@article{MuranyiMalkuschMuelleretal.2013,
  author    = {Muranyi, Walter and Malkusch, Sebastian and M{\"u}ller, Barbara and Heilemann, Mike and Kr{\"a}usslich, Hans-Georg},
  title     = {Super-Resolution Microscopy Reveals Specific Recruitment of HIV-1 Envelope Proteins to Viral Assembly Sites Dependent on the Envelope C-Terminal Tail},
  series = {PLoS Pathogens},
  volume    = {9},
  journal   = {PLoS Pathogens},
  number    = {2},
  doi       = {10.1371/journal.ppat.1003198},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131235},
  pages     = {e1003198},
  year      = {2013},
  abstract  = {The inner structural Gag proteins and the envelope (Env) glycoproteins of human immunodeficiency virus (HIV-1) traffic independently to the plasma membrane, where they assemble the nascent virion. HIV-1 carries a relatively low number of glycoproteins in its membrane, and the mechanism of Env recruitment and virus incorporation is incompletely understood. We employed dual-color super-resolution microscopy visualizing Gag assembly sites and HIV-1 Env proteins in virus-producing and in Env expressing cells. Distinctive HIV-1 Gag assembly sites were readily detected and were associated with Env clusters that always extended beyond the actual Gag assembly site and often showed enrichment at the periphery and surrounding the assembly site. Formation of these Env clusters depended on the presence of other HIV-1 proteins and on the long cytoplasmic tail (CT) of Env. CT deletion, a matrix mutation affecting Env incorporation or Env expression in the absence of other HIV-1 proteins led to much smaller Env clusters, which were not enriched at viral assembly sites. These results show that Env is recruited to HIV-1 assembly sites in a CT-dependent manner, while Env\((\Delta CT)\) appears to be randomly incorporated. The observed Env accumulation surrounding Gag assemblies, with a lower density on the actual bud, could facilitate viral spread in vivo. Keeping Env molecules on the nascent virus low may be important for escape from the humoral immune response, while cell-cell contacts mediated by surrounding Env molecules could promote HIV-1 transmission through the virological synapse.},
  language  = {en}
}
@article{SporbertCseresnyesHeidbrederetal.2013,
  author    = {Sporbert, Anje and Cseresnyes, Zoltan and Heidbreder, Meike and Domaing, Petra and Hauser, Stefan and Kaltschmidt, Barbara and Kaltschmidt, Christian and Heilemann, Mike and Widera, Darius},
  title     = {Simple Method for Sub-Diffraction Resolution Imaging of Cellular Structures on Standard Confocal Microscopes by Three-Photon Absorption of Quantum Dots},
  series = {PLoS ONE},
  volume    = {8},
  journal   = {PLoS ONE},
  number    = {5},
  doi       = {10.1371/journal.pone.0064023},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130963},
  pages     = {e64023},
  year      = {2013},
  abstract  = {This study describes a simple technique that improves a recently developed 3D sub-diffraction imaging method based on three-photon absorption of commercially available quantum dots. The method combines imaging of biological samples via tri-exciton generation in quantum dots with deconvolution and spectral multiplexing, resulting in a novel approach for multi-color imaging of even thick biological samples at a 1.4 to 1.9-fold better spatial resolution. This approach is realized on a conventional confocal microscope equipped with standard continuous-wave lasers. We demonstrate the potential of multi-color tri-exciton imaging of quantum dots combined with deconvolution on viral vesicles in lentivirally transduced cells as well as intermediate filaments in three-dimensional clusters of mouse-derived neural stem cells (neurospheres) and dense microtubuli arrays in myotubes formed by stacks of differentiated C2C12 myoblasts.},
  language  = {en}
}
@article{DietzHasseFerrarisetal.2013,
  author    = {Dietz, Mariana S. and Hasse, Daniel and Ferraris, Davide M. and G{\"o}hler, Antonia and Niemann, Hartmut H. and Heilemann, Mike},
  title     = {Single-molecule photobleaching reveals increased MET receptor dimerization upon ligand binding in intact cells},
  series = {BMC Biophysics},
  volume    = {6},
  journal   = {BMC Biophysics},
  number    = {6},
  issn      = {2046-1682},
  doi       = {10.1186/2046-1682-6-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121835},
  year      = {2013},
  abstract  = {Background: The human receptor tyrosine kinase MET and its ligand hepatocyte growth factor/scatter factor are essential during embryonic development and play an important role during cancer metastasis and tissue regeneration. In addition, it was found that MET is also relevant for infectious diseases and is the target of different bacteria, amongst them Listeria monocytogenes that induces bacterial uptake through the surface protein internalin B. Binding of ligand to the MET receptor is proposed to lead to receptor dimerization. However, it is also discussed whether preformed MET dimers exist on the cell membrane. Results: To address these issues we used single-molecule fluorescence microscopy techniques. Our photobleaching experiments show that MET exists in dimers on the membrane of cells in the absence of ligand and that the proportion of MET dimers increases significantly upon ligand binding. Conclusions: Our results indicate that partially preformed MET dimers may play a role in ligand binding or MET signaling. The addition of the bacterial ligand internalin B leads to an increase of MET dimers which is in agreement with the model of ligand-induced dimerization of receptor tyrosine kinases.},
  language  = {en}
}