Mammalian Target of Rapamycin (mTOR) and S6 Kinase Down-regulate Phospholipase D2 Basal Expression and Function

The mammalian target of rapamycin (mTOR) and S6 kinase (S6K) pathway is essential for cell differentiation, growth, and survival. Phospholipase D2 (PLD2) plays a key role in mTOR/S6K mitogenic signaling. However, the impact of PLD on mTOR/S6K gene expression is not known. Here we show that interleukin-8 (IL-8) increases mRNA expression levels for PLD2, mTOR, and S6K, with PLD2 preceding mTOR/S6K in time. Silencing of PLD2 gene expression abrogated IL-8-induced mTOR/S6K mRNA expression, whereas silencing of mTOR or S6K gene expression resulted in large (>3-fold and >5-fold, respectively) increased levels of PLD2 RNA, which was paralleled by increases in protein expression and lipase activity. Treatment of cells with 0.5 nm rapamycin induced a similar trend. These results suggest that, under basal conditions, PLD2 expression and concomitant activity is negatively regulated by the mTOR/S6K signaling pathway. Down-regulation of PLD2 was confirmed in differentiated HL-60 leukocytes overexpressing an mTOR-wild type, but not an mTOR kinase-dead construct. At the cellular level, overexpression of mTOR-wild type resulted in lower basal cell migration, which was reversed by treatment with IL-8. We propose that IL-8 reverses an mTOR/S6K-led down-regulation of PLD2 expression and enables PLD2 to fully function as a facilitator for cell migration.     

Structure based design of a series of potent and selective non peptidic PTP-1B inhibitors

A series of benzotriazole phenyldifluoromethylphosphonic acids were found to be potent PTP-1B inhibitors. Molecular modeling on the X-ray crystal structure of the lead structure led to the design of potent PTP-1B inhibitors that show moderate selectivity against TC-PTP, a very closely related protein tyrosine phosphatase.     

Phage display-derived antibody fragments against conserved regions of VacA toxin of Helicobacter pylori

Applied Microbiology and Biotechnology - Infection with Helicobacter pylori may result in the emergence of gastric adenocarcinoma. Among various toxins assisting pathogenesis of H. pylori,...     

Characterization of functionally important sites in the bacteriophage Mu transposase protein

The 663 amino acid Mu transposase protein is absolutely required for Mu DNA transposition. Mutant proteins were constructed in vitro in order to locate regions of transposase that may be important for the catalysis of DNA transposition. Deletions in the A gene, which encodes the transposase, yielded two stable mutant proteins that aid in defining the end-specific DNA-binding domain. Linker insertion mutagenesis at eight sites in the Mu A gene generated two proteins, FF6 and FF14 (resulting from two and four amino acid insertions, respectively, at position 408), which were thermolabile for DNA binding in vitro at 43°C. However, transposition activity in vivo was severely reduced for all mutant proteins at 37°C, except those with insertions at positions 328 and 624. In addition, site-specific mutagenesis was performed to alter tyrosine 414, which is situated in a region that displays amino acid homology to the active sites of a number of nicking/closing enzymes. Tyrosine 414 may reside within an important, yet non-essential, site of transposase, as an aspartate-substituted protein had a drastically reduced frequency of transposition, while the remaining mutants yielded reduced, but substantial, frequencies of Mu transposition in vivo.     

Screen of safflower (Carthamus tinctorius L.) genotypes against Phytophthora drechsleri and Fusarium solani,the causal agents of root rot disease

Safflower (Carthamus tinctorius L.) plants were affected by a severe root rot disease caused by Phytophthora drechsleri and Fusarium solani in Isfahan province of Iran during 2005–2007. Disease incidence was more than 30% in severely infected fields. Twenty-one safflower genotypes, including six local cultivars and 15 internal pure lines were evaluated for their resistance to root rot disease in laboratory and greenhouse conditions. Safflower seedlings were evaluated for lesion length on infected roots in laboratory, as well percentage of live seedlings in greenhouse. The results indicated a high negative correlation between lesion length on roots and percentage of live seedlings. The most resistant and susceptible genotypes to P. drechsleri were identified as pure line Karaj row 12 (KW12) and cultivar Koseh with lesion lengths of 10.01 and 15.51?mm on roots and 45.60 and 18.00% live seedlings, respectively. The most resistant genotype to F. solani was identified as pure line KW11 with a lesion length of 9.31?mm on roots as well 62.80% live seedlings. The most susceptible genotypes were identified as cultivar Koseh and pure lines KW2 and KW3 with lesion lengths of 13.29, 12.72 and 12.13?mm on roots and 25.60, 28.40 and 28.40% live seedlings, respectively. The most resistant genotypes to both P. drechsleri and F. solani were identified as pure lines KW15 and KW9 with a 55.40% live seedlings. The most susceptible genotypes were cultivars Koseh, Goldasht and pure lines KW6, KW3 and KW2 with 35.40, 35.40, 35.40, 37.60 and 37.60% live seedlings in greenhouse, respectively.     

Differentiation of human olfactory system-derived stem cells into dopaminergic neuron-like cells: A comparison between olfactory bulb and mucosa as two sources of stem cells

Cell transplantation has become a possible therapeutic approach in the treatment of neurodegenerative diseases of the nervous system by replacing lost cells. The current study aimed to make a comparison between the differentiation capacity of the olfactory bulb neural stem cells (OB-NSCs) and olfactory ectomesenchymal stem cells (OE-MSCs) into dopaminergic-like neurons under the inductive effect of transforming growth factor β (TGF-β). After culturing and treating with TGF-β, the differentiation capacities of both types of stem cells into dopaminergic neuron-like cells were evaluated. Quantitative real-time polymerase chain reaction analysis 3 weeks after induction demonstrated that the mRNA expression of the dopaminergic activity markers tyrosine hydroxylase (TH), dopamine transporter (DAT), paired box gene 2 (PAX2), and PAX5 in the neuron-like cells derived from OB-NSCs was significantly higher than those derived from OE-MSCs. These findings were further supported by the immunocytochemistry staining showing that the expression of the tyrosine hydroxylase, DAT, PAX2, and paired like homeodomain 3 seemed to be slightly higher in OB-NSCs compared with OE-MSCs. Despite the lower differentiation capacity of OE-MSCs, other considerations such as a noninvasive and easier harvesting process, faster proliferation attributes, longer life span, autologous transplantability, and also the easier and inexpensive cultural process of the OE-MSCs, cumulatively make these cells the more appropriate alternative in the case of autologous transplantation during the treatment process of neurodegenerative disorders like Parkinson's disease.     

Fusion between Hematopoietic and Epithelial Cells in Adult Human Intestine

Following transplantation of hematopoietic lineage cells, genetic markers unique to the transplanted cells have been detected in non-hematopoietic recipient cells of human liver, vascular endothelium, intestinal epithelium and brain. The underlying mechanisms by which this occurs are unclear. Evidence from mice suggests it is due in part to fusion between cells of hematopoietic and non-hematopoietic origins; however, direct evidence for this in humans is scant. Here, by quantitative and statistical analysis of X- and Y-chromosome numbers in epithelial and non-epithelial intestinal cells from gender-mismatched hematopoietic cell transplant patients, we provide evidence that transplanted cells of the hematopoietic lineage incorporate into human intestinal epithelium through cell fusion. This is the first definitive identification of cell fusion between hematopoietic cells and any epithelial cell type in humans, and provides the basis for further understanding the physiological and potential pathological consequences of cell fusion in humans.