http://www.biosignaling.com The latest research articles published by Cell Communication and Signaling 2012-05-16T00:00:00Z Infertility affects one in seven couples globally and has recently been classified as a disease by the World Health Organisation (WHO). While in-vitro fertilisation (IVF) offers effective treatment for many infertile couples, cases exhibiting severe male infertility (19-57%) often remain difficult, if not impossible to treat. In such cases, intracytoplasmic sperm injection (ICSI), a technique in which a single sperm is microinjected into the oocyte, is implemented. However, 1-5% of ICSI cycles still fail to fertilise, affecting over 1000 couples per year in the UK alone. Pregnancy and delivery rates for IVF and ICSI rarely exceed 30% and 23% respectively. It is therefore imperative that Assisted Reproductive Technology (ART) protocols are constantly modified by associated research programmes, in order to provide patients with the best chances of conception. Prior to fertilisation, mature oocytes are arrested in the metaphase stage of the second meiotic division (MII), which must be alleviated to allow the cell cycle, and subsequent embryogenesis, to proceed. Alleviation occurs through a series of concurrent events, collectively termed 'oocyte activation'. In mammals, oocytes are activated by a series of intracellular calcium (Ca2+) oscillations following gamete fusion. Recent evidence implicates a sperm-specific phospholipase C, PLCzeta (PLCzeta), introduced into the oocyte following membrane fusion as the factor responsible. This review summarises our current understanding of oocyte activation failure in human males, and describes recent advances in our knowledge linking certain cases of male infertility with defects in PLCzeta expression and activity. Systematic literature searches were performed using PubMed and the ISI-Web of Knowledge. Databases compiled by the United Nations and World Health Organisation databases (UNWHO), and the Human Fertilization and Embryology Authority (HFEA) were also scrutinised. It is clear that PLCzeta plays a fundamental role in the activation of mammalian oocytes, and that genetic, molecular, or biochemical perturbation of this key enzyme is strongly linked to human infertility where oocyte activation is deficient. Consequently, there is significant scope for our understanding of PLCzeta to be translated to the ART clinic, both as a novel therapeutic agent with which to rescue oocyte activation deficiency (OAD), or as a prognostic/diagnostic biomarker of oocyte activation ability in target sperm samples. http://www.biosignaling.com/content/10/1/12 Walaa Ramadan Junaid Kashir Celine Jones Kevin Coward Cell Communication and Signaling 2012, null:12 2012-05-16T00:00:00Z doi:10.1186/1478-811X-10-12 /content/figures/1478-811X-10-12-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 12 2012-05-16T00:00:00Z PDF In the 21st century, systems-wide analyses of biological processes are getting more and more realistic. Especially for the in depth analysis of signal transduction pathways and networks, various approaches of systems biology are now successfully used. The EU FP7 large integrated project SYBILLA (Systems Biology of T-cell Activation in Health and Disease) coordinates such an endeavor. By using a combination of experimental data sets and computational modelling, the consortium strives for gaining a detailed and mechanistic understanding of signal transduction processes that govern T-cell activation. In order to foster the interaction between systems biologists and experimentally working groups, SYBILLA co-organized the 15th meeting "Signal Transduction: Receptors, Mediators and Genes" together with the Signal Transduction Society (STS). Thus, the annual STS conference, held from November 7 to 9, 2011 in Weimar, Germany, provided an interdisciplinary forum for research on signal transduction with a major focus on systems biology addressing signalling events in T-cells. Here we report on a selection of ongoing projects of SYBILLA and how they were discussed at this interdisciplinary conference. http://www.biosignaling.com/content/10/1/11 Christine Louis-Dit-Sully Katharina Kubatzky Jonathan Lindquist Christine Blattner Ottmar Janssen Wolfgang Schamel Cell Communication and Signaling 2012, null:11 2012-04-30T00:00:00Z doi:10.1186/1478-811X-10-11 /content/figures/1478-811X-10-11-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 11 2012-04-30T00:00:00Z PDF Background: The biological phenomenon of cell fusion has been linked to several characteristics of tumour progression, including an enhanced metastatogenic capacity and an enhanced drug resistance