Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The protein islet amyloid polypeptide (IAPP) is a glucose metabolism associated hormone cosecreted with insulin by the beta-cells of the pancreas. In humans with type 2 diabetes, IAPP deposits as amyloid fibers. The assembly intermediates of this process are associated with beta-cell death. Here, we examine the rat IAPP sequence variant under physiological solution conditions. Rat IAPP is mechanistically informative for fibrillogenesis, as it samples intermediate-like states but does not progress to form amyloid. A central challenge was the development of a bacterial expression system to generate isotopically labeled IAPP without terminal tags, but which does include a eukaryotic post-translational modification. While optical spectroscopy shows IAPP to be natively unfolded, NMR chemical shifts of backbone and beta-carbon resonances reveal the sampling of alpha-helical states across a continuous stretch comprising approximately 40% of the protein. In addition, the manifestation of nonrandom coil chemical shifts is confirmed by the relative insensitivity of the amide proton chemical shifts to alterations in temperature. Intriguingly, the residues displaying helical propensity are conserved with the human sequence, suggesting a functional role for this conformational bias. The inability of rat IAPP to self assemble can be ascribed, in part, to several slowly exchanging conformations evident as multiple chemical shift assignments in the immediate vicinity of three proline residues residing outside of this helical region.
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PMID:Direct detection of transient alpha-helical states in islet amyloid polypeptide. 1712 62

Exploiting the incretin effect to develop new glucose-lowering treatments has become the focus of intense research. One successful approach has been the development of oral inhibitors of dipeptidyl peptidase-IV (DPP-IV). These drugs reversibly block DPP-IV-mediated inactivation of incretin hormones, for example, glucagon-like peptide 1 (GLP-1) and also other peptides that have alanine or proline as the penultimate N-terminal amino acid. DPP-IV inhibitors, therefore, increase circulating levels and prolong the biological activity of endogenous GLP-1, but whether this is sufficient to fully explain the substantial reduction in haemoglobin A(1c) (HbA(1c)) and associated metabolic profile remains open to further investigation. DPP-IV inhibitors such as vildagliptin and sitagliptin have been shown to be highly effective antihyperglycaemic agents that augment insulin secretion and reduce glucagon secretion via glucose-dependent mechanisms. This review summarizes the major clinical trials with DPP-IV inhibitors as monotherapy and as add-on therapy in patients with type 2 diabetes. The magnitude of HbA(1c) reduction with DPP-IV inhibitors depends upon the pretreatment HbA(1c) values, but there seems to be no change in body weight, and very low rates of hypoglycaemia and gastrointestinal disturbance with these agents. DPP-IV inhibitors represent a major new class of oral antidiabetic drug and their metabolic profile offers a number of unique clinical advantages for the management of type 2 diabetes.
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PMID:Dipeptidyl peptidase-IV inhibitors: a major new class of oral antidiabetic drug. 1730 May 91

The emergence of glucagon-like peptide 1 (GLP-1) as a well validated approach to the treatment of type 2 diabetes and preclinical validation of dipeptidyl peptidase IV (DPP-4) inhibition as an alternate, oral approach to GLP-1 therapy prompted the initiation of a DPP-4 inhibitor program at Merck in 1999. DPP-4 inhibitors threo- and allo-isoleucyl thiazolidide were in-licensed to jump start the program; however, development was discontinued due to profound toxicity in rat and dog safety studies. The observation that both compounds inhibit the related proline peptidases DPP8 and DPP9 led to the hypothesis that inhibition of DPP8 and/or DPP9 could evoke severe toxicities in preclinical species. Indeed, the observed toxicities were recapitulated with a selective dual DPP8/9 inhibitor but not with an inhibitor selective for DPP-4. Thus, medicinal chemistry efforts focused on identifying a highly selective DPP-4 inibitor for clinical development. Initial work in an alpha-amino acid series related to isoleucyl thiazolidide was discontinued due to lack of selectivity; however, SAR studies on two screening leads led to the identification of a highly selective beta-amino acid piperazine series. In an effort to stabilize the piperazine moiety, which was extensively metabolized in vivo, a series of bicyclic derivatives were prepared, culminating in the identification of a potent and selective triazolopiperazine series. Unlike their monocyclic counterparts, these analogs typically showed excellent pharmacokinetic properties in preclinical species. Optimization of this series led to the discovery of JANUVIA (sitagliptin), a highly selective DPP-4 inhibitor for the treatment of type 2 diabetes.
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PMID:Discovery of JANUVIA (Sitagliptin), a selective dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes. 1735 77

