Long-term AAV vector gene and protein expression in mouse brain from a small pan-cellular promoter is similar to neural cell promoters

T Husain, MA Passini, MK Parente, NW Fraser… - Gene therapy, 2009 - nature.com
T Husain, MA Passini, MK Parente, NW Fraser, JH Wolfe
Gene therapy, 2009nature.com
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 …
Abstract
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 β-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.
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