NFκB and AP-1 drive human myometrial IL8 expression

Area of Science:

• Reproductive biology
• Molecular endocrinology
• Gene regulation

Background:

• Uterine expression of the chemokine IL8 significantly increases during labor.
• The IL8 gene promoter has binding sites for transcription factors: nuclear factor-kappa B (NFκB), activator protein-1 (AP-1), and CCAAT/enhancer-binding protein (CEBP).

Purpose of the Study:

• To investigate the roles of NFκB, AP-1, and CEBP in IL1B-mediated regulation of the IL8 gene in human myometrium.

Main Methods:

• Chromatin immune precipitation (ChIP) assay to detect transcription factor binding to the IL8 promoter.
• Site-directed mutagenesis of transcription factor binding sites.
• Small interfering RNA (siRNA) to silence transcription factors.

Main Results:

• NFκB, CEBP, and AP-1 bind to the IL8 promoter upon IL1B stimulation.
• The NFκB binding site is crucial for basal and IL1B-stimulated IL8 expression.
• Mutating the AP-1 site moderately decreased IL8 expression, while mutating the CEBP site abolished the IL1B response.
• NFκB silencing abolished the IL8 response to IL1B, AP-1 silencing reduced it, and CEBP silencing enhanced it.

Conclusions:

• Nuclear factor-kappa B (NFκB) plays a central and essential role in the regulation of IL8 gene expression in human myometrium.
• The transcription factors NFκB, AP-1, and CEBP differentially contribute to IL8 gene regulation in response to IL1B.