Chlorpyrifos-oxon induced neuronal cell death via endoplasmic reticulum stress-triggered apoptosis pathways.

Chlorpyrifos (CPF) is one of the organophosphorus pesticides widely used throughout the world. Epidemiological studies suggested a link between CPF exposure and neurologic disorders, while the molecular mechanisms remain inconclusive. In the present study, we investigated the impacts of chlorpyrifos-oxon (CPO), the major toxic CPF metabolite, on cell apoptosis, and explored possible mechanism associated with endoplasmic reticulum (ER) stress in SH-SY5Y cells. Results showed that CPO exposure induced dose-dependent apoptosis and expression of ER stress-related proteins in SH-SY5Y cells. Pretreatment with 4-PBA (an ER stress inhibitor) effectively inhibited the expression of GRP78, GRP94, p-IRE1α, and XBP1-s, and apoptotic events. Pretreatment with STF-083010 (an IRE1α inhibitor) partially attenuated CPO-induced apoptosis. In addition, CPO exposure significantly evoked the generation of reactive oxygen species (ROS) which could be eliminated by pretreatment of 4-PBA. Of note, buffering the ROS generation with antioxidant NAC had little impact on the expression of p-IRE1α, and only partially attenuated CPO-induced apoptosis. In contrast, co-pretreatment with NAC and STF-083010 effectively inhibited CPO-induced apoptotic events. Collectively, our results indicate that CPO exposure exerts neuronal cytotoxicity via ER stress downstream-regulated IRE1α/XBP1 signaling pathway and ROS generation-triggered apoptosis. These findings highlight the role of ER stress in CPF-induced neurotoxicity, and provide a promising target for the intervention of organophosphate-associated neurodegenerative diseases.

Combined effect of co-exposure to di (2-ethylhexyl) phthalates and 50-Hz magnetic-fields on promoting human amniotic cells proliferation.

Di (2-ethylhexyl) phthalate (DEHP) and extremely low-frequency electromagnetic fields (ELF-EMFs) exist far and wide in our surroundings. Studies have reported that both of DEHP and ELF-EMFs could promote cell proliferation which is related with adverse bioeffects. In this study, we investigated whether there is the combined effect between DEHP and 50-Hz magnetic fields (MFs) on cell proliferation in human amniotic (FL) cells. Results revealed that the low-concentration DEHP (1 µM) could promote FL cell proliferation, whereas the high-dose DEHP (100 µM) inhibited cell proliferation. When FL cells were treated jointly by a 50-Hz, 0.2-mT MF and 0.1 µM DEHP, the proliferation rate of cells was significantly higher than that of single factor exposure. Additionally, co-exposure to under-threshold MF and DEHP could cooperatively activate protein kinase B (Akt), sphingosine kinase 1 (SphK1) and extracellular signal regulated kinase (ERK) in a cascade manner, and finally mediate cell proliferation. Taken together, the findings of this study indicated that the co-exposure to under-threshold MF and DEHP could jointly promote cell proliferation through activating proliferation-related signal pathway, which warned us that it should be cautious about assessing the underlying health hazards of co-exposure to MFs and DEHP at under-threshold levels.

A 50-Hz magnetic-field exposure promotes human amniotic cells proliferation via SphK-S1P-S1PR cascade mediated ERK signaling pathway.

Extremely low-frequency electromagnetic fields (ELF-EMFs) present a kind of common non-ionizing radiation in public and occupational environments. Previous studies have suggested that ELF-EMF exposure might have a potential impact on co-carcinogenesis and the progression of tumorigenesis by inducing cell proliferation. However, the underlying mechanisms remain largely unknown. In this study, we investigated the possible role of the sphingosine-1-phosphate (S1P)-related pathway in regulating cell proliferation induced by 50-Hz, 0.4-mT magnetic-field (MF) exposure. The results showed that MF exposure significantly promoted sphingosine kinase 1 (SphK1) activity, and that inhibition of the SphK1-S1P-S1P receptor (S1PR) pathway could remarkably reverse MF-induced cell proliferation. Additionally, we could infer indirectly from an exogenous-S1P experiment that MF-induced S1P might act on S1PR1/3 in a paracrine and/or autocrine manner to mediate the proliferation effect. Notably, although the MF activated the extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) pathways, the SphK1-S1P-S1PR1/3 cascade regulated MF-induced proliferation by activating the ERK rather than the Akt pathway. Taken together, the findings of this study indicated that the SphK1-S1P-S1PR1/3 cascade played an important role in MF-induced proliferation by mediating the ERK signaling pathway, which could bring new insights into understanding and preventing the adverse effects of MFs.

The endoplasmic reticulum stress and related signal pathway mediated the glyphosate-induced testosterone synthesis inhibition in TM3 cells.

Glyphosate is the most widely used herbicide in the world. In recent years, many studies have demonstrated that exposure to glyphosate-based herbicides (GHBs) was related to the decrease of serum testosterone and the decline in semen quality. However, the molecular mechanism of glyphosate-induced testosterone synthesis disorders is still unclear. In the present study, the effects of glyphosate on testosterone secretion and the role of endoplasmic reticulum (ER) stress in the process were investigated in TM3 cells. The effects of glyphosate at different concentrations on the viability of TM3 cells were detected by CCK8 method. The effect of glyphosate exposure on testosterone secretion was determined by enzyme-linked immunosorbent assay (ELISA). The expression levels of testosterone synthases and ER stress-related proteins were detected by Western blot and Immunofluorescence stain. Results showed that exposure to glyphosate at concentrations below 200 mg/L had no effect on cell viability, while the glyphosate above 0.5 mg/L could inhibit the testosterone secretion in TM3 cells. Treatment TM3 cells with glyphosate at 5 mg/L not only reduced the protein levels of testosterone synthase StAR and CYP17A1, inhibited testosterone secretion, but also increased the protein level of ER stress molecule Bip and promoted the phosphorylation of PERK and eIF2α. Pretreatment cells with PBA, an inhibitor of ER stress, alleviated glyphosate-induced increase in Bip, p-PERK and p-eIF2α protein levels, meanwhile rescuing glyphosate-induced testosterone synthesis disorders. When pretreatment with GSK2606414, a PERK inhibitor, the glyphosate-induced phosphorylation of PERK and eIF2α was blocked, and the glyphosate-inhibited testosterone synthesis and secretion was also restored. Overall, our findings suggest that glyphosate can interfere with the expression of StAR and CYP17A1 and inhibit testosterone synthesis and secretion via ER stress-mediated the activation of PERK/eIF2α signaling pathway in Leydig cells.