Assessing Chondrocyte Status by Immunofluorescence-Mediated Localization of Parkin Relative to Mitochondria

Immunofluorescence staining is a widely used and powerful tool for the visualization and colocalization of two or more proteins and/or cellular organelles. For colocalization studies in fixed cells, one target protein/organelle is immunostained and visualized by one fluorophore and the other target protein/organelle is immunostained and visualized by a different fluorophore whose excitation emission spectra does not overlap with the first fluorophore. Parkin (PARK2) is an E3 ubiquitin ligase which performs ubiquitination of surface proteins of dysfunctional mitochondria to mark them for autolysosomal degradation. Here we describe the immunofluorescence staining of parkin protein and immunofluorescence or dye-based methods to visualize mitochondria and study the colocalization of parkin and mitochondria in primary human or mouse chondrocytes or cell lines.