1
|
Pu Y, Yang J, Pan Q, Li C, Wang L, Xie X, Chen X, Xiao F, Chen G. MGST3 regulates BACE1 protein translation and amyloidogenesis by controlling the RGS4-mediated AKT signaling pathway. J Biol Chem 2024; 300:107530. [PMID: 38971310 PMCID: PMC11332907 DOI: 10.1016/j.jbc.2024.107530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/03/2024] [Accepted: 06/16/2024] [Indexed: 07/08/2024] Open
Abstract
Microsomal glutathione transferase 3 (MGST3) regulates eicosanoid and glutathione metabolism. These processes are associated with oxidative stress and apoptosis, suggesting that MGST3 might play a role in the pathophysiology of Alzheimer's disease. Here, we report that knockdown (KD) of MGST3 in cell lines reduced the protein level of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and the resulting amyloidogenesis. Interestingly, MGST3 KD did not alter intracellular reactive oxygen species level but selectively reduced the expression of apoptosis indicators which could be associated with the receptor of cysteinyl leukotrienes, the downstream metabolites of MGST3 in arachidonic acid pathway. We then showed that the effect of MGST3 on BACE1 was independent of cysteinyl leukotrienes but involved a translational mechanism. Further RNA-seq analysis identified that regulator of G-protein signaling 4 (RGS4) was a target gene of MGST3. Silencing of RGS4 inhibited BACE1 translation and prevented MGST3 KD-mediated reduction of BACE1. The potential mechanism was related to AKT activity, as the protein level of phosphorylated AKT was significantly reduced by silencing of MGST3 and RGS4, and the AKT inhibitor abolished the effect of MGST3/RGS4 on phosphorylated AKT and BACE1. Together, MGST3 regulated amyloidogenesis by controlling BACE1 protein expression, which was mediated by RGS4 and downstream AKT signaling pathway.
Collapse
Affiliation(s)
- Yalan Pu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China; Department of Neurology, Langzhong People's Hospital, Nanchong, Sichuan, China
| | - Jie Yang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China; Affiliated Sichuan Provincial Rehabilitation Hospital of Chengdu University of TCM, Sichuan, China
| | - Qiuling Pan
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Chenlu Li
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Lu Wang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiaoyong Xie
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xue Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Fei Xiao
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China.
| | - Guojun Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China.
| |
Collapse
|
2
|
Trehalose Reduces the Secreted Beta-Amyloid Levels in Primary Neurons Independently of Autophagy Induction. Metabolites 2021; 11:metabo11070421. [PMID: 34206776 PMCID: PMC8306653 DOI: 10.3390/metabo11070421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 06/21/2021] [Accepted: 06/21/2021] [Indexed: 12/28/2022] Open
Abstract
The disaccharide trehalose was described as possessing relevant neuroprotective properties as an mTORC1-independent inducer of autophagy, with the ability to protect cellular membranes and denaturation, resulting from desiccation, and preventing the cellular accumulation of protein aggregates. These properties make trehalose an interesting therapeutic candidate against proteinopathies such as Alzheimer’s disease (AD), which is characterized by deposits of aggregated amyloid-beta (Aβ) and hyperphosphorylated tau. In this study, we observed that trehalose was able to induce autophagy in neurons only in the short-term, whereas long-term treatment with trehalose provoked a relevant anti-amyloidogenic effect in neurons from an AD mouse model that was not mediated by autophagy. Trehalose treatment reduced secreted Aβ levels in a manner unrelated to its intracellular accumulation or its elimination through endocytosis or enzymatic degradation. Moreover, the levels of Aβ precursor protein (APP) and beta-secretase (BACE1) remained unaltered, as well as the proper acidic condition of the endo-lysosome system. Instead, our results support that the neuroprotective effect of trehalose was mediated by a reduced colocalization of APP and BACE1 in the cell, and, therefore, a lower amyloidogenic processing of APP. This observation illustrates that the determination of the mechanism, or mechanisms, that associate APP and BACE is a relevant therapeutic target to investigate.
Collapse
|
3
|
Nie R, Wu Z, Ni J, Zeng F, Yu W, Zhang Y, Kadowaki T, Kashiwazaki H, Teeling JL, Zhou Y. Porphyromonas gingivalis Infection Induces Amyloid-β Accumulation in Monocytes/Macrophages. J Alzheimers Dis 2019; 72:479-494. [DOI: 10.3233/jad-190298] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Ran Nie
- Department of Dental Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
- OBT Research Center, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
| | - Junjun Ni
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
| | - Fan Zeng
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
| | - Weixian Yu
- Jilin Provincial Key Laboratory of Tooth Development and Bone Remodeling, Jilin University, Changchun, China
| | - Yufeng Zhang
- Gerontal Department of Stomatology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Tomoko Kadowaki
- Division of Frontier Life Science, Department of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Haruhiko Kashiwazaki
- Section of Geriatric Dentistry and Perioperative Medicine in Dentistry, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
| | - Jessica L. Teeling
- Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom
| | - Yanmin Zhou
- Department of Dental Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| |
Collapse
|
4
|
Becker-Pauly C, Pietrzik CU. Mice are not Men: ADAM30 Findings Emphasize a Broader Look Towards Murine Alzheimer's Disease Models. EBioMedicine 2016; 9:19-20. [PMID: 27396345 PMCID: PMC4972564 DOI: 10.1016/j.ebiom.2016.06.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
5
|
Cysteine proteases as therapeutic targets: does selectivity matter? A systematic review of calpain and cathepsin inhibitors. Acta Pharm Sin B 2015; 5:506-19. [PMID: 26713267 PMCID: PMC4675809 DOI: 10.1016/j.apsb.2015.08.001] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/09/2015] [Accepted: 07/14/2015] [Indexed: 01/17/2023] Open
Abstract
Cysteine proteases continue to provide validated targets for treatment of human diseases. In neurodegenerative disorders, multiple cysteine proteases provide targets for enzyme inhibitors, notably caspases, calpains, and cathepsins. The reactive, active-site cysteine provides specificity for many inhibitor designs over other families of proteases, such as aspartate and serine; however, a) inhibitor strategies often use covalent enzyme modification, and b) obtaining selectivity within families of cysteine proteases and their isozymes is problematic. This review provides a general update on strategies for cysteine protease inhibitor design and a focus on cathepsin B and calpain 1 as drug targets for neurodegenerative disorders; the latter focus providing an interesting query for the contemporary assumptions that irreversible, covalent protein modification and low selectivity are anathema to therapeutic safety and efficacy.
