Regulated expression of Wnt family members during neuroectodermal differentiation of P19 embryonal carcinoma cells: overexpression of Wnt-1 perturbs normal differentiation-specific properties.
The P19 embryonal carcinoma (EC) cell line represents a useful model system for analysis of neural development and differentiation processes that are difficult to study in mammalian embryos. Since many members of the Wnt family of signaling molecules are expressed in the developing as well as adult nervous system, we have examined expression of these genes in P19 cells. Analysis of the mRNA accumulation profiles for Wnt genes during retinoic acid (RA)-induced neural differentiation of P19 cells showed that nine Wnt family members were expressed in a regulated manner during this process. Most were induced by RA treatment, and some were also expressed in undifferentiated P19 cells. Since Wnt-1 is not expressed in undifferentiated P19 cells but is induced during neuroectodermal differentiation we have generated P19 cell lines that overexpress Wnt-1 in the absence of RA treatment, in order to address the role of Wnt-1 in P19 differentiation. In the presence of ectopic Wnt-1, expression of other endogenous Wnt genes, which serve as early differentiation markers in this system, were induced without RA, which is normally required for appearance of these gene products. Furthermore, ectopic expression of Wnt-1 resulted in a loss of SSEA-1 antigen expression, a marker of undifferentiated P19 cells. Similarly to the parental cell line, addition of RA to P19 cells overexpressing Wnt-1 induced the neuroectodermal pathway, but expression of cell type-specific markers such as MASH-1, HNK-1, and GAP-43 was diminished and the morphology of neuronal processes, stained with an antibody to neurofilament, was abnormal. These data suggest that Wnt-1 itself can induce some aspects of early neuroectodermal differentiation and, furthermore, that the correct timing of Wnt-1 expression is necessary for proper RA-induced expression of the neural phenotype.
SUGEN, Inc., Redwood City, California 94063.
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Smolich
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Papkoff
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D015152:Blotting, Northern; D018236:Carcinoma, Embryonal; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004475:Ectoderm / Q000166:cytology* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D051379:Mice; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000096:biosynthesis*; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D014157:Transcription Factors / Q000096:biosynthesis; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051153:Wnt Proteins; D051155:Wnt1 Protein; D029961:Zebrafish Proteins
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D014212:Tretinoin; D051153:Wnt Proteins; D051155:Wnt1 Protein; D029961:Zebrafish Proteins; C499317:Ascl1 protein, mouse; C495246:Wnt1 protein, mouse