Cyclosporin A Associated Helicase-Like Protein Facilitates the Association of Hepatitis C Virus RNA Polymerase with Its Cellular Cyclophilin B

BACKGROUND: Cyclosporin A (CsA) is well known as an immunosuppressive drug useful for allogeneic transplantation. It has been reported that CsA inhibits hepatitis C virus (HCV) genome replication, which indicates that cellular targets of CsA regulate the viral replication. However, the regulation mechanisms of HCV replication governed by CsA target proteins have not been fully understood. PRINCIPAL FINDINGS: Here we show a chemical biology approach that elucidates a novel mechanism of HCV replication. We developed a phage display screening to investigate compound-peptide interaction and identified a novel cellular target molecule of CsA. This protein, named CsA associated helicase-like protein (CAHL), possessed RNA-dependent ATPase activity that was negated by treatment with CsA. The downregulation of CAHL in the cells resulted in a decrease of HCV genome replication. CAHL formed a complex with HCV-derived RNA polymerase NS5B and host-derived cyclophilin B (CyPB), known as a cellular cofactor for HCV replication, to regulate NS5B-CyPB interaction. CONCLUSIONS: We found a cellular factor, CAHL, as CsA associated helicase-like protein, which would form trimer complex with CyPB and NS5B of HCV. The strategy using a chemical compound and identifying its target molecule by our phage display analysis is useful to reveal a novel mechanism underlying cellular and viral physiology

Arabidopsis DEAD-box RNA helicase UAP56 interacts with both RNA and DNA as well as with mRNA export factors

The DEAD-box protein UAP56 (U2AF65-associcated protein) is an RNA helicase that in yeast and metazoa is critically involved in mRNA splicing and export. In Arabidopsis, two adjacent genes code for an identical UAP56 protein, and both genes are expressed. In case one of the genes is inactivated by a T-DNA insertion, wild type transcript level is maintained by the other intact gene. In contrast to other organisms that are severely affected by elevated UAP56 levels, Arabidopsis plants that overexpress UAP56 have wild type appearance. UAP56 localises predominantly to euchromatic regions of Arabidopsis nuclei, and associates with genes transcribed by RNA polymerase II independently from the presence of introns, while it is not detected at non-transcribed loci. Biochemical characterisation revealed that in addition to ssRNA and dsRNA, UAP56 interacts with dsDNA, but not with ssDNA. Moreover, the enzyme displays ATPase activity that is stimulated by RNA and dsDNA and it has ATP-dependent RNA helicase activity unwinding dsRNA, whereas it does not unwind dsDNA. Protein interaction studies showed that UAP56 directly interacts with the mRNA export factors ALY2 and MOS11, suggesting that it is involved in mRNA export from plant cell nuclei

Chemotherapy-related amenorrhea after adjuvant paclitaxel–trastuzumab (APT trial)

PURPOSE: Chemotherapy-related amenorrhea (CRA) is associated with infertility and menopausal symptoms. Learning how frequently paclitaxel and trastuzumab cause amenorrhea is important. Most other adjuvant breast cancer therapies induce CRA in approximately 50% of all premenopausal recipients [1]. METHODS: 410 patients enrolled on the APT Trial, a single-arm phase 2 adjuvant study of 12 weeks of paclitaxel and trastuzumab followed by nine months of trastuzumab monotherapy. Eligible patients had ≤3cm node-negative HER2+ breast cancers. Premenopausal enrollees were asked to complete menstrual surveys every 3-12 months for 72 months. Women who responded to at least one survey at least 15 months after chemotherapy initiation (and who did not undergo hysterectomy and/or bilateral oophorectomy or receive ovarian suppressing medications prior to 15 months) were included in this analysis. A participant was defined as having amenorrhea in follow-up if her self-reported last menstrual period at last follow-up was greater than 12 months prior to the survey. RESULTS: Among the 64 women in the evaluable population (median age at study entry 44 years, range 27-52 years), the median time between chemotherapy initiation and last menstrual survey was 51 months (range 16-79). 18 of 64 women (28%, 95% CI 18-41%) were amenorrheic at that time point. CONCLUSIONS: Amenorrhea rates among premenopausal women treated with adjuvant paclitaxel and trastuzumab for early stage breast cancer appear lower than those seen historically with standard alkylator-based breast cancer regimens. Future studies are needed to understand the impact of this regimen on related issues of fertility and menopausal symptoms

Systematic identification of factors involved in post-transcriptional processes in wheat grain

The original publication can be found at www.springerlink.comPost-transcriptional processing of primary transcripts can significantly affect both the quantity and the structure of mature mRNAs and the corresponding protein products. It is an important mechanism of gene regulation in animals, yeast and plants. Here we have investigated the interactive networks of pre-mRNA processing factors in the developing grain of wheat (Triticum aestivum), one of the world’s major food staples. As a first step we isolated a homologue of the plant specific AtRSZ33 splicing factor, which has been shown to be involved in the early stages of embryo development in Arabidopsis. Real-time PCR showed that the wheat gene, designated TaRSZ38, is expressed mainly in young, developing organs (flowers, root, stem), and expression peaks in immature grain. In situ hybridization and immunodetection revealed preferential abundance of TaRSZ38 in mitotically active tissues of the major storage organ of the grain, the endosperm. The protein encoded by TaRSZ38 was subsequently used as a starting bait in a two-hybrid screen to identify additional factors in grain that are involved in pre-mRNA processing. Most of the identified proteins showed high homology to known splicing factors and splicing related proteins, supporting a role for TaRSZ38 in spliceosome formation and 5′ site selection. Several clones were selected as baits in further yeast two-hybrid screens. In total, cDNAs for 16 proteins were isolated. Among these proteins, TaRSZ22, TaSRp30, TaU1-70K, and the large and small subunits of TaU2AF, are wheat homologues of known plant splicing factors. Several, additional proteins are novel for plants and show homology to known pre-mRNA splicing, splicing related and mRNA export factors from yeast and mammals.Sergiy Lopato, Ljudmilla Borisjuk, Andrew S. Milligan, Neil Shirley, Natalia Bazanova and Peter Langridg