Sterculic acid antagonizes 7-ketocholesterol-mediated inflammation and inhibits choroidal neovascularization

Sterculic acid is a cyclopropene fatty acid with numerous biological activities. In this study we demonstrate that sterculic acid is a potent inhibitor of endoplasmic reticulum (ER) stress and related inflammation caused by 7-ketocholesterol (7KCh). 7KCh is a highly toxic oxysterol suspected in the pathogenesis of various age-related diseases such as atherosclerosis, Alzheimer's disease and age-related macular degeneration. Sterculic acid demonstrated to be 5-10 times more effective than other anti-inflammatory fatty acids at inhibiting 7KCh-mediated inflammatory responses in cultured cells. In vivo, sterculic acid was effective at inhibiting the formation of choroidal neovascularization (CNV) in the laser-injury rat model. Our data suggests that sterculic acid may be useful in treating CNV in certain forms of age-related macular degeneration.     

Early apoptosis-related changes triggered by HSV-1 in individual neuronlike cells

Early events of apoptosis following HSV-1 infection were investigated at the single-cell level using intensified fluorescence digital-imaging microscopy. The results provide evidence that infection of differentiated ND7 neuronlike cells by HSV-1 triggers detectable alterations indicative of physiological changes associated with the early stages of apoptosis. Less than 1 h after infection with HSV-1 (KOS strain) or K26GFP (GFP being fused to HSV-1 capsid protein VP26) we observed (i) moderate decrease in mitochondrial membrane potential (about 20%), (ii) exposure of phosphatidyl serine, (iii) morphological change in the mitochondria that became spherical instead of filamentous, and (iv) activation of caspase-8. Within 3 h changes reverted to normal, which indicated that apoptosis was counteracted very early following HSV-1 infection. Similar results were obtained with KOS-TK27GFP, lacking TK and UL24 proteins, suggesting that TK and UL24 play no role in apoptosis. In Vero cells mitochondrial changes characteristic of the apoptotic process were not observed following HSV-1 infection. The UV-inactivated K26GFP had the capacity to induce apoptosis in neuronlike cells. This real-time multiparametric analysis, in combination with relevant viral mutants, could be a useful approach for dissecting the roles of various viral genes in modulating apoptotic pathways during infection.     

Lack of correlation between surface expression and currents in epileptogenic AB-calmodulin binding domain Kv7.2 potassium channel mutants

Heteromers of Kv7.2/Kv7.3 subunits constitute the main substrate of the neuronal M-current that limits neuronal hyper-excitability and firing frequency. Calmodulin (CaM) binding is essential for surface expression of Kv7 channels, and disruption of this interaction leads to diseases ranging from mild epilepsy to early onset encephalopathy. In this study, we addressed the impact of a charge neutralizing mutation located at the periphery of helix B (K526N). We found that, CaM binding and surface expression was impaired, although current amplitude was not altered. Currents were reduced at a faster rate after activation of a voltage-dependent phosphatase, suggesting that phosphatidylinositol-4,5-bisphosphate (PIP₂) binding was weaker. In contrast, a charge neutralizing mutation located at the periphery of helix A (R333Q) did not affect CaM binding, but impaired trafficking and led to a reduction in current amplitude. Taken together, these results suggest that disruption of CaM-dependent or CaM-independent trafficking of Kv7.2/Kv7.3 channels can lead to pathology regardless of the consequences on the macroscopic ionic flow through the channel.     

An Evidence for the Repair of Double-Strand Scissions in DNA of Micrococcus radiodurans after Alpha Bombardment

The conversion of prochaetoglobosins as plausible precursors into mycotoxin chaetoglobosin A (1) in a cell-free system of Chaetomium subaffine was unsuccessful. However, reductase activity of the 20-keto-analogues (1), and prochaetoglobosins II (5) and III (6) were found in a microsomal fraction of this fungi. Two new metabolites of chaetoglobosins, named chaetoglobosin F_ex (2) and 20-dihydro-chaetoglobosin A (3), were also isolated from the same micro-organisms. Their structures were elucidated by spectroscopic data and chemical transformation.     

Critical parameters in the MCF-7 cell proliferation bioassay (E-Screen)

The MCF-7 cell proliferation bioassay has grown in popularity as a rapid test for detecting potentially oestrogenic compounds. Several MCF-7 cell sublines with different sensitivities to oestrogens are currently used, with maximal proliferation responses ranging from two- to 10-fold above those of hormone-free controls. In the highly responsive MCF-7 BUS cell line, we evaluated critical assay parameters for test performance, including growth conditions, initial seeding densities and differences in growth stimulation in medium containing human serum or fetal calf serum as well as appropriate solvents for oestrogen-mimicking compounds. Modifications significantly reduced the labour-intensive steps and overall assay costs without affecting the sensitivity of the assay. Using this optimized test regimen, the responsiveness of treated MCF-7 BUS cells was consistently increased up to 11-fold over hormone-free controls. The specificity was characterized by examining the effects of oestradiol-17 β, the anti-oestrogen ICI 182,780, and dieldrin, a recognized xeno-oestrogen. The improved proliferation bioassay will be a useful tool in identifying potential xeno-oestrogens.     

Catalytic residues and substrate specificity of scytalidoglutamic peptidase, the first member of the eqolisin in family (G1) of peptidases

Scytalidoglutamic peptidase (SGP) is the first-discovered member of the eqolisin family of peptidases with a unique structure and a presumed novel catalytic dyad (E136 and Q53) [Fujinaga et al., PNAS 101 (2004) 3364-3369]. Mutants of SGP, E136A, Q53A, and Q53E lost both the autoprocessing and enzymatic activities of the wild-type enzyme. Coupled with the results from the structural analysis of SGP, Glu136 and Gln53 were identified as the catalytic residues. The substrate specificity of SGP is unique, particularly, in the preference at the P3 (basic amino acid), P1' (small a.a.), and P3' (basic a.a.) positions. Superior substrates and inhibitors have been synthesized for kinetic studies based on the results reported here. kcat, Km, and kcat/Km of SGP for D-Dap(MeNHBz)-GFKFF*ALRK(Dnp)-D-R-D-R were 34.8 s-1, 0.065 microM, and 535 microM-1 s-1, respectively. Ki of Ac-FKF-(3S,4S)-phenylstatinyl-LR-NH2 for SGP was 1.2x10(-10) M. Taken together, we can conclude that SGP has not only structural and catalytic novelties but also a unique subsite structure.     

Pyrazolo[4,3-e][1,2,4]triazine sulfonamides as carbonic anhydrase inhibitors with antitumor activity

A series of sildenafil analogues and aniline substituted pyrazolo[4,3-e][1,2,4]triazine sulfonamides were prepared and evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors and for their anticancer activity against two human breast cancer cell lines (MCF-7, MDA-MB-231). The new compounds were ineffective as CA I inhibitors, poorly inhibited CA II, but were more effective against the tumor-associated isoforms CA IX and XII, with some compounds acting as low nanomolar inhibitors. Evaluation of the cytotoxicity by using an MTT assay, the inhibition of [³H]thymidine incorporation into DNA as well as collagen synthesis inhibition, demonstrated that these sulfonamides exhibit cytotoxic effects on breast cancer cell lines ex vivo.