bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on anomalous n-type conduction of P-doped ZnO using P2O5 dopant source
Authors: Yu Zhi Gen , Gong Hao , Wu Ping
Published: May 2005

The unexpected n-type conduction observed in P-doped ZnO thin films fabricated from rf magnetron sputtering, was studied systematically through a combined approach of experiment and computer modeling. The carrier stability was predicted from first-principles density functional theory and chemical thermodynamic calculations. It demonstrated that, under oxygen-poor growth condition and low temperature, the stable doping defect PO−1 may have negative effect on n-type conduction and, under oxygen-poor growth condition and high temperature, the stable doping defect may contribute significantly to the n-type conduction. Furthermore, under oxygen-rich growth condition, the stable doping defect PZn1 may help to maintain the n-type conduction at high oxygen partial pressures. Our model predictions are in good agreement with experimental observations in anomalous conduction of P2O5-doped ZnO thin films and provide scientific explanation. This research not only revealed increased fundamental understanding on electronic behaviors but also provided a fabrication strategy for P-doped n-type ZnO.
Domain structure control of (001)∕(100)-oriented epitaxial Pb(Zr,Ti)O3 films grown on (100)cSrRuO3∕(100)SrTiO3 substrates
Authors: Kim Yong Kwan , Morioka Hitoshi , Ueno Risako , Yokoyama Shintaro , Funakubo Hiroshi
Published: May 2005

The domain structure and electrical properties were systematically investigated in (001)∕(100)-oriented tetragonal epitaxial Pb(Zr0.35,Ti0.65)O3 thin films grown on (100)cSrRuO3∕(100)SrTiO3 substrates by metalorganic chemical vapor deposition. The wide range of domain structures with various volume fractions of c-domains from 0.05 to 1.0 was systematically controlled by changing the growth temperature from 380to540°C and the film thickness from 50to380nm, while keeping the other processing conditions the same. Reducing the deposition temperature and∕or increasing the film thickness reduced the population of c-domains. The relative dielectric constant (≈500) of the a-domain dominant films (volume fraction of c-axis-oriented domains, VC≈0.05) was larger than that (≈300) of the c-domain dominant ones (VC≈1.0). In the c-domain dominant region, the saturation and remanent polarization changed linearly with the volume fraction of c-domains. In the a-domain dominant region, they showed extraordinary large values, suggesting that a-domain switching makes a large contribution in this region.
Singlet-singlet and singlet-heat annihilations in fluorescence-based organic light-emitting diodes under steady-state high current density
Authors: Nakanotani Hajime , Sasabe Hiroyuki , Adachi Chihaya
Published: May 2005

We observed a significant decrease in electroluminescence (EL) in the high-current-density region (J>1A∕cm2) in organic light-emitting diodes (OLEDs). The decreased external quantum efficiency (ηext) in an OLED with a cathode diameter of d=50μm was in excellent agreement with the singlet–singlet annihilation (SSA) model. In contrast, the decreased ηext in an OLED with a cathode diameter of d=1000μm coincided well with the singlet-heat annihilation (SHA) model. These results suggest that large OLEDs generate significant Joule heat, which causes additional exciton dissociation in addition to SSA. We also used a very thermally conductive sapphire substrate (46k∕Wm−1K−1) combined with a small cathode diameter of 50μm in an OLED to alleviate the ηext roll off characteristics and achieved injection at a much higher current density. With this device configuration, a maximum current density of Jmax=447A∕cm2 was achieved. However, decreased ηext based on SHA was observed in the high current region, indicating that significant Joule heat was generated under a few hundred A∕cm2 that induced additional exciton dissociation even when the sapphire substrate was used.
Public Input in Toxic Site Cleanup Decisions: The Strengths and Limitations of Community Advisory Boards
Authors: Laurian Lucie
Published: May 2005

Toxic sites worldwide expose millions to environmental and health risks. In response, public agencies in Western Europe and the United States have begun to identify and remediate contaminated sites. Public participation in cleanup decisions is a critical part of this process. US agencies increasingly rely on Community Advisory Boards (CABs) to facilitate long-term participation. CABs are intended to inform and consult the public and integrate citizens' input in cleanup decisions. Recent research, however, finds that participatory processes often fall short of their objectives. This paper examines the performance of CABs in involving the public in toxic sites cleanup decisions in the United States. The research (1) develops a conceptual framework and a quantitative methodology to assess CABs; and (2) uses this methodology to assess whether CABs achieve successful participation. The analysis targets CABs at five toxic sites in Tucson, Arizona, and builds on the content analysis of eighty-one CAB meeting minutes, twenty-seven interviews with CAB members, and a survey of eighty residents around three of the sites. The key findings are that, although CABs successfully diffuse information from agencies to CAB members and (to a lesser degree) gather feedback from CAB members, they fail to inform the general public and provide community feedback to the agency.
An Algorithmic Definition of the Axial Map
Authors: Turner Alasdair , Penn Alan , Hillier Bill
Published: May 2005

The fewest-line axial map, often simply referred to as the ‘axial map’, is one of the primary tools of space syntax. Its natural language definition has allowed researchers to draw consistent maps that present a concise description of architectural space; it has been established that graph measures obtained from the map are useful for the analysis of pedestrian movement patterns and activities related to such movement: for example, the location of services or of crime. However, the definition has proved difficult to translate into formal language by mathematicians and algorithmic implementers alike. This has meant that space syntax has been criticised for a lack of rigour in the definition of one of its fundamental representations. Here we clarify the original definition of the fewest-line axial map and show that it can be implemented algorithmically. We show that the original definition leads to maps similar to those currently drawn by hand, and we demonstrate that the differences between the two may be accounted for in terms of the detail of the algorithm used. We propose that the analytical power of the axial map in empirical studies derives from the efficient representation of key properties of the spatial configuration that it captures.
Towards the Mass Customization of Housing: The Grammar of Siza's Houses at Malagueira
Authors: Duarte José Pinto
Published: May 2005

The goal of the described research is an interactive computer system for the design of customized mass housing. Shape grammars are the formalism proposed to systematize the design rules required for such a system. A shape grammar for Alvaro Siza's patio houses at Malagueira, a 1200-unit development still being designed and constructed today, is presented. The grammar is based on the corpus of thirty-five houses designed between 1977 and 1996. The generation of houses in the grammar proceeds by the recursive dissection of rectangles locating four different functional zones (patio, living, services, and sleeping) and the key placement of the staircase. The schematic generations of two existing houses and the detailed generation of a novel one illustrate the grammar.
Collaborative Decisionmaking for Sustainable Urban Renewal Projects: A Simulation – Gaming Approach
Authors: Mayer Igor S , van Bueren Ellen M , Bots Pieter W G , van der Voort Haiko , Seijdel Robin
Published: May 2005

Differences in stakeholders' perceptions, lack of commitment, unused knowledge, and interfering, ineffective, measures are just some of the problems encountered in sustainable urban development projects. Collaborative decisionmaking approaches tackle these problems by creating a shared understanding of the problems faced and of ways to address them. The authors explore how the combined application of two techniques, a decision-support tool and a simulation game, can support decisionmaking for sustainable urban development. The techniques are applied in decision-making for real and in fictional sustainable urban renewal projects. Benefits and challenges of this combined approach are discussed based on experiences in seven applications. The main finding is that the use of the decision-support tool combined with the simulation–gaming procedure can support agenda setting and help create a shared understanding of problems and potential solutions in the field of sustainable urban renewal.
The two-component signal transduction system RR06/HK06 regulates expression of
cbpA
in
Streptococcus pneumoniae
Authors: Standish Alistair J. , Stroeher Uwe H. , Paton James C.
Published: May 2005

Streptococcus pneumoniae
encounters a number of environmental niches in the body, including the nasopharynx, lungs, blood, middle ear, and brain. Recent studies have identified 13 putative two-component signal-transduction systems in
S. pneumoniae
, which are likely to be important for gene regulation in response to external stimuli. Here, we present conclusive evidence for the regulation of choline binding protein A (CbpA), a major pneumococcal virulence factor and protective antigen, by one of these two-component signal-transduction systems. We have demonstrated divergent expression of
cbpA
in unmarked
hk06
and
rr06
deletion mutants relative to wild-type
S. pneumoniae
D39 by using Western immunoblotting and real-time RT-PCR. Electrophoretic mobility-shift and solid-phase binding assays have demonstrated the binding of RR06 to the promoter region of
cbpA
, suggesting that RR06/HK06 directly regulates
cbpA
transcription. We have also shown that this system is important for the ability of the pneumococcus to adhere to epithelial cells
in vitro
and to survive and proliferate in an
in vivo
mouse model. Thus, the RR06/HK06 system has a significant role in pathogenesis, both in colonization and invasive disease.
Human coronavirus NL63 employs the severe acute respiratory syndrome coronavirus receptor for cellular entry
Authors: Hofmann Heike , Pyrc Krzysztof , van der Hoek Lia , Geier Martina , Berkhout Ben , Pöhlmann Stefan
Published: May 2005

Coronavirus (CoV) infection of humans is usually not associated with severe disease. However, discovery of the severe acute respiratory syndrome (SARS) CoV revealed that highly pathogenic human CoVs (HCoVs) can evolve. The identification and characterization of new HCoVs is, therefore, an important task. Recently, a HCoV termed NL63 was discovered in patients with respiratory tract illness. Here, cell tropism and receptor usage of HCoV-NL63 were analyzed. The NL63 spike (S) protein mediated infection of different target cells compared with the closely related 229E-S protein but facilitated entry into cells known to be permissive to SARS-CoV-S-driven infection. An analysis of receptor engagement revealed that NL63-S binds angiotensin-converting enzyme (ACE) 2, the receptor for SARS-CoV, and HCoV-NL63 uses ACE2 as a receptor for infection of target cells. Potent neutralizing activity directed against NL63- but not 229E-S protein was detected in virtually all sera from patients 8 years of age or older, suggesting that HCoV-NL63 infection of humans is common and usually acquired during childhood. Here, we show that SARS-CoV shares its receptor ACE2 with HCoV-NL63. Because the two viruses differ dramatically in their ability to induce disease, analysis of HCoV-NL63 might unravel pathogenicity factors in SARS-CoV. The frequent HCoV-NL63 infection of humans suggests that highly pathogenic variants have ample opportunity to evolve, underlining the need for vaccines against HCoVs.
The crystal structures of human steroidogenic factor-1 and liver receptor homologue-1
Authors: Wang Weiru , Zhang Chao , Marimuthu Adhirai , Krupka Heike I. , Tabrizizad Maryam , Shelloe Rafe , Mehra Upasana , Eng Kevin , Nguyen Hoa , Settachatgul Calvin , Powell Ben , Milburn Michael V. , West Brian L.
Published: May 2005

Steroidogenic factor-1 (SF-1) and liver receptor homologue-1 (LRH-1) belong to the fushi tarazu factor 1 subfamily of nuclear receptors. SF-1 is an essential factor for sex determination during development and regulates adrenal and gonadal steroidogenesis in the adult, whereas LRH-1 is a critical factor for development of endodermal tissues and regulates cholesterol and bile acid homeostasis. Regulatory ligands are unknown for SF-1 and LRH-1. A reported mouse LRH-1 structure revealed an empty pocket in a region commonly occupied by ligands in the structures of other nuclear receptors, and pocket-filling mutations did not alter the constitutive activity observed. Here we report the crystal structures of the putative ligand-binding domains of human SF-1 at 2.1-Å resolution and human LRH-1 at 2.5-Å resolution. Both structures bind a coactivator-derived peptide at the canonical activation–function surface, thus adopting the transcriptionally activating conformation. In human LRH-1, coactivator peptide binding also occurs to a second site. We discovered in both structures a phospholipid molecule bound in a pocket of the putative ligand-binding domain. MS analysis of the protein samples used for crystallization indicated that the two proteins associate with a range of phospholipids. Mutations of the pocket-lining residues reduced the transcriptional activities of SF-1 and LRH-1 in mammalian cell transfection assays without affecting their expression levels. These results suggest that human SF-1 and LRH-1 may be ligand-binding receptors, although it remains to be seen if phospholipids or possibly other molecules regulate SF-1 or LRH-1 under physiological conditions.
Inhibition of protein kinase CK2 prevents the progression of glomerulonephritis
Authors: Yamada Masateru , Katsuma Susumu , Adachi Tetsuya , Hirasawa Akira , Shiojima Satoshi , Kadowaki Tadashi , Okuno Yasushi , Koshimizu Taka-aki , Fujii Shigeo , Sekiya Yumiko , Miyamoto Yohei , Tamura Mitsutaka , Yumura Wako , Nihei Hiroshi , Kobayashi Makio , Tsujimoto Gozoh
Published: May 2005

Glomerulonephritis (GN) is a progressive inflammation that may be caused by a variety of underlying disorders. It is the primary cause of chronic renal failure and end-stage renal disease, which require dialysis and transplantation worldwide. Immunosuppressive therapy has been used to treat GN clinically, but this treatment has had insufficient therapeutic effects. Here, we show that protein kinase CK2 is a key molecule in the progression of GN. cDNA microarray analysis identified CK2α, the catalytic subunit of CK2, as a GN-related, differentially expressed gene. Overexpression of CK2α was noted in the proliferative glomerular lesions in rat GN models and in renal biopsy specimens from lupus nephritis or IgA nephropathy patients. Administration of either antisense oligodeoxynucleotide against CK2α or low molecular weight CK2-specific inhibitors effectively prevented the progression of renal pathology in the rat GN models. The resolution of GN by CK2 inhibition may result from its suppression of extracellular signal-regulated kinase-mediated cell proliferation, and its suppression of inflammatory and fibrotic processes that are enhanced in GN. Our results show that CK2 plays a critical role in the progression of immunogenic renal injury, and therefore, CK2 is a potential target for GN therapy.
A network analysis of committees in the U.S. House of Representatives
Authors: Porter Mason A. , Mucha Peter J. , Newman M. E. J. , Warmbrand Casey M.
Published: May 2005

Network theory provides a powerful tool for the representation and analysis of complex systems of interacting agents. Here, we investigate the U.S. House of Representatives network of committees and subcommittees, with committees connected according to “interlocks,” or common membership. Analysis of this network reveals clearly the strong links between different committees, as well as the intrinsic hierarchical structure within the House as a whole. We show that network theory, combined with the analysis of roll-call votes using singular value decomposition, successfully uncovers political and organizational correlations between committees in the House without the need to incorporate other political information.
Metal ion-binding properties of (N3)-deprotonated uridine, thymidine, and related pyrimidine nucleosides in aqueous solution
Authors: Knobloch Bernd , Linert Wolfgang , Sigel Helmut
Published: May 2005

The acidity constants for (N3)H of the uridine-type ligands (U) 5-fluorouridine, 5-chloro-2′-deoxyuridine, uridine, and thymidine (2′-deoxy-5-methyluridine) and the stability constants of the M(U–H)
+
complexes for M
2+
= Mg
2+
, Ca
2+
, Sr
2+
, Ba
2+
, Mn
2+
, Co
2+
, Ni
2+
, Cu
2+
, Zn
2+
, Cd
2+
, and Pb
2+
were measured (potentiometric pH titrations; aqueous solution; 25°C;
I
= 0.1 M, NaNO
3
). Plots of

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\begin{equation*}{\mathrm{log}}K_{{\mathrm{M}}({\mathrm{U}}-{\mathrm{H}})}^{{\mathrm{M}}}\end{equation*}\end{document}

vs.

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\begin{equation*}{\mathrm{p}}K_{{\mathrm{U}}}^{{\mathrm{H}}}\end{equation*}\end{document}

result in straight lines that are compared with previous plots for simple pyridine-type and
o
-amino(methyl)pyridine-type ligands as well as with the stabilities of the corresponding M(cytidine)
2+
complexes. The results indicate monodentate coordination to (N3)
–
in M(U–H)
+
for Co
2+
and Ni
2+
. For the M(U–H)
+
species of Cd
2+
, Zn
2+
, or Cu
2+
, increased stabilities imply that semichelates form, i.e., M
2+
is (N3)
–
-bound and coordinated water molecules form hydrogen bonds to (C2)O and (C4)O; these “double” semichelates are in equilibrium with “single” semichelates involving either (C2)O or (C4)O and possibly also with four-membered chelates for which M
2+
is innersphere-coordinated to (N3)
–
and a carbonyl oxygen. For the alkaline earth ions, semichelates dominate with the M
2+
outersphere bound to (N3)
–
and innersphere to one of the carbonyl oxygens. Mn(U–H)
+
is with its properties between those of Cd
2+
(which probably also hold for Pb
2+
) and the alkaline earth ions. In nucleic acids, M
2+
–C(O) interactions are expected, if support is provided by other primary binding sites. (N3)H may possibly be acidified via carbonyl-coordinated M
2+
to become a proton donor in the physiological pH range, at which direct (N3)
–
binding of M
2+
also seems possible.
Peptide signaling during terminal differentiation ofDictyostelium
Authors: Anjard Christophe , Loomis William F.
Published: May 2005

A wide variety of mechanisms have evolved for intercellular communication in metazoans, but some of the signaling molecules were already used in their predecessors. The social amoeba,Dictyostelium discoideum, is known to use peptides to trigger sporulation within fruiting bodies, but their sequences have not been defined. We found that the peptide signal spore differentiation factor 2 (SDF-2) is processed from acyl-CoA binding protein, AcbA. The mammalian homolog of AcbA is processed to diazepam binding inhibitor that binds to the GABAAreceptor in the brain and to peripheral 1,4 benzodiazepine receptors. AlthoughDictyosteliumhas neither GABAAnor peripheral-type benzodiazepine receptors, we find that both a diazepam binding inhibitor peptide and diazepam (Valium) can mimic SDF-2 in aDictyosteliumbioassay. Mutants lacking AcbA sporulate well only when developed in chimeras with WT cells. Using a yeast system we show that ligand binding to the SDF-2 receptor histidine kinase, DhkA, inhibits phosphorelay, which can account for its ability to induce rapid sporulation.
Quantitating intracellular transport of polyplexes by spatio-temporal image correlation spectroscopy
Authors: Kulkarni Rajan P. , Wu David D. , Davis Mark E. , Fraser Scott E.
Published: May 2005

Quantitatively understanding how nonviral gene delivery vectors (polyplexes) are transported inside cells is essential before they can be optimized for gene therapy and medical applications. In this study, we used spatio-temporal image correlation spectroscopy (ICS) to follow polymer-nucleic acid particles (polyplexes) of various sizes and analyze their diffusive-like and flow behaviors intracellularly to elucidate the mechanisms responsible for their transport. ICS is a quantitative imaging technique that allows the assessment of particle motion in complex systems, although it has not been widely used to date. We find that the internalized polyplexes are able to use microtubule motors for intracellular trafficking and exhibit different transport behaviors for short (<10 s) versus long (≈60 s) correlation times. This motion can be explained by a memory effect of the microtubule motors. These results reveal that, although microtubule motor biases may be present for short periods of time, resulting in a net directional velocity, the overall long-term motion of the polyplexes is best described as a random walk-like process. These studies suggest that spatio-temporal ICS is a powerful technique for assessing the nature of intracellular motion and provides a quantitative tool to compare the transport of different objects within a living cell.
Components of the REST/CoREST/histone deacetylase repressor complex are disrupted, modified, and translocated in HSV-1-infected cells
Authors: Gu Haidong , Liang Yu , Mandel Gail , Roizman Bernard
Published: May 2005

The infected cell protein (ICP)0 enables gene expression and the replication of herpes simplex virus (HSV)-1 in cells infected at low multiplicities and enhances the expression of genes introduced into cells by transfection or infection. We report that a short sequence of ICP0 is similar to a sequence in the amino terminus of CoREST, a corepressor that exists in complexes with the repressor REST and histone deacetylases (HDACs) 1 or 2 to repress cellular gene expression. In wild-type-virus-infected cells, HDAC1 dissociates from the CoREST/REST complex, CoREST and HDAC1 are phosphorylated by a process mediated by viral protein kinases, and CoREST and HDAC1 are partially translocated to the cytoplasm. In cells infected with a virus mutant (ΔICP4), in which ICP0 accumulates, but post-α gene expression is blocked, HDAC1 is dissociated from the CoREST/REST complex, but translocation to the cytoplasm does not occur. After infection with a mutant virus from which ICP0 is deleted, the complex remains intact, but, under conditions of productive infection, the complex is partially translocated to the cytoplasm. These results suggest that, at low multiplicities of infection, ICP0 blocks CoREST-mediated silencing of viral genes by dissociation of HDAC1, whereas subsequent modifications and translocation of the components of the complex are the functions of other viral gene products made later in infection.
The candidate tumor suppressor ING4 represses activation of the hypoxia inducible factor (HIF)
Authors: Ozer Abdullah , Wu Leeju C. , Bruick Richard K.
Published: May 2005

The hypoxia inducible factor (HIF) plays an important role in the progression of a number of pathophysiological processes including tumorigenesis. In addition to several well characterized oxygen-dependent modes of regulation, the function of the HIF transcription factor can also be influenced through the action of other regulatory pathways. Misregulation of these factors resulting in inappropriate HIF expression or activity can contribute to the progression of human cancers through the induction of genes promoting angiogenesis, glycolysis, cell survival, and metastasis, among other processes. The candidate tumor suppressor protein inhibitor of growth family member 4 (ING4) has recently been implicated as a repressor of angiogenesis and tumor growth through association with NF-κB. Here we demonstrate that suppression of ING4 further induces HIF transcriptional activity as well. ING4 directly associates with the HIF prolyl hydroxylase, an Fe(II)-dependent oxygenase previously shown to mediate HIF stability as a function of oxygen availability. However, rather than affecting HIF's stability, ING4 mediates HIF's activity. These data support a model in which, in addition to regulating HIF stability, HIF prolyl hydroxylases can modulate HIF function through the recruitment of ING4, a likely component of a chromatin-remodeling complex.
Sca-1 expression identifies stem cells in the proximal region of prostatic ducts with high capacity to reconstitute prostatic tissue
Authors: Burger Patricia E. , Xiong Xiaozhong , Coetzee Sandra , Salm Sarah N. , Moscatelli David , Goto Ken , Wilson E. Lynette
Published: May 2005