Collapse
Key Words
- AD, Alzheimer׳s disease
- ALS, amyotrophic lateral sclerosis
- APP, amyloid precursor protein
- APP/PS1, Aβ overexpressing mice APP (K670N/M671L) and PS1 (M146L) mutants
- Ala, alanine
- Alzheimer׳s disease
- AppLon, London familial amyloid precursor protein mutation, APP (V717I)
- AppSwe, Swedish amyloid precursor protein mutation, APP (K670N/M671L)
- Arg, arginine
- Aβ, amyloid β
- Aβ1-42, amyloid β, 42 amino acid protein
- BACE-1, β-amyloid cleaving enzyme
- BBB, blood–brain barrier
- CANP, calcium-activated neutral protease
- CNS, central nervous system
- CREB, cyclic adenosine monophosphate response element binding protein
- CaMKII, Ca2+/calmodulin-dependent protein kinases II
- Calpain
- Cathepsin
- Cdk5/p35, activator of cyclin-dependent kinase 5
- Cysteine protease
- DTT, dithioerythritol
- EGFR, epidermal growth factor receptor
- ERK1/2, extracellular signal-regulated kinase 1/2
- Enzyme inhibitors
- GSH, glutathione
- Gln, glutamine
- Glu, glutamic acid
- Gly, glutamine
- Hsp70.1, heat shock protein 70.1
- Ile, isoleucine
- KO, knockout
- Leu, leucine
- Lys, lysine
- MAP-2, microtubule-associated protein 2
- MMP-9, matrix metalloproteinase 9
- Met, methionine
- NFT, neurofibrilliary tangles
- Neurodegeneration
- Nle, norleucine
- PD, Parkinson׳s disease
- PK, pharmacokinetic
- PKC, protein kinase C
- PTP1B, protein-tyrosine phosphatase 1B
- Phe, phenylalanine
- Pro, proline
- SP, senile plaques
- TBI, traumatic brain injury
- TNF, tumor necrosis factor
- Thr, threonine
- Tyr, tyrosine
- Val, valine
- WRX, Trp-Arg containing epoxysuccinate cysteine protease inhibitor
- WT, wildtype
- isoAsp, isoaspartate
- pGlu, pyroglutamate
- pyroGluAβ, pyroglutamate-amyloid β
Collapse
|
6
|
Hook G, Yu J, Toneff T, Kindy M, Hook V. Brain pyroglutamate amyloid-β is produced by cathepsin B and is reduced by the cysteine protease inhibitor E64d, representing a potential Alzheimer's disease therapeutic. J Alzheimers Dis 2015; 41:129-49. [PMID: 24595198 DOI: 10.3233/jad-131370] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pyroglutamate amyloid-β peptides (pGlu-Aβ) are particularly pernicious forms of amyloid-β peptides (Aβ) present in Alzheimer's disease (AD) brains. pGlu-Aβ peptides are N-terminally truncated forms of full-length Aβ peptides (flAβ(1-40/42)) in which the N-terminal glutamate is cyclized to pyroglutamate to generate pGlu-Aβ(3-40/42). β-secretase cleavage of amyloid-β precursor protein (AβPP) produces flAβ(1-40/42), but it is not yet known whether the β-secretase BACE1 or the alternative β-secretase cathepsin B (CatB) participate in the production of pGlu-Aβ. Therefore, this study examined the effects of gene knockout of these proteases on brain pGlu-Aβ levels in transgenic AβPPLon mice, which express AβPP isoform 695 and have the wild-type (wt) β-secretase activity found in most AD patients. Knockout or overexpression of the CatB gene reduced or increased, respectively, pGlu-Aβ(3-40/42), flAβ(1-40/42), and pGlu-Aβ plaque load, but knockout of the BACE1 gene had no effect on those parameters in the transgenic mice. Treatment of AβPPLon mice with E64d, a cysteine protease inhibitor of CatB, also reduced brain pGlu-Aβ(3-42), flAβ(1-40/42), and pGlu-Aβ plaque load. Treatment of neuronal-like chromaffin cells with CA074Me, an inhibitor of CatB, resulted in reduced levels of pGlu-Aβ(3-40) released from the activity-dependent, regulated secretory pathway. Moreover, CatB knockout and E64d treatment has been previously shown to improve memory deficits in the AβPPLon mice. These data illustrate the role of CatB in producing pGlu-Aβ and flAβ that participate as key factors in the development of AD. The advantages of CatB inhibitors, especially E64d and its derivatives, as alternatives to BACE1 inhibitors in treating AD patients are discussed.
