Retinoic acid suppresses the canonical Wnt signaling pathway in embryonic stem cells and activates the noncanonical Wnt signaling pathway.

TitleRetinoic acid suppresses the canonical Wnt signaling pathway in embryonic stem cells and activates the noncanonical Wnt signaling pathway.
Publication TypeJournal Article
Year of Publication2014
AuthorsOsei-Sarfo K, Gudas LJ
JournalStem Cells
Volume32
Issue8
Pagination2061-71
Date Published2014 Aug
ISSN1549-4918
KeywordsAnimals, Blotting, Western, Cell Differentiation, Cell Lineage, Chromatin Immunoprecipitation, Embryonic Stem Cells, Mice, Mice, Knockout, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, Tretinoin, Wnt Signaling Pathway
Abstract

Embryonic stem cells (ESCs) have both the ability to self-renew and to differentiate into various cell lineages. Retinoic acid (RA), a metabolite of Vitamin A, has a critical function in initiating lineage differentiation of ESCs through binding to the retinoic acid receptors. Additionally, the Wnt signaling pathway plays a role in pluripotency and differentiation, depending on the activation status of the canonical and noncanonical pathways. The activation of the canonical Wnt signaling pathway, which requires the nuclear accumulation of β-catenin and its interaction with Tcf1/Lef at Wnt response elements, is involved in ESC stemness maintenance. The noncanonical Wnt signaling pathway, through actions of Tcf3, can antagonize the canonical pathway. We show that RA activates the noncanonical Wnt signaling pathway, while concomitantly inhibiting the canonical pathway. RA increases the expression of ligands and receptors of the noncanonical Wnt pathway (Wnt 5a, 7a, Fzd2 and Fzd6), downstream signaling, and Tcf3 expression. RA reduces the phosphorylated β-catenin levels by fourfold, although total β-catenin levels do not change. We show that RA signaling increases the dissociation of Tcf1 and the association of Tcf3 at promoters of genes that regulate stemness (e.g., NR5A2, Lrh-1) or differentiation (e.g. Cyr61, Zic5). Knockdown of Tcf3 increases Lrh-1 transcript levels in mESCs and prevents the RA-associated, fourfold increase in Zic5, indicating that RA requires Tcf3 to effect changes in Zic5 levels. We demonstrate a novel role for RA in altering the activation of these two Wnt signaling pathways and show that Tcf3 mediates some actions of RA during differentiation.

DOI10.1002/stem.1706
Alternate JournalStem Cells
PubMed ID24648413
PubMed Central IDPMC4106995
Grant ListT32 CA062948 / CA / NCI NIH HHS / United States
NIAAA R01AA018332 / / PHS HHS / United States
R01 AA018332 / AA / NIAAA NIH HHS / United States
NCI T32 CA062948 / CA / NCI NIH HHS / United States
NCI R01 CA43796 / CA / NCI NIH HHS / United States
R01 CA043796 / CA / NCI NIH HHS / United States