Deletion of Mitochondrial Translocator Protein (TSPO) Gene Decreases Oxidative Retinal Pigment Epithelial Cell Death via Modulation of TRPM2 Channel

Abstract

The current results indicated the possible protective actions of 18 kDa mitochondrial translocator protein (TSPO) deletion on TRPM2 stimulation, mitochondrial free ROS (Mito-fROS) and apoptotic harmful actions in the cells of adult retinal pigment epithelial19 (ARPE19). There was a direct relationship between TSPO and the disease of age-related macular degeneration. The nature of TSPO implicates upregulation of Mito-fROS and apoptosis via the activation of Ca2+ channels in ARPE19, although deletion of TSPO gene downregulates the activation. The decrease of oxidative cytotoxicity and apoptosis might induce in TSPO gene deleted cells by the inhibition of Mito-fROS and PARP-1 activation-induced TRPM2 cation channel activation. The ARPE19 cells were divided into two main groups as TSPO expressing (ARPE19) and non-expressing cells (ARPE19-KO). The levels of caspase -3 (Casp -3), caspase -9 (Casp -9), apoptosis, Mito-fROS, TRPM2 current and intracellular free Ca2+ were upregulated in the ARPE19 by the stimulations of H2O2 and ADP-ribose, although their levels were downregulated in the cells by the modulators of PARP-1 (DPQ and PJ34), TRPM2 (ACA and 2APB) and glutathione. However, the H2O2 and ADP-ribose-mediated increases were not observed in the ARPE19-KO. The expression levels of Bax, Casp -3, Casp -9 and PARP-1 were higher in the ARPE19 group as compared to the ARPE19-KO group. In summary, current results confirmed that TRPM2-mediated cell death and oxidative cytotoxicity in the ARPE19 cells were occurred by the presence of TSPO. The deletion of TSPO may be considered as a therapeutic way to TRPM2 activation-mediated retinal oxidative injury.

A novel antagonist of TRPM2 and TRPV4 channels: Carvacrol

“…The generation of ADPR in the SH-SY5Y could be decreased by the inhibitors of PARP-1 (Butenko et al 2012 ; Akyuva and Nazıroğlu 2020 ). The DPQ and PJ34 are two well-known PARP1 inhibitors in the TRPM2 channel experiments (Armağan and Nazıroğlu 2021 ; Özkaya et al 2021 ). Hence, I wanted to test modulator actions of ADPR production through DPQ and PJ34 treatment on the cCa 2+ concentrations in the SH-SY5Y cells.…”

Curcumin attenuates hydroxychloroquine-mediated apoptosis and oxidative stress via the inhibition of TRPM2 channel signalling pathways in a retinal pigment epithelium cell line

“…Although they lack some physiological characteristics of the RPE, ARPE-19 cells are regarded as a reliable model for investigating RPE cell metabolism [ 9 , 11 , 12 ]. The detrimental oxidative and apoptotic effects of medicines such as HCQ and chloroquine have been experimentally studied using ARPE19 cells as a model of the human RPE [ 9 , 11 , 12 ]. Recently, it was also reported that a TRPM2 channel naturally exists in ARPE19 cells [ 16 , 27 ].…”

“…In addition to the CASY cell viability analyses, the cell viability analyses were repeated in the cells by using the MTT test [ 11 , 12 ]. For the analyses, the ARPE19 cells were seeded in ninety-six-well plates at an initial density of 1 × 10 6 cells/well and were treated with 100 µl of 5 mg/ml of MTT in PBS was added to each well, and incubated for 4 h at 37 °C.…”

“…Stimulation of the transient receptor potential melastatin 2 (TRPM2) channels in ARPE19 cells by a number of drugs, including bevacizumab [ 11 ] and cisplatin [ 15 ], has been reported to cause adverse oxidative and apoptotic effects. However, these negative effects have been counteracted by the use of TRPM2 channel antagonists, including carvacrol (CRV) and N-(p-amylcinnamoyl)anthranilic acid (ACA) [ 12 , 13 , 16 ], as well as antioxidants, such as CRC and glutathione [ 11 , 15 ]. The involvement of TRPM2 has not been reported in HCQ-mediated overload cCa 2+ influx and mROS generation in ARPE19 cells.…”

“…The influx of Ca 2+ modulates the physiological functions of retinal cells [ 17 ]. However, increased mROS production and apoptosis are induced by elevated Ca 2+ accumulation within the mitochondria via the activation of TRPM2 in ARPE19 cells [ 12 , 13 , 15 , 16 ]. CRC is a bright-yellow material produced by plants of the Curcuma longa genus.…”