SPECIFIC-INHIBITION OF A HUMAN PAPILLOMAVIRUS E2 TRANSACTIVATOR BY INTRACELLULAR DELIVERY OF ITS REPRESSOR

Papillomaviruses are the causative agents of benign and malignant epit helial tumors of the skin and mucosa. They encode a DNA-binding protei n, E2, that regulates viral transcription and replication, making it a n important therapeutic target. By deleting the amino-terminal trans-a ctivation domain of human papillomavirus type 16 (HPV-16) E2 while ret aining its carboxy-terminal DNA binding and dimerization domain, an E2 repressor (E2R) that efficiently inhibits transcriptional activation by full-length HPV E2 was generated. To deliver this repressor protein into animal cells, we have utilized the human immunodeficiency virus type 1 (HIV-1) Tat protein which itself is taken up efficiently into i ntact cells. Chimeras of E2R and the cellular uptake domain of Tat spe cifically inhibited E2-dependent reporter gene expression in COS-7 cel ls. Treatment of cervical intraepithelial neoplasia cells having episo mally replicating HPV-31 DNA with this Tat-E2R protein led to a dose-d ependent loss of HPV DNA copies and inhibition of cell growth. Tat-med iated delivery can be a valuable tool for assessing protein function a nd may allow the development of novel therapeutic proteins having intr acellular targets.