1
|
Peng W, Minakaki G, Nguyen M, Krainc D. Preserving Lysosomal Function in the Aging Brain: Insights from Neurodegeneration. Neurotherapeutics 2019; 16:611-634. [PMID: 31183763 PMCID: PMC6694346 DOI: 10.1007/s13311-019-00742-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Lysosomes are acidic, membrane-bound organelles that serve as the primary catabolic compartment of the cell. They are crucial to a variety of cellular processes from nutrient storage to autophagy. Given the diversity of lysosomal functions, it is unsurprising that lysosomes are also emerging as important players in aging. Lysosomal dysfunction is implicated in several aging-related neurodegenerative diseases including Alzheimer's, Parkinson's, amyotrophic lateral sclerosis/frontotemporal dementia, and Huntington's. Although the precise role of lysosomes in the aging brain is not well-elucidated, some insight into their function has been gained from our understanding of the pathophysiology of age-dependent neurodegenerative diseases. Therapeutic strategies targeting lysosomes and autophagic machinery have already been tested in several of these diseases with promising results, suggesting that improving lysosomal function could be similarly beneficial in preserving function in the aging brain.
Collapse
Affiliation(s)
- Wesley Peng
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, 60611, USA
| | - Georgia Minakaki
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, 60611, USA
| | - Maria Nguyen
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, 60611, USA
| | - Dimitri Krainc
- The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, 60611, USA.
| |
Collapse
|
2
|
Li X, Cui J, Yu Y, Li W, Hou Y, Wang X, Qin D, Zhao C, Yao X, Zhao J, Pei G. Traditional Chinese Nootropic Medicine Radix Polygalae and Its Active Constituent Onjisaponin B Reduce β-Amyloid Production and Improve Cognitive Impairments. PLoS One 2016; 11:e0151147. [PMID: 26954017 PMCID: PMC4782990 DOI: 10.1371/journal.pone.0151147] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/24/2016] [Indexed: 11/25/2022] Open
Abstract
Decline of cognitive function is the hallmark of Alzheimer’s disease (AD), regardless of the pathological mechanism. Traditional Chinese medicine has been used to combat cognitive impairments and has been shown to improve learning and memory. Radix Polygalae (RAPO) is a typical and widely used herbal medicine. In this study, we aimed to follow the β-amyloid (Aβ) reduction activity to identify active constituent(s) of RAPO. We found that Onjisaponin B of RAPO functioned as RAPO to suppress Aβ production without direct inhibition of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and γ-secretase activities. Our mechanistic study showed that Onjisaponin B promoted the degradation of amyloid precursor protein (APP). Further, oral administration of Onjisaponin B ameliorated Aβ pathology and behavioral defects in APP/PS1 mice. Taken together, our results indicate that Onjisaponin B is effective against AD, providing a new therapeutic agent for further drug discovery.
Collapse
Affiliation(s)
- Xiaohang Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jin Cui
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yang Yu
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou, China
| | - Wei Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yujun Hou
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin Wang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Dapeng Qin
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou, China
| | - Cun Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xinsheng Yao
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou, China
| | - Jian Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
- * E-mail: (GP); (JZ)
| | - Gang Pei
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, China
- * E-mail: (GP); (JZ)
| |
Collapse
|
3
|
Jung JI, Price AR, Ladd TB, Ran Y, Park HJ, Ceballos-Diaz C, Smithson LA, Hochhaus G, Tang Y, Akula R, Ba S, Koo EH, Shapiro G, Felsenstein KM, Golde TE. Cholestenoic acid, an endogenous cholesterol metabolite, is a potent γ-secretase modulator. Mol Neurodegener 2015; 10:29. [PMID: 26169917 PMCID: PMC4501119 DOI: 10.1186/s13024-015-0021-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 05/29/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Amyloid-β (Aβ) 42 has been implicated as the initiating molecule in the pathogenesis of Alzheimer's disease (AD); thus, therapeutic strategies that target Aβ42 are of great interest. γ-Secretase modulators (GSMs) are small molecules that selectively decrease Aβ42. We have previously reported that many acidic steroids are GSMs with potencies ranging in the low to mid micromolar concentration with 5β-cholanic acid being the most potent steroid identified GSM with half maximal effective concentration (EC50) of 5.7 μM. RESULTS We find that the endogenous cholesterol metabolite, 3β-hydroxy-5-cholestenoic acid (CA), is a steroid GSM with enhanced potency (EC50 of 250 nM) relative to 5β-cholanic acid. CA i) is found in human plasma at ~100-300 nM concentrations ii) has the typical acidic GSM signature of decreasing Aβ42 and increasing Aβ38 levels iii) is active in in vitro γ-secretase assay iv) is made in the brain. To test if CA acts as an endogenous GSM, we used Cyp27a1 knockout (Cyp27a1-/-) and Cyp7b1 knockout (Cyp7b1-/-) mice to investigate if manipulation of cholesterol metabolism pathways relevant to CA formation would affect brain Aβ42 levels. Our data show that Cyp27a1-/- had increased brain Aβ42, whereas Cyp7b1-/- mice had decreased brain Aβ42 levels; however, peripheral dosing of up to 100 mg/kg CA did not affect brain Aβ levels. Structure-activity relationship (SAR) studies with multiple known and novel CA analogs studies failed to reveal CA analogs with increased potency. CONCLUSION These data suggest that CA may act as an endogenous GSM within the brain. Although it is conceptually attractive to try and increase the levels of CA in the brain for prevention of AD, our data suggest that this will not be easily accomplished.
Collapse
Affiliation(s)
- Joo In Jung
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Ashleigh R Price
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Thomas B Ladd
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Yong Ran
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Hyo-Jin Park
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Carolina Ceballos-Diaz
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Lisa A Smithson
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Günther Hochhaus
- College of Pharmacy, University of Florida, Gainesville, FL, 32610, USA.
| | - Yufei Tang
- College of Pharmacy, University of Florida, Gainesville, FL, 32610, USA.
| | | | - Saritha Ba
- SAI Life Sciences Ltd., Turkapally, AP500078, India.
| | - Edward H Koo
- Department of Neuroscience, University of California, La Jolla, San Diego, CA, 92093, USA.
- Departments of Medicine and Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119077, Singapore.
| | | | - Kevin M Felsenstein
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| | - Todd E Golde
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| |
Collapse
|
4
|
Jung JI, Premraj S, Cruz PE, Ladd TB, Kwak Y, Koo EH, Felsenstein KM, Golde TE, Ran Y. Independent relationship between amyloid precursor protein (APP) dimerization and γ-secretase processivity. PLoS One 2014; 9:e111553. [PMID: 25350374 PMCID: PMC4211736 DOI: 10.1371/journal.pone.0111553] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/28/2014] [Indexed: 12/26/2022] Open
Abstract
Altered production of β-amyloid (Aβ) from the amyloid precursor protein (APP) is closely associated with Alzheimer's disease (AD). APP has a number of homo- and hetero-dimerizing domains, and studies have suggested that dimerization of β-secretase derived APP carboxyl terminal fragment (CTFβ, C99) impairs processive cleavage by γ-secretase increasing production of long Aβs (e.g., Aβ1-42, 43). Other studies report that APP CTFβ dimers are not γ-secretase substrates. We revisited this issue due to observations made with an artificial APP mutant referred to as 3xK-APP, which contains three lysine residues at the border of the APP ectodomain and transmembrane domain (TMD). This mutant, which dramatically increases production of long Aβ, was found to form SDS-stable APP dimers, once again suggesting a mechanistic link between dimerization and increased production of long Aβ. To further evaluate how multimerization of substrate affects both initial γ-secretase cleavage and subsequent processivity, we generated recombinant wild type- (WT) and 3xK-C100 substrates, isolated monomeric, dimeric and trimeric forms of these proteins, and evaluated both ε-cleavage site utilization and Aβ production. These show that multimerization significantly impedes γ-secretase cleavage, irrespective of substrate sequence. Further, the monomeric form of the 3xK-C100 mutant increased long Aβ production without altering the initial ε-cleavage utilization. These data confirm and extend previous studies showing that dimeric substrates are not efficient γ-secretase substrates, and demonstrate that primary sequence determinants within APP substrate alter γ-secretase processivity.
Collapse
Affiliation(s)
- Joo In Jung
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Sasha Premraj
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- College of Pharmacy, University of Florida, Gainesville, Florida, United States of America
| | - Pedro E. Cruz
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Thomas B. Ladd
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Yewon Kwak
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
| | - Edward H. Koo
- Department of Neuroscience, University of California San Diego, La Jolla, California, United States of America
| | - Kevin M. Felsenstein
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Todd E. Golde
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Yong Ran
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| |
Collapse
|
5
|
Jung JI, Ran Y, Cruz PE, Rosario AM, Ladd TB, Kukar TL, Koo EH, Felsenstein KM, Golde TE. Complex relationships between substrate sequence and sensitivity to alterations in γ-secretase processivity induced by γ-secretase modulators. Biochemistry 2014; 53:1947-57. [PMID: 24620716 PMCID: PMC3985764 DOI: 10.1021/bi401521t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
γ-Secretase
catalyzes the final cleavage of the amyloid precursor
protein (APP), resulting in the production of amyloid-β (Aβ)
peptides with different carboxyl termini. Presenilin (PSEN) and amyloid precursor protein (APP) mutations
linked to early onset familial Alzheimer’s disease modify the
profile of Aβ isoforms generated, by altering both the initial
γ-secretase cleavage site and subsequent processivity in a manner
that leads to increased levels of the more amyloidogenic Aβ42
and in some circumstances Aβ43. Compounds termed γ-secretase
modulators (GSMs) and inverse GSMs (iGSMs) can decrease and increase
levels of Aβ42, respectively. As GSMs lower the level of production
of pathogenic forms of long Aβ isoforms, they are of great interest
as potential Alzheimer’s disease therapeutics. The factors
that regulate GSM modulation are not fully understood; however, there
is a growing body of evidence that supports the hypothesis that GSM
activity is influenced by the amino acid sequence of the γ-secretase
substrate. We have evaluated whether mutations near the luminal border
of the transmembrane domain (TMD) of APP alter the ability of both
acidic, nonsteroidal anti-inflammatory drug-derived carboxylate and
nonacidic,
phenylimidazole-derived classes of GSMs and iGSMs to modulate γ-secretase
cleavage. Our data show that point mutations can dramatically reduce
the sensitivity to modulation of cleavage by GSMs but have weaker
effects on iGSM activity. These studies support the concept that the
effect of GSMs may be substrate selective; for APP, it is dependent
on the amino acid sequence of the substrate near the junction of the
extracellular domain and luminal segment of the TMD.
