PABPN1 polyalanine tract deletion and long expansions modify its aggregation pattern and expression.
Expansions of a (GCN)10/polyalanine tract in the Poly(A) Binding Protein Nuclear 1 (PABPN1) cause autosomal dominant oculopharyngeal muscular dystrophy (OPMD). In OPMD muscles, as in models, PABPN1 accumulates in intranuclear inclusions (INIs) whereas in other diseases caused by similar polyalanine expansions, the mutated proteins have been shown to abnormally accumulate in the cytoplasm. This study presents the impact on the subcellular localization of PABPN1 produced by large expansions or deletion of its polyalanine tract. Large tracts of more than 24 alanines result in the nuclear accumulation of PABPN1 in SFRS2-positive functional speckles and a significant decline in cell survival. These large expansions do not cause INIs formation nor do they lead to cytoplasmic accumulation. Deletion of the polyalanine tract induces the formation of aggregates that are located on either side and cross the nuclear membrane, highlighting the possible role of the N-terminal polyalanine tract in PABPN1 nucleo-cytoplasmic transport. We also show that even though five other proteins with polyalanine tracts tend to aggregate when over-expressed they do not co-aggregate with PABPN1 INIs. This study presents the first experimental evidence that there may be a relative loss of function in OPMD by decreasing the availability of PABPN1 through an INI-independent mechanism.
Klein
Arnaud F
AF
Laboratory of neurogenetics of motion, Centre d'excellence en neuromique de l'Université de Montréal, CRCHUM, Université de Montréal, Montréal, Canada.
Ebihara
Mitsuru
M
Alexander
Christine
C
Dicaire
Marie-Josée
MJ
Sasseville
A Marie-Josée
AM
Langelier
Yves
Y
Rouleau
Guy A
GA
Brais
Bernard
B
D000818:Animals; D019556:COS Cells; D022003:Cell Nucleus Structures / Q000737:chemistry; D002470:Cell Survival; D002522:Chlorocebus aethiops; D042622:DNA Repeat Expansion; D006367:HeLa Cells; D006801:Humans; D009685:Nuclear Envelope / Q000737:chemistry; D009687:Nuclear Proteins / Q000032:analysis; D010455:Peptides / Q000737:chemistry / Q000235:genetics*; D039103:Poly(A)-Binding Protein II / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012261:Ribonucleoproteins / Q000032:analysis; D017384:Sequence Deletion; D000068103:Serine-Arginine Splicing Factors
D009687:Nuclear Proteins; D010455:Peptides; D039103:Poly(A)-Binding Protein II; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors; C019529:polyalanine