Functional and physiological genomics of estrogen-related receptors (ERRs) in health and disease.

Orphan nuclear receptors, in a manner comparable to classic steroid hormone receptors, regulate key developmental and physiological processes. However, the lack of appropriate pharmacological tools has often hindered the identification and study of their biological functions. In this review, we demonstrate that functional and physiological genomics are effective alternatives to discover biological functions associated with orphan nuclear receptors. Indeed, we document that these approaches have allowed for the unambiguous identification of the estrogen-related receptors (ERRs) α, β, and γ (NR3B1, 2, and 3) as global regulators of cellular energy metabolism. We further show that although the three ERR isoforms control analogous gene networks, each isoform performs unique biological functions in a tissue-specific manner in response to a variety of physiological stressors. Finally, we discuss how the activity of the three ERR isoforms contributes to the development and progression of metabolic diseases as well as to the adaptation of cancer cells to their unique bioenergetic requirement. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.