Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HIV-1 protease inhibitors have revolutionized the treatment of HIV infection, but their use has been associated with lipodystrophy and insulin resistance. One suggestion for this has been the inhibition of insulin-degrading enzyme (IDE). We have previously demonstrated that insulin, through IDE, can inhibit the proteasome, thus decreasing cytosolic protein degradation. We examined whether the protease inhibitor nelfinavir inhibited IDE and its effect on protein degradation both in vitro and in whole cells. 125I-Insulin degradation was measured by trichloroacetic acid precipitation. Proteasome activities were measured using fluorogenic peptide substrates. Cellular protein degradation was measured by prelabelling cells with 3H-leucine and determining the release of TCA-soluble radioactivity. Nelfinavir inhibited IDE in a concentration-dependent manner with 50% inhibition at the maximal concentration tested, 100 microm. Similarly, the chymotrypsin-like and trypsin-like activities of the proteasome were decreased with an IC50 of approximately 3 microm. The ability of insulin to inhibit the proteasome was abrogated by nelfinavir. Treatment of HepG2 cells with 50 microm nelfinavir decreased 125I-insulin degradation and increased cell-associated radioactivity. Insulin alone maximally decreased protein degradation by 15%. Addition of 50 microm nelfinavir inhibited cellular protein degradation by 14% and blunted the effect of insulin. These data show that nelfinavir inhibits IDE, decreases insulin's ability to inhibit protein degradation via the proteasome and provides another possible mechanism for the insulin resistance seen in protease inhibitor-treated HIV patients.
Diabetes Obes Metab 2006 Nov
PMID:Effect of nelfinavir on insulin metabolism, proteasome activity and protein degradation in HepG2 cells. 1702 90

The existence of links between Alzheimer's disease and diabetes is an important topic currently under active debate. Establishing such links if they exist and defining their common pathogenesis and pathophysiological mechanisms may lead to new concepts and research directions for the pharmacological treatment of Alzheimer's disease and diabetes. Alzheimer's disease is associated with peripheral and central insulin abnormalities. Cognitive capacities are often impaired in patients with diabetes. There are many mechanisms by which insulin-signaling abnormalities may affect clinical and pathological outcome of Alzheimer's disease. Insulin resistance and dysregulation of the degradation of neurotoxic amyloid and insulin appear at the core of the links between Alzheimer's disease and diabetes. Functions and expression of insulysin, an enzyme involved in the degradation of neurotoxic amyloid peptides and insulin, are usually impaired or reduced in Alzheimer's disease and diabetes. The increased occurrence of insulin resistance in Alzheimer's disease suggests that improving insulin effectiveness and insulysin activity may have therapeutic value in Alzheimer's disease patients and therefore is worth intensive investigation.
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PMID:Links between Alzheimer's disease and diabetes. 1689 2

The molecular mechanisms involved in the development of type 2 diabetes are poorly understood. Starting from genome-wide genotype data for 1924 diabetic cases and 2938 population controls generated by the Wellcome Trust Case Control Consortium, we set out to detect replicated diabetes association signals through analysis of 3757 additional cases and 5346 controls and by integration of our findings with equivalent data from other international consortia. We detected diabetes susceptibility loci in and around the genes CDKAL1, CDKN2A/CDKN2B, and IGF2BP2 and confirmed the recently described associations at HHEX/IDE and SLC30A8. Our findings provide insight into the genetic architecture of type 2 diabetes, emphasizing the contribution of multiple variants of modest effect. The regions identified underscore the importance of pathways influencing pancreatic beta cell development and function in the etiology of type 2 diabetes.
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PMID:Replication of genome-wide association signals in UK samples reveals risk loci for type 2 diabetes. 1746 49

C-peptide is a substance that the pancreas releases into the circulation in equimolar amounts to insulin and has demonstrated important physiological effects which relate to the vascular field, in particular the microcirculation. For this analysis, we included 321 full and 36 half sibling pairs affected with type 2 diabetes (T2D) from West Africa. A genome-wide panel of 390 tri-nucleotide and tetra-nucleotide repeats with an average distance of 8.9 cM was performed on a total of 691 persons. Variance components based on multipoint linkage approach as implemented in SOLAR were performed for log C-peptide. Significant linkage evidences were observed on 10q23 at D10S2327 with a LOD score of 4.04 (nominal p-value=0.000008, empirical p-value=0.0004); and on 4p15 at D4S2632 with a LOD score of 3.48 (nominal p-value=0.000031, empirical p-value=0.0013). Other suggestive evidence of linkage were observed on 15q14 at D15S659 with a LOD score 2.41 (nominal p-value=0.000435, empirical p-value=0.0068), and on 18p11 near D18S976 with a LOD score 2.18 (nominal p-value=0.000771 and empirical p-value=0.0094). Interestingly, five positional candidate genes for diabetes and related complications are located in our linkage region (the pituitary adenylate cyclase activating polypeptide (PACAP in 18p11); the peroxisome proliferator-activated receptor gamma coactivator 1 (PPARGC1 in 4p15); PTEN, PPP1R5, and IDE located in 10q23. In conclusion, we identified four major genetic loci (10q23, 4p15, 15q14, and 18p11) influencing C-peptide concentration in West Africans with T2D.
Diabetes Res Clin Pract 2007 Dec
PMID:Genome-wide search for susceptibility genes to type 2 diabetes in West Africans: potential role of C-peptide. 1754 23

