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Vitória JJM, Trigo D, da Cruz E Silva OAB. Revisiting APP secretases: an overview on the holistic effects of retinoic acid receptor stimulation in APP processing. Cell Mol Life Sci 2022; 79:101. [PMID: 35089425 PMCID: PMC11073327 DOI: 10.1007/s00018-021-04090-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 11/18/2021] [Accepted: 12/01/2021] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia worldwide and is characterized by the accumulation of the β-amyloid peptide (Aβ) in the brain, along with profound alterations in phosphorylation-related events and regulatory pathways. The production of the neurotoxic Aβ peptide via amyloid precursor protein (APP) proteolysis is a crucial step in AD development. APP is highly expressed in the brain and is complexly metabolized by a series of sequential secretases, commonly denoted the α-, β-, and γ-cleavages. The toxicity of resulting fragments is a direct consequence of the first cleaving event. β-secretase (BACE1) induces amyloidogenic cleavages, while α-secretases (ADAM10 and ADAM17) result in less pathological peptides. Hence this first cleavage event is a prime therapeutic target for preventing or reverting initial biochemical events involved in AD. The subsequent cleavage by γ-secretase has a reduced impact on Aβ formation but affects the peptides' aggregating capacity. An array of therapeutic strategies are being explored, among them targeting Retinoic Acid (RA) signalling, which has long been associated with neuronal health. Additionally, several studies have described altered RA levels in AD patients, reinforcing RA Receptor (RAR) signalling as a promising therapeutic strategy. In this review we provide a holistic approach focussing on the effects of isoform-specific RAR modulation with respect to APP secretases and discuss its advantages and drawbacks in subcellular AD related events.
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Affiliation(s)
- José J M Vitória
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Diogo Trigo
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal.
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2
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da Rocha JF, Bastos L, Domingues SC, Bento AR, Konietzko U, da Cruz E Silva OAB, Vieira SI. APP Binds to the EGFR Ligands HB-EGF and EGF, Acting Synergistically with EGF to Promote ERK Signaling and Neuritogenesis. Mol Neurobiol 2021; 58:668-688. [PMID: 33009641 DOI: 10.1007/s12035-020-02139-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/17/2020] [Indexed: 12/31/2022]
Abstract
The amyloid precursor protein (APP) is a transmembrane glycoprotein central to Alzheimer's disease (AD) with functions in brain development and plasticity, including in neurogenesis and neurite outgrowth. Epidermal growth factor (EGF) and heparin-binding EGF-like growth factor (HB-EGF) are well-described neurotrophic and neuromodulator EGFR ligands, both implicated in neurological disorders, including AD. Pro-HB-EGF arose as a putative novel APP interactor in a human brain cDNA library yeast two-hybrid screen. Based on their structural and functional similarities, we first aimed to verify if APP could bind to (HB-)EGF proforms. Here, we show that APP interacts with these two EGFR ligands, and further characterized the effects of APP-EGF interaction in ERK activation and neuritogenesis. Yeast co-transformation and co-immunoprecipitation assays confirmed APP interaction with HB-EGF. Co-immunoprecipitation also revealed that APP binds to cellular pro-EGF. Overexpression of HB-EGF in HeLa cells, or exposure of SH-SY5Y cells to EGF, both resulted in increased APP protein levels. EGF and APP were observed to synergistically activate the ERK pathway, crucial for neuronal differentiation. Immunofluorescence analysis of cellular neuritogenesis in APP overexpression and EGF exposure conditions confirmed a synergistic effect in promoting the number and the mean length of neurite-like processes. Synergistic ERK activation and neuritogenic effects were completely blocked by the EGFR inhibitor PD 168393, implying APP/EGF-induced activation of EGFR as part of the mechanism. This work shows novel APP protein interactors and provides a major insight into the APP/EGF-driven mechanisms underlying neurite outgrowth and neuronal differentiation, with potential relevance for AD and for adult neuroregeneration.
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Affiliation(s)
- Joana F da Rocha
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal
| | - Luísa Bastos
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal
- Roche Sistemas de Diagnósticos, Lda, 2720-413, Amadora, Portugal
| | - Sara C Domingues
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal
| | - Ana R Bento
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal
| | - Uwe Konietzko
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Odete A B da Cruz E Silva
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal
| | - Sandra I Vieira
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Agra do Crasto, 3810-193, Aveiro, Portugal.
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3
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Soares Martins T, Trindade D, Vaz M, Campelo I, Almeida M, Trigo G, da Cruz E Silva OAB, Henriques AG. Diagnostic and therapeutic potential of exosomes in Alzheimer's disease. J Neurochem 2020; 156:162-181. [PMID: 32618370 DOI: 10.1111/jnc.15112] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/20/2020] [Accepted: 06/18/2020] [Indexed: 12/12/2022]
Abstract
Exosomes are small extracellular vesicles released by almost all cell types in physiological and pathological conditions. The exosomal potential to unravel disease mechanisms, or to be used as a source of biomarkers, is being explored, in particularly in the field of neurodegenerative diseases. Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the world and exosomes appear to have a relevant role in disease pathogenesis. This review summarizes the current knowledge on exosome contributions to AD as well as their use as disease biomarker resources or therapeutic targets. The most recent findings with respect to both protein and miRNA biomarker candidates for AD, herein described, highlight the state of the art in this field and encourage the use of exosomes derived from biofluids in clinical practice in the near future.
