TY - JOUR A1 - Wei, Xiaoyan A1 - Franke, Julia A1 - Ost, Mario A1 - Wardelmann, Kristina A1 - Börno, Stefan A1 - Timmermann, Bernd A1 - Meierhofer, David A1 - Kleinridders, Andre A1 - Klaus, Susanne A1 - Stricker, Sigmar T1 - Cell autonomous requirement of neurofibromin (Nf1) for postnatal muscle hypertrophic growth and metabolic homeostasis JF - Journal of cachexia, sarcopenia and muscle N2 - Background Neurofibromatosis type 1 (NF1) is a multi-organ disease caused by mutations in neurofibromin 1 (NF1). Amongst other features, NF1 patients frequently show reduced muscle mass and strength, impairing patients' mobility and increasing the risk of fall. The role of Nf1 in muscle and the cause for the NF1-associated myopathy are mostly unknown. Methods To dissect the function ofNf1in muscle, we created muscle-specific knockout mouse models for NF1, inactivatingNf1in the prenatal myogenic lineage either under the Lbx1 promoter or under the Myf5 promoter. Mice were analysed during prenatal and postnatal myogenesis and muscle growth. Results Nf1(Lbx1)and Nf1(Myf5)animals showed only mild defects in prenatal myogenesis. Nf1(Lbx1)animals were perinatally lethal, while Nf1(Myf5)animals survived only up to approximately 25 weeks. A comprehensive phenotypic characterization of Nf1(Myf5)animals showed decreased postnatal growth, reduced muscle size, and fast fibre atrophy. Proteome and transcriptome analyses of muscle tissue indicated decreased protein synthesis and increased proteasomal degradation, and decreased glycolytic and increased oxidative activity in muscle tissue. High-resolution respirometry confirmed enhanced oxidative metabolism in Nf1(Myf5)muscles, which was concomitant to a fibre type shift from type 2B to type 2A and type 1. Moreover, Nf1(Myf5)muscles showed hallmarks of decreased activation of mTORC1 and increased expression of atrogenes. Remarkably, loss of Nf1 promoted a robust activation of AMPK with a gene expression profile indicative of increased fatty acid catabolism. Additionally, we observed a strong induction of genes encoding catabolic cytokines in muscle Nf1(Myf5)animals, in line with a drastic reduction of white, but not brown adipose tissue. Conclusions Our results demonstrate a cell autonomous role for Nf1 in myogenic cells during postnatal muscle growth required for metabolic and proteostatic homeostasis. Furthermore, Nf1 deficiency in muscle drives cross-tissue communication and mobilization of lipid reserves. KW - neurofibromatosis KW - NF1 KW - myopathy KW - muscle atrophy KW - muscle metabolism KW - muscle fibre type KW - AMPK Y1 - 2020 U6 - https://doi.org/10.1002/jcsm.12632 SN - 2190-5991 SN - 2190-6009 VL - 11 IS - 6 SP - 1758 EP - 1778 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Linke, Christian A1 - Wösle, Markus A1 - Harder, Anja T1 - Anti-cancer agent 3-bromopyruvate reduces growth of MPNST and inhibits metabolic pathways in a representative in-vitro model JF - BMC cancer N2 - Background Anticancer compound 3-bromopyruvate (3-BrPA) suppresses cancer cell growth via targeting glycolytic and mitochondrial metabolism. The malignant peripheral nerve sheath tumor (MPNST), a very aggressive, therapy resistant, and Neurofibromatosis type 1 associated neoplasia, shows a high metabolic activity and affected patients may therefore benefit from 3-BrPA treatment. To elucidate the specific mode of action, we used a controlled cell model overexpressing proteasome activator (PA) 28, subsequently leading to p53 inactivation and oncogenic transformation and therefore reproducing an important pathway in MPNST and overall tumor pathogenesis. Methods Viability of MPNST cell lines S462, NSF1, and T265 in response to increasing doses (0-120 mu M) of 3-BrPA was analyzed by CellTiter-Blue (R) assay. Additionally, we investigated viability, reactive oxygen species (ROS) production (dihydroethidium assay), nicotinamide adenine dinucleotide dehydrogenase activity (NADH-TR assay) and lactate production (lactate assay) in mouse B8 fibroblasts overexpressing PA28 in response to 3-BrPA application. For all experiments normal and nutrient deficient conditions were tested. MPNST cell lines were furthermore characterized immunohistochemically for Ki67, p53, bcl2, bcl6, cyclin D1, and p21. Results MPNST significantly responded dose dependent to 3-BrPA application, whereby S462 cells were most responsive. Human control cells showed a reduced sensitivity. In PA28 overexpressing cancer cell model 3-BrPA application harmed mitochondrial NADH dehydrogenase activity mildly and significantly failed to inhibit lactate production. PA28 overexpression was associated with a functional glycolysis as well as a partial resistance to stress provoked by nutrient deprivation. 3-BrPA treatment was not associated with an increase of ROS. Starvation sensitized MPNST to treatment. Conclusions Aggressive MPNST cells are sensitive to 3-BrPA therapy in-vitro with and without starvation. In a PA28 overexpression cancer cell model leading to p53 inactivation, thereby reflecting a key molecular feature in human NF1 associated MPNST, known functions of 3-BrPA to block mitochondrial activity and glycolysis were reproduced, however oncogenic cells displayed a partial resistance. To conclude, 3-BrPA was sufficient to reduce NF1 associated MPNST viability potentially due inhibition of glycolysis which should lead to the initiation of further studies and promises a potential benefit for NF1 patients. KW - MPNST KW - NF1 KW - 3-BrPA KW - glycolysis KW - mitochondrial respiration KW - p53 KW - starvation KW - cell cycle KW - PA28 KW - B8 fibroblasts Y1 - 2020 U6 - https://doi.org/10.1186/s12885-020-07397-w SN - 1471-2407 VL - 20 IS - 1 PB - BioMed Central CY - London ER -