During embryogenesis, zebra fish cardiac precursor cells (CPCs) originating from anterior lateral plate mesoderm migrate toward the midline between the endoderm and the yolk syncytial layer (YSL) to form cardiac tube. The endoderm functions as a foothold for CPCs as evidenced by the endodermal mutants (cas/sox32, sox17, oep, fau/gata5, and bon) showing two hearts (cardia bifida) [1]. Furthermore, mutant zebra fish (toh) lacking sphingosine-1-phosphate (S1P) transporter which is expressed in the YSL show two hearts [2], indicating the essential role for S1P-mediated signal in cardiac development. This is also supported by a S1p2 receptor mutant (mil) which exhibits two hearts [3]. However, it is still unclear how S1P released from YSL regulates CPC migration.
Copyright 2016, The Author(s).