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Affiliation(s)
- Tânia Soares Martins
- Neurosciences and Signalling Group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Dário Trindade
- Neurosciences and Signalling Group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Margarida Vaz
- Neurosciences and Signalling Group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Inês Campelo
- Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Martim Almeida
- Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Guilherme Trigo
- Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Neurosciences and Signalling Group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.,The Discovery CTR, University of Aveiro Campus, Aveiro, Portugal
| | - Ana Gabriela Henriques
- Neurosciences and Signalling Group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
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4
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Gandy S, Suzuki T. Paul Greengard, Ph.D. (1925-2019). Alzheimers Dement 2019; 15:1229-1235. [DOI: 10.1016/j.jalz.2019.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 08/05/2019] [Indexed: 10/26/2022]
Affiliation(s)
- Sam Gandy
- Mount Sinai Center for Cognitive Health and NFL Neurological Care; Icahn School of Medicine at Mount Sinai; New York NY USA
| | - Toshiharu Suzuki
- Department of Neuroscience; School of Pharmaceutical Sciences Hokkaido University; Sapporo Hokkaido Japan
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5
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Sarajärvi T, Jäntti M, Paldanius KMA, Natunen T, Wu JC, Mäkinen P, Tarvainen I, Tuominen RK, Talman V, Hiltunen M. Protein kinase C -activating isophthalate derivatives mitigate Alzheimer's disease-related cellular alterations. Neuropharmacology 2018; 141:76-88. [PMID: 30138694 DOI: 10.1016/j.neuropharm.2018.08.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/15/2018] [Accepted: 08/19/2018] [Indexed: 12/26/2022]
Abstract
Abnormal protein kinase C (PKC) function contributes to many pathophysiological processes relevant for Alzheimer's disease (AD), such as amyloid precursor protein (APP) processing. Phorbol esters and other PKC activators have been demonstrated to enhance the secretion of soluble APPα (sAPPα), reduce the levels of β-amyloid (Aβ), induce synaptogenesis, and promote neuroprotection. We have previously described isophthalate derivatives as a structurally simple family of PKC activators. Here, we characterised the effects of isophthalate derivatives HMI-1a3 and HMI-1b11 on neuronal viability, neuroinflammatory response, processing of APP and dendritic spine density and morphology in in vitro. HMI-1a3 increased the viability of embryonic primary cortical neurons and decreased the production of the pro-inflammatory mediator TNFα, but not that of nitric oxide, in mouse neuron-BV2 microglia co-cultures upon LPS- and IFN-γ-induced neuroinflammation. Furthermore, both HMI-1a3 and HMI-1b11 increased the levels of sAPPα relative to total sAPP and the ratio of Aβ42/Aβ40 in human SH-SY5Y neuroblastoma cells. Finally, bryostatin-1, but not HMI-1a3, increased the number of mushroom spines in proportion to total spine density in mature mouse hippocampal neuron cultures. These results suggest that the PKC activator HMI-1a3 exerts neuroprotective functions in the in vitro models relevant for AD by reducing the production of TNFα and increasing the secretion of neuroprotective sAPPα.
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Affiliation(s)
- T Sarajärvi
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - M Jäntti
- Drug Research Program and Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - K M A Paldanius
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - T Natunen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - J C Wu
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - P Mäkinen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - I Tarvainen
- Drug Research Program and Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - R K Tuominen
- Drug Research Program and Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
| | - V Talman
- Drug Research Program and Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - M Hiltunen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
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6
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Du Y, Zhao Y, Li C, Zheng Q, Tian J, Li Z, Huang TY, Zhang W, Xu H. Inhibition of PKCδ reduces amyloid-β levels and reverses Alzheimer disease phenotypes. J Exp Med 2018; 215:1665-1677. [PMID: 29739836 PMCID: PMC5987914 DOI: 10.1084/jem.20171193] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 01/11/2018] [Accepted: 03/29/2018] [Indexed: 12/28/2022] Open
Abstract
β-amyloid protein (Aβ) plays a central role in the pathogenesis of Alzheimer disease (AD). Aβ is generated from sequential cleavage of amyloid precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) and the γ-secretase complex. Although activation of some protein kinase C (PKC) isoforms such as PKCα and ε has been shown to regulate nonamyloidogenic pathways and Aβ degradation, it is unclear whether other PKC isoforms are involved in APP processing/AD pathogenesis. In this study, we report that increased PKCδ levels correlate with BACE1 expression in the AD brain. PKCδ knockdown reduces BACE1 expression, BACE1-mediated APP processing, and Aβ production. Conversely, overexpression of PKCδ increases BACE1 expression and Aβ generation. Importantly, inhibition of PKCδ by rottlerin markedly reduces BACE1 expression, Aβ levels, and neuritic plaque formation and rescues cognitive deficits in an APP Swedish mutations K594N/M595L/presenilin-1 with an exon 9 deletion-transgenic AD mouse model. Our study indicates that PKCδ plays an important role in aggravating AD pathogenesis, and PKCδ may be a potential target in AD therapeutics.