We previously showed that prostatic stem cells are concentrated in the proximal regions of prostatic ducts. We now report that these stem cells can be purified from isolated proximal duct regions by virtue of their high expression of the cell surface protein stem cell antigen 1 (Sca-1). In anin vivoprostate reconstitution assay, the purified Sca-1-expressing cell population isolated from the proximal region of ducts was more effective in generating prostatic tissue than a comparable population of Sca-1-depleted cells (203.0 ± 83.1 mg vs. 11.9 ± 9.2 mg) or a population of Sca-1-expressing cells isolated from the remaining regions of ducts (transit-amplifying cells) (31.9 ± 24.1 mg). Almost all of the proliferative capacity of the proximal duct Sca-1-expressing cell population resides within the fraction of cells that express high levels of Sca-1 (top one-third), with the proximal region of prostatic ducts containing 7.2-fold more Sca-1highcells than the remaining regions. More than 60% of the high-expressing cells coexpress α6 integrin and the antiapoptotic factor Bcl-2, markers that are also characteristic of stem cells of other origins. Further stratification of the phenotype of the stem cells may enable the development of rational therapies for treating prostate cancer and benign prostatic hyperplasia.
Irreversible inhibitors of the EGF receptor may circumvent acquired resistance to gefitinib
Authors: Kwak Eunice L. , Sordella Raffaella , Bell Daphne W. , Godin-Heymann Nadia , Okimoto Ross A. , Brannigan Brian W. , Harris Patricia L. , Driscoll David R. , Fidias Panos , Lynch Thomas J. , Rabindran Sridhar K. , McGinnis John P. , Wissner Allan , Sharma Sreenath V. , Isselbacher Kurt J. , Settleman Jeffrey , Haber Daniel A.
Published: May 2005

Non-small cell lung cancers (NSCLCs) with activating mutations in the kinase domain of the epidermal growth factor receptor (EGFR) demonstrate dramatic, but transient, responses to the reversible tyrosine kinase inhibitors gefitinib (Iressa) and erlotinib (Tarceva). Some recurrent tumors have a common secondary mutation in the EGFR kinase domain, T790M, conferring drug resistance, but in other cases the mechanism underlying acquired resistance is unknown. In studying multiple sites of recurrent NSCLCs, we detected T790M in only a small percentage of tumor cells. To identify additional mechanisms of acquired resistance to gefitinib, we used NSCLC cells harboring an activating EGFR mutation to generate multiple resistant clonesin vitro. These drug-resistant cells demonstrate continued dependence on EGFR and ERBB2 signaling for their viability and have not acquired secondary EGFR mutations. However, they display increased internalization of ligand-activated EGFR, consistent with altered receptor trafficking. Although gefitinib-resistant clones are cross-resistant to related anilinoquinazolines, they demonstrate sensitivity to a class of irreversible inhibitors of EGFR. These inhibitors also show effective inhibition of signaling by T790M-mutant EGFR and killing of NSCLC cells with the T790M mutation. Both mechanisms of gefitinib resistance are therefore circumvented by irreversible tyrosine kinase inhibitors. Our findings suggest that one of these, HKI-272, may prove highly effective in the treatment of EGFR-mutant NSCLCs, including tumors that have become resistant to gefitinib or erlotinib.
VEGF–integrin interplay controls tumor growth and vascularization
Authors: De Sarmishtha , Razorenova Olga , McCabe Noel Patrick , O'Toole Timothy , Qin Jun , Byzova Tatiana V.
Published: May 2005

Cross-talk between the major angiogenic growth factor, VEGF, and integrin cell adhesion receptors has emerged recently as a critical factor in the regulation of angiogenesis and tumor development. However, the molecular mechanisms and consequences of this intercommunication remain unclear. Here, we define a mechanism whereby integrin αvβ3, through activation, clustering, and signaling by means of p66 Shc (Src homology 2 domain containing), regulates the production of VEGF in tumor cells expressing this integrin. Tumors with “activatable” but not “inactive” β3 integrin secrete high levels of VEGF, which in turn promotes extensive neovascularization and augments tumor growth
in vivo
. This stimulation of VEGF expression depends upon the ability of αvβ3 integrin to cluster and promote phosphorylation of p66 Shc. These observations identify a link between β3 integrins and VEGF in tumor growth and angiogenesis and, therefore, may influence anti-integrin as well as anti-VEGF therapeutic strategies.
Sumoylation induced by the Arf tumor suppressor: A p53-independent function
Authors: Tago Kenji , Chiocca Susanna , Sherr Charles J.
Published: May 2005

The mouse p19
Arf
protein has both p53-dependent and p53-independent tumor-suppressive activities. Arf triggers sumoylation of many cellular proteins, including Mdm2 and nucleophosmin (NPM/B23), with which p19
Arf
physically interacts
in vivo
, and this occurs equally well in cells expressing or lacking functional p53. In an
Arf
-null NIH 3T3 cell derivative (MT-
Arf
cells) engineered to reexpress an
Arf
transgene driven by a zinc-inducible metallothionein promoter, sumoylation of endogenous Mdm2 and NPM proteins was initiated as p19
Arf
was induced and was observed before p53-dependent cell cycle arrest. Predominately nucleoplasmic molecules visualized by immunofluorescence with antibodies to small ubiquitin-like modifier (SUMO) 1 localized to nucleoli as p19
Arf
accumulated there. Two Arf mutants, one of which binds to Mdm2 and NPM but is excluded from nucleoli and the other of which enters nucleoli but is handicapped in binding to Mdm2 and NPM, were defective in inducing sumoylation of these two target proteins and did not localize bulk sumoylated molecules to nucleoli. The CELO adenovirus protein, Gam1, which inhibits the SUMO activating enzyme (E1) and leads to down-regulation of the SUMO conjugating enzyme (E2/Ubc9), had no overt effect on the ability of p19
Arf
to activate p53 or the p53-responsive genes encoding Mdm2 and p21
Cip1
, despite the fact that Arf-induced sumoylation of Mdm2 was blocked. Reduction of Ubc9 levels with short hairpin RNAs rendered similar results. We suggest that Arf's p53-independent effects on gene expression and tumor suppression might depend on Arf-induced sumoylation.
Overexpression of LMO4 induces mammary hyperplasia, promotes cell invasion, and is a predictor of poor outcome in breast cancer
Authors: Sum Eleanor Y. M. , Segara Davendra , Duscio Belinda , Bath Mary L. , Field Andrew S. , Sutherland Robert L. , Lindeman Geoffrey J. , Visvader Jane E.
Published: May 2005

The zinc finger protein LMO4 is overexpressed in a high proportion of breast carcinomas. Here, we report that overexpression of a mouse mammary tumor virus (MMTV)
-Lmo4
transgene in the mouse mammary gland elicits hyperplasia and mammary intraepithelial neoplasia or adenosquamous carcinoma in two transgenic strains with a tumor latency of 13–18 months. To investigate cellular processes controlled by LMO4 and those that may be deregulated during oncogenesis, we used RNA interference. Down-regulation of LMO4 expression reduced proliferation of human breast cancer cells and increased differentiation of mouse mammary epithelial cells. Furthermore, small-interfering-RNA-transfected breast cancer cells (MDA-MB-231) had a reduced capacity to migrate and invade an extracellular matrix. Conversely, overexpression of LMO4 in noninvasive, immortalized human MCF10A cells promoted cell motility and invasion. Significantly, in a cohort of 159 primary breast cancers, high nuclear levels of LMO4 were an independent predictor of death from breast cancer. Together, these findings suggest that deregulation of LMO4 in breast epithelium contributes directly to breast neoplasia by altering the rate of cellular proliferation and promoting cell invasion.
Essential function of Drosophila Sec6 in apical exocytosis of epithelial photoreceptor cells
Authors: Beronja Slobodan , Laprise Patrick , Papoulas Ophelia , Pellikka Milena , Sisson John , Tepass Ulrich
Published: May 2005

Polarized exocytosis plays a major role in development and cell differentiation but the mechanisms that target exocytosis to specific membrane domains in animal cells are still poorly understood. We characterized Drosophila Sec6, a component of the exocyst complex that is believed to tether secretory vesicles to specific plasma membrane sites. sec6 mutations cause cell lethality and disrupt plasma membrane growth. In developing photoreceptor cells (PRCs), Sec6 but not Sec5 or Sec8 shows accumulation at adherens junctions. In late PRCs, Sec6, Sec5, and Sec8 colocalize at the rhabdomere, the light sensing subdomain of the apical membrane. PRCs with reduced Sec6 function accumulate secretory vesicles and fail to transport proteins to the rhabdomere, but show normal localization of proteins to the apical stalk membrane and the basolateral membrane. Furthermore, we show that Rab11 forms a complex with Sec5 and that Sec5 interacts with Sec6 suggesting that the exocyst is a Rab11 effector that facilitates protein transport to the apical rhabdomere in Drosophila PRCs.
Endoplasmic reticulum stress signaling transmitted by ATF6 mediates apoptosis during muscle development
Authors: Nakanishi Keiko , Sudo Tatsuhiko , Morishima Nobuhiro
Published: May 2005

Although apoptosis occurs during myogenesis, its mechanism of initiation remains unknown. In a culture model, we demonstrate activation of caspase-12, the initiator of the endoplasmic reticulum (ER) stress-specific caspase cascade, during apoptosis associated with myoblast differentiation. Induction of ER stress-responsive proteins (BiP and CHOP) was also observed in both apoptotic and differentiating cells. ATF6, but not other ER stress sensors, was specifically activated during apoptosis in myoblasts, suggesting that partial but selective activation of ER stress signaling was sufficient for induction of apoptosis. Activation of caspase-12 was also detected in developing muscle of mouse embryos and gradually disappeared later. CHOP was also transiently induced. These results suggest that specific ER stress signaling transmitted by ATF6 leads to naturally occurring apoptosis during muscle development.
Inducible ablation of mouse Langerhans cells diminishes but fails to abrogate contact hypersensitivity
Authors: Bennett Clare L. , van Rijn Erwin , Jung Steffen , Inaba Kayo , Steinman Ralph M. , Kapsenberg Martien L. , Clausen Björn E.
Published: May 2005

Langerhans cells (LC) form a unique subset of dendritic cells (DC) in the epidermis but so far their in vivo functions in skin immunity and tolerance could not be determined, in particular in relation to dermal DC (dDC). Here, we exploit a novel diphtheria toxin (DT) receptor (DTR)/DT-based system to achieve inducible ablation of LC without affecting the skin environment. Within 24 h after intra-peritoneal injection of DT into Langerin-DTR mice LC are completely depleted from the epidermis and only begin to return 4 wk later. LC deletion occurs by apoptosis in the absence of inflammation and, in particular, the dDC compartment is not affected. In LC-depleted mice contact hypersensitivity (CHS) responses are significantly decreased, although ear swelling still occurs indicating that dDC can mediate CHS when necessary. Our results establish Langerin-DTR mice as a unique tool to study LC function in the steady state and to explore their relative importance compared with dDC in orchestrating skin immunity and tolerance.
Palmitoylation regulates plasma membrane–nuclear shuttling of R7BP, a novel membrane anchor for the RGS7 family
Authors: Drenan Ryan M. , Doupnik Craig A. , Boyle Maureen P. , Muglia Louis J. , Huettner James E. , Linder Maurine E. , Blumer Kendall J.
Published: May 2005

The RGS7 (R7) family of RGS proteins bound to the divergent Gβ subunit Gβ5 is a crucial regulator of G protein–coupled receptor (GPCR) signaling in the visual and nervous systems. Here, we identify R7BP, a novel neuronally expressed protein that binds R7–Gβ5 complexes and shuttles them between the plasma membrane and nucleus. Regional expression of R7BP, Gβ5, and R7 isoforms in brain is highly coincident. R7BP is palmitoylated near its COOH terminus, which targets the protein to the plasma membrane. Depalmitoylation of R7BP translocates R7BP–R7–Gβ5 complexes from the plasma membrane to the nucleus. Compared with nonpalmitoylated R7BP, palmitoylated R7BP greatly augments the ability of RGS7 to attenuate GPCR-mediated G protein–regulated inward rectifying potassium channel activation. Thus, by controlling plasma membrane nuclear–shuttling of R7BP–R7–Gβ5 complexes, reversible palmitoylation of R7BP provides a novel mechanism that regulates GPCR signaling and potentially transduces signals directly from the plasma membrane to the nucleus.
TGF-β–dependent CD103 expression by CD8+ T cells promotes selective destruction of the host intestinal epithelium during graft-versus-host disease
Authors: El-Asady Riham , Yuan Rongwen , Liu Kechang , Wang Donghua , Gress Ronald E. , Lucas Philip J. , Drachenberg Cinthia B. , Hadley Gregg A.
Published: May 2005

Destruction of the host intestinal epithelium by donor effector T cell populations is a hallmark of graft-versus-host disease (GVHD), but the underlying mechanisms remain obscure. We demonstrate that CD8+ T cells expressing CD103, an integrin conferring specificity for the epithelial ligand E-cadherin, play a critical role in this process. A TCR transgenic GVHD model was used to demonstrate that CD103 is selectively expressed by host-specific CD8+ T cell effector populations (CD8 effectors) that accumulate in the host intestinal epithelium during GVHD. Although host-specific CD8 effectors infiltrated a wide range of host compartments, only those infiltrating the intestinal epithelium expressed CD103. Host-specific CD8 effectors expressing a TGF-β dominant negative type II receptor were defective in CD103 expression on entry into the intestinal epithelium, which indicates local TGF-β activity as a critical regulating factor. Host-specific CD8 effectors deficient in CD103 expression successfully migrated into the host intestinal epithelium but were retained at this site much less efficiently than wild-type host-specific CD8 effectors. The relevance of these events to GVHD pathogenesis is supported by the finding that CD103-deficient CD8+ T cells were strikingly defective in transferring intestinal GVHD pathology and mortality. Collectively, these data document a pivotal role for TGF-β–dependent CD103 expression in dictating the gut tropism, and hence the destructive potential, of CD8+ T cells during GVHD pathogenesis.
Available carbon source influences the resistance of Neisseria meningitidis against complement
Authors: Exley Rachel M. , Shaw Jonathan , Mowe Eva , Sun Yao-hui , West Nicholas P. , Williamson Michael , Botto Marina , Smith Harry , Tang Christoph M.
Published: May 2005

Neisseria meningitidis is an important cause of septicaemia and meningitis. To cause disease, the bacterium must acquire essential nutrients for replication in the systemic circulation, while avoiding exclusion by host innate immunity. Here we show that the utilization of carbon sources by N. meningitidis determines its ability to withstand complement-mediated lysis, through the intimate relationship between metabolism and virulence in the bacterium. The gene encoding the lactate permease, lctP, was identified and disrupted. The lctP mutant had a reduced growth rate in cerebrospinal fluid compared with the wild type, and was attenuated during bloodstream infection through loss of resistance against complement-mediated killing. The link between lactate and complement was demonstrated by the restoration of virulence of the lctP mutant in complement (C3−/−)-deficient animals. The underlying mechanism for attenuation is mediated through the sialic acid biosynthesis pathway, which is directly connected to central carbon metabolism. The findings highlight the intimate relationship between bacterial physiology and resistance to innate immune killing in the meningococcus.
Shared reactivity of Vδ2neg γδ T cells against cytomegalovirus-infected cells and tumor intestinal epithelial cells
Authors: Halary Franck , Pitard Vincent , Dlubek Dorota , Krzysiek Roman , de la Salle Henri , Merville Pierre , Dromer Claire , Emilie Dominique , Moreau Jean-François , Déchanet-Merville Julie
Published: May 2005

Long-lasting expansion of Vδ2neg γδ T cells is a hallmark of cytomegalovirus (CMV) infection in kidney transplant recipients. The ligands of these cells and their role remain elusive. To better understand their immune function, we generated γδ T cell clones from several transplanted patients. Numerous patient Vδ1+, Vδ3+, and Vδ5+ γδ T cell clones expressing diverse Vγ chains, but not control Vγ9Vδ2+ T clones, displayed strong reactivity against CMV-infected cells, as shown by their production of tumor necrosis factor-α. Vδ2neg γδ T lymphocytes could also kill CMV-infected targets and limit CMV propagation in vitro. Their anti-CMV reactivity was specific for this virus among herpesviridae and required T cell receptor engagement, but did not involve major histocompatibility complex class I molecules or NKG2D. Vδ2neg γδ T lymphocytes expressed receptors essential for intestinal homing and were strongly activated by intestinal tumor, but not normal, epithelial cell lines. High frequencies of CMV- and tumor-specific Vδ2neg γδ T lymphocytes were found among patients' γδ T cells. In conclusion, Vδ2neg γδ T cells may play a role in protecting against CMV and tumors, probably through mucosal surveillance of cellular stress, and represent a population that is largely functionally distinct from Vγ9Vδ2+ T cells.
IκB kinase (IKK)β, but not IKKα, is a critical mediator of osteoclast survival and is required for inflammation-induced bone loss
Authors: Ruocco Maria Grazia , Maeda Shin , Park Jin Mo , Lawrence Toby , Hsu Li-Chung , Cao Yixue , Schett Georg , Wagner Erwin F. , Karin Michael
Published: May 2005

Transcription factor, nuclear factor κB (NF-κB), is required for osteoclast formation in vivo and mice lacking both of the NF-κB p50 and p52 proteins are osteopetrotic. Here we address the relative roles of the two catalytic subunits of the IκB kinase (IKK) complex that mediate NF-κB activation, IKKα and IKKβ, in osteoclast formation and inflammation-induced bone loss. Our findings point out the importance of the IKKβ subunit as a transducer of signals from receptor activator of NF-κB (RANK) to NF-κB. Although IKKα is required for RANK ligand-induced osteoclast formation in vitro, it is not needed in vivo. However, IKKβ is required for osteoclastogenesis in vitro and in vivo. IKKβ also protects osteoclasts and their progenitors from tumor necrosis factor α–induced apoptosis, and its loss in hematopoietic cells prevents inflammation-induced bone loss.
Impaired early B cell tolerance in patients with rheumatoid arthritis
Authors: Samuels Jonathan , Ng Yen-Shing , Coupillaud Claire , Paget Daniel , Meffre Eric
Published: May 2005

Autoantibody production is a characteristic of most autoimmune diseases including rheumatoid arthritis (RA). The role of these autoantibodies in the pathogenesis of RA remains elusive, but they appear in the serum many years before the onset of clinical disease suggesting an early break in B cell tolerance. The stage of B cell development at which B cell tolerance is broken in RA remains unknown. We previously established in healthy donors that most polyreactive developing B cells are silenced in the bone marrow, and additional autoreactive B cells are removed in the periphery. B cell tolerance in untreated active RA patients was analyzed by testing the specificity of recombinant antibodies cloned from single B cells. We find that autoreactive B cells fail to be removed in all six RA patients and represent 35–52% of the mature naive B cell compartment compared with 20% in healthy donors. In some patients, RA B cells express an increased proportion of polyreactive antibodies that can recognize immunoglobulins and cyclic citrullinated peptides, suggesting early defects in central B cell tolerance. Thus, RA patients exhibit defective B cell tolerance checkpoints that may favor the development of autoimmunity.
Hematopoietic cells maintain hematopoietic fates upon entering the brain
Authors: Massengale Mei , Wagers Amy J. , Vogel Hannes , Weissman Irving L.
Published: May 2005

Several studies have reported that bone marrow (BM) cells may give rise to neurons and astrocytes in vitro and in vivo. To further test this hypothesis, we analyzed for incorporation of neural cell types expressing donor markers in normal or injured brains of irradiated mice reconstituted with whole BM or single, purified c-kit+Thy1.1loLin−Sca-1+ (KTLS) hematopoietic stem cells (HSCs), and of unirradiated parabionts with surgically anastomosed vasculature. Each model showed low-level parenchymal engraftment of donor-marker+ cells with 96–100% immunoreactivity for panhematopoietic (CD45) or microglial (Iba1 or Mac1) lineage markers in all cases studied. Other than one arborizing structure in the olfactory bulb of one BM-transplanted animal, possibly representing a neuronal or glial cell process, we found no donor-marker–expressing astrocytes or non-Purkinje neurons among >10,000 donor-marker+ cells from 21 animals. These data strongly suggest that HSCs and their progeny maintain lineage fidelity in the brain and do not adopt neural cell fates with any measurable frequency.
In vivo costimulatory role of B7-DC in tuning T helper cell 1 and cytotoxic T lymphocyte responses
Authors: Shin Tahiro , Yoshimura Kiyoshi , Shin Takako , Crafton Emily B. , Tsuchiya Haruo , Housseau Franck , Koseki Haruhiko , Schulick Richard D. , Chen Lieping , Pardoll Drew M.
Published: May 2005

B7-DC, one of the recently described B7 family members, has the capacity to inhibit T cell responses via engagement of the immunoreceptor tyrosine-based inhibitory motif–containing inhibitory PD-1 receptor as well as enhance responses via an as yet unidentified costimulatory receptor. B7-DC is highly homologous to a coinhibitory B7 family member, B7-H1, which also binds PD-1. It is currently unclear which B7-DC function—costimulation or inhibition—predominates in vivo. To study in vivo functions of B7-DC, we evaluated immune responses in B7-DC knockout (KO) mice. Although not eliminated, interferon-γ (IFN-γ) production by CD4 T cells and IFN-γ–dependent humoral responses were reduced in B7-DC KO mice relative to wild type mice. Antigen-specific CD8 T cell responses and cytotoxic T lymphocyte (CTL) activity were also diminished in B7-DC KO mice. Hepatic tumors grew more quickly in B7-DC KO mice, associated with a decrease in intrahepatic tumor-specific CD8 T cells. These results highlight the contrasting in vivo roles of B7-DC and B7-H1 and indicate that B7-DC functions as a tuning molecule, selectively augmenting T helper 1 and CTL responses.