Collapse
Affiliation(s)
- Gregory Hook
- American Life Science Pharmaceuticals, La Jolla, CA, USA
| | - Jin Yu
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA Ralph H. Johnson VA Medical Center, Charleston, SC, USA
| | - Thomas Toneff
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Departments of Neurosciences and Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Mark Kindy
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA Ralph H. Johnson VA Medical Center, Charleston, SC, USA
| | - Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Departments of Neurosciences and Pharmacology, University of California, San Diego, La Jolla, CA, USA
| |
Collapse
|
7
|
Tam JHK, Seah C, Pasternak SH. The Amyloid Precursor Protein is rapidly transported from the Golgi apparatus to the lysosome and where it is processed into beta-amyloid. Mol Brain 2014; 7:54. [PMID: 25085554 PMCID: PMC4237969 DOI: 10.1186/s13041-014-0054-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/23/2014] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is characterized by cerebral deposition of β-amyloid peptide (Aβ). Aβ is produced by sequential cleavage of the Amyloid Precursor Protein (APP) by β- and γ-secretases. Many studies have demonstrated that the internalization of APP from the cell surface can regulate Aβ production, although the exact organelle in which Aβ is produced remains contentious. A number of recent studies suggest that intracellular trafficking also plays a role in regulating Aβ production, but these pathways are relatively under-studied. The goal of this study was to elucidate the intracellular trafficking of APP, and to examine the site of intracellular APP processing. RESULTS We have tagged APP on its C-terminal cytoplasmic tail with photoactivatable Green Fluorescent Protein (paGFP). By photoactivating APP-paGFP in the Golgi, using the Golgi marker Galactosyltranferase fused to Cyan Fluorescent Protein (GalT-CFP) as a target, we are able to follow a population of nascent APP molecules from the Golgi to downstream compartments identified with compartment markers tagged with red fluorescent protein (mRFP or mCherry); including rab5 (early endosomes) rab9 (late endosomes) and LAMP1 (lysosomes). Because γ-cleavage of APP releases the cytoplasmic tail of APP including the photoactivated GFP, resulting in loss of fluorescence, we are able to visualize the cleavage of APP in these compartments. Using APP-paGFP, we show that APP is rapidly trafficked from the Golgi apparatus to the lysosome; where it is rapidly cleared. Chloroquine and the highly selective γ-secretase inhibitor, L685, 458, cause the accumulation of APP in lysosomes implying that APP is being cleaved by secretases in the lysosome. The Swedish mutation dramatically increases the rate of lysosomal APP processing, which is also inhibited by chloroquine and L685, 458. By knocking down adaptor protein 3 (AP-3; a heterotetrameric protein complex required for trafficking many proteins to the lysosome) using siRNA, we are able to reduce this lysosomal transport. Blocking lysosomal transport of APP reduces Aβ production by more than a third. CONCLUSION These data suggests that AP-3 mediates rapid delivery of APP to lysosomes, and that the lysosome is a likely site of Aβ production.
Collapse
Affiliation(s)
- Joshua HK Tam
- J. Allyn Taylor Centre for Cell Biology, Molecular Brain Research Group, Robarts Research Institute, 100 Perth Drive, London N6A 5K8, Ontario, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London N6A 5K8, Ontario, Canada
| | - Claudia Seah
- J. Allyn Taylor Centre for Cell Biology, Molecular Brain Research Group, Robarts Research Institute, 100 Perth Drive, London N6A 5K8, Ontario, Canada
| | - Stephen H Pasternak
- J. Allyn Taylor Centre for Cell Biology, Molecular Brain Research Group, Robarts Research Institute, 100 Perth Drive, London N6A 5K8, Ontario, Canada
- Department of Clinical Neurological Sciences, London N6A 5K8, Ontario, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London N6A 5K8, Ontario, Canada
| |
Collapse
|
8
|
Polajnar M, Zavašnik-Bergant T, Škerget K, Vizovišek M, Vidmar R, Fonović M, Kopitar-Jerala N, Petrovič U, Navarro S, Ventura S, Žerovnik E. Human stefin B role in cell's response to misfolded proteins and autophagy. PLoS One 2014; 9:e102500. [PMID: 25047918 PMCID: PMC4105463 DOI: 10.1371/journal.pone.0102500] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/18/2014] [Indexed: 11/30/2022] Open
Abstract
Alternative functions, apart from cathepsins inhibition, are being discovered for stefin B. Here, we investigate its role in vesicular trafficking and autophagy. Astrocytes isolated from stefin B knock-out (KO) mice exhibited an increased level of protein aggregates scattered throughout the cytoplasm. Addition of stefin B monomers or small oligomers to the cell medium reverted this phenotype, as imaged by confocal microscopy. To monitor the identity of proteins embedded within aggregates in wild type (wt) and KO cells, the insoluble cell lysate fractions were isolated and analyzed by mass spectrometry. Chaperones, tubulins, dyneins, and proteosomal components were detected in the insoluble fraction of wt cells but not in KO aggregates. In contrast, the insoluble fraction of KO cells exhibited increased levels of apolipoprotein E, fibronectin, clusterin, major prion protein, and serpins H1 and I2 and some proteins of lysosomal origin, such as cathepsin D and CD63, relative to wt astrocytes. Analysis of autophagy activity demonstrated that this pathway was less functional in KO astrocytes. In addition, synthetic dosage lethality (SDL) gene interactions analysis in Saccharomyces cerevisiae expressing human stefin B suggests a role in transport of vesicles and vacuoles These activities would contribute, directly or indirectly to completion of autophagy in wt astrocytes and would account for the accumulation of protein aggregates in KO cells, since autophagy is a key pathway for the clearance of intracellular protein aggregates.
