Polyomavirus middle T antigen downregulates junctional cell-to-cell communication.

We examined the effect of polyomavirus middle T antigen on cell-to-cell communication in rat F cells transfected with an inducible middle T recombinant DNA or infected with a conditional mutant virus. Junctional permeability fell (reversibly) when middle T transcription was induced or when middle T was switched to the transformation+ form. The effect correlates with the rise of protein tyrosine kinase activity.