[{"publication_status":"published","ddc":["570"],"project":[{"grant_number":"665385","_id":"2564DBCA-B435-11E9-9278-68D0E5697425","name":"International IST Doctoral Program","call_identifier":"H2020"}],"department":[{"_id":"GradSch"},{"_id":"MiSi"}],"page":"226","supervisor":[{"last_name":"Sixt","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-6620-9179","full_name":"Sixt, Michael K","first_name":"Michael K"}],"date_published":"2023-12-20T00:00:00Z","publisher":"Institute of Science and Technology Austria","citation":{"short":"J.A. Stopp, Neutrophils on the Hunt: Migratory Strategies Employed by Neutrophils to Fulfill Their Effector Function, Institute of Science and Technology Austria, 2023.","ama":"Stopp JA. Neutrophils on the hunt: Migratory strategies employed by neutrophils to fulfill their effector function. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:14697\">10.15479/at:ista:14697</a>","ieee":"J. A. Stopp, “Neutrophils on the hunt: Migratory strategies employed by neutrophils to fulfill their effector function,” Institute of Science and Technology Austria, 2023.","mla":"Stopp, Julian A. <i>Neutrophils on the Hunt: Migratory Strategies Employed by Neutrophils to Fulfill Their Effector Function</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:14697\">10.15479/at:ista:14697</a>.","chicago":"Stopp, Julian A. “Neutrophils on the Hunt: Migratory Strategies Employed by Neutrophils to Fulfill Their Effector Function.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:14697\">https://doi.org/10.15479/at:ista:14697</a>.","ista":"Stopp JA. 2023. Neutrophils on the hunt: Migratory strategies employed by neutrophils to fulfill their effector function. Institute of Science and Technology Austria.","apa":"Stopp, J. A. (2023). <i>Neutrophils on the hunt: Migratory strategies employed by neutrophils to fulfill their effector function</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:14697\">https://doi.org/10.15479/at:ista:14697</a>"},"date_created":"2023-12-18T19:14:28Z","year":"2023","related_material":{"record":[{"relation":"part_of_dissertation","id":"6328","status":"public"},{"status":"public","id":"7885","relation":"part_of_dissertation"},{"status":"public","relation":"part_of_dissertation","id":"12272"},{"id":"14274","relation":"part_of_dissertation","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"14360"}]},"degree_awarded":"PhD","ec_funded":1,"acknowledged_ssus":[{"_id":"LifeSc"},{"_id":"Bio"}],"_id":"14697","file_date_updated":"2023-12-20T10:41:42Z","doi":"10.15479/at:ista:14697","author":[{"full_name":"Stopp, Julian A","first_name":"Julian A","id":"489E3F00-F248-11E8-B48F-1D18A9856A87","last_name":"Stopp"}],"file":[{"content_type":"application/pdf","file_size":51585778,"access_level":"closed","relation":"main_file","creator":"jstopp","embargo_to":"open_access","date_created":"2023-12-20T09:35:34Z","date_updated":"2023-12-20T09:35:34Z","embargo":"2024-12-20","checksum":"457927165d5d556305d3086f6b83e5c7","file_name":"Thesis.pdf","file_id":"14699"},{"creator":"jstopp","file_size":69625950,"relation":"source_file","access_level":"closed","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_name":"Thesis.docx","checksum":"e8d26449ac461f5e8478a62c9507506f","file_id":"14700","date_created":"2023-12-20T09:35:35Z","date_updated":"2023-12-20T10:41:42Z"}],"user_id":"8b945eb4-e2f2-11eb-945a-df72226e66a9","day":"20","oa_version":"Published Version","month":"12","publication_identifier":{"issn":["2663 - 337X"],"isbn":["978-3-99078-038-1"]},"status":"public","type":"dissertation","alternative_title":["ISTA Thesis"],"title":"Neutrophils on the hunt: Migratory strategies employed by neutrophils to fulfill their effector function","article_processing_charge":"No","date_updated":"2023-12-21T14:30:02Z","has_accepted_license":"1","language":[{"iso":"eng"}]},{"user_id":"8b945eb4-e2f2-11eb-945a-df72226e66a9","file":[{"embargo":"2023-12-20","checksum":"cc4a2b4a7e3c4ee8ef7f2dbf909b12bd","file_id":"12402","file_name":"PhD-Thesis_Saren Tasciyan_formatted_aftercrash_fixed_600dpi_95pc_final_PDFA3b.pdf","date_created":"2023-01-26T11:58:14Z","date_updated":"2023-12-21T23:30:03Z","creator":"cchlebak","relation":"main_file","file_size":42059787,"access_level":"open_access","content_type":"application/pdf"},{"content_type":"application/x-zip-compressed","relation":"source_file","access_level":"closed","file_size":261256696,"creator":"cchlebak","embargo_to":"open_access","date_created":"2023-01-26T12:00:10Z","date_updated":"2023-12-21T23:30:03Z","checksum":"f1b4ca98b8ab0cb043b1830971e9bd9c","file_id":"12403","file_name":"Source Files - Saren Tasciyan - PhD Thesis.zip"}],"oa_version":"Published Version","day":"22","month":"12","publication_identifier":{"issn":["2663-337X"]},"author":[{"id":"4323B49C-F248-11E8-B48F-1D18A9856A87","last_name":"Tasciyan","orcid":"0000-0003-1671-393X","first_name":"Saren","full_name":"Tasciyan, Saren"}],"status":"public","type":"dissertation","alternative_title":["ISTA Thesis"],"has_accepted_license":"1","title":"Role of microenvironment heterogeneity in cancer cell invasion","article_processing_charge":"No","date_updated":"2024-09-10T12:04:26Z","oa":1,"language":[{"iso":"eng"}],"abstract":[{"text":"Detachment of the cancer cells from the bulk of the tumor is the first step of metastasis, which\r\nis the primary cause of cancer related deaths. It is unclear, which factors contribute to this step.\r\nRecent studies indicate a crucial role of the tumor microenvironment in malignant\r\ntransformation and metastasis. Studying cancer cell invasion and detachments quantitatively in\r\nthe context of its physiological microenvironment is technically challenging. Especially, precise\r\ncontrol of microenvironmental properties in vivo is currently not possible. Here, I studied the\r\nrole of microenvironment geometry in the invasion and detachment of cancer cells from the\r\nbulk with a simplistic and reductionist approach. In this approach, I engineered microfluidic\r\ndevices to mimic a pseudo 3D extracellular matrix environment, where I was able to\r\nquantitatively tune the geometrical configuration of the microenvironment and follow tumor\r\ncells with fluorescence live imaging. To aid quantitative analysis I developed a widely applicable\r\nsoftware application to automatically analyze and visualize particle tracking data.\r\nQuantitative analysis of tumor cell invasion in isotropic and anisotropic microenvironments\r\nshowed that heterogeneity in the microenvironment promotes faster invasion and more\r\nfrequent detachment of cells. These observations correlated with overall higher speed of cells at\r\nthe edge of the bulk of the cells. In heterogeneous microenvironments cells preferentially\r\npassed through larger pores, thus invading areas of least resistance and generating finger-like\r\ninvasive structures. The detachments occurred mostly at the tips of these structures.\r\nTo investigate the potential mechanism, we established a two dimensional model to simulate\r\nactive Brownian particles representing the cell nuclei dynamics. These simulations backed our in\r\nvitro observations without the need of precise fitting the simulation parameters. Our model\r\nsuggests the importance of the pore heterogeneity in the direction perpendicular to the\r\norientation of bias field (lateral heterogeneity), which causes the interface roughening.","lang":"eng"}],"ddc":["610"],"publication_status":"published","department":[{"_id":"GradSch"},{"_id":"MiSi"}],"page":"105","date_published":"2022-12-22T00:00:00Z","supervisor":[{"id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt","orcid":"0000-0002-6620-9179","first_name":"Michael K","full_name":"Sixt, Michael K"}],"publisher":"Institute of Science and Technology Austria","related_material":{"record":[{"status":"public","relation":"part_of_dissertation","id":"679"},{"id":"10703","relation":"part_of_dissertation","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"7885"},{"id":"9429","relation":"part_of_dissertation","status":"public"}]},"degree_awarded":"PhD","date_created":"2023-01-26T11:55:16Z","citation":{"chicago":"Tasciyan, Saren. “Role of Microenvironment Heterogeneity in Cancer Cell Invasion.” Institute of Science and Technology Austria, 2022. <a href=\"https://doi.org/10.15479/at:ista:12401\">https://doi.org/10.15479/at:ista:12401</a>.","mla":"Tasciyan, Saren. <i>Role of Microenvironment Heterogeneity in Cancer Cell Invasion</i>. Institute of Science and Technology Austria, 2022, doi:<a href=\"https://doi.org/10.15479/at:ista:12401\">10.15479/at:ista:12401</a>.","ista":"Tasciyan S. 2022. Role of microenvironment heterogeneity in cancer cell invasion. Institute of Science and Technology Austria.","ieee":"S. Tasciyan, “Role of microenvironment heterogeneity in cancer cell invasion,” Institute of Science and Technology Austria, 2022.","ama":"Tasciyan S. Role of microenvironment heterogeneity in cancer cell invasion. 2022. doi:<a href=\"https://doi.org/10.15479/at:ista:12401\">10.15479/at:ista:12401</a>","short":"S. Tasciyan, Role of Microenvironment Heterogeneity in Cancer Cell Invasion, Institute of Science and Technology Austria, 2022.","apa":"Tasciyan, S. (2022). <i>Role of microenvironment heterogeneity in cancer cell invasion</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:12401\">https://doi.org/10.15479/at:ista:12401</a>"},"year":"2022","doi":"10.15479/at:ista:12401","_id":"12401","file_date_updated":"2023-12-21T23:30:03Z"},{"author":[{"last_name":"Tomasek","id":"3AEC8556-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-3768-877X","first_name":"Kathrin","full_name":"Tomasek, Kathrin"}],"day":"18","oa_version":"Published Version","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","file":[{"creator":"ktomasek","file_size":13266088,"relation":"main_file","access_level":"open_access","content_type":"application/pdf","file_name":"ThesisTomasekKathrin.pdf","file_id":"10308","checksum":"b39c9e0ef18d0484d537a67551effd02","embargo":"2022-11-18","date_updated":"2022-12-20T23:30:05Z","date_created":"2021-11-18T15:07:31Z"},{"file_id":"10309","file_name":"ThesisTomasekKathrin.docx","checksum":"c0c440ee9e5ef1102a518a4f9f023e7c","date_updated":"2022-12-20T23:30:05Z","date_created":"2021-11-18T15:07:46Z","embargo_to":"open_access","creator":"ktomasek","relation":"source_file","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_size":7539509,"access_level":"closed"}],"publication_identifier":{"issn":["2663-337X"]},"month":"11","alternative_title":["ISTA Thesis"],"status":"public","type":"dissertation","title":"Pathogenic Escherichia coli hijack the host immune response","oa":1,"date_updated":"2023-09-07T13:34:38Z","article_processing_charge":"No","has_accepted_license":"1","language":[{"iso":"eng"}],"publication_status":"published","abstract":[{"lang":"eng","text":"Bacteria-host interactions represent a continuous trade-off between benefit and risk. Thus, the host immune response is faced with a non-trivial problem – accommodate beneficial commensals and remove harmful pathogens. This is especially difficult as molecular patterns, such as lipopolysaccharide or specific surface organelles such as pili, are conserved in both, commensal and pathogenic bacteria. Type 1 pili, tightly regulated by phase variation, are considered an important virulence factor of pathogenic bacteria as they facilitate invasion into host cells. While invasion represents a de facto passive mechanism for pathogens to escape the host immune response, we demonstrate a fundamental role of type 1 pili as active modulators of the innate and adaptive immune response."}],"ddc":["570"],"page":"73","department":[{"_id":"MiSi"},{"_id":"CaGu"},{"_id":"GradSch"}],"publisher":"Institute of Science and Technology Austria","supervisor":[{"first_name":"Michael K","full_name":"Sixt, Michael K","orcid":"0000-0002-4561-241X","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt"},{"first_name":"Calin C","full_name":"Guet, Calin C","orcid":"0000-0001-6220-2052","last_name":"Guet","id":"47F8433E-F248-11E8-B48F-1D18A9856A87"}],"date_published":"2021-11-18T00:00:00Z","citation":{"ista":"Tomasek K. 2021. Pathogenic Escherichia coli hijack the host immune response. Institute of Science and Technology Austria.","mla":"Tomasek, Kathrin. <i>Pathogenic Escherichia Coli Hijack the Host Immune Response</i>. Institute of Science and Technology Austria, 2021, doi:<a href=\"https://doi.org/10.15479/at:ista:10307\">10.15479/at:ista:10307</a>.","chicago":"Tomasek, Kathrin. “Pathogenic Escherichia Coli Hijack the Host Immune Response.” Institute of Science and Technology Austria, 2021. <a href=\"https://doi.org/10.15479/at:ista:10307\">https://doi.org/10.15479/at:ista:10307</a>.","ama":"Tomasek K. Pathogenic Escherichia coli hijack the host immune response. 2021. doi:<a href=\"https://doi.org/10.15479/at:ista:10307\">10.15479/at:ista:10307</a>","ieee":"K. Tomasek, “Pathogenic Escherichia coli hijack the host immune response,” Institute of Science and Technology Austria, 2021.","short":"K. Tomasek, Pathogenic Escherichia Coli Hijack the Host Immune Response, Institute of Science and Technology Austria, 2021.","apa":"Tomasek, K. (2021). <i>Pathogenic Escherichia coli hijack the host immune response</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:10307\">https://doi.org/10.15479/at:ista:10307</a>"},"date_created":"2021-11-18T15:05:06Z","year":"2021","degree_awarded":"PhD","related_material":{"record":[{"id":"10316","relation":"part_of_dissertation","status":"public"}]},"acknowledged_ssus":[{"_id":"LifeSc"},{"_id":"Bio"},{"_id":"PreCl"},{"_id":"EM-Fac"}],"file_date_updated":"2022-12-20T23:30:05Z","_id":"10307","doi":"10.15479/at:ista:10307"},{"publisher":"Institute of Science and Technology Austria","date_published":"2019-10-09T00:00:00Z","supervisor":[{"orcid":"0000-0002-6620-9179","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt","first_name":"Michael K","full_name":"Sixt, Michael K"}],"page":"142","department":[{"_id":"MiSi"}],"ddc":["570"],"abstract":[{"lang":"eng","text":"Lymph nodes  are es s ential organs  of the immune  s ys tem where adaptive immune responses originate, and consist of various leukocyte populations and a stromal backbone. Fibroblastic reticular  cells (FRCs) are  the  main  stromal  cells and  form  a sponge-like extracellular matrix network,   called  conduits ,  which  they   thems elves   enwrap   and  contract.  