Abstract

Mitophagy is a cellular process that selectively removes damaged, old or dysfunctional mitochondria. Defective mitophagy is thought to contribute to normal aging and to various neurodegenerative and cardiovascular diseases. Previous methods used to detect mitophagy in vivo were cumbersome, insensitive and difficult to quantify. We created a transgenic mouse model that expresses the pH-dependent fluorescent protein mt-Keima in order to more readily assess mitophagy. Keima is a pH-sensitive, dual-excitation ratiometric fluorescent protein that also exhibits resistance to lysosomal proteases. At the physiological pH of the mitochondria (pH 8.0), the shorter-wavelength excitation predominates. Within the acidic lysosome (pH 4.5) after mitophagy, mt-Keima undergoes a gradual shift to longer-wavelength excitation. In this protocol, we describe how to monitor mitophagic flux in living cells over an 18-h time frame, as well as how to quantify mitophagy using the mt-Keima probe. This protocol also describes how to use confocal microscopy to visualize mitophagy in living tissues obtained from mt-Keima transgenic mice. With this protocol, the mt-Keima probe can reliably be imaged within the first 60 min after tissue collection. We also describe how to apply mt-Keima with stimulated emission depletion (STED) microscopy, which can potentially provide substantially higher-resolution images. Typically, the approximate time frame for time-lapse fluorescence imaging of mt-Keima is 20 h for living cells. For confocal analysis of tissue from an mt-Keima mouse, the whole procedure generally takes no longer than 60 min, and the STED imaging usually takes <2 h.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.