Herpesvirus-associated Ubiquitin-specific Protease (HAUSP) Modulates Peroxisome Proliferator-activated Receptor γ (PPARγ) Stability through Its Deubiquitinating Activity

• Published in: The Journal of biological chemistry 2013-11, Vol.288 (46), p.32886-32896
• Main Authors: Lee, Kyeong Won, Cho, Jin Gu, Kim, Chul Min, Kang, A Young, Kim, Min, Ahn, Byung Yong, Chung, Sung Soo, Lim, Key-Hwan, Baek, Kwang-Hyun, Sung, Jong-Hyuk, Park, Kyong Soo, Park, Sang Gyu
• Format: Article
• Language: English
• Subjects: Adenoviridae; Amino Acid Substitution; Animals; Biological Transport, Active - drug effects; Biological Transport, Active - physiology; Blood Glucose - genetics; Blood Glucose - metabolism; Chlorocebus aethiops; COS Cells; Deubiquitination; Diabetes; Fatty Acids - blood; Fatty Acids - genetics; Gene Knockdown Techniques; Glucose Metabolism; HeLa Cells; Hep G2 Cells; Humans; Indenes - pharmacology; Male; Metabolism; Mice; Mutagenesis, Site-Directed; Mutation, Missense; Peroxisome Proliferator-activated receptor (PPAR); PPAR gamma - genetics; PPAR gamma - metabolism; Protein Stability; Pyrazines - pharmacology; Transcription, Genetic - drug effects; Transcription, Genetic - physiology; Transduction, Genetic; Ubiquitin Thiolesterase - antagonists & inhibitors; Ubiquitin Thiolesterase - genetics; Ubiquitin Thiolesterase - metabolism; Ubiquitin-Specific Peptidase 7; Ubiquitin-Specific Proteases - genetics; Ubiquitin-Specific Proteases - metabolism; Ubiquitination - drug effects; Ubiquitination - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.496331

The peroxisome proliferator-activated receptor γ (PPARγ) is a central regulator of adipogenesis and modulates glucose and lipid metabolism. In this study, herpesvirus-associated ubiquitin-specific protease (HAUSP) was isolated as a binding partner of PPARγ. Both endogenous and exogenous PPARγ associated with HAUSP in co-immunoprecipitation analysis. HAUSP, but not the catalytically inactive HAUSP C223S mutant, increased the stability of both endogenous and exogenous PPARγ through its deubiquitinating activity. Site-directed mutagenesis experiments showed that the Lys462 residue of PPARγ is critical for ubiquitination. HBX 41,108, a specific inhibitor of HAUSP, abolished the increase in PPARγ stability induced by HAUSP. In addition, knockdown of endogenous HAUSP using siRNA decreased PPARγ protein levels. HAUSP enhanced the transcriptional activity of both exogenous and endogenous PPARγ in luciferase activity assays. Quantitative RT-PCR analysis showed that HAUSP increased the transcript levels of PPARγ target genes in HepG2 cells, resulting in the enhanced uptake of glucose and fatty acids, and vice versa, upon siRNA knockdown of HAUSP. In vivo analysis using adenoviruses confirmed that HAUSP, but not the HAUSP C223S mutant, decreased blood glucose and triglyceride levels, which are associated with the increased expression of endogenous PPARγ and lipid accumulation in the liver. Our results demonstrate that the stability and activity of PPARγ are modulated by the deubiquitinating activity of HAUSP, which may be a target for the development of anti-diabetic drugs. Background: The increase of PPARγ stability could contribute to lower blood glucose levels. Results: PPARγ stability is increased by the deubiquitinating activity of HAUSP. Conclusion: HAUSP overexpression could decrease blood glucose and triglyceride levels at least in part by deubiquitinating and stabilizing PPARγ in the liver. Significance: Identification of a novel enzyme (HAUSP) that deubiquitinates and stabilizes PPARγ and its potential role in liver glucose and lipid metabolism are significant.