Mitochondrial phospholipid homeostasis is regulated by the i-AAA protease PaIAP and affects organismic aging

Mitochondria are ubiquitous organelles of eukaryotic organisms with a number of essential functions, including synthesis of iron-sulfur clusters, amino acids, lipids, and adenosine triphosphate (ATP). During aging of the fungal aging model Podospora anserina, the inner mitochondrial membrane (IMM) undergoes prominent morphological alterations, ultimately resulting in functional impairments. Since phospholipids (PLs) are key components of biological membranes, maintenance of membrane plasticity and integrity via regulation of PL biosynthesis is indispensable. Here, we report results from a lipidomic analysis of isolated mitochondria from P. anserina that revealed an age-related reorganization of the mitochondrial PL profile and the involvement of the i-AAA protease PaIAP in proteolytic regulation of PL metabolism. The absence of PaIAP enhances biosynthesis of characteristic mitochondrial PLs, leads to significant alterations in the acyl composition of the mitochondrial signature PL cardiolipin (CL), and induces mitophagy. These alterations presumably cause the lifespan increase of the PaIap deletion mutant under standard growth conditions. However, PaIAP is required at elevated temperatures and for degradation of superfluous CL synthase PaCRD1 during glycolytic growth. Overall, our study uncovers a prominent role of PaIAP in the regulation of PL homeostasis in order to adapt membrane plasticity to fluctuating environmental conditions as they occur in nature

Cerebral mitochondrial function and cognitive performance during aging: a longitudinal study in NMRI mice

Brain aging is one of the major risk factors for the development of several neurodegenerative diseases. Therefore, mitochondrial dysfunction plays an important role in processes of both, brain aging and neurodegeneration. Aged mice including NMRI mice are established model organisms to study physiological and molecular mechanisms of brain aging. However, longitudinal data evaluated in one cohort are rare but are important to understand the aging process of the brain throughout life, especially since pathological changes early in life might pave the way to neurodegeneration in advanced age. To assess the longitudinal course of brain aging, we used a cohort of female NMRI mice and measured brain mitochondrial function, cognitive performance, and molecular markers every 6 months until mice reached the age of 24 months. Furthermore, we measured citrate synthase activity and respiration of isolated brain mitochondria. Mice at the age of three months served as young controls. At six months of age, mitochondria-related genes (complex IV, creb-1, β-AMPK, and Tfam) were significantly elevated. Brain ATP levels were significantly reduced at an age of 18 months while mitochondria respiration was already reduced in middle-aged mice which is in accordance with the monitored impairments in cognitive tests. mRNA expression of genes involved in mitochondrial biogenesis (cAMP response element-binding protein 1 (creb-1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), nuclear respiratory factor-1 (Nrf-1), mitochondrial transcription factor A (Tfam), growth-associated protein 43 (GAP43), and synaptophysin 1 (SYP1)) and the antioxidative defense system (catalase (Cat) and superoxide dismutase 2 (SOD2)) was measured and showed significantly decreased expression patterns in the brain starting at an age of 18 months. BDNF expression reached, a maximum after 6 months. On the basis of longitudinal data, our results demonstrate a close connection between the age-related decline of cognitive performance, energy metabolism, and mitochondrial biogenesis during the physiological brain aging process

Cerebral Mitochondrial Function and Cognitive Performance during Aging: A Longitudinal Study in NMRI Mice

Brain aging is one of the major risk factors for the development of several neurodegenerative diseases. Therefore, mitochondrial dysfunction plays an important role in processes of both, brain aging and neurodegeneration. Aged mice including NMRI mice are established model organisms to study physiological and molecular mechanisms of brain aging. However, longitudinal data evaluated in one cohort are rare but are important to understand the aging process of the brain throughout life, especially since pathological changes early in life might pave the way to neurodegeneration in advanced age. To assess the longitudinal course of brain aging, we used a cohort of female NMRI mice and measured brain mitochondrial function, cognitive performance, and molecular markers every 6 months until mice reached the age of 24 months. Furthermore, we measured citrate synthase activity and respiration of isolated brain mitochondria. Mice at the age of three months served as young controls. At six months of age, mitochondria-related genes (complex IV, creb-1, β-AMPK, and Tfam) were significantly elevated. Brain ATP levels were significantly reduced at an age of 18 months while mitochondria respiration was already reduced in middle-aged mice which is in accordance with the monitored impairments in cognitive tests. mRNA expression of genes involved in mitochondrial biogenesis (cAMP response element-binding protein 1 (creb-1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), nuclear respiratory factor-1 (Nrf-1), mitochondrial transcription factor A (Tfam), growth-associated protein 43 (GAP43), and synaptophysin 1 (SYP1)) and the antioxidative defense system (catalase (Cat) and superoxide dismutase 2 (SOD2)) was measured and showed significantly decreased expression patterns in the brain starting at an age of 18 months. BDNF expression reached, a maximum after 6 months. On the basis of longitudinal data, our results demonstrate a close connection between the age-related decline of cognitive performance, energy metabolism, and mitochondrial biogenesis during the physiological brain aging process

