---
_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.
corr_author: '1'
date_created: 2018-12-11T11:45:49Z
date_published: 2018-04-12T00:00:00Z
date_updated: 2025-09-22T08:27:34Z
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
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'
...
---
_id: '326'
abstract:
- lang: eng
text: Three-dimensional (3D) super-resolution microscopy technique structured illumination
microscopy (SIM) imaging of dendritic spines along the dendrite has not been previously
performed in fixed tissues, mainly due to deterioration of the stripe pattern
of the excitation laser induced by light scattering and optical aberrations. To
address this issue and solve these optical problems, we applied a novel clearing
reagent, LUCID, to fixed brains. In SIM imaging, the penetration depth and the
spatial resolution were improved in LUCID-treated slices, and 160-nm spatial resolution
was obtained in a large portion of the imaging volume on a single apical dendrite.
Furthermore, in a morphological analysis of spine heads of layer V pyramidal neurons
(L5PNs) in the medial prefrontal cortex (mPFC) of chronic dexamethasone (Dex)-treated
mice, SIM imaging revealed an altered distribution of spine forms that could not
be detected by high-NA confocal imaging. Thus, super-resolution SIM imaging represents
a promising high-throughput method for revealing spine morphologies in single
dendrites.
acknowledged_ssus:
- _id: EM-Fac
article_processing_charge: No
author:
- first_name: Kazuaki
full_name: Sawada, Kazuaki
last_name: Sawada
- first_name: Ryosuke
full_name: Kawakami, Ryosuke
last_name: Kawakami
- first_name: Ryuichi
full_name: Shigemoto, Ryuichi
id: 499F3ABC-F248-11E8-B48F-1D18A9856A87
last_name: Shigemoto
orcid: 0000-0001-8761-9444
- first_name: Tomomi
full_name: Nemoto, Tomomi
last_name: Nemoto
citation:
ama: Sawada K, Kawakami R, Shigemoto R, Nemoto T. Super resolution structural analysis
of dendritic spines using three-dimensional structured illumination microscopy
in cleared mouse brain slices. European Journal of Neuroscience. 2018;47(9):1033-1042.
doi:10.1111/ejn.13901
apa: Sawada, K., Kawakami, R., Shigemoto, R., & Nemoto, T. (2018). Super resolution
structural analysis of dendritic spines using three-dimensional structured illumination
microscopy in cleared mouse brain slices. European Journal of Neuroscience.
Wiley. https://doi.org/10.1111/ejn.13901
chicago: Sawada, Kazuaki, Ryosuke Kawakami, Ryuichi Shigemoto, and Tomomi Nemoto.
“Super Resolution Structural Analysis of Dendritic Spines Using Three-Dimensional
Structured Illumination Microscopy in Cleared Mouse Brain Slices.” European
Journal of Neuroscience. Wiley, 2018. https://doi.org/10.1111/ejn.13901.
ieee: K. Sawada, R. Kawakami, R. Shigemoto, and T. Nemoto, “Super resolution structural
analysis of dendritic spines using three-dimensional structured illumination microscopy
in cleared mouse brain slices,” European Journal of Neuroscience, vol.
47, no. 9. Wiley, pp. 1033–1042, 2018.
ista: Sawada K, Kawakami R, Shigemoto R, Nemoto T. 2018. Super resolution structural
analysis of dendritic spines using three-dimensional structured illumination microscopy
in cleared mouse brain slices. European Journal of Neuroscience. 47(9), 1033–1042.
mla: Sawada, Kazuaki, et al. “Super Resolution Structural Analysis of Dendritic
Spines Using Three-Dimensional Structured Illumination Microscopy in Cleared Mouse
Brain Slices.” European Journal of Neuroscience, vol. 47, no. 9, Wiley,
2018, pp. 1033–42, doi:10.1111/ejn.13901.
short: K. Sawada, R. Kawakami, R. Shigemoto, T. Nemoto, European Journal of Neuroscience
47 (2018) 1033–1042.
