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Modulation of Insulin Sensitivity by Insulin-Degrading Enzyme. Biomedicines 2021; 9:biomedicines9010086. [PMID: 33477364 PMCID: PMC7830943 DOI: 10.3390/biomedicines9010086] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Insulin-degrading enzyme (IDE) is a highly conserved and ubiquitously expressed metalloprotease that degrades insulin and several other intermediate-size peptides. For many decades, IDE had been assumed to be involved primarily in hepatic insulin clearance, a key process that regulates availability of circulating insulin levels for peripheral tissues. Emerging evidence, however, suggests that IDE has several other important physiological functions relevant to glucose and insulin homeostasis, including the regulation of insulin secretion from pancreatic β-cells. Investigation of mice with tissue-specific genetic deletion of Ide in the liver and pancreatic β-cells (L-IDE-KO and B-IDE-KO mice, respectively) has revealed additional roles for IDE in the regulation of hepatic insulin action and sensitivity. In this review, we discuss current knowledge about IDE’s function as a regulator of insulin secretion and hepatic insulin sensitivity, both evaluating the classical view of IDE as an insulin protease and also exploring evidence for several non-proteolytic functions. Insulin proteostasis and insulin sensitivity have both been highlighted as targets controlling blood sugar levels in type 2 diabetes, so a clearer understanding the physiological functions of IDE in pancreas and liver could led to the development of novel therapeutics for the treatment of this disease.
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Neprilysin Confers Genetic Susceptibility to Alzheimer's Disease in Han Chinese. Mol Neurobiol 2015; 53:4883-92. [PMID: 26362309 DOI: 10.1007/s12035-015-9411-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 08/26/2015] [Indexed: 02/05/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease, with increasing incidence all over the world. Amyloid-β (Aβ) was considered to be the original cause to AD, and many reported pathogenic or risk genes for AD were located in the Aβ generation and degradation pathways. Neprilysin (NEP), insulin-degrading enzyme (IDE), and matrix metalloprotease-9 (MMP-9) are the most important Aβ-degrading proteases. Accumulating genetic evidence suggested that single nucleotide polymorphisms (SNPs) of these genes confer susceptibility to AD in Caucasian populations. In this study, we screened eight SNPs within these three Aβ-degrading protease genes in 1475 individuals of two independent Han Chinese case-control cohorts. SNP rs1816558 of NEP was found to be significantly associated with AD after adjustment for ε4 allele of the apolipoprotein E gene (APOEε4) and the Bonferroni correction. The remaining variants were not associated with risk of AD in Han Chinese sample set. Further data mining revealed that messenger RNA (mRNA) level of NEP substantially increased during the development of AD and was positively correlated with APP expression. The combined results indicated that NEP confers genetic susceptibility to AD in Han Chinese populations.
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Wang S, He F, Wang Y. Association between polymorphisms of the insulin-degrading enzyme gene and late-onset Alzheimer disease. J Geriatr Psychiatry Neurol 2015; 28:94-8. [PMID: 25414272 DOI: 10.1177/0891988714554707] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 06/10/2014] [Indexed: 11/17/2022]
Abstract
The insulin-degrading enzyme (IDE) gene is a strong positional and biological candidate for late-onset Alzheimer disease (LOAD) susceptibility, with recent studies independently demonstrating an association between IDE gene variants and LOAD. However, previous data have been controversial. To investigate the relationship between IDE gene polymorphisms and LOAD risk, a case-control association study of 406 Han Chinese participants in Xinjiang, China, was undertaken. The LOAD and control groups consisted of 202 and 204 participants, respectively. The single-nucleotide polymorphisms rs1887922 and rs1999764 of the IDE gene were linked to LOAD incidence. The presence of the CT+CC genotype of rs1999764 had a protective effect compared to the TT genotype (adjusted P=.0001; odds ratio [OR]=0.226; 95% confidence interval [CI]=0.116-0.441), while the CT+CC genotype of rs1887922 was associated with increased LOAD risk (adjusted P=.0001; OR=3.640; 95% CI=1.889-7.016). Moreover, the effects of rs1887922 and rs1999764 were associated with LOAD risk independent of the apolipoprotein E ∊4 polymorphism and were more significant in men and women, respectively. These results demonstrate that the polymorphisms rs1887922 and rs1999764 of the IDE gene are associated with LOAD susceptibility in the Xinjiang Han population.
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Affiliation(s)
- Shitao Wang
- Department of Cardes Health Care, People's Hospital of Xinjiang Uygur Autonomous Region, Anhui Medical University, Urumqi, China
| | - Feiyan He
- Department of Cardes Health Care, People's Hospital of Xinjiang Uygur Autonomous Region, Anhui Medical University, Urumqi, China
| | - Ying Wang
- Department of Cardes Health Care, People's Hospital of Xinjiang Uygur Autonomous Region, Anhui Medical University, Urumqi, China
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Reduced neuronal expression of insulin-degrading enzyme in the dorsolateral prefrontal cortex of patients with haloperidol-treated, chronic schizophrenia. J Psychiatr Res 2009; 43:1095-105. [PMID: 19394958 DOI: 10.1016/j.jpsychires.2009.03.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 02/20/2009] [Accepted: 03/16/2009] [Indexed: 12/21/2022]
Abstract
Insulin-degrading enzyme (IDE) is a neutral thiol metalloprotease, which cleaves insulin with high specificity. Additionally, IDE hydrolyzes Abeta, glucagon, IGF I and II, and beta-endorphin. We studied the expression of IDE protein in postmortem brains of patients with schizophrenia and controls because: (1) the gene encoding IDE is located on chromosome 10q23-q25, a gene locus linked to schizophrenia; (2) insulin resistance with brain insulin receptor deficits/receptor dysfunction was reported in schizophrenia; (3) the enzyme cleaves IGF-I and IGF-II which are implicated in the pathophysiology of the disease; and (4) brain gamma-endorphin levels, liberated from beta-endorphin exclusively by IDE, have been reported to be altered in schizophrenia. We counted the number of IDE immunoreactive neurons in the dorsolateral prefrontal cortex, the hypothalamic paraventricular and supraoptic nuclei, and the basal nucleus of Meynert of 14 patients with schizophrenia and 14 matched control cases. Patients had long-term haloperidol treatment. In addition, relative concentrations of IDE protein in the dorsolateral prefrontal cortex were estimated by Western blot analysis. There was a significantly reduced number of IDE expressing neurons and IDE protein content in the left and right dorsolateral prefrontal cortex in schizophrenia compared with controls, but not in other brain areas investigated. Results of our studies on the influence of haloperidol on IDE mRNA expression in SHSY5Y neuroblastoma cells, as well as the effect of long-term treatment with haloperidol on the number of IDE immunoreactive neurons in rat brain, indicate that haloperidol per se, is not responsible for the decreased neuronal expression of the enzyme in schizophrenics. Haloperidol however, might exert some effect on IDE, through changes of the expression levels of its substrates IGF-I and II, insulin and beta-endorphin. Reduced cortical IDE expression might be part of the disturbed insulin signaling cascades found in schizophrenia. Furthermore, it might contribute to the altered metabolism of certain neuropeptides (IGF-I and IGF-II, beta-endorphin), in schizophrenia.
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Pivovarova O, Gögebakan O, Pfeiffer AFH, Rudovich N. Glucose inhibits the insulin-induced activation of the insulin-degrading enzyme in HepG2 cells. Diabetologia 2009; 52:1656-64. [PMID: 19396426 DOI: 10.1007/s00125-009-1350-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 03/06/2009] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS Hepatic insulin degradation decreases in type 2 diabetes. Insulin-degrading enzyme (IDE) plays a key role in insulin degradation and its gene is located in a diabetes-associated chromosomal region. We hypothesised that IDE may be regulated by insulin and/or glucose in a liver cell model. To validate the observed regulation of IDE in vivo, we analysed biopsies of human adipose tissue during different clamp experiments in men. METHODS Human hepatoma HepG2 cells were incubated in normal (1 g/l) or high (4.5 g/l) glucose medium and treated with insulin for 24 h. Catalytic activity, mRNA and protein levels of IDE were assessed. IDE mRNA levels were measured in biopsies of human subcutaneous adipose tissue before and at 240 min of hyperinsulinaemic, euglycaemic and hyperglycaemic clamps. RESULTS In HepG2 cells, insulin increased IDE activity under normal glucose conditions with no change in IDE mRNA or protein levels. Under conditions of high glucose, insulin increased mRNA levels of IDE without changes in IDE activity. Both in normal and high glucose medium, insulin increased levels of the catalytically more active 15a IDE isoform compared with the 15b isoform. In subcutaneous adipose tissue, IDE mRNA levels were not significantly upregulated after euglycaemic or hyperglycaemic clamps. CONCLUSIONS/INTERPRETATION Insulin increases IDE activity in HepG2 cells in normal but not in high glucose conditions. This disturbance cannot be explained by corresponding alterations in IDE protein levels or IDE splicing. The loss of insulin-induced regulation of IDE activity under hyperglycaemia may contribute to the reduced insulin extraction and peripheral hyperinsulinaemia in type 2 diabetes.