CLiB – a novel cardiolipin-binder isolated via data-driven and in vitro screening

Cardiolipin, the mitochondria marker lipid, is crucially involved in stabilizing the inner mitochondrial membrane and is vital for the activity of mitochondrial proteins and protein complexes. Directly targeting cardiolipin by a chemical-biology approach and thereby altering the cellular concentration of “available” cardiolipin eventually allows to systematically study the dependence of cellular processes on cardiolipin availability. In the present study, physics-based coarse-grained free energy calculations allowed us to identify the physical and chemical properties indicative of cardiolipin selectivity and to apply these to screen a compound database for putative cardiolipin-binders. The membrane binding properties of the 22 most promising molecules identified in the in silico approach were screened in vitro, using model membrane systems finally resulting in the identification of a single molecule, CLiB (CardioLipin-Binder). CLiB clearly affects respiration of cardiolipin-containing intact bacterial cells as well as of isolated mitochondria. Thus, the structure and function of mitochondrial membranes and membrane proteins might be (indirectly) targeted and controlled by CLiB for basic research and, potentially, also for therapeutic purposes

MH84 improves mitochondrial dysfunction in a mouse model of early Alzheimer’s disease

Abstract Background Current approved drugs for Alzheimer’s disease (AD) only attenuate symptoms, but do not cure the disease. The pirinixic acid derivate MH84 has been characterized as a dual gamma-secretase/proliferator activated receptor gamma (PPARγ) modulator in vitro. Pharmacokinetic studies in mice showed that MH84 is bioavailable after oral administration and reaches the brain. We recently demonstrated that MH84 improved mitochondrial dysfunction in a cellular model of AD. In the present study, we extended the pharmacological characterization of MH84 to 3-month-old Thy-1 AβPPSL mice (harboring the Swedish and London mutation in human amyloid precursor protein (APP)) which are characterized by enhanced AβPP processing and cerebral mitochondrial dysfunction, representing a mouse model of early AD. Methods Three-month-old Thy-1 AβPPSL mice received 12 mg/kg b.w. MH84 by oral gavage once a day for 21 days. Mitochondrial respiration was analyzed in isolated brain mitochondria, and mitochondrial membrane potential and ATP levels were determined in dissociated brain cells. Citrate synthase (CS) activity was determined in brain tissues and MitoTracker Green fluorescence was measured in HEK293-AβPPwt and HEK293-AβPPsw cells. Soluble Aβ1–40 and Aβ1–42 levels were determined using ELISA. Western blot analysis and qRT-PCR were used to measure protein and mRNA levels, respectively. Results MH84 reduced cerebral levels of the β-secretase-related C99 peptide and of Aβ40 levels. Mitochondrial dysfunction was ameliorated by restoring complex IV (cytochrome-c oxidase) respiration, mitochondrial membrane potential, and levels of ATP. Induction of PPARγ coactivator-1α (PGC-1α) mRNA and protein expression was identified as a possible mode of action that leads to increased mitochondrial mass as indicated by enhanced CS activity, OXPHOS levels, and MitoTracker Green fluorescence. Conclusions MH84 modulates β-secretase processing of APP and improves mitochondrial dysfunction by a PGC-1α-dependent mechanism. Thus, MH84 seems to be a new promising therapeutic agent with approved in-vivo activity for the treatment of AD