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Affiliation(s)
- Ying Du
- Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xian, China
| | - Yingjun Zhao
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Chuan Li
- Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xian, China
| | - Qiuyang Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, The Collaborative Innovation Center for Brain Science, Medical College, Xiamen University, Xiamen, China
| | - Jing Tian
- College of Life Sciences and Oceanography, Shenzhen Key Laboratory of Marine Bioresources and Eco-Environmental Science, Shenzhen University, Shenzhen, China
| | - Zhuyi Li
- Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xian, China
| | - Timothy Y Huang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Wei Zhang
- Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xian, China
| | - Huaxi Xu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA.,Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, The Collaborative Innovation Center for Brain Science, Medical College, Xiamen University, Xiamen, China
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7
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Fisher DW, Bennett DA, Dong H. Sexual dimorphism in predisposition to Alzheimer's disease. Neurobiol Aging 2018; 70:308-324. [PMID: 29754747 DOI: 10.1016/j.neurobiolaging.2018.04.004] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 04/08/2018] [Accepted: 04/10/2018] [Indexed: 12/20/2022]
Abstract
Clinical studies indicate that Alzheimer's disease (AD) disproportionately affects women in both disease prevalence and rate of symptom progression, but the mechanisms underlying this sexual divergence are unknown. Although some have suggested this difference in risk is a reflection of the known differences in longevity between men and women, mounting clinical and preclinical evidence supports women also having intrinsic susceptibilities toward the disease. Although a number of potential risk factors have been hypothesized to mediate these differences, none have been definitively verified. In this review, we first summarize the epidemiologic studies of prevalence and incidence of AD among the sexes. Next, we discuss the most likely risk factors to date that interact with biological sex, including (1) genetic factors, (2) sex hormones (3) deviations in brain structure, (4) inflammation and microglia, and (5) and psychosocial stress responses. Overall, though differences in life span are likely to account for part of the divide between the sexes in AD prevalence, the abundance of preclinical and clinical evidence presented here suggests an increase in intrinsic AD risk for women. Therefore, future studies focusing on the underlying biological mechanisms for this phenomenon are needed to better understand AD pathogenesis in both sexes, with the eventual goal of sex-specific prevention and treatment strategies.
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Affiliation(s)
- Daniel W Fisher
- Departments of Psychiatry and Behavioral Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
| | - David A Bennett
- Department of Neurological Sciences, Rush Alzheimer's Disease Center, Rush Medical College, Chicago, IL, USA
| | - Hongxin Dong
- Departments of Psychiatry and Behavioral Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA.
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8
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Yan Y, Dominguez S, Fisher DW, Dong H. Sex differences in chronic stress responses and Alzheimer's disease. Neurobiol Stress 2018; 8:120-126. [PMID: 29888307 PMCID: PMC5991323 DOI: 10.1016/j.ynstr.2018.03.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/10/2018] [Accepted: 03/17/2018] [Indexed: 11/13/2022] Open
Abstract
Clinical studies indicate that Alzheimer's disease (AD) disproportionately affects women in both disease prevalence and severity, but the mechanisms underlying this sex divergence are unknown. Though some have suggested this difference in risk is a reflection of known differences in longevity between men and women, mounting clinical and preclinical evidence supports women also having intrinsic susceptibilities towards the disease. While a number of potential risk factors have been hypothesized to affect these differences in risks, none have been definitively verified. In this review, we discuss a novel hypothesis whereby women's susceptibility to chronic stress also mediates increased risk for AD. As stress is a risk factor for AD, and women are twice as likely to develop mood disorders where stress is a major etiology, it is possible that sex dimorphisms in stress responses contribute to the increase in women with AD. In line with this, sex divergence in biochemical responses to stress have been noted along the hypothalamic-pituitary-adrenal (HPA) axis and among known molecular effectors of AD, with crosstalk between these processes also being likely. In addition, activation of the cortical corticotrophin-releasing factor receptor 1 (CRF1) signaling pathway leads to distinct female-biased increases in molecules associated with AD pathogenesis. Therefore, the different biochemical responses to stress between women and men may represent an intrinsic, sex-dependent risk factor for AD.
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Affiliation(s)
- Yan Yan
- Department of Psychiatry & Behavioral Sciences, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Department of Physiology, Zunyi Medical University, Zunyi Guizhou 563099, China
| | - Sky Dominguez
- Department of Psychiatry & Behavioral Sciences, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Daniel W. Fisher
- Department of Neurology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Hongxin Dong
- Department of Psychiatry & Behavioral Sciences, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Department of Physiology, Zunyi Medical University, Zunyi Guizhou 563099, China
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9
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Sajan MP, Hansen BC, Higgs MG, Kahn CR, Braun U, Leitges M, Park CR, Diamond DM, Farese RV. Atypical PKC, PKCλ/ι, activates β-secretase and increases Aβ 1-40/42 and phospho-tau in mouse brain and isolated neuronal cells, and may link hyperinsulinemia and other aPKC activators to development of pathological and memory abnormalities in Alzheimer's disease. Neurobiol Aging 2018; 61:225-237. [PMID: 29032894 PMCID: PMC5705272 DOI: 10.1016/j.neurobiolaging.2017.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/25/2017] [Accepted: 09/03/2017] [Indexed: 12/31/2022]
Abstract
Hyperinsulinemia activates brain Akt and PKC-λ/ι and increases Aβ1-40/42 and phospho-tau in insulin-resistant animals. Here, we examined underlying mechanisms in mice, neuronal cells, and mouse hippocampal slices. Like Aβ1-40/42, β-secretase activity was increased in insulin-resistant mice and monkeys. In insulin-resistant mice, inhibition of hepatic PKC-λ/ι sufficient to correct hepatic abnormalities and hyperinsulinemia simultaneously reversed increases in Akt, atypical protein kinase C (aPKC), β-secretase, and Aβ1-40/42, and restored acute Akt activation. However, 2 aPKC inhibitors additionally blocked insulin's ability to activate brain PKC-λ/ι and thereby increase β-secretase and Aβ1-40/42. Furthermore, direct blockade of brain aPKC simultaneously corrected an impairment in novel object recognition in high-fat-fed insulin-resistant mice. In neuronal cells and/or mouse hippocampal slices, PKC-ι/λ activation by insulin, metformin, or expression of constitutive PKC-ι provoked increases in β-secretase, Aβ1-40/42, and phospho-thr-231-tau that were blocked by various PKC-λ/ι inhibitors, but not by an Akt inhibitor. PKC-λ/ι provokes increases in brain β-secretase, Aβ1-40/42, and phospho-thr-231-tau. Excessive signaling via PKC-λ/ι may link hyperinsulinemia and other PKC-λ/ι activators to pathological and functional abnormalities in Alzheimer's disease.
