Differential roles of trithorax protein MLL-1 in regulating neuronal Ion channels

Repressive regulation of potassium channel genes by Polycomb group (PcG) proteins contributes to PcG protein-mediated neuroprotection against neuronal ischemic injury, as seen in an ischemic stroke. Here we asked the question whether Trithorax group (TrxG) proteins, the antagonistic partners of PcG proteins (i.e, epigenetic activators targeting the same genes) may also regulate potassium channels. Results of patch-clamp studies on cultured neuronal cells showed that inhibition of TrxG protein MLL-1 led to an increase in potassium channel activity, an unexpected effect for a presumed gene activator. In contrast, decreased sodium currents were observed with MLL-1 inhibition. Increased or decreased levels of potassium channel protein Kv2.1 or sodium channel protein Nav1.2, respectively, were seen with MLL-1 inhibition, as determined by immunocytochemistry. These results, for the first time, demonstrate an involvement of TrxG protein MLL-1 in regulating neuronal ion channels, potentially repressing potassium channel genes.

Differential gene expression in Drosophila melanogaster and D. nigrosparsa infected with the same Wolbachia strain

Wolbachia are maternally inherited endosymbionts that infect nearly half of all arthropod species. Wolbachia manipulate their hosts to maximize their transmission, but they can also provide benefits such as nutrients and resistance against viruses to their hosts. The Wolbachia strain wMel was recently found to increase locomotor activities and possibly trigger cytoplasmic incompatibility in the transinfected fly Drosophilanigrosparsa. Here, we investigated, in females of both D.melanogaster and D.nigrosparsa, the gene expression between animals uninfected and infected with wMel, using RNA sequencing to see if the two Drosophila species respond to the infection in the same or different ways. A total of 2164 orthologous genes were used. The two fly species responded to the infection in different ways. Significant changes shared by the fly species belong to the expression of genes involved in processes such as oxidation–reduction process, iron-ion binding, and voltage-gated potassium-channel activity. We discuss our findings also in the light of how Wolbachia survive within both the native and the novel host.

Absence of entourage: Terpenoids commonly found in Cannabis sativa do not modulate the functional activity of Δ9-THC at human CB1and CB2 receptors

IntroductionCompounds present in Cannabis sativa such as phytocannabinoids and terpenoids, may act in concert to elicit therapeutic effects. Cannabinoids such as Δ9-tetrahydrocannabinol (Δ9-THC) directly activate cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2), however, it is not known if terpenoids present in Cannabis also affect cannabinoid receptor signalling. Therefore, we examined 6 common terpenoids alone, and in combination with cannabinoid receptor agonists, on CB1 and CB2 signalling in vitro.Materials and MethodsPotassium channel activity in AtT20 FlpIn cells transfected with human CB1 or CB2 receptors was measured in real-time using FLIPR® membrane potential dye in a FlexStation 3 plate reader. Terpenoids were tested individually and in combination for periods up to 30 minutes. Endogenous somatostatin receptors served as a control for direct effects of drugs on potassium channels.Resultsα-Pinene, β-pinene, β-caryophyllene, linalool, limonene and β-myrcene (up to 30-100 µM) did not change membrane potential in AtT20 cells expressing CB1 or CB2, or affect the response to a maximally effective concentration of the synthetic cannabinoid CP55,940. The presence of individual or a combination of terpenoids did not affect the hyperpolarization produced by Δ9-THC (10µM): (CB1: control, 59±7%; with terpenoids (10 µM each) 55±4%; CB2: Δ9-THC 16±5%, with terpenoids (10 µM each) 17±4%). To investigate possible effect on desensitization of CB1 responses, all six terpenoids were added together with Δ9-THC and signalling measured continuously over 30 min. Terpenoids did not affect desensitization, after 30 minutes the control hyperpolarization recovered by 63±6%, in the presence of the terpenoids recovery was 61±5%.DiscussionNone of the six of the most common terpenoids in Cannabis directly activated CB1 or CB2, or modulated the signalling of the phytocannabinoid agonist Δ9-THC. These results suggest that if a phytocannabinoid-terpenoid entourage effect exists, it is not at the CB1 or CB2 receptor level. It remains possible that terpenoids activate CB1 and CB2 signalling pathways that do not involve potassium channels, however, it seems more likely that they may act at different molecular target(s) in the neuronal circuits important for the behavioural effect of Cannabis.