Collapse
Affiliation(s)
- Mira Polajnar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Tina Zavašnik-Bergant
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Katja Škerget
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Department of Molecular and Biomedical Science, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Matej Vizovišek
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Robert Vidmar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Marko Fonović
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Nataša Kopitar-Jerala
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Uroš Petrovič
- Department of Molecular and Biomedical Science, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Susanna Navarro
- Institute of Biotechnology and Biomedicine, Autonomous University of Barcelona, Bellaterra, Spain
| | - Salvador Ventura
- Institute of Biotechnology and Biomedicine, Autonomous University of Barcelona, Bellaterra, Spain
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
- CipKeBip - Center of Excellence for integrated approaches in chemistry and biology of proteins, Ljubljana, Slovenia
- * E-mail:
| |
Collapse
|
9
|
Wang Y, Thinakaran G, Kar S. Overexpression of the IGF-II/M6P receptor in mouse fibroblast cell lines differentially alters expression profiles of genes involved in Alzheimer's disease-related pathology. PLoS One 2014; 9:e98057. [PMID: 24846272 PMCID: PMC4028253 DOI: 10.1371/journal.pone.0098057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/25/2014] [Indexed: 11/29/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common type of senile dementia affecting elderly people. The processing of amyloid precursor protein (APP) leading to the generation of β-amyloid (Aβ) peptide contributes to neurodegeneration and development of AD pathology. The endocytic trafficking pathway, which comprises of the endosomes and lysosomes, acts as an important site for Aβ generation, and endocytic dysfunction has been linked to increased Aβ production and loss of neurons in AD brains. Since insulin-like growth factor-II (IGF-II) receptor plays a critical role in the transport of lysosomal enzymes from the trans-Golgi network to endosomes, it is likely that the receptor may have a role in regulating Aβ metabolism in AD pathology. However, very little is known on how altered levels of the IGF-II receptor can influence the expression/function of various molecules involved in AD pathology. To address this issue, we evaluated the expression profiles of 87 selected genes related to AD pathology in mouse fibroblast MS cells that are deficient in murine IGF-II receptor and corresponding MS9II cells overexpressing ∼500 times the human IGF-II receptors. Our results reveal that an elevation in IGF-II receptor levels alters the expression profiles of a number of genes including APP as well as enzymes regulating Aβ production, degradation and clearance mechanisms. Additionally, it influences the expression of various lysosomal enzymes and protein kinases that are involved in Aβ toxicity. IGF-II receptor overexpression also alters expression of several genes involved in intracellular signalling as well as cholesterol metabolism, which play a critical role in AD pathology. The altered gene profiles observed in this study closely match with the corresponding protein levels, with a few exceptions. These results, taken together, suggest that an elevation in IGF-II receptor levels can influence the expression profiles of transcripts as well as proteins that are involved in AD pathogenesis.
Collapse
Affiliation(s)
- Yanlin Wang
- Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
| | - Gopal Thinakaran
- Departments of Neurobiology, Neurology and Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Satyabrata Kar
- Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
- Department of Medicine (Neurology), University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| |
Collapse
|
10
|
Lahiri DK, Maloney B, Long JM, Greig NH. Lessons from a BACE1 inhibitor trial: off-site but not off base. Alzheimers Dement 2014; 10:S411-9. [PMID: 24530026 DOI: 10.1016/j.jalz.2013.11.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 11/04/2013] [Accepted: 11/25/2013] [Indexed: 11/19/2022]
Abstract
Alzheimer's disease (AD) is characterized by formation of neuritic plaque primarily composed of a small filamentous protein called amyloid-β peptide (Aβ). The rate-limiting step in the production of Aβ is the processing of Aβ precursor protein (APP) by β-site APP-cleaving enzyme (BACE1). Hence, BACE1 activity plausibly plays a rate-limiting role in the generation of potentially toxic Aβ within brain and the development of AD, thereby making it an interesting drug target. A phase II trial of the promising LY2886721 inhibitor of BACE1 was suspended in June 2013 by Eli Lilly and Co., due to possible liver toxicity. This outcome was apparently a surprise to the study's team, particularly since BACE1 knockout mice and mice treated with the drug did not show such liver toxicity. Lilly proposed that the problem was not due to LY2886721 anti-BACE1 activity. We offer an alternative hypothesis, whereby anti-BACE1 activity may induce apparent hepatotoxicity through inhibiting BACE1's processing of β-galactoside α-2,6-sialyltransferase I (STGal6 I). In knockout mice, paralogues, such as BACE2 or cathepsin D, could partially compensate. Furthermore, the short duration of animal studies and short lifespan of study animals could mask effects that would require several decades to accumulate in humans. Inhibition of hepatic BACE1 activity in middle-aged humans would produce effects not detectable in mice. We present a testable model to explain the off-target effects of LY2886721 and highlight more broadly that so-called off-target drug effects might actually represent off-site effects that are not necessarily off-target. Consideration of this concept in forthcoming drug design, screening, and testing programs may prevent such failures in the future.
