Objective: The organophosphate compounds chlorpyrifos (O, O-diethyl O-[3,5,6-trichloro-2-pyridinyl] phosphorothioate, CPF) and phenyl saligenin phosphate (PSP) have been widely implicated in developmental neurotoxicity and neurodegeneration. However, the underlying mechanism remains unclear. Transglutaminase (TG)2 is a calcium ion (Ca2+)-dependent enzyme with an important role in neuronal cell outgrowth and differentiation and in neurotoxin activity and is modulated by organophosphates.
Materials and methods: We studied TG2 activity modulation by CPO and PSP during differentiation in C6 glioma cells. We studied the effects of CPO or PSP treatment with or without the TG2 inhibitor Z-DON and identified potential TG2 protein substrates via mass spectrometry.
Results: PSP and CPO did not affect cell viability but affected TG2 activity in differentiating cells. Our results indicate that the organophosphate-induced amine incorporation activity of TG2 may have a direct effect on neuronal outgrowth, differentiation, and cell survival by modifying several essential microtubule proteins, including tubulin. Inhibiting TG2 reduced neurite length but not cell survival.
Conclusions: TG2 inhibitors can protect against organophosphate-induced neuropathy and could be used for developing novel therapeutic strategies for treating brain cancer and neurodegenerative disorders.