Table 2.
Summary of ubiquitin and SUMO modification of PPAR coreceptor RXRα and coactivator PGC-1 α and the resulting effects on transcription
| PPAR Coreceptor/Coactivator | Post-translational Modification | Ubiquitin/SUMO Ligase (E3) Identified | Modification Type | Transcriptional Affect | Effect of Ligand | Cell Type | References |
|---|---|---|---|---|---|---|---|
| RXRα | Ubiquitination | SmSINA and RNF8 (E3 ligase?) Not determined | Polyubiquitination targets Schistosoma mansoni RXR homologues (RXR1, RXR2) for degradation RNF8 enhances RXRα activity independent of ubiquitination polyubiquitination | Not determined Inhibition of RXRα by promoting its degradation | Not determined 9-cis-retinoic acid enhances RXRα polyubiquitination | S. mansoni COS-7 Smooth muscle cells derived from human myometrium and leiomyoma | (21) |
| SUMOylation | SUSP1 (SENP6) SUMO protease (Removes SUMO) | K108 SUMO-1 | SUSP1 deSUMOylation of RXRα enhances its activity. | Not determined | HEK293 | (14) | |
| PGC-1α | Ubiquitination | Not determined | Poly-ubiquitination in nucleus (NH2-terminal pathway?) | Inhibition of PGC-1α by promoting its degradation | — | COS-7; HL-1 (cardiac muscle cell line) | (2, 74) |
| SUMOylation | PIAS1 and PIAS3 SUMOylates SUSP1 (SENP6) SUMO protease (Removes SUMO) | K183 SUMO-1 K183 SUMO-1 | SUMOylation of K183 enhances PGC-1α activity | — | COS-1; HeLa | (71) |
See main text for definition of abbreviations.