bluuebunny/crossref_metadata_2025 huggingface dataset:
VEGFR-3 is expressed on megakaryocyte precursors in the murine bone marrow and plays a regulatory role in megakaryopoiesis
Authors: Thiele Wilko , Krishnan Jaya , Rothley Melanie , Weih Debra , Plaumann Diana , Kuch Vanessa , Quagliata Luca , Weich Herbert A. , Sleeman Jonathan P.
Published: July 2012

VEGFR-3 is a transmembrane receptor tyrosine kinase that is activated by its ligands VEGF-C and VEGF-D. Although VEGFR-3 has been linked primarily to the regulation of lymphangiogenesis, in the present study, we demonstrate a role for VEGFR-3 in megakaryopoiesis. Using a human erythroleukemia cell line and primary murine BM cells, we show that VEGFR-3 is expressed on megakaryocytic progenitor cells through to the promegakaryoblast stage. Functionally, specific activation of VEGFR-3 impaired the transition to polyploidy of CD41+ cells in primary BM cultures. Blockade of VEGFR-3 promoted endoreplication consistently. In vivo, long-term activation or blockade of VEGFR-3 did not affect steady-state murine megakaryopoiesis or platelet counts significantly. However, activation of VEGFR-3 in sublethally irradiated mice resulted in significantly elevated numbers of CD41+ cells in the BM and a significant increase in diploid CD41+ cells, whereas the number of polyploid CD41+ cells was reduced significantly. Moreover, activation of VEGFR-3 increased platelet counts in thrombopoietin-treated mice significantly and modulated 5-fluorouracil–induced thrombocytosis strongly, suggesting a regulatory role for VEGFR-3 in megakaryopoiesis.
Intrinsic impairment of CD4+CD25+ regulatory T cells in acquired aplastic anemia
Authors: Shi Jun , Ge Meili , Lu Shihong , Li Xingxin , Shao Yingqi , Huang Jinbo , Huang Zhendong , Zhang Jing , Nie Neng , Zheng Yizhou
Published: July 2012

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure attacked by autoreactive effector T cells and BM is the main target organ. CD4+CD25+ regulatory T cells (Tregs) were believed to control development and progression of autoimmunity by suppressing autoreactive effector T cells, but little was known regarding the function of Tregs in AA. Our study demonstrated that both peripheral blood (PB) and BM had decreased frequencies of Tregs, accompanied with a reversed lower ratio of Treg frequencies between BM and PB in AA. PB Tregs in AA had impaired migratory ability because of lower CXCR4 (but not for CXCR7) expression. Interestingly, we first showed that impairment of Treg-mediated immunosuppression was intrinsic to Tregs, rather than resistance of effector T cells to suppression in AA by coculture assays and criss-cross experiments in vitro. Furthermore, Tregs in AA were less able to inhibit interferon-γ production by effector T cells. Defective immunosuppression by Tregs could contribute to impaired hematopoiesis conducted by effector T cells in vitro. Our study provided powerful evidence that impairment of Tregs played a critical role in the pathophysiology of AA. Thus, patients with AA might greatly benefit from a Treg-oriented immunosuppressive strategy.
Internalization and endosomal degradation of receptor-bound antigens regulate the efficiency of cross presentation by human dendritic cells
Authors: Chatterjee Bithi , Smed-Sörensen Anna , Cohn Lillian , Chalouni Cécile , Vandlen Richard , Lee Byoung-Chul , Widger Jenifer , Keler Tibor , Delamarre Lélia , Mellman Ira
Published: July 2012

Dendritic cells (DCs) can capture extracellular antigens and load resultant peptides on to MHC class I molecules, a process termed cross presentation. The mechanisms of cross presentation remain incompletely understood, particularly in primary human DCs. One unknown is the extent to which antigen delivery to distinct endocytic compartments determines cross presentation efficiency, possibly by influencing antigen egress to the cytosol. We addressed the problem directly and quantitatively by comparing the cross presentation of identical antigens conjugated with antibodies against different DC receptors that are targeted to early or late endosomes at distinct efficiencies. In human BDCA1+ and monocyte-derived DCs, CD40 and mannose receptor targeted antibody conjugates to early endosomes, whereas DEC205 targeted antigen primarily to late compartments. Surprisingly, the receptor least efficient at internalization, CD40, was the most efficient at cross presentation. This did not reflect DC activation by CD40, but rather its relatively poor uptake or intra-endosomal degradation compared with mannose receptor or DEC205. Thus, although both early and late endosomes appear to support cross presentation in human DCs, internalization efficiency, especially to late compartments, may be a negative predictor of activity when selecting receptors for vaccine development.
Inhibition of proliferation and survival of diffuse large B-cell lymphoma cells by a small-molecule inhibitor of the ubiquitin-conjugating enzyme Ubc13-Uev1A
Authors: Pulvino Mary , Liang Yue , Oleksyn David , DeRan Michael , Van Pelt Elise , Shapiro Joel , Sanz Ignacio , Chen Luojing , Zhao Jiyong
Published: July 2012

Diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma, remains a partially curable disease. Genetic alterations affecting components of NF-κB signaling pathways occur frequently in DLBCL. Almost all activated B cell–like (ABC) DLBCL, which is the least curable group among the 3 major subtypes of this malignancy, and a substantial fraction of germinal center B cell–like (GCB) DLBCL exhibit constitutive NF-κB pathway activity. It has been demonstrated that ABC-DLBCL cells require such activity for proliferation and survival. Therefore, inhibition of NF-κB activation in DLBCL may provide an efficient and targeted therapy. In screening for small-molecule compounds that may inhibit NF-κB activation in DLBCL cells, we identified a compound, NSC697923, which inhibits the activity of the ubiquitin-conjugating (E2) enzyme Ubc13-Uev1A. NSC697923 impedes the formation of the Ubc13 and ubiquitin thioester conjugate and suppresses constitutive NF-κB activity in ABC-DLBCL cells. Importantly, NSC697923 inhibits the proliferation and survival of ABC-DLBCL cells and GCB-DLBCL cells, suggesting the Ubc13-Uev1A may be crucial for DLBCL growth. Consistently, knockdown of Ubc13 expression also inhibited DLBCL cell survival. The results of the present study indicate that Ubc13-Uev1A may represent a potential therapeutic target in DLBCL. In addition, compound NSC697923 may be exploited for the development of DLBCL therapeutic agents.
Superiority of bortezomib, thalidomide, and dexamethasone (VTD) as induction pretransplantation therapy in multiple myeloma: a randomized phase 3 PETHEMA/GEM study
Authors: Rosiñol Laura , Oriol Albert , Teruel Ana Isabel , Hernández Dolores , López-Jiménez Javier , de la Rubia Javier , Granell Miquel , Besalduch Joan , Palomera Luis , González Yolanda , Etxebeste Mª Asunción , Díaz-Mediavilla Joaquín , Hernández Miguel T. , de Arriba Felipe , Gutiérrez Norma C. , Martín-Ramos Mª Luisa , Cibeira Mª Teresa , Mateos Mª Victoria , Martínez Joaquín , Alegre Adrián , Lahuerta Juan José , San Miguel Jesús , Bladé Joan
Published: July 2012

The Spanish Myeloma Group conducted a trial to compare bortezomib/thalidomide/dexamethasone (VTD) versus thalidomide/dexamethasone (TD) versus vincristine, BCNU, melphalan, cyclophosphamide, prednisone/vincristine, BCNU, doxorubicin, dexamethasone/bortezomib (VBMCP/VBAD/B) in patients aged 65 years or younger with multiple myeloma. The primary endpoint was complete response (CR) rate postinduction and post–autologous stem cell transplantation (ASCT). Three hundred eighty-six patients were allocated to VTD (130), TD (127), or VBMCP/VBAD/B (129). The CR rate was significantly higher with VTD than with TD (35% vs 14%, P = .001) or with VBMCP/VBAD/B (35% vs 21%, P = .01). The median progression-free survival (PFS) was significantly longer with VTD (56.2 vs 28.2 vs 35.5 months, P = .01). In an intention-to-treat analysis, the post-ASCT CR rate was higher with VTD than with TD (46% vs 24%, P = .004) or with VBMCP/VBAD/B (46% vs 38%, P = .1). Patients with high-risk cytogenetics had a shorter PFS and overall survival in the overall series and in all treatment groups. In conclusion, VTD resulted in a higher pre- and posttransplantation CR rate and in a significantly longer PFS although it was not able to overcome the poor prognosis of high-risk cytogenetics. Our results support the use of VTD as a highly effective induction regimen prior to ASCT. The study was registered with http://www.clinicaltrials.gov (NCT00461747) and Eudra CT (no. 2005-001110-41).
LNA-mediated anti–miR-155 silencing in low-grade B-cell lymphomas
Authors: Zhang Yong , Roccaro Aldo M. , Rombaoa Christopher , Flores Ludmilla , Obad Susanna , Fernandes Stacey M. , Sacco Antonio , Liu Yang , Ngo Hai , Quang Phong , Azab Abdel Kareem , Azab Feda , Maiso Patricia , Reagan Michaela , Brown Jennifer R. , Thai To-Ha , Kauppinen Sakari , Ghobrial Irene M.
Published: July 2012

miR-155 acts as an oncogenic miR in B-cell lymphoproliferative disorders, including Waldenstrom macroglobulinemia (WM) and chronic lymphocytic leukemia, and is therefore a potential target for therapeutic intervention. However, efficient targeting of miRs in tumor cells in vivo remains a significant challenge for the development of miR-155–based therapeutics for the treatment of B-cell malignancies. In the present study, we show that an 8-mer locked nucleic acid anti–miR-155 oligonucleotide targeting the seed region of miR-155 inhibits WM and chronic lymphocytic leukemia cell proliferation in vitro. Moreover, anti–miR-155 delivered systemically showed uptake in the BM CD19+ cells of WM-engrafted mice, resulting in the up-regulation of several miR-155 target mRNAs in these cells, and decreased tumor growth significantly in vivo. We also found miR-155 levels to be elevated in stromal cells from WM patients compared with control samples. Interestingly, stromal cells from miR-155–knockout mice led to significant inhibition of WM tumor growth, indicating that miR-155 may also contribute to WM proliferation through BM microenvironmental cells. The results of the present study highlight the therapeutic potential of anti–miR-155–mediated inhibition of miR-155 in the treatment of WM.
Inactivation of heparan sulfate 2-O-sulfotransferase accentuates neutrophil infiltration during acute inflammation in mice
Authors: Axelsson Jakob , Xu Ding , Na Kang Bit , Nussbacher Julia K. , Handel Tracy M. , Ley Klaus , Sriramarao P. , Esko Jeffrey D.
Published: July 2012

