The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Dennis J Selkoe - One of the best experts on this subject based on the ideXlab platform.
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peroxisome proliferator activated receptor gamma enhances the activity of an insulin degrading Enzyme like metalloprotease for amyloid beta clearance
Journal of Alzheimer's Disease, 2010Co-Authors: Ira Espunycamacho, Dennis J Selkoe, Diana Ines Dominguez, Pascal Gerard Merchiers, Luc Van Rompaey, Bart De StrooperAbstract:Peroxisome proliferator-activated receptor gamma (PPARgamma) activation results in an increased rate of amyloid-beta (Abeta) clearance from the media of diverse cells in culture, including primary neurons and glial cells. Here, we further investigate the mechanism for Abeta clearance and found that PPARgamma activation modulates a cell surface metalloprotease that can be inhibited by metalloprotease inhibitors, like EDTA and phenanthroline, and also by the peptide hormones insulin and glucagon. The metalloprotease profile of the Abeta-degrading mechanism is surprisingly similar to Insulin-Degrading Enzyme (IDE). This mechanism is maintained in hippocampal and glia primary cultures from IDE loss-of-function mice. We conclude that PPARgamma activates an IDE-like Abeta degrading activity. Our work suggests a drugable pathway that can clear Abeta peptide from the brain.
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small molecule activators of insulin degrading Enzyme discovered through high throughput compound screening
PLOS ONE, 2009Co-Authors: Christelle Cabrol, Dennis J Selkoe, Malwina Huzarska, Christopher Dinolfo, Maria C Rodriguez, Lael Reinstatler, Li An Yeh, Gregory D Cuny, Ross L Stein, Malcolm A LeissringAbstract:Background: Hypocatabolism of the amyloid b-protein (Ab) by Insulin-Degrading Enzyme (IDE) is implicated in the pathogenesis of Alzheimer disease (AD), making pharmacological activation of IDE an attractive therapeutic strategy. However, it has not been established whether the proteolytic activity of IDE can be enhanced by drug-like compounds. Methodology/Principal Findings: Based on the finding that ATP and other nucleotide polyphosphates modulate IDE activity at physiological concentrations, we conducted parallel high-throughput screening campaigns in the absence or presence of ATP and identified two compounds—designated Ia1 and Ia2—that significantly stimulate IDE proteolytic activity. Both compounds were found to interfere with the crosslinking of a photoaffinity ATP analogue to IDE, suggesting that they interact with a bona fide ATP-binding domain within IDE. Unexpectedly, we observed highly synergistic activation effects when the activity of Ia1 or Ia2 was tested in the presence of ATP, a finding that has implications for the mechanisms underlying ATP-mediated activation of IDE. Notably, Ia1 and Ia2 activated the degradation of Ab by ,700% and ,400%, respectively, albeit only when Ab was presented in a mixture also containing shorter substrates. Conclusions/Significance: This study describes the first examples of synthetic small-molecule activators of IDE, showing that pharmacological activation of this important protease with drug-like compounds is achievable. These novel activators help to establish the putative ATP-binding domain as a key modulator of IDE proteolytic activity and offer new insights into the modulatory action of ATP. Several larger lessons abstracted from this screen will help inform the design of future screening campaigns and facilitate the eventual development of IDE activators with therapeutic utility.
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partial loss of function mutations in insulin degrading Enzyme that induce diabetes also impair degradation of amyloid β protein
American Journal of Pathology, 2004Co-Authors: Wesley Farris, Lars Bertram, Malcolm A Leissring, Stefan Mansourian, Elizabeth A Eckman, Christopher B Eckman, Rudolph E Tanzi, Dennis J SelkoeAbstract:The causes of cerebral accumulation of amyloid β-protein (Aβ) in most cases of Alzheimer's disease (AD) remain unknown. We recently found that homozygous deletion of the Insulin-Degrading Enzyme (IDE) gene in mice results in an early and marked elevation of cerebral Aβ. Both genetic linkage and allelic association in the IDE region of chromosome 10 have been reported in families with late-onset AD. For IDE to remain a valid candidate gene for late-onset AD on functional grounds, it must be shown that partial loss of function of IDE can still alter Aβ degradation, but without causing early, severe elevation of brain Aβ. Here, we show that naturally occurring IDE missense mutations in a well-characterized rat model of type 2 diabetes mellitus (DM2) result in decreased catalytic efficiency and a significant ∼15 to 30% deficit in the degradation of both insulin and Aβ. Endogenously secreted Aβ 40 and Aβ 42 are significantly elevated in primary neuronal cultures from animals with the IDE mutations, but there is no increase in steady-state levels of rodent Aβ in the brain up to age 14 months. We conclude that naturally occurring, partial loss-of-function mutations in IDE sufficient to cause DM2 also impair neuronal regulation of Aβ levels, but the brain can apparently compensate for the partial deficit during the life span of the rat. Our findings have relevance for the emerging genetic evidence suggesting that IDE may be a late-onset AD-risk gene, and for the epidemiological relationships among hyperinsulinemia, DM2, and AD.
