Regulation of Apolipoprotein A-I Gene Expression in Human Macrophages by Oxidized Low-Density Lipoprotein

Biochemistry (Moscow) - Apolipoprotein A-I (ApoA-I) is a key component of reverse cholesterol transport in humans. In the previous studies, we demonstrated expression of the apoA-I gene in human...     

1A2 Insulator can interact with promoter of hsp70 gene in D. melanogaster

Insulators are regulatory DNA elements that participate in the modulation of the interactions between enhancers and promoters. Depending on the situation, insulators can either stabilize or destroy the contacts between enhancers and promoters. A possible explanation for the activity of insulators is their ability to directly interact with gene promoters. In the present study, it was demonstrated that, in model systems, a 1A2 insulator could interact with the core sequence of an hsp70 promoter. In this case, the insulator protein CP190 is found on the hsp70 promoter, which depends on the presence of an insulator in the transgene. The data obtained are consistent with the model, which implies that direct contacts between insulators and promoters make a considerable contribution to the modulation of the interactions between insulators and promoters.     

Complete genome sequence of the hyperthermophilic archaeon Thermococcus sp. strain AM4, capable of organotrophic growth and growth at the expense of hydrogenogenic or sulfidogenic oxidation of carbon monoxide

Analysis of the complete genome of Thermococcus sp. strain AM4, which was the first lithotrophic Thermococcales isolate described and the first archaeal isolate to exhibit a capacity for hydrogenogenic carboxydotrophy, reveals a proximity with Thermococcus gammatolerans, corresponding to close but distinct species that differ significantly in their lithotrophic capacities.     

Neuroplastin-65 and a mimetic peptide derived from its homophilic binding site modulate neuritogenesis and neuronal plasticity

Neuroplastin-65 (Np65) is a brain-specific cell adhesion molecule belonging to the immunoglobulin superfamily. Homophilic trans-interaction of Np65 mediates adhesion between cells and modulates synaptic plasticity. This interaction solely occurs through the first immunoglobulin (Ig) module of Np65, but the exact binding mechanism has not yet been elucidated. In this study, we identify the homophilic binding motif of Np65 and show that a synthetic peptide modeled after this motif, termed enplastin, binds to Np65. We demonstrate that both Np65- and enplastin-induced intracellular signaling depends on fibroblast growth factor receptor, p38 mitogen-activated protein kinase, Ca(2+) /calmodulin-dependent protein kinase, and cytoplasmic Ca(2+) concentration. In addition, we show that interference with Np65 homophilic binding by enplastin has an inhibitory effect on Np65-mediated neurite outgrowth in vitro and on the initial phase of spatial learning in rats.     

Contribution of social isolation, restraint, and hindlimb unloading to changes in hemodynamic parameters and motion activity in rats

The most accepted animal model for simulation of the physiological and morphological consequences of microgravity on the cardiovascular system is one of head-down hindlimb unloading. Experimental conditions surrounding this model include not only head-down tilting of rats, but also social and restraint stresses that have their own influences on cardiovascular system function. Here, we studied levels of spontaneous locomotor activity, blood pressure, and heart rate during 14 days under the following experimental conditions: cage control, social isolation in standard rat housing, social isolation in special cages for hindlimb unloading, horizontal attachment (restraint), and head-down hindlimb unloading. General activity and hemodynamic parameters were continuously monitored in conscious rats by telemetry. Heart rate and blood pressure were both evaluated during treadmill running to reveal cardiovascular deconditioning development as a result of unloading. The main findings of our work are that: social isolation and restraint induced persistent physical inactivity, while unloading in rats resulted in initial inactivity followed by normalization and increased locomotion after one week. Moreover, 14 days of hindlimb unloading showed significant elevation of blood pressure and slight elevation of heart rate. Hemodynamic changes in isolated and restrained rats largely reproduced the trends observed during unloading. Finally, we detected no augmentation of tachycardia during moderate exercise in rats after 14 days of unloading. Thus, we concluded that both social isolation and restraint, as an integral part of the model conditions, contribute essentially to cardiovascular reactions during head-down hindlimb unloading, compared to the little changes in the hydrostatic gradient.     

Planar arrangement of eukaryotic cells in merged hydrogels combines the advantages of 3-D and 2-D cultures

We report an unordered 2-D array of eukaryotic cells completely embedded in a 3-D matrix. Every cell is located at the same distance from the gel surface, which ensures uniformity of growth conditions and ease of observation characteristic of a 2-D culture. Each cell is firmly immobilized, and each has a unique address in the array. The cells can be rapidly screened, individually monitored during extended time periods, and cultured with the formation of spheroid microcolonies characteristic of a 3-D culture. Individual microcolonies can be extracted from the gel and further propagated, thus enabling isolation of pure cell clones from rather dense cell populations and rapid drug-free generation of stable cell lines.     

Crystal structure of D-serine dehydratase from Escherichia coli

D-Serine dehydratase from Escherichia coli is a member of the β-family (fold-type II) of the pyridoxal 5′-phosphate-dependent enzymes, catalyzing the conversion of D-serine to pyruvate and ammonia. The crystal structure of monomeric D-serine dehydratase has been solved to 1.97 Å-resolution for an orthorhombic data set by molecular replacement. In addition, the structure was refined in a monoclinic data set to 1.55 Å resolution. The structure of DSD reveals a larger pyridoxal 5′-phosphate-binding domain and a smaller domain. The active site of DSD is very similar to those of the other members of the β-family. Lys118 forms the Schiff base to PLP, the cofactor phosphate group is liganded to a tetraglycine cluster Gly279-Gly283, and the 3-hydroxyl group of PLP is liganded to Asn170 and N1 to Thr424, respectively. In the closed conformation the movement of the small domain blocks the entrance to active site of DSD. The domain movement plays an important role in the formation of the substrate recognition site and the catalysis of the enzyme. Modeling of D-serine into the active site of DSD suggests that the hydroxyl group of D-serine is coordinated to the carboxyl group of Asp238. The carboxyl oxygen of D-serine is coordinated to the hydroxyl group of Ser167 and the amide group of Leu171 (O1), whereas the O2 of the carboxyl group of D-serine is hydrogen-bonded to the hydroxyl group of Ser167 and the amide group of Thr168. A catalytic mechanism very similar to that proposed for L-serine dehydratase is discussed.