Collapse
Affiliation(s)
- Joo In Jung
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, and McKnight Brain Institute, College of Medicine, University of Florida , Gainesville, Florida 32603, United States
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Golde TE, Koo EH, Felsenstein KM, Osborne BA, Miele L. γ-Secretase inhibitors and modulators. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1828:2898-907. [PMID: 23791707 PMCID: PMC3857966 DOI: 10.1016/j.bbamem.2013.06.005] [Citation(s) in RCA: 210] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/04/2013] [Indexed: 12/11/2022]
Abstract
γ-Secretase is a fascinating, multi-subunit, intramembrane cleaving protease that is now being considered as a therapeutic target for a number of diseases. Potent, orally bioavailable γ-secretase inhibitors (GSIs) have been developed and tested in humans with Alzheimer's disease (AD) and cancer. Preclinical studies also suggest the therapeutic potential for GSIs in other disease conditions. However, due to inherent mechanism based-toxicity of non-selective inhibition of γ-secretase, clinical development of GSIs will require empirical testing with careful evaluation of benefit versus risk. In addition to GSIs, compounds referred to as γ-secretase modulators (GSMs) remain in development as AD therapeutics. GSMs do not inhibit γ-secretase, but modulate γ-secretase processivity and thereby shift the profile of the secreted amyloid β peptides (Aβ) peptides produced. Although GSMs are thought to have an inherently safe mechanism of action, their effects on substrates other than the amyloid β protein precursor (APP) have not been extensively investigated. Herein, we will review the current state of development of GSIs and GSMs and explore pertinent biological and pharmacological questions pertaining to the use of these agents for select indications. This article is part of a Special Issue entitled: Intramembrane Proteases.
Collapse
Affiliation(s)
- Todd E Golde
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
| | | | | | | | | |
Collapse
|
7
|
Jung JI, Ladd TB, Kukar T, Price AR, Moore BD, Koo EH, Golde TE, Felsenstein KM. Steroids as γ-secretase modulators. FASEB J 2013; 27:3775-85. [PMID: 23716494 PMCID: PMC3752532 DOI: 10.1096/fj.12-225649] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/14/2013] [Indexed: 11/11/2022]
Abstract
Aggregation and accumulation of Aβ42 play an initiating role in Alzheimer's disease (AD); thus, selective lowering of Aβ42 by γ-secretase modulators (GSMs) remains a promising approach to AD therapy. Based on evidence suggesting that steroids may influence Aβ production, we screened 170 steroids at 10 μM for effects on Aβ42 secreted from human APP-overexpressing Chinese hamster ovary cells. Many acidic steroids lowered Aβ42, whereas many nonacidic steroids actually raised Aβ42. Studies on the more potent compounds showed that Aβ42-lowering steroids were bonafide GSMs and Aβ42-raising steroids were inverse GSMs. The most potent steroid GSM identified was 5β-cholanic acid (EC50=5.7 μM; its endogenous analog lithocholic acid was virtually equipotent), and the most potent inverse GSM identified was 4-androsten-3-one-17β-carboxylic acid ethyl ester (EC50=6.25 μM). In addition, we found that both estrogen and progesterone are weak inverse GSMs with further complex effects on APP processing. These data suggest that certain endogenous steroids may have the potential to act as GSMs and add to the evidence that cholesterol, cholesterol metabolites, and other steroids may play a role in modulating Aβ production and thus risk for AD. They also indicate that acidic steroids might serve as potential therapeutic leads for drug optimization/development.
Collapse
Affiliation(s)
- Joo In Jung
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Thomas B. Ladd
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Thomas Kukar
- Department of Pharmacology and Neurology, Emory University School of Medicine, Atlanta, Georgia, USA; and
| | - Ashleigh R. Price
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Brenda D. Moore
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Edward H. Koo
- Department of Neuroscience, University of California, San Diego, La Jolla, California, USA
| | - Todd E. Golde
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Kevin M. Felsenstein
- Center for Translational Research in Neurodegenerative Disease and
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
8
|
Loureiro RM, Dumin JA, McKee TD, Austin WF, Fuller NO, Hubbs JL, Shen R, Jonker J, Ives J, Bronk BS, Tate B. Efficacy of SPI-1865, a novel gamma-secretase modulator, in multiple rodent models. ALZHEIMERS RESEARCH & THERAPY 2013; 5:19. [PMID: 23597079 PMCID: PMC3707052 DOI: 10.1186/alzrt173] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/26/2013] [Accepted: 04/05/2013] [Indexed: 12/22/2022]
Abstract
Introduction Modulation of the gamma-secretase enzyme, which reduces the production of the amyloidogenic Aβ42 peptide while sparing the production of other Aβ species, is a promising therapeutic approach for the treatment of Alzheimer's disease. Satori has identified a unique class of small molecule gamma-secretase modulators (GSMs) capable of decreasing Aβ42 levels in cellular and rodent model systems. The compound class exhibits potency in the nM range in vitro and is selective for lowering Aβ42 and Aβ38 while sparing Aβ40 and total Aβ levels. In vivo, a compound from the series, SPI-1865, demonstrates similar pharmacology in wild-type CD1 mice, Tg2576 mice and Sprague Dawley rats. Methods Animals were orally administered either a single dose of SPI-1865 or dosed for multiple days. Aβ levels were measured using a sensitive plate-based ELISA system (MSD) and brain and plasma exposure of drug were assessed by LC/MS/MS. Results In wild-type mice using either dosing regimen, brain Aβ42 and Aβ38 levels were decreased upon treatment with SPI-1865 and little to no statistically meaningful effect on Aβ40 was observed, reflecting the changes observed in vitro. In rats, brain Aβ levels were examined and similar to the mouse studies, brain Aβ42 and Aβ38 were lowered. Comparable changes were also observed in the Tg2576 mice, where Aβ levels were measured in brain as well as plasma and CSF. Conclusions Taken together, these data indicate that SPI-1865 is orally bioavailable, brain penetrant, and effective at lowering Aβ42 in a dose responsive manner. With this unique profile, the class of compounds represented by SPI-1865 may be a promising new therapy for Alzheimer's disease.
Collapse
Affiliation(s)
- Robyn M Loureiro
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Jo Ann Dumin
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Timothy D McKee
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Wesley F Austin
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Nathan O Fuller
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Jed L Hubbs
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Ruichao Shen
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Jeff Jonker
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Jeff Ives
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Brian S Bronk
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| | - Barbara Tate
- Satori Pharmaceuticals, 281 Albany St., Cambridge, MA 02139, USA
| |
Collapse
|
9
|
Altered processing of amyloid precursor protein in cells undergoing apoptosis. PLoS One 2013; 8:e57979. [PMID: 23469123 PMCID: PMC3585261 DOI: 10.1371/journal.pone.0057979] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/30/2013] [Indexed: 01/25/2023] Open
Abstract
Altered proteolysis of amyloid precursor protein is an important determinant of pathology development in Alzheimer's disease. Here, we describe the detection of two novel fragments of amyloid precursor protein in H4 neuroglioma cells undergoing apoptosis. Immunoreactivity of these 25-35 kDa fragments to two different amyloid precursor protein antibodies suggests that they contain the amyloid-β region and an epitope near the C-terminus of amyloid precursor protein. Generation of these fragments is associated with cleavage of caspase-3 and caspase-7, suggesting activation of these caspases. Studies in neurons undergoing DNA damage-induced apoptosis also showed similar results. Inclusion of caspase inhibitors prevented the generation of these novel fragments, suggesting that they are generated by a caspase-dependent mechanism. Molecular weight prediction and immunoreactivity of the fragments generated suggested that such fragments could not be generated by cleavage at any previously identified caspase, secretase, or calpain site on amyloid precursor protein. Bioinformatic analysis of the amino acid sequence of amyloid precursor protein revealed that fragments fitting the observed size and immunoreactivity could be generated by either cleavage at a novel, hitherto unidentified, caspase site or at a previously identified matrix metalloproteinase site in the extracellular domain. Proteolytic cleavage at any of these sites leads to a decrease in the generation of α-secretase cleaved secreted APP, which has both anti-apoptotic and neuroprotective properties, and thus may contribute to neurodegeneration in Alzheimer's disease.
Collapse
|
10
|
McKee TD, Loureiro RM, Dumin JA, Zarayskiy V, Tate B. An improved cell-based method for determining the γ-secretase enzyme activity against both Notch and APP substrates. J Neurosci Methods 2013; 213:14-21. [DOI: 10.1016/j.jneumeth.2012.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 11/30/2022]
|
11
|
Niedowicz DM, Studzinski CM, Weidner AM, Platt TL, Kingry KN, Beckett TL, Bruce-Keller AJ, Keller JN, Murphy MP. Leptin regulates amyloid β production via the γ-secretase complex. Biochim Biophys Acta Mol Basis Dis 2012; 1832:439-44. [PMID: 23274884 DOI: 10.1016/j.bbadis.2012.12.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 12/17/2012] [Accepted: 12/19/2012] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is the most common age-related neurodegenerative disease, affecting an estimated 5.3million people in the United States. While many factors likely contribute to AD progression, it is widely accepted that AD is driven by the accumulation of β-amyloid (Aβ), a small, fibrillogenic peptide generated by the sequential proteolysis of the amyloid precursor protein by the β- and γ-secretases. Though the underlying causes of Aβ accumulation in sporadic AD are myriad, it is clear that lifestyle and overall health play a significant role. The adipocyte-derived hormone leptin has varied systemic affects, including neuropeptide release and neuroprotection. A recent study by Lieb et al. (2009) showed that individuals with low plasma leptin levels are at greater risk of developing AD, through unknown mechanisms. In this report, we show that plasma leptin is a strong negative predictor of Aβ levels in the mouse brain, supporting a protective role for the hormone in AD onset. We also show that the inhibition of Aβ accumulation is due to the downregulation of transcription of the γ-secretase components. On the other hand, β-secretase expression is either unchanged (BACE1) or increased (BACE2). Finally, we show that only presenilin 1 (PS1) is negatively correlated with plasma leptin at the protein level (p<0.0001). These data are intriguing and may highlight a role for leptin in regulating the onset of amyloid pathology and AD.
Collapse
|
12
|
Modulation of gamma-secretase for the treatment of Alzheimer's disease. Int J Alzheimers Dis 2012; 2012:210756. [PMID: 23320246 PMCID: PMC3536039 DOI: 10.1155/2012/210756] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 11/08/2012] [Indexed: 11/24/2022] Open
Abstract
The Amyloid Hypothesis states that the cascade of events associated with Alzheimer's disease (AD)—formation of amyloid plaques, neurofibrillary tangles, synaptic loss, neurodegeneration, and cognitive decline—are triggered by Aβ peptide dysregulation (Kakuda et al., 2006, Sato et al., 2003, Qi-Takahara et al., 2005). Since γ-secretase is critical for Aβ production, many in the biopharmaceutical community focused on γ-secretase as a target for therapeutic approaches for Alzheimer's disease. However, pharmacological approaches to control γ-secretase activity are challenging because the enzyme has multiple, physiologically critical protein substrates. To lower amyloidogenic Aβ peptides without affecting other γ-secretase substrates, the epsilon (ε) cleavage that is essential for the activity of many substrates must be preserved. Small molecule modulators of γ-secretase activity have been discovered that spare the ε cleavage of APP and other substrates while decreasing the production of Aβ42. Multiple chemical classes of γ-secretase modulators have been identified which differ in the pattern of Aβ peptides produced. Ideally, modulators will allow the ε cleavage of all substrates while shifting APP cleavage from Aβ42 and other highly amyloidogenic Aβ peptides to shorter and less neurotoxic forms of the peptides without altering the total Aβ pool. Here, we compare chemically distinct modulators for effects on APP processing and in vivo activity.
Collapse
|
13
|
Fraering PC. Structural and Functional Determinants of gamma-Secretase, an Intramembrane Protease Implicated in Alzheimer's Disease. Curr Genomics 2011; 8:531-49. [PMID: 19415127 PMCID: PMC2647162 DOI: 10.2174/138920207783769521] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 12/27/2007] [Accepted: 12/27/2007] [Indexed: 12/28/2022] Open
Abstract
Alzheimer’s disease is the most common form of neurodegenerative diseases in humans, characterized by the progressive accumulation and aggregation of amyloid-β peptides (Aβ) in brain regions subserving memory and cognition. These 39-43 amino acids long peptides are generated by the sequential proteolytic cleavages of the amyloid-β precursor protein (APP) by β- and γ-secretases, with the latter being the founding member of a new class of intramembrane-cleaving proteases (I-CliPs) characterized by their intramembranous catalytic residues hydrolyzing the peptide bonds within the transmembrane regions of their respective substrates. These proteases include the S2P family of metalloproteases, the Rhomboid family of serine proteases, and two aspartyl proteases: the signal peptide peptidase (SPP) and γ-secretase. In sharp contrast to Rhomboid and SPP that function as a single component, γ-secretase is a multi-component protease with complex assembly, maturation and activation processes. Recently, two low-resolution three-dimensional structures of γ-secretase and three high-resolution structures of the GlpG rhomboid protease have been obtained almost simultaneously by different laboratories. Although these proteases are unrelated by sequence or evolution, they seem to share common functional and structural mechanisms explaining how they catalyze intramembrane proteolysis. Indeed, a water-containing chamber in the catalytic cores of both γ-secretase and GlpG rhomboid provides the hydrophilic environment required for proteolysis and a lateral gating mechanism controls substrate access to the active site. The studies that have identified and characterized the structural determinants critical for the assembly and activity of the γ-secretase complex are reviewed here.
Collapse
Affiliation(s)
- Patrick C Fraering
- Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
| |
Collapse
|
14
|
Neely KM, Green KN, LaFerla FM. Presenilin is necessary for efficient proteolysis through the autophagy-lysosome system in a γ-secretase-independent manner. J Neurosci 2011; 31:2781-91. [PMID: 21414900 PMCID: PMC3064964 DOI: 10.1523/jneurosci.5156-10.2010] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 10/22/2010] [Accepted: 10/28/2010] [Indexed: 12/12/2022] Open
Abstract
Presenilins are ubiquitous, intramembrane proteins that function in Alzheimer's disease (AD) as the catalytic component of the γ-secretase complex. Familial AD mutations in presenilin are known to exacerbate lysosomal pathology. Hence, we sought to elucidate the function endogenous, wild-type presenilins play in autophagy-mediated protein degradation. We report the finding that genetic deletion or knockdown of presenilins alters many autophagy-related proteins demonstrating a buildup of autophagosomes, indicative of dysfunction in the system. Presenilin-deficient cells inefficiently clear long-lived proteins and fail to build up autophagosomes when challenged with lysosomal inhibitors. Our studies further show that γ-secretase inhibitors do not adversely impact autophagy, indicating that the role of presenilins in autophagy is independent of γ-secretase activity. Based on our findings, we conclude that endogenous, wild-type presenilins are necessary for proper protein degradation through the autophagosome-lysosome system by functioning at the lysosomal level. The role of presenilins in autophagy has many implications for its function in neurological diseases such as AD.
Collapse
Affiliation(s)
- Kara M. Neely
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697-4545
| | - Kim N. Green
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697-4545
| | - Frank M. LaFerla
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697-4545
| |
Collapse
|
15
|
Effects of nonsteroidal anti-inflammatory drugs on amyloid-beta pathology in mouse skeletal muscle. Neurobiol Dis 2010; 39:449-56. [PMID: 20493261 DOI: 10.1016/j.nbd.2010.05.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Revised: 04/26/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022] Open
Abstract
Sporadic inclusion body myositis (sIBM) is a common age-related inflammatory myopathy characterized by the presence of intracellular inclusions that contain the amyloid-beta (Abeta) peptide, a derivative of the amyloid precursor protein (APP). Abeta is believed to cause Alzheimer's disease (AD), suggesting that a link may exist between the two diseases. If AD and sIBM are linked, then treatments that lower Abeta in brain may prove useful for sIBM. To test this hypothesis, transgenic mice that overexpress APP in skeletal muscle were treated for 6 months with a variety of nonsteroidal anti-inflammatory drugs (NSAIDs; naproxen, ibuprofen, carprofen or R-flurbiprofen), a subset of which reduce Abeta in brain and cultured cells. Only ibuprofen lowered Abeta in muscle, and this was not accompanied by corresponding improvements in phenotype. These results indicate that the effects of NSAIDs in the brain may be different from other tissues and that Abeta alone cannot account for skeletal muscle dysfunction in these mice.
Collapse
|
16
|
Weyand NJ, Calton CM, Higashi DL, Kanack KJ, So M. Presenilin/gamma-secretase cleaves CD46 in response to Neisseria infection. THE JOURNAL OF IMMUNOLOGY 2009; 184:694-701. [PMID: 20018629 DOI: 10.4049/jimmunol.0900522] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD46 is a type I transmembrane protein with complement and T cell regulatory functions in human cells. CD46 has signaling and receptor properties in immune and nonimmune cells, many of which are dependent on the expression of cytoplasmic tail (cyt) isoforms cyt1 or cyt2. Little is known about how cyt1 and cyt2 mediate cellular responses. We show that CD46-cyt1 and CD46-cyt2 are substrates for presenilin/gamma-secretase (PS/gammaS), an endogenous protease complex that regulates many important signaling proteins through proteolytic processing. PS/gammaS processing of CD46 releases immunoprecipitable cyt1 and cyt2 tail peptides into the cell, is blocked by chemical inhibitors, and is prevented in dominant negative presenilin mutant cell lines. Two human pathogens, Neisseria gonorrhoeae and Neisseria meningitidis, stimulate PS/gammaS processing of CD46-cyt1 and CD46-cyt2. This stimulation requires type IV pili and PilT, the type IV pilus retraction motor, implying that mechanotransduction plays a role in this event. We present a model for PS/gammaS processing of CD46 that provides a mechanism by which signals are transduced via the cyt1 and cyt2 tails to regulate CD46-dependent cellular responses. Our findings have broad implications for understanding the full range of CD46 functions in infection and noninfection situations.
Collapse
Affiliation(s)
- Nathan J Weyand
- BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.
| | | | | | | | | |
Collapse
|
17
|
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
|
18
|
Cohen MP, Shearman CW. Reduction of Abeta42 in brains of transgenic APPswe mice by 2-3-chlorophenylaminophenylacetate. Clin Exp Pharmacol Physiol 2009; 36:1099-103. [PMID: 19413589 DOI: 10.1111/j.1440-1681.2009.05201.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
1. Imbalanced generation of the Abeta42 peptide from the amyloid beta protein precursor (APP) is implicated in the pathogenesis of Alzheimer's disease. 2. The present study is the first to evaluate the ability of 2-[3-chlorophenylamino]phenylacetic acid (GLY-230), a new drug in clinical development for the treatment of vascular complications of diabetes, to modulate Abeta42 levels in transgenic mice expressing APP. 3. Oral administration of 7.5 mg/kg GLY-230 twice a day for 14 days to APPswe transgenic mice aged 3 months significantly reduced brain Abeta42 and increased plasma Abeta42 levels by 50 and 20%, respectively. 4. GLY-230 readily entered the brain after administration of a dose (7.5 mg/kg) that decreased brain Abeta42. 5. These results are the first to demonstrate that GLY-230, which exhibits antiglycation but no cyclo-oxygenase inhibitory properties, lowers brain Abeta42 levels in this experimental model of Alzheimer's disease.
Collapse
Affiliation(s)
- Margo P Cohen
- Glycadia Inc., Philadelphia, Pennsylvania 19103, USA.
| | | |
Collapse
|
19
|
Elbert DL, Mawuenyega KG, Scott EA, Wildsmith KR, Bateman RJ. Stable isotope labeling tandem mass spectrometry (SILT): integration with peptide identification and extension to data-dependent scans. J Proteome Res 2008; 7:4546-56. [PMID: 18774841 DOI: 10.1021/pr800386u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Quantitation of relative or absolute amounts of proteins by mass spectrometry can be prone to large errors. The use of MS/MS ion intensities and stable isotope labeling, which we term stable isotope labeling tandem mass spectrometry (SILT), decreases the effects of contamination from unrelated compounds. We present a software package (SILTmass) that automates protein identification and quantification by the SILT method. SILTmass has the ability to analyze the kinetics of protein turnover, in addition to relative and absolute protein quantitation. Instead of extracting chromatograms to find elution peaks, SILTmass uses only scans in which a peptide is identified and that meet an ion intensity threshold. Using only scans with identified peptides, the accuracy and precision of SILT is shown to be superior to precursor ion intensities, particularly at high or low dilutions of the isotope labeled compounds or with low amounts of protein. Using example scans, we demonstrate likely reasons for the improvements in quantitation by SILT. The appropriate use of variable modifications in peptide identification is described for measurement of protein turnover kinetics. The combination of identification with SILT facilitates quantitation without peak detection and helps to ensure the appropriate use of variable modifications for kinetics experiments.
Collapse
Affiliation(s)
- Donald L Elbert
- Department of Biomedical Engineering and Center for Materials Innovation, Washington University, St. Louis, Missouri, USA.
| | | | | | | | | |
Collapse
|
20
|
Carter DB, Dunn E, Pauley AM, McKinley DD, Fleck TJ, Ellerbrook BR, Stratman NC, Zhou X, Himes CS, Nye JS, Tomasselli A, Yan R. Changes in gamma-secretase activity and specificity caused by the introduction of consensus aspartyl protease active motif in Presenilin 1. Mol Neurodegener 2008; 3:6. [PMID: 18474109 PMCID: PMC2405781 DOI: 10.1186/1750-1326-3-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 05/12/2008] [Indexed: 11/12/2022] Open
Abstract
Presenilin (PS1 or PS2) is an essential component of the active γ-secretase complex that liberates the Aβ peptides from amyloid precursor protein (APP). PS1 is regarded as an atypical aspartyl protease harboring two essential aspartic acids in the context of the sequence D257LV and D385FI, respectively, rather than the typical DTG...DTG catalytic motif of classical aspartyl proteases. In the present studies, we introduced the sequence DTG in PS1 at and around the catalytic D257 and D385 residues to generate three PS1 mutants: D257TG, D385TG, and the double-mutant D257TG/D385TG. The effects of these changes on the γ-secretase activity in the presence or absence of γ-secretase inhibitors and modulators were investigated. The results showed that PS1 mutants having D385TG robustly enhanced Aβ42 production compared to the wild type (wt), and were more sensitive than wt to inhibition by a classical aspartyl protease transition state mimic, and fenchylamine, a sulfonamide derivative. Unlike wt PS1 and some of its clinical mutants, all three PS1 artificial mutants decreased cleavage of Notch S3-site, suggesting that these artificial mutations may trigger conformational changes at the substrate docking and catalytic site that cause alteration of substrate specificity and inhibition pattern. Consistent with this notion, we have found that NSAID enzymatic inhibitors of COX, known modulators of the γ-secretase activity, cause PS1 mutants containing D385TG to produce higher levels of both Aβ38 and Aβ42, but to reduce levels of Aβ39, showing a pattern of Aβ formation different from that observed with wild type PS1 and its clinical mutants. This study provides an important structural clue for the rational design of drugs to inhibit processing of APP at the γ-site without interfering with Notch processing.
Collapse
Affiliation(s)
- Donald B Carter
- Global Research and Development, Pfizer Inc, Kalamazoo, MI 49001, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Ostrowski SM, Wilkinson BL, Golde TE, Landreth G. Statins Reduce Amyloid-β Production through Inhibition of Protein Isoprenylation. J Biol Chem 2007; 282:26832-26844. [PMID: 17646164 DOI: 10.1074/jbc.m702640200] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epidemiological evidence suggests that long term treatment with hydroxymethylglutaryl-CoA reductase inhibitors, or statins, decreases the risk for developing Alzheimer disease (AD). However, statin-mediated AD protection cannot be fully explained by reduction of cholesterol levels. In addition to their cholesterol lowering effects, statins have pleiotropic actions and act to lower the concentrations of isoprenoid intermediates, such as geranylgeranyl pyrophosphate and farnesyl pyrophosphate. The Rho and Rab family small G-proteins require addition of these isoprenyl moieties at their C termini for normal GTPase function. In neuroblastoma cell lines, treatment with statins inhibits the membrane localization of Rho and Rab proteins at statin doses as low as 200 nm, without affecting cellular cholesterol levels. In addition, we show for the first time that at low, physiologically relevant, doses statins preferentially inhibit the isoprenylation of a subset of GTPases. The amyloid precursor protein (APP) is proteolytically cleaved to generate beta-amyloid (Abeta), which is the major component of senile plaques found in AD. We show that inhibition of protein isoprenylation by statins causes the accumulation of APP within the cell through inhibition of Rab family proteins involved in vesicular trafficking. Moreover, inhibition of Rho family protein function reduces levels of APP C-terminal fragments due to enhanced lysosomal dependent degradation. Statin inhibition of protein isoprenylation results in decreased Abeta secretion. In summary, we show that statins selectively inhibit GTPase isoprenylation at clinically relevant doses, leading to reduced Abeta production in an isoprenoid-dependent manner. These studies provide insight into the mechanisms by which statins may reduce AD pathogenesis.
Collapse
Affiliation(s)
- Stephen M Ostrowski
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Brandy L Wilkinson
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Todd E Golde
- Department of Neuroscience, Mayo Clinic Jacksonville, Mayo Clinic College of Medicine, Jacksonville, Florida 32224
| | - Gary Landreth
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106.
| |
Collapse
|
22
|
Laifenfeld D, Patzek LJ, McPhie DL, Chen Y, Levites Y, Cataldo AM, Neve RL. Rab5 mediates an amyloid precursor protein signaling pathway that leads to apoptosis. J Neurosci 2007; 27:7141-53. [PMID: 17611268 PMCID: PMC6794581 DOI: 10.1523/jneurosci.4599-06.2007] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) involves activation of apoptotic pathways that may be regulated through signaling cascades initiated by the amyloid precursor protein (APP). Enlarged endosomes have been observed in postmortem AD brains at very early stages of the disease. We show here that exogenous expression of a familial AD (FAD) mutant of APP or of the APP binding protein APP-BP1 in neurons causes enlargement of early endosomes, increased receptor-mediated endocytosis via a pathway dependent on APP-BP1 binding to APP, and apoptosis. Levels of both APP-BP1 and Rab5 are elevated in early endosomes in cortical embryonic neurons expressing APP(V642I) or APP-BP1, in cultured skin fibroblast cells from Down syndrome subjects, and in postmortem hippocampal tissue of individuals with AD. Indeed, Rab5 was found to bind specifically to APP-BP1, between amino acids 443 and 479. Inhibition of Rab5 or dynamin activity, but not of Eps15 (epidermal growth factor receptor pathway substrate 15) activity, rescued neurons from apoptosis induced by either APP(V642I) or APP-BP1, without affecting levels of intracellular or secreted amyloid-beta (Abeta). Induction of Rab5 activity via expression of a constitutively active mutant led to an increase in neuronal apoptosis more than twice that attributable to induction of endosome enlargement via a Rab5-independent mechanism, regardless of Abeta production. Together, these findings suggest that Rab5 activation via an APP/APP-BP1-initiated signaling pathway mediates neuronal apoptosis caused by FAD mutants of APP and that, within this pathway, Rab5 has a specific role in signaling that is distinct from, although not independent of, its role in trafficking.
Collapse
Affiliation(s)
- Daphna Laifenfeld
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02478
| | - Lucas J. Patzek
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02478
| | - Donna L. McPhie
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02478
| | - Yuzhi Chen
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, and
| | - Yona Levites
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, Florida 32224
| | - Anne M. Cataldo
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02478
| | - Rachael L. Neve
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02478
| |
Collapse
|
23
|
Bateman RJ, Munsell LY, Chen X, Holtzman DM, Yarasheski KE. Stable isotope labeling tandem mass spectrometry (SILT) to quantify protein production and clearance rates. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:997-1006. [PMID: 17383190 PMCID: PMC2040126 DOI: 10.1016/j.jasms.2007.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/07/2007] [Accepted: 02/14/2007] [Indexed: 05/11/2023]
Abstract
In all biological systems, protein amount is a function of the rate of production and clearance. The speed of a response to a disturbance in protein homeostasis is determined by turnover rate. Quantifying alterations in protein synthesis and clearance rates is vital to understanding disease pathogenesis (e.g., aging, inflammation). No methods currently exist for quantifying production and clearance rates of low-abundance (femtomole) proteins in vivo. We describe a novel, mass spectrometry-based method for quantitating low-abundance protein synthesis and clearance rates in vitro and in vivo in animals and humans. The utility of this method is demonstrated with amyloid-beta (Abeta), an important low-abundance protein involved in Alzheimer's disease pathogenesis. We used in vivo stable isotope labeling, immunoprecipitation of Abeta from cerebrospinal fluid, and quantitative liquid chromatography electrospray-ionization tandem mass spectrometry (LC-ESI-tandem MS) to quantify human Abeta protein production and clearance rates. The method is sensitive and specific for stable isotope-labeled amino acid incorporation into CNS Abeta (+/-1% accuracy). This in vivo method can be used to identify pathophysiologic changes in protein metabolism and may serve as a biomarker for monitoring disease risk, progression, or response to novel therapeutic agents. The technique is adaptable to other macromolecules, such as carbohydrates or lipids.
Collapse
Affiliation(s)
- Randall J Bateman
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
| | | | | | | | | |
Collapse
|
24
|
Boeras DI, Granic A, Padmanabhan J, Crespo NC, Rojiani AM, Potter H. Alzheimer's presenilin 1 causes chromosome missegregation and aneuploidy. Neurobiol Aging 2006; 29:319-28. [PMID: 17169464 PMCID: PMC2692942 DOI: 10.1016/j.neurobiolaging.2006.10.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 09/27/2006] [Accepted: 10/25/2006] [Indexed: 11/24/2022]
Abstract
Mutations in the presenilin 1 gene cause most early onset familial Alzheimer's disease (FAD). Here, we report that a defect in the cell cycle - improper chromosome segregation - can be caused by abnormal presenilin function and therefore may contribute to AD pathogenesis. Specifically we find that either over-expression or FAD mutation in presenilin 1 (M146L and M146V) leads to chromosome missegregation and aneuploidy in vivo and in vitro: (1) Up to 20% of lymphocytes and neurons of FAD-PS-1 transgenic and knocking mice are aneuploid by metaphase chromosome analysis and in situ hybridization. (2) Transiently transfected human cells over-expressing normal or mutant PS-1 develop similar aneuploidy within 48 h, including trisomy 21. (3) Mitotic spindles in the PS-1 transfected cells contain abnormal microtubule arrays and lagging chromosomes. Several mechanisms by which chromosome missegregation induced by presenilin may contribute to Alzheimer's disease are discussed.
Collapse
Affiliation(s)
- Debrah I. Boeras
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Antoneta Granic
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Jaya Padmanabhan
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Nichole C. Crespo
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Amyn M. Rojiani
- Department of Pathology, University of South Florida College of Medicine, Tampa, FL 33612, USA
| | - Huntington Potter
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
- H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
| |
Collapse
|
25
|
Nyborg AC, Ladd TB, Jansen K, Kukar T, Golde TE. Intramembrane proteolytic cleavage by human signal peptide peptidase like 3 and malaria signal peptide peptidase. FASEB J 2006; 20:1671-9. [PMID: 16873890 DOI: 10.1096/fj.06-5762com] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Signal peptide peptidase (SPP) is an intramembrane cleaving protease (I-CLiP) identified by its cleavage of several type II membrane signal peptides. To date, only human SPP has been directly shown to have proteolytic activity. Here we demonstrate that the most closely related human homologue of SPP, signal peptide peptidase like 3 (SPPL3), cleaves a SPP substrate, but a more distantly related homologue, signal peptide peptidase like 2b (SPPL2b), does not. These data provide strong evidence that the SPP and SPPL3 have conserved active sites and suggest that the active sites SPPL2b is distinct. We have also synthesized a cDNA designed to express the single SPP gene present in Plasmodium falciparum and cloned this into a mammalian expression vector. When the malaria SPP protein is expressed in mammalian cells it cleaves a SPP substrate. Notably, several human SPP inhibitors block the proteolytic activity of malarial SPP (mSPP). Studies from several model organisms that express multiple SPP homologs demonstrate that the silencing of a single SPP homologue is lethal. Based on these data, we hypothesize that mSPP is a potential a novel therapeutic target for malaria.
Collapse
Affiliation(s)
- Andrew C Nyborg
- Department of Neuroscience, Mayo Clinic Jacksonville, Mayo Clinic College of Medicine, 4500 San Pablo Rd., Jacksonville, Florida 32224, USA
| | | | | | | | | |
Collapse
|
26
|
Nistor M, Don M, Parekh M, Sarsoza F, Goodus M, Lopez G, Kawas C, Leverenz J, Doran E, Lott I, Hill M, Head E. Alpha- and beta-secretase activity as a function of age and beta-amyloid in Down syndrome and normal brain. Neurobiol Aging 2006; 28:1493-506. [PMID: 16904243 PMCID: PMC3375834 DOI: 10.1016/j.neurobiolaging.2006.06.023] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 05/09/2006] [Accepted: 06/21/2006] [Indexed: 11/22/2022]
Abstract
Aged individuals with Down syndrome (DS) develop Alzheimer's disease (AD) neuropathology by the age of 40 years. The purpose of the current study was to measure age-associated changes in APP processing in 36 individuals with DS (5 months-69 years) and in 26 controls (5 months-100 years). Alpha-secretase significantly decreased with age in DS, particularly in cases over the age of 40 years and was stable in controls. The levels of C-terminal fragments of APP reflecting alpha-secretase processing (CTF-alpha) decreased with age in both groups. In both groups, there was significant increase in beta-secretase activity with age. CTF-beta remained constant with age in controls suggesting compensatory increases in turnover/clearance mechanisms. In DS, young individuals had the lowest CTF-beta levels that may reflect rapid conversion of beta-amyloid (Abeta) to soluble pools or efficient CTF-beta clearance mechanisms. Treatments to slow or prevent AD in the general population targeting secretase activity may be more efficacious in adults with DS if combined with approaches that enhance Abeta degradation and clearance.
Collapse
Affiliation(s)
- M. Nistor
- Institute for Brain Aging & Dementia, CA, United States
| | - M. Don
- Institute for Brain Aging & Dementia, CA, United States
| | - M. Parekh
- Institute for Brain Aging & Dementia, CA, United States
| | - F. Sarsoza
- Institute for Brain Aging & Dementia, CA, United States
| | - M. Goodus
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
| | - G.E. Lopez
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
| | - C. Kawas
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
| | - J. Leverenz
- Neurology and Psychiatry and Behavioral Sciences, University of Washington Seattle, WA 98108, United States
| | - E. Doran
- Institute for Brain Aging & Dementia, CA, United States
| | - I.T. Lott
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
| | - M. Hill
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
| | - E. Head
- Institute for Brain Aging & Dementia, CA, United States
- Department of Neurology, University of California, 1259 Gillespie NRF, Irvine, CA 92697-4540, United States
- Corresponding author. Tel.: +1 949 824 8700; fax: +1 949 824 2071. (E. Head)
| |
Collapse
|
27
|
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
|
28
|
Chen F, Eckman EA, Eckman CB. Reductions in levels of the Alzheimer's amyloid beta peptide after oral administration of ginsenosides. FASEB J 2006; 20:1269-71. [PMID: 16636099 DOI: 10.1096/fj.05-5530fje] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
For millennia, ginseng and some of its components have been used to treat a wide variety of medical conditions, including age-related memory impairment. Because of its purported effects and apparently low rate of side effects, ginseng remains one of the top selling natural product remedies in the United States. Given its potential role for improving age-related memory impairments and its common use in China for the treatment of Alzheimer's disease-like symptoms, we analyzed the effects of commercially available preparations of ginseng on the accumulation of the Alzheimer's amyloid beta peptide (Abeta) in a cell-based model system. In this model system, ginseng treatment resulted in a significant reduction in the levels of Abeta in the conditioned medium. We next examined the effects of several compounds isolated from ginseng and found that certain ginsenosides lowered Abeta concentration in a dose-dependent manner with ginsenoside Rg3 having an approximate IC50 of under 25 microM against Abeta42. Furthermore, we found that three of these isolated components, ginsenoside Rg1, Rg3, and RE, resulted in significant reductions in the amount of Abeta detected in the brains of animals after single oral doses of these agents. The results indicate that ginseng itself, or purified ginsenosides, may have similarly useful effects in human disease.
Collapse
Affiliation(s)
- Feng Chen
- Mayo Clinic College of Medicine, Department of Pharmacology, Birdsall Bldg. Rm. 327, 4500 San Pablo Rd., Jacksonville, Florida 32224, USA
| | | | | |
Collapse
|
29
|
Tanii H, Jiang J, Fukumori A, Tagami S, Okazaki Y, Okochi M, Takeda M. Effect of valine on the efficiency and precision at S4 cleavage of the Notch-1 transmembrane domain. J Neurosci Res 2006; 84:918-25. [PMID: 16802341 DOI: 10.1002/jnr.20978] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Presenilin-dependent intramembranous proteolysis mediates the dual cleavage of the Notch-1 protein (S4 and S3) as well as the beta amyloid precursor protein (betaAPP) (gamma40 and epsilon-site). betaAPP has a valine residue just before the gamma40 (amyloid beta [Abeta] numbering) site and after the epsilon-site. Both gamma40 and epsilon have multiple cleavage sites, and the varieties of gamma40 cleavage are associated with Alzheimer's disease (AD). These lines of evidence suggest that valine plays a role in the intramembranous proteolysis. S4 cleavage in the middle of the Notch-1 transmembrane domain (TMD) corresponds to the gamma40 cleavage of betaAPP. The cleavage site is in the center of four sequential alanine residues between Ala1731 and Ala1732, neither of which has a valine residue. To investigate the effects of valine on presenilin-dependent intramembranous proteolysis, we replaced the transmembrane domain residue of Notch-1 with valine and analyzed the efficiency and precision at S4 and S3. We observed that all valine-mutated Notch-1 proteins have a dominant cleavage site (S4) between Ala1731 and Ala1732 with some variations of cleavage precision, suggesting that valine is not indispensable for determining the cleavage site of the Notch-1 transmembrane domain, but affects the efficiency and precision at S4 cleavage of the Notch-1 transmembrane domain.
Collapse
Affiliation(s)
- Hisashi Tanii
- Department of Psychiatry, Institute of Neuroscience, Mie University Graduate School of Medicine, Mie, Japan.
| | | | | | | | | | | | | |
Collapse
|
30
|
Watanabe N, Tomita T, Sato C, Kitamura T, Morohashi Y, Iwatsubo T. Pen-2 is incorporated into the gamma-secretase complex through binding to transmembrane domain 4 of presenilin 1. J Biol Chem 2005; 280:41967-75. [PMID: 16234244 DOI: 10.1074/jbc.m509066200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
gamma-Secretase is a multimeric membrane protein complex comprised of presenilin (PS), nicastrin (Nct), Aph-1, and Pen-2. It is a member of an atypical class of aspartic proteases that hydrolyzes peptide bonds within the membrane. During the biosynthetic process of the gamma-secretase complex, Nct and Aph-1 form a heterodimeric intermediate complex and bind to the C-terminal region of PS, serving as a stabilizing scaffold for the complex. Pen-2 is then recruited into this trimeric complex and triggers endoproteolysis of PS, conferring gamma-secretase activity. Although the Pen-2 accumulation depends on PS, the binding partner of Pen-2 within the gamma-secretase complex remains unknown. We reconstituted PS1 in Psen1/Psen2 deficient cells by expressing a series of PS1 mutants in which one of the N-terminal six transmembrane domains (TMDs) was swapped with those of CD4 (a type I transmembrane protein) or CLAC-P (a type II transmembrane protein). We report that the proximal two-thirds of TMD4 of PS1, including the conserved Trp-Asn-Phe sequence, are required for its interaction with Pen-2. Using a chimeric CD4 molecule harboring PS1 TMD4, we further demonstrate that the PS1 TMD4 bears a direct binding motif to Pen-2. Pen-2 may contribute to the activation of the gamma-secretase complex by directly binding to the TMD4 of PS1.
Collapse
Affiliation(s)
- Naoto Watanabe
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | | | | | | | | | | |
Collapse
|
31
|
Kim SH, Sisodia SS. Evidence that the "NF" motif in transmembrane domain 4 of presenilin 1 is critical for binding with PEN-2. J Biol Chem 2005; 280:41953-66. [PMID: 16234243 DOI: 10.1074/jbc.m509070200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Macromolecular complexes containing presenilins (PS1 and PS2), nicastrin, anterior pharynx defective phenotype 1 (APH-1), and PS enhancer 2 (PEN-2) mediate the intramembranous, gamma-secretase cleavage of beta-amyloid precursor protein (APP), Notch, and a variety of type 1 membrane proteins. We previously demonstrated that PEN-2 is critical for promoting endoproteolysis of PS1 and that the proximal two-thirds of transmembrane domain (TMD) 1 of PEN-2 is required for binding with PS1. In this study, we sought to identify the structural domains of PS1 that are necessary for binding with PEN-2. To address this issue, we generated a series of constructs encoding PS1 mutants harboring deletions or replacements of specific TMDs of PS1-NTF, and examined the effects of encoded molecules on interactions with PEN-2, stabilization and endoproteolysis of PS1, and gamma-secretase activity. We now show that PS1 TMDs 1 and 2 and the intervening hydrophilic loop are dispensable for binding to PEN-2. Furthermore, analysis of chimeric PS1 molecules that harbor replacements of each TMD with corresponding transmembrane segments from the sterol regulatory element-binding protein cleavage activating protein (SCAP) revealed that the PS1-SCAP TMD4 mutant failed to coimmunoprecipitate endogenous PEN-2, strongly suggesting that the fourth TMD of PS1 is required for interaction with PEN-2. Further mutational analyses revealed that the "NF" sequence within the TMD4 of PS1 is the minimal motif that is required for binding with PEN-2, promoting PS1 endoproteolysis and gamma-secretase activity.
Collapse
Affiliation(s)
- Seong-Hun Kim
- Department of Neurobiology, Pharmacology and Physiology, the University of Chicago, Chicago, Illinois 60637, USA
| | | |
Collapse
|
32
|
Brunkan AL, Martinez M, Wang J, Walker ES, Beher D, Shearman MS, Goate AM. Two domains within the first putative transmembrane domain of presenilin 1 differentially influence presenilinase and gamma-secretase activity. J Neurochem 2005; 94:1315-28. [PMID: 16001967 DOI: 10.1111/j.1471-4159.2005.03278.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Presenilins (PS) are thought to contain the active site for presenilinase endoproteolysis of PS and gamma-secretase cleavage of substrates. The structural requirements for PS incorporation into the gamma-secretase enzyme complex, complex stability and maturation, and appropriate presenilinase and gamma-secretase activity are poorly understood. We used rescue assays to identify sequences in transmembrane domain one (TM1) of PS1 required to support presenilinase and gamma-secretase activities. Swap mutations identified an N-terminal TM1 domain that is important for gamma-secretase activity only and a C-terminal TM1 domain that is essential for both presenilinase and gamma-secretase activities. Exchange of residues 95-98 of PS1 (sw95-98) completely abolishes both activities while the familial Alzheimer's disease mutation V96F significantly inhibits both activities. Reversion of residue 96 back to valine in the sw95-98 mutant rescues PS function, identifying V96 as the critical residue in this region. The TM1 mutants do not bind to an aspartyl protease transition state analog gamma-secretase inhibitor, indicating a conformational change induced by the mutations that abrogates catalytic activity. TM1 mutant PS1 molecules retain the ability to interact with gamma-secretase substrates and gamma-secretase complex members, although Nicastrin stability is decreased by the presence of these mutants. gamma-Secretase complexes that contain V96F mutant PS1 molecules display a partial loss of function for gamma-secretase that alters the ratio of amyloid-beta peptide species produced, leading to the amyloid-beta peptide aggregation that causes familial Alzheimer's disease.
Collapse
Affiliation(s)
- A L Brunkan
- Department of Psychiatry, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
Alzheimer's disease (AD) is the most common form of dementia and is characterized pathologically by the accumulation of beta-amyloid (Abeta) plaques and neurofibrillary tangles in the brain. Genetic studies of AD first highlighted the importance of the presenilins (PS). Subsequent functional studies have demonstrated that PS form the catalytic subunit of the gamma-secretase complex that produces the Abeta peptide, confirming the central role of PS in AD biology. Here, we review the studies that have characterized PS function in the gamma-secretase complex in Caenorhabditis elegans, mice and in in vitro cell culture systems, including studies of PS structure, PS interactions with substrates and other gamma-secretase complex members, and the evidence supporting the hypothesis that PS are aspartyl proteases that are active in intramembranous proteolysis. A thorough knowledge of the mechanism of PS cleavage in the context of the gamma-secretase complex will further our understanding of the molecular mechanisms that cause AD, and may allow the development of therapeutics that can alter Abeta production and modify the risk for AD.
Collapse
Affiliation(s)
- A L Brunkan
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO 63100, USA
| | | |
Collapse
|
34
|
Yamamoto M, Horiba M, Buescher JL, Huang D, Gendelman HE, Ransohoff RM, Ikezu T. Overexpression of monocyte chemotactic protein-1/CCL2 in beta-amyloid precursor protein transgenic mice show accelerated diffuse beta-amyloid deposition. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 166:1475-85. [PMID: 15855647 PMCID: PMC1606401 DOI: 10.1016/s0002-9440(10)62364-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Microglia accumulation at the site of amyloid plaques is a strong indication that microglia play a major role in Alzheimer's disease pathogenesis. However, how microglia affect amyloid-beta peptide (Abeta) deposition remains poorly understood. To address this question, we developed a novel bigenic mouse that overexpresses both amyloid precursor protein (APP) and monocyte chemotactic protein-1 (MCP-1; CCL2 in systematic nomenclature). CCL2 expression, driven by the glial fibrillary acidic protein promoter, induced mononuclear phagocyte (MP; monocyte-derived macrophage and microglial) accumulation in the brain. When APP/CCL2 transgenic mice were compared to APP mice, a fivefold increase in Abeta deposition was present despite increased MP accumulation around hippocampal and cortical amyloid plaques. Levels of full-length APP, its C-terminal fragment, and Abeta-degrading enzymes (insulin-degrading enzyme and neprilysin) in APP/CCL2 and APP mice were indistinguishable. Sodium dodecyl sulfate-insoluble Abeta (an indicator of fibrillar Abeta) was increased in APP/CCL2 mice at 5 months of age. Apolipoprotein E, which enhances Abeta deposition, was also increased (2.2-fold) in aged APP/CCL2 as compared to APP mice. We propose that although CCL2 stimulates MP accumulation, it increases Abeta deposition by reducing Abeta clearance through increased apolipoprotein E expression. Understanding the mechanisms underlying these events could be used to modulate microglial function in Alzheimer's disease and positively affect disease outcomes.
Collapse
Affiliation(s)
- Masaru Yamamoto
- Center for Neurovirology and Neurodegenerative Disorders and Department of Pharmacology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
| | | | | | | | | | | | | |
Collapse
|
35
|
Head E, Moffat K, Das P, Sarsoza F, Poon WW, Landsberg G, Cotman CW, Murphy MP. Beta-amyloid deposition and tau phosphorylation in clinically characterized aged cats. Neurobiol Aging 2005; 26:749-63. [PMID: 15708450 DOI: 10.1016/j.neurobiolaging.2004.06.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 06/08/2004] [Accepted: 06/16/2004] [Indexed: 10/26/2022]
Abstract
The current study describes both Abeta and tau abnormalities that accumulate in the brains of aged (16-21 years), but not young (<4 years) clinically characterized cats. Diffuse plaques that were morphologically different from what is typically observed in the human brain could be detected with 4G8 (Abeta17-24) or an Abeta1-42-specific antibody but not with N-terminal Abeta or an Abeta1-40-specific antibody. SELDI-TOF mass spectrometry experiments indicated that cat brain Abeta consisted almost entirely of Abeta1-42. Markers of tau hyperphosphorylation (AT8 and PHF-1) labeled a subset of neurons in two aged animals. In the hilus of the hippocampus, a subset of AT8 positive neurons showed a sprouting morphology similar to that observed in human brain. Western blot analysis with antibodies against hyperphosphorylated tau indicated that tau is hyperphosphorylated in the aged cat and contains many of the same epitopes found in Alzheimer's disease (AD) brain. Thus, the aged cat brain develops AD-related lesions with important morphological and biochemical differences compared to human brain.
Collapse
Affiliation(s)
- E Head
- Department of Neurology, Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697-4540, USA.
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Kukar T, Murphy MP, Eriksen JL, Sagi SA, Weggen S, Smith TE, Ladd T, Khan MA, Kache R, Beard J, Dodson M, Merit S, Ozols VV, Anastasiadis PZ, Das P, Fauq A, Koo EH, Golde TE. Diverse compounds mimic Alzheimer disease-causing mutations by augmenting Abeta42 production. Nat Med 2005; 11:545-50. [PMID: 15834426 DOI: 10.1038/nm1235] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Accepted: 03/09/2005] [Indexed: 11/09/2022]
Abstract
Increased Abeta42 production has been linked to the development of Alzheimer disease. We now identify a number of compounds that raise Abeta42. Among the more potent Abeta42-raising agents identified are fenofibrate, an antilipidemic agent, and celecoxib, a COX-2-selective NSAID. Many COX-2-selective NSAIDs tested raised Abeta42, including multiple COX-2-selective derivatives of two Abeta42-lowering NSAIDs. Compounds devoid of COX activity and the endogenous isoprenoids FPP and GGPP also raised Abeta42. These compounds seem to target the gamma-secretase complex, increasing gamma-secretase-catalyzed production of Abeta42 in vitro. Short-term in vivo studies show that two Abeta42-raising compounds increase Abeta42 levels in the brains of mice. The elevations in Abeta42 by these compounds are comparable to the increases in Abeta42 induced by Alzheimer disease-causing mutations in the genes encoding amyloid beta protein precursor and presenilins, raising the possibility that exogenous compounds or naturally occurring isoprenoids might increase Abeta42 production in humans.
Collapse
Affiliation(s)
- Thomas Kukar
- Department of Neuroscience, Mayo Clinic, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, Florida 32224, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Xie J, Guo Q. PAR-4 is involved in regulation of beta-secretase cleavage of the Alzheimer amyloid precursor protein. J Biol Chem 2005; 280:13824-32. [PMID: 15671026 DOI: 10.1074/jbc.m411933200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mounting evidence indicates that aberrant production and aggregation of amyloid beta-peptide (Abeta)-(1-42) play a central role in the pathogenesis of Alzheimer disease (AD). Abeta is produced when amyloid precursor protein (APP) is cleaved by beta- and gamma-secretases at the N and C termini of the Abeta domain, respectively. The beta-secretase is membrane-bound aspartyl protease, most commonly known as BACE1. Because BACE1 cleaves APP at the N terminus of the Abeta domain, it catalyzes the first step in Abeta generation. PAR-4 (prostate apoptosis response-4) is a leucine zipper protein that was initially identified to be associated with neuronal degeneration and aberrant Abeta production in models of AD. We now report that the C-terminal domain of PAR-4 is necessary for forming a complex with the cytosolic tail of BACE1 in co-immunoprecipitation assays and in vitro pull-down experiments. Overexpression of PAR-4 significantly increased, whereas silencing of PAR-4 expression by RNA interference significantly decreased, beta-secretase cleavage of APP. These results suggest that PAR-4 may be directly involved in regulating the APP cleavage activity of BACE1. Because the increased BACE1 activity observed in AD patients does not seem to arise from genetic mutations or polymorphisms in BACE1, the identification of PAR-4 as an endogenous regulator of BACE1 activity may have significant implications for developing novel therapeutic strategies for AD.
Collapse
Affiliation(s)
- Jun Xie
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | | |
Collapse
|
38
|
Akbari Y, Hitt BD, Murphy MP, Dagher NN, Tseng BP, Green KN, Golde TE, LaFerla FM. Presenilin regulates capacitative calcium entry dependently and independently of gamma-secretase activity. Biochem Biophys Res Commun 2004; 322:1145-52. [PMID: 15336962 DOI: 10.1016/j.bbrc.2004.07.136] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Indexed: 10/26/2022]
Abstract
Mutations in presenilin-1 and 2 (PS) lead to increased intracellular calcium stores and an attenuation in the refilling mechanism known as capacitative calcium entry (CCE). Previous studies have shown that the mechanism by which PS modulates intracellular calcium signaling is dependent on gamma-secretase activity. Although the modulation of intracellular calcium signaling can lead to alterations in CCE, it is plausible that PS can also directly affect CCE independent of the effect it exerts on intracellular stores. To investigate this possibility, we studied the effects of the dominant negative variant of PS1 known as DeltaTM1-2, which lacks the first two transmembrane domains of PS1 and in which gamma-secretase activity is abrogated. We demonstrate that, like other dominant negative isoforms of PS1, DeltaTM1-2 expression leads to reduced intracellular calcium. However, unlike other dominant negative isoforms, DeltaTM1-2 leads to a deficit rather than a potentiation of CCE. These data suggest that changes in the structural components of presenilin can modulate CCE independent of its function in gamma-secretase activity and intracellular calcium stores.
Collapse
Affiliation(s)
- Yama Akbari
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4545, USA
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Esposito L, Gan L, Yu GQ, Essrich C, Mucke L. Intracellularly generated amyloid-β peptide counteracts the antiapoptotic function of its precursor protein and primes proapoptotic pathways for activation by other insults in neuroblastoma cells. J Neurochem 2004; 91:1260-74. [PMID: 15584903 DOI: 10.1111/j.1471-4159.2004.02816.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Most mutations in amyloid precursor proteins (APPs) linked to early onset familial Alzheimer's disease (FAD) increase the production of amyloid-beta peptides ending at residue 42 (Abeta42), which are released from APP by beta- and gamma-secretase cleavage. Stably transfected cells expressing wild-type human APP (APP(WT)) were more resistant to apoptosis-inducing treatments than cells expressing FAD-mutant human APP (APP(FAD)). Preventing Abeta42 production with an M596I mutation (beta-), which blocks beta-secretase cleavage of APP, or by treatment with a gamma-secretase inhibitor increased the resistance of APP(FAD)-expressing cells to apoptosis. Exposing hAPP(FAD/beta-) cells to exogenous Abeta42 or conditioned medium from Abeta42-producing APP(FAD) cells did not diminish their resistance to apoptosis. Preventing APP from entering the distal secretory pathway, where most Abeta peptides are generated, by retaining APP in the endoplasmic reticulum (ER)/intermediate compartment (IC) increased the resistance of APP(FAD)-expressing cells to apoptosis and did not alter the resistance of APP(WT)-expressing cells. p53-mediated gene transactivation after apoptosis-inducing treatments was much stronger in APP(FAD) cells than in hAPP(WT) or hAPP(FAD/beta-) cells. In contrast, upon induction of ER stress, cells expressing APP(FAD), hAPP(FAD/beta-), or APP(WT) had comparable levels of glucose-regulated protein-78 mRNA, an unfolded protein response indicator. We conclude that Abeta, especially intracellular Abeta, counteracts the antiapoptotic function of its precursor protein and predisposes cells to p53-mediated, and possibly other, proapoptotic pathways.
Collapse
Affiliation(s)
- Luke Esposito
- Gladstone Institute of Neurological Disease, Department of Neurology, University of California, San Francisco, California, USA
| | | | | | | | | |
Collapse
|
40
|
Peers C, Kemp PJ. Ion channel regulation by chronic hypoxia in models of acute oxygen sensing. Cell Calcium 2004; 36:341-8. [PMID: 15261490 DOI: 10.1016/j.ceca.2004.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2004] [Accepted: 02/18/2004] [Indexed: 10/26/2022]
Abstract
Several potentially life-threatening cardiovascular and respiratory disorders result in prolonged deprivation of oxygen, which in turn results in significant cellular adaptation, or remodelling. An important component of this functional adaptation arises as a direct consequence of altered ion channel expression by chronic hypoxia. In this review, we discuss current understanding of this hypoxic remodelling process, with particular reference to regulation of L-type Ca2+ channels and high-conductance, Ca2+-sensitive K+ (BK) channels. In systems where this remodelling occurs, changes in functional expression of these particular channels evokes marked alteration in, or responses to, Ca2+-dependent events. Evidence to date indicates that channel expression can be modulated at the transcriptional level but, additionally, that crucial post-transcriptional events are also regulated by chronic hypoxia. Importantly, such remodelling is, in some cases, strongly associated with production of amyloid peptides of Alzheimer's disease, implicating chronic hypoxia as a causative factor in the progression of specific pathology. Moreover, subtle changes in functional expression of BK channels implicates chronic hypoxia as an important regulator of cell excitability.
Collapse
Affiliation(s)
- Chris Peers
- School of Medicine, University of Leeds, Leeds LS2 9JT, UK.
| | | |
Collapse
|
41
|
Cervantes S, Saura CA, Pomares E, Gonzàlez-Duarte R, Marfany G. Functional Implications of the Presenilin Dimerization. J Biol Chem 2004; 279:36519-29. [PMID: 15220354 DOI: 10.1074/jbc.m404832200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Presenilins are the catalytic components of gamma-secretase, an intramembrane-cleaving protease whose substrates include beta-amyloid precursor protein (betaAPP) and the Notch receptors. These type I transmembrane proteins undergo two distinct presenilin-dependent cleavages within the transmembrane region, which result in the production of Abeta and APP intracellular domain (from betaAPP) and the Notch intracellular domain signaling peptide. Most cases of familial Alzheimer's disease are caused by presenilin mutations, which are scattered throughout the coding sequence. Although the underlying molecular mechanism is not yet known, the familial Alzheimer's disease mutations produce a shift in the ratio of the long and short forms of the Abeta peptide generated by the gamma-secretase. We and others have previously shown that presenilin homodimerizes and suggested that a presenilin dimer is at the catalytic core of gamma-secretase. Here, we demonstrate that presenilin transmembrane domains contribute to the formation of the dimer. In-frame substitution of the hydrophilic loop 1, located between transmembranes I and II, which modulates the interactions within the N-terminal fragment/N-terminal fragment dimer, abolishes both presenilinase and gamma-secretase activities. In addition, by reconstituting gamma-secretase activity from two catalytically inactive presenilin aspartic mutants, we provide evidence of an active diaspartyl group assembled at the interface between two presenilin monomers. Under our conditions, this catalytic group mediates the generation of APP intracellular domain and Abeta but not Notch intracellular domain, therefore suggesting that specific diaspartyl groups within the presenilin catalytic core of gamma-secretase mediate the cleavage of different substrates.
Collapse
Affiliation(s)
- Sara Cervantes
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, E-08028 Barcelona, Spain
| | | | | | | | | |
Collapse
|
42
|
Lleó A, Berezovska O, Growdon JH, Hyman BT. Clinical, pathological, and biochemical spectrum of Alzheimer disease associated with PS-1 mutations. Am J Geriatr Psychiatry 2004; 12:146-56. [PMID: 15010344 DOI: 10.1097/00019442-200403000-00006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Three genes have been implicated in the etiology of early-onset autosomal-dominant Alzheimer disease (AD): the amyloid precursor protein, the presenilin-1, and presenilin-2 genes. Approximately half of autosomal-dominant AD cases are associated with mutations in the presenilin-1 (PS-1) gene on the long arm of Chromosome 14. Marked allelic heterogeneity characterizes families with PS-1 gene mutations; more than 100 different mutations have been found in independent families thus far. With the exception of age at onset, the clinical phenotype is similar to late-onset AD, although some rare specific phenotypes have been described. These mutations lead to enhanced deposition of total Abeta and Abeta42 (but not Abeta40) in the brain, compared with sporadic AD. There is a considerable heterogeneity in the histological profiles among brains from patients with different mutations, and although some lead to predominantly parenchymal deposition of Abeta in the form of diffuse and cored plaques, others show predominantly vascular deposition, with severe amyloid angiopathy. Only some mutations are associated with enhanced neurofibrillary tangle formation and increased neuronal loss compared with sporadic AD. However, there is an important clinical and pathological variability even among family members with the same mutation, which suggests the involvement of other genetic or environmental factors that modulate the clinical expression of the disease. This represents a valuable model for identifying such factors and has potential implications for the development of new therapeutic strategies for delaying disease onset.
Collapse
Affiliation(s)
- Alberto Lleó
- Massachusetts General Hospital, Alzheimer Research Unit, Charleston, MA 02129, USA
| | | | | | | |
Collapse
|
43
|
Wilhelmsen K, van der Geer P. Phorbol 12-myristate 13-acetate-induced release of the colony-stimulating factor 1 receptor cytoplasmic domain into the cytosol involves two separate cleavage events. Mol Cell Biol 2004; 24:454-64. [PMID: 14673177 PMCID: PMC303356 DOI: 10.1128/mcb.24.1.454-464.2004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The colony-stimulating factor 1 (CSF-1) receptor is a protein-tyrosine kinase that regulates cell division, differentiation, and development. In response to phorbol 12-myristate 13-acetate (PMA), the CSF-1 receptor is subject to proteolytic processing. Use of chimeric receptors indicates that the CSF-1 receptor is cleaved at least two times, once in the extracellular domain and once in the transmembrane domain. Cleavage in the extracellular domain results in ectodomain shedding while the cytoplasmic domain remains associated with the membrane. Intramembrane cleavage depends on the sequence of the transmembrane domain and results in the release of the cytoplasmic domain. This process can be blocked by gamma-secretase inhibitors. The cytoplasmic domain localizes partially to the nucleus, displays limited stability, and is degraded by the proteosome. CSF-1 receptors are continuously subject to down-modulation and regulated intramembrane proteolysis (RIP). RIP is stimulated by granulocyte-macrophage-CSF, CSF-1, interleukin-2 (IL-2), IL-4, lipopolysaccharide, and PMA and may provide the CSF-1 receptor with an additional mechanism for signal transduction.
Collapse
Affiliation(s)
- Kevin Wilhelmsen
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0601, USA
| | | |
Collapse
|
44
|
Tesco G, Koh YH, Tanzi RE. Caspase activation increases beta-amyloid generation independently of caspase cleavage of the beta-amyloid precursor protein (APP). J Biol Chem 2003; 278:46074-80. [PMID: 12960154 DOI: 10.1074/jbc.m307809200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amyloid precursor protein (APP) undergoes "alternative" proteolysis mediated by caspases. Three major caspase recognition sites have been identified in the APP, i.e. one at the C terminus (Asp720) and two at the N terminus (Asp197 and Asp219). Caspase cleavage at Asp720 has been suggested as leading to increased production of Abeta. Thus, we set out to determine which putative caspase sites in APP, if any, are cleaved in Chinese hamster ovary cell lines concurrently with the increased Abeta production that occurs during apoptosis. We found that cleavage at Asp720 occurred concurrently with caspase 3 activation and the increased production of total secreted Abeta and Abeta1-42 in association with staurosporine- and etoposide-induced apoptosis. To investigate the contribution of caspase cleavage of APP to Abeta generation, we expressed an APP mutant truncated at Asp720 that mimics APP caspase cleavage at the C-terminal site. This did not increase Abeta generation but, in contrast, dramatically decreased Abeta production in Chinese hamster ovary cells. Furthermore, the ablation of caspase-dependent cleavage at Asp720, Asp197, and Asp219 (by site-directed mutagenesis) did not prevent enhanced Abeta production following etoposide-induced apoptosis. These findings indicate that the enhanced Abeta generation associated with apoptosis does not require cleavage of APP at its C-terminal (Asp720) and/or N-terminal caspase sites.
Collapse
Affiliation(s)
- Giuseppina Tesco
- Genetics and Aging Research Unit, Center for Aging, Genetics and Neurodegeneration, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachussetts 02129, USA
| | | | | |
Collapse
|
45
|
Ling Y, Morgan K, Kalsheker N. Amyloid precursor protein (APP) and the biology of proteolytic processing: relevance to Alzheimer's disease. Int J Biochem Cell Biol 2003; 35:1505-35. [PMID: 12824062 DOI: 10.1016/s1357-2725(03)00133-x] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The processing of amyloid precursor protein (APP) generates amyloid-beta (Abeta) peptides 1-40 and 1-42. The latter is neurotoxic and its accumulation results in amyloid fibril formation and the generation of senile plaques, the hallmark of Alzheimer's disease (AD). Whilst there has been considerable progress made in understanding the generation of Abeta by alpha-, beta- and gamma-secretase activity on APP, recently enzymes involved in the degradation of Abeta have been identified including neprilysin and insulin-degrading enzyme (IDE). We review the pathways involved in proteolytic processing of APP and discuss the potential implications of aberrant proteolysis on neurodegeneration. It is conceivable that single nucleotide polymorphisms (SNPs) in the regulatory regions of genes in these proteolytic cascades, which alter their expression, could contribute to some of the age-related changes seen in AD.
Collapse
Affiliation(s)
- Yan Ling
- Division of Clinical Chemistry, Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | | | | |
Collapse
|
46
|
Schroeter EH, Ilagan MXG, Brunkan AL, Hecimovic S, Li YM, Xu M, Lewis HD, Saxena MT, De Strooper B, Coonrod A, Tomita T, Iwatsubo T, Moore CL, Goate A, Wolfe MS, Shearman M, Kopan R. A presenilin dimer at the core of the gamma-secretase enzyme: insights from parallel analysis of Notch 1 and APP proteolysis. Proc Natl Acad Sci U S A 2003; 100:13075-80. [PMID: 14566063 PMCID: PMC240747 DOI: 10.1073/pnas.1735338100] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Notch receptors and the amyloid precursor protein are type I membrane proteins that are proteolytically cleaved within their transmembrane domains by a presenilin (PS)-dependent gamma-secretase activity. In both proteins, two peptide bonds are hydrolyzed: one near the inner leaflet and the other in the middle of the transmembrane domain. Under saturating conditions the substrates compete with each other for proteolysis, but not for binding to PS. At least some Alzheimer's disease-causing PS mutations reside in proteins possessing low catalytic activity. We demonstrate (i) that differentially tagged PS molecules coimmunoprecipitate, and (ii) that PS N-terminal fragment dimers exist by using a photoaffinity probe based on a transition state analog gamma-secretase inhibitor. We propose that gamma-secretase contains a PS dimer in its catalytic core, that binding of substrate is at a site separate from the active site, and that substrate is cleaved at the interface of two PS molecules.
Collapse
Affiliation(s)
- Eric H. Schroeter
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Ma. Xenia G. Ilagan
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Anne L. Brunkan
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Silva Hecimovic
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Yue-ming Li
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Min Xu
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Huw D. Lewis
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Meera T. Saxena
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Bart De Strooper
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Archie Coonrod
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Taisuke Tomita
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Takeshi Iwatsubo
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Chad L. Moore
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Alison Goate
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Michael S. Wolfe
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Mark Shearman
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
| | - Raphael Kopan
- Departments of Molecular Biology and Pharmacology and Psychiatry, Washington University School of Medicine, St. Louis, MO 63110; Department of Biological Chemistry, Merck Research Laboratories, West Point, PA 19486-0004; Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan; Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom; Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115; Department of Pharmaceutical Sciences, University of Tennessee, Memphis, TN 38163; and Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Katholieke Universiteit and Flanders Interuniversity Institute for Biotechnology, VIB4 Leuven, Belgium
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
47
|
Abstract
Presenilins (PS) constitute a fascinating family of proteins that play crucial roles in several major signalling processes involved in key cellular functions and are also closely associated with dysfunction in Alzheimer's disease (AD). Presenilin-dependent intramembrane cleavage of transmembrane proteins such as amyloid beta precursor protein (AbetaPP) and Notch resides in a high-molecular-weight gamma-secretase protein complex, of which at least five core components have now been identified. Remarkably, it has now become evident that presenilin-dependent gamma-secretase activity extends beyond its role in AbetaPP and Notch cleavages to have a generic role in the regulated intramembranous cleavage of certain membrane proteins. Actually, a new picture is emerging in which cells can relay signals from the extracellular space to their interior through presenilin-dependent proteolysis within the membrane-spanning regions of type 1 integral membrane proteins to generate potential transcriptionally active intracellular fragments. This review deals with the complex biology of presenilins and focuses more specifically on recent developments regarding the composition, assembly and regulation of the gamma-secretase protein complex, its substrates and its implications for cellular signalling.
Collapse
Affiliation(s)
- Miguel Medina
- Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, AO San Luigi Gonzaga, Regione Gonzole 10, Orbassano, Turin 10043, Italy.
| | | |
Collapse
|
48
|
Sagi SA, Weggen S, Eriksen J, Golde TE, Koo EH. The non-cyclooxygenase targets of non-steroidal anti-inflammatory drugs, lipoxygenases, peroxisome proliferator-activated receptor, inhibitor of kappa B kinase, and NF kappa B, do not reduce amyloid beta 42 production. J Biol Chem 2003; 278:31825-30. [PMID: 12805355 DOI: 10.1074/jbc.m303588200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Epidemiological evidence suggests that chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) reduces the risk of Alzheimer's disease. Recently, NSAIDs have been shown to decrease amyloid pathology in a transgenic mouse model of Alzheimer's disease. This benefit may be partially attributable to the ability of NSAIDs to selectively reduce production of the amyloidogenic A beta 42 peptide in both cultured cells and transgenic mice. Although this activity does not appear to require the action of cyclooxygenases in cultured cells, it is not known whether other NSAID-sensitive targets contribute to this A beta 42 effect. In this study, we have used both pharmacological and genetic means to determine if other known cellular targets of NSAIDs could mediate the reduction in A beta 42 secretion from cultured cells. We find that altered arachidonic acid metabolism via NSAID action on cyclooxygenases and lipoxygenases does not alter A beta 42 production. Furthermore, we demonstrate that alterations in activity of peroxisome proliferator-activated receptors, I kappa B kinase beta or nuclear factor kappa B do not affect A beta 42 production. Thus, NSAIDs do not appear to alter A beta 42 production indirectly through previously identified cellular targets and may interact directly with the gamma-secretase complex itself to affect amyloid production.
Collapse
Affiliation(s)
- Sarah A Sagi
- Department of Neurosciences, University of California San Diego, La Jolla, California 921093, USA
| | | | | | | | | |
Collapse
|
49
|
Weggen S, Eriksen JL, Sagi SA, Pietrzik CU, Ozols V, Fauq A, Golde TE, Koo EH. Evidence that nonsteroidal anti-inflammatory drugs decrease amyloid beta 42 production by direct modulation of gamma-secretase activity. J Biol Chem 2003; 278:31831-7. [PMID: 12805356 DOI: 10.1074/jbc.m303592200] [Citation(s) in RCA: 231] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a lower risk of developing Alzheimer's disease. Recent evidence indicates that some NSAIDs specifically inhibit secretion of the amyloidogenic A beta 42 peptide in cultured cells and mouse models of Alzheimer's disease. The reduction of A beta 42 peptides is not mediated by inhibition of cyclooxygenases (COX) but the molecular mechanism underlying this novel activity of NSAIDs has not been further defined. We now demonstrate that NSAIDs efficiently reduce the intracellular pool of A beta 42 in cell-based studies and selectively decrease A beta 42 production in a cell-free assay of gamma-secretase activity. Moreover, we find that presenilin-1 (PS1) mutations, which affect gamma-secretase activity, differentially modulate the cellular A beta 42 response to NSAID treatment. Overexpression of the PS1-M146L mutation enhances the cellular drug response to A beta 42 lowering NSAIDs as compared with cells expressing wild-type PS1. In contrast, expression of the PS1-Delta Exon9 mutation strongly diminishes the A beta 42 response, showing that PS1 mutations can modulate the cellular drug response to NSAID treatment both positively and negatively. Enhancement of the NSAID drug response was also observed with overexpression of the APP V717F mutation but not with Swedish mutant APP, which affects beta-secretase cleavage. In sum, these results strongly suggest that NSAIDs represent a founding group of compounds that lower A beta 42 production by direct modulation of gamma-secretase activity or its substrate.
Collapse
Affiliation(s)
- Sascha Weggen
- Department of Neurosciences, University of California San Diego, La Jolla, California 92093, USA
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Eriksen JL, Sagi SA, Smith TE, Weggen S, Das P, McLendon DC, Ozols VV, Jessing KW, Zavitz KH, Koo EH, Golde TE. NSAIDs and enantiomers of flurbiprofen target gamma-secretase and lower Abeta 42 in vivo. J Clin Invest 2003; 112:440-9. [PMID: 12897211 PMCID: PMC166298 DOI: 10.1172/jci18162] [Citation(s) in RCA: 360] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Epidemiologic studies demonstrate that long-term use of NSAIDs is associated with a reduced risk for the development of Alzheimer disease (AD). In this study, 20 commonly used NSAIDs, dapsone, and enantiomers of flurbiprofen were analyzed for their ability to lower the level of the 42-amino-acid form of amyloid beta protein (Abeta42) in a human H4 cell line. Thirteen of the NSAIDs and the enantiomers of flurbiprofen were then tested in acute dosing studies in amyloid beta protein precursor (APP) transgenic mice, and plasma and brain levels of Abeta and the drug were evaluated. These studies show that (a). eight FDA-approved NSAIDs lower Abeta42 in vivo, (b). the ability of an NSAID to lower Abeta42 levels in cell culture is highly predicative of its in vivo activity, (c). in vivo Abeta42 lowering in mice occurs at drug levels achievable in humans, and (d). there is a significant correlation between Abeta42 lowering and levels of ibuprofen. Importantly, flurbiprofen and its enantiomers selectively lower Abeta42 levels in broken cell gamma-secretase assays, indicating that these compounds directly target the gamma-secretase complex that generates Abeta from APP. Of the compounds tested, meclofenamic acid, racemic flurbiprofen, and the purified R and S enantiomers of flurbiprofen lowered Abeta42 levels to the greatest extent. Because R-flurbiprofen reduces Abeta42 levels by targeting gamma-secretase and has reduced side effects related to inhibition of cyclooxygenase (COX), it is an excellent candidate for clinical testing as an Abeta42 lowering agent.
Collapse
Affiliation(s)
- Jason L Eriksen
- Department of Neuroscience, Mayo Graduate School, Mayo Clinic Jacksonville, Jacksonville, Florida 32224, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|