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)

Dipeptidyl peptidase IV (DPP-IV) deactivates the incretin hormones GLP-1 and GIP by cleaving the penultimate proline or alanine from the N-terminal (P1-position) of the peptide. Inhibition of this enzyme will prevent the degradation of the incretin hormones and maintain glucose homeostasis; this makes it an attractive target for the development of drugs for diabetes. This paper reports 3D-QSAR analysis of several DPP-IV inhibitors, which were aligned by the receptor-based technique. The conformation of the molecules in the active site was obtained through docking methods. The QSAR models were generated on two training sets composed of 74 and 25 molecules which included phenylalanine, thiazolidine, and fluorinated pyrrolidine analogs. The 3D-QSAR models are robust with statistically significant r(2), q(2), and r(pred)(2) values. The CoMFA and CoMSIA models were used to design some new inhibitors with several fold higher binding affinity.
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PMID:3D-QSAR studies of Dipeptidyl peptidase IV inhibitors using a docking based alignment. 1767 45

Type 2 diabetes is a heterogeneous, polygenic disorder in which dysfunction in a number of important metabolic pathways appears to play roles. Although it remains unclear exactly which event triggers the disorder, beta-cell dysfunction is a key element in the underlyingpathophysiology. Both impaired insulin secretion and insulin resistance contribute to the hyperglycemic state that causes the devastating cardiovascular, neurologic, and renal effects characteristic of type 2 diabetes. To prevent these complications, the American Diabetes Association recommends maintaining A1C levels below 7%. A1C has long been the target of diabetes therapy, and while this remains true in those with A1C levels above 8.4%, it is now apparent that in those with mild to moderate diabetes, postprandial glucose excursions may be of greater importance. Postprandial hyperglycemia occurs in 74% of those diagnosed with diabetes and 39% of those with optimal A1C levels. Involvement of impaired alpha-cell function has recently been recognized in the pathophysiology of type 2 diabetes. As a result of this dysfunction, glucagon and hepatic glucose levels that rise during fasting are not suppressed with a meal. Given inadequate levels of insulin and increased insulin resistance, hyperglycemia results. The incretins are important gut mediators of insulin release, and in the case of GLP-1, of glucagon suppression. Although GIP activity is impaired in those with type 2 diabetes, GLP-1 insulinotropic effects are preserved, and thus GLP-1 represents a potentially beneficial therapeutic option. However, like GIP, GLP-1 is rapidly inactivated by DPP-IV in vivo. Two therapeutic approaches to this problem have been developed: GLP-1 analogs with increased half-lives, and DPP-IV inhibitors, which prevent the breakdown of endogenous GLP-1 as well as GIP. Both classes of agent have shown promise, with potential not only to normalize fasting and postprandial glucose levels but also to improve beta-cell functioning and mass.
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PMID:Pathophysiology of type 2 diabetes and the role of incretin hormones and beta-cell dysfunction. 1821 45

In the pathogenesis of diabetes type 2, increasing insulin resistance is accompanied by dysfunction of pancreatic islet b cells. It is hypothesized that at the basis of this pathology lies an incretin defect of insulinotropic gut-derived hormones, relying on decreased secretion of GLP-1 (glucagon-like peptide 1), with preserved insulinotropic effect, whereas GIP (glucose-dependent insulinotropic polypeptide) secretion remains within physiological limits, but its action is mostly impaired due to total loss of possibility for stimulation of the second phase insulin secretion. Possibilities for pharmacological correction of incretin defect create an opportunity of causative treatment of diabetes and provide basis for development of research on a new group of drugs which promote hypoglycemia. In the presence of these findings there are many ongoing clinical studies with the use of GLP-1 analogues or GLP-1 receptors activators (GLP-1 agonists), as well as the inhibitors of dipeptidyl peptidase IV (DPP-IV), the enzyme responsible for incretin proteolysis, in the treatment of type 2 diabetes. Multidirectional, glucoregulative mechanism of action of these drugs, aiming at the pathogenesis of the disease, restores the proper function of the intestinal-pancreatic axis in subjects with type 2 diabetes and ensures good metabolic control and improvement in quality of life in this group of patients.
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PMID:[Incretin hormones in the treatment of type 2 diabetes. Part II. Incretins - new possibilities for pharmacotherapy of type 2 diabetes]. 1877 3

