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Medizinerkolleg Münster

Abschlusskolloquium der Kohorte 2019_2 und

Auftaktveranstaltung der Kohorte 2020_2

am 31.01.2021

MedK Kohorte 2019_2; Foto: Erk Wibberg

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Liebe Teilnehmer*innen, wir begrüßen Sie herzlich zum Abschlusskolloquium des Medizinerkollegs 2019_2 am 31.Januar 2021. In das Kolloquium ist die Auftaktveranstaltung für die neue Kohorte 2020_2 integriert, die wir vorab ebenfalls ganz herzlich willkommen heißen. Da wir das Kolloquium leider nicht als Präsenzveranstaltung, sondern als Zoom-Konferenz abhalten müssen, möchten wir Ihnen vorab ein paar Informationen zu diesem Format zukommen lassen: Bei den Vorträgen ist eine Redezeit von 15min und Diskussionszeit von 5min vorgesehen. Sie sind alle herzlich eingeladen, sich aktiv an den Diskussionen zu beteiligen und gerne viele Fragen zu stellen. Dies gilt auch und insbesondere für die neuen Kollegiatinnen und Kollegiaten. Wenn Sie gerade keinen Redebeitrag leisten möchten, bitten wir Sie das Mikrofon auszustellen. Im Rahmen eines wertschätzenden Miteinanders während Zoom-Konferenzen möchten wir Sie bitten Ihre Kamera einzuschalten, sofern dies für Sie technisch möglich ist. Neben den Vorträgen wird es ein weiteres Präsentationsformat geben, welches die in den vergangenen Jahren durchgeführten Postersessions ersetzt. Diese alternativen Postersessions werden wie folgt ablaufen:

- Die Präsentierenden bekommen jeweils einen Breakoutraum zugeteilt und präsentieren Ihr Thema in einer 5minütigen Kurzpräsentation. Anschließend kann 10min diskutiert werden. Abstracts zu den Kurzpräsentationen finden Sie ab Seite 6 des Programmheftes

- Alle anderen Teilnehmer können sich aussuchen, welchen Raum Sie besuchen und werden gebeten sich möglichst gut auf die 5 angebotenen Räume zu verteilen.

- Nach 15min werden die Breakouträume geschlossen und für eine weitere Runde erneut geöffnet. Sie haben die Möglichkeit 4 von 5 angebotenen Räume zu besuchen.

Wir wünschen allen Teilnehmern ein spannendes und erfolgreiches Kolloquium, Das Organisations-Team Sarah W. Derichs (Kohortensprecherin 2019_2) Samuel Corr (stellv. Kohortenprecher 2019_2) Prof. Dr. Rupert Hallmann (Sprecher des MedK) Dr. Jana Zimmermann (Studienkoordinatorin MedK)

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Datum: 31.01.2021 Ort: Zoom

Programm: 8:15 Begrüßung der Kohorten 2019_2 und 2020_2 Prof. Dr. Rupert

Hallmann Vorträge

8:30 Investigation of S100A8 and S100A9 Interactions with Different S100 Receptors, Prof. Dr. Thomas Vogl, Institut für Immunologie

Alexander Möller

8:50 Ion Channels in the Volume Regulation of Tumor Cells, Prof. Dr. Albrecht Schwab, Institut für Physiologie II

Christoph Post

9:10 Pause 10min

Postersession I

9:20 PSI-BR01: Establishment and Evaluation of Rat Liver Decellularization via Portal Venous Perfusion, PD Dr. Benjamin Strücker, Klinik für Allgemein-, Viszeral- und Transplantationsmedizin

Anna-Maria Diedrich

PSI-BR02: The Role of Junctional Adhesion Molecules in Entosis, Prof. Dr. Klaus Ebnet, Institut für Medizinische Biochemie

Anne Kaschler

PSI-BR03: Role of Post-Translational Modifications of the Histone Demethylase OHF8 in Sensitization of Acute Myeloid Leukemia Cells to ATRA, PD Dr. Jan-Henrik Mikesch, Medizinische Klinik A

Franca Seifert

PSI-BR04: Interaction of Actin and VE-Cadherin during Cell Junction Maturation and Reactivation, Univ.-Prof. Dr. Hans Joachim Schnittler, Institut für Anatomie und vaskuläre Biologie

