The Etl-1 gene encodes a nuclear protein differentially expressed during early mouse development.
Recently, we isolated a novel mouse gene, Etl-1 (Enhancer-trap-locus-1), whose deduced amino acid sequence shows in its C-terminal portion striking homology to the brahma protein (BRM), a transcriptional regulator of homeotic genes in Drosophila, and to SNF2/SWI2, a transcriptional regulator of various genes in Saccharomyces cerevisiae. Here we report the generation of antibodies against the Etl-1 gene product (ETL-1) and describe the subcellular localization as well as the expression and distribution of the ETL-1 protein during mouse pre- and early post-implantation development. ETL-1 is a nuclear protein and is expressed in a biphasic manner during early embryogenesis. Moderate levels of ETL-1 were detected in unfertilized and fertilized eggs but in the latter the protein was not concentrated in the pronuclei and seemed evenly distributed throughout the cytoplasm. In two-cell embryos nuclear ETL-1 protein accumulated transiently and levels decreased during subsequent cleavage development. After the morula stage, ETL-1 levels increased again; in blastocysts high levels of ETL-1 were present in inner cell mass cells whereas trophectoderm cells contained little or no ETL-1. During subsequent development essentially all cell types except parietal endoderm and trophoblast cells contained high levels of ETL-1. Our results imply that nuclear ETL-1 is dispensable for the progression to the two cell stage, and suggest that during cleavage ETL-1 might be needed at the onset of embryonic transcription. In blastocysts ETL-1 function might be specifically required in cells of the inner cell mass and later in most cells of the embryo proper and extraembryonic ectoderm lineage.
Schoor
M
M
Max-Delbrück-Laboratorium, MPG, Köln, FRG.
Schuster-Gossler
K
K
Gossler
A
A
D000818:Animals; D000906:Antibodies; D001755:Blastocyst / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004265:DNA Helicases; D005314:Embryonic and Fetal Development / Q000502:physiology*; D007120:Immunochemistry; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics*; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis
D000906:Antibodies; D009687:Nuclear Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D004265:DNA Helicases; C079429:Smarcad1 protein, mouse