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Affiliation(s)
- Mini P Sajan
- Internal Medicine and Research Services, James A. Haley Veterans Medical Center, Tampa, Florida, USA; Department of Internal Medicine, University of South Florida College of Medicine, Tampa, Florida, USA
| | - Barbara C Hansen
- Internal Medicine and Research Services, James A. Haley Veterans Medical Center, Tampa, Florida, USA
| | - Margaret G Higgs
- Internal Medicine and Research Services, James A. Haley Veterans Medical Center, Tampa, Florida, USA
| | - C Ron Kahn
- Joslin Research Foundation, Harvard Medical School, Boston, MA, USA
| | | | | | - Collin R Park
- Departments of Psychology, Molecular Pharmacology and Physiology, Center for Preclinical and Clinical Research on PTSD, University of South Florida, Tampa, Florida, USA
| | - David M Diamond
- Departments of Psychology, Molecular Pharmacology and Physiology, Center for Preclinical and Clinical Research on PTSD, University of South Florida, Tampa, Florida, USA
| | - Robert V Farese
- Internal Medicine and Research Services, James A. Haley Veterans Medical Center, Tampa, Florida, USA; Department of Internal Medicine, University of South Florida College of Medicine, Tampa, Florida, USA.
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10
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Small things matter: Implications of APP intracellular domain AICD nuclear signaling in the progression and pathogenesis of Alzheimer’s disease. Prog Neurobiol 2017; 156:189-213. [DOI: 10.1016/j.pneurobio.2017.05.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/08/2023]
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11
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Alfonso SI, Callender JA, Hooli B, Antal CE, Mullin K, Sherman MA, Lesné SE, Leitges M, Newton AC, Tanzi RE, Malinow R. Gain-of-function mutations in protein kinase Cα (PKCα) may promote synaptic defects in Alzheimer's disease. Sci Signal 2016; 9:ra47. [PMID: 27165780 PMCID: PMC5154619 DOI: 10.1126/scisignal.aaf6209] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is a progressive dementia disorder characterized by synaptic degeneration and amyloid-β (Aβ) accumulation in the brain. Through whole-genome sequencing of 1345 individuals from 410 families with late-onset AD (LOAD), we identified three highly penetrant variants in PRKCA, the gene that encodes protein kinase Cα (PKCα), in five of the families. All three variants linked with LOAD displayed increased catalytic activity relative to wild-type PKCα as assessed in live-cell imaging experiments using a genetically encoded PKC activity reporter. Deleting PRKCA in mice or adding PKC antagonists to mouse hippocampal slices infected with a virus expressing the Aβ precursor CT100 revealed that PKCα was required for the reduced synaptic activity caused by Aβ. In PRKCA(-/-) neurons expressing CT100, introduction of PKCα, but not PKCα lacking a PDZ interaction moiety, rescued synaptic depression, suggesting that a scaffolding interaction bringing PKCα to the synapse is required for its mediation of the effects of Aβ. Thus, enhanced PKCα activity may contribute to AD, possibly by mediating the actions of Aβ on synapses. In contrast, reduced PKCα activity is implicated in cancer. Hence, these findings reinforce the importance of maintaining a careful balance in the activity of this enzyme.
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Affiliation(s)
- Stephanie I Alfonso
- Department of Neurosciences and Division of Biology, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Julia A Callender
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA. Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Basavaraj Hooli
- Genetics and Aging Research Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Corina E Antal
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA. Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kristina Mullin
- Genetics and Aging Research Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Mathew A Sherman
- Department of Neuroscience, N. Bud Grossman Center for Memory Research and Care, and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN 55414, USA
| | - Sylvain E Lesné
- Department of Neuroscience, N. Bud Grossman Center for Memory Research and Care, and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN 55414, USA
| | - Michael Leitges
- Biotechnology Centre of Oslo, University of Oslo, Oslo 0317, Norway
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Rudolph E Tanzi
- Genetics and Aging Research Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.
