1
|
Nik Akhtar S, Bunner WP, Brennan E, Lu Q, Szatmari EM. Crosstalk between the Rho and Rab family of small GTPases in neurodegenerative disorders. Front Cell Neurosci 2023; 17:1084769. [PMID: 36779014 PMCID: PMC9911442 DOI: 10.3389/fncel.2023.1084769] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/06/2023] [Indexed: 01/28/2023] Open
Abstract
Neurodegeneration is associated with defects in cytoskeletal dynamics and dysfunctions of the vesicular trafficking and sorting systems. In the last few decades, studies have demonstrated that the key regulators of cytoskeletal dynamics are proteins from the Rho family GTPases, meanwhile, the central hub for vesicle sorting and transport between target membranes is the Rab family of GTPases. In this regard, the role of Rho and Rab GTPases in the induction and maintenance of distinct functional and morphological neuronal domains (such as dendrites and axons) has been extensively studied. Several members belonging to these two families of proteins have been associated with many neurodegenerative disorders ranging from dementia to motor neuron degeneration. In this analysis, we attempt to present a brief review of the potential crosstalk between the Rab and Rho family members in neurodegenerative pathologies such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington disease, and amyotrophic lateral sclerosis (ALS).
Collapse
Affiliation(s)
- Shayan Nik Akhtar
- The Harriet and John Wooten Laboratory for Alzheimer’s and Neurodegenerative Diseases Research, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Wyatt P. Bunner
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States
| | - Elizabeth Brennan
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States
| | - Qun Lu
- The Harriet and John Wooten Laboratory for Alzheimer’s and Neurodegenerative Diseases Research, Brody School of Medicine, East Carolina University, Greenville, NC, United States,*Correspondence: Erzsebet M. Szatmari Qun Lu
| | - Erzsebet M. Szatmari
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States,*Correspondence: Erzsebet M. Szatmari Qun Lu
| |
Collapse
|
2
|
Jordan KL, Koss DJ, Outeiro TF, Giorgini F. Therapeutic Targeting of Rab GTPases: Relevance for Alzheimer’s Disease. Biomedicines 2022; 10:biomedicines10051141. [PMID: 35625878 PMCID: PMC9138223 DOI: 10.3390/biomedicines10051141] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/22/2022] [Accepted: 04/18/2022] [Indexed: 11/16/2022] Open
Abstract
Rab GTPases (Rabs) are small proteins that play crucial roles in vesicle transport and membrane trafficking. Owing to their widespread functions in several steps of vesicle trafficking, Rabs have been implicated in the pathogenesis of several disorders, including cancer, diabetes, and multiple neurodegenerative diseases. As treatments for neurodegenerative conditions are currently rather limited, the identification and validation of novel therapeutic targets, such as Rabs, is of great importance. This review summarises proof-of-concept studies, demonstrating that modulation of Rab GTPases in the context of Alzheimer’s disease (AD) can ameliorate disease-related phenotypes, and provides an overview of the current state of the art for the pharmacological targeting of Rabs. Finally, we also discuss the barriers and challenges of therapeutically targeting these small proteins in humans, especially in the context of AD.
Collapse
Affiliation(s)
- Kate L. Jordan
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK;
| | - David J. Koss
- Faculty of Medical Sciences, Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK; (D.J.K.); (T.F.O.)
| | - Tiago F. Outeiro
- Faculty of Medical Sciences, Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK; (D.J.K.); (T.F.O.)
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany
- Max Planck Institute for Natural Sciences, 37075 Göttingen, Germany
- Scientific Employee with a Honorary Contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), 37075 Göttingen, Germany
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK;
- Correspondence:
| |
Collapse
|
3
|
Leite DM, Seifi M, Ruiz-Perez L, Nguemo F, Plomann M, Swinny JD, Battaglia G. Syndapin-2 mediated transcytosis of amyloid-ß across the blood-brain barrier. Brain Commun 2022; 4:fcac039. [PMID: 35233527 PMCID: PMC8882007 DOI: 10.1093/braincomms/fcac039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 10/31/2021] [Accepted: 02/15/2022] [Indexed: 11/14/2022] Open
Abstract
A deficient transport of amyloid-β across the blood–brain barrier, and its diminished clearance from the brain, contribute to neurodegenerative and vascular pathologies, such as Alzheimer’s disease and cerebral amyloid angiopathy, respectively. At the blood–brain barrier, amyloid-β efflux transport is associated with the low-density lipoprotein receptor-related protein 1. However, the precise mechanisms governing amyloid-β transport across the blood–brain barrier, in health and disease, remain to be fully understood. Recent evidence indicates that the low-density lipoprotein receptor-related protein 1 transcytosis occurs through a tubulation-mediated mechanism stabilized by syndapin-2. Here, we show that syndapin-2 is associated with amyloid-β clearance via low-density lipoprotein receptor-related protein 1 across the blood–brain barrier. We further demonstrate that risk factors for Alzheimer’s disease, amyloid-β expression and ageing, are associated with a decline in the native expression of syndapin-2 within the brain endothelium. Our data reveals that syndapin-2-mediated pathway, and its balance with the endosomal sorting, are important for amyloid-β clearance proposing a measure to evaluate Alzheimer’s disease and ageing, as well as a target for counteracting amyloid-β build-up. Moreover, we provide evidence for the impact of the avidity of amyloid-β assemblies in their trafficking across the brain endothelium and in low-density lipoprotein receptor-related protein 1 expression levels, which may affect the overall clearance of amyloid-β across the blood–brain barrier.
Collapse
Affiliation(s)
- Diana M. Leite
- Department of Chemistry, University College London, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Mohsen Seifi
- Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, Leicester, United Kingdom
| | - Lorena Ruiz-Perez
- Department of Chemistry, University College London, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Filomain Nguemo
- Institute for Neurophysiology, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Markus Plomann
- Institute of Biochemistry, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Jerome D. Swinny
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
| | - Giuseppe Battaglia
- Department of Chemistry, University College London, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
| |
Collapse
|
4
|
Deaton CA, Johnson GVW. Presenilin 1 Regulates Membrane Homeostatic Pathways that are Dysregulated in Alzheimer's Disease. J Alzheimers Dis 2021; 77:961-977. [PMID: 32804090 DOI: 10.3233/jad-200598] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations in the PSEN1 gene, encoding presenilin 1 (PS1), are the most common cause of familial Alzheimer's disease (fAD). Since the first mutations in the PSEN1 gene were discovered more than 25 years ago, many postulated functions of PS1 have been investigated. The majority of earlier studies focused on its role as the catalytic component of the γ-secretase complex, which in concert with β site amyloid precursor protein cleaving enzyme 1 (BACE1), mediates the formation of Aβ from amyloid-β protein precursor (AβPP). Though mutant PS1 was originally considered to cause AD by promoting Aβ pathology through its protease function, it is now becoming clear that PS1 is a multifunctional protein involved in regulating membrane dynamics and protein trafficking. Therefore, through loss of these abilities, mutant PS1 has the potential to impair numerous cellular functions such as calcium flux, organization of proteins in different compartments, and protein turnover via vacuolar metabolism. Impaired calcium signaling, vacuolar dysfunction, mitochondrial dysfunction, and increased ER stress, among other related membrane-dependent disturbances, have been considered critical to the development and progression of AD. Given that PS1 plays a key regulatory role in all these processes, this review will describe the role of PS1 in different cellular compartments and provide an integrated view of how PS1 dysregulation (due to mutations or other causes) could result in impairment of various cellular processes and result in a "multi-hit", integrated pathological outcome that could contribute to the etiology of AD.
