Control of peroxisome proliferator-activated receptor gamma2 stability and activity by SUMOylation.
OBJECTIVE
To determine whether small ubiquitin-related modifier (SUMO)ylation of lysine 107 plays a role in regulating the activity of peroxisome proliferator-activated receptor gamma (PPARgamma).


METHODS
Transient expression of wild-type and K107R-PPARgamma2 in the NIH 3T3 fibroblast cell line was carried out in conjunction with half-life studies, luciferase activity assays, and indirect immunofluorescence localization studies. Additional in vitro analysis was carried out using recombinant SUMOylation pathway proteins along with in vitro transcribed and translated wild-type or K107R-PPARgamma2 to examine the SUMO-1 modification state of wild-type and SUMO-deficient K107R-PPARgamma2.


RESULTS
While examining PPARgamma2 for potential ubiquitylation sites, we identified a strong consensus site for SUMO modification that contains lysine 107. In vitro, SUMOylation studies showed that lysine 107 of PPARgamma2 is a major SUMOylation site and that at least one other SUMOylation site is present in PPARgamma. In addition, our results demonstrated that SUMO-1 affects PPARgamma stability and transcriptional activity but not the nuclear localization of PPARgamma.


CONCLUSIONS
These results indicated that SUMOylation plays a role in regulating PPARgamma, both indirectly and directly by modification of lysine 107. Because PPARgamma is regulated in numerous animal models of obesity, understanding the covalent modifications of PPARgamma may enhance our understanding of the metabolic syndrome.
Floyd
Z Elizabeth
ZE
Louisiana State University, Department of Biological Sciences, Baton Rouge, LA 70803, USA.
Stephens
Jacqueline M
JM
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008239:Lysine / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D041681:NIH 3T3 Cells; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D025842:SUMO-1 Protein / Q000378:metabolism*; D045162:Thiazolidinediones / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection
D015853:Cysteine Proteinase Inhibitors; D007004:Hypoglycemic Agents; D007976:Leupeptins; D018160:Receptors, Cytoplasmic and Nuclear; D025842:SUMO-1 Protein; D045162:Thiazolidinediones; D014157:Transcription Factors; C089948:darglitazone; D008239:Lysine; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde