Investigation of cellular morphology and proliferation on patterned electrospun PLA-gelatin mats

Journal of Biological Physics - The morphology and proliferation of eukaryotic cells depend on their microenvironment. When electrospun mats are used as tissue engineering scaffolds, the local...     

Prenatal Stress in Maternal Hyperhomocysteinemia: Impairments in the Fetal Nervous System Development and Placental Function

Biochemistry (Moscow) - The article presents current views on maternal hyperhomocysteinemia (HHcy) as an important factor causing prenatal stress and impaired nervous system development in fetuses...     

The binding of precipitant ions in the tetragonal crystals of hen egg white lysozyme

Abstract

The bonds between lysozyme molecules and precipitant ions in single crystals grown with chlorides of several metals are analysed on the basis of crystal structure data. Crystals of tetragonal hen egg lysozyme (HEWL) were grown with chlorides of several alkali and transition metals (LiCl, NaCl, KCl, NiCl₂ and CuCl₂) as precipitants and the three-dimensional structures were determined at 1.35?Å resolution by X-ray diffraction method. The positions of metal and chloride ions attached to the protein were located, divided into three groups and analysed. Some of them, in accordance with the recently proposed and experimentally confirmed crystal growth model, provide connections in protein dimers and octamers that are precursor clusters in the crystallization lysozyme solution. The first group, including Cu⁺², Ni⁺² and Na⁺¹ cations, binds specifically to the protein molecule. The second group consists of metal and chloride ions bound inside the dimers and octamers. The third group of ions can participate in connections between the octamers that are suggested as building units during the crystal growth. The arrangement of chloride and metal ions associated with lysozyme molecule at all stages of the crystallization solution formation and crystal growth is discussed.

Communicated by Ramaswamy H. Sarma     

Human probiotic bacteria attenuate Pseudomonas aeruginosa biofilm and virulence by quorum-sensing inhibition

Abstract

This work investigated chloroform extracts from culture supernatants of two human probiotic bacteria, Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730 for the production of virulence factors and quorum sensing (QS) interference against three Pseudomonas aeruginosa strains. Both extracts inhibited biofilm biomass (up to 50%), biofilm metabolic activity (up to 39%), the production of the enzyme elastase (up to 63%) and pyocyanin (up to 77%), and decreased QS, without presenting any antibacterial acgivity. In addition, the chloroform extracts of both strains disrupted preformed biofilms of the three strains of P. aeruginosa analyzed (up to 40%). GC-MS analysis revealed that the major compounds detected in the bioactive extracts were four diketopiperazines. This study suggests that the metabolites of L. casei and L. acidophilus could be a promising alternative to combat the pathogenicity of P. aeruginosa.     

Evidences against vesicle-dependent trafficking and involvement of extracellular proteasomes into cell-to-cell communications

The ubiquitin proteasome system is involved in the regulation of most basic intracellular processes, and deregulation of this system can results in certain kinds of human diseases. Proteolytic core this system, the 20S proteasome, has been found in physiological fluids of both healthy humans and patients suffering from a variety of inflammatory, autoimmune, and neoplastic diseases. The concentration of these extracellular proteasomes has been found to correlate with the diseased state, being of a prognostic significance. The transport mechanisms and functions of these proteasomes, however, are largely unclear. Previous studies revealed that the transport of extracellular proteasomes may occur via microvesicles and exosomes, which led to the hypothesis that extracellular proteasomes are implicated in cell-to-cell communication process. Here we show that microvesicles and exosomes, two major known types of intercellular vehicles, contain no detectable proteasomes. Moreover, neither affinity purified nor naturally released into conditioned medium by donor cells 20S proteasomes could penetrate recipient HeLa cells. Taken together, these results suggest that extracellular proteasomes are unlikely to be involved in the cell-to-cell communication and that their release by cells serve other biological purposes.     

Diffusion of energetic compounds through biological membrane: Application of classical MD and COSMOmic approximations

Computational studies of the potential biological impact of several energetic compounds were performed. The most commonly used explosives were considered in the present studies: trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 2,4-dinitroanisole (DNAN), and 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO). The effect of such factors as ionic strength and presence of DMSO in the water solution on the structure of the membrane were considered using the POPC lipid bilayer as an example. Molecular dynamics (MD) simulations revealed that, even on a short-time scale, the influence of those additives is noticeable, and therefore those factors should always be taken into account. The MD and the COSMOmic approaches were used to elucidate the ability of the energetic compounds to penetrate the living cell. Calculated free energy profiles and partitioning coefficients revealed distributions of the compounds in the lipid bilayer as well as an overall ability to enter the cell. MD in this case provides a better representation of the free energy profile, while the COSMOmic approach works better to predict log(K_lipw) values. The effect of the functional group was observed for the profiles that were obtained using the MD method.     

Synthesis and biological evaluation of novel mono- and bivalent ASGP-R-targeted drug-conjugates

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatile synthetic approach to novel mono- and multivalent drug-conjugates containing N-acetyl-2-deoxy-2-aminogalactopyranose and anticancer drug – paclitaxel (PTX). Several molecules have demonstrated high affinity towards ASGP-R and good stability under physiological conditions, significant in vitro anticancer activity comparable to PTX, as well as good internalization via ASGP-R-mediated endocytosis. Therefore, the conjugates with the highest potency can be regarded as a promising therapeutic option against HCC.     

Involvement of the specific nucleolar protein SURF6 in regulation of proliferation and ribosome biogenesis in mouse NIH/3T3 fibroblasts

The nucleolar proteins which link cell proliferation to ribosome biogenesis are regarded to be potentially oncogenic. Here, in order to examine the involvement of an evolutionary conserved nucleolar protein SURF6/Rrp14 in proliferation and ribosome biogenesis in mammalian cells, we established stably transfected mouse NIH/3T3 fibroblasts capable of conditional overexpression of the protein. Cell proliferation was monitored in real-time, and various cell cycle parameters were quantified based on flow cytometry, Br-dU-labeling and conventional microscopy data. We show that overexpression of SURF6 accelerates cell proliferation and promotes transition through all cell cycle phases. The most prominent SURF6 pro-proliferative effects include a significant reduction of the population doubling time, from 19.8 ± 0.7 to 16.2 ± 0.5 hours (t-test, p < 0.001), and of the length of cell division cycle, from 17.6 ± 0.6 to 14.0 ± 0.4 hours (t-test, p < 0.001). The later was due to the shortening of all cell cycle phases but the length of G1 period was reduced most, from 5.7 ± 0.4 to 3.8 ± 0.3 hours, or by ～30%, (t-test, p < 0.05). By Northern blots and qRT-PCR, we further showed that the acceleration of cell proliferation was concomitant with an accumulation of rRNA species along both ribosomal subunit maturation pathways. It is evident, therefore, that like the yeast homologue Rrp14, mammalian SURF6 is involved in various steps of rRNA processing during ribosome biogenesis. We concluded that SURF6 is a novel positive regulator of proliferation and G1/S transition in mammals, implicating that SURF6 is a potential oncogenic protein, which can be further studied as a putative target in anti-cancer therapy.