Gelsolin Induces Colorectal Tumor Cell Invasion via Modulation of the Urokinase-Type Plasminogen Activator Cascade

Gelsolin is a cytoskeletal protein which participates in actin filament dynamics and promotes cell motility and plasticity. Although initially regarded as a tumor suppressor, gelsolin expression in certain tumors correlates with poor prognosis and therapy-resistance. In vitro, gelsolin has anti-apoptotic and pro-migratory functions and is critical for invasion of some types of tumor cells. We found that gelsolin was highly expressed at tumor borders infiltrating into adjacent liver tissues, as examined by immunohistochemistry. Although gelsolin contributes to lamellipodia formation in migrating cells, the mechanisms by which it induces tumor invasion are unclear. Gelsolin's influence on the invasive activity of colorectal cancer cells was investigated using overexpression and small interfering RNA knockdown. We show that gelsolin is required for invasion of colorectal cancer cells through matrigel. Microarray analysis and quantitative PCR indicate that gelsolin overexpression induces the upregulation of invasion-promoting genes in colorectal cancer cells, including the matrix-degrading urokinase-type plasminogen activator (uPA). Conversely, gelsolin knockdown reduces uPA levels, as well as uPA secretion. The enhanced invasiveness of gelsolin-overexpressing cells was attenuated by treatment with function-blocking antibodies to either uPA or its receptor uPAR, indicating that uPA/uPAR activity is crucial for gelsolin-dependent invasion. In summary, our data reveals novel functions of gelsolin in colorectal tumor cell invasion through its modulation of the uPA/uPAR cascade, with potentially important roles in colorectal tumor dissemination to metastatic sites.     

Carnitine Deficiency in OCTN2?/? Newborn Mice Leads to a Severe Gut and Immune Phenotype with Widespread Atrophy,Apoptosis and a Pro-Inflammatory Response

We have investigated the gross, microscopic and molecular effects of carnitine deficiency in the neonatal gut using a mouse model with a loss-of-function mutation in the OCTN2 (SLC22A5) carnitine transporter. The tissue carnitine content of neonatal homozygous (OCTN2^−/−) mouse small intestine was markedly reduced; the intestine displayed signs of stunted villous growth, early signs of inflammation, lymphocytic and macrophage infiltration and villous structure breakdown. Mitochondrial β-oxidation was active throughout the GI tract in wild type newborn mice as seen by expression of 6 key enzymes involved in β-oxidation of fatty acids and genes for these 6 enzymes were up-regulated in OCTN2^−/− mice. There was increased apoptosis in gut samples from OCTN2^−/− mice. OCTN2^−/− mice developed a severe immune phenotype, where the thymus, spleen and lymph nodes became atrophied secondary to increased apoptosis. Carnitine deficiency led to increased expression of CD45-B220⁺ lymphocytes with increased production of basal and anti-CD3-stimulated pro-inflammatory cytokines in immune cells. Real-time PCR array analysis in OCTN2^−/− mouse gut epithelium demonstrated down-regulation of TGF-β/BMP pathway genes. We conclude that carnitine plays a major role in neonatal OCTN2^−/− mouse gut development and differentiation, and that severe carnitine deficiency leads to increased apoptosis of enterocytes, villous atrophy, inflammation and gut injury.     

Synthesis of 2-[3-(7-Chloro-quinolin-4-ylamino)-alkyl]-1-(substituted phenyl)-2,3,4,9-tetrahydro-1H-beta-carbolines as a new class of antimalarial agents

A series of hybrid molecules 2-[3-(7-Chloro-quinolin-4-ylamino)-alkyl]-1-(substituted phenyl)-2,3,4,9-tetrahydro-1H-beta-carbolines have been synthesized and screened for their in vitro antimalarial activity against chloroquine-sensitive strains of Plasmodium falciparum. Compounds 26, 32, and 34 have shown MIC in the range of 0.05-0.11 microM and are in vitro several folds more active than chloroquine.     

Genetic engineering and accelerated plant improvement: Opportunities and challenges

Plant Cell, Tissue and Organ Culture (PCTOC) -     

Aeroallergens and pollinosis: Molecular and immunological characteristics of cloned pollen allergens

Affecting almost twenty percent of thepopulation in industrialized countries,allergic diseases such as asthma and seasonalrhinitis result from the development ofimmediate hypersensitivity to otherwiseinnocuous components of the environment. Pollen, the male gametophyte of flowering plantspecies, is one of the most predominant sourcesof environmental allergens, and a significantcause of allergic diseases. This reviewdiscusses the nature of pollen proteins asallergens, their effect on the human immunesystem and their mode of environmentaltransmission, including effects of theinteraction between pollen aeroallergens andair pollution. The influence of cross-reactivepollen allergens to the incidence of foodsensitivities is also discussed. Floweringplant species that possess allergenic pollen,identified with allergens cloned from thesespecies, are also discussed.     

Genetic variability and association of ISSR markers with some biochemical traits in mulberry (Morus spp.) genetic resources available in India

Utilizing intersimple sequence repeat (ISSR) markers, 18 mulberry (Morus spp.) germplasm collections were studied for genetic variability, phylogenetic relationship, and association with protein and sugar content. The genetic polymorphism exhibited by ISSR primers was 100%, and the genetic diversity recorded among the mulberry accessions had an average of 0.263 ± 0.094. Dendrogram (unweighted pair group method analysis) clustered the mulberry accessions into two major groups, one comprised the accessions collected from north or northeast regions of India, and the other comprised three subclusters and one isolate, i.e., Assamjati, a collection from Assam. Another subcluster contained accessions collected from Kerala, which belong to Morus indica. These accessions of M. indica from Kerala were found to be genetically diverse from north and northeast India. Multidimensional scaling of the ISSR data clearly separated the mulberry accessions according to their genetic diversity and protein content. Mulberry accessions were arbitrarily grouped into three classes viz. very low, moderate, and high in terms of protein and sugar content using standard statistical programs. Stepwise multiple regression analysis identified four ISSR markers (835_1,600, 835_5,600, 822_2,500, and 807_2,500) associated with protein content with highly positive correlation (p < 0.001) with linear curves with high F values (18.055 to 48.674; p < 0.001). In case of sugar content, four ISSR markers viz. 812₉₀₀, 817_1,500, 826_1,500, and 810_8,000 showed negative correlation. Hence, DNA markers for proteins seem promising and may be used in marker-assisted breeding program.     

Bag3-Induced Autophagy Is Associated with Degradation of JCV Oncoprotein, T-Ag

JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag), in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag) family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases.     

Distinctive Solvation Patterns Make Renal Osmolytes Diverse

The kidney uses mixtures of five osmolytes to counter the stress induced by high urea and NaCl concentrations. The individual roles of most of the osmolytes are unclear, and three of the five have not yet been thermodynamically characterized. Here, we report partial molar volumes and activity coefficients of glycerophosphocholine (GPC), taurine, and myo-inositol. We derive their solvation behavior from the experimental data using Kirkwood-Buff theory. We also provide their solubility data, including solubility data for scyllo-inositol. It turns out that renal osmolytes fall into three distinct classes with respect to their solvation. Trimethyl-amines (GPC and glycine-betaine) are characterized by strong hard-sphere-like self-exclusion; urea, taurine, and myo-inositol have a tendency toward self-association; sorbitol and most other nonrenal osmolytes have a relatively constant, intermediate solvation that has components of both exclusion and association. The data presented here show that renal osmolytes are quite diverse with respect to their solvation patterns, and they can be further differentiated based on observations from experiments examining their effect on macromolecules. It is expected, based on the available surface groups, that each renal osmolyte has distinct effects on various classes of biomolecules. This likely allows the kidney to use specific combinations of osmolytes independently to fine-tune the chemical activities of several types of molecules.