Dorsal differentiation of neural plate cells induced by BMP-mediated signals from epidermal ectoderm

Abstract

The cellular interactions that control the differentiation of dorsal cell types from neural progenitors have been examined in neural plate explants. Certain genes that are expressed in the dorsal neural tube are initially expressed uniformly within the neural plate and appear to achieve their dorsal restriction through a Sonic hedgehog (SHH)-mediated repressive signal from the notochord. The acquisition of definitive dorsal cell fates, however, requires a contact-dependent signal from the epidermal ectoderm. BMP4 and BMP7 are expressed in the epidermal ectoderm, and both proteins mimic its inductive activity. BMP4 and a related gene, DSL1, are subsequently expressed by cells in the dorsal neural tube. The differentiation of dorsal cell types, therefore, appears to be initiated at the neural plate stage and to involve the opponent activities of a BMP-mediated dorsalizing signal from the epidermal ectoderm and a SHH-mediated ventralizing signal from the notochord.

Endogenous bone morphogenetic protein antagonists regulate mammalian neural crest generation and survival

“…BMPs have been hypothesized to be key factors in NCC induction based on their expression in tissues that induce NCCs, the ability of recombinant BMP to mimic this inductive activity, and the consequences of reducing BMP activity (Liem et al, 1995;Selleck et al, 1998). In support of this hypothesis, mouse and zebrafish mutants lacking Bmp2 display severe deficiencies of NCCs (Kanzler et al, 2000).…”

In ovo electroporation of Crim1 in the developing chick spinal cord

“…This requirement is partly mediated by members of the transforming growth factor-beta (TGF-␤) superfamily, particularly the bone morphogenetic protein (BMP) and closely related growth and differentiation factor (GDF) subfamilies (Lee and Jessell, 1999). Several BMPs/GDFs are secreted from the lateral margin of the neural plate, and subsequently by the overlying ectoderm and dorsal roof plate (Basler et al, 1993;Liem et al, 1995Liem et al, , 1997Lee et al, 1998).…”

“…BMPs are potent inhibitors of ventral cell-type formation and can direct ventral tissues to adopt a dorsal fate (Basler et al, 1993;Arkell and Beddington, 1997). Conversely, SHH can ventralize dorsal regions of the neural tube (Liem et al, 1995). It has become apparent that there are specific mechanisms to restrict and regulate the actions of BMPs and SHH.…”

BMP controls nitric oxide-mediated regulation of cell numbers in the developing neural tube

“…Compelling evidence makes the extracellular factor, bone morphogenetic protein (BMP), which is expressed in the dorsal NT along the A-P axis at these embryonic stages, 8 an attractive candidate. BMPs constitute a subclass of the transforming growth factor-b superfamily of soluble proteins.…”

“…14 Initially, BMPs are expressed at high levels in non-neural ectoderm and later also in the roof plate of the NT. 8,15,16 A BMP activity gradient across the D-V axis of the NT induces dorsal identity markers indicative of neural crest or dorsal interneuron precursors. [17][18][19][20] BMPs also induce apoptosis in the early developing central nervous system (CNS), [16][17][18][19][20][21] neuronal differentiation in mid-gestation of CNS precursors 22,23 and glial differentiation in late embryonic or adult CNS precursors.…”