Jonas Franz

PSI-BR05: Analysis of the Epigenetic Pathways of ETP-ALL Dependence on the Chromatin Reader BRD4, Prof. Dr. Claudia Rössig, Pädiatrsiche Hämatologie und Onkologie

Nicola Schmitz

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10:20 Pause 20min

Vorträge

10:40 Cellular and Functional Analysis of a sec31a1 Mutation Associated with Polycystic Liver Disease, Univ.-Prof. Dr. Hartmut Schmidt, Medizinische Klinik B

Jana Krader

11:00 Determinants for the spread of Panton-Valentine leukocidin positive Staphylococcus aureus in Africa, Prof. Dr. Frieder Schaumburg, Institut für Medizinische Mikrobiologie

Viktoria Rudolf

11:20 Pause 10min

Postersession II

11:30 PSII-BR01: Response Prediction of Virtual Reality Exposure Therapy for Spider Phobics – Behavioral and Magnetoencephalographic Correlates, Prof. Dr. Markus Junghöfer, Institut für Biomagnetismus und Biosignalanalyse

Julius Tölle

PSII-BR02: Phenotypic Comparison of Asymptomatic Bacteruria, Prof. Dr. Ulrich Dobrindt, Institut für Hygiene

Louisa Nienhaus

PSII-BR03: Video-Based Analysis of Sub-Second Behavioral Features of the Paw Withdrawal Reaction after Mechanical Stimulation in Models of Incisional and Neuropathic Pain in Mice, Prof. Dr. Esther Pogatzki-Zahn, Klinik für Anästhesiologie, operative Intensivmedizin und Schmerztherapie, UKM

Melanie Thorey

PSII-BR04: The Role of Heat Shock Protein 27 in Stress Tolerance Induction of Phagocytes, Prof. Dr. Johannes Roth, Institut für Immunologie

Nikita Drössel

12:30 Mittagspause

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Vorträge

13:30 Characterization of Mucoid S. aureus Isolates in the Airways of Cystic Fibrosis Patients During a Prospective Multicenter Study, Prof. Dr. med. Barbara Kahl, Institut für Medizinsiche Mikrobiologie

Karin Romme

13:50 A protein Fingerprint of Postoperative Pain in Male Volunteers, Univ.-Prof. Dr. Esther Pogatzki-Zahn, Klinik für Anästhesiologie, operative Intensivmedizin und Schmerztherapie, UKM

Max van der Burgt

14:10 Pause 10 min

Postersession III

14:20 PSIII-BR01: Influence of Supernumerary C-Chromosome and X-Chromosome Inactivation (XCI) in Bone Structures in Male Mice with an XXY Karyotype, Prof. Richard Stange, Institut für Muskuloskelettale Medizin

Niklas Husmann

PSIII-BR02: Analysis of the Potential Tumor-Suppressor Protein PATJ in the Pathogenesis of Colon Carcinoma, Prof. Dr. Dr. Michael Krahn, Medizinische Klinik D

Ronja Geller

PSIII-BR03: The Function of Short Linear Amino Acid Motifs in the Cytodomain of the HSV1-Fusionprotein Glycoprotein B (HSV1-gB), Prof. Dr. Joachim Kühn, Institut für klinische Virologie

Samuel Corr

PSIII-BR04: The Role of YAP/TAZ Signaling in Endothelial Cell-Cell Contact Dynamics under Atheroprone Shear Stress Conditions, Univ.-Prof. Dr. Hans Joachim Schnittler, Institut für Anatomie und vaskuläre Biologie

Sarah Derichs

15:20 Resümee und Verabschiedung Prof. Dr. Rupert Hallmann

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Poster-Abstracts: Postersession I: PSI-BR01: Establishment and Evaluation of Rat Liver Decellularization via Portal Venous Perfusion Anna-Maria Diedrich PD Dr. Benjamin Strücker, Klinik für Allgemein-, Viszeral-, und Transplantationschirurgie Organ decellularization and recellularization are promising approaches to generate functional and transplantable organs in vitro. During decellularization cells and antigenic material are removed and only the organ-specific, non-immunogenic extracellular matrix (ECM) is obtained. The ECM serves as a bio matrix for cellular repopulation in the context of recellularization. Since Uygun et al. (1) published the first report of a transplantable recellularized liver graft in 2010 there have been several attempts to improve the decellularization. But an ideal and standardized decellularization strategy is currently still unknown, that is why the aim in the first place was to establish and optimize the decellularization technique. In this project decellularized liver scaffolds were obtained by perfusing 1% Triton X-100 and 1% sodium dodecyl sulphate (SDS) for 90 minutes each through the cannulated portal vein with a constant flow rate of 5 ml/ min. Macroscopically decellularization was achieved, when the organ appeared translucent and the extracellular network and vascular structure could be identified. To evaluate the decellularization qualitatively and quantitatively firstly the efficiency of cell removal was assessed by measuring the DNA content und through hematoxylin and eosin (H&E) staining. Secondly the adequacy of ECM retention and integrity was measured and quantified by different histological staining methods and glycosaminoglycan, collagen IV and elastin assays. Immunohistochemical analysis of the ECM remains to be done. The evaluation of the decellularized matrices showed that most of the structure and components of the ECM were obtained during decellularization and moreover nuclear material and DNA could not be detected. 1 Uygun BE, Soto-Gutierrez A, Yagi H, Izamis ML, Guzzardi MA, Shulman C, et al. Organ reengineering through development of a transplantable recellularized liver graft using decellularized liver matrix. Nat Med. 2010;16(7):814-20. PSI-BR02: The Role of Junctional Adhesion Molecules in Entosis Anne Kaschler Prof. Dr. Klaus Ebnet, Institut für Medizinische Biochemie Entosis describes a nonapoptotic cell death process that occurs predominantly in cancer cells and leads to cell-in-cell structures. “This cell death mechanism is initiated by an unusual process involving the invasion of one live cell into another, followed by the degradation of internalized cells by lysosomal enzymes.”(Overholtzer et al., A nonapoptotic cell death process, entosis, that occurs by cell-in-cell invasion. Cell, 2007, vol.131, pp. 966). In previous studies the workgroup of Prof.

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Ebnet observed the suppression of entosis through the Junctional adhesion molecule A (JAM-A) in adherent cells. Interestingly the knockdown of JAM-A in human MCF-7 breast cancer cells leads to an increased amount of cell-in-cell structures in migrating cells. In the absence of JAM-A, cells continue to migrate one upon the other and engulf the cell beneath by entosis. The aim of my project is to investigate the role of JAM-A in entosis. Another trigger of entosis is the loss of attachment to the basement membrane, which is called matrix detachment. To provoke the formation of cell-in-cell structures, MCF-7 cells with a JAM-A knockdown have been cultured in suspension. Afterwards cell internalization was analyzed by immunofluorescence microscopy. PSI-BR03: Role of the Histone Demethylase PHF8 in Sensitization of Acute Myeloid Leukemia Cells to ATRA Franca Seifert Prof. Dr. med. Christoph Schliemann, Medizinische Klinik A Despite extensive chemotherapy treatment along with optional allogenic stem cell transplantation, prognosis of Acute Myeloid Leukemia (AML) remains poor, holding a 5-year overall survival rate of less than 40% [1]. However, treatment of Acute Promyelocytic Leukemia (APL), a sub-entity of AML, with all-trans retinoic acid (ATRA), caused a dramatic improvement in prognosis, transforming APL to a curable form of leukemia [2]. Nonetheless, the clinical effectiveness of ATRA in other subtypes of AML is limited. The histone demethylase PHF8, when forcibly expressed, has been proven to sensitize APL cells to ATRA treatment [3]. In my research, I studied the effects of PHF8 overexpression on clonal growth, cell proliferation and apoptosis in non-APL AML cell lines harboring different chromosomal translocations and mutations. Forced expression of PHF8 compromises the colony formation and proliferation capacity of AML cells and enhances the proportion of apoptotic cells in culture. The impact of ATRA treatment on these cell characteristics increases when PHF8 is overexpressed. These findings confirm the role of PHF8 in compromising the leukemic potential of non-APL AML cells and indicate a stronger response to ATRA when PHF8 is ectopically expressed. [1] van Gils N, Verhagen HJMP, Smit L. Reprogramming acute myeloid leukemia into sensitivity for retinoic-acid-driven differentiation. Exp Hematol. 2017 Aug; 52:12-23. doi: 10.1016/j.exphem.2017.04.007. Epub 2017 Apr 27. PMID: 28456748. [2] Thomas X. Acute Promyelocytic Leukemia: A History over 60 Years-From the Most Malignant to the most Curable Form of Acute Leukemia. Oncol Ther. 2019 Jun; 7(1):33-65. doi: 10.1007/s40487-018-0091-5. Epub 2019 Feb 5. PMID: 32700196; PMCID: PMC7360001. [3] Arteaga MF, Mikesch JH, Qiu J, et al. The histone demethylase PHF8 governs retinoic acid response in acute promyelocytic leukemia. Cancer Cell. 2013; 23(3):376-389. doi:10.1016/j.ccr.2013.02.014