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enhanced proteolysis of β amyloid in app transgenic mice prevents plaque formation secondary pathology and premature death
Neuron, 2003Co-Authors: Malcolm A Leissring, Wesley Farris, Alice Y Chang, Dominic M Walsh, Xining Wu, Matthew P Frosch, Dennis J SelkoeAbstract:Converging evidence suggests that the accumulation of cerebral amyloid β-protein (Aβ) in Alzheimer's disease (AD) reflects an imbalance between the production and degradation of this self-aggregating peptide. Upregulation of proteases that degrade Aβ thus represents a novel therapeutic approach to lowering steady-state Aβ levels, but the consequences of sustained upregulation in vivo have not been studied. Here we show that transgenic overexpression of Insulin-Degrading Enzyme (IDE) or neprilysin (NEP) in neurons significantly reduces brain Aβ levels, retards or completely prevents amyloid plaque formation and its associated cytopathology, and rescues the premature lethality present in amyloid precursor protein (APP) transgenic mice. Our findings demonstrate that chronic upregulation of Aβ-degrading proteases represents an efficacious therapeutic approach to combating Alzheimer-type pathology in vivo.
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insulin degrading Enzyme regulates the levels of insulin amyloid β protein and the β amyloid precursor protein intracellular domain in vivo
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Wesley Farris, Dennis J Selkoe, Matthew P Frosch, Stefan Mansourian, Yang Chang, Loren Lindsley, Elizabeth A Eckman, Christopher B Eckman, Rudolph E Tanzi, Suzanne Y GuenetteAbstract:Two substrates of Insulin-Degrading Enzyme (IDE), amyloid beta-protein (Abeta) and insulin, are critically important in the pathogenesis of Alzheimer's disease (AD) and type 2 diabetes mellitus (DM2), respectively. We previously identified IDE as a principal regulator of Abeta levels in neuronal and microglial cells. A small chromosomal region containing a mutant IDE allele has been associated with hyperinsulinemia and glucose intolerance in a rat model of DM2. Human genetic studies have implicated the IDE region of chromosome 10 in both AD and DM2. To establish whether IDE hypofunction decreases Abeta and insulin degradation in vivo and chronically increases their levels, we characterized mice with homozygous deletions of the IDE gene (IDE --). IDE deficiency resulted in a >50% decrease in Abeta degradation in both brain membrane fractions and primary neuronal cultures and a similar deficit in insulin degradation in liver. The IDE -- mice showed increased cerebral accumulation of endogenous Abeta, a hallmark of AD, and had hyperinsulinemia and glucose intolerance, hallmarks of DM2. Moreover, the mice had elevated levels of the intracellular signaling domain of the beta-amyloid precursor protein, which was recently found to be degraded by IDE in vitro. Together with emerging genetic evidence, our in vivo findings suggest that IDE hypofunction may underlie or contribute to some forms of AD and DM2 and provide a mechanism for the recently recognized association among hyperinsulinemia, diabetes, and AD.
Jeffrey I Cohen - One of the best experts on this subject based on the ideXlab platform.
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the insulin degrading Enzyme binding domain of varicella zoster virus vzv glycoprotein e is important for cell to cell spread and vzv infectivity while a glycoprotein i binding domain is essential for infection
Virology, 2009Co-Authors: Mir A Ali, Elizabeth R Fischer, Jeffrey I CohenAbstract:Varicella-zoster virus (VZV) glycoprotein E (gE) interacts with glycoprotein I and with insulin degrading Enzyme (IDE), which is a receptor for the virus. We found that a VZV gE deletion mutant could only be grown in cells expressing gE. Expression of VZV gE on the surface of cells did not interfere with VZV infection. HSV deleted for gE is impaired for cell-to-cell spread; VZV gE could not complement this activity in an HSV gE null mutant. VZV lacking the IDE binding domain of gE grew to peak titers nearly equivalent to parental virus; however, it was impaired for cell-to-cell spread and for infectivity with cell-free virus. VZV deleted for a region of gE that binds glycoprotein I could not replicate in cell culture unless grown in cells expressing gE. We conclude that the IDE binding domain is important for efficient cell-to-cell spread and infectivity of cell-free virus.
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the amino terminus of varicella zoster virus vzv glycoprotein e is required for binding to insulin degrading Enzyme a vzv receptor
Journal of Virology, 2007Co-Authors: Tammy Krogmann, Weijen Tang, Mir A Ali, Jeffrey I CohenAbstract:Varicella-zoster virus (VZV) glycoprotein E (gE) is required for VZV infection. Although gE is well conserved among alphaherpesviruses, the amino terminus of VZV gE is unique. Previously, we showed that gE interacts with Insulin-Degrading Enzyme (IDE) and facilitates VZV infection and cell-to-cell spread of the virus. Here we define the region of VZV gE required to bind IDE. Deletion of amino acids 32 to 71 of gE, located immediately after the predicted signal peptide, resulted in loss of the ability of gE to bind IDE. A synthetic peptide corresponding to amino acids 24 to 50 of gE blocked its interaction with IDE in a concentration-dependent manner. However, a chimeric gE in which amino acids 1 to 71 of VZV gE were fused to amino acids 30 to 545 of herpes simplex virus type 2 gE did not show an increased level of binding to IDE compared with that of full-length HSV gE. Thus, amino acids 24 to 71 of gE are required for IDE binding, and the secondary structure of gE is critical for the interaction. VZV gE also forms a heterodimer with glycoprotein gI. Deletion of amino acids 163 to 208 of gE severely reduced its ability to form a complex with gI. The amino portion of IDE, as well an IDE mutant in the catalytic domain of the protein, bound to gE. Therefore, distinct motifs of VZV gE are important for binding to IDE or to gI.
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insulin degrading Enzyme is a cellular receptor mediating varicella zoster virus infection and cell to cell spread
Cell, 2006Co-Authors: Mir A Ali, Jeffrey I CohenAbstract:Varicella-zoster virus (VZV) causes chickenpox and shingles. While varicella is likely spread as cell-free virus to susceptible hosts, the virus is transmitted by cell-to-cell spread in the body and in vitro. Since VZV glycoprotein E (gE) is essential for virus infection, we postulated that gE binds to a cellular receptor. We found that Insulin-Degrading Enzyme (IDE) interacts with gE through its extracellular domain. Downregulation of IDE by siRNA, or blocking of IDE with antibody, with soluble IDE protein extracted from liver, or with bacitracin inhibited VZV infection. Cell-to-cell spread of virus was also impaired by blocking IDE. Transfection of cell lines impaired for VZV infection with a plasmid expressing human IDE resulted in increased entry and enhanced infection with cell-free and cell-associated virus. These studies indicate that IDE is a cellular receptor for both cell-free and cell-associated VZV.
Dominic M Walsh - One of the best experts on this subject based on the ideXlab platform.
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enhanced proteolysis of β amyloid in app transgenic mice prevents plaque formation secondary pathology and premature death
Neuron, 2003Co-Authors: Malcolm A Leissring, Wesley Farris, Alice Y Chang, Dominic M Walsh, Xining Wu, Matthew P Frosch, Dennis J SelkoeAbstract:Converging evidence suggests that the accumulation of cerebral amyloid β-protein (Aβ) in Alzheimer's disease (AD) reflects an imbalance between the production and degradation of this self-aggregating peptide. Upregulation of proteases that degrade Aβ thus represents a novel therapeutic approach to lowering steady-state Aβ levels, but the consequences of sustained upregulation in vivo have not been studied. Here we show that transgenic overexpression of Insulin-Degrading Enzyme (IDE) or neprilysin (NEP) in neurons significantly reduces brain Aβ levels, retards or completely prevents amyloid plaque formation and its associated cytopathology, and rescues the premature lethality present in amyloid precursor protein (APP) transgenic mice. Our findings demonstrate that chronic upregulation of Aβ-degrading proteases represents an efficacious therapeutic approach to combating Alzheimer-type pathology in vivo.
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naturally secreted oligomers of amyloid beta protein potently inhibit hippocampal long term potentiation in vivo
Nature, 2002Co-Authors: Dominic M Walsh, Igor Klyubin, Julia V Fadeeva, William K Cullen, Roger Anwyl, Michael S Wolfe, Michael J Rowan, Dennis J SelkoeAbstract:Although extensive data support a central pathogenic role for amyloid beta protein (Abeta) in Alzheimer's disease, the amyloid hypothesis remains controversial, in part because a specific neurotoxic species of Abeta and the nature of its effects on synaptic function have not been defined in vivo. Here we report that natural oligomers of human Abeta are formed soon after generation of the peptide within specific intracellular vesicles and are subsequently secreted from the cell. Cerebral microinjection of cell medium containing these oligomers and abundant Abeta monomers but no amyloid fibrils markedly inhibited hippocampal long-term potentiation (LTP) in rats in vivo. Immunodepletion from the medium of all Abeta species completely abrogated this effect. Pretreatment of the medium with Insulin-Degrading Enzyme, which degrades Abeta monomers but not oligomers, did not prevent the inhibition of LTP. Therefore, Abeta oligomers, in the absence of monomers and amyloid fibrils, disrupted synaptic plasticity in vivo at concentrations found in human brain and cerebrospinal fluid. Finally, treatment of cells with gamma-secretase inhibitors prevented oligomer formation at doses that allowed appreciable monomer production, and such medium no longer disrupted LTP, indicating that synaptotoxic Abeta oligomers can be targeted therapeutically.
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naturally secreted oligomers of amyloid beta protein potently inhibit hippocampal long term potentiation in vivo
Nature, 2002Co-Authors: Dominic M Walsh, Igor Klyubin, Julia V Fadeeva, William K Cullen, Roger Anwyl, Michael S Wolfe, Michael J Rowan, Dennis J SelkoeAbstract:Although extensive data support a central pathogenic role for amyloid β protein (Aβ) in Alzheimer's disease1, the amyloid hypothesis remains controversial, in part because a specific neurotoxic species of Aβ and the nature of its effects on synaptic function have not been defined in vivo. Here we report that natural oligomers of human Aβ are formed soon after generation of the peptide within specific intracellular vesicles and are subsequently secreted from the cell. Cerebral microinjection of cell medium containing these oligomers and abundant Aβ monomers but no amyloid fibrils markedly inhibited hippocampal long-term potentiation (LTP) in rats in vivo. Immunodepletion from the medium of all Aβ species completely abrogated this effect. Pretreatment of the medium with Insulin-Degrading Enzyme, which degrades Aβ monomers but not oligomers, did not prevent the inhibition of LTP. Therefore, Aβ oligomers, in the absence of monomers and amyloid fibrils, disrupted synaptic plasticity in vivo at concentrations found in human brain and cerebrospinal fluid. Finally, treatment of cells with γ-secretase inhibitors prevented oligomer formation at doses that allowed appreciable monomer production, and such medium no longer disrupted LTP, indicating that synaptotoxic Aβ oligomers can be targeted therapeutically.
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neurons regulate extracellular levels of amyloid β protein via proteolysis by insulin degrading Enzyme
The Journal of Neuroscience, 2000Co-Authors: Konstantinos Vekrellis, Marsha Rich Rosner, Dominic M Walsh, Zhen Ye, Dean M Hartley, Valerie Chesneau, Dennis J SelkoeAbstract:Progressive cerebral accumulation of amyloid β-protein (Aβ) is an early and invariant feature of Alzheimer9s disease. Little is known about how Aβ, after being secreted, is degraded and cleared from the extracellular space of the brain. Defective Aβ degradation could be a risk factor for the development of Alzheimer9s disease in some subjects. We reported previously that microglial cells release substantial amounts of an Aβ-degrading protease that, after purification, is indistinguishable from Insulin-Degrading Enzyme (IDE). Here we searched for and characterized a role for IDE in Aβ degradation by neurons, the principal cell type that produces Aβ. Whole cultures of differentiated pheochromocytoma (PC12) cells and primary rat cortical neurons actively degraded endogenously secreted Aβ via IDE. However, unlike that in microglia, IDE in differentiated neurons was not released but localized to the cell surface, as demonstrated by biotinylation. Undifferentiated PC12 cells released IDE into their medium, whereas after differentiation, IDE was cell associated but still degraded Aβ in the medium. Overexpression of IDE in mammalian cells markedly reduced the steady-state levels of extracellular Aβ 40 and Aβ 42 , and the catalytic site mutation (E111Q) abolished this effect. We observed a novel membrane-associated form of IDE that is ∼5 kDa larger than the known cytosolic form in a variety of cells, including differentiated PC12 cells. Our results support a principal role for membrane-associated and secreted IDE isoforms in the degradation and clearance of naturally secreted Aβ by neurons and microglia.
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neurons regulate extracellular levels of amyloid β protein via proteolysis by insulin degrading Enzyme
The Journal of Neuroscience, 2000Co-Authors: Konstantinos Vekrellis, Marsha Rich Rosner, Dominic M Walsh, Wei Qiao Qiu, Dean M Hartley, Valerie Chesneau, Dennis J SelkoeAbstract:Progressive cerebral accumulation of amyloid beta-protein (Abeta) is an early and invariant feature of Alzheimer's disease. Little is known about how Abeta, after being secreted, is degraded and cleared from the extracellular space of the brain. Defective Abeta degradation could be a risk factor for the development of Alzheimer's disease in some subjects. We reported previously that microglial cells release substantial amounts of an Abeta-degrading protease that, after purification, is indistinguishable from Insulin-Degrading Enzyme (IDE). Here we searched for and characterized a role for IDE in Abeta degradation by neurons, the principal cell type that produces Abeta. Whole cultures of differentiated pheochromocytoma (PC12) cells and primary rat cortical neurons actively degraded endogenously secreted Abeta via IDE. However, unlike that in microglia, IDE in differentiated neurons was not released but localized to the cell surface, as demonstrated by biotinylation. Undifferentiated PC12 cells released IDE into their medium, whereas after differentiation, IDE was cell associated but still degraded Abeta in the medium. Overexpression of IDE in mammalian cells markedly reduced the steady-state levels of extracellular Abeta(40) and Abeta(42), and the catalytic site mutation (E111Q) abolished this effect. We observed a novel membrane-associated form of IDE that is approximately 5 kDa larger than the known cytosolic form in a variety of cells, including differentiated PC12 cells. Our results support a principal role for membrane-associated and secreted IDE isoforms in the degradation and clearance of naturally secreted Abeta by neurons and microglia.
Weijen Tang - One of the best experts on this subject based on the ideXlab platform.
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structures of human ccl18 ccl3 and ccl4 reveal molecular determinants for quaternary structures and sensitivity to insulin degrading Enzyme
Journal of Molecular Biology, 2015Co-Authors: Wenguang G Liang, Min Ren, Fan Zhao, Weijen TangAbstract:CC chemokine ligands (CCLs) are 8- to 14-kDa signaling proteins involved in diverse immune functions. While CCLs share similar tertiary structures, oligomerization produces highly diverse quaternary structures that protect chemokines from proteolytic degradation and modulate their functions. CCL18 is closely related to CCL3 and CCL4 with respect to both protein sequence and genomic location, yet CCL18 has distinct biochemical and biophysical properties. Here, we report a crystal structure of human CCL18 and its oligomerization states in solution based on crystallographic and small-angle X-ray scattering analyses. Our data show that CCL18 adopts an α-helical conformation at its N-terminus that weakens its dimerization, explaining CCL18's preference for the monomeric state. Multiple contacts between monomers allow CCL18 to reversibly form a unique open-ended oligomer different from those of CCL3, CCL4, and CCL5. Furthermore, these differences hinge on proline 8, which is conserved in CCL3 and CCL4 but is replaced by lysine in human CCL18. Our structural analyses suggest that a mutation of proline 8 to alanine stabilizes a type 1 β-turn at the N-terminus of CCL4 to prevent dimerization but prevents dimers from making key contacts with each other in CCL3. Thus, the P8A mutation induces depolymerization of CCL3 and CCL4 by distinct mechanisms. Finally, we used structural, biochemical, and functional analyses to unravel why Insulin-Degrading Enzyme degrades CCL3 and CCL4 but not CCL18. Our results elucidate the molecular basis for the oligomerization of three closely related CC chemokines and suggest how oligomerization shapes CCL chemokine function.
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Anti-diabetic activity of Insulin-Degrading Enzyme inhibitors mediated by multiple hormones
Nature, 2014Co-Authors: Juan Pablo Maianti, Weijen Tang, Malcolm A Leissring, Amanda Mcfedries, Zachariah H. Foda, Ralph E. Kleiner, Maureen J. Charron, Markus A. Seeliger, Alan Saghatelian, David R. LiuAbstract:Established treatments for type-2 diabetes include drugs that increase insulin biosynthesis and secretion or improve insulin sensitivity. In theory, inhibition of endogenous insulin degradation could also be effective therapeutically, but despite the identification of the zinc metalloprotease Insulin-Degrading Enzyme (IDE) as the product of a diabetes susceptibility gene, and decades of research, the relationship between IDE activity and glucose homeostasis has remained unclear. Here David Liu and colleagues report the first physiologically active IDE inhibitor, a 20-membered macrocycle that engages a binding pocket away from the Enzyme's catalytic site. Treatment of lean and obese mice with this inhibitor shows that IDE not only regulates insulin abundance and signalling, but also that of glucagon and amylin. Acute IDE inhibition with the new inhibitor leads to substantially improved glucose tolerance. This work demonstrates the potential of IDE as a new target for anti-diabetes therapeutics. The discovery of a selective, physiologically active inhibitor of Insulin-Degrading Enzyme (IDE) illuminates the therapeutic potential of IDE inhibitors for the treatment of diabetes and reveals that IDE regulates in vivo glucagon and amylin, in addition to insulin. Despite decades of speculation that inhibiting endogenous insulin degradation might treat type-2 diabetes^ 1 , 2 , and the identification of IDE (Insulin-Degrading Enzyme) as a diabetes susceptibility gene^ 3 , 4 , the relationship between the activity of the zinc metalloprotein IDE and glucose homeostasis remains unclear. Although Ide ^–/– mice have elevated insulin levels, they exhibit impaired, rather than improved, glucose tolerance that may arise from compensatory insulin signalling dysfunction^ 5 , 6 . IDE inhibitors that are active in vivo are therefore needed to elucidate IDE’s physiological roles and to determine its potential to serve as a target for the treatment of diabetes. Here we report the discovery of a physiologically active IDE inhibitor identified from a DNA-templated macrocycle library. An X-ray structure of the macrocycle bound to IDE reveals that it engages a binding pocket away from the catalytic site, which explains its remarkable selectivity. Treatment of lean and obese mice with this inhibitor shows that IDE regulates the abundance and signalling of glucagon and amylin, in addition to that of insulin. Under physiological conditions that augment insulin and amylin levels, such as oral glucose administration, acute IDE inhibition leads to substantially improved glucose tolerance and slower gastric emptying. These findings demonstrate the feasibility of modulating IDE activity as a new therapeutic strategy to treat type-2 diabetes and expand our understanding of the roles of IDE in glucose and hormone regulation.
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insulin degrading Enzyme modulates the natriuretic peptide mediated signaling response
Journal of Biological Chemistry, 2011Co-Authors: Luis A Ralat, Min Ren, Qing Guo, Todd Funke, Deborah M Dickey, Lincoln R Potter, Weijen TangAbstract:Natriuretic peptides (NPs) are cyclic vasoactive peptide hormones with high therapeutic potential. Three distinct NPs (ANP, BNP, and CNP) can selectively activate natriuretic peptide receptors, NPR-A and NPR-B, raising the cyclic GMP (cGMP) levels. Insulin-Degrading Enzyme (IDE) was found to rapidly cleave ANP, but the functional consequences of such cleavages in the cellular environment and the molecular mechanism of recognition and cleavage remain unknown. Here, we show that reducing expression levels of IDE profoundly alters the response of NPR-A and NPR-B to the stimulation of ANP, BNP, and CNP in cultured cells. IDE rapidly cleaves ANP and CNP, thus inactivating their ability to raise intracellular cGMP. Conversely, reduced IDE expression enhances the stimulation of NPR-A and NPR-B by ANP and CNP, respectively. Instead of proteolytic inactivation, IDE cleavage can lead to hyperactivation of BNP toward NPR-A. Conversely, decreasing IDE expression reduces BNP-mediated signaling. Additionally, the cleavages of ANP and BNP by IDE render them active with NPR-B and a reduction of IDE expression diminishes the ability of ANP and BNP to stimulate NPR-B. Our kinetic and crystallographic analyses offer the molecular basis for the selective degradation of NPs and their variants by IDE. Furthermore, our studies reveal how IDE utilizes its catalytic chamber and exosite to engulf and bind up to two NPs leading to biased stochastic, non-sequential cleavages and the ability of IDE to switch its substrate selectivity. Thus, the evolutionarily conserved IDE may play a key role in modulating and reshaping the strength and duration of NP-mediated signaling.
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polymerization of mip 1 chemokine ccl3 and ccl4 and clearance of mip 1 by insulin degrading Enzyme
The EMBO Journal, 2010Co-Authors: Martin Lenz, Feng Qian, Rory R Koenen, Hua Xu, Alexander B Schilling, Christian Weber, Richard D Ye, Aaron R Dinner, Weijen TangAbstract:Macrophage inflammatory protein-1 (MIP-1), MIP-1α (CCL3) and MIP-1β (CCL4) are chemokines crucial for immune responses towards infection and inflammation. Both MIP-1α and MIP-1β form high-molecular-weight aggregates. Our crystal structures reveal that MIP-1 aggregation is a polymerization process and human MIP-1α and MIP-1β form rod-shaped, double-helical polymers. Biophysical analyses and mathematical modelling show that MIP-1 reversibly forms a polydisperse distribution of rod-shaped polymers in solution. Polymerization buries receptor-binding sites of MIP-1α, thus depolymerization mutations enhance MIP-1α to arrest monocytes onto activated human endothelium. However, same depolymerization mutations render MIP-1α ineffective in mouse peritoneal cell recruitment. Mathematical modelling reveals that, for a long-range chemotaxis of MIP-1, polymerization could protect MIP-1 from proteases that selectively degrade monomeric MIP-1. Insulin-Degrading Enzyme (IDE) is identified as such a protease and decreased expression of IDE leads to elevated MIP-1 levels in microglial cells. Our structural and proteomic studies offer a molecular basis for selective degradation of MIP-1. The regulated MIP-1 polymerization and selective inactivation of MIP-1 monomers by IDE could aid in controlling the MIP-1 chemotactic gradient for immune surveillance.
