bluuebunny/crossref_metadata_2025 huggingface dataset:
High-mobility group protein HMGB2 regulates human erythroid differentiation through trans-activation of GFI1B transcription
Authors: Laurent Benoît , Randrianarison-Huetz Voahangy , Maréchal Vincent , Mayeux Patrick , Dusanter-Fourt Isabella , Duménil Dominique
Published: November 2009

Gfi-1B is a transcriptional repressor that is crucial for erythroid differentiation: inactivation of the GFI1B gene in mice leads to embryonic death due to failure to produce differentiated red cells. Accordingly, GFI1B expression is tightly regulated during erythropoiesis, but the mechanisms involved in such regulation remain partially understood. We here identify HMGB2, a high-mobility group HMG protein, as a key regulator of GFI1B transcription. HMGB2 binds to the GFI1B promoter in vivo and up-regulates its trans-activation most likely by enhancing the binding of Oct-1 and, to a lesser extent, of GATA-1 and NF-Y to the GFI1B promoter. HMGB2 expression increases during erythroid differentiation concomitantly to the increase of GfI1B transcription. Importantly, knockdown of HMGB2 in immature hematopoietic progenitor cells leads to decreased Gfi-1B expression and impairs their erythroid differentiation. We propose that HMGB2 potentiates GATA-1–dependent transcription of GFI1B by Oct-1 and thereby controls erythroid differentiation.
KSHV-induced notch components render endothelial and mural cell characteristics and cell survival
Authors: Liu Ren , Li Xiuqing , Tulpule Anil , Zhou Yue , Scehnet Jeffrey S. , Zhang Shaobing , Lee Jong-Soo , Chaudhary Preet M. , Jung Jae , Gill Parkash S.
Published: November 2009

Kaposi sarcoma–associated herpesvirus (KSHV) infection is essential to the development of Kaposi sarcoma (KS). Notch signaling is also known to play a pivotal role in KS cell survival and lytic phase entrance of KSHV. In the current study, we sought to determine whether KSHV regulates Notch components. KSHV-infected lymphatic endothelial cells showed induction of receptors Notch3 and Notch4, Notch ligands Dll4 and Jagged1, and activated Notch receptors in contrast to uninfected lymphatic endothelial cells. In addition, KSHV induced the expression of endothelial precursor cell marker (CD133) and mural cell markers (calponin, desmin, and smooth muscle alpha actin), suggesting dedifferentiation and trans-differentiation. Overexpression of latency proteins (LANA, vFLIP) and lytic phase proteins (RTA, vGPCR, viral interleukin-6) further supported the direct regulatory capacity of KSHV viral proteins to induce Notch receptors (Notch2, Notch3), ligands (Dll1, Dll4, Jagged1), downstream targets (Hey, Hes), and endothelial precursor CD133. Targeting Notch pathway with γ-secretase inhibitor and a decoy protein in the form of soluble Dll4 inhibited growth of KSHV-transformed endothelial cell line. Soluble Dll4 was also highly active in vivo against KS tumor xenograft. It inhibited tumor cell growth, induced tumor cell death, and reduced vessel perfusion. Soluble Dll4 is thus a candidate for clinical investigation.
Rho GTPases in hematopoiesis and hemopathies
Authors: Mulloy James C. , Cancelas Jose A. , Filippi Marie-Dominique , Kalfa Theodosia A. , Guo Fukun , Zheng Yi
Published: November 2009

Rho family GTPases are intracellular signaling proteins regulating multiple pathways involved in cell actomyosin organization, adhesion, and proliferation. Our knowledge of their cellular functions comes mostly from previous biochemical studies that used mutant overexpression approaches in various clonal cell lines. Recent progress in understanding Rho GTPase functions in blood cell development and regulation by gene targeting of individual Rho GTPases in mice has allowed a genetic understanding of their physiologic roles in hematopoietic progenitors and mature lineages. In particular, mouse gene–targeting studies have provided convincing evidence that individual members of the Rho GTPase family are essential regulators of cell type–specific functions and stimuli-specific pathways in regulating hematopoietic stem cell interaction with bone marrow niche, erythropoiesis, and red blood cell actin dynamics, phagocyte migration and killing, and T- and B-cell maturation. In addition, deregulation of Rho GTPase family members has been associated with multiple human hematologic diseases such as neutrophil dysfunction, leukemia, and Fanconi anemia, raising the possibility that Rho GTPases and downstream signaling pathways are of therapeutic value. In this review we discuss recent genetic studies of Rho GTPases in hematopoiesis and several blood lineages and the implications of Rho GTPase signaling in hematologic malignancies, immune pathology. and anemia.
Expression of terminal α2-6–linked sialic acid on von Willebrand factor specifically enhances proteolysis by ADAMTS13
Authors: McGrath Rachel T. , McKinnon Thomas A. J. , Byrne Barry , O'Kennedy Richard , Terraube Virginie , McRae Emily , Preston Roger J. S. , Laffan Mike A. , O'Donnell James S.
Published: November 2009