Lymph,  containing  s oluble  antigens ,  arrive in  lymph  nodes  via afferent lymphatic  vessels that  connect  to  the  s ubcaps ular  s inus   and  conduit  network.  According  to  the  current  paradigm,  the  conduit  network   dis tributes   afferent  lymph  through   lymph  nodes   and  thus   provides   acces s   for  immune  cells to lymph-borne  antigens. An  elas tic  caps ule  s urrounds   the  organ  and  confines   the immune  cells and  FRC  network.   Lymph   nodes   are  completely  packed  with  lymphocytes   and  lymphocyte  numbers  directly  dictates  the size  of  the  organ.  Although  lymphocytes   cons tantly  enter  and  leave  the  lymph  node,  its   s ize  remains   remarkedly   s table  under  homeostatic conditions. It is only partly known  how the cellularity and s ize of the lymph node is regulated and  how  the  lymph  node  is able to swell in inflammation.  The role of the FRC network   in  lymph  node   s welling  and  trans fer  of  fluids   are  inves tigated in  this   thes is.  Furthermore,   we  s tudied  what  trafficking  routes   are  us ed  by  cancer  cells   in  lymph  nodes   to  form  distal metastases.We examined the role of a mechanical feedback in regulation of lymph  node swelling. Using parallel plate compression  and UV-las er  cutting  experiments   we  dis s ected  the  mechanical  force dynamics  of the whole lymph  node, and individually for FRCs  and the  caps ule. Physical forces   generated  by  packed  lymphocytes   directly  affect  the  tens ion  on  the  FRC  network  and  capsule,  which  increases  its  resistance  to   swelling.  This  implies  a  feedback  mechanism  between   tis s ue   pres s ure   and   ability   of   lymphocytes    to   enter   the   organ.   Following   inflammation,  the  lymph  node  swells ∼10 fold in two weeks . Yet, what  is  the role  for tens ion on  the  FRC  network   and  caps ule,  and  how  are  lymphocytes   able  to  enter  in  conditions  that resist swelling remain open ques tions . We s how that tens ion on the FRC network is  important to  limit  the  swelling  rate  of  the  organ  so  that  the  FRC  network  can  grow  in  a  coordinated  fashion. This is illustrated by interfering with FRC contractility, which leads to faster swelling rates  and a dis organized FRC network  in the inflamed lymph  node. Growth  of the FRC network  in  turn  is   expected  to  releas e  tens ion  on  thes e  s tructures   and  lowers   the  res is tance  to  swelling, thereby allowing more lymphocytes to enter the organ and drive more swelling. Halt of  swelling coincides   with  a  thickening  of  the  caps ule,  which  forms   a  thick  res is tant  band  around  the organ and lowers  tens ion on the FRC network  to form a new force equilibrium.The  FRC  and  conduit   network   are  further   believed  to  be  a  privileged  s ite  of  s oluble  information  within  the  lymph  node,  although  many  details   remain  uns olved.  We  s how  by  3D  ultra-recons truction   that  FRCs   and  antigen  pres enting  cells   cover  the  s urface  of  conduit  s ys tem for more  than 99% and we dis cus s  the implications  for s oluble information  exchangeat the conduit level.Finally, there  is an ongoing debate in the cancer field whether and how cancer cells  in lymph nodes   s eed  dis tal  metas tas es .  We  s how  that  cancer  cells   infus ed  into  the  lymph  node  can  utilize trafficking routes of immune  cells and  rapidly  migrate  to  blood  vessels. Once  in  the  blood circulation,  these cells are able to form  metastases in distal tissues."}],"publication_status":"published","doi":"10.15479/AT:ISTA:6947","file_date_updated":"2020-11-07T23:30:03Z","_id":"6947","acknowledged_ssus":[{"_id":"Bio"},{"_id":"PreCl"},{"_id":"EM-Fac"}],"degree_awarded":"PhD","related_material":{"record":[{"id":"664","relation":"part_of_dissertation","status":"public"},{"id":"402","relation":"part_of_dissertation","status":"public"}]},"year":"2019","date_created":"2019-10-14T16:54:52Z","citation":{"apa":"Assen, F. P. (2019). <i>Lymph node mechanics: Deciphering the interplay between stroma contractility, morphology and lymphocyte trafficking</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:6947\">https://doi.org/10.15479/AT:ISTA:6947</a>","mla":"Assen, Frank P. <i>Lymph Node Mechanics: Deciphering the Interplay between Stroma Contractility, Morphology and Lymphocyte Trafficking</i>. Institute of Science and Technology Austria, 2019, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:6947\">10.15479/AT:ISTA:6947</a>.","ista":"Assen FP. 2019. Lymph node mechanics: Deciphering the interplay between stroma contractility, morphology and lymphocyte trafficking. Institute of Science and Technology Austria.","chicago":"Assen, Frank P. “Lymph Node Mechanics: Deciphering the Interplay between Stroma Contractility, Morphology and Lymphocyte Trafficking.” Institute of Science and Technology Austria, 2019. <a href=\"https://doi.org/10.15479/AT:ISTA:6947\">https://doi.org/10.15479/AT:ISTA:6947</a>.","ieee":"F. P. Assen, “Lymph node mechanics: Deciphering the interplay between stroma contractility, morphology and lymphocyte trafficking,” Institute of Science and Technology Austria, 2019.","ama":"Assen FP. Lymph node mechanics: Deciphering the interplay between stroma contractility, morphology and lymphocyte trafficking. 2019. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:6947\">10.15479/AT:ISTA:6947</a>","short":"F.P. Assen, Lymph Node Mechanics: Deciphering the Interplay between Stroma Contractility, Morphology and Lymphocyte Trafficking, Institute of Science and Technology Austria, 2019."},"alternative_title":["ISTA Thesis"],"type":"dissertation","status":"public","publication_identifier":{"issn":["2663-337X"]},"month":"10","oa_version":"Published Version","day":"9","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","file":[{"date_updated":"2020-11-07T23:30:03Z","date_created":"2019-11-06T12:30:02Z","file_id":"6990","checksum":"53a739752a500f84d0f8ec953cbbd0b6","file_name":"PhDthesis_FrankAssen_revised2.docx","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","access_level":"closed","file_size":214172667,"relation":"source_file","embargo_to":"open_access","creator":"fassen"},{"date_created":"2019-11-06T12:30:57Z","date_updated":"2020-11-07T23:30:03Z","embargo":"2020-11-06","checksum":"8c156b65d9347bb599623a4b09f15d15","file_id":"6991","file_name":"PhDthesis_FrankAssen_revised2.pdf","access_level":"open_access","file_size":83637532,"content_type":"application/pdf","relation":"main_file","creator":"fassen"}],"author":[{"orcid":"0000-0003-3470-6119","last_name":"Assen","id":"3A8E7F24-F248-11E8-B48F-1D18A9856A87","full_name":"Assen, Frank P","first_name":"Frank P"}],"language":[{"iso":"eng"}],"has_accepted_license":"1","date_updated":"2023-09-13T08:50:57Z","oa":1,"article_processing_charge":"No","title":"Lymph node mechanics: Deciphering the interplay between stroma contractility, morphology and lymphocyte trafficking"},{"ddc":["570"],"abstract":[{"text":"While cells of mesenchymal or epithelial origin perform their effector functions in a purely anchorage dependent manner, cells derived from the hematopoietic lineage are not committed to operate only within a specific niche. Instead, these cells are able to function autonomously of the molecular composition in a broad range of tissue compartments. By this means, cells of the hematopoietic lineage retain the capacity to disseminate into connective tissue and recirculate between organs, building the foundation for essential processes such as tissue regeneration or immune surveillance. \r\nCells of the immune system, specifically leukocytes, are extraordinarily good at performing this task. These cells are able to flexibly shift their mode of migration between an adhesion-mediated and an adhesion-independent manner, instantaneously accommodating for any changes in molecular composition of the external scaffold. The key component driving directed leukocyte migration is the chemokine receptor 7, which guides the cell along gradients of chemokine ligand. Therefore, the physical destination of migrating leukocytes is purely deterministic, i.e. given by global directional cues such as chemokine gradients. \r\nNevertheless, these cells typically reside in three-dimensional scaffolds of inhomogeneous complexity, raising the question whether cells are able to locally discriminate between multiple optional migration routes. Current literature provides evidence that leukocytes, specifically dendritic cells, do indeed probe their surrounding by virtue of multiple explorative protrusions. However, it remains enigmatic how these cells decide which one is the more favorable route to follow and what are the key players involved in performing this task. Due to the heterogeneous environment of most tissues, and the vast adaptability of migrating leukocytes, at this time it is not clear to what extent leukocytes are able to optimize their migratory strategy by adapting their level of adhesiveness. And, given the fact that leukocyte migration is characterized by branched cell shapes in combination with high migration velocities, it is reasonable to assume that these cells require fine tuned shape maintenance mechanisms that tightly coordinate protrusion and adhesion dynamics in a spatiotemporal manner. \r\nTherefore, this study aimed to elucidate how rapidly migrating leukocytes opt for an ideal migratory path while maintaining a continuous cell shape and balancing adhesive forces to efficiently navigate through complex microenvironments. \r\nThe results of this study unraveled a role for the microtubule cytoskeleton in promoting the decision making process during path finding and for the first time point towards a microtubule-mediated function in cell shape maintenance of highly ramified cells such as dendritic cells. Furthermore, we found that migrating low-adhesive leukocytes are able to instantaneously adapt to increased tensile load by engaging adhesion receptors. This response was only occurring tangential to the substrate while adhesive properties in the vertical direction were not increased. As leukocytes are primed for rapid migration velocities, these results demonstrate that leukocyte integrins are able to confer a high level of traction forces parallel to the cell membrane along the direction of migration without wasting energy in gluing the cell to the substrate. \r\nThus, the data in the here presented thesis provide new insights into the pivotal role of cytoskeletal dynamics and the mechanisms of force transduction during leukocyte migration. \r\nThereby the here presented results help to further define fundamental principles underlying leukocyte migration and open up potential therapeutic avenues of clinical relevance.\r\n","lang":"eng"}],"publication_status":"published","publisher":"Institute of Science and Technology Austria","supervisor":[{"last_name":"Sixt","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-6620-9179","first_name":"Michael K","full_name":"Sixt, Michael K"}],"date_published":"2019-07-24T00:00:00Z","page":"171","department":[{"_id":"MiSi"}],"project":[{"grant_number":"W01250-B20","_id":"265E2996-B435-11E9-9278-68D0E5697425","name":"Nano-Analytics of Cellular Systems","call_identifier":"FWF"}],"related_material":{"link":[{"url":"https://ist.ac.at/en/news/feeling-like-a-cell/","relation":"press_release"}],"record":[{"status":"public","id":"6328","relation":"part_of_dissertation"},{"relation":"part_of_dissertation","id":"15","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"6877"}]},"degree_awarded":"PhD","year":"2019","date_created":"2019-09-19T08:19:44Z","citation":{"mla":"Kopf, Aglaja. <i>The Implication of Cytoskeletal Dynamics on Leukocyte Migration</i>. Institute of Science and Technology Austria, 2019, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:6891\">10.15479/AT:ISTA:6891</a>.","chicago":"Kopf, Aglaja. “The Implication of Cytoskeletal Dynamics on Leukocyte Migration.” Institute of Science and Technology Austria, 2019. <a href=\"https://doi.org/10.15479/AT:ISTA:6891\">https://doi.org/10.15479/AT:ISTA:6891</a>.","ista":"Kopf A. 2019. The implication of cytoskeletal dynamics on leukocyte migration. Institute of Science and Technology Austria.","ama":"Kopf A. The implication of cytoskeletal dynamics on leukocyte migration. 2019. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:6891\">10.15479/AT:ISTA:6891</a>","ieee":"A. Kopf, “The implication of cytoskeletal dynamics on leukocyte migration,” Institute of Science and Technology Austria, 2019.","short":"A. Kopf, The Implication of Cytoskeletal Dynamics on Leukocyte Migration, Institute of Science and Technology Austria, 2019.","apa":"Kopf, A. (2019). <i>The implication of cytoskeletal dynamics on leukocyte migration</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:6891\">https://doi.org/10.15479/AT:ISTA:6891</a>"},"keyword":["cell biology","immunology","leukocyte","migration","microfluidics"],"doi":"10.15479/AT:ISTA:6891","file_date_updated":"2020-10-17T22:30:03Z","_id":"6891","month":"07","publication_identifier":{"isbn":["978-3-99078-002-2"],"eissn":["2663-337X"]},"day":"24","oa_version":"Published Version","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","file":[{"date_updated":"2020-10-17T22:30:03Z","date_created":"2019-10-15T05:28:42Z","checksum":"00d100d6468e31e583051e0a006b640c","file_id":"6950","file_name":"Kopf_PhD_Thesis.docx","relation":"source_file","file_size":74735267,"access_level":"closed","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","embargo_to":"open_access","creator":"akopf"},{"content_type":"application/pdf","file_size":52787224,"relation":"main_file","access_level":"open_access","creator":"akopf","date_updated":"2020-10-17T22:30:03Z","date_created":"2019-10-15T05:28:47Z","file_id":"6951","checksum":"5d1baa899993ae6ca81aebebe1797000","file_name":"Kopf_PhD_Thesis1.pdf","embargo":"2020-10-16"}],"author":[{"full_name":"Kopf, Aglaja","first_name":"Aglaja","id":"31DAC7B6-F248-11E8-B48F-1D18A9856A87","last_name":"Kopf","orcid":"0000-0002-2187-6656"}],"alternative_title":["ISTA Thesis"],"type":"dissertation","status":"public","has_accepted_license":"1","oa":1,"date_updated":"2023-10-18T08:49:17Z","article_processing_charge":"No","title":"The implication of cytoskeletal dynamics on leukocyte migration","language":[{"iso":"eng"}]},{"doi":"10.15479/AT:ISTA:th_998","file_date_updated":"2021-02-11T23:30:17Z","_id":"323","acknowledged_ssus":[{"_id":"NanoFab"},{"_id":"Bio"},{"_id":"PreCl"},{"_id":"EM-Fac"}],"degree_awarded":"PhD","related_material":{"record":[{"relation":"part_of_dissertation","id":"1321","status":"public"}]},"acknowledgement":"First of all I would like to thank Michael Sixt for giving me the opportunity to work in \r\nhis group and for his support throughout the years. He is a truly inspiring person and \r\nthe  best  boss  one  can  imagine.  I  would  also  like  to  thank  all  current  and  past \r\nmembers of the Sixt group for their help and the great working atmosphere in the lab. \r\nIt is a true privilege to work with such a bright, funny and friendly group of people and \r\nI’m  proud  that  I  could  be  part  of  it.  Furthermore,  I  would  like  to  say  ‘thank  you’  to Daria Siekhaus for all the meetings and discussion we had throughout the years \r\nand to  Federica  Benvenuti  for  being  part  of  my  committee.  I  am  also  grateful  to  Jack \r\nMerrin  in  the  nanofabrication  facility  and  all  the  people  working  in  the  bioimaging-\r\n, the electron microscopy- and the preclinical facilities.","year":"2018","publist_id":"7542","date_created":"2018-12-11T11:45:49Z","citation":{"apa":"Leithner, A. F. (2018). <i>Branched actin networks in dendritic cell biology</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:th_998\">https://doi.org/10.15479/AT:ISTA:th_998</a>","chicago":"Leithner, Alexander F. “Branched Actin Networks in Dendritic Cell Biology.” Institute of Science and Technology Austria, 2018. <a href=\"https://doi.org/10.15479/AT:ISTA:th_998\">https://doi.org/10.15479/AT:ISTA:th_998</a>.","ista":"Leithner AF. 2018. Branched actin networks in dendritic cell biology. Institute of Science and Technology Austria.","mla":"Leithner, Alexander F. <i>Branched Actin Networks in Dendritic Cell Biology</i>. Institute of Science and Technology Austria, 2018, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:th_998\">10.15479/AT:ISTA:th_998</a>.","ieee":"A. F. Leithner, “Branched actin networks in dendritic cell biology,” Institute of Science and Technology Austria, 2018.","ama":"Leithner AF. Branched actin networks in dendritic cell biology. 2018. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:th_998\">10.15479/AT:ISTA:th_998</a>","short":"A.F. Leithner, Branched Actin Networks in Dendritic Cell Biology, Institute of Science and Technology Austria, 2018."},"publisher":"Institute of Science and Technology Austria","date_published":"2018-04-12T00:00:00Z","supervisor":[{"orcid":"0000-0002-6620-9179","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt","full_name":"Sixt, Michael K","first_name":"Michael K"}],"page":"99","department":[{"_id":"MiSi"}],"ddc":["571","599","610"],"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)","image":"/images/cc_by.png","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"abstract":[{"text":"In the here presented thesis, we explore the role of branched actin networks in cell migration and antigen presentation, the two most relevant processes in dendritic cell biology. Branched actin networks construct lamellipodial protrusions at the leading edge of migrating cells. These are typically seen as adhesive structures, which mediate force transduction to the extracellular matrix that leads to forward locomotion. We ablated Arp2/3 nucleation promoting factor WAVE in DCs and found that the resulting cells lack lamellipodial protrusions. Instead, depending on the maturation state, one or multiple filopodia were formed. By challenging these cells in a variety of migration assays we found that lamellipodial protrusions are dispensable for the locomotion of leukocytes and actually dampen the speed of migration. However, lamellipodia are critically required to negotiate complex environments that DCs experience while they travel to the next draining lymph node. Taken together our results suggest that leukocyte lamellipodia have rather a sensory- than a force transducing function. Furthermore, we show for the first time structure and dynamics of dendritic cell F-actin at the immunological synapse with naïve T cells. Dendritic cell F-actin appears as dynamic foci that are nucleated by the Arp2/3 complex. WAVE ablated dendritic cells show increased membrane tension, leading to an altered ultrastructure of the immunological synapse and severe T cell priming defects. These results point towards a previously unappreciated role of the cellular mechanics of dendritic cells in T cell activation. Additionally, we present a novel cell culture based system for the differentiation of dendritic cells from conditionally immortalized hematopoietic precursors. These precursor cells are genetically tractable via the CRISPR/Cas9 system while they retain their ability to differentiate into highly migratory dendritic cells and other immune cells. This will foster the study of all aspects of dendritic cell biology and beyond. ","lang":"eng"}],"publication_status":"published","language":[{"iso":"eng"}],"has_accepted_license":"1","oa":1,"date_updated":"2023-09-07T12:39:44Z","pubrep_id":"998","article_processing_charge":"No","title":"Branched actin networks in dendritic cell biology","alternative_title":["ISTA Thesis"],"type":"dissertation","status":"public","month":"04","publication_identifier":{"issn":["2663-337X"]},"day":"12","oa_version":"Published