Mutant Lef1 controls Gata6 in sebaceous gland development and cancer

UK Medical Research Council (G1100073)Wellcome Trust (096540/Z/ 11/Z

Detection of IL28B SNP DNA from Buccal Epithelial Cells, Small Amounts of Serum, and Dried Blood Spots

Background & Aims: Point mutations in the coding region of the interleukin 28 gene (rs12979860) have recently been identified for predicting the outcome of treatment of hepatitis C virus infection. This polymorphism detection was based on whole blood DNA extraction. Alternatively, DNA for genetic diagnosis has been derived from buccal epithelial cells (BEC), dried blood spots (DBS), and genomic DNA from serum. The aim of the study was to investigate the reliability and accuracy of alternative routes of testing for single nucleotide polymorphism allele rs12979860CC. Methods: Blood, plasma, and sera samples from 200 patients were extracted (400 mL). Buccal smears were tested using an FTA card. To simulate postal delay, we tested the influence of storage at ambient temperature on the different sources of DNA at five time points (baseline, 48 h, 6 days, 9 days, and 12 days) Results: There was 100 % concordance between blood, plasma, sera, and BEC, validating the use of DNA extracted from BEC collected on cytology brushes for genetic testing. Genetic variations in HPTR1 gene were detected using smear technique in blood smear (3620 copies) as well as in buccal smears (5870 copies). These results are similar to those for whole blood diluted at 1/10. A minimum of 0.04 mL, 4 mL, and 40 mL was necessary to obtain exploitable results respectively for whole blood, sera, and plasma. No significant variation between each time point was observed for the different sources of DNA. IL28B SNPs analysis at these different time points showed the same results using the four sources of DNA

Localization and processing of the amyloid-β protein precursor in mitochondria-associated membranes

Alteration of mitochondria-associated membranes (MAMs) has been proposed to contribute to the pathogenesis of Alzheimer’s disease (AD). We studied herein the subcellular distribution, the processing, and the protein interactome of the amyloid- protein precursor (AβPP) and its proteolytic products in MAMs. We reveal that A PP and its catabolites are present in MAMs in cellular models overexpressing wild type A PP or A PP harboring the double Swedish or Londonfamilial AD mutations, and in brains of transgenic mice model of AD. Furthermore, we evidenced that both - and -secretases are present and harbor A PP processing activities in MAMs. Interestingly, cells overexpressing APPsweshowincreased ER-mitochondria contact sites. We also document increased neutral lipid accumulation linked to A production and reversed by inhibiting -or -secretases. Using a proteomic approach, we show that A PP and its catabolites interact with key proteins of MAMs controlling mitochondria and ER functions. These data highlight the role of A PP processing and proteomic interactome in MAMs deregulation taking place in AD

Calcium signalling-dependent mitochondrial dysfunction and bioenergetics regulation in respiratory chain Complex II deficiency

International audienceDespite advanced knowledge on the genetic basis of oxidative phosphorylation (OXPHOS)-related diseases, the molecular and/or cellular determinants for tissue specific dysfunction are not completely understood. Here, we report the cellular events associated with mitochondrial respiratory Complex II deficiency occurring prior to cell death. Mutation or chronic inhibition of Complex II determined a large increase of basal and agonist-evoked Ca2+ signals in the cytosol and the mitochondria, in parallel with mitochondrial dysfunction characterized by membrane potential (∆ψmit) loss, [ATP] reduction and increased Reactive Oxygen Species (ROS) production. cytosolic and mitochondrial Ca2+ overload are linked to increased ER Ca2+ leakage, and to SERCA2b and PMCA proteasome-dependent degradation. Increased [Ca2+]mit is also contributed by decreased mitochondrial motility and increased ER-mitochondria contact sites. Interestingly, increased intracellular [Ca2+] activated on the one hand a compensatory Ca2+-dependent glycolytic ATP production and determined on the second hand mitochondrial pathology. These results revealed the primary role for Ca2+ signalling in the control of mitochondrial dysfunction and cellular bioenergetics outcomes linked to respiratory chain Complex II deficiency