Collapse
Affiliation(s)
- Carol A Deaton
- Cell Biology of Disease Program and the Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Gail V W Johnson
- Cell Biology of Disease Program and the Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, USA
| |
Collapse
|
5
|
Waschbüsch D, Khan AR. Phosphorylation of Rab GTPases in the regulation of membrane trafficking. Traffic 2020; 21:712-719. [PMID: 32969543 PMCID: PMC7756361 DOI: 10.1111/tra.12765] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/17/2020] [Accepted: 09/17/2020] [Indexed: 12/15/2022]
Abstract
Rab GTPases are master regulators of membrane trafficking in eukaryotic cells. Phosphorylation of Rab GTPases was characterized in the 1990s and there have been intermittent reports of its relevance to Rab functions. Phosphorylation as a regulatory mechanism has gained prominence through the identification of Rabs as physiological substrates of leucine‐rich repeat kinase 2 (LRRK2). LRRK2 is a Ser/Thr kinase that is associated with inherited and sporadic forms of Parkinson disease. In recent years, numerous kinases and their associated signaling pathways have been identified that lead to phosphorylation of Rabs. These emerging studies suggest that serine/threonine and tyrosine phosphorylation of Rabs may be a widespread and under‐appreciated mechanism for controlling their membrane trafficking functions. Here we survey current knowledge of Rab phosphorylation and discuss models for how this post‐translational mechanism exerts control of membrane trafficking.
Collapse
Affiliation(s)
- Dieter Waschbüsch
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
| | - Amir R Khan
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland.,Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| |
Collapse
|
6
|
Evolutionary History of Alzheimer Disease-Causing Protein Family Presenilins with Pathological Implications. J Mol Evol 2020; 88:674-688. [DOI: 10.1007/s00239-020-09966-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 09/22/2020] [Indexed: 12/14/2022]
|
7
|
Abstract
Defects in membrane trafficking are hallmarks of neurodegeneration. Rab GTPases are key regulators of membrane trafficking. Alterations of Rab GTPases, or the membrane compartments they regulate, are associated with virtually all neuronal activities in health and disease. The observation that many Rab GTPases are associated with neurodegeneration has proven a challenge in the quest for cause and effect. Neurodegeneration can be a direct consequence of a defect in membrane trafficking. Alternatively, changes in membrane trafficking may be secondary consequences or cellular responses. The secondary consequences and cellular responses, in turn, may protect, represent inconsequential correlates or function as drivers of pathology. Here, we attempt to disentangle the different roles of membrane trafficking in neurodegeneration by focusing on selected associations with Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and selected neuropathies. We provide an overview of current knowledge on Rab GTPase functions in neurons and review the associations of Rab GTPases with neurodegeneration with respect to the following classifications: primary cause, secondary cause driving pathology or secondary correlate. This analysis is devised to aid the interpretation of frequently observed membrane trafficking defects in neurodegeneration and facilitate the identification of true causes of pathology.
Collapse
|
8
|
Rab GTPases: Switching to Human Diseases. Cells 2019; 8:cells8080909. [PMID: 31426400 PMCID: PMC6721686 DOI: 10.3390/cells8080909] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 02/07/2023] Open
Abstract
Rab proteins compose the largest family of small GTPases and control the different steps of intracellular membrane traffic. More recently, they have been shown to also regulate cell signaling, division, survival, and migration. The regulation of these processes generally occurs through recruitment of effectors and regulatory proteins, which control the association of Rab proteins to membranes and their activation state. Alterations in Rab proteins and their effectors are associated with multiple human diseases, including neurodegeneration, cancer, and infections. This review provides an overview of how the dysregulation of Rab-mediated functions and membrane trafficking contributes to these disorders. Understanding the altered dynamics of Rabs and intracellular transport defects might thus shed new light on potential therapeutic strategies.
Collapse
|
9
|
Pająk B, Kania E, Gołaszewska A, Orzechowski A. Preliminary Study on Clusterin Protein (sCLU) Expression in PC-12 Cells Overexpressing Wild-Type and Mutated (Swedish) AβPP genes Affected by Non-Steroid Isoprenoids and Water-Soluble Cholesterol. Int J Mol Sci 2019; 20:E1481. [PMID: 30909654 PMCID: PMC6470582 DOI: 10.3390/ijms20061481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/04/2019] [Accepted: 03/18/2019] [Indexed: 02/07/2023] Open
Abstract
In this study we attempted to verify the hypothesis that the mevalonate pathway affects amyloid beta precursor protein (AβPP) processing and regulates clusterin protein levels. AβPP expression was monitored by green fluorescence (FL) and Western blot (WB). WB showed soluble amyloid protein precursor alpha (sAβPPα) presence in AβPP-wt cells and Aβ expression in AβPP-sw cells. Nerve growth factor (NGF)-differentiated rat neuronal pheochromocytoma PC-12 cells were untreated/treated with statins alone or together with non-sterol isoprenoids. Co-treatment with mevalonate, dolichol, ubiquinol, farnesol, geranylgeraniol, or water-soluble cholesterol demonstrated statin-dependent neurotoxicity resulted from the attenuated activity of mevalonate pathway rather than lower cholesterol level. Atorvastatin (50 μM) or simvastatin (50 μM) as well as cholesterol chelator methyl-β-cyclodextrin (0.2 mM) diminished cell viability (p < 0.05) and clusterin levels. Interestingly, co-treatment with mevalonate, dolichol, ubiquinol, farnesol, geranylgeraniol, or water-soluble cholesterol stimulated (p < 0.05) clusterin expression. Effects of non-sterol isoprenoids, but not water soluble cholesterol (Chol-PEG), were the most significant in mock-transfected cells. Geranylgeraniol (GGOH) overcame atorvastatin (ATR)-dependent cytotoxicity. This effect does not seem to be dependent on clusterin, as its level became lower after GGOH. The novelty of these findings is that they show that the mevalonate (MEV) pathway rather than cholesterol itself plays an important role in clusterin expression levels. In mock-transfected, rather than in AβPP-overexpressing cells, GGOH/farnesol (FOH) exerted a protective effect. Thus, protein prenylation with GGOH/FOH might play substantial role in neuronal cell survival.
Collapse
Affiliation(s)
- Beata Pająk
- Independent Laboratory of Genetics and Molecular Biology, Kaczkowski Military Institute of Hygiene and Epidemiology, Kozielska 4, 01-163 Warsaw, Poland.
| | - Elżbieta Kania
- Tumor Cell Death Laboratory, Cancer Research UK, Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK.
| | - Anita Gołaszewska
- Department of Neuroendocrinology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland.
- Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences ⁻ SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland.
| | - Arkadiusz Orzechowski
- Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences ⁻ SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland.
| |
Collapse
|
10
|
Zhang X, Huang TY, Yancey J, Luo H, Zhang YW. Role of Rab GTPases in Alzheimer's Disease. ACS Chem Neurosci 2019; 10:828-838. [PMID: 30261139 DOI: 10.1021/acschemneuro.8b00387] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) comprises two major pathological hallmarks: extraneuronal deposition of β-amyloid (Aβ) peptides ("senile plaques") and intraneuronal aggregation of the microtubule-associated protein tau ("neurofibrillary tangles"). Aβ is derived from sequential cleavage of the β-amyloid precursor protein by β- and γ-secretases, while aggregated tau is hyperphosphorylated in AD. Mounting evidence suggests that dysregulated trafficking of these AD-related proteins contributes to AD pathogenesis. Rab proteins are small GTPases that function as master regulators of vesicular transport and membrane trafficking. Multiple Rab GTPases have been implicated in AD-related protein trafficking, and their expression has been observed to be altered in postmortem AD brain. Here we review current implicated roles of Rab GTPase dysregulation in AD pathogenesis. Further elucidation of the pathophysiological role of Rab GTPases will likely reveal novel targets for AD therapeutics.
Collapse
Affiliation(s)
- Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| | - Timothy Y. Huang
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Joel Yancey
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Hong Luo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| | - Yun-wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| |
Collapse
|
11
|
Molecular Insights into the Roles of Rab Proteins in Intracellular Dynamics and Neurodegenerative Diseases. Neuromolecular Med 2018; 20:18-36. [PMID: 29423895 DOI: 10.1007/s12017-018-8479-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/27/2018] [Indexed: 02/01/2023]
Abstract
In eukaryotes, the cellular functions are segregated to membrane-bound organelles. This inherently requires sorting of metabolites to membrane-limited locations. Sorting the metabolites from ribosomes to various organelles along the intracellular trafficking pathways involves several integral cellular processes, including an energy-dependent step, in which the sorting of metabolites between organelles is catalyzed by membrane-anchoring protein Rab-GTPases (Rab). They contribute to relaying the switching of the secretory proteins between hydrophobic and hydrophilic environments. The intracellular trafficking routes include exocytic and endocytic pathways. In these pathways, numerous Rab-GTPases are participating in discrete shuttling of cargoes. Long-distance trafficking of cargoes is essential for neuronal functions, and Rabs are critical for these functions, including the transport of membranes and essential proteins for the development of axons and neurites. Rabs are also the key players in exocytosis of neurotransmitters and recycling of neurotransmitter receptors. Thus, Rabs are critical for maintaining neuronal communication, as well as for normal cellular physiology. Therefore, cellular defects of Rab components involved in neural functions, which severely affect normal brain functions, can produce neurological complications, including several neurodegenerative diseases. In this review, we provide a comprehensive overview of the current understanding of the molecular signaling pathways of Rab proteins and the impact of their defects on different neurodegenerative diseases. The insights gathered into the dynamics of Rabs that are described in this review provide new avenues for developing effective treatments for neurodegenerative diseases-associated with Rab defects.
Collapse
|
12
|
Poulsen ET, Iannuzzi F, Rasmussen HF, Maier TJ, Enghild JJ, Jørgensen AL, Matrone C. An Aberrant Phosphorylation of Amyloid Precursor Protein Tyrosine Regulates Its Trafficking and the Binding to the Clathrin Endocytic Complex in Neural Stem Cells of Alzheimer's Disease Patients. Front Mol Neurosci 2017; 10:59. [PMID: 28360834 PMCID: PMC5350151 DOI: 10.3389/fnmol.2017.00059] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 02/21/2017] [Indexed: 11/15/2022] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and is likely caused by defective amyloid precursor protein (APP) trafficking and processing in neurons leading to amyloid plaques containing the amyloid-β (Aβ) APP peptide byproducts. Understanding how APP is targeted to selected destinations inside neurons and identifying the mechanisms responsible for the generation of Aβ are thus the keys for the advancement of new therapies. We previously developed a mouse model with a mutation at tyrosine (Tyr) 682 in the C-terminus of APP. This residue is needed for APP to bind to the coating protein Clathrin and to the Clathrin adaptor protein AP2 as well as for the correct APP trafficking and sorting in neurons. By extending these findings to humans, we found that APP binding to Clathrin is decreased in neural stem cells from AD sufferers. Increased APP Tyr phosphorylation alters APP trafficking in AD neurons and it is associated to Fyn Tyr kinase activation. We show that compounds affecting Tyr kinase activity and counteracting defects in AD neurons can control APP location and compartmentalization. APP Tyr phosphorylation is thus a potential therapeutic target for AD.
Collapse
Affiliation(s)
- Ebbe T. Poulsen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
| | | | | | - Thorsten J. Maier
- Institute of Biomedicine, Aarhus UniversityAarhus, Denmark
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Goethe UniversityFrankfurt, Germany
| | - Jan J. Enghild
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
| | | | | |
Collapse
|
13
|
The Role of Presenilin in Protein Trafficking and Degradation—Implications for Metal Homeostasis. J Mol Neurosci 2016; 60:289-297. [DOI: 10.1007/s12031-016-0826-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/17/2016] [Indexed: 12/13/2022]
|
14
|
Climer LK, Dobretsov M, Lupashin V. Defects in the COG complex and COG-related trafficking regulators affect neuronal Golgi function. Front Neurosci 2015; 9:405. [PMID: 26578865 PMCID: PMC4621299 DOI: 10.3389/fnins.2015.00405] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/12/2015] [Indexed: 12/22/2022] Open
Abstract
The Conserved Oligomeric Golgi (COG) complex is an evolutionarily conserved hetero-octameric protein complex that has been proposed to organize vesicle tethering at the Golgi apparatus. Defects in seven of the eight COG subunits are linked to Congenital Disorders of Glycosylation (CDG)-type II, a family of rare diseases involving misregulation of protein glycosylation, alterations in Golgi structure, variations in retrograde trafficking through the Golgi and system-wide clinical pathologies. A troublesome aspect of these diseases are the neurological pathologies such as low IQ, microcephaly, and cerebellar atrophy. The essential function of the COG complex is dependent upon interactions with other components of trafficking machinery, such as Rab-GTPases and SNAREs. COG-interacting Rabs and SNAREs have been implicated in neurodegenerative diseases like Alzheimer's disease and Parkinson's disease. Defects in Golgi maintenance disrupts trafficking and processing of essential proteins, frequently associated with and contributing to compromised neuron function and human disease. Despite the recent advances in molecular neuroscience, the subcellular bases for most neurodegenerative diseases are poorly understood. This article gives an overview of the potential contributions of the COG complex and its Rab and SNARE partners in the pathogenesis of different neurodegenerative disorders.
Collapse
Affiliation(s)
- Leslie K Climer
- Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Maxim Dobretsov
- Department of Anesthesiology, College of Medicine, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Vladimir Lupashin
- Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences Little Rock, AR, USA
| |
Collapse
|
15
|
Duggan SP, McCarthy JV. Beyond γ-secretase activity: The multifunctional nature of presenilins in cell signalling pathways. Cell Signal 2015; 28:1-11. [PMID: 26498858 DOI: 10.1016/j.cellsig.2015.10.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/19/2015] [Indexed: 01/24/2023]
Abstract
The presenilins are the catalytic subunit of the membrane-embedded tetrameric γ-secretase protease complexes. More that 90 transmembrane proteins have been reported to be γ-secretase substrates, including the widely studied amyloid precursor protein (APP) and the Notch receptor, which are precursors for the generation of amyloid-β peptides and biologically active APP intracellular domain (AICD) and Notch intracellular domain (NICD). The diversity of γ-secretase substrates highlights the importance of presenilin-dependent γ-secretase protease activities as a regulatory mechanism in a range of biological systems. However, there is also a growing body of evidence that supports the existence of γ-secretase-independent functions for the presenilins in the regulation and progression of an array of cell signalling pathways. In this review, we will present an overview of current literature that proposes evolutionarily conserved presenilin functions outside of the γ-secretase complex, with a focus on the suggested role of the presenilins in the regulation of Wnt/β-catenin signalling, protein trafficking and degradation, calcium homeostasis and apoptosis.
Collapse
Affiliation(s)
- Stephen P Duggan
- Signal Transduction Laboratory, School of Biochemistry & Cell Biology, ABCRF, Western Gateway Building, University College Cork, Cork, Ireland
| | - Justin V McCarthy
- Signal Transduction Laboratory, School of Biochemistry & Cell Biology, ABCRF, Western Gateway Building, University College Cork, Cork, Ireland.
| |
Collapse
|
16
|
The role of rab proteins in neuronal cells and in the trafficking of neurotrophin receptors. MEMBRANES 2014; 4:642-77. [PMID: 25295627 PMCID: PMC4289860 DOI: 10.3390/membranes4040642] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/27/2014] [Accepted: 09/16/2014] [Indexed: 12/11/2022]
Abstract
Neurotrophins are a family of proteins that are important for neuronal development, neuronal survival and neuronal functions. Neurotrophins exert their role by binding to their receptors, the Trk family of receptor tyrosine kinases (TrkA, TrkB, and TrkC) and p75NTR, a member of the tumor necrosis factor (TNF) receptor superfamily. Binding of neurotrophins to receptors triggers a complex series of signal transduction events, which are able to induce neuronal differentiation but are also responsible for neuronal maintenance and neuronal functions. Rab proteins are small GTPases localized to the cytosolic surface of specific intracellular compartments and are involved in controlling vesicular transport. Rab proteins, acting as master regulators of the membrane trafficking network, play a central role in both trafficking and signaling pathways of neurotrophin receptors. Axonal transport represents the Achilles' heel of neurons, due to the long-range distance that molecules, organelles and, in particular, neurotrophin-receptor complexes have to cover. Indeed, alterations of axonal transport and, specifically, of axonal trafficking of neurotrophin receptors are responsible for several human neurodegenerative diseases, such as Huntington's disease, Alzheimer's disease, amyotrophic lateral sclerosis and some forms of Charcot-Marie-Tooth disease. In this review, we will discuss the link between Rab proteins and neurotrophin receptor trafficking and their influence on downstream signaling pathways.
