title: Rpn10-mediated degradation of ubiquitinated proteins is essential for mouse development.
abstract: Rpn10 is a subunit of the 26S proteasome that recognizes polyubiquitinated proteins. The importance of Rpn10 in ubiquitin-mediated proteolysis is debatable, since a deficiency of Rpn10 causes different phenotypes in different organisms. To date, the role of mammalian Rpn10 has not been examined genetically. Moreover, vertebrates have five splice variants of Rpn10 whose expressions are developmentally regulated, but their biological significance is not understood. To address these issues, we generated three kinds of Rpn10 mutant mice. Rpn10 knockout resulted in early-embryonic lethality, demonstrating the essential role of Rpn10 in mouse development. Rpn10a knock-in mice, which exclusively expressed the constitutive type of Rpn10 and did not express vertebrate-specific variants, grew normally, indicating that Rpn10 diversity is not essential for conventional development. Mice expressing the N-terminal portion of Rpn10, which contained a von Willebrand factor A (VWA) domain but lacked ubiquitin-interacting motifs (Rpn10DeltaUIM), also exhibited embryonic lethality, suggesting the important contribution of UIM domains to viability, but survived longer than Rpn10-null mice, consistent with a "facilitator" function of the VWA domain. Biochemical analysis of the Rpn10DeltaUIM liver showed specific impairment of degradation of ubiquitinated proteins. Our results demonstrate that Rpn10-mediated degradation of ubiquitinated proteins, catalyzed by UIMs, is indispensable for mammalian life.
authors.affiliation: Laboratory of Frontier Science, Core Technology and Research Center, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Hamazaki
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Sasaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawahara
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hisanaga
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Shigeo
authors.initials: S
authors.lastname: Murata
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D018390:Gene Targeting; D008099:Liver / Q000378:metabolism; D051379:Mice / Q000196:embryology* / Q000254:growth & development* / Q000378:metabolism; D018345:Mice, Knockout; D025821:Polyubiquitin / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins; D054875:Ubiquitination
chemical_list: D002352:Carrier Proteins; D021122:Protein Subunits; C490781:Psmd4 protein, mouse; D016601:RNA-Binding Proteins; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease