F-actin plays a crucial role in fundamental cellular processes, and is extremely susceptible to peroxynitrite attack due to the high abundance of tyrosine in the peptide. Methionine sulfoxide reductase (Msr) B1 is a selenium-dependent enzyme (selenoprotein R) that may act as a reactive oxygen species (ROS) scavenger. However, its function in coping with reactive nitrogen species (RNS)-mediated stress and the physiological significance remain unclear. Thus, the present study was conducted to elucidate the role and mechanism of MsrB1 in protecting human lens epithelial (hLE) cells against peroxynitrite-induced F-actin disruption. While exposure to high concentrations of peroxynitrite and gene silencing of MsrB1 by siRNA alone caused disassembly of F-actin via inactivation of extracellular signal-regulated kinase (ERK) in hLE cells, the latter substantially aggravated the disassembly of F-actin triggered by the former. This aggravation concurred with elevated nitration of F-actin and inactivation of ERK compared with that induced by the peroxynitrite treatment alone. In conclusion, MsrB1 protected hLE cells against the peroxynitrite-induced F-actin disruption, and the protection was mediated by inhibiting the resultant nitration of F-actin and inactivation of ERKs.
Keywords: DMEM; Dulbecco’s Modified Eagle’s Medium; ECL; ERK; Extracellular signal-regulated kinase; F-actin; G-actin; Human lens epithelial cells; MAPK; MEK; MetO; Methionine sulfoxide reductase B1; Msr; NCS; PBS; Peroxynitrite; RNS; ROS; RT; SelR; T-TBS; bFGF; basic fibroblast growth factor; enhanced chemiluminescence; extracellular signal-related kinase; filamentous actin; globular actin; hLE; human lens epithelial; methionine sulfoxide; methionine sulfoxide reductase; mitogen-activated protein kinase; mitogen-activated protein kinase kinase; newborn calf serum; phosphate-buffered saline; reactive nitrogen species; reactive oxygen species; room temperature; selenoprotein R; short interfering RNA; siRNA; tris-buffered saline with Tween.
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