| | - Roberto Malinow
- Department of Neurosciences and Division of Biology, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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12
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Herbst-Robinson KJ, Liu L, James M, Yao Y, Xie SX, Brunden KR. Inflammatory Eicosanoids Increase Amyloid Precursor Protein Expression via Activation of Multiple Neuronal Receptors. Sci Rep 2015; 5:18286. [PMID: 26672557 PMCID: PMC4682150 DOI: 10.1038/srep18286] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 10/26/2015] [Indexed: 01/27/2023] Open
Abstract
Senile plaques comprised of Aβ peptides are a hallmark of Alzheimer's disease (AD) brain, as are activated glia that release inflammatory molecules, including eicosanoids. Previous studies have demonstrated that amyloid precursor protein (APP) and Aβ levels can be increased through activation of thromboxane A2-prostanoid (TP) receptors on neurons. We demonstrate that TP receptor regulation of APP expression depends on Gαq-signaling and conventional protein kinase C isoforms. Importantly, we discovered that Gαq-linked prostaglandin E2 and leukotriene D4 receptors also regulate APP expression. Prostaglandin E2 and thromboxane A2, as well as total APP levels, were found to be elevated in the brains of aged 5XFAD transgenic mice harboring Aβ plaques and activated glia, suggesting that increased APP expression resulted from eicosanoid binding to Gαq-linked neuronal receptors. Notably, inhibition of eicosanoid synthesis significantly lowered brain APP protein levels in aged 5XFAD mice. These results provide new insights into potential AD therapeutic strategies.
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Affiliation(s)
- Katie J. Herbst-Robinson
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Li Liu
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Michael James
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Yuemang Yao
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Sharon X. Xie
- Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Kurt R. Brunden
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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Dong H, Wang S, Zeng Z, Li F, Montalvo-Ortiz J, Tucker C, Akhtar S, Shi J, Meltzer HY, Rice KC, Csernansky JG. Effects of corticotrophin-releasing factor receptor 1 antagonists on amyloid-β and behavior in Tg2576 mice. Psychopharmacology (Berl) 2014; 231:4711-22. [PMID: 24862368 PMCID: PMC4233002 DOI: 10.1007/s00213-014-3629-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 05/14/2014] [Indexed: 12/11/2022]
Abstract
RATIONALE Previous studies indicate that psychosocial stressors could accelerate amyloid-β (Aβ) levels and accelerate plaque deposition in mouse models of Alzheimer disease (AD). Stressors enhanced the release of corticotrophin-releasing factor (CRF), and exogenous CRF administration mimicked the effects of stress on Aβ levels in mouse models of AD. However, whether CRF receptor 1 (CRF1) antagonists could influence the stress-induced acceleration of an AD-like process in mouse models has not been well studied. OBJECTIVE We sought to examine whether CRF1 antagonists inhibit the effects of isolation stress on tissue Aβ levels, Aβ plaque deposition, and behaviors related to anxiety and memory in Tg2576 mice, and to investigate the molecular mechanism underlying such effects. METHODS Cohorts of Tg2576 mouse pups were isolated or group-housed at 21 days of age, and then the subgroups of these cohorts received daily intraperitoneal injections of the CRF1 antagonists, antalarmin or R121919 (5, 10, and 20 mg/kg), or vehicle for 1 week. Other cohorts of Tg2576 mouse pups were isolated or group-housed at 21 days of age, and then at 4 months of age, subgroups of these mice were administered antalarmin (20 mg/kg) or vehicle in their drinking water for 6 months. Finally, cultured primary hippocampal neurons from regular Tg2576 pups (P0) were incubated with CRF (0.1, 1, and 10 nM), antalarmin (100 nM) or H-89 (1 μM) for 48 h. Brain tissues or cultured neurons were collected for histological and biochemical analyses, and behavioral measures were collected in the cohorts of mice that were chronically stressed. RESULTS Administration of antalarmin at 20 mg/kg dose for 1 week significantly reduced Aβ1-42 levels in isolation stressed mice. Administration of antalarmin for 6 months significantly decreased plasma corticosterone levels, tissue Aβ1-42 levels, and Aβ plaque deposition in the brain and blocked the effects of isolation stress on behaviors related to anxiety and memory. Finally, incubation of neurons with 100 nM antalarmin inhibited the ability of 10 nM CRF to increase Aβ1-42 levels and protein kinase A IIβ expression. The effect of CRF1 on Aβ1-42 levels was also diminished by treatment with H-89, a c-AMP/PKA inhibitor. CONCLUSIONS These results suggest that CRF1 antagonists can slow an AD-like process in Tg2576 mice and that the c-AMP/PKA signaling pathway may be involved in this effect.
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Affiliation(s)
- Hongxin Dong
- Department of Psychiatry and Behavioral Sciences, Feinberg School Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL, 60611, USA,
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14
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Revett TJ, Baker GB, Jhamandas J, Kar S. Glutamate system, amyloid ß peptides and tau protein: functional interrelationships and relevance to Alzheimer disease pathology. J Psychiatry Neurosci 2013; 38:6-23. [PMID: 22894822 PMCID: PMC3529221 DOI: 10.1503/jpn.110190] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alzheimer disease is the most prevalent form of dementia globally and is characterized premortem by a gradual memory loss and deterioration of higher cognitive functions and postmortem by neuritic plaques containing amyloid ß peptide and neurofibrillary tangles containing phospho-tau protein. Glutamate is the most abundant neurotransmitter in the brain and is essential to memory formation through processes such as long-term potentiation and so might be pivotal to Alzheimer disease progression. This review discusses how the glutamatergic system is impaired in Alzheimer disease and how interactions of amyloid ß and glutamate influence synaptic function, tau phosphorylation and neurodegeneration. Interestingly, glutamate not only influences amyloid ß production, but also amyloid ß can alter the levels of glutamate at the synapse, indicating that small changes in the concentrations of both molecules could influence Alzheimer disease progression. Finally, we describe how the glutamate receptor antagonist, memantine, has been used in the treatment of individuals with Alzheimer disease and discuss its effectiveness.
