sphingosine-1-phosphate and Cardiomegaly

To investigate the effects of sphingosine-1-phosphate (S1P) on cardiac hypertrophic response in H9c2 cells.. H9c2 cells were randomly divided into four groups: normal control group, S1P (1 μmol/L) treated group, Phenylephrine (PE) (100 μmol/L) treated group, PE (100 μmol/L) treated group combined with S1P (1 μmol/L) treatment. Each group has 3 duplicated wells. After 24 hours, the size of H9c2 cells in each group was detected by Actin-Trakcer Green immunofluorescence staining. Transcriptional levels of hypertrophic markers ( ANP, BNP and β-MHC) in H9c2 cells were determined by real-time PCR. Western blot was performed to examine the expression level of ANP in each group. Then H9c2 cells were randomly divided into five groups: normal control group, PE (100 μmol/L) treated group, PE (100 μmol/L) with S1P low-dose (0.1 μmol/L) treated group, PE (100 μmol/L) with S1P middle-dose (1 μmol/L) treated group and PE (100 μmol/L) with S1P high-dose (10 μmol/L) treated group. Each group has 3 duplicated wells. After 24 hours, Western blot was performed to examine the expressions of phosphorylated Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3) under low, medium and high concentrations of S1P. Each experiment was repeated three times.. Compared with normal control group, the surface area of H9c2 cells in PE group was increased significantly (. S1P could protect H9c2 cells against hypertrophic response induced by PE, which may be achieved by activating JAK2/STAT3 signal pathway.

Topics: Cardiomegaly; Cell Line; Humans; Lysophospholipids; Myocytes, Cardiac

Inhibition of histone deacetylase-2 (HDAC2), which is a prohypertrophic factor in the heart, can functionally attenuate cardiac hypertrophy. The present study aimed to investigate whether sphingosine‑1‑phosphate (S1P), which has recently been reported to suppress HDAC2 activity, could ameliorate the cardiac hypertrophic response and improve cardiac function in mice with transverse aortic constriction (TAC), as well as to determine the underlying mechanisms. Briefly, 8‑week‑old male C57BL/6 mice were randomly divided into sham, TAC and TAC + S1P groups; the results indicated that S1P treatment attenuated TAC‑induced cardiac dysfunction. In addition, heart size and the expression levels of fetal cardiac genes were reduced in the TAC + S1P group compared with in the TAC group. Furthermore, in cultured H9c2 cells exposed to phenylephrine, S1P was revealed to decrease cardiomyocyte size and the exaggerated expression of fetal cardiac genes. The present study also demonstrated that S1P had no effect on HDAC2 expression, but it did suppress its activity and increase acetylation of histone H3 in vivo and in vitro. Krüppel‑like factor 4 (KLF4) is an antihypertrophic transcriptional regulator, which mediates HDAC inhibitor‑induced prevention of cardiac hypertrophy; in the present study, KLF4 was upregulated by S1P. Finally, the results indicated that S1P receptor 2 (S1PR2) may be involved in the antihypertrophic effects, whereas the suppressive effects of S1P on HDAC2 activity were independent of S1PR2. In conclusion, the present study demonstrated that S1P treatment may ameliorate the cardiac hypertrophic response, which may be partly mediated by the suppression of HDAC2 activity and the upregulation of KLF4; it was suggested that S1PR2 may also be involved. Therefore, S1P may be considered a potential therapy for the treatment of heart diseases caused by cardiac hypertrophy.

Topics: Animals; Aorta; Cardiomegaly; Cells, Cultured; Constriction, Pathologic; Electrocardiography; Hemodynamics; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Lysophospholipids; Male; Mice, Inbred C57BL; Models, Biological; Phenylephrine; Rats; Receptors, Lysosphingolipid; RNA, Small Interfering; Sphingosine; Up-Regulation

Sphingosine 1 phosphate (S1P), an aminophospholipid, acts extracellularly as a ligand via the specific G protein-coupled receptors of the endothelial differentiation gene (EDG) 1, 3, 5, 6 and 8 receptors family and intracellularly as a second messenger in various cellular types. The aim of this work was to investigate biological activity of S1P in cardiomyocytes with respect to related sphingolipids. S1P was applied for 48 h on rat neonatal cardiomyocytes at 10 nM, 100 nM and 1 microM. S1P induced a concentration-dependent cellular hypertrophy evidenced by an increase in cell size, [3H]-phenylalanine incorporation, protein content and Brain Natriuretic Peptide (BNP) secretion. Among the lipids tested S1P exhibits the lower EC50 (67 nM) followed by dihydro-S1P (107 nM) and sphingosylphosphorylcholine (1.6 microM). The effect of S1P could be related to a stimulation of the EDG1 receptor since we showed that the EDG1 receptor is predominantly expressed at the mRNA and protein levels in rat cardiomyocytes and that specific anti-EDG1 antibodies inhibited the hypertrophic effect induced by S1P. Furthermore the expression level of most other EDG receptors for S1P appeared very low in cardiac myocytes. S1P (100 nM) increased the phosphorylation of p42/44MAPK, p38MAPK, JNK, Akt and p70(S6K), this effect being reversed by inhibitors of their respective phosphorylation which also rescue the hypertrophic phenotype. Finally, S1P stimulated actin stress fibre formation reverted by the Rho inhibitor, the C3 exoenzyme. Altogether, our results show that S1P induces cardiomyocyte hypertrophy mainly via the EDG1 receptor and subsequently via Gi through ERKs, p38 MAPK, JNK, PI3K and via Rho pathway.

Topics: Adrenergic alpha-Agonists; Animals; Animals, Newborn; Cardiomegaly; Cells, Cultured; Culture Media, Serum-Free; Dose-Response Relationship, Drug; Heart; Humans; Immediate-Early Proteins; Lysophospholipids; Microscopy, Fluorescence; Mitogen-Activated Protein Kinases; Myocardium; Peptides; Phenylephrine; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Structure, Tertiary; Rats; Rats, Wistar; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Receptors, Lysophospholipid; Sphingosine; Stress Fibers; Tissue Extracts; Virulence Factors, Bordetella