Research Techniques Made Simple: Analysis of Autophagy in the Skin.

Autophagy is required for normal skin homeostasis and its disordered regulation is implicated in a range of cutaneous diseases. Several well-characterized biomarkers of autophagy are used experimentally to quantify autophagic activity or clinically to correlate autophagy with disease progression. This article discusses the advantages and limitations of different approaches for measuring autophagy as well as the techniques for modulating autophagy. These include analysis of endogenous LC3, a central autophagy regulatory protein, and measurement of LC3 flux using a dual-fluorescent reporter, which provides a quantitative readout of autophagy in cell culture systems in vitro and animal models in vivo. Degradation of SQSTM1/p62 during autophagy is proposed as an alternative biomarker allowing the analysis of autophagy both experimentally and clinically. However, the complex regulation of individual autophagy proteins and their involvement in multiple pathways means that several proteins must be analyzed together, preferably over a time course to accurately interpret changes in autophagic activity. Genetic modification of autophagy proteins can be used to better understand basic autophagic mechanisms contributing to health and disease, whereas small molecule inhibitors of autophagy regulatory proteins, lysosomal inhibitors, or activators of cytotoxic autophagy have been explored as potential treatments for skin disorders where autophagy is defective.