Role of NF-κB and p38 MAPK activation in mediating angiotensin II and endothelin-1-induced stimulation in leptin production and cardiomyocyte hypertrophy

We recently identified leptin as a downstream factor mediating the hypertrophic effects of both angiotensin II and endothelin-1 in cardiomyocytes, an effect dependent on increased leptin biosynthesis, however, the mechanism for such increased leptin production is not known. This study was designed to elucidate the mechanisms underlying angiotensin II- and endothelin-1-stimulated synthesis in cultured ventricular myocytes. The hypertrophic effects of both angiotensin II (100 nM) and endothelin-1 (10 nM) were associated with increased leptin secretion and gene expression by 40 and 50 %, and 86 and 68 %, respectively. These effects were associated with significantly increased nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) phosphorylation by 34 and 52 %, as well as enhanced translocation of NF-κB into nuclei and also the NF-κB-DNA binding activity by 35 and 31 % induced by angiotensin II and endothelin-1, respectively. On their own, 24 h treatment with either angiotensin II or endothelin-1 increased cell surface area by 30 and 40 %, protein synthesis by 30 % and the α-skeletal actin gene by 53 and 68 %, respectively, indicating a robust hypertrophic effect whereas this was completely prevented by NF-κB inhibition. In addition, NF-κB inhibition significantly attenuated angiotensin II and endothelin-1-induced p38 MAPK activation whereas inhibition of p38 MAPK blocked both angiotensin II- and endothelin-1-induced increases in leptin secretion. The ability of both angiotensin II- and endothelin-1 to increase leptin production in cardiomyocytes and the resultant hypertrophic response are mediated by NF-κB and dependent on p38 MAPK activation.     

Ovarian cancer: insights into genetics and pathogeny

Starting from the information on ovarian cancer provided by the mainstream publications, we construct a review focusing on the following issues: (i) the genetic profile, (ii) the role of the epithelial-mesenchymal transition in the acquirement of malignant features, (iii) the controversial hypothesis regarding the origin, and (iv) the involvement of the immune system in the tumoral microenvironment. Advances in the decipherment at the genetic level in the pathogenic mechanisms progressively lead to the idea of a genetic signature for the ovarian cancer. Moreover, the complementary approaches oriented towards the decryption of the intrinsic structure of the expressed molecules and, implicitly, the development of proteomics open new perspectives for an early diagnosis and an appropriate treatment. The research on the epithelial-mesenchymal transition (mainly those exploring the signaling pathways responsible for the switch between the loss of the epithelial characteristics and the gain of a mesenchymal cell phenotype, with results in the amplification of differentiation, motility and tumoral invasion) allow a deeper understanding of the complex pathogenic mechanism which governs ovarian carcinogenesis. The classic conception of ovarian cancer pathogeny, based on the role of the ovarian surface epithelium, is currently reconsidered, and a novel hypothesis is formulated, which supports direct involvement of the Fallopian tubes for the serous type. Although recent research suggests the implication of immune/inflammatory cells by specific mechanisms in ovarian cancer pathogenesis, there is yet reliable evidence concerning their modality of direct action and/or modulation of tumoral growth. Thus, ovarian carcinogenesis remains a research challenge, due to still numerous unknown factors involved in the malignant transformation sequences, originating from the genetic-molecular alterations and reflected by cellular and tissue expression patterns.     

Regeneration of plantlets from mature embryo calli of Western Ghats land race cultivar of rice, Oryza sativa L

