Class II phosphatidylinositol 3-kinase ß in nutrient signaling, endocytosis and centronuclear myopathy

To adapt to the availability of nutrients and growth factors, cells must sense these cues and adapt their metabolism and proliferation accordingly. Defects in these processes have been associated with many diseases ranging from diabetes to cancer. Nutrient signaling is controlled by the master regulator mTOR complex 1 (mTORC1). When nutrients and growth factors are readily available, mTORC1 localizes to lysosomes and phosphorylates target proteins initiating anabolic processes like protein translation and lipid synthesis and inhibiting catabolic processes like autophagy. Amino acids induce the translocation of mTORC1 to the lysosomal surface via the activity of Rag GTPases whereas growth factors lead to the activation of the small GTPase Rheb at the lysosome that interacts with mTORC1 to activate it. When growth factor levels are low, mTORC1 activity is inhibited by lysosomal PI(3,4)P2 through so far unknown mechanisms. PI(3,4)P2 is synthesized from PI(4)P by the class II PI 3- kinase β (PI3KC2β). PI3KC2β itself is inhibited by growth factor signaling. Active growth factor receptors promote the activity of the mTORC2 complex which then activates protein kinase N2 (PKN2) by phosphorylation. PKN2 in turn phosphorylates PI3KC2β in its unstructured N terminal domain, triggering the association of inhibitory 14-3-3 proteins that sequester PI3KC2β in the cytoplasm. How PI3KC2β is actively recruited to the lysosomal surface upon growth factor starvation was previously unknow. In this study I demonstrate that active, GTP bound Rab7A interacts with PI3KC2β and recruits it to the lysosomal surface upon growth factor starvation. Rab7A was required for the interaction of PI3KC2β with the mTORC1 subunit Raptor and PI3KC2β translocation to lysosome. Furthermore, lysosomal PI(3,4)P2 and mTORC1 inhibition depended on Rab7A activity. To further investigate the influence of PI3KC2β on mTORC1 composition, I generated a HEK293T cell line that endogenously expresses eGFP-Raptor using CRISPR/Cas9 mediated genome editing. This cell line allowed for the isolation of mTORC1 by immunoprecipitation. PI3KC2β depletion indeed altered the mTORC1 composition, as the interaction of the inhibitory subunit PRAS40 was reduced by 40 %. The exact mechanisms of this observation remain the subject of further studies. Beyond its role in mTORC1 signaling, PI3KC2β is known as an important regulator in x linked centronuclear myopathy (XLCNM). XLCNM is a severe muscular disorder caused by loss 12 of function mutations in the PI(3)P phosphatase MTM1. The depletion of PI3KC2β in MTM1 knock out mice prevents disease onset by hereto unknown mechanisms. MTM1 is required for the depletion of PI(3)P from recycling endosomes to enable the synthesis of PI(4)P by PI4KIIα which is in turn required for the recruitment of the exocyst complex and exocytosis of cargo destined for recycling. This leads to the endosomal accumulation of β1 integrins and triggers defects in muscle fiber generation through myoblast fusion, a process that depends on proper β1 integrin localization and activation. Using C2C12 myoblast cell lines harboring knockouts (KO) of MTM1, PI3KC2β or both MTM1 and PI3KC2β I could reproduce the myoblast fusion defect induced by MTM1 loss in a cellular model. Furthermore, I could confirm that MTM1 KO C2C12 cells had less active β1 integrin at the cell surface. Contrarily, HeLa cells depleted of PI3KC2β had elevated active β1 integrin surface levels and decreased rates of active β1 integrin endocytosis. Both findings could be rescued with the re-expression wild type PI3KC2β but not with kinase inactive PI3KC2β or a mutant that only synthesizes PI(3)P but not PI(3,4)P2. Thus PI3KC2β is required for active β1 integrin endocytosis trough the synthesis of PI(3,4)P2. In line with that, PI3KC2β localized to clathrin coated pits (CCPs) and co-immunoprecipitated with the integrin endocytosis adaptor Dab2 and the endocytic proteins clathrin heavy chain and intersectin-1. I therefore propose a model where MTM1 is required for active β1 integrin recycling and PI3KC2β is required for active β1 integrin endocytosis. If the recycling process fails due to MTM1 loss, active surface β1 integrin levels can be restored by depleting PI3KC2β and thus reducing the rate of β1 integrin endocytosis

Physiotherapie mit Kriegs- und Folteropfern : welchen Einfluss hat Basic Body Awareness Therapy (BBAT) auf physische und psychische Beschwerden sowie auf die Lebensqualität von Kriegs- und Folteropfern?

Darstellung des Themas: Weltweit sind 60 Millionen Menschen Opfer von Krieg und Folter. Viele dieser Menschen tragen komplexe physische und psychische Spuren davon. Basic Body Awareness Therapy (BBAT) könnte einen potentiellen Therapieansatz darstellen, um die physischen und psychischen Spätfolgen von Krieg und Folter zu behandeln. Zielsetzung: In der vorliegenden Arbeit soll untersucht werden, welchen Einfluss BBAT auf physische und psychische Beschwerden sowie auf die Lebensqualität von Kriegs- und Folteropfern hat. Daraus soll eine evidenzbasierte Empfehlung für die Physiotherapie hergeleitet werden. Methode: Die Literaturrecherche erfolgte in den Datenbanken AMED, CINAHL, MEDLINE und PsycINFO. Anhand vordefinierter Ein- und Ausschlusskriterien konnten zwei zur Beantwortung der Fragestellung relevante Studien gefunden und analysiert werden. Relevante Ergebnisse: In beiden Studien wurden qualitative Interviews durchgeführt. Sie deuten auf eine Verbesserung der physischen und psychischen Beschwerden sowie der Lebensqualität der Betroffenen hin. Die zusätzlichen quantitativen Daten konnten jedoch nur bezüglich der Bewegungsqualität, der Depression und der chronischen Schmerzen der Arme eine signifikante Verbesserung aufzeigen. Schlussfolgerung: BBAT scheint grundsätzlich einen positiven Einfluss auf physische und psychische Beschwerden sowie die Lebensqualität von Kriegs- und Folteropfern zu haben. Es kann derzeit jedoch keine allgemeingültige Aussage getroffen werden.Background: 60 million people around the world are victims of war and torture. Many of them bear highly complex physical and psychological traces. Basic Body Awareness Therapy (BBAT) might prove to be a potential approach in treatment of these physical and psychological long-term consequences and in the improvement of quality of life. Aim: This bachelor thesis seeks to determine the influence of BBAT on physical and psychological disorders and quality of life in victims of war and torture. The aim is to derive an evidence-based recommendation for physiotherapy. Method: The literature research was conducted using the databases AMED, CINAHL, MEDLINE and PsycINFO. Using criteria for inclusion and exclusion, two studies relevant to the research question could be found and analyzed. Results: Both studies conducted qualitative interviews. They indicate an improvement in physical and psychological disorders and quality of life. The quantitative results in one study only show significant improvement regarding movement quality, depression and chronic pain in the arms. Conclusion: BBAT seems to have a positive influence on physical and psychological disorders and quality of life in victims of war and torture. A universally applicable conclusion can currently not be drawn

Executive functions in elite athletes – Comparing open-skill and closed-skill sports and considering the role of athletes' past involvement in both sport categories

Previous research documented differences in executive functions between elite athletes in different sports. It was argued that athletes in sport disciplines with higher cognitive demands (i.e., open-skill) show better executive functions than athletes in less cognitively challenging sport disciplines (i.e., closed-skill). In the current study, we aimed at detecting differences in executive functions between elite athletes in open-skill versus closed-skill sports and questioned the role of their total involvement in these sports until the age of 18 on executive functions. Seventy-five elite athletes (45 males and 30 females; Mage = 23.03 ± 4.41 years) from various sports were classified as open- or closed-skill athletes based on the sport they currently competed in. The athletes conducted a series of neuro-psychological tests measuring working memory, inhibition, and cognitive flexibility (Design Fluency test, Trail Making test, Flanker task, and a 2-back task). Retrospective interviews assessed athletes’ sport involvement in open-skill and closed-skill sports until the age of 18. MANCOVAs revealed that athletes in open-skill sports performed better on measures of working memory and cognitive flexibility. Generalized Linear Models displayed that elite athletes in closed-skill sports, with greater involvement in open-skill sports until the age of 18, performed better during working memory and cognitive flexibility tasks. The results indicate that extensive time spent in open- and closed-skill sports can affect executive functions in elite athletes. A high involvement in open-skill sports proved to be beneficial for executive functions, in particular for elite athletes in closed-skill sports. These findings suggest that experiences in cognitively demanding sports may cause benefits for the development of executive functions

Pre-trained language models evaluating themselves - A comparative study

Evaluating generated text received new attention with the introduction of model-based metrics in recent years. These new metrics have a higher correlation with human judgments and seemingly overcome many issues of previous n-gram based metrics from the symbolic age. In this work, we examine the recently introduced metrics BERTScore, BLEURT, NUBIA, MoverScore, and Mark-Evaluate (Petersen). We investigate their sensitivity to different types of semantic deterioration (part of speech drop and negation), word order perturbations, word drop, and the common problem of repetition. No metric showed appropriate behaviour for negation, and further none of them was overall sensitive to the other issues mentioned above