apyrase and Diabetes-Mellitus

Diabetes mellitus (DM) and hypertension are highly prevalent worldwide health problems and frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy, stroke, and cardiac arrhythmia, among others. Despite all existing research results and reasonable speculations, knowledge about the role of purinergic system in individuals with DM and hypertension remains restricted. Purinergic signaling accounts for a complex network of receptors and extracellular enzymes responsible for the recognition and degradation of extracellular nucleotides and adenosine. The main components of this system that will be presented in this review are: P1 and P2 receptors and the enzymatic cascade composed by CD39 (NTPDase; with ATP and ADP as a substrate), CD73 (5'-nucleotidase; with AMP as a substrate), and adenosine deaminase (ADA; with adenosine as a substrate). The purinergic system has recently emerged as a central player in several physiopathological conditions, particularly those linked to inflammatory responses such as diabetes and hypertension. Therefore, the present review focuses on changes in both purinergic P1 and P2 receptor expression as well as the activities of CD39, CD73, and ADA in diabetes and hypertension conditions. It can be postulated that the manipulation of the purinergic axis at different levels can prevent or exacerbate the insurgency and evolution of diabetes and hypertension working as a compensatory mechanism.

Topics: 5'-Nucleotidase; Adenosine Deaminase; Animals; Antigens, CD; Apyrase; Cell Communication; Diabetes Mellitus; Diet, Healthy; Exercise; Humans; Hypertension; Purinergic P1 Receptor Antagonists; Purinergic P2 Receptor Antagonists; Purines; Receptors, Purinergic P1; Receptors, Purinergic P2; Signal Transduction

Diabetes is an important risk factor for the development of cardiovascular disease including atherosclerosis and ischemic heart disease. Vascular complications including macro- and micro-vascular dysfunction are the leading causes of morbidity and mortality in diabetes. Disease mechanisms at present are unclear and no ideal therapies are available, which urgently calls for the identification of novel therapeutic targets/agents. An altered nucleotide- and nucleoside-mediated purinergic signaling has been implicated to cause diabetes-associated vascular dysfunction in major organs. Alteration of both purinergic P1 and P2 receptor sensitivity rather than the changes in receptor expression accounts for vascular dysfunction in diabetes. Activation of P2X

Topics: 5'-Nucleotidase; Adenosine Triphosphate; Animals; Apyrase; Atherosclerosis; Diabetes Mellitus; Diabetic Angiopathies; Erythrocytes; GPI-Linked Proteins; Humans; Receptors, Purinergic P1; Receptors, Purinergic P2X7; Retinal Vessels; Signal Transduction

Purinergic signaling accounts for a complex network of receptors and extracellular enzymes responsible for the generation, recognition and degradation of extracellular ATP and adenosine. The main components of this system include P2X, P2Y and Adenosine Receptors, ectonucleotidases CD39 and CD73 and Adenosine Deaminase. The purinergic network recently emerged as a central player in several physiopathological conditions particularly those linked to immune system regulation including type 1 and type 2 diabetes.. Here, we give an overview of recent findings linking purinergic signaling with diabetes pathogenesis, including purines roles in altered glucose homeostasis, impaired metabolic control, and immune system-mediated pancreatic β cells destruction. We particularly focused our attention on established preclinical experimental models of diabetes development and therapy including NOD mice, streptozotocin-induced β islets degeneration, and islet transplantation.. The summarized studies delineate a central role of purines, their receptors and degrading enzymes in diabetes by demonstrating that manipulation of the purinergic axis at different levels can prevent or exacerbate the insurgency and evolution of both type 1 and type 2 diabetes.. The reported preclinical data and the availability of several effective compounds targeting the different steps of the purinergic response strongly suggest that P2 and Adenosine Receptors or ecto-nucleotidases will be feasible therapeutic targets for the treatment of diabetes.

Topics: 5'-Nucleotidase; Adenosine Deaminase; Animals; Antigens, CD; Apyrase; Diabetes Mellitus; Humans; Receptors, Purinergic; Signal Transduction

Fibrosis of renal tubules is the final common pathway in diabetic nephropathy and develops in the face of tubular injury and fibroblast activation. Aberrant connexin 43 (Cx43) hemichannel activity has been linked to this damage under euglycaemic conditions, however, its role in glycaemic injury is unknown. This study investigated the effect of a Cx43 blocker (Tonabersat) on hemichannel activity and cell-cell interactions within and between tubular epithelial cells and fibroblasts in an in vitro model of diabetic nephropathy.. Human kidney (HK2) proximal tubule epithelial cells and medullary fibroblasts (TK173) were treated in low (5 mM) or high (25 mM) glucose ± transforming growth factor beta-1 (TGFβ1) ± Tonabersat in high glucose. Carboxyfluorescein dye uptake and ATPlite luminescence assessed changes in hemichannel-mediated ATP release, while immunoblotting determined protein expression. Co-incubation with the ATP-diphosphohydrolase apyrase or a P2X7R inhibitor (A438079) assessed ATP-P2X7R signalling. Indirect co-culture with conditioned media from the alternate cell type evaluated paracrine-mediated heterotypic interactions.. Tonabersat partially negated glucose/TGFβ1-induced increases in Cx43 hemichannel-mediated ATP release and downstream changes in adherens junction and extracellular matrix (ECM) protein expression in HK2 and TK173 cells. Apyrase and A438079 highlighted the role for ATP-P2X7R in driving changes in protein expression in TK173 fibroblasts. Indirect co-culture studies suggest that epithelial cell secretome increases Tonabersat-sensitive hemichannel-mediated dye uptake in fibroblasts and downstream protein expression.. Tonabersat-sensitive hemichannel-mediated ATP release enhances TGFβ1-driven heterotypic cell-cell interaction and favours myofibroblast activation. The data supports the potential benefit of Cx43 inhibition in reducing tubulointerstitial fibrosis in late-stage diabetic nephropathy.

Topics: Adenosine Triphosphate; Apyrase; Communication; Connexin 43; Diabetes Mellitus; Diabetic Nephropathies; Epithelial Cells; Fibroblasts; Fibrosis; Glucose; Humans

The objective of this work was to evaluate the effect of different glucose levels on the ATP, ADP and AMP hydrolysis in the platelets of diabetic, hypertensive and diabetic/hypertensive participants.. The activities of the enzymes NTPDase (ATP and ADP hydrolysis) and 5'-nucleotidase (AMP hydrolysis), and CD39 expression were analyzed in human blood platelets of diabetic (DM-2), hypertensive (HT) and diabetic/hypertensive (DM-2/HT) patients. To evaluate the interference of glucose and fructose in NTPDase and 5'-nucleotidase activities, experiments were performed with glucose, fructose and mannitol concentrations ranging from 5 to 30 mM in platelet-rich plasma (PRP). Pre-incubation times of 10, 120 min and 24h were used.. NTPDase and 5'-nucleotidase activities increased with increasing glucose and fructose concentrations (P<0.001) and the different times of pre-incubation did not interfere in ectonucleotidases activities (P>0.5). NTPDase and 5'-nucleotidase activities demonstrated a positive correlation between serum glucose levels and ATP and ADP hydrolysis in DM-2 and DM-2/HT patients. CD39 expression demonstrated that DM-2, HT and DM-2/HT groups presented a significant increase when compared to the control group (P<0.004).. The hydrolysis of adenine nucleotides is enhanced in platelets of patients with diabetes and hypertension. We observed that an increasing glucose concentration had a direct effect on ATP, ADP and AMP hydrolysis. Furthermore, CD39 expression was enhanced in all patients groups, indicating that these enzyme activities are related with diabetes and hypertension.

Topics: 5'-Nucleotidase; Adenosine Diphosphate; Adenosine Triphosphate; Adult; Aged; Albuminuria; Antigens, CD; Apyrase; Blood Glucose; Blood Platelets; C-Reactive Protein; Cholesterol; Diabetes Complications; Diabetes Mellitus; Glucose; Humans; Hypertension; Middle Aged; Nucleoside-Triphosphatase