Neuroprotection by osteopontin in stroke.
Osteopontin (OPN) is a secreted extracellular phosphoprotein involved in diverse biologic functions, including inflammation, cell migration, and antiapoptotic processes. Here we investigate the neuroprotective potential of OPN to reduce cell death using both in vitro and in vivo models of ischemia. We show that incubation of cortical neuron cultures with OPN protects against cell death from oxygen and glucose deprivation. The effect of OPN depends on the Arg-Gly-Asp (RGD)-containing motif as the protective effect of OPN in vitro was blocked by an RGD-containing hexapeptide, which prevents integrin receptors binding to their ligands. Osteopontin treatment of cortical neuron cultures caused an increase in Akt and p42/p44 MAPK phosphorylation, which is consistent with OPN-inducing neuroprotection via the activation of these protein kinases. Indeed, the protective effect of OPN was reduced by inhibiting the activation of Akt and p42/p44 MAPK using LY294002 and U0126, respectively. The protective effect of OPN was also blocked by the protein synthesis inhibitor cycloheximide, suggesting that the neuroprotective effect of OPN required new protein synthesis. Finally, intracerebral ventricular administration of OPN caused a marked reduction in infarct size after transient middle cerebral artery occlusion in a murine stroke model. These data suggest that OPN is a potent neuroprotectant against ischemic injury.
Meller
Robert
R
Robert S. Dow Neurobiology Laboratories, Legacy Research, Portland, Oregon 97232, USA. rmeller@downeurobiology.org
Stevens
Susan L
SL
Minami
Manabu
M
Cameron
Jennifer A
JA
King
Sonya
S
Rosenzweig
Holly
H
Doyle
Kristian
K
Lessov
Nikola S
NS
Simon
Roger P
RP
Stenzel-Poore
Mary P
MP
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000187:drug effects* / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology / Q000517:prevention & control*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D006801:Humans; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D018696:Neuroprotective Agents / Q000737:chemistry / Q000494:pharmacology*; D009842:Oligopeptides; D053495:Osteopontin; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D012795:Sialoglycoproteins / Q000737:chemistry / Q000494:pharmacology*; D020521:Stroke / Q000150:complications / Q000188:drug therapy* / Q000473:pathology
D018696:Neuroprotective Agents; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; D011518:Proto-Oncogene Proteins; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; C506897:Spp1 protein, rat; D053495:Osteopontin; C047981:arginyl-glycyl-aspartic acid; D003513:Cycloheximide; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3