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_5 label "Selventa" provenance.
large_corpus.bel title "BEL Framework Large Corpus Document" provenance.
large_corpus.bel description "Approximately 61,000 statements." provenance.
large_corpus.bel version "1.4" provenance.
large_corpus.bel authoredBy _5 provenance.
assertion wasDerivedFrom large_corpus.bel provenance.
assertion wasDerivedFrom _4 provenance.
assertion hadPrimarySource 12764228 provenance.
_4 wasQuotedFrom 12764228 provenance.
_4 value "The strongest effect was observed when MEF2C or MEF2D was expressed with both CnA and PGC-1-alpha (Fig. 2B). No effect was found by the coexpression of any of these proteins with NFAT. In contrast to the data for CnA, the effect of CaMKIV on this promoter was not changed by the addition of MEF2s or PGC-1-alpha (data not shown). Together, these data strongly suggest that the major effect of CaMKIV on PGC-1-alpha expression is via CREB acting on the PGC-1-alpha promoter, whereas CnA is able to increase further the activity of MEF2s to stimulate transcription driven by the PGC-1-alpha promoter. Computer-aided sequence analysis of the mouse PGC-1-alpha 5 flanking region revealed a potential MEF2-binding site between 1,464 and 1,447 (Fig. 3A) and a possible NFAT-binding site between 1,547 and 1,536 (25). Similar configurations of adjacent MEF2- and NFAT-binding sites previously have been described in several muscle fiber type I-specific promoters (9). We next examined whether mutations of this MEF2 site affects MEF2 activity on the PGC-1-alpha promoter. The mutated 2-kb promoter (called MEF2; see Fig. 3A) is no longer able to mediate MEF2C or MEF2D induction alone, when activated by CnA or coactivated by PGC-1-alpha , suggesting that this site is responsible for the MEF2 action (Fig. 3B). Moreover, electrophoretic mobility-shift assays revealed binding of MEF2C to this MEF-binding site but not the mutated MEF site in the PGC-1-alpha promoter (Fig. 3C). The identity of the MEF2C-DNA complex was confirmed by using an anti-MEF2 antibody that leads to a supershift of the DNA-protein complex. To confirm that the coactivation of MEF2C by PGC-1-alpha observed in reporter gene assays (Fig. 3B) was linked to direct binding of these two proteins, we tested whether PGC-1-alpha directly interacts with MEF2C on this MEF-binding site. Increasing amounts of PGC-1-alpha protein (amino acids 31-797) decreased the mobility of the complex containing MEF2C bound to the MEF-binding site, as visualized by a supershift in electrophoretic mobility-shift assays (Fig. 3D). As a control, PGC-1-alpha protein that lacks the MEF2C-interaction domain (amino acids 1-180; see ref. 7) was not able to bind to MEF2C. Inclusion of an MEF2- specific antibody was able to supershift further the protein-DNA complex containing MEF2C, PGC-1-alpha , and the MEF2-binding site (Fig. 3E). Neither a shift nor a supershift could be obtained when using the mutated MEF site. These results indicate that MEF2s bind to the PGC-1-alpha promoter and that PGC-1-alpha coactivates MEF2 proteins on the PGC-1-alpha promoter by a direct protein-protein interaction. The ability of PGC-1-alpha protein to stimulate the PGC-1-alpha promoter via coactivation of the MEF2 proteins implies a potential autoregulatory loop. As shown in the model illustrated in Fig. 4A, exercise or increased motor neuron activity would result in the activation of CaMKIV and CnA." provenance.