Tina Romer

ChromoTek GmbH, Planeck, Bavaria, Germany

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Publications (6)44.56 Total impact

  • Cancer Research 08/2015; 75(15 Supplement):1231-1231. DOI:10.1158/1538-7445.AM2015-1231 · 9.33 Impact Factor

  • Cancer Research 08/2015; 75(15 Supplement):86-86. DOI:10.1158/1538-7445.AM2015-86 · 9.33 Impact Factor
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    ABSTRACT: Abstract β-catenin is the key component of the canonical Wnt pathway and plays a crucial role in a multitude of developmental and homeostatic processes. The different tasks of β-catenin are orchestrated by its subcellular localization and participation in multiprotein complexes. To gain a better understanding of β-catenin's role in living cells we have generated a new set of single domain antibodies, referred to as nanobodies, derived from heavy chain antibodies of camelids. We selected nanobodies recognizing the N-terminal, core or C-terminal domain of β-catenin and applied these new high-affinity binders as capture molecules in sandwich immunoassays and co-immunoprecipitations of endogenous β-catenin complexes. In addition, we engineered intracellularly functional anti-β-catenin chromobodies by combining the binding moieties of the nanobodies with fluorescent proteins. For the first time, we were able to visualize the subcellular localization and nuclear translocation of endogenous β-catenin in living cells using these chromobodies. Moreover, the chromobody signal allowed us to trace the accumulation of diffusible, hypo-phosphorylated β-catenin in response to compound treatment in real time using High Content Imaging. The anti-β-catenin nanobodies and chromobodies characterized in this study are versatile tools that enable a novel and unique approach to monitor the dynamics of subcellular β-catenin in biochemical and cell biological assays. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Molecular &amp Cellular Proteomics 01/2015; DOI:10.1074/mcp.M114.044016 · 6.56 Impact Factor
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    ABSTRACT: Numerous applications of conventional and biogenic magnetic nanoparticles (MNPs), such as in diagnostics, immunomagnetic separations, and magnetic cell labeling, require the immobilization of antibodies. This is usually accomplished by chemical conjugation, which, however, has several disadvantages, such as poor efficiency and the need for coupling chemistry. Here, we describe a novel strategy to display a functional camelid antibody fragment (nanobody) from an alpaca (Lama pacos) on the surface of bacterial biogenic magnetic nanoparticles (magnetosomes). Magnetosome-specific expression of a red fluorescent protein (RFP)-binding nanobody (RBP) in vivo was accomplished by genetic fusion of RBP to the magnetosome protein MamC in the magnetite-synthesizing bacterium Magnetospirillum gryphiswaldense. We demonstrate that isolated magnetosomes expressing MamC-RBP efficiently recognize and bind their antigen in vitro and can be used for immunoprecipitation of RFP-tagged proteins and their interaction partners from cell extracts. In addition, we show that coexpression of monomeric RFP (mRFP or its variant mCherry) and MamC-RBP results in intracellular recognition and magnetosome recruitment of RFP within living bacteria. The intracellular expression of a functional nanobody targeted to a specific bacterial compartment opens new possibilities for in vivo synthesis of MNP-immobilized nanobodies. Moreover, intracellular nanotraps can be generated to manipulate bacterial structures in live cells.
    Applied and Environmental Microbiology 09/2011; 77(17):6165-71. DOI:10.1128/AEM.05282-11 · 3.67 Impact Factor
  • Tina Romer · Heinrich Leonhardt · Ulrich Rothbauer ·
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    ABSTRACT: The rapid and ongoing discovery of new disease related biomarkers leads to a dramatic paradigm change in human healthcare and constitutes the basis for a truly personalized medicine. Molecular imaging enables early detection and classification of human diseases and provides valuable data for optimized, target-oriented therapies. By now, the biochemical and physiological properties of antibody derivatives or alternative protein scaffolds can be engineered for the detection of a wide range of target structures. The successful application of these reagents in animals, xenograft models and cells in preclinical research clearly demonstrate their utility for molecular imaging. Despite these promising perspectives, only a few antibodies and recombinant proteins are used yet for molecular imaging in human medicine. Especially the high safety demands and the need to eliminate off target effects in humans require extensive research and development efforts.
    Current Opinion in Biotechnology 06/2011; 22(6):882-7. DOI:10.1016/j.copbio.2011.06.007 · 7.12 Impact Factor
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    ABSTRACT: Molecular conjugates comprising targeting ligands hold great promise for site-specific gene delivery to distant tumors and individual organs including the lung. Here we show that prostaglandin I2 analogues can be used to improve gene transfer efficiency of polyethylenimine (PEI) gene vectors on bronchial and alveolar epithelial cells in vitro and lungs of mice in vivo. Prostacyclin (IP1) receptor expression was confirmed in pulmonary epithelial cell lines by western blot. Iloprost (ILO) and treprostinil (TRP), two prostaglandin I2 analogues, were conjugated to fluorescein-labeled BSA (FLUO-BSA) and compared for IP1 receptor binding/uptake in different lung cell lines. Binding of FLUO-BSA-ILO was 2-4-fold higher than for FLUO-BSA-TRP and could be specifically inhibited by free ILO and IP1 receptor antagonist CAY10449. Internalization of FLUO-BSA-ILO was confirmed by confocal microscopy. Molecular conjugates of PEI and ILO (PEI-g-ILO) were synthesized with increasing coupling degree (F(ILO) (ILO:PEI) = 2, 5, 8, 16) and analyzed for DNA binding, particle formation and transfection efficiency. At optimized conditions (N/P 4, F(ILO) = 5), gene expression using PEI-g-ILO was significantly up to 46-fold higher than for PEI gene vectors and specifically inhibited by CAY10449. Gene expression in the lungs of mice after aerosol delivery was 14-fold higher with PEI-g-ILO F(ILO) = 5 than for PEI. We suggest that targeting of IP1 receptor using ILO represents a promising approach to improve pulmonary gene transfer.
    Biomaterials 04/2010; 31(10):2903-11. DOI:10.1016/j.biomaterials.2009.12.035 · 8.56 Impact Factor