@article{MayerLoefflerLozaValdesetal.2019, author = {Mayer, Alexander E. and L{\"o}ffler, Mona C. and Loza Vald{\´e}s, Angel E. and Schmitz, Werner and El-Merahbi, Rabih and Trujillo-Viera, Jonathan and Erk, Manuela and Zhang, Thianzhou and Braun, Ursula and Heikenwalder, Mathias and Leitges, Michael and Schulze, Almut and Sumara, Grzegorz}, title = {The kinase PKD3 provides negative feedback on cholesterol and triglyceride synthesis by suppressing insulin signaling}, series = {Science Signaling}, journal = {Science Signaling}, edition = {accepted manuscript}, doi = {10.1126/scisignal.aav9150}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250025}, year = {2019}, abstract = {Hepatic activation of protein kinase C (PKC) isoforms by diacylglycerol (DAG) promotes insulin resistance and contributes to the development of type 2 diabetes (T2D). The closely related protein kinase D (PKD) isoforms act as effectors for DAG and PKC. Here, we showed that PKD3 was the predominant PKD isoform expressed in hepatocytes and was activated by lipid overload. PKD3 suppressed the activity of downstream insulin effectors including the kinase AKT and mechanistic target of rapamycin complex 1 and 2 (mTORC1 and mTORC2). Hepatic deletion of PKD3 in mice improved insulin-induced glucose tolerance. However, increased insulin signaling in the absence of PKD3 promoted lipogenesis mediated by SREBP (sterol regulatory element-binding protein) and consequently increased triglyceride and cholesterol content in the livers of PKD3-deficient mice fed a high-fat diet. Conversely, hepatic-specific overexpression of a constitutively active PKD3 mutant suppressed insulin-induced signaling and caused insulin resistance. Our results indicate that PKD3 provides feedback on hepatic lipid production and suppresses insulin signaling. Therefore, manipulation of PKD3 activity could be used to decrease hepatic lipid content or improve hepatic insulin sensitivity.}, language = {en} } @article{BensaadFavaroLewisetal.2014, author = {Bensaad, Karim and Favaro, Elena and Lewis, Caroline A. and Peck, Barrie and Lord, Simon and Collins, Jennifer M. and Pinnick, Katherine E. and Wigfield, Simon and Buffa, Francesca M. and Li, Ji-Liang and Zhang, Qifeng and Wakelam, Michael J. O. and Karpe, Fredrik and Schulze, Almut and Harris, Adrian L.}, title = {Fatty Acid Uptake and Lipid Storage Induced by HIF-1 alpha Contribute to Cell Growth and Survival after Hypoxia-Reoxygenation}, series = {Cell Reports}, volume = {9}, journal = {Cell Reports}, number = {1}, issn = {2211-1247}, doi = {10.1016/j.celrep.2014.08.056}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115162}, pages = {349-365}, year = {2014}, abstract = {An in vivo model of antiangiogenic therapy allowed us to identify genes upregulated by bevacizumab treatment, including Fatty Acid Binding Protein 3 (FABP3) and FABP7, both of which are involved in fatty acid uptake. In vitro, both were induced by hypoxia in a hypoxia-inducible factor-1 alpha (HIF-1 alpha)-dependent manner. There was a significant lipid droplet (LD) accumulation in hypoxia that was time and O-2 concentration dependent. Knockdown of endogenous expression of FABP3, FABP7, or Adipophilin (an essential LD structural component) significantly impaired LD formation under hypoxia. We showed that LD accumulation is due to FABP3/7-dependent fatty acid uptake while de novo fatty acid synthesis is repressed in hypoxia. We also showed that ATP production occurs via beta-oxidation or glycogen degradation in a cell-type-dependent manner in hypoxia-reoxygenation. Finally, inhibition of lipid storage reduced protection against reactive oxygen species toxicity, decreased the survival of cells subjected to hypoxia-reoxygenation in vitro, and strongly impaired tumorigenesis in vivo.}, language = {en} }