Nuclear Receptors, RXR, and the Big Bang

Area of Science:

• Molecular Endocrinology
• Genomics
• Structural Biology

Background:

• The identification of receptors for steroids, retinoids, vitamin D, and thyroid hormone revealed a conserved nuclear receptor template.
• This led to the discovery of numerous 'orphan receptors' with unknown functions.
• Nuclear receptors are critical regulators of gene expression and cellular processes.

Purpose of the Study:

• To provide a personal perspective on the evolution and function of nuclear hormone receptors.
• To explore the integrated signaling networks orchestrated by nuclear receptors.
• To highlight the role of the retinoid X receptor (RXR) and its transcriptional mechanisms.

Main Methods:

• Gene isolation and structural/functional analysis of nuclear hormone receptors.
• Characterization of orphan receptors, with a focus on RXR.
• Review of integrated signaling networks and transcriptional mechanisms.

Main Results:

• Discovery of an evolutionarily conserved template for nuclear hormone receptors.
• Identification of numerous orphan receptors, expanding the nuclear receptor superfamily.
• Characterization of RXR positioned nuclear receptors at the forefront of molecular endocrinology.

Conclusions:

• Nuclear receptors, particularly RXR, are central to the 'Big Bang' of molecular endocrinology.
• These receptors form integrated and coordinated signaling networks essential for multicellular life.
• Understanding RXR heterodimers, ligands, and transcriptional mechanisms is key to deciphering these networks.