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PSI-BR04: Interaction of Actin and VE-Cadherin during Cell Junction Maturation and Reactivation Jonas Franz Univ.-Prof. Dr. Hans-Joachim Schnittler, Institut für Anatomie und vaskuläre Biologie Endothelial cells line our blood vessels as the innermost cellular layer and form a natural barrier between the blood and the interstitium. Cell contacts ensure the monolayer integrity while at the same time dynamically influence its integrity. Recent research of our group demonstrated a subcellular highly dynamic regulation of cell junctions rather than a uniform cell junction activity level. In particular, regulation occurs via actin-driven “junction associated intermittent lamellipodia” (JAIL), which directly drive the dynamics of vascular endothelial cadherin (VE-cadherin). This process underlines an auto regulatory process with the local concentrations of VE-cadherin and actin as main players. It maintains cell layer integrity during remodeling processes and cell migration and is important in wound healing mechanisms and angiogenesis. JAIL-mediated VE-cadherin dynamics are an excellent example of how the actin cytoskeleton and the cell contact proteins cooperate. The aim of our project is to improve the understanding of the regulation of actin and VE-cadherin dynamics and its reorganization during cell contact maturation. We develop a model using HUVECs, which describes the process from mature cell contacts (resting endothelium, lower dynamics) to a more activated state (higher dynamics, directed cell migration) and vice versa. Further we investigate cell-matrix interactions. Therefore, cells were challenged by fluid shear stress, which forces the transition of a resting into an activated state characterized by cell migration, shape change leading to cell alignment and cell elongation. Using phase-contrast-microscopy and several fluorescence microscopy techniques we define the activity-state of HUVECs based on VE-cadherin, actin and cell-matrix dynamics. References:

Abu Taha, A. et al. (2014). ARP2/3- mediated junction-associated lamellipodia control VE-cadherin-based cell junction dynamics and maintain monolayer integrity. Mol. Biol. Cell 25, 245-256.

Buschmann MH. et al. (2005). Analysis of flow in a cone-and-plate apparatus with respect to spatial and temporal effects on endothelial cells. Biotechnol Bioeng. 89(5):493-502.

Cao, J. et al. (2017). Polarized actin and VE-cadherin dynamics regulate junctional remodeling and cell migration during sprouting angiogenesis. Nat. Commun. 8, 2210.

Cao, J. and Schnittler, H. (2019). Putting VE-cadherin into JAIL for junction re- modeling. J. Cell Sci. 132, jcs222893.

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PSI-BR05: Analysis of the Epigenetic Pathways of ETP-ALL Dependence on the Chromatin Reader BRD4 Nicola Schmitz Prof. Dr. Claudia Rössig, Dr. Dr. Sebastian Balbach; Klinik für Kinder- und Jugendmedizin - Pädiatrische Hämatologie und Onkologie

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a hematological malignancy and a subgroup of T-cell ALL. It is characterized by its poorer long-term outcome and the need of more intense therapy compared to non ETP-ALL patients.1 Studies suggest that this might be due to genomic alterations affecting the genes responsible for transcription, signaling and epigenetic pathways. One of these epigenetic factors with altered activity in ETP-ALL is the Bromodomain-containing protein 4 (BRD4). An essential function of BRD4 is the upregulation of certain genes by increasing the accessibility of chromatin and stabilizing the binding of transcription factors in the area of its target genes. When this process occurs at a certain stage of T-cell development, aberrant gene expression takes place, leading to an overexpression of oncogenes and therefore the disease pathogenesis of ETP-ALL.2

