FP.10 Combination of BIO101 with antisense oligonucleotide therapy demonstrates synergistic beneficial effects in severe SMA-like mice

Spinal Muscular Atrophy: A Deficiency in a Ubiquitous Protein; a Motor Neuron-Specific Disease

Buying time for infants with spinal muscular atrophy

Bifunctional RNAs Targeting the Intronic Splicing Silencer N1 Increase SMN Levels and Reduce Disease Severity in an Animal Model of Spinal Muscular Atrophy

Dual Masking of Specific Negative Splicing Regulatory Elements Resulted in Maximal Exon 7 Inclusion of SMN2 Gene

SMA THERAPIES II AND BIOMARKERS: P.259SMN protein levels before and after treatment with RG7916 in type 1, 2 and 3 SMA patients compared to healthy subjects

Exercise training: thinking ahead to counteract systemic manifestations of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a progressive neuromuscular disease. Since disease severity is related to the amount of survival motor neuron (SMN) protein, up-regulated functional SMN protein levels from the SMN2 gene are considered a major SMA drug-discovery strategy. In this study, we investigated the possible effects of triptolide, a diterpene triepoxide purified from Tripterygium wilfordii Hook. F., as a new compound for increasing SMN protein. The effects and mechanisms of triptolide on the production of SMA protein were determined by cell-based assays using the motor neuronal cell line NSC34 and skin fibroblasts from SMA patients. Wild-type (Smn(+/+) SMN2(-/-) , C57BL/6) and SMA-like (Smn(-/-) SMN2) mice were injected with triptolide (0.01 or 0.1 mg·kg(-1) ·day(-1) , i.p.) and their survival rate and level of change in SMN protein in neurons and muscle tissue measured. In NSC34 cells and human SMA fibroblasts, pM concentrations of triptolide significantly increased SMN protein expression and the levels of SMN complex component (Gemin2 and Gemin3). In human SMA fibroblasts, triptolide increased SMN-containing nuclear gems and the ratio of full-length transcripts (FL-SMN2) to SMN2 transcripts lacking exon 7 (SMN2Δ7). Furthermore, in SMA-like mice, triptolide significantly increased SMN protein levels in the brain, spinal cord and gastrocnemius muscle. Furthermore, triptolide treatment increased survival and reduced weight loss in SMA-like mice. Triptolide enhanced SMN protein production by promoting SMN2 activation, exon 7 inclusion and increasing nuclear gems, and increased survival in SMA mice, which suggests triptolide might be a potential candidate for SMA therapy.

93rd ENMC international workshop: non-5q-spinal muscular atrophies (SMA) – clinical picture (6–8 April 2001, Naarden, The Netherlands)

The survival of motor neuron (SMN) protein, responsible for the neurodegenerative disease spinal muscular atrophy (SMA), oligomerizes and forms a stable complex with seven other major components, the Gemin proteins. Besides the SMN protein, Gemin2 is a core protein that is essential for the formation of the SMN complex, although the mechanism by which it drives formation is unclear. We have found a novel interaction, a Gemin2 self-association, using the mammalian two-hybrid system and the in vitro pull-down assays. Using in vitro dissociation assays, we also found that the self-interaction of the amino-terminal SMN protein, which was confirmed in this study, became stable in the presence of Gemin2. In addition, Gemin2 knockdown using small interference RNA treatment revealed a drastic decrease in SMN oligomer formation and in the assembly activity of spliceosomal small nuclear ribonucleoprotein (snRNP). Taken together, these results indicate that Gemin2 plays an important role in snRNP assembly through the stabilization of the SMN oligomer/complex via novel self-interaction. Applying the results/techniques to amino-terminal SMN missense mutants that were recently identified from SMA patients, we successfully showed that amino-terminal self-association, Gemin2 binding, the stabilization effect of Gemin2, and snRNP assembly activity were all lowered in the mutant SMN(D44V), suggesting that instability of the amino-terminal SMN self-association may cause SMA in patients carrying this allele.

