Publications by authors named "Lisa Johann"

5 Publications

  • Page 1 of 1

Analyzing the α-Actinin Network in Human iPSC-Derived Cardiomyocytes Using Single Molecule Localization Microscopy.

J Vis Exp 2020 11 3(165). Epub 2020 Nov 3.

Department of Cardiac Surgery, Reference and Translation Center for Cardiac Stem Cell Therapy (RTC), Rostock University Medical Center; Faculty of Interdisciplinary Research, Department Life, Light & Matter, University Rostock.

The maturation of iPSC-derived cardiomyocytes is a critical issue for their application in regenerative therapy, drug testing and disease modeling. Despite the development of multiple differentiation protocols, the generation of iPSC cardiomyocytes resembling an adult-like phenotype remains challenging. One major aspect of cardiomyocytes maturation involves the formation of a well-organized sarcomere network to ensure high contraction capacity. Here, we present a super resolution-based approach for semi-quantitative analysis of the α-actinin network in cardiomyocytes. Using photoactivated localization microscopy a comparison of sarcomere length and z-disc thickness of iPSC-derived cardiomyocytes and cardiac cells isolated from neonatal tissue was performed. At the same time, we demonstrate the importance of proper imaging conditions to obtain reliable data. Our results show that this method is suitable to quantitatively monitor the structural maturity of cardiac cells with high spatial resolution, enabling the detection of even subtle changes of sarcomere organization.
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http://dx.doi.org/10.3791/61605DOI Listing
November 2020

Interleukin-1 promotes autoimmune neuroinflammation by suppressing endothelial heme oxygenase-1 at the blood-brain barrier.

Acta Neuropathol 2020 10 11;140(4):549-567. Epub 2020 Jul 11.

Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.

The proinflammatory cytokine interleukin 1 (IL-1) is crucially involved in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Herein, we studied the role of IL-1 signaling in blood-brain barrier (BBB) endothelial cells (ECs), astrocytes and microglia for EAE development, using mice with the conditional deletion of its signaling receptor IL-1R1. We found that IL-1 signaling in microglia and astrocytes is redundant for the development of EAE, whereas the IL-1R1 deletion in BBB-ECs markedly ameliorated disease severity. IL-1 signaling in BBB-ECs upregulated the expression of the adhesion molecules Vcam-1, Icam-1 and the chemokine receptor Darc, all of which have been previously shown to promote CNS-specific inflammation. In contrast, IL-1R1 signaling suppressed the expression of the stress-responsive heme catabolizing enzyme heme oxygenase-1 (HO-1) in BBB-ECs, promoting disease progression via a mechanism associated with deregulated expression of the IL-1-responsive genes Vcam1, Icam1 and Ackr1 (Darc). Mechanistically, our data emphasize a functional crosstalk of BBB-EC IL-1 signaling and HO-1, controlling the transcription of downstream proinflammatory genes promoting the pathogenesis of autoimmune neuroinflammation.
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http://dx.doi.org/10.1007/s00401-020-02187-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498485PMC
October 2020

Quantitative Evaluation of the Sarcomere Network of Human hiPSC-Derived Cardiomyocytes Using Single-Molecule Localization Microscopy.

Int J Mol Sci 2020 Apr 17;21(8). Epub 2020 Apr 17.

Department of Cardiac Surgery, Reference and Translation Center for Cardiac Stem Cell Therapy (RTC), Rostock University Medical Center, 18057 Rostock, Germany.

