Developing Therapeutic Splice-Correcting Antisense Oligomers for Adult-Onset Pompe Disease with c.-32-13T>G Mutation.

The mutation c.-32-13T>G in the GAA gene impacts normal exon 2 splicing and is found in two-thirds of late-onset Pompe disease cases. We have explored a therapeutic strategy using splice modulating phosphorodiamidate morpholino oligomers to enhance GAA exon 2 inclusion in the mature mRNA of patients carrying this common mutation.

Investigating the Implications of Exon Skipping Using a Exon 9 Deleted Mouse Model.

Severity and disease progression in people with Cystic Fibrosis (CF) is typically dependent on their genotype. One potential therapeutic strategy for people with specific mutations is exon skipping with antisense oligonucleotides (AO). exon 9 is an in-frame exon and hence the exclusion of this exon would excise only 31 amino acids but not alter the reading frame of the remaining mRNA.

Morpholino Oligomer-Induced Dystrophin Isoforms to Map the Functional Domains in the Dystrophin Protein.

Dystrophin plays a crucial role in maintaining sarcolemma stability during muscle contractions, and mutations that prevent the expression of a functional protein cause Duchenne muscular dystrophy (DMD). Antisense oligonucleotide-mediated manipulation of pre-messenger RNA splicing to bypass Duchenne-causing mutations and restore functional dystrophin expression has entered the clinic for the most common mutations. The rationale of "exon skipping" is based upon genotype-phenotype correlations observed in Becker muscular dystrophy, a milder allelic disorder generally characterized by in-frame deletions and internally truncated but semi-functional dystrophin isoforms.

Expanding the phenotype of GMPPB mutations.

Dystroglycanopathies are a heterogeneous group of diseases with a broad phenotypic spectrum ranging from severe disorders with congenital muscle weakness, eye and brain structural abnormalities and intellectual delay to adult-onset limb-girdle muscular dystrophies without mental retardation. Most frequently the disease onset is congenital or during childhood. The exception is FKRP mutations, in which adult onset is a common presentation.

Antisense oligonucleotide induction of progerin in human myogenic cells.

We sought to use splice-switching antisense oligonucleotides to produce a model of accelerated ageing by enhancing expression of progerin, translated from a mis-spliced lamin A gene (LMNA) transcript in human myogenic cells. The progerin transcript (LMNA Δ150) lacks the last 150 bases of exon 11, and is translated into a truncated protein associated with the severe premature ageing disease, Hutchinson-Gilford progeria syndrome (HGPS). HGPS arises from de novo mutations that activate a cryptic splice site in exon 11 of LMNA and result in progerin accumulation in tissues of mesodermal origin.

Antisense suppression of donor splice site mutations in the dystrophin gene transcript.

We describe two donor splice site mutations, affecting dystrophin exons 16 and 45 that led to Duchenne muscular dystrophy (DMD), through catastrophic inactivation of the mRNA. These gene lesions unexpectedly resulted in the retention of the downstream introns, thereby increasing the length of the dystrophin mRNA by 20.2 and 36 kb, respectively.

Investigation of age-related changes in LMNA splicing and expression of progerin in human skeletal muscles.

Age-related changes in splice-forms of LMNA, which encodes the nuclear lamina proteins lamin A/C, have not been investigated in skeletal muscle. In the rare premature ageing disease, Hutchinson-Gilford progeria syndrome (HGPS), de novo point mutations in LMNA activate a cryptic splice site in exon 11, resulting in a 150 base deletion in LMNA mRNA and accumulation of a truncated protein isoform, progerin. The LMNA Δ150 progerin transcript has also been found in trace quantities in tissues of healthy people and its implication in 'natural' ageing has been proposed.

Primary over-expression of AβPP in muscle does not lead to the development of inclusion body myositis in a new lineage of the MCK-AβPP transgenic mouse.

The aim of this study is to determine whether primary over-expression of AβPP in skeletal muscle results in the development of features of inclusion body myositis (IBM) in a new lineage of the MCK-AβPP transgenic mouse. Quantitative histological, immunohistochemical and western blotting studies were performed on muscles from 3 to 18 month old transgenic and wild-type C57BL6/SJL mice. Electron microscopy was also performed on muscle sections from selected animals.

Mismatched single stranded antisense oligonucleotides can induce efficient dystrophin splice switching.

Background: Antisense oligomer induced exon skipping aims to reduce the severity of Duchenne muscular dystrophy by redirecting splicing during pre-RNA processing such that the causative mutation is by-passed and a shorter but partially functional Becker muscular dystrophy-like dystrophin isoform is produced. Normal exons are generally targeted to restore the dystrophin reading frame however, an appreciable subset of dystrophin mutations are intra-exonic and therefore have the potential to compromise oligomer efficiency, necessitating personalised oligomer design for some patients. Although antisense oligomers are easily personalised, it remains unclear whether all patient polymorphisms within antisense oligomer target sequences will require the costly process of producing and validating patient specific compounds.

Dystrophin isoform induction in vivo by antisense-mediated alternative splicing.

Antisense oligomer-induced manipulation of dystrophin pre-mRNA processing can remove exons carrying mutations, or exclude exons flanking frameshifting mutations, and restore dystrophin expression in dystrophinopathy models and in Duchenne muscular dystrophy (DMD) patients. Splice intervention can also be used to manipulate the normal dystrophin pre-mRNA processing and ablate dystrophin expression in wild-type mice, with signs of pathology being induced in selected muscles within 4 weeks of commencing treatment. The disruption of normal dystrophin pre-mRNA processing to alter the reading frame can be very efficient and offers an alternative mechanism to RNA silencing for gene suppression.

Differential effects of dietary fatty acids on the cerebral distribution of plasma-derived apo B lipoproteins with amyloid-beta.

Some dietary fats are a risk factor for Alzheimer's disease (AD) but the mechanisms for this association are presently unknown. In the present study we showed in wild-type mice that chronic ingestion of SFA results in blood-brain barrier (BBB) dysfunction and significant delivery into the brain of plasma proteins, including apo B lipoproteins that are endogenously enriched in amyloid-beta (Abeta). Conversely, the plasma concentration of S100B was used as a marker of brain-to-blood leakage and was found to be increased two-fold because of SFA feeding.

Synergistic effects of high fat feeding and apolipoprotein E deletion on enterocytic amyloid-beta abundance.

Background: Amyloid-beta (Abeta), a key protein found in amyloid plaques of subjects with Alzheimer's disease is expressed in the absorptive epithelial cells of the small intestine. Ingestion of saturated fat significantly enhances enterocytic Abeta abundance whereas fasting abolishes expression. Apolipoprotein (apo) E has been shown to directly modulate Abeta biogenesis in liver and neuronal cells but it's effect in enterocytes is not known.

Morpholino oligomer-mediated exon skipping averts the onset of dystrophic pathology in the mdx mouse.

Duchenne and Becker muscular dystrophies are allelic disorders arising from mutations in the dystrophin gene. Duchenne muscular dystrophy is characterized by an absence of functional protein, whereas Becker muscular dystrophy, commonly caused by in-frame deletions, shows synthesis of partially functional protein. Anti-sense oligonucleotides can induce specific exon removal during processing of the dystrophin primary transcript, while maintaining or restoring the reading frame, and thereby overcome protein-truncating mutations.

Dystrophin expression in the mdx mouse after localised and systemic administration of a morpholino antisense oligonucleotide.

Background: Duchenne and Becker muscular dystrophies are allelic disorders arising from mutations in the dystrophin gene. Duchenne muscular dystrophy is characterised by an absence of functional protein, while Becker muscular dystrophy is usually caused by in-frame deletions allowing synthesis of some functional protein. Treatment options are limited, and we are investigating the potential of transcript manipulation to overcome disease-causing mutations.

Terminal antisense oligonucleotide modifications can enhance induced exon skipping.

Induction of specific exon skipping during the processing of the dystrophin gene transcript is being pursued as a potential therapy for Duchenne muscular dystrophy. Antisense oligonucleotides directed at motifs involved in pre-mRNA processing can manipulate dystrophin exon incorporation in the mature gene transcript. We have compared the exon skipping ability of oligodeoxyribonucleotides with compounds of the identical sequence incorporating 2'-O-methyl modified bases.

Prevalence of amyloid-beta deposition in the cerebral cortex in Parkinson's disease.

The pathological basis for the dementia which occurs in 20 to 40% of patients with idiopathic Parkinson's disease (PD) remains uncertain. In the present postmortem study, we compared the prevalence and severity of parenchymal and vascular amyloid-beta (Abeta) deposition in the cerebral cortex in a group of 57 PD brains, including 13 cases with dementia, and in 100 control brains. A higher proportion of PD brains had vascular Abeta deposition, whereas the proportions and severity of parenchymal Abeta were similar in the PD and control groups.

Prevalence of stroke in Parkinson's disease: a postmortem study.

The results of previous epidemiological studies of the relationship between Parkinson's disease and stroke have been conflicting; some showing a reduced risk of ischaemic and haemorrhagic stroke during life, and others indicating an increased likelihood of stroke-related death. We compared the frequency of cerebral infarcts and haemorrhages at postmortem in 100 cases of pathologically verified idiopathic Parkinson's disease and 100 age-matched control brains. No significant differences were found in the numbers of infarcts or haemorrhages or stroke-related deaths between the two groups.