Journal
JOURNAL OF CLINICAL INVESTIGATION
Volume 116, Issue 7, Pages 1902-1912Publisher
AMER SOC CLINICAL INVESTIGATION INC
DOI: 10.1172/JCI28400
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Funding
- NIDDK NIH HHS [U19 DK062434, U19-DK62434] Funding Source: Medline
- NIGMS NIH HHS [GM069338, U54 GM069338] Funding Source: Medline
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Cholesterol is the obligate precursor to adrenal steroids but is cytotoxic at high concentrations. Here, we show the role of the liver X receptors (LXR alpha and LXR beta) in preventing accumulation of free cholesterol in mouse adrenal glands by controlling expression of genes involved in all aspects of cholesterol utilization, including the steroidogenic acute regulatory protein, StAR, a novel LXR target. Under chronic dietary stress, adrenal glands from Lxr alpha beta(-/-) mice accumulated free cholesterol. In contrast, wild-type animals maintained cholesterol homeostasis through basal expression of genes involved in cholesterol efflux and storage (ABC transporter A1 [ABCA1], apoE, SREBP-1c) while preventing steroidogenic gene (StAR) expression. Upon treatment with an LXR agonist that mimics activation by oxysterols, expression of these target genes was increased. Basally, Lxr alpha beta(-/-) mice exhibited a marked decrease in ABCA1 and a derepression of StAR expression, causing a net decrease in cholesterol efflux and an increase in steroidogenesis. These changes occurred under conditions that prevented the acute stress response and resulted in a phenotype more specific to the loss of LXR alpha, including hypercorticosteronemia, cholesterol ester accumulation, and adrenomegaly. These results imply LXR alpha provides a safety valve to limit free cholesterol levels as a basal protective mechanism in the adrenal gland, where cholesterol is under constant flux.
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