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| Institute: |
Lab or Branch |
| George Washington University Medical Center |
Department of Biochemistry and Molecular
Biology |
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| Title: |
| Protein Profile of Human T-cell Leukemia
Virus Type 1 Viral Activator. |
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| Authors: |
| K. Wu, C. de la Fuente, L. Deng, S. D.
Gitlin, A. Maddukuri, H. Li, A. Vertes, A. Pumfery, F.
Kashanchi |
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| Abstract: |
| Infection with human T-cell leukemia virus
type 1 (HTLV-1) results in adult T-cell leukemia (ATL)
and HTLV-1-associated myelopathy/tropical spastic paraparesis
(HAM/TSP). Tax, a 40 kDa protein, regulates viral and
cellular transcription, host signal transduction, cell
cycle, and apoptosis. Tax has been shown to modulate cellular
CREB and NFkB pathways, however to date its role in binding
to various host cellular proteins involved in tumorogenesis
has not been fully described. Here, we describe the Tax-associated
proteins and their functions in cells through the use
of chromatography, immunoaffinity purification, 2-Dimension
(2-D) gel electrophoresis separation, and MALDI-TOF analysis.
Tax eluted at three peaks from the sizing column, at low
(170 kDa), medium (1,800 kDa), and high (> 4,000 kDa)
molecular weight. One particular fraction, the 1,800 kDa
fraction, was further studied since similar pattern of
expression was observed in other Tax-expressing cells.
Following Tax immunoprecipitation from the 1,800 kDa fraction,
washes with high salt buffer, 2D gel separation, and MALDI-TOF
mass spectrometry analysis, a total of 32 proteins were
identified. Many of these proteins belong to the signal
transduction, cytoskeleton, and transcription/chromatin
remodeling pathways. A few of these proteins, including
TXBP151, have previously been shown to bind to Tax via
two-hybrid systems. Tax's interaction with small GTPase-cytoskeleton
proteins, such as ras GAP1m, Rac1, Cdc42, RhoA and gelsolin,
indicate how Tax may regulate migration, invasion, and
adhesion in T-cell cancers. Finally, Tax's physical and
functional association with the chromatin remodeling SWI/SNF
complex was assessed using in vitro remodeling ChIP assays,
BRG1 mutant cells, and RNAi experiments. Collectively,
Tax, is able to bind and regulate many cellular proteins
that regulate transcription and cytoskeletal related pathways.
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