Abstract
A hexanucleotide repeat expansion (HRE), (GGGGCC) n, in C9orf72 is the most common genetic cause of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here we identify a molecular mechanism by which structural polymorphism of the HRE leads to ALS/FTD pathology and defects. The HRE forms DNA and RNA G-quadruplexes with distinct structures and promotes RNA•DNA hybrids (R-loops). The structural polymorphism causes a repeat-length-dependent accumulation of transcripts aborted in the HRE region. These transcribed repeats bind to ribonucleoproteins in a conformation- dependent manner. Specifically, nucleolin, an essential nucleolar protein, preferentially binds the HRE G-quadruplex, and patient cells show evidence of nucleolar stress. Our results demonstrate that distinct C9orf72 HRE structural polymorphism at both DNA and RNA levels initiates molecular cascades leading to ALS/FTD pathologies, and provide the basis for a mechanistic model for repeat-associated neurodegenerative diseases.
| Original language | English |
|---|---|
| Pages (from-to) | 195-200 |
| Number of pages | 6 |
| Journal | Nature |
| Volume | 507 |
| Issue number | 7491 |
| DOIs | |
| State | Published - 2014 |
Bibliographical note
Funding Information:Acknowledgements We thankB. J. Traynor for theinformation onthe ALS patientcells, M. DeJesus-Hernandez and R. Rademakers for the genotyping PCR protocols on patient cells, P. J. Tienari for providing additional fibroblast/iPS cell lines, M. J. Matunis for the hnRNP F/H antibody, R. S. Nirujogi for his assistance with the SILAC LC-MS analysis, T. K. Chakravarty for his assistance with transfection of HEK293T cells, the S. Balasubramanian laboratory for generously providing the BG4 plasmid, P. L. Steinwald for purification and assistance in the validation of the BG4 protein, R.M.Powers for assistance inthe staining and quantification ofPbodiesiniPS neurons, and O. Pletnikova for processing human tissues. This work was supported by National Institutes of Health grants NS07432 (J.W.) and NS085207 (R.S. and J.D.R.), the Robert Packard Center for ALS Research at Johns Hopkins and the Muscular Dystrophy Association (J.W.), Target ALS (J.D.R.), the ALS Association (J.W.), the Johns Hopkins Alzheimer’s Disease Research Center NIH P50AG05146 (J.C.T.), National Cancer Institute training grant 5T32CA009110-36 (A.R.H. and E.A.J.S.), Maryland Stem Cell Research Fund (C.J.D.), Judith & Jean Pape Adams Charitable Foundation (R.S.), and the Samuel I. Newhouse Foundation (J.C.T.). We thank P. A. Coulumbe, V. C. Culotta, M. J. Matunis, P. S. Miller, B. A. Learn and members of the J. Wang laboratory for manuscript advice and discussions.