@article{GiebingToelleJuergensenetal.2005,
  author    = {Giebing, G{\"u}nter and T{\"o}lle, Markus and J{\"u}rgensen, Jana and Eichhorst, Jenny and Furkert, Jens and Beyermann, Michael and Neusch{\"a}fer-Rube, Frank and Rosenthal, Walter and Zidek, Walter and van der Giet, Markus and Oksche, Alexander},
  title     = {Arrestin-independent internalization and recycling of the urotensin receptor contribute to long-lasting urotensin II - Mediated vasoconstriction},
  issn      = {0009-7330},
  year      = {2005},
  abstract  = {Urotensin II (UII), which acts on the G protein-coupled urotensin ( UT) receptor, elicits long-lasting vasoconstriction. The role of UT receptor internalization and intracellular trafficking in vasoconstriction has yet not been analyzed. Therefore, UII-mediated contractile responses of aortic ring preparations in wire myography and rat UT (rUT) receptor internalization and intracellular trafficking in binding and imaging analyses were compared. UII elicited a concentration-dependent vasoconstriction of rat aorta (-log EC50, mol/L:9.0 +/- 0.1). A second application of UII after 30 minutes elicited a reduced contraction (36 +/- 4\% of the initial response), but when applied after 60 minutes elicited a full contraction. In internalization experiments with radioactive labeled VII (I-125-UII), approximate to 70\% of rUT receptors expressed on the cell surface of human embryonic kidney 293 cells were sequestered within 30 minutes (half life [t(h)]: 5.6 +/- 0.2 minutes), but recycled quantitatively within 60 minutes (t(h) 31.9 +/- 2.6 minutes). UII- bound rUT receptors were sorted to early and recycling endosomes, as evidenced by colocalization of rUT receptors with the early endosomal antigen and the transferrin receptor. Real-time imaging with a newly developed fluorescent UII (Cy3- UII) revealed that rUT receptors recruited arrestin3 green fluorescent protein to the plasma membrane. Arrestin3 was not required for the endocytosis of the rUT receptor, however, as internalization of Cy3-UII was not altered in mouse embryonic fibroblasts lacking endogenous arrestin2/arrestin3 expression. The data demonstrate that the rUT receptor internalizes arrestin independently and recycles quantitatively. The continuous externalization of rUT receptors provides the basis for repetitive and lasting UII-mediated vasoconstriction},
  language  = {en}
}
@article{DraffehnEichhorstWiesneretal.2016,
  author    = {Draffehn, Soeren and Eichhorst, Jenny and Wiesner, Burkhard and Kumke, Michael Uwe},
  title     = {Insight into the Modification of Polymeric Micellar and Liposomal Nanocarriers by Fluorescein-Labeled Lipids and Uptake-Mediating Lipopeptides},
  series = {Langmuir},
  volume    = {32},
  journal   = {Langmuir},
  publisher = {American Chemical Society},
  address   = {Heidelberg},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.6b01487},
  pages     = {6928 -- 6939},
  year      = {2016},
  abstract  = {Encapsulation of diagnostic and therapeutic compounds in transporters improves their delivery to the point of need. An even more efficient treatment of diseases can be achieved using carriers with targeting or protecting moieties. In the present work, we investigated micellar and liposomal nanocarriers modified with fluorescein, peptides, and polymers that are covalently bound to fatty acids or phospholipids to ensure a self-driven incorporation into the micelles or liposomes. First, we characterized the photophysics of the fluorescent probes in the absence and in the presence of nanocarriers. Changes in the fluorescence decay time, quantum yield, and intensity of a fluorescein-labeled fatty acid (fluorescein-labeled palmitic acid [fPA]) and a fluorescein-labeled lipopeptide (P2fA2) were found. By exploiting these changes, we investigated a lipopeptide (P2A2 as an uptake-mediating unit) in combination with different nanocarriers (micelles and liposomes) and determined the corresponding association constant K-ass values, which were found to be very high. In addition, the mobility of fPA was exploited using fluorescence correlation spectroscopy (FCS) and fluorescence depolarization (FD) experiments to characterize the nanocarriers. Cellular uptake experiments with mouse brain endothelial cells provided information on the uptake behavior of liposomes modified by uptake-mediating P2A2 and revealed differences in the uptake behavior between pH-sensitive and pH-insensitive liposomes.},
  language  = {en}
}