Endogenous Expression of HSP70 and Thioredoxin-1 During Methamphetamine-Induced Degeneration.

Abstract

Background/Objectives: Although HSP70 and thioredoxin-1 (TRX1) are well known to counteract methamphetamine (METH)-induced neurodegeneration, no evidence on the effects of METH administration concerning the level, localization, and co-expression of HSP70 and/or TRX1 is available. Therefore, in the present study, carried out using methamphetamine-treated PC12 cells, we sought to analyze these effects along with the merging of specific markers for mitochondria, autophagy, lysosomes, and chaperone-mediated autophagy (CMA). Methods: The levels of specific proteins for specific cell compartments were assessed along with their merging. Thus, co-expression of HSP70 and TRX1 with lipidated LC3 (LC3-II), as well as lysosomal markers such as LAMP1 and LAMP2 (a specific marker for CMA), was assessed. Due to severe mitochondrial alterations produced by METH, both MitoTracker green and MitoTracker red were used in these experimental conditions. Light and electron microscopy, including in situ stoichiometry, were used in these experiments. Results: A moderate dose of METH, 100 µM, increases both TRX1 and HSP70; while HSP70 is preferentially co-expressed with the lysosome marker LAMP1, TRX1 is instead co-expressed with the marker LAMP2, which stains for CMA. Both chaperones increase along with cleaved caspase 3 and the autophagosome marker LC3-II. Conclusions: The outcome of the present study applies to METH-induced intoxication and is relevant in the fields of neurodegeneration, acute neuronal injury, and the domain of drug abuse. In fact, suppression of TRX1 enables METH-induced addiction, while overexpression of TRX1 or HSP70 produces the opposite effect.