Latency of Lysosomal Proteinases

Abstract

The review on lysosomal functions cogently summarizes their roles in cell survival (1Turk B. Turk V. Lysosomes as “suicide bags” in cell death: myth or reality?.J. Biol. Chem. 2009; 284: 21783-21787Abstract Full Text Full Text PDF PubMed Scopus (220) Google Scholar). I would like to add that one important substrate for acid proteinase (cathepsin D) is the myelin basic protein. The increase in the free activity of acid proteinase could thus account for demyelination seen as a complication of carbon monoxide poisoning (2Savolainen H. Elovaara E. Effect of carbon monoxide on protein metabolism in mouse brain..Exp. Neurol. 1977; 57: 374-378Crossref PubMed Scopus (11) Google Scholar). It is interesting to note that the increased proteolysis was apparently compensated for by increased synthesis (2Savolainen H. Elovaara E. Effect of carbon monoxide on protein metabolism in mouse brain..Exp. Neurol. 1977; 57: 374-378Crossref PubMed Scopus (11) Google Scholar). As to the loss of the lysosomal latency, it may have been caused by peroxidative damage in the reoxygenation period (3Savolainen H. Labilization of cerebral lysosomes by autologous microsomes and protection by cytosolic fraction and a superoxide scavenger in vitro..Biochem. Biophys. Res. Commun. 1979; 86: 1222-1226Crossref PubMed Scopus (6) Google Scholar). In this case, the lysosomal latency could be maintained by a complete superoxide dismutase-glutathione peroxide system or with a less efficient addition of sodium benzoate, a hydroxyl radical scavenger (3Savolainen H. Labilization of cerebral lysosomes by autologous microsomes and protection by cytosolic fraction and a superoxide scavenger in vitro..Biochem. Biophys. Res. Commun. 1979; 86: 1222-1226Crossref PubMed Scopus (6) Google Scholar).