126. Progesterone regulates CXCL14 (macrophage inflammatory protein 2γ) mRNA in human endometrium

Abstract

The emergence of microarray technology has enabled a thorough study of the level of transcripts in the human body. A high density micoarray analysis revealed a comprehensive list of transcripts, which were significantly different between mid-proliferative and mid-secretory phase endometrium.² An EST identified from the HG_U95B chip is identical to the 3′UTR of CXCL14 or macrophage inflammatory protein 2γ (MIP 2γ). The level is 19-fold higher in the mid-secretory compared to the mid-proliferative phase of menstrual cycle. This has suggested that the transcript level of CXCL14 may be directly regulated by progesterone. Northern hybridisation and in situ hybridisation confirmed that the transcript level of CXCL14 (MIP 2γ) was high in the mid-to-late secretory endometrium and its mRNA was localised in the glandular epithelium of this tissue.¹ In silico analysis has predicted six progesterone response elements (PREs) within 2040 bp upstream from the ATG site. To investigate the possible functions of these PREs, a dual luciferase assay was performed on the ishikawa cell line transfected with five deletion constructs of the gene promoter. Cells were co-transfected with progesterone receptor B (PRB) and treated with 10^–6 M progesterone. Luciferase activities of these constructs have localised two fragments that were most likely to contain the active PREs, i.e. PRE1 and PRE2. An electrophoretic mobility shift assay showed that PRE oligonulcleotides within these two regions were able to bind PRB that was synthesised in vitro, although there was a stronger signal seen in the PRE2 region. A dose competition study revealed PRE1/PRB and PRE2/PRB protein binding could be competed with different concentrations of cold wild-type competitor oligonucleotides. Mutagenesis of PRE1 and PRE2 analysed by luciferase reporter assay reduced the inductive effect of progesterone treatment. This study indicates that progestegen induced transcript encoding a chemokine in the human endometrium may likely act as a chemoattractant for leucocytes during the secretory phase of the menstrual cycle.

   (1) Mokhtar NM, Smith SK, Charnock-Jones DS. (2003). Characterisation of chemokine macrophage inflammatory protein 2gamma mRNA in human endometrium. 50th Society for Gynaecologic Investigation. Washington DC, USA. March 2003.
   (2) Borthwick JM, Charnock-Jones DS, Tom BD, Hull ML, Teirney R, Phillip SC, Smith SK. (2003). Determination of the transcript profile of human endometrium. Mol. Hum. Reprod. 9, 19–33.