Canonical Wnt signaling regulates Foxc1/2 expression in P19 cells.
FOXC1 and FOXC2 are forkhead/winged-helix transcription factors expressed in paraxial mesoderm and somites. Emphasizing the importance of FOXC1/2 during embryonic development, double-knockout mice lacking the alleles for both Foxc1 and Foxc2 failed to form segmented somites and undergo myogenesis. The present study aims to determine upstream factors that regulate Foxc1/2 expression during the differentiation of P19 cells into skeletal muscle. Previous work had shown that dominant-negative forms of beta-catenin, Gli2, and Meox1 could inhibit distinct stages of skeletal myogenesis in P19 cells. In the presence of a dominant-negative beta-catenin fusion protein, Foxc1/2 transcripts were not upregulated and neither were markers of somitogenesis/myogenesis, including Meox1, Pax3 and MyoD. Conversely, inhibition of GSK3 by LiCl or overexpression of activated beta-catenin in aggregated P19 cells resulted in enhancement of Foxc1/2 expression, indicating that FOX transcription may be under the control of Wnt signaling. Supporting this hypothesis, beta-catenin bound to conserved regions upstream of Foxc1 during P19 cell differentiation and drove transcription from this region in a promoter assay. In addition, ectopic expression of a dominant-negative Meox1 or Gli2 resulted in decreased Foxc1/2 transcript levels, correlating with inhibition of skeletal myogenesis. Overexpression of Gli2 was also sufficient to upregulate Foxc1/2 transcript levels and induce skeletal myogenesis. In summary, Foxc1/2 expression is dependent on a complex interplay from various signaling inputs from the Wnt and Shh pathways during early stages of in vitro skeletal myogenesis.
Savage
Josée
J
Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
Voronova
Anastassia
A
Mehta
Virja
V
Sendi-Mukasa
Flavia
F
Skerjanc
Ilona S
IS
D000818:Animals; D015152:Blotting, Northern; D018236:Carcinoma, Embryonal / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D005455:Fluorescent Antibody Technique; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D051153:Wnt Proteins / Q000502:physiology*; D000075746:Zinc Finger Protein Gli2; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D051858:Forkhead Transcription Factors; C112890:Foxc1 protein, mouse; C000618551:Gli2 protein, mouse; D018398:Homeodomain Proteins; D051741:Kruppel-Like Transcription Factors; C484871:Meox1 protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D051153:Wnt Proteins; D000075746:Zinc Finger Protein Gli2; D051176:beta Catenin; C082078:mesenchyme fork head 1 protein