@phdthesis{Collenburg2018,
  author    = {Collenburg, Lena},
  title     = {The Role of Ceramides and Sphingomyelinases for Dynamic Membrane Processes in T Cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151161},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Previous work of our group has established a role of sphingomyelinases in the regulation of T cell responses to TCR or pathogen stimulation, and this became particularly evident at the level of actin cytoskeletal dynamics. The formation of lipid membrane microdomains is crucial for receptor clustering and signal induction, and therefore, ceramide accumulation by membrane sphingomyelin breakdown is needed for signalling- complex-assembly. Pathogen-induced overshooting of SMase activation substantially impacted the formation of membrane protrusions, with T cell spreading as well as a front/rear polarisation upon CD3/CD28 co-stimulation [103]. On the other hand, NSM activation is part of the physiological TCR signal [67], indicating that a spatiotemporally balanced NSM activation is crucial for its physiological function. It involves actin cytoskeletal reorganisation and T cell polarisation. These two functions are also of central importance in directional T cell migration and motility in tissues. This thesis aims on defining the role of NSM in compartmentalisation of the T cell membrane in polarisation and migration. Therefore, functional studies on the impact of NSM activity in these processes had to be complemented by the development of tools to study ceramide compartmentalisation in living T cells.},
  subject      = {Ceramides},
  language  = {en}
}
@article{CollenburgBeyersdorfWieseetal.2017,
  author    = {Collenburg, Lena and Beyersdorf, Niklas and Wiese, Teresa and Arenz, Christoph and Saied, Essa M. and Becker-Flegler, Katrin Anne and Schneider-Schaulies, Sibylle and Avota, Elita},
  title     = {The activity of the neutral sphingomyelinase is important in T cell recruitment and directional migration},
  series = {Frontiers in Immunology},
  volume    = {8},
  journal   = {Frontiers in Immunology},
  number    = {1007},
  doi       = {10.3389/fimmu.2017.01007},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158944},
  year      = {2017},
  abstract  = {Breakdown of sphingomyelin as catalyzed by the activity of sphingomyelinases profoundly affects biophysical properties of cellular membranes which is particularly important with regard to compartmentalization of surface receptors and their signaling relay. As it is activated both upon TCR ligation and co-stimulation in a spatiotemporally controlled manner, the neutral sphingomyelinase (NSM) has proven to be important in T cell activation, where it appears to play a particularly important role in cytoskeletal reorganization and cell polarization. Because these are important parameters in directional T cell migration and motility in tissues, we analyzed the role of the NSM in these processes. Pharmacological inhibition of NSM interfered with early lymph node homing of T cells in vivo indicating that the enzyme impacts on endothelial adhesion, transendothelial migration, sensing of chemokine gradients or, at a cellular level, acquisition of a polarized phenotype. NSM inhibition reduced adhesion of T cells to TNF-α/IFN-γ activated, but not resting endothelial cells, most likely via inhibiting high-affinity LFA-1 clustering. NSM activity proved to be highly important in directional T cell motility in response to SDF1-α, indicating that their ability to sense and translate chemokine gradients might be NSM dependent. In fact, pharmacological or genetic NSM ablation interfered with T cell polarization both at an overall morphological level and redistribution of CXCR4 and pERM proteins on endothelial cells or fibronectin, as well as with F-actin polymerization in response to SDF1-α stimulation, indicating that efficient directional perception and signaling relay depend on NSM activity. Altogether, these data support a central role of the NSM in T cell recruitment and migration both under homeostatic and inflamed conditions by regulating polarized redistribution of receptors and their coupling to the cytoskeleton.},
  language  = {en}
}
@article{SchneiderSchauliesMuellerAvotaetal.2014,
  author    = {Schneider-Schaulies, Sibylle and Mueller, Nora and Avota, Elita and Collenburg, Lena and Grassm{\´e}, Heike},
  title     = {Neutral Sphingomyelinase in Physiological and Measles Virus Induced T Cell Suppression},
  doi       = {10.1371/journal.ppat.1004574},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111038},
  year      = {2014},
  abstract  = {T cell paralysis is a main feature of measles virus (MV) induced immunosuppression. MV contact mediated activation of sphingomyelinases was found to contribute to MV interference with T cell actin reorganization. The role of these enzymes in MV-induced inhibition of T cell activation remained equally undefined as their general role in regulating immune synapse (IS) activity which relies on spatiotemporal membrane patterning. Our study for the first time reveals that transient activation of the neutral sphingomyelinase 2 (NSM2) occurs in physiological co-stimulation of primary T cells where ceramide accumulation is confined to the lamellum (where also NSM2 can be detected) and excluded from IS areas of high actin turnover. Genetic ablation of the enzyme is associated with T cell hyper-responsiveness as revealed by actin dynamics, tyrosine phosphorylation, Ca2+-mobilization and expansion indicating that NSM2 acts to suppress overshooting T cell responses. In line with its suppressive activity, exaggerated, prolonged NSM2 activation as occurring in co-stimulated T cells following MV exposure was associated with aberrant compartmentalization of ceramides, loss of spreading responses, interference with accumulation of tyrosine phosphorylated protein species and expansion. Altogether, this study for the first time reveals a role of NSM2 in physiological T cell stimulation which is dampening and can be abused by a virus, which promotes enhanced and prolonged NSM2 activation to cause pathological T cell suppression.},
  language  = {en}
}