Collapse
|
17
|
Wang X, Huang T, Bu G, Xu H. Dysregulation of protein trafficking in neurodegeneration. Mol Neurodegener 2014; 9:31. [PMID: 25152012 PMCID: PMC4237948 DOI: 10.1186/1750-1326-9-31] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/14/2014] [Indexed: 02/02/2023] Open
Abstract
Intracellular protein trafficking plays an important role in neuronal function and survival. Protein misfolding is a common theme found in many neurodegenerative diseases, and intracellular trafficking machinery contributes to the pathological accumulation and clearance of misfolded proteins. Although neurodegenerative diseases exhibit distinct pathological features, abnormal endocytic trafficking is apparent in several neurodegenerative diseases, such as Alzheimer’s disease (AD), Down syndrome (DS) and Parkinson’s disease (PD). In this review, we will focus on protein sorting defects in three major neurodegenerative diseases, including AD, DS and PD. An important pathological feature of AD is the presence of extracellular senile plaques in the brain. Senile plaques are composed of β-amyloid (Aβ) peptide aggregates. Multiple lines of evidence demonstrate that over-production/aggregation of Aβ in the brain is a primary cause of AD and attenuation of Aβ generation has become a topic of extreme interest in AD research. Aβ is generated from β-amyloid precursor protein (APP) through sequential cleavage by β-secretase and the γ-secretase complex. Alternatively, APP can be cleaved by α-secretase within the Aβ domain to release soluble APPα which precludes Aβ generation. DS patients display a strikingly similar pathology to AD patients, including the generation of neuronal amyloid plaques. Moreover, all DS patients develop an AD-like neuropathology by their 40 s. Therefore, understanding the metabolism/processing of APP and how these underlying mechanisms may be pathologically compromised is crucial for future AD and DS therapeutic strategies. Evidence accumulated thus far reveals that synaptic vesicle regulation, endocytic trafficking, and lysosome-mediated autophagy are involved in increased susceptibility to PD. Here we review current knowledge of endosomal trafficking regulation in AD, DS and PD.
Collapse
Affiliation(s)
| | | | | | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
| |
Collapse
|
18
|
Jiang S, Li Y, Zhang X, Bu G, Xu H, Zhang YW. Trafficking regulation of proteins in Alzheimer's disease. Mol Neurodegener 2014; 9:6. [PMID: 24410826 PMCID: PMC3891995 DOI: 10.1186/1750-1326-9-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 12/15/2013] [Indexed: 12/12/2022] Open
Abstract
The β-amyloid (Aβ) peptide has been postulated to be a key determinant in the pathogenesis of Alzheimer’s disease (AD). Aβ is produced through sequential cleavage of the β-amyloid precursor protein (APP) by β- and γ-secretases. APP and relevant secretases are transmembrane proteins and traffic through the secretory pathway in a highly regulated fashion. Perturbation of their intracellular trafficking may affect dynamic interactions among these proteins, thus altering Aβ generation and accelerating disease pathogenesis. Herein, we review recent progress elucidating the regulation of intracellular trafficking of these essential protein components in AD.
Collapse
Affiliation(s)
| | | | | | | | | | - Yun-wu Zhang
- Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
| |
Collapse
|
19
|
De Kimpe L, van Haastert ES, Kaminari A, Zwart R, Rutjes H, Hoozemans JJM, Scheper W. Intracellular accumulation of aggregated pyroglutamate amyloid beta: convergence of aging and Aβ pathology at the lysosome. AGE (DORDRECHT, NETHERLANDS) 2013; 35:673-687. [PMID: 22477259 PMCID: PMC3636379 DOI: 10.1007/s11357-012-9403-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 03/09/2012] [Indexed: 05/27/2023]
Abstract
Deposition of aggregated amyloid beta (Aβ) is a major hallmark of Alzheimer's disease (AD)-a common age-related neurodegenerative disorder. Typically, Aβ is generated as a peptide of varying lengths. However, a major fraction of Aβ peptides in the brains of AD patients has undergone posttranslational modifications, which often radically change the properties of the peptides. Aβ3(pE)-42 is an N-truncated, pyroglutamate-modified variant that is abundantly present in AD brain and was suggested to play a role early in the pathogenesis. Here we show that intracellular accumulation of oligomeric aggregates of Aβ3(pE)-42 results in loss of lysosomal integrity. Using a novel antibody specific for aggregates of AβpE3, we show that in postmortem human brain tissue, aggregated AβpE3 is predominantly found in the lysosomes of both neurons and glial cells. Our data further demonstrate that AβpE3 is relatively resistant to lysosomal degradation, which may explain its accumulation in the lysosomes. The intracellular AβpE3 aggregates increase in an age-dependent manner. The results presented in this study support a model where Aβ pathology and aging converge, leading to accumulation of the degradation-resistant pE-modified Aβ in the lysosomes, lysosomal dysfunction, and neurodegeneration.
Collapse
Affiliation(s)
- Line De Kimpe
- Department of Genome Analysis, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Elise S. van Haastert
- Department of Pathology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Archontia Kaminari
- Department of Genome Analysis, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Rob Zwart
- Department of Genome Analysis, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Helma Rutjes
- Hycult Biotech, Frontstraat 2a, 5405 PB Uden, The Netherlands
| | - Jeroen J. M. Hoozemans
- Department of Pathology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Wiep Scheper
- Department of Genome Analysis, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Department of Neurology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Department of Genome Analysis, Academic Medical Center, P.O. Box 22660, 1100 DE Amsterdam, The Netherlands
| |
Collapse
|
20
|
A new Mint1 isoform, but not the conventional Mint1, interacts with the small GTPase Rab6. PLoS One 2013; 8:e64149. [PMID: 23737971 PMCID: PMC3667844 DOI: 10.1371/journal.pone.0064149] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/09/2013] [Indexed: 12/31/2022] Open
Abstract
Small GTPases of the Rab family are important regulators of a large variety of different cellular functions such as membrane organization and vesicle trafficking. They have been shown to play a role in several human diseases. One prominent member, Rab6, is thought to be involved in the development of Alzheimer's Disease, the most prevalent mental disorder worldwide. Previous studies have shown that Rab6 impairs the processing of the amyloid precursor protein (APP), which is cleaved to β-amyloid in brains of patients suffering from Alzheimer's Disease. Additionally, all three members of the Mint adaptor family are implied to participate in the amyloidogenic pathway. Here, we report the identification of a new Mint1 isoform in a yeast two-hybrid screening, Mint1 826, which lacks an eleven amino acid (aa) sequence in the conserved C-terminal region. Mint1 826, but not the conventional Mint1, interacts with Rab6 via the PTB domain. This interaction is nucleotide-dependent, Rab6-specific and influences the subcellular localization of Mint1 826. We were able to detect and sequence a corresponding proteolytic peptide derived from cellular Mint1 826 by mass spectrometry proving the absence of aa 495-505 and could show that the deletion does not influence the ability of this adaptor protein to interact with APP. Taking into account that APP interacts and co-localizes with Mint1 826 and is transported in Rab6 positive vesicles, our data suggest that Mint1 826 bridges APP to the small GTPase at distinct cellular sorting points, establishing Mint1 826 as an important player in regulation of APP trafficking and processing.
Collapse
|
21
|
Funk KE, Kuret J. Lysosomal fusion dysfunction as a unifying hypothesis for Alzheimer's disease pathology. Int J Alzheimers Dis 2012; 2012:752894. [PMID: 22970406 PMCID: PMC3437286 DOI: 10.1155/2012/752894] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/01/2012] [Accepted: 08/02/2012] [Indexed: 12/31/2022] Open
Abstract
Alzheimer's disease is characterized pathologically by extracellular senile plaques, intracellular neurofibrillary tangles, and granulovacuolar degeneration. It has been debated whether these hallmark lesions are markers or mediators of disease progression, and numerous paradigms have been proposed to explain the appearance of each lesion individually. However, the unfaltering predictability of these lesions suggests a single pathological nidus central to disease onset and progression. One of the earliest pathologies observed in Alzheimer's disease is endocytic dysfunction. Here we review the recent literature of endocytic dysfunction with particular focus on disrupted lysosomal fusion and propose it as a unifying hypothesis for the three most-studied lesions of Alzheimer's disease.
Collapse
Affiliation(s)
- Kristen E. Funk
- Department of Molecular and Cellular Biochemistry, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Jeff Kuret
- Department of Molecular and Cellular Biochemistry, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| |
Collapse
|
22
|
Qi X, Cai J, Ruan Q, Liu L, Boye SL, Chen Z, Hauswirth WW, Ryals RC, Shaw L, Caballero S, Grant MB, Boulton ME. γ-Secretase inhibition of murine choroidal neovascularization is associated with reduction of superoxide and proinflammatory cytokines. Invest Ophthalmol Vis Sci 2012; 53:574-85. [PMID: 22205609 DOI: 10.1167/iovs.11-8728] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
PURPOSE This study aimed to determine whether upregulation of γ-secretase could inhibit laser-induced choroidal neovascularization (CNV) and if this was associated with a reduction in both oxidative stress and proinflammatory cytokines. METHODS γ-Secretase, or its catalytic subunit presenilin 1 (PS1), were upregulated by exposure to either pigment epithelial derived factor (PEDF) or an AAV2 vector containing a PS1 gene driven by a vascular endothelial-cadherin promoter. Retinal endothelial cells were infected with AAV2 or exposed to PEDF in the presence or absence of VEGF and in vitro angiogenesis determined. Mouse eyes either received intravitreal injection of PEDF, DAPT (a γ-secretase inhibitor) or PEDF + DAPT at the time of laser injury, or AAV2 infection 3 weeks before receiving laser burns. Lesion volume was determined 14 days post laser injury. Superoxide generation, antioxidant activity and the production of proinflammatory mediators were assessed. Knockdown of γ-secretase was achieved using siRNA. RESULTS γ-Secretase upregulation and PS1 overexpression suppressed VEGF-induced in vitro angiogenesis and in vivo laser-induced CNV. This was associated with a reduction in the expression of VEGF and angiogenin 1 together with reduced superoxide anion generation and an increase in MnSOD compared with untreated CNV eyes. PS1 overexpression reduced proinflammatory factors and microglial activation in eyes with CNV compared with control. siRNA inhibition of γ-secretase resulted in increased angiogenesis. CONCLUSIONS γ-Secretase, and in particular PS1 alone, are potent regulators of angiogenesis and this is due in part to stabilizing endogenous superoxide generation and reducing proinflammatory cytokine expression during CNV.
Collapse
Affiliation(s)
- Xiaoping Qi
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Pavarotti M, Capmany A, Vitale N, Colombo MI, Damiani MT. Rab11 is phosphorylated by classical and novel protein kinase C isoenzymes upon sustained phorbol ester activation. Biol Cell 2012; 104:102-15. [PMID: 22188018 DOI: 10.1111/boc.201100062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 11/29/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND INFORMATION Rab11 is a small GTPase that controls diverse intracellular trafficking pathways. However, the molecular machinery that regulates the participation of Rab11 in those different transport events is poorly understood. In resting cells, Rab11 localizes at the endocytic recycling compartment (ERC), whereas the different protein kinase C (PKC) isoforms display a cytosolic distribution. RESULTS Sustained phorbol ester stimulation induces the translocation of the classical PKCα and PKCβII isoenzymes to the ERC enriched in Rab11, and results in transferrin recycling inhibition. In contrast, novel PKCε and atypical PKCζ isoenzymes neither redistribute to the perinucleus nor modify transferrin recycling transport after phorbol ester stimulation. Although several Rabs have been shown to be phosphorylated, there is to date no evidence indicating Rab11 as a kinase substrate. In this report, we show that Rab11 appears phosphorylated in vivo in phorbol ester-stimulated cells. A bioinformatic analysis of Rab11 allowed us to identify several high-probability Ser/Thr kinase phosphorylation sites. Our results demonstrate that classical PKC (PKCα and PKCβII but not PKCβI) directly phosphorylate Rab11 in vitro. In addition, novel PKCε and PKCη but not PKCδ isoenzymes also phosphorylate Rab11. Mass spectrometry analysis revealed that Ser 177 is the Rab11 residue to be phosphorylated in vitro by either PKCβII or PKCε. In agreement, the phosphomimetic mutant, Rab11 S177D, retains transferrin at the ERC in the absence of phorbol-12-myristate-13-acetate stimulus. CONCLUSIONS This report shows for the first time that Rab11 is differentially phosphorylated by distinct PKC isoenzymes and that this post-translational modification might be a regulatory mechanism of intracellular trafficking.
Collapse
Affiliation(s)
- Martín Pavarotti
- IHEM-CONICET, National Research Council, School of Medicine, University of Cuyo, Mendoza, Argentina
| | | | | | | | | |
Collapse
|
24
|
Cai J, Chen Z, Ruan Q, Han S, Liu L, Qi X, Boye SL, Hauswirth WW, Grant MB, Boulton ME. γ-Secretase and presenilin mediate cleavage and phosphorylation of vascular endothelial growth factor receptor-1. J Biol Chem 2011; 286:42514-42523. [PMID: 22016384 PMCID: PMC3234916 DOI: 10.1074/jbc.m111.296590] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We have reported previously that pigment epithelium-derived factor (PEDF) can, via γ-secretase-mediated events, inhibit VEGF-induced angiogenesis in microvascular endothelial cells by both (a) cleavage and intracellular translocation of a C-terminal fragment of VEGF receptor-1 (VEGFR1) and (b) inhibition of VEGF-induced phosphorylation of VEGFR1. Using site-direct mutagenesis and transfection of wild type and mutated receptors into endothelial cells, we showed that transmembrane cleavage of VEGFR1 occurs at valine 767 and that a switch from valine to alanine at this position prevented cleavage and formation of a VEGFR1 intracellular fragment. Using siRNA to selectively knock down protein-tyrosine phosphatases (PTPs) in endothelial cells, we demonstrated that vascular endothelial PTP is responsible for dephosphorylation of activated VEGFR1. PEDF up-regulation of full-length presenilin 1 (Fl.PS1) facilitated the association of vascular endothelial PTP and VEGFR1. Knockdown of Fl.PS1 prevented dephosphorylation of VEGFR1, whereas up-regulation of Fl.PS1 stimulated VEGFR1 dephosphorylation. Fl.PS1 associated with VEGFR1 within 15 min after PEDF treatment. In conclusion, we determined the PEDF-mediated events responsible for VEGFR1 signaling and identified full-length presenilin as a critical adaptor molecule in the dephosphorylation of VEGFR1. This greater understanding of the regulation of VEGFR1 signaling will help identify novel anti-VEGF therapeutic strategies.
