A novel mutation of ALK2, L196P, found in the most benign case of fibrodysplasia ossificans progressiva activates BMP-specific intracellular signaling equivalent to a typical mutation, R206H

Naphthoquinone derivatives have been reported to possess various pharmacological activities, such as antiplatelet, anticancer, antifungal, and antiviral properties. In this study, we investigated the effects of a newly-synthesized naphthoquinone derivative, 2-decylamino-5,8-dimethoxy-1,4-naphthoquinone (2-decylamino-DMNQ), on VSMC proliferation and examined the molecular basis of the underlying mechanism. In a dose-dependent manner, 2-decylamino-DMNQ inhibited PDGF-stimulated VSMC proliferation with no apparent cytotoxic effect. While 2-decylamino-DMNQ did not affect PDGF-Rβ or Akt, it did inhibit the phosphorylation of Erk1/2 and PLCγ1 induced by PDGF. Moreover, 2-decylamino-DMNQ suppressed DNA synthesis through the arrest of cell cycle progression at the G₀/G₁ phase, including the suppression of pRb phosphorylation and a decrease in PCNA expression, which was related to the downregulation of cell cycle regulatory factors, such as cyclin D1/E and CDK 2/4. It was demonstrated that both U0126, an Erk1/2 inhibitor, and U73122, a PLCγ inhibitor, increased the proportion of cells in the G₀/G₁ phase of the cell cycle. Thus, these results suggest that 2-decylamino DMNQ has an inhibitory effect on PDGF-induced VSMC proliferation and the mechanism of this action is through cell cycle arrest at the G₀/G₁ phase. This may be a useful tool for studying interventions for vascular restenosis in coronary revascularization procedures and stent implantation.     

The interplay of mRNA stimulatory signals required for AUU-mediated initiation and programmed -1 ribosomal frameshifting in decoding of transposable element IS911

The IS911 bacterial transposable element uses -1 programmed translational frameshifting to generate the protein required for its mobility: translation initiated in one gene (orfA) shifts to the -1 frame and continues in a second overlapping gene (orfB), thus generating the OrfAB transposase. The A-AAA-AAG frameshift site of IS911 is flanked by two stimulatory elements, an upstream Shine-Dalgarno sequence and a downstream stem-loop. We show here that, while they can act independently, these stimulators have a synergistic effect when combined. Mutagenic analyses revealed features of the complex stem-loop that make it a low-efficiency stimulator. They also revealed the dual role of the upstream Shine-Dalgarno sequence as (i) a stimulator of frameshifting, by itself more potent than the stem-loop, and (ii) a mandatory determinant of initiation of OrfB protein synthesis on an AUU codon directly preceding the A6G motif. Both roles rely on transient base pairing of the Shine-Dalgarno sequence with the 3' end of 16S rRNA. Because of its effect on frameshifting, the Shine-Dalgarno sequence is an important determinant of the level of transposase in IS911-containing cells, and hence of the frequency of transposition.     

The genes sup-7 X and sup-5 III of C. elegans suppress amber nonsense mutations via altered transfer RNA

The sup-5 III and sup-7 X suppressors in C. elegans have previously been shown to have many genetic properties in common with tRNA nonsense suppressors of microorganisms. We report here the results of two lines of investigation into the molecular basis of these suppressors. In one, which sought to determine the nature of suppressible alleles, we demonstrate through DNA sequencing studies that a suppressible allele, unc-54(e 1300) I, of the myosin heavy chain gene contains a C leads to T substitution, which changes a glutamine codon to amber terminator at residue 1903. In the other approach, which sought to define the nature of the suppressing activity, we show through in vitro translation studies that tRNA fractions from the suppressor strains, but not wild-type, promote the specific readthrough of amber terminators of three different messenger RNAs. We conclude that sup-5 and sup-7 result in readthrough of amber terminators in vivo through an altered tRNA.     

Cytotoxic and apoptotic activities of Amorphophallus campanulatus (Roxb.) Bl. tuber extracts against human colon carcinoma cell line HCT-15

Colorectal cancer is one of the leading causes of cancer death worldwide and is the third most common form of malignancy in both men and women. Several possible colon cancer chemopreventive agents are found in edible plants. Amorphophallus campanulatus (Roxb.) Blume (family: Araceae) is a tuber crop, largely cultivated throughout the plains of India for using its corm as food. This tuber has also been traditionally used for the treatment of abdominal tumors, liver diseases, piles etc. The aim of this study was to evaluate the dose-dependent cytotoxic and apoptosis inducing effects of the sub fractions of A. campanulatus tuber methanolic extract (ACME) viz. petroleum ether fraction (PEF), chloroform fraction (CHF), ethyl acetate fraction (EAF) and methanolic fraction (MEF) on the colon cancer cell line, HCT-15. Antiproliferative effects of the sub fractions of ACME were studied by MTT assay. Apoptotic activity was assessed by DAPI, Annexin V-FITC and JC-1 fluorescent staining. The chemotherapeutic drug, 5-flurouracil (5-FU) was used as positive drug control. The sub fractions of ACME significantly inhibited the proliferation of HCT-15 cells in a dose-dependent manner. In addition, the extracts were found to induce apoptosis and were confirmed by DAPI, Annexin V-FITC and JC-1 fluorescent staining. A pronounced results of cytotoxic and apoptotic activities were observed in the cells treated with 5-FU and CHF, whereas, EAF and MEF treated cells exhibited a moderate result and the least effect was observed in PEF treated cells. Our results suggested that, among the sub fractions of ACME, CHF had potent cytotoxic and apoptotic activity and thus it could be explored as a novel target for anticancer drug development. Furthermore, these findings confirm that the sub fractions of ACME dose-dependently suppress the proliferation of HCT-15 cells by inducing apoptosis.     

