TSUNAMI: an antisense method to phenocopy splicing-associated diseases in animals

Antisense oligonucleotides (ASOs) are versatile molecules that can be designed to specifically alter splicing patterns of target pre-mRNAs. Here we exploit this feature to phenocopy a genetic disease. Spinal muscular atrophy (SMA) is a motor neuron disease caused by loss-of-function mutations in the SMN1 gene. The related SMN2 gene expresses suboptimal levels of functional SMN protein due to alternative splicing that skips exon 7; correcting this defect-e.g., with ASOs-is a promising therapeutic approach. We describe the use of ASOs that exacerbate SMN2 missplicing and phenocopy SMA in a dose-dependent manner when administered to transgenic Smn(-/-) mice. Intracerebroventricular ASO injection in neonatal mice recapitulates SMA-like progressive motor dysfunction, growth impairment, and shortened life span, with alpha-motor neuron loss and abnormal neuromuscular junctions. These SMA-like phenotypes are prevented by a therapeutic ASO that restores correct SMN2 splicing. We uncovered starvation-induced splicing changes, particularly in SMN2, which likely accelerate disease progression. These results constitute proof of principle that ASOs designed to cause sustained splicing defects can be used to induce pathogenesis and rapidly and accurately model splicing-associated diseases in animals. This approach allows the dissection of pathogenesis mechanisms, including spatial and temporal features of disease onset and progression, as well as testing of candidate therapeutics

Observation of Enhancement of the Morin Transition Temperature in Iridium-Doped α -Fe2O3 Thin Film by 57Fe-Grazing Incidence Synchrotron Radiation Mössbauer Spectroscopy

The Morin transition of a (0001)-oriented iridium-doped α -Fe2O3 thin film deposited on an Al2O3(0001) substrate was studied by 57Fe-grazing incidence synchrotron radiation Mössbauer spectroscopy (GISRMS). Temperature-dependentspectra proved that the iridium doping markedly enhanced the Morin temperature of the α -Fe2O3 thin film; the iron spin directions were perpendicular to the film plane at temperatures below 100 °C, while they were in-plane at temperatures above 150 °C. The antiferromagnetic ordering was maintained far above 400 °C. The results demonstrated the availabilities of 57Fe-GISRMS, which enables a very quick evaluation of the magnetism in antiferromagnetic ultrathin films at high temperatures

Pathological impact of SMN2 mis-splicing in adult SMA mice

Loss-of-function mutations in SMN1 cause spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. The related SMN2 gene expresses suboptimal levels of functional SMN protein, due to a splicing defect. Many SMA patients reach adulthood, and there is also adult-onset (type IV) SMA. There is currently no animal model for adult-onset SMA, and the tissue-specific pathogenesis of post-developmental SMN deficiency remains elusive. Here, we use an antisense oligonucleotide (ASO) to exacerbate SMN2 mis-splicing. Intracerebroventricular ASO injection in adult SMN2-transgenic mice phenocopies key aspects of adult-onset SMA, including delayed-onset motor dysfunction and relevant histopathological features. SMN2 mis-splicing increases during late-stage disease, likely accelerating disease progression. Systemic ASO injection in adult mice causes peripheral SMN2 mis-splicing and affects prognosis, eliciting marked liver and heart pathologies, with decreased IGF1 levels. ASO dose-response and time-course studies suggest that only moderate SMN levels are required in the adult central nervous system, and treatment with a splicing-correcting ASO shows a broad therapeutic time window. We describe distinctive pathological features of adult-onset and early-onset SMA