Neutrophil recruitment and extravasation at sites of inflammation provide a mechanism for host defense. We showed previously that heparan sulfate, a type of sulfated glycosaminoglycan, facilitates neutrophil recruitment based on the reduction of neutrophil infiltration in mice in which the overall sulfation of the chains was reduced by selective inactivation of N-acetylglucosamine N-deacetylase-N-sulfotransferase (Ndst1) in endothelial cells. Here we show that inactivation of uronyl 2-O-sulfotransferase in endothelial cells (Hs2st), an enzyme that acts downstream from Ndst1, results in enhanced neutrophil recruitment in several models of acute inflammation. Enhanced neutrophil infiltration resulted in part from reduced rolling velocity under flow both in vivo and in vitro, which correlated with stronger binding of neutrophil L-selectin to mutant endothelial cells. Hs2st-deficient endothelial cells also displayed a striking increase in binding of IL-8 and macrophage inflammatory protein-2. The enhanced binding of these mediators of neutrophil recruitment resulted from a change in heparan sulfate structure caused by increased N-sulfation and 6-O-sulfation of glucosamine units in response to the decrease in 2-O-sulfation of uronic acid residues. This gain-of-function phenotype provides formidable evidence demonstrating the importance of endothelial heparan sulfate in inflammation and suggests a novel enzyme target for enhancing the innate immune response.
SOCS3 is an endogenous inhibitor of pathologic angiogenesis
Authors: Stahl Andreas , Joyal Jean-Sebastian , Chen Jing , Sapieha Przemyslaw , Juan Aimee M. , Hatton Colman J. , Pei Dorothy T. , Hurst Christian G. , Seaward Molly R. , Krah Nathan M. , Dennison Roberta J. , Greene Emily R. , Boscolo Elisa , Panigrahy Dipak , Smith Lois E. H.
Published: July 2012

Inflammatory cytokines and growth factors drive angiogenesis independently; however, their integrated role in pathologic and physiologic angiogenesis is not fully understood. Suppressor of cytokine signaling-3 (SOCS3) is an inducible negative feedback regulator of inflammation and growth factor signaling. In the present study, we show that SOCS3 curbs pathologic angiogenesis. Using a Cre/Lox system, we deleted SOCS3 in vessels and studied developmental and pathologic angiogenesis in murine models of oxygen-induced retinopathy and cancer. Conditional loss of SOCS3 leads to increased pathologic neovascularization, resulting in pronounced retinopathy and increased tumor size. In contrast, physiologic vascularization is not regulated by SOCS3. In vitro, SOCS3 knockdown increases proliferation and sprouting of endothelial cells costimulated with IGF-1 and TNFα via reduced feedback inhibition of the STAT3 and mTOR pathways. These results identify SOCS3 as a pivotal endogenous feedback inhibitor of pathologic angiogenesis and a potential therapeutic target acting at the converging crossroads of growth factor– and cytokine-induced vessel growth.
The porphyrias: advances in diagnosis and treatment
Authors: Balwani Manisha , Desnick Robert J.
Published: July 2012

The inborn errors of heme biosynthesis, the porphyrias, are 8 genetically distinct metabolic disorders that can be classified as “acute hepatic,” “hepatic cutaneous,” and “erythropoietic cutaneous” diseases. Recent advances in understanding their pathogenesis and molecular genetic heterogeneity have led to improved diagnosis and treatment. These advances include DNA-based diagnoses for all the porphyrias, new understanding of the pathogenesis of the acute hepatic porphyrias, identification of the iron overload-induced inhibitor of hepatic uroporphyrin decarboxylase activity that causes the most common porphyria, porphyria cutanea tarda, the identification of an X-linked form of erythropoietic protoporphyria due to gain-of-function mutations in erythroid-specific 5-aminolevulinate synthase (ALAS2), and new and experimental treatments for the erythropoietic prophyrias. Knowledge of these advances is relevant for hematologists because they administer the hematin infusions to treat the acute attacks in patients with the acute hepatic porphyrias, perform the chronic phlebotomies to reduce the iron overload and clear the dermatologic lesions in porphyria cutanea tarda, and diagnose and treat the erythropoietic porphyrias, including chronic erythrocyte transfusions, bone marrow or hematopoietic stem cell transplants, and experimental pharmacologic chaperone and stem cell gene therapies for congenital erythropoietic protoporphyria. These developments are reviewed to update hematologists on the latest advances in these diverse disorders.
Nucleotide variability and linkage disequilibrium patterns in the porcine MUC4 gene
Authors: Yang Ming , Yang Bin , Yan Xueming , Ouyang Jing , Zeng Weihong , Ai Huashui , Ren Jun , Huang Lusheng
Published: July 2012

Background

MUC4 is a type of membrane anchored glycoprotein and serves as the major constituent of mucus that covers epithelial surfaces of many tissues such as trachea, colon and cervix. MUC4 plays important roles in the lubrication and protection of the surface epithelium, cell proliferation and differentiation, immune response, cell adhesion and cancer development. To gain insights into the evolution of the porcine MUC4 gene, we surveyed the nucleotide variability and linkage disequilibrium (LD) within this gene in Chinese indigenous breeds and Western commercial breeds.

