title: ASK1 negatively regulates the 26 S proteasome.
abstract: The 26 S proteasome, composed of the 20 S core and 19 S regulatory particle, plays a central role in ubiquitin-dependent proteolysis. Disruption of this process contributes to the pathogenesis of the various diseases; however, the mechanisms underlying the regulation of 26 S proteasome activity remain elusive. Here, cell culture experiments and in vitro assays demonstrated that apoptosis signal-regulating kinase 1 (ASK1), a member of the MAPK kinase kinase family, negatively regulated 26 S proteasome activity. Immunoprecipitation/Western blot analyses revealed that ASK1 did not interact with 20 S catalytic core but did interact with ATPases making up the 19 S particle, which is responsible for recognizing polyubiquitinated proteins, unfolding them, and translocating them into the 20 S catalytic core in an ATP-dependent process. Importantly, ASK1 phosphorylated Rpt5, an AAA ATPase of the 19 S proteasome, and inhibited its ATPase activity, an effect that may underlie the ability of ASK1 to inhibit 26 S proteasome activity. The current findings point to a novel role for ASK1 in the regulation of 26 S proteasome and offer new strategies for treating human diseases caused by proteasome malfunction.
authors.affiliation: Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Um
authors.forename: Eunju
authors.initials: E
authors.lastname: Im
authors.forename: Joongkyu
authors.initials: J
authors.lastname: Park
authors.forename: Yohan
authors.initials: Y
authors.lastname: Oh
authors.forename: Boram
authors.initials: B
authors.lastname: Min
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Jong Bok
authors.initials: JB
authors.lastname: Yoon
authors.forename: Kwang Chul
authors.initials: KC
authors.lastname: Chung
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005910:Glioma / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054875:Ubiquitination
chemical_list: D021122:Protein Subunits; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D048848:MAP Kinase Kinase Kinase 5; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease