Gene expression profiling identifies liver X receptor alpha as an estrogen-regulated gene in mouse adipose tissue

Area of Science:

• Endocrinology
• Molecular Biology
• Metabolism

Background:

• Estrogens are known to decrease adipose tissue mass in mammals.
• The precise molecular mechanisms underlying estrogen's effects on adipose tissue remain incompletely understood.

Purpose of the Study:

• To investigate the direct molecular effects of estrogen on mouse white adipose tissue (WAT) using a gene expression profiling approach.
• To identify novel genes and pathways mediating estrogen's impact on adipose tissue mass.

Main Methods:

• Gene expression profiling of mouse WAT following 17beta-estradiol treatment in ovariectomized mice.
• Analysis of messenger RNA (mRNA) expression levels of key metabolic genes and estrogen receptors.
• Identification of regulatory elements in the LXRalpha promoter responsive to estrogen.

Main Results:

• 17beta-estradiol treatment significantly decreased mRNA expression of liver X receptor alpha (LXRα) and its target genes, including sterol regulatory element-binding protein 1c and ATP-binding cassette transporters.
• A 1.5 kb LXRα promoter fragment was identified as being negatively regulated by estrogen.
• Several novel genes involved in lipogenesis and lipolysis were identified as potential mediators of estrogenic effects on WAT.
• Estrogen receptor alpha (ERα) was confirmed as the primary estrogen receptor in mouse WAT, with significantly higher mRNA levels than ERbeta.

Conclusions:

• Estrogen exerts its effects on white adipose tissue, in part, through the downregulation of the LXRα pathway.
• ERα is the dominant estrogen receptor mediating these effects in mouse WAT.
• The findings identify novel molecular targets and pathways involved in estrogen-mediated regulation of adipose tissue mass.