Collapse
Affiliation(s)
- Jun Cai
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235
| | - Zhijuan Chen
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235
| | - Qing Ruan
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235
| | - Song Han
- Department of Surgery, University of Florida, Gainesville, Florida 32610-0235
| | - Li Liu
- Departments of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida 32610-0235
| | - Xiaoping Qi
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235
| | - Sanford L Boye
- Department of Ophthalmology, University of Florida, Gainesville, Florida 32610-0235
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida 32610-0235
| | - Maria B Grant
- Departments of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida 32610-0235
| | - Michael E Boulton
- Departments of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235.
| |
Collapse
|
25
|
Abstract
AD (Alzheimer's disease) is a neurodegenerative disease characterized by a gradual loss of neurons and the accumulation of neurotoxic Aβ (amyloid β-peptide) and hyperphosphorylated tau. The discovery of mutations in three genes, PSEN1 (presenilin 1), PSEN2 (presenilin 2) and APP (amyloid precursor protein), in patients with FAD (familial AD) has made an important contribution towards an understanding of the disease aetiology; however, a complete molecular mechanism is still lacking. Both presenilins belong to the γ-secretase complex, and serve as the catalytic entity needed for the final cleavage of APP into Aβ. PSEN only functions within the γ-secretase complex through intra- and inter-molecular interactions with three other membrane components, including nicastrin, Aph-1 (anterior pharynx defective-1) and Pen-2 (PSEN enhancer-2). However, although the list of γ-secretase substrates is still expanding, other non-catalytic activities of presenilins are also increasing the complexity behind its molecular contribution towards AD. These γ-secretase-independent roles are so far mainly attributed to PSEN1, including the transport of membrane proteins, cell adhesion, ER (endoplasmic reticulum) Ca(2+) regulation and cell signalling. In the present minireview, we discuss the current understanding of the γ-secretase-independent roles of PSENs and their possible implications in respect of AD.
Collapse
|
26
|
Zhang YW, Thompson R, Zhang H, Xu H. APP processing in Alzheimer's disease. Mol Brain 2011; 4:3. [PMID: 21214928 PMCID: PMC3022812 DOI: 10.1186/1756-6606-4-3] [Citation(s) in RCA: 566] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 01/07/2011] [Indexed: 12/12/2022] Open
Abstract
An important pathological feature of Alzheimer's disease (AD) is the presence of extracellular senile plaques in the brain. Senile plaques are composed of aggregations of small peptides called β-amyloid (Aβ). Multiple lines of evidence demonstrate that overproduction/aggregation of Aβ in the brain is a primary cause of AD and inhibition of Aβ generation has become a hot topic in AD research. Aβ is generated from β-amyloid precursor protein (APP) through sequential cleavages first by β-secretase and then by γ-secretase complex. Alternatively, APP can be cleaved by α-secretase within the Aβ domain to release soluble APPα and preclude Aβ generation. Cleavage of APP by caspases may also contribute to AD pathologies. Therefore, understanding the metabolism/processing of APP is crucial for AD therapeutics. Here we review current knowledge of APP processing regulation as well as the patho/physiological functions of APP and its metabolites.
Collapse
Affiliation(s)
- Yun-wu Zhang
- Institute for Biomedical Research, Xiamen University, 422 SiMingNanLu, Xiamen 361005, Fujian, PR China
| | | | | | | |
Collapse
|
27
|
Modulation of cholesterol, farnesylpyrophosphate, and geranylgeranylpyrophosphate in neuroblastoma SH-SY5Y-APP695 cells: impact on amyloid beta-protein production. Mol Neurobiol 2010; 41:341-50. [PMID: 20405344 DOI: 10.1007/s12035-010-8117-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 03/15/2010] [Indexed: 12/23/2022]
Abstract
There is keen interest in the role of the isoprenoids farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP) in protein prenylation and cell function in Alzheimer's disease (AD). We recently reported elevated FPP and GGPP brain levels and increased gene expression of FPP synthase (FPPS) and GGPP synthase (GGPPS) in the frontal cortex of AD patients. Cholesterol levels and gene expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase were similar in AD and control samples, suggesting that homeostasis of FPP and GGPP but not cholesterol is specifically targeted in brain tissue of AD patients (Neurobiol Dis 2009 35:251-257). In the present study, it was determined if cellular levels of FPP, GGPP, and cholesterol affect beta-amyloid (Abeta) abundance in SH-SY5Y cells, expressing human APP695. Cells were treated with different inhibitors of the mevalonate/isoprenoid/cholesterol pathway. FPP, GGPP, cholesterol, and Abeta(1-40) levels were determined, and activities of farnesyltransferase and geranylgeranyltransferase I were measured. Inhibitors of different branches of the mevalonate/isoprenoid/cholesterol pathway as expected reduced cholesterol and isoprenoid levels in neuroblastoma cells. Abeta(1-40) levels were selectively reduced by cholesterol synthesis inhibitors but not by inhibitors of protein isoprenylation, indicating that changes in cholesterol levels per se and not isoprenoid levels account for the observed modifications in Abeta production.
Collapse
|
28
|
Hooff GP, Wood WG, Müller WE, Eckert GP. Isoprenoids, small GTPases and Alzheimer's disease. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:896-905. [PMID: 20382260 DOI: 10.1016/j.bbalip.2010.03.014] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Revised: 03/26/2010] [Accepted: 03/27/2010] [Indexed: 11/27/2022]
Abstract
The mevalonate pathway is a crucial metabolic pathway for most eukaryotic cells. Cholesterol is a highly recognized product of this pathway but growing interest is being given to the synthesis and functions of isoprenoids. Isoprenoids are a complex class of biologically active lipids including for example, dolichol, ubiquinone, farnesylpyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). Early work had shown that the long-chain isoprenoid dolichol is decreased but that dolichyl phosphate and ubiquinone are elevated in brains of Alzheimer's disease (AD) patients. Until recently, levels of their biological active precursors FPP and GGPP were unknown. These short-chain isoprenoids are critical in the post-translational modification of certain proteins which function as molecular switches in numerous signaling pathways. The major protein families belong to the superfamily of small GTPases, consisting of roughly 150 members. Recent experimental evidence indicated that members of the small GTPases are involved in AD pathogenesis and stimulated interest in the role of FPP and GGPP in protein prenylation and cell function. A straightforward prediction derived from those studies was that FPP and GGPP levels would be elevated in AD brains as compared with normal neurological controls. For the first time, recent evidence shows significantly elevated levels of FPP and GGPP in human AD brain tissue. Cholesterol levels did not differ between AD and control samples. One obvious conclusion is that homeostasis of FPP and GGPP but not of cholesterol is specifically targeted in AD. Since prenylation of small GTPases by FPP or GGPP is indispensable for their proper function we are proposing that these two isoprenoids are up-regulated in AD resulting in an over abundance of certain prenylated proteins which contributes to neuronal dysfunction.
Collapse
Affiliation(s)
- Gero P Hooff
- Department of Pharmacology, Campus Riedberg, Goethe University, 60438 Frankfurt, Germany
| | | | | | | |
Collapse
|
29
|
Regulation of the brain isoprenoids farnesyl- and geranylgeranylpyrophosphate is altered in male Alzheimer patients. Neurobiol Dis 2009; 35:251-7. [PMID: 19464372 PMCID: PMC3778879 DOI: 10.1016/j.nbd.2009.05.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/02/2009] [Accepted: 05/10/2009] [Indexed: 11/24/2022] Open
Abstract
Post-translational modification of small GTPases by farnesyl- (FPP) and geranylgeranylpyrophosphate (GGPP) has generated much attention due to their potential contribution to cancer, cardiovascular and neurodegenerative diseases. Prenylated proteins have been identified in numerous cell functions and elevated levels of FPP and GGPP have been previously proposed to occur in Alzheimer disease (AD) but have never been quantified. In the present study, we determined if the mevalonate derived compounds FPP and GGPP are increased in brain grey and white matter of male AD patients as compared with control samples. This study demonstrates for the first time that FPP and GGPP levels are significantly elevated in human AD grey and white matter but not cholesterol, indicating a potentially disease-specific targeting of isoprenoid regulation independent of HMG-CoA-reductase. Further suggesting a selective disruption of FPP and GGPP homeostasis in AD, we show that inhibition of HMG-CoA reductase in vivo significantly reduced FPP, GGPP and cholesterol abundance in mice with the largest effect on the isoprenoids. A tentative conclusion is that if indeed regulation of FPP and GGPP is altered in AD brain such changes may stimulate protein prenylation and contribute to AD neuropathophysiology.
