Methylmercury induces lysosomal membrane permeabilization through JNK-activated Bax lysosomal translocation in neuronal cells.

MeHg, an environmental toxicant, is highly toxic to the central nervous system. Recent studies have reported that LMP is an important way in the lysosomal damage. However, the role and molecular mechanism of LMP in MeHg-induced neurotoxicity remain unknown. To study MeHg-induced LMP, we used 10µM MeHg to treat SH-SY5Y cells and 2µM MeHg to treat rat cerebral cortical neurons. Acridine orange (AO) staining and analysis of cathepsin B (CTSB) release were used to determine LMP. We found that MeHg reduced red AO fluorescence and induced CTSB release from lysosomes to the cytoplasm in a time-dependent manner. Moreover, pretreatment with the CTSB inhibitor alleviated cytotoxicity in neuronal cells. These results indicate MeHg induces LMP and subsequent CTSB-dependent cytotoxicity in neuronal cells. Bax is a pore-forming protein, which is involved in mitochondrial outer membrane permeabilization. Intriguingly, we demonstrated that MeHg induced Bax to translocate to lysosomes by using immunofluorescence and Western blot analysis of subcellular fractions. Furthermore, downregulating Bax expression suppressed MeHg-induced LMP. Bax subcellular localization is regulated by protein interaction with the cytoplasmic 14-3-3. Our previous study demonstrated that JNK participated in neurotoxicity through regulating protein interaction. In the current study, we showed that JNK dissociated Bax-14-3-3 complex to facilitate Bax lysosomal translocation. Finally, inhibition of the JNK/Bax pathway could alleviate MeHg-induced cytotoxicity in neuronal cells. The present study implies that inhibiting lysosomal damage (LMP)-related signaling might alleviate MeHg neurotoxicity.

The mechanism research of STIM1 in breast cancer cells / 实用医学杂志

Objectives To explore the calcium signaling mechanism of STIM1 in breast cancer cells. Meth-ods After SiRNA interruption, Western blot and Transwell were used to measure protein expression of STIM1 and cell migration in MDA-MB-231 cells respectively. The relationship between STIM1 and SOCE calcium signaling were analysed by Laser confocal microscopy. Western blots were used to measure protein expression of FAK after si-lence STIM1. Results The numbers of cells without STIM1 were significantly lower than those cells with STIM1 by Transwell assay. STIM1 mediated SOCE in MDA-MB-231. Blocking SOCE might inhibite cells migration. Si-lence STIM1 did not affect the expression or activation of FAK in MDA-MB-231 cells. Conclusion STIM1 influ-ences cell migration through SOCE pathway in breast cancer cells, which is independent on the expression or activa-tion of FAK.