Type 2 diabetes mellitus is an increasingly prevalent condition worldwide. The complications of this disease are known to significantly increase the morbidity and mortality of those affected, resulting in substantial direct and indirect costs. Although good glycemic control has been shown to reduce the incidence and progression of diabetes-related microvascular complications, blood glucose levels are not adequately controlled in most individuals with diabetes. The reasons for this are many, and include issues such as poor adherence to complex medication regimes; costs of prescribed therapies; and the failure of traditionally prescribed medications to preserve beta cell function over time. However, our armamentarium of glucose-lowering drugs has expanded recently with the development of medications that act via the incretin pathway. Sitagliptin, the first commercially available dipeptidyl peptidase-4 inhibitor, inhibits the metabolism and inactivation of the incretin hormones GLP-1 and GIP. The subsequent elevation in levels of these hormones and associated prolongation of their actions has been shown to increase insulin secretion and suppress glucagon secretion in a glucose-appropriate fashion. Sitagliptin therapy in individuals with type 2 diabetes has been found to lower significantly hemoglobin A1c (Hb1c) levels with a minimum of adverse side effects such as weight gain or hypoglycemia. Use of sitagliptin in conjunction with the insulin-sensitizing medication metformin has been shown to decrease HbAlc levels more significantly than does either drug alone. This combination of medications is generally well tolerated, with no adverse effects on weight and a very low likelihood of treatment-related hypoglycemia. Use of both drugs will positively affect many of the underlying metabolic abnormalities associated with type 2 diabetes, including the disordered secretion of insulin and glucagon as well as impaired sensitivity to insulin which are known to accompany this disease. Animal studies also suggest that dipeptidyl peptidase-4 inhibitor treatment may help to preserve beta cell mass; however, it is unclear at present whether or not this will prove to be the case in humans.
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PMID:New combination treatments in the management of diabetes: focus on sitagliptin-metformin. 1906 92

Some studies indicate that diabetes mellitus exerts an influence on the gastrointestinal tract and its diffuse neuroendocrine system (DNES) in regard to cellular density and neuroendocrine content. Since there is no data about relationship between experimentally induced non-insulin-dependent (type 2) diabetes mellitus (NIDDM) on the gut K cells, the aim of our study was to investigate immunohistochemical, stereological and ultrastructural changes of rat K cells after 12 days of dexamethasone treatment. Twenty male Wistar rats aged 30 days were given daily intraperitoneally 2 mg kg(-1) dexamethasone (group DEX, 10 rats) or saline (group C, 10 rats) for 12 days. Tissue specimens were obtained from each antrum with corpus and different parts of the small (SI) and large intestine (LI) of all animals. Immunohistochemistry was carried out using antisera against the GIP and insulin. Transmission electron microscopy was also used. Although, according to the literature data, rat K cells are present in the duodenum and jejunum and, to a lesser extent, in the ileum, in the present study we observed that those cells were abundant also in all parts of the LI. We observed generally that GIP-producing K cells were augmented in all parts of SI and decreased in the LI of DEX rats. Insulin immunoreactivity (ir) coexpressed with GIP-ir in K cells and was stronger in the SI of DEX rats as compared with C rats. We also found by electron microscopy that small intestinal K cells have features not only of GIP-secreted but also of insulin-secreted cells. We concluded that dexamethasone treatment caused proliferation of K cells in the rat SI, and simultaneously transformation of GIP-producing K cells to insulin-synthesizing cells.
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PMID:Glucose-dependent insulinotropic polypeptide-producing K cells in dexamethasone-treated rats. 1909 27

Improvement in Type 2 diabetes is seen in 80-98% of obese diabetic patients who undergo gastric bypass or bilio-pancreatic diversion. This improvement is evident early after the operation before significant weight loss has occurred. Although numerous teams have extensively studied the physiology of this early post-bypass amelioration of type 2 diabetes, the exact mechanism of diabetes remission remains unclear. Studies have focused on changes in the entero-insular axis, which is mediated in part by the interaction of insulinotropic hormones GIP and GIP 1 on the beta islet cells of the pancreas. Other mechanisms which have been postulated focus on the adipo-insular axis; the actions of adiponectin and leptin seem to have an important role in insulin resistance but their action is weight-loss dependent. Post-operative caloric restriction may also contribute to the early resolution of type 2 diabetes observed after gastric bypass and bilio- pancreatic diversion.
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PMID:[Early improvement in Type 2 diabetes in obese patients following gastric bypass and bilio-pancreatic diversion: the role of the entero-insular axis]. 1910 85