The Malnad region located in the Western Ghats of Karnataka is known for the cultivation of indigenous rain fed land race cultivar of rice. The present study was to investigate the callogenic and caulogenic potentialities of the two indigenous rice cultivar namely Karimundaga and Kanadatumba using dehusked mature embryo explants. For callus and shoot bud differentiation, the explants were cultured on Murashige and Skoog (MS) medium supplemented with 2,4-D (1-3 mg/L), IAA (1-2 mg/L), Kn (1-4 mg/L) and BAP (1-4 mg/L). The morphogenic potentialities of the two rice cultivar differed in texture of callus. In both the cultivar callogenic frequency was optimized at 1 mg/L 2,4-D concentration, it was 94% in Karimundaga and 58% in Kanadatumba. Supplementation of IAA either alone (1-2 mg/L) or in combination with Kn or BAP at 1 to 4 mg/L concentration of each induces shoot bud differentiation from the calli. In the cultivar Karimundaga caulogenic frequency was highest (10.60 +/- 2.55) at 1.0 mg/L IAA and 4.0 mg/L BAP concentration. While in the cultivar Kanadatumba highest number of shoot buds (7.90 +/- 2.69) was differentiated at 1.0 mg/L IAA and 4.0 mg/L Kn concentration. The calli derived regenerants were successfully acclimatized in the greenhouse and agro-morphological variations were evaluated. The growth characteristics and yield related parameters exhibited by in vitro plants were lower than the in vivo plants.     

Tyrosine-phosphorylated galectin-3 protein is resistant to prostate-specific antigen (PSA) cleavage

Galectin-3 is a chimeric carbohydrate-binding protein, which interacts with cell surface carbohydrate-containing molecules and extracellular matrix glycoproteins and has been implicated in various biological processes such as cell growth, angiogenesis, motility, and metastasis. It is expressed in a wide range of tumor cells and is associated with tumor progression. The functions of galectin-3 are dependent on its localization and post-translational modifications such as cleavage and phosphorylation. Recently, we showed that galectin-3 Tyr-107 is phosphorylated by c-Abl; concomitantly, it was also shown that galectin-3 can be cleaved at this site by prostate-specific antigen (PSA), a chymotrypsin-like serine protease, after Tyr-107, resulting in loss of galectin-3 multivalency while preserving its carbohydrate binding activity. Galectin-3 is largely a monomer in solution but may form a homodimer by self-association through its carbohydrate recognition domain, whereas, in the presence of a ligand, galectin-3 polymerizes up to pentamers utilizing its N-terminal domain. Oligomerization is a unique feature of secreted galectin-3, which allows its function by forming ordered galectin-glycan structures, i.e. lattices, on the cell surface or through direct engagement of specific cell surface glycoconjugates by traditional ligand-receptor binding. We questioned whether Tyr-107 phosphorylation by c-Abl affects galectin-3 cleavage by PSA. The data suggest a role for galectin-3 in prostate cells associated with increased activity of c-Abl kinase and loss of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) activity. In addition, the ratio of phosphorylated/dephosphorylated galectin-3 might be used as a complementary value to that of PSA for prognosis of prostate cancer and a novel therapeutic target for the treatment of prostate cancer.     

Over-expression of OSRIP18 increases drought and salt tolerance in transgenic rice plants

Both drought and high salinity stresses are major abiotic factors that limit the yield of agricultural crops. Transgenic techniques have been regarded as effective ways to improve crops in their tolerance to these abiotic stresses. Functional characterization of genes is the prerequisite to identify candidates for such improvement. Here, we have investigated the biological functions of an Oryza sativa Ribosome-inactivating protein gene 18 (OSRIP18) by ectopically expressing this gene under the control of CaMV 35S promoter in the rice genome. We have generated 11 independent transgenic rice plants and all of them showed significantly increased tolerance to drought and high salinity stresses. Global gene expression changes by Microarray analysis showed that more than 100 probe sets were detected with up-regulated expression abundance while signals from only three probe sets were down-regulated after over-expression of OSRIP18. Most of them were not regulated by drought or high salinity stresses. Our data suggested that the increased tolerance to these abiotic stresses in transgenic plants might be due to up-regulation of some stress-dependent/independent genes and OSRIP18 may be potentially useful in further improving plant tolerance to various abiotic stresses by over-expression.     

Mechanistic insight into the microtubule and actin cytoskeleton coupling through dynein-dependent RhoGEF inhibition

Actin-based stress fiber formation is coupled to microtubule depolymerization through the local activation of RhoA. While the RhoGEF Lfc has been implicated in this cytoskeleton coupling process, it has remained elusive how Lfc is recruited to microtubules and how microtubule recruitment moderates Lfc activity. Here, we demonstrate that the dynein light chain protein Tctex-1 is required for localization of Lfc to microtubules. Lfc residues 139-161 interact with Tctex-1 at a site distinct from the cleft that binds dynein intermediate chain. An NMR-based GEF assay revealed that interaction with Tctex-1 represses Lfc nucleotide exchange activity in an indirect manner that requires both polymerized microtubules and phosphorylation of S885 by PKA. We show that inhibition of Lfc by Tctex-1 is dynein dependent. These studies demonstrate a pivotal role of Tctex-1 as a negative regulator of actin filament organization through its control of Lfc in the crosstalk between microtubule and actin cytoskeletons.     

Alleviation of gut inflammation by Cdx2/Pxr pathway in a mouse model of chemical colitis

Pregnane X Receptor (PXR), a master regulator of drug metabolism and inflammation, is abundantly expressed in the gastrointestinal tract. Baicalein and its O-glucuronide baicalin are potent anti-inflammatory and anti-cancer herbal flavonoids that undergo a complex cycle of interconversion in the liver and gut. We sought to investigate the role these flavonoids play in inhibiting gut inflammation by an axis involving PXR and other potential factors. The consequences of PXR regulation and activation by the herbal flavonoids, baicalein and baicalin were evaluated in vitro in human colon carcinoma cells and in vivo using wild-type, Pxr-null, and humanized (hPXR) PXR mice. Baicalein, but not its glucuronidated metabolite baicalin, activates PXR in a Cdx2-dependent manner in vitro, in human colon carcinoma LS174T cells, and in the murine colon in vivo. While both flavonoids abrogate dextran sodium sulfate (DSS)-mediated colon inflammation in vivo, oral delivery of a potent bacterial β-glucuronidase inhibitor eliminates baicalin's effect on gastrointestinal inflammation by preventing the microbial conversion of baicalin to baicalien. Finally, reduction of gastrointestinal inflammation requires the binding of Cdx2 to a specific proximal site on the PXR promoter. Pharmacological targeting of intestinal PXR using natural metabolically labile ligands could serve as effective and potent therapeutics for gut inflammation that avert systemic drug interactions.     

Enzyme characterization for hydrolysis of AFEX and liquid hot-water pretreated distillers' grains and their conversion to ethanol

Dried distillers' grains with solubles (DDGS), a co-product of corn ethanol production, was investigated as a feedstock for additional ethanol production. DDGS was pretreated with liquid hot-water (LHW) and ammonia fiber explosion (AFEX) processes. Cellulose was readily converted to glucose from both LHW and AFEX treated DDGS using a mixture of commercial cellulase and beta-glucosidase; however, these enzymes were ineffective at saccharifying the xylan present in the pretreated DDGS. Several commercial enzyme preparations were evaluated in combination with cellulase to saccharify pretreated DDGS xylan and it was found that adding commercial grade (e.g. impure) pectinase and feruloyl esterase (FAE) preparations were effective at releasing arabinose and xylose. The response of sugar yields for pretreated AFEX and LHW DDGS (6wt%/solids) were determined for different enzyme loadings of FAE and pectinase and modeled as a response surfaces. Arabinose and xylose yields rose with increasing FAE and pectinase enzyme dosages for both pretreated materials. When hydrolyzed at 20wt%/solids with the same blend of commercial enzymes, the yields were 278 and 261g sugars (i.e. total of arabinose, xylose, and glucose) per kg of DDGS (dry basis, db) for AFEX and LHW pretreated DDGS, respectively. The pretreated DDGS's were also evaluated for fermentation using Saccharomyces cerevisiae at 15wt%/solids. Pretreated DDGS were readily fermented and were converted to ethanol at 89-90% efficiency based upon total glucans; S. cerevisiae does not ferment arabinose or xylose.