title: Adipose triglyceride lipase and hormone-sensitive lipase are involved in fat loss in JunB-deficient mice.
abstract: Proteins of the activator protein-1 family are known to have roles in many physiological processes such as proliferation, apoptosis, and inflammation. However, their role in fat metabolism has yet to be defined in more detail. Here we study the impact of JunB deficiency on the metabolic state of mice. JunB knockout (JunB-KO) mice show markedly decreased weight gain, reduced fat mass, and a low survival rate compared with control mice. If fed a high-fat diet, the weight gain of JunB-KO mice is comparable to control mice and the survival rate improves dramatically. Along with normal expression of adipogenic marker genes in white adipose tissue (WAT) of JunB-KO mice, this suggests that adipogenesis per se is not affected by JunB deficiency. This is supported by in vitro data, because neither JunB-silenced 3T3-L1 cells nor mouse embryonic fibroblasts from JunB-KO mice show a change in adipogenic potential. Interestingly, the key enzymes of lipolysis, adipose triglyceride lipase and hormone-sensitive lipase, were significantly increased in WAT of fasted JunB-KO mice. Concomitantly, the ratio of plasma free fatty acids per gram fat mass was increased, suggesting an elevated lipolytic rate under fasting conditions. Furthermore, up-regulation of TNFα and reduced expression of perilipin indicate that this pathway is also involved in increased lipolytic rate in these mice. Additionally, JunB-KO mice are more insulin sensitive than controls and show up-regulation of lipogenic genes in skeletal muscle, indicating a shuttling of energy substrates from WAT to skeletal muscle. In summary, this study provides valuable insights into the impact of JunB deficiency on the metabolic state of mice.
authors.affiliation: Institute for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Pinent
authors.forename: Andreas
authors.initials: A
authors.lastname: Prokesch
authors.forename: Hubert
authors.initials: H
authors.lastname: Hackl
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Voshol
authors.forename: Ariane
authors.initials: A
authors.lastname: Klatzer
authors.forename: Evelyn
authors.initials: E
authors.lastname: Walenta
authors.forename: Ute
authors.initials: U
authors.lastname: Panzenboeck
authors.forename: Lukas
authors.initials: L
authors.lastname: Kenner
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Trajanoski
authors.forename: Gerald
authors.initials: G
authors.lastname: Hoefler
authors.forename: Juliane G
authors.initials: JG
authors.lastname: Bogner-Strauss
mesh_terms: D041721:3T3-L1 Cells; D052438:Adipocytes, White / Q000166:cytology / Q000378:metabolism*; D050154:Adiposity; D000818:Animals; D002352:Carrier Proteins; D003433:Crosses, Genetic; D004041:Dietary Fats / Q000008:administration & dosage; D005786:Gene Expression Regulation; D006130:Growth Disorders / Q000178:diet therapy / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D007333:Insulin Resistance; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D008066:Lipolysis; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000378:metabolism; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000502:physiology*; D002787:Sterol Esterase / Q000235:genetics / Q000378:metabolism*; D016019:Survival Analysis; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D000217:Acyltransferases
chemical_list: D002352:Carrier Proteins; D004041:Dietary Fats; D008049:Lipase; D000070778:Perilipin-1; D010750:Phosphoproteins; D020033:Protein Isoforms; D016755:Proto-Oncogene Proteins c-jun; D002787:Sterol Esterase; D014409:Tumor Necrosis Factor-alpha; C494445:PNPLA2 protein, mouse; D000217:Acyltransferases