scholarly journals 3′ Splice Site Sequences of Spinal Muscular Atrophy Related SMN2 Pre-mRNA Include Enhancers for Nearby Exons

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Sunghee Cho ◽  
Heegyum Moon ◽  
Tiing Jen Loh ◽  
Hyun Kyung Oh ◽  
Hey-Ran Kim ◽  
...  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Splice Site ◽  
Genetic Disease ◽  
Muscular Atrophy ◽  
Cleavage Sites ◽  
Human Genetic Disease ◽  
Splice Site Selection ◽  
Smn1 Gene ◽  
Splice Site Sequence ◽  
Smn Protein

Spinal muscular atrophy (SMA) is a human genetic disease which occurs because of the deletion or mutation of SMN1 gene. SMN1 gene encodes the SMN protein which plays a key role in spliceosome assembly. Although human patients contain SMN2, a duplicate of SMN1, splicing of SMN2 produces predominantly exon 7 skipped isoform. In order to understand the functions of splice site sequences on exon 7 and 8, we analyzed the effects of conserved splice site sequences on exon 7 skipping of SMN2 and SMN1 pre-mRNA. We show here that conserved 5′ splice site sequence of exon 7 promoted splicing of nearby exons and subsequently reduced splicing of distant exons. However, to our surprise, conserved 3′ splice site sequence of exon 7 and 8 did not promote splicing of nearby exons. By contrast, the mutation inhibited splicing of nearby exons and subsequently promoted splicing of distant exons. Our study shows that 3′ splice sites of exon 7 and 8 contain enhancer for their splice site selection, in addition to providing cleavage sites.

Onasemnogene Abeparvovec-xioi: Gene Therapy for Spinal Muscular Atrophy

2020 ◽  
Vol 54 (10) ◽  
pp. 1001-1009 ◽  
Author(s):  
Debra Stevens ◽  
Melanie K. Claborn ◽  
Brooke L. Gildon ◽  
Tiffany L. Kessler ◽  
Cheri Walker
Keyword(s):  
Gene Therapy ◽  
Spinal Muscular Atrophy ◽  
English Language ◽  
Liver Toxicity ◽  
Muscular Atrophy ◽  
Data Extraction ◽  
Case Series ◽  
Survival Motor Neuron ◽  
Smn1 Gene ◽  
Smn Protein

Objective: To review the efficacy and safety of onasemnogene abeparvovec-xioi (Zolgensma) in the treatment of spinal muscular atrophy (SMA). Data Sources: An English-language literature search of PubMed, MEDLINE, and Ovid (1946 to December 2019) was completed using the terms onasemnogene, AVXS-101, and spinal muscular atrophy. Manufacturer prescribing information, article bibliographies, and data from ClinicalTrials.gov were incorporated in the reviewed data. Study Selection/Data Extraction: All studies registered on ClinicalTrials.gov were incorporated in the reviewed data. Data Synthesis: Onasemnogene is the first agent for SMA utilizing gene therapy to directly provide survival motor neuron 1 ( SMN1) gene to produce SMN protein. Four publications of 1 clinical trial, 1 comparison study of treatment effects, and 1 combination therapy case series have been published. Relevance to Patient Care and Clinical Practice: Onasemnogene is a one time dose approved by the Food and Drug Administration for SMA patients <2 years old who possess mutations in both copies of the SMN1 gene. Conclusion: Onasemnogene appears to be an efficacious therapy for younger pediatric patients with SMA type 1. Concerns include drug cost and potential liver toxicity. Long-term benefits and risks have not been determined.

scholarly journals Therapeutic advances in 5q-linked spinal muscular atrophy

2018 ◽  
Vol 76 (4) ◽  
pp. 265-272 ◽  
Author(s):  
Umbertina Conti Reed ◽  
Edmar Zanoteli
Keyword(s):  
Spinal Muscular Atrophy ◽  
Antisense Oligonucleotides ◽  
Viral Vector ◽  
Age Of Onset ◽  
Muscular Atrophy ◽  
Homozygous Mutation ◽  
Smn1 Gene ◽  
New Era ◽  
History Of ◽  
Smn Protein

ABSTRACT Spinal muscular atrophy (SMA) is a severe and clinically-heterogeneous motor neuron disease caused, in most cases, by a homozygous mutation in the SMN1 gene. Regarding the age of onset and motor involvement, at least four distinct clinical phenotypes have been recognized. This clinical variability is, in part, related to the SMN2 copy number. By now, only supportive therapies have been available. However, promising specific therapies are currently being developed based on different mechanisms to increase the level of SMN protein; in particular, intrathecal antisense oligonucleotides that prevent the skipping of exon 7 during SMN2 transcription, and intravenous SMN1 insertion using viral vector. These therapeutic perspectives open a new era in the natural history of the disease. In this review, we intend to discuss the most recent and promising therapeutic strategies, with special consideration to the pathogenesis of the disease and the mechanisms of action of such therapies.

scholarly journals The First Orally Deliverable Small Molecule for the Treatment of Spinal Muscular Atrophy

2020 ◽  
Vol 15 ◽  
pp. 263310552097398
Author(s):  
Ravindra N Singh ◽  
Eric W Ottesen ◽  
Natalia N Singh
Keyword(s):  
Spinal Muscular Atrophy ◽  
Small Molecule ◽  
Muscular Atrophy ◽  
Survival Motor Neuron ◽  
Smn1 Gene ◽  
The Third ◽  
Splicing Silencer ◽  
Phenotypic Spectrum ◽  
Low Levels ◽  
Smn Protein

Spinal muscular atrophy (SMA) is 1 of the leading causes of infant mortality. SMA is mostly caused by low levels of Survival Motor Neuron (SMN) protein due to deletion of or mutation in the SMN1 gene. Its nearly identical copy, SMN2, fails to compensate for the loss of SMN1 due to predominant skipping of exon 7. Correction of SMN2 exon 7 splicing by an antisense oligonucleotide (ASO), nusinersen (Spinraza™), that targets the intronic splicing silencer N1 (ISS-N1) became the first approved therapy for SMA. Restoration of SMN levels using gene therapy was the next. Very recently, an orally deliverable small molecule, risdiplam (Evrysdi™), became the third approved therapy for SMA. Here we discuss how these therapies are positioned to meet the needs of the broad phenotypic spectrum of SMA patients.

scholarly journals Genomic Variability in the Survival Motor Neuron Genes (SMN1 and SMN2): Implications for Spinal Muscular Atrophy Phenotype and Therapeutics Development

2021 ◽  
Vol 22 (15) ◽  
pp. 7896
Author(s):  
Matthew E. R. Butchbach
Keyword(s):  
Spinal Muscular Atrophy ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Muscular Atrophy ◽  
Survival Motor Neuron ◽  
Smn1 Gene ◽  
Spinal Motor Neurons ◽  
Copy Numbers ◽  
Smn Protein ◽  
High Degree

Spinal muscular atrophy (SMA) is a leading genetic cause of infant death worldwide that is characterized by loss of spinal motor neurons leading to muscle weakness and atrophy. SMA results from the loss of survival motor neuron 1 (SMN1) gene but retention of its paralog SMN2. The copy numbers of SMN1 and SMN2 are variable within the human population with SMN2 copy number inversely correlating with SMA severity. Current therapeutic options for SMA focus on increasing SMN2 expression and alternative splicing so as to increase the amount of SMN protein. Recent work has demonstrated that not all SMN2, or SMN1, genes are equivalent and there is a high degree of genomic heterogeneity with respect to the SMN genes. Because SMA is now an actionable disease with SMN2 being the primary target, it is imperative to have a comprehensive understanding of this genomic heterogeneity with respect to hybrid SMN1–SMN2 genes generated by gene conversion events as well as partial deletions of the SMN genes. This review will describe this genetic heterogeneity in SMA and its impact on disease phenotype as well as therapeutic efficacy.

SMN mRNA and protein levels in peripheral blood

Neurology ◽  
2006 ◽  
Vol 66 (7) ◽  
pp. 1067-1073 ◽  
Author(s):  
C. J. Sumner ◽  
S. J. Kolb ◽  
G. G. Harmison ◽  
N. O. Jeffries ◽  
K. Schadt ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Spinal Muscular Atrophy ◽  
Disease Severity ◽  
Peripheral Blood ◽  
Muscular Atrophy ◽  
Gene Copy ◽  
Blood Levels ◽  
Type I ◽  
Protein Levels ◽  
Smn Protein

Background: Clinical trials of drugs that increase SMN protein levels in vitro are currently under way in patients with spinal muscular atrophy.Objective: To develop and validate measures of SMN mRNA and protein in peripheral blood and to establish baseline SMN levels in a cohort of controls, carriers, and patients of known genotype, which could be used to follow response to treatment.Methods: SMN1 and SMN2 gene copy numbers were determined in blood samples collected from 86 subjects. Quantitative reverse transcription PCR was used to measure blood levels of SMN mRNA with and without exon 7. A cell immunoassay was used to measure blood levels of SMN protein.Results: Blood levels of SMN mRNA and protein were measured with high reliability. There was little variation in SMN levels in individual subjects over a 5-week period. Levels of exon 7-containing SMN mRNA and SMN protein correlated with SMN1 and SMN2 gene copy number. With the exception of type I SMA, there was no correlation between SMN levels and disease severity.Conclusion: SMN mRNA and protein levels can be reliably measured in the peripheral blood and used during clinical trials in spinal muscular atrophy, but these levels do not necessarily predict disease severity.

scholarly journals Calpain Inhibition Increases SMN Protein in Spinal Cord Motoneurons and Ameliorates the Spinal Muscular Atrophy Phenotype in Mice

2018 ◽  
Vol 56 (6) ◽  
pp. 4414-4427 ◽  
Author(s):  
Sandra de la Fuente ◽  
Alba Sansa ◽  
Ambika Periyakaruppiah ◽  
Ana Garcera ◽  
Rosa M. Soler
Keyword(s):  
Spinal Cord ◽  
Spinal Muscular Atrophy ◽  
Muscular Atrophy ◽  
Smn Protein ◽  
Calpain Inhibition
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