title: Purinergic signaling is required for fluid shear stress-induced NF-κB translocation in osteoblasts.
abstract: Fluid shear stress regulates gene expression in osteoblasts, in part by activation of the transcription factor NF-κB. We examined whether this process was under the control of purinoceptor activation. MC3T3-E1 osteoblasts under static conditions expressed the NF-κB inhibitory protein IκBα and exhibited cytosolic localization of NF-κB. Under fluid shear stress, IκBα levels decreased, and concomitant nuclear localization of NF-κB was observed. Cells exposed to fluid shear stress in ATP-depleted medium exhibited no significant reduction in IκBα, and NF-κB remained within the cytosol. Similar results were found using oxidized ATP or Brilliant Blue G, P2X(7) receptor antagonists, indicating that the P2X(7) receptor is responsible for fluid shear-stress-induced IκBα degradation and nuclear accumulation of NF-κB. Pharmacologic blockage of the P2Y6 receptor also prevented shear-induced IκBα degradation. These phenomena involved neither ERK1/2 signaling nor autocrine activation by P2X(7)-generated lysophosphatidic acid. Our results suggest that fluid shear stress regulates NF-κB activity through the P2Y(6) and P2X(7) receptor.
authors.affiliation: Department of Anatomy, Cell Biology, and Physiology, School of Veterinary Medicine, University of California, Davis, CA, USA. dgenetos@ucdavis.edu
authors.forename: Damian C
authors.initials: DC
authors.lastname: Genetos
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Karin
authors.forename: Derik J
authors.initials: DJ
authors.lastname: Geist
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Donahue
authors.forename: Randall L
authors.initials: RL
authors.lastname: Duncan
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D007150:Immunohistochemistry; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D021381:Protein Transport; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism; D015398:Signal Transduction; D013314:Stress, Mechanical
chemical_list: D016328:NF-kappa B; D058486:Receptors, Purinergic P2X7