title: Reactive oxygen species mediate RANK signaling in osteoclasts.
abstract: RANKL, a member of tumor necrosis factor (TNF) superfamily, regulates the differentiation, activation, and survival of osteoclasts through binding to its cognate receptor, RANK. RANK can interact with several TNF-receptor-associated factors (TRAFs) and activates signaling molecules including Akt, NF-kappaB, and MAPKs. Although the transient elevation of reactive oxygen species (ROS) by receptor activation has been shown to act as a cellular secondary messenger, the involvement of ROS in RANK signaling pathways has been not characterized. In this study, we found that RANKL stimulated ROS generation in osteoclasts. Pretreatment of osteoclasts with the antioxidants N-acetyl-l-cystein and glutathione reduced RANKL-induced Akt, NF-kappaB, and ERK activation. The reduced NF-kappaB activity by antioxidants was associated with decreased IKK activity and IkappaBalpha phosphorylation. In contrast, antioxidants did not prevent TNF-alpha-induced Akt and NF-kappaB activation. Pretreatment with antioxidants also significantly reduced RANKL-induced actin ring formation, required for bone resorbing activity, and osteoclast survival. Taken together, our results suggest that ROS act as mediators in RANKL-induced signaling pathways and cellular events.
authors.affiliation: Department of Cell and Developmental Biology, College of Dentistry, Seoul National University, Seoul 110-749, Korea.
authors.forename: Hyunil
authors.initials: H
authors.lastname: Ha
authors.forename: Han Bok
authors.initials: HB
authors.lastname: Kwak
authors.forename: Soo Woong
authors.initials: SW
authors.lastname: Lee
authors.forename: Hye Mi
authors.initials: HM
authors.lastname: Jin
authors.forename: Hyun-Man
authors.initials: HM
authors.lastname: Kim
authors.forename: Hong-Hee
authors.initials: HH
authors.lastname: Kim
authors.forename: Zang Hee
authors.initials: ZH
authors.lastname: Lee
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002352:Carrier Proteins / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D053245:RANK Ligand; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism*; D053246:Receptor Activator of Nuclear Factor-kappa B; D015398:Signal Transduction
chemical_list: D000199:Actins; D000975:Antioxidants; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D053245:RANK Ligand; D017382:Reactive Oxygen Species; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases