Human Molecular Genetics Advance Access originally published online on January 15, 2009
Human Molecular Genetics 2009 18(7):1310-1322; doi:10.1093/hmg/ddp030
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Translational readthrough by the aminoglycoside geneticin (G418) modulates SMN stability in vitro and improves motor function in SMA mice in vivo
1 Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA 2 Human Molecular Genetics Program, Children's Memorial Research Center, 2300 Children's Plaza, PO Box 211, Chicago, IL 60614, USA
* To whom correspondence should be addressed. Tel: +1 7737556352; Fax: +1 7737556345; Email: c-didonato{at}northwestern.edu
Received October 24, 2008; Revised December 22, 2008; Accepted January 14, 2009
Proximal spinal muscular atrophy (SMA) is a neuromuscular disorder for which there is no available therapy. SMA is caused by loss or mutation of the survival motor neuron 1 gene, SMN1, with retention of a nearly identical copy gene, SMN2. In contrast to SMN1, most SMN2 transcripts lack exon 7. This alternatively spliced transcript, 
7-SMN, encodes a truncated protein that is rapidly degraded. Inhibiting this degradation may be of therapeutic value for the treatment of SMA. Recently aminoglycosides, which decrease translational fidelity to promote readthrough of termination codons, were shown to increase SMN levels in patient cell lines. Amid uncertainty concerning the role of SMN's C-terminus, the potential of translational readthrough as a therapeutic mechanism for SMA is unclear. Here, we used stable cell lines to demonstrate the SMN C-terminus modulates protein stability in a sequence-independent manner that is reproducible by translational readthrough. Geneticin (G418) was then identified as a potent inducer of the 7-SMN target sequence in vitro through a novel quantitative assay amenable to high throughput screens. Subsequent treatment of patient cell lines demonstrated that G418 increases SMN levels and is a potential lead compound. Furthermore, treatment of SMA mice with G418 increased both SMN protein and mouse motor function. Chronic administration, however, was associated with toxicity that may have prevented the detection of a survival benefit. Collectively, these results substantiate a sequence independent role of SMN's C-terminus in protein stability and provide the first in vivo evidence supporting translational readthrough as a therapeutic strategy for the treatment of SMA.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  V. B. Mattis, A. D. Ebert, M. Y. Fosso, C.-W. Chang, and C. L. Lorson Delivery of a read-through inducing compound, TC007, lessens the severity of a spinal muscular atrophy animal model Hum. Mol. Genet., October 15, 2009; 18(20): 3906 - 3913. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Workman, L. Saieva, T. L. Carrel, T. O. Crawford, D. Liu, C. Lutz, C. E. Beattie, L. Pellizzoni, and A. H.M. Burghes A SMN missense mutation complements SMN2 restoring snRNPs and rescuing SMA mice Hum. Mol. Genet., June 15, 2009; 18(12): 2215 - 2229. [Abstract] [Full Text] [PDF]
|
|