We have recently reported that thiazolidinediones induce PGC-1α gene transcription in adipose
Amuvatinib through a PPRE capable of binding PPARγ[14] (see Fig. 2A). In order to establish the transcriptional responsiveness of the PGC-1α gene to PPARδ activation, transient transfection assays were performed. Transcriptional activity driven by the 2 kb 5′ non-coding region of the mouse PGC-1α gene was induced by the PPARδ activator GW501516 (Fig. 2B). Cotransfection of a PPARα expression vector and/or exposure to the PPARα-selective activation mediated by 10 μM Wy14,643 had no effect, in agreement with results above on endogenous PGC-1α gene regulation. In contrast, PPARδ cotransfection and exposure to the selective PPARδ ligand elicited a significant induction of the PGC-1α gene promoter activity. Parallel assays were performed using a mutated version of the promoter construct in which the PPRE has been modified to impair PPAR binding and results indicated a severe reduction in PPARδ-dependent responsiveness. EMSA assays indicated that the PPRE in the PGC-1α gene was capable of binding PPARδ, but also PPARα, in vitro ( Fig. 2C). This indicates that the selectivity for different PPAR subtypes in the functional responsiveness of the PGC-1α gene is not mediated by a capacity of the PPRE DNA
element to differentially bind the PPAR subtypes.
