Regulatory brain cytoplasmic RNAs cooperate with eukaryotic initiation factor 4B to couple translation to receptor activation in support of long-term plastic changes in neurons.

In higher eukaryotes, increasing evidence suggests, gene expression is to a large degree controlled by RNA. Regulatory RNAs have been implicated in the management of neuronal function and plasticity in mammalian brains. However, much of the molecular-mechanistic framework that enables neuronal regulatory RNAs to control gene expression remains poorly understood. Here, we establish molecular mechanisms that underlie the regulatory capacity of neuronal BC RNAs in the translational control of gene expression. We report that regulatory BC RNAs employ a two-pronged approach in translational control. One of two distinct repression mechanisms is mediated by C-loop motifs in BC RNA 3 stem-loop domains. These C-loops bind to eIF4B and prevent the factor's interaction with 18S rRNA of the small ribosomal subunit. In the second mechanism, the central A-rich domains of BC RNAs target eIF4A, specifically inhibiting its RNA helicase activity. Thus, BC RNAs repress translation initiation in a bimodal mechanistic approach. As BC RNA functionality has evolved independently in rodent and primate lineages, our data suggest that BC RNA translational control was necessitated and implemented during mammalian phylogenetic development of complex neural systems.Translational control is an important means for the regulation of gene expression in eukaryotic cells (22). In neurons, the local translation of select mRNAs in synaptodendritic domains is considered a key determinant of neuronal function and plasticity (11,13,28,42). Strict control of local translation is essential to ensure that relevant proteins are synthesized only when and where needed (11). Progress has been made over the last 10 years as translational control mechanisms have been investigated in neurons, and several translational regulators have been identified (33,46). In one of these mechanisms, the effectors of neuronal translational control are regulatory BC RNAs (2,8,(43)(44)(45).Dendritic BC RNAs, neuronal small cytoplasmic RNAs (scRNAs) that include rodent BC1 RNA and primate BC200 RNA (20,21,40,41), are non-protein-coding RNAs that regulate translation at the level of initiation (43, 44). Translational control mediated by BC1 RNA is important in the management of neuronal excitability (8,47,48). Lack of BC1 RNA in a BC1Ϫ/Ϫ animal model triggers increased group I metabotropic glutamate receptor-dependent synthesis of select synaptic proteins (47). Such alterations in the absence of BC1 RNA precipitate neuronal metabotropic glutamate receptor-mediated hyperexcitability that manifests in the form of exaggerated cortical gamma frequency oscillations, epileptogenic neuronal responses, and generalized seizures triggered by auditory stimulation (47, 48). These phenotypical manifestations are consonant with the molecular role of BC RNAs as translational repressors. BC1 RNA inhibits recruitment of the 43S preinitiation complex to the mRNA (44), a rate-limiting step in translation initiation that is mediated by the eIF4 family of eukaryotic initiation factors (6,9,12,31).The...

Background: Resveratrol is a non flavonoid polyphenol compound present in many plants and fruits and, at especially high concentrations, in the grape berries of Vitis vinifera. This compound has a strong bioactivity and its cytoprotective action has been demonstrated, however at high concentrations the drug exhibits also an effective anti-proliferative action. We recently showed its ability to abolish the effects of oxidative stress in cultured cells. In this work we assayed the bioactivity of resveratrol as antiproliferative and antiviral drug in cultured fibroblasts. Studies by other Authors showed that this natural compound inhibits the proliferation of different viruses such as herpes simplex, varicella-zoster and influenza A. The results presented here show an evident toxic activity of the drug at high concentrations, on the other hand at sub-cytotoxic concentrations, resveratrol can effectively inhibit the synthesis of polyomavirus DNA. A possible interpretation is that, due to the damage caused by resveratrol to the plasma membrane, the transfer of the virus from the endoplasmic reticulum to the nucleus, may be hindered thus inhibiting the production of viral DNA.

Neem oil is obtained from the seeds of the tree Azadirachta indica. Its chemical composition is very complex, being rich in terpenoids and limonoids, as well as volatile sulphur modified compounds. This work focused on the evaluation of a component of the whole Neem oil obtained by methanolic extraction and defined as MEX. Cytotoxicity was assessed on two different cell populations: a stabilized murine fibroblast line (3T6) and a tumor cell line (HeLa). The data presented here suggest a differential sensitivity of these two populations, the tumor line exhibiting a significantly higher sensitivity to MEX. The data strongly suggest that its toxic target is the cell membrane. In addition the results presented here imply that MEX may contain one or more agents that could find a potential use in anti-proliferative therapy.