@article{JohnGruneOttetal.2018,
  author    = {John, Cathleen and Grune, Jana and Ott, Christiane and Nowotny, Kerstin and Deubel, Stefanie and K{\"u}hne, Arne and Schubert, Carola and Kintscher, Ulrich and Regitz-Zagrosek, Vera and Grune, Tilman},
  title     = {Sex Differences in Cardiac Mitochondria in the New Zealand Obese Mouse},
  series = {Frontiers in Endocrinology},
  volume    = {9},
  journal   = {Frontiers in Endocrinology},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-2392},
  doi       = {10.3389/fendo.2018.00732},
  pages     = {9},
  year      = {2018},
  abstract  = {Background: Obesity is a risk factor for diseases including type 2 diabetes mellitus (T2DM) and cardiovascular disorders. Diabetes itself contributes to cardiac damage. Thus, studying cardiovascular events and establishing therapeutic intervention in the period of type T2DM onset and manifestation are of highest importance. Mitochondrial dysfunction is one of the pathophysiological mechanisms leading to impaired cardiac function. Methods: An adequate animal model for studying pathophysiology of T2DM is the New Zealand Obese (NZO) mouse. These mice were maintained on a high-fat diet (HFD) without carbohydrates for 13 weeks followed by 4 week HFD with carbohydrates. NZO mice developed severe obesity and only male mice developed manifest T2DM. We determined cardiac phenotypes and mitochondrial function as well as cardiomyocyte signaling in this model. Results: The development of an obese phenotype and T2DM in male mice was accompanied by an impaired systolic function as judged by echocardiography and MyH6/7 expression. Moreover, the mitochondrial function only in male NZO hearts was significantly reduced and ERK1/2 and AMPK protein levels were altered. Conclusions: This is the first report demonstrating that the cardiac phenotype in male diabetic NZO mice is associated with impaired cardiac energy function and signaling events.},
  language  = {en}
}
@article{SaussenthalerOuniBaumeieretal.2019,
  author    = {Saussenthaler, Sophie and Ouni, Meriem and Baumeier, Christian and Schwerbel, Kristin and Gottmann, Pascal and Christmann, Sabrina and Laeger, Thomas and Sch{\"u}rmann, Annette},
  title     = {Epigenetic regulation of hepatic Dpp4 expression in response to dietary protein},
  series = {The journal of nutritional biochemistry},
  volume    = {63},
  journal   = {The journal of nutritional biochemistry},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {0955-2863},
  doi       = {10.1016/j.jnutbio.2018.09.025},
  pages     = {109 -- 116},
  year      = {2019},
  abstract  = {Dipeptidyl peptidase 4 (DPP4) is known to be elevated in metabolic disturbances such as obesity, type 2 diabetes and fatty liver disease. Lowering DPP4 concentration by pharmacological inhibition improves glucose homeostasis and exhibits beneficial effects to reduce hepatic fat content. As factors regulating the endogenous expression of Dpp4 are unknown, the aim of this study was to examine whether the Dpp4 expression is epigenetically regulated in response to dietary components. Primary hepatocytes were treated with different macronutrients, and Dpp4 mRNA levels and DPP4 activity were evaluated. Moreover, dietary low-protein intervention was conducted in New Zealand obese (NZO) mice, and subsequently, effects on Dpp4 expression, methylation as well as plasma concentration and activity were determined. Our results indicate that Dpp4 mRNA expression is mediated by DNA methylation in several tissues. We therefore consider the Dpp4 southern shore as tissue differentially methylated region. Amino acids increased Dpp4 expression in primary hepatocytes, whereas glucose and fatty acids were without effect. Dietary protein restriction in NZO mice increased Dpp4 DNA methylation in liver leading to diminished Dpp4 expression and consequently to lowered plasma DPP4 activity. We conclude that protein restriction in the adolescent and adult states is a sufficient strategy to reduce DPP4 which in turn contributes to improve glucose homeostasis. (C) 2018 Published by Elsevier Inc.},
  language  = {en}
}
@article{LaegerCastanoMartinezWernoetal.2018,
  author    = {Laeger, Thomas and Castano-Martinez, Teresa and Werno, Martin W. and Japtok, Lukasz and Baumeier, Christian and Jonas, Wenke and Kleuser, Burkhard and Sch{\"u}rmann, Annette},
  title     = {Dietary carbohydrates impair the protective effect of protein restriction against diabetes in NZO mice used as a model of type 2 diabetes},
  series = {Diabetologia : journal of the European Association for the Study of Diabetes (EASD)},
  volume    = {61},
  journal   = {Diabetologia : journal of the European Association for the Study of Diabetes (EASD)},
  number    = {6},
  publisher = {Springer},
  address   = {New York},
  issn      = {0012-186X},
  doi       = {10.1007/s00125-018-4595-1},
  pages     = {1459 -- 1469},
  year      = {2018},
  abstract  = {Aims/hypothesis Low-protein diets are well known to improve glucose tolerance and increase energy expenditure. Increases in circulating fibroblast growth factor 21 (FGF21) have been implicated as a potential underlying mechanism. Methods We aimed to test whether low-protein diets in the context of a high-carbohydrate or high-fat regimen would also protect against type 2 diabetes in New Zealand Obese (NZO) mice used as a model of polygenetic obesity and type 2 diabetes. Mice were placed on high-fat diets that provided protein at control (16 kJ\%; CON) or low (4 kJ\%; low-protein/high-carbohydrate [LP/HC] or low-protein/high-fat [LP/HF]) levels. Results Protein restriction prevented the onset of hyperglycaemia and beta cell loss despite increased food intake and fat mass. The effect was seen only under conditions of a lower carbohydrate/fat ratio (LP/HF). When the carbohydrate/fat ratio was high (LP/HC), mice developed type 2 diabetes despite the robustly elevated hepatic FGF21 secretion and increased energy expenditure. Conclusion/interpretation Prevention of type 2 diabetes through protein restriction, without lowering food intake and body fat mass, is compromised by high dietary carbohydrates. Increased FGF21 levels and elevated energy expenditure do not protect against hyperglycaemia and type 2 diabetes per se.},
  language  = {en}
}