title: Genetic ablation of myelin protein zero-like 3 in mice increases energy expenditure, improves glycemic control, and reduces hepatic lipid synthesis.
abstract: Obesity continues to be a global health problem, and thus it is imperative that new pathways regulating energy balance be identified. Recently, it was reported: (Hayashi K, Cao T, Passmore H, Jourdan-Le Saux C, Fogelgren B, Khan S, Hornstra I, Kim Y, Hayashi M, Csiszar K. J Invest Dermatol 123: 864-871, 2004) that mice carrying a missense mutation in myelin protein zero-like 3 (Mpzl3rc) have reduced body weight. To determine how Mpzl3 controls energy balance in vivo, we generated mice deficient in myelin protein zero-like 3 (Mpzl3-KO). Interestingly, KO mice were hyperphagic yet had reduced body weight and fat mass. Moreover, KO mice were highly resistant to body weight and fat mass gain after exposure to a high-fat, energy-dense diet. These effects on body weight and adiposity were driven, in part, by a pronounced increase in whole body energy expenditure levels in KO mice. KO mice also had reduced blood glucose levels during an intraperitoneal glucose challenge and significant reductions in circulating insulin levels suggesting an increase in insulin sensitivity. In addition, there was an overall increase in oxidative capacity and contractile force in skeletal muscle isolated from KO mice. Hepatic triglyceride levels were reduced by 92% in livers of KO mice, in part due to a reduction in de novo lipid synthesis. Interestingly, Mpzl3 mRNA expression in liver was increased in diet-induced obese mice. Moreover, KO mice exhibited an increase in insulin-stimulated Akt signaling in the liver, further demonstrating that Mpzl3 can regulate insulin sensitivity in this tissue. We have determined that Mpzl3 has a novel physiological role in controlling body weight regulation, energy expenditure, glycemic control, and hepatic triglyceride synthesis in mice.
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA. czyzyk.traci@mayo.edu
authors.forename: Traci A
authors.initials: TA
authors.lastname: Czyzyk
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Andrews
authors.forename: Tamer
authors.initials: T
authors.lastname: Coskun
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wade
authors.forename: Eric D
authors.initials: ED
authors.lastname: Hawkins
authors.forename: John F
authors.initials: JF
authors.lastname: Lockwood
authors.forename: Gabor
authors.initials: G
authors.lastname: Varga
authors.forename: Allison E
authors.initials: AE
authors.lastname: Sahr
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Chen
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Brozinick
authors.forename: Kristine
authors.initials: K
authors.lastname: Kikly
authors.forename: Michael A
authors.initials: MA
authors.lastname: Statnick
mesh_terms: D050154:Adiposity / Q000235:genetics / Q000502:physiology; D000818:Animals; D001774:Blood Chemical Analysis; D001786:Blood Glucose / Q000502:physiology*; D015153:Blotting, Western; D001831:Body Temperature / Q000502:physiology; D004032:Diet; D050171:Dyslipidemias / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005951:Glucose Tolerance Test; D006943:Hyperglycemia / Q000235:genetics / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009119:Muscle Contraction / Q000502:physiology; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D060888:Real-Time Polymerase Chain Reaction; D014280:Triglycerides / Q000378:metabolism; D015430:Weight Gain / Q000502:physiology
chemical_list: D001786:Blood Glucose; D008055:Lipids; D008565:Membrane Proteins; C520409:Mpzl3 protein, mouse; D014280:Triglycerides
keywords: immunoglobulin-like V-type domain; nonalcoholic fatty liver disease; rough coat (rc/rc), Akt; skeletal muscle