Negative regulation of human parathyroid hormone gene promoter by vitamin D3 through nuclear factor Y

Area of Science:

• Endocrinology
• Molecular Biology
• Gene Regulation

Background:

• The human parathyroid hormone (PTH) gene is negatively regulated by vitamin D3.
• Rat pituitary GH4C1 cells possess factors essential for this negative regulation.

Purpose of the Study:

• To investigate the molecular mechanisms of human PTH gene regulation by vitamin D3 in GH4C1 cells.
• To identify the roles of NF-Y and vitamin D receptor (VDR) in this regulatory process.

Main Methods:

• Studied the binding of NF-Y and VDR to the human PTH gene promoter in GH4C1 cells.
• Assessed the impact of VDR and NF-Y binding on promoter activity.
• Compared regulatory mechanisms in GH4C1 and ROS17/2.8 cell lines.

Main Results:

• NF-Y binds to sequences downstream of the VDR binding site in the PTH gene promoter.
• NF-Y binding sites near the VDR site are crucial for full promoter activity.
• VDR and NF-Y binding to the VDRE region is mutually exclusive.
• VDR binding sequesters NF-Y partners, affecting transcription via NF-Y elements in GH4C1 cells.

Conclusions:

• 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) regulates human PTH gene transcription through competitive binding of VDR and NF-Y.
• Vitamin D3 modulates NF-Y transcriptional activity, contributing to PTH gene regulation.