Targeting splicing in spinal muscular atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder. About 80% - 90% of SMA patients are missing both copies of SMN1, and 5% - 10% of patients are compound heterozygotes. In the present study, we aimed to analyze survival motor neuron 1 (SMN1) gene mutation in three patients with spinal muscular atrophy and their families to explore the effect of mutation on SMN protein function and the relationship between mutation and clinical phenotype. According to the international criterion, all patients were diagnosed by a neurologist. Patient 1 is a 5 years old boy with SMA type II. Patient 2, female, 2.5 years old, was SMA type II. Patient 3, female, 9 years old, was SMA type III. The brother of patient 3 was SMA type II, too. The age at last examination was 14 years. Genomic DNA was extracted from peripheral blood leukocytes by using standard phenol/chloroform method and total RNA was extracted from whole blood with QIAamp RNA Blood Mini Kit. PCR/RFLP was used to detect the homozygosis deletion of the SMN1 exon 7, and multiplex ligation-dependent probe amplification (MLPA) were performed to analyze the gene dosage of SMN1 and SMN2 for each patient and his/her family members; reverse transcriptase (RT)-PCR and clone sequencing were conducted for identifying the point mutation of SMN1 in three patients. The sequencing of genomic DNA and MLPA were carried out in the 3 families members to confirm the transition of mutation. No homozygous deletion of the SMN1 exon 7 was observed in any member of the 3 families. Case 1 and case 2 had one SMN1 copy compound with c.400G > A (p.Glu134Lys) mutation on it and SMN2 was two copies, respectively. Case 3 and her brother also had one copy of SMN1 and two copies of SMN2, and a mutation c.689C > T (p.Ser230Leu) occurred on the retained SMN1. All point mutations were from their fathers and deletion come from their mothers for SMN1 gene. In this work, p.Glu134Lys and p.Ser230Leu mutations were identified in three unrelated families and p.Glu134Lys from two patients was first discovered in Chinese SMA. The p.Glu134Lys mutation within the SMN Tudor domain prevents the binding of SMN and Sm. The fact that p.Ser230Leu results in a polar amino acid substituted for non-polar amino acid possibly affects the structure of SMN and then damages its function. SMN1 point mutation analysis is not only advantageous to the diagnosis of those patients with heterozygous deletion of SMN1, but will be beneficial to the prenatal diagnosis and genetic counseling for their families.

The real impact of physical exercise parameters, i.e. intensity, type of contraction and solicited energetic metabolism, on neuroprotection in the specific context of neurodegeneration remains poorly explored. In this study behavioural, biochemical and cellular analyses were conducted to compare the effects of two different long-term exercise protocols, high intensity swimming and low intensity running, on motor units of a type 3 spinal muscular atrophy (SMA)-like mouse model. Our data revealed a preferential SMA-induced death of intermediate and fast motor neurons which was limited by the swimming protocol only, suggesting a close relationship between neuron-specific protection and their activation levels by specific exercise. The exercise-induced neuroprotection was independent of SMN protein expression and associated with specific metabolic and behavioural adaptations with notably a swimming-induced reduction of muscle fatigability. Our results provide new insight into the motor units' adaptations to different physical exercise parameters and will contribute to the design of new active physiotherapy protocols for patient care. Spinal muscular atrophy (SMA) is a group of autosomal recessive neurodegenerative diseases differing in their clinical outcome, characterized by the specific loss of spinal motor neurons, caused by insufficient level of expression of the protein survival of motor neuron (SMN). No cure is at present available for SMA. While physical exercise might represent a promising approach for alleviating SMA symptoms, the lack of data dealing with the effects of different exercise types on diseased motor units still precludes the use of active physiotherapy in SMA patients. In the present study, we have evaluated the efficiency of two long-term physical exercise paradigms, based on either high intensity swimming or low intensity running, in alleviating SMA symptoms in a mild type 3 SMA-like mouse model. We found that 10months' physical training induced significant benefits in terms of resistance to muscle damage, energetic metabolism, muscle fatigue and motor behaviour. Both exercise types significantly enhanced motor neuron survival, independently of SMN expression, leading to the maintenance of neuromuscular junctions and skeletal muscle phenotypes, particularly in the soleus, plantaris and tibialis of trained mice. Most importantly, both exercises significantly improved neuromuscular excitability properties. Further, all these training-induced benefits were quantitatively and qualitatively related to the specific characteristics of each exercise, suggesting that the related neuroprotection is strongly dependent on the specific activation of some motor neuron subpopulations. Taken together, the present data show significant long-term exercise benefits in type 3 SMA-like mice providing important clues for designing rehabilitation programmes in patients.

Is RNA manipulation a viable therapy for spinal muscular atrophy?

Trinucleotide insertion in the SMN2 promoter may not be related to the clinical phenotype of SMA

AAV9-Mediated Expression of SMN Restricted to Neurons Does Not Rescue the Spinal Muscular Atrophy Phenotype in Mice