Thus, we hypothesize that a better understanding of the downstream pathways of BRD4 could lead to a more targeted and effective therapy for ETP-ALL. Our goal is to identify the mechanisms by which BRD4 can influence the malignancy of ETP-ALL. To analyze pathways of BRD4, RNA- and ChIP-seq with cells resistant to the BRD4 Inhibitor JQ1, cells treated with JQ1 for a short time and untreated ETP-ALL cells were performed. 1 Jain, N. et al. (2016) ‘Early T-cell precursor acute lymphoblastic leukemia/lymphoma (ETP-ALL/LBL) in adolescents and adults: A high-risk subtype’, Blood. American Society of Hematology, 127(15), pp. 1863–1869. doi: 10.1182/blood-2015-08-661702. 2 Tavakoli Shirazi, P. et al. (2020) ‘The effect of co-occurring lesions on leukaemogenesis and drug response in T-ALL and ETP-ALL’, British Journal of Cancer. Springer Nature, pp. 455–464. doi: 10.1038/s41416-019-0647-7. Postersession II: PSII-BR01: Response Prediction of a Virtual Reality Exposure Therapy for Spider Phobics – Behavioral and Magnetoencephalographic Correlates Julius Tölle Prof. Dr. Markus Junghöfer, Institut für Biomagnetismus und Biosignalanalyse Models of anxiety disorders include fear conditioning as an important etiological factor, yet its link with exposure therapy (ET) outcomes has remained largely unclear. We investigated whether behavioral and magnetoencephalographic pre-treatment correlates of fear conditioning in adult spider-phobic patients moderate their response ET.

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Sixty- six patients with spider phobia completed pre- treatment clinical and experimental fear conditioning assessments, one session of in virtuo ET and a post-treatment clinical assessment. During fear conditioning, tilted gabor gratings served as conditioned stimuli (CS) that were either paired (CS+) or remained unpaired (CS-) with an aversive unconditioned stimulus (UCS). As indices of fear conditioning, CS+/CS- differences in fear ratings and magnetoencephalographic event-related fields (ERFs) were related to percentual symptom reductions from pre- to post-treatment, that were assessed via the spider phobia questionnaire (SPQ). While fear ratings were not associated with percentual SPQ- reductions, source estimations of ERFs revealed an association between stronger activations to the safety signaling CS- (vs. CS+) and better ET outcomes in the left dorsolateral- prefrontal cortex (DLPFC) (290-570ms after CS onset). Similar effects in the right DLPFC were limited to phobia-related but not phobia unrelated UCS (110- 200ms after CS onset). Time periods of neural activation refer to the importance of relatively early and automated processes of differential fear conditioning. Results provide initial evidence that magnetoencephalographic but not behavioral pre-treatment correlates of fear conditioning may hold predictive information regarding later responses to exposure therapy. Our findings suggest that inhibitory responses to safety cues during fear conditioning might moderate ET outcomes. PSII-BR02: Phenotypic Comparison of Asymptomatic Bacteriuria E. coli Isolates Louisa Raphaela Nienhaus Prof. Dr. Ulrich Dobrindt, Institut für Hygiene To further characterize phenotypic differences between asymptomatic bacteriuria (ABU) E. coli isolates and pathogens causing symptomatic episodes of lower or upper urinary tract infection(UTI), a collective of patient isolates, consisting of 50 asymptomatic bacteriuria E. coli(ABU) isolates, 57 cystitis isolates and 48 pyelonephritis isolates, was examined with regard to phenotypic properties. A significantly lower number of ABU isolates was characterized by aerobactin production and serum resistance compared to the symptomatic UTI isolates. In addition, the ABU isolates showed a slightly lower hemolytic activity (not significant) compared to the other two isolate groups. Moreover, the adhesiveness and invasiveness of selected non-hemolytic ABU isolates was analyzed. This was of interest, because the investigated ABU isolates should be characterized in more detail from the point of view of alternative treatment options for therapeutic bladder inoculation instead of ABU model isolate 83972, which is already used for bacterial interference in patients suffering from chronic symptomatic urinary tract infections. With regard to the ability to adhere to the RT-112 bladder epithelial cell line, most of the ten ABU isolates examined showed poor adhesion in comparison to the control strains E. coli CFT073 (UPEC) and coisolate 83972(ABU).Two ABU isolates adhered significantly better compared to the other ABU isolates. Furthermore, these two strongly adherent ABU isolates displayed marked invasiveness. Based on these in vitro results, many phenotypic similarities between the ABU isolate ABU 44 and the E. coli isolate 83972 could be shown. Based on the outcome of additional future studies, this ABU isolate could represent an alternative therapy strain.