Collapse
Affiliation(s)
- Debomoy K Lahiri
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Bryan Maloney
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Justin M Long
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Nigel H Greig
- Laboratory of Translational Gerontology, Intramural Research Program, National Institute of Aging, National Institutes of Health, Baltimore, MD, USA
| |
Collapse
|
11
|
Bien J, Jefferson T, Causević M, Jumpertz T, Munter L, Multhaup G, Weggen S, Becker-Pauly C, Pietrzik CU. The metalloprotease meprin β generates amino terminal-truncated amyloid β peptide species. J Biol Chem 2012; 287:33304-13. [PMID: 22879596 DOI: 10.1074/jbc.m112.395608] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amyloid β (Aβ) peptide, which is abundantly found in the brains of patients suffering from Alzheimer disease, is central in the pathogenesis of this disease. Therefore, to understand the processing of the amyloid precursor protein (APP) is of critical importance. Recently, we demonstrated that the metalloprotease meprin β cleaves APP and liberates soluble N-terminal APP (N-APP) fragments. In this work, we present evidence that meprin β can also process APP in a manner reminiscent of β-secretase. We identified cleavage sites of meprin β in the amyloid β sequence of the wild type and Swedish mutant of APP at positions p1 and p2, thereby generating Aβ variants starting at the first or second amino acid residue. We observed even higher kinetic values for meprin β than BACE1 for both the wild type and the Swedish mutant APP form. This enzymatic activity of meprin β on APP and Aβ generation was also observed in the absence of BACE1/2 activity using a β-secretase inhibitor and BACE knock-out cells, indicating that meprin β acts independently of β-secretase.
Collapse
Affiliation(s)
- Jessica Bien
- Institute of Pathobiochemistry, University Medical Centre of the Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Dopamine induces apoptosis in APPswe-expressing Neuro2A cells following Pepstatin-sensitive proteolysis of APP in acid compartments. Brain Res 2012; 1471:102-17. [DOI: 10.1016/j.brainres.2012.06.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/14/2012] [Accepted: 06/21/2012] [Indexed: 11/23/2022]
|
13
|
Abou-Gharbia M, Childers W. Targeting neurodegenerative diseases: Drug discovery in a challenging arena. PURE APPL CHEM 2012. [DOI: 10.1351/pac-con-11-11-09] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neurodegenerative diseases represent one of the health care community’s truly unmet medical needs. They can be loosely classified into two categories, acute and chronic. One of the best known chronic neurodegenerative diseases, Alzheimer’s disease, represents a serious health care problem that may well exceed the limits of current fiscal and care giver resources. No disease-modifying therapeutic agents have been identified, and the few available symptomatic treatments possess limitations in their duration of action and side effects. Despite decades of drug discovery research and numerous clinical trials, no truly effective treatment for stroke, the most prevalent acute neurodegenerative disease, has been identified. This article summarizes two recent drug discovery projects, one targeting Alzheimer’s disease and the other targeting ischemic stroke. Both projects involved design, synthesis, and biological evaluation of a novel series of heterocyclic derivatives.
Collapse
Affiliation(s)
- Magid Abou-Gharbia
- 1Moulder Center for Drug Discovery Research, School of Pharmacy, Temple University, 3307 North Broad Street, Philadelphia, PA 18938, USA
| | - Wayne Childers
- 1Moulder Center for Drug Discovery Research, School of Pharmacy, Temple University, 3307 North Broad Street, Philadelphia, PA 18938, USA
| |
Collapse
|
14
|
Hook G, Hook V, Kindy M. The cysteine protease inhibitor, E64d, reduces brain amyloid-β and improves memory deficits in Alzheimer's disease animal models by inhibiting cathepsin B, but not BACE1, β-secretase activity. J Alzheimers Dis 2012; 26:387-408. [PMID: 21613740 DOI: 10.3233/jad-2011-110101] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cysteine protease cathepsin B is a potential drug target for reducing brain amyloid-β (Aβ) and improving memory in Alzheimer's disease (AD), as reduction of cathepsin B in transgenic mice expressing human wild-type amyloid-β protein precursor (AβPP) results in significantly decreased brain Aβ. Cathepsin B cleaves the wild-type β-secretase site sequence in AβPP to produce Aβ, and cathepsin B inhibitors administered to animal models expressing AβPP containing the wild-type β-secretase site sequence reduce brain Aβ in a manner consistent with β-secretase inhibition. But such inhibitors could act either by direct inhibition of cathepsin B β-secretase activity or by off-target inhibition of the other β-secretase, the aspartyl protease BACE1. To evaluate that issue, we orally administered a cysteine protease inhibitor, E64d, to normal guinea pigs or transgenic mice expressing human AβPP, both of which express the human wild-type β-secretase site sequence. In guinea pigs, oral E64d administration caused a dose-dependent reduction of up to 92% in brain, CSF, and plasma of Aβ40 and Aβ42, a reduction of up to 50% in the C-terminal β-secretase fragment (CTFβ), and a 91% reduction in brain cathepsin B activity, but increased brain BACE1 activity by 20%. In transgenic AD mice, oral E64d administration improved memory deficits and reduced brain Aβ40 and Aβ42, amyloid plaque, brain CTFβ, and brain cathepsin B activity, but increased brain BACE1 activity. We conclude that E64d likely reduces brain Aβ by inhibiting cathepsin B and not BACE1 β-secretase activity and that E64d therefore may have potential for treating AD patients.