date_created: 2018-12-11T11:45:50Z
date_published: 2018-03-07T00:00:00Z
date_updated: 2023-09-19T09:58:40Z
day: '07'
ddc:
- '570'
department:
- _id: RySh
doi: 10.1111/ejn.13901
external_id:
isi:
- '000431496400001'
file:
- access_level: open_access
checksum: 98e901d8229e44aa8f3b51d248dedd09
content_type: application/pdf
creator: dernst
date_created: 2018-12-17T16:16:50Z
date_updated: 2020-07-14T12:46:06Z
file_id: '5721'
file_name: 2018_EJN_Sawada.pdf
file_size: 4850261
relation: main_file
file_date_updated: 2020-07-14T12:46:06Z
has_accepted_license: '1'
intvolume: ' 47'
isi: 1
issue: '9'
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
page: 1033 - 1042
publication: European Journal of Neuroscience
publication_status: published
publisher: Wiley
publist_id: '7539'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Super resolution structural analysis of dendritic spines using three-dimensional
structured illumination microscopy in cleared mouse brain slices
tmp:
image: /images/cc_by_nc.png
legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode
name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
short: CC BY-NC (4.0)
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 47
year: '2018'
...
---
_id: '1094'
abstract:
- lang: eng
text: Immunogold labeling of freeze-fracture replicas has recently been used for
high-resolution visualization of protein localization in electron microscopy.
This method has higher labeling efficiency than conventional immunogold methods
for membrane molecules allowing precise quantitative measurements. However, one
of the limitations of freeze-fracture replica immunolabeling is difficulty in
keeping structural orientation and identifying labeled profiles in complex tissues
like brain. The difficulty is partly due to fragmentation of freeze-fracture replica
preparations during labeling procedures and limited morphological clues on the
replica surface. To overcome these issues, we introduce here a grid-glued replica
method combined with SEM observation. This method allows histological staining
before dissolving the tissue and easy handling of replicas during immunogold labeling,
and keeps the whole replica surface intact without fragmentation. The procedure
described here is also useful for matched double-replica analysis allowing further
identification of labeled profiles in corresponding P-face and E-face.
acknowledged_ssus:
- _id: EM-Fac
acknowledgement: 'We thank Prof. Elek Molnár for providing us a pan-AMPAR anti-body
used in Fig.2 and Dr. Ludek Lovicar for technical assistance in scanning electron
microscope imaging. This work was supported by the European Union (HBP—Project Ref.
604102). '
alternative_title:
- Methods in Molecular Biology
article_processing_charge: No
author:
- first_name: Harumi
full_name: Harada, Harumi
id: 2E55CDF2-F248-11E8-B48F-1D18A9856A87
last_name: Harada
orcid: 0000-0001-7429-7896
- first_name: Ryuichi
full_name: Shigemoto, Ryuichi
id: 499F3ABC-F248-11E8-B48F-1D18A9856A87
last_name: Shigemoto
orcid: 0000-0001-8761-9444
citation:
ama: 'Harada H, Shigemoto R. Immunogold protein localization on grid-glued freeze-fracture
replicas. In: High-Resolution Imaging of Cellular Proteins. Vol 1474. Springer;
2016:203-216. doi:10.1007/978-1-4939-6352-2_12'
apa: Harada, H., & Shigemoto, R. (2016). Immunogold protein localization on
grid-glued freeze-fracture replicas. In High-Resolution Imaging of Cellular
Proteins (Vol. 1474, pp. 203–216). Springer. https://doi.org/10.1007/978-1-4939-6352-2_12
chicago: Harada, Harumi, and Ryuichi Shigemoto. “Immunogold Protein Localization
on Grid-Glued Freeze-Fracture Replicas.” In High-Resolution Imaging of Cellular
Proteins, 1474:203–16. Springer, 2016. https://doi.org/10.1007/978-1-4939-6352-2_12.
ieee: H. Harada and R. Shigemoto, “Immunogold protein localization on grid-glued
freeze-fracture replicas,” in High-Resolution Imaging of Cellular Proteins,
vol. 1474, Springer, 2016, pp. 203–216.
