Background: The cells of the mesencephalic trigeminal nucleus (MTN) are the proprioceptive sensory neurons that innervate the jaw closing muscles. These cells differentiate close to the two key signalling centres that influence the dorsal midbrain, the isthmus, which mediates its effects via FGF and WNT signalling and the roof plate, which is a major source of BMP signalling as well as WNT signalling.
Methods: In this study, we have set out to analyse the importance of FGF, WNT and BMP signalling for the development of the MTN. We have employed pharmacological inhibitors of these pathways in explant cultures as well as utilising the electroporation of inhibitory constructs in vivo in the chick embryo.
Results: We find that interfering with either FGF or WNT signalling has pronounced effects on MTN development whilst abrogation of BMP signalling has no effect. We show that treatment of explants with either FGF or WNT antagonists results in the generation of fewer MTN neurons and affects MTN axon extension and that inhibition of both these pathways has an additive effect. To complement these studies, we have used in vivo electroporation to inhibit BMP, FGF and WNT signalling within dorsal midbrain cells prior to, and during, their differentiation as MTN neurons. Again, we find that inhibition of BMP signalling has no effect on the development of MTN neurons. We additionally find that cells electroporated with inhibitory constructs for either FGF or WNT signalling can differentiate as MTN neurons suggesting that these pathways are not required cell intrinsically for the emergence of these neurons. Indeed, we also show that explants of dorsal mesencephalon lacking both the isthmus and roof plate can generate MTN neurons. However, we did find that inhibiting FGF or WNT signalling had consequences for MTN differentiation.
Conclusions: Our results suggest that the emergence of MTN neurons is an intrinsic property of the dorsal mesencephalon of gnathostomes, and that this population undergoes expansion, and maturation, along with the rest of the dorsal midbrain under the influence of FGF and WNT signalling.
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http://dx.doi.org/10.1186/s13064-017-0088-z | DOI Listing |
Development
January 2025
Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, 90033, USA.
The calvarial bones of the infant skull are linked by transient fibrous joints known as sutures and fontanelles, which are essential for skull compression during birth and expansion during postnatal brain growth. Genetic conditions caused by pathogenic variants in FGFR2, such as Apert, Pfeiffer, Crouzon syndromes, result in calvarial deformities due to premature suture fusion and a persistently open anterior fontanelle (AF). In this study we investigated how Fgfr2 regulates AF closure by leveraging mouse genetics and single-cell transcriptomics.
View Article and Find Full Text PDFCells
December 2024
Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 41345 Gothenburg, Sweden.
The human heart regenerates slowly through life, but how new cells are generated is mostly unknown. The atrioventricular junction (AVj) has been indicated as a potential stem cell niche region. Little is known about the protein composition of the human AVj.
View Article and Find Full Text PDFDev Biol
January 2025
Biology Department, Texas A&M University, College Station, TX, 7843-3258, USA. Electronic address:
During development of the vertebrate inner ear, sensory epithelia and neurons of the statoacoustic ganglion (SAG) arise from lineage-restricted progenitors that proliferate extensively before differentiating into mature post-mitotic cell types. Development of progenitors is regulated by Fgf, Wnt and Notch signaling, but how these pathways are coordinated to achieve an optimal balance of proliferation and differentiation is not well understood. Here we investigate the role in zebrafish of Foxm1, a transcription factor commonly associated with proliferation in developing tissues and tumors.
View Article and Find Full Text PDFThe formation of the vertebrate body involves the coordinated production of trunk tissues from progenitors located in the posterior of the embryo. Although in vitro models using pluripotent stem cells replicate aspects of this process, they lack crucial components, most notably the notochord-a defining feature of chordates that patterns surrounding tissues. Consequently, cell types dependent on notochord signals are absent from current models of human trunk formation.
View Article and Find Full Text PDFScience
December 2024
Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Severe lung injury causes airway basal stem cells to migrate and outcompete alveolar stem cells, resulting in dysplastic repair. We found that this "stem cell collision" generates an injury-induced tissue niche containing keratin 5 epithelial cells and plastic Pdgfra mesenchymal cells. Single-cell analysis revealed that the injury-induced niche is governed by mesenchymal proliferation and Notch signaling, which suppressed Wnt/Fgf signaling in the injured niche.
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