TY - JOUR
T1 - Over-expression of an inactive mutant cathepsin D increases endogenous alpha-synuclein and cathepsin B activity in SH-SY5Y cells
AU - Crabtree, Donna
AU - Dodson, Matthew
AU - Ouyang, Xiaosen
AU - Boyer-Guittaut, Michaël
AU - Liang, Qiuli
AU - Ballestas, Mary E.
AU - Fineberg, Naomi
AU - Zhang, Jianhua
PY - 2014/3
Y1 - 2014/3
N2 - Parkinson's disease is a neurodegenerative movement disorder. The histopathology of Parkinson's disease comprises proteinaceous inclusions known as Lewy bodies, which contains aggregated α-synuclein. Cathepsin D (CD) is a lysosomal protease previously demonstrated to cleave α-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 α-synuclein degradation, as evidenced by the accumulation of endogenous α-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 α-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 α-synuclein accumulation as a therapeutic strategy against development of synucleinopathy.
AB - Parkinson's disease is a neurodegenerative movement disorder. The histopathology of Parkinson's disease comprises proteinaceous inclusions known as Lewy bodies, which contains aggregated α-synuclein. Cathepsin D (CD) is a lysosomal protease previously demonstrated to cleave α-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 α-synuclein degradation, as evidenced by the accumulation of endogenous α-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 α-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 α-synuclein accumulation as a therapeutic strategy against development of synucleinopathy.
KW - autophagy
KW - cathepsin D
KW - lysosome
KW - α-synuclein
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U2 - 10.1111/jnc.12497
DO - 10.1111/jnc.12497
M3 - Article
C2 - 24138030
AN - SCOPUS:84895920556
SN - 0022-3042
VL - 128
SP - 950
EP - 961
JO - Journal of neurochemistry
JF - Journal of neurochemistry
IS - 6
ER -