Results

A total of 53 SNPs covering the MUC4 gene were genotyped on 5 wild boars and 307 domestic pigs representing 11 Chinese breeds and 3 Western breeds. The nucleotide variability, haplotype phylogeny and LD extent of MUC4 were analyzed in these breeds. Both Chinese and Western breeds had considerable nucleotide diversity at the MUC4 locus. Western pig breeds like Duroc and Large White have comparable nucleotide diversity as many of Chinese breeds, thus artificial selection for lean pork production have not reduced the genetic variability of MUC4 in Western commercial breeds. Haplotype phylogeny analyses indicated that MUC4 had evolved divergently in Chinese and Western pigs. The dendrogram of genetic differentiation between breeds generally reflected demographic history and geographical distribution of these breeds. LD patterns were unexpectedly similar between Chinese and Western breeds, in which LD usually extended less than 20 kb. This is different from the presumed high LD extent (more than 100 kb) in Western commercial breeds. The significant positive Tajima’D, and Fu and Li’s D statistics in a few Chinese and Western breeds implied that MUC4 might undergo balancing selection in domestic breeds. Nevertheless, we cautioned that the significant statistics could be upward biased by SNP ascertainment process.

Conclusions

Chinese and Western breeds have similar nucleotide diversity but evolve divergently in the MUC4 region. Western breeds exhibited unusual low LD extent at the MUC4 locus, reflecting the complexity of nucleotide variability of pig genome. The finding suggests that high density (e.g. 1SNP/10 kb) markers are required to capture the underlying causal variants at such regions.
Total Lymphocyte Count as surrogate marker for CD4 Cell Count in HIV-Infected Individuals in Gondar University Hospital, Northwest Ethiopia
Authors: Wondimeneh Yitayih , Ferede Getachew , Yismaw Gizachew , Muluye Dagnachew
Published: July 2012

Background

The high cost of CD4 count estimation in resource-limited countries is a major challenge in initiating patients on highly active antiretroviral therapy (HAART). Therefore, assessment of inexpensive and simple laboratory diagnostic marker is mandatory to diagnose immuno-suppression.

Objective

To evaluate utility of total lymphocyte count (TLC) as surrogate marker for CD4 count in HIV-infected patients.

Materials and Methods

In this cross sectional study, 400 ART-naive HIV-positive patients enrolled in Gondar University Hospital, from March 2011 to May 2011, were tested for CD4 count & TLC. The cutoffs were determined as: 200 cells/μL for CD4 count and 1200 cells/μL for TLC by using BD FACS count and CELL DYN 1800 Flow Cytometrys respectively. Spearman correlation between TLC and CD4 cell count were assessed. Sensitivity, specificity, positive and negative predictive values for different age a group, TLC ≤1200 was computed for CD4 count ≤200 cells/cu.mm.

Results

Among 400 ART naive HIV infected patients, 278 (69.5%) were females. The mean age of the study participants was 33.7. TLC and CD4 count were positively correlated (r = 0.33, p = 0.001). A TLC of ≤1200 cells/m m3 was found to have a sensitivity (32.86%), specificity (95.33%), PPV (79.7%), and NPV (71.9%) for predicting a CD4 count of <200 cells/mm3.

Conclusion

This study showed that low sensitivity and specificity of TLC as a surrogate measure for CD4 count. Moreover, CD4 cell counts of < 200 cells/mm3 were found in 96 cases (24%) with TLCs of ≤1200 cells/mm3. Thus, 1 in 4 individuals would have been deprived of needed treatment. Therefore, we recommend keep on expansion of access to CD4 counter.
DNA promoter methylation as a diagnostic and therapeutic biomarker in gallbladder cancer
Authors: Letelier Pablo , Brebi Priscilla , Tapia Oscar , Roa Juan Carlos
Published: July 2012

Gallbladder cancer is an infrequent neoplasia with noticeable geographical variations in its incidence around the world. In Chile, it is the main cause of death owing to cancer in women over 40 years old, with mortality rates up to 16.5 per 100,000 cases. The prognosis is poor with few therapeutic options; in advanced cases there is only a 10% survival at 5 years.

Several studies mention the possible role of DNA methylation in gallbladder carcinogenesis. This epigenetic modification affects tumor suppressor genes involved in regulation pathways, cell cycle control, cell adhesion and extracellular matrix degradation, in a sequential and cumulative way. Determining DNA methylation patterns would allow them to be used as biomarkers for the early detection, diagnosis, prognosis and/or therapeutic selection in gallbladder cancer.
Raman microspectroscopy for species identification and mapping within bacterial biofilms
Authors: Beier Brooke D , Quivey Robert G , Berger Andrew J
Published: July 2012

A new method of mapping multiple species of oral bacteria in intact biofilms has been developed, using the optical technique of confocal Raman microscopy. A species classification algorithm, developed on dried biofilms, was used to analyze spectra of hydrated biofilms containing two microbial species central to dental health:Streptococcus sanguinisandStreptococcus mutans. The algorithm transferred successfully to the hydrated environment, correctly identifying the species of origin of single-species biofilms. We then used the algorithm successfully both to detect the presence of two species in mixed biofilms and to create spatial maps within these biofilms.
The top cited clinical research articles on sepsis: a bibliometric analysis
Authors: Tao Tianzhu , Zhao Xiaohong , Lou Jingsheng , Bo Lulong , Wang Fei , Li Jinbao , Deng Xiaoming
Published: July 2012

Introduction

The objective of this study was to identify and characterize the most highly cited clinical research articles published on sepsis.

Methods

A comprehensive list of citation classics in sepsis was generated by searching the database of Web of Science-Expanded (1970 to present) using keywords 'sepsis' or 'septic shock'. The top 50 cited clinical research papers were retrieved by reading the abstract or full text if needed. Each eligible article was reviewed for basic information, including country of origin, article type, journals, authors, and funding sources.

Results

A total of 2,151 articles were cited more than 100 times; the 50 top-cited clinical articles were published between 1974 and 2008. The number of citations ranged from 372 to 2,932, with a mean of 678 citations per article. These citation classics came from nine countries, of which 26 articles came from the United States. Rush University and the University of Pittsburgh lead the list of classics with six papers each. The 50 top-cited articles were published in 17 journals, with the New England Journal of Medicine and Journal of the American Medical Association topping the list. The top 50 articles consisted of 21 clinical trials and 29 observational studies.

Conclusions

Our bibliometric analysis provides a historical perspective on the progress of clinical research on sepsis. Articles originating from the United States and published in high-impact journals are most likely to be cited in the field of sepsis research.
Effects of Fibroblast Growth Factor 9 (FGF9) on Steroidogenesis and Gene Expression and Control of FGF9 mRNA in Bovine Granulosa Cells
Authors: Schreiber Nicole B. , Spicer Leon J.
Published: July 2012

Gene expression of fibroblast growth factor-9 (FGF9) is decreased in granulosa cells (GC) of cystic follicles compared with normal dominant follicles in cattle. The objectives of this study were to investigate the effects of FGF9 on GC steroidogenesis, gene expression, and cell proliferation and to determine the hormonal control of GC FGF9 production. GC were collected from small (1–5 mm) and large (8–22 mm) bovine follicles and treated in vitro with various hormones in serum-free medium for 24 or 48 h. In small- and large-follicle GC, FGF9 inhibited (P < 0.05) IGF-I-, dibutyryl cAMP-, and forskolin-induced progesterone and estradiol production. In contrast, FGF9 increased (P < 0.05) GC numbers induced by IGF-I and 10% fetal calf serum. FGF9 inhibited (P < 0.05) FSHR and CYP11A1 mRNA abundance in small- and large-follicle GC but had no effect (P > 0.10) on CYP19A1 or StAR mRNA. In the presence of a 3β-hydroxysteroid dehydrogenase inhibitor, trilostane, FGF9 also decreased (P < 0.05) pregnenolone production. IGF-I inhibited (P < 0.05) whereas estradiol and FSH had no effect (P > 0.10) on FGF9 mRNA abundance. TNFα and wingless-type mouse mammary tumor virus integration site family member-3A decreased (P < 0.05) whereas T4 and sonic hedgehog increased (P < 0.05) FGF9 mRNA abundance in control and IGF-I-treated GC. Thus, GC FGF9 gene expression is hormonally regulated, and FGF9 may act as an autocrine regulator of ovarian function by slowing follicular differentiation via inhibiting IGF-I action, gonadotropin receptors, the cAMP signaling cascade, and steroid synthesis while stimulating GC proliferation in cattle.
Overexpression of Hepatocyte Nuclear Factor-4α Initiates Cell Cycle Entry, but Is not Sufficient to Promote β-Cell Expansion in Human Islets
Authors: Rieck Sebastian , Zhang Jia , Li Zhaoyu , Liu Chengyang , Naji Ali , Takane Karen K. , Fiaschi-Taesch Nathalie M. , Stewart Andrew F. , Kushner Jake A. , Kaestner Klaus H.
Published: July 2012

The transcription factor HNF4α (hepatocyte nuclear factor-4α) is required for increased β-cell proliferation during metabolic stress in vivo. We hypothesized that HNF4α could induce proliferation of human β-cells. We employed adenoviral-mediated overexpression of an isoform of HNF4α (HNF4α8) alone, or in combination with cyclin-dependent kinase (Cdk)6 and Cyclin D3, in human islets. Heightened HNF4α8 expression led to a 300-fold increase in the number of β-cells in early S-phase. When we overexpressed HNF4α8 together with Cdk6 and Cyclin D3, β-cell cycle entry was increased even further. However, the punctate manner of bromodeoxyuridine incorporation into HNF4αHigh β-cells indicated an uncoupling of the mechanisms that control the concise timing and execution of each cell cycle phase. Indeed, in HNF4α8-induced bromodeoxyuridine+,punctate β-cells we observed signs of dysregulated DNA synthesis, cell cycle arrest, and activation of a double stranded DNA damage-associated cell cycle checkpoint mechanism, leading to the initiation of loss of β-cell lineage fidelity. However, a substantial proportion of β-cells stimulated to enter the cell cycle by Cdk6 and Cyclin D3 alone also exhibited a DNA damage response. HNF4α8 is a mitogenic signal in the human β-cell but is not sufficient for completion of the cell cycle. The DNA damage response is a barrier to efficient β-cell proliferation in vitro, and we suggest its evaluation in all attempts to stimulate β-cell replication as an approach to diabetes treatment.
The Long Wait: Timely Secrets of the Contemporary Detective Novel
Authors: Martin Theodore
Published: July 2012

What does it mean to read like a detective? While critics have long seen the detective novel as a model for hermeneutic suspicion (the familiar spatial binaries of surface/depth, concealed/revealed), this essay proposes that there is something more timely at work in detective work. Recent detective novels like Michael Chabon's The Yiddish Policeman's Union and Vikram Chandra's Sacred Games require us to reassess the temporalities of expectation, deferral, and disappointment that have traditionally shaped the genre. Detective fiction, these texts suggest, is all about making us wait. Detection, then, is not a stance of suspicion or a law of revelation but a process that illuminates what it means to be subject to time. Ultimately, I argue, the figure of the wait describes not only the narrative time of unmet expectations but also the experience of our most timely historical category: the contemporary itself. Neither proleptic nor periodizable, the contemporary may be most aptly described as a wait. The long wait of the contemporary detective novel shows us how the act of reading is both embedded in and reflective of the times that make up our present time.
National Myth, Transnational Memory: Ondaatje's Archival Method
Authors: Vadde Aarthi
Published: July 2012

This essay proposes that Michael Ondaatje's novels develop an archival method that adapts the historical novel to the globalized era. Where Georg Lukács argued that the classical historical novel awakened national sensibility through the creation of psychologically complex characters (real individuals), I claim that Ondaatje's The Collected Works of Billy the Kid and Anil's Ghost explore the breakdown of that sensibility through the creation of characters as legends. The circulation of these legends, namely Billy the Kid and Sailor, turns the historical novel toward a disruption of national myth rather than the production of it. That disruption is made possible by Ondaatje's use of the archive as a formal paradigm for the novel—one that is open-ended, unsynthesized, and shape shifting. Using the archive as structure and style, Ondaatje challenges national mythologies not so much by demystifying their ideological structures but by immersing American and Sri Lankan legends, Billy and Sailor, in a proliferation of artifacts, genres, and contexts that traverse several national and supranational traditions. Archival form effectively subjects these national legends to defamiliarization and reinscription within transnational geographies of memory that both expand the number of groups that may lay claim to these legends and trouble the boundaries among those groups. In this way, Ondaatje's novels show us how to begin remapping communal pasts in response to the demands of global collectivity, a configuration in which many groups might be said to intersect but cannot be said to cohere.
Does size matter? – Thermoregulation of ‘heavyweight’ and ‘lightweight’ wasps (Vespa crabro and Vespula sp.)
Authors: Kovac Helmut , Stabentheiner Anton
Published: July 2012

In insect groups with the ability of endothermy, the thermoregulatory capacity has a direct relation to body mass. To verify this relationship in vespine wasps, we compared the thermoregulation of hornets (Vespa crabro), the largest species of wasps in Central Europe, with two smaller wasps (Vespula vulgaris and Vespula germanica) in the entire range of ambient temperature (Ta: ∼0–40°C) where the insects exhibited foraging flights.

Despite the great difference in body weight of Vespula (V. vulgaris: 84.1±19.0 mg, V. germanica: 74.1±9.6 mg) and Vespa (477.5±59.9 mg), they exhibited similarities in the dependence of thorax temperature on Ta on their arrival (mean Tth  =  30–40°C) and departure (mean Tth  =  33–40°C) at the nest entrance. However, the hornets' thorax temperature was up to 2.5°C higher upon arrival and up to 3°C lower at departure. The thorax temperature excess (Tth−Ta) above ambient air of about 5–18°C indicates a high endothermic capacity in both hornets and wasps. Heat gain from solar radiation elevated the temperature excess by up to 1°C. Results show that hornets and wasps are able to regulate their body temperature quite well, even during flight. A comparison of flight temperature with literature reports on other vespine wasps revealed a dependence of the Tth on the body mass in species weighing less than about 200 mg.
Segregation of PIP2 and PIP3 into distinct nanoscale regions within the plasma membrane
Authors: Wang Jie , Richards David A.
Published: July 2012

PIP2 and PIP3 are implicated in a wide variety of cellular signaling pathways at the plasma membrane. We have used STORM imaging to localize clusters of PIP2 and PIP3 to distinct nanoscale regions within the plasma membrane of PC12 cells. With anti-phospholipid antibodies directly conjugated with AlexaFluor 647, we found that PIP2 clusters in membrane domains of 64.5±27.558 nm, while PIP3 clusters had a size of 125.6±22.408 nm. With two color direct STORM imaging we show that >99% of phospholipid clusters have only one or other phospholipid present. These results indicate that lipid nano-domains can be readily identified using super-resolution imaging techniques, and that the lipid composition and size of clusters is tightly regulated.
Dealing with water deficit in Atta ant colonies: large ants scout for water while small ants transport it
Authors: Da-Silva Antonio Carlos , Navas Carlos A. , Ribeiro Pedro L.
Published: July 2012

Leafcutter ants (Atta sexdens rubropilosa) (Forel 1908) have an elaborate social organization, complete with caste divisions. Activities carried out by specialist groups contribute to the overall success and survival of the colony when it is confronted with environmental challenges such as dehydration. Ants detect variations in humidity inside the nest and react by activating several types of behavior that enhance water uptake and decrease water loss, but it is not clear whether or not a single caste collects water regardless of the cost of bringing this resource back to the colony. Accordingly, we investigated water collection activities in three colonies of Atta sexdens rubropilosa experimentally exposed to water stress. Specifically, we analyzed whether or not the same ant caste foraged for water, regardless of the absolute energetic cost (distance) of transporting this resource back to the colony. Our experimental design offered water sources at 0 m, 1 m and 10 m from the nest. We studied the body size of ants near the water sources from the initial offer of water (time  =  0) to 120 min, and tested for specialization. We observed a reduction in the average size and variance of ants that corroborated the specialization hypothesis. Although the temporal course of specialization changed with distance, the final outcome was similar among distances. Thus, we conclude that, for this species, a specialist (our use of the word “specialist” does not mean exclusive) task force is responsible for collecting water, regardless of the cost of transporting water back to the colony.
Deconstructing the third dimension – how 3D culture microenvironments alter cellular cues
Authors: Baker Brendon M. , Chen Christopher S.
Published: July 2012

