Movement and commitment of primitive streak precardiac cells during cardiogenesis

Abstract

Fate maps are required to address questions about the commitment and differentiation of precardiac cells. Here, we report a detailed study of the precardiac cells located at the level of the primitive streak, employing different experiments with a variety of techniques combining double transplantations, microinjections and immunocytochemistry. Most cells of the more rostral segments of the primitive streak were found to contribute cells to the endodermal layer, adjacent to precardiac mesodermal cells of the heart forming region whose provenance was in the immediately more caudal segments of the primitive streak. We established a close spatiotemporal relationship between the two cell layers and the expression of their specific cardiac markers (cNkx-2.5, Bmp2, Cripto, Usmaar, dHand, GATA4, Pitx2, Hex, Fgf8, AMHC1 and VMHC1). We also analyzed the ability of precardiac cells to differentiate when they are transplanted to ectopic locations or are subjected to the influence of the organizer. We propose that the precardiac cells of the primitive streak form at least two groups with different significance. One, regulated by mediation of the organizer, is located preferentially in the more rostral region of the primitive streak. It consists of the prospective cells of the endoderm layer, with a hierarchic pattern of expression of different genes characterized by its capacity for induction and regulation of a second group of cells. This second group is located preferentially in the more caudal segments, and is fated to form the precardiac mesoderm, whose differentiation would be characterized by the expression of various specific genes.

The Aplnr GPCR regulates myocardial progenitor development via a novel cell-non-autonomous, Gαi/o protein-independent pathway

“…Explant experiments, primarily done in the chick embryo, have yielded conflicting results on this question (reviewed in (Yutzey and Kirby, 2002)). Whereas some studies argue that cells exist in the early gastrula that are capable of forming cardiomyocytes regardless of later location in the embryo (Auda-Boucher et al, 2000; Lopez-Sanchez et al, 2009), others suggest that ultimate localization to the ALPM is sufficient for cardiac differentiation (Inagaki et al, 1993; Tam et al, 1997). A lack of mutants that specifically affect early myocardial progenitor development, and markers to isolate and characterize these cells, has hindered progress on this key question of early heart development.…”

Fate Mapping Identifies the Origin of SHF/AHF Progenitors in the Chick Primitive Streak

“…A number of studies have focused on identifying the embryonic origins of cardiogenic mesoderm in amniotes, particularly chicken and mouse embryos, which, similar to human, develop a four-chambered heart. However, the majority of these studies have involved fate mapping experiments in the chick due to their accessibility and ease of manipulation in ovo and ex ovo which makes them well suited to analyse early cardiac lineage and cell fate [2], [3], [4], [5].…”

Smarcd3b and Gata5 promote a cardiac progenitor fate in the zebrafish embryo

“…Montgomery et al, 1994;Schoenwolf and Garcia-Martinez, 1995). However, recent work suggests that presumptive cardiac progenitors from the pregastrula embryo do have the potential to form cardiomyocytes when placed in ectopic (normally non-cardiogenic) embryonic locations (Lopez-Sanchez et al, 2009). Studies in mouse and sea squirt Ciona intestinalis have shown that Mesp family basic helix-loop-helix transcription factors are essential for cardiac mesoderm formation (Kitajima et al, 2000;Satou et al, 2004), and indeed Mesps can promote cardiac differentiation of ES cells in vitro (Bondue et al, 2008).…”