Nakanaga, K., Hama, K., Kano, K., Sato, T., Yukiura, H., Inoue, A., Saigusa, D., Tokuyama, H., Tomioka, Y., Nishina, H., Kawahara, A., and Aoki, J. (2014) Overexpression of autotaxin, a lysophosphatidic acid-producing enzyme, enhances cardia bifida induced by hypo-sphingosine-1-phosphate signaling in zebrafish embryo. Journal of biochemistry. 155(4):235-41.
Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are second-generation lysophospholipid mediators that exert
multiple biological functions through their own cognate receptors. They are both present in the blood stream, activate receptors
with similar structures (endothelial differentiation gene receptors), have similar roles in the vasculature and are vasoactive.
However, it is unclear whether these lysophospholipid mediators cross-talk downstream of each receptor. Here, we provide in vivo evidence that LPA signaling counteracted S1P signaling. When autotaxin (Atx), an LPA-producing enzyme, was overexpressed
in zebrafish embryos by injecting atx mRNA, the embryos showed cardia bifida, a phenotype induced by down-regulation of S1P signaling. A similar cardiac phenotype
was not induced when catalytically inactive Atx was introduced. The cardiac phenotype was synergistically enhanced when antisense
morpholino oligonucleotides (MO) against S1P receptor (s1pr2/mil) or S1P transporter (spns2) was introduced together with atx mRNA. The Atx-induced cardia bifida was prominently suppressed when embryos were treated with an lpar1 receptor antagonist, Ki16425, or with MO against lpar1. These results provide the first in vivo evidence of cross-talk between LPA and S1P signaling.