Liver X receptors and fat cell metabolism.

Liver X receptors (LXRs) are members of the nuclear receptor family and are present in two isoforms, α and β, encoded by two separate genes. Originally described in the liver, LXRs have in the last 15 years been implicated in central metabolic pathways, including bile acid synthesis, lipid and glucose homeostasis. Although the vast majority of studies have been performed in non-adipose cells/tissues, results in recent years suggest that LXRs may have important modulatory roles in adipose tissue and adipocytes. Although several authors have published reviews on LXR, there have been no attempts to summarize the effects reported specifically in adipose systems. This overview gives a brief introduction to LXR and describes the sometimes-contradictory results obtained in murine cell systems and in rodent adipose tissue. The so far very limited number of studies performed in human adipocytes and adipose tissue are also presented. It should be apparent that although LXR may impact on several different pathways in metabolism, the clinical role of LXR modulation in adipose tissue is still not clear.