title: Enhanced muscle fat oxidation and glucose transport by ACRP30 globular domain: acetyl-CoA carboxylase inhibition and AMP-activated protein kinase activation.
abstract: gACRP30, the globular subunit of adipocyte complement-related protein of 30 kDa (ACRP30), improves insulin sensitivity and increases fatty acid oxidation. The mechanism by which gACRP30 exerts these effects is unknown. Here, we examined if gACRP30 activates AMP-activated protein kinase (AMPK), an enzyme that has been shown to increase muscle fatty acid oxidation and insulin sensitivity. Incubation of rat extensor digitorum longus (EDL), a predominantly fast twitch muscle, with gACRP30 (2.5 micro g/ml) for 30 min led to 2-fold increases in AMPK activity and phosphorylation of both AMPK on Thr-172 and acetyl CoA carboxylase (ACC) on Ser-79. Accordingly, concentration of malonyl CoA was diminished by 30%. In addition, gACRP30 caused a 1.5-fold increase in 2-deoxyglucose uptake. Similar changes in malonyl CoA and ACC were observed in soleus muscle incubated with gACRP30 (2.5 micro g/ml), although no significant changes in AMPK activity or 2-deoxyglucose uptake were detected. When EDL was incubated with full-length hexameric ACRP30 (10 micro g/ml), AMPK activity and ACC phosphorylation were not altered. Administration of gACRP30 (75 micro g) to C57 BL6J mice in vivo led to increased AMPK activity and ACC phosphorylation and decreased malonyl CoA concentration in gastrocnemius muscle within 15-30 min. Both in vivo and in vitro, activation of AMPK was the first effect of gACRP30 and was transient, whereas alterations in malonyl CoA and ACC occurred later and were more sustained. Thus, gACRP30 most likely exerts its actions on muscle fatty acid oxidation by inactivating ACC via activation of AMPK and perhaps other signal transduction proteins.
authors.affiliation: Diabetes Unit, Section of Endocrinology, Boston Medical Center and Departments of Medicine and Physiology, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Tomas
authors.forename: Tsu-Shuen
authors.initials: TS
authors.lastname: Tsao
authors.forename: Asish K
authors.initials: AK
authors.lastname: Saha
authors.forename: Heather E
authors.initials: HE
authors.lastname: Murrey
authors.forename: Cheng cheng
authors.initials: Cc
authors.lastname: Zhang Cc
authors.forename: Samar I
authors.initials: SI
authors.lastname: Itani
authors.forename: Harvey F
authors.initials: HF
authors.lastname: Lodish
authors.forename: Neil B
authors.initials: NB
authors.lastname: Ruderman
mesh_terms: D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D052242:Adiponectin; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D004789:Enzyme Activation; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D007333:Insulin Resistance; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008316:Malonyl Coenzyme A / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009097:Multienzyme Complexes / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D052242:Adiponectin; D005227:Fatty Acids; D036341:Intercellular Signaling Peptides and Proteins; D009097:Multienzyme Complexes; D009124:Muscle Proteins; D011506:Proteins; D008316:Malonyl Coenzyme A; D003847:Deoxyglucose; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; D005947:Glucose