Herpesvirus-associated ubiquitin-specific protease (HAUSP) modulates peroxisome proliferator-activated receptor γ (PPARγ) stability through its deubiquitinating activity.
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 Lys(462) 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.
From the Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong, Chongnogu, Seoul 110-744.
Kyeong Won
KW
Lee
Jin Gu
JG
Cho
Chul Min
CM
Kim
A Young
AY
Kang
Min
M
Kim
Byung Yong
BY
Ahn
Sung Soo
SS
Chung
Key-Hwan
KH
Lim
Kwang-Hyun
KH
Baek
Jong-Hyuk
JH
Sung
Kyong Soo
KS
Park
Sang Gyu
SG
Park
D000256:Adenoviridae; D019943:Amino Acid Substitution; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D001786:Blood Glucose / Q000235:genetics / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D005227:Fatty Acids / Q000097:blood / Q000235:genetics; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007192:Indenes / Q000494:pharmacology; D008297:Male; D051379:Mice; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D011719:Pyrazines / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D014161:Transduction, Genetic; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000076084:Ubiquitin-Specific Peptidase 7; D064570:Ubiquitin-Specific Proteases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects / Q000502:physiology*
D001786:Blood Glucose; D005227:Fatty Acids; C546441:HBX 41,108; D007192:Indenes; D047495:PPAR gamma; D011719:Pyrazines; C464569:USP7 protein, human; D043222:Ubiquitin Thiolesterase; D000076084:Ubiquitin-Specific Peptidase 7; D064570:Ubiquitin-Specific Proteases; C579190:Usp7 protein, mouse
Deubiquitination; Diabetes; Glucose Metabolism; Metabolism; Peroxisome Proliferator-activated receptor (PPAR)