RNAi activity of siRNAs modified with 2'-aminoalkyl-substituted fluorinated nucleobases.

We recently reported that a 1'-deoxy-1'-(4,6-difluoro-1H-benzimidazol-1-yl)-2'-(beta-aminoethyl)-beta-d-ribofuranose nucleoside appears to be a universal nucleoside which does not differentiate between the four natural nucleosides A, C, G, and U in duplexes. Moreover, ribozymes modified with this nucleoside analog showed a better or at least equal catalytic activity relative to Watson-Crick mismatches.[1] Due to these data, we investigated the ability of this compound to tolerate Watson-Crick mismatches in order to avoid HIV escape mutations in RNA interference. The influence of this nucleoside analog on siRNA efficiency was analyzed with a proven siRNA targeting GFP.

Characterization of ZC3H15 as a potential TRAF-2-interacting protein implicated in the NFκB pathway and overexpressed in AML.

The gene product of the zinc finger CCCH-type containing 15 (ZC3H15) gene, an immediate early erythropoietin response gene (synonymous: LEREPO4), was further characterized. ZC3H15 was expressed ubiquitously in all human tissues tested by northern blotting and showed mainly a diffuse cytoplasmic distribution by immune fluorescence microscopy and western blotting of subcellular protein fractions. The expression of ZC3H15 was downregulated effectively in HeLa cells to ≤13% of the control by transfection of specific small interfering RNA (siRNA). Subsequent Affymetrix microarray analysis revealed 202 differentially expressed genes including 114 induced (≥3-fold) genes and 88 suppressed (≤0.3-fold) genes. The gene ontology (GO) categories containing an over-representation of differentially expressed genes comprised cell growth, transcription, cell adhesion, regulation of NF-κB, regulation of MAPK, cell cycle arrest and immune response. ZC3H15 interacted with the signaling adapter protein tumor necrosis factor receptor associated factor 2 (TRAF-2) as shown by co-immunoprecipitation. ZC3H15 expression was found to be significantly increased in acute myeloid leukemia (AML) samples compared to MDS, CML, ALL and normal bone marrow samples using the Leukemia Gene Atlas (LGA) database. Based on these data, it is hypothesized that ZC3H15 may interact with TRAF-2 functionally within the NF-κB pathway, and may be explored as a potential target in AML.

Endoplasmic reticulum protein GliPR1 regulates G protein signaling and the cell cycle and is overexpressed in AML.

Glioma pathogenesis­related protein 1 (GliPR1) is a pleiotropic protein involved in cell proliferation, tumor growth and apoptosis. The aim of the present study was to further characterize GliPR1 in regard to its subcellular localization and its overall effect on cellular gene expression. Knockdown of GliPR1 and Affymetrix microarray mRNA expression analysis revealed 262 GliPR1­dependent differentially expressed genes, of which 40 were induced and 222 were suppressed. Differentially expressed genes were overrepresented in five Gene Ontology categories: G protein signaling pathways, regulation of cyclin­dependent protein kinase activity, ER to Golgi vesicle-mediated transport, axon guidance and dephosphorylation. GliPR1-EGFP fusion protein co­localized with the endoplasmic reticulum (ER) or with cytoplasmic vesicles as demonstrated by confocal microscopy. GliPR1 expression was found to be significantly increased in acute myeloid leukemia (AML) bone marrow samples, while markedly reduced in acute lymphoblastic leukemia, unchanged in myelodysplastic syndrome and slightly decreased in chronic lymphocytic leukemia as well as in chronic myelocytic leukemia (CML) when compared to normal samples. GliPR1 was localized and involved in the ER secretory protein pathway. GliPR1 affects G protein signaling and cell cycle regulation. Based on the observed overexpression in AML samples, GliPR1 should be further explored as a potential target for AML.

Knockdown of ERM family member moesin in host cells increases HIV type 1 replication.

Moesin is a member of the ERM (ezrin, radixin, moesin) family of cytoskeleton/membrane structure organizing and signal transduction proteins. Previously, we found an increased expression of moesin during HIV-1 infection. Moesin was also reported to be incorporated into HIV-1 virions. To analyze whether moesin is a host factor affecting the replication cycle of human immunodeficiency virus type 1 (HIV-1), we used small interfering RNAs (siRNAs) to evaluate the effect of moesin knockdown on HIV-1 replication in P4-CCR5 cells. Moesin's knockdown did not affect the cell viability or cell phenotype. Interestingly, we observed a marked increase in viral replication, as demonstrated by enhanced HIV-1 RNA, p24 antigen, and ß-galactosidase reporter expression. Moesin-dependent enhancement of HIV-1 replication was confirmed in lymphocytic host cells (Jurkat). These results suggest an overall rather restrictive role of moesin for HIV-1 replication in host cells in vitro.