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Updated: May 22, 2026
A General Method for Evaluating Deep Brain Stimulation Effects on Intravenous Methamphetamine Self-Administration
Published on: January 22, 2016
Hyperstimulation of macropinocytosis leads to lysosomal dysfunction during exposure to methamphetamine in SH-SY5Y
Akina Nara1, Toshihiko Aki, Takeshi Funakoshi
1Section of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan. akina.legm@gmail.com
Abstract:
Although various cytotoxic effects on neuronal cells caused by methamphetamine (METH) have been investigated, the cellular and molecular mechanisms of METH-induced neurotoxicity remain to be elucidated. We previously reported that METH-induced cytomorphological effects on retinoic acid (RA)-differentiated SH-SY5Y human neuroblastoma cells involved macropinocytosis, which is an actin-dependent endocytic pathway. We also noted that hyperstimulation of this process might play an important role in the cytotoxicity of METH in neuronal cells. In this study, we investigated the molecular mechanisms as well as subsequent outcomes of macropinocytosis during METH treatment. It was found that macropinosomes formed upon exposure to METH were colocalized with constitutively active GFP-Ras (G12V) and GFP-Rac1 (Q61L). Furthermore, both Ras inhibitor, farnesylthiosalicylic acid (FTS), and Rac1 inhibitor, EHT1864, significantly inhibited the formation of macropinosomes, suggesting the involvement of these molecules. The expressions of lysosome-associated membrane proteins (lamps) gradually increased by METH in a time-dependent manner. In contrast, the proteolytic activation of cathepsin L, a marker of lysosomal function, was markedly suppressed by METH. METH-induced dysfunction of lysosomal enzyme as well as cell death was significantly attenuated by nocodazole, a microtube interfering reagent that inhibits the transport of vesicles, including macropinosome, to lysosomes. Our results indicate that METH has cytotoxic effects, at least in part, by inhibiting normal lysosomal function through Ras- and Rac1-mediated macropinocytosis in RA-differentiated SH-SY5Y cells.
Insights
Methamphetamine (METH) causes neuronal cell death by disrupting lysosomal function via Ras- and Rac1-mediated macropinocytosis. Inhibiting this pathway protects against METH neurotoxicity.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- Methamphetamine (METH) neurotoxicity mechanisms are not fully understood.
- METH induces cytomorphological changes in neuronal cells via macropinocytosis, an actin-dependent endocytic pathway.
- Hyperstimulation of macropinocytosis may contribute to METH's cytotoxicity.
Purpose of the Study:
- To investigate the molecular mechanisms and outcomes of macropinocytosis during METH treatment.
- To elucidate the role of Ras and Rac1 in METH-induced macropinocytosis.
- To determine the impact of METH on lysosomal function and cell death.
Main Methods:
- Utilized retinoic acid (RA)-differentiated SH-SY5Y human neuroblastoma cells.
- Observed macropinosome formation and colocalization with active GFP-Ras (G12V) and GFP-Rac1 (Q61L).
- Employed Ras inhibitor (FTS) and Rac1 inhibitor (EHT1864) to assess macropinocytosis inhibition.
- Measured lysosome-associated membrane proteins (lamps) expression and cathepsin L activity.
- Investigated the effect of nocodazole on METH-induced lysosomal dysfunction and cell death.
Main Results:
- METH exposure led to macropinosomes colocalizing with active Ras and Rac1.
- Ras and Rac1 inhibitors significantly reduced METH-induced macropinosome formation.
- METH increased lamps expression but suppressed cathepsin L activation, indicating lysosomal dysfunction.
- Nocodazole attenuated METH-induced lysosomal dysfunction and cell death.
Conclusions:
- METH exerts cytotoxic effects by inhibiting lysosomal function through Ras- and Rac1-mediated macropinocytosis.
- This pathway is crucial for METH-induced neurotoxicity in RA-differentiated SH-SY5Y cells.
- Targeting this macropinocytosis pathway may offer therapeutic strategies against METH neurotoxicity.
