Alternative splicing of the bcl-x gene generates two transcripts: the anti-apoptotic bcl-xL isoform and the pro-apoptotic bcl-xS isoform. The ratio between the two isoforms is a key factor in development and in cancer progression. Here, we show that a short antisense chimeric peptide nucleic acid (PNA) oligonucleotide conjugated to a polypeptide containing eight Ser-Arg repeats (SR)8 can modulate splicing of bcl-x both in vitro and in vivo and induces apoptosis in HeLa cells. The PNA-SR oligo was targeted to a region of bcl-x that does not contain splicing regulatory sequences and was able to override the complex network of splicing enhancers and silencers that regulates the ratio between the two bcl-x isoforms. Thus, PNA-SR oligos are powerful tools that can potentially modulate splice site choice in endogenous genes independent of the presence of other splicing regulatory mechanisms on the target gene.

Two unique gene mutations in the enzyme beta-glucuronidase (GUSB) that result in the lysosomal storage disease Mucopolysaccharidosis (MPS) type VII had previously been reported to have differing disease phenotype severities when compared on differing mouse strains. The MPSVII mouse has proven to be a highly efficacious model to study mucopolysaccharidoses and for evaluating potential gene or stem cell therapies for lysosomal storage diseases. We examined the single base pair deletion (MPSVII) and the intracisternal A particle element insertion (MPSVII2J) in GUSB compared with control animals by skeletal measures, electroretinography, auditory-evoked brainstem response and life span on a C57BL/6J background strain. In all measures, both mutations result in either a trend toward or significant changes from the background strain control. In all measures, there is no significant phenotypic difference between the two mutations. The 2J variant is a more easily genotyped and equally affected phenotype, which holds promise for further studies of chimerism and stem cell therapy approaches.

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