Collapse
|
30
|
Liu Y, Zhang YW, Wang X, Zhang H, You X, Liao FF, Xu H. Intracellular trafficking of presenilin 1 is regulated by beta-amyloid precursor protein and phospholipase D1. J Biol Chem 2009; 284:12145-52. [PMID: 19276086 DOI: 10.1074/jbc.m808497200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Excessive accumulation of beta-amyloid peptides in the brain is a major cause for the pathogenesis of Alzheimer disease. beta-Amyloid is derived from beta-amyloid precursor protein (APP) through sequential cleavages by beta- and gamma-secretases, whose enzymatic activities are tightly controlled by subcellular localization. Delineation of how intracellular trafficking of these secretases and APP is regulated is important for understanding Alzheimer disease pathogenesis. Although APP trafficking is regulated by multiple factors including presenilin 1 (PS1), a major component of the gamma-secretase complex, and phospholipase D1 (PLD1), a phospholipid-modifying enzyme, regulation of intracellular trafficking of PS1/gamma-secretase and beta-secretase is less clear. Here we demonstrate that APP can reciprocally regulate PS1 trafficking; APP deficiency results in faster transport of PS1 from the trans-Golgi network to the cell surface and increased steady state levels of PS1 at the cell surface, which can be reversed by restoring APP levels. Restoration of APP in APP-deficient cells also reduces steady state levels of other gamma-secretase components (nicastrin, APH-1, and PEN-2) and the cleavage of Notch by PS1/gamma-secretase that is more highly correlated with cell surface levels of PS1 than with APP overexpression levels, supporting the notion that Notch is mainly cleaved at the cell surface. In contrast, intracellular trafficking of beta-secretase (BACE1) is not regulated by APP. Moreover, we find that PLD1 also regulates PS1 trafficking and that PLD1 overexpression promotes cell surface accumulation of PS1 in an APP-independent manner. Our results clearly elucidate a physiological function of APP in regulating protein trafficking and suggest that intracellular trafficking of PS1/gamma-secretase is regulated by multiple factors, including APP and PLD1.
Collapse
Affiliation(s)
- Yun Liu
- Burnham Institute for Medical Research, La Jolla, California 92037, USA
| | | | | | | | | | | | | |
Collapse
|
31
|
Hass MR, Sato C, Kopan R, Zhao G. Presenilin: RIP and beyond. Semin Cell Dev Biol 2008; 20:201-10. [PMID: 19073272 DOI: 10.1016/j.semcdb.2008.11.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/19/2008] [Accepted: 11/19/2008] [Indexed: 12/22/2022]
Abstract
Over the years the presenilins (PSENs), a family of multi-transmembrane domain proteins, have been ascribed a number of diverse potential functions. Recent in vivo evidence has supported the existence of PSEN functions beyond its well-established role in regulated intramembrane proteolysis. In this review, we will briefly discuss the ability of PSEN to modulate cellular signaling pathways through gamma-secretase cleavage of transmembrane proteins. Additionally, we will critically examine the proposed roles of PSEN in the regulation of beta-catenin function, protein trafficking, calcium regulation, and apoptosis.
Collapse
Affiliation(s)
- Matthew R Hass
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, MO, United States
| | | | | | | |
Collapse
|
32
|
Reid PC, Urano Y, Kodama T, Hamakubo T. Alzheimer's disease: cholesterol, membrane rafts, isoprenoids and statins. J Cell Mol Med 2007; 11:383-92. [PMID: 17635634 PMCID: PMC3922347 DOI: 10.1111/j.1582-4934.2007.00054.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is a heterogeneous neurodegenerative disorder and the most prevalent form of dementia worldwide. AD is characterized pathologically by amyloid-β plaques, neurofibrillary tangles and neuronal loss, and clinically by a progressive loss of cognitive abilities. At present, the fundamental molecular mechanisms underlying the disease are unclear and no treatment for AD is known. Epidemiological evidence continues to mount linking vascular diseases, such as hypertension and diabetes, and hypercholesterolaemia with an increased risk for developing AD. A growing amount of evidence suggests a mechanistic link between cholesterol metabolism in the brain and the formation of amyloid plaques in AD development. Cholesterol and statins clearly modulate β-amyloid precursor protein (βAPP) processing in cell culture and animal models. Statins not only reduce endogenous cholesterol synthesis but also exert other various pleiotrophic effects, such as the reduction in protein isoprenylation. Through these effects statins modulate a variety of cellular functions involving both cholesterol (and membrane rafts) and isoprenylation. Although clearly other factors, such as vascular inflammation, oxidative stress and genetic factors, are intimately linked with the progression of AD, this review focuses on the present research findings describing the effect of cholesterol, membrane rafts and isoprenylation in regulating βAPP processing and in particular γ-secretase complex assembly and function and AD progression, along with consideration for the potential role statins may play in modulating these events.
Collapse
Affiliation(s)
- Patrick C Reid
- Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
- PeptiDream Inc., Tokyo, Japan
- *Correspondence to: Takao HAMAKUBO Department of Molecular Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, #35 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. Tel.: +81-3-5452-5231; Fax: +81-3-5452-5232 E-mail:
| | - Yasuomi Urano
- Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH, USA
| | - Tatsuhiko Kodama
- Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Takao Hamakubo
- Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
- Department of Molecular Biology and Medicine, The University of Tokyo, Tokyo, Japan
- *Correspondence to: Takao HAMAKUBO Department of Molecular Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, #35 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. Tel.: +81-3-5452-5231; Fax: +81-3-5452-5232 E-mail:
| |
Collapse
|
33
|
Scheper W, Hoozemans JJM, Hoogenraad CC, Rozemuller AJM, Eikelenboom P, Baas F. Rab6 is increased in Alzheimer's disease brain and correlates with endoplasmic reticulum stress. Neuropathol Appl Neurobiol 2007; 33:523-32. [PMID: 17573808 DOI: 10.1111/j.1365-2990.2007.00846.x] [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: 10/23/2022]
Abstract
Alzheimer's disease (AD) is characterized by deposits of aggregated proteins. Accumulation of aggregation-prone proteins activates protein quality control mechanisms, such as the unfolded protein response (UPR) in the endoplasmic reticulum (ER). We previously reported upregulation of the UPR marker BiP in AD brain. In this study, we investigated the small GTPase Rab6, which is involved in retrograde Golgi-ER trafficking and may function as a post-ER quality control system. Using immunohistochemistry and semiquantitative Western blotting, the expression of Rab6 was analysed in hippocampus, entorhinal and temporal cortex of 10 AD patients and six nondemented control subjects. Rab6 is upregulated in AD temporal cortex from Braak stage 3/4, the same stage that UPR activation is found. We observe increased neuronal Rab6 immunoreactivity in all brain areas examined. Although some neurones show colocalization of immunoreactivity for Rab6 and hyperphosphorylated tau, strong Rab6 staining does not colocalize with tangles. We find a highly significant correlation between the Rab6 and BiP levels. In vitro data show that Rab6 is not upregulated as a result of UPR activation or proteasome inhibition indicating an independent regulatory mechanism. Our data suggest that ER and post-ER protein quality control mechanisms are activated early in the pathology of AD.
Collapse
Affiliation(s)
- W Scheper
- Neurogenetics Laboratory, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | | | | | |
Collapse
|
34
|
Selivanova A, Winblad B, Farmery MR, Dantuma NP, Ankarcrona M. COPI-mediated retrograde transport is required for efficient γ-secretase cleavage of the amyloid precursor protein. Biochem Biophys Res Commun 2006; 350:220-6. [PMID: 16999935 DOI: 10.1016/j.bbrc.2006.09.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Accepted: 09/09/2006] [Indexed: 11/30/2022]
Abstract
Sequential cleavage of the amyloid precursor protein (APP) by beta- and gamma-secretases results in the production of beta-amyloid peptide, which is a key determinant in Alzheimer's disease. Since several putative locations for gamma-secretase cleavage have been identified along the secretory pathway, trafficking of APP may be of importance for beta-amyloid peptide production. Here we have studied the role of retrograde transport in APP processing. We found that APP interacts with the beta subunit of the coatomer protein I (COPI) complex, which is involved in retrograde transport. In line with a role of retrograde trafficking in APP transport, inhibition of COPI-dependent transport altered APP trafficking, decreased APP cell surface expression, and coincided with a profound reduction in gamma-secretase cleavage. These results suggest that COPI-dependent retrograde transport is important for APP processing and influences production of beta-amyloid peptide.
