Progesterone regulates HLA-G gene expression through a novel progesterone response element

Area of Science:

• Immunology
• Molecular Biology
• Reproductive Endocrinology

Background:

• Progesterone stimulates HLA-G gene expression.
• This effect is blocked by the anti-progestin RU486, suggesting receptor-mediated action.
• The precise molecular mechanisms require further investigation.

Purpose of the Study:

• To elucidate the molecular mechanisms by which progesterone influences HLA-G gene expression.
• To identify the specific DNA elements involved in progesterone's regulation of HLA-G.

Main Methods:

• JEG-3 choriocarcinoma cells were transfected with an HLA-G promoter-chloramphenicol acetyltransferase (CAT) construct.
• Electrophoretic mobility shift assay (EMSA) and DNA fragment-binding ELISA were used to identify a progesterone response element (PRE).

Main Results:

• Progesterone treatment increased CAT synthesis, confirming transcriptional activation of the HLA-G promoter.
• RU486 inhibited this progesterone-induced activation.
• A novel PRE, with 60% homology to the mouse mammary tumour virus (MMTV) PRE, was identified in the HLA-G promoter.

Conclusions:

• Progesterone regulates HLA-G gene expression through progesterone receptor (PR) activation.
• This activation involves binding to a newly discovered PRE within the HLA-G promoter region.
• This pathway represents a potential mechanism for progesterone-mediated immunomodulation during pregnancy.