PPARGC1A and Huntington disease: In addition, a decreased expression of transducer of regulated CREB-binding protein 1 (TORC1), an activator of CREB-mediated PGC-1α expression, has been found in post mortem HD striatum, in transgenic HD mice, and in an in vitro HD model, which may contribute to the downregulation of PGC-1α expression in HD [160], whereas others suggest that PGC-1α repression may be secondary to the downregulation of PPARγ in HD [159].