The protective effect of tomatidine on TNF alpha induced apoptosis in C2C12 myoblasts
Seung-Eun Song1, Su-Kyung Shin1, Hyun Woo Cho1, So-Yeon Kim1 , Seung-Soon Im1, Jae-Hoon Bae1, Dae-Kyu Song1* 1Department of Physiology, Keimyung University School of Medicine, Daegu, Korea
In this study, we examined the effect of tomatidine on tumor necrosis factor (TNF)-alpha-induced apoptosis in C2C12 myoblasts. TNF-alpha treatment increased cleaved caspase 3 and cleaved poly (ADP-ribose) polymerase (PARP) protein levels in a dose- and time-dependent manner. Pretreatment of cells with 10 μM tomatidine prevented TNF-alpha-induced apoptosis, caspase 3 cleavage, and PARP cleavage. Cells were treated with 100 ng/mL TNF-alpha for 24 h, and flow cytometry was utilized to assess apoptosis using annexin-V and 7-aminoactinomycin D. TNF-alpha up-regulated activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP) expression. This effect was suppressed by pretreatment with tomatidine. Pretreatment with 4-phenylbutyric acid (a chemical chaperone) also inhibited TNF-alpha-induced cleavage of caspase 3 and PARP and up-regulation of ATF4 and CHOP expression. In addition, tomatidine-mediated inhibition of phosphorylation of c-Jun amino terminal kinase (JNK) attenuated TNF-alpha-induced cleavage of PARP and caspase 3. However, tomatidine did not affect NF-kB activation in TNF-alpha-treated C2C12 myoblast cells. Taken together, the present study demonstrates that tomatidine attenuates TNF-alpha-induced apoptosis through down-regulation of CHOP expression and inhibition of JNK activation.