Effects of canonical Wnt signaling on dorso-ventral specification of the mouse telencephalon.
Wnt signaling is involved in numerous processes during vertebrate CNS development. In this study, we used conditional Cre/loxP system in mouse to ablate or activate beta-catenin in the telencephalon in two time windows: before and after the onset of neurogenesis. We show that beta-catenin mediated Wnt signals are required to maintain the molecular identity of the pallium. Inactivation of beta-catenin in the telencephalon before neurogenesis results in downregulated expression of dorsal markers Emx1, Emx2 and Ngn2, and in ectopic up-regulation of ventral markers Gsh2, Mash1 and Dlx2 in the pallium. In contrast, ablation of ss-catenin after the onset of cortical neurogenesis (E11.5) does not result in a dorso-ventral fate shift. In addition, activation of canonical Wnt signaling in the subpallium leads to a repression of ventral telencephalic cell identities as shown by the down-regulation of subpallial markers Dlx2, Nkx2.1, Gsh2, Olig2 and Mash1. This was accompanied with an expansion of dorsal identities ventrally as shown by the expanded expression domains of pallial markers Pax6 and Ngn2. Thus, our data suggest that canonical Wnt signals are involved in maintaining the identity of the pallium by controlling expression of dorsal markers and by suppressing ventral programs from being activated in pallial progenitor cells.
Backman
Mattias
M
Institute of Medical Microbiology and Centre for Molecular Biology and Neuroscience, University of Oslo, The National Hospital, 0027 Oslo, Norway.
Machon
Ondrej
O
Mygland
Line
L
van den Bout
Christiaan Johannes
CJ
Zhong
Weimin
W
Taketo
Makoto M
MM
Krauss
Stefan
S
D000818:Animals; D001483:Base Sequence; D019521:Body Patterning; D017931:DNA Primers; D047108:Embryonic Development / Q000235:genetics / Q000502:physiology; D005091:Exons; D005838:Genotype; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009474:Neurons / Q000166:cytology / Q000502:physiology; D016133:Polymerase Chain Reaction; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology; D013687:Telencephalon / Q000166:cytology / Q000196:embryology*; D051153:Wnt Proteins
D017931:DNA Primers; D036341:Intercellular Signaling Peptides and Proteins; D051153:Wnt Proteins