ATP oscillations mediate inductive action of FGF and Shh signalling on prechondrogenic condensation

Skeletal patterns are prefigured by prechondrogenic condensation. Morphogens such as fibroblast growth factor (FGF) and sonic hedgehog (Shh) specify the skeletal patterns in limb development. However, how morphogens regulate prechondrogenic condensation has remained unclear. Recently, it was demonstrated that synchronized Adenosine triphosphate (ATP) oscillations play a critical role in prechondrogenic condensation. Thus, the present study has focused on whether ATP oscillations mediate the actions of major developmental morphogens such as FGF and Shh on prechondrogenic condensation. It has been shown that both FGF and Shh signalling promoted cellular condensation but not chondrogenic differentiation and also induced ATP oscillations. In addition, blockage of FGF and Shh signalling prevented both ATP oscillations and prechondrogenic condensation. Furthermore, it was found that inhibition of ATP oscillations suppressed FGF/Shh‐induced prechondrogenic condensation. These results indicate that ATP oscillations mediate the actions of FGF and Shh signalling on prechondrogenic condensation. This study proposes that morphogens organize skeletal patterns via ATP oscillations. Copyright © 2012 John Wiley & Sons, Ltd.     

PICH promotes mitotic chromosome segregation: Identification of a novel role in rDNA disjunction

PICH is an SNF2-family DNA translocase that appears to play a role specifically in mitosis. Characterization of PICH in human cells led to the initial discovery of “ultra-fine DNA bridges” (UFBs) that connect the 2 segregating DNA masses in the anaphase of mitosis. These bridge structures, which arise from specific regions of the genome, are a normal feature of anaphase but had escaped detection previously because they do not stain with commonly used DNA dyes. Nevertheless, UFBs are important for genome maintenance because defects in UFB resolution can lead to cytokinesis failure. We reported recently that PICH stimulates the unlinking (decatenation) of entangled DNA by Topoisomerase IIα (Topo IIα), and is important for the resolution of UFBs. We also demonstrated that PICH and Topo IIα co-localize at the rDNA (rDNA). In this Extra View article, we discuss the mitotic roles of PICH and explore further the role of PICH in the timely segregation of the rDNA locus.     

Protective effects of veskamide, enferamide, becatamide, and oretamide on H2O2-induced apoptosis of PC-12 cells

Veskamide, enferamide, becatamide, and oretamide are phenolic amides whose analogues are found in plants. In this study, the four amides were prepared by chemical synthesis and their protective effects on H₂O₂-induced apoptosis in PC-12 cells were investigated. The syntheses were relatively simple and the yields were more than 43%. Using NMR spectroscopic methods, the chemical structures of veskamide, enferamide, becatamide, and oretamide were confirmed. The decreasing order of the protective effects on H₂O₂-induced apoptosis was becatamide > enferamide ≥ oretamide > veskamide. In fact, becatamide suppressed H₂O₂-induced mitochondrial membrane depolarization in a dose-dependent manner. At the concentration of 10 μM, becatamide maintained mitochondrial membrane depolarization at 16% compared to 51% in H₂O₂-treated PC-12 cells (P < 0.05). Also, at the same concentration, becatamide inhibited H₂O₂-induced caspase-9 activation and caspase-independent chromatin condensation by 68% (P < 0.05) and 73% (P < 0.05), respectively. This is the first report about the chemical synthesis of becatamide and its potential biological activity to inhibit H₂O₂-induced apoptosis of PC-12 cells via protecting mitochondrial membrane integrity, thereby suppressing caspase-9 activation and chromatin condensation.     

Synthesis and Biological Activity of Some Bromophenols and Their Derivatives Including Natural Products

In addition to the first synthesis of the natural bromophenol butyl 2-(3,5-dibromo-4-hydroxyphenyl)acetate ( 1 ), indene derivatives 34 and 35 were synthesized from 3-phenylpropenal derivatives in BBr₃ medium. Five known natural bromophenols and some derivatives were synthesized by known methods. Cholinesterase (ChEs) inhibitors reduce the breakdown of acetylcholine and are used in the treatment of Alzheimer's disease (AD) and dementia symptoms. The inhibition effects of all obtained compounds were examined towards acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glycosidase enzymes. All synthesized compounds demonstrated the strong inhibition effects against both cholinergic enzymes. For determination of Ki values of novel bromophenols Lineweaver-Burk graphs were obtained. Ki values were found in the ranging of 0.13–14.74 nM for AChE, 5.11–23.95 nM for BChE, and 63.96–206.78 nM for α-glycosidase, respectively. All bromophenols and their derivatives exhibit effective inhibition profile when compared to positive controls.     

Energetics of peptide bond formation at elevated temperatures

Summary The free energies of formation of the peptide bond between carbobenzoxy-glycine and L-phenylalanine amide in aqueous solution at temperatures up to 60°C were calculated from experimentally determined equilibrium constants. The reaction was catalyzed by a thermophylic enzyme. The thermodynamic energy barrier to peptide bond formation was found to decrease with increasing temperature: the standard free energy of peptide bond formation did appear to become negative in the region of 60°C. The possible significance of these results for peptide bond formation under prebiotic conditions is discussed.     

A Multivariate Re-Examination of Experimental Condition Effects on Acyloin-Type Condensation Mediated by Saccharomyces Cerevisiae

Statistical methods of optimization were applied to the stereoselective synthesis of (2S,3R)-5-phenylpent-4-en-2,3-diol mediated by baker's yeast. The quantitative effects of seven variables, i.e. pH, temperature, concentration of cinnamaldehyde, yeast and glucose, addition of pyruvate and acetaldehyde were investigated using a fractional factorial design. This approach gave informations about the chemical behaviour of the yeast. Response surface methodology was employed to describe the variability of the yield in the experimental domain.