This is consistent with reports indicating that ubiquitin-mediated degradation is usually important for proteins with a half-life of 3 5 hours, while for proteins with half-lives longer than 30 hours degradation is linked to lysosomes [12].
Further evidence is that the build-up of iduronic acid in the lysosome has been linked to lysosomal storage disorder caused by defects in the sialic acid lysosomal transporter [ 55].
The other mechanisms of anti-inflammatory action of whole-body cryotherapy may be linked to stabilization of lysosome membranes and subsequent inhibition of release of active enzymes from lysosomes [ 40].
To date, up to 50 lysosome-dependent diseases have been described in human (called Lysosomal Storage Diseases, LSDs), and are linked to mutations in the genes encoding the different lysosomal hydrolases and LMPs proteins.
Additionally, increased levels of cAMP have been linked to reduced actin assembly, inhibition of phagosome-lysosome fusion and acidification, and increased intraphagosomal growth of pathogens [33].
Autophagy in the RPE is used as in most cells to maintain cell homeostasis, and for example in age-related macular degeneration the disease-related build-up of lipofuscin in lysosomes of the RPE has been linked to abnormal autophagy.
Degradative capacity is linked to the maintenance of an acidic milieu in the lysosome, an energy dependent process requiring the vacuolar-type proton ATPase (V-ATPase) and other hydrogen pumps, which are required for activation of the proteases [43], [44].
Several lysosome-associated proteins have subsequently been linked to rare and rather atypical forms, including ATP1A3 in rapid-onset parkinsonism-dystonia, and most recently ATP6AP2[ 71].
To corroborate these findings, we assessed the fusion of endosomes or autophagosomes to lysosomes using NIH-3T3 cells stably expressing a tandem fluorescence-tagged autophagosomal marker in which LC3 was linked to both monomeric red fluorescent protein (mCherry) and GFP.
