Dale Frank Lab
Department of Biochemisty
Rappaport Faculty of Medicine
Technion - Israel Institute of Technology
The journey from EGG to FROG!
Meis3: A TALE-Family Homeobox Protein Controls Posterior Neural Cell Fates in Vertebrates
A. Over-expression of Meis3 protein INHIBITS FOREBRAIN, while ENHANCING HINDBRAIN cell fates.
B. Meis3 protein knock down INHIBITS HINDBRAIN, PRIMARY NEURON & NEURAL CREST fates, while EXPANDING the FOREBRAIN.
C. Meis3 Protein acts downstream to mesodermal Wnt3a protein to caudalize the nervous system.
Ectopic Meis3 Expression
Meis3 protein restores posterior neural cell fates in the absence of canonical Wnt signaling.
Left Panel: Morphology of mid-late neurula embryos (a) injected at the one-cell stage with either Wnt3a Morpholino (MO) (b), or Meis3 mRNA (c), or doubly-injected with both (d). Neural plate folding and convergence extension-elongation is strongly-inhibited in Wnt3a morphant embryos (b); Meis3 co-expression rescued this phenotype (d). All embryos are viewed dorsally, and oriented with anterior at the top, posterior at the bottom.
Right Panel: In situ hybridization of mid-late neurula embryos (a,e,i,m,q) injected at the one-cell stage with either Wnt3a-MO (b,f,j,n,r), or separately with Meis3 mRNA (d,h,l,p,t) or doubly-injected with both (c,g,k,o,s). Anterior-forebrain-specific XAnf1 expression is posteriorly expanded in Wnt3a-morphants (b), and suppressed by Meis3 co-expression (c,d). Expression of the posterior neural markers Krox20 (hindbrain), HoxB3 (hindbrain), N-Tub (primary neuron) and FoxD3 (neural crest) is inhibited in Wnt3a-morphants (f,j,n,r), but rescued by Meis3 co-expression (g,k,o,s). All embryos are viewed dorsally, and oriented with anterior at the top, posterior at the bottom.