A mouse pluripotent embryonal stem cell line stage-specifically regulates expression of homeo-box containing DNA sequences during differentiation in vitro

Mouse embryonal stem (ES) cells have been shown to provide a new model system suitable for the analysis of different aspects of murine development. This report gives evidence that ES cell lines are also most useful for the study of developmentally regulated gene expression in vitro. Homeo-box containing genes which are suggested to play a key role in the regulation of differentiation steps occurring during embryogenesis are stage-specifically transcribed in differentiating murine ES cells: (i) A mouse embryonal stem cell line (ES-12957) was isolated and characterized with respect to its differentiation potential. When injected subcutaneously into syngeneic mice, ES-12957 cells formed fully differentiated teratomas representing derivatives of all three germ layers. When allowed to grow in suspension cultures in vitro, the cells followed a reproducible developmental pathway forming complex organized 'embryoid bodies' which resembled mouse early postimplantation embryos. (ii) A mouse DNA sequence with homeo-box homology (MH-121) was isolated and structurally analyzed. Transcription of a 1.7 kb RNA species from this DNA sequence was demonstrated in ES-12957 cells which were differentiated in vitro. A second, previously described homeo-box gene (Mo-10) was also shown to be expressed in ES-12957 cells in a stage-specific manner. A 4-kb transcript could be identified exclusively in RNA of cells which were allowed to differentiate for 9 days. These findings support the suggestion that the homeo-box genes of mammals, like those of Drosophila, may have important functions during embryonic development

Chromosomal mapping of the structural gene coding for the mouse cell adhesion molecule uvomorulin.

The gene coding for the mouse cell adhesion molecule uvomorulin has been mapped to chromosome 8. Uvomorulin cDNA clone F5H3 identified restriction fragment length polymorphisms in Southern blots of genomic DNA from mouse species Mus musculus domesticus and Mus spretus. By analyzing the segregation pattern of the gene in 75 offspring from an interspecific backcross a single genetic locus, Um, was defined on chromosome 8. Recombination frequency between Um and the co-segregating loci serum esterase 1 (Es-1) and tyrosine aminotransferase (Tat) places Um about 14 centimorgan (cM) distal to Es-1, and 5 cM proximal to Tat. In situ hybridization of uvomorulin [3H]cDNA to mouse metaphase chromosomes located the Um locus close to the distal end of chromosome 8 (bands C3-E1). Since uvomorulin is evolutionarily highly conserved, its chromosomal assignment adds an important marker to the mouse genetic map

The structure of cell adhesion molecule uvomorulin. Insights into the molecular mechanism of Ca2+-dependent cell adhesion

We have determined the amino acid sequence of the Ca2+-dependent cell adhesion molecule uvomorulin as it appears on the cell surface. The extracellular part of the molecule exhibits three internally repeated domains of 112 residues which are most likely generated by gene duplication. Each of the repeated domains contains two highly conserved units which could represent putative Ca2+-binding sites. Secondary structure predictions suggest that the putative Ca2+-binding units are located in external loops at the surface of the protein. The protein sequence exhibits a single membrane-spanning region and a cytoplasmic domain. Sequence comparison reveals extensive homology to the chicken L-CAM. Both uvomorulin and L-CAM are identical in 65% of their entire amino acid sequence suggesting a common origin for both CAMs

The structure of cell adhesion molecule uvomorulin. Insights into the molecular mechanism of Ca2+-dependent cell adhesion.

We have determined the amino acid sequence of the Ca2+-dependent cell adhesion molecule uvomorulin as it appears on the cell surface. The extracellular part of the molecule exhibits three internally repeated domains of 112 residues which are most likely generated by gene duplication. Each of the repeated domains contains two highly conserved units which could represent putative Ca2+-binding sites. Secondary structure predictions suggest that the putative Ca2+-binding units are located in external loops at the surface of the protein. The protein sequence exhibits a single membrane-spanning region and a cytoplasmic domain. Sequence comparison reveals extensive homology to the chicken L-CAM. Both uvomorulin and L-CAM are identical in 65% of their entire amino acid sequence suggesting a common origin for both CAMs