Combined BMP-2 and FGF-4, but Neither Factor Alone, Induces Cardiogenesis in Non-Precardiac Embryonic Mesoderm

Abstract

Previous work in this laboratory has shown that endoderm cells in the heart forming region (HFR endoderm) of the chicken embryo induce terminal cardiac differentiation in explanted precardiac mesoderm cells. Immunostaining patterns indicating that HFR endoderm cells express Drosophila decapentaplegic (dpp)-like antigens prompted a degenerate polymerase chain reaction (PCR) screen to identify cDNAs in the dpp subgroup of the transforming growth factor-beta (TGF-beta) family. Among 50 clones of PCR products that have been sequenced, over half have identity with bone morphogenetic protein-2 (BMP-2). No other TGF-beta cDNAs have been detected, suggesting that BMP-2 is the major dpp subgroup protein synthesized by HFR endoderm cells. However, BMP-2 protein did not promote survival of either precardiac or non-precardiac mesoderm cells in culture. Whereas FGF-4 supports cardiogenesis in precardiac mesoderm, it did not induce cardiogenesis in nonprecardiac mesoderm, although explant viability was maintained. In contrast to the isolated effects of these growth factors, treatment of non-precardiac mesoderm with combined BMP-2 and FGF-4 induced cardiogenesis in the majority of explants, as revealed by the formation of a rhythmically contractile multicellular vesicle that expresses sarcomeric alpha-actin. These findings suggest that BMP-2 and FGF-4 possess respective differentiative and proliferative activities, the combination of which specifies cells to the cardiac lineage.

Inhibition of Wnt activity induces heart formation from posterior mesoderm

“…It has been reported by others that FGF can respecify posterior lateral mesoderm to form heart in combination with BMP-2 (Lough et al 1996;Ladd et al 1998). However, the lateral mesoderm in that work extended considerably closer to the heart-forming region, whereas the lateral mesoderm in our assay was located at the extreme posterior of the embryo (at 75%-100% streak length).…”

Geometric Control of Cardiomyogenic Induction in Human Pluripotent Stem Cells

“…Upon phosphorylation, these receptor-regulated (R)-Smads form complexes with Smad4, which are subsequently translocated to the nucleus to regulate activation of transcription factors, such as cardiac transcription factors Nkx-2.5, GATA-4, and Tbx factors (Massague and Chen 2000;Schlange, Andree et al 2000;Moustakas, Souchelnytskyi et al 2001;Attisano and Wrana 2002;Harvey 2002;Wakefield and Roberts 2002;Attisano and Labbe 2004;. FGF family proteins (FGF-2 and FGF-4) have been shown to support cardiomyocyte induction during embryonic development mainly by stimulating proliferation of mesodermal cells in vitro (Mima, Ueno et al 1995;Lough, Barron et al 1996;Schultheiss and Lassar 1997;Ladd, Yatskievych et al 1998;Barron, Gao et al 2000;Kawai, Takahashi et al 2004). During embryogenesis, these growth factors, originating from the anterior and lateral endoderm, synergize in a precise spatial and temporal program to support and induce cardiogenesis in neighboring precardiac mesoderm (Figure 1.2).…”

“…TGF-β1 and activin appear to have a similar effect in inducing cardiomyocyte differentiation in posterior epiblast tissue (including regions not fated to form heart) (Yatskievych, Ladd et al 1997;Ladd, Yatskievych et al 1998), but not in non-cardiogenic mesoderm (Schultheiss, Burch et al 1997;Ladd, Yatskievych et al 1998). Conversely, BMP-2 and -4, in combination with FGF-4, induce cardiac differentiation of non-cardiogenic mesoderm (Lough, Barron et al 1996;Schultheiss and Lassar 1997;Ladd, Yatskievych et al 1998;Barron, Gao et al 2000), but fail to support cardiogenesis in posterior epiblast. FGF-2 is expressed in both endoderm as well as myocardial cells of the developing embryo (Parlow, Bolender et al 1991;Sugi, Sasse et al 1993).…”

Extrinsic regulation of cardiomyocyte differentiation of embryonic stem cells

“…An example is, FGF-2 secreted by endoderm promote cardiac myogenesis [Sugi and Lough, 1995]. In addition, BMP and FGF-specific pathways interact to specify the cardiac lineage [Lough et al, 1996;Ladd et al, 1998]. Inactivation of FGFR-1 in mice dramatically affects the expression of several cardiac transcription factors with a consequent impairment on the expression of structural myocardial genes and contractile foci formation [Dell'Era et al, 2003].…”