title: Rapid degradation of Bim by the ubiquitin-proteasome pathway mediates short-term ischemic tolerance in cultured neurons.
abstract: A previous exposure to a non-harmful ischemic insult (preconditioning) protects the brain against subsequent harmful ischemia (ischemic tolerance). In contrast to delayed gene-mediated ischemic tolerance, little is known about the molecular mechanisms that regulate rapid ischemic tolerance, which occurs within 1 h following preconditioning. Here we have investigated the degradation of the pro-apoptotic Bcl-2 family member Bim as a mechanism of rapid ischemic tolerance. Bim protein levels were reduced 1 h following preconditioning and occurred concurrent with an increase in Bim ubiquitination. Ubiquitinated proteins are degraded by the proteasome, and inhibition of the proteasome with MG132 (a proteasome inhibitor) prevented Bim degradation and blocked rapid ischemic tolerance. Inhibition of p42/p44 mitogen-activated protein kinase activation by U0126 reduced Bim ubiquitination and Bim degradation and blocked rapid ischemic tolerance. Finally, inhibition of Bim expression using antisense oligonucleotides also reduced cell death following ischemic challenge. Our results suggest that following preconditioning ischemia, Bim is rapidly degraded by the ubiquitin-proteasome system, resulting in rapid ischemic tolerance. This suggests that the rapid degradation of cell death-promoting proteins by the ubiquitin-proteasome pathway may represent a novel therapeutic strategy to reduce cell damage following neuropathological insults, e.g. stroke.
authors.affiliation: Robert S. Dow Neurobiology Laboratories, Legacy Clinical Research and Technology Center, 1225 NE 2nd Avenue, Portland, OR 97232, USA. meller@downeurobiology.org
authors.forename: Robert
authors.initials: R
authors.lastname: Meller
authors.forename: Jennifer Anastasia
authors.initials: JA
authors.lastname: Cameron
authors.forename: Daniel John
authors.initials: DJ
authors.lastname: Torrey
authors.forename: Corrin Erin
authors.initials: CE
authors.lastname: Clayton
authors.forename: Andrea Nicole
authors.initials: AN
authors.lastname: Ordonez
authors.forename: David Clifford
authors.initials: DC
authors.lastname: Henshall
authors.forename: Manabu
authors.initials: M
authors.lastname: Minami
authors.forename: Clara Kay
authors.initials: CK
authors.lastname: Schindler
authors.forename: Julie Anne
authors.initials: JA
authors.lastname: Saugstad
authors.forename: Roger Pancoast
authors.initials: RP
authors.lastname: Simon
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry* / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D002070:Butadienes / Q000494:pharmacology; D016923:Cell Death; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000737:chemistry; D015151:Immunoblotting; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007511:Ischemia / Q000473:pathology; D019194:Ischemic Preconditioning; D007976:Leupeptins / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D009570:Nitriles / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D010766:Phosphorylation; D011419:Propidium / Q000737:chemistry; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D025801:Ubiquitin / Q000737:chemistry*
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606778:Bcl2l11 protein, rat; D002070:Butadienes; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007976:Leupeptins; D008565:Membrane Proteins; D009570:Nitriles; D016376:Oligonucleotides, Antisense; D011518:Proto-Oncogene Proteins; C113580:U 0126; D025801:Ubiquitin; D011419:Propidium; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde