SUMOylation promotes protective responses to DNA-protein crosslinks

DNA-protein crosslinks (DPCs) are highly cytotoxic lesions that obstruct essential DNA transactions and whose resolution is critical for cell and organismal fitness. However, the mechanisms by which cells respond to and overcome DPCs remain incompletely understood. Recent studies unveiled a dedicated DPC repair pathway in higher eukaryotes involving the SprT-type metalloprotease SPRTN/DVC1, which proteolytically processes DPCs during DNA replication in a ubiquitin-regulated manner. Here, we show that chemically induced and defined enzymatic DPCs trigger potent chromatin SUMOylation responses targeting the crosslinked proteins and associated factors. Consequently, inhibiting SUMOylation compromises DPC clearance and cellular fitness. We demonstrate that ACRC/GCNA family SprT proteases interact with SUMO and establish important physiological roles of Caenorhabditis elegans GCNA-1 and SUMOylation in promoting germ cell and embryonic survival upon DPC formation. Our findings provide first global insights into signaling responses to DPCs and reveal an evolutionarily conserved function of SUMOylation in facilitating responses to these lesions in metazoans that may complement replication-coupled DPC resolution processes

Alternative HER/PTEN/Akt Pathway Activation in HPV Positive and Negative Penile Carcinomas

Copyright: 2011 Stankiewicz et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: The pathogenesis of penile squamous cell carcinoma (PSCC) is not well understood, though risk factors include human papillomavirus (HPV). Disruption of HER/PTEN/Akt pathway is present in many cancers; however there is little information on its function in PSCC. We investigated HER family receptors and phosphatase and tension homolog (PTEN) in HPV-positive and negative PSCC and its impact on Akt activation using immunohistochemistry and fluorescent in situ hybridisation (FISH). Methodology/Principal Findings: 148 PSCCs were microarrayed and immunostained for phosphorylated EGFR (pEGFR), HER2, HER3, HER4, phosphorylated Akt (pAkt), Akt1 and PTEN proteins. EGFR and PTEN gene status were also evaluated using FISH. HPV presence was assessed by PCR. pEGFR expression was detected significantly less frequently in HPV-positive than HPV-negative tumours (p = 0.0143). Conversely, HER3 expression was significantly more common in HPV-positive cases (p = 0.0128). HER4, pAkt, Akt and PTEN protein expression were not related to HPV. HER3 (p = 0.0054) and HER4 (p = 0.0002) receptors significantly correlated with cytoplasmic Akt1 immunostaining. All three proteins positively correlated with tumour grade (HER3, p = 0.0029; HER4, p = 0.0118; Akt1, p = 0.0001). pEGFR expression correlated with pAkt but not with tumour grade or stage. There was no EGFR gene amplification. HER2 was not detected. PTEN protein expression was reduced or absent in 62% of tumours but PTEN gene copy loss was present only in 4% of PSCCs. Conclusions/Significance: EGFR, HER3 and HER4 but not HER2 are associated with penile carcinogenesis. HPV-negative tumours tend to express significantly more pEGFR than HPV-positive cancers and this expression correlates with pAkt protein, indicating EGFR as an upstream regulator of Akt signalling in PSCC. Conversely, HER3 expression is significantly more common in HPV-positive cases and positively correlates with cytoplasmic Akt1 expression. HER4 and PTEN protein expression are not related to HPV infection. Our results suggest that PSCC patients could benefit from therapies developed to target HER receptors.Peer reviewedFinal Published versio

STAT3 Regulates Monocyte TNF-Alpha Production in Systemic Inflammation Caused by Cardiac Surgery with Cardiopulmonary Bypass

BACKGROUND: Cardiopulmonary bypass (CPB) surgery initiates a controlled systemic inflammatory response characterized by a cytokine storm, monocytosis and transient monocyte activation. However, the responsiveness of monocytes to Toll-like receptor (TLR)-mediated activation decreases throughout the postoperative course. The purpose of this study was to identify the major signaling pathway involved in plasma-mediated inhibition of LPS-induced tumor necrosis factor (TNF)-α production by monocytes. METHODOLOGY/PRINCIPAL FINDINGS: Pediatric patients that underwent CPB-assisted surgical correction of simple congenital heart defects were enrolled (n = 38). Peripheral blood mononuclear cells (PBMC) and plasma samples were isolated at consecutive time points. Patient plasma samples were added back to monocytes obtained pre-operatively for ex vivo LPS stimulations and TNF-α and IL-6 production was measured by flow cytometry. LPS-induced p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB activation by patient plasma was assessed by Western blotting. A cell-permeable peptide inhibitor was used to block STAT3 signaling. We found that plasma samples obtained 4 h after surgery, regardless of pre-operative dexamethasone treatment, potently inhibited LPS-induced TNF-α but not IL-6 synthesis by monocytes. This was not associated with attenuation of p38 MAPK activation or IκB-α degradation. However, abrogation of the IL-10/STAT3 pathway restored LPS-induced TNF-α production in the presence of suppressive patient plasma. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that STAT3 signaling plays a crucial role in the downregulation of TNF-α synthesis by human monocytes in the course of systemic inflammation in vivo. Thus, STAT3 might be a potential molecular target for pharmacological intervention in clinical syndromes characterized by systemic inflammation

GENERIC QUESTION-AND-ANSWER BASED BUSINESS GAMES

Within day-to-day business many problems are not well-structured, data are missing, the problem definition is incomplete etc. Employees have to specify their tasks accurately, search for relevant information, ask how the task is intended before being able to provide suitable solutions. This "real life situation" is hardly been not practiced by students. Usually, students are facing well defined tasks with clear objectives. Even the knowledge and methods that they have to apply is mostly given within an exercise. To prepare students for real life, they have to practice such situations. For this, we present a game-based learning solution that simulates the real life situation of incomplete problem definitions. The end result is clearly defined, but the restrictions or determinants are not given. That means, that each student who wants to solve the exercise knows which data has to be found or computed but in the beginning most of the determinants are missing. Therefore, students have to structure the problem first. They have to find the determinants they need to compute the result. Then, they can ask the system about the required values and get information and leading hints in response. The advantages of the game based learning system are obvious: Students have to analyse the situation, they have to find a problem solving method and they have to do an investigation on their own. Therefore, they learn to work independently. As a side effect, those exercises can be used in exams: The students' solutions can be compared to the reference solution and can be marked as correct or wrong. The system knows all about the required values. If students fill in the correct solution without having asked the right questions the system knows that they have guessed or cheated. Even if students have not found the correct end result the assignment can take place: On the basis of the questions asked by students the system can analyse how much of the problem was solved.</jats:p

E-LEARNING SUPPORTED SQL TEACHING

Most database systems that are used in enterprises are based on the database language SQL. As a kind of programming language, SQL cannot only be taught with paper and pencil. Instead, it is evident to use computers so that students can make their own practical experiences. But then, students may "get lost" in the database: They can destroy the underlying data base scheme or delete too many data sets. Then, case studies or exercises that build upon each other cannot be solved correctly or students cannot verify if they solved the exercises correctly because they work on a modified data base different to the one that is assumed for the reference output of SQL queries. Besides, if students work on the same data base the learning progress of a student can be negatively affected not only by himself but by other students. The e-learning system presented here solves this situation. It provides a database environment to each single student separated from other students so that it cannot be influenced by others. There, students can build their own "private" data base with which they can work during the courses. Predefined databases and schemes are provided for case studies and consecutive exercises so that students can always return to different milestones provided in the learning process. We analysed the usefulness of the system concerning the learning progress of students. In bachelor as well as master courses, the use of the system has clearly led to a better understanding of SQL.</jats:p