Molecular iodine induces caspase-independent apoptosis in human breast carcinoma cells involving the mitochondria-mediated pathway

Molecular iodine (I2) is known to inhibit the induction and promotion of N-methyl-n-nitrosourea-induced mammary carcinogenesis, to regress 7,12-dimethylbenz(a)anthracene-induced breast tumors in rat, and has also been shown to have beneficial effects in fibrocystic human breast disease. Cytotoxicity of iodine on cultured human breast cancer cell lines, namely MCF-7, MDA-MB-231, MDA-MB-453, ZR-75-1, and T-47D, is reported in this communication. Iodine induced apoptosis in all of the cell lines tested, except MDA-MB-231, shown by sub-G1 peak analysis using flow cytometry. Iodine inhibited proliferation of normal human peripheral blood mononuclear cells; however, it did not induce apoptosis in these cells. The iodine-induced apoptotic mechanism was studied in MCF-7 cells. DNA fragmentation analysis confirmed internucleosomal DNA degradation. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling established that iodine induced apoptosis in a time- and dose-dependent manner in MCF-7 cells. Iodine-induced apoptosis was independent of caspases. Iodine dissipated mitochondrial membrane potential, exhibited antioxidant activity, and caused depletion in total cellular thiol content. Western blot results showed a decrease in Bcl-2 and up-regulation of Bax. Immunofluorescence studies confirmed the activation and mitochondrial membrane localization of Bax. Ectopic Bcl-2 overexpression did not rescue iodine-induced cell death. Iodine treatment induces the translocation of apoptosis-inducing factor from mitochondria to the nucleus, and treatment of N-acetyl-L-cysteine prior to iodine exposure restored basal thiol content, ROS levels, and completely inhibited nuclear translocation of apoptosis-inducing factor and subsequently cell death, indicating that thiol depletion may play an important role in iodine-induced cell death. These results demonstrate that iodine treatment activates a caspase-independent and mitochondria-mediated apoptotic pathway.     

A synthetic route to 9-(polyhydroxyalkyl)purines

Mercuric-ion promoted condensation of 6-chloropurine with acetylated dimethyl dithioacetals of D-ribose and D-arabinose in nitromethane afforded a separable mixture of 1'(S)-2,3,4,5-tetra-O-acetyl-1-(6-chloropurin-9-yl)-1-S-methyl-1-thio-D-ribitol (4) and its 1'(R) diastereomer, and the corresponding 1'(R)-arabinitol analogue (5); the structure of 4 was confirmed by X-ray crystallography. Desulfurization of 4 and 5 by tributylstannane in toluene gave 2,3,4,5-tetra-O-acetyl-1-(6-chloropurin-9-yl)-1-deoxy-D-ribitol (7) and the arabinitol analogue 8, convertible by the action of thiourea into the 1,6-dihydro-6-thioxopurin-9-yl analogues 9 and 10, which on deacetylation furnished the corresponding acyclic-sugar nucleosides 11 and 12.     

PathSys: integrating molecular interaction graphs for systems biology

Background  

The goal of information integration in systems biology is to combine information from a number of databases and data sets, which are obtained from both high and low throughput experiments, under one data management scheme such that the cumulative information provides greater biological insight than is possible with individual information sources considered separately.     

IL-6, in synergy with IL-7 or IL-15, stimulates TCR-independent proliferation and functional differentiation of CD8+ T lymphocytes

