HIV-1 suppressive sequences are modulated by Rev transport of unspliced RNA and are required for efficient HIV-1 production.

The unspliced human immunodeficiency virus type 1 (HIV-1) RNAs are translated as Gag and Gag-Pol polyproteins or packaged as genomes into viral particles. Efficient translation is necessary before the transition to produce infective virions. The viral protein Rev exports all intron-containing viral RNAs; however, it also appears to enhance translation.

Evaluating target silencing by short hairpin RNA mediated by the group I intron in cultured mammalian cells.

Background: The group I intron, a ribozyme that catalyzes its own splicing reactions in the absence of proteins in vitro, is a potential target for rational engineering and attracted our interest due to its potential utility in gene repair using trans-splicing. However, the ribozyme activity of a group I intron appears to be facilitated by RNA chaperones in vivo; therefore, the efficiency of self-splicing could be dependent on the structure around the insert site or the length of the sequence to be inserted. To better understand how ribozyme activity could be modulated in cultured mammalian cells, a group I intron was inserted into a short hairpin RNA (shRNA), and silencing of a reporter gene by the shRNA was estimated to reflect self-splicing activity in vivo.

Expression of shRNA using intron splicing.

RNA is considered a highly promising candidate for several applications such as gene knock-down, gene repair and gene therapy, where double-stranded RNA and RNA with catalytic activity are key players. A group I intron, a ribozyme catalyzing its own splicing reactions in the absence of any proteins, has generated interest for its potential utility in gene repair using trans-splicing. On the other hand, the induction of small interfering RNA, via double-stranded RNA cleavage in short hairpin RNA (shRNA) by the RNase* *enzyme DICER is a convenient and powerful mechanism for gene silencing.

Bhc-cNMPs as either water-soluble or membrane-permeant photoreleasable cyclic nucleotides for both one- and two-photon excitation.

Cyclic nucleoside monophosphates (cNMPs) play key roles in many cellular regulatory processes, such as growth, differentiation, motility, and gene expression. Caged derivatives that can be activated by irradiation could be powerful tools for studying such diverse functions of intracellular second messengers, since the spatiotemporal dynamics of these molecules can be controlled by irradiation with appropriately focused light. Here we report the synthesis, photochemistry, and biological testing of 6-bromo-7-hydroxycoumarin-4-ylmethyl esters of cNMP (Bhc-cNMP) and their acetyl derivatives (Bhc-cNMP/Ac) as new caged second messengers.

Nuclear translocation of mouse polycomb m33 protein in regenerating liver.

Immunoblots probed with an antibody to M33 protein, a homolog of Drosophila Polycomb, revealed that most M33 in adult mouse liver had a higher electrophoretic mobility than that in F9 embryonal carcinoma cells. High-mobility 60-kDa M33 localized in the cytoplasmic fraction of liver homogenates, and two less abundant 66- and 70-kDa species were detected in the nuclear fraction. Immunocytochemistry of freeze-substituted tissues showed a punctate pattern of immunofluorescence in the cytoplasm of hepatic parenchymal cells.