von Willebrand factor (VWF) multimeric composition is regulated in plasma by ADAMTS13. VWF deglycosylation enhances proteolysis by ADAMTS13. In this study, the role of terminal sialic acid residues on VWF glycans in mediating proteolysis by ADAMTS13 was investigated. Quantification and distribution of VWF sialylation was examined by sequential digestion and high-performance liquid chromatography analysis. Total sialic acid expression on VWF was 167nmol/mg, of which the majority (80.1%) was present on N-linked glycan chains. Enzymatic desialylation of VWF by α2-3,6,8,9 neuraminidase (Neu-VWF) markedly impaired ADAMTS13-mediated VWF proteolysis. Neu-VWF collagen binding activity was reduced to 50% (± 14%) by ADAMTS13, compared with 11% (± 7%) for untreated VWF. Despite this, Neu-VWF exhibited increased susceptibility to other proteases, including trypsin, chymotrypsin, and cathepsin B. VWF expressing different blood groups exhibit altered ADAMTS13 proteolysis rates (O ≥ B > A ≥ AB). However, ABO blood group regulation of ADAMTS13 proteolysis was ablated on VWF desialylation, as both Neu-O-VWF and Neu-AB-VWF were cleaved by ADAMTS13 at identical rates. These novel data show that sialic acid protects VWF against proteolysis by serine and cysteine proteases but specifically enhances susceptibility to ADAMTS13 proteolysis. Quantitative variation in VWF sialylation therefore represents a key determinant of VWF multimeric composition and, as such, may be of pathophysiologic significance.
Attenuation by dextromethorphan on the higher liability to morphine-induced reward, caused by prenatal exposure of morphine in rat offspring
Authors: Wu Ling-Yi , Chen Jain-Fang , Tao Pao-Luh , Huang Eagle Yi-Kung
Published: November 2009

Co-administration of dextromethorphan (DM) with morphine during pregnancy and throughout lactation has been found to reduce morphine physical dependence and tolerance in rat offspring. No evidence was presented, however, for the effect of DM co-administered with morphine during pregnancy on morphine-induced reward and behavioral sensitization (possibly related to the potential to induce morphine addiction) in morphine-exposed offspring. Conditioned place preference and locomotor activity tests revealed that the p60 male offspring of chronic morphine-treated female rats were more vulnerable to morphine-induced reward and behavioral sensitization. The administration of a low dose of morphine (1 mg/kg, i.p.) in these male offspring also increased the dopamine and serotonin turnover rates in the nucleus accumbens, which implied that they were more sensitive to morphine. Co-administration of DM with morphine in the dams prevented this adverse effect of morphine in the offspring rats. Thus, DM may possibly have a great potential in the prevention of higher vulnerability to psychological dependence of morphine in the offspring of morphine-addicted mothers.
Colorectal cancer cell-derived microvesicles are enriched in cell cycle-related mRNAs that promote proliferation of endothelial cells
Authors: Hong Bok Sil , Cho Ji-Hoon , Kim Hyunjung , Choi Eun-Jeong , Rho Sangchul , Kim Jongmin , Kim Ji Hyun , Choi Dong-Sic , Kim Yoon-Keun , Hwang Daehee , Gho Yong Song
Published: November 2009

Background

Various cancer cells, including those of colorectal cancer (CRC), release microvesicles (exosomes) into surrounding tissues and peripheral circulation. These microvesicles can mediate communication between cells and affect various tumor-related processes in their target cells.

Results

We present potential roles of CRC cell-derived microvesicles in tumor progression via a global comparative microvesicular and cellular transcriptomic analysis of human SW480 CRC cells. We first identified 11,327 microvesicular mRNAs involved in tumorigenesis-related processes that reflect the physiology of donor CRC cells. We then found 241 mRNAs enriched in the microvesicles above donor cell levels, of which 27 were involved in cell cycle-related processes. Network analysis revealed that most of the cell cycle-related microvesicle-enriched mRNAs were associated with M-phase activities. The integration of two mRNA datasets showed that these M-phase-related mRNAs were differentially regulated across CRC patients, suggesting their potential roles in tumor progression. Finally, we experimentally verified the network-driven hypothesis by showing a significant increase in proliferation of endothelial cells treated with the microvesicles.

Conclusion

Our study demonstrates that CRC cell-derived microvesicles are enriched in cell cycle-related mRNAs that promote proliferation of endothelial cells, suggesting that microvesicles of cancer cells can be involved in tumor growth and metastasis by facilitating angiogenesis-related processes. This information will help elucidate the pathophysiological functions of tumor-derived microvesicles, and aid in the development of cancer diagnostics, including colorectal cancer.
Functional analysis of conserved aromatic amino acids in the discoidin domain of Paenibacillus β-1,3-glucanase
Authors: Cheng Yueh-Mei , Hsieh Feng-Chia , Meng Menghsiao
Published: November 2009

The 190-kDa Paenibacillus β-1,3-glucanase (LamA) contains a catalytic module of the glycoside hydrolase family 16 (GH16) and several auxiliary domains. Of these, a discoidin domain (DS domain), present in both eukaryotic and prokaryotic proteins with a wide variety of functions, exists at the carboxyl-terminus. To better understand the bacterial DS domain in terms of its structure and function, this domain alone was expressed in Escherichia coli and characterized. The results indicate that the DS domain binds various polysaccharides and enhances the biological activity of the GH16 module on composite substrates. We also investigated the importance of several conserved aromatic residues in the domain's stability and substrate-binding affinity. Both were affected by mutations of these residues; however, the effect on protein stability was more notable. In particular, the forces contributed by a sandwiched triad (W1688, R1756, and W1729) were critical for the presumable β-sandwich fold.
Hepcidin is elevated in mice injected with Mycoplasma arthritidis
Authors: Koening Curry L , Mu Hong-Hua , Van Schelt Adam , Lo Eric , Ward Diane M , Kaplan Jerry , De Domenico Ivana
Published: November 2009

Mycoplasma arthritidis causes arthritis in specific mouse strains. M. arthritidis mitogen (MAM), a superantigen produced by M. arthritidis, activates T cells by forming a complex between the major histocompatability complex II on antigen presenting cells and the T cell receptor on CD4+ T lymphocytes. The MAM superantigen is also known to interact with Toll-like receptors (TLR) 2 and 4. Hepcidin, an iron regulator protein, is upregulated by TLR4, IL-6, and IL-1. In this study, we evaluated serum hepcidin, transferrin saturation, ferritin, IL-6, IL-1, and hemoglobin levels in M. arthritidis injected C3H/HeJ (TLR2+/+, TLR4-/-) mice and C3H/HeSnJ (TLR2+/+, TLR4+/+) mice over a 21 day period. C3H/HeJ mice have a defective TLR4 and an inability to produce IL-6. We also measured arthritis severity in these mice and the amount of hepcidin transcripts produced by the liver and spleen. C3H/HeJ mice developed a more severe arthritis than that of C3H/HeSnJ mice. Both mice had an increase in serum hepcidin within three days after infection. Hepcidin levels were greater in C3H/HeJ mice despite a nonfunctioning TLR4 and low serum levels of IL-6. Splenic hepcidin production in C3H/HeJ mice was delayed compared to C3H/HeSnJ mice. Unlike C3H/HeSnJ mice, C3H/HeJ mice did not develop a significant rise in serum IL-6 levels but did develop a significant increase in IL-1β during the first ten days after injection. Both mice had an increase in serum ferritin but a decrease in serum transferrin saturation. In conclusion, serum hepcidin regulation in C3H/HeJ mice does not appear to be solely dependent upon TLR4 or IL-6.
Genetic diversity and phylogeography of Seewis virus in the Eurasian common shrew in Finland and Hungary
Authors: Kang Hae Ji , Arai Satoru , Hope Andrew G , Song Jin-Won , Cook Joseph A , Yanagihara Richard
Published: November 2009

Recent identification of a newfound hantavirus, designated Seewis virus (SWSV), in the Eurasian common shrew (Sorex araneus), captured in Switzerland, corroborates decades-old reports of hantaviral antigens in this shrew species from Russia. To ascertain the spatial or geographic variation of SWSV, archival liver tissues from 88 Eurasian common shrews, trapped in Finland in 1982 and in Hungary during 1997, 1999 and 2000, were analyzed for hantavirus RNAs by reverse transcription-polymerase chain reaction. SWSV RNAs were detected in 12 of 22 (54.5%) and 13 of 66 (19.7%) Eurasian common shrews from Finland and Hungary, respectively. Phylogenetic analyses of S- and L-segment sequences of SWSV strains, using maximum likelihood and Bayesian methods, revealed geographic-specific genetic variation, similar to the phylogeography of rodent-borne hantaviruses, suggesting long-standing hantavirus-host co-evolutionary adaptation.
A randomised controlled comparison of early post-pyloric versus early gastric feeding to meet nutritional targets in ventilated intensive care patients
Authors: White Hayden , Sosnowski Kellie , Tran Khoa , Reeves Annelli , Jones Mark
Published: November 2009

Introduction

To compare outcomes from early post-pyloric to gastric feeding in ventilated, critically ill patients in a medical intensive care unit (ICU).

Methods

Prospective randomized study. Ventilated patients were randomly assigned to receive enteral feed via a nasogastric or a post-pyloric tube. Post-pyloric tubes were inserted by the bedside nurse and placement was confirmed radiographically.

Results

A total of 104 patients were enrolled, 54 in the gastric group and 50 in the post-pyloric group. Bedside post-pyloric tube insertion was successful in 80% of patients. Patients who failed post-pyloric insertion were fed via the nasogastric route, but were analysed on an intent-to treat basis. A per protocol analysis was also performed. Baseline characteristics were similar for all except Acute Physiology and Chronic Health Evaluation II (APACHE II) score, which was higher in the post-pyloric group. There was no difference in length of stay or ventilator days. The gastric group was quicker to initiate feed 4.3 hours (2.9 - 6.5 hours) as compared to post-pyloric group 6.6 hours (4.5 - 13.0 hours) (P = 0.0002). The time to reach target feeds from admission was also faster in gastric group: 8.7 hours (7.6 - 13.0 hours) compared to 12.3 hours (8.9 - 17.5 hours). The average daily energy and protein deficit were lower in gastric group 73 Kcal (2 - 288 Kcal) and 3.5 g (0 - 15 g) compared to 167 Kcal (70 - 411 Kcal) and 6.5 g (2.8 - 17.3 g) respectively but was only statistically significant for the average energy deficit (P = 0.035). This difference disappeared in the per protocol analysis. Complication rates were similar.

Conclusions

Early post-pyloric feeding offers no advantage over early gastric feeding in terms of overall nutrition received and complications

Trial Registration

Clinical Trial: anzctr.org.au:ACTRN12606000367549
Expression of Ankyrin Repeat and Suppressor of Cytokine Signaling Box Protein 4 (Asb-4) in Proopiomelanocortin Neurons of the Arcuate Nucleus of Mice Produces a Hyperphagic, Lean Phenotype
Authors: Li Ji-Yao , Chai Biao-Xin , Zhang Weizhen , Wang Hui , Mulholland Michael W.
Published: November 2009

Ankyrin repeat and suppressor of cytokine signaling box-containing protein 4 (Asb-4) is specifically expressed in the energy homeostasis-related brain areas and colocalizes with proopiomelanocortin (POMC) neurons of the arcuate nucleus (ARC). Injection of insulin into the third ventricle of the rat brain increased Asb-4 mRNA expression in the paraventricular nucleus but not in the ARC of the hypothalamus, whereas injection of leptin (ip) increased Asb-4 expression in both mouse paraventricular nucleus and ARC. A transgenic mouse in which Myc-tagged Asb-4 is specifically expressed in POMC neurons of the ARC was made and used to study the effects of Asb-4 on ingestive behavior and metabolic rate. Animals with overexpression of Asb-4 in POMC neurons demonstrated an increase in food intake. However, POMC-Asb-4 transgenic animals gained significantly less weight from 6–30 wk of age. The POMC-Asb-4 mice had reduced fat mass and increased lean mass and lower levels of blood leptin. The transgenic animals were resistant to high-fat diet-induced obesity. Transgenic mice had significantly higher rates of oxygen consumption and carbon dioxide production than wild-type mice during both light and dark periods. The locomotive activity of transgenic mice was increased. The overexpression of Asb-4 in POMC neurons increased POMC mRNA expression in the ARC. The transgenic animals had no observed effect on peripheral glucose metabolism and the activity of the autonomic nervous system. These results indicate that Asb-4 is a key regulatory protein in the central nervous system, involved in the control of feeding behavior and metabolic rate.
Functional Effects of Polymorphisms in the Human Gene Encoding 11β-Hydroxysteroid Dehydrogenase Type 1 (11β-HSD1): A Sequence Variant at the Translation Start of 11β-HSD1 Alters Enzyme Levels
Authors: Malavasi Elise L. V. , Kelly Val , Nath Nikita , Gambineri Alessandra , Dakin Rachel S. , Pagotto Uberto , Pasquali Renato , Walker Brian R. , Chapman Karen E.
Published: November 2009

Regeneration of active glucocorticoids within liver and adipose tissue by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) may be of pathophysiological importance in obesity and metabolic syndrome and is a therapeutic target in type 2 diabetes. Polymorphisms in HSD11B1, the gene encoding 11β-HSD1, have been associated with metabolic phenotype in humans, including type 2 diabetes and hypertension. Here, we have tested the functional consequences of two single nucleotide polymorphisms located in contexts that potentially affect tissue levels of 11β-HSD1. We report no effect of allelic variation at rs846910, a polymorphism within the 5′-flanking region of the gene on HSD11B1 promoter activity in vitro. However, compared with the common G allele, the A allele of rs13306421, a polymorphism located two nucleotides 5′ to the translation initiation site, gave higher 11β-HSD1 expression and activity in vitro and was translated at higher levels in in vitro translation reactions, possibly associated with a lower frequency of “leaky scanning.” These data suggest that this polymorphism may have direct functional consequences on levels of 11β-HSD1 enzyme activity in vivo. However, the rs13306421 A sequence variant originally reported in other ethnic groups may be of low prevalence because it was not detected in a population of 600 European Caucasian women.
Molecular Mechanism of the Inhibition of Estradiol-Induced Endometrial Epithelial Cell Proliferation by Clomiphene Citrate
Authors: Amita Mitsuyoshi , Takahashi Toshifumi , Tsutsumi Seiji , Ohta Tsuyoshi , Takata Keiko , Henmi Noriko , Hara Shuichiro , Igarashi Hideki , Takahashi Kazuhiro , Kurachi Hirohisa
Published: November 2009

We examined the molecular mechanisms of the antiestrogenic effects of clomiphene citrate (CC) in the endometrium using two types of cell lines, Ishikawa and EM-E6/E7/hTERT cells. CC or ICI182780 inhibited 17β-estradiol (E2)-induced endometrial cell proliferation and transcriptional activation of the estrogen response element (ERE) gene. We directly visualized the ligand-estrogen receptor (ER)α interaction using green fluorescent protein (GFP)-tagged ERα in a single living cell. Whereas E2 changed the nuclear localization of GFP-ERα to a punctate distribution within 5 min, CC or ICI182780 changed the slower and less mobilization of GFP-ERα compared with E2. Pretreatment with CC or ICI182780 partly prevented the E2-induced nuclear redistribution of GFP-ERα. Fluorescence recovery after photobleaching revealed that GFP-ERα mobility treated with E2 was more rapid than that treated by CC or ICI182780. As coactivator recruitment to the ER is essential for ER-dependent transcription, we examined the interaction between ERα and steroid receptor coactivator-1 (SRC-1). The complex formation between ERα and SRC-1 was significantly increased by E2 but was prevented in the presence of CC or ICI182780 by coimmunoprecipitation. Moreover, the E2-induced colocalization of GFP-ERα and SRC-1 was prevented in the presence of CC or ICI182780 according to an immunofluorescence assay. We also observed that the reduction of SRC-1 using small interfering RNA for SRC-1 resulted in the inhibition of E2-induced cell proliferation and transcriptional activation of the ERE gene. Collectively, these results suggest that CC may inhibit E2-induced endometrial epithelial cell proliferation and ERE transactivation by inhibiting the recruitment of SRC-1 to ERα.
Senescence Marker Protein-30/Gluconolactonase Deletion Worsens Glucose Tolerance through Impairment of Acute Insulin Secretion
Authors: Hasegawa Goji , Yamasaki Masahiro , Kadono Mayuko , Tanaka Muhei , Asano Mai , Senmaru Takafumi , Kondo Yoshitaka , Fukui Michiaki , Obayashi Hiroshi , Maruyama Naoki , Nakamura Naoto , Ishigami Akihito
Published: November 2009

Senescence marker protein-30 (SMP30) is an androgen-independent factor that decreases with age. We recently identified SMP30 as the lactone-hydrolyzing enzyme gluconolactonase (GNL), which is involved in vitamin C biosynthesis in animal species. To examine whether the age-related decrease in SMP30/GNL has effects on glucose homeostasis, we used SMP30/GNL knockout (KO) mice treated with l-ascorbic acid. In an ip glucose tolerance test at 15 wk of age, blood glucose levels in SMP30/GNL KO mice were significantly increased by 25% at 30 min after glucose administration compared with wild-type (WT) mice. Insulin levels in SMP30/GNL KO mice were significantly decreased by 37% at 30 min after glucose compared with WT mice. Interestingly, an insulin tolerance test showed a greater glucose-lowering effect in SMP30/GNL KO mice. High-fat diet feeding severely worsened glucose tolerance in both WT and SMP30/GNL KO mice. Morphometric analysis revealed no differences in the degree of high-fat diet-induced compensatory increase in β-cell mass and proliferation. In the static incubation study of islets, insulin secretion in response to 20 mm glucose or KCl was significantly decreased in SMP30/GNL KO mice. On the other hand, islet ATP content at 20 mm in SMP30/GNL KO mice was similar to that in WT mice. Collectively, these data indicate that impairment of the early phase of insulin secretion due to dysfunction of the distal portion of the secretion pathway underlies glucose intolerance in SMP30/GNL KO mice. Decreased SMP30/GNL may contribute to the worsening of glucose tolerance that occurs in normal aging.
Naturally Occurring Glucokinase Mutations Are Associated with Defects in Posttranslational S-Nitrosylation
Authors: Ding Shi-Ying , Tribble Nicholas D. , Kraft Catherine A. , Markwardt Michele , Gloyn Anna L. , Rizzo Mark A.
Published: November 2009

Posttranslational activation of glucokinase (GCK) through S-nitrosylation has been recently observed in the insulin-secreting pancreatic β-cell; however, the function of this molecular mechanism in regulating the physiology of insulin secretion is not well understood. To more fully understand the function of posttranslational regulation of GCK, we examined two naturally occurring GCK mutations that map to residues proximal to the S-nitrosylated cysteine and cause mild fasting hyperglycemia (maturity-onset diabetes of the young; subtype glucokinase). The kinetics of recombinantly generated GCK-R369P and GCK-V367M were assessed in vitro. The GCK-R369P protein has greatly reduced catalytic activity (relative activity index 0.05 vs. 1.00 for wild type), whereas the GCK-V367M has near normal kinetics (relative activity index 1.26 vs. 1.00 for wild type). Quantitative imaging and biochemical assays were used to assess the effect of these mutants on the metabolic response to glucose, GCK activation, and S-nitrosylation of GCK in βTC3 insulinoma cells. Expression of either mutant in βTC3 cells did not affect the metabolic response to 5 mm glucose. However, expression of either mutant blocked the effects of insulin on glucose-stimulated nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate reduction, suggesting defects in posttranslational regulation of GCK. Each of these mutations blocked GCK activation, and prevented posttranslational cysteine S-nitrosylation. Our findings link defects in hormone-regulated GCK S-nitrosylation to hyperglycemia and support a role for posttranslational regulation of GCK S-nitrosylation as a vital regulatory mechanism for glucose-stimulated insulin secretion.
Toll-dependent antimicrobial responses inDrosophilalarval fat body require Spätzle secreted by haemocytes
Authors: Shia Alice K. H. , Glittenberg Marcus , Thompson Gavin , Weber Alexander N. , Reichhart Jean-Marc , Ligoxygakis Petros
Published: November 2009

In Drosophila, the humoral response characterised by the synthesis of antimicrobial peptides (AMPs) in the fat body (the equivalent of the mammalian liver) and the cellular response mediated by haemocytes (blood cells) engaged in phagocytosis represent two major reactions that counter pathogens. Although considerable analysis has permitted the elucidation of mechanisms pertaining to the two responses individually, the mechanism of their coordination has been unclear. To characterise the signals with which infection might be communicated between blood cells and fat body, we ablated circulating haemocytes and defined the parameters of AMP gene activation in larvae. We found that targeted ablation of blood cells influenced the levels of AMP gene expression in the fat body following both septic injury and oral infection. Expression of the AMP gene drosomycin (a Toll target) was blocked when expression of the Toll ligand Spätzle was knocked down in haemocytes. These results show that in larvae, integration of the two responses in a systemic reaction depend on the production of a cytokine (spz), a process that strongly parallels the mammalian immune response.
MT1-MMP- and Cdc42-dependent signaling co-regulate cell invasion and tunnel formation in 3D collagen matrices
Authors: Fisher Kevin E. , Sacharidou Anastasia , Stratman Amber N. , Mayo Anne M. , Fisher Sarah B. , Mahan Rachel D. , Davis Michael J. , Davis George E.
Published: November 2009

Complex signaling events control tumor invasion in three-dimensional (3D) extracellular matrices. Recent evidence suggests that cells utilize both matrix metalloproteinase (MMP)-dependent and MMP-independent means to traverse 3D matrices. Herein, we demonstrate that lysophosphatidic-acid-induced HT1080 cell invasion requires membrane-type-1 (MT1)-MMP-mediated collagenolysis to generate matrix conduits the width of a cellular nucleus. We define these spaces as single-cell invasion tunnels (SCITs). Once established, cells can migrate within SCITs in an MMP-independent manner. Endothelial cells, smooth muscle cells and fibroblasts also generate SCITs during invasive events, suggesting that SCIT formation represents a fundamental mechanism of cellular motility within 3D matrices. Coordinated cellular signaling events are required during SCIT formation. MT1-MMP, Cdc42 and its associated downstream effectors such as MRCK (myotonic dystrophy kinase-related Cdc42-binding kinase) and Pak4 (p21 protein-activated kinase 4), protein kinase Cα and the Rho-associated coiled-coil-containing protein kinases (ROCK-1 and ROCK-2) coordinate signaling necessary for SCIT formation. Finally, we show that MT1-MMP and Cdc42 are fundamental components of a co-associated invasion-signaling complex that controls directed single-cell invasion of 3D collagen matrices.
The Rho-family GEF Asef2 activates Rac to modulate adhesion and actin dynamics and thereby regulate cell migration
Authors: Bristow Jeanne M. , Sellers Meredith H. , Majumdar Devi , Anderson Bridget , Hu Lan , Webb Donna J.
Published: November 2009

