City University of New York, New York, NY 10021
| | - Fred S. Gorelick
- *Laboratory of Molecular and Cellular Neuroscience, and Fisher Center for Research on Alzheimer Disease, The Rockefeller University, 1230 York Avenue, New York, NY 10021
- Department of Internal Medicine, Veterans Affairs Connecticut Healthcare System and Yale University, West Haven, CT 06516; and
| | - Huaxi Xu
- *Laboratory of Molecular and Cellular Neuroscience, and Fisher Center for Research on Alzheimer Disease, The Rockefeller University, 1230 York Avenue, New York, NY 10021
- **Center for Neurosciences and Aging, Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037
- To whom correspondence may be addressed. E-mail:
or
| | - Paul Greengard
- *Laboratory of Molecular and Cellular Neuroscience, and Fisher Center for Research on Alzheimer Disease, The Rockefeller University, 1230 York Avenue, New York, NY 10021
- To whom correspondence may be addressed. E-mail:
or
| |
Collapse
|
18
|
Dalfó E, Albasanz JL, Rodríguez A, Martín M, Ferrer I. Abnormal Group I Metabotropic Glutamate Receptor Expression and Signaling in the Frontal Cortex in Pick Disease. J Neuropathol Exp Neurol 2005; 64:638-47. [PMID: 16042316 DOI: 10.1097/01.jnen.0000171649.86718.f2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluR1) regulate synaptic transmission through the stimulation of phospholipase Cbeta1 (PLCbeta1) and then by the activation of protein kinase C (PKC). Considering these properties, it is conceivable that major cortical functional deficits may be attributed to abnormal mGluR processing and signaling. The present work examines mGluRI expression and signaling in the frontal cortex (area 8) of 3 cases with Pick disease (PiD), a neurodegenerative disease with abnormal phospho-tau accumulation, in comparison with 3 age-matched controls by means of glutamate binding assays, enzymatic activity, gel electrophoresis and Western blotting, solubility and immunoprecipitation assays, and confocal microscopy. Reduced expression levels of PLCbeta1 and reduced PLCbeta1 activity have been found in PiD. The expression levels of the nonrelated phospholipase PLCgamma, a substrate of tyrosine kinase, are also reduced in PiD. This is accompanied by a marked decrease in the expression of cPKCalpha and increased expression of the inner band (76 kDa) of the nPKCdelta doublet at the expense of a decrease of the phosphorylated (active) form (78 kDa). In contrast, L-[3H]glutamate-specific binding to mGluRs is augmented in PiD cases, mainly because of the higher mGluR1 and mGluRs expression levels detected. No modifications in PLCbeta1 solubility have been observed in PiD and no interactions between PLCbeta1 and tau have been demonstrated in diseased and control cases. Moreover, double-labeling immunofluorescence and confocal microscopy have shown no colocalization of phospho-tau (AT8 antibody) and PLCbeta1 in phospho-tau inclusions, including Pick bodies. These results demontrate for the first time abnormal mGluR signaling in the cerebral cortex in PiD and selective vulnerability of phospholipases and PKC to PiD.
Collapse
Affiliation(s)
- Esther Dalfó
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Spain
| | | | | | | | | |
Collapse
|
19
|
Li X, Lu F, Tian Q, Yang Y, Wang Q, Wang JZ. Activation of glycogen synthase kinase-3 induces Alzheimer-like tau hyperphosphorylation in rat hippocampus slices in culture. J Neural Transm (Vienna) 2005; 113:93-102. [PMID: 15959856 DOI: 10.1007/s00702-005-0303-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Accepted: 03/12/2005] [Indexed: 01/05/2023]
Abstract
Formation of neurofibrillary tangle from hyperphosphorylated tau is one of the hallmark lesions seen in Alzheimer's disease (AD) brain, and neuronal deregulation of glycogen synthase kinase-3 (GSK-3) activity plays key role in tau hyperphosphorylation. In the present study, the role of GSK-3 on tau phosphorylation in hippocampus slice culture was examined by incubating the slice with wortmannin (WT), an inhibitor of phosphatidylinositol 3-kinase (PI3K) and GF-109203X (GFX), an inhibitor of protein kinase C (PKC). It was found that treatment of the slices with GFX or WT separately induced tau hyperphosphorylation both at Ser396/Ser404 (PHF-1) and Ser199/Ser202 (Tau-1) sites. The phosphorylation rate of tau at PHF-1 and Tau-1 epitopes was further increased when GFX and WT were used in combination, and at this condition, AD-like tau accumulation was observed. GSK-3 activity was significantly increased with a concurrently decreased level of inactivated form of GSK-3. Lithium chloride (LiCl), a GSK-3 inhibitor, prevented tau from WT- and GFX-induced hyperphosphorylation. It suggests that GSK-3 is regulated through PI3K and PKC pathway, and activation of GSK-3 not only induces hyperphosphorylation of tau but also leads to accumulation of tau in cultured rat brain slice.
Collapse
Affiliation(s)
- X Li
- Pathophysiology Department, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan, PR China
| | | | | | | | | | | |
Collapse
|
20
|
Albasanz JL, Dalfó E, Ferrer I, Martín M. Impaired metabotropic glutamate receptor/phospholipase C signaling pathway in the cerebral cortex in Alzheimer's disease and dementia with Lewy bodies correlates with stage of Alzheimer's-disease-related changes. Neurobiol Dis 2005; 20:685-93. [PMID: 15949941 DOI: 10.1016/j.nbd.2005.05.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2004] [Revised: 04/27/2005] [Accepted: 05/02/2005] [Indexed: 10/25/2022] Open
Abstract
The aim of the present work was to analyze the status of metabotropic glutamate receptors (mGluRs) in the frontal cortex (area 8) from ten cases with common form DLB (cDLB) and eleven cases with pure AD in comparison with five age-matched controls. mGluRs, determined by radioligand binding assays, were significantly decreased in cerebral cortex in cDLB. This decrease was already present in cases with early AD changes not involving the frontal cortex, but dramatically correlated with AD neuropathological changes, at its greatest in isocortical stages, which was associated with a decrease in the expression levels of mGluR1 detected by Western blotting. Moreover, mGluRs analyzed in pure AD were lower than those obtained in cDLB and also correlated with progression of illness. On the other hand, the expression levels of phospholipase Cbeta1 (PLCbeta1) isoform, which is the effector of group I mGluRs, was decreased in parallel in cDLB cases. Finally, the PLCbeta1 decrease was associated with reduced GTP- and l-glutamate-stimulated PLC activity in both cDLB and AD cases. These results show that group I mGluRs/PLC signaling are down-regulated and desensitized in the frontal cortex in cDLB and AD cases and that these modifications worsen with progression of AD changes in the cerebral neocortex. Therefore, group I mGluR dysfunction may be implicated in the pathogenesis of cognitive impairment and dementia in common form of DLB and pure AD.
Collapse
Affiliation(s)
- José Luis Albasanz
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Ciencias Químicas, Area de Bioquímica, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Avenida Camilo José Cela, 10, 13071 Ciudad Real, Spain
| | | | | | | |
Collapse
|
21
|
Aguado-Llera D, Arilla-Ferreiro E, Campos-Barros A, Puebla-Jiménez L, Barrios V. Protective effects of insulin-like growth factor-I on the somatostatinergic system in the temporal cortex of beta-amyloid-treated rats. J Neurochem 2005; 92:607-15. [PMID: 15659230 DOI: 10.1111/j.1471-4159.2004.02889.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Insulin-like growth factor-I (IGF-I) has protective effects against beta-amyloid (Abeta)-induced neuronal cell death. Because alterations of the somatostatinergic system have been described in Alzheimer's disease, we investigated the effects of the Abeta peptide and the possible protective role of IGF-I on the somatostatinergic system of the rat temporal cortex and on cell death and phosphorylated (p)-Akt levels in this area. Abeta25-35 was administered intracerebroventricularly to male rats via an osmotic minipump over 14 days (300 pmol/day). Another group received a subcutaneous IGF-I infusion (50 microg/kg/day), concomitant with Abeta25-35 administration, whereas a third group received IGF-I alone. Abeta25-35 significantly decreased the somatostatin (SRIF)-like immunoreactive content and the SRIF receptor density, as a result of a decrease in the levels of the SRIF receptor subtype 2. The inhibitory effect of SRIF on adenylyl cyclase activity was significantly lower after Abeta25-35 infusion, whereas the levels of the inhibitory G protein subunit Gialpha1, Gialpha2 or Gialpha3 were unaltered. Cell death was increased and p-Akt levels decreased in Abeta25-35-treated animals. IGF-I administration increased immunoreactive IGF-I levels in the temporal cortex and restored all parameters affected by Abeta25-35 to baseline values. These findings suggest that IGF-I prevents the deleterious effect of Abeta25-35 on the somatostatinergic system.
Collapse
Affiliation(s)
- D Aguado-Llera
- Research Laboratory, Universidad Autónoma, Hospital Infantil Universitario Niño Jesús, Avda. Menéndez Pelayo 65, E-28009 Madrid, Spain
| | | | | | | | | |
Collapse
|
22
|
Tyszkiewicz JP, Yan Z. beta-Amyloid peptides impair PKC-dependent functions of metabotropic glutamate receptors in prefrontal cortical neurons. J Neurophysiol 2005; 93:3102-11. [PMID: 15659527 DOI: 10.1152/jn.00939.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The metabotropic glutamate receptors (mGluRs) have been implicated in cognition, memory, and some neurodegenerative disorders, including the Alzheimer's disease (AD). To understand how the dysfunction of mGluRs contributes to the pathophysiology of AD, we examined the beta-amyloid peptide (Abeta)-induced alterations in the physiological functions of mGluRs in prefrontal cortical pyramidal neurons. Two potential targets of mGluR signaling involved in cognition, the GABAergic system and the N-methyl-d-aspartate (NMDA) receptor, were examined. Activation of group I mGluRs with (S)-3,5-dihydroxyphenylglycine (DHPG) significantly increased the spontaneous inhibitory postsynaptic current (sIPSC) amplitude, and this effect was protein kinase C (PKC) sensitive. Treatment with Abeta abolished the DHPG-induced enhancement of sIPSC amplitude. On the other hand, activation of group II mGluRs with (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate (APDC) significantly increased the NMDA receptor (NMDAR)-mediated currents via a PKC-dependent mechanism, and Abeta treatment also diminished the APDC-induced potentiation of NMDAR currents. In Abeta-treated slices, both DHPG and APDC failed to activate PKC. These results indicate that the mGluR regulation of GABA transmission and NMDAR currents is impaired by Abeta treatment probably due to the Abeta-mediated interference of mGluR activation of PKC. This study provides a framework within which the role of mGluRs in normal cognitive functions and AD can be better understood.
