Analysis of Chaperone-Mediated Autophagy

Chaperone-mediated autophagy (CMA) is a selective type of autophagy whereby a specific subset of intracellular proteins is targeted to the lysosome for degradation. These proteins are identified by a chaperone that targets them to lysosomes. There, they are translocated into the organelle lumen through a lysosomal membrane receptor/translocation complex. CMA plays an important role in maintaining cellular proteostasis by eliminating damaged and altered proteins. CMA also participates in the control of the cellular energetic balance through recycling of amino acids resulting from lysosomal proteolysis of the substrate proteins. Lastly, due to the intrinsic protein selectivity of CMA, this type of autophagy exerts regulatory functions by mediating timely degradation of key cellular proteins that participate in processes such as lipid and glucose metabolism, cell cycle, DNA repair, and cellular reprogramming, among others. Dysfunctional CMA occurs with age and has now been described in a growing list of human pathologies such as metabolic disorders, neurodegeneration, cancer, immunodeficiency, and diabetes. In this chapter, we describe current methodologies to quantitatively analyze CMA activity in different experimental models.