Post-transcriptional Modulation of Sphingosine-1-Phosphate Receptor 1 by miR-19a Affects Cardiovascular Development in Zebrafish

Abstract

Sphingosine-1-phosphate is a bioactive lipid and a signaling molecule integrated into many physiological systems such as differentiation, proliferation and migration. In mammals S1P acts through binding to a family of five trans-membrane, G-protein coupled receptors (S1PRs) whose complex role has not been completely elucidated. In this study we use zebrafish, in which seven s1prs have been identified, to investigate the role of s1pr1. In mammals S1PR1 is the most highly expressed S1P receptor in the developing heart and regulates vascular development, but in zebrafish the data concerning its role are contradictory. Here we show that overexpression of zebrafish s1pr1 affects both vascular and cardiac development. Moreover we demonstrate that s1pr1 expression is strongly repressed by miR-19a during the early phases of zebrafish development. In line with this observation and with a recent study showing that miR-19a is downregulated in a zebrafish Holt-Oram model, we now demonstrate that s1pr1 is upregulated in heartstring hearts. Next we investigated whether defects induced by s1pr1 upregulation might contribute to the morphological alterations caused by Tbx5 depletion. We show that downregulation of s1pr1 is able to partially rescue cardiac and fin defects induced by Tbx5 depletion. Taken together, these data support a role for s1pr1 in zebrafish cardiovascular development, suggest the involvement of this receptor in the Tbx5 regulatory circuitry, and further support the crucial role of microRNAs in early phase of zebrafish development.

Sphingolipids in the Heart: From Cradle to Grave

“…In Zebrafish, mutations in s1pr2, but not any of the other S1P receptors, led to cardia bifida or formation of two laterally positioned hearts (22) (Summarized in Figure 1). This phenotype was also observed in multiple studies with a spns2 mutant or overexpression of s1pr1 (22)(23)(24)(25)(26)(27)(28)(29). In mice, conditional knockout (KO) of S1PR1 caused embryonic lethality due to ventricular non-compaction, ventricular septal defects, absence of normal increase in the number of cardiomyocytes and decreased myofibril organization (28).…”

“…At later developmental stages, knockdown of the zebrafish gene homolog to s1pr1 caused an improperly looped heart (30,31). Another study showed that an s1pr1 morpholino in zebrafish affected heart valve orientation, an indicator of incorrect looping (28). During the looping process, precursors of cardiac valves-endocardial cushioning (EC) and atrioventricular canal (AV)-are also formed.…”

“…This phenotype was also observed in multiple studies with a spns2 mutant or overexpression of s1pr1 ( 22 – 29 ). In mice, conditional knockout (KO) of S1PR1 caused embryonic lethality due to ventricular non-compaction, ventricular septal defects, absence of normal increase in the number of cardiomyocytes and decreased myofibril organization ( 28 ). These studies suggest S1P signaling components S1PR1, S1PR2, and Spns2 are necessary for cardiomyocyte expansion and myocardial precursor migration to the ventral midline of the embryo where they develop into the primitive heart tube.…”

Bioactive Lipid Signaling in Cardiovascular Disease, Development, and Regeneration

“…s1pr1 levels are normally suppressed by microRNA (miR)-19a, and when levels of this microRNA are decreased, higher s1pr1 expression causes impaired cardiac looping, abnormal chamber shapes, and downregulation of cardiac precursor genes. s1pr1 upregulation appears to mediate the detrimental effects on cardiac and fin development normally caused by T-box transcription factor 5 ((Tbx5) and subsequent miR-19a) depletion [ 249 ]. In mice, the situation appears to be much simpler, as shown by a recent report that utilized Cre-mediated conditional knockout of the S1P receptor 1 in developing embryos.…”

The pervasive role of microRNAs in arrhythmia: animal models and novel discoveries

“…In zebrafish, cardiac defects generated by Tbx5 depletion can be partially reverted by modulation of miR-19a, a member of this cluster, in line with a role of this miRNA as Tbx5 functional effector. Furthermore, miR-19a is able to affect heart rate control in Holt-Oram syndrome [HOS] fish by targeting the Sphingosine-1-Phosphate Receptor 1 which is highly expressed in mammalian cardiomyocytes and implicated in numerous cardiovascular processes [32]. Moreover miR-17-92 cluster has been also shown to directly repress genes, such as SHOX2 and TBX3, that are required for sinoatrial node development while miR-1 also targets the zinc finger homeobox 3 gene (ZFHX3) which is another important AF susceptibility-conferring gene [33][34][35].…”