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PSII-BR03: Video-Based Analysis of Sub-Second Behavioral Features of the Paw Withdrawal Reaction after Mechanical Stimulation in Models of Incisional and Neuropathic Pain in Mice Melanie Thorey Univ.-Prof. Dr. Esther Pogatzki-Zahn, Klinik für Anästhesiologie, operative Intensivmedizin und Schmerztherapie, UKM Introduction: Assessing of pain-related behavior is essential in mechanism-based preclinical research in rodents. The traditional method of scoring a binary yes/no paw withdrawal response (PWR) to different modalities and intensities only insufficiently captures pain-related aspects. Recently, video-based approaches have been introduced to identify and analyze phenotypes of PWR after mechanical stimulation1. This study adapted a video-based method for PWR-analysis and applied it in longitudinal studies regarding pain models of acute incisional (INC) and chronic neuropathic pain (SNI). Methods: After establishing the experimental set-up, naïve male C57BL/6J mice were randomly assigned to an INC- (n=4) or SNI-cohort (n=3). Every cohort underwent three training sessions, two baseline tests, and PWR-tests on multiple postoperative days (POD) specific for each pain model. After 15 minutes of habituation, mechanical stimuli (Dynamic Brush (DB), von Frey-Filaments (vFF), PinPrick (PP)) were applied to the plantar aspect of the hind paw in a randomized order, and the resulting PWR was captured on video (240fps). Blinded experimenters analyzed the reflexive (withdrawal frequency) and affective components (occurrence of shaking/guarding, duration) of PWR within the analysis period (4s after stimulation). Results: PWR frequency increased with higher forces of vFF and at specific time points in both pain models but failed to adequately discriminate a typical innocuous (DB) from a typical noxious (PP) stimulus. In contrast, video-based analysis detected differences in the affective components of PWR to DB vs. PP stimulation in both pain models. Conclusion: Video-based methods show promising potential for improving the accuracy of interpreting PWR after mechanical stimulation. 1 Abdus-Saboor, I. et al. (2019). Development of a Mouse Pain Scale Using Sub-second Behavioral Mapping and Statistical Modeling. Cell Reports Vol.28, S.1623-1634.e4. https://doi.org/10.1016/j.celrep.2019.07.017 PSII-BR04: The Role of Heat Shock Protein 27 in Stress Tolerance Induction of Phagocytes Nikita Drössel Prof. Dr. Johannes Roth, Institut für Immunologie The regulation of the inflammatory responsiveness of phagocytes to exogenous and endogenous stimuli plays an essential part in the development of systemic inflammation like sepsis. In later stages of sepsis, it has been shown, that phagocytes develop a secondary state of hyporesponsiveness. Our lab identified heat shock protein 27 as a potential key protein in this molecular mechanism, known as endotoxin-tolerance.

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We performed protein detection, quantification, and analysis of HSP27 in tolerized cells and were able to show, that this protein plays an essential part in the induction of the tolerization of monocyte cells to pathogenic stimuli. With the inhibition of HSP27 with specific inhibitors, the tolerance of phagocytes is not inducible, making it an indispensable protein in the pathway involved in tolerance induction. On the contrary, with exogenous recombinant HSP27 we were able to induce a tolerized state in the cells, hinting that HSP27 could play a critical role extracellularly and interact with different TLR receptors, normally responsible for the recognition of PAMPs. Finally, we were also able to show that phosphorylated HSP27 accumulates in tolerized cells, underlining our previous findings and hinting at a potential translocation of HSP27 to the nucleus in the remodeling. HSP27 plays a key factor intracellularly and extracellularly in the modelling of the responsiveness of phagocytes. These results undermine the importance of further studies on it to gain a better understanding of tolerance and hyporeactivity in immune diseases. Postersession III: PSIII-BR01: Influence of Supernumerary X-Chromosomes on Bone Structure in Aged Male Mice with an XXY Karyotype Niklas Husmann Prof. Richard Stange, Institut für Muskoloskelettale Medizin

Introduction: Klinefelter Syndrome is the most common chromosomal aneuploidy in men. Patients suffer from the consequences of a lack of testosterone (infertility, osteoporosis). Studies suggest that supernumerary X chromosomes, along with X chromosome inactivation (XCI), play a role in osteoporosis development.1 Integral membrane Protein (ITM) 2a escapes XCI and was identified as a promising target for bone research. Aim of the project is to find out whether XXY*-mice suffer from a similar systemic bone loss compared to humans during the course of aging, and whether the supernumerary X-chromosome causes differences in gene expression related to bone development.2

Material and Methods: Bone structure of lumbar vertebrae, tibiae and femora of 24 months old male wild type (WT, n=10) and 41 XXY* mice (B6Ei.Lt-Y*,3 n=14) were analysed by µCT. In addition, tissue slices of bones, heart, liver, brain, lung and kidney were prepared for immunohistochemistry (IHC) staining using anti-ITM2a-antibody. Results: Lumbar vertebrae and femora of XXY* mice showed significantly lower bone quality compared to WT mice. IHC staining showed a high expression of ITM2a in chondrocytes, as well as in different bone marrow cell types. However, there were no obvious differences between XXY*- and WT mice visible. Discussion: Bone analysis showed a significant reduction in bone quality (p<0,05) in XXY* mice, even higher as in WT. The results support the significance of this mouse model to investigate its bone phenotype in correlation with Klinefelter Syndrome. Analysis of younger animals is planned. ITM2a serves as an interesting target to study XCI in bone. REFERENCES: 1 Liu PY, Kalak R, Lue Y, et al. Genetic and hormonal control of bone volume, architecture, and remodeling in XXY mice. J Bone Miner Res. 2010; 25(10):2148-2154. doi:10.1002/jbmr.104; 2 Pittois, K., Wauters, J., Bossuyt, P. et al. Genomic

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organization and chromosomal localization of the Itm2a gene. 10, 54–56 (1999); 3 Eicher EM, Hale DW, Hunt PA, Lee BK, Tucker PK, King TR, Eppig JT, Washburn LL. The mouse Y* chromosome involves a complex rearrangement, including interstitial positioning of the pseudoautosomal region. Cytogenet Cell Genet 1991; 57:221–230. PSIII-BR02: Analysis of the Potential Tumor-Suppressor Protein PATJ in the Pathogenesis of Colon Carcinoma Ronja Geller Prof. Dr. Dr. Michael Krahn Medizinische Klinik D Apical-basal polarization is essential for the organization and function of polarized cells and orchestrated through the molecular interplay of an intricate network of protein complexes. During epithelial-mesenchymal-transition (EMT), an essential process in the advanced stages of tumor migration and invasiveness, polarization is partially lost. Defects in the expression of cell polarity components are also often associated with the emergence of neoplasia. Thus, a valid but still only partially answered question is that of the role of polarity proteins as tumor suppressors and promotors. One of these proteins is PATJ (PALS1-associated TJ protein) a tight junction-associated multi-PDZ protein and part of the Crumbs complex at the intercellular side of the tight junction. PATJ has been shown to be essential for the stability of the Crumbs complex and higher expression of PATJ is associated with survival in colon cancer. Previous studies in drosophila and human cell culture have suggested that both the Crumbs complex in general and PATJ itself may influence the susceptibility of cells to EMT and the regulation of contact-inhibited growth within the epithelium. Additionally, previous work of the AG Krahn has suggested that PATJ may act as a tumor suppressor in colon cancer cells. This thesis shows how the presence and absence of PATJ influence cell proliferation and migration in human colon carcinoma cell culture (HCT 116) and proposes how PATJ may function as tumor suppressor in influencing cellular pathways controlling the cell cycle and EMT. PSIII-BR03: The Function of Short Linear Amino Acid Motifs in the Cytodomain of the HSV1-Fusionprotein Glycoprotein B (HSV1-gB) Samuel Corr Prof. Dr. J. Kühn, Institut für klinische Virologie Enveloped Viruses, like herpes simplex virus 1 (HSV-1), need specialized membrane proteins, called fusogens, to enter target cells. Fusogens can fold from a metastable pre- to a stable post fusion conformation, thereby merging viral and host membranes. This leads to fusion of both membranes and allows virus entry. HSV-1 needs four glycoproteins for cell penetration, gD, gH, gL and gB. The last one, gB, is the real fusogen of HSV-1. It consists of a large ectodomain (ECD), which drive fusion, a transmembrane and a cytoplasmic domain (CTD). The CTD fixates the