Collapse
Affiliation(s)
- Alexandra Selivanova
- Department of Neurobiology, Caring Sciences and Society (NVS), KI Alzheimer Disease Research Center, Karolinska Institutet, Novum 5th floor, S-141 57 Stockholm, Sweden.
| | | | | | | | | |
Collapse
|
35
|
Burré J, Beckhaus T, Corvey C, Karas M, Zimmermann H, Volknandt W. Synaptic vesicle proteins under conditions of rest and activation: Analysis by 2-D difference gel electrophoresis. Electrophoresis 2006; 27:3488-96. [PMID: 16944461 DOI: 10.1002/elps.200500864] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Synaptic vesicles are organelles of the nerve terminal that secrete neurotransmitters by fusion with the presynaptic plasma membrane. Vesicle fusion is tightly controlled by depolarization of the plasma membrane and a set of proteins that may undergo post-translational modifications such as phosphorylation. In order to identify proteins that undergo modifications as a result of synaptic activation, we induced massive exocytosis and analysed the synaptic vesicle compartment by benzyldimethyl-n-hexadecylammonium chloride (BAC)/SDS-PAGE and difference gel electrophoresis (DIGE) followed by MALDI-TOF-MS. We identified eight proteins that revealed significant changes in abundance following nerve terminal depolarization. Of these, six were increased and two were decreased in abundance. Three of these proteins were phosphorylated as detected by Western blot analysis. In addition, we identified an unknown synaptic vesicle protein whose abundance increased on synaptic activation. Our results demonstrate that depolarization of the presynaptic compartment induces changes in the abundance of synaptic vesicle proteins and post-translational protein modification.
Collapse
Affiliation(s)
- Jacqueline Burré
- Department of Neurochemistry, JW Goethe-University, Frankfurt/Main, Germany.
| | | | | | | | | | | |
Collapse
|
36
|
Vetrivel KS, Zhang YW, Xu H, Thinakaran G. Pathological and physiological functions of presenilins. Mol Neurodegener 2006; 1:4. [PMID: 16930451 PMCID: PMC1513131 DOI: 10.1186/1750-1326-1-4] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Accepted: 06/12/2006] [Indexed: 11/16/2022] Open
Abstract
Mutations in PSEN1 and PSEN2 genes account for the majority of cases of early-onset familial Alzheimer disease. Since the first prediction of a genetic link between PSEN1 and PSEN2 with Alzheimer's disease, many research groups from both academia and pharmaceutical industry have sought to unravel how pathogenic mutations in PSEN cause presenile dementia. PSEN genes encode polytopic membrane proteins termed presenilins (PS1 and PS2), which function as the catalytic subunit of γ-secretase, an intramembrane protease that has a wide spectrum of type I membrane protein substrates. Sequential cleavage of amyloid precursor protein by BACE and γ-secretase releases highly fibrillogenic β-amyloid peptides, which accumulate in the brains of aged individuals and patients with Alzheimer's disease. Familial Alzheimer's disease-associated presenilin variants are thought to exert their pathogenic function by selectively elevating the levels of highly amyloidogenic Aβ42 peptides. In addition to Alzheimer's disease, several recent studies have linked PSEN1 to familiar frontotemporal dementia. Here, we review the biology of PS1, its role in γ-secretase activity, and discuss recent developments in the cell biology of PS1 with respect to Alzheimer's disease pathogenesis.
Collapse
Affiliation(s)
- Kulandaivelu S Vetrivel
- Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, Chicago, IL 60637, USA
| | - Yun-wu Zhang
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, LaJolla, CA 92037, USA
| | - Huaxi Xu
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, LaJolla, CA 92037, USA
| | - Gopal Thinakaran
- Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, Chicago, IL 60637, USA
| |
Collapse
|
37
|
Cole SL, Vassar R. Isoprenoids and Alzheimer's disease: a complex relationship. Neurobiol Dis 2006; 22:209-22. [PMID: 16406223 DOI: 10.1016/j.nbd.2005.11.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 11/04/2005] [Accepted: 11/13/2005] [Indexed: 11/22/2022] Open
Abstract
Cholesterol metabolism has been linked to Alzheimer's disease (AD) neuropathology, which is characterized by amyloid plaques, neurofibrillary tangles and neuroinflammation. Indeed, the use of statins, which inhibit cholesterol and isoprenoid biosynthesis, as potential AD therapeutics is under investigation. Whether statins offer benefit for AD will be determined by the outcome of large, placebo-controlled, randomized clinical trials. However, their use as pharmacological tools has delineated novel roles for isoprenoids in AD. Protein isoprenylation regulates multiple cellular and molecular events and here we review the complex roles of isoprenoids in AD-relevant processes and carefully evaluate isoprenoid pathways as potential AD therapeutic targets.
Collapse
Affiliation(s)
- S L Cole
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA.
| | | |
Collapse
|
38
|
Teber I, Nagano F, Kremerskothen J, Bilbilis K, Goud B, Barnekow A. Rab6 interacts with the mint3 adaptor protein. Biol Chem 2005; 386:671-7. [PMID: 16207088 DOI: 10.1515/bc.2005.078] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe Rab6 GTPase regulates a retrograde transport route connecting endosomes and the endoplasmic reticulum (ER) via the Golgi apparatus. Recently it was shown that active (GTP-loaded) Rab6A regulates intracellular processing of the amyloid precursor protein (APP). To characterize the role of Rab6A in APP trafficking and to identify effector proteins of the active Rab6A protein, we screened a human placenta cDNA library using the yeast two-hybrid system. We isolated an interacting cDNA clone encoding part of the adaptor protein mint3. The interaction between Rab6A and mint3 is GTP-dependent and requires the complete phosphotyrosine-binding (PTB) domain of the mint protein, which also mediates the association with APP. By confocal microscopy we show that Rab6A, mint3 and APP co-localize at Golgi membranes in HeLa cells. Density gradient centrifugation of cytosolic extracts confirms a common distribution of these three proteins. Our data suggest that mint3 links Rab6A to APP traffic.
Collapse
Affiliation(s)
- Iskender Teber
- Department of Experimental Tumor Biology, University of Münster, D-48149 Germany
| | | | | | | | | | | |
Collapse
|
39
|
Scheper W, Zwart R, Baas F. Alternative splicing in the N-terminus of Alzheimer's presenilin 1. Neurogenetics 2004; 5:223-7. [PMID: 15480879 DOI: 10.1007/s10048-004-0195-y] [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] [Received: 08/23/2004] [Accepted: 08/27/2004] [Indexed: 12/17/2022]
Abstract
Presenilin 1 (PS1) is mutated in the majority of familial cases of Alzheimer disease (AD). Although it is clear that PS1 is involved in the processing of the amyloid precursor protein (APP), the exact function of PS1 is still elusive. Human presenilin 1 (PS1) is alternatively spliced, resulting in the presence or absence of a four-amino acid motif, VRSQ, in the PS1 N-terminus. In human tissues, both isoforms are expressed. Here we report that mouse and rat only express the longer PS1 isoform. The presence of this motif introduces a potential phosphorylation site for protein kinase C. Because the splice occurs in the region of PS1 that we have previously shown to bind to rabGDI, this might provide a regulatory mechanism for this interaction. Our data show that the -VRSQ isoform binds rabGDI, but the +VRSQ does not. Moreover, mutation of the putatively phosphorylated threonine in PS1 disrupts the binding to rabGDI, showing its importance for the interaction. To our knowledge this is the first study showing a functional difference between PS1 splice variants. The possible consequences for APP processing and the pathogenesis of AD are discussed.
Collapse
Affiliation(s)
- Wiep Scheper
- Neurogenetics Laboratory, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | |
Collapse
|