Recent reports have shown that IL-21, in synergy with IL-15, stimulates proliferation of CD8(+) T lymphocytes in the absence of signaling via the TCR. In this study, we show that IL-6, which induces phosphorylation of STAT3 similarly to IL-21, also can stimulate proliferation of CD8(+) T cells in synergy with IL-7 or IL-15. IL-6 displays a stronger synergy with IL-7 than with IL-15 to stimulate naive CD8(+) T cells. Concomitant stimulation by IL-6 or IL-21 augments phosphorylation and DNA-binding activity of STAT5 induced by IL-7 or IL-15. Like IL-21, IL-6 reduces the TCR signaling threshold required to stimulate CD8(+) T cells. Prior culture of P14 TCR transgenic CD8 T cells with IL-6 or IL-21 in the presence of IL-7 or IL-15 augments their proliferation and cytolytic activity upon subsequent stimulation by Ag. Furthermore, cytokine stimulation induces quantitatively and qualitatively distinct phenotypic changes on CD8(+) T cells compared with those induced by TCR signaling. We propose that the ability of IL-6 to induce TCR-independent activation of CD8(+) T cells in synergy with IL-7 or IL-15 may play an important role in the transition from innate to adaptive immunity.     

An <Emphasis Type="Italic">ipdC</Emphasis> gene knock-out of <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> strain SM and its implications on indole-3-acetic acid biosynthesis and plant growth promotion

The indole-3-pyruvate decarboxylase gene (ipdC), coding for a key enzyme of the indole-3-pyruvic acid pathway of IAA biosynthesis in Azospirillum brasilense SM was functionally disrupted in a site-specific manner. This disruption was brought about by group II intron-based Targetron gene knock-out system as other conventional methods were unsuccessful in generating an IAA-attenuated mutant. Intron insertion was targeted to position 568 on the sense strand of ipdC, resulting in the knock-out strain, SMIT568s10 which showed a significant (∼50%) decrease in the levels of indole-3-acetic acid, indole-3-acetaldehyde and tryptophol compared to the wild type strain SM. In addition, a significant decrease in indole-3-pyruvate decarboxylase enzyme activity by ∼50% was identified confirming a functional knock-out. Consequently, a reduction in the plant growth promoting response of strain SMIT568s10 was observed in terms of root length and lateral root proliferation as well as the total dry weight of the treated plants. Residual indole-3-pyruvate decarboxylase enzyme activity, and indole-3-acetic acid, tryptophol and indole-3-acetaldehyde formed along with the plant growth promoting response by strain SMIT568s10 in comparison with an untreated set suggest the presence of more than one copy of ipdC in the A. brasilense SM genome.     

Role of lutoid membrane transport and protein synthesis in the regeneration mechanism of latex in different <Emphasis Type="Italic">Hevea</Emphasis> clones

Natural rubber (cis-1,4 polyisoprene) is synthesised in the milky cytoplasm, the latex, of specialized cells called laticifers in the bark tissues of the rubber tree (Hevea brasiliensis). Regeneration mechanism of latex after each tapping (controlled wounding of the bark) was studied in relation to lutoid membrane enzymes and protein synthesis in twelve rubber clones with varying yield potentials during the peak rubber yielding season. High activity of membrane enzymes and better availability of biochemical energy [ATP] were observed in clones viz; RRII 105, RRIM 600, PB 260, RRII 422 and RRII 430. The highest protein biosynthetic capacity was noticed in clone PB 260 and RRIM 600. However, high ATP content, increased invertase activity and protein biosynthesis were observed in the medium yielding clone GT1 compared to clones with low rubber yield potential. Very low sugar content and increased invertase activity in the latex of clone PB 260 indicated intense latex metabolism with high protein turnover that implies fast recouping of the cellular metabolites lost during latex harvesting. Clone PB 217 was characterized by very high sucrose and low ATP concentration and ATPase activity in latex indicating slow metabolism and hence be suitable for inducing latex metabolism using ethylene stimulant. Low rubber yielding clones such as RRII 33 and RRII 38 were consistently recorded a high sucrose content but very low activity of membrane enzymes, reduced ATP concentration and low protein biosynthesis in latex. Among the recently released modern clones (RRII 400 series), latex regeneration capacity was higher in RRII 422 and RRII 430. The significance of lutoid membrane transport and protein synthesis is discussed in relation to general latex metabolism of these rubber clones. The outcome of this study would be helpful to design suitable latex harvesting systems and yield stimulation methods for optimizing latex production in each clone based on metabolic profiling.