title: An endogenous electrophile that modulates the regulatory mechanism of protein turnover: inhibitory effects of 15-deoxy-Delta 12,14-prostaglandin J2 on proteasome.
abstract: Prostaglandin D(2) (PGD(2)), a major cyclooxygenase product in a variety of tissues and cells, readily undergoes dehydration to yield electrophilic PGs, such as 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)). We have previously shown that 15d-PGJ(2) potently induces apoptosis of SH-SY5Y human neuroblastoma cells via accumulation of the tumor suppressor gene product p53. In the study presented here, we investigated the molecular mechanisms involved in the 15d-PGJ(2)-induced accumulation of p53. It was observed that 15d-PGJ(2) potently induced p53 protein expression but scarcely induced p53 gene expression. In addition, exposure of the cells to 15d-PGJ(2) resulted in an accumulation of ubiquitinated proteins and in a significant inhibition of proteasome activities, suggesting that 15d-PGJ(2) acted on the ubiquitin-proteasome pathway, a regulatory mechanism of p53 turnover. The effects of 15d-PGJ(2) on the protein turnover were attributed to its electrophilic feature, based on the observations that (i) the reduction of the double bond in the cyclopentenone ring of 15d-PGJ(2) virtually abolished the effects on protein turnover, (ii) overexpression of an endogenous redox regulator, thioredoxin 1, significantly retarded the inhibition of proteasome activities and accumulations of p53 and ubiquitinated proteins induced by 15d-PGJ(2), and (iii) treatment of SH-SY5Y cells with biotinylated 15d-PGJ(2) indeed resulted in the formation of a 15d-PGJ(2)-proteasome conjugate. These data suggest that the modulation of proteasome activity may be involved in the mechanism responsible for the accumulation of p53 and subsequent induction of apoptotic cell death induced by 15d-PGJ(2).
authors.affiliation: Laboratory of Food and Biodynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shibata
authors.forename: Takaaki
authors.initials: T
authors.lastname: Yamada
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kondo
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Tanahashi
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Hajime
authors.initials: H
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masutani
authors.forename: Junji
authors.initials: J
authors.lastname: Yodoi
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001665:Binding Sites; D045744:Cell Line, Tumor; D003517:Cyclopentanes / Q000737:chemistry; D003546:Cysteine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000737:chemistry*; D006801:Humans; D007155:Immunologic Factors / Q000737:chemistry* / Q000502:physiology*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D013329:Structure-Activity Relationship; D013879:Thioredoxins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism
chemical_list: C097240:15-deoxy-delta(12,14)-prostaglandin J2; D003517:Cyclopentanes; D004791:Enzyme Inhibitors; D007155:Immunologic Factors; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D011506:Proteins; D016159:Tumor Suppressor Protein p53; D013879:Thioredoxins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C013905:cyclopentenone; D015230:Prostaglandin D2