Degradation of neuropathy target esterase by the macroautophagic lysosomal pathway.
OBJECTIVE
Neuropathy target esterase (NTE) was proposed as the initial target during the process of organophosphate-induced delayed neuropathy (OPIDN) in humans and some sensitive animals. NTE was recently identified as a novel phospholipase B that is anchored to the cytoplasmic side of the endoplasmic reticulum. However, little is known about the degradation of NTE. In this study, we have investigated the role of the macroautophagic-lysosomal pathway in NTE degradation in neuronal and non-neuronal cells.


METHODS
Macroautophagy inhibitors and activators were used to interrupt the lysosomal pathway, and NTE protein level was followed using western blotting analysis. A fluorescent microscopy assay was used to determine the co-localization of NTE and lysosomes.


RESULTS
Western blotting analysis showed that the macroautophagy inhibitors 3-methyladenine and ammonium chloride increased the levels of a heterologously expressed NTE-GFP fusion protein as well as endogenous NTE. Starvation had the opposite effect. The role of macroautophagy in NTE degradation was further supported by the co-localization of exogenous NTE with lysosomes in starved COS7 cells. Furthermore, the contribution of NTE activity and protein domains to the degradation of NTE by macroautophagy was investigated, showing that both the transmembrane and regulatory domains played a role in the degradation of NTE and that the catalytic domain, and thus NTE activity, was not involved.


CONCLUSIONS
Our findings clearly demonstrate, for the first time, that the macroautophagy/lysosome pathway plays a role in controlling NTE quantity, providing a further understanding of the function of NTE.
Long
Ding-Xin
DX
Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
Chang
Ping-An
PA
Liang
Yu-Jie
YJ
Yang
Lin
L
Wu
Yi-Jun
YJ
D000818:Animals; D001343:Autophagy; D019556:COS Cells; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*
D049452:Green Fluorescent Proteins; D002265:Carboxylic Ester Hydrolases; C021859:neurotoxic esterase