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Affiliation(s)
| | | | | | - Satyabrata Kar
- Correspondence to: S. Kar, Centre for Prions and Protein Folding Diseases, Departments of Medicine (Neurology) and Psychiatry, University of Alberta, Edmonton AB T6G 2M8;
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15
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Dong H, Murphy KM, Meng L, Montalvo-Ortiz J, Zeng Z, Kolber BJ, Zhang S, Muglia LJ, Csernansky JG. Corticotrophin releasing factor accelerates neuropathology and cognitive decline in a mouse model of Alzheimer's disease. J Alzheimers Dis 2012; 28:579-92. [PMID: 22045495 DOI: 10.3233/jad-2011-111328] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chronic stress has been suggested to influence the pathogenesis of Alzheimer's disease (AD); however, the mechanism underlying this influence remains unknown. In this study, we created a triple transgenic mouse model that overexpresses corticotrophin-releasing factor (CRF) and human amyloid-β protein precursor (AβPP), to investigate whether increases in the expression of CRF can mimic the effects of stress on amyloid metabolism and the neurodegeneration. Tg2576 mice that overexpresses human AβPP gene were crossbreed with Tetop-CRF (CRF) mice and CaMKII-tTA (tTA) mice to create a novel triple transgenic mouse model that conditioned overexpresses CRF in forebrain and overexpresses human AβPP (called AβPP+/CRF+/tTA+, or TT mice). Then we evaluated serial neuro-anatomical and behavioral phenotypes on TT mice using histological, biochemical, and behavioral assays. TT mice showed a Cushingoid-like phenotype starting at 3 months of age. At 6 months of age, these mice demonstrated increases in tissue-soluble amyloid-β (Aβ) and Aβ plaques in the cortex and hippocampus, as compared to control mice. Moreover, TT mice characterized substantial decreases in dendritic branching and dendritic spine density in pyramidal neurons in layer 4 of the frontal cortex and CA1 of the hippocampus. Finally, TT mice showed significantly impaired working memory and contextual memory, with a modest increase in anxiety-like behavior. Our results suggested genetic increases in the brain of CRF expression mimicked chronic stress on the effects of amyloid deposition, neurodegeneration, and behavioral deficits. The novel transgenic mouse model will provide a unique tool to further investigate the mechanisms between stress and AD.
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Affiliation(s)
- Hongxin Dong
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Yi P, Schrott L, Castor TP, Alexander JS. Bryostatin-1 vs. TPPB: dose-dependent APP processing and PKC-α, -δ, and -ε isoform activation in SH-SY5Y neuronal cells. J Mol Neurosci 2012; 48:234-44. [PMID: 22700373 PMCID: PMC3413820 DOI: 10.1007/s12031-012-9816-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/16/2012] [Indexed: 01/17/2023]
Abstract
Activation of the α-secretase processing pathway of amyloid precursor protein (APP) is recognized as an important mechanism which diverts APP processing from production of beta-amyloid (Aβ) to non toxic sAPPα, decreasing Alzheimer’s disease (AD) plaque formation and AD-associated cognitive deficits. Two potent classes of PKC modulators can activate the α-secretase pathway, the benzo/indolactams and bryostatin/bryologues. While both modulate PKC-dependent APP processing, no direct comparisons of their relative pharmacological potencies have been accomplished which could assist in the development of AD therapies. In this study, we measured the activation of α-secretase APP processing and PKC-α, -δ, and -ε induced by the benzolactam-APP modulator TPPB and bryostatin-1 in the neuroblastoma cell line SH-SY5Y which expresses APP and α- and β-secretase processing mechanisms. Bryostatin-1 produced a more rapid, potent, and sustained activation of α-secretase APP processing than TPPB and selectively activated PKC-δ and PKC-ε. Although TPPB also activated α-secretase, its potency was approximately 10- to 100-fold lower, possibly reflecting lower PKC-δ and -ε activation. Because bryostatin-1 is a highly potent PKC-δ and -ε activator which activates α-secretase APP processing, further characterization of bryostatin-1/bryologues may help refine their use as important tools for the clinical management of AD.
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Affiliation(s)
- P. Yi
- Department of Molecular and Cellular Physiology, LSU Health, 1501 Kings Hwy, Shreveport, LA 71130 USA
| | - L. Schrott
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health, 1501 Kings Hwy, Shreveport, LA 71130 USA
| | | | - J. S. Alexander
- Department of Molecular and Cellular Physiology, LSU Health, 1501 Kings Hwy, Shreveport, LA 71130 USA
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Himeno E, Ohyagi Y, Ma L, Nakamura N, Miyoshi K, Sakae N, Motomura K, Soejima N, Yamasaki R, Hashimoto T, Tabira T, M. LaFerla F, Kira JI. Apomorphine treatment in Alzheimer mice promoting amyloid-β degradation. Ann Neurol 2011; 69:248-56. [DOI: 10.1002/ana.22319] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Thathiah A, De Strooper B. The role of G protein-coupled receptors in the pathology of Alzheimer's disease. Nat Rev Neurosci 2011; 12:73-87. [DOI: 10.1038/nrn2977] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Kim T, Hinton DJ, Choi DS. Protein kinase C-regulated aβ production and clearance. Int J Alzheimers Dis 2011; 2011:857368. [PMID: 21274428 PMCID: PMC3026967 DOI: 10.4061/2011/857368] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 12/03/2010] [Accepted: 12/13/2010] [Indexed: 11/20/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia among the elderly population. AD, which is characterized as a disease of cognitive deficits, is mainly associated with an increase of amyloid β-peptide (Aβ) in the brain. A growing body of recent studies suggests that protein kinase C (PKC) promotes the production of the secretory form of amyloid precursor protein (sAPPα) via the activation of α-secretase activity, which reduces the accumulation of pathogenic Aβ levels in the brain. Moreover, activation of PKCα and mitogen-activated protein kinase (MAPK) is known to increase sAPPα. A novel type of PKC, PKCε, activates the Aβ degrading activity of endothelin converting enzyme type 1 (ECE-1), which might be mediated via the MAPK pathway as well. Furthermore, dysregulation of PKC-MAPK signaling is known to increase Aβ levels in the brain, which results in AD phenotypes. Here, we discuss roles of PKC in Aβ production and clearance and its implication in AD.
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Affiliation(s)
- Taehyun Kim
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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21
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Peng Y, Hu Y, Xu S, Feng N, Wang L, Wang X. l-3-n-Butylphthalide regulates amyloid precursor protein processing by PKC and MAPK pathways in SK-N-SH cells over-expressing wild type human APP695. Neurosci Lett 2011; 487:211-6. [DOI: 10.1016/j.neulet.2010.10.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 09/27/2010] [Accepted: 10/11/2010] [Indexed: 11/27/2022]
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22
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Vieira SI, Rebelo S, Esselmann H, Wiltfang J, Lah J, Lane R, Small SA, Gandy S, da Cruz E Silva EF, da Cruz E Silva OA. Retrieval of the Alzheimer's amyloid precursor protein from the endosome to the TGN is S655 phosphorylation state-dependent and retromer-mediated. Mol Neurodegener 2010; 5:40. [PMID: 20937087 PMCID: PMC2994555 DOI: 10.1186/1750-1326-5-40] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 10/11/2010] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Retrograde transport of several transmembrane proteins from endosomes to the trans-Golgi network (TGN) occurs via Rab 5-containing endosomes, mediated by clathrin and the recently characterized retromer complex. This complex and one of its putative sorting receptor components, SorLA, were reported to be associated to late onset Alzheimer's disease (AD). The pathogenesis of this neurodegenerative disorder is still elusive, although accumulation of amyloidogenic Abeta is a hallmark. This peptide is generated from the sucessive β- and γ- secretase proteolysis of the Alzheimer's amyloid precursor protein (APP), events which are associated with endocytic pathway compartments. Therefore, APP targeting and time of residence in endosomes would be predicted to modulate Abeta levels. However, the formation of an APP- and retromer-containing protein complex with potential functions in retrieval of APP from the endosome to the TGN had, to date, not been demonstrated directly. Further, the motif(s) in APP that regulate its sorting to the TGN have not been characterized. RESULTS Through the use of APP-GFP constructs, we show that APP containing endocytic vesicles targeted for the TGN, are also immunoreactive for clathrin-, Rab 5- and VPS35. Further, they frequently generate protruding tubules near the TGN, supporting an association with a retromer-mediated pathway. Importantly, we show for the first time, that mimicking APP phosphorylation at S655, within the APP 653YTSI656 basolateral motif, enhances APP retrieval via a retromer-mediated process. The phosphomimetic APP S655E displays decreased APP lysosomal targeting, enhanced mature half-life, and decreased tendency towards Abeta production. VPS35 downregulation impairs the phosphorylation dependent APP retrieval to the TGN, and decreases APP half-life. CONCLUSIONS We reported for the first time the importance of APP phosphorylation on S655 in regulating its retromer-mediated sorting to the TGN or lysosomes. Significantly, the data are consistent with known interactions involving the retromer, SorLA and APP. Further, these findings add to our understanding of APP targeting and potentially contribute to our knowledge of sporadic AD pathogenesis representing putative new targets for AD therapeutic strategies.
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Affiliation(s)
- Sandra I Vieira
- Neuroscience, Centre for Cell Biology, Health Sciences Department SACS, University of Aveiro, Aveiro 3810, Portugal.
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Giorgi C, Agnoletto C, Baldini C, Bononi A, Bonora M, Marchi S, Missiroli S, Patergnani S, Poletti F, Rimessi A, Zavan B, Pinton P. Redox control of protein kinase C: cell- and disease-specific aspects. Antioxid Redox Signal 2010; 13:1051-85. [PMID: 20136499 DOI: 10.1089/ars.2009.2825] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hormones, growth factors, electrical stimulation, and cell-cell interactions regulate numerous cellular processes by altering the levels of second messengers, thus influencing biochemical reactions inside the cells. The Protein Kinase C family (PKCs) is a group of serine/threonine kinases that are dependent on calcium (Ca(2+)), diacylglycerol, and phospholipids. Signaling pathways that induce variations on the levels of PKC activators have been implicated in the regulation of diverse cellular functions and, in turn, PKCs are key regulators of a plethora of cellular processes, including proliferation, differentiation, and tumorigenesis. Importantly, PKCs contain regions, both in the N-terminal regulatory domain and in the C-terminal catalytic domain, that are susceptible to redox modifications. In several pathophysiological conditions when the balance between oxidants, antioxidants, and alkylants is compromised, cells undergo redox stress. PKCs are cell-signaling proteins that are particularly sensitive to redox stress because modification of their redox-sensitive regions interferes with their activity and, thus, with their biological effects. In this review, we summarize the involvement of PKCs in health and disease and the importance of redox signaling in the regulation of this family of kinases.
