@phdthesis{Loeffler2019,
  author    = {L{\"o}ffler, Mona Christina},
  title     = {Protein kinase D1 deletion in adipocytes enhances energy dissipation and protects against adiposity},
  doi       = {10.25972/OPUS-18859},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188593},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Adaptation to alterations in nutrient availability ensures the survival of organisms. In vertebrates, adipocytes play a decisive role in this process due to their ability to store large amounts of excess nutrients and release them in times of food deprivation. In todays western world, a rather unlimited excess of nutrients leads to high-caloric food consumption in humans. Nutrient overload together with a decreased energy dissipation result in obesity as well as associated diseases such as insulin resistance, diabetes, and liver steatosis. Obesity causes a hormonal imbalance, which in combination with altered nutrient levels can aberrantly activate G-protein coupled receptors utilizing diacylglycerol (DAG) as secondary messenger. Protein kinase D (PKD) 1 is a DAG effector integrating multiple hormonal and nutritional inputs. Nevertheless, its physiological role in adipocytes has not been investigated so far. In this thesis, evidence is provided that the deletion of PKD1 in adipocytes suppresses lipogenesis as well as the accumulation of triglycerides. Furthermore, PKD1 depletion results in increased mitochondrial biogenesis as well as decoupling activity. Moreover, PKD1 deletion promotes the expression of the β3-adrenergic receptor (ADRB3) in a CCAAT/enhancer-binding protein (C/EBP)-α and δ-dependent manner. This results in elevated expression levels of beige markers in adipocytes in the presence of a β-agonist. Contrarily, adipocytes expressing a constitutive active form of PKD1 present a reversed phenotype. Additionally, PKD1 regulates adipocyte metabolism in an AMP-activated protein kinase (AMPK)-dependent manner by suppressing its activity through phosphorylation of AMPK α1/α2 subunits. Thus, PKD1 deletion results in an enhanced activity of the AMPK complex. Consistent with the in vitro findings, mice lacking PKD1 in adipocytes demonstrate a resistance to high-fat diet-induced obesity due to an elevated energy expenditure caused by trans-differentiation of white into beige adipocytes. Moreover, deletion of PKD1 in murine adipocytes improves systemic insulin sensitivity and ameliorates liver steatosis. Finally, PKD1 levels positively correlate with HOMA-IR as well as insulin levels in human subjects. Furthermore, inhibition of PKD1 in human adipocytes leads to metabolic alterations, which are comparable to the alterations seen in their murine counterparts. Taken together, these data demonstrate that PKD1 suppresses energy dissipation, drives lipogenesis, and adiposity. Therefore, increased energy dissipation induced by several complementary mechanisms upon PKD1 deletion might represent an attractive strategy to treat obesity and its related complications.},
  subject      = {Proteinkinase D},
  language  = {en}
}
@article{HoffmannEtzrodtWillkommetal.2015,
  author    = {Hoffmann, Linda S. and Etzrodt, Jennifer and Willkomm, Lena and Sanyal, Abhishek and Scheja, Ludger and Fischer, Alexander W. C. and Stasch, Johannes-Peter and Bloch, Wilhelm and Friebe, Andreas and Heeren, Joerg and Pfeifer, Alexander},
  title     = {Stimulation of soluble guanylyl cyclase protects against obesity by recruiting brown adipose tissue},
  series = {Nature Communications},
  volume    = {6},
  journal   = {Nature Communications},
  number    = {7235},
  doi       = {10.1038/ncomms8235},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143127},
  year      = {2015},
  abstract  = {Obesity is characterized by a positive energy balance and expansion of white adipose tissue (WAT). In contrast, brown adipose tissue (BAT) combusts energy to produce heat. Here we show that a small molecule stimulator (BAY 41-8543) of soluble guanylyl cyclase (sGC), which produces the second messenger cyclic GMP (cGMP), protects against diet-induced weight gain, induces weight loss in established obesity, and also improves the diabetic phenotype. Mechanistically, the haeme-dependent sGC stimulator BAY 41-8543 enhances lipid uptake into BAT and increases whole-body energy expenditure, whereas ablation of the haeme-containing \(\beta\)\(_{1}\)-subunit of sGC severely impairs BAT function. Notably, the sGC stimulator enhances differentiation of human brown adipocytes as well as induces 'browning' of primary white adipocytes. Taken together, our data suggest that sGC is a potential pharmacological target for the treatment of obesity and its comorbidities.},
  language  = {en}
}