Asef2 is a recently identified Rho-family guanine nucleotide exchange factor (GEF) that has been implicated in the modulation of actin, but its function in cell migration and adhesion dynamics is not well understood. In this study, we show that Asef2 is an important regulator of cell migration and adhesion assembly and disassembly (turnover). Asef2 localizes with actin at the leading edge of cells. Knockdown of endogenous Asef2 impairs migration and significantly slows the turnover of adhesions. Asef2 enhances both Rac1 and Cdc42 activity in HT1080 cells, but only Rac1 is crucial for the Asef2-promoted increase in migration and adhesion turnover. Phosphoinositide 3-kinase (PI3K) and the serine/threonine kinase Akt are also essential for the Asef2-mediated effects on migration and adhesion turnover. Consistent with this, Asef2 increases the amount of active Akt at the leading edge of cells. Asef2 signaling leads to an overall decrease in Rho activity, which is crucial for stimulating migration and adhesion dynamics. Thus, our results reveal an important new role for Asef2 in promoting cell migration and rapid adhesion turnover by coordinately regulating the activities of Rho-family GTPases.
Symmetric and asymmetric mitotic segregation patterns influence Wolbachia distribution in host somatic tissue
Authors: Albertson Roger , Casper-Lindley Catharina , Cao Jian , Tram Uyen , Sullivan William
Published: November 2009

Wolbachia are maternally inherited bacterial endosymbionts that occupy many but not all tissues of adult insects. During the initial mitotic divisions in Drosophila embryogenesis, Wolbachia exhibit a symmetric pattern of segregation. Wolbachia undergo microtubule-dependent and cell-cycle-regulated movement between centrosomes. Symmetric segregation occurs during late anaphase when Wolbachia cluster around duplicated and separating centrosomes. This centrosome association is microtubule-dependent and promotes an even Wolbachia distribution throughout the host embryo. By contrast, during the later embryonic and larval neuroblast divisions, Wolbachia segregate asymmetrically with the apical self-renewing neuroblast. During these polarized asymmetric neuroblast divisions, Wolbachia colocalize with the apical centrosome and apically localized Par complex. This localization depends on microtubules, but not the cortical actin-based cytoskeleton. We also found that Wolbachia concentrate in specific regions of the adult brain, which might be a direct consequence of the asymmetric Wolbachia segregation in the earlier neuroblast divisions. Finally, we demonstrate that the fidelity of asymmetric segregation to the self-renewing neuroblast is lower in the virulent Popcorn strain of Wolbachia.
CaMKIIα interacts with multi-PDZ domain protein MUPP1 in spermatozoa and prevents spontaneous acrosomal exocytosis
Authors: Ackermann Frauke , Zitranski Nele , Borth Heike , Buech Thomas , Gudermann Thomas , Boekhoff Ingrid
Published: November 2009

The success of acrosomal exocytosis, a complex process with a variety of inter-related steps, relies on the coordinated interaction of participating signaling molecules. Since the acrosome reaction resembles Ca2+-regulated exocytosis in neurons, we investigated whether cognate neuronal binding partners of the multi-PDZ domain protein MUPP1, which recruits molecules that control the initial tethering and/or docking between the acrosomal vesicle and the plasma membrane, are also expressed in spermatozoa, and whether they contribute to the regulation of acrosomal secretion. We observed that CaMKIIα colocalizes with MUPP1 in the acrosomal region of epididymal spermatozoa where the kinase selectively binds to a region encompassing PDZ domains 10-11 of MUPP1. Furthermore, we found that pre-treating mouse spermatozoa with a CaMKII inhibitor that directly blocks the catalytic region of the kinase, as well as a competitive displacement of CaMKIIα from PDZ domains 10-11, led to a significant increase in spontaneous acrosomal exocytosis. Since Ca2+-calmodulin releases CaMKIIα from the PDZ scaffolding protein, MUPP1 represents a central signaling platform to dynamically regulate the assembly and disassembly of binding partners pertinent to acrosomal secretion, thereby precisely adjusting an increase in Ca2+ to synchronized fusion pore formation.
Elastic energy storage in the mantis shrimp's fast predatory strike
Authors: Zack T. I. , Claverie T. , Patek S. N.
Published: November 2009

Storage of elastic energy is key to increasing the power output of many biological systems. Mantis shrimp (Stomatopoda) must store considerable elastic energy prior to their rapid raptorial strikes; however, little is known about the dynamics and location of elastic energy storage structures in this system. We used computed tomography (CT) to visualize the mineralization patterns in Gonodactylaceus falcatus and high speed videography of Odontodactylus scyllarus to observe the dynamics of spring loading. Using a materials testing apparatus, we measured the force and work required to contract the elastic structures in G. falcatus. There was a positive linear correlation between contraction force and contraction distance; alternative model tests further supported the use of a linear model. Therefore, we modeled the system as a Hookean spring. The force required to fully compress the spring was positively correlated with body mass and appendage size, but the spring constant did not scale with body size, suggesting a possible role of muscle constraints in the scaling of this system. One hypothesized elastic storage structure, the saddle, only contributed approximately 11% of the total measured force, thus suggesting that primary site of elastic energy storage is in the mineralized ventral bars found in the merus segment of the raptorial appendages. Furthermore, the intact system exhibited 81% resilience and severing the saddle resulted in a non-significant reduction to 77% resilience. The remarkable shapes and mineralization patterns that characterize the mantis shrimp's raptorial appendage further reveal a highly integrated mechanical power amplification system based on exoskeletal elastic energy storage.
The peptide hormone pQDLDHVFLRFamide (crustacean myosuppressin) modulates theHomarus americanuscardiac neuromuscular system at multiple sites
Authors: Stevens J. S. , Cashman C. R. , Smith C. M. , Beale K. M. , Towle D. W. , Christie A. E. , Dickinson P. S.
Published: November 2009

pQDLDHVFLRFamide is a highly conserved crustacean neuropeptide with a structure that places it within the myosuppressin subfamily of the FMRFamide-like peptides. Despite its apparent ubiquitous conservation in decapod crustaceans, the paracrine and/or endocrine roles played by pQDLDHVFLRFamide remain largely unknown. We have examined the actions of this peptide on the cardiac neuromuscular system of the American lobster Homarus americanus using four preparations: the intact animal, the heart in vitro, the isolated cardiac ganglion (CG), and a stimulated heart muscle preparation. In the intact animal, injection of myosuppressin caused a decrease in heartbeat frequency. Perfusion of the in vitro heart with pQDLDHVFLRFamide elicited a decrease in the frequency and an increase in the amplitude of heart contractions. In the isolated CG, myosuppressin induced a hyperpolarization of the resting membrane potential of cardiac motor neurons and a decrease in the cycle frequency of their bursting. In the stimulated heart muscle preparation, pQDLDHVFLRFamide increased the amplitude of the induced contractions, suggesting that myosuppressin modulates not only the CG, but also peripheral sites. For at least the in vitro heart and the isolated CG, the effects of myosuppressin were dose-dependent (10−9 to 10−6 mol l−1 tested), with threshold concentrations (10−8−10−7 mol l−1) consistent with the peptide serving as a circulating hormone. Although cycle frequency, a parameter directly determined by the CG, consistently decreased when pQDLDHVFLRFamide was applied to all preparation types, the magnitudes of this decrease differed, suggesting the possibility that, because myosuppressin modulates the CG and the periphery, it also alters peripheral feedback to the CG.
Electromechanical coupled non-linear vibration of the microplate
Authors: Xu L , Sun L
Published: November 2009

In this article, the non-linear electromechanical coupled dynamic equation of the micro-plate subjected to an electrostatic force is presented. The non-linear free vibration of the electromechanical coupled micro-plate system and the non-linear forced response of the system to voltage excitation are investigated. Non-linear vibration frequencies of the micro-plate for every mode are calculated and compared with the linear natural frequencies. Changes in the non-linear frequencies with the system parameters are presented. The non-linear vibration displacements of the micro-plate at some typical cross-section are calculated for the first three modes. Effects of the system parameters on the displacements are analysed. The changes in the vibration amplitudes with respect to the exciting frequency under different modes and parameters are investigated. Moreover, the effects of the boundary conditions on the electromechanical coupled micro-plate system are also investigated.
Using a homogeneous beam element to analyse functionally graded beams
Authors: Taeprasartsit S
Published: November 2009

When an appropriate reference plane is used, the coupling between axial and bending deformations in the stiffness matrix of a functionally graded beam (FGB) element vanishes. Then the stiffness matrix of the FGB element reduces to the same form as that of the homogeneous beam element. However, the coupling in the mass matrix of the FGB element cannot be eliminated at the same time. Consequently, in an analysis that does not involve mass, it is possible to use a homogeneous beam element to obtain the same results as would be achieved with an FGB element. This paper focuses on explaining a procedure to use ANSYS's BEAM3 element to analyse FGBs. The BEAM3 element has the ability to deal with a linear temperature gradient that is sufficient to analyse any arbitrary temperature distribution shape through thickness.
Active-set sequential quadratic programming with variable probabilistic constraint evaluations for optimization problems under non-Gaussian uncertainties
Authors: Chan K-Y , Huang Y-C
Published: November 2009

Design optimization under random uncertainties are formulated as problems with probabilistic constraints. Calculating these constraints presents a major challenge in the optimization. While most research concentrates on uncertainties that are Gaussian, a great number of uncertainties in the environment are non-Gaussian. In this work, various reliability analyses for non-Gaussian uncertainties within a sequential quadratic programming framework are integrated. An analytical reliability contour (RC) is first constructed in the design space to indicate the minimal distance from the feasible boundary of a design at a desired reliability level. A safe zone contour is then created so as to provide a quick estimate of the RC. At each design iteration reliability analyses of different accuracies are selected based on the level needed, depending on the activity of a constraint. For problems with a large number of constraints and relatively few design variables, such as structural problems, the active set strategies significantly improve efficiency, as demonstrated in the examples.
Applying improved multi-scale entropy and support vector machines for bearing health condition identification
Authors: Zhang L , Xiong G , Liu H , Zou H , Guo W
Published: November 2009

Considering the non-linearity existing in bearing vibration signals as well as the scarcity of fault samples, this paper presents a method for bearing health condition identification based on improved multi-scale entropy (IMSE) and support vector machines (SVMs). IMSE refers to the calculation of improved sample entropies (i.e. fuzzy sample entropies across a sequence of scales). Applying IMSE to mechanical vibration signals can take into account not only the non-linearity but also the interactions and coupling between mechanical components, thus providing much more information regarding the machine health condition than traditional single-scale entropy can be expected to. In engineering practice, the amount of fault samples is often limited for training a classifier, which thus decreases the performance of traditional classifiers like artificial neural networks (ANNs). SVMs are derived from statistical learning theory, which is different from the conventional statistical theory on which ANNs are based. SVMs provide a favourable solution to small sample-sized problems. In this study, IMSE and SVMs are employed as fault feature extractor and classifier, respectively. The experimental results verify that the proposed method has potential applications in bearing health condition identification.
A new approach for an analytical solution of unsteady laminar flow in dispensing processes
Authors: Nguyen Q H , Choi S B
Published: November 2009

In this study, a new method to analytically model unsteady laminar flows of both Newtonian fluid and power-laws fluid is developed. The proposed approach is based on the assumption that the pressure drop of the unsteady flow results from the pressure drop due to inertia and the pressure drop due to fluid viscosity, separately. After an overview of dispensing technology and historical modelling methods of the unsteady flows, a new modelling approach of the unsteady laminar flow is developed for the flow in a circular pipe and the axial Couette flow in an annular duct. Using the proposed model, simulation results of the unsteady flow in an arbitrary circular pipe and the annular duct are obtained and compared with other approach solutions. In addition, a comparative work between the proposed analytical dynamic model and the finite-element model is undertaken in order to demonstrate the effectiveness of the proposed modelling methodology.
An inertial piezoelectric rotary motor
Authors: Xu L , Xing J
Published: November 2009

In this study, a novel inertial piezoelectric rotary motor is proposed and its operating principle is introduced. The dynamics model of the motor is presented. From the model, the equations of the natural frequency and mode function of the motor are obtained. Using these equations, the natural frequency and mode function of the motor are investigated and chosen. A model machine of the motor is made and the operating test of the motor is done. The test results illustrate the working principle of the motor and analytical calculations. The motor structure is quite simple and is favourable to further miniaturize the piezoelectric rotational motor.
Stress concentration factors in compression—fit couplings
Authors: Croccolo D , Vincenzi N
Published: November 2009

The aim of the present work is to define the maximum stress generated by the coupling of axially symmetric and continuous shafts press-fitted into axially symmetric hubs. The theoretical stresses given by the well-known formulae of the thick-walled cylinders theory are constant on the whole coupling surface, but if the shaft extends beyond the hub there is a stress concentration factor on the boundary zone. This occurrence is confirmed by finite element analyses performed by the authors on several different shaft—hub couplings. The analysed couplings have the shaft extended beyond the hub, the shafts press-fitted into the hubs, and both shafts and hubs loaded by an external pressure and an internal pressure. The stress concentration factors have been calculated in this work and their expressions have been derived as a function of some tensile and geometrical parameters. By combining the thick-walled cylinders theory with the proposed formulae, it is possible to evaluate the maximum stress located at the end of the hub without performing any numerical investigations.
Dimensional synthesis of a five-point double-toggle mould clamping mechanism using a genetic algorithm—differential evolution hybrid algorithm
Authors: Lin W Y , Wang S S
Published: November 2009

A hybrid evolutionary algorithm by combining real-valued genetic algorithm (RGA) with differential evolution (DE) has been proposed by the first author. This is termed the ‘GA—DE hybrid algorithm’. The only difference between the GA—DE hybrid algorithm and the RGA is in the content of the crossover. The crossover operation in the RGA is replaced by differential vector perturbation, with the best individual or some excellent individuals as the base vectors. In this work, the GA—DE hybrid evolutionary algorithm and the RGA with arithmetic crossover are employed to solve the optimization problem of the dimensional synthesis of the five-point double-toggle mould clamping mechanism with the performance of thrust saving for the prescribed input and output strokes. The optimization design task is relatively unique, because the number of constraints is considerable and the constraints are uneven. A technique for proper handling of design constraints is presented. The synthesized results are estimated using the solutions obtained by the parametric study based on an exhaustive search. Findings show that the GA—DE hybrid algorithm can successfully find a better objective function value more efficiently than the RGA with arithmetic crossover.
Poly(A)-binding protein modulates mRNA susceptibility to cap-dependent miRNA-mediated repression
Authors: Walters Robert W. , Bradrick Shelton S. , Gromeier Matthias
Published: November 2009

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally through binding specific sites within the 3′ untranslated regions (UTRs) of their target mRNAs. Numerous investigations have documented repressive effects of miRNAs and identified factors required for their activity. However, the precise mechanisms by which miRNAs modulate gene expression are still obscure. Here, we have examined the effects of multiple miRNAs on diverse target transcripts containing artificial or naturally occurring 3′ UTRs in human cell culture. In agreement with previous studies, we report that both the 5′ m7G cap and 3′ poly(A) tail are essential for maximum miRNA repression. These cis-acting elements also conferred miRNA susceptibility to target mRNAs translating under the control of viral- and eukaryotic mRNA-derived 5′ UTR structures that enable cap-independent translation. Additionally, we evaluated a role for the poly(A)-binding protein (PABP) in miRNA function utilizing multiple approaches to modulate levels of active PABP in cells. PABP expression and activity inversely correlated with the strength of miRNA silencing, in part due to antagonism of target mRNA deadenylation. Together, these findings further define the cis- and trans-acting factors that modulate miRNA efficacy.