Interaction of human dipeptidyl peptidase IV and human immunodeficiency virus type-1 transcription transactivator in <it>Sf9 </it>cells

• Main Authors: Reutter Werner, Tauber Rudolf, Berger Markus, Blanchard Véronique, Tansi Felista L, Fan Hua
• Format: Article
• Language: English
• Published: BMC 2010-10-01
• Series: Virology Journal
• Online Access: http://www.virologyj.com/content/7/1/267

<p>Abstract</p> <p>Background</p> <p>Dipeptidyl peptidase IV (DPPIV) also known as the T cell activation marker CD26 is a multifunctional protein which is involved in various biological processes. The association of human-DPPIV with components of the human immunodeficiency virus type-1 (HIV1) is well documented and raised some discussions. Several reports implicated the interaction of human-DPPIV with the HIV1 transcription transactivator protein (HIV1-Tat) and the inhibition of the dipeptidyl peptidase activity of DPPIV by the HIV1-Tat protein. Furthermore, enzyme kinetic data implied another binding site for the HIV1-Tat other than the active centre of DPPIV. However, the biological significance of this interaction of the HIV1-Tat protein and human-DPPIV has not been studied, yet. Therefore, we focused on the interaction of HIV1-Tat protein with DPPIV and investigated the subsequent biological consequences of this interaction in <it>Spodoptera frugiperda </it>cells, using the BAC-TO-BAC baculovirus system.</p> <p>Results</p> <p>The HIV1-Tat protein (Tat-<it>BRU</it>) co-localized and co-immunoprecipitated with human-DPPIV protein, following co-expression in the baculovirus-driven <it>Sf9 </it>cell expression system. Furthermore, tyrosine phosphorylation of DPPIV protein was up-regulated in Tat/DPPIV-co-expressing cells after 72 h culturing and also in DPPIV-expressing <it>Sf9 </it>cells after application of purified recombinant Tat protein. As opposed to the expression of Tat alone, serine phosphorylation of the Tat protein was decreased when co-expressed with human-DPPIV protein.</p> <p>Conclusions</p> <p>We show for the first time that human-DPPIV and HIV1-Tat co-immunoprecipitate. Furthermore, our findings indicate that the interaction of HIV1-Tat and human-DPPIV may be involved in signalling platforms that regulate the biological function of both human-DPPIV and HIV1-Tat.</p>