Zebrafish cardiac development requires a conserved secondary heart field

Abstract

SUMMARYThe secondary heart field is a conserved developmental domain in avian and mammalian embryos that contributes myocardium and smooth muscle to the definitive cardiac arterial pole. This field is part of the overall heart field and its myocardial component has been fate mapped from the epiblast to the heart in both mammals and birds. In this study we show that the population that gives rise to the arterial pole of the zebrafish can be traced from the epiblast, is a discrete part of the mesodermal heart field, and contributes myocardium after initial heart tube formation, giving rise to both smooth muscle and myocardium. We also show that Isl1, a transcription factor associated with undifferentiated cells in the secondary heart field in other species, is active in this field. Furthermore, Bmp signaling promotes myocardial differentiation from the arterial pole progenitor population, whereas inhibiting Smad1/5/8 phosphorylation leads to reduced myocardial differentiation with subsequent increased smooth muscle differentiation. Molecular pathways required for secondary heart field development are conserved in teleosts, as we demonstrate that the transcription factor Tbx1 and the Sonic hedgehog pathway are necessary for normal development of the zebrafish arterial pole.

Utilizing Zebrafish to Understand Second Heart Field Development

“…25.1c; [7]). Finally, DiI labeling has shown that the SHF resides adjacent to the heart tube in older embryos: pericardial cells just outside the outflow tract at 24 hpf move into the arterial pole at later stages [7]. The SHF has also been identified using Cre-mediated lineage tracing.…”

“…Prior to gastrulation, arterial pole progenitors are found adjacent to ventricular progenitors at the embryonic margin ( Fig. 25.1c; [7]). After [5].…”

“…(b) Green-to-red conversion of photoconvertible proteins expressed in differentiated cardiomyocytes at 24 hpf, followed by imaging at 48 hpf, reveals newly added green cardiomyocytes in the outflow tract [6]. (c) Fate mapping in the late blastula shows that outflow tract progenitors (purple) are located close to the margin, adjacent to ventricular progenitors (red), and separate from atrial progenitors (yellow) [7]. In the early gastrula, outflow tract progenitors are located in a medial cranial portion of the ALPM [7] gastrulation, arterial pole progenitors map to a medial cranial region next to the FHF in the anterior lateral plate mesoderm (ALPM) ( Fig.…”

“…(c) Fate mapping in the late blastula shows that outflow tract progenitors (purple) are located close to the margin, adjacent to ventricular progenitors (red), and separate from atrial progenitors (yellow) [7]. In the early gastrula, outflow tract progenitors are located in a medial cranial portion of the ALPM [7] gastrulation, arterial pole progenitors map to a medial cranial region next to the FHF in the anterior lateral plate mesoderm (ALPM) ( Fig. 25.1c; [7]).…”

“…In the early gastrula, outflow tract progenitors are located in a medial cranial portion of the ALPM [7] gastrulation, arterial pole progenitors map to a medial cranial region next to the FHF in the anterior lateral plate mesoderm (ALPM) ( Fig. 25.1c; [7]). Finally, DiI labeling has shown that the SHF resides adjacent to the heart tube in older embryos: pericardial cells just outside the outflow tract at 24 hpf move into the arterial pole at later stages [7].…”