Differences in gene expression between wild type and Hoxa1 knockout embryonic stem cells after retinoic acid treatment or leukemia inhibitory factor (LIF) removal.
Homeobox (Hox) genes encode a family of transcription factors that regulate embryonic patterning and organogenesis. In embryos, alterations of the normal pattern of Hox gene expression result in homeotic transformations and malformations. Disruption of the Hoxa1 gene, the most 3' member of the Hoxa cluster and a retinoic acid (RA) direct target gene, results in abnormal ossification of the skull, hindbrain, and inner ear deficiencies, and neonatal death. We have generated Hoxa1(-/-) embryonic stem (ES) cells (named Hoxa1-15) from Hoxa1(-/-) mutant blastocysts to study the Hoxa1 signaling pathway. We have characterized in detail these Hoxa1(-/-) ES cells by performing microarray analyses, and by this technique we have identified a number of putative Hoxa-1 target genes, including genes involved in bone development (e.g. Col1a1, Postn/Osf2, and the bone sialoprotein gene or BSP), genes that are expressed in the developing brain (e.g. Nnat, Wnt3a, BDNF, RhoB, and Gbx2), and genes involved in various cellular processes (e.g. M-RAS, Sox17, Cdkn2b, LamA1, Col4a1, Foxa2, Foxq1, Klf5, and Igf2). Cell proliferation assays and Northern blot analyses of a number of ES cell markers (e.g. Rex1, Oct3/4, Fgf4, and Bmp4) suggest that the Hoxa1 protein plays a role in the inhibition of cell proliferation by RA in ES cells. Additionally, Hoxa1(-/-) ES cells express high levels of various endodermal markers, including Gata4 and Dab2, and express much less Fgf5 after leukemia inhibitory factor (LIF) withdrawal. Finally, we propose a model in which the Hoxa1 protein mediates repression of endodermal differentiation while promoting expression of ectodermal and mesodermal characteristics.
Martinez-Ceballos
Eduardo
E
Department of Pharmacology, Weill Medical College of Cornell University, New York, New York 10021, USA.
Chambon
Pierre
P
Gudas
Lorraine J
LJ
D000818:Animals; D015415:Biomarkers; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D001921:Brain / Q000196:embryology / Q000378:metabolism; D055511:CCN Intercellular Signaling Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D051379:Mice; D008810:Mice, Inbred C57BL; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism; D050814:Octamer Transcription Factor-3; D020411:Oligonucleotide Array Sequence Analysis; D015513:Oncogene Proteins / Q000378:metabolism; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011506:Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D013234:Stem Cells / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism*; D000099261:Homeobox A1 Protein
D015415:Biomarkers; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D055511:CCN Intercellular Signaling Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins; D050814:Octamer Transcription Factor-3; D015513:Oncogene Proteins; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011506:Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D014212:Tretinoin; D000099261:Homeobox A1 Protein; C525810:Bmp4 protein, mouse; C492067:CCN4 protein, mouse; C507838:Lif protein, mouse; C481797:Pbx1 protein, mouse; C494174:Pou5f1 protein, mouse