Soluble expanded PABPN1 promotes cell death in oculopharyngeal muscular dystrophy.
Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disease caused by the expansion of a polyalanine repeat (GCG)(8-13) in exon 1 of the PABPN1 gene. Skeletal muscle fibers nuclei from OPMD patients contain insoluble polyalanine expanded PABPN1 (expPABPN1) nuclear aggregates that sequester different cellular components. Whether these aggregates are pathogenic, or the consequence of a molecular defense mechanism, remains controversial in the field of neurodegenerative disorders and OPMD. Our cellular model shows that interfering with the formation of expPABPN1-induced large nuclear aggregates increases the availability of nuclear expPABPN1 and significantly exacerbates cell death. Live microscopy reveals that cells harboring an increased amount of the soluble forms of expPABPN1 are significantly more prone to toxicity than those with nuclear aggregates. This is the first report directly indicating that nuclear aggregation in OPMD may reflect an active process by which cells sequester and inactivate the soluble toxic form of expPABPN1.
Messaed
Christiane
C
Center for Study of Brain Disease, CHUM Research Center, Notre-Dame Hospital, J.A. De-Sève Pavilion Y-3633, 1560 Sherbrooke East, Montreal (Québec), Canada H2L 4M1.
Dion
Patrick A
PA
Abu-Baker
Aida
A
Rochefort
Daniel
D
Laganiere
Janet
J
Brais
Bernard
B
Rouleau
Guy A
GA
D016923:Cell Death / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D042622:DNA Repeat Expansion / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D045586:Intranuclear Inclusion Bodies / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D039141:Muscular Dystrophy, Oculopharyngeal / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D009154:Mutation / Q000235:genetics; D039103:Poly(A)-Binding Protein II / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity*; D011189:Potassium Chloride / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D012995:Solubility; D014162:Transfection / Q000379:methods
D039103:Poly(A)-Binding Protein II; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D011189:Potassium Chloride