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molecular basis for the recognition and cleavages of igf ii tgf alpha and amylin by human insulin degrading Enzyme
Journal of Molecular Biology, 2010Co-Authors: Qing Guo, Alexander B Schilling, Marika Manolopoulou, Yao Bian, Weijen TangAbstract:Insulin-Degrading Enzyme (IDE) is involved in the clearance of many bioactive peptide substrates, including insulin and amyloid-beta, peptides vital to the development of diabetes and Alzheimer's disease, respectively. IDE can also rapidly degrade hormones that are held together by intramolecular disulfide bond(s) without their reduction. Furthermore, IDE exhibits a remarkable ability to preferentially degrade structurally similar peptides such as the selective degradation of insulin-like growth factor (IGF)-II and transforming growth factor-alpha (TGF-alpha) over IGF-I and epidermal growth factor, respectively. Here, we used high-accuracy mass spectrometry to identify the cleavage sites of human IGF-II, TGF-alpha, amylin, reduced amylin, and amyloid-beta by human IDE. We also determined the structures of human IDE-IGF-II and IDE-TGF-alpha at 2.3 A and IDE-amylin at 2.9 A. We found that IDE cleaves its substrates at multiple sites in a biased stochastic manner. Furthermore, the presence of a disulfide bond in amylin allows IDE to cut at an additional site in the middle of the peptide (amino acids 18-19). Our amylin-bound IDE structure offers insight into how the structural constraint from a disulfide bond in amylin can alter IDE cleavage sites. Together with NMR structures of amylin and the IGF and epidermal growth factor families, our work also reveals the structural basis of how the high dipole moment of substrates complements the charge distribution of the IDE catalytic chamber for the substrate selectivity. In addition, we show how the ability of substrates to properly anchor their N-terminus to the exosite of IDE and undergo a conformational switch upon binding to the catalytic chamber of IDE can also contribute to the selective degradation of structurally related growth factors.
Wesley Farris - One of the best experts on this subject based on the ideXlab platform.
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partial loss of function mutations in insulin degrading Enzyme that induce diabetes also impair degradation of amyloid β protein
American Journal of Pathology, 2004Co-Authors: Wesley Farris, Lars Bertram, Malcolm A Leissring, Stefan Mansourian, Elizabeth A Eckman, Christopher B Eckman, Rudolph E Tanzi, Dennis J SelkoeAbstract:The causes of cerebral accumulation of amyloid β-protein (Aβ) in most cases of Alzheimer's disease (AD) remain unknown. We recently found that homozygous deletion of the Insulin-Degrading Enzyme (IDE) gene in mice results in an early and marked elevation of cerebral Aβ. Both genetic linkage and allelic association in the IDE region of chromosome 10 have been reported in families with late-onset AD. For IDE to remain a valid candidate gene for late-onset AD on functional grounds, it must be shown that partial loss of function of IDE can still alter Aβ degradation, but without causing early, severe elevation of brain Aβ. Here, we show that naturally occurring IDE missense mutations in a well-characterized rat model of type 2 diabetes mellitus (DM2) result in decreased catalytic efficiency and a significant ∼15 to 30% deficit in the degradation of both insulin and Aβ. Endogenously secreted Aβ 40 and Aβ 42 are significantly elevated in primary neuronal cultures from animals with the IDE mutations, but there is no increase in steady-state levels of rodent Aβ in the brain up to age 14 months. We conclude that naturally occurring, partial loss-of-function mutations in IDE sufficient to cause DM2 also impair neuronal regulation of Aβ levels, but the brain can apparently compensate for the partial deficit during the life span of the rat. Our findings have relevance for the emerging genetic evidence suggesting that IDE may be a late-onset AD-risk gene, and for the epidemiological relationships among hyperinsulinemia, DM2, and AD.
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enhanced proteolysis of β amyloid in app transgenic mice prevents plaque formation secondary pathology and premature death
Neuron, 2003Co-Authors: Malcolm A Leissring, Wesley Farris, Alice Y Chang, Dominic M Walsh, Xining Wu, Matthew P Frosch, Dennis J SelkoeAbstract:Converging evidence suggests that the accumulation of cerebral amyloid β-protein (Aβ) in Alzheimer's disease (AD) reflects an imbalance between the production and degradation of this self-aggregating peptide. Upregulation of proteases that degrade Aβ thus represents a novel therapeutic approach to lowering steady-state Aβ levels, but the consequences of sustained upregulation in vivo have not been studied. Here we show that transgenic overexpression of Insulin-Degrading Enzyme (IDE) or neprilysin (NEP) in neurons significantly reduces brain Aβ levels, retards or completely prevents amyloid plaque formation and its associated cytopathology, and rescues the premature lethality present in amyloid precursor protein (APP) transgenic mice. Our findings demonstrate that chronic upregulation of Aβ-degrading proteases represents an efficacious therapeutic approach to combating Alzheimer-type pathology in vivo.
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insulin degrading Enzyme regulates the levels of insulin amyloid β protein and the β amyloid precursor protein intracellular domain in vivo
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Wesley Farris, Dennis J Selkoe, Matthew P Frosch, Stefan Mansourian, Yang Chang, Loren Lindsley, Elizabeth A Eckman, Christopher B Eckman, Rudolph E Tanzi, Suzanne Y GuenetteAbstract:Two substrates of Insulin-Degrading Enzyme (IDE), amyloid beta-protein (Abeta) and insulin, are critically important in the pathogenesis of Alzheimer's disease (AD) and type 2 diabetes mellitus (DM2), respectively. We previously identified IDE as a principal regulator of Abeta levels in neuronal and microglial cells. A small chromosomal region containing a mutant IDE allele has been associated with hyperinsulinemia and glucose intolerance in a rat model of DM2. Human genetic studies have implicated the IDE region of chromosome 10 in both AD and DM2. To establish whether IDE hypofunction decreases Abeta and insulin degradation in vivo and chronically increases their levels, we characterized mice with homozygous deletions of the IDE gene (IDE --). IDE deficiency resulted in a >50% decrease in Abeta degradation in both brain membrane fractions and primary neuronal cultures and a similar deficit in insulin degradation in liver. The IDE -- mice showed increased cerebral accumulation of endogenous Abeta, a hallmark of AD, and had hyperinsulinemia and glucose intolerance, hallmarks of DM2. Moreover, the mice had elevated levels of the intracellular signaling domain of the beta-amyloid precursor protein, which was recently found to be degraded by IDE in vitro. Together with emerging genetic evidence, our in vivo findings suggest that IDE hypofunction may underlie or contribute to some forms of AD and DM2 and provide a mechanism for the recently recognized association among hyperinsulinemia, diabetes, and AD.
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insulin degrading Enzyme regulates the levels of insulin amyloid β protein and the β amyloid precursor protein intracellular domain in vivo
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Wesley Farris, Dennis J Selkoe, Matthew P Frosch, Stefan Mansourian, Yang Chang, Loren Lindsley, Elizabeth A Eckman, Christopher B Eckman, Rudolph E Tanzi, Suzanne Y GuenetteAbstract:Two substrates of Insulin-Degrading Enzyme (IDE), amyloid β-protein (Aβ) and insulin, are critically important in the pathogenesis of Alzheimer's disease (AD) and type 2 diabetes mellitus (DM2), respectively. We previously identified IDE as a principal regulator of Aβ levels in neuronal and microglial cells. A small chromosomal region containing a mutant IDE allele has been associated with hyperinsulinemia and glucose intolerance in a rat model of DM2. Human genetic studies have implicated the IDE region of chromosome 10 in both AD and DM2. To establish whether IDE hypofunction decreases Aβ and insulin degradation in vivo and chronically increases their levels, we characterized mice with homozygous deletions of the IDE gene (IDE −/−). IDE deficiency resulted in a >50% decrease in Aβ degradation in both brain membrane fractions and primary neuronal cultures and a similar deficit in insulin degradation in liver. The IDE −/− mice showed increased cerebral accumulation of endogenous Aβ, a hallmark of AD, and had hyperinsulinemia and glucose intolerance, hallmarks of DM2. Moreover, the mice had elevated levels of the intracellular signaling domain of the β-amyloid precursor protein, which was recently found to be degraded by IDE in vitro. Together with emerging genetic evidence, our in vivo findings suggest that IDE hypofunction may underlie or contribute to some forms of AD and DM2 and provide a mechanism for the recently recognized association among hyperinsulinemia, diabetes, and AD.