Facilitated DNA transfer to rat submandibular gland in vivo and GRP-Ca gene regulation.

The internalization of DNA can be facilitated by adenovirus infection. Using the replication-deficient adenovirus, Ad-dl312, and a plasmid-based firefly luciferase gene as a reporter, we have optimized the uptake and expression of DNA in rat submandibular glands in vivo. Luciferase expression is transient and peaked at approximately 18 h after infection. Luciferase activity increased with plasmid concentration and was greatest at 10(9) to 10(10) plaque-forming units of Ad-dl312 per gland. We next examined the expression in vivo of plasmids containing deletions of the glutamine/glutamic acid-rich protein (GRP-Ca isoform) gene upstream region linked to a chloramphenicol acetyltransferase (CAT) reporter. Constructs with 9.4, 6.3, and 2.7 kb and 17 base pairs of upstream sequence gave relative CAT activities of 100, 30, 7.6, and 38.5, respectively. With the 9.4-kb GRP-Ca construct, CAT was preferentially expressed in acinar cells, which is characteristic of GRP. This gene transfer approach should prove useful in the further study of gene expression in salivary glands and other organs.