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

Recent human genetics studies have revealed that common variants of the TCF7L2 (T-cell factor 7-like 2, formerly known as TCF4) gene are strongly associated with type 2 diabetes mellitus (T2DM). We have shown that TCF7L2 expression in the beta-cells is correlated with function and survival of the insulin-producing pancreatic beta-cell. In order to understand how variations in TCF7L2 influence diabetes progression, we investigated its mechanism of action in the beta-cell. We show robust differences in TCF7L2 expression between healthy controls and models of T2DM. While mRNA levels were approximately 2-fold increased in isolated islets from the diabetic db/db mouse, the Vancouver Diabetic Fatty (VDF) Zucker rat and the high fat/high sucrose diet-treated mouse compared with the non-diabetic controls, protein levels were decreased. A similar decrease was observed in pancreatic sections from patients with T2DM. In parallel, expression of the receptors for glucagon-like peptide 1 (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIP-R) was decreased in islets from humans with T2DM as well as in isolated human islets treated with siRNA to TCF7L2 (siTCF7L2). Also, insulin secretion stimulated by glucose, GLP-1 and GIP, but not KCl or cyclic adenosine monophosphate (cAMP) was impaired in siTCF7L2-treated isolated human islets. Loss of TCF7L2 resulted in decreased GLP-1 and GIP-stimulated AKT phosphorylation, and AKT-mediated Foxo-1 phosphorylation and nuclear exclusion. Our findings suggest that beta-cell function and survival are regulated through an interplay between TCF7L2 and GLP-1R/GIP-R expression and signaling in T2DM.
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PMID:Decreased TCF7L2 protein levels in type 2 diabetes mellitus correlate with downregulation of GIP- and GLP-1 receptors and impaired beta-cell function. 2575 58

Type 2 diabetes (T2D) and associated obesity have reached epidemic proportions, and there is an increasing need for orally effective agents that regulate glucose homeostasis with a concurrent reduction in body weight. GPR119, a class-A (rhodopsin-like) G protein-coupled receptor, expressed primarily in the human pancreas and gastrointestinal tract, has attracted considerable interest as a T2D drug target in the last three to five years. The activation of GPR119 increases the intracellular accumulation of cAMP, leading to enhanced glucose-dependent insulin secretion and increased levels of the incretin hormones GLP-1 (glucagon-like peptide 1) and GIP (glucose-dependent insulinotropic peptide). In rodent models, orally available GPR119-specific agonists have been shown to attenuate blood glucose levels with a simultaneous body weight loss. This review summarizes the research leading to the identification of GPR119 as a potential drug target for T2D and related metabolic disorders. In addition, an overview of the recent progress made in the discovery of orally active GPR119 agonists is provided.
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PMID:GPR119 agonists: a promising new approach for the treatment of type 2 diabetes and related metabolic disorders. 1956 48

Poor control of glucose homeostasis accounts for diabetes-related bone loss. Incretins - GLP-1 and GIP - have been proposed to affect bone turnover. GLP-1, apart from its anti-diabetic and other actions, has shown to exert a bone anabolic effect in streptozotocin-induced type 2 diabetic (T2D) and fructose-induced insulin-resistant (IR) rats. Exendin-4 (Ex-4), a peptide of non-mammalian nature, is sharing with GLP-1 part of its structural sequence, and also several glucoregulatory effects in mammals in an even more efficient manner. We have explored the effect of continuous administration (3 days by osmotic pump) of Ex-4 or saline (control) on bone turnover factors and bone structure in T2D and IR rats, compared to N, and the possible interaction of Ex-4 with the Wnt signalling pathway. Blood was taken before and after treatment for plasma measurements; tibiae and femurs were collected for gene expression of bone markers (RT-PCR) and structure (microCT) analysis; we also measured the mRNA levels of LRP5 - an activator of the Wnt pathway - and those of DKK1 and sclerostin (SOST) - both blockers of LRP5 activity. Compared to N-control, plasma glucose and insulin were respectively higher and lower in T2D; osteocalcin (OC) and tartrate-resistant alkaline phosphatase 5b (TRAP5b) were lower; after Ex-4, these turnover markers were further reduced in T2D and IR, while TRAP5b increased in N. Bone OC, osteoprogeterin (OPG) and receptor activator of NF-kB ligand (RANKL) mRNA were lower in T2D and IR; Ex-4 increased OC in all groups and OPG in N and IR, reduced RANKL in N and T2D but increased it in IR; the LRP5/DKK1 and LRP5/SOST mRNA ratios were similarly decreased in T2D, but in IR, the latter ratio was reduced while the former was increased; after Ex-4, both ratios augmented in N, and that of LRP5/DKK1 tended to normalize in T2D and IR. In conclusion, Ex-4 exerts osteogenic effects in T2D and IR models, and interacts with the Wnt pathway to promote bone formation.
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PMID:Exendin-4 exerts osteogenic actions in insulin-resistant and type 2 diabetic states. 1958 9


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