The maturation of iPSC-derived cardiomyocytes is still a critical point for their application in cardiovascular research as well as for their clinical use. Although multiple differentiation protocols have been established, researchers failed to generate fully mature cardiomyocytes in vitro possessing identical phenotype-related and functional properties as their native adult counterparts. Besides electrophysiological and metabolic changes, the establishment of a well structured sarcomere network is important for the development of a mature cardiac phenotype. Here, we present a super resolution-based approach to quantitatively evaluate the structural maturation of iPSC-derived cardiomyocytes. Fluorescence labelling of the α-actinin cytoskeleton and subsequent visualization by photoactivated localization microscopy allows the acquisition of highly resolved images for measuring sarcomere length and z-disc thickness. Our image analysis revealed that iPSC and neonatal cardiomyocyte share high similarity with respect to their sarcomere organization, however, contraction capacity was inferior in iPSC-derived cardiac cells, indicating an early maturation level. Moreover, we demonstrate that this imaging approach can be used as a tool to monitor cardiomyocyte integrity, helping to optimize iPSC differentiation as well as somatic cell direct-reprogramming strategies.
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http://dx.doi.org/10.3390/ijms21082819DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216082PMC
April 2020

Antigen-presenting cell diversity for T cell reactivation in central nervous system autoimmunity.

J Mol Med (Berl) 2018 12 1;96(12):1279-1292. Epub 2018 Nov 1.

University Medical Center of the Johannes Gutenberg-Universität Mainz, Mainz, Germany.

Autoreactive T cells are considered the major culprits in the pathogenesis of many autoimmune diseases like multiple sclerosis (MS). Upon activation in the lymphoid organs, autoreactive T cells migrate towards the central nervous system (CNS) and target the myelin sheath-forming oligodendrocytes, resulting in detrimental neurological symptoms. Despite the availability of extensively studied systems like the experimental autoimmune encephalomyelitis (EAE) model, our understanding of this disease and the underlying pathogenesis is still elusive. One vividly discussed subject represents the T cell reactivation in the CNS. In order to exert their effector functions in the CNS, autoreactive T cells must encounter antigen-presenting cells (APCs). This interaction provides an antigen-restricted stimulus in the context of major histocompatibility complex class II (MHC-II) and other co-stimulatory molecules. Peripherally derived dendritic cells (DCs), B cells, border-associated macrophages (BAM), CNS-resident microglia, and astrocytes have the capacity to express molecules required for antigen presentation under inflammatory conditions. Also, endothelial cells can fulfill these prerequisites in certain situations. Which of these cells in fact act as APCs for T cell reactivation and to which extent they can exert this function has been studied intensively, but unfortunately with no firm conclusion. In this review, we will summarize the findings that support or question the antigen presenting capacities of the mentioned cell types of CNS-localized T cell reactivation.
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http://dx.doi.org/10.1007/s00109-018-1709-7DOI Listing
December 2018

The surge of earthquakes in Central Oklahoma has features of reservoir-induced seismicity.

Sci Rep 2018 07 31;8(1):11505. Epub 2018 Jul 31.

Freie Universitaet Berlin, Institute of Geophysics, Berlin, 12249, Germany.

The recent surge of seismicity in Oklahoma and Kansas is related to fluid disposal. Evidences suggest that critical parameters are the injection volume as well as injection depth but dominant physical processes and a corresponding model to describe the physics are still not clear. We analyse the spatio-temporal distribution of induced earthquakes in the basement and find visible signatures of pore pressure diffusion and poroelastic coupling, features which strongly resemble seismicity induced by the filling of artificial lakes, so-called reservoir-induced seismicity. We developed a first-principle model of underground reservoir-induced seismicity. The physics of the model are based upon the combined mechanisms of fluid mass added to the pore-space of the injection layer and acting as a normal stress on the basement surface, pore-fluid pressure diffusion in the basement as well as poroelastic coupling contributing to the pore-fluid pressure and stress. Furthermore, we demonstrate that underground reservoir-induced seismicity occurs preferably in normal faulting and strike-slip settings, the latter being prevalent in Oklahoma. Our model explains observed injection volume and depth dependence of the seismicity and should be considered as a basis for future hazard prediction and prevention as well as for planning possible disposal sites.
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http://dx.doi.org/10.1038/s41598-018-29883-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068131PMC
July 2018