Identification of novel monocistronic HTLV-1 mRNAs encoding functional Rex isoforms

Retrovirology

Vincenzo Ciminale¹  Genoveffa Franchini⁵  Donna M D’Agostino⁶  Valerio W Valeri²  Vibeke Andresen³  Ilaria Cavallari⁴  Francesca Rende⁴ 

[1] Istituto Oncologico Veneto-IRCCS, Padua, Italy;Novartis Vaccines Loc., Bellaria Rosia, Sovicille, 53018, SI, Italy;Translational Hemato-Oncology Group, Department of Clinical Science, Centre of Cancer Biomarkers CCBIO, University of Bergen, Bergen, Norway;Department of Surgery, Oncology and Gastroenterology, University of Padova, Padua, Italy;Animal Models and Retroviral Vaccines Section, National Cancer Institute, Bethesda, MD, USA;Department of Biomedical Sciences, University of Padova, Padua, Italy

关键词: Splicing;    Rex;    HTLV-1;   

Others  :  1221134
DOI  :  10.1186/s12977-015-0184-2

 received in 2015-01-20, accepted in 2015-06-19,  发布年份 2015

【 摘 要 】

Background

Human T cell leukemia virus type 1 (HTLV-1) gene expression is controlled by the key regulatory proteins Tax and Rex. The concerted action of these proteins results in a two-phase kinetics of viral expression that depends on a time delay between their action. However, it is difficult to explain this delay, as Tax and Rex are produced from the same mRNA. In the present study we investigated whether HTLV-1 may produce novel mRNA species capable of expressing Rex and Tax independently.

Findings

Results revealed the expression of three alternatively spliced transcripts coding for novel Rex isoforms in infected cell lines and in primary samples from infected patients. One mRNA coded for a Tax isoform and a Rex isoform, and two mRNAs coded for Rex isoforms but not Tax. Functional assays showed that these Rex isoforms exhibit activity comparable to canonic Rex. An analysis of the temporal expression of these transcripts upon ex vivo culture of cells from infected patients and cell lines transfected with a molecular clone of HTLV-1 revealed early expression of the dicistronic tax/rex mRNAs followed by the monocistronic mRNAs coding for Rex isoforms.

Conclusion

The production of monocistronic HTLV-1 mRNAs encoding Rex isoforms with comparable activity to canonical Rex, but with distinct timing, would support a prolonged duration of Rex function with gradual loss of Tax, and is consistent with the two-phase expression kinetics. A thorough understanding of these regulatory circuits will shed light on the basis of viral latency and provide groundwork to develop strategies for eradicating persistent infections.

【 授权许可】

   
2015 Rende et al.

【 图 表 】

Figure1.

Figure2.

Figure3.

Figure4.

Figure5.

Figure6.

Figure7.

【 参考文献 】

• [1]Goncalves DU, Proietti FA, Ribas JG, Araújo MG, Pinheiro SR, Guedes AC et al.. Epidemiology, treatment, and prevention of human T-cell leukemia virus type 1-associated diseases. Clin Microbiol Rev. 2010; 23(3):577-589.
• [2]Currer R, Van Duyne R, Jaworski E, Guendel I, Sampey G, Das R et al.. HTLV tax: a fascinating multifunctional co-regulator of viral and cellular pathways. Front Microbiol. 2012; 3:406.
• [3]Nakano K, Watanabe T. HTLV-1 Rex: the courier of viral messages making use of the host vehicle. Front Microbiol. 2012; 3:330.
• [4]Hidaka M, Inoue J, Yoshida M, Seiki M. Post-transcriptional regulator (rex) of HTLV-1 initiates expression of viral structural proteins but suppresses expression of regulatory proteins. EMBO J. 1988; 7(2):519-523.
• [5]Rende F, Cavallari I, Corradin A, Silic-Benussi M, Toulza F, Toffolo GM et al.. Kinetics and intracellular compartmentalization of HTLV-1 gene expression: nuclear retention of HBZ mRNA. Blood. 2011; 117:4855-4859.
• [6]Ciminale V, Rende F, Bertazzoni U, Romanelli MG. HTLV-1 and HTLV-2: highly similar viruses with distinct oncogenic properties. Front Microbiol. 2014; 5:398.
• [7]Cavallari I, Rende F, Bender C, Romanelli MG, D’Agostino DM, Ciminale V. Fine tuning of the temporal expression of HTLV-1 and HTLV-2. Front Microbiol. 2013; 4:235.
• [8]Corradin A, DI Camillo B, Rende F, Ciminale V, Toffolo GM, Cobelli C (2010) Retrovirus HTLV-1 gene circuit: a potential oscillator for eukaryotes. Pac Symp Biocomput 421–432
• [9]Kimata JT, Wong FH, Wang JJ, Ratner L. Construction and characterization of infectious human T-cell leukemia virus type 1 molecular clones. Virology. 1994; 204(2):656-664.
• [10]Schwartz S, Felber BK, Benko DM, Fenyö EM, Pavlakis GN. Cloning and functional analysis of multiply spliced mRNA species of human immunodeficiency virus type 1. J Virol. 1990; 64(6):2519-2529.
• [11]Ciminale V, Pavlakis GN, Derse D, Cunningham CP, Felber BK. Complex splicing in the human T-cell leukemia virus (HTLV) family of retroviruses: novel mRNAs and proteins produced by HTLV type I. J Virol. 1992; 66(3):1737-1745.
• [12]Koralnik IJ, Gessain A, Klotman ME, Lo Monico A, Berneman ZN, Franchini G. Protein isoforms encoded by the pX region of human T-cell leukemia/lymphotropic virus type I. Proc Natl Acad Sci USA. 1992; 89(18):8813-8817.
• [13]Rende F, Cavallari I, Romanelli MG, Diani E, Bertazzoni U, Ciminale V. Comparison of the genetic organization, expression strategies and oncogenic potential of HTLV-1 and HTLV-2. Leuk Res Treat. 2012; 2012:876153.
• [14]Popovic M, Lange-Wantzin G, Sarin PS, Mann D, Gallo RC. Transformation of human umbilical cord blood T cells by human T-cell leukemia/lymphoma virus. Proc Natl Acad Sci USA. 1983; 80(17):5402-5406.
• [15]Hanon E, Hall S, Taylor GP, Saito M, Davis R, Tanaka Y et al.. Abundant tax protein expression in CD4+ T cells infected with human T-cell lymphotropic virus type I (HTLV-I) is prevented by cytotoxic T lymphocytes. Blood. 2000; 95(4):1386-1392.
• [16]Bhat NK, Adachi Y, Samuel KP, Derse D. HTLV-1 gene expression by defective proviruses in an infected T-cell line. Virology. 1993; 196(1):15-24.
• [17]Benko DM, Robinson R, Solomin L, Mellini M, Felber BK, Pavlakis GN. Binding of trans-dominant mutant Rev protein of human immunodeficiency virus type 1 to the cis-acting Rev-responsive element does not affect the fate of viral mRNA. New Biol. 1990; 2(12):1111-1122.
• [18]Schwartz S, Felber BK, Pavlakis GN. Distinct RNA sequences in the gag region of human immunodeficiency virus type 1 decrease RNA stability and inhibit expression in the absence of Rev protein. J Virol. 1992; 66(1):150-159.
• [19]Kesic M, Doueiri R, Ward M, Semmes OJ, Green PL. Phosphorylation regulates human T-cell leukemia virus type 1 Rex function. Retrovirology. 2009; 6:105. BioMed Central Full Text
• [20]Narayan M, Younis I, D’Agostino DM, Green PL. Functional domain structure of human T-cell leukemia virus type 2 rex. J Virol. 2003; 77(23):12829-12840.
• [21]Cavallari I, Rende F, D’Agostino DM, Ciminale V. Converging strategies in expression of human complex retroviruses. Viruses. 2011; 3(8):1395-1414.
• [22]Cavallari I, Rende F, Ciminale V. Quantitative analysis of human T-lymphotropic virus type 1 (HTLV-1) gene expression using nucleo-cytoplasmic fractionation and splice junction-specific real-time RT-PCR (qRT-PCR). Hum Retrovir Methods Protoc. 2014; 1087:325-337.