THE HUMAN PH ALDOLASE-A PROMOTER DIRECTS WIDESPREAD BUT MUSCLE-PREDOMINANT EXPRESSION IN TRANSGENIC MICE

In order to identify regulatory elements that direct widespread in viv o expression of a linked gene, we have examined one of the human aldol ase A alternative promoters, the ubiquitous pH promoter, which is acti ve in most foetal and adult tissues. We have used the pH promoter regi on to drive expression of an heterologous CAT reporter gene in transge nic mice. We show that a short 820 bp pH promoter fragment is able to confer a ubiquitous and reproducible activity pattern on the CAT repor ter gene in most of the transgenic lines analysed, with a particularly high level of expression in adult skeletal muscle. Activity of this t ransgene was detected from early embryonic stages. Therefore, this pH promoter region appears to be a powerful tool to direct ubiquitous and early expression of a transgene in vivo. Deletion analysis revealed t hat: (i) the region between -651 and -369 bp relative to the pH promot er transcription start site includes DNA elements capable of overridin g effects of the surrounding chromatin at the integration site, (ii) t he region between -285 and -211 bp is involved in pH promoter tissue-s pecific expression pattern in skeletal muscle and/or nervous tissues, (iii) the region located between -211 and -108 bp is necessary for its ubiquitous and muscle-predominant activity and (iv) the most proximal region downstream from -108 bp is still sufficient to confer an activ ity in brain and lung.