Background: Enzymes of the FAH superfamily catalyze a multitude of diverse chemical reactions. Results: Using molecular modeling followed by biochemical investigations, FAHD1 was identified as oxaloacetate decarboxylase. Conclusion: Our findings suggest that ODx activity can be found in eukaryotic members of the FAH superfamily. Significance: Our results identify a mammalian ODx enzyme as a so far undescribed player in mitochondrial metabolism.

Highlights► Proteomic analysis of senescent secretome reveals upregulation of IGFBP-6 in fibroblasts. ► IGFBP-6 knockdown induces premature senescence in young fibroblasts. ► IGFBP-6 lentiviral overexpression delays replicative senescence in fibroblasts.

Introduction !ROS induce damage to biological systems and were shown to contribute to ageing in cells. Aberrant ROS levels are linked to a variety of cancers [1] and many other diseases, e.g., vascular disease [2][3][4][5][6]. Whereas ROS are obligatory byproducts of mitochondrial oxidative metabolism, Nox2, the founding member of the Nox family [7,8], was found responsible for the oxidative burst of phagocytes, where ROS are deliberately produced by Nox2 to enforce pathogen elimination [7,8]. In humans, the Nox family consists of seven enzymes, i.e., five NADPH oxidases (Nox1 through Nox5; for review, see [7,9]) and two Nox homologues (Duox1 and Duox2) [10], along with several subunits and regulatory proteins. All Nox proteins are transmembrane proteins with six (Nox1-Nox5) or seven (Duox1,2) transmembrane domains. In each case, four conserved histidines Abstract ! NADPH oxidases transport electrons from cytosolic NADPH through biological membranes to generate reactive oxygen species. NADPH oxidase 4, broadly expressed in humans, is an interesting pharmacological target, since its activity is deregulated in several diseases, including pulmonary fibrosis, diabetic nephropathy, and cardiac hypertrophy. Whereas several candidate NADPH oxidase 4 inhibitors were recently described, most of these compounds are either unspecific or toxic. Here we set out to identify new NADPH oxidase 4 inhibitors from edible plants, in an attempt to decrease the number of hits with toxic side effects. We screened a compound library prepared from edible plants for new bioactives with the ability to inhibit the activity of NADPH oxidase 4. Using both cell-based and cell-free assays, we identified several compounds with significant inhibitory activity towards NADPH oxidase 4. For selected compounds, the activity profile towards NADPH oxidase 2 and NADPH oxidase 5 was established, and controls were carried out to exclude general reactive oxygen species scavengers. A number of promising NADPH oxidase 4 inhibitors from edible plants was identified and characterised. Several new chemical entities are disclosed which act as NADPH oxidase 4 inhibitors, and the efficacies of our best hits, in particular several diarylheptanoids and lignans, are comparable to the best available pharmacological NADPH oxidase 4 inhibitors. These findings will provide valuable tools to study mechanisms of NADPH oxidase inhibition. Abbreviations

Mitotic cells in culture show a limited replicative potential and after extended subculturing undergo a terminal growth arrest termed cellular senescence. When cells reach the senescent phenotype, this is accompanied by a significant change in the cellular phenotype and massive changes in gene expression, including the upregulation of secreted factors. In human fibroblasts, senescent cells also acquire resistance to apoptosis. In contrary, in human endothelial cells, both replicative and stress-induced premature senescence is accompanied by increased cell death; however mechanisms of cell death are poorly explored. In this communication, we addressed the role of endonuclease G (EndoG), a mitochondrial mediator of caspase-independent cell death, in senescence-associated cell death of human endothelial cells. Using immunofluorescence microscopy, we found, that EndoG is localized in the mitochondria in young cells, but relocalizes to the nucleus upon senescence. When EndoG gene expression was downregulated by lentiviral shRNA vectors, we found a significant reduction in the replicative life span and a corresponding increase in cell death. We also observed a slight shift in the cell death phenotype from necrosis to apoptosis. Together these observations suggest an important role of EndoG in the senescence program of human endothelial cells.3