Collapse
Affiliation(s)
- Gregory Hook
- American Life Science Pharmaceuticals, San Diego, CA 92109, USA.
| | | | | |
Collapse
|
15
|
The green tea polyphenol (2)-epigallocatechin-3-gallate (EGCG) is not a β-secretase inhibitor. Bioorg Med Chem Lett 2011; 22:1408-14. [PMID: 22225636 DOI: 10.1016/j.bmcl.2011.12.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/21/2011] [Accepted: 12/07/2011] [Indexed: 12/14/2022]
Abstract
(2)-Epigallocatechin-3-gallate (EGCG) is a major polyphenolic component of green tea. A number of studies have demonstrated EGCG has the possibility for delaying the onset or retarding the progression of Alzheimer's disease (AD) and indicated EGCG possess inhibition of β-secretase activity. We utilized homogeneous time-resolved fluorescence assay with a substrate Eu-CEVNLDAEFK-Qsy7 to screen β-secretase inhibitor in a cell-free system and AlphaLISA assay in cell system. The results first showed that EGCG had significant inhibition of β-secretase activity with IC(50) value of 7.57 × 10(-7)M in screening assay, but then we found EGCG had significant fluorescence-quenching effect in confirming assay, this indicates EGCG has the false positive β-secretase inhibitory activity. Furthermore, the followed AlphaLISA assay based on cell showed EGCG did not reduce the β-amyloid 1-40 secretion in HuAPPswe/HuBACE1 Chinese hamster ovary cell without affecting cell viability. Therefore our findings indicate EGCG do not inhibit β-secretase cleavage activity. Overall this study illustrates that EGCG is not a β-secretase inhibitor based on the compelling data. This provides further support that the choice of complementary assay format or technology is a critical factor in molecular screening and drug development for improving the hit-finding capability and efficiency.
Collapse
|
16
|
Zhang H, Ma Q, Zhang YW, Xu H. Proteolytic processing of Alzheimer's β-amyloid precursor protein. J Neurochem 2011; 120 Suppl 1:9-21. [PMID: 22122372 DOI: 10.1111/j.1471-4159.2011.07519.x] [Citation(s) in RCA: 233] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
β-Amyloid precursor protein (APP) is a critical factor in the pathogenesis of Alzheimer's disease (AD). APP undergoes post-translational proteolysis/processing to generate the hydrophobic β-amyloid (Aβ) peptides. Deposition of Aβ in the brain, forming oligomeric Aβ and plaques, is identified as one of the key pathological hallmarks of AD. The processing of APP to generate Aβ is executed by β- and γ-secretase and is highly regulated. Aβ toxicity can lead to synaptic dysfunction, neuronal cell death, impaired learning/memory and abnormal behaviors in AD models in vitro and in vivo. Aside from Aβ, proteolytic cleavages of APP can also give rise to the APP intracellular domain, reportedly involved in multiple types of cellular events such as gene transcription and apoptotic cell death. In addition to amyloidogenic processing, APP can also be cleaved by α-secretase to form a soluble or secreted APP ectodomain (sAPP-α) that has been shown to be mostly neuro-protective. In this review, we describe the mechanisms involved in APP metabolism and the likely functions of its various proteolytic products to give a better understanding of the patho/physiological functions of APP.
Collapse
Affiliation(s)
- Han Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
| | - Qilin Ma
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
| |
Collapse
|
17
|
Schechter I, Ziv E. Cathepsins S, B and L with aminopeptidases display β-secretase activity associated with the pathogenesis of Alzheimer's disease. Biol Chem 2011; 392:555-69. [PMID: 21585286 DOI: 10.1515/bc.2011.054] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
β-site APP-cleaving enzyme (BACE1) cleaves the wild type (WT) β-site very slowly (k(cat)/K(m): 46.6 m(-1) s(-1)). Therefore we searched for additional β-secretases and identified three cathepsins that split the WT β-site much faster. Human cathepsin S cleaves the WT β-site (k(cat)/K(m): 54 700 m(-1) s(-1)) 1170-fold faster than BACE1 and cathepsins B and L are 440- and 74-fold faster than BACE1, respectively. These cathepsins split two bonds flanking the WT β-site (K-MD-A), where the K-M bond (85%) is cleaved more efficiently than the D-A bond (15%). Cleavage at the major K-M bond yields Aβ (amyloid β-peptide) extended by N-terminal Met that should be removed to generate Aβ initiated by Asp1. The activity of cytosol and microsomal aminopeptidases on relevant peptides revealed rapid removal of N-terminal Met but not N-terminal Asp. Brain aminopeptidases showed similar specificity. Thus, aminopeptidases would convert Aβ extended by Met into regular Aβ (Asp1) found in amyloid plaques. Earlier studies indicate that Aβ is likely produced in the endosome and lysosome system where cathepsins S, B and L are localized and cysteine cathepsin inhibitors reduce the level of Aβ in cells and animals. Taken together, cathepsins S, B and L deserve further evaluation as therapeutic targets to develop disease modifying drugs to treat Alzheimer's disease.
