Delivery of antibodies to the cytosol: debunking the myths.
The use of antibodies to target their antigens in living cells is a powerful analytical tool for cell biology research. Not only can molecules be localized and visualized in living cells, but interference with cellular processes by antibodies may allow functional analysis down to the level of individual post-translational modifications and splice variants, which is not possible with genetic or RNA-based methods. To utilize the vast resource of available antibodies, an efficient system to deliver them into the cytosol from the outside is needed. Numerous strategies have been proposed, but the most robust and widely applicable procedure still remains to be identified, since a quantitative ranking of the efficiencies has not yet been done. To achieve this, we developed a novel efficiency evaluation method for antibody delivery based on a fusion protein consisting of a human IgG 1 Fc and the recombination enzyme Cre (Fc-Cre). Applied to suitable GFP reporter cells, it allows the important distinction between proteins trapped in endosomes and those delivered to the cytosol. Further, it ensures viability of positive cells and is unsusceptible to fixation artifacts and misinterpretation of cellular localization in microscopy and flow cytometry. Very low cytoplasmic delivery efficiencies were found for various profection reagents and membrane penetrating peptides, leaving electroporation as the only practically useful delivery method for antibodies. This was further verified by the successful application of this method to bind antibodies to cytosolic components in living cells.
Technische Universität Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany.
Andrea L J
AL
Marschall
Georg-Speyer-Haus; Institute for Tumor Biology und experimental Therapy; Frankfurt, Germany.
Congcong
C
Zhang
Technische Universität Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany.
André
A
Frenzel
Yumab GmbH; Braunschweig, Germany.
Thomas
T
Schirrmann
Technische Universität Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany.
Michael
M
Hust
Institut Curie; Centre de Recherche; Paris, France; CNRS UMR144; Paris, France.
Franck
F
Perez
Technische Universität Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany.
Stefan
S
Dübel
D003600:Cytosol / Q000378:metabolism*; D016503:Drug Delivery Systems / Q000379:methods*; D011992:Endosomes / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics / Q000494:pharmacology; D007074:Immunoglobulin G / Q000235:genetics / Q000494:pharmacology; D019426:Integrases / Q000235:genetics / Q000493:pharmacokinetics / Q000494:pharmacology; D021381:Protein Transport; D011993:Recombinant Fusion Proteins
D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; C045073:Cre recombinase; D019426:Integrases
CPP; PTD; cell penetrating peptides; electroporation; electrotransfer; profection; protein delivery; protein transduction domain; transbody; transfection; yumab