C75 [4-Methylene-2-octyl-5-oxo-tetrahydro-furan-3-carboxylic Acid] Activates Carnitine Palmitoyltransferase-1 in Isolated Mitochondria and Intact Cells without Displacement of Bound Malonyl CoA

• Published in: The Journal of pharmacology and experimental therapeutics 2005-01, Vol.312 (1), p.127-133
• Main Authors: Yang, Nengyu, Kays, Joanne S, Skillman, Tiffanie R, Burris, Lorri, Seng, Thomas W, Hammond, Craig
• Format: Article
• Language: English
• Subjects: 4-Butyrolactone - analogs & derivatives; 4-Butyrolactone - pharmacology; Animals; Carnitine O-Palmitoyltransferase - metabolism; Enzyme Activation - drug effects; Humans; Malonyl Coenzyme A - metabolism; Mitochondria, Heart - drug effects; Mitochondria, Heart - enzymology; Rats; Recombinant Proteins - metabolism; Tumor Cells, Cultured; Yeasts - genetics
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.104.074104

Carnitine palmitoyltransferase 1β (CPT-1β) is a key regulator of the β oxidation of long-chain fatty acids in skeletal muscle and therefore a potential therapeutic target for diseases associated with defects in lipid metabolism such as obesity and type 2 diabetes. C75 [4-methylene-2-octyl-5-oxo-tetrahydro-furan-3-carboxylic acid] is an α-methylene-butyrolactone that has been characterized as both an inhibitor of fatty acid synthase and more recently, an activator of CPT-1 ( Thupari et al., 2002 ). Using human CPT-1β expressed in the yeast Pichia pastoris , we demonstrate that C75 can activate the skeletal muscle isoform of CPT-1 and overcome inactivation of the enzyme by malonyl CoA, an important physiological repressor of CPT-1, and the malonyl CoA mimetic Ro25-0187 [{5-[2-(naphthalen-2-yloxy)-ethoxy]-thiophen-2-yl}-oxo-acetic acid]. We also show that C75 can activate CPT-1 in intact hepatocytes to levels similar to those achieved with inhibition of acetyl-CoA carboxylase, the enzyme that produces malonyl CoA. Finally, we demonstrate that concentrations of C75 sufficient for activation of CPT-1 do not displace bound malonyl CoA. We conclude that CPT-1 is an activator of human CPT-1β and other CPT-1 isoforms but that it does not activate CPT-1 through antagonism of malonyl CoA binding.