Over-expression of an inactive mutant cathepsin D increases endogenous alpha-synuclein and cathepsin B activity in SH-SY5Y cells.
Fiche publication
Date publication
mars 2014
Auteurs
Membres identifiés du Cancéropôle Est :
Pr GUITTAUT Michaël
Tous les auteurs :
Crabtree D, Dodson M, Ouyang X, Boyer-Guittaut M, Liang Q, Ballestas ME, Fineberg N, Zhang J
Lien Pubmed
Résumé
Parkinson's disease is a neurodegenerative movement disorder. The histopathology of Parkinson's disease comprises proteinaceous inclusions known as Lewy bodies, which contains aggregated alpha-synuclein. Cathepsin D (CD) is a lysosomal protease previously demonstrated to cleave alpha-synuclein and decrease its toxicity in both cell lines and mouse brains in vivo. Here, we show that pharmacological inhibition of CD, or introduction of catalytically inactive mutant CD, resulted in decreased CD activity and increased cathepsin B activity, suggesting a possible compensatory response to inhibition of CD activity. However, this increased cathepsin B activity was not sufficient to maintain alpha-synuclein degradation, as evidenced by the accumulation of endogenous alpha-synuclein. Interestingly, the levels of LC3, LAMP1, and LAMP2, proteins involved in autophagy-lysosomal activities, as well as total lysosomal mass as assessed by LysoTracker flow cytometry, were unchanged. Neither autophagic flux nor proteasomal activities differs between cells over-expressing wild-type versus mutant CD. These observations point to a critical regulatory role for that endogenous CD activity in dopaminergic cells in alpha-synuclein homeostasis which cannot be compensated for by increased Cathepsin B. These data support the potential need to enhance CD function in order to attenuate alpha-synuclein accumulation as a therapeutic strategy against development of synucleinopathy.
Référence
J Neurochem. 2014 Mar;128(6):950-61