Article

A comparison of changes in proteasomal subunit expression in the substantia nigra in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy.

School of Health and Biomedical Sciences, King's College, London, UK.
Brain research (impact factor: 2.46). 02/2010; 1326:174-83. DOI:10.1016/j.brainres.2010.02.045 pp.174-83
Source: PubMed

ABSTRACT Dysfunction of the ubiquitin-proteasome system (UPS) occurs in dopaminergic neurones in the SN in PD and it is associated with Lewy body formation. However, it remains unknown whether this is specific to PD or whether it also occurs in multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) where nigral dopaminergic neurones also degenerate. In the present study, we investigated changes in the expression of proteasomal subunits in the SN in PD, MSA and PSP. Immunohistochemistry double staining showed that proteasome 20S-alpha4 and -alpha6, and 20S-beta3 and -beta5i subunits are colocalized with tyrosine hydroxylase (TH)-positive cells in the SN of control, PD, MSA and PSP brain. Semi-quantitative analysis showed a significant loss of 20S-alpha4 and -alpha6 subunits TH-positive cells in PD, MSA and PSP compared to control tissue. There was no change in the expression of 20S-beta3 and -beta5i subunits in any of the disease states. The expression of PA700-Rpt5 subunits was not changed in PSP or PD but was significantly increased in MSA compared to control SN. PA700-Rpn10 subunit was not colocalized with TH within dopamine cells but was co-expressed with glial fibrillary acid protein (GFAP) positive astrocytes in the SN of all groups. PA28-alpha immunoreactivity was low in TH positive neurones in control tissue and quantification was not possible. Qualitative analysis suggested a decrease in PD and no immunoreactivity was detected in MSA or PSP. The results show that changes in proteasomal structure occur in the SN in PD, MSA and PSP and that these are similar in nature suggesting that dysfunction of UPS is not specific to PD or to Lewy body formation.

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Keywords

-alpha6 subunits TH-positive cells
 
-beta5i subunits
 
control SN
 
control tissue
 
disease states
 
dopamine cells
 
dopaminergic neurones
 
glial fibrillary acid protein
 
Immunohistochemistry double staining
 
Lewy body formation
 
multiple system atrophy
 
nigral dopaminergic neurones
 
PA28-alpha immunoreactivity
 
PA700-Rpt5 subunits
 
proteasomal subunits
 
PSP brain
 
Qualitative analysis
 
TH positive neurones
 
TH)-positive cells
 
ubiquitin-proteasome system