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Affiliation(s)
- Carlotta Giorgi
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation (ICSI), BioPharmaNet, University of Ferrara, Ferrara, Italy
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Nelson TJ, Cui C, Luo Y, Alkon DL. Reduction of beta-amyloid levels by novel protein kinase C(epsilon) activators. J Biol Chem 2009; 284:34514-21. [PMID: 19850930 PMCID: PMC2787312 DOI: 10.1074/jbc.m109.016683] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 10/20/2009] [Indexed: 12/12/2022] Open
Abstract
Isoform-specific protein kinase C (PKC) activators may be useful as therapeutic agents for the treatment of Alzheimer disease. Three new epsilon-specific PKC activators, made by cyclopropanation of polyunsaturated fatty acids, have been developed. These activators, AA-CP4, EPA-CP5, and DHA-CP6, activate PKCepsilon in a dose-dependent manner. Unlike PKC activators that bind to the 1,2-diacylglycerol-binding site, such as bryostatin and phorbol esters, which produce prolonged down-regulation, the new activators produced sustained activation of PKC. When applied to cells expressing human APPSwe/PS1delta, which produce large quantities of beta-amyloid peptide (Abeta), DCP-LA and DHA-CP6 reduced the intracellular and secreted levels of Abeta by 60-70%. In contrast to the marked activation of alpha-secretase produced by PKC activators in fibroblasts, the PKC activators produced only a moderate and transient activation of alpha-secretase in neuronal cells. However, they activated endothelin-converting enzyme to 180% of control levels, suggesting that the Abeta-lowering ability of these PKCepsilon activators is caused by increasing the rate of Abeta degradation by endothelin-converting enzyme and not by activating nonamyloidogenic amyloid precursor protein metabolism.
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Affiliation(s)
- Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26506, USA.
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S655 phosphorylation enhances APP secretory traffic. Mol Cell Biochem 2009; 328:145-54. [DOI: 10.1007/s11010-009-0084-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 03/11/2009] [Indexed: 10/20/2022]
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Henriques AG, Vieira SI, da Cruz e Silva EF, da Cruz e Silva OAB. Alphabeta hinders nuclear targeting of AICD and Fe65 in primary neuronal cultures. J Mol Neurosci 2009; 39:248-55. [PMID: 19340611 PMCID: PMC2744832 DOI: 10.1007/s12031-009-9192-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Accepted: 01/19/2009] [Indexed: 11/28/2022]
Abstract
The intracellular domain of the Alzheimer's amyloid precursor protein (AICD) has been described as an important player in the transactivation of specific genes. It results from proteolytic processing of the Alzheimer's amyloid precursor protein (APP), as does the neurotoxic Abeta peptide. Although normally produced in cells, Abeta is typically considered to be a neurotoxic peptide, causing devastating effects. By exposing primary neuronal cultures to relatively low Abeta concentrations, this peptide was shown to affect APP processing. Our findings indicate that APP C-terminal fragments are increased with concomitant reduction in the expression levels of APP itself. AICD nuclear immunoreactivity detected under control conditions was dramatically reduced in response to Abeta exposure. Additionally, intracellular protein levels of Fe65 and GSK3 were also decreased in response to Abeta. APP nuclear signaling is altered by Abeta, affecting not only AICD production but also its nuclear translocation and complex formation with Fe65. In effect, Abeta can trigger a physiological negative feedback mechanism that modulates its own production.
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Affiliation(s)
- A G Henriques
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Campus de Santiago, Aveiro, Portugal
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Nelson TJ, Alkon DL. Neuroprotective versus tumorigenic protein kinase C activators. Trends Biochem Sci 2009; 34:136-45. [PMID: 19233655 DOI: 10.1016/j.tibs.2008.11.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
Abstract
Protein kinase C (PKC) activators possess potent neurotrophic and neuroprotective activity, thus indicating potential applications in treating neurodegenerative diseases, stroke and traumatic brain injury. Although some activators, such as bryostatin and gnidimacrin, have been tested as antitumor agents, others, such as phorbol esters, are potent tumor promoters. All PKC activators downregulate PKC at high concentrations and long application times. However, tumorigenic activators downregulate certain PKC isozymes, especially PKCdelta, more strongly. Tumorigenic activators possess unique structural features that could account for this difference. At concentrations that minimize PKC downregulation, PKC activators can improve long-term memory, reduce beta-amyloid levels, induce synaptogenesis, promote neuronal repair and inhibit cell proliferation. Intermittent, low concentrations of structurally specific, non-tumorigenic PKC activators, therefore, could offer therapeutic benefit for a variety of neurologic disorders.
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Affiliation(s)
- T J Nelson
- Blanchette Rockefeller Neurosciences Institute, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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