title: Strategies for Assaying Lysosomal Membrane Permeabilization.
abstract: Late endosomal organelles have an acidic pH and contain hydrolytic enzymes to degrade cargo delivered either from the extracellular environment by endocytosis or from within the cell itself by autophagy. In the event of lysosomal membrane permeabilization (LMP), the contents of late endosomes and lysosomes can be released into the cytosol and then initiate apoptosis. Compounds that can trigger LMP are therefore candidates for the induction of apoptosis, in particular in anticancer therapy. Alternatively, drug-delivery systems, such as nanoparticles, can have side effects that can include LMP, which has toxic consequences for the cells. To determine when, to what extent, and with what consequences LMP occurs is therefore of paramount importance for the evaluation of new potentially LMP-inducing compounds. In this introduction, we provide an overview of some basic assays for assessing LMP, such as staining with lysosomotropic dyes and measurement of cysteine cathepsin activity, and discuss additional strategies for the detection of the release of endogenous lysosomal molecules or preloaded exogenous tracers into the cytosol.
authors.affiliation: Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia Department of Biosciences, University of Oslo, NO-0371 Oslo, Norway.
authors.forename: Urška
authors.initials: U
authors.lastname: Repnik
authors.affiliation: Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia.
authors.forename: Maruša
authors.initials: M
authors.lastname: Hafner Česen
authors.affiliation: Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia Center of Excellence CIPKEBIP, SI-1000 Ljubljana, Slovenia.
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
mesh_terms: D003584:Cytological Techniques / Q000379:methods*; D007425:Intracellular Membranes / Q000187:drug effects* / Q000502:physiology*; D008247:Lysosomes / Q000187:drug effects* / Q000378:metabolism*; D010539:Permeability