Fig. 5.

Model showing the regulation of PPARα by metabolism and PAR bZip transcription factors. (Left) Under normal diet conditions, the expression of ACOTs are under the control of circadian PAR bZip transcription factors. These transcription factors thus control the release of free FA from acyl-CoA thioesters, and the free FAs stimulate PPARα activity. The activated PPARα then stimulates transcription of Acot and Lpl, and in a feed-forward loop reinforces its own expression and activity. (Right) Under a fat-free diet, all free FAs are derived from the de novo synthesis pathway. Under these conditions, PPARα activity is not dependent on PAR bZip transcription factors.