Much of our understanding of the biological mechanisms that underlie cellular functions, such as migration, differentiation and force-sensing has been garnered from studying cells cultured on two-dimensional (2D) glass or plastic surfaces. However, more recently the cell biology field has come to appreciate the dissimilarity between these flat surfaces and the topographically complex, three-dimensional (3D) extracellular environments in which cells routinely operate in vivo. This has spurred substantial efforts towards the development of in vitro 3D biomimetic environments and has encouraged much cross-disciplinary work among biologists, material scientists and tissue engineers. As we move towards more-physiological culture systems for studying fundamental cellular processes, it is crucial to define exactly which factors are operative in 3D microenvironments. Thus, the focus of this Commentary will be on identifying and describing the fundamental features of 3D cell culture systems that influence cell structure, adhesion, mechanotransduction and signaling in response to soluble factors, which – in turn – regulate overall cellular function in ways that depart dramatically from traditional 2D culture formats. Additionally, we will describe experimental scenarios in which 3D culture is particularly relevant, highlight recent advances in materials engineering for studying cell biology, and discuss examples where studying cells in a 3D context provided insights that would not have been observed in traditional 2D systems.
Molecular force transduction by ion channels – diversity and unifying principles
Authors: Sukharev Sergei , Sachs Frederick
Published: July 2012

Cells perceive force through a variety of molecular sensors, of which the mechanosensitive ion channels are the most efficient and act the fastest. These channels apparently evolved to prevent osmotic lysis of the cell as a result of metabolite accumulation and/or external changes in osmolarity. From this simple beginning, nature developed specific mechanosensitive enzymes that allow us to hear, maintain balance, feel touch and regulate many systemic variables, such as blood pressure. For a channel to be mechanosensitive it needs to respond to mechanical stresses by changing its shape between the closed and open states. In that way, forces within the lipid bilayer or within a protein link can do work on the channel and stabilize its state. Ion channels have the highest turnover rates of all enzymes, and they can act as both sensors and effectors, providing the necessary fluxes to relieve osmotic pressure, shift the membrane potential or initiate chemical signaling. In this Commentary, we focus on the common mechanisms by which mechanical forces and the local environment can regulate membrane protein structure, and more specifically, mechanosensitive ion channels.
United we stand – integrating the actin cytoskeleton and cell–matrix adhesions in cellular mechanotransduction
Authors: Schwarz Ulrich S. , Gardel Margaret L.
Published: July 2012

Many essential cellular functions in health and disease are closely linked to the ability of cells to respond to mechanical forces. In the context of cell adhesion to the extracellular matrix, the forces that are generated within the actin cytoskeleton and transmitted through integrin-based focal adhesions are essential for the cellular response to environmental clues, such as the spatial distribution of adhesive ligands or matrix stiffness. Whereas substantial progress has been made in identifying mechanosensitive molecules that can transduce mechanical force into biochemical signals, much less is known about the nature of cytoskeletal force generation and transmission that regulates the magnitude, duration and spatial distribution of forces imposed on these mechanosensitive complexes. By focusing on cell-matrix adhesion to flat elastic substrates, on which traction forces can be measured with high temporal and spatial resolution, we discuss our current understanding of the physical mechanisms that integrate a large range of molecular mechanotransduction events on cellular scales. Physical limits of stability emerge as one important element of the cellular response that complements the structural changes affected by regulatory systems in response to mechanical processes.
Finding the weakest link – exploring integrin-mediated mechanical molecular pathways
Authors: Roca-Cusachs Pere , Iskratsch Thomas , Sheetz Michael P.
Published: July 2012

From the extracellular matrix to the cytoskeleton, a network of molecular links connects cells to their environment. Molecules in this network transmit and detect mechanical forces, which subsequently determine cell behavior and fate. Here, we reconstruct the mechanical pathway followed by these forces. From matrix proteins to actin through integrins and adaptor proteins, we review how forces affect the lifetime of bonds and stretch or alter the conformation of proteins, and how these mechanical changes are converted into biochemical signals in mechanotransduction events. We evaluate which of the proteins in the network can participate in mechanotransduction and which are simply responsible for transmitting forces in a dynamic network. Besides their individual properties, we also analyze how the mechanical responses of a protein are determined by their serial connections from the matrix to actin, their parallel connections in integrin clusters and by the rate at which force is applied to them. All these define mechanical molecular pathways in cells, which are emerging as key regulators of cell function alongside better studied biochemical pathways.
Beclin 1-interacting autophagy protein Atg14L targets SNARE-associated protein Snapin to coordinate endocytic trafficking
Authors: Kim Hee Jin , Zhong Qing , Sheng Zu-Hang , Yoshimori Tamotsu , Liang Chengyu , Jung Jae U.
Published: July 2012

Autophagy is a highly regulated membrane remodeling process that allows the lysosome-mediated degradation of cytoplasmic entities by sequestrating them in double-membrane autophagosomes. Autophagy is hence highly intertwined with the endocytic trafficking pathway, sharing similar molecular machinery. Atg14L, also known as Beclin 1-associated autophagy-related key regulator (Barkor), directly interacts with Beclin 1 through its coiled-coil domain and enhances phosphatidylinositol 3-phosphate kinase class III (PI3KC3) activity to induce autophagosome membrane nucleation, highlighting its essential role in the early stage of mammalian autophagy. Here, we report a novel function of Atg14L in the endocytic trafficking pathway wherein Atg14L binds to and colocalizes with the fusogenic SNARE effector protein Snapin to facilitate endosome maturation. Atg14L specifically binds to Snapin and this interaction effectively facilitates endosomal maturation without affecting autophagic cargo degradation. Consequently, atg14l knockdown significantly delayed the late stage of endocytic trafficking, as evidenced by the retarded kinetics of internalized surface receptor degradation. This phenotype was effectively complemented by Atg14L wildtype or Beclin 1-binding mutant, but not by its Snapin-binding mutant. Taken together, our study demonstrates that Atg14L functions as a multivalent trafficking effector that regulates endosome maturation as well as autophagosome formation, reflecting the complexity of the crosstalk between autophagic and endocytic vesicle trafficking in higher eukaryotes.
Visualisation of direct interaction of MDA5 and the dsRNA replicative intermediate form of positive strand RNA viruses
Authors: Triantafilou Kathy , Vakakis Emmanouil , Kar Satwik , Richer Edward , Evans Gareth L. , Triantafilou Martha
Published: July 2012

