Complestatin antagonizes the AMPA/kainate-induced neurotoxicity in cultured chick telencephalic neurons

P450 monooxygenase ComJ catalyses side chain phenolic cross-coupling during complestatin biosynthesis

P450 monooxygenase enzyme ComJ catalyzed biaryl ether bond formation with high efficiency and low stereoselectivity on selected complestatin-like peptide substrates.

In vitro toxicity of colistin on primary chick cortex neurons and its potential mechanism

Colistin is increasingly used as the last-line therapy for infections caused by Gram-negative 'superbugs'. Although colistin neurotoxicity was reported in the literature, there has no data on its mechanism. In the present study, we examined the effect of colistin on primary chick neuron cells, which were treated with 0.83, 4.15 and 8.3μg/mL colistin for 6, 12 and 24h. Cell viability was evaluated with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assays after exposure to colistin. Formation of reactive oxygen species (ROS), nuclear morphology, caspase-3 activity and internucleosomal DNA fragmentation were examined. The results showed that, compared with the control, no significant change was observed in cell viability, ROS formation and caspase-3 activity in cells treated for 6, 12 and 24h with 0.83μg/mL colistin. However, in the 4.15 and 8.3μg/mL colistin-treated groups, the viability of chick primary neurons significantly decreased at 12 and 24h, respectively; caspase-3 activities were significantly increased to 5.1 and 7.4 fold at 6h, more earlier than the changes of ROS, which was significant increased to 124.5% and 143.5% (P<0.01) of control at 12h, respectively. The apoptosis of neuron cells was revealed by both nuclear morphological observations and internucleosomal DNA fragmentation in the 4.15 and 8.3μg/mL colistin-treated groups at 6, 12 and 24h. Our data demonstrated that colistin can induce apoptosis in primary chick cortex neurons through caspase-3 activation, which may be contributed with ROS-dependent and independent mechanism.

Complestatin prevents apoptotic cell death: inhibition of a mitochondrial caspase pathway through AKT/PKB activation

Complestatin, a bicyclo hexapeptide from Streptomyces, was isolated as a possible regulator of neuronal cell death. In this study, we report an anti-apoptotic activity of complestatin and its underlying molecular mechanism. Complestatin blocked TRAIL (TNF-related apoptosis-inducing ligand)-induced apoptosis and activation of caspase-3 and -8 at micromolar concentration levels without inhibiting the catalytic activities of these caspases. Complestatin potently induced a rapid and sustained AKT/PKB activation and Bad phosphorylation, resulting in inhibition of mitochondrial cytochrome c release. These anti-apoptotic activities of complestatin were significantly abrogated in cells expressing dominant negative AKT/PKB. Taken together, our results suggest that complestatin prevents apoptotic cell death via AKT/PKB-dependent inhibition of the mitochondrial apoptosis signal pathway. The novel property of complestatin may be valuable for developing new pharmaceutical means that will control unwanted cell death.