Version","file":[{"embargo_to":"open_access","creator":"dernst","file_size":29027671,"access_level":"closed","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","relation":"source_file","file_name":"PhD_thesis_AlexLeithner_final_version.docx","file_id":"6219","checksum":"d5e3edbac548c26c1fa43a4b37a54a4c","date_updated":"2021-02-11T23:30:17Z","date_created":"2019-04-05T09:23:11Z"},{"date_updated":"2021-02-11T11:17:16Z","date_created":"2019-04-05T09:23:11Z","file_id":"6220","checksum":"071f7476db29e41146824ebd0697cb10","file_name":"PhD_thesis_AlexLeithner.pdf","embargo":"2019-04-15","access_level":"open_access","relation":"main_file","file_size":66045341,"content_type":"application/pdf","creator":"dernst"}],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","author":[{"orcid":"0000-0002-1073-744X","id":"3B1B77E4-F248-11E8-B48F-1D18A9856A87","last_name":"Leithner","first_name":"Alexander F","full_name":"Leithner, Alexander F"}]},{"acknowledged_ssus":[{"_id":"Bio"},{"_id":"PreCl"},{"_id":"LifeSc"}],"_id":"1129","file_date_updated":"2021-02-22T11:43:14Z","degree_awarded":"PhD","publist_id":"6231","date_created":"2018-12-11T11:50:18Z","citation":{"mla":"Schwarz, Jan. <i>Quantitative Analysis of Haptotactic Cell Migration</i>. Institute of Science and Technology Austria, 2016.","ista":"Schwarz J. 2016. Quantitative analysis of haptotactic cell migration. Institute of Science and Technology Austria.","chicago":"Schwarz, Jan. “Quantitative Analysis of Haptotactic Cell Migration.” Institute of Science and Technology Austria, 2016.","ieee":"J. Schwarz, “Quantitative analysis of haptotactic cell migration,” Institute of Science and Technology Austria, 2016.","ama":"Schwarz J. Quantitative analysis of haptotactic cell migration. 2016.","short":"J. Schwarz, Quantitative Analysis of Haptotactic Cell Migration, Institute of Science and Technology Austria, 2016.","apa":"Schwarz, J. (2016). <i>Quantitative analysis of haptotactic cell migration</i>. Institute of Science and Technology Austria."},"year":"2016","acknowledgement":"First, I would like to thank Michael Sixt for being a great supervisor, mentor and\r\nscientist. I highly appreciate his guidance and continued support. Furthermore, I\r\nam very grateful that he gave me the exceptional opportunity to pursue many\r\nideas of which some managed to be included in this thesis.\r\nI owe sincere thanks to the members of my PhD thesis committee, Daria\r\nSiekhaus, Daniel Legler and Harald Janovjak. Especially I would like to thank\r\nDaria for her advice and encouragement during our regular progress meetings.\r\nI also want to thank the team and fellows of the Boehringer Ingelheim Fond\r\n(BIF) PhD Fellowship for amazing and inspiring meetings and the BIF for\r\nfinancial support.\r\nImportant factors for the success of this thesis were the warm, creative\r\nand helpful atmosphere as well as the team spirit of the whole Sixt Lab.\r\nTherefore I would like to thank my current and former colleagues Frank Assen,\r\nMarkus Brown, Ingrid de Vries, Michelle Duggan, Alexander Eichner, Miroslav\r\nHons, Eva Kiermaier, Aglaja Kopf, Alexander Leithner, Christine Moussion, Jan\r\nMüller, Maria Nemethova, Jörg Renkawitz, Anne Reversat, Kari Vaahtomeri,\r\nMichele Weber and Stefan Wieser. We had an amazing time with many\r\nlegendary evenings and events. Along these lines I want to thank the in vitro\r\ncrew of the lab, Jörg, Anne and Alex, for lots of ideas and productive\r\ndiscussions. I am sure, some day we will reveal the secret of the ‘splodge’.\r\nI want to thank the members of the Heisenberg Lab for a great time and\r\nthrilling kicker matches. In this regard I especially want to thank Maurizio\r\n‘Gnocci’ Monti, Gabriel Krens, Alex Eichner, Martin Behrndt, Vanessa Barone,Philipp Schmalhorst, Michael Smutny, Daniel Capek, Anne Reversat, Eva\r\nKiermaier, Frank Assen and Jan Müller for wonderful after-lunch matches.\r\nI would not have been able to analyze the thousands of cell trajectories\r\nand probably hundreds of thousands of mouse clicks without the productive\r\ncollaboration with Veronika Bierbaum and Tobias Bollenbach. Thanks Vroni for\r\ncountless meetings, discussions and graphs and of course for proofreading and\r\nadvice for this thesis. For proofreading I also want to thank Evi, Jörg, Jack and\r\nAnne.\r\nI would like to acknowledge Matthias Mehling for a very productive\r\ncollaboration and for introducing me into the wild world of microfluidics. Jack\r\nMerrin, for countless wafers, PDMS coated coverslips and help with anything\r\nmicro-fabrication related. And Maria Nemethova for establishing the ‘click’\r\npatterning approach with me. Without her it still would be just one of the ideas…\r\nMany thanks to Ekaterina Papusheva, Robert Hauschild, Doreen Milius\r\nand Nasser Darwish from the Bioimaging Facility as well as the Preclinical and\r\nthe Life Science facilities of IST Austria for excellent technical support. At this\r\npoint I especially want to thank Robert for countless image analyses and\r\ntechnical ideas. Always interested and creative he played an essential role in all\r\nof my projects.\r\nAdditionally I want to thank Ingrid and Gabby for welcoming me warmly\r\nwhen I first started at IST, for scientific and especially mental support in all\r\nthose years, countless coffee sessions and Heurigen evenings. #BioimagingFacility #LifeScienceFacility #PreClinicalFacility","page":"178","department":[{"_id":"MiSi"}],"supervisor":[{"id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt","orcid":"0000-0002-6620-9179","first_name":"Michael K","full_name":"Sixt, Michael K"}],"date_published":"2016-07-01T00:00:00Z","publisher":"Institute of Science and Technology Austria","abstract":[{"lang":"eng","text":"Directed cell migration is a hallmark feature, present in almost all multi-cellular\r\norganisms. Despite its importance, basic questions regarding force transduction\r\nor directional sensing are still heavily investigated. Directed migration of cells\r\nguided by immobilized guidance cues - haptotaxis - occurs in key-processes,\r\nsuch as embryonic development and immunity (Middleton et al., 1997; Nguyen\r\net al., 2000; Thiery, 1984; Weber et al., 2013). Immobilized guidance cues\r\ncomprise adhesive ligands, such as collagen and fibronectin (Barczyk et al.,\r\n2009), or chemokines - the main guidance cues for migratory leukocytes\r\n(Middleton et al., 1997; Weber et al., 2013). While adhesive ligands serve as\r\nattachment sites guiding cell migration (Carter, 1965), chemokines instruct\r\nhaptotactic migration by inducing adhesion to adhesive ligands and directional\r\nguidance (Rot and Andrian, 2004; Schumann et al., 2010). Quantitative analysis\r\nof the cellular response to immobilized guidance cues requires in vitro assays\r\nthat foster cell migration, offer accurate control of the immobilized cues on a\r\nsubcellular scale and in the ideal case closely reproduce in vivo conditions. The\r\nexploration of haptotactic cell migration through design and employment of such\r\nassays represents the main focus of this work.\r\nDendritic cells (DCs) are leukocytes, which after encountering danger\r\nsignals such as pathogens in peripheral organs instruct naïve T-cells and\r\nconsequently the adaptive immune response in the lymph node (Mellman and\r\nSteinman, 2001). To reach the lymph node from the periphery, DCs follow\r\nhaptotactic gradients of the chemokine CCL21 towards lymphatic vessels\r\n(Weber et al., 2013). Questions about how DCs interpret haptotactic CCL21\r\ngradients have not yet been addressed. The main reason for this is the lack of\r\nan assay that offers diverse haptotactic environments, hence allowing the study\r\nof DC migration as a response to different signals of immobilized guidance cue.\r\nIn this work, we developed an in vitro assay that enables us to\r\nquantitatively assess DC haptotaxis, by combining precisely controllable\r\nchemokine photo-patterning with physically confining migration conditions. With this tool at hand, we studied the influence of CCL21 gradient properties and\r\nconcentration on DC haptotaxis. We found that haptotactic gradient sensing\r\ndepends on the absolute CCL21 concentration in combination with the local\r\nsteepness of the gradient. Our analysis suggests that the directionality of\r\nmigrating DCs is governed by the signal-to-noise ratio of CCL21 binding to its\r\nreceptor CCR7. Moreover, the haptotactic CCL21 gradient formed in vivo\r\nprovides an optimal shape for DCs to recognize haptotactic guidance cue.\r\nBy reconstitution of the CCL21 gradient in vitro we were also able to\r\nstudy the influence of CCR7 signal termination on DC haptotaxis. To this end,\r\nwe used DCs lacking the G-protein coupled receptor kinase GRK6, which is\r\nresponsible for CCL21 induced CCR7 receptor phosphorylation and\r\ndesensitization (Zidar et al., 2009). We found that CCR7 desensitization by\r\nGRK6 is crucial for maintenance of haptotactic CCL21 gradient sensing in vitro\r\nand confirm those observations in vivo.\r\nIn the context of the organism, immobilized haptotactic guidance cues\r\noften coincide and compete with soluble chemotactic guidance cues. During\r\nwound healing, fibroblasts are exposed and influenced by adhesive cues and\r\nsoluble factors at the same time (Wu et al., 2012; Wynn, 2008). Similarly,\r\nmigrating DCs are exposed to both, soluble chemokines (CCL19 and truncated\r\nCCL21) inducing chemotactic behavior as well as the immobilized CCL21. To\r\nquantitatively assess these complex coinciding immobilized and soluble\r\nguidance cues, we implemented our chemokine photo-patterning technique in a\r\nmicrofluidic system allowing for chemotactic gradient generation. To validate\r\nthe assay, we observed DC migration in competing CCL19/CCL21\r\nenvironments.\r\nAdhesiveness guided haptotaxis has been studied intensively over the\r\nlast century. However, quantitative studies leading to conceptual models are\r\nlargely missing, again due to the lack of a precisely controllable in vitro assay. A\r\nrequirement for such an in vitro assay is that it must prevent any uncontrolled\r\ncell adhesion. This can be accomplished by stable passivation of the surface. In\r\naddition, controlled adhesion must be sustainable, quantifiable and dose\r\ndependent in order to create homogenous gradients. Therefore, we developed a novel covalent photo-patterning technique satisfying all these needs. In\r\ncombination with a sustainable poly-vinyl alcohol (PVA) surface coating we\r\nwere able to generate gradients of adhesive cue to direct cell migration. This\r\napproach allowed us to characterize the haptotactic migratory behavior of\r\nzebrafish keratocytes in vitro. Furthermore, defined patterns of adhesive cue\r\nallowed us to control for cell shape and growth on a subcellular scale."}],"ddc":["570"],"publication_status":"published","language":[{"iso":"eng"}],"has_accepted_license":"1","title":"Quantitative analysis of haptotactic cell migration","article_processing_charge":"No","oa":1,"date_updated":"2023-09-07T11:54:33Z","type":"dissertation","status":"public","alternative_title":["ISTA Thesis"],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","file":[{"creator":"dernst","file_size":32044069,"content_type":"application/pdf","relation":"main_file","access_level":"closed","file_id":"6813","checksum":"e3cd6b28f9c5cccb8891855565a2dade","file_name":"Thesis_JSchwarz_final.pdf","date_created":"2019-08-13T10:55:35Z","date_updated":"2019-08-13T10:55:35Z"},{"file_size":8396717,"relation":"main_file","content_type":"application/pdf","access_level":"open_access","creator":"dernst","date_created":"2021-02-22T11:43:14Z","date_updated":"2021-02-22T11:43:14Z","success":1,"file_id":"9181","checksum":"c3dbe219acf87eed2f46d21d5cca00de","file_name":"2016_Thesis_JSchwarz.pdf"}],"day":"01","oa_version":"Published Version","publication_identifier":{"issn":["2663-337X"]},"month":"07","author":[{"first_name":"Jan","full_name":"Schwarz, Jan","last_name":"Schwarz","id":"346C1EC6-F248-11E8-B48F-1D18A9856A87"}]},{"page":"141","department":[{"_id":"MiSi"}],"date_published":"2011-03-01T00:00:00Z","supervisor":[{"first_name":"Michael K","full_name":"Sixt, Michael K","id":"41E9FBEA-F248-11E8-B48F-1D18A9856A87","last_name":"Sixt","orcid":"0000-0002-6620-9179"}],"publisher":"Institute of Science and Technology Austria","publication_status":"published","abstract":[{"lang":"eng","text":"Chemokines organize immune cell trafficking by inducing either directed (tactic) or random (kinetic) migration and by activating integrins in order to support surface adhesion (haptic). Beyond that the same chemokines can establish clearly defined functional areas in secondary lymphoid organs. Until now it is unclear how chemokines can fulfill such diverse functions. One decisive prerequisite to explain these capacities is to know how chemokines are presented in tissue. In theory chemokines could occur either soluble or immobilized, and could be distributed either homogenously or as a concentration gradient. To dissect if and how the presenting mode of chemokines influences immune cells, I tested the response of dendritic cells (DCs) to differentially displayed chemokines. DCs are antigen presenting cells that reside in the periphery and migrate into draining lymph nodes (LNs) once exposed to inflammatory stimuli to activate naïve T cells. DCs are guided to and within the LN by the chemokine receptor CCR7, which has two ligands, the chemokines CCL19 and CCL21. Both CCR7 ligands are expressed by fibroblastic reticular cells in the LN, but differ in their ability to bind to heparan sulfate residues. CCL21 has a highly charged C-terminal extension, which mediates binding to anionic surfaces, whereas CCL19 is lacking such residues and likely distributes as a soluble molecule. This study shows that surface-bound CCL21 causes random, haptokinetic DC motility, which is confined to the chemokine coated area by insideout activation of β2 integrins that mediate cell binding to the surface. CCL19 on the other hand forms concentration gradients which trigger directional, chemotactic movement, but no surface adhesion. In addition DCs can actively manipulate this system by recruiting and activating serine proteases on their surfaces, which create - by proteolytically removing the adhesive C-terminus - a solubilized variant of CCL21 that functionally resembles CCL19. By generating a CCL21 concentration gradient DCs establish a positive feedback loop to recruit further DCs from the periphery to the CCL21 coated region. In addition DCs can sense chemotactic gradients as well as immobilized haptokinetic fields at the same time and integrate these signals. The result is chemotactically biased haptokinesis - directional migration confined to a chemokine coated track or area - which could explain the dynamic but spatially tightly controlled swarming leukocyte locomotion patterns that have been observed in lymphatic organs by intravital microscopists. The finding that DCs can approach soluble cues in a non-adhesive manner while they attach to surfaces coated with immobilized cues raises the question how these cells transmit intracellular forces to the environment, especially in the non-adherent migration mode. In order to migrate, cells have to generate and transmit force to the extracellular substrate. Force transmission is the prerequisite to procure an expansion of the leading edge and a forward motion of the whole cell body. In the current conceptions actin polymerization at the leading edge is coupled to extracellular ligands via the integrin family of transmembrane receptors, which allows the transmission of intracellular force. Against the paradigm of force transmission during migration, leukocytes, like DCs, are able to migrate in threedimensional environments without using integrin transmembrane receptors (Lämmermann et al., 2008). This reflects the biological function of leukocytes, as they can invade almost all tissues, whereby their migration has to be independent from the extracellular environment. How the cells can achieve this is unclear. For this study I examined DC migration in a defined threedimensional environment and highlighted actin-dynamics with the probe Lifeact-GFP. The result was that chemotactic DCs can switch between integrin-dependent and integrin- independent locomotion and can thereby adapt to the adhesive properties of their environment. If the cells are able to couple their actin cytoskeleton to the substrate, actin polymerization is entirely converted into protrusion. Without coupling the actin cortex undergoes slippage and retrograde actin flow can be observed. But retrograde actin flow can be completely compensated by higher actin polymerization rate keeping the migration velocity and the shape of the cells unaltered. Mesenchymal cells like fibroblast cannot balance the loss of adhesive interaction, cannot protrude into open space and, therefore, strictly depend on integrinmediated force coupling. This leukocyte specific phenomenon of “adaptive force transmission” endows these cells with the unique ability to transit and invade almost every type of tissue. "}],"ddc":["570","579"],"_id":"3275","file_date_updated":"2021-02-22T11:24:30Z","citation":{"ieee":"K. Schumann, “The role of chemotactic gradients in dendritic cell migration,” Institute of Science and Technology Austria, 2011.","ama":"Schumann K. The role of chemotactic gradients in dendritic cell migration. 2011.","short":"K. Schumann, The Role of Chemotactic Gradients in Dendritic Cell Migration, Institute of Science and Technology Austria, 2011.","mla":"Schumann, Kathrin. <i>The Role of Chemotactic Gradients in Dendritic Cell Migration</i>. Institute of Science and Technology Austria, 2011.","chicago":"Schumann, Kathrin. “The Role of Chemotactic Gradients in Dendritic Cell Migration.” Institute of Science and Technology Austria, 2011.","ista":"Schumann K. 2011. The role of chemotactic gradients in dendritic cell migration. Institute of Science and Technology Austria.","apa":"Schumann, K. (2011). <i>The role of chemotactic gradients in dendritic cell migration</i>. Institute of Science and Technology Austria."},"date_created":"2018-12-11T12:02:24Z","publist_id":"3371","year":"2011","acknowledgement":"I would like to express my sincere gratitude to the following people who made with their continuous support and encouragement this thesis possible: First, I want to thank Prof. Dr. Michael Sixt for his excellent supervision and mentoring, especially for the nice, relaxed working atmosphere, a lot of brilliant ideas and the freedom to work in my own way.\r\n\r\nProf. Dr. Reinhard Fässler for his constant support of the Sixt lab and for providing excellent working conditions. \r\n\r\nProf. Dr. Sanjiv Luther and Prof. Dr. Tobias Bollenbach for agreeing to be member of my thesis committee and to evaluate my work.\r\n\r\nDr. Walther Göhring, Carmen Schmitz, the Recombinant Protein Production core facility and the animal care takers for providing the “infrastructure” for this thesis. \r\n\r\nProf. Dr. Daniel Legler, Markus Bruckner and Dr. Julien Polleux for very fruitful collaborations and discussions.\r\n\r\nMy labmates for their help, a lot of discussions and to make the Sixt lab to a convenient place to work : Karin Hirsch, Tim Lämmeramnn, Holger Pflicke, Jörg Renkawitz, Michele Weber and Alexander Eichner All members of the Department of Molecular Medicine for their help. Especially I want to thank Sarah Schmidt, Karin Hirsch and Raphael Ruppert for their friendship, nice chats and their uncensored point of view. ","degree_awarded":"PhD","type":"dissertation","status":"public","alternative_title":["ISTA Thesis"],"author":[{"full_name":"Schumann, Kathrin","first_name":"Kathrin","last_name":"Schumann","id":"F44D762E-4F9D-11E9-B64C-9EB26CEFFB5F"}],"file":[{"file_name":"2011_Thesis_Kathrin_Schumann.pdf","file_id":"6177","checksum":"e69eee6252660f0b694a2ea8923ddc72","date_updated":"2020-07-14T12:46:06Z","date_created":"2019-03-26T08:12:21Z","creator":"dernst","relation":"main_file","file_size":4487708,"content_type":"application/pdf","access_level":"closed"},{"file_id":"9175","checksum":"71727d63f424b5b446f68f4b87ecadc0","file_name":"2011_Thesis_Schumann_noS.pdf","success":1,"date_updated":"2021-02-22T11:24:30Z","date_created":"2021-02-22T11:24:30Z","creator":"dernst","access_level":"open_access","content_type":"application/pdf","relation":"main_file","file_size":4313127}],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","oa_version":"Published Version","day":"01","month":"03","publication_identifier":{"issn":["2663-337X"]},"language":[{"iso":"eng"}],"title":"The role of chemotactic gradients in dendritic cell migration","article_processing_charge":"No","date_updated":"2023-09-07T11:31:48Z","oa":1,"pubrep_id":"11","has_accepted_license":"1"}]