Complexes between kinases, mitochondrial porin and adenylate translocator in rat brain resemble the permeability transition pore

AbstractIn vitro incubation of isolated hexokinase isozyme I or isolated dimer of mitochondrial creatine kinase with the outer mitochondrial membrane pore led to high molecular weight complexes of enzyme oligomers. Similar complexes of hexokinase and mitochondrial creatine kinase could be extracted by 0.5% Triton X-100 from homogenates of rat brain. Hexokinase and creatine kinase complexes could be separated by subsequent chromatography on DEAE anion exchanger. The molecular weight, as determined by gel-permeation chromatography, was approximately 400 kDa for both complexes. The Mr suggested tetramers of hexokinase (monomer 100 kDa) and creatine kinase (active enzyme is a dimer of 80 kDa). The composition of the complexes was further characterised by specific antibodies. Besides either hexokinase or creatine kinase molecules the complexes contained porin and adenylate translocator. It was possible to incorporate the complexes into artificial bilayer membranes and to measure conductance in 1 M KCl. The incorporating channels had a high conductance of 6 nS that was asymmetrically voltage dependent. The complexes were also reconstituted in phospholipid vesicles that were loaded with ATP. Complex containing vesicles retained ATP while vesicles reconstituted with pure porin were leaky. The internal ATP could be used by creatine kinase and hexokinase in the complex to phosphorylate external creatine or glucose. This process was inhibited by atractyloside. The hexokinase complex containing vesicles were furthermore loaded with malate or ATP that was gradually released by addition of Ca2+ between 100 and 600 μM. The liberation of malate or ATP by Ca2+ could be inhibited by N-methylVal-4-cyclosporin, suggesting that the porin translocator complex constitutes the permeability transition pore. The results show the physiological existence of kinase porin translocator complexes at the mitochondrial surface. It is assumed that such complexes between inner and outer membrane components are the molecular basis of contact sites observed by electron microscopy. Kinase complex formation may serve three regulatory functions, firstly regulation of the kinase activity, secondly stimulation of oxidative phosphorylation and thirdly regulation of the permeability transition pore

Disorders of compulsivity: a common bias towards learning habits.

Why do we repeat choices that we know are bad for us? Decision making is characterized by the parallel engagement of two distinct systems, goal-directed and habitual, thought to arise from two computational learning mechanisms, model-based and model-free. The habitual system is a candidate source of pathological fixedness. Using a decision task that measures the contribution to learning of either mechanism, we show a bias towards model-free (habit) acquisition in disorders involving both natural (binge eating) and artificial (methamphetamine) rewards, and obsessive-compulsive disorder. This favoring of model-free learning may underlie the repetitive behaviors that ultimately dominate in these disorders. Further, we show that the habit formation bias is associated with lower gray matter volumes in caudate and medial orbitofrontal cortex. Our findings suggest that the dysfunction in a common neurocomputational mechanism may underlie diverse disorders involving compulsion.This study was funded by the WT fellowship grant for VV (093705/Z/ 10/Z) and Cambridge NIHR Biomedical Research Centre. VV and NAH are Wellcome Trust (WT) intermediate Clinical Fellows. YW is supported by the Fyssen Fondation and MRC Studentships. PD is supported by the Gatsby Charitable Foundation. JEG has received grants from the National Institute of Drug Abuse and the National Center for Responsible Gaming. TWR and BJS are supported on a WT Programme Grant (089589/Z/09/Z). The BCNI is supported by a WT and MRC grant.This is the final published version. It's also available from Molecular Psychiatry at http://www.nature.com/mp/journal/vaop/ncurrent/full/mp201444a.html

Therapygenetic effects of 5-HTTLPR on cognitive-behavioral therapy in anxiety disorders: a meta-analysis

