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.
Carnitine palmitoyltransferase 1beta (CPT-1beta) is a key regulator of the beta 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 alpha-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-1beta 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-1beta and other CPT-1 isoforms but that it does not activate CPT-1 through antagonism of malonyl CoA binding.
Yang
Nengyu
N
Endocrine Research, Lilly Research Laboratories, Division of Eli Lilly & Co., Lilly Corporate Center, Indianapolis, IN 46285, USA.
Kays
Joanne S
JS
Skillman
Tiffanie R
TR
Burris
Lorri
L
Seng
Thomas W
TW
Hammond
Craig
C
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008316:Malonyl Coenzyme A / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015003:Yeasts / Q000235:genetics
C406734:4-methylene-2-octyl-5-oxofuran-3-carboxylic acid; D011994:Recombinant Proteins; D008316:Malonyl Coenzyme A; D002334:Carnitine O-Palmitoyltransferase; D015107:4-Butyrolactone