Dipeptidyl peptidase IV (DPP IV) is a validated target for the treatment of type 2 diabetes, with several inhibitors currently in phase 3 clinical trials. This review will mainly focus on proline-specific dipeptidyl peptidases related to DPP IV: fibroblast activation protein (FAP), dipeptidyl peptidase 8 (DPP8), dipeptidyl peptidase 9 (DPP9) and dipeptidyl peptidase II (DPP II). The biochemical and biological properties of these enzymes will be discussed, as well as the therapeutic potential of their inhibition. The development of potent and selective inhibitors for each of these peptidases will be described.
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PMID:Prolyl peptidases related to dipeptidyl peptidase IV: potential of specific inhibitors in drug discovery. 1735 82

Neuropeptide Y (NPY) is a sympathetic neurotransmitter that plays a role in e.g. circulation, hormone release and angiogenesis. Earlier studies have shown that the Leucine 7 to Proline 7 (Leu7Pro) polymorphism of preproNPY is associated with increased risk for vascular complications in type 2 diabetes. The mechanism for this maybe altered transmitter and hormone levels or altered cardiovascular functions, which have been observed in healthy subjects having the Leu7Pro polymorphism. The current study was undertaken to explore if the Leu7Pro polymorphism has an impact on these functions in subjects with type 2 diabetes. Diurnal measurements were performed for Finnish Caucasian type 2 diabetes patients of two preproNPY genotypes (matched by sex, age, BMI, duration of diabetes and HbA1c) in resting position to prevent sympathetic stimulation. Standard meals were offered during the 24-hour study period. Nine subjects with the Leu7Pro polymorphism and ten subjects without this polymorphism were studied. Plasma concentrations of NPY, glucose, insulin, cortisol, prolactin and leptin were measured by taking blood samples at 20 time points (from 8 a.m. to 8 a.m.). Heart rate and blood pressure were measured at the same time points. The results show that NPY concentrations were similar in both preproNPY genotypes. Glucose, insulin, cortisol and leptin concentrations as well as heart rate and blood pressure were also similar. However, a significant difference between genotypes was found in the association of NPY concentrations with cortisol concentrations (p for difference=0.002). Also a statistically significant negative association of plasma NPY levels with plasma glucose levels was found in both genotypes. Since no impact of preproNPY genotype on mean NPY or hormone levels were detected in subjects with type 2 diabetes, the mechanisms for the increased risk for diabetic complications in the subjects with the Leu7Pro polymorphism need to be further explored.
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PMID:Impact of the Leu7Pro polymorphism of preproNPY on diurnal NPY and hormone secretion in type 2 diabetes. 1751 89

Peroxisome proliferators-activated receptor gamma (PPAR gamma) is a nuclear hormone receptor that serves as a master regulator for adipocytes-specific genes contributing to adipocytes differentiation, insulin sensitivity and lipid metabolism. The substitution of proline to alanine at codon 12 of the PPAR gamma 2 gene (Pro12Ala polymorphism) is most widely studied, and the associations with diabetes, obesity, and other clinical parameters have been reported and discussed in several ethnic groups. Among native Qatar ethnicity, however, there is no report about this polymorphism. The aim of this study was to estimate the allele frequency of the Pro12Ala polymorphism of PPAR gamma 2 gene among Qatari population and investigate the association between this polymorphism and obesity or type 2 diabetes. This is a matched case-control study. It was carried out among diabetic patients and healthy subjects at the Primary Healthcare Clinics, and the survey was conducted from February 2003 to March 2006 in Qatari male and female nationals aged 35 to 60 years. The study was based on matched age, sex, and ethnicity of 400 cases (with diabetes) and 450 controls (without diabetes). Face-to-face interviews were based on a questionnaire that included variables such as age, sex, sociodemographic status, body mass index (BMI), and obesity. Their health status was assessed by medical conditions, family history, and blood pressure measurements. The allele frequency of Pro12Ala polymorphism in PPAR gamma 2 gene among Qataris is lower than that in many Caucasian ethnic groups. No association is seen between the Pro12Ala and type 2 Diabetes (0.055 vs 0.059, OR = 1.1311, P = 0.669). Nearly half of the diabetic type 2 patients (48.5%) were obese (BMI > 30) compared to nondiabetic subjects (29.8%) (P < 0.001). In this study, no association is seen between the Pro12Ala polymorphism in PPAR gamma 2 gene and the type 2 diabetes in Qatar.
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PMID:Lack of association between the Pro12Ala polymorphism of the PPAR-gamma 2 gene and type 2 diabetes mellitus in the Qatari consanguineous population. 1780 73

Diabetes mellitus, commonly referred to as diabetes, is a medical condition associated with abnormally high levels of glucose (or sugar) in the blood. Keeping this view, we demonstrate the phylogenetic motifs (PMs) identification in type 2 diabetes mellitus very likely corresponding to protein functional sites. In this article, we have identified PMs for all the candidate genes for type 2 diabetes mellitus. Glycine 310 remains conserved for glucokinase and potassium channel KCNJ11. Isoleucine 137 was conserved for insulin receptor and regulatory subunit of a phosphorylating enzyme. Whereas residues valine, leucine, methionine were highly conserved for insulin receptor. Occurrence of proline was very high for calpain 10 gene and glucose transporter.
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PMID:Type 2 diabetes mellitus: phylogenetic motifs for predicting protein functional sites. 1791 41

Deficient repair activity for 8-hydroxy-2'-deoxyguanine (8-oxoguanine), a premutagenic oxidative DNA damage, has been observed in affected tissues in neurodegenerative diseases of aging, such as Alzheimer's disease, and in ischemia/reperfusion injury, type 2 diabetes mellitus, and cancer. These conditions have in common the accumulation of oxidative DNA damage, which is believed to play a role in disease progression, and loss of intracellular calcium regulation. These observations suggest that oxidative DNA damage repair capacity may be influenced by fluctuations in cellular calcium. We have identified human 8-oxoguanine-DNA glycosylase 1 (OGG1), the major 8-oxoguanine repair activity, as a specific target of the Ca(2+)-dependent protease Calpain I. Protein sequencing of a truncated partially calpain-digested OGG1 revealed that calpain recognizes OGG1 for degradation at a putative PEST (proline, glutamic acid, serine, threonine) sequence in the C-terminus of the enzyme. Co-immunoprecipitation experiments showed that OGG1 and Calpain I are associated in human cells. Exposure of HeLa cells to hydrogen peroxide or cisplatin resulted in the degradation of OGG1. Pretreatment of cells with the calpain inhibitor calpeptin resulted in inhibition of OGG1 proteolysis and suggests that OGG1 is a target for calpain-mediated degradation in vivo during oxidative stress- and cisplatin-induced apoptosis. Polymorphic OGG1 S326C was comparatively resistant to calpain digestion in vitro, yet was also degraded by a calpain-dependent pathway in vivo following DNA damaging agent exposure. The degradation of OGG1 by calpain may contribute to decreased 8-oxoguanine repair activity and elevated levels of 8-oxoguanine reported in tissues undergoing chronic oxidative stress, ischemia/reperfusion, and other cellular stressors known to produce perturbations of intracellular calcium homeostasis which activate calpain.
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PMID:OGG1 is degraded by calpain following oxidative stress and cisplatin exposure. 1829 29

Emerging as an epidemic of the 21st century type 2 diabetes has become a major health problem throughout the globe. The number of deaths attributable to diabetes reflects the insufficient glycemic control achieved with the treatments used in recent past. DPP-4 inhibitors have been investigated as a new therapy with novel mechanisms of action and improved tolerability. DPP-4, a protease that specifically cleaves dipeptides from proteins and oligopeptides after a penultimate N-terminal proline or alanine, is involved in the degradation of a number of neuropeptides, peptide hormones and cytokines, including the incretins GLP-1 and GIP. As soon as released from the gut in response to food intake, GLP-1 and GIP exert a potent glucose-dependent insulinotropic action, thereby playing a key role in the maintenance of post-meal glycemic control. Consequently, inhibiting DPP-4 prolongs the action of GLP-1 and GIP, which in turn improves glucose homeostasis with a low risk of hypoglycemia and potential for disease modification. Indeed, clinical trials involving diabetic patients have shown improved glucose control by administering DPP-4 inhibitors, thus demonstrating the benefit of this promising new class of antidiabetics. Intense research activities in this area have resulted in the launch of sitagliptin and vildagliptin (in Europe only) and the advancement of a few others into preregistration/phase 3, for example, saxagliptin, alogliptin and ABT-279. Achieving desired selectivity for DPP-4 over other related peptidases such as DPP-8 and DPP-9 (inhibition of which was linked to toxicity in animal studies) and long-acting potential for maximal efficacy (particularly in more severe diabetic patients) were the major challenges. Whether these goals are achieved with the present series of inhibitors in the advanced stages of clinical development is yet to be confirmed. Nevertheless, treatment of this metabolic disorder especially in the early stages of the disease via DPP-4 inhibition has been recognized as a validated principle and a large number of inhibitors are presently in various stage of pre-clinical/clinical development. Sitagliptin is a new weapon in the arsenal of oral antihyperglycemic agents. This review will focus on the journey of drug discovery of DPP-4 inhibitors for oral delivery covering a brief scientific background and medicinal chemistry approaches along with the status of advanced clinical candidates.
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PMID:Medicinal chemistry approaches to the inhibition of dipeptidyl peptidase-4 for the treatment of type 2 diabetes. 1921 90

A series of 4-substituted proline amides was synthesized and evaluated as inhibitors of dipeptidyl pepdidase IV for the treatment of type 2 diabetes. (3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone (5) emerged as a potent (IC(50) = 13 nM) and selective compound, with high oral bioavailability in preclinical species and low plasma protein binding. Compound 5, PF-00734200, was selected for development as a potential new treatment for type 2 diabetes.
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PMID:(3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone: a potent, selective, orally active dipeptidyl peptidase IV inhibitor. 1927 64


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