1-Benzyl derivatives of 5-(arylamino)uracils as anti-HIV-1 and anti-EBV agents

Pyrimidine analogs have long found use over a broad chemotherapeutic spectrum. In an effort to further explore the antiviral potential of several uracil derivatives previously synthesized in our laboratories, a series of benzylated pyrimidines were designed and synthesized. Introduction of the benzyl residue onto the 5-phenylaminouracil scaffold was carried out using 2,4-bis(trimethylsilyloxy)pyrimidine with the corresponding benzyl bromides. Similarly, 1-benzyl-5-(benzylamino)- and 1-benzyl-5-(phenethylamino)uracils were obtained via amination of 1-benzyl-5-bromouracils with benzylamine or phenylethylamine. The results of the broad screen antiviral studies revealed that compounds 5 and 11 exhibit promising inhibitory activity against HIV-1 in CEM-SS culture. A 50% protective effect was observed at concentrations of 11.9 and 9.5 μМ, respectively. Moreover, compounds 8 and 3 exhibited good inhibitory effects against EBV in АKАТА cell culture with EC₅₀ values of 2.3 and 12 μM, respectively. The synthesis and biological studies are detailed herein.     

Synchronous intra-Golgi transport induces the release of Ca from the Golgi apparatus

The mechanisms of secretory transport through the Golgi apparatus remain an issue of debate. The precise functional importance of calcium ions (Ca²⁺) for intra-Golgi transport has also been poorly studied. Here, using different approaches to measure free Ca²⁺ concentrations in the cell cytosol ([Ca²⁺]_cyt) and inside the lumen of the Golgi apparatus ([Ca²⁺]_GA), we have revealed transient increases in [Ca²⁺]_cyt during the late phase of intra-Golgi transport that are concomitant with a decline in the maximal [Ca²⁺]_GA restoration ability. Thus, this redistribution of Ca²⁺ from the Golgi apparatus into the cytosol during the movement of cargo through the Golgi apparatus appears to have a role in intra-Golgi transport, and mainly in the late Ca²⁺-dependent phase of SNARE-regulated fusion of Golgi compartments.     

Structure- and function-based characterization of a new phosphoglycolate phosphatase from Thermoplasma acidophilum

The protein TA0175 has a large number of sequence homologues, most of which are annotated as unknown and a few as belonging to the haloacid dehalogenase superfamily, but has no known biological function. Using a combination of amino acid sequence analysis, three-dimensional crystal structure information, and kinetic analysis, we have characterized TA0175 as phosphoglycolate phosphatase from Thermoplasma acidophilum. The crystal structure of TA0175 revealed two distinct domains, a larger core domain and a smaller cap domain. The large domain is composed of a centrally located five-stranded parallel beta-sheet with strand order S10, S9, S8, S1, S2 and a small beta-hairpin, strands S3 and S4. This central sheet is flanked by a set of three alpha-helices on one side and two helices on the other. The smaller domain is composed of an open faced beta-sandwich represented by three antiparallel beta-strands, S5, S6, and S7, flanked by two oppositely oriented alpha-helices, H3 and H4. The topology of the large domain is conserved; however, structural variation is observed in the smaller domain among the different functional classes of the haloacid dehalogenase superfamily. Enzymatic assays on TA0175 revealed that this enzyme catalyzed the dephosphorylation of phosphoglycolate in vitro with similar kinetic properties seen for eukaryotic phosphoglycolate phosphatase. Activation by divalent cations, especially Mg2+, and competitive inhibition behavior with Cl- ions are similar between TA0175 and phosphoglycolate phosphatase. The experimental evidence presented for TA0175 is indicative of phosphoglycolate phosphatase.     

Modulation of Rac localization and function by dynamin

The GTPase dynamin controls a variety of endocytic pathways, participates in the formation of phagosomes, podosomal adhesions, and invadopodia, and in regulation of the cytoskeleton and apoptosis. Rac, a member of the Rho family of small GTPases, controls formation of lamellipodia and focal complexes, which are critical in cell migration and phagocytosis. We now show that disruption of dynamin(-2) function alters Rac localization and inhibits cell spreading and lamellipodia formation even though Rac is activated. Dominant-negative K44A dynamin(-2) inhibited cell spreading and lamellipodia formation on fibronectin without blocking cell adhesion; dynamin(-2) depletion by specific small interfering RNA inhibited lamellipodia in a similar manner. Dyn2(K44A) induced Rac mislocalization away from cell edges, into abnormal dorsal ruffles, and led to increased total Rac activity. Fluorescence resonance energy transfer imaging of Rac activity confirmed its predominant localization to aberrant dorsal ruffles in the presence of dominant-negative dyn2(K44A). Dyn2(K44A) induced the accumulation of tubulated structures bearing membrane-bound Rac-GFP. Constitutively active but not wild-type GFP-Rac was found on macropinosomes and Rac-dependent, platelet-derived growth factor-induced macropinocytosis was abolished by Dyn2(K44A) expression. These data suggest an indispensable role of dynamin in Rac trafficking to allow for lamellipodia formation and cell spreading.     

The functional significance of the monomeric and trimeric states of the photosystem II light harvesting complexes

The main light harvesting complex of photosystem II in plants, LHCII, exists in a trimeric state. To understand the biological significance of trimerization, a comparison has been made been LHCII trimers and LHCII monomers prepared by treatment with phospholipase. The treatment used caused no loss of chlorophyll, but there was a difference in carotenoid composition, together with the previously observed alterations in absorption spectrum. It was found that, when compared to monomers, LHCII trimers showed increased thermal stability and a reduced structural flexibility as determined by the decreased rate and amplitude of fluorescence quenching in low-detergent concentration. It is suggested that LHCII should be considered as having two interacting domains: the lutein 1 domain, the site of fluorescence quenching [Wentworth et al. (2003) J. Biol. Chem. 278, 21845-21850], and the lutein 2 domain. The lutein 2 domain faces the interior of the trimer, the differences in absorption spectrum and carotenoid binding in trimers compared to monomers indicating that the trimeric state modulates the conformation of this domain. It is suggested that the lutein 2 domain controls the conformation of the lutein 1 domain, thereby providing allosteric control of fluorescence quenching in LHCII. Thus, the pigment configuration and protein conformation in trimers is adapted for efficient light harvesting and enhanced protein stability. Furthermore, trimers exhibit the optimum level of control of energy dissipation by modulating the development of the quenched state of the complex.     

Tiam1 takes PARt in cell polarity

Cell polarity is an essential requirement for the proper tissue development of complex organisms. This is underscored by in vivo studies showing that loss of cell polarity contributes to the formation and progression of tumours. Evolutionary conserved multiprotein complexes, such as the Par3-Par6-aPKC or, in short, the Par polarity complex, regulate the establishment of cell polarity. The small Rho GTPases CDC42 and Rac control the activation of the Par polarity complex. Evidence now implicates the Rac activator Tiam1 as a crucial component of the Par complex in regulating neuronal (axonal) and epithelial (apical-basal) polarity. Our current knowledge places Tiam1 at the centre of a pivotal biological process, the establishment and maintenance of cell polarity, and suggests that deregulation of the Tiam1-Par complex contributes to tumourigenicity.     

Evaluation of the Sterility Test for Detection of Microbial Contaminants of Allografts

Tissue banks routinely use a sterility test to determine the suitability of processed tissue prior to release. However, many tissue banks also accompany the sterility test with additional types of media to ensure detection of slower-growing or more fastidious organisms that may not be detected in the standard two media/two incubation temperature sterility test. This study was designed to determine if a standard sterility test is capable of detecting the wide variety of organisms that may be isolated from human tissue thereby making the additional plated media unnecessary. More than 100 isolates, representing more than 90 different species were tested. All isolates exhibited growth in at least one of the two standard sterility test media within the 14-day incubation period.     

Global and local mechanisms of forebrain and midbrain patterning

During the past years, major advances have been made in understanding the sequential events involved in neural plate patterning. Positional information is already conferred to cells of the neural plate at the time of its induction in the ectoderm. The interplay between the BMP- and the Fgf- signaling pathways leads to the induction of neural cell fates. Thus, neural induction and neural plate patterning are overlapping processes. Later, at the end of gastrulation, positional cell identities within the neural plate are refined and maintained by the action of several neural plate organizers. By locally emitting signaling molecules, they influence the fate of the developing nervous system with high regional specificity. Recent advances have been made both in understanding the mechanisms that dictate the relative position of these organizers and in how signaling molecules spread from them with high spatial and temporal resolution.     

Aldosterone stimulates activity and surface expression of NHE3 in human primary proximal tubule epithelial cells (RPTEC).

The steroid hormone aldosterone is a major regulator of extracellular volume and blood pressure. Aldosterone effectors are for example the epithelial Na(+) channel (ENaC), the Na(+)-K(+)-ATPase and the proximal tubule Na(+)/H(+) exchanger isoform 3 (NHE3). The aim of this study was to investigate whether aldosterone acts directly on proximal tubule cells to stimulate NHE3 and if so whether the EGF-receptor (EGFR) is involved. For this purpose, primary human renal proximal tubule cells were exposed to aldosterone. NHE3 activity was determined from Na(+)- dependent pH-recovery, NHE3 surface expression was determined by biotinylation and immunoblotting. EGFR-expression was assessed by ELISA. pH(i)- measurements revealed an aldosterone-induced increase in NHE3 activity, which was inhibited by the mineralocorticoid receptor blocker spironolactone and by the EGFR-kinase inhibitor AG1478. Immunoprecipitation and immunoblot analysis showed an aldosterone-induced increase in NHE3 surface expression, which was also inhibited by spironolactone and AG1478. Furthermore, aldosterone enhanced EGFR-expression. In conclusion, aldosterone stimulates NHE3 in human proximal tubule cells. The underlying mechanisms include AG1478 inhibitable kinase and are paralleled by enhanced EGFR expression, which could be compatible with EGF-receptor-pathway-dependent surface expression and activity of NHE3 in human primary renal proximal tubule epithelial cells.     

N-(4-{[4-(1H-Benzoimidazol-2-yl)-arylamino]-methyl}-phenyl)-benzamide derivatives as small molecule heparanase inhibitors

A novel class of N-(4-{[4-(1H-benzoimidazol-2-yl)-arylamino]-methyl}-phenyl)-benzamides are described as inhibitors of the endo-beta-glucuronidase heparanase. Among them are N-(4-{[4-(1H-benzoimidazol-2-yl)-phenylamino]-methyl}-phenyl)-3-bromo-4-methoxy-benzamide (15h), and N-(4-{[5-(1H-benzoimidazol-2-yl)-pyridin-2-ylamino]-methyl}- phenyl)-3-bromo-4-methoxy-benzamide (23) which displayed good heparanase inhibitory activity (IC(50) 0.23-0.29 microM), with the latter showing oral exposure in mice.