RETROVIRUS-MEDIATED ENZYMATIC CORRECTION OF TAY-SACHS DEFECT IN TRANSDUCED AND NON-TRANSDUCED CELLS

Tay-Sachs disease is a severe neurodegenerative disorder due to mutati ons in the HEXA gene coding for the alpha-chain of the alpha-beta hete rodimeric lysosomal enzyme beta-hexosaminidase A (HexA). Because no tr eatment is available for this disease, we have investigated the possib ility of enzymatic correction of HexA-deficient cells by HEXA gene tra nsfer. Human HEXA cDNA was subcloned into a retroviral plasmid generat ing to G.HEXA vector. The best Psi-CRIP producer clone of G.HEXA retro viral particles was isolated, and murine HexA-deficient fibroblasts de rived from hexa -/-mice were transduced with the G.HEXA vector. Transd uced cells overexpressed the alpha-chain, resulting in the synthesis o f interspecific HexA (human alpha-chain/murine beta-chain) and in a to tal correction of HexA deficiency. The alpha-chain was secreted in the culture medium and taken up by HexA-deficient cells via mannose-6-pho sphate receptor binding, allowing for the restoration of intracellular HexA activity in non-transduced cells.