bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorylation of inositol 1,4,5-trisphosphate receptors by protein kinase B/Akt inhibits Ca
2+
release and apoptosis
Authors: Szado Tania , Vanderheyden Veerle , Parys Jan B. , De Smedt Humbert , Rietdorf Katja , Kotelevets Larissa , Chastre Eric , Khan Farid , Landegren Ulf , Söderberg Ola , Bootman Martin D. , Roderick H. Llewelyn
Published: February 2008

Imbalance of signals that control cell survival and death results in pathologies, including cancer and neurodegeneration. Two pathways that are integral to setting the balance between cell survival and cell death are controlled by lipid-activated protein kinase B (PKB)/Akt and Ca
2+
. PKB elicits its effects through the phosphorylation and inactivation of proapoptotic factors. Ca
2+
stimulates many prodeath pathways, among which is mitochondrial permeability transition. We identified Ca
2+
release through inositol 1,4,5-trisphosphate receptor (InsP
3
R) intracellular channels as a prosurvival target of PKB. We demonstrated that in response to survival signals, PKB interacts with and phosphorylates InsP
3
Rs, significantly reducing their Ca
2+
release activity. Moreover, phosphorylation of InsP
3
Rs by PKB reduced cellular sensitivity to apoptotic stimuli through a mechanism that involved diminished Ca
2+
flux from the endoplasmic reticulum to the mitochondria. In glioblastoma cells that exhibit hyperactive PKB, the same prosurvival effect of PKB on InsP
3
R was found to be responsible for the insensitivity of these cells to apoptotic stimuli. We propose that PKB-mediated abolition of InsP
3
-induced Ca
2+
release may afford tumor cells a survival advantage.
Resetting of
FLOWERING LOCUS C
expression after epigenetic repression by vernalization
Authors: Sheldon Candice C. , Hills Melissa J. , Lister Clare , Dean Caroline , Dennis Elizabeth S. , Peacock W. James
Published: February 2008

The epigenetic repression of
FLOWERING LOCUS C
(
FLC
) in winter-annual ecotypes of
Arabidopsis
by prolonged cold ensures that plants flower in spring and not during winter. Resetting of the
FLC
expression level in progeny is an important step in the life cycle of the plant. We show that both the paternally derived and the maternally derived
FLC
:
GUS
genes are reset to activity but that the timing of their first expression differs. The paternal
FLC
:
GUS
gene in vernalized plants is expressed in the male reproductive organs, the anthers, in both somatic tissue and in the sporogenous pollen mother cells, but there is no expression in mature pollen. In the progeny generation, the paternally derived
FLC
:
GUS
gene is expressed in the single-celled zygote (fertilized egg cell) and through embryo development, but not in the fertilized central cell, which generates the endosperm of the progeny seed.
FLC
:
GUS
is not expressed during female gametogenesis, with the maternally derived
FLC
:
GUS
being first expressed in the early multicellular embryo. We show that
FLC
activity during late embryo development is a prerequisite for the repressive action of
FLC
on flowering.
Gene expression dynamics in the macrophage exhibit criticality
Authors: Nykter Matti , Price Nathan D. , Aldana Maximino , Ramsey Stephen A. , Kauffman Stuart A. , Hood Leroy E. , Yli-Harja Olli , Shmulevich Ilya
Published: February 2008

Cells are dynamical systems of biomolecular interactions that process information from their environment to mount diverse yet specific responses. A key property of many self-organized systems is that of criticality: a state of a system in which, on average, perturbations are neither dampened nor amplified, but are propagated over long temporal or spatial scales. Criticality enables the coordination of complex macroscopic behaviors that strike an optimal balance between stability and adaptability. It has long been hypothesized that biological systems are critical. Here, we address this hypothesis experimentally for system-wide gene expression dynamics in the macrophage. To this end, we have developed a method, based on algorithmic information theory, to assess macrophage criticality, and we have validated the method on networks with known properties. Using global gene expression data from macrophages stimulated with a variety of Toll-like receptor agonists, we found that macrophage dynamics are indeed critical, providing the most compelling evidence to date for this general principle of dynamics in biological systems.
Bcl-x
L
induces Drp1-dependent synapse formation in cultured hippocampal neurons
Authors: Li Hongmei , Chen Yingbei , Jones Adrienne F. , Sanger Richard H. , Collis Leon P. , Flannery Richard , McNay Ewan C. , Yu Tingxi , Schwarzenbacher Robert , Bossy Blaise , Bossy-Wetzel Ella , Bennett Michael V. L. , Pypaert Marc , Hickman John A. , Smith Peter J. S. , Hardwick J. Marie , Jonas Elizabeth A.
Published: February 2008

Maturation of neuronal synapses is thought to involve mitochondria. Bcl-x
L
protein inhibits mitochondria-mediated apoptosis but may have other functions in healthy adult neurons in which Bcl-x
L
is abundant. Here, we report that overexpression of Bcl-x
L
postsynaptically increases frequency and amplitude of spontaneous miniature synaptic currents in rat hippocampal neurons in culture. Bcl-x
L
, overexpressed either pre or postsynaptically, increases synapse number, the number and size of synaptic vesicle clusters, and mitochondrial localization to vesicle clusters and synapses, likely accounting for the changes in miniature synaptic currents. Conversely, knockdown of Bcl-x
L
or inhibiting it with ABT-737 decreases these morphological parameters. The mitochondrial fission protein, dynamin-related protein 1 (Drp1), is a GTPase known to localize to synapses and affect synaptic function and structure. The effects of Bcl-x
L
appear mediated through Drp1 because overexpression of Drp1 increases synaptic markers, and overexpression of the dominant-negative dnDrp1-K38A decreases them. Furthermore, Bcl-x
L
coimmunoprecipitates with Drp1 in tissue lysates, and in a recombinant system, Bcl-x
L
protein stimulates GTPase activity of Drp1. These findings suggest that Bcl-x
L
positively regulates Drp1 to alter mitochondrial function in a manner that stimulates synapse formation.
Crystal structure of the extracellular cholinesterase-like domain from neuroligin-2
Authors: Koehnke Jesko , Jin Xiangshu , Budreck Elaine C. , Posy Shoshana , Scheiffele Peter , Honig Barry , Shapiro Lawrence
Published: February 2008

Neuroligins (NLs) are catalytically inactive members of a family of cholinesterase-like transmembrane proteins that mediate cell adhesion at neuronal synapses. Postsynaptic neuroligins engage in Ca
2+
-dependent transsynaptic interactions via their extracellular cholinesterase domain with presynaptic neurexins (NRXs). These interactions may be regulated by two short splice insertions (termed A and B) in the NL cholinesterase domain. Here, we present the 3.3-Å crystal structure of the ectodomain from NL2 containing splice insertion A (NL2A). The overall structure of NL2A resembles that of cholinesterases, but several structural features are unique to the NL proteins. First, structural elements surrounding the esterase active-site region differ significantly between active esterases and NL2A. On the opposite surface of the NL2A molecule, the positions of the A and B splice insertions identify a candidate NRX interaction site of the NL protein. Finally, sequence comparisons of NL isoforms allow for mapping the location of residues of previously identified mutations in NL3 and NL4 found in patients with autism spectrum disorders. Overall, the NL2 structure promises to provide a valuable model for dissecting NL isoform- and synapse-specific functions.
Influence of ocean winds on the pelagic ecosystem in upwelling regions
Authors: Rykaczewski Ryan R. , Checkley David M.
Published: February 2008

Upwelling of nutrient-rich, subsurface water sustains high productivity in the ocean's eastern boundary currents. These ecosystems support a rate of fish harvest nearly 100 times the global mean and account for >20% of the world's marine fish catch. Environmental variability is thought to be the major cause of the decadal-scale biomass fluctuations characteristic of fish populations in these regions, but the mechanisms relating atmospheric physics to fish production remain unexplained. Two atmospheric conditions induce different types of upwelling in these ecosystems: coastal, alongshore wind stress, resulting in rapid upwelling (with high vertical velocity,
w
); and wind-stress curl, resulting in slower upwelling (low
w
). We show that the level of wind-stress curl has increased and that production of Pacific sardine (
Sardinops sagax
) varies with wind-stress curl over the past six decades. The extent of isopycnal shoaling, nutricline depth, and chlorophyll concentration in the upper ocean also correlate positively with wind-stress curl. The size structure of plankton assemblages is related to the rate of wind-forced upwelling, and sardine feed efficiently on small plankters generated by slow upwelling. Upwelling rate is a fundamental determinant of the biological structure and production in coastal pelagic ecosystems, and future changes in the magnitude and spatial gradient of wind stress may have important and differing effects on these ecosystems. Understanding of the biological mechanisms relating fisheries production to environmental variability is essential for wise management of marine resources under a changing climate.
Cytoplasmic BK
Ca
channel intron-containing mRNAs contribute to the intrinsic excitability of hippocampal neurons
Authors: Bell Thomas J. , Miyashiro Kevin Y. , Sul Jai-Yoon , McCullough Ronald , Buckley Peter T. , Jochems Jeanine , Meaney David F. , Haydon Phil , Cantor Charles , Parsons Thomas D. , Eberwine James
Published: February 2008

High single-channel conductance K
+
channels, which respond jointly to membrane depolarization and micromolar concentrations of intracellular Ca
2+
ions, arise from extensive cell-specific alternative splicing of pore-forming α-subunit mRNAs. Here, we report the discovery of an endogenous BK
Ca
channel α-subunit intron-containing mRNA in the cytoplasm of hippocampal neurons. This partially processed mRNA, which comprises ≈10% of the total BK
Ca
channel α-subunit mRNAs, is distributed in a gradient throughout the somatodendritic space. We selectively reduced endogenous cytoplasmic levels of this intron-containing transcript by RNA interference without altering levels of the mature splice forms of the BK
Ca
channel mRNAs. In doing so, we could demonstrate that changes in a unique BK
Ca
channel α-subunit intron-containing splice variant mRNA can greatly impact the distribution of the BK
Ca
channel protein to dendritic spines and intrinsic firing properties of hippocampal neurons. These data suggest a new regulatory mechanism for modulating the membrane properties and ion channel gradients of hippocampal neurons.
Gain-of-function mutation of
GATA-2
in acute myeloid transformation of chronic myeloid leukemia
Authors: Zhang Su-Jiang , Ma Li-Yuan , Huang Qiu-Hua , Li Guo , Gu Bai-Wei , Gao Xiao-Dong , Shi Jing-Yi , Wang Yue-Ying , Gao Li , Cai Xun , Ren Rui-Bao , Zhu Jiang , Chen Zhu , Chen Sai-Juan
Published: February 2008

Acquisition of additional genetic and/or epigenetic abnormalities other than the
BCR
/
ABL
fusion gene is believed to cause disease progression in chronic myeloid leukemia (CML) from chronic phase to blast crisis (BC). To gain insights into the underlying mechanisms of progression to BC, we screened DNA samples from CML patients during blast transformation for mutations in a number of transcription factor genes that are critical for myeloid–lymphoid development. In 85 cases of CML blast transformation, we identified two new mutations in the coding region of
GATA-2
, a negative regulator of hematopoietic stem/progenitor cell differentiation. A L359V substitution within zinc finger domain (ZF) 2 of
GATA-2
was found in eight cases with myelomonoblastic features, whereas an in-frame deletion of 6 aa (Δ341–346) spanning the C-terminal border of ZF1 was detected in one patient at myeloid BC with eosinophilia. Further studies indicated that L359V not only increased transactivation activity of GATA-2 but also enhanced its inhibitory effects on the activity of PU.1, a major regulator of myelopoiesis. Consistent with the myelomonoblastic features of CML transformation with the
GATA-2
L359V mutant, transduction of the
GATA-2
L359V mutant into HL-60 cells or
BCR
/
ABL
-harboring murine cells disturbed myelomonocytic differentiation/proliferation
in vitro
and
in vivo
, respectively. These data strongly suggest that
GATA-2
mutations may play a role in acute myeloid transformation in a subset of CML patients.
TASK channel deletion in mice causes primary hyperaldosteronism
Authors: Davies Lucinda A. , Hu Changlong , Guagliardo Nick A. , Sen Neil , Chen Xiangdong , Talley Edmund M. , Carey Robert M. , Bayliss Douglas A. , Barrett Paula Q.
Published: February 2008

When inappropriate for salt status, the mineralocorticoid aldosterone induces cardiac and renal injury. Autonomous overproduction of aldosterone from the adrenal zona glomerulosa (ZG) is also the most frequent cause of secondary hypertension. Yet, the etiology of nontumorigenic primary hyperaldosteronism caused by bilateral idiopathic hyperaldosteronism remains unknown. Here, we show that genetic deletion of TWIK-related acid-sensitive K (TASK)-1 and TASK-3 channels removes an important background K current that results in a marked depolarization of ZG cell membrane potential. Although TASK channel deletion mice (TASK
−/−
) adjust urinary Na excretion and aldosterone production to match Na intake, they produce more aldosterone than control mice across the range of Na intake. Overproduction of aldosterone is not the result of enhanced activity of the renin–angiotensin system because circulating renin concentrations remain either unchanged or lower than those of control mice at each level of Na intake. In addition, TASK
−/−
mice fail to suppress aldosterone production in response to dietary Na loading. Autonomous aldosterone production is also demonstrated by the failure of an angiotensin type 1 receptor blocker, candesartan, to normalize aldosterone production to control levels in TASK
−/−
mice. Thus, TASK
−/−
channel knockout mice exhibit the hallmarks of primary hyperaldosteronism. Our studies establish an animal model of nontumorigenic primary hyperaldosteronism and identify TASK channels as a possible therapeutic target for primary hyperaldosteronism.
Natural glucocorticoids induce expansion of all developmental stages of murine bone marrow granulocytes without inhibiting function
Authors: Trottier Mark D. , Newsted Matthew M. , King Louis E. , Fraker Pamela J.
Published: February 2008

Natural glucocorticoids (Gc) produced during stress have profound effects on the immune system. It is well known that Gc induce apoptosis in precursor T and B cells, markedly altering lymphopoiesis. However, it has been noted that marrow myeloid cells expanded both in proportion and absolute numbers in the mouse after Gc exposure. Mice were implanted with a corticosterone (CS) tablet that increased serum Gc and caused atrophied thymuses, both classic signs of activation of the stress axis. Blood neutrophil counts were elevated (4.8×), whereas lymphocyte counts declined. Flow cytometric analysis of the marrow revealed that the phenotypic distribution of the various major classes of cells was shifted by Gc exposure. As expected, marrow lymphocyte numbers declined >40% after 3 days of exposure to Gc. Conversely, in the myeloid compartment, both monocytes and granulocytes increased in number by >40%. Further, all granulocyte developmental stages showed large increases in both total number and percentage of cells. To investigate the functional capacity of mature granulocytes from Gc-treated mice, an improved granulocyte isolation method was developed. Gc exposure had little effect on the ability of granulocytes to produce superoxide or undergo chemotaxis or phagocytose bacteria. These results indicate that Gc treatment shifts bone marrow composition and provides evidence that granulocytes and their progenitors are selectively preserved under stressful conditions without losing function.
Normal development is an integral part of tumorigenesis in T cell-specific PTEN-deficient mice
Authors: Xue Ling , Nolla Hector , Suzuki Akira , Mak Tak W. , Winoto Astar
Published: February 2008

PTENis a tumor suppressor gene but whether cancer can develop in all PTEN-deficient cells is not known. In T cell-specific PTEN-deficient (tPTEN−/−) mice, which suffer from mature T cell lymphomas, we found that premalignancy, as defined by elevated AKT and senescence pathways, starts in immature T cell precursors and surprisingly not in mature T cells. Premalignancy only starts in 6-week-old mice and becomes much stronger in 9-week-old mice although PTEN is lost since birth. tPTEN−/−immature T cells do not become tumors, and senescence has no role in this model because these cells exist in a novel cell cycle state, expressing proliferating proteins but not proliferating to any significant degree. Instead, the levels of p27kip1, which is lower in tPTEN−/−immature T cells and almost nonexistent in tPTEN−/−mature T cells, correlate with the proliferation capability of these cells. Interestingly, transient reduction of these cancer precursor cells in adult tPTEN−/−mice within a crucial time window significantly delayed lymphomas and mouse lethality. Thus, loss of PTEN alone is not sufficient for cells to become cancerous, therefore other developmental events are necessary for tumor formation.
Role for Plk1 phosphorylation of Hbo1 in regulation of replication licensing
Authors: Wu Zhao-Qiu , Liu Xiaoqi
Published: February 2008

In a search for Polo-like kinase 1 (Plk1)-interacting proteins using a yeast two-hybrid system, we have identified histone acetyltransferase binding to the origin recognition complex 1 (Hbo1) as a potential Plk1 target. Here, we show that the interaction between Plk1 and Hbo1 is mitosis-specific and that Plk1 phosphorylates Hbo1 on Ser-57
in vitro
and
in vivo
. During mitosis, Cdk1 phosphorylates Hbo1 on Thr-85/88, creating a docking site for Plk1 to be recruited. Significantly, the overexpression of Hbo1 mutated at the Plk1 phosphorylation site (S57A) leads to cell-cycle arrest in the G
1
/S phase, inhibition of chromatin loading of the minichromosome maintenance (Mcm) complex, and a reduced DNA replication rate. Similarly, Hbo1 depletion results in decreased DNA replication and a failure of Mcm complex binding to chromatin, both of which can be partially rescued by the ectopic expression of WT Hbo1 but not Hbo1-S57A. These results suggest that Plk1 phosphorylation of Hbo1 may be required for prereplicative complex (pre-RC) formation and DNA replication licensing.
IL-33 mediates antigen-induced cutaneous and articular hypernociception in mice
Authors: Verri Waldiceu A. , Guerrero Ana T. G. , Fukada Sandra Y. , Valerio Daniel A. , Cunha Thiago M. , Xu Damo , Ferreira Sérgio H. , Liew Foo Y. , Cunha Fernando Q.
Published: February 2008

IL-33, a new member of the IL-1 family, signals through its receptor ST2 and induces T helper 2 (Th2) cytokine synthesis and mediates inflammatory response. We have investigated the role of IL-33 in antigen-induced hypernociception. Recombinant IL-33 induced cutaneous and articular mechanical hypernociception in a time- and dose-dependent manner. The hypernociception was inhibited by soluble (s) ST2 (a decoy receptor of IL-33), IL-1 receptor antagonist (IL-1ra), bosentan [a dual endothelin (ET)A/ETBreceptor antagonist], clazosentan (an ETAreceptor antagonist), or indomethacin (a cyclooxygenase inhibitor). IL-33 induced hypernociception in IL-18−/−mice but not in TNFR1−/−or IFNγ−/−mice. The IL-33-induced hypernociception was not affected by blocking IL-15 or sympathetic amines (guanethidine). Furthermore, methylated BSA (mBSA)-induced cutaneous and articular mechanical hypernociception depended on TNFR1 and IFNγ and was blocked by sST2, IL-1ra, bosentan, clazosentan, and indomethacin. mBSA also induced significant IL-33 and ST2 mRNA expression. Importantly, we showed that mBSA induced hypernociception via the IL-33 → TNFα → IL-1β → IFNγ → ET-1 → PGE2signaling cascade. These results therefore demonstrate that IL-33 is a key mediator of immune inflammatory hypernociception normally associated with a Th1 type of response, revealing a hitherto unrecognized function of IL-33 in a key immune pharmacological pathway that may be amenable to therapeutic intervention.
Cell- and stimulus-dependent heterogeneity of synaptic vesicle endocytic recycling mechanisms revealed by studies of dynamin 1-null neurons
Authors: Hayashi Mitsuko , Raimondi Andrea , O'Toole Eileen , Paradise Summer , Collesi Chiara , Cremona Ottavio , Ferguson Shawn M. , De Camilli Pietro
Published: February 2008

Mice lacking expression of dynamin 1, a GTPase implicated in the fission reaction of synaptic vesicle endocytosis, fail to thrive and exhibit severe activity-dependent endocytic defects at their synapses. Here, we have used electron tomography to investigate the massive increase in clathrin-coated pit abundance that is selectively observed at a subset of synapses in dynamin 1 KO primary neuron cultures under conditions of spontaneous network activity. This increase, leading to branched tubular plasma membrane invaginations capped by clathrin-coated buds, occurs selectively at inhibitory synapses. A similar massive increase of clathrin-coated profiles (in this case, of clathrin-coated vesicles) is observed at inhibitory synapses of neurons that lack expression of synaptojanin 1, a phosphoinositide phosphatase involved in clathrin-coated vesicle uncoating. Thus, although excitatory synapses are largely spared under these conditions, inhibitory synapses are uniquely sensitive to perturbation of endocytic proteins, probably as a result of their higher levels of tonic activity leading to a buildup of clathrin-coated intermediates in these synapses. In contrast, the predominant endocytic structures observed at the majority of dynamin 1 KO synapses after acute stimulation are endosome-like intermediates that originate by a dynamin 1-independent form of endocytosis. These findings reveal a striking heterogeneity in the mode of synaptic vesicle recycling in different synapses and functional states.
Patriotism in the News: “Rally Round the Flag”
Authors: Barnett Brooke , Roselle Laura
Published: February 2008

In the United States, journalists learn the importance of objectivity, fairness, and independence. However, these values are often undermined, especially in times of crisis. Following the September 11 attacks, the media responded with a particularly patriotic slant to their reporting. Television news was marked by news reporters wearing flag pins; flag images; and red, white, and blue patriotic banners. An experiment using patriotic and neutral news stories shows that, generally, viewers of patriotic images didn't report that patriotic news stories were less fair, sensational, biased, accurate, important, newsworthy, or balanced. There were exceptions, however, as Democrats and liberals perceived the anchor to be less objective in one patriotic news story (about terrorism). Although viewers (as a whole) of patriotic news didn't think these stories adhered less to journalistic norms, some groups were affected by the patriotic news in one important way. Certain groups who viewed the patriotic news stories were significantly less likely to be afraid of future terrorist attacks than those who watched the neutral stories. The results of this experiment suggest that Americans are comfortable with the flag and other patriotic images enmeshed in their news broadcasts and that, for some, these images lessen the fear of a future terrorist attack.
The Effects of Audiences' Ideological Views on the Customer-Based Brand Equity of Cable News Networks
Authors: Oyedeji Tayo
Published: February 2008

This study explores the effects of audience members' ideological views on their perceptions of the customer-based brand equity (CBBE) of cable news networks. Aaker's (1991) and Keller's (2002) conceptualizations of CBBE were used to create a brand equity measure while respondents' attitudes toward contentious policy issues and political personalities were used to create an ideology index on the liberal-conservative continuum. Respondents' ideological views didn't affect their perceptions of the CBBE of CNN and MSNBC. In contrast, ideology had significant effects on audience perceptions of the CBBE of Fox News Channel.
The Canadian News Directors Study: Role Conceptions of Television Newsroom Decision Makers
Authors: Barber Marsha , Rauhala Ann
Published: February 2008

This is the second in a series of academic studies investigating the men and women who make key editorial decisions in television newsrooms across Canada. The researchers surveyed television news directors to investigate how they understand the journalistic roles of the reporters who work for them. This research suggests there are differences between news directors in public and private broadcasting. It also suggests that in both public and private broadcasting, news directors' attitudes about roles journalists should play differ somewhat from those of the journalists who work for them.
Visualization of a proteasome-independent intermediate during restriction of HIV-1 by rhesus TRIM5α
Authors: Campbell Edward M. , Perez Omar , Anderson Jenny L. , Hope Thomas J.
Published: February 2008

TRIM5 proteins constitute a class of restriction factors that prevent host cell infection by retroviruses from different species. TRIM5α restricts retroviral infection early after viral entry, before the generation of viral reverse transcription products. However, the underlying restriction mechanism remains unclear. In this study, we show that during rhesus macaque TRIM5α (rhTRIM5α)–mediated restriction of HIV-1 infection, cytoplasmic HIV-1 viral complexes can associate with concentrations of TRIM5α protein termed cytoplasmic bodies. We observe a dynamic interaction between rhTRIM5α and cytoplasmic HIV-1 viral complexes, including the de novo formation of rhTRIM5α cytoplasmic body–like structures around viral complexes. We observe that proteasome inhibition allows HIV-1 to remain stably sequestered into large rhTRIM5α cytoplasmic bodies, preventing the clearance of HIV-1 viral complexes from the cytoplasm and revealing an intermediate in the restriction process. Furthermore, we can measure no loss of capsid protein from viral complexes arrested at this intermediate step in restriction, suggesting that any rhTRIM5α-mediated loss of capsid protein requires proteasome activity.
CAPS and syntaxin dock dense core vesicles to the plasma membrane in neurons
Authors: Hammarlund Marc , Watanabe Shigeki , Schuske Kim , Jorgensen Erik M.
Published: February 2008

Docking to the plasma membrane prepares vesicles for rapid release. Here, we describe a mechanism for dense core vesicle docking in neurons. In Caenorhabditis elegans motor neurons, dense core vesicles dock at the plasma membrane but are excluded from active zones at synapses. We have found that the calcium-activated protein for secretion (CAPS) protein is required for dense core vesicle docking but not synaptic vesicle docking. In contrast, we see that UNC-13, a docking factor for synaptic vesicles, is not essential for dense core vesicle docking. Both the CAPS and UNC-13 docking pathways converge on syntaxin, a component of the SNARE (soluble N-ethyl-maleimide–sensitive fusion protein attachment receptor) complex. Overexpression of open syntaxin can bypass the requirement for CAPS in dense core vesicle docking. Thus, CAPS likely promotes the open state of syntaxin, which then docks dense core vesicles. CAPS function in dense core vesicle docking parallels UNC-13 in synaptic vesicle docking, which suggests that these related proteins act similarly to promote docking of independent vesicle populations.
Caspase-14 reveals its secrets
Authors: Denecker Geertrui , Ovaere Petra , Vandenabeele Peter , Declercq Wim
Published: February 2008

Caspase-14 is a unique member of the evolutionarily conserved family of cysteinyl aspartate–specific proteinases, which are mainly involved in inflammation and apoptosis. However, recent evidence also implicates these proteases in proliferation and differentiation. Although most caspases are ubiquitously expressed, caspase-14 expression is confined mainly to cornifying epithelia, such as the skin. Moreover, caspase-14 activation correlates with cornification, indicating that it plays a role in terminal keratinocyte differentiation. The determination of in vitro conditions for caspase-14 activity paved the way to identifying its substrates. The recent development of caspase-14–deficient mice underscored its importance in the correct degradation of (pro)filaggrin and in the formation of the epidermal barrier that protects against dehydration and UVB radiation. Here, we review the current knowledge on caspase-14 in skin homeostasis and disease.
Mutations inHydinimpair ciliary motility in mice
Authors: Lechtreck Karl-Ferdinand , Delmotte Philippe , Robinson Michael L. , Sanderson Michael J. , Witman George B.
Published: February 2008

Chlamydomonas reinhardtii hydin is a central pair protein required for flagellar motility, and mice with Hydin defects develop lethal hydrocephalus. To determine if defects in Hydin cause hydrocephalus through a mechanism involving cilia, we compared the morphology, ultrastructure, and activity of cilia in wild-type and hydin mutant mice strains. The length and density of cilia in the brains of mutant animals is normal. The ciliary axoneme is normal with respect to the 9 + 2 microtubules, dynein arms, and radial spokes but one of the two central microtubules lacks a specific projection. The hydin mutant cilia are unable to bend normally, ciliary beat frequency is reduced, and the cilia tend to stall. As a result, these cilia are incapable of generating fluid flow. Similar defects are observed for cilia in trachea. We conclude that hydrocephalus in hydin mutants is caused by a central pair defect impairing ciliary motility and fluid transport in the brain.
Increased endothelial expression of Toll-like receptor 2 at sites of disturbed blood flow exacerbates early atherogenic events
Authors: Mullick Adam E. , Soldau Katrin , Kiosses William B. , Bell Thomas A. , Tobias Peter S. , Curtiss Linda K.
Published: February 2008

Toll-like receptors (TLRs) are pattern recognition receptors of innate immunity. TLRs initiate inflammatory pathways that may exacerbate chronic inflammatory diseases like atherosclerosis. En face laser scanning confocal microscopy (LSCM) of isolated aortic segments revealed the distribution of intimal TLR2 expression and the atheroprotective outcomes resulting from a TLR2 deficiency. TLR2 expression was restricted to endothelial cells in regions of disturbed blood flow, such as the lesser curvature region, in atherosclerosis-prone, low-density lipoprotein receptor–deficient (LDLr−/−) mice. Diet-induced hyperlipidemia in LDLr−/− mice increased this regional endothelial TLR2 expression. Bone marrow (BM) reconstitution of LDLr−/− and LDLr−/−TLR2−/− mice created chimeric mice with green fluorescent protein (GFP) expression in BM-derived cells (BMGFP+). Lesser curvature BMGFP+ leukocyte accumulation, lipid accumulation, foam cell generation and endothelial cell injury were all increased by hyperlipidemia, whereas hyperlipidemic double mutant BMGFP+LDLr−/−TLR2−/− mice had reduced BMGFP+ leukocyte accumulation, lipid accumulation, foam cells, and endothelial cell injury. This is the first report of in vivo site-specific expression of endothelial cell TLR2. Expression of this receptor on endothelial cells contributed to early atherosclerotic processes in lesion-prone areas of the mouse aorta.
Ozone exposure in a mouse model induces airway hyperreactivity that requires the presence of natural killer T cells and IL-17
Authors: Pichavant Muriel , Goya Sho , Meyer Everett H. , Johnston Richard A. , Kim Hye Y. , Matangkasombut Ponpan , Zhu Ming , Iwakura Yoichiro , Savage Paul B. , DeKruyff Rosemarie H. , Shore Stephanie A. , Umetsu Dale T.
Published: February 2008

Exposure to ozone, which is a major component of air pollution, induces a form of asthma that occurs in the absence of adaptive immunity. Although ozone-induced asthma is characterized by airway neutrophilia, and not eosinophilia, it is nevertheless associated with airway hyperreactivity (AHR), which is a cardinal feature of asthma. Because AHR induced by allergens requires the presence of natural killer T (NKT) cells, we asked whether ozone-induced AHR had similar requirements. We found that repeated exposure of wild-type (WT) mice to ozone induced severe AHR associated with an increase in airway NKT cells, neutrophils, and macrophages. Surprisingly, NKT cell–deficient (CD1d−/− and Jα18−/−) mice failed to develop ozone-induced AHR. Further, treatment of WT mice with an anti-CD1d mAb blocked NKT cell activation and prevented ozone-induced AHR. Moreover, ozone-induced, but not allergen-induced, AHR was associated with NKT cells producing interleukin (IL)-17, and failed to occur in IL-17−/− mice nor in WT mice treated with anti–IL-17 mAb. Thus, ozone exposure induces AHR that requires the presence of NKT cells and IL-17 production. Because NKT cells are required for the development of two very disparate forms of AHR (ozone- and allergen-induced), our results strongly suggest that NKT cells mediate a unifying pathogenic mechanism for several distinct forms of asthma, and represent a unique target for effective asthma therapy.
Oct2 enhances antibody-secreting cell differentiation through regulation of IL-5 receptor α chain expression on activated B cells
Authors: Emslie Dianne , D'Costa Kathy , Hasbold Jhagvaral , Metcalf Donald , Takatsu Kiyoshi , Hodgkin Philip O. , Corcoran Lynn M.
Published: February 2008

Mice lacking a functional gene for the Oct2 transcriptional activator display several developmental and functional deficiencies in the B lymphocyte lineage. These include defective B cell receptor (BCR) and Toll-like receptor 4 signaling, an absence of B-1 and marginal zone populations, and globally reduced levels of serum immunoglobulin (Ig) in naive and immunized animals. Oct2 was originally identified through its ability to bind to regulatory regions in the Ig loci, but genetic evidence has not supported an essential role for Oct2 in the expression of Ig genes. We describe a new Oct2-mediated role in B cells. Oct2 augments the ability of activated B cells to differentiate to antibody-secreting plasma cells (ASCs) under T cell–dependent conditions through direct regulation of the gene encoding the α chain of the interleukin (IL) 5 receptor. Ectopic expression of IL-5Rα in oct2-deficient B cells largely restores their ability to differentiate to functional ASCs in vitro but does not correct other phenotypic defects in the mutants, such as the maturation and specialization of peripheral B cells, which must therefore rely on distinct Oct2 target genes. IL-5 augments ASC differentiation in vitro, and we show that IL-5 directly activates the plasma cell differentiation program by enhancing blimp1 expression.
Appropriateness of Use of Indwelling Urinary Tract Catheters in Hospitalized Patients in Italy
Authors: Raffaele Gianluca , Bianco Aida , Aiello Maria , Pavia Maria
Published: February 2008

By reviewing medical records, we evaluated the appropriateness of use of indwelling urinary tract catheters in hospitalized patients in Italy. The inappropriate use of an indwelling urinary tract catheter (in 138 [30%] of 461 patients) was significantly associated with greater age, not having undergone a surgical intervention, a good state of consciousness, presence of chronic comorbidities, duration of catheterization, and ward of admission.
The evolution of virulence and pathogenicity in plant pathogen populations
Authors: SACRISTÁN SOLEDAD , GARCÍA‐ARENAL FERNANDO
Published: February 2008

The term virulence has a conflicting history among plant pathologists. Here we define virulence as the degree of damage caused to a host by parasite infection, assumed to be negatively correlated with host fitness, and pathogenicity the qualitative capacity of a parasite to infect and cause disease on a host. Selection may act on both virulence and pathogenicity, and their change in parasite populations can drive parasite evolution and host–parasite co‐evolution. Extensive theoretical analyses of the factors that shape the evolution of pathogenicity and virulence have been reported in last three decades. Experimental work has not followed the path of theoretical analyses. Plant pathologists have shown greater interest in pathogenicity than in virulence, and our understanding of the molecular basis of pathogenicity has increased enormously. However, little is known regarding the molecular basis of virulence. It has been proposed that the mechanisms of recognition of parasites by hosts will have consequences for the evolution of pathogenicity, but much experimental work is still needed to test these hypotheses. Much theoretical work has been based on evidence from cellular plant pathogens. We review here the current experimental and observational evidence on which to test theoretical hypotheses or conjectures. We compare evidence from viruses and cellular pathogens, mostly fungi and oomycetes, which differ widely in genomic complexity and in parasitism. Data on the evolution of pathogenicity and virulence from viruses and fungi show important differences, and their comparison is necessary to establish the generality of hypotheses on pathogenicity and virulence evolution.
Multi‐factor regulation of pectate lyase secretion by Colletotrichum gloeosporioides pathogenic on avocado fruits
Authors: MIYARA I. , SHAFRAN H. , KRAMER HAIMOVICH H. , ROLLINS J. , SHERMAN A. , PRUSKY D.
Published: February 2008

Tissue alkalinization during Colletotrichum gloeosporioides attack enhances the expression of PELB, which encodes pectate lyase (PL), and PL secretion, which is considered essential for full virulence. We studied the regulation of PL secretion by manipulation of C. gloeosporioides PELB. PELB was down‐regulated by knocking out PAC1, which encodes the PacC transcription factor that regulates gene products with pH‐sensitive activities. We functionally characterized a PACC gene homologue, PAC1, from C. gloeosporioides wild‐type (WT) Cg‐14 and two independent deletion strains, Δpac1372and Δpac1761. Loss‐of‐function PAC1 mutants showed 85% reduction of PELB transcript expression, delayed PL secretion and dramatically reduced virulence, as detected in infection assays with avocado fruits. In contrast, PELB was up‐regulated in the presence of carbon sources such as glucose. When glucose was used as a carbon source in the medium for the WT strain and the Δpac1 mutant at pH 6.0, PELB transcript expression and PL secretion were activated. Other sugars, such as sucrose and fructose (but not galactose), also activated PELB expression. These results suggest that the pH‐regulated response is only part of a multi‐factor regulation of PELB, and that sugars are also needed to promote the transition from quiescent to active necrotrophic development by the pathogen.
Are diatoms good integrators of temporal variability in stream water quality?
Authors: LAVOIE ISABELLE , CAMPEAU STÉPHANE , DARCHAMBEAU FRANÇOIS , CABANA GILBERT , DILLON PETER J.
Published: February 2008

1. Although diatoms have been used for many decades for river monitoring around the world, studies showing evidence that diatoms integrate temporal variability in water chemistry are scarce.

2. The purpose of this study was to evaluate the response of the Eastern Canadian Diatom Index (IDEC: Indice Diatomées de l’Est du Canada) with respect to temporal water chemistry variability using three different spatio‐temporal data sets.

3. Along a large phosphorus gradient, the IDEC was highly correlated with averaged water chemistry data. Along within‐stream phosphorus gradients, the IDEC integrated phosphorus over various periods of time, depending on the trophic status of the site studied (Boyer, Nicolet or Ste. Anne river) and variability in nutrient concentration.

4. In the Ste. Anne River, where nutrient concentrations were low and generally stable, an input of phosphorus induced a rapid change in diatom community structure and IDEC value within the following week. In the mesotrophic Nicolet River, the observed integration period was approximately 2 weeks. Diatom communities in the eutrophic Boyer River appeared to be adapted to frequent and significant fluctuations in nutrient concentrations. In this system, the IDEC therefore showed a slower response to short term fluctuations and integrated nutrient concentrations over a period of 5 weeks.

5. Our results suggest that the integration period varies as a function of trophic status and nutrient concentration variability in the streams. Oligotrophic streams are more sensitive to nutrient variations and their diatom communities are directly altered by nutrient increase, while diatom communities of eutrophic rivers are less sensitive to nutrient fluctuations and major variations take a longer time to be integrated into index values.

6. The longer integration period in the eutrophic environment may be attributed to the complexity of the diatom community. The results from this study showed that the diversity and evenness of the communities increased with trophic status.
Fine‐scale patterns of genetic variation indicate non‐equilibrium gene frequency divergence in the stream lily, Helmholtzia glaberrima
Authors: PRENTIS PETER J. , MATHER PETER B.
Published: February 2008

1. Helmholtzia glaberrima (Philydraceae) is a rare plant, endemic to streams of the border ranges of Queensland and New South Wales, Australia.

2. We used AFLP markers to investigate genetic diversity and patterns of differentiation among 19 populations of H. glaberrima (24 for demographic analyses), and also collected data on the size, distribution and altitude of populations.

3. Based on the distribution of populations, altitude significantly influenced the spatial arrangement of H. glaberrima along stream systems, with population size and frequency greatest in upstream habitat.

4. Patterns of genetic diversity within populations were not related to population size or distribution. Altitude and genetic diversity were related, with upstream and downstream populations having higher genetic diversity than mid‐stream populations. Differentiation among populations was pronounced at all spatial scales and did not conform to a hierarchical model of gene flow.

5. Both genetic diversity and differentiation data sets indicated that strong non‐equilibrium conditions associated with persistent founder effects, and not landscape characteristics, have shaped patterns of genetic diversity and differentiation in H. glaberrima. Patterns of distribution indicate that populations are distributed over a discontinuous ecological gradient, which becomes marginal at lower altitudes.
Progesterone receptor reactivity in renal oncocytoma and chromophobe renal cell carcinoma
Authors: Mai K T , Teo I , Belanger E C , Robertson S J , Marginean E C , Islam S
Published: February 2008

Aims:  To investigate the reactivity for oestrogen and progesterone receptors (ER and PR) in renal oncocytoma (RO) and chromophobe renal cell carcinoma (CHRCC).

Materials and methods:  Thirty‐eight RO, 25 CHRCC, 20 papillary RCC with oncocytic cytoplasm and 10 clear cell RCC with dominant eosinophilic cytoplasm were submitted for immunohistochemistry for ER, PR, CD117 and RCC.

Results:  All cases of RO and CHRCC displayed moderately positive reactivity for PR. The nuclear reactivity ranged from 60% to 90% in RO and from occasional cells to 70% in CHRCC. In CHRCC, reactivity tended to be more prevalent in areas of tumour cells with eosinophilic cytoplasm. Progesterone reactivity was focal in areas. All RO and most CHRCC were reactive for CD117 and neither RO nor CHRCC was reactive for RCC. CD117 reactivity tended to be more intense in CHRCC than in RO. Negative reactivity for CD117 and positive reactivity for RCC were observed in almost all RCC, as reported in the literature.

Conclusions:  PR can be used in combination with CD117 and RCC in the differential diagnosis of RO and eosinophilic variant of CHRCC with other RCC with oncocytic or eosinophilic cytoplasm.
Sclerosing poorly differentiated liposarcoma: clinicopathological, immunohistochemical and molecular analysis of a distinct morphological subtype of lipomatous tumour of soft tissue
Authors: Suster S , Morrison C
Published: February 2008

Aims:  To present eight cases of a distinctive morphological subtype of lipomatous tumour of soft tissue.

Methods and results:  The clinicopathological, immunohistochemical and molecular pathological features of these tumours were analysed. The tumours were characterized by dense stromal sclerosis containing singly scattered pleomorphic atypical cells with lipoblastic features. The tumours occurred in four women and four men, aged 39–90 years (mean = 63). They were located in the retroperitoneum, thigh, retropubic space, arm and spermatic cord. Four cases arose de novo and four cases presented as local recurrences of previously resected liposarcomas. MDM2 amplification and cyclophoshamide doxorubicin hydrochloride (adriamycin), vincristine and prednisolone (CHOP) translocation was studied in seven cases by fluorescence in situ hybridization. High‐level amplification of MDM2 at 12q13‐15 was observed in 4/7 cases. All cases were negative for the CHOP translocation; in one MDM2+ case, the CHOP gene showed amplification but no translocation. Three patients died from their tumours from 1 to 6 years after their last surgery with lung metastases.

Conclusions:  The tumours described appear to represent an unusual morphological variant of poorly differentiated liposarcoma associated with aggressive behaviour, and may represent a common end‐stage pathway for various types of liposarcoma.
Chromogranin A expression correlates with tumour cell type and prognosis in signet ring cell carcinoma of the stomach
Authors: Fujiyoshi Y , Eimoto T
Published: February 2008

Aims:  To investigate neuroendocrine (NE) differentiation in gastric signet ring cell carcinoma (SRCC) using chromogranin A (CgA) as an indicator of a well‐differentiated NE phenotype and to determine its relationship to cell type, stage and prognosis.

Methods and results:  102 SRCCs were categorized into five subtypes according to the predominant cell type in the World Health Organization classification. 38 cases (37.3%) showed focal or diffuse CgA positivity. The positive cells were mostly histiocytoid and eosinophilic SRCC cells and some were classical SRCC cells. Small cell and anaplastic‐type SRCC cells were only rarely immunopositive. There was no significant relationship between CgA expression and the extent of invasion or presence of metastasis. However, a significant positive correlation existed between CgA positivity and favourable prognosis, with a tendency for greater positivity to be associated with better overall survival. Multivariate analysis showed expression of CgA to be an independent prognostic factor.

Conclusion:  CgA expression is restricted to certain tumour cell types and may help to predict prognosis in gastric SRCCs.