Regulation of MHC class I gene expression is at transcriptional and post-transcriptional level in bovine placenta

A previous study of MHC in cattle trophoblast demonstrated low or absent class I expression, using a broad specificity monoclonal antibody. The study reported here uses MHC-defined cattle and embryo transfer to ensure MHC incompatibility between dam and calf. Transcription and expression of defined class I genes was examined in placentomes taken at term, using monoclonal antibodies to bovine class I, a gene-specific DNA-based typing system, and in situ hybridisation. Results demonstrate intermediate levels of fetal MHC class I mRNA in trophoblast, but no detectable fetal class I protein. This suggests a level of transcriptional down-regulation, and a post-transcriptional block which might involve other gene products, such as beta(2)-microglobulin (beta(2)m), or proteins involved in generation/transport of peptides. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.