Spastin recovery in hereditary spastic paraplegia by preventing neddylation-dependent degradation

Francesca Sardina, Alessandra Pisciottani, Manuela Ferrara, Davide Valente, Marialuisa Casella, Marco Crescenzi, Angelo Peschiaroli, Carlo Casali, Silvia Soddu, Andrew J Grierson, Cinzia Rinaldo
2020 Life Science Alliance  
Hereditary Spastic Paraplegia (HSP) is a neurodegenerative disease most commonly caused by autosomal dominant mutations in the SPG4 gene encoding the microtubule-severing protein spastin. We hypothesise that SPG4-HSP is attributable to reduced spastin function because of haploinsufficiency; thus, therapeutic approaches which elevate levels of the wild-type spastin allele may be an effective therapy. However, until now, how spastin levels are regulated is largely unknown. Here, we show that the
more » ... inase HIPK2 regulates spastin protein levels in proliferating cells, in differentiated neurons and in vivo. Our work reveals that HIPK2-mediated phosphorylation of spastin at S268 inhibits spastin K48-poly-ubiquitination at K554 and prevents its neddylation-dependent proteasomal degradation. In a spastin RNAi neuronal cell model, overexpression of HIPK2, or inhibition of neddylation, restores spastin levels and rescues neurite defects. Notably, we demonstrate that spastin levels can be restored pharmacologically by inhibiting its neddylation-mediated degradation in neurons derived from a spastin mouse model of HSP and in patient-derived cells, thus revealing novel therapeutic targets for the treatment of SPG4-HSP.
doi:10.26508/lsa.202000799 pmid:33106322 fatcat:7nl4bpwq3ra3bl6rlvro3n32xm