Human T-cell leukemia/lymphoma virus type 1 nonstructural genes and their functions

Abstract

The human T-cell leukemia/lymphoma virus (HTLV) genome, in addition to the structural Gag and Env proteins and retroviral enzymes, carries a region at its 3 0 end originally designated pX. To date, we know that this region encodes two essential transcriptional and posttranscriptional positive regulators of viral expression, the Tax and Rex proteins, respectively (reviewed elsewhere in this issue). Here, we will review current knowledge of the functions of three additional proteins encoded in the pX region, p12 I , p13 II , and p30 II .

Effects of valproate on Tax and HBZ expression in HTLV-1 and HAM/TSP T lymphocytes

“…Although the chronology in HAM/TSP cells is consistent with the hypothesis of a feedback loop coordinating Tax and HBZ expressions, we cannot exclude that in ACs the observed concomitant Tax-expression decrease and HBZ-expression increase are not related to cellular mechanisms or perhaps involve other HTLV-1 auxiliary proteins, for example, p30 or Rex. 23 Indeed, as shown in Figure 6, expression of Tax and HBZ were regulated differently in infected cells from AC and TSP/HAM patients.We analyzed VPA impact on the balance of Tax/HBZ-mRNA expression in freshly cultured cells. VPA significantly enhanced but also prolonged Tax-mRNA levels.…”

Mechanisms of HTLV-1 persistence and transformation

“…p12 localises to the endoplasmic reticulum (ER) and regulates calcium-dependent signalling thereby activating nuclear factor of activated T-cell (NFAT) (Nicot et al, 2005). p12 also increases STAT5 transcriptional activity by interacting with the interleukin 2 receptor (IL2R).…”

“…In addition, p30 modulates expression of cellular genes involved in T-cell activation, apoptosis and cell cycle regulation through complex formation with p300/ CBP and TIP60 (Nicot et al, 2005).…”

Effects of human T‐cell leukemia virus type 1 (HTLV‐1) p13 on mitochondrial K+ permeability: A new member of the viroporin family?

“…The present review focuses on p13, an 87-amino acid mitochondrial protein coded by the HTLV-1 x-II ORF from a singly spliced mRNA [2][3][4]. Fig.…”

“…Expression of these partially overlapping ORFs is accessed through alternative splicing and multicistronic translation. Proteins coded in the X region play key roles in the control of viral gene expression and host cell turnover [2]. The ability of HTLV-1 to immortalize T-cells is attributable primarily to the X-region protein Tax, which, in addition to transactivating the viral promoter, affects the expression and function of cellular genes controlling signal transduction, cell growth, apoptosis and chromosomal stability [1].…”