Ethanol induces cell cycle arrest and triggers apoptosis via Sp1-dependent p75NTR expression in human neuroblastoma cells

Abstract

Ethanol exposure has deleterious effects on the central nervous system. Although several mechanisms for ethanol-induced damage have been suggested, the precise mechanism underlying ethanol-induced neuronal cell death remains unclear. Recent studies indicate that the p75 neurotrophin receptor (p75NTR) has a critical role in the regulation of neuronal survival. This study was designed to examine the role of p75NTR in ethanol-induced apoptotic signaling in neuroblastoma cells. Ethanol caused highly increased level of p75NTR expression. The use of small interfering RNA to inhibit p75NTR expression markedly attenuated ethanol-induced cell cycle arrest and apoptosis. DNA binding activity of Sp1 was increased by ethanol, whereas inhibition of Sp1 activity by mithramycin, a Sp1 inhibitor, or short hairpin RNA suppressed ethanol-induced p75NTR expression. In addition, inhibitors of casein kinase 2 (CK2) and extracellular signal-regulated kinase (ERK) augmented ethanol-induced p75NTR expression. Our results also demonstrate that inhibition of ERK and CK2 caused a further increase in the activation of the p75NTR proximal promoter induced by ethanol. This increased activation was partially suppressed by the deletion of the Sp1 binding sites. These results suggest that Sp1-mediated p75NTR expression is regulated at least in part by ERK and CK2 pathways. The present study also showed that treatment with ethanol resulted in significant increases in the expression of p21, but not the levels of p53 and p53 target genes such as Bax, Puma, and Bcl-2. Furthermore, the inhibition of p75NTR expression or Sp1 activity suppressed ethanol-induced p21 expression, cell cycle arrest, and apoptosis. These data suggest that ethanol increases p75NTR expression, and CK2 and ERK signaling inversely regulate Sp1-mediated p75NTR expression in ethanol-treated neuroblastoma cells. Thus, our study provides more insight into the mechanisms underlying ethanol actions.

Gene expression and highly diluted molecules

“…As clearly indicated in our paper (Marzotto et al, 2014), the final ethanol concentration was 0.03% v/v (p. 2), and “no significant differences in cell viability were observed between cells treated with the ethanol control solution 0.03% (v/v) and untreated cells” (p. 5). Furthermore, as other researchers have found (Do et al, 2013), cell viability of neurocytes is unaffected by doses of ethanol up to 10 mmol/L (0.06%). Low doses of ethanol may influence gene expression, but would have acted in the same way in the Gelsemium and in the control samples.…”

Peptide selected by phage display increases survival of SH‐SY5Y neurons comparable to brain‐derived neurotrophic factor

“…The results of monoclonal phage-ELISA indicated that all clones had principally bound to NTRK2 (binding affinity above 2.1), as shown in Figure 3. Clones 1, 3, 10, 14,16,17,19,20,22,23,24,28,30,31, and 32 were selected as strongly positive phage plaques for sequencing and further analysis (quadruple asterisks with a significant difference in Figure 3).…”

Distinction Between Cell Proliferation and Apoptosis Signals Regulated by Brain‐Derived Neurotrophic Factor in Human Periodontal Ligament Cells and Gingival Epithelial Cells

“…It was reported that the activation of JNK reduced cell proliferation by elevation of the expression of cyclin‐dependent kinase inhibitor (cell‐cycle inhibitor) p21 in neuroblastic cells [Haeusgen et al, ]. Coincident with this report, p75 receptor is engaged in the suppression of neuroblastoma cell growth by p21 induction [Do et al, ]. Moreover, p75 also regulates other cell‐cycle inhibitors, p27 and Rb, to block the proliferation of gastric cancer cells [Jin et al, ].…”