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Affiliation(s)
- O Pivovarova
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke, 14558 Nuthetal, Germany.
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Zuo X, Jia J. Promoter polymorphisms which modulate insulin degrading enzyme expression may increase susceptibility to Alzheimer's disease. Brain Res 2009; 1249:1-8. [DOI: 10.1016/j.brainres.2008.10.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 10/01/2008] [Accepted: 10/10/2008] [Indexed: 10/21/2022]
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Qin W, Jia J. Down-regulation of insulin-degrading enzyme by presenilin 1 V97L mutant potentially underlies increased levels of amyloid beta 42. Eur J Neurosci 2008; 27:2425-32. [DOI: 10.1111/j.1460-9568.2008.06207.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Bernstein HG, Lendeckel U, Bukowska A, Ansorge S, Ernst T, Stauch R, Trübner K, Steiner J, Dobrowolny H, Bogerts B. Regional and cellular distribution patterns of insulin-degrading enzyme in the adult human brain and pituitary. J Chem Neuroanat 2007; 35:216-24. [PMID: 18226493 DOI: 10.1016/j.jchemneu.2007.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 12/04/2007] [Accepted: 12/04/2007] [Indexed: 11/17/2022]
Abstract
The regional distribution and cellular localization of insulin-degrading enzyme (IDE) was studied in adult human brain and pituitary by means of immunhistochemistry. We show that the enzyme is widely but unevenly distributed in human brain, with hypothalamic neurons showing the strongest immunoreaction. Strong to moderate immunostaining for the enzyme was observed in multiple cortical areas, hippocampus, cerebellum, and brain stem. Cellularly, IDE was mainly confined to neurons, but it was also present in oligodendrocytes, choroid plexus, and some blood vessel endothelial cells. A strong immunoreaction was seen in a subset of adenohypophysial cells. Some immunolabeling was also present in the neurohypophysis. The putative importance of the distribution of the enzyme in brain and pituitary is discussed in relation to its main known substrates, insulin, Abeta, and beta-endorphin.
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Affiliation(s)
- Hans-Gert Bernstein
- HansDepartment of Psychiatry, University of Magdeburg, Leipziger Str. 44, D-39120 Magdeburg, Germany.
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Im H, Manolopoulou M, Malito E, Shen Y, Zhao J, Neant-Fery M, Sun CY, Meredith SC, Sisodia SS, Leissring MA, Tang WJ. Structure of substrate-free human insulin-degrading enzyme (IDE) and biophysical analysis of ATP-induced conformational switch of IDE. J Biol Chem 2007; 282:25453-63. [PMID: 17613531 DOI: 10.1074/jbc.m701590200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Insulin-degrading enzyme (IDE) is a zinc metalloprotease that hydrolyzes amyloid-beta (Abeta) and insulin, which are peptides associated with Alzheimer disease (AD) and diabetes, respectively. Our previous structural analysis of substrate-bound human 113-kDa IDE reveals that the N- and C-terminal domains of IDE, IDE-N and IDE-C, make substantial contact to form an enclosed catalytic chamber to entrap its substrates. Furthermore, IDE undergoes a switch between the closed and open conformations for catalysis. Here we report a substrate-free IDE structure in its closed conformation, revealing the molecular details of the active conformation of the catalytic site of IDE and new insights as to how the closed conformation of IDE may be kept in its resting, inactive conformation. We also show that Abeta is degraded more efficiently by IDE carrying destabilizing mutations at the interface of IDE-N and IDE-C (D426C and K899C), resulting in an increase in Vmax with only minimal changes to Km. Because ATP is known to activate the ability of IDE to degrade short peptides, we investigated the interaction between ATP and activating mutations. We found that these mutations rendered IDE less sensitive to ATP activation, suggesting that ATP might facilitate the transition from the closed state to the open conformation. Consistent with this notion, we found that ATP induced an increase in hydrodynamic radius, a shift in electrophoretic mobility, and changes in secondary structure. Together, our results highlight the importance of the closed conformation for regulating the activity of IDE and provide new molecular details that will facilitate the development of activators and inhibitors of IDE.
