ABSTRACT
In this paper we describe the cloning of the mouse Parathyroid Hormone/Parathyroid Hormone related Peptide Receptor (PTH/PTHrPR) cDNA and expression of its mRNA during mouse postimplantation development from day 5.5 until day 15.5 post coitum (p.c.). In support of a model from previous studies, in which parietal endoderm differentiation is regulated by the interaction of the PTH/PTHrPR and Parathyroid Hormone related Peptide (PTHrP), high levels of PTH/PTHrPR mRNA levels were detected in developing parietal endoderm from day 5.5 p.c. and onwards. In the embryo proper, PTH/PTHrPR mRNA expression was mainly detected at sites of epithelium/mesenchyme interactions, starting at day 9.5 p.c. in the epithelium of the intestine and later in the mesenchyme of the lung, the epithelium of meso- and metanephric tubuli, the dermis and at all sites where bone formation takes place. The complexity of the PTH/PTHrPR expression pattern suggests tight developmental regulation and indicates multiple roles in embryogenesis for the receptor and its ligands, not only in extraembryonic tissue but also in the formation of various organs.
Subject(s)
Embryo, Mammalian/chemistry , Embryonic Development/physiology , Embryonic and Fetal Development/physiology , RNA, Messenger/analysis , Receptors, Parathyroid Hormone/genetics , Receptors, Parathyroid Hormone/physiology , Animals , Blotting, Northern , Cloning, Molecular , DNA/analysis , DNA/genetics , Embryonic and Fetal Development/genetics , Endoderm/chemistry , Female , In Situ Hybridization , Intestines/chemistry , Intestines/embryology , Lung/chemistry , Lung/embryology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Pregnancy , RNA/analysis , RNA/genetics , RNA, Messenger/genetics , Receptor, Parathyroid Hormone, Type 1ABSTRACT
Like other HOX genes the murine Hox-2.4 gene is thought to be involved in regional specification along the antero-posterior axis. In addition it has been reported to have oncogenic potential. We studied expression Hox-2.4 in murine EC cells and determined the transcription start site. Studies of DNA-protein interactions in the promoter region showed that the Hox-2.4 promoter contains a CCAAT box and a perfect octamer motif, which is capable of binding Oct-factors. Cotransfection of Oct expression vectors influences the transcriptional activity of the promoter, suggesting that the Oct-gene family may be involved in regulating HOX genes.
Subject(s)
Gene Expression Regulation/genetics , Genes, Homeobox/genetics , Promoter Regions, Genetic/genetics , Transcription, Genetic/genetics , Animals , Base Sequence , Binding Sites/genetics , Blotting, Northern , Embryonal Carcinoma Stem Cells , Genetic Vectors/genetics , Luciferases/genetics , Luciferases/metabolism , Mice , Molecular Sequence Data , Neoplastic Stem Cells , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
The murine homeobox-containing gene Hox-2.3 contains a basal promoter in a 210-bp region upstream of the transcription start site. In vitro studies of DNA-protein interactions in this region, and in a 1.3-kb upstream region which is known to play a role in tissue specific expression in vivo, led to the identification of DNA elements interacting with nuclear proteins from embryocarcinoma cells. Among the factors binding to the basal promoter is the upstream stimulating factor (USF), also known as major late transcription factor (MLTF). A single point mutation in its binding site abolishes binding in vitro and leads to 50% reduction of the transcriptional activity as measured in receptor gene experiments, showing that it is an activator of Hox-2.3 expression.
