title: Experimenters' guide to colocalization studies: finding a way through indicators and quantifiers, in practice.
abstract: Multicolor fluorescence microscopy helps to define the local interplay of subcellular components in cell biological experiments. The analysis of spatial coincidence of two or more markers is a first step in investigating the potential interactions of molecular actors. Colocalization studies rely on image preprocessing and further analysis; however, they are limited by optical resolution. Once those limitations are taken into account, characterization might be performed. In this review, we discuss two types of parameters that are aimed at evaluating colocalization, which are indicators and quantifiers. Indicators evaluate signal coincidence over a predefined scale, while quantifiers provide an absolute measurement. As the image is both a collection of intensities and a collection of objects, both approaches are applicable. Most of the available image processing software include various colocalization options; however, guidance for the choice of the appropriate method is rarely proposed. In this review, we provide the reader with a basic description of the available colocalization approaches, proposing a guideline for their use, either alone or in combination.
authors: Bordeaux Imaging Center, UMS 3420 CNRS-Université Bordeaux Segalen-US4 INSERM, Pôle d'imagerie photonique, Institut François Magendie, Bordeaux Cedex, France.
authors: Fabrice P
authors: FP
authors: Cordelières
authors: Sorbonne Universités-UPMC Univ Paris 06, Institut de Biologie Paris-Seine-CNRS FR 3631, Cellular Imaging Facility, Paris Cedex, France.
authors: Susanne
authors: S
authors: Bolte
mesh_terms: D007091:Image Processing, Computer-Assisted; D008856:Microscopy, Fluorescence; D021381:Protein Transport; D012107:Research Design; D059010:Single-Cell Analysis / Q000379:methods*
keywords: Cell biology; Coincidence; Colocalization indicators; Colocalization quantifiers; Fluorescence microscopy