Insulin-degrading enzyme deficiency in bone marrow cells increases atherosclerosis in LDL receptor-deficient mice

Insulin-Degrading Enzyme, an Under-Estimated Potential Target to Treat Cancer?

Insulin-degrading enzyme (IDE) is a multifunctional protease due to the variety of its substrates, its various cellular locations, its conservation between species and its many non-proteolytic functions. Numerous studies have successfully demonstrated its implication in two main therapeutic areas: metabolic and neuronal diseases. In recent years, several reports have underlined the overexpression of this enzyme in different cancers. Still, the exact role of IDE in the physiopathology of cancer remains to be elucidated. Known as the main enzyme responsible for the degradation of insulin, an essential growth factor for healthy cells and cancer cells, IDE has also been shown to behave like a chaperone and interact with the proteasome. The pharmacological modulation of IDE (siRNA, chemical compounds, etc.) has demonstrated interesting results in cancer models. All these results point towards IDE as a potential target in cancer. In this review, we will discuss evidence of links between IDE and cancer development or resistance, IDE's functions, catalytic or non-catalytic, in the context of cell proliferation, cancer development and the impact of the pharmacomodulation of IDE via cancer therapeutics.

Inhibition of Insulin Degrading Enzyme to Control Diabetes Mellitus and its Applications on some Other Chronic Disease: a Critical Review

PURPOSE

This review aims to provide a precise perceptive of the insulin-degrading enzyme (IDE) and its relationship to type 2 diabetes (T2D), Alzheimer's disease (AD), obesity, and cardiovascular diseases. The purpose of the current study was to provide clear idea of treating prevalent diseases such as T2D, and AD by molecular pharmacological therapeutics rather than conventional medicinal therapy.

METHODS

To achieve the aims, molecular docking was performed using several softwares such as LIGPLOT+, Python, and Protein-Ligand Interaction Profiler with corresponding tools.

RESULTS

The IDE is a large zinc-metalloprotease that breakdown numerous pathophysiologically important extracellular substrates, comprising amyloid β-protein (Aβ) and insulin. Recent studies demonstrated that dysregulation of IDE leads to develop AD and T2D. Specifically, IDE regulates circulating insulin in a variety of organs via a degradation-dependent clearance mechanism. IDE is unique because it was subjected to allosteric activation and mediated via an oligomer structure.

CONCLUSION

In this review, we summarised the factors that modulate insulin reformation by IDE and interaction of IDE and some recent reports on IDE inhibitors against AD and T2D. We also highlighted the latest signs of progress of the function of IDE and challenges in advancing IDE- targetted therapies against T2D and AD.

Modulation of Insulin Sensitivity by Insulin-Degrading Enzyme

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.

Hepatic insulin-degrading enzyme regulates glucose and insulin homeostasis in diet-induced obese mice

The insulin-degrading enzyme (IDE) is a metalloendopeptidase with a high affinity for insulin. Human genetic polymorphisms in Ide have been linked to increased risk for T2DM. In mice, hepatic Ide ablation causes glucose intolerance and insulin resistance when mice are fed a regular diet.

OBJECTIVE

These studies were undertaken to further investigate its regulatory role in glucose homeostasis and insulin sensitivity in diet-induced obesity.

METHODS

To this end, we have compared the metabolic effects of loss versus gain of IDE function in mice fed a high-fat diet (HFD).

RESULTS

We demonstrate that loss of IDE function in liver (L-IDE-KO mouse) exacerbates hyperinsulinemia and insulin resistance without changes in insulin clearance but in parallel to an increase in pancreatic β-cell function. Insulin resistance was associated with increased FoxO1 activation and a ~2-fold increase of GLUT2 protein levels in the liver of HFD-fed mice in response to an intraperitoneal injection of insulin. Conversely, gain of IDE function (adenoviral delivery) improves glucose tolerance and insulin sensitivity, in parallel to a reciprocal ~2-fold reduction in hepatic GLUT2 protein levels. Furthermore, in response to insulin, IDE co-immunoprecipitates with the insulin receptor in liver lysates of mice with adenoviral-mediated liver overexpression of IDE.

CONCLUSIONS

We conclude that IDE regulates hepatic insulin action and whole-body glucose metabolism in diet-induced obesity via insulin receptor levels.