The innate immune system is a vital part of the body's defences against viral pathogens. RIG-I and MDA5 function as cytoplasmic PRRs that are involved in the elimination of actively replicating RNA viruses. Their location and their differential responses to RNA viruses emphasises the complexity of the innate detection system. Despite the wealth of information on the types of RNA that trigger RIG-I, much less is known about the nature of the RNAs that act as agonists for MDA5. In order to identify which RNA species triggers MDA5 activation during infection, we isolated viral ssRNA and replicative intermediates of RNA from positive sense ssRNA viruses. We reveal that MDA5 recognises not the genomic ssRNA but the dsRNA generated by the replication of these viruses. Furthermore, using fluorescent imaging we present the first report of the visualization of dsRNA and MDA5, which provides unique evidence between the relationship of viral dsRNA and MDA5 and proves without a doubt that MDA5 is the key sensor for the dsRNA replicative intermediate form of positive sense ssRNA viruses.
ER-shaping proteins facilitate lipid exchange between the ER and mitochondria in S. cerevisiae
Authors: Voss Christiane , Lahiri Sujoy , Young Barry P. , Loewen Christopher J. , Prinz William A.
Published: July 2012

The endoplasmic reticulum (ER) forms a network of sheets and tubules that extends throughout the cell. Proteins required to maintain this complex structure include the reticulons, reticulon-like proteins, and dynamin-like GTPases called atlastins in mammals and Sey1p in S. cerevisiae. Yeast cells missing these proteins have abnormal ER structure, particularly defects in the formation of ER tubules, but grow about as well as wild-type cells. We screened for mutations that cause cells with defects in maintaining ER tubules to grow poorly. Among the genes we found were members of the ER mitochondria encounter structure (ERMES) complex that tethers the ER and mitochondria. Close contacts between the ER and mitochondria are thought to be sites where lipids are moved from the ER to mitochondria, a process that is required for mitochondrial membrane biogenesis. We show that ER to mitochondria phospholipid transfer slows significantly in cells missing both ER-shaping proteins and the ERMES complex. These cells also have altered steady-state levels of phospholipids. We found that the defect in ER to mitochondria phospholipid transfer in a strain missing ER-shaping proteins and a component of the ERMES complex was corrected by expression of a protein that artificially tethers the ER and mitochondria. Our findings indicate that ER-shaping proteins play a role in maintaining functional contacts between the ER and mitochondria and suggest that the shape of the ER at ER-mitochondria contact sites affects lipid exchange between these organelles.
PKD2 and PKD3 Promote Prostate Cancer Cell Invasion via uPA by Shifting Balance Between NF-κB and HDAC1
Authors: Zou Zhipeng , Zeng Fangyin , Xu Wanfu , Wang Chunxia , Ke Zhiyong , Wang Q. Jane , Deng Fan
Published: July 2012

Although protein kinase D3 (PKD3) has been shown to contribute to prostate cancer cell growth and survival, the role of PKD in prostate cancer cell motility remains unclear. Here, we show that PKD2 and PKD3 promote nuclear factor-kappaB (NF-κB) signaling and urokinase-type plasminogen activator (uPA) expression/activation, which are critical to prostate cancer cell invasion. Silencing of endogenous PKD2 and/or PKD3 markedly decreased prostate cancer cell migration and invasion, reduced uPA and uPA receptor (uPAR) expression, and increased plasminogen activator inhibitor-2 (PAI-2) expression. These results were further substantiated by the finding that PKD2 and PKD3 promoted the activity of uPA and matrix metalloproteinase (MMP)-9. Furthermore, depletion of PKD2 and/or PKD3 decreased the binding of p65 NF-κB to the uPA promoter, suppressing transcriptional activation of uPA. Endogenous PKD2 and PKD3 interacted with IκB kinase β (IKKβ); PKD2 mainly regulated the pIKK-IκB-p65 nuclear translocation cascade and phosphorylation of Ser276 on p65, while PKD3 was responsible for the phosphorylation of Ser536 on p65. Conversely, inhibition of uPA transactivation by PKD3 silencing was rescued by constitutive Ser536 phosphorylation, and reduced tumor cell invasion resulting from PKD2 or PKD3 silencing was rescued by ectopic expression of p65. Interestingly, PKD3 interacted with histone deacetylase 1 (HDAC1), suppressing HDAC1 expression and decreasing its binding to the uPA promoter. Moreover, depletion of HDAC1 resulted in recovery of uPA transactivation in PKD3-knockdown cells. Taken together, these data suggest that PKD2 and PKD3 may coordinate to promote prostate cancer cell invasion through p65 NF-κB- and HDAC1-mediated expression and activation of uPA.