Primitive streak mesoderm-like cell lines expressing Pax-3 and Hox gene autoinducing activities.
Differentiating P19 embryonal carcinoma (EC) cells transiently express an endogenous activity capable of inducing Pax-3 expression in adjacent P19 stem cells (Pruitt, Development 116, 573-583, 1992). In the present study, expression of this activity in mesodermal cell lineages is demonstrated. First, expression of the mesodermal marker Brachyury correlates with expression of Pax-3-inducing activity. Second, the ability of leukemia inhibitory factor (LIF) to block mesoderm differentiation at two different points is demonstrated and correlated with the inhibition of Pax-3-inducing activity. Finally, two mesodermal cell lines that express Pax-3-inducing activity were derived from P19 EC cells. Each of these lines expresses high levels of the mesodermal marker Brachyury and high levels of Oct-3/4 (which is down-regulated at early times during mesoderm differentiation) suggesting that these lines are early mesodermal derivatives. Unlike EC or embryonic stem cell lines, each of the two mesodermal derivatives autoinduces Hox gene expression on aggregation even in the presence of LIF. Following aggregation, anterior-specific genes are expressed more rapidly than more posterior genes. These observations directly demonstrate the ability of murine mesodermal derivatives to autoinduce Hox gene expression in the absence of signals from other cell lineages. Similar to the Pax-3-inducing activity, signals from mesodermal cell lines were sufficient to induce HOX expression in adjacent P19 stem cells in cell mixing assays. These observations are consistent with the previous suggestion (Blum, M., Gaunt, S. J., Cho, K. W. Y., Steinbeisser, H., Blumberg, B., Bittner, D. and De Robertis, E. M. (1992) Cell 69, 1097-1106) that signals responsible for anterior-posterior organizer activity are localized to the anterior primitive streak mesoderm of the mouse embryo.
Pruitt
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SC
Roswell Park Cancer Institute, Department of Molecular and Cellular Biology, Buffalo, NY 14263.
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics*; D004627:Embryonic Induction / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D005775:Gastrula / Q000502:physiology*; D005786:Gene Expression Regulation / Q000235:genetics*; D005801:Genes, Homeobox / Q000235:genetics*; D005819:Genetic Markers; D005821:Genetic Techniques; D006131:Growth Inhibitors / Q000502:physiology; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000502:physiology; D008648:Mesoderm / Q000502:physiology*; D051379:Mice; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D014981:Xenopus; D029867:Xenopus Proteins
D004268:DNA-Binding Proteins; D005819:Genetic Markers; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; C489411:Pax3 protein, Xenopus; D014157:Transcription Factors; D029867:Xenopus Proteins; C068686:Pax3 protein, mouse