Collapse
Affiliation(s)
- Joanna P Tyszkiewicz
- Dept. of Physiology and Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY, 14214, USA
| | | |
Collapse
|
23
|
Rodríguez A, Freixes M, Dalfó E, Martín M, Puig B, Ferrer I. Metabotropic glutamate receptor/phospholipase C pathway: A vulnerable target to Creutzfeldt-Jakob disease in the cerebral cortex. Neuroscience 2005; 131:825-32. [PMID: 15749337 DOI: 10.1016/j.neuroscience.2004.12.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2004] [Indexed: 10/25/2022]
Abstract
Glutamate is the main excitatory neurotransmitter in the cerebral cortex. Altered glutamatergic transmission has been suggested as having a central role in many neurodegenerative diseases. Metabotropic glutamate receptors (mGluRs) are coupled to intracellular signal transduction via G proteins, and they mediate slower responses than ionotropic glutamate receptors. Group I mGluRs are positively coupled to phospholipase C beta1 (PLCbeta1). Creutzfeldt-Jakob disease (CJD) is a human transmissible spongiform encephalopathy associated with a dysfunction in the membrane glycoprotein PrP which is converted into an abnormal isoform, with a predominant beta-sheet structure, that is pathogenic and partially resistant to protease digestion. Proteins associated with the signal transduction of group I mGluRs were examined in the frontal cortex (area 8) of 12 cases with sCJD and four age-matched controls, by means of gel electrophoresis and Western blotting of total homogenates. Densitometric analysis of the bands demonstrated decreased expression levels of PLCbeta1 and PLCgamma, a non-related phospholipase which is a substrate of tyrosine kinase, in CJD cases when compared with controls. Novel protein kinase C delta (nPKCdelta) has also been found to be significantly decreased in CJD cases. However, no modifications in mGluR1 cPKCalpha expression levels are found in CJD when compared with controls. No modifications in PLCbeta1 solubility in PBS-, deoxycholate- and sodium dodecylsulphate-soluble fractions have been observed in CJD when compared with controls. Finally, no interactions between PLCbeta1 and PrP, as revealed by immunoprecipitation assays, have been found in CJD and controls. The present results show, for the first time, reduced expression levels of phospholipases, particularly PLCbeta1, which may interfere with group I mGluR signaling in the cerebral cortex in CJD. These abnormalities are not the result of abnormal PLC solubility or interactions with PrP. Selective involvement of group I mGluRs may have functional effects on glutamatergic transmission modulation and processing in CJD.
Collapse
Affiliation(s)
- A Rodríguez
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, c/ Feixa llarga sn, 08907 Hospitalet de Llobregat, Spain
| | | | | | | | | | | |
Collapse
|
24
|
Aguado-Llera D, Martín-Martínez M, García-López MT, Arilla-Ferreiro E, Barrios V. Gly-Pro-Glu protects beta-amyloid-induced somatostatin depletion in the rat cortex. Neuroreport 2004; 15:1979-82. [PMID: 15305149 DOI: 10.1097/00001756-200408260-00029] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effect of Gly-Pro-Glu (GPE) on the somatostatinergic system of the temporal cortex in amyloid beta-peptide (Abeta) treated rats was investigated. Intracerebroventricular Abeta25-35 administration for 14 days (300 pmol/day) to ovariectomized rats produced a marked reduction in somatostatin (SRIF) content, SRIF receptor density and reduced the inhibitory effect of SRIF on adenylyl cyclase activity. I.p. injection of three doses (300 microg) of GPE on days 0, 6 and 12 resulted in a partial recovery of the parameters affected by Abeta25-35 administration. These results indicate that GPE may have an in vivo effect protecting the temporal cortical somatostatinergic system from Abeta insult.
