PIAS3 and Huntington disease: SUMOylation was also deregulated in the R6/2 mouse model of HD: both Sumo1 and Sumo2 mRNA increased in the striatum at a late stage of the disease; the same pattern was observed in the mRNA expression of enzymes (Senp1, Senp6, Pias3 and Pias4) involved in this pathway (O'Rourke et al., 2013).