--- _id: '323' abstract: - lang: eng 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. ' acknowledged_ssus: - _id: NanoFab - _id: Bio - _id: PreCl - _id: EM-Fac 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." alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Alexander F full_name: Leithner, Alexander F id: 3B1B77E4-F248-11E8-B48F-1D18A9856A87 last_name: Leithner orcid: 0000-0002-1073-744X citation: ama: Leithner AF. Branched actin networks in dendritic cell biology. 2018. doi:10.15479/AT:ISTA:th_998 apa: Leithner, A. F. (2018). Branched actin networks in dendritic cell biology. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_998 chicago: Leithner, Alexander F. “Branched Actin Networks in Dendritic Cell Biology.” Institute of Science and Technology Austria, 2018. https://doi.org/10.15479/AT:ISTA:th_998. ieee: A. F. Leithner, “Branched actin networks in dendritic cell biology,” Institute of Science and Technology Austria, 2018. ista: Leithner AF. 2018. Branched actin networks in dendritic cell biology. Institute of Science and Technology Austria. mla: Leithner, Alexander F. Branched Actin Networks in Dendritic Cell Biology. Institute of Science and Technology Austria, 2018, doi:10.15479/AT:ISTA:th_998. short: A.F. Leithner, Branched Actin Networks in Dendritic Cell Biology, Institute of Science and Technology Austria, 2018. date_created: 2018-12-11T11:45:49Z date_published: 2018-04-12T00:00:00Z date_updated: 2023-09-07T12:39:44Z day: '12' ddc: - '571' - '599' - '610' degree_awarded: PhD department: - _id: MiSi doi: 10.15479/AT:ISTA:th_998 file: - access_level: closed checksum: d5e3edbac548c26c1fa43a4b37a54a4c content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document creator: dernst date_created: 2019-04-05T09:23:11Z date_updated: 2021-02-11T23:30:17Z embargo_to: open_access file_id: '6219' file_name: PhD_thesis_AlexLeithner_final_version.docx file_size: 29027671 relation: source_file - access_level: open_access checksum: 071f7476db29e41146824ebd0697cb10 content_type: application/pdf creator: dernst date_created: 2019-04-05T09:23:11Z date_updated: 2021-02-11T11:17:16Z embargo: 2019-04-15 file_id: '6220' file_name: PhD_thesis_AlexLeithner.pdf file_size: 66045341 relation: main_file file_date_updated: 2021-02-11T23:30:17Z has_accepted_license: '1' language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '04' oa: 1 oa_version: Published Version page: '99' publication_identifier: issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria publist_id: '7542' pubrep_id: '998' related_material: record: - id: '1321' relation: part_of_dissertation status: public status: public supervisor: - first_name: Michael K full_name: Sixt, Michael K id: 41E9FBEA-F248-11E8-B48F-1D18A9856A87 last_name: Sixt orcid: 0000-0002-6620-9179 title: Branched actin networks in dendritic cell biology tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: dissertation user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 year: '2018' ...