Lansoprazole protects and heals gastric mucosa from non-steroidal anti-inflammatory drug (NSAID)-induced gastropathy by inhibiting mitochondrial as well as Fas-mediated death pathways with concurrent induction of mucosal cell renewal

We have investigated the mechanism of antiapoptotic and cell renewal effects of lansoprazole, a proton pump inhibitor, to protect and heal gastric mucosal injury in vivo induced by indomethacin, a non-steroidal anti-inflammatory drug (NSAID). Lansoprazole prevents indomethacin-induced gastric damage by blocking activation of mitochondrial and Fas pathways of apoptosis. Lansoprazole prevents indomethacin-induced up-regulation of proapoptotic Bax and Bak and down-regulation of antiapoptotic Bcl-2 and Bcl(xL) to maintain the normal proapoptotic/antiapoptotic ratio and thereby arrests indomethacin-induced mitochondrial translocation of Bax and collapse of mitochondrial membrane potential followed by cytochrome c release and caspase-9 activation. Lansoprazole also inhibits indomethacin-induced Fas-mediated mucosal cell death by down-regulating Fas or FasL expression and inhibiting caspase-8 activation. Lansoprazole favors mucosal cell renewal simultaneously by stimulating gene expression of prosurvival proliferating cell nuclear antigen, survivin, epidermal growth factor, and basic fibroblast growth factor. The up-regulation of Flt-1 further indicates that lansoprazole activates vascular epidermal growth factor-mediated controlled angiogenesis to repair gastric mucosa. Lansoprazole also stimulates the healing of already formed ulcers induced by indomethacin. Time course study of healing indicates that it switches off the mitochondrial death pathway completely but not the Fas pathway. However, lansoprazole heals mucosal lesions almost completely after overcoming the persisting Fas pathway, probably by favoring the prosurvival genes expression. This study thus provides the detailed mechanism of antiapoptotic and prosurvival effects of lansoprazole for offering gastroprotection against indomethacin-induced gastropathy.     

Resonant and non‐resonant energy transfer from Ce3+ → X (X = Tb3+, Eu3+ or Dy3+) in NaMgSO4F material

An inorganic NaMgSO₄F fluoride material was prepared by the wet chemical method and studied for its photoluminescence (PL) and resonant–non‐resonant energy transfer (RET and NORET) capabilities between Ce³⁺ → Tb³⁺, Ce³⁺ → Eu³⁺ and Ce³⁺ → Dy³⁺ rare earth ions. The Tb³⁺ emission for Ce³⁺ → Tb³⁺ transfers under ultraviolet (UV) wavelengths peaked at 491, 547, and 586 nm, for excitation at 308 nm due to ⁵D₄ → ⁷F_J (J = 4, 5, 6) transitions. Eu emission spectra were observed at 440 nm (Eu²⁺), 593 nm and 616 nm (Eu³⁺) recorded for different concentrations of materials, whereas Dy³⁺ emission from Ce³⁺ → Dy³⁺ transfer under UV wavelengths peaked at 485 nm and 577 nm due to ⁴F_9/2 → ⁶H_15/2 and ⁶H_13/2 transitions. The purpose of the present study is to understand the RET and NORET effects of Tb³⁺, Eu³⁺ and Dy³⁺ co‐doping in a NaMgSO₄F:Ce³⁺ luminescent material, which could be used as a green‐emitting material for lamp phosphors.     

Molecular characterization and localization of Plasmodium falciparum choline kinase

Generation of phosphocholine by choline kinase is important for phosphatidylcholine biosynthesis via Kennedy pathway and phosphatidylcholine biosynthesis is essential for intraerythrocytic growth of malaria parasite. A putative gene (Gene ID PF14_0020) in chromosome 14, having highest sequence homology with choline kinase, has been identified by BLAST searches from P. falciparum genome sequence database. This gene has been PCR amplified, cloned, over-expressed and characterized. Choline kinase activity of the recombinant protein (PfCK) was validated as it catalyzed the formation of phosphocholine from choline in presence of ATP. The K(m) values for choline and ATP are found to be 145+/-20 microM and 2.5+/-0.3 mM, respectively. PfCK can phosphorylate choline efficiently but not ethanolamine. Southern blotting indicates that PfCK is a single copy gene and it is a cytosolic protein as evidenced by Western immunoblotting and confocal microscopy. A model structure of PfCK was constructed based on the crystal structure of choline kinase of C. elegans to search the structural homology. Consistent with the homology modeling predictions, CD analysis indicates that the alpha and beta content of PfCK are 33% and 14%, respectively. Since choline kinase plays a vital role for growth and multiplication of P. falciparum during intraerythrocytic stages, we can suggest that this well characterized PfCK may be exploited in the screening of new choline kinase inhibitors to evaluate their antimalarial activity.     

Role of Mitochondrial Dynamics in Neuronal Development: Mechanism for Wolfram Syndrome

Deficiency of the protein Wolfram syndrome 1 (WFS1) is associated with multiple neurological and psychiatric abnormalities similar to those observed in pathologies showing alterations in mitochondrial dynamics. The aim of this study was to examine the hypothesis that WFS1 deficiency affects neuronal function via mitochondrial abnormalities. We show that down-regulation of WFS1 in neurons leads to dramatic changes in mitochondrial dynamics (inhibited mitochondrial fusion, altered mitochondrial trafficking, and augmented mitophagy), delaying neuronal development. WFS1 deficiency induces endoplasmic reticulum (ER) stress, leading to inositol 1,4,5-trisphosphate receptor (IP₃R) dysfunction and disturbed cytosolic Ca²⁺ homeostasis, which, in turn, alters mitochondrial dynamics. Importantly, ER stress, impaired Ca²⁺ homeostasis, altered mitochondrial dynamics, and delayed neuronal development are causatively related events because interventions at all these levels improved the downstream processes. Our data shed light on the mechanisms of neuronal abnormalities in Wolfram syndrome and point out potential therapeutic targets. This work may have broader implications for understanding the role of mitochondrial dynamics in neuropsychiatric diseases.     

RNAi-mediated silencing of spermidine synthase gene results in reduced reproductive potential in tobacco

Spermidine belongs to a class of polycationic compounds known as polyamines. Polyamines are known to be involved in a wide range of biological processes but the exact role and contribution of different polyamines to these processes are still not clear. In the present study, we have tried to understand the contribution of triamine spermidine to the growth and development of tobacco by downregulating spermidine synthase gene (SPDS) using RNA interference. Down-regulatioin of SPDS gene resulted in decreased spermidine levels and a slight increase in the levels of its precursor, the diamine putrescine and the molecule downstream of Spd, the tetraamine spermine. While the vegetative growth of the transgenics remained largely unaffected, SPDS down-regulation resulted in smaller size of flowers, decreased pollen viability and seed setting, and a reduced and delayed seed germination. When subjected to abiotic stress, the transgenics showed an increased tolerance to salinity and drought conditions owing to a steady intracellular pool of putrescine and spermine. The results not only highlight the importance of spermidine in determining reproductive potential in plants but have also help delineate its function from that of putrescine and spermine.     

IFI16 protein mediates the anti-inflammatory actions of the type-I interferons through suppression of activation of caspase-1 by inflammasomes

Background

Type-I interferons (IFNs) are used to treat certain inflammatory diseases. Moreover, activation of type-I IFN-signaling in immune cells inhibits the production of proinflammatory cytokines and activation of inflammasomes. However, the molecular mechanisms remain largely unknown. Upon sensing cytosolic double-stranded DNA, the AIM2 protein forms the AIM2-ASC inflammasome, resulting in activation of caspase-1. Given that the IFI16 and AIM2 proteins are IFN-inducible and can heterodimerize with each other, we investigated the regulation of IFI16, AIM2, and inflammasome proteins by type-I and type-II IFNs and explored whether the IFI16 protein could negatively regulate the activation of the AIM2 (or other) inflammasome.

Methodology/ Principal Findings

We found that basal levels of the IFI16 and AIM2 proteins were relatively low in peripheral blood monocytes (CD14⁺) and in the THP-1 monocytic cell line. However, treatment of THP-1 cells with type-I (IFN-α or β) or type-II (IFN-γ) IFN induced the expression levels of IFI16, AIM2, ASC and CASP1 proteins. The induced levels of IFI16 and AIM2 proteins were detected primarily in the cytoplasm. Accordingly, relatively more IFI16 protein bound with the AIM2 protein in the cytoplasmic fraction. Notably, increased expression of IFI16 protein in transfected HEK-293 cells inhibited activation of caspase-1 by the AIM2-ASC inflammasome. Moreover, the constitutive knockdown of the IFI16 expression in THP-1 cells increased the basal and induced [induced by poly(dA:dT) or alum] activation of the caspase-1 by the AIM2 and NLRP3 inflammasomes.

Conclusions/Significance

Our observations revealed that the type-I and type-II IFNs induce the expression of IFI16, AIM2, and inflammasome proteins to various extents in THP-1 cells and the expression of IFI16 protein in THP-1 cells suppresses the activation of caspase-1 by the AIM2 and NLRP3 inflammasomes. Thus, our observations identify the IFI16 protein as a mediator of the anti-inflammatory actions of the type-I IFNs.     

Characterization ofβ-lactamase fromMycobacterium smegmatis SN2

-Lactamase fromMycohacterium smegamatis SN2 was purified to homogeneity. The molecular weight of the enzyme was 30,000 and the isoelectric point was 4.1. The enzyme showed maximal activity at pH 6.5 and 56°C and resembled the plasmid-mediated TEM-type -lactamases commonly encountered in gram-negative bacteria in substrate profile. The enzyme shared antigenic structure with -lactamase fromMycobacterium butyricum ATCC 19979 andEscherichia coli HB101 (pBR322).