of hybrid cells. We demonstrated recently that M13SV1-EGFP-Neo breast epithelial cells exhibiting stem cell characteristics spontaneously fused with MDA-MB-435-Hyg breast cancer cells, thereby giving rise to stable M13MDA435 hybrid cells, which are characterised by a unique gene expression profile and migratory behaviour. Here we investigated the involvement of the PLC-β/γ1, PI3K/AKT and RAS-RAF-ERK signal transduction cascades in the EGF and SDF-1α induced migration of two M13MDA435 hybrid cell clones in comparison to their parental cells. Results: Analysis of the migratory behaviour by using the three-dimensional collagen matrix migration assay showed that M13SV1-EGFP-Neo cells as well as M13MDA435 hybrid cells, but not the breast cancer cell line, responded to EGF stimulation with an increased locomotory activity. By contrast, SDF-1α solely stimulated the migration of M13SV1-EGFP-Neo cells, whereas the migratory activity of the other cell lines was blocked. Analysis of signal transduction cascades revealed a putative differential RAF-AKT crosstalk in M13MDA435-1 and -3 hybrid cell clones. The PI3K inhibitor Ly294002 effectively blocked the EGF induced migration of M13MDA435-3 hybrid cells, whereas the EGF induced locomotion of M13MDA435-1 hybrid cells was markedly increased. Analysis of RAF-1 S259 phosphorylation, being a major mediator of the negative regulation of RAF-1 by AKT, showed decreased pRAF-1 S259 levels in LY294002 treated M13MDA435-1 hybrid cells. By contrast, pRAF-1 S259 levels remained unaltered in the other cell lines. Inhibition of PI3K/AKT signalling by Ly294002 relieves the AKT mediated phosphorylation of RAF-1, thereby restoring MAPK signalling. Conclusions: Here we show that hybrid cells could evolve exhibiting a differential active RAF-AKT crosstalk. Because PI3K/AKT signalling has been chosen as a target for anti-cancer therapies our data might point to a possible severe side effect of AKT targeted cancer therapies. Inhibition of PI3K/AKT signalling in RAF-AKT crosstalk positive cancer (hybrid) cells could result in a progression of these cells. Thus, not only the receptor (activation) status, but also the activation of signal transduction molecules should be analysed thoroughly prior to therapy. http://www.biosignaling.com/content/10/1/10 Cem Ozel Jeanette Seidel Sonke Meyer-Staeckling Burkhard Brandt Bernd Niggemann Kurt Zanker Thomas Dittmar Cell Communication and Signaling 2012, null:10 2012-04-09T00:00:00Z doi:10.1186/1478-811X-10-10 /content/figures/1478-811X-10-10-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 10 2012-04-09T00:00:00Z XML Background: The latent membrane protein (LMP) 2A of Epstein-Barr virus (EBV) is expressed during different latency stages of EBV-infected B cells in which it triggers activation of cytoplasmic protein tyrosine kinases. Early studies revealed that an immunoreceptor tyrosine-based activation motif (ITAM) in the cytoplasmic N-terminus of LMP2A can trigger a transient increase of the cytosolic Ca2+ concentration similar to that observed in antigen-activated B cells when expressed as a chimeric transmembrane receptor. Even so, LMP2A was subsequently ascribed an inhibitory rather than an activating function because its expression seemed to partially inhibit B cell antigen receptor (BCR) signaling in EBV-transformed B cell lines. However, the analysis of LMP2A signaling has been hampered by the lack of cellular model systems in which LMP2A can be studied without the influence of other EBV-encoded factors. Results: We have reanalyzed LMP2A signaling using B cells in which LMP2A is expressed in an inducible manner in the absence of any other EBV signaling protein. This allowed us for the first time to monitor LMP2A signaling in statu nascendi as it occurs during the EBV life cycle in vivo. We show that mere expression of LMP2A not only stimulated protein tyrosine kinases but also induced phospholipase C-γ2-mediated Ca2+ oscillations followed by activation of the extracellular signal-regulated kinase (Erk) mitogen-activated protein kinase pathway and induction of the lytic EBV gene bzlf1. Furthermore, expression of the constitutively phosphorylated LMP2A ITAM modulated rather than inhibited BCR-induced Ca2+ mobilization. Conclusion: Our data establish that LMP2A expression has a function beyond the putative inhibition of the BCR by generating a ligand-independent cellular activation signal that may provide a molecular switch for different EBV life cycle stages and most probably contributes to EBV-associated lymphoproliferative disorders. http://www.biosignaling.com/content/10/1/9 Niklas Engels Gokhan Yigit Christoph Emmerich Dirk Czesnik Detlev