There is a recurring debate on the role of the serotonin transporter gene linked polymorphic region (5-HTTLPR) in the moderation of response to cognitive behavioral therapy (CBT) in anxiety disorders. Results, however, are still inconclusive. We here aim to perform a meta-analysis on the role of 5-HTTLPR in the moderation of CBT outcome in anxiety disorders. We investigated both categorical (symptom reduction of at least 50%) and dimensional outcomes from baseline to post-treatment and follow-up. Original data were obtained from ten independent samples (including three unpublished samples) with a total of 2,195 patients with primary anxiety disorder. No significant effects of 5-HTTLPR genotype on categorical or dimensional outcomes at post and follow-up were detected. We conclude that current evidence does not support the hypothesis of 5-HTTLPR as a moderator of treatment outcome for CBT in anxiety disorders. Future research should address whether other factors such as long-term changes or epigenetic processes may explain further variance in these complex gene-environment interactions and molecular-genetic pathways that may confer behavioral change following psychotherapy

Reconstituted adenine nucleotide translocase forms a channel for small molecules comparable to the mitochondrial permeability transition pore

AbstractHighly purified adenylate translocase (ANT) from rat heart mitochondria was functionally reconstituted as ATP/ADP exchange carrier in asolectin/cardiolipin vesicles. The ANT preparations used were free of porin, cyclophilin D, and Bax as analysed immunologically and by activity measurements. After pre-loading the ANT-containing proteoliposomes with ATP, malate or AMP, a gradual release of the trapped compounds by increasing the external Ca2+ concentrations could be demonstrated. N-Methyl-Val-4-cyclosporin did not inhibit the Ca2+ dependent release of internal substances from ANT liposomes. This inhibitor was found to be specific for the mitochondrial permeability transition pore (MTP) in intact mitochondria or reconstituted MTP-like protein complexes (e.g. hexokinase, porin, ANT complex). However, ADP in concentrations >20 μM inhibited the liberation of internal compounds, while in contrast, atractyloside (30 μM) and HgCl2 (5 μM) both induced permeability of the ANT-containing liposomes resulting in a release of trapped substances. These results strongly suggest that ANT itself is capable to adopt a pore-like structure under conditions known to induce the permeability transition in mitochondria

Early clinical outcome of aortic transcatheter valve-in-valve implantation in the Nordic countries

Objective: Transcatheter valve-in-valve implantation has emerged as an option, in addition to reoperative surgical aortic valve replacement, to treat failed biologic heart valve substitutes. However, the clinical experience with this approach is still limited. We report the comprehensive experience of transcatheter valve-in-valve implantation in the Nordic countries from May 2008 to January 2012. Methods: A total of 45 transcatheter aortic valve-in-valve implantations were performed during the study period in 11 centers. The mean age of the patients was 80.6 years (range, 61-91), 26 were male and 19 were female, and the mean EuroSCORE, EuroSCORE II, and Society of Thoracic Surgeons score was 35.4, 16.3, and 14.6, respectively. The type of failure was stenosis and combined in 58% (mean and peak aortic valve gradient, 77 and 45 mm Hg, respectively) and regurgitation in 42% of cases. The SAPIEN/XT (Edwards LifeSciences, Irvine, Calif) and CoreValve (Medtronic Inc, Minneapolis, Minn) system was used in 33 and 12 cases, respectively. The access route was transapical in 25, transfemoral in 17, transaortic in 2, and subclavian in 1 case. The mean follow-up was 14.4 months. The periprocedural and postoperative outcomes were assessed using the Valve Academic Research Consortium criteria. Results: No intraprocedural mortality occurred. The technical success rate was 95.6% (1 second valve implantation, 1 conversion to open surgery). The all-cause 30-day mortality was 4.4% (1 cardiac-related and 1 aspiration pneumonia). The major complications within 30 days included stroke in 2.2%, periprocedural myocardial infarction in 4.4%, and major vascular complication in 2.2% of patients. At 1 month, all but 1 patient had either no or mild paravalvular leakage, with a mean and peak valve gradient of 17 mm Hg (range, 4-38) and 30 mm Hg (range, 7-68), respectively. The mean gradient was greater than 20 mm Hg in 17% of patients and remained unchanged at 12 months. The 1-year survival was 88.1%. Conclusions: Transcatheter valve-in-valve implantation is widely performed, albeit in small numbers, in most centers in the Nordic countries. The short-termresults were excellent in this high-risk patient population, demonstrating a low incidence of device-or procedure-related complications. However, a considerable number of patients were left with suboptimal systolic valve performance with unknown long-term effects, warranting close surveillance after transcatheter valve-in-valve implantation