E4F1, a novel estrogen-responsive gene in possible atheroprotection, revealed by microarray analysis

Area of Science:

• Cardiovascular Biology
• Endocrinology
• Molecular Biology

Background:

• Estrogen's role in inhibiting vascular smooth muscle cell (VSMC) proliferation is known but the precise mechanism via estrogen receptors (ER) is unclear.
• Estrogen receptors, ER alpha (ERα) and ER beta (ERβ), mediate distinct cellular responses.
• Understanding ER-mediated gene regulation is crucial for cardiovascular health.

Purpose of the Study:

• To identify estrogen-responsive genes in human VSMCs expressing ERα or ERβ.
• To elucidate the mechanism by which estrogen inhibits VSMC proliferation.
• To investigate the role of identified genes in estrogen-related atheroprotection.

Main Methods:

• Microarray analysis of estrogen-treated human VSMCs (ERα-positive and ERβ-positive).
• Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for gene expression analysis.
• Small interfering RNA (siRNA) to block target gene (TG) function and in situ hybridization for aortic expression.

Main Results:

• Estrogen significantly increased E4F1 expression specifically in ERα-positive VSMCs.
• Blocking E4F1 with siRNA abolished the estrogenic inhibition of ERα-positive VSMC proliferation.
• E4F1 mRNA was abundant in premenopausal female aortas with early atherosclerotic changes.

Conclusions:

• E4F1 is an estrogen-responsive gene mediated by ERα.
• E4F1 plays a role in estrogen-induced inhibition of VSMC proliferation.
• E4F1 may contribute to estrogen-related atheroprotection in the human aorta.