Transduction of TAT-HA-beta-galactosidase fusion protein into salivary gland-derived cells and organ cultures of the developing gland, and into rat submandibular gland in vivo

We have studied the transduction of TAT-HA-beta -galactosidase fusion prote in into two cell lines of rat salivary gland origin, A5 and C6-21, into cel ls of fetal mouse submandibular glands in organ culture, and into rat subma ndibular gland after retrograde duct injection, using a histochemical metho d to demonstrate beta -galactosidase activity. Transduction of the fusion p rotein into A5 and C6-21 cells was concentration- and time-dependent. There fore, the intensity of the beta -galactosidase staining, which was cytoplas mic. was less after 1 hr of exposure compared to exposures up to 24 hr. How ever, the fusion protein was transduced into 100% of both types of cultured cells. When explants of mouse fetuses at 13 days of gestation were exposed to the fusion proteins, both epithelial and mesenchymal cells were stained for the enzyme, with a conspicuous accumulation of the reaction product at perinuclear cytoplasmic regions. The histochemical staining of the mesench ymal cells was more intense compared to that seen in epithelial cells. TAT- HA-beta -galactosidase fusion protein was also delivered to rat submandibul ar glands by retrograde duct injection. Histochemical staining for beta -ga lactosidase activity of cryostat sections prepared from the injected glands revealed that the transduction of the fusion protein was also time- and do se-dependent. In the glands of rats sacrificed from 10 min to 1 hr after th e retrograde injection, essentially all acinar and duct cells showed cytopl asmic staining. The intensity of the staining then declined, and was not se en in the glands of rats killed 24 hr after the injection of the fusion pro teins. These results indicate that a full-length, active TAT fusion protein can be targeted to salivary gland cells both in vitro and in vivo to analy ze physiological, developmental, and pathophysiological processes.