Sphingosine-1-phosphate and sphingosine kinase are critical for transforming growth factor-beta-stimulated collagen production by cardiac fibroblasts.
OBJECTIVE
Following injury, fibroblasts transform into myofibroblasts and produce extracellular matrix (ECM). Excess production of ECM associated with cardiac fibrosis severely inhibits cardiac function. Sphingosine-1-phosphate (S1P), a bioactive lysophospholipid, regulates the function of numerous cell types. In this study, we determined the role of S1P in promoting pro-fibrotic actions of cardiac fibroblasts (CFs).


RESULTS
S1P-mediated effects on myofibroblast transformation, collagen production, and cross-talk with transforming growth factor-beta (TGF-beta) using mouse CF were examined. S1P increased alpha-smooth muscle actin (a myofibroblast marker) and collagen expression in a S1P2 receptor- and Rho kinase-dependent manner. TGF-beta increased sphingosine kinase 1 (SphK1; the enzyme responsible for S1P production) expression and activity. TGF-beta-stimulated collagen production was inhibited by SphK1 or S1P2 siRNA, a SphK inhibitor, and an anti-S1P monoclonal antibody.


CONCLUSIONS
These findings suggest that TGF-beta-stimulated collagen production in CF involves 'inside-out' S1P signalling whereby S1P produced intracellularly by SphK1 can be released and act in an autocrine/paracrine fashion to activate S1P2 and increase collagen production.
Gellings Lowe
Nicole
N
Department of Biology, San Diego State University, 5500 Campanile Dr, San Diego, CA 92182-4614, USA.
Swaney
James S
JS
Moreno
Kelli M
KM
Sabbadini
Roger A
RA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008233:Lymphotoxin-alpha / Q000494:pharmacology*; D008246:Lysophospholipids / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism; D000099157:Sphingosine Kinase
D000911:Antibodies, Monoclonal; D003094:Collagen; D004791:Enzyme Inhibitors; D008233:Lymphotoxin-alpha; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D034741:RNA, Small Interfering; D013110:Sphingosine; D054460:rho-Associated Kinases; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate