Involvement of BMP‐4/msx‐1 and FGF pathways in neural induction in the Xenopus embryo

Abstract

The msx homeodomain protein is a downstream transcription factor of the bone morphogenetic protein (BMP)- results of cell-lineage tracing experiments indicated that the neural cells were differentiated from the animal pole tissue where the excess RNA of either BMP-4 or Xmsx-1 was injected, whereas notochord was differentiated from the organizer mesoderm. Neural tissue differentiated from BMP-4-injected ectodermal cells strongly expressed posterior neural markers, such as hoxB9 and krox20, suggesting that the posterior neural cells differentiated regardless of the existence of the BMP signal. The introduction of a dominant-negative form of the fibroblast growth factor (FGF) receptor (XFD) into the ectodermal cells drastically reduced the expression of pan and posterior neural mark

BMP induction of cardiogenesis in P19 cells requires prior cell–cell interaction(s)

“…8). The upregulation of Msx-1 expression by BMPs has been documented by many investigators (Tucker et al, 1998;Ishimura et al, 2000;Alvarez Martinez et al, 2001;Binato et al, 2005), and Msx-1 has been shown to inhibit (Song et al, 1992;Lee et al, 2004;Hu et al, 2001) and in some cases reverse (Odelberg et al, 2000) terminal differentiation. Interestingly, one reported activity of Msx-1 is to alter the quality of cell-cell interactions toward a "less cohesive" phenotype (Lincecum et al, 1998).…”

“…The expression of Msx-1, a homeodomain transcription factor and a target of BMP4 signaling (Tucker, 1998;Ishimura, 2000;Alvarez Martinez et al, 2001;Binato et al, 2005), increases in P19-SI aggregates at about the same time as do BMP4 and GATA4 (Fig. 5e).…”

TGF-β Family Signaling in Neural and Neuronal Differentiation, Development, and Function

“…In particular, fibroblast growth factor (FGF) signaling down-regulates the expression of BMP-4 and BMP-7, and FGF together with insulin-like growth factor (IGF) activate the mitogen-activating protein (MAP) kinase cascade that regulates BMP signaling (Ishimura et al 2000;Wilson et al 2000). FGF and IGF obstruct BMP signal transduction by phosphorylating the linker region of Smad1 that blocks translocation of Smad to the nucleus (Pera et al 2003;Sapkota et al 2007).…”

Neural induction: old problem, new findings, yet more questions

“…This is because the injection of dominant-negative FGFR1 inhibits mesoderm formation and posterior axis development but not neural induction (Amaya et al, 1991;Cox and Hemmati-Brivanlou, 1995;Kroll and Amaya, 1996;Godsave and Durston, 1997;Holowacz and Sokol, 1999;Curran and Grainger, 2000;Ishimura et al, 2000;Ribisi et al, 2000;Pownall et al, 2003). However, it has been proposed that neural induction may involve FGFR4 rather than FGFR1 (Hongo et al, 1999;Hardcastle et al, 2000;Umbhauer et al, 2000), and a more recent study using a general inhibitor of FGFRs has uncovered a clear requirement for FGF signalling in neural induction in Xenopus (Delaune et al, 2005).…”