Hepatic Insulin Clearance: Mechanism and Physiology

Upon its secretion from pancreatic β-cells, insulin reaches the liver through the portal circulation to exert its action and eventually undergo clearance in the hepatocytes. In addition to insulin secretion, hepatic insulin clearance regulates the homeostatic level of insulin that is required to reach peripheral insulin target tissues to elicit proper insulin action. Receptor-mediated insulin uptake followed by its degradation constitutes the basic mechanism of insulin clearance. Upon its phosphorylation by the insulin receptor tyrosine kinase, carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) takes part in the insulin-insulin receptor complex to increase the rate of its endocytosis and targeting to the degradation pathways. This review summarizes how this process is regulated and how it is associated with insulin-degrading enzyme in the liver. It also discusses the physiological implications of impaired hepatic insulin clearance: Whereas reduced insulin clearance cooperates with increased insulin secretion to compensate for insulin resistance, it can also cause hepatic insulin resistance. Because chronic hyperinsulinemia stimulates hepatic de novo lipogenesis, impaired insulin clearance also causes hepatic steatosis. Thus impaired insulin clearance can underlie the link between hepatic insulin resistance and hepatic steatosis. Delineating these regulatory pathways should lead to building more effective therapeutic strategies against metabolic syndrome.

PreImplantation factor prevents atherosclerosis via its immunomodulatory effects without affecting serum lipids

PreImplantation factor (PIF) is a 15-amino acid peptide endogenously secreted by viable embryos, regulating/enabling maternal (host) acceptance/tolerance to the “invading” embryo (allograft) all-while preserving maternal immunity to fight infections. Such attributes make PIF a potential therapeutic agent for chronic inflammatory diseases. We investigated whether PIF’s immunomodulatory properties prevent progression of atherosclerosis in the hyper-cholesterolaemic ApoEdeficient murine model. Male, high-fat diet fed, ApoE-deficient (ApoE-/-) mice were administered either PBS, scrambled PIF (0.3–3 mg/kg) or PIF (0.3–3 mg/kg) for seven weeks. After treatment, PIF (3 mg/kg)-treated ApoE-/- mice displayed significantly reduced atherosclerosis lesion burden in the aortic sinus and aortic arch, without any effect on lipid profile. PIF also caused a significant reduction in infiltration of macrophages, decreased expression of pro-inflammatory adhesion molecules, cytokines and chemokines in the plaque, and reduced circulating IFN-γ levels. PIF preferentially binds to monocytes/neutrophils. In vitro, PIF attenuated monocyte migration (MCP-1-induced chemotaxis assay) and in vivo in LPS peritonitis model. Also PIF prevented leukocyte extravasation (peritonitis thioglycollate-induced model), demonstrating that PIF exerts its effect in part by modulation of monocyte function. Inhibition of the potassium channel KCNAB3 (Kv1.3) and of the insulin degrading enzyme (IDE) was demonstrated as potential mechanism of PIF’s immunomodulatory effects. In conclusion, PIF regulates/lowers inflammation and prevents atherosclerosis development without affecting circulating lipids. Overall our findings establish PIF as a strong immunomodulatory drug candidate for atherosclerosis therapy.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Targeting Insulin-Degrading Enzyme to Treat Type 2 Diabetes Mellitus

Insulin-degrading enzyme (IDE) selectively degrades peptides, such as insulin, amylin, and amyloid β (Aβ) that form toxic aggregates, to maintain proteostasis. IDE defects are linked to the development of type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD). Structural and biochemical analyses revealed the molecular basis for IDE-mediated destruction of amyloidogenic peptides and this information has been exploited to develop promising inhibitors of IDE to improve glucose homeostasis. However, the inhibition of IDE can also lead to glucose intolerance. In this review, I focus on recent advances regarding our understanding of the structure and function of IDE and the discovery of IDE inhibitors, as well as challenges in developing IDE-based therapy for human diseases, particularly T2DM.

Impaired Aβ clearance: a potential link between atherosclerosis and Alzheimer's disease

Alzheimer’s Disease (AD) and atherosclerosis remain two of the largest public health burdens in the world today. Although traditionally considered distinct pathological entities, mounting epidemiologic, clinical and experimental evidence suggests that cerebrovascular atherosclerosis and AD interact reciprocally to disrupt brain structure and function. Whereas the hypoperfusion and hypoxia caused by atherosclerosis of cerebral vessels may enhance the production of amyloid-β peptide (Aβ), a peptide central to AD pathology, Aβ, in turn, may promote formation of atherosclerotic lesions through vascular oxidative stress and endothelial dysfunction leading to additional vascular damage. Here, we briefly review evidence suggesting that impaired clearance of Aβ is an additional, simultaneously occurring mechanism by which AD and cerebrovascular disease may be causally linked. We examine the literature supporting mechanisms by which flow-limiting large-artery stenosis, arterial stiffening and microvascular dysfunction could contribute to AD pathophysiology by impairing Aβ clearance and elevating brain levels of Aβ. Finally, we highlight the need for further research to improve our understanding of the complex interactions of AD and atherosclerosis with Aβ clearance, which may ultimately serve to guide the development of novel diagnostic and therapeutic approaches for this devastating and highly prevalent condition.