Poster abstracts
Poster number 10 submitted by Jacob Al-Saleem
Identification and Characterization of Novel Tax-1 Interacting Protein, SNX27, and its Role in HTLV-1 Pathobiology
Jacob Al-Saleem (Center for Retrovirus Research, Department of Veterinary Biosciences, College of Veterinary Medicine,The Ohio State University, Columbus, OH, USA), Nikoloz Shkriabai (Center for Retrovirus Research, Department of Pharmaceutics and Pharmaceutical Chemistry, The Ohio State University, Columbus, OH, USA), Mamuka Kvaratskhelia (Center for Retrovirus Research, Department of Pharmaceutics and Pharmaceutical Chemistry, The Ohio State University, Columbus, OH, USA), Lee Ratner (Division of Oncology, Washington University, St Louis, MO, USA), Patrick L. Green (Center for Retrovirus Research, Department of Veterinary Biosciences, College of Veterinary Medicine, Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Col)
Abstract:
Human T-cell Leukemia Virus Type-1 (HTLV-1) is a complex retrovirus infecting 15-20 million people worldwide, and is the etiological agent of an aggressive malignancy of CD4+ T-cells termed Adult T-Cell Leukemia. By contrast, HTLV-2 is non-pathogenic in humans. Both HTLV-1 and HTLV-2 express related Tax proteins termed Tax-1 and Tax-2, respectively. Studies have revealed that Tax-1 contains a C-terminal post synaptic density protein (PDZ) binding motif (PBM) and a central leucine zipper region (LZR), which are absent in Tax-2. We aim to determine whether each of these domains in Tax-1 are required for protein-protein interactions, and whether they account for differences in protein interactions between Tax-1 and Tax-2. This could prove crucial for differences in pathogenesis of the two viruses. Using Tax-1 mutants that do not possess the PBM or LZR we identified several potential candidates via a mass spectrometry based proteomic screen. One identified protein was Sorting Nexin 27 (SNX27), a member of the sorting nexin family of proteins which are involved in endocytosis and protein trafficking. SNX27 is a unique member of the sorting nexin family in that it contains a PDZ domain. Published literature has shown that SNX27 is involved in GLUT1 recycling from lysosomes to the plasma membrane, and without SNX27 GLUT1 is internalized and degraded. We propose that Tax-1 interaction with SNX27 may alter this SNX27 regulation of GLUT1, which is the receptor molecule for HTLV-1. This modulation could prove beneficial to HTLV-1 since plasma membrane bound receptor molecules have been shown to interfere with virion release and infectivity in other retroviruses, including HIV. We confirmed that Tax-1 interacts with SNX27 through the PDZ domain and that deleting either the PDZ domain from SNX27 or the PBM from Tax-1 resulted in a loss of interaction between the two proteins. We also demonstrated that SNX27 overexpression does not affect Tax-1 transactivation of the viral promoter, but resulted in decreased p19 release into the supernatant from virus producing cells. Our future work will determine the mechanistic role of the SNX27 and Tax-1 interaction in modulation of GLUT1. These studies will further our knowledge on HTLV-1 virus release and infectivity, and may potentially lead to new therapies to prevent infection.
Keywords: HTLV-1, ATL, SNX27