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Neural Induction (neural + induction)
Selected AbstractsAnterior,posterior patterning of neural differentiated embryonic stem cells by canonical Wnts, Fgfs, Bmp4 and their respective antagonistsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2009Marijke Hendrickx Embryonic stem (ES) cells are pluripotent and can differentiate into every cell type of the body. Next to their potential in regenerative medicine, they are excellent tools to study embryonic development. In this work the processes of neural induction and neural patterning along the antero-posterior (A/P) body axis are studied and evidence suggests a two step mechanism for these events. First, neural induction occurs by default in the primitive ectoderm, forming anterior neural tissue and thereafter, a series of factors can posteriorize this anterior neurectoderm. In a gain-of-function/loss-of-function approach using mouse ES cells, we show that Fgf2 has the strongest caudalizing potential of all Fgfs tested. Furthermore, Bmp4 and Wnt3a, but not Wnt1, can caudalize the neurectodermal cells. The effect of the antagonists of these factors was also examined and though Dkk1 and Noggin clearly have an effect that opposes that of Wnt3a and Bmp4 respectively, they fail to anteriorize the neurectoderm. The patterning effect of SU5402, an Fgf receptor inhibitor, was rather limited. These data confirm that in the mouse, two steps are involved in neural patterning and we show that while Fgf4, Fgf8 and Wnt1 have no strong patterning effect, Fgf2, Wnt3a and Bmp4 are strong posteriorizing factors. [source] Involvement of BMP-4/msx-1 and FGF pathways in neural induction in the Xenopus embryoDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2000Akihiko Ishimura The msx homeodomain protein is a downstream transcription factor of the bone morphogenetic protein (BMP)-4 signal and a key regulator for neural tissue differentiation. Xmsx-1 antagonizes the dorsal expression of noggin and cerberus, as revealed by in situ hybridization and reverse transcription,polymerase chain reaction assays. In animal cap explants, Xmsx-1 and BMP-4 inhibit the neural tissue differentiation induced by noggin or cerberus. A loss-of-function study using the Xmsx-1/VP-16 fusion construct indicated that neural tissue formation was directly induced by the injection of fusion ribonucleic acid, although the expression of neural cell adhesion molecule (N-CAM) in the cap was less than that in the cap injected with tBR or noggin. In contrast to the single cap assay, unexpectedly, both BMP-4 and Xmsx-1 failed to inhibit neurulation in the ectodermal explants to which the organizer mesoderm was attached. The 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 markers (N-CAM and hoxB-9) if co-injected with BMP-4 RNA, although XFD alone at the same dose did not shut down the expression of N-CAM in the combination explants. Therefore, it is proposed that an FGF-related molecule was involved in the direct induction of posterior neural tissue in the inducing signals from the organizer mesoderm in vivo. [source] Cloning and characterization of voltage-gated calcium channel alpha1 subunits in Xenopus laevis during developmentDEVELOPMENTAL DYNAMICS, Issue 11 2009Brittany B. Lewis Abstract Voltage-gated calcium channels play a critical role in regulating the Ca2+ activity that mediates many aspects of neural development, including neural induction, neurotransmitter phenotype specification, and neurite outgrowth. Using Xenopus laevis embryos, we describe the spatial and temporal expression patterns during development of the 10 pore-forming alpha1 subunits that define the channels' kinetic properties. In situ hybridization indicates that CaV1.2, CaV2.1, CaV2.2, and CaV3.2 are expressed during neurula stages throughout the neural tube. These, along with CaV1.3 and CaV2.3, beginning at early tail bud stages, and CaV3.1 at late tail bud stages, are detected in complex patterns within the brain and spinal cord through swimming tadpole stages. Additional expression of various alpha1 subunits was observed in the cranial ganglia, retina, olfactory epithelium, pineal gland, and heart. The unique expression patterns for the different alpha1 subunits suggests they are under precise spatial and temporal regulation and are serving specific functions during embryonic development. Developmental Dynamics 238:2891,2902, 2009. © 2009 Wiley-Liss, Inc. [source] Analysis of neural potential of human umbilical cord blood,derived multipotent mesenchymal stem cells in response to a range of neurogenic stimuliJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2008Isabel Zwart Abstract We investigated the neurogenic potential of full-term human umbilical cord blood (hUCB),derived multipotent mesenchymal stem cells (MSCs) in response to neural induction media or coculture with rat neural cells. Phenotypic and functional changes were assessed by immunocytochemistry, RT-PCR, and whole-cell patch-clamp recordings. Naive MSCs expressed both mesodermal and ectodermal markers prior to neural induction. Exposure to retinoic acid, basic fibroblast growth factor, or cyclic adenosine monophosphate (cAMP) did not stimulate neural morphology, whereas exposure to dibutyryl cAMP and 3-isobutyl-1-methylxanthine stimulated a neuron-like morphology but also appeared to be cytotoxic. All protocols stimulated increases in expression of the neural precursor marker nestin, but expression of mature neuronal or glial markers MAP2 and GFAP was not observed. Nestin expression increases were serum level dependent. Electrophysiological properties of MSCs were studied with whole-cell patch-clamp recordings. The MSCs possessed no ionic currents typical of neurons before or after neural induction protocols. Coculture of hUCB-derived MSCs and rat neural cells induced some MSCs to adopt an astrocyte-like morphology and express GFAP protein and mRNA. Our data suggest hUCB-derived MSCs do not transdifferentiate into mature functioning neurons in response to the above neurogenic protocols; however, coculture with rat neural cells led to a minority adopting an astrocyte-like phenotype. © 2008 Wiley-Liss, Inc. [source] | ||||||||||