Collapse
|
18
|
Chow VW, Mattson MP, Wong PC, Gleichmann M. An overview of APP processing enzymes and products. Neuromolecular Med 2010; 12:1-12. [PMID: 20232515 DOI: 10.1007/s12017-009-8104-z] [Citation(s) in RCA: 446] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The generation of amyloid beta-peptide (A beta) by enzymatic cleavages of the beta-amyloid precursor protein (APP) has been at the center of Alzheimer's disease (AD) research. While the basic process of beta- and gamma-secretase-mediated generation of A beta is text book knowledge, new aspects of A beta and other cleavage products have emerged in recent years. Also our understanding of the enzymes involved in APP proteolysis has increased dramatically. All of these discoveries contribute to a more complete understanding of APP processing and the physiologic and pathologic roles of its secreted and intracellular protein products. Understanding APP processing is important for any therapeutic strategy aimed at reducing A beta levels in AD. In this review, we provide a concise description of the current state of understanding the enzymes involved in APP processing, the cleavage products generated by different processing patterns, and the potential functions of those cleavage products.
Collapse
Affiliation(s)
- Vivian W Chow
- Department of Pathology, Division of Neuropathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | | | | |
Collapse
|
19
|
Alterations in mRNA expression of BACE1, cathepsin B, and glutaminyl cyclase in mice ischemic brain. Neuroreport 2010; 20:1456-60. [PMID: 19809370 DOI: 10.1097/wnr.0b013e328332024a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The relationship between cerebral ischemia and Alzheimer's disease has been evaluated extensively. However, the association between cerebral ischemia and the deposition of beta-amyloid (Abeta) remains to be clarified. Here, we used mice bilateral common carotid artery ligation model to investigate the alterations in mRNA expression of Abeta precursor protein cleavage enzyme 1(BACE1), cathepsin B, and glutaminyl cyclase after transient global cerebral ischemia. The reverse-transcriptase PCR assay showed that the expressions of these three Abeta-metabolism-related genes were upregulated in brain with different manner. It indicates that all these three Abeta-metabolism-related genes may participate in the acute and chronic Abeta generation after transient cerebral ischemia, and will be helpful to understand the mechanisms underlying the linkage of brain ischemia and Alzheimer's disease.
Collapse
|
20
|
Abstract
Alzheimer's disease (AD) pathogenesis is widely believed to be driven by the production and deposition of the amyloid-beta peptide (Abeta). For many years, investigators have been puzzled by the weak to nonexistent correlation between the amount of neuritic plaque pathology in the human brain and the degree of clinical dementia. Recent advances in our understanding of the development of amyloid pathology have helped solve this mystery. Substantial evidence now indicates that the solubility of Abeta, and the quantity of Abeta in different pools, may be more closely related to disease state. The composition of these pools of Abeta reflects different populations of amyloid deposits and has definite correlates with the clinical status of the patient. Imaging technologies, including new amyloid imaging agents based on the chemical structure of histologic dyes, are now making it possible to track amyloid pathology along with disease progression in the living patient. Interestingly, these approaches indicate that the Abeta deposited in AD is different from that found in animal models. In general, deposited Abeta is more easily cleared from the brain in animal models and does not show the same physical and biochemical characteristics as the amyloid found in AD. This raises important issues regarding the development and testing of future therapeutic agents.
Collapse
Affiliation(s)
- M Paul Murphy
- Department of Molecular and Cellular Biochemistry and the Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA.
| | | |
Collapse
|
21
|
Ahmed RR, Holler CJ, Webb RL, Li F, Beckett TL, Murphy MP. BACE1 and BACE2 enzymatic activities in Alzheimer's disease. J Neurochem 2009; 112:1045-53. [PMID: 19968762 DOI: 10.1111/j.1471-4159.2009.06528.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
beta-Secretase is the rate limiting enzymatic activity in the production of the amyloid-beta peptide (Abeta) and is thought to be involved in Alzheimer's disease (AD) pathogenesis. Although BACE1 (beta-site APP Cleaving Enzyme 1, EC 3.4.23.46) has received significant attention, the related BACE2 (EC 3.4.23.45) has not. Though BACE2 is also expressed in the brain, its potential role in AD has not been resolved. In this study, we compared the activities of both BACE1 and BACE2, which were isolated from the same samples of frontal cortex from both AD-affected individuals and age-matched controls. BACE1 activity showed a significant positive correlation with the amount of extractable Abeta, and BACE1 protein and activity were significantly increased in AD cases. Unexpectedly, there were substantial total amounts of BACE2 protein and enzymatic activity in the human brain. BACE2 activity did not change significantly in the AD brain, and was not related to Abeta concentration. These data indicate that BACE1 likely accounts for most of the Abeta produced in the human brain, and that BACE2 activity is not a likely contributor. However, as both forms of BACE compete for the same substrate pool, even small changes in BACE2 activity could have consequences for human disease.
