HUMAN JC VIRUS CAMP RESPONSE ELEMENTS FUNCTIONAL FOR ENHANCED GLIAL-CELL EXPRESSION IN DIFFERENTIATING EMBRYONAL CARCINOMA-CELLS

Human JC virus (JCV) is glial cell-specific for growth and expression. This specificity is attributed to the cis-acting sequences of the two 98-bp tandem repeats in the JCV regulatory region. JCV causes brain l esions, especially in AIDS patients. To study the expression of JCV in glial cells, the role of both repeal region TGAGCTCA sequences, which are homologous to the classical TGAGCTCA cAMP response element (CRE), was examined. The effect of the CRE on expression of the JCV early pr omoter (JCV(E)) in response to cAMP was studied with undifferentiated, glial and muscle P19 embryonal carcinoma cells. The results showed a threefold increase in response to cAMP only in the glial cells in whic h JCV is efficiently expressed. The direct in vivo role of the JCV CRE was confirmed by site-directed mutagenesis. Additionally, a CRE oligo nucleotide was induced by cAMP in vivo, and in in vitro transcription assays with glial cell extracts. The early promoter of human BK virus containing nonhomologous CRE sequences was previously shown not to be glial cell-specific and failed to respond to cAMP in glial P19 cells i n this study. Mobility shift assays showed the cAMP-induced in vitro i nteraction of glial cell protein(s) with the CRE oligonucleotide. Sout hwestern blot and uv crosslinking experiments identified an approximat ely 43-kDa protein interacting with the JCV CRE oligonucleotide. The r esults indicate that the in vivo expression of JCV(E) is specifically increased in response to cAMP only in glial cells and JCV CRE in vitro protein complexes are only detected in response to cAMP for glial cel l extracts. (C) 1996 Academic Press, Inc.