Biochemical and Biophysical Research Communications
The canonical Wnt pathway directly regulates NRSF/REST expression in chick spinal cord
Section snippets
Materials and methods
cDNA cloning and expression vectors. Full-length cDNAs of mouse Wnt1, β-catenin, and dominant-negative Lef1 were inserted into the pCAGGS expression vector [18]. Mouse full-length Wnt1 cDNA was amplified by RT-PCR based on the published sequence. Mouse β-catenin and Lef1 were gifts from Drs. H. Shibuya and S. Nakagawa, respectively. Chick Wnt1 cDNA was a gift from Dr. M. Wassef and was used for in situ hybridization. Chick Cyclin D1 cDNA was obtained by RT-PCR based on the published sequence.
Expression of the NRSF, Wnt1, and Cyclin D1 genes in developing chick spinal cord
In a search of putative factors that prevent neural differentiation of actively dividing progenitor cells in the chick spinal cord, we found that NRSF is expressed in the VZ (Fig. 1A), as reported in the mouse [12]. Expression of NRSF was not observed in the MZ, where mature neurons reside (Fig. 1A).
Previous studies have identified that dorsal–ventral growth of the spinal cord is controlled by a gradient of Wnt signaling emanating from the dorsal midline of the spinal cord. Among several Wnts,
The canonical Wnt pathway and its direct target, NRSF
Neural stem cells are located in the VZ and actively proliferate to renew the pool of progenitor cells. In parallel, the progenitor pool generates postmitotic cells that leave the VZ and migrate to the MZ to differentiate into neurons [1].
Several factors are known to regulate the growth of the spinal progenitor pool. Wnt1 and Wnt3a are the pivotal factors controlling this process [7]. These Wnt molecules transduce their signals through the canonical Wnt pathway, in which the β-catenin and the
Acknowledgements
We thank Drs. H. Shibuya, S. Nakagawa, M. Wassef, and S. Kitazawa for plasmids and probes. This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas (C) from the Ministry of Education, Science, Sports and Culture of Japan (T.O.), and a Creative Basic Research grant from the Ministry of Education, Science, Sports and Culture of Japan (T.O.).
References (30)
- et al.
The wnt-1 (int-1) proto-oncogene is required for development of a large region of the mouse brain
Cell
(1990) - et al.
Control of beta-catenin phosphorylation/degradation by a dual-kinase mechanism
Cell
(2002) - et al.
Beta-catenin signals regulate cell growth and the balance between progenitor cell expansion and differentiation in the nervous system
Dev. Biol.
(2003) - et al.
REST: a mammalian silencer protein that restricts sodium channel gene expression to neurons
Cell
(1995) - et al.
Presenilin couples the paired phosphorylation of beta-catenin independent of axin: implications for beta-catenin activation in tumorigenesis
Cell
(2002) - et al.
APC mutations in sporadic medulloblastomas
Am. J. Pathol.
(2000) The development of neural stem cells
Nature
(2001)- et al.
Targeted disruption of the murine int-1 proto-oncogene resulting in severe abnormalities in midbrain and cerebellar development
Nature
(1990) - et al.
A local Wnt-3a signal is required for development of the mammalian hippocampus
Development
(2000) - et al.
Wnt signaling required for expansion of neural crest and CNS progenitors
Nature
(1997)