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Updated: Jun 26, 2026
Generating Retinal Injury Models in Xenopus Tadpoles
Published on: October 13, 2023
Xenopus NM23-X4 regulates retinal gliogenesis through interaction with p27Xic1
Toshiaki Mochizuki1, Aikaterini Bilitou, Caroline T Waters
1Hutchison/MRC Research Centre, Department of Oncology, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK. full-moon@umin.ac.jp
Background:
In Xenopus retinogenesis, p27Xic1, a Xenopus cyclin dependent kinase inhibitor, functions as a cell fate determinant in both gliogenesis and neurogenesis in a context dependent manner. This activity is essential for co-ordination of determination and cell cycle regulation. However, very little is known about the mechanism regulating the context dependent choice between gliogenesis versus neurogenesis.
Results:
We have identified NM23-X4, a NM23 family member, as a binding partner of p27Xic1. NM23-X4 is expressed at the periphery of the ciliary marginal zone of the Xenopus retina and the expression overlaps with p27Xic1 at the central side. Our in vivo functional analysis in Xenopus retina has shown that knockdown of NM23-X4 activates gliogenesis. Furthermore, co-overexpression of NM23-X4 with p27Xic1 results in the inhibition of p27Xic1-mediated gliogenesis, through direct interaction of NM23-X4 with the amino-terminal side of p27Xic1. This inhibitory effect on gliogenesis requires serine-150 and histidine-148, which correspond to the important residues for the kinase activities of NM23 family members.
Conclusion:
This study demonstrates that NM23-X4 functions as an inhibitor of p27Xic1-mediated gliogenesis in Xenopus retina and suggests that this activity contributes to the proper spatio-temporal regulation of gliogenesis.
Insights
NM23-X4 inhibits p27Xic1-mediated gliogenesis in Xenopus retina. This interaction is crucial for regulating cell fate determination during retinogenesis, ensuring proper spatio-temporal control of gliogenesis.
Area of Science:
- Developmental Biology
- Neuroscience
- Cell Biology
Background:
- p27Xic1 is a Xenopus cyclin-dependent kinase inhibitor crucial for retinogenesis, acting as a context-dependent cell fate determinant.
- The precise mechanisms governing p27Xic1's role in cell fate decisions between gliogenesis and neurogenesis remain largely unknown.
Purpose of the Study:
- To identify novel binding partners of p27Xic1 involved in regulating cell fate during Xenopus retinogenesis.
- To elucidate the functional role of NM23-X4 in the context-dependent regulation of gliogenesis versus neurogenesis.
Main Methods:
- Identification of p27Xic1 binding partners using biochemical assays.
- In vivo functional analysis in Xenopus retina through knockdown and co-overexpression studies.
- Investigation of specific protein-protein interactions and critical residues involved in functional inhibition.
Main Results:
- NM23-X4 was identified as a binding partner of p27Xic1 in the Xenopus retina.
- Knockdown of NM23-X4 led to the activation of gliogenesis.
- Co-overexpression of NM23-X4 inhibited p27Xic1-mediated gliogenesis, dependent on specific kinase residues (Serine-150, Histidine-148).
Conclusions:
- NM23-X4 acts as an inhibitor of p27Xic1-driven gliogenesis in the Xenopus retina.
- This inhibitory function of NM23-X4 contributes to the precise spatio-temporal regulation of gliogenesis during retinal development.
