Cholesterol is not only a major component of the cell membrane, but also plays an important role in a wide range of biological processes and pathologies. It is therefore crucial to develop appropriate tools for visualizing intracellular cholesterol transport. Here, we describe new cationic analogues of BODIPY-Cholesterol (TopFluor-Cholesterol, TF-Chol), which combine a positive charge on the sterol side chain and a BODIPY group connected via a C-4 linker. In contrast to TF-Chol, the new analogues TF-1 and TF-3 possessing acetyl groups on the A ring (C-3 position on steroid) internalized much faster and displayed slightly different levels of intracellular localization. Their applicability for cholesterol monitoring was indicated by the fact that they strongly label compartments with accumulated cholesterol in cells carrying a mutation of the Niemann-Pick disease-associated cholesterol transporter, NPC1.

CZ OPENSCREEN Institute of Molecular Genetics of the Czech Academy of Sciences v v i Vídeňská 1083 142 20 Prague 4 Czech Republic

Czech University of Life Sciences Prague Kamýcká 129 165 00 Prague 6 Czech Republic

Light microscopy core facility Institute of Molecular Genetics of the Czech Academy of Sciences v v i Vídeňská 1083 142 20 Prague 4 Czech Republic

University of Chemistry and Technology Technická 5 166 28 Prague 6 Czech Republic

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Colchicine-BODIPY Probes: Evidence for the Involvement of Intracellular Membranes in the Targeting of Colchicine to Tubulin