5. Gossypol acetate reduced mHTT level and rescued HD-relevant
phenotypes in vivo
Having demonstrated that gossypol acetate protected HD neurons by
inducing autophagy-mediated degradation of mHTT, we assessed whether
gossypol acetate had beneficial effect in vivo onDrosophila HD models expressing HTT-16Q, HTT-128Q, HTTexon1-25Q
or HTTexon1-72Q fragments (33 ). As shown by HTRF assays, gossypol
acetate significantly reduced mHTT level in the HTT-128Q model as well
as in HTTexon1-72Q model without reducing wtHTT level in transgenicDrosophila model with HTT-16Q or HTTexon1-25Q (Fig. 4A). In
HTT-128Q flies,feeding with food containing 10 μM gossypol acetate
significantly rescued the climbing deficits in Huntington’s disease
flies (Fig. 4B). Flies expressing HTTexon1-72Q exhibited similar
climbing deficits and a shorter lifespan and were also rescued by
feeding the flies with gossypol acetate, while little effects after GA
treatment were observed in flies expressing wtHTT (HTT-16Q or
HTTexon1-25Q) (Fig. 4C, 4D). The results suggested that gossypol acetate
was effective in reducing mHTT level and rescuing HD phenotypes inDrosophila models.
To further confirm its neuronal protective effects and therapeutic
potential, we examined the effects of gossypol acetate in the HD
knock-in mouse model expressing endogenous mHTT proteins with 140Q
(HdhQ140/Q140). Consistent with previous reports, we
observed several motor function-related deficits in the homozygous HD
(HdhQ140/Q140) mice (Fig. 5A-D) , including decrease
of the activity in the rearing test, deficits in the open-field tests,
and reduced latency to fall in the rotarod tests. Intraperitoneal
injection of gossypol acetate significantly rescued all these behavioral
phenotypes (Figure 5A-C). Consistently, homozygous HD mice treated with
gossypol acetate showed significantly reduced mHTT levels in the cortex
and striata (Fig. 5D). All results confirmed that gossypol acetate
treatment reduced mHTT levels in vivo and rescued HD relevant
phenotypes.