Internally quenched fluorogenic substrates are commonly used for measuring enzyme activity in biological samples and allow high sensitivity and continuous real-time measurement that is well suited for high throughput analysis. We describe the development and optimisation of an immunocapture-based assay that uses the fluorogenic peptide substrate (Mca-RPPGFSAFK(Dnp)) and allows the specific measurement of insulin-degrading enzyme (IDE) activity in brain tissue homogenates. This fluorogenic substrate can be cleaved by a number of enzymes including neprilysin (NEP), endothelin-converting enzyme-1 (ECE-1) and angiotensin-converting enzyme (ACE), as well as IDE, and we have previously shown that discrimination between these individual enzymes is not readily achieved in tissue homogenates, even in the presence of selective inhibitors and pH conditions. We tested a panel of IDE antibodies to isolate and capture IDE from brain tissue homogenates and found that immunocapture with antibody to the inactive domain of IDE prior to the addition of fluorogenic substrate allows sensitive (linear at 156-2500ng/ml) and specific measurement of IDE activity and negligible cross-reactivity with NEP, ACE or ECE-1. This assay should allow the measurement of IDE enzyme levels in a variety of biological tissues and may be useful in study of diseases such as Alzheimer's disease and insulin-dependent diabetes.
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PMID:Immunocapture-based fluorometric assay for the measurement of insulin-degrading enzyme activity in brain tissue homogenates. 1822 86

In Alzheimer's disease (AD) Abeta accumulates because of imbalance between the production of Abeta and its removal from the brain. There is increasing evidence that in most sporadic forms of AD, the accumulation of Abeta is partly, if not in some cases solely, because of defects in its removal--mediated through a combination of diffusion along perivascular extracellular matrix, transport across vessel walls into the blood stream and enzymatic degradation. Multiple enzymes within the central nervous system (CNS) are capable of degrading Abeta. Most are produced by neurons or glia, but some are expressed in the cerebral vasculature, where reduced Abeta-degrading activity may contribute to the development of cerebral amyloid angiopathy (CAA). Neprilysin and insulin-degrading enzyme (IDE), which have been most extensively studied, are expressed both neuronally and within the vasculature. The levels of both of these enzymes are reduced in AD although the correlation with enzyme activity is still not entirely clear. Other enzymes shown capable of degrading Abetain vitro or in animal studies include plasmin; endothelin-converting enzymes ECE-1 and -2; matrix metalloproteinases MMP-2, -3 and -9; and angiotensin-converting enzyme (ACE). The levels of plasmin and plasminogen activators (uPA and tPA) and ECE-2 are reported to be reduced in AD. Reductions in neprilysin, IDE and plasmin in AD have been associated with possession of APOEepsilon4. We found no change in the level or activity of MMP-2, -3 or -9 in AD. The level and activity of ACE are increased, the level being directly related to Abeta plaque load. Up-regulation of some Abeta-degrading enzymes may initially compensate for declining activity of others, but as age, genetic factors and diseases such as hypertension and diabetes diminish the effectiveness of other Abeta-clearance pathways, reductions in the activity of particular Abeta-degrading enzymes may become critical, leading to the development of AD and CAA.
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PMID:Abeta-degrading enzymes in Alzheimer's disease. 1836 35

We have evaluated the effect of peripheral insulin deficiency on brain insulin pathway activity in a mouse model of type 1 diabetes, the parallels with Alzheimer's disease (AD), and the effect of treatment with insulin. Nine weeks of insulin-deficient diabetes significantly impaired the learning capacity of mice, significantly reduced insulin-degrading enzyme protein expression, and significantly reduced phosphorylation of the insulin-receptor and AKT. Phosphorylation of glycogen synthase kinase-3 (GSK3) was also significantly decreased, indicating increased GSK3 activity. This evidence of reduced insulin signaling was associated with a concomitant increase in tau phosphorylation and amyloid beta protein levels. Changes in phosphorylation levels of insulin receptor, GSK3, and tau were not observed in the brain of db/db mice, a model of type 2 diabetes, after a similar duration (8 weeks) of diabetes. Treatment with insulin from onset of diabetes partially restored the phosphorylation of insulin receptor and of GSK3, partially reduced the level of phosphorylated tau in the brain, and partially improved learning ability in insulin-deficient diabetic mice. Our data indicate that mice with systemic insulin deficiency display evidence of reduced insulin signaling pathway activity in the brain that is associated with biochemical and behavioral features of AD and that it can be corrected by insulin treatment.
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PMID:Defective insulin signaling pathway and increased glycogen synthase kinase-3 activity in the brain of diabetic mice: parallels with Alzheimer's disease and correction by insulin. 1862 32

Insulin-degrading enzyme (IDE, insulysin, insulinase; EC 3.4.22.11), a thiol metalloendopeptidase, is involved in intracellular degradation of insulin, thereby inhibiting its translocation and accumulation to the nucleus. Recently, protein expression of IDE has been demonstrated in the epithelial ducts of normal breast and breast cancer tissue. Utilizing four different antibodies generated against different epitopes of the IDE molecule, we performed Western blot analysis and immunohistochemical staining on several normal human tissues, on a plethora of tumor cell lines of different tissue origin, and on malignant breast and ovarian tissue. Applying the four IDE-directed antibodies, we demonstrated IDE expression at the protein level, by means of immunoblotting and immunocytochemistry, in each of the tumor cell lines analyzed. Insulin-degrading enzyme protein expression was found in normal tissues of the kidney, liver, lung, brain, breast and skeletal muscle, as well as in breast and ovarian cancer tissues. Immunohistochemical visualization of IDE indicated cytoplasmic localization of IDE in each of the cell lines and tissues assessed. In conclusion, we performed for the first time a wide-ranging survey on IDE protein expression in normal and malignant tissues and cells thus extending our knowledge on the cellular and tissue distribution of IDE, an enzyme which to date has mainly been studied in connection with Alzheimer's disease and diabetes but not in cancer.
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PMID:Expression of metalloprotease insulin-degrading enzyme insulysin in normal and malignant human tissues. 1881 47

Type 2 diabetes recently has been identified as a risk factor for developing Alzheimer's disease (AD). The main reason for this appears to be insulin signaling failure in the brain. Furthermore, cholinergic neurons are particularly affected in the brains of AD patients. The aim of the present study is to investigate if insulin signaling-related proteins are co-located with cholinergic neuron in the CA1 region of hippocampus of mice, which could explain the early loss of cholinergic neurons in AD. Using immunohistochemistry, the insulin signaling-related proteins, such as insulin receptor (InsR), insulin receptor substrate-1 (IRS-1), protein kinase B (PKB, also named Akt), glycogen synthase kinase-3beta (GSK-3beta) and insulin-degrading enzyme (IDE) were analysed. Choline acetyltransferase (ChAT) was selected as a marker of cholinergic neurons. In the CA1 region of hippocampus of mice, several of the insulin signaling-related proteins we had chosen are co-located with ChAT, and most double immunoreactive positive cells were pyramidal cells. The coexistences indicated that the insulin signaling may play an important part in the activities of cholinergic neurons, and the impairment of the pathway may be important in the mechanisms that underlie neurodegeneration in AD.
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PMID:Coexistences of insulin signaling-related proteins and choline acetyltransferase in neurons. 1901 38

TCF7L2, HHEX and IDE on chromosome 10q23-25 reside within the linkage region for type 2 diabetes (T2D). Previous studies including ours have demonstrated that genetic polymorphisms in these three loci are associated with T2D, respectively. But, it is unclear whether TCF7L2, independently or interactively with HHEX and IDE, confer the susceptibility to T2D. In the present study, we first replicated genetic association study of the TCF7L2 gene in a Swedish cohort including 528 non-diabetic healthy controls and 243 T2D patients and then evaluated combining effect from common risk polymorphisms in TCF7L2-HHEX-IDE loci. T2D patients were diagnosed in the intermediate study time. To avoid influence from anti-diabetic treatment, baseline data in all T2D patients were used for analysis. We found that SNPs rs7901695, rs4506565, rs7903146 and rs12255372 in the TCF7L2 gene were strongly associated with T2D (p<0.004). In rs7903146, T2D patients carrying genotypes CT or TT had higher fasting plasma glucose (FPG) levels (p=0.042) and lower HOMA-beta index (p=0.015) and BMI (p=0.015) compared to the patients carrying CC genotype. Furthermore, the risk alleles from TCF7L2 rs7903146 polymorphism either with IDE rs2251101 polymorphism (p=0.0257, OR=1.398) or with HHEX rs1544210 polymorphism (p=0.0024, OR=1.514) were significantly associated with T2D. When risk alleles from three loci were combined, the association with T2D remained significant (p=0.0018, OR=1.506). The present study thus provides evidence that TCF7L2, as the main gene, together with HHEX and IDE loci have combining effects on genetic predisposition to T2D.
Exp Clin Endocrinol Diabetes 2009 Apr
PMID:Loci of TCF7L2, HHEX and IDE on chromosome 10q and the susceptibility of their genetic polymorphisms to type 2 diabetes. 1905 27


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