Adenoviral-mediated, high-level, cell-specific transgene expression: a SYN1-WPRE cassette mediates increased transgene expression with no loss of neuron specificity
Key findings
A composite adenoviral expression cassette combining 495 bp of the human SYN1 (synapsin-1) promoter with 800 bp of the woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) was constructed. In non-neuronal HeLa cells, SYN1-driven vectors produced no fluorescence above background regardless of WPRE addition, confirming complete neuronal specificity.
Addition of WPRE to the SYN1-EGFP adenoviral construct increased EGFP fluorescence approximately 3-fold by fluorometry and 2.2-fold by FACS in primary dissociated hippocampal cultures. Neuronal specificity was maintained across all MOIs and time points, demonstrating that WPRE enhances expression without compromising the cell-type restriction of the SYN1 promoter.
In vivo injection of SYN1-WPRE-EGFP adenoviral vectors demonstrated enhanced transgene expression in dentate-gyrus neurons with no loss of neuronal specificity for at least 6 weeks post-transfection. This supports use of the SYN1-WPRE cassette for long-term neuron-specific gene delivery at lower viral titers, potentially reducing immunogenic inflammatory responses associated with higher viral loads.