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Cellular tRNALys-3 serves as the primer for reverse transcription of human immunodeficiency virus, type 1 (HIV-1). tRNALys-3 interacts directly with HIV-1 reverse transcriptase, is packaged into viral particles and anneals to the primer-binding site (PBS) of the HIV-1 genome to initiate reverse transcription. Therefore, the priming step of reverse transcription is a potential target for antiviral strategies. We have developed a mutant tRNALys-3 derivative with mutations in the PBS-binding region such that priming specificity was re-directed to the highly conserved TAR stem-loop region. This mutant tRNA retains high-affinity binding to HIV-1 reverse transcriptase, viral encapsidation, and is able to prime at both the targeted TAR sequence and at the viral PBS. Constitutive expression of mutant tRNA in T-cells results in marked inhibition of HIV-1 replication, as determined by measurements of viral infectivity, syncytium formation, and p24 production. Inhibition of retroviral replication through interference with the normal process of priming constitutes a new anti-retroviral approach and also provides a novel tool for dissecting molecular aspects of priming.

Departmental sources Background:Oxidative stress and myocardial apoptosis are features of doxorubicin-induced cardiac toxicity that can result in cardiac dysfunction. Previous studies showed that microRNA-143 (miR-143) was expressed in the myocardium and had a role in cardiac function. This study aimed to investigate the effects and possible molecular mechanisms of miR-143 on oxidative stress and myocardial cell apoptosis in a mouse model of doxorubicininduced cardiac toxicity. Material/Methods:Mice underwent intraperitoneal injection of doxorubicin (15 mg/kg) daily for eight days to develop the mouse model of doxorubicin-induced cardiac toxicity. Four days before doxorubicin administration, a group of mice was pretreated daily with a miR-143 antagonist (25 mg/kg/day) for four consecutive days by tail vein injection.The study included the use of a miR-143 antagomir, or anti-microRNA, an oligonucleotide that silenced endogenous microRNA (miR), and an agomir to miR-143, and also the AKT inhibitor, MK2206. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunoblot analysis were used to measure mRNA and protein expression, respectively. Results:Doxorubicin treatment increased the expression of miR-143, which was reduced by the miR-143 antagomir. Overexpression of miR-143 increased doxorubicin-induced myocardial apoptosis and oxidative stress. The use of the miR-143 antagomir significantly activated protein kinase B (PKB) and AKT, which were reduced in the presence of the AKT inhibitor, MK2206. However, the use of the miR-143 antagomir further down-regulated AKT phosphorylation following doxorubicin treatment and increased AKT activation. Conclusions:In a mouse model of doxorubicin-induced cardiac toxicity, miR-143 increased oxidative stress and myocardial cell apoptosis following doxorubicin treatment by inhibiting AKT.

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The Rex protein is an essential regulator of RNA expression in human T-cell leukemia virus types 1 and 2 (HTLV-1 and HTLV-2) that promotes the accumulation of full-length and partially spliced viral transcripts in the cytoplasm. Rex-mediated regulation correlates with specific binding to a cognate RNA recognition element which overlaps the 5 splice site in the viral long terminal repeat. It has been unclear whether Rex directly affects splicing or only nuclear-to-cytoplasmic transport of viral mRNA. We demonstrate that HTLV-2 Rex is a potent inhibitor of splicing in vitro at an early step in spliceosome assembly. Inhibition requires phosphorylation of Rex and the ability of Rex to bind to the Rex response element. Direct inhibition of early spliceosome assembly by Rex may account for differential accumulation of unspliced transcripts and represents a novel mechanism of retroviral gene regulation. MATERIALS AND METHODSConstruction of splicing vectors. (i) HTLV-2 splicing constructs. All HTLV-2 splice donors were subcloned into recipient plasmid pBSA (a gift from J. D. Reilly and Mary Edmonds, University of Pittsburgh) restricted with BamHI and EcoRI or EcoRV. Inserts were derived as follows: LTR SD (nucleotides [nt] 361 to 786) was derived from pGEM 361-786 (4) cut with BamHI and EcoRI, LTR ⌬SD (nt 361 to 786, s449,450) was derived from pM13 LII 361-786 s449,450 (2) restricted with BamHI and EcoRI, LTR ⌬CRS (nt 361 to 520) was derived from plasmid pM13 LII 361-520 (4) digested with BamHI and SmaI, and LTR SD⌬RxRE (nt 361 to 786⌬465-501 [⌬ indicates deletion]) was derived from plasmid pM13 LII 361-786⌬465-501 (4) digested with BamHI and EcoRI. The LTR U1 (nt 361 to 786 s447,448,456) construct was derived by site-directed mutagenesis (Amersham) using a 28-nt oligonucleotide (CTGAGAGGATACT TACCTGGGGAGGAGC) and pM13 LII 361-786 as the substrate, confirmed by dideoxy nucleotide sequencing, and subcloned as a BamHI-EcoRI fragment into pBSA. The env SD construct (nt 5090 to 5810, splice donor at nt 5183) was derived from the HTLV-2 subclone pH6B 3.5 digested with BamHI and PvuII. Splicing vectors are outlined in Fig. 1A. (ii) Multimerization of stem-bulge-loop sequences. The minimal RxRE was synthesized by annealing complementary oligonucleotides comprising nt 458 to 507 of the 5Ј LTR of HTLV-2 (5Ј-GGGCCTCTCAGGTCGAGCTCGGCTGC CCCTTAGGTAGTCGCTCCCCGAGGGTCTTT-3Ј) adapted with restriction half sites of SmaI at the 5Ј end and DraI at the 3Ј end. The annealed product was purified by electrophoresis on 2% low-melting-point NuSieve agarose in 1ϫ Tris-acetate-EDTA and then subjected to excision and DNA extraction. The precipitated DNA was resuspended in 1ϫ ligation buffer and ligated overnight at 16ЊC in the presence of 0.5 mM ATP, 3 U of T4 DNA ligase, and 10 U each of SmaI and DraI. Ligation products were phenol extracted, ethanol precipitated, and resolved on a 2% low-melting-point agarose gel in 1ϫ Tris-agarose-EDTA. Discrete bands, corresponding to products ranging from one to eight monomers, were gel purified and incubated i...

TZYGD is effective and highly safe in treating non-alcoholic fatty liver.

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