Design,Synthesis and Enzymatic Inhibition of Novel Unusual Amino Acids as a Transition State Analogue of Amyloid Precursor Protein Peptide

International Journal of Peptide Research and Therapeutics - β-secretase 1 (BACE1) plays a pivotal role in the pathology of Alzheimer?s disease via accumulation beta amyloid in the...     

Synthesis,Biological Evaluation and Molecular Docking of Deferasirox and Substituted 1,2,4‐Triazole Derivatives as Novel Potent Urease Inhibitors: Proposing Repositioning Candidate

A series of new deferasirox derivatives were synthesized through the reaction of monosubstituted hydrazides with 2‐(2‐hydroxyphenyl)‐4H‐benzo[e][1,3]oxazin‐4‐one. For the first time, deferasirox and some of its derivatives were evaluated for their in vitro inhibitory activity against Jack bean urease. The potencies of the members of this class of compounds are higher than that of acetohydroxamic acid. Two compounds, bearing tetrazole and hydrazine derivatives (bioisoester of carboxylate group), represented the most potent urease inhibitory activity with IC₅₀ values of 1.268 and 3.254 μm , respectively. In silico docking studies were performed to delineate possible binding modes of the compounds with the enzyme, urease. Docking analysis suggests that the synthesized compounds were anchored well in the catalytic site and extending to the entrance of binding pocket and thus restrict the mobility of the flap by interacting with its crucial amino acid residues, CME592 and His593. The overall results of urease inhibition have shown that these target compounds can be further optimized and developed as a lead skeleton for the discovery of novel urease inhibitors     

Cell surface expression of 27C7 by neonatal rat olfactory ensheathing cells in situ and in vitro is independent of axonal contact

Olfactory ensheathing cells (OECs) are Schwann cell-like glial cells of the olfactory system that promote neural regeneration after transplantation into the injured central nervous system. Compared to the closely related Schwann cells, however, the biological characterization of OECs has remained fragmentary. This is due to the fact that the expression of OEC-specific markers is subject to complex regulation and that intricate ultrastructural analysis is essential to determine their localization. The p75 neurotrophin receptor (p75^NTR) as the prototype OEC marker, for example, is only expressed by a minor population of neonatal rat OECs in situ. The major population carries O4-positive axonal fragments on their surface after dissociation and up-regulates p75^NTR during culturing (Wewetzer et al. in Glia 49:577–587, 2005). In the present study, we investigated whether the cell surface determinant 27C7, defined by a monoclonal antibody to Schwann cells, is also expressed by neonatal rat OECs in situ and in vitro. Primary cell suspensions of the olfactory bulb displayed 27C7 expression of both p75^NTR-negative and p75^NTR-positive OECs, while immature oligodendrocytes and astrocytes were devoid of any 27C7 labeling. This together with the finding that the intrafascicular OECs of the olfactory nerves in the mucosa expressed 27C7 but not p75^NTR, suggests that 27C7 was expressed by the entire OEC population in situ. Maintenance of OECs in the absence of olfactory neurons in organotypic slice culture up-regulated p75^NTR but did not alter 27C7 expression. It is concluded that 27C7 unlike p75^NTR is constitutively expressed by OECs and may, therefore, be a useful marker for characterization of neonatal OECs in situ and in vitro.     

Copper(II) complexes derived from tripodal tris[(2-ethyl-(1-pyrazolyl)]amine

Three mono-nuclear copper(II) complexes [Cu(tepza)X]ClO₄ (X = Cl, 1; X = NCS, 2; X = dca, 3) and two dinuclear bridging complexes [Cu₂(tepza)₂(μ-C₄O₄)](ClO₄)₂·H₂O(4) and [Cu₂(tepza)₂(μ-C₅O₅)](ClO₄)₂(5) where tepza = tris[2-ethyl(1-pyrazolyl)]amine, dca = dicyanamide, C₄O₄²⁻ = 3,4-dihydroxycyclobut-3-ene-1,2-dionate (squarate dianion) and C₅O₅²⁻ = 4,5-dihydroxycyclopent-4-ene-1,2,3-trionate (croconate dianion) were synthesized and structurally characterized by IR and UV-Vis spectroscopy as well as by single X-ray crystallography. In the solid state, the geometry of copper(II) centers in these complexes are as follows: close to SP in 2, distorted TBP in 3, predominant SP in 4, and distorted octahedral in 5, whereas in solution distorted SP geometry was generally found. The squarato and the croconato dianions in complexes 4 and 5 are bridging the two copper(II) centers in cis-bis-monodentate and bis-bidentate bonding modes, respectively. Magnetic susceptibility measurements at variable temperatures (2-300 K) reveal the weak antiferromagnetic coupling in the two bridging dinuclear complexes 4 (J = −24.9 cm⁻¹) and 5 (J = −3.1 cm⁻¹).     