Les propositions de la revue à mi-parcours de la PAC sont explicitées

Le Commissaire pour l'agriculture Franz Fischler a souligné les conclusions des récentes études d'impact et les raisons qui justifient les propositions réglementaires pour des réformes supplémentaires de la PAC présentées par l'UE au Parlement européen le 22 janvier 2003. Il a insisté sur le fait que ces propositions : * supprimeraient les déséquilibres structurels sur les marchés du seigle, du boe uf et du riz ; * ne conduiraient pas, en raison du découplage, à un abandon massif de la production, mais relancerait au contraire les revenus des producteurs dans la mesure où ceux-ci pourraient s'orienter vers des productions plus rentables. Il a aussi souligné deux modifications notables dans les réglementations proposées, par rapport à celles de juin 2002, à savoir l'adoption d'une proposition de réforme du régime laitier et des changements importants aux accords sur la modulation dynamique. Les contraintes budgétaires de l'UE n'ont pas permis de faire avancer la réforme du secteur laitier. Les propositions spécifiques formulées pour ce secteur comprennent les mesures suivantes : * extension du système de quotas jusqu'en 2014 ; * réduction supplémentaire du soutien des prix du lait et augmentation des quotas de 1% par an en 2007 et 2008 dans l'UE à 25 ; * réduction des prix d'intervention de 3,5% par an pour le lait écrémé en poudre ; * réduction de 7% par an des prix d'intervention sur le beurre ; * compensation des réductions de prix pour les producteurs de lait à hauteur de 58% des réduction de prix. Le Commissaire Fischler a estimé que ces propositions devraient rendre le secteur laitier de l'UE plus compétitif et donnera l'UE une plus grande marge de manoe uvre à l'OMC. Les propositions de modulation dynamique comprennent les éléments suivants : * pas de réduction de paiements pour les agriculteurs qui reçoivent jusqu'à 5 000 € ; * 12.5% réduction pour les agriculteurs qui reçoivent entre 5 000 et 50 000 € ; * 19% de réduction pour les agriculteurs qui reçoivent plus de 50 000 € . 6% environ de l'ensemble des économies ainsi réalisées seront affectés au développement rural, le reste servira à financer des réformes ultérieures et à assister les agriculteurs en grande difficulté. Le Commissaire a expliqué le fonctionnement du découplage en termes simples: 'Pour chaque exploitation, les versements directs actuellement dus seront regroupés en un seul versement dont le niveau sera basé sur les montants perçus pendant la période 2000-2002 au titre des droits acquis dans le dispositif actuel. Tous les critères sur lesquels ce soutien était basé pendant la période de référence seront pris en compte ( zone de paiements, têtes de bétail, paiements par tonne etc.). Ces paiements seraient conditionnés à la conformité avec des standards obligatoires en matière de protection de l'environnement, de sécurité alimentaire, de santé animale et de sécurité en matière de bien-être et d'emploi. Ce soutien serait supprimé en cas de non conformité. Pour facilité le transfert des droits de paiement d'une exploitation à une autre, ces droits devront faire l'objet d'un calcul basé sur une division du niveau de paiement par exploitation par la taille de la zone sur laquelle les paiements étaient basés. Ainsi les zones de pâturages, de céréales et de d'oléagineux seraient concernés, mais pas les zones utilisées pour cultiver de la canne à sucre ou des pommes de terre.' Les Etats-membres seraient autorisés à mettre en place ce dispositif en fonction des circonstances régionales qui détermineront les principes de conformité croisée à appliquer. Il a souligné le fait que les propositions de la Commission n'entraîneraient pas de découplage dans tous les secteurs, car cela pourrait conduire à des baisses de production inacceptables pour certains produits. En conséquence, certaines aides pourraient continuer à être liées à la production, notamment le blé dur, la fécule de pomme de terre, le riz et les protéines alimentaires. En fait, le découplage ne serait introduit que dans la mesure où il est nécessaire pour atteindre les objectifs de l'UE, s'agissant notamment de la reconnaissance internationale et de l'acceptation du système de soutien de l'UE. Quant à l'OMC, le Commissaire Fischler estime que si l'UE faisait preuve d'initiative, il serait plus facile de protéger le modèle agricole européen et sécuriser l'acceptation internationale des positions de l'UE sur les questions non commerciales. Comment: Il faut noter que le recours aux économies sur le budget de l'UE pour faire avancer la réforme du secteur laitier signifie que celle du secteur du sucre pourrait bien être à nouveau reportée. En soulignant que le découplage pourrait n'être introduit que s'il est nécessaire à l'atteinte des objectifs de l'UE, comme l'assurance d'une approbation internationale du dispositif UE de soutien, le Commissaire a clairement indiqué qu'il ne permettrait pas qu'une réforme menace d'une quelconque façon des produits UE couverts par la PAC. Cela indique concrètement les limites qui sont mises à l'extension de la réforme de la PAC et aux réductions des aides publiques de l'UE au secteur agricole.Le Commissaire pour l'agriculture Franz Fischler a..

Additional file 3: Figure S3. of MH84 improves mitochondrial dysfunction in a mouse model of early Alzheimer’s disease

Western blot analysis of A brain-derived neurotrophic factor (BDNF), B Growth associated protein 43 (GAP43), and C synaptophysin in brain homogenate isolated from wild-type mice (control), Thy-1 AβPPSL (control), and MH-84-treated Thy-1 AβPPSL (MH84) mice. Tubulin (A, C) and GAPDH (B) were used as loading controls. Data represent means ± SEM. N = 11 (six females, five males); one-way ANOVA with Tukey’s multiple comparison post test (***p < 0.001, **p < 0.01, against wild-type(control); +p < 0.05 against Thy-1 AβPPSL (control)). (TIFF 12802 kb