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Affiliation(s)
- Hookang Im
- Ben-May Department for Cancer Research, the University of Chicago, Chicago, Illinois 60637, USA
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Kim M, Hersh LB, Leissring MA, Ingelsson M, Matsui T, Farris W, Lu A, Hyman BT, Selkoe DJ, Bertram L, Tanzi RE. Decreased Catalytic Activity of the Insulin-degrading Enzyme in Chromosome 10-Linked Alzheimer Disease Families. J Biol Chem 2007; 282:7825-32. [PMID: 17244626 DOI: 10.1074/jbc.m609168200] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-degrading enzyme (IDE) is a zinc metalloprotease that degrades the amyloid beta-peptide, the key component of Alzheimer disease (AD)-associated senile plaques. We have previously reported evidence for genetic linkage and association of AD on chromosome 10q23-24 in the region harboring the IDE gene. Here we have presented the first functional assessment of IDE in AD families showing the strongest evidence of the genetic linkage. We have examined the catalytic activity and expression of IDE in lymphoblast samples from 12 affected and unaffected members of three chromosome 10-linked AD pedigrees in the National Institute of Mental Health AD Genetics Initiative family sample. We have shown that the catalytic activity of cytosolic IDE to degrade insulin is reduced in affected versus unaffected subjects of these families. Further, we have shown the decrease in activity is not due to reduced IDE expression, suggesting the possible defects in IDE function in these AD families. In attempts to find potential mutations in the IDE gene in these families, we have found no coding region substitutions or alterations in splicing of the canonical exons and exon 15b of IDE. We have also found that total IDE mRNA levels are not significantly different in sporadic AD versus age-matched control brains. Collectively, our data suggest that the genetic linkage of AD in this set of chromosome 10-linked AD families may be the result of systemic defects in IDE activity in the absence of altered IDE expression, further supporting a role for IDE in AD pathogenesis.
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Affiliation(s)
- Minji Kim
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Charlestown, Massachusetts 02129, and Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington 40536, USA
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Morelli L, Llovera RE, Mathov I, Lue LF, Frangione B, Ghiso J, Castaño EM. Insulin-degrading Enzyme in Brain Microvessels. J Biol Chem 2004; 279:56004-13. [PMID: 15489232 DOI: 10.1074/jbc.m407283200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The accumulation of amyloid beta (Abeta) in the walls of small vessels in the cerebral cortex is associated with diseases characterized by dementia or stroke. These include Alzheimer's disease, Down syndrome, and sporadic and hereditary cerebral amyloid angiopathies (CAAs) related to mutations within the Abeta sequence. A higher tendency of Abeta to aggregate, a defective clearance to the systemic circulation, and insufficient proteolytic removal have been proposed as mechanisms that lead to Abeta accumulation in the brain. By using immunoprecipitation and mass spectrometry, we show that insulin-degrading enzyme (IDE) from isolated human brain microvessels was capable of degrading (125)I-insulin and cleaved Abeta-(1-40) wild type and the genetic variants Abeta A21G (Flemish), Abeta E22Q (Dutch), and Abeta E22K (Italian) at the predicted sites. In microvessels from Alzheimer's disease cases with CAA, IDE protein levels showed a 44% increase as determined by sandwich enzyme-linked immunosorbent assay and Western blot. However, the activity of IDE upon radiolabeled insulin was significantly reduced in CAA as compared with age-matched controls. These results support the notion that a defect in Abeta proteolysis by IDE contributes to the accumulation of this peptide in the cortical microvasculature. Moreover they raise the possibility that IDE inhibition or inactivation is a pathogenic mechanism that may open novel strategies for the treatment of cerebrovascular Abeta amyloidoses.
