Activation of expression of genes coding for extracellular matrix proteins in Tat-producing glioblastoma cells.

The Tat protein of human immunodeficiency virus type 1 has been increasingly implicated in directly contributing to the disease AIDS by altering the expression of strategic cellular genes. In this study we demonstrate that the presence of the human immunodeficiency virus type 1 regulatory protein Tat is associated with a significant induction in the expression of certain protein components of the extracellular matrix in glial-derived cells. Northern blot analysis reveals that in cells expressing Tat there is a marked elevation in the steady-state RNA levels for fibronectin and types I and III collagen. Metabolic labeling of the Tat-producing cells demonstrates that this induction is also reflected at the level of protein synthesis. Transient transfection experiments indicate that the presence of Tat results in increased transcription of fibronectin and alpha I type I collagen promoters. Possible mechanisms for this phenomenon and their significance with regard to AIDS are discussed.