Assembly of the 26S Proteasome Is Regulated by Phosphorylation of the p45/Rpt6 ATPase Subunit

Satoh, Kaneo; Sasajima, Hitoshi; Nyoumura, Ken-ichi; Yokosawa, Hideyoshi; Sawada, Hitoshi

doi:10.1021/bi001815n

Cited by 123 publications

(100 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, phosphorylation of the 20 S proteasome ␣ subunit C8 substantially affects the stability of the 26 S proteasome (29). In addition, phosphorylation of Rpt6 promotes the association of the regulatory complex with the 20 S proteasome to form the 26 S proteasome (32). In contrast, the present study shows that ASK1 does not affect the assembly of the native 26 S proteasome.…”

Section: Discussioncontrasting

confidence: 52%

ASK1 Negatively Regulates the 26 S Proteasome

Park

et al. 2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

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.

show abstract

Section: Discussioncontrasting

confidence: 52%

ASK1 Negatively Regulates the 26 S Proteasome

Park

et al. 2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…36), and the phosphorylation of C8 by casein kinase 2 was suggested to increase the stability of the 26S proteasome (37). Satoh et al (38) suggested that dephosphorylation of proteasome structures elicits the dissociation of the 26S proteasome to the 20S proteasome and the regulatory complex. In addition, phosphorylation of several ATPase subunits of 26S in human lung cancer cell lines was found by two-dimensional gel analysis (39).…”

Section: Discussionmentioning

confidence: 99%

Epidermal Growth Factor Receptor vIII Expression in U87 Glioblastoma Cells Alters Their Proteasome Composition, Function, and Response to Irradiation

Kim

Brush

Watson

et al. 2008

Molecular Cancer Research

View full text Add to dashboard Cite

Little is known about the factors that influence the proteasome structures in cells and their activity, although this could be highly relevant to cancer therapy. We have previously shown that, within minutes, irradiation inhibits substrate degradation by the 26S proteasome in most cell types. Here, we report an exception in U87 glioblastoma cells transduced to express the epidermal growth factor receptor vIII (EGFRvIII) mutant (U87EGFRvIII), which does not respond to irradiation with 26S proteasome inhibition. This was assessed using either a fluorogenic substrate or a reporter gene, the ornithine decarboxylase degron fused to ZsGreen (cODCZsGreen), which targets the protein to the 26S proteasome. To elucidate whether this was due to alterations in proteasome composition, we used quantitative reverse transcription-PCR to quantify the constitutive (X, Y, Z) and inducible 20S subunits (Lmp7, Lmp2, Mecl1), and 11S (PA28A and B) and 19S components (PSMC1 and PSMD4). U87 and U87EGFRvIII significantly differed in expression of proteasome subunits, and in particular immunosubunits. Interestingly, 2 Gy irradiation of U87 increased subunit expression levels by 16% to 324% at 6 hours, with a coincident 30% decrease in levels of the proteasome substrate c-myc, whereas they changed little in U87EGFRvIII. Responses similar to 2 Gy were seen in U87 treated with a proteasome inhibitor, NPI0052, suggesting that proteasome inhibition induced replacement of subunits independent of the means of inhibition. Our data clearly indicate that the composition and function of the 26S proteasome can be changed by expression of the EGFRvIII. How this relates to the increased radioresistance associated with this cell line remains to be established. (Mol Cancer Res 2008;6(3):426 -34)

show abstract

“…There were prior indications that phosphorylation promotes 26S assembly (10,18) and that dephosphorylation of Rpt6 in purified proteasomes promoted their dissociation into 20S and 19S components by disrupting the interaction between Rpt6 and α2 (10). Conversely, phosphorylation by PKA appears to promote 26S in vitro and in vivo (18).…”

mentioning

confidence: 99%

“…During the past two decades, proteasome phosphorylation has often been reported, but it remains unclear whether such modifications actually perturb rates or selectivity of protein degradation. Various subunits have been shown to be phosphorylated in vivo including four of the seven α-subunits that comprise the outer rings of the 20S particle, α7, α3, α2, and α4 (3-7), and two of the six ATPases, Rpt6 (8)(9)(10)(11) and Rpt2 (12), that comprise a ring at the base of the 19S complex. Because these rings lie adjacent to each other, their interactions are very likely to be influenced by phosphorylation and dephosphorylation.…”

mentioning

confidence: 99%