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ectodomain on the membrane and negatively regulates the fusion capacity of gB, which saves HSV-1 from excessive fusion activity. Currently, the inhibiting influence of the CTD on the ECD is not perfectly understood (Cooper et al., Nature Struct.Mol.Biol. Vol. 25, 416-424, 2018). The gB-CTD contains a lot of short linear amino acid motifs. In this work, we focus on a di-arginine (RXR) ER-retention signal, which is conserved among a lot of herpes viruses. RXR-signals play a critical role in assembly and maturation of multimeric membrane proteins by retaining not native folded proteins in the ER (Michelsen et al., EMBO reports Vol. 6, 717-722, 2005). RXR-signals can be activated and masked by different processes, e. g. the distance of the signal to the inner membrane. We investigate if the RXR-signal is regulated by different spacing to the inner membrane and if this influences the fusion capacity of gB. PSIII-BR04: The Role of YAP/TAZ Signaling in Endothelial Cell-Cell Contact Dynamics under Atheroprone Shear Stress Conditions Sarah Warunee Derichs Univ.-Prof. Dr. Hans-Joachim Schnittler, Institut für Anatomie und vaskuläre Biologie The integrity of the endothelium is essential to ensure homeostasis between blood and tissue, even under the constant fluid shear stress of the blood flow. Downstream of vascular branching point this blood flow is disturbed which leads to pathophysiological reactions of the endothelium sometimes resulting in atherosclerotic plaques. Barrier maintenance of the endothelium is based on the integrity of cell-cell contacts and their dynamics. An altered endothelium might result in disturbed homeostasis, LDL and macrophage infiltration and therefore the development of atherosclerotic plaques are possible. Studies of atherosclerotic plaques in human and mouse aortae showed an increased expression of target genes of the hippo signaling pathway1. Oscillatory shear stress in vitro leads to an activation of Hippo signaling characterized by a translocation of Hippo signaling transcription factors Yap and Taz into the nucleus2. This signaling pathway, known to influence many cellular processes such as cell proliferation and differentiation, has been shown to regulate endothelial barrier maintenance and angiogenesis3. However, the role of Yap/Taz on cell-cell contact organization and dynamics under oscillatory shear stress conditions is still unknown. This project aims to get an insight into this role of Yap/Taz in controlling and influencing the integrity and dynamics of endothelial junctions under oscillatory shear stress conditions by analyzing the expression of VE-Cadherin as one cell-cell contact protein upon loss of Yap/Taz under static conditions and conditions of oscillatory shear stress. 1 Schober et al. (2002). Identification of integrin αMβ2 as an adhesion receptor on peripheral blood monocytes for Cyr61 (CCN1) and connective tissue growth factor (CCN2): immediate-early gene products expressed in atherosclerotic lesions, Cicha et al. (2005). Connective Tissue Growth Factor Is Overexpressed in Complicated Atherosclerotic Plaques and Induces Mononuclear Cell Chemotaxis in Vitro 2 Bondavera et al. (2019). Identification of atheroprone shear stress responsive regulatory elements in endothelial cells 3 Neto et al. (2018). YAP and TAZ regulate adherens junction dynamics and endothelial cell distribution during vascular development

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