title: Mild electrical stimulation at 0.1-ms pulse width induces p53 protein phosphorylation and G2 arrest in human epithelial cells.
abstract: Exogenous low-intensity electrical stimulation has been used for treatment of various intractable diseases despite the dearth of information on the molecular underpinnings of its effects. Our work and that of others have demonstrated that applied electrical stimulation at physiological strength or mild electrical stimulation (MES) activates the PI3K-Akt pathway, but whether MES activates other molecules remains unknown. Considering that MES is a form of physiological stress, we hypothesized that it can activate the tumor suppressor p53, which is a key modulator of the cell cycle and apoptosis in response to cell stresses. The potential response of p53 to an applied electrical current of low intensity has not been investigated. Here, we show that p53 was transiently phosphorylated at Ser-15 in epithelial cells treated with an imperceptible voltage (1 V/cm) and a 0.1-ms pulse width. MES-induced p53 phosphorylation was inhibited by pretreatment with a p38 MAPK inhibitor and transfection of dominant-negative mutants of p38, MKK3b, and MKK6b, implying the involvement of the p38 MAPK signaling pathway. Furthermore, MES treatment enhanced p53 transcriptional function and increased the expression of p53 target genes p21, BAX, PUMA, NOXA, and IRF9. Importantly, MES treatment triggered G2 cell cycle arrest, but not cell apoptosis. MES treatment had no effect on the cell cycle in HCT116 p53(-/-) cells, suggesting a dependence on p53. These findings identify some molecular targets of electrical stimulation and incorporate the p38-p53 signaling pathway among the transduction pathways that MES affects.
authors.affiliation: Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Fukuda
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Suico
authors.forename: Kosuke
authors.initials: K
authors.lastname: Koyama
authors.forename: Kohei
authors.initials: K
authors.lastname: Omachi
authors.forename: Yukari
authors.initials: Y
authors.lastname: Kai
authors.forename: Shingo
authors.initials: S
authors.lastname: Matsuyama
authors.forename: Kazunori
authors.initials: K
authors.lastname: Mitsutake
authors.forename: Manabu
authors.initials: M
authors.lastname: Taura
authors.forename: Saori
authors.initials: S
authors.lastname: Morino-Koga
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shuto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kai
mesh_terms: D004558:Electric Stimulation; D004847:Epithelial Cells; D059565:G2 Phase Cell Cycle Checkpoints; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D048371:MAP Kinase Kinase 3 / Q000235:genetics / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D047428:Protein Kinase Inhibitors; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; C482530:MAP2K3 protein, human; C482566:MAP2K6 protein, human
keywords: Electrophysiology; G2 Arrest; Mild Electrical Stimulation; Signaling; Stress; p38; p53; p53 Activation