PPAR-delta (also PPAR-beta/delta, gene PPARD, nuclear receptor NR1C2) is one of three peroxisome proliferator-activated receptors. It is a ligand-activated transcription factor: fatty acids and their derivatives bind a large hydrophobic pocket, the receptor heterodimerises with RXR, and the pair occupies PPAR response elements in target promoters, exchanging corepressors for coactivators.
Why PPAR-delta matters
Unlike PPAR-gamma, which is concentrated in adipose tissue, PPAR-delta is expressed broadly and most notably in skeletal muscle, where its target genes include CPT1, PDK4, UCP2/3 and other fatty-acid oxidation machinery. Transgenic mouse work published in 2004 reported a shift toward oxidative fibre type, which is the origin of the durable interest in synthetic agonists.
GW-501516 (cardarine) is the reference synthetic agonist and is supplied strictly as a research compound. Its development was discontinued after long-term rodent carcinogenicity findings, and it is prohibited in sport by WADA. That history is a material part of the definition and should accompany any experimental design that uses it. Related work on REV-ERB agonists targets a different nuclear receptor with partly overlapping metabolic readouts.
Related terms and material
AMPK · preclinical · research use only. Reference material: metabolic & circadian compounds. Further reading: what is cardarine (GW-501516) and PPAR and REV-ERB agonists explained.