Expression of the Wnt inhibitor Dickkopf-1 is required for the induction of neural markers in mouse embryonic stem cells differentiating in response to retinoic acid

Authors:
Verani R, Cappuccio I, Spinsanti P, Gradini R, Caruso A, Magnotti MC, Motolese M, Nicoletti F, Melchiorri D
In:
Source: J Neurochem
Publication Date: (2007)
Issue: 100(1): 242-50
Research Area:
Stem Cells
Cells used in publication:
Embryonic stem cell (ES), mouse
Species: mouse
Tissue Origin: embryo
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
Cultured mouse D3 embryonic stem (ES) cells differentiating into embryoid bodies (EBs) expressed several Wnt isoforms, nearly all isotypes of the Wnt receptor Frizzled and the Wnt/Dickkopf (Dkk) co-receptor low-density lipoprotein receptor-related protein (LRP) type 5. A 4-day treatment with retinoic acid (RA), which promoted neural differentiation of EBs, substantially increased the expression of the Wnt antagonist Dkk-1, and induced the synthesis of the Wnt/Dkk-1 co-receptor LRP6. Recombinant Dkk-1 applied to EBs behaved like RA in inducing the expression of the neural markers nestin and distal-less homeobox gene (Dlx-2). Recombinant Dkk-1 was able to inhibit the Wnt pathway, as shown by a reduction in nuclear beta-catenin levels. Remarkably, the antisense- or small interfering RNA-induced knockdown of Dkk-1 largely reduced the expression of Dlx-2, and the neuronal marker beta-III tubulin in EBs exposed to RA. These data suggest that induction of Dkk-1 and the ensuing inhibition of the canonical Wnt pathway is required for neural differentiation of ES cells.