First Evidence of Kv3.1b Potassium Channel Subtype Expression during Neuronal Serotonergic 1C11 Cell Line Development.

Kv3.1 channel is abundantly expressed in neurons and its dysfunction causes sleep loss, neurodegenerative diseases and depression. Fluoxetine, a serotonin selective reuptake inhibitor commonly used to treat depression, acts also on Kv3.1. To define the relationship between Kv3.1 and serotonin receptors (SR) pharmacological modulation, we showed that 1C11, a serotonergic cell line, expresses different voltage gated potassium (VGK) channels subtypes in the presence (differentiated cells (1C11D)) or absence (not differentiated cells (1C11ND)) of induction. Only Kv1.2 and Kv3.1 transcripts increase even if the level of Kv3.1b transcripts is highest in 1C11D and, after fluoxetine, in 1C11ND but decreases in 1C11D. The Kv3.1 channel protein is expressed in 1C11ND and 1C11D but is enhanced by fluoxetine only in 1C11D. Whole cell measurements confirm that 1C11 cells express (VGK) currents, increasing sequentially as a function of cell development. Moreover, SR 5HT1b is highly expressed in 1C11D but fluoxetine increases the level of transcript in 1C11ND and significantly decreases it in 1C11D. Serotonin dosage shows that fluoxetine at 10 nM blocks serotonin reuptake in 1C11ND but slows down its release when cells are differentiated through a decrease of 5HT1b receptors density. We provide the first experimental evidence that 1C11 expresses Kv3.1b, which confirms its major role during differentiation. Cells respond to the fluoxetine effect by upregulating Kv3.1b expression. On the other hand, the possible relationship between the fluoxetine effect on the kinetics of 5HT1b differentiation and Kv3.1bexpression, would suggest the Kv3.1b channel as a target of an antidepressant drug as well as it was suggested for 5HT1b.

Hyalomma dromedarii (Acari: Ixodidae) Salivary Gland Extract Inhibits Angiogenesis and Exhibits In Vitro Antitumor Effects.

Hard ticks (Acari: Ixodidae) are blood-sucking ectoparasites characterized by the extended period of their attachment to their host. To access their bloodmeal, ticks secrete saliva containing a range of molecules that target the host's inflammation, immune system, and hemostatic components. Some of these molecules reportedly possess antiangiogenic and antitumor properties. The present study describes our investigation, the first of its kind, of the antiangiogenic and antitumoral effects of the Hyalomma dromedarii Koch, 1844 (Acari: Ixodidae), salivary gland extract (SGE), which inhibited the adhesion and migration of Human Umbilical Vein Endothelial Cells (HUVECs) in a dose-dependent manner, as well as angiogenesis in the Chick Chorioallantoic Membrane model. Interestingly, H. dromedarii SGE exerted an antiproliferative effect on U87 glioblastoma cells and inhibited their adhesion and migration to fibrinogen. These results open up new possibilities for characterizing and developing new molecules involved in the key steps of tumor progression.

Phthalimido-ferrocidiphenol cyclodextrin complexes: Characterization and anticancer activity.

Several ferrocenyl analogues of tamoxifen have already showed strong antiproliferative activity in experimental glioma models. Nevertheless, these compounds are very poorly soluble in water and an adapted formulation is needed. In this work, we have tailored and optimized methylated cyclodextrin soluble complexes of phthalimido-ferrocidiphenol for the first time. The complexes were characterized, and the optimized formulation was tested for in vitro efficacy and cell proliferation assays on U87, human glioblastoma cancer cells. Molecular modeling can provide accurate information about the inclusion process. The inclusion of all the moieties at the same time (i.e., ferrocene, phthalimidylpropyl, 2 phenols) is not possible due to the steric hindrance of the 1:4 system. The 1:3 systems are possible but do not seem very relevant. However, various 1:2 and 1:1 complexes are mostly present in aqueous solutions. Some experiments have confirmed our hypothesis. First, interactions between the phenol, phthalimidylpropyl and ferrocenyl groups have been observed in our NMR experiments. Second, the inclusion of phthalimidylpropyl was detected by UV-vis spectrophotometry with an apparent 1:1 interaction, which was observed through the Benesi-Hildebrand method. The complex is readily soluble in water and keeps its pharmacological activity against U87 tumor cells (IC50=0.028 ± 0.007 µM vs. 0.018 ± 0.003 µM for PhtFerr).

Inhibition of human Kv3.1 current expressed in Xenopus oocytes by the toxic venom fraction of Androctonus australis hector.

AahG50, the toxic fraction of Androctonus australis hector venom, was studied on human Kv3.1 channels activation, stably expressed in Xenopus oocytes using the two-electrode voltage clamp technique. AahG50 reduced Kv3.1 currents in a reversible concentration-dependent manner, with an IC50 value and a Hill coefficient of 40.4 ± 0.2 µg/ml and 1.3 ± 0.05, respectively. AahG50 inhibited IKv3.1 without modifying the current activation kinetics. The AahG50-induced inhibition of Kv3.1 channels was voltage-dependent, with a gradual increase at lower concentrations and over the voltage range of channels opening. However, at higher concentrations, the inhibition exhibited voltage dependence only in the first range of channels opening from -20 to +10 mV, but demonstrates a low degree of voltage-dependence when channels are fully activated. In the literature, toxins have previously been isolated from AahG50, KAaH1 and KAaH2 and were reported not to have any effect on IKv3.1. The present article's findings suggest that AahG50 may contain a peptidic component active on Kv3.1 channels, which inhibits IKv3.1 in a selective manner.

VHH, bivalent domains and chimeric Heavy chain-only antibodies with high neutralizing efficacy for scorpion toxin AahI'.

Many efforts aim at solving the serious problems encountered with immunotherapy against scorpion envenoming. The most attractive approach consists in generating single-chain antibody fragments (scFv) as their pharmaco-kinetic properties should match closely those of the scorpion toxins. Although high affinity scFv reagents have been generated in the past, their production level, stability, and toxin neutralizing capacity remain disappointingly poor. In the current study, we identified one Nanobody (Nb), a single-domain antigen-binding fragment of a dromedary Heavy-chain antibody (HCAb) that recognizes specifically the Androctonus australis hector AahI' toxin. This Nb has excellent production, stability and solubility characteristics. With this Nb we further manufactured a tandem linked bivalent construct and assembled a HCAb with improved antigen binding due to avidity effects. All these constructs were shown in mouse models to possess a scorpion toxin neutralization capacity that exceeds by far all previous attempts with scFv-based materials, even when used at lower doses. It is therefore clear that in the near future Nanobodies will be at the core of novel serotherapeutics as they combine multiple benefits over other reagents to treat scorpion envenomed patients.