Elucidation of the Block to Herpes Simplex Virus Egress in the Absence of Tegument Protein UL16 Reveals a Novel Interaction with VP22

UL16 is a tegument protein of herpes simplex virus (HSV) that is conserved among all members of the Herpesviridae, but its function is poorly understood. Previous studies revealed that UL16 is associated with capsids in the cytoplasm and interacts with the membrane protein UL11, which suggested a “bridging” function during cytoplasmic envelopment, but this conjecture has not been tested. To gain further insight, cells infected with UL16-null mutants were examined by electron microscopy. No defects in the transport of capsids to cytoplasmic membranes were observed, but the wrapping of capsids with membranes was delayed. Moreover, clusters of cytoplasmic capsids were often observed, but only near membranes, where they were wrapped to produce multiple capsids within a single envelope. Normal virion production was restored when UL16 was expressed either by complementing cells or from a novel position in the HSV genome. When the composition of the UL16-null viruses was analyzed, a reduction in the packaging of glycoprotein E (gE) was observed, which was not surprising, since it has been reported that UL16 interacts with this glycoprotein. However, levels of the tegument protein VP22 were also dramatically reduced in virions, even though this gE-binding protein has been shown not to depend on its membrane partner for packaging. Cotransfection experiments revealed that UL16 and VP22 can interact in the absence of other viral proteins. These results extend the UL16 interaction network beyond its previously identified binding partners to include VP22 and provide evidence that UL16 plays an important function at the membrane during virion production.     

The oxidation of benzo[a]pyrene-7,8-dihydrodiol mediated by lipid peroxidation in the rat intestine and the effect of dietary lipids

This study has demonstrated that the microsomal fraction of the rat small intestinal mucosa has the capacity to catalyse the oxidation of benzo[a]pyrene(BP)-7,8-diol to BP-diol-epoxides (BPDEs) both by a mechanism involving the mixed-function oxidase system (NADPH-dependent) and as a result of the initiation of peroxidation of the membrane phospholipids by ferrous ions, ascorbate and ADP. The NADPH-dependent reaction was fastest in the proximal part of the intestine and resulted in the formation of approximately equal amounts of BPDE I and BPDE II. The lipid peroxidation-catalysed reaction favoured the production of BPDE I and was maximal in the middle region of the intestine, closely paralleling the rate of lipid peroxidation in the intestinal sections. Feeding rats on a cod liver oil diet, rich in C20:5 and C22:6, significantly increased the incorporation of these fatty acids into the microsomal fractions. This resulted in a greatly increased rate of lipid peroxidation in vitro and a significantly higher rate of lipid peroxidation-catalysed BP-7,8-diol oxidation compared to rats fed fat-free, mono-unsaturated lard or corn oil (58% C18:2) diets. Thus the rate of conversion of BP-7,8-diol to its ultimate carcinogenic forms during lipid peroxidation in the intestinal fractions of rats fed a polyunsaturated fat was quantitatively more important than the NADPH-catalysed reaction as measured in vitro.     

Regulation of sugar and ethanol metabolism in Saccharomyces cerevisiae

This review briefly surveys the literature on the nature, regulation, genetics, and molecular biology of the major energy-yielding pathways in yeasts, with emphasis on Saccharomyces cerevisiae. While sugar metabolism has received the lion's share of attention from workers in this field because of its bearing on the production of ethanol and other metabolites, more attention is now being paid to ethanol metabolism and the regulation of aerobic metabolism by fermentable and nonfermentable substrates. The utility of yeast as a highly manipulable organism and the discovery that yeast metabolic pathways are subject to the same types of control as those of higher cells open up many opportunities in such diverse areas as molecular evolution and cancer research.     

Scrapie, ribosomal proteins and biological information

Consideration of the autocatalytic synthesis of ribosomal proteins leads to a criterion for the infectivity of a foreign proteinaceous species in terms of the biochemical rate constants governing the propagation of errors during the translation of genetic information in a model system. Evidence pertaining to the suggestion that scrapie and its analogues are caused by proteinaceous infectious agents (prions) which replicate by invading the translation process and altering ribosomal specificity is examined. It is found that anomalous aetiological features of scrapie infection are explained by the model. An analysis suggesting that the possibility of prion replication undermines the basis of current molecular biological theory is provided and it is concluded that the exclusive identification of biological information with nucleic acid sequences is unjustified.