Schild Jurgen Wienands Cell Communication and Signaling 2012, null:9 2012-04-03T00:00:00Z doi:10.1186/1478-811X-10-9 /content/figures/1478-811X-10-9-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 9 2012-04-03T00:00:00Z XML Background: Signaling studies in cell lines are hampered by non-physiological alterations obtained in vitro. Physiologic primary tumor cells from patients with leukemia require passaging through immune-compromised mice for amplification. The aim was to enable molecular work in patients' ALL cells by establishing siRNA transfection into cells amplified in mice. Results: We established delivering siRNA into these cells without affecting cell viability. Knockdown of single or multiple genes reduced constitutive or induced protein expression accompanied by marked signaling alterations. Conclusion: Our novel technique allows using patient-derived tumor cells instead of cell lines for signaling studies in leukemia. http://www.biosignaling.com/content/10/1/8 Ines Hofig Harald Ehrhardt Irmela Jeremias Cell Communication and Signaling 2012, null:8 2012-03-26T00:00:00Z doi:10.1186/1478-811X-10-8 /content/figures/1478-811X-10-8-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 8 2012-03-26T00:00:00Z XML Macroautophagy (commonly abbreviated as autophagy) is an evolutionary conserved lysosome-directed vesicular trafficking pathway in eukaryotic cells that mediates the lysosomal degradation of intracellular components. The cytoplasmic cargo is initially enclosed by a specific double membrane vesicle, termed the autophagosome. By this means, autophagy either helps to remove damaged organelles, long-lived proteins and protein aggregates, or serves as a recycling mechanism for molecular building blocks. Autophagy was once invented by unicellular organisms to compensate the fluctuating external supply of nutrients. In higher eukaryotes, it is strongly enhanced under various stress conditions, such as nutrient and growth factor deprivation or DNA damage. The serine/threonine kinase Atg1 was the first identified autophagy-related gene (ATG) product in yeast. The corresponding nematode homolog UNC-51, however, has additional neuronal functions. Vertebrate genomes finally encode five closely related kinases, of which UNC-51-like kinase 1 (Ulk1) and Ulk2 are both involved in the regulation of autophagy and further neuron-specific vesicular trafficking processes. This review will mainly focus on the vertebrate Ulk1/2-Atg13-FIP200 protein complex, its function in autophagy initiation, its evolutionary descent from the yeast Atg1-Atg13-Atg17 complex, as well as the additional non-autophagic functions of its components. Since the rapid nutrient- and stress-dependent cellular responses are mainly mediated by serine/threonine phosphorylation, it will summarize our current knowledge about the relevant upstream signaling pathways and the altering phosphorylation status within this complex during autophagy induction. http://www.biosignaling.com/content/10/1/7 Sebastian Alers Antje Loffler Sebastian Wesselborg Bjorn Stork Cell Communication and Signaling 2012, null:7 2012-03-13T00:00:00Z doi:10.1186/1478-811X-10-7 /content/figures/1478-811X-10-7-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 7 2012-03-13T00:00:00Z XML p38 MAP kinase is known to be activated by cellular stress finally leading to cell cycle arrest or apoptosis. Furthermore, a tumour suppressor role of p38 MAPK has been proposed. In contrast, a requirement of p38 for proliferation has also been described. To clarify this paradox, we investigated stress- and mitogen-induced p38 signalling in the same cell type using fibroblasts. We demonstrate that - in the same cell line - p38 is activated by mitogens or cellular stress, but p38-dependent signalling is different. Exposure to cellular stress, such as anisomycin, leads to a strong and persistent p38 activation independent of GTPases. As a result, MK2 and downstream the transcription factor CREB are phosphorylated. In contrast, mitogenic stimulation results in a weaker and transient p38 activation, which upstream involves small GTPases and is required for cyclin D1 induction. Consequently, the retinoblastoma protein is phosphorylated and allows G1/S transition. Our data suggest a dual role of p38 and indicate that the level and/or duration of p38 activation determines the cellular response, i.e either proliferation or cell cycle arrest. http://www.biosignaling.com/content/10/1/6 Dagmar Faust Christina Schmitt Franz Oesch Barbara Oesch-Bartlomowicz Ilona Schreck Carsten Weiss Cornelia Dietrich Cell Communication and Signaling 2012, null:6 2012-03-09T00:00:00Z doi:10.1186/1478-811X-10-6 /content/figures/1478-811X-10-6-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 6 2012-03-09T00:00:00Z XML Serum response factor (SRF) acts as a multifunctional transcription factor regulated by mutually exclusive interactions with ternary complex factors (TCFs) or myocardin-related transcription factors (MRTFs). Binding of Rho- and actin-regulated MRTF:SRF complexes to target gene promoters requires an SRF-binding site only, whereas MAPK-regulated TCF:SRF complexes in addition rely on flanking sequences present in the serum response element (SRE). Here, we report on the activation of an SRE luciferase reporter by Tip, the viral oncoprotein essentially contributing to human T-cell transformation by Herpesvirus saimiri. SRE activation in Tip-expressing Jurkat T cells could not be attributed to triggering of the MAPK pathway. Therefore, we further analyzed the contribution of MRTF complexes. Indeed, Tip also activated a reporter construct responsive to MRTF:SRF. Activation of this reporter was abrogated by overexpression of a dominant negative mutant of the MRTF-family member MAL. Moreover, enrichment of monomeric actin suppressed the Tip-induced reporter activity. Further upstream, the Rho-family GTPase Rac, was found to be required for MRTF:SRF reporter activation by Tip. Initiation of this pathway was strictly dependent on Tip's ability to interact with Lck and on the activity of this Src-family kinase. Independent of Tip, T-cell stimulation orchestrates Src-family kinase, MAPK and actin pathways to induce SRF. These findings establish actin-regulated transcription in human T cells and suggest its role in viral oncogenesis. http://www.biosignaling.com/content/10/1/5 Kristin Katsch Sarah de Jong Jens Albrecht Julia Steger Harald Genth Guido Posern Brigitte Biesinger Cell Communication and Signaling 2012, null:5 2012-03-03T00:00:00Z doi:10.1186/1478-811X-10-5 /content/figures/1478-811X-10-5-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 5 2012-03-03T00:00:00Z XML Background: Ribosomal protein S6 kinase 1(S6K1) is an evolutionary conserved kinase that is activated in response to growth factors and viral stimuli to influence cellular growth and proliferation. This downstream effector of target of rapamycin (TOR) signaling cascade is known to be directly activated by TOR- kinase mediated hydrophobic motif (HM) phosphorylation at Threonine 412 (T412). Selective loss of this phosphorylation by inactivation of TOR kinase or activation/recruitment of a phosphatase has accordingly been implicated in mediating inhibition by rapamycin.FindingsWe present evidence that baculovirus driven expression of S6K1 in insect cells (Sf9) fails to activate the enzyme and instead renders it modestly active representing 4-6 folds less activity than its fully active mammalian counterpart. Contrary to the contention that viral infection activates TOR signaling pathway, we report that BVr enzyme fails to exhibit putative TOR dependent phosphorylation at the HM and the resultant phosphorylation at the activation loop (AL) of the enzyme, correlating with the level of activity observed. Surprisingly, the BVr enzyme continued to exhibit sensitivity to rapamycin that remained unaffected by mutations compromised for TOR phosphorylation (T412A) or deletions compromised for TOR binding (ΔNH 2-46/ΔCT104). Conclusions: These data together with the ability of the BVr enzyme to resist inactivation by phosphatases indicate that inhibition by rapamycin is not mediated by any phosphorylation event in general and TOR dependent phosphorylation in particular. http://www.biosignaling.com/content/10/1/4 Mushtaq Beigh Mehvish Showkat Mahboob ul Hussain Shafat Latoo Sheikh tahir Majeed Khurshid Andrabi Cell Communication and Signaling 2012, null:4 2012-03-01T00:00:00Z doi:10.1186/1478-811X-10-4 /content/figures/1478-811X-10-4-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 4 2012-03-01T00:00:00Z XML Background: Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer characterized by invasion of carcinoma cells into dermal lymphatic vessels where they form tumor emboli over expressing adhesion molecule E-cadherin. Although invasion and metastasis are dynamic processes controlled by complex interaction between tumor cells and microenvironment the mechanisms by which soluble mediators may regulate motility and invasion of IBC cells are poorly understood. The present study investigated the effect of media conditioned by human monocytes U937 secreted cytokines, chemokines and growth factors on the expression of adhesion molecules E-cadherin and fibronectin of human IBC cell line SUM149. Furthermore, cytokines signaling pathway involved were also identