bluuebunny/crossref_metadata_2025 huggingface dataset:
Alzheimer's disease neurofibrillary degeneration: pivotal and multifactorial
Authors: Iqbal Khalid , Wang Xiaochuan , Blanchard Julie , Liu Fei , Gong Cheng-Xin , Grundke-Iqbal Inge
Published: July 2010

Independent of the aetiology, AD (Alzheimer's disease) neurofibrillary degeneration of abnormally hyperphosphorylated tau, a hallmark of AD and related tauopathies, is apparently required for the clinical expression of the disease and hence is a major therapeutic target for drug development. However, AD is multifactorial and heterogeneous and probably involves several different aetiopathogenic mechanisms. On the basis of CSF (cerebrospinal fluid) levels of Aβ1–42 (where Aβ is amyloid β-peptide), tau and ubiquitin, five different subgroups, each with its own clinical profile, have been identified. A successful development of rational therapeutic disease-modifying drugs for AD will require understanding of the different aetiopathogenic mechanisms involved and stratification of AD patients by different disease subgroups in clinical trials. We have identified a novel aetiopathogenic mechanism of AD which is initiated by the cleavage of SET, also known as inhibitor-2 (I2PP2A) of PP2A (protein phosphatase 2A) at Asn175 into N-terminal (I2NTF) and C-terminal (I2CTF) halves and their translocation from the neuronal nucleus to the cytoplasm. AAV1 (adeno-associated virus 1)-induced expression of I2CTF in rat brain induces inhibition of PP2A activity, abnormal hyperphosphorylation of tau, neurodegeneration and cognitive impairment in rats. Restoration of PP2A activity by inhibition of the cleavage of I2PP2A/SET offers a promising therapeutic opportunity in AD with this aetiopathogenic mechanism.
Modulation of tau pathology in tau transgenic models
Authors: Brion Jean-Pierre , Ando Kunie , Heraud Céline , Leroy Karelle
Published: July 2010

NFTs (neurofibrillary tangles) in Alzheimer's disease and in tauopathies are hallmark neuropathological lesions whose relationship with neuronal dysfunction, neuronal death and with other lesions [such as Aβ (amyloid β-peptide) pathology] are still imperfectly understood. Many transgenic mice overexpressing wild-type or mutant tau proteins have been generated to investigate the physiopathology of tauopathies. Most of the mice overexpressing wild-type tau do not develop NFTs, but can develop a severe axonopathy, whereas overexpression of mutant tau leads to NFT formation, synaptic loss and neuronal death in several models. The association between neuronal death and NFTs has, however, been challenged in some models showing a dissociation between tau aggregation and tau toxicity. Cross-breeding of mice developing NFTs with mice developing Aβ deposits increases NFT pathology, highlighting the relationship between tau and amyloid pathology. On the other hand, tau expression seems to be necessary for expression of a pathological phenotype associated with amyloid pathology. These findings suggest that there is a bilateral cross-talk between Aβ and tau pathology. These observations are discussed by the presentation of some relevant models developed recently.
NMR spectroscopy of the neuronal tau protein: normal function and implication in Alzheimer's disease
Authors: Landrieu Isabelle , Leroy Arnaud , Smet-Nocca Caroline , Huvent Isabelle , Amniai Laziza , Hamdane Malika , Sibille Nathalie , Buée Luc , Wieruszeski Jean-Michel , Lippens Guy
Published: July 2010

NMR spectroscopy was used to explore the different aspects of the normal and pathological functions of tau, but proved challenging because the protein contains 441 amino acids and has poor signal dispersion. We have set out to dissect the phosphorylation patterns of tau in order to understand better its role in the aggregation process and microtubule-binding regulation. Our current knowledge on the functional consequences of specific phosphorylations is still limited, mainly because producing and assessing quantitatively phosphorylated tau samples is far from straightforward, even in vitro. We use NMR spectroscopy as a proteomics tool to characterize the phosphorylation patterns of tau, after in vitro phosphorylation by recombinant kinases. The phosphorylated tau can next be use for functional assays or interaction assays with phospho-dependent protein partners, such as the prolyl cis–trans isomerase Pin1.
Functional implications of the association of tau with the plasma membrane
Authors: Pooler Amy M. , Hanger Diane P.
Published: July 2010

Tau is an abundant microtubule-associated protein which regulates the stability of the cytoskeleton. Tau binds microtubules directly through microtubule-binding domains in its C-terminus. However, tau is not only located in the cytosol of cells, but also associated with other intracellular domains, including the plasma membrane, suggesting that tau may have additional functions other than stabilizing the neuronal cytoskeleton. Localization of tau at the cell surface appears to be dependent on interactions of the N-terminal projection domain of tau. Furthermore, membrane-associated tau is dephosphorylated at serine/threonine residues, suggesting that the phosphorylation state of tau regulates its intracellular trafficking. Dephosphorylation of tau may increase the association of tau with trafficking proteins which target tau to the plasma membrane. Thus it is possible that the hyperphosphoryation of tau may contribute to the pathogenesis of Alzheimer's disease by promoting the formation of neurofibrillary tangles from cytosolic tau, and also by inhibiting additional tau functions through disruption of its targeting to the plasma membrane.
Developments in three-dimensional cell culture technology aimed at improving the accuracy ofin vitroanalyses
Authors: Maltman Daniel J. , Przyborski Stefan A.
Published: July 2010

Drug discovery programmes require accurate in vitro systems for drug screening and testing. Traditional cell culture makes use of 2D (two-dimensional) surfaces for ex vivo cell growth. In such environments, cells are forced to adopt unnatural characteristics, including aberrant flattened morphologies. Therefore there is a strong demand for new cell culture platforms which allow cells to grow and respond to their environment in a more realistic manner. The development of 3D (three-dimensional) alternative substrates for in vitro cell growth has received much attention, and it is widely acknowledged that 3D cell growth is likely to more accurately reflect the in vivo tissue environments from which cultured cells are derived. 3D cell growth techniques promise numerous advantages over 2D culture, including enhanced proliferation and differentiation of stem cells. The present review focuses on the development of scaffold technologies for 3D cell culture.
Human papillomavirus regulation of SR proteins
Authors: McFarlane Melanie , Graham Sheila V.
Published: July 2010

Splicing is a cellular process essential for mRNA biogenesis. There are two types of splicing: constitutive and alternative splicing. During constitutive splicing, non-coding intron sequences are removed and exonic coding sequences are spliced together to form mature mRNAs. Alternative splicing can maximize the coding capacity of the genome by specific alternative selection of exons from multi-exon metazoan pre-mRNAs. Splicing is a tightly regulated process, so when control is lost disease may occur. SR proteins (serine/arginine-rich proteins) are a family of highly conserved splicing regulators that are also involved in other steps in RNA biogenesis and expression. Many viruses have evolved to utilize the cellular splicing machinery to enhance their proteome from a limited number of genes. HPV (human papillomavirus) is an example of one such virus. The HPV transcription/replication factor E2 (early 2) specifically up-regulates expression of the SR proteins SF2/ASF (splicing factor 2/alternative splicing factor), SRp20 and SC35 in infected epithelial cells. These SR proteins are essential for viral RNA processing. SF2/ASF is a proto-oncogene that is also up-regulated in a number of cancers. For example, SF2/ASF, together with SRp20 and SC35 is selectively up-regulated in cervical tumours caused by persistent oncogenic HPV infection. However, the mode of SR protein up-regulation in tumours is different to the E2-directed transcriptional regulation in normal transient HPV infection. SR proteins could provide excellent targets for HPV antiviral therapy as well as anticancer therapy.
Inhibition of translation initiation following glucose depletion in yeast facilitates a rationalization of mRNA content
Authors: Lui Jennifer , Campbell Susan G. , Ashe Mark P.
Published: July 2010

Glucose is the preferred carbon source for most eukaryotes and so it is important that cells can sense and react rapidly to fluctuations in glucose levels. It is becoming increasingly clear that the regulation of gene expression at the post-transcriptional level is important in the adaptation to changes in glucose levels, possibly as this could engender more rapid alterations in the concentrations of key proteins, such as metabolic enzymes. Following the removal of glucose from yeast cells a rapid inhibition of translation is observed. As a consequence, mRNPs (messenger ribonucleoproteins) relocalize into cytoplasmic granules known as P-bodies (processing bodies) and EGP-bodies. mRNA decay components localize into P-bodies, and thus these assemblies are likely to represent sites where mRNAs are targeted for degradation. In contrast, EGP-bodies lack any decay components and contain the eukaryotic translation initiation factors eIF4E, eIF4G and Pab1p, as well as other RNA-binding proteins. Therefore EGP-bodies probably constitute sites where mRNAs are earmarked for storage. So, it is possible that cells distinguish between transcripts and target them to either P-bodies or EGP-bodies depending on their functional value. The localization of mRNAs into these granules following glucose starvation may serve to preserve mRNAs that are involved in the diauxic shift to ethanol growth and entry into stationary phase, as well as to degrade mRNAs that are solely involved in glucose fermentation.
3′ uridylation and the regulation of RNA function in the cytoplasm
Authors: Norbury Chris J.
Published: July 2010

Degradation of cytoplasmic mRNAs is an important aspect of the regulation of gene function in eukaryotes. Much of what is currently known about the underlying pathways of mRNA decay is derived from studies of the budding yeast Saccharomyces cerevisiae, in which mRNA turnover is initiated by deadenylation, followed either by decapping and 5′→3′ degradation or by further 3′→5′ exonucleolysis. Our studies using RNA cRACE (circularization-based rapid amplification of cDNA ends) techniques indicate that mRNA decapping in the fission yeast Schizosaccharomyces pombe often does not require prior deadenylation. Furthermore, the poly(A) polymerase-related, cytoplasmic enzyme Cid1 catalyses uridylation of a variety of functionally diverse poly(A)+ mRNAs and hence stimulates decapping as part of a novel mRNA turnover pathway. The pathways initiated by uridylation and deadenylation stimulate decapping in a partially redundant fashion, but urg1 mRNA is stabilized in mutants lacking cid1. Accumulation of uridylated RNAs in an lsm1 mutant suggests an involvement of the Lsm1–7 complex in recognition of the 3′ uridylation tag and recruitment of the decapping machinery. Recent reports from other groups suggest that in metazoans, which unlike budding yeast contain Cid1 orthologues, 3′ uridylation by such enzymes is used to regulate miRNA (microRNA) and siRNA (small interfering RNA) biogenesis and activity. It has further been suggested that uridylation is an important regulatory modification of non-polyadenylated replication-dependent histone mRNAs. This modification may also form the basis of a widespread mechanism for the initiation of the decay of polyadenylated mRNAs in organisms other than fission yeast.
Offsetting Benefits? Analyzing Access to Forest Carbon
Authors: Corbera Esteve , Brown Katrina
Published: July 2010

Emissions trading has created new forms of exchangeable property which become commodities when traded in markets designed to reduce greenhouse-gas emissions and mitigate climate change. This paper analyzes a set of social processes which influence who benefits from reductions in emissions generated by primary production from forest ecosystems. Informed by commodification literature, and property and access theory, we suggest that farmers and rural communities cannot derive full benefits from carbon sequestration because they lack key structural and relational mechanisms, such as capital, knowledge, expertise, technology, and, in some cases, even labour. We illustrate this argument by examining three ongoing carbon-forestry projects in China, Ecuador, and Mexico and we highlight its implications for future forestry mitigation projects and programmes.
The Rise and Fall of a Micro-Learning Region: Mexican Immigrants and Construction in Center-South Philadelphia
Authors: Iskander Natasha , Lowe Nichola , Riordan Christine
Published: July 2010

This paper documents the rise and fall of a micro-learning region in Philadelphia. The central actors in this region are undocumented Mexican immigrants who until recently were able to draw on the intensity of their workplace interactions and their heterodox knowledge to produce new and innovative building techniques in the city's residential construction. The new knowledge they developed was primarily tacit. More significantly, the learning practices through which immigrant workers developed skills and innovated new techniques were also heavily tacit. Because these practices were never made formal and were never made explicit, they remained invisible and difficult to defend. With the housing-market collapse and subsequent decline in housing renovation in the south-center region of Philadelphia, this tacit knowledge, and the practices that gave it shape and significance, are no longer easily accessible. We draw on this case to demonstrate the importance of access to the political and economic resources to turn learning practices into visible structured institutions that protect knowledge and skill. Whether or not the practices that support knowledge development are themselves made explicit can determine whether the knowledge they produce becomes an innovation that is recognized and adopted or whether it remains confined to a set of ephemeral practices that exist only so long as they are being enacted.
Mess among Disciplines: Interdisciplinarity in Environmental Research
Authors: Donaldson Andrew , Ward Neil , Bradley Sue
Published: July 2010

This paper discusses interdisciplinary collaboration between social and natural scientists from the perspective of ‘mess’. The literature on interdisciplinarity has generated a series of conventions about what it means to conduct interdisciplinary research. Building on the experience of a research project that brought social and natural scientists together with local residents to study flooding, we argue that interdisciplinarity can be understood as a response to mess, to the irreducibly complex problems of the world. Mess can be dealt with as an epistemological or ontological problem. We argue that discursive conventions focus on the epistemological dimensions of mess and thus have their limits. By considering the ontological dimensions of mess the whole range of objects that are involved in interdisciplinary research is brought into focus.
Spatiotemporal Evolution of Urban Form and Land-Use Structure in Hangzhou, China: Evidence from Fractals
Authors: Feng Jian , Chen Yanguang
Published: July 2010

Using fractal theory and urban land-use maps for 1949, 1959, 1980, and 1996, this study is devoted to analyzing the evolutionary features of urban form and land-use structure in Hangzhou, China. We find that self-similarity exists in both the built-up area and the municipal area, and fractal properties tend to become better defined with time. The fractal dimension of each type of land use is less than that of all land use. From 1980 to 1996, the fractal dimensions of residential, industrial, and external transport increased while those of educational and virescent land use decreased, indicating that partial degradation accompanied holistic optimization during the process of Hangzhou's self-organizing evolvement. The mechanisms of the spatiotemporal evolution of urban form in Hangzhou are discussed, including socioeconomic development and the dispersal or concentration of activities. The Tandabing approach to urban spatial expansion, the Jianfengchazhen approach to urban construction, and a top-down urban management style led to differences in fractal evolution between Chinese and Western cities.
Exogenous fms-like tyrosine kinase 3 ligand overrides brain immune privilege and facilitates recognition of a neo-antigen without causing autoimmune neuropathology
Authors: Larocque Daniel , Sanderson Nicholas S. R. , Bergeron Josée , Curtin James F. , Girton Joe , Wibowo Mia , Bondale Niyati , Kroeger Kurt M. , Yang Jieping , Lacayo Liliana M. , Reyes Kevin C. , Farrokhi Catherine , Pechnick Robert N. , Castro Maria G. , Lowenstein Pedro R.
Published: July 2010

Soluble antigens diffuse out of the brain and can thus stimulate a systemic immune response, whereas particulate antigens (from infectious agents or tumor cells) remain within brain tissue, thus failing to stimulate a systemic immune response. Immune privilege describes how the immune system responds to particulate antigens localized selectively within the brain parenchyma. We believe this immune privilege is caused by the absence of antigen presenting dendritic cells from the brain. We tested the prediction that expression of fms-like tyrosine kinase ligand 3 (Flt3L) in the brain will recruit dendritic cells and induce a systemic immune response against exogenous influenza hemagglutinin in BALB/c mice. Coexpression of Flt3L with HA in the brain parenchyma induced a robust systemic anti-HA immune response, and a small response against myelin basic protein and proteolipid protein epitopes. Depletion of CD4
+
CD25+ regulatory T cells (Tregs) enhanced both responses. To investigate the autoimmune impact of these immune responses, we characterized the neuropathological and behavioral consequences of intraparenchymal injections of Flt3L and HA in BALB/c and C57BL/6 mice. T cell infiltration in the forebrain was time and strain dependent, and increased in animals treated with Flt3L and depleted of Tregs; however, we failed to detect widespread defects in myelination throughout the forebrain or spinal cord. Results of behavioral tests were all normal. These results demonstrate that Flt3L overcomes the brain's immune privilege, and supports the clinical development of Flt3L as an adjuvant to stimulate clinically effective immune responses against brain neo-antigens, for example, those associated with brain tumors.
Paper surfaces and dynamical limits
Authors: de Carvalho André , Hall Toby
Published: July 2010

It is very common in mathematics to construct surfaces by identifying the sides of a polygon together in pairs: For example, identifying opposite sides of a square yields a torus. In this article the construction is considered in the case where infinitely many pairs of segments around the boundary of the polygon are identified. The topological, metric, and complex structures of the resulting surfaces are discussed: In particular, a condition is given under which the surface has a global complex structure (i.e., is a Riemann surface). In this case, a modulus of continuity for a uniformizing map is given. The motivation for considering this construction comes from dynamical systems theory: If the modulus of continuity is uniform across a family of such constructions, each with an iteration defined on it, then it is possible to take limits in the family and hence to complete it. Such an application is briefly discussed.
Deletion of
TDP-43
down-regulates
Tbc1d1
, a gene linked to obesity, and alters body fat metabolism
Authors: Chiang Po-Min , Ling Jonathan , Jeong Yun Ha , Price Donald L. , Aja Susan M. , Wong Philip C.
Published: July 2010

Tat activating regulatory DNA-binding protein (Tardbp or TDP-43), a highly conserved metazoan DNA/RNA binding protein thought to be involved in RNA transcription and splicing, has been linked to the pathophysiology of amyotrophic lateral sclerosis and frontotemporal lobar degeneration and is essential for early embryonic development. However, neither the physiological role of TDP-43 in the adult nor its downstream targets are well defined. To address these questions, we developed conditional
Tardbp
-KO mice and embryonic stem (ES) cell models. Here, we show that postnatal deletion of
Tardbp
in mice caused dramatic loss of body fat followed by rapid death. Moreover, conditional
Tardbp
-KO ES cells failed to proliferate. Importantly, high-throughput DNA sequencing analysis on the transcriptome of ES cells lacking
Tardbp
revealed a set of downstream targets of TDP-43. We show that
Tbc1d1
, a gene known to mediate leanness and linked to obesity, is down-regulated in the absence of TDP-43. Collectively, our results establish that TDP-43 is critical for fat metabolism and ES cell survival.
Biological markers of the effects of intravenous methylphenidate on improving inhibitory control in cocaine-dependent patients
Authors: Li Chiang-shan R. , Morgan Peter T. , Matuskey David , Abdelghany Osama , Luo Xi , Chang Jeremy L. K. , Rounsaville Bruce J. , Ding Yu-shin , Malison Robert T.
Published: July 2010

Prior research points to the importance of psychostimulants in improving self-control. However, the neural substrates underlying such improvement remain unclear. Here, in a pharmacological functional MRI study of the stop signal task, we show that methylphenidate (as compared with placebo) robustly decreased stop signal reaction time (SSRT), an index of improved control, in cocaine-dependent patients (a population in which inhibitory control is impaired). Methylphenidate-induced decreases in SSRT were positively correlated with inhibition-related activation of left middle frontal cortex (MFC) and negatively with activation of the ventromedial prefrontal cortex (vmPFC) in whole brain linear regressions. Inhibition-related MFC but not vmPFC activation distinguished individuals with short and long SSRT in 36 demographically matched healthy individuals, whereas vmPFC but not MFC activation, along with improvement in SSRT, was correlated with a previously implicated biomarker of methylphenidate response (systolic blood pressure). These results implicate a specific neural (i.e., vmPFC) mechanism whereby stimulants improve inhibitory control. Altered ventromedial prefrontal activation and increased blood pressure may represent useful CNS and peripheral biomarkers in individualized treatment with methylphenidate for patients with cocaine dependence.
Immune-related zinc finger gene ZFAT is an essential transcriptional regulator for hematopoietic differentiation in blood islands
Authors: Tsunoda Toshiyuki , Takashima Yasuo , Tanaka Yoko , Fujimoto Takahiro , Doi Keiko , Hirose Yumiko , Koyanagi Midori , Yoshida Yasuhiro , Okamura Tadashi , Kuroki Masahide , Sasazuki Takehiko , Shirasawa Senji
Published: July 2010

TAL1 plays pivotal roles in vascular and hematopoietic developments through the complex with LMO2 and GATA1. Hemangioblasts, which have a differentiation potential for both endothelial and hematopoietic lineages, arise in the primitive streak and migrate into the yolk sac to form blood islands, where primitive hematopoiesis occurs. ZFAT (a zinc-finger gene in autoimmune thyroid disease susceptibility region / an immune-related transcriptional regulator containing 18 C
2
H
2
-type zinc-finger domains and one AT-hook) was originally identified as an immune-related transcriptional regulator containing 18 C
2
H
2
-type zinc-finger domains and one AT-hook, and is highly conserved among species. ZFAT is thought to be a critical transcription factor involved in immune-regulation and apoptosis; however, developmental roles for ZFAT remain unknown. Here we show that
Zfat
-deficient (
Zfat
−/−
) mice are embryonic-lethal, with impaired differentiation of hematopoietic progenitor cells in blood islands, where ZFAT is exactly expressed. Expression levels of
Tal1
,
Lmo2
, and
Gata1
in
Zfat
−/−
yolk sacs are much reduced compared with those of wild-type mice, and ChIP-PCR analysis revealed that ZFAT binds promoter regions for these genes in vivo. Furthermore, profound reduction in TAL1, LMO2, and GATA1 protein expressions are observed in
Zfat
−/−
blood islands. Taken together, these results suggest that ZFAT is indispensable for mouse embryonic development and functions as a critical transcription factor for primitive hematopoiesis through direct-regulation of
Tal1
,
Lmo2
, and
Gata1.
Elucidation of ZFAT functions in hematopoiesis might lead to a better understanding of transcriptional networks in differentiation and cellular programs of hematopoietic lineage and provide useful information for applied medicine in stem cell therapy.
Linkages among climate change, crop yields and Mexico–US cross-border migration
Authors: Feng Shuaizhang , Krueger Alan B. , Oppenheimer Michael
Published: July 2010

Climate change is expected to cause mass human migration, including immigration across international borders. This study quantitatively examines the linkages among variations in climate, agricultural yields, and people's migration responses by using an instrumental variables approach. Our method allows us to identify the relationship between crop yields and migration without explicitly controlling for all other confounding factors. Using state-level data from Mexico, we find a significant effect of climate-driven changes in crop yields on the rate of emigration to the United States. The estimated semielasticity of emigration with respect to crop yields is approximately −0.2, i.e., a 10% reduction in crop yields would lead an additional 2% of the population to emigrate. We then use the estimated semielasticity to explore the potential magnitude of future emigration. Depending on the warming scenarios used and adaptation levels assumed, with other factors held constant, by approximately the year 2080, climate change is estimated to induce 1.4 to 6.7 million adult Mexicans (or 2% to 10% of the current population aged 15–65 y) to emigrate as a result of declines in agricultural productivity alone. Although the results cannot be mechanically extrapolated to other areas and time periods, our findings are significant from a global perspective given that many regions, especially developing countries, are expected to experience significant declines in agricultural yields as a result of projected warming.
Extra-large pore zeolite (ITQ-40) with the lowest framework density containing double four- and double three-rings
Authors: Corma A. , Díaz-Cabañas M. J. , Jiang J. , Afeworki M. , Dorset D. L. , Soled S. L. , Strohmaier K. G.
Published: July 2010

The first zeolite structure (ITQ-40) that contains double four (D4) and double three (D3) member ring secondary building units has been synthesized by introducing Ge and NH
4
F and working in concentrated synthesis gels. It is the first time that D3-Rs have been observed in a zeolite structure. As was previously analyzed [Brunner GO, Meier, WM (1989)
Nature
337:146–147], such a structure has a very low framework density (10.1 T/1,000 
Å
3
). Indeed, ITQ-40 has the lowest framework density ever achieved in oxygen-containing zeolites. Furthermore, it contains large pore openings, i.e., 15-member rings parallel to the [001] hexagonal axis and 16-member ring channels perpendicular to this axis. The results presented here push ahead the possibilities of zeolites for uses in electronics, control delivery of drugs and chemicals, as well as for catalysis.
Cardioprotection by a nonerythropoietic, tissue-protective peptide mimicking the 3D structure of erythropoietin
Authors: Ueba Hiroto , Brines Michael , Yamin Michael , Umemoto Tomio , Ako Junya , Momomura Shin-ichi , Cerami Anthony , Kawakami Masanobu
Published: July 2010

Erythropoietin (EPO), originally identified for its critical hormonal role in regulating production and survival of erythrocytes, is a member of the type 1 cytokine superfamily. Recent studies have shown that EPO has cytoprotective effects in a wide variety of tissues, including the heart, by preventing apoptosis. However, EPO also has undesirable effects, such as thrombogenesis. In the present study, we investigated whether a helix B-surface peptide (HBSP), a nonerythropoietic, tissue-protective peptide mimicking the 3D structure of erythropoietin, protects cardiomyocytes from apoptosis in vitro and in vivo. In cultured neonatal rat cardiomyocytes, HBSP clearly inhibited apoptosis (≈80%) induced by TNF-α, which was comparable with the effect of EPO, and activated critical signaling pathways of cell survival, including Akt, ERK1/2, and STAT3. Among these pathways, Akt was shown to play an essential role in HBSP-induced prevention of apoptosis, as assessed by using a small interfering RNA approach. In the dilated cardiomyopathic hamster (J2N-k), whose cardiac tissues diffusely expressed TNF-α, HBSP also inhibited apoptosis (≈70%) and activated Akt in cardiomyocytes. Furthermore, the levels of serum creatine kinase activity and of cardiac expression of atrial natriuretic peptide, a marker of chronic heart failure, were down-regulated in animals treated with HBSP. These data demonstrate that HBSP protects cardiomyocytes from apoptosis and leads to a favorable outcome in failing hearts through an Akt-dependent pathway. Because HBSP does not have the undesirable effects of EPO, it could be a promising alternative for EPO to treat cardiovascular diseases, such as myocardial infarction and heart failure.
Neurite beading is sufficient to decrease the apparent diffusion coefficient after ischemic stroke
Authors: Budde Matthew D. , Frank Joseph A.
Published: July 2010

Diffusion-weighted MRI (DWI) is a sensitive and reliable marker of cerebral ischemia. Within minutes of an ischemic event in the brain, the microscopic motion of water molecules measured with DWI, termed the apparent diffusion coefficient (ADC), decreases within the infarcted region. However, although the change is related to cell swelling, the precise pathological mechanism remains elusive. We show that focal enlargement and constriction, or beading, in axons and dendrites are sufficient to substantially decrease ADC. We first derived a biophysical model of neurite beading, and we show that the beaded morphology allows a larger volume to be encompassed within an equivalent surface area and is, therefore, a consequence of osmotic imbalance after ischemia. The DWI experiment simulated within the model revealed that intracellular ADC decreased by 79% in beaded neurites compared with the unbeaded form. To validate the model experimentally, excised rat sciatic nerves were subjected to stretching, which induced beading but did not cause a bulk shift of water into the axon (i.e., swelling). Beading-induced changes in cell-membrane morphology were sufficient to significantly hinder water mobility and thereby decrease ADC, and the experimental measurements were in excellent agreement with the simulated values. This is a demonstration that neurite beading accurately captures the diffusion changes measured in vivo. The results significantly advance the specificity of DWI in ischemia and other acute neurological injuries and will greatly aid the development of treatment strategies to monitor and repair damaged brain in both clinical and experimental settings.
Redox sensor SsrB Cys203enhancesSalmonellafitness against nitric oxide generated in the host immune response to oral infection
Authors: Husain Maroof , Jones-Carson Jessica , Song Miryoung , McCollister Bruce D. , Bourret Travis J. , Vázquez-Torres Andrés
Published: July 2010

We show herein that theSalmonellapathogenicity island 2 (SPI2) response regulator SsrB undergoes S-nitrosylation upon exposure ofSalmonellato acidified nitrite, a signal encountered by this enteropathogen in phagosomes of macrophages. Mutational analysis has identified Cys203in the C-terminal dimerization domain of SsrB as the redox-active residue responding to nitric oxide (NO) congeners generated in the acidification of nitrite. Peroxynitrite and products of the autooxidation of NO in the presence of oxygen, but not hydrogen peroxide, inhibit the DNA-binding capacity of SsrB, demonstrating the selectivity of the reaction of Cys203with reactive nitrogen species (RNS). These findings identify the two-component response regulator SsrB Cys203as a thiol-based redox sensor. A C203S substitution protects SsrB against the attack of RNS while preserving its DNA-binding capacity. When exposed to SPI2-inducing conditions,Salmonellaexpressing the wild-typessrBallele or thessrBC203S variant sustain transcription of thesifA,sspH2, andsrfJeffector genes. Nonetheless, compared with the strain expressing a redox-resistant SsrB C203S variant, wild-typeSalmonellabearing the NO-responsive allele exhibit increased fitness when exposed to RNS in an NRAMPR, C3H/HeN murine model of acute oral infection. Given the widespread occurrence of the wild-type allele inSalmonella enterica, these findings indicate that SsrB Cys203increasesSalmonellavirulence by serving as a redox sensor of NO resulting from the host immune response to oral infection.
Large volume collapse observed in the phase transition in cubic PbCrO
3
perovskite
Authors: Xiao Wansheng , Tan Dayong , Xiong Xiaolin , Liu Jing , Xu Jian
Published: July 2010

When cubic PbCrO
3
perovskite (Phase I) is squeezed up to ∼1.6 GPa at room temperature, a previously undetected phase (Phase II) has been observed with a 9.8% volume collapse. Because the structure of Phase II can also be indexed into a cubic perovskite as Phase I, the transition between Phases I and II is a cubic to cubic isostructural transition. Such a transition appears independent of the raw materials and synthesizing methods used for the cubic PbCrO
3
perovskite sample. In contrast to the high-pressure isostructural electronic transition that appears in Ce and SmS, this transition seems not related with any change of electronic state, but it could be possibly related on the abnormally large volume and compressibility of the PbCrO
3
Phase I. The physical mechanism behind this transition and the structural and electronic/magnetic properties of the condensed phases are the interesting issues for future studies.
Forest contraction in north equatorial Southeast Asia during the Last Glacial Period
Authors: Wurster Christopher M. , Bird Michael I. , Bull Ian D. , Creed Frances , Bryant Charlotte , Dungait Jennifer A. J. , Paz Victor
Published: July 2010

Today, insular Southeast Asia is important for both its remarkably rich biodiversity and globally significant roles in atmospheric and oceanic circulation. Despite the fundamental importance of environmental history for diversity and conservation, there is little primary evidence concerning the nature of vegetation in north equatorial Southeast Asia during the Last Glacial Period (LGP). As a result, even the general distribution of vegetation during the Last Glacial Maximum is debated. Here we show, using the stable carbon isotope composition of ancient cave guano profiles, that there was a substantial forest contraction during the LGP on both peninsular Malaysia and Palawan, while rainforest was maintained in northern Borneo. These results directly support rainforest “refugia” hypotheses and provide evidence that environmental barriers likely reduced genetic mixing between Borneo and Sumatra flora and fauna. Moreover, it sheds light on possible early human dispersal events.
Distinct class of DNA-binding domains is exemplified by a master regulator of phenotypic switching in
Candida albicans
Authors: Lohse Matthew B. , Zordan Rebecca E. , Cain Christopher W. , Johnson Alexander D.
Published: July 2010

Among the most important classes of regulatory proteins are the sequence-specific DNA-binding proteins that control transcription through the occupancy of discrete DNA sequences within genomes. Currently, this class of proteins encompasses at least 37 distinct structural superfamilies and more than 100 distinct structural motifs. In this paper, we examine the transcriptional regulator Wor1, a master regulator of white-opaque switching in the human fungal pathogen
Candida albicans
. As assessed by a variety of algorithms, this protein has no sequence or structural similarity to any known DNA-binding protein. It is, however, conserved across the vast fungal lineage, with a 300aa region of sequence conservation. Here, we show that this 300aa region of Wor1 exhibits sequence-specific DNA binding and therefore represents a new superfamily of DNA-binding proteins. We identify the 14-nucleotide-pair DNA sequence recognized by Wor1, characterize the site through mutational analysis, and demonstrate that this sequence is sufficient for the Wor1-dependent activation of transcription in vivo. Within the 300aa DNA-binding conserved region, which we have termed the WOPR box, are two domains (WOPRa and WOPRb), dissimilar to each other but especially well-conserved across the fungal lineage. We show that the WOPR box binds DNA as a monomer and that neither domain, when expressed and purified separately, exhibits sequence-specific binding. DNA binding is restored, however, when the two isolated domains are added together. These results indicate that the WOPR family of DNA-binding proteins involves an unusual coupling between two dissimilar, covalently linked domains.
Anthrax toxin-neutralizing antibody reconfigures the protective antigen heptamer into a supercomplex
Authors: Radjainia Mazdak , Hyun Jae-Kyung , Leysath Clinton E. , Leppla Stephen H. , Mitra Alok K.
Published: July 2010

The tripartite protein exotoxin secreted by
Bacillus anthracis
, a major contributor to its virulence and anthrax pathogenesis, consists of binary complexes of the protective antigen (PA) heptamer (PA63h), produced by proteolytic cleavage of PA, together with either lethal factor or edema factor. The mouse monoclonal anti-PA antibody 1G3 was previously shown to be a potent antidote that shares F
C
domain dependency with the human monoclonal antibody MDX-1303 currently under clinical development. Here we demonstrate that 1G3 instigates severe perturbation of the PA63h structure and creates a PA supercomplex as visualized by electron microscopy. This phenotype, produced by the unconventional mode of antibody action, highlights the feasibility for optimization of vaccines based on analogous structural modification of PA63h as an additional strategy for future remedies against anthrax.
Flexibly deployed
Pax
genes in eye development at the early evolution of animals demonstrated by studies on a hydrozoan jellyfish
Authors: Suga Hiroshi , Tschopp Patrick , Graziussi Daria F. , Stierwald Michael , Schmid Volker , Gehring Walter J.
Published: July 2010

Pax transcription factors are involved in a variety of developmental processes in bilaterians, including eye development, a role typically assigned to Pax-6. Although no true
Pax-6
gene has been found in nonbilateral animals, some jellyfish have eyes with complex structures. In the cubozoan jellyfish
Tripedalia
,
Pax-B
, an ortholog of vertebrate
Pax-2/5
/
8
, had been proposed as a regulator of eye development. Here we have isolated three
Pax
genes (
Pax-A
,
Pax-B
, and
Pax-E
) from
Cladonema radiatum
, a hydrozoan jellyfish with elaborate eyes.
Cladonema Pax-A
is strongly expressed in the retina, whereas
Pax-B
and
Pax-E
are highly expressed in the manubrium, the feeding and reproductive organ. Misexpression of
Cladonema Pax-A
induces ectopic eyes in
Drosophila
imaginal discs, whereas
Pax-B
and
Pax-E
do not. Furthermore,
Cladonema
Pax-A paired domain protein directly binds to the 5′ upstream region of eye-specific
Cladonema
opsin genes, whereas Pax-B does not. Our data suggest that
Pax-A
, but not
Pax-B
or
Pax-E
, is involved in eye development and/or maintenance in
Cladonema
. Phylogenetic analysis indicates that
Pax-6
,
Pax-B
, and
Pax-A
belong to different
Pax
subfamilies, which diverged at the latest before the Cnidaria–Bilateria separation. We argue that our data, showing the involvement of
Pax
genes in hydrozoan eye development as in bilaterians, supports the monophyletic evolutionary origin of all animal eyes. We then propose that during the early evolution of animals, distinct classes of
Pax
genes, which may have played redundant roles at that time, were flexibly deployed for eye development in different animal lineages.
Telomerase-immortalized human mammary stem/progenitor cells with ability to self-renew and differentiate
Authors: Zhao Xiangshan , Malhotra Gautam K. , Lele Subodh M. , Lele Manjiri S. , West William W. , Eudy James D. , Band Hamid , Band Vimla
Published: July 2010

There is increasing evidence that breast and other cancers originate from and are maintained by a small fraction of stem/progenitor cells with self-renewal properties. Whether such cancer stem/progenitor cells originate from normal stem cells based on initiation of a de novo stem cell program, by reprogramming of a more differentiated cell type by oncogenic insults, or both remains unresolved. A major hurdle in addressing these issues is lack of immortal human stem/progenitor cells that can be deliberately manipulated in vitro. We present evidence that normal and human telomerase reverse transcriptase (hTERT)-immortalized human mammary epithelial cells (hMECs) isolated and maintained in Dana-Farber Cancer Institute 1 (DFCI-1) medium retain a fraction with progenitor cell properties. These cells coexpress basal (K5, K14, and vimentin), luminal (E-cadherin, K8, K18, or K19), and stem/progenitor (CD49f, CD29, CD44, and p63) cell markers. Clonal derivatives of progenitors coexpressing these markers fall into two distinct types—a K5
+
/K19
−
type and a K5
+
/K19
+
type. We show that both types of progenitor cells have self-renewal and differentiation ability. Microarray analyses confirmed the differential expression of components of stem/progenitor-associated pathways, such as Notch, Wnt, Hedgehog, and LIF, in progenitor cells compared with differentiated cells. Given the emerging evidence that stem/progenitor cells serve as precursors for cancers, these cellular reagents represent a timely and invaluable resource to explore unresolved questions related to stem/progenitor origin of breast cancer.
Bothrops snake myotoxins induce a large efflux of ATP and potassium with spreading of cell damage and pain
Authors: Cintra-Francischinelli Mariana , Caccin Paola , Chiavegato Angela , Pizzo Paola , Carmignoto Giorgio , Angulo Yamileth , Lomonte Bruno , Gutiérrez José María , Montecucco Cesare
Published: July 2010

Myotoxins play a major role in the pathogenesis of the envenomations caused by snake bites in large parts of the world where this is a very relevant public health problem. We show here that two myotoxins that are major constituents of the venom of
Bothrops asper
, a deadly snake present in Latin America, induce the release of large amounts of K
+
and ATP from skeletal muscle. We also show that the released ATP amplifies the effect of the myotoxins, acting as a “danger signal,” which spreads and causes further damage by acting on purinergic receptors. In addition, the release of ATP and K
+
well accounts for the pain reaction characteristic of these envenomations. As
Bothrops asper
myotoxins are representative of a large family of snake myotoxins with phospholipase A
2
structure, these findings are expected to be of general significance for snake bite envenomation. Moreover, they suggest potential therapeutic approaches for limiting the extent of muscle tissue damage based on antipurinergic drugs.
Receptor tyrosine kinase-like orphan receptor 2 (ROR2) and Indian hedgehog regulate digit outgrowth mediated by the phalanx-forming region
Authors: Witte Florian , Chan Danny , Economides Aris N. , Mundlos Stefan , Stricker Sigmar
Published: July 2010

Elongation of the digit rays resulting in the formation of a defined number of phalanges is a process poorly understood in mammals, whereas in the chicken distal mesenchymal bone morphogenetic protein (BMP) signaling in the so-called phalanx-forming region (PFR) or digit crescent (DC) seems to be involved. The human brachydactylies (BDs) are inheritable conditions characterized by variable degrees of digit shortening, thus providing an ideal model to analyze the development and elongation of phalanges. We used a mouse model for BDB1 (

Ror2
W749X/W749X

) lacking middle phalanges and show that a signaling center corresponding to the chick PFR exists in the mouse, which is diminished in BDB1 mice. This resulted in a strongly impaired elongation of the digit condensations due to reduced chondrogenic commitment of undifferentiated distal mesenchymal cells. We further show that a similar BMP-based mechanism accounts for digit shortening in a mouse model for the closely related condition BDA1 (

Ihh
E95K/E95K

), altogether indicating the functional significance of the PFR in mammals. Genetic interaction experiments as well as pathway analysis in BDB1 mice suggest that Indian hedgehog and WNT/β-catenin signaling, which we show is inhibited by receptor tyrosine kinase-like orphan receptor 2 (ROR2) in distal limb mesenchyme, are acting upstream of BMP signaling in the PFR.
Roles of epithelial cell-derived periostin in TGF-β activation, collagen production, and collagen gel elasticity in asthma
Authors: Sidhu Sukhvinder S. , Yuan Shaopeng , Innes Anh L. , Kerr Sheena , Woodruff Prescott G. , Hou Lydia , Muller Susan J. , Fahy John V.
Published: July 2010

Periostin is considered to be a matricellular protein with expression typically confined to cells of mesenchymal origin. Here, by using in situ hybridization, we show that periostin is specifically up-regulated in bronchial epithelial cells of asthmatic subjects, and in vitro, we show that periostin protein is basally secreted by airway epithelial cells in response to IL-13 to influence epithelial cell function, epithelial–mesenchymal interactions, and extracellular matrix organization. In primary human bronchial epithelial cells stimulated with periostin and epithelial cells overexpressing periostin, we reveal a function for periostin in stimulating the TGF-β signaling pathway in a mechanism involving matrix metalloproteinases 2 and 9. Furthermore, conditioned medium from the epithelial cells overexpressing periostin caused TGF-β–dependent secretion of type 1 collagen by airway fibroblasts. In addition, mixing recombinant periostin with type 1 collagen in solution caused a dramatic increase in the elastic modulus of the collagen gel, indicating that periostin alters collagen fibrillogenesis or cross-linking and leads to stiffening of the matrix. Epithelial cell-derived periostin in asthma has roles in TGF-β activation and collagen gel elasticity in asthma.