Collapse
Affiliation(s)
- Rachel R Ahmed
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA
| | | | | | | | | | | |
Collapse
|
22
|
|
23
|
Hook VYH, Kindy M, Reinheckel T, Peters C, Hook G. Genetic cathepsin B deficiency reduces beta-amyloid in transgenic mice expressing human wild-type amyloid precursor protein. Biochem Biophys Res Commun 2009; 386:284-8. [PMID: 19501042 DOI: 10.1016/j.bbrc.2009.05.131] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 05/12/2009] [Indexed: 10/20/2022]
Abstract
Neurotoxic beta-amyloid (Abeta) peptides participate in Alzheimer's disease (AD); therefore, reduction of Abeta generated from APP may provide a therapeutic approach for AD. Gene knockout studies in transgenic mice producing human Abeta may identify targets for reducing Abeta. This study shows that knockout of the cathepsin B gene in mice expressing human wild-type APP (hAPPwt) results in substantial decreases in brain Abeta40 and Abeta42 by 67% and decreases in levels of the C-terminal beta-secretase fragment (CTFbeta) derived from APP. In contrast, knockout of cathepsin B in mice expressing hAPP with the rare Swedish (Swe) and Indiana (Ind) mutations had no effect on Abeta. The difference in reduction of Abeta in hAPPwt mice, but not in hAPPSwe/Ind mice, shows that the transgenic model can affect cathepsin B gene knockout results. Since most AD patients express hAPPwt, these data validate cathepsin B as a target for development of inhibitors to lower Abeta in AD.
Collapse
Affiliation(s)
- Vivian Y H Hook
- Depts of Neurosciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093-0744, USA.
| | | | | | | | | |
Collapse
|
24
|
Böhme L, Hoffmann T, Manhart S, Wolf R, Demuth HU. Isoaspartate-containing amyloid precursor protein-derived peptides alter efficacy and specificity of potential beta-secretases. Biol Chem 2008; 389:1055-66. [PMID: 18979630 DOI: 10.1515/bc.2008.125] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Neuritic plaques of Alzheimer patients are composed of multiple protein components. Among them, the amyloid beta-peptides (Abeta) 1-40/42 and further N- and C-terminally modified fragments of Abeta are highly abundant. Most prominent are the isoaspartate (isoAsp)-Abeta peptides and pyroglutamyl (pGlu)-Abeta. While pGlu-Abeta can only be formed from an N-terminal glutamate by glutaminyl cyclase, spontaneous isoAsp-isomerization cannot occur at an N-terminal aspartate of peptides. This means that isoAsp-Abeta formation must precede proteolysis of the amyloid precursor protein (APP). Abeta generation from APP by beta- and gamma-secretases initiates the amyloid peptide aggregation and deposition process. Two aspartate proteases have been identified as secretases: BACE-1 (beta-site amyloid precursor protein cleaving enzyme) and the intramembrane gamma-secretase multiprotein complex. However, recent evidence supports more than one beta-secretase initiating this cascade. Formation of Abeta1-40/42 was predominantly studied by expression of mutated human APP sequences in cell culture and transgenic animals, generating Abeta fragments that did not contain such multiple posttranslational modifications as in Alzheimer's disease. This prompted us to investigate the catalytic turnover of Asp- or isoAsp-containing APP-derived peptide sequences by BACE-1 and cathepsin B, another potential beta-secretase. While cathepsin B is more effective than BACE-1 in processing the Asp-containing peptide derivatives, only cathepsin B can cleave the isoAsp-containing peptides, which occurs with high catalytic efficiency.
Collapse
Affiliation(s)
- Livia Böhme
- Probiodrug AG, Biocenter, Weinbergweg 22, D-06120 Halle/Saale, Germany
| | | | | | | | | |
Collapse
|
25
|
Hook V, Schechter I, Demuth HU, Hook G. Alternative pathways for production of beta-amyloid peptides of Alzheimer's disease. Biol Chem 2008; 389:993-1006. [PMID: 18979625 DOI: 10.1515/bc.2008.124] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This highlight article describes three Alzheimer's disease (AD) studies presented at the 5th General Meeting of the International Proteolysis Society that address enzymatic mechanisms for producing neurotoxic beta-amyloid (Abeta) peptides. One group described the poor kinetics of BACE 1 for cleaving the wild-type (WT) beta-secretase site of APP found in most AD patients. They showed that cathepsin D displays BACE 1-like specificity and cathepsin D is 280-fold more abundant in human brain than BACE 1. Nevertheless, as BACE 1 and cathepsin D show poor activity towards the WT beta-secretase site, they suggested continuing the search for additional beta-secretase(s). The second group reported cathepsin B as an alternative beta-secretase possessing excellent kinetic efficiency and specificity for the WT beta-secretase site. Significantly, inhibitors of cathepsin B improved memory, with reduced amyloid plaques and decreased Abeta(40/42) in brains of AD animal models expressing amyloid precursor protein containing the WT beta-secretase site. The third group addressed isoaspartate and pyroglutamate (pGlu) posttranslational modifications of Abeta. Results showed that cathepsin B, but not BACE 1, efficiently cleaves the WT beta-secretase isoaspartate site. Furthermore, cyclization of N-terminal Glu by glutaminyl cyclase generates highly amyloidogenic pGluAbeta(3-40/42). These presentations suggest cathepsin B and glutaminyl cyclase as potential new AD therapeutic targets.
Collapse
Affiliation(s)
- Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093, USA.
| | | | | | | |
Collapse
|
26
|
Hook V, Schechter I, Demuth HU, Hook G. Alternative pathways for production of β-amyloid peptides of Alzheimer's disease. Biol Chem 2008. [DOI: 10.1515/bc.2008.124_bchm.just-accepted] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|