Long-term AAV vector gene and protein expression in mouse brain from a small pan-cellular promoter is similar to neural cell promoters.
The neurogenetic, lysosomal enzyme (LSE) deficiency diseases are characterized by storage lesions throughout the brain; therefore, gene transfer needs to provide widespread distribution of the normal enzyme. Adeno-associated virus (AAV) vectors can be effective in the brain despite limited transduction because LSEs are exported to neighboring cells (cross-correction) to reverse the metabolic deficit. The extent of correction is determined by a combination of the total amount of LSE produced by a vector and the spatial distribution of the vector within the brain. Neuron-specific promoters have been used in the brain because AAV predominantly transduces neurons. However, these promoters are large, using up a substantial amount of the limited cloning capacity of AAV vector genomes. A small promoter that is active in all cells, from the LSE beta-glucuronidase (GUSB), has been used for long-term expression in AAV vectors in the brain but the natural promoter is expressed at very low levels. The amount of LSE exported from a cell is proportional to the level of transcription, thus more active promoters would export more LSE for cross-correction, but direct comparisons have not been reported. In this study, we show that in long-term experiments (>6 months) the GUSB minimal promoter (hGBp) expresses the hGUSB enzyme in brain at similar levels as the neuron-specific enolase promoter or the promoter from the latency-associated transcript of herpes simplex virus. The hGBp minimal promoter thus may be useful for long-term expression in the central nervous system of large cDNAs, bicitronic transcription units, self-complimentary or other designs with size constraints in the AAV vector system.
Husain
T
T
W F Goodman Center for Comparative Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Passini
M A
MA
Parente
M K
MK
Fraser
N W
NW
Wolfe
J H
JH
D000818:Animals; D001921:Brain / Q000201:enzymology*; D000229:Dependovirus / Q000235:genetics*; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000627:therapeutic use*; D005966:Glucuronidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007267:Injections; D008247:Lysosomes / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D016538:Mucopolysaccharidosis VII / Q000201:enzymology / Q000628:therapy; D011401:Promoter Regions, Genetic; D014018:Tissue Distribution; D014158:Transcription, Genetic / Q000235:genetics; D014161:Transduction, Genetic / Q000379:methods
D005966:Glucuronidase