Microglia Proliferation Is Controlled by P2X7 Receptors in a Pannexin-1-Independent Manner during Early Embryonic Spinal Cord Invasion

During metanephric development, non-polarized mesenchymal cells are induced to form the epithelial structures of the nephron following interaction with extracellular matrix proteins and factors produced by the inducing tissue, ureteric bud. This induction can occur in a transfilter organ culture system where it can also be produced by heterologous cells such as the embryonic spinal cord. We found that when embryonic mesenchyme was induced in vitro and in vivo, many of the cells surrounding the new epithelium showed morphological evidence of programmed cell death (apoptosis) such as condensed nuclei, fragmented cytoplasm, and cell shrinking. A biochemical correlate of apoptosis is the transcriptional activation of a calcium-sensitive endonuclease. Indeed, DNA isolated from uninduced mesenchyme showed progressive degradation, a process that was prevented by treatment with actinomycin-D or cycloheximide and by buffering intracellular calcium. These results demonstrate that the metanephric mesenchyme is programmed for apoptosis. Incubation of mesenchyme with a heterologous inducer, embryonic spinal cord prevented this DNA degradation. To investigate the mechanism by which inducers prevented apoptosis we tested the effects of protein kinase C modulators on this process. Phorbol esters mimicked the effects of the inducer and staurosporine, an inhibitor of this protein kinase, prevented the effect of the inducer. EGF also prevented DNA degradation but did not lead to differentiation. These results demonstrate that conversion of mesenchyme to epithelial requires at least two steps, rescue of the mesenchyme from apoptosis and induction of differentiation.

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Olig2-positive progenitors in the embryonic spinal cord give rise not only to motoneurons and oligodendrocytes, but also to a subset of astrocytes and ependymal cells

Developmental Biology ◽

10.1016/j.ydbio.2006.02.029 ◽

2006 ◽

Vol 293 (2) ◽

pp. 358-369 ◽

Cited By ~ 108

Author(s):

Noritaka Masahira ◽

Hirohide Takebayashi ◽

Katsuhiko Ono ◽

Keisuke Watanabe ◽

Lei Ding ◽

...

Keyword(s):

Spinal Cord ◽

Ependymal Cells ◽

Embryonic Spinal Cord

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Distinctive structural and cytoskeletal properties of the long-surviving neurons in cell cultures of embryonic spinal cord

Neuroscience ◽

10.1016/0306-4522(85)90174-5 ◽

1985 ◽

Vol 14 (1) ◽

pp. 207-224 ◽

Cited By ~ 3

Author(s):

P. Debbage

Keyword(s):

Spinal Cord ◽

Cell Cultures ◽

Embryonic Spinal Cord

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Role of BMPs in controlling the spatial and temporal origin of GFAP astrocytes in the embryonic spinal cord

Developmental Biology ◽

10.1016/j.ydbio.2010.05.017 ◽

2010 ◽

Vol 344 (2) ◽

pp. 611-620 ◽

Cited By ~ 11

Author(s):

Eric Agius ◽

Yann Decker ◽

Chadi Soukkarieh ◽

Cathy Soula ◽

Philippe Cochard

Keyword(s):

Spinal Cord ◽

Embryonic Spinal Cord

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Functional Coupling between the P2X7 Receptor and Pannexin-1 Channel in Rat Trigeminal Ganglion Neurons

International Journal of Molecular Sciences ◽

10.3390/ijms22115978 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5978

Author(s):

Hiroyuki Inoue ◽

Hidetaka Kuroda ◽

Wataru Ofusa ◽

Sadao Oyama ◽

Maki Kimura ◽

...

Keyword(s):

Trigeminal Ganglion ◽

P2x7 Receptor ◽

P2x Receptor ◽

Functional Coupling ◽

Dependent Manner ◽

High Concentration ◽

Receptor Antagonists ◽

P2x7 Receptors ◽

Pannexin 1 ◽

Ganglion Neurons

The ionotropic P2X receptor, P2X7, is believed to regulate and/or generate nociceptive pain, and pain in several neuropathological diseases. Although there is a known relationship between P2X7 receptor activity and pain sensing, its detailed functional properties in trigeminal ganglion (TG) neurons remains unclear. We examined the electrophysiological and pharmacological characteristics of the P2X7 receptor and its functional coupling with other P2X receptors and pannexin-1 (PANX1) channels in primary cultured rat TG neurons, using whole-cell patch-clamp recordings. Application of ATP and Bz-ATP induced long-lasting biphasic inward currents that were more sensitive to extracellular Bz-ATP than ATP, indicating that the current was carried by P2X7 receptors. While the biphasic current densities of the first and second components were increased by Bz-ATP in a concentration dependent manner; current duration was only affected in the second component. These currents were significantly inhibited by P2X7 receptor antagonists, while only the second component was inhibited by P2X1, 3, and 4 receptor antagonists, PANX1 channel inhibitors, and extracellular ATPase. Taken together, our data suggests that autocrine or paracrine signaling via the P2X7-PANX1-P2X receptor/channel complex may play important roles in several pain sensing pathways via long-lasting neuronal activity driven by extracellular high-concentration ATP following tissue damage in the orofacial area.

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Natural loss of function of ephrin-B3 shapes spinal flight circuitry in birds

Science Advances ◽

10.1126/sciadv.abg5968 ◽

2021 ◽

Vol 7 (24) ◽

pp. eabg5968

Author(s):

Baruch Haimson ◽

Oren Meir ◽

Reut Sudakevitz-Merzbach ◽

Gerard Elberg ◽

Samantha Friedrich ◽

...

Keyword(s):

Spinal Cord ◽

Mutant Mouse ◽

Loss Of Function ◽

Dorsal Midline ◽

Roof Plate ◽

Embryonic Spinal Cord ◽

Guidance Molecule

Flight in birds evolved through patterning of the wings from forelimbs and transition from alternating gait to synchronous flapping. In mammals, the spinal midline guidance molecule ephrin-B3 instructs the wiring that enables limb alternation, and its deletion leads to synchronous hopping gait. Here, we show that the ephrin-B3 protein in birds lacks several motifs present in other vertebrates, diminishing its affinity for the EphA4 receptor. The avian ephrin-B3 gene lacks an enhancer that drives midline expression and is missing in galliforms. The morphology and wiring at brachial levels of the chicken embryonic spinal cord resemble those of ephrin-B3 null mice. Dorsal midline decussation, evident in the mutant mouse, is apparent at the chick brachial level and is prevented by expression of exogenous ephrin-B3 at the roof plate. Our findings support a role for loss of ephrin-B3 function in shaping the avian brachial spinal cord circuitry and facilitating synchronous wing flapping.

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