jte-013 and Diabetic-Nephropathies

Sphingosine-1-phosphate receptor 2 (S1PR2) is a G-protein-coupled receptor that regulates sphingosine-1-phosphate-triggered cellular response. However, the role of S1PR2 in diabetes-induced glomerular endothelial cell dysfunction remains unclear. This study aims to investigate the effect of S1PR2 blockade on the morphology and function of mitochondria in human renal glomerular endothelial cells (HRGECs).. HRGECs were pretreated with a S1PR2 antagonist (JTE-013) or a Rho-associated coiled coil-containing protein kinase 1 (ROCK1) inhibitor (Y27632) for 30 min and then cultured with normal glucose (5.5 mM) or high glucose (30 mM) for 72 h. The protein expression levels of RhoA, ROCK1, and Dynmin-related protein-1(Drp1) were evaluated by immunoblotting; mitochondrial morphology was observed by electron microscopy; intracellular levels of ATP, ROS, and Ca. High glucose induced mitochondrial fission and dysfunction, indicated by increased mitochondrial fragmentation, ROS generation, and calcium overload but decreased ATP production. High glucose also induced endothelial cell dysfunction, indicated by increased permeability and apoptosis but decreased migration. However, inhibition of either S1PR2 or ROCK1 almost completely blocked these high glucose-mediated cellular responses. Furthermore, inhibiting S1PR2 resulted in the deceased expression of RhoA, ROCK1, and Drp1 while inhibiting ROCK1 led to the downregulated expression of Drp1.. S1PR2 antagonist modulates the morphology and function of mitochondria in HRGECs via the positive regulation of the RhoA/ROCK1/Drp1 signaling pathway, suggesting that the S1PR2/ROCK1 pathway may play a crucial role in high glucose milieu.

Topics: Amides; Blood Glucose; Cells, Cultured; Diabetic Nephropathies; Endothelial Cells; Enzyme Inhibitors; Humans; Kidney Glomerulus; Mitochondria; Pyrazoles; Pyridines; rho-Associated Kinases; Signal Transduction; Sphingosine-1-Phosphate Receptors

Accumulation of extracellular matrix including fibronectin in mesangium is one of the major pathologic characteristics in diabetic nephropathy. In the current study, we explored role of sphingosine-1-phosphate (S1P) receptor in fibronectin expression and underlying molecular mechanism. Among five S1P receptors the mRNA level of S1P2 receptor was the most abundant in kidney of diabetic rats and mesangial cells under high glucose condition. S1P augmentation of fibronectin was significantly inhibited by S1P2 receptor antagonist JTE-013 and S1P2-siRNA. S1P-stimulated fibronectin expression was remarkably blocked by ERK1/2 inhibitor PD98059 and p38MAPK inhibitor SB203580. Phospho-ERK1/2 and phospho-p38MAPK level induced by S1P were markedly abrogated by JTE-013 and S1P2-siRNA. In conclusion, S1P2 receptor was significantly up-regulated under diabetic condition. S1P2 receptor mediated fibronectin expression through the activation of S1P-S1P2-MAPK (ERK1/2 and p38MAPK) axis in mesangial cells under high glucose condition, suggesting that it might be a potential therapeutic target for diabetic nephropathy treatment.

Topics: Animals; Diabetic Nephropathies; Extracellular Matrix; Extracellular Signal-Regulated MAP Kinases; Fibronectins; Flavonoids; Glucose; Hyperglycemia; Imidazoles; Kidney; Lysophospholipids; MAP Kinase Signaling System; Mesangial Cells; p38 Mitogen-Activated Protein Kinases; Pyrazoles; Pyridines; Rats; Rats, Sprague-Dawley; Receptors, Lysosphingolipid; RNA Interference; RNA, Messenger; RNA, Small Interfering; Sphingosine; Sphingosine-1-Phosphate Receptors