Collapse
Affiliation(s)
- David Aguado-Llera
- Department of Endocrinology and Research Laboratory Hospital Infantil Universitario Niño Jesús, Universidad Autónoma, E-28009 Madrid, Spain
| | | | | | | | | |
Collapse
|
25
|
Dalfó E, Albasanz JL, Martín M, Ferrer I. Abnormal metabotropic glutamate receptor expression and signaling in the cerebral cortex in diffuse Lewy body disease is associated with irregular alpha-synuclein/phospholipase C (PLCbeta1) interactions. Brain Pathol 2004; 14:388-98. [PMID: 15605986 PMCID: PMC8095885 DOI: 10.1111/j.1750-3639.2004.tb00082.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diffuse Lewy body disease (DLBD) is a degenerative disease of the nervous system, involving the brain stem, diencephalic nuclei and cerebral cortex, associated with abnormal a-synuclein aggregation and widespread formation of Lewy bodies and Lewy neurites. DLBD presents as pure forms (DLBDp) or in association with Alzheimer disease (AD) in the common forms (DLBDc). Several neurotransmitter abnormalities have been reported including those of the nigrostriatal and mesocorticolimbic dopaminergic system, and central noradrenergic, serotoninergic and cholinergic pathways. The present work examines metabotropic glutamate receptor (mGluR) expression and signaling in the frontal cortex of DLBDp and DLBDc cases in comparison with age-matched controls. Abnormal L-[3H]glutamate specific binding to group I and II mGluRs, and abnormal mGluR1 levels have been found in DLBD. This is associated with reduced expression levels of phospholipase C beta1 (PLCbeta1), the effector of group I mGluRs following protein G activation upon glutamate binding. Additional modification in the solubility of PLCbeta1 and reduced PLCbeta1 activity in pure and common DLBD further demonstrates for the first time abnormal mGluR signaling in the cerebral cortex in DLBD. In order to look for a possible link between abnormal mGluR signaling and a-synuclein accumulation in DLBD, immunoprecipitation studies have shown alpha-synuclein/PLCbeta1 binding in controls and decreased alpha-synuclein/PLCbeta1 binding in DLBD. This is accompanied by a shift in the distribution of a-synuclein, but not of PLCbeta1, in DLBD when compared with controls. Together, these results support the concept that abnormal a-synuclein in DLBD produces functional effects on cortical glutamatergic synapses, which are associated with reduced alpha-synuclein/PLCbeta1 interactions, and, therefore, that mGluRs are putative pharmacological targets in DLBD. Finally, these results emphasize the emergence of a functional neuropathology that has to be explored for a better understanding of the effects of abnormal protein interactions in degenerative diseases of the nervous system.
Collapse
Affiliation(s)
- E. Dalfó
- Instituto de Neuropatología, Servicio de Anatomía Patológica, IDIBELL‐Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Spain
| | - J. L. Albasanz
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla‐La Mancha, Ciudad Real, Spain
| | - M. Martín
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla‐La Mancha, Ciudad Real, Spain
| | - I. Ferrer
- Instituto de Neuropatología, Servicio de Anatomía Patológica, IDIBELL‐Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Spain
- Departamento de Biología Celular y Anatomía Patológica, Facultad de Medicina, Universidad de Barcelona, campus de Bellvitge, Hospitalet de Llobregat, Spain
| |
Collapse
|
26
|
Liu SJ, Zhang AH, Li HL, Wang Q, Deng HM, Netzer WJ, Xu H, Wang JZ. Overactivation of glycogen synthase kinase-3 by inhibition of phosphoinositol-3 kinase and protein kinase C leads to hyperphosphorylation of tau and impairment of spatial memory. J Neurochem 2004; 87:1333-44. [PMID: 14713290 DOI: 10.1046/j.1471-4159.2003.02070.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neurofibrillary tangles (NFTs) consisting of the hyperphosphorylated microtubule-associated protein tau are a defining pathological characteristic of Alzheimer's disease (AD). Hyperphosphorylation of tau is hypothesized to impair the microtubule stabilizing function of tau, leading to the formation of paired helical filaments and neuronal death. Glycogen synthase kinase-3 (GSK-3) has been shown to be one of several kinases that mediate tau hyperphosphorylation in vitro. However, molecular mechanisms underlying overactivation of GSK-3 and its potential linkage to AD-like pathologies in vivo remain unclear. Here, we demonstrate that injection of wortmannin (a specific inhibitor of phosphoinositol-3 kinase) or GF-109203X (a specific inhibitor of protein kinase C) into the left ventricle of rat brains leads to overactivation of GSK-3, hyperphosphorylation of tau at Ser 396/404/199/202 and, most significantly, impaired spatial memory. The effects of wortmannin and GF-109203X are additive. Significantly, specific inhibition of GSK-3 activity by LiCl prevents hyperphosphorylation of tau, and spatial memory impairment resulting from PI3K and PKC inhibition. These results indicate that in vivo inhibition of phosphoinositol-3 kinase and protein kinase C results in overactivation of GSK-3 and tau hyperphosphorylation and support a direct role of GSK-3 in the formation of AD-like cognitive deficits.
