Ago1 and Ago2 differentially affect cell proliferation, motility and apoptosis when overexpressed in SH-SY5Y neuroblastoma cells.

Argonaute are a conserved class of proteins central to the microRNA pathway. We have highlighted a novel and non-redundant function of Ago1 versus Ago2; the two core factors of the miRNA-associated RISC complex. Stable overexpression of Ago1 in neuroblastoma cells causes the cell cycle to slow down, a decrease in cellular motility and a stronger apoptotic response upon UV irradiation. These effects, together with a significant increase in p53 levels, suggest that Ago1 may act as a tumor-suppressor factor, a function also supported by GEO Profiles microarrays that inversely correlate Ago1 expression levels with cell proliferation rates.

RISC activity in hippocampus is essential for contextual memory.

RNA-Induced Silencing Complex (RISC) mediates post-transcriptional control of gene expression and contains Argonaute 2 (AGO2) protein as a central effector of cleavage or inhibition of mRNA translation. In the brain, the RISC pathway is involved in neuronal functions, such as synaptic development and local protein synthesis, which are potentially critical for memory. In this study, we examined the role of RISC in memory formation in rodents, by silencing AGO2 expression in dorsal hippocampus of C57BL/6 mice and submitting animals to hippocampus-related tasks. One week after surgery, AGO2 downregulation impaired both short-term and long-term contextual fear memories. Conversely, no long-lasting effects were observed three weeks after surgery, when AGO2 levels were re-established. These results show that altered RISC activity severely affects learning and memory processes in rodents.

The artificial gene Jazz, a transcriptional regulator of utrophin, corrects the dystrophic pathology in mdx mice.

The absence of the cytoskeletal protein dystrophin results in Duchenne muscular dystrophy (DMD). The utrophin protein is the best candidate for dystrophin replacement in DMD patients. To obtain therapeutic levels of utrophin expression in dystrophic muscle, we developed an alternative strategy based on the use of artificial zinc finger transcription factors (ZF ATFs). The ZF ATF 'Jazz' was recently engineered and tested in vivo by generating a transgenic mouse specifically expressing Jazz at the muscular level. To validate the ZF ATF technology for DMD treatment we generated a second mouse model by crossing Jazz-transgenic mice with dystrophin-deficient mdx mice. Here, we show that the artificial Jazz protein restores sarcolemmal integrity and prevents the development of the dystrophic disease in mdx mice. This exclusive animal model establishes the notion that utrophin-based therapy for DMD can be efficiently developed using ZF ATF technology and candidates Jazz as a novel therapeutic molecule for DMD therapy.

The eEF1γ subunit contacts RNA polymerase II and binds vimentin promoter region.

Here, we show that the eukaryotic translation elongation factor 1 gamma (eEF1γ) physically interacts with the RNA polymerase II (pol II) core subunit 3 (RPB3), both in isolation and in the context of the holo-enzyme. Importantly, eEF1γ has been recently shown to bind Vimentin mRNA. By chromatin immunoprecipitation experiments, we demonstrate, for the first time, that eEF1γ is also physically present on the genomic locus corresponding to the promoter region of human Vimentin gene. The eEF1γ depletion causes the Vimentin protein to be incorrectly compartmentalised and to severely compromise cellular shape and mitochondria localisation. We demonstrate that eEF1γ partially colocalises with the mitochondrial marker Tom20 and that eEF1γ depletion increases mitochondrial superoxide generation as well as the total levels of carbonylated proteins. Finally, we hypothesise that eEF1γ, in addition to its role in translation elongation complex, is involved in regulating Vimentin gene by contacting both pol II and the Vimentin promoter region and then shuttling/nursing the Vimentin mRNA from its gene locus to its appropriate cellular compartment for translation.