Identification of luminal Loop 1 of Scap protein as the sterol sensor that maintains cholesterol homeostasis

Cellular cholesterol homeostasis is maintained by Scap, an endoplasmic reticulum (ER) protein with eight transmembrane helices. In cholesterol-depleted cells, Scap transports sterol regulatory element-binding proteins (SREBPs) to the Golgi, where the active fragment of SREBP is liberated by proteases so that it can activate genes for cholesterol synthesis. When ER cholesterol increases, Scap binds cholesterol, and this changes the conformation of cytosolic Loop 6, which contains the binding site for COPII proteins. The altered conformation precludes COPII binding, abrogating movement to the Golgi. Consequently, cholesterol synthesis declines. Here, we identify the cholesterol-binding site on Scap as Loop 1, a 245-amino acid sequence that projects into the ER lumen. Recombinant Loop 1 binds sterols with a specificity identical to that of the entire Scap membrane domain. When tyrosine 234 in Loop 1 is mutated to alanine, Loop 6 assumes the cholesterol-bound conformation, even in sterol-depleted cells. As a result, full-length Scap(Y234A) cannot mediate SREBP processing in transfected cells. These results indicate that luminal Loop 1 of Scap controls the conformation of cytosolic Loop 6, thereby determining whether cells produce cholesterol.     

Quantitative immunogold localization of protein phosphatase 2B (calcineurin) in Paramecium cells.

For immunogold EM labeling analysis, we fixed Paramecium cells in 4% formaldehyde and 0.125% glutaraldehyde, followed by low-temperature embedding in unicryl and UV polymerization. We first quantified some obvious but thus far neglected side effects of section staining on immunogold labeling, using mono- or polyclonal antibodies (Abs) against defined secretory and cell surface components, followed by F(ab)(2)- or protein A-gold conjugates. Use of alkaline lead staining resulted in considerable rearrangement and loss of label unless sections were postfixed by glutaraldehyde after gold labeling. This artifact is specific for section staining with lead. It can be avoided by staining sections with aqueous uranyl acetate only to achieve high-resolution immunogold localization of a protein phosphatase on unicryl sections. In general, phosphatases are assumed to be closely, although loosely, associated with their targets. Because the occurrence of protein phosphatase 2B (calcineurin) in Paramecium has been previously established by biochemical and immunological work, as well as by molecular biology, we have used Abs against mammalian CaN or its subunits, CaN-A and CaN-B, for antigen mapping in these cells by quantitative immunogold labeling analysis. Using ABs against whole CaN, four structures are selectively labeled (with slightly decreasing intensity), i.e., infraciliary lattice (centrin-containing contractile cortical filament network), parasomal sacs (coated pits), and outlines of alveolar sacs (subplasmalemmal calcium stores, tightly attached to the cell membrane), as well as rims of chromatin-containing nuclear domains. In other subcellular regions, gold granules reached densities three to four times above background outside the cell but there was no selective enrichment, e.g., in cilia, ciliary basal bodies, cytosol, mitochondria, trichocysts (dense-core secretory organelles), and non-chromatin nuclear domains. Their labeling density was 4- to 8.5-fold (average 6.5-fold) less than that on selectively labeled structures. Labeling tendency was about the same with Abs against either subunit. Our findings may facilitate the examination of molecular targets contained in the selectively labeled structures. (J Histochem Cytochem 48:1269-1281, 2000)     

Prenatal liver stromal cells: Favorable feeder cells for long-term culture of hepatic progenitor cells

Clinical and pharmaceutical applications of primary hepatocytes (PHs) are limited due to inadequate number of donated livers and potential challenges in successful maintenance of PHs in culture. Freshly isolated hepatocytes lose their specific features and rapidly de-differentiate in culture. Bipotent hepatoblasts, as liver precursor cells that can differentiate into both hepatocytes and cholangiocytes (Alb- and Ck19-positive cells, respectively), could be used as an alternative and reliable cell source to produce enough PHs for drug discovery or possible clinical applications. In this study, growth factor-free coculture systems of prenatal or postnatal murine liver stromal cells (pre-LSCs or post-LSCs, respectively) were used as feeder cells to support freshly isolated mice hepatoblasts. DLK1-positive hepatoblasts were isolated from mouse fetuses (E14.5) and cocultured with feeder cells under adherent conditions. The hepatoblasts' bipotent features, proliferation rate, and colony formation capacity were assessed on day 5 and 7 post-seeding. Immunofluorescence staining showed that the hepatoblasts remained double positive for Alb and Ck19 on both Pre- and Post-LSCs, after 5 and 7 days of coculture. Moreover, application of pre-LSCs as feeder cells significantly increased the number of DLK1-positive cells and their proliferation rate (ie, increased the number of Ki-67 positive cells) on day 7, compared to Post-LSCs group. Finally, to address our ultimate goal, which was an extension of hepatoblasts ex vivo maintenance, 3D spheres of isolated hepatoblasts were, cultured in conditioned medium (CM) derived from pre-LSCs until day 30. It was observed that the CM derived from Pre-LSCs could successfully prolong the maintenance of hepatic progenitor cells (HPCs) in 3D suspension culture.     

Design,Synthesis, Molecular Docking,and Cholinesterase Inhibitory Potential of Phthalimide‐Dithiocarbamate Hybrids as New Agents for Treatment of Alzheimer's Disease

A novel series of phthalimide‐dithiocarbamate hybrids was synthesized and evaluated for in vitro inhibitory potentials against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The anti‐cholinesterase results indicated that among the synthesized compounds, the compounds 7g and 7h showed the most potent anti‐AChE and anti‐BuChE activities, respectively. Molecular docking and dynamic studies of the compounds 7g and 7h , respectively, in the active site of AChE and BuChE revealed that these compounds as well interacted with studied cholinesterases. These compounds also possessed drug‐like properties and were able to cross the BBB.     

Karyoevelution on the genus Onosma L. (Boraginaceae): quantification of chromosome number heterogeneity

In this survey, chromosome counts of different species belonging to the genus Onosma are summarized and then karyological patterns available including frequency of cytotype occurrence, percentage of taxa with particular basic chromosome number and rate of polyploidy in the genus are evaluated. Quantitative parameters have been used to characterize chromosome number (CN) variation. In order to verify if variation patterns differ between three groups of Onosma, Index of CN Heterogeneity (ICNH) was quantified. In addition, meiotic chromosome numbers of 14 populations belonging to 11 species growing in Iran, namely Onosma araratica (2n = 2x = 16), O. asperrima (2n = 2x = 16), O. bulbotricha (2n = 2x = 18), O. kotschyi (2n = 2x = 16), O. microcarpa (2n = 2x = 16), O. nigricaulis (2n = 2x = 16), O. nervosa (2n = 2x = 16), O. obtusifolia (2n = 2x = 16), O. pachypoda (2n = 2x = 16), O. stenosiphon (2n = 2x = 20) and O. subsericea (2n = 2x = 16), were determined. With the exception of O. microcarpa and O. bulbotricha, all chromosome counts are reported for the first time. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Establishment and characterization of two human breast carcinoma cell lines by spontaneous immortalization: Discordance between Estrogen, Progesterone and HER2/neu receptors of breast carcinoma tissues with derived cell lines

Background

Breast cancer is one of the most common cancers among women throughout the world. Therefore, established cell lines are widely used as in vitro experimental models in cancer research.

Methods

Two continuous human breast cell lines, designated MBC1 and MBC2, were successfully established and characterized from invasive ductal breast carcinoma tissues of Malaysian patients. MBC1 and MBC2 have been characterized in terms of morphology analysis, population doubling time, clonogenic formation, wound healing assay, invasion assay, cell cycle, DNA profiling, fluorescence immunocytochemistry, Western blotting and karyotyping.

Results

MBC1 and MBC2 exhibited adherent monolayer epithelial morphology at a passage number of 150. Receptor status of MBC1 and MBC2 show (ER⁺, PR⁺, HER2⁺) and (ER⁺, PR^-, HER2⁺), respectively. These results are in discordance with histopathological studies of the tumoral tissues, which were triple negative and (ER^-, PR^-, HER2⁺) for MBC1 and MBC2, respectively. Both cell lines were capable of growing in soft agar culture, which suggests their metastatic potential. The MBC1 and MBC2 metaphase spreads showed an abnormal karyotype, including hyperdiploidy and complex rearrangements with modes of 52–58 chromosomes per cell.

Conclusions

Loss or gain in secondary properties, deregulation and specific genetic changes possibly conferred receptor changes during the culturing of tumoral cells. Thus, we hypothesize that, among heterogenous tumoral cells, only a small minority of ER⁺/PR⁺/HER2⁺ and ER⁺/PR^-/HER2⁺ cells with lower energy metabolism might survive and adjust easily to in vitro conditions. These cell lines will pave the way for new perspectives in genetic and biological investigations, drug resistance and chemotherapy studies, and would serve as prototype models in Malaysian breast carcinogenesis investigations.