Regulation of ubiquitin and 26S proteasome mediated by phenolic compounds during oxidative stress.
Little attention has been devoted to studying the roles of natural antioxidants in the ubiquitin-proteasome pathway during oxidative stress. We demonstrated that a time course revealed that the reassociation of the 19S regulators with the 20S proteasomes occurred automatically and rapidly to reconstitute the 26S proteasomes, with up to 80% completion, within 5 min after H2O2 treatment. Ubiquitin, methyl gallate and tannic acid are able to prevent H2O2 from inhibiting the 26S activity. We further show that the level of the ubiquitin, S5a and 20S core subunits decreased within 30 min and increased after 24 h of H2O2 treatment in Hep-2 cells. Phenolic compounds not only inhibited the 26S activity but also decreased the USP47 levels, which reduce the DNA damage repair rate during oxidative stress; in addition, the presence of DNA fragments, procaspase-3 and a decreased poly (ADP-ribose) polymerase also appeared as a result of the above conditions. Ubiquitin could serve as a protective substrate in H2O2 and phenolic compound-treated Hep-2 cells. Methyl gallate and tannic acid, as prooxidants, can attenuate the apoptotic response resulting from long-term oxidative stress. Collectively, these data demonstrate an important role for phenolic compounds in regulating the 26S proteasome and ubiquitin during oxidative stress.
Department of Biological Sciences and Technology, National University of Tainan, Tainan 70005, Taiwan. Electronic address: tsuiling@mail.nutn.edu.tw.
Tsui-Ling
TL
Chang
Shu-Wei
SW
Lin
Shuo-lun
SL
Wu
Chu-Mei
CM
Hong
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D053938:DNA Fragmentation / Q000187:drug effects; D004610:Ellagic Acid / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D013634:Tannins / Q000494:pharmacology; D025801:Ubiquitin / Q000378:metabolism*
D000975:Antioxidants; D013634:Tannins; D025801:Ubiquitin; D004610:Ellagic Acid; C052082:methyl gallate; D005707:Gallic Acid; D006861:Hydrogen Peroxide; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
26S proteasome inhibitor; Ellagic acid; Gallic acid; Methyl gallate; Oxidative stress; Tannic acid