Rapid degradation of Bim by the ubiquitin-proteasome pathway mediates short-term ischemic tolerance in cultured neurons.
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.
Meller
Robert
R
Robert S. Dow Neurobiology Laboratories, Legacy Clinical Research and Technology Center, 1225 NE 2nd Avenue, Portland, OR 97232, USA. meller@downeurobiology.org
Cameron
Jennifer Anastasia
JA
Torrey
Daniel John
DJ
Clayton
Corrin Erin
CE
Ordonez
Andrea Nicole
AN
Henshall
David Clifford
DC
Minami
Manabu
M
Schindler
Clara Kay
CK
Saugstad
Julie Anne
JA
Simon
Roger Pancoast
RP
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*
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