title: Ethyl pyruvate inhibits HMGB1 phosphorylation and release by chelating calcium.
abstract: Ethyl pyruvate (EP), a simple aliphatic ester of pyruvic acid, has been shown to have antiinflammatory effects and to confer protective effects in various pathological conditions. Recently, a number of studies have reported EP inhibits high mobility group box 1 (HMGB1) secretion and suggest this might contribute to its antiinflammatory effect. Since EP is used in a calcium-containing balanced salt solution (Ringer solution), we wondered if EP directly chelates Ca(2+) and if it is related to the EP-mediated suppression of HMGB1 release. Calcium imaging assays revealed that EP significantly and dose-dependently suppressed high K(+)-induced transient [Ca(2+)]i surges in primary cortical neurons and, similarly, fluorometric assays showed that EP directly scavenges Ca(2+) as the peak of fluorescence emission intensities of Mag-Fura-2 (a low-affinity Ca(2+) indicator) was shifted in the presence of EP at concentrations of ≥7 mmol/L. Furthermore, EP markedly suppressed the A23187-induced intracellular Ca(2+) surge in BV2 cells and, under this condition, A23187-induced activations of Ca(2+)-mediated kinases (protein kinase Cα and calcium/calmodulin-dependent protein kinase IV), HMGB1 phosphorylation and subsequent secretion of HMGB1 also were suppressed. (A23187 is a calcium ionophore and BV2 cells are a microglia cell line.) Moreover, the above-mentioned EP-mediated effects were obtained independent of cell death or survival, which suggests that they are direct effects of EP. Together, these results indicate that EP directly chelates Ca(2+), and that it is, at least in part, responsible for the suppression of HMGB1 release by EP.
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Joo-Hyun
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Il-Doo
authors.initials: ID
authors.lastname: Kim
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Seung-Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Yinchuan
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Chemistry, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: Ju-Hun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Brain and Cognitive Science, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: Tae-Kyung
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Physiology and Biophysics, Inha University, Incheon, Republic of Korea.
authors.forename: Chang-Kook
authors.initials: CK
authors.lastname: Suh
authors.affiliation: Department of Physiology and Biophysics, Inha University, Incheon, Republic of Korea.
authors.forename: Jiyeon
authors.initials: J
authors.lastname: Kwak
authors.affiliation: Department of Chemistry, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: Keun-Hyeung
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Brain and Cognitive Science, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: Pyung-Lim
authors.initials: PL
authors.lastname: Han
authors.affiliation: Department of Anatomy, Inha University School of Medicine, Incheon, Republic of Korea.
authors.forename: Ja-Kyeong
authors.initials: JK
authors.lastname: Lee
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D024243:HMGB1 Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects; D010766:Phosphorylation; D011773:Pyruvates / Q000494:pharmacology*
chemical_list: D024243:HMGB1 Protein; D011773:Pyruvates; C046522:ethyl pyruvate; D000001:Calcimycin; D016202:N-Methylaspartate; D002118:Calcium