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Published on: August 25, 2017
Molecular mechanisms of cellular transformation by HTLV-1 Tax
Ralph Grassmann1, Mordechai Aboud, Kuan-Teh Jeang
1Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, Germany. Ralph.Grassmann@viro.med.uni-erlangen.de
Abstract:
The HTLV Tax protein is crucial for viral replication and for initiating malignant transformation leading to the development of adult T-cell leukemia. Tax has been shown to be oncogenic, since it transforms and immortalizes rodent fibroblasts and human T-lymphocytes. Through CREB, NF-kappaB and SRF pathways Tax transactivates cellular promoters including those of cytokines (IL-13, IL-15), cytokine receptors (IL-2Ralpha) and costimulatory surface receptors (OX40/OX40L) leading to upregulated protein expression and activated signaling cascades (e.g. Jak/STAT, PI3Kinase, JNK). Tax also stimulates cell growth by direct binding to cyclin-dependent kinase holenzymes and/or inactivating tumor suppressors (e.g. p53, DLG). Moreover, Tax silences cellular checkpoints, which guard against DNA structural damage and chromosomal missegregation, thereby favoring the manifestation of a mutator phenotype in cells.
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