TY - JOUR
T1 - (CCUG)n RNA toxicity in a Drosophila model of myotonic dystrophy type 2 (DM2) activates apoptosis
AU - Yenigun, Vildan Betul
AU - Sirito, Mario
AU - Amcheslavky, Alla
AU - Czernuszewicz, Tomek
AU - Colonques-Bellmunt, Jordi
AU - García-Alcover, Irma
AU - Wojciechowska, Marzena
AU - Bolduc, Clare
AU - Chen, Zhihong
AU - Castel, Arturo López
AU - Krahe, Ralf
AU - Bergmann, Andreas
N1 - Funding Information:
This work was supported by the National Institute of General Medical Sciences (NIGMS) under award number R35 GM118330 to A.B., and by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) under award number AR48171, the Muscular Dystrophy Association (RG 4321) and the Alice Kleberg Reynolds Foundation for Genetics to R.K. Supported in part by the National Institutes of Health/National Cancer Institute under award number P30 CA016672 and used for the Sequencing and Microarray Facility. Deposited in PMC for immediate release.
Publisher Copyright:
© 2017. Published by The Company of Biologists Ltd.
PY - 2017/8/1
Y1 - 2017/8/1
N2 - The myotonic dystrophies are prototypic toxic RNA gain-of-function diseases. Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by different unstable, noncoding microsatellite repeat expansions - (CTG)DM1 in DMPK and (CCTG)DM2 in CNBP. Although transcription of mutant repeats into (CUG)DM1 or (CCUG)DM2 appears to be necessary and sufficient to cause disease, their pathomechanisms remain incompletely understood. To study the mechanisms of (CCUG)DM2 toxicity and develop a convenient model for drug screening, we generated a transgenic DM2 model in the fruit fly Drosophila melanogaster with (CCUG)n repeats of variable length (n=16 and 106). Expression of noncoding (CCUG)106, but not (CCUG)16, in muscle and retinal cells led to the formation of ribonuclear foci and mis-splicing of genes implicated in DM pathology. Mis-splicing could be rescued by co-expression of human MBNL1, but not by CUGBP1 (CELF1) complementation. Flies with (CCUG)106 displayed strong disruption of external eye morphology and of the underlying retina. Furthermore, expression of (CCUG)106 in developing retinae caused a strong apoptotic response. Inhibition of apoptosis rescued theretinal disruptionin(CCUG)106 flies. Finally, we tested two chemical compounds that have shown therapeutic potential in DM1 models. Whereas treatment of (CCUG)106 flies with pentamidine had no effect, treatment with a PKR inhibitor blocked both the formation of RNA foci and apoptosis in retinae of (CCUG)106 flies. Our data indicate that expression of expanded (CCUG)DM2 repeats is toxic, causing inappropriate cell death in affected fly eyes. Our Drosophila DM2 model might provide a convenient tool for in vivo drug screening.
AB - The myotonic dystrophies are prototypic toxic RNA gain-of-function diseases. Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by different unstable, noncoding microsatellite repeat expansions - (CTG)DM1 in DMPK and (CCTG)DM2 in CNBP. Although transcription of mutant repeats into (CUG)DM1 or (CCUG)DM2 appears to be necessary and sufficient to cause disease, their pathomechanisms remain incompletely understood. To study the mechanisms of (CCUG)DM2 toxicity and develop a convenient model for drug screening, we generated a transgenic DM2 model in the fruit fly Drosophila melanogaster with (CCUG)n repeats of variable length (n=16 and 106). Expression of noncoding (CCUG)106, but not (CCUG)16, in muscle and retinal cells led to the formation of ribonuclear foci and mis-splicing of genes implicated in DM pathology. Mis-splicing could be rescued by co-expression of human MBNL1, but not by CUGBP1 (CELF1) complementation. Flies with (CCUG)106 displayed strong disruption of external eye morphology and of the underlying retina. Furthermore, expression of (CCUG)106 in developing retinae caused a strong apoptotic response. Inhibition of apoptosis rescued theretinal disruptionin(CCUG)106 flies. Finally, we tested two chemical compounds that have shown therapeutic potential in DM1 models. Whereas treatment of (CCUG)106 flies with pentamidine had no effect, treatment with a PKR inhibitor blocked both the formation of RNA foci and apoptosis in retinae of (CCUG)106 flies. Our data indicate that expression of expanded (CCUG)DM2 repeats is toxic, causing inappropriate cell death in affected fly eyes. Our Drosophila DM2 model might provide a convenient tool for in vivo drug screening.
KW - Apoptosis
KW - DM2
KW - Drosophila
KW - Muscleblind
KW - Myotonic dystrophy
KW - RNA toxicity
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U2 - 10.1242/dmm.026179
DO - 10.1242/dmm.026179
M3 - Article
C2 - 28623239
AN - SCOPUS:85027416871
SN - 1754-8403
VL - 10
SP - 993
EP - 1003
JO - DMM Disease Models and Mechanisms
JF - DMM Disease Models and Mechanisms
IS - 8
ER -