Collapse
Affiliation(s)
- Shi Jie Liu
- Pathophysiology Department, Neuroscience Institute, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Mahlapuu R, Viht K, Balaspiri L, Bogdanovic N, Saar K, Soomets U, Land T, Zilmer M, Karelson E, Langel U. Amyloid precursor protein carboxy-terminal fragments modulate G-proteins and adenylate cyclase activity in Alzheimer's disease brain. ACTA ACUST UNITED AC 2003; 117:73-82. [PMID: 14499483 DOI: 10.1016/s0169-328x(03)00292-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The influence of three C-terminal sequences and of transmembrane domain from amyloid precursor protein (APP) on the activity of G-proteins and of the coupled cAMP-signalling system in the postmortem Alzheimer's disease (AD) and age-matched control brains was compared. 10 microM APP(639-648)-APP(657-676) (PEP1) causes a fivefold stimulation in the [35S]GTPgammaS-binding to control hippocampal G-proteins. APP(657-676) (PEP2) and APP(639-648) (PEP4) showed less pronounced stimulation whereas cytosolic APP(649-669) (PEP3) showed no regulatory activity in the [35S]GTPgammaS-binding. PEP1 also showed 1.4-fold stimulatory effect of on the high-affinity GTPase and adenylate cyclase activity in control membranes, whereas in AD hippocampal membranes the stimulatory effect of PEP1 was substantially weaker. The PEP1 stimulation of the [35S]GTPgammaS-binding to the control membranes was significantly reduced by 1.5 mM glutathione, 0.5 mM antioxidant N-acetylcysteine and, in the greatest extent, by 0.01 mM of desferrioxamine. In AD hippocampus these antioxidants revealed no remarkable reducing effect on PEP1-induced stimulation. Our results suggest that C-terminal and transmembrane APP sequences possess receptor-like G-protein activating function in human hippocampus and that abnormalities of this function contribute to AD progression. The stimulatory action of these sequences on G-protein mediated signalling suggests the region-specific formation of reactive species.
Collapse
Affiliation(s)
- Riina Mahlapuu
- Department of Biochemistry, Tartu University, 50411 Tartu, Estonia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Li L. The biochemistry and physiology of metallic fluoride: action, mechanism, and implications. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2003; 14:100-14. [PMID: 12764073 DOI: 10.1177/154411130301400204] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fluoride is a well-known G protein activator. Activation of heterotrimeric GTP-binding proteins by fluoride requires trace amounts of Al3+ or Be2+ ions. AlFx mimics a gamma-phosphate at its transition state in a Galpha protein and is therefore able to inhibit its GTPase activity. AlFx also forms complexes with small GTP-binding proteins in the presence of their GTPase-activating proteins (GAP). As phosphate analogs, AlFx or BeFx affect the activity of a variety of phosphoryl transfer enzymes. Most of these enzymes are fundamentally important in cell signal transduction or energy metabolism. Al3+ and F- tend to form stable complexes in aqueous solution. The exact structure and concentration of AlFx depend on the pH and the amount of F- and Al3+ in the solution. Humans are exposed to both F and Al. It is possible that Al-F complexes may be formed in vivo, or formed in vitro prior to their intake by humans. Al-F complexes may play physiological or pathological roles in bone biology, fluorosis, neurotoxicity, and oral diseases such as dental caries and periodontal disease. The aim of this review is to discuss the basic chemical, biochemical, and toxicological properties of metallic fluoride, to explore its potential physiological and clinical implications.
Collapse
Affiliation(s)
- Liang Li
- Faculty of Dentistry, University of Manitoba, Winnipeg, MB, Canada.
| |
Collapse
|