Search results for "RNA interference"
showing 10 items of 202 documents
Apoptosis induced by a HIPK2 full-length-specific siRNA is due to off-target effects rather than prevalence of HIPK2-Δe8 isoform
2017
Small interfering RNAs (siRNAs) are widely used to study gene function and extensively exploited for their potential therapeutic applications. HIPK2 is an evolutionary conserved kinase that binds and phosphorylates several proteins directly or indirectly related to apoptosis. Recently, an alternatively spliced isoform skipping 81 nucleotides of exon 8 (Hipk2-Δe8) has been described. Selective depletion of Hipk2 full-length (Hipk2-FL) with a specific siRNA that spares the Hipk2-Δe8 isoform has been shown to strongly induce apoptosis, suggesting an unpredicted dominant-negative effect of Hipk2-FL over the Δe8 isoform. From this observation, we sought to take advantage and assessed the therape…
From “Cellular” RNA to “Smart” RNA: Multiple Roles of RNA in Genome Stability and Beyond
2018
Coding for proteins has been considered the main function of RNA since the "central dogma" of biology was proposed. The discovery of noncoding transcripts shed light on additional roles of RNA, ranging from the support of polypeptide synthesis, to the assembly of subnuclear structures, to gene expression modulation. Cellular RNA has therefore been recognized as a central player in often unanticipated biological processes, including genomic stability. This ever-expanding list of functions inspired us to think of RNA as a "smart" phone, which has replaced the older obsolete "cellular" phone. In this review, we summarize the last two decades of advances in research on the interface between RNA…
Rab33B Controls Hepatitis B Virus Assembly by Regulating Core Membrane Association and Nucleocapsid Processing
2017
Many viruses take advantage of cellular trafficking machineries to assemble and release new infectious particles. Using RNA interference (RNAi), we demonstrate that the Golgi/autophagosome-associated Rab33B is required for hepatitis B virus (HBV) propagation in hepatoma cell lines. While Rab33B is dispensable for the secretion of HBV subviral envelope particles, its knockdown reduced the virus yield to 20% and inhibited nucleocapsid (NC) formation and/or NC trafficking. The overexpression of a GDP-restricted Rab33B mutant phenocopied the effect of deficit Rab33B, indicating that Rab33B-specific effector proteins may be involved. Moreover, we found that HBV replication enhanced Rab33B expres…
Tetraspanin CD151 Promotes Initial Events in Human Cytomegalovirus Infection.
2016
ABSTRACT Human cytomegalovirus (HCMV), a betaherpesvirus, can cause life-threatening disease in immunocompromised individuals. Viral envelope glycoproteins that mediate binding to and penetration into target cells have been identified previously. In contrast, cellular proteins supporting HCMV during entry are largely unknown. In order to systematically identify host genes affecting initial steps of HCMV infection, a targeted RNA interference screen of 96 cellular genes was performed in endothelial cells by use of a virus strain expressing the full set of known glycoprotein H and L (gH/gL) complexes. The approach yielded five proviral host factors from different protein families and eight an…
Noncanonical GLI1 signaling promotes stemness features and in vivo growth in lung adenocarcinoma
2016
Aberrant Hedgehog/GLI signaling has been implicated in a diverse spectrum of human cancers, but its role in lung adenocarcinoma (LAC) is still under debate. We show that the downstream effector of the Hedgehog pathway, GLI1, is expressed in 76% of LACs, but in roughly half of these tumors, the canonical pathway activator, Smoothened, is expressed at low levels, possibly owing to epigenetic silencing. In LAC cells including the cancer stem cell compartment, we show that GLI1 is activated noncanonically by MAPK/ERK signaling. Different mechanisms can trigger the MAPK/ERK/GLI1 cascade including KRAS mutation and stimulation of NRP2 by VEGF produced by the cancer cells themselves in an autocrin…
PTEN status is a crucial determinant of the functional outcome of combined MEK and mTOR inhibition in cancer
2017
AbstractCombined MAPK/PI3K pathway inhibition represents an attractive, albeit toxic, therapeutic strategy in oncology. Since PTEN lies at the intersection of these two pathways, we investigated whether PTEN status determines the functional response to combined pathway inhibition. PTEN (gene, mRNA, and protein) status was extensively characterized in a panel of cancer cell lines and combined MEK/mTOR inhibition displayed highly synergistic pharmacologic interactions almost exclusively in PTEN-loss models. Genetic manipulation of PTEN status confirmed a mechanistic role for PTEN in determining the functional outcome of combined pathway blockade. Proteomic analysis showed greater phosphoprote…
Knockdown of Drosophila hemoglobin suggests a role in O2 homeostasis.
2016
Almost all insects are equipped with a tracheal system, which appears to be sufficient for O2 supply even in phases of high metabolic activity. Therefore, with the exception of a few species dwelling in hypoxic habitats, specialized respiratory proteins had been considered unnecessary in insects. The recent discovery and apparently universal presence of intracellular hemoglobins in insects has remained functionally unexplained. The fruitfly Drosophila melanogaster harbors three different globin genes (referred to as glob1-3). Glob1 is the most highly expressed globin and essentially occurs in the tracheal system and the fat body. To better understand the functions of insect globins, the lev…
Dysfunctional mitochondrial fission impairs cell reprogramming
2016
We have recently shown that mitochondrial fission is induced early in reprogramming in a Drp1-dependent manner; however, the identity of the factors controlling Drp1 recruitment to mitochondria was unexplored. To investigate this, we used a panel of RNAi targeting factors involved in the regulation of mitochondrial dynamics and we observed that MiD51, Gdap1 and, to a lesser extent, Mff were found to play key roles in this process. Cells derived from Gdap1-null mice were used to further explore the role of this factor in cell reprogramming. Microarray data revealed a prominent down-regulation of cell cycle pathways in Gdap1-null cells early in reprogramming and cell cycle profiling uncovered…
An siRNA-based screen in C2C12 myoblasts identifies novel genes involved in myogenic differentiation
2017
International audience; AbstractMyogenesis is a highly regulated multi-step process involving myoblast proliferation and differentiation. Although studies over the last decades have identified several factors governing these distinct major phases, many of them are not yet known. In order to identify novel genes, we took advantage of the C2C12 myoblastic line to establish a functional siRNA screen combined with quantitative-imaging analysis of a large amount of differentiated myoblasts. We knocked down 100 preselected mouse genes without a previously characterized role in muscle. Using image analysis, we tracked gene-silencing phenotypes by quantitative assessment of cellular density, myotub…
Engineered Functional Redundancy Relaxes Selective Constraints upon Endogenous Genes in Viral RNA Genomes
2018
Functional redundancy, understood as the functional overlap of different genes, is a double-edge sword. At the one side, it is thought to serve as a robustness mechanism that buffers the deleterious effect of mutations hitting one of the redundant copies, thus resulting in pseudogenization. At the other side, it is considered as a source of genetic and functional innovation. In any case, genetically redundant genes are expected to show an acceleration in the rate of molecular evolution. Here, we tackle the role of functional redundancy in viral RNA genomes. To this end, we have evaluated the rates of compensatory evolution for deleterious mutations affecting an essential function, the suppr…