Sulforaphane Activates Heat Shock Response and Enhances Proteasome Activity through Up-regulation of Hsp27

• Published in: The Journal of biological chemistry Vol. 285; no. 46; pp. 35528 - 35536
• Main Authors: Gan, Nanqin, Wu, Yu-Chieh, Brunet, Mathilde, Garrido, Carmen, Chung, Fung-Lung, Dai, Chengkai, Mi, Lixin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.11.2010; American Society for Biochemistry and Molecular Biology
• Subjects: Aging; Animals; Anticarcinogenic Agents - pharmacology; Cell Line, Tumor; Chlorocebus aethiops; COS Cells; Cysteine Proteinase Inhibitors - pharmacology; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Dose-Response Relationship, Drug; Enzyme Activation - drug effects; Gene Regulation; Heat Shock Protein; Heat Shock Transcription Factors; Heat-Shock Response - drug effects; HeLa Cells; Hot Temperature; HSF1; Hsp27; HSP27 Heat-Shock Proteins - genetics; HSP27 Heat-Shock Proteins - metabolism; Humans; Immunoblotting; Isothiocyanates; Leupeptins - pharmacology; Neurodegeneration; Proteasome; Proteasome Endopeptidase Complex - metabolism; Proteasome Inhibitors; Protein Biosynthesis - drug effects; Protein Synthesis and Degradation; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Sulforaphane; Thiocyanates - pharmacology; Transcription Factors - genetics; Transcription Factors - metabolism; Up-Regulation - drug effects; Gene Regulation; Neurodegeneration; Hsp27; Sulforaphane; HSF1; Aging; Heat Shock Protein; Proteasome
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.152686

It is conceivable that stimulating proteasome activity for rapid removal of misfolded and oxidized proteins is a promising strategy to prevent and alleviate aging-related diseases. Sulforaphane (SFN), an effective cancer preventive agent derived from cruciferous vegetables, has been shown to enhance proteasome activities in mammalian cells and to reduce the level of oxidized proteins and amyloid β-induced cytotoxicity. Here, we report that SFN activates heat shock transcription factor 1-mediated heat shock response. Specifically, SFN-induced expression of heat shock protein 27 (Hsp27) underlies SFN-stimulated proteasome activity. SFN-induced proteasome activity was significantly enhanced in Hsp27-overexpressing cells but absent in Hsp27-silenced cells. The role of Hsp27 in regulating proteasome activity was further confirmed in isogenic REG cells, in which SFN-induced proteasome activation was only observed in cells stably overexpressing Hsp27, but not in the Hsp27-free parental cells. Finally, we demonstrated that phosphorylation of Hsp27 is irrelevant to SFN-induced proteasome activation. This study provides a novel mechanism underlying SFN-induced proteasome activity. This is the first report to show that heat shock response by SFN, in addition to the antioxidant response mediated by the Keap1-Nrf2 pathway, may contribute to cytoprotection.