sew2871 and dihydrosphingosine-1-phosphate

Cardiac fibrosis and myocyte hypertrophy are hallmarks of the cardiac remodelling process in cardiomyopathies such as heart failure (HF). Dyslipidemia or dysregulation of lipids contribute to HF. The dysregulation of high density lipoproteins (HDL) could lead to altered levels of other lipid metabolites that are bound to it such as sphingosine-1- phosphate (S1P). Recently, it has been shown that S1P and its analogue dihydrosphingosine-1-phosphate (dhS1P) are bound to HDL in plasma. The effects of dhS1P on cardiac cells have been obscure. In this study, we show that extracellular dhS1P is able to increase collagen synthesis in neonatal rat cardiac fibroblasts (NCFs) and cause hypertrophy of neonatal cardiac myocytes (NCMs). The janus kinase/signal transducer and activator (JAK/STAT) signalling pathway was involved in the increased collagen synthesis by dhS1P, through sustained increase of tissue inhibitor of matrix metalloproteinase 1 (TIMP1). Extracellular dhS1P increased phosphorylation levels of STAT1 and STAT3 proteins, also caused an early increase in gene expression of transforming growth factor-β (TGFβ), and sustained increase in TIMP1. Inhibition of JAKs led to inhibition of TIMP1 and TGFβ gene and protein expression. We also show that dhS1P is able to cause NCM hypertrophy through S1P-receptor-1 (S1PR1) signalling which is opposite to that of its analogue, S1P. Taken together, our results show that dhS1P increases collagen synthesis in cardiac fibroblasts causing fibrosis through dhS1P-JAK/STAT-TIMP1 signalling.

Topics: Animals; Animals, Newborn; Biomarkers; Cell Differentiation; Collagen; Fibroblasts; Gene Expression Regulation; Hypertrophy; Janus Kinases; Lysophospholipids; Matrix Metalloproteinase 2; Models, Biological; Myocardium; Myocytes, Cardiac; Oxadiazoles; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Rats, Sprague-Dawley; RNA, Messenger; Signal Transduction; Smad2 Protein; Sphingosine; STAT Transcription Factors; Thiophenes; Time Factors; Tissue Inhibitor of Metalloproteinase-1; Transforming Growth Factor beta

Liver failure due to ischemia and reperfusion (IR) and subsequent acute kidney injury are significant clinical problems. We showed previously that liver IR selectively reduced plasma sphinganine-1-phosphate levels without affecting sphingosine-1-phosphate (S1P) levels. Furthermore, exogenous sphinganine-1-phosphate protected against both liver and kidney injury induced by liver IR. In this study, we elucidated the signaling mechanisms of sphinganine-1-phosphate-mediated renal and hepatic protection. A selective S1P(1) receptor antagonist blocked the hepatic and renal protective effects of sphinganine-1-phosphate, whereas a selective S1P(2) or S1P(3) receptor antagonist was without effect. Moreover, a selective S1P(1) receptor agonist, SEW-2871, provided similar degree of liver and kidney protection compared with sphinganine-1-phosphate. Furthermore, in vivo gene knockdown of S1P(1) receptors with small interfering RNA abolished the hepatic and renal protective effects of sphinganine-1-phosphate. In contrast to sphinganine-1-phosphate, S1P's hepatic protection was enhanced with an S1P(3) receptor antagonist. Inhibition of extracellular signal-regulated kinase, Akt or pertussis toxin-sensitive G-proteins blocked sphinganine-1-phosphate-mediated liver and kidney protection in vivo. Taken together, our results show that sphinganine-1-phosphate provided renal and hepatic protection after liver IR injury in mice through selective activation of S1P(1) receptors and pertussis toxin-sensitive G-proteins with subsequent activation of ERK and Akt.

Topics: Acute Kidney Injury; Animals; Extracellular Signal-Regulated MAP Kinases; Ischemia; Kidney; Liver; Liver Diseases; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Oxadiazoles; Proto-Oncogene Proteins c-akt; Receptors, Lysosphingolipid; Reperfusion Injury; Signal Transduction; Sphingosine; Thiophenes