ista: 'Harada H, Shigemoto R. 2016.Immunogold protein localization on grid-glued
freeze-fracture replicas. In: High-Resolution Imaging of Cellular Proteins. Methods
in Molecular Biology, vol. 1474, 203–216.'
mla: Harada, Harumi, and Ryuichi Shigemoto. “Immunogold Protein Localization on
Grid-Glued Freeze-Fracture Replicas.” High-Resolution Imaging of Cellular Proteins,
vol. 1474, Springer, 2016, pp. 203–16, doi:10.1007/978-1-4939-6352-2_12.
short: H. Harada, R. Shigemoto, in:, High-Resolution Imaging of Cellular Proteins,
Springer, 2016, pp. 203–216.
date_created: 2018-12-11T11:50:06Z
date_published: 2016-08-12T00:00:00Z
date_updated: 2025-04-15T07:12:21Z
day: '12'
department:
- _id: RySh
doi: 10.1007/978-1-4939-6352-2_12
ec_funded: 1
intvolume: ' 1474'
language:
- iso: eng
month: '08'
oa_version: None
page: 203 - 216
project:
- _id: 25CD3DD2-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '604102'
name: Localization of ion channels and receptors by two and three-dimensional immunoelectron
microscopic approaches
publication: High-Resolution Imaging of Cellular Proteins
publication_identifier:
eissn:
- 1611-3349
issn:
- 0302-9743
publication_status: published
publisher: Springer
publist_id: '6281'
quality_controlled: '1'
status: public
title: Immunogold protein localization on grid-glued freeze-fracture replicas
type: book_chapter
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 1474
year: '2016'
...
---
_id: '1993'
abstract:
- lang: eng
text: 'The fitness effects of symbionts on their hosts can be context-dependent,
with usually benign symbionts causing detrimental effects when their hosts are
stressed, or typically parasitic symbionts providing protection towards their
hosts (e.g. against pathogen infection). Here, we studied the novel association
between the invasive garden ant Lasius neglectus and its fungal ectosymbiont Laboulbenia
formicarum for potential costs and benefits. We tested ants with different Laboulbenia
levels for their survival and immunity under resource limitation and exposure
to the obligate killing entomopathogen Metarhizium brunneum. While survival of
L. neglectus workers under starvation was significantly decreased with increasing
Laboulbenia levels, host survival under Metarhizium exposure increased with higher
levels of the ectosymbiont, suggesting a symbiont-mediated anti-pathogen protection,
which seems to be driven mechanistically by both improved sanitary behaviours
and an upregulated immune system. Ants with high Laboulbenia levels showed significantly
longer self-grooming and elevated expression of immune genes relevant for wound
repair and antifungal responses (β-1,3-glucan binding protein, Prophenoloxidase),
compared with ants carrying low Laboulbenia levels. This suggests that the ectosymbiont
Laboulbenia formicarum weakens its ant host by either direct resource exploitation
or the costs of an upregulated behavioural and immunological response, which,
however, provides a prophylactic protection upon later exposure to pathogens. '
acknowledged_ssus:
- _id: EM-Fac
acknowledgement: "Funding was obtained by the German Research Foundation (CR 118–2)
and an ERC StG (243071) by the European Research Council (both to S.C.).\r\nWe thank
Line V. Ugelvig for help with ant collection and statistical discussion, Xavier
Espadaler for detailed information on the ant collection site, Birgit Lautenschläger
for the electron microscopy images and Eva Sixt for ant drawings. We further thank
Jørgen Eilenberg for the fungal strain, Meghan L. Vyleta for genetic strain characterization
and immune gene primer development, Paul Schmid-Hempel for discussion, and Line
V. Ugelvig, Xavier Espadaler and Christopher D. Pull for comments on the manuscript.
S.C., M.K. and S.T. conceived the study; M.K. and A.V.G. performed the experiments;
M.K. performed the statistical analysis; S.C. and M.K. wrote the manuscript with
intense contributions of A.V.G. and S.T.; all authors approved the manuscript."
article_number: '20141976'
article_processing_charge: No
article_type: original
author:
- first_name: Matthias
full_name: Konrad, Matthias
id: 46528076-F248-11E8-B48F-1D18A9856A87
last_name: Konrad
- first_name: Anna V
full_name: Grasse, Anna V
id: 406F989C-F248-11E8-B48F-1D18A9856A87
last_name: Grasse
- first_name: Simon
full_name: Tragust, Simon
id: 35A7A418-F248-11E8-B48F-1D18A9856A87
last_name: Tragust
- first_name: Sylvia
full_name: Cremer, Sylvia
id: 2F64EC8C-F248-11E8-B48F-1D18A9856A87
last_name: Cremer
orcid: 0000-0002-2193-3868
citation:
ama: Konrad M, Grasse AV, Tragust S, Cremer S. Anti-pathogen protection versus survival
costs mediated by an ectosymbiont in an ant host. Proceedings of the Royal
Society of London Series B Biological Sciences. 2015;282(1799). doi:10.1098/rspb.2014.1976
apa: Konrad, M., Grasse, A. V., Tragust, S., & Cremer, S. (2015). Anti-pathogen
protection versus survival costs mediated by an ectosymbiont in an ant host. Proceedings
of the Royal Society of London Series B Biological Sciences. The Royal Society.
https://doi.org/10.1098/rspb.2014.1976
chicago: Konrad, Matthias, Anna V Grasse, Simon Tragust, and Sylvia Cremer. “Anti-Pathogen
Protection versus Survival Costs Mediated by an Ectosymbiont in an Ant Host.”
Proceedings of the Royal Society of London Series B Biological Sciences.
The Royal Society, 2015. https://doi.org/10.1098/rspb.2014.1976.
ieee: M. Konrad, A. V. Grasse, S. Tragust, and S. Cremer, “Anti-pathogen protection
versus survival costs mediated by an ectosymbiont in an ant host,” Proceedings
of the Royal Society of London Series B Biological Sciences, vol. 282, no.
1799. The Royal Society, 2015.
ista: Konrad M, Grasse AV, Tragust S, Cremer S. 2015. Anti-pathogen protection versus
survival costs mediated by an ectosymbiont in an ant host. Proceedings of the
Royal Society of London Series B Biological Sciences. 282(1799), 20141976.
mla: Konrad, Matthias, et al. “Anti-Pathogen Protection versus Survival Costs Mediated
by an Ectosymbiont in an Ant Host.” Proceedings of the Royal Society of London
Series B Biological Sciences, vol. 282, no. 1799, 20141976, The Royal Society,
2015, doi:10.1098/rspb.2014.1976.
short: M. Konrad, A.V. Grasse, S. Tragust, S. Cremer, Proceedings of the Royal Society
of London Series B Biological Sciences 282 (2015).
corr_author: '1'
date_created: 2018-12-11T11:55:06Z
date_published: 2015-01-22T00:00:00Z
date_updated: 2025-09-23T07:55:03Z
day: '22'
department:
- _id: SyCr
doi: 10.1098/rspb.2014.1976
ec_funded: 1
external_id:
isi:
- '000345624600008'
pmid:
- '25473011'
intvolume: ' 282'
isi: 1
issue: '1799'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4286035/
month: '01'
oa: 1
oa_version: Submitted Version
pmid: 1
project:
- _id: 25DC711C-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '243071'
name: 'Social Vaccination in Ant Colonies: from Individual Mechanisms to Society
Effects'
- _id: 25DAF0B2-B435-11E9-9278-68D0E5697425
grant_number: CR-118/3-1
name: Host-Parasite Coevolution
publication: Proceedings of the Royal Society of London Series B Biological Sciences
publication_identifier:
eissn:
- 1471-2954
issn:
- 0962-8452
publication_status: published
publisher: The Royal Society
publist_id: '5090'
quality_controlled: '1'
related_material:
record:
- id: '9740'
relation: research_data
status: public
scopus_import: '1'
status: public
title: Anti-pathogen protection versus survival costs mediated by an ectosymbiont
in an ant host
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 282
year: '2015'
...