TY - JOUR
T1 - Antisense transcripts of the expanded C9ORF72 hexanucleotide repeat form nuclear RNA foci and undergo repeat-associated non-ATG translation in c9FTD/ALS
AU - Gendron, Tania F.
AU - Bieniek, Kevin F.
AU - Zhang, Yong Jie
AU - Jansen-West, Karen
AU - Ash, Peter E.A.
AU - Caulfield, Thomas
AU - Daughrity, Lillian
AU - Dunmore, Judith H.
AU - Castanedes-Casey, Monica
AU - Chew, Jeannie
AU - Cosio, Danielle M.
AU - Van Blitterswijk, Marka
AU - Lee, Wing C.
AU - Rademakers, Rosa
AU - Boylan, Kevin B.
AU - Dickson, Dennis W.
AU - Petrucelli, Leonard
N1 - Funding Information:
Acknowledgments We are grateful to all patients, family members, and caregivers who agreed to brain donation, without which these studies would have been impossible. We also acknowledge expert technical assistance of linda rousseau and Virginia Phillips for histology, and Beth Marten, Pamela Desaro, Amelia Johnston and Kris-tin Staggs-Douberly for brain banking. This work was supported by Mayo Clinic Foundation; National Institutes of Health/National Institute on Aging [r01 Ag026251 (lP, rr), P01 Ag003949 (DWD), P50 Ag016574 (DWD, rr)]; National Institutes of Health/National Institute of Neurological Disorders and Stroke [r21 NS074121 (TFg, KB), r21 NS079807 (YZ), r01 NS080882 (rr), r01 NS063964 (lP); r01 NS077402 (lP), P50 NS072187 (DWD, rr); r21 NS084528 (lP)]; National Institute of environmental Health Services [r01 eS20395 (lP)]; Amyotrophic lateral Sclerosis Association (KB, lP); AlS Therapy Alliance (rr).
PY - 2013/12
Y1 - 2013/12
N2 - Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are devastating neurodegenerative disorders with clinical, genetic, and neuropathological overlap. A hexanucleotide (GGGGCC) repeat expansion in a non-coding region of C9ORF72 is the major genetic cause of both diseases. The mechanisms by which this repeat expansion causes "c9FTD/ALS" are not definitively known, but RNA-mediated toxicity is a likely culprit. RNA transcripts of the expanded GGGGCC repeat form nuclear foci in c9FTD/ALS, and also undergo repeat-associated non-ATG (RAN) translation resulting in the production of three aggregation- prone proteins. The goal of this study was to examine whether antisense transcripts resulting from bidirectional transcription of the expanded repeat behave in a similar manner. We show that ectopic expression of (CCCCGG)66 in cultured cells results in foci formation. Using novel polyclonal antibodies for the detection of possible (CCCCGG) exp RAN proteins [poly(PR), poly(GP) and poly(PA)], we validated that (CCCCGG)66 is also subject to RAN translation in transfected cells. Of importance, foci composed of antisense transcripts are observed in the frontal cortex, spinal cord and cerebellum of c9FTD/ALS cases, and neuronal inclusions of poly(PR), poly(GP) and poly(PA) are present in various brain tissues in c9FTD/ALS, but not in other neurodegenerative diseases, including CAG repeat disorders. Of note, RNA foci and poly(GP) inclusions infrequently cooccur in the same cell, suggesting these events represent two distinct ways in which the C9ORF72 repeat expansion may evoke neurotoxic effects. These findings provide mechanistic insight into the pathogenesis of c9FTD/ALS, and have significant implications for therapeutic strategies.
AB - Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are devastating neurodegenerative disorders with clinical, genetic, and neuropathological overlap. A hexanucleotide (GGGGCC) repeat expansion in a non-coding region of C9ORF72 is the major genetic cause of both diseases. The mechanisms by which this repeat expansion causes "c9FTD/ALS" are not definitively known, but RNA-mediated toxicity is a likely culprit. RNA transcripts of the expanded GGGGCC repeat form nuclear foci in c9FTD/ALS, and also undergo repeat-associated non-ATG (RAN) translation resulting in the production of three aggregation- prone proteins. The goal of this study was to examine whether antisense transcripts resulting from bidirectional transcription of the expanded repeat behave in a similar manner. We show that ectopic expression of (CCCCGG)66 in cultured cells results in foci formation. Using novel polyclonal antibodies for the detection of possible (CCCCGG) exp RAN proteins [poly(PR), poly(GP) and poly(PA)], we validated that (CCCCGG)66 is also subject to RAN translation in transfected cells. Of importance, foci composed of antisense transcripts are observed in the frontal cortex, spinal cord and cerebellum of c9FTD/ALS cases, and neuronal inclusions of poly(PR), poly(GP) and poly(PA) are present in various brain tissues in c9FTD/ALS, but not in other neurodegenerative diseases, including CAG repeat disorders. Of note, RNA foci and poly(GP) inclusions infrequently cooccur in the same cell, suggesting these events represent two distinct ways in which the C9ORF72 repeat expansion may evoke neurotoxic effects. These findings provide mechanistic insight into the pathogenesis of c9FTD/ALS, and have significant implications for therapeutic strategies.
KW - Amyotrophic lateral sclerosis
KW - Bidirectional transcription
KW - C9ORF72
KW - Expanded repeat
KW - Frontotemporal dementia
KW - RNA foci
KW - Repeat-associated non-ATG translation
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U2 - 10.1007/s00401-013-1192-8
DO - 10.1007/s00401-013-1192-8
M3 - Article
C2 - 24129584
AN - SCOPUS:84892590289
SN - 0001-6322
VL - 126
SP - 829
EP - 844
JO - Acta Neuropathologica
JF - Acta Neuropathologica
IS - 6
ER -