The human MHC class I gene, HLA-G, is unique among members of the class I gene family in that it is nonpolymorphic, and expression is primarily restricted to extraembryonic tissues. To examine regulatory elements that direct tissue- and cell lineage-specific expression of this gene, transgenic mice expressing HLA-G have been established. In this study, in situ hybridization was used to evaluate the cellular distribution of HLA-G mRNA in transgenic placentas. Extraembryonic tissues were obtained at gestation day 12.5 from embryos that had been microinjected with either 6.0 or 5.7 kb of HLA-G genomic DNA and had been transferred into pseudopregnant HLA-G transgenic mice or Swiss mice. The 6.0 kb transgene contained an additional 250 bp at the extreme 5′-end of the upstream region. Genotype of the recipient had no discernable effect on the cellular distribution of HLA-G mRNA. HLA-G mRNA was present in both trophoblast and mesenchymal cells in transgenic placentas carrying 6.0 kb of genomic HLA-G, a pattern strikingly similar to that of HLA-G message distribution in early gestation human placentas. By contrast, in placentas from embryos carrying 5.7 kb HLA-G DNA, specific mRNA was found primarily in mesenchymal cells at the base of the placenta. Thus, the 6.0 genomic fragment contains elements capable of directing HLA-G expression in placentas, and is particularly influential in the trophoblastic cell lineage.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Immunology|
|State||Published - Oct 1 1993|