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Affiliation(s)
- Laura Morelli
- IQUIFIB/Consejo Nacional de Investigaciones Científicas y Técnicas, Cátedra de Química Biológica Patológica, Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956, C1113AAD, Buenos Aires, Argentina
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Abstract
Insulin-degrading enzyme (IDE) is a metalloprotease implicated in insulin degradation and suggested to have a variety of additional functions, including the clearance of amyloid beta peptides of Alzheimer's disease. Little is known about endogenous proteins that may interact with and modulate IDE's activity in the cell. We purified and characterized two proteins from mouse leukemic splenocytes that interact with IDE and inhibit its insulin-degrading activity. A protein of 14 kDa was similar to a competitive IDE inhibitor reported previously. The major inhibitor was identified by amino acid sequencing as ubiquitin, a protein that is post-translationally covalently attached to other intracellular proteins and regulates diverse cellular processes. Ubiquitin inhibited insulin-degrading activity of IDE and diminished crosslinking of 125I-insulin to IDE in a specific, concentration-dependent, reversible, and ATP-independent manner. Ubiquitin did not affect the crosslinking of 125I-insulin to insulin receptors or of 125I-atrial natriuretic peptide (ANP) to its receptor guanylate cyclase-A. These findings suggest a novel role for ubiquitin or perhaps proteins with ubiquitin-like domains in regulating the function of IDE.
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Affiliation(s)
- Tomo Saric
- Division of Molecular Medicine, Rudjer Boskovic Institute, Bijenicka 54, P.O. Box 180, 10002 Zagreb, Croatia.
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Chesneau V, Rosner MR. Functional human insulin-degrading enzyme can be expressed in bacteria. Protein Expr Purif 2000; 19:91-8. [PMID: 10833395 DOI: 10.1006/prep.2000.1217] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin-degrading enzyme (IDE) has been shown to degrade a number of biologically important peptides, including insulin and the amyloid-beta protein implicated in Alzheimer's disease. However, lack of a facile method to generate purified enzyme and related mutants has made it difficult to study the precise role of IDE in the clearance of these peptides. Therefore, we determined whether recombinant wild-type and mutant human IDEs can be overexpressed as functional enzymes in bacteria. Three vectors carrying cDNAs encoding N-terminally polyhistidine-tagged recombinant IDEs were constructed, and the proteins expressed in Escherichia coli were purified by metal affinity chromatography (final yield approximately 8 mg per liter of culture). The recombinant IDEs, like the endogenous mammalian enzyme, migrate with 110-kDa apparent molecular masses in SDS-polyacrylamide gels and as a approximately 200-kDa species in gel filtration. Further analysis by native PAGE indicates that IDE can form multimers of different complexities. The wild-type recombinant endopeptidase degrades insulin with an efficiency similar to that of the enzyme purified from mammalian tissues. Purified IDEs are stable at 4 degrees C for at least 1 month. Purified recombinant protein was used to raise specific polyclonal antibodies that can immunoprecipitate native mammalian IDE. Thus, the procedure described allows the rapid production of large amounts of purified IDE and demonstrates that IDE can be produced in an active form in the absence of other potential interacting mammalian proteins.
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Affiliation(s)
- V Chesneau
- Ben May Institute for Cancer Research, University of Chicago, Illinois 60637, USA
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Abstract
Insulin (Ins) and various other hormones and growth factors have been shown to be rapidly internalized and translocated to the cell nucleus. This review summarizes the mechanisms that are involved in the translocation of Ins to the nucleus, and discusses its possible role in Ins action, based on observations by the authors and others. Ins is internalized to endosomes by both receptor-mediated and fluid-phase endocytosis, the latter occurring only at high Ins concentrations. The authors recently demonstrated the caveolae are the primary cell membrane locations responsible for initiating the signal transduction cascade induced by Ins. Once Ins is internalized, Ins dissociates from the Ins receptor in the endosome, and is translocated to the cytoplasm, where most Ins is degraded by Ins-degrading enzyme (IDE), although how the polypeptides cross the lipid bilayer is unknown. Some Ins escapes the degradation and binds to cytosolic Ins-binding proteins (CIBPs), in addition to IDE. IDE and some CIBPs are known to be binding proteins for other hormones or their receptors, and are involved in gene regulation, suggesting physiological relevance of CIBPs in the signaling of Ins and other hormones. Ins is eventually translocated through the nuclear pore to the nucleus, where Ins tightly associates with nuclear matrix. The role of Ins internalization and translocation to the nucleus is still controversial, although there is substantial evidence to support its role in cellular responses caused by Ins. Many studies indicate that nuclear translocation of various growth factors and hormones plays an important role in cell proliferation or DNA synthesis. It would be reasonable to suggest that Ins internalization, its association with CIBPs, and its translocation to the nucleus may be essential for the regulation of nuclear events by Ins.
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Affiliation(s)
- S Harada
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
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Abstract
Insulin degradation is a regulated process that plays a role in controlling insulin action by removing and inactivating the hormone. Abnormalities in insulin clearance and degradation are present in various pathological conditions including type 2 diabetes and obesity and may be important in producing clinical problems. The uptake, processing, and degradation of insulin by cells is a complex process with multiple intracellular pathways. Most evidence supports IDE as the primary degradative mechanism, but other systems (PDI, lysosomes, and other enzymes) undoubtedly contribute to insulin metabolism. Recent studies support a multifunctional role for IDE, as an intracellular binding, regulatory, and degradative protein. IDE increases proteasome and steroid hormone receptor activity, and this activation is reversed by insulin. This raises the possibility of a direct intracellular interaction of insulin with IDE that could modulate protein and fat metabolism. The recent findings would place intracellular insulin-IDE interaction into the insulin signal transduction pathway for mediating the intermediate effects of insulin on fat and protein turnover.
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Affiliation(s)
- W C Duckworth
- Veterans Affairs Medical Center, Omaha, Nebraska 68105, USA
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Chevenne D, Letailleur A, Trivin F, Porquet D. Effect of Hemolysis on the Concentration of Insulin in Serum Determined by RIA and IRMA. Clin Chem 1998. [DOI: 10.1093/clinchem/44.2.354] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Didier Chevenne
- Hôp. Robert Debré, Lab. de Biochim.-Hormonol., 48 blvd. Sérurier, 75019-Paris, France; Hôp. Saint-Joseph, Lab. de Biochim., 185 rue Raymond Losserand, 75674-Paris Cédex 14, France
- Hôp. Robert Debré, Lab. de Biochim.-Hormonol., 48 blvd. Sérurier, 75019-Paris, France; Hôp. Saint-Joseph, Lab. de Biochim., 185 rue Raymond Losserand, 75674-Paris Cédex 14, France
| | - Annick Letailleur
- Hôp. Robert Debré, Lab. de Biochim.-Hormonol., 48 blvd. Sérurier, 75019-Paris, France; Hôp. Saint-Joseph, Lab. de Biochim., 185 rue Raymond Losserand, 75674-Paris Cédex 14, France
| | - François Trivin
- Hôp. Robert Debré, Lab. de Biochim.-Hormonol., 48 blvd. Sérurier, 75019-Paris, France; Hôp. Saint-Joseph, Lab. de Biochim., 185 rue Raymond Losserand, 75674-Paris Cédex 14, France
| | - Dominique Porquet
- Hôp. Robert Debré, Lab. de Biochim.-Hormonol., 48 blvd. Sérurier, 75019-Paris, France; Hôp. Saint-Joseph, Lab. de Biochim., 185 rue Raymond Losserand, 75674-Paris Cédex 14, France
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Kurochkin IV, Goto S. Alzheimer's beta-amyloid peptide specifically interacts with and is degraded by insulin degrading enzyme. FEBS Lett 1994; 345:33-7. [PMID: 8194595 DOI: 10.1016/0014-5793(94)00387-4] [Citation(s) in RCA: 297] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cerebral deposition of beta-amyloid peptide (beta A) is a hallmark of Alzheimer's disease. Concentration of beta A could play a critical role in the rate of amyloid deposition. It is therefore of considerable importance to identify proteases involved in processing of beta A. 125I-labeled synthetic beta A specifically cross-linked to a single protein with M(r) = 110,000 in cytosol fractions from rat brain and liver. This protein was identified as insulin degrading enzyme (IDE) since the labeling of the 110 kDa protein was completely blocked by an excess of insulin, and anti-IDE monoclonal antibodies precipitated the labeled protein. Purified rat IDE effectively degraded beta A.
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Affiliation(s)
- I V Kurochkin
- Department of Biochemistry, School of Pharmaceutical Sciences, Toho University, Chiba, Japan
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Harada S, Smith RM, Jarett L. 1,10-Phenanthroline increases nuclear accumulation of insulin in response to inhibiting insulin degradation but has a biphasic effect on insulin's ability to increase mRNA levels. DNA Cell Biol 1994; 13:487-93. [PMID: 8024692 DOI: 10.1089/dna.1994.13.487] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previous reports demonstrated that insulin is translocated through the cytoplasm to the nucleus of H35 hepatoma cells and suggested that nuclear insulin may be involved in stimulating transcription of immediate-early genes. In a recent study, inhibition of insulin-degrading enzyme with 1,10-phenanthroline, a Zn2+ chelator, caused a significant increase in the nuclear accumulation of insulin. The present study characterized the effects of 1,10-phenanthroline and its nonchelating isomer, 1,7-phenanthroline, on insulin degradation, nuclear accumulation, and stimulation of immediate-early gene expression. 1,10- but not 1,7-phenanthroline inhibited insulin degradation and increased nuclear accumulation of insulin in a dose-dependent manner. 1,7-phenanthroline caused a dose-dependent decrease in the expression of insulin-stimulated immediate-early genes, but had no significant effect on alpha-tubulin mRNA levels. In the presence of insulin, Northern analysis revealed that 1,10-phenanthroline at all concentrations tested increased alpha-tubulin mRNA levels, but had a biphasic effect on insulin-stimulated immediate-early gene expression. At low concentrations (5-200 microM), 1,10-phenanthroline increased the expression of insulin-stimulated g33, c-fos, and Egr-1 mRNA. At concentrations greater than 1 mM, insulin-stimulated immediate-early gene expression was decreased similar to the effect seen with 1,7-phenanthroline. Nuclear run-on analysis demonstrated that high concentrations of 1,10-phenanthroline decreased insulin-stimulated immediate-early gene transcription but had no effect on transcription of alpha-tubulin. However, low concentrations of 1,10-phenanthroline did not increase transcription of any genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Harada
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104
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Abstract
AtT-20 cells are known to synthesize two molecular weight forms of the prohormone converting enzyme PC1 with molecular masses of 87 and 66 kDa. In this study we have analyzed basal and stimulated secretion of these proteins. Western blot results show that basal secretion medium of cultured AtT-20 cells contained low concentrations of both the 87 and 66 kDa forms of PC1 with the former protein predominant. During the stimulation period with CRF, cAMP and cAMP + BaCl2, increased release of both proteins was observed, but the 66 kDa protein predominated. Secretion medium obtained from stimulated and unstimulated cells was enzymatically active against the Cbz-Arg-Ser-Lys-Arg-AMC fluorogenic substrate as well as against 35S-proenkephalin. This activity was Ca+2 dependent and was inhibited by the chelating agent EDTA. The activity was insensitive to acid and thiol proteinase inhibitors as well as to N-alpha-p-tosyl-L-Lys-chloromethyl ketone; it was slightly sensitive to phenylmethyl sulfonyl fluoride and was strongly inhibited by D-Tyr-Ala-Lys-Arg-chloromethyl ketone. This inhibitor profile exhibits strong similarities to furin and kexin. After partial purification of medium by gel filtration chromatography, a portion of the enzymatic activity and immunoreactivity for both 87 kDa and 66 kDa proteins eluted with an apparent molecular weight of 400 kDa (suggesting aggregation); however the highest activity appeared in the elution position of the 66 kDa monomer. When the 87 kDa protein was removed from the medium by means of an affinity column containing an antibody against the carboxyl terminal portion of PC1, the column flow-through, which included the 66 kDa protein, still remained enzymatically active. These data support the notion that the 66 kDa protein, which is the most concentrated PC1 product stored in AtT-20 cells and is released during stimulation, is enzymatically active.
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Affiliation(s)
- O Vindrola
- Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans 70112
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22
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Gehm B, Kuo W, Perlman R, Rosner M. Mutations in a zinc-binding domain of human insulin-degrading enzyme eliminate catalytic activity but not insulin binding. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53049-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Baumeister H, Müller D, Rehbein M, Richter D. The rat insulin-degrading enzyme. Molecular cloning and characterization of tissue-specific transcripts. FEBS Lett 1993; 317:250-4. [PMID: 8425612 DOI: 10.1016/0014-5793(93)81286-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The primary structure of the rat insulin-degrading enzyme (IDE) was determined by cDNA analysis. Rat IDE, as well as the previously characterized homologs from human and Drosophila, contain the carboxyl-terminal consensus sequence A/S-K-L, for peroxisome targeting. A stretch of 43 bp surrounding an alternatively used polyadenylation site is highly conserved between rat and human, suggesting that it may contain important regulatory information. Northern blot analysis revealed two IDE transcripts of 3.7 and 5.5 kb in various tissues. Testis was found to be exceptional in having three different RNAs (3.7, 4.1 and 6.1 kb) at a relatively high abundance. The expression of the IDE gene in testis is correlated with sexual maturation.
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Affiliation(s)
- H Baumeister
- Institut für Zellbiochemie und klinische Neurobiologie, UKE, Universität Hamburg, Germany
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