Aggregation and proteasome: the case of elongated polyglutamine aggregation in spinal and bulbar muscular atrophy.
Aggregates, a hallmark of most neurodegenerative diseases, may have different properties, and possibly different roles in neurodegeneration. We analysed ubiquitin-proteasome pathway functions during cytoplasmic aggregation in polyglutamine (polyQ) diseases, using a unique model of motor neuron disease, the SpinoBulbar Muscular Atrophy. The disease, which is linked to a polyQ tract elongation in the androgen receptor (ARpolyQ), has the interesting feature that ARpolyQ aggregation is triggered by the AR ligand, testosterone. Using immortalized motor neurons expressing ARpolyQ, we found that a proteasome reporter, YFPu, accumulated in absence of aggregates; testosterone treatment, which induced ARpolyQ aggregation, allowed the normal clearance of YFPu, suggesting that aggregation contributed to proteasome de-saturation, an effect not related to AR nuclear translocation. Using AR antagonists to modulate the kinetic of ARpolyQ aggregation, we demonstrated that aggregation, by removing the neurotoxic protein from the soluble compartment, protected the proteasome from an excess of misfolded protein to be processed.
Rusmini
Paola
P
Institute of Endocrinology, Center of Excellence on Neurodegenerative Diseases, University of Milan, Milano, Italy.
Sau
Daniela
D
Crippa
Valeria
V
Palazzolo
Isabella
I
Simonini
Francesca
F
Onesto
Elisa
E
Martini
Luciano
L
Poletti
Angelo
A
D000818:Animals; D002461:Cell Line, Transformed; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D009134:Muscular Atrophy, Spinal / Q000235:genetics*; D009154:Mutation; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013739:Testosterone / Q000494:pharmacology; D014162:Transfection / Q000379:methods; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D043743:Ubiquitin-Protein Ligase Complexes
D008164:Luminescent Proteins; D010455:Peptides; D012333:RNA, Messenger; D011944:Receptors, Androgen; C097188:polyglutamine; D013739:Testosterone; D043743:Ubiquitin-Protein Ligase Complexes; D046988:Proteasome Endopeptidase Complex