Lipocalin Prostaglandin D Synthase and PPARc2 Coordinate to Regulate Carbohydrate and Lipid Metabolism In Vivo Sam Virtue1*, Mojgan Masoodi2, Vidya Velagapudi3, Chong Yew Tan 1 , Martin Dale1, Tapani Suorti3, Marc Slawik4, Margaret Blount1, Keith Burling 1 , Mark Campbell1, Naomi Eguchi5, Gema Medina-Gomez6, Jaswinder K. Sethi1, Matej Oresˇ icˇ 3, Yoshihiro Urade5, Julian L. Griffin7, Antonio Vidal-Puig1* 1 University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Cambridge, United Kingdom, 2 Elsie Widdowson Laboratory, Medical Research Council Human Nutrition Research, Cambridge, United Kingdom, 3 VTT Technical Research Centre of Finland, Espoo, Finland, 4 Department of Medicine Innenstadt, Endocrinology/Diabetes University Hospital, Munich, Germany, 5 Osaka Bioscience Institute, Osaka, Japan, 6 Departamento de Bioqu´ımica, Fisiolog´ıa y Gene´tica Molecular, Universidad Rey Juan Carlos, Madrid, Spain, 7 Department of Biochemistry, Medical Research Council Human Nutrition Research, Cambridge, United Kingdom Abstract Mice lacking Peroxisome Proliferator-Activated Receptor c2 (PPARc2) have unexpectedly normal glucose tolerance and mild insulin resistance. Mice lacking PPARc2 were found to have elevated levels of Lipocalin prostaglandin D synthase (L-PGDS) expression in BAT and subcutaneous white adipose tissue (WAT). To determine if induction of L-PGDS was compensating for a lack of PPARc2, we crossed L-PGDS KO mice to PPARc2 KO mice to generate Double Knock Out mice (DKO). Using DKO mice we demonstrated a requirement of L-PGDS for maintenance of subcutaneous WAT (scWAT) function. In scWAT, DKO mice had reduced expression of thermogenic genes, the de novo lipogenic program and the lipases ATGL and HSL. Despite the reduction in markers of lipolysis in scWAT, DKO mice had a normal metabolic rate and elevated serum FFA levels compared to L-PGDS KO alone. Analysis of intra-abdominal white adipose tissue (epididymal WAT) showed elevated expression of mRNA and protein markers of lipolysis in DKO mice, suggesting that DKO mice may become more reliant on intra-abdominal WAT to supply lipid for oxidation. This switch in depot utilisation from subcutaneous to epididymal white adipose tissue was associated with a worsening of whole organism metabolic function, with DKO mice being glucose intolerant, and having elevated serum triglyceride levels compared to any other genotype. Overall, L-PGDS and PPARc2 coordinate to regulate carbohydrate and lipid metabolism. Citation: Virtue S, Masoodi M, Velagapudi V, Tan CY, Dale M, et al. (2012) Lipocalin Prostaglandin D Synthase and PPARc2 Coordinate to Regulate Carbohydrate and Lipid Metabolism In Vivo. PLoS ONE 7(7): e39512. doi:10.1371/journal.pone.0039512 Editor: Jose A. L. Calbet, University of Las Palmas de Gran Canaria, Spain Received November 10, 2011; Accepted May 22, 2012; Published July 5, 2012 Copyright: 2012 Virtue et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This study was funded by Diabetes UK (www.diabetes.org.uk), EU HEPADIP FP6 (Hepatic and Adipose Tissue and Functions in the Metabolic Syndrome) (www.hepadip.org), The Medical Research Council Centre for Obesity Related Disorders (www.mrc-cord.org), and the Medical Research Council (www.mrc.ac.uk). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have read the journal’s policy and have the following conflicts: Co-author Matej Oresˇicˇ is an Academic Editor on the PLoS ONE Editorial Board. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. All other authors have declared that no competing interests exist. * E-mail: sv234@medschl.cam.ac.uk (SV); ajv22@medschl.cam.ac.uk (AV-P) Introduction We have previously described the phenotype of the Peroxisome Proliferator Activated Receptor c2 KO mouse on a sv129 background (sv129 PPARc2 KO mice) [1], a mouse model notable for its surprisingly mild phenotype in terms of adipose tissue function and insulin resistance. The nuclear receptor Peroxisome Proliferator Activated Receptor c (PPARc) is essential for adipogenesis [2] and has two isoforms, PPARc1 and PPARc2. In vivo PPARc1 has a broad tissue distribution whereas, under normal physiological conditions, PPARc2 expression is almost exclusive to adipose tissue [3]. In white and brown adipose tissue, approximately half of all PPARc protein and PPARc transcript is PPARc2 [3]. Further- more, PPARc2 has a higher transcriptional activity than PPARc1 [4], suggesting that loss of PPARc2 from adipose tissue would represent a loss of the majority of PPARc mediated transcriptional function. In accordance with these data, two separate studies demonstrated that when either preadipocytes or mouse embryonic fibroblasts (MEFS) were obtained from PPARc2 KO mice, they had a greatly impaired capacity for adipogenesis in vitro when compared to wild-type cells [5,6]. While much focus on PPARc function has been directed towards its adipogenic role and its control of glucose homeostasis, PPARc also regulates many of the enzymes involved in lipid uptake, synthesis and release. Mice and humans with dominant negative mutations in PPARc have severe impairments in lipid clearance [7,8], pointing to an important role for PPARc in daily lipid buffering. The finding that mice harbouring a P465L Dominant Negative (DN) mutation in the PPARc gene actually had normal glucose tolerance but impaired lipid clearance suggests that PPARc may be more crucial for lipid homeostasis than carbohydrate metabolism [7]. PPARc2 KO mice also exhibited almost normal glucose tolerance and insulin sensitivity but also had severe impairments in lipid clearance compared to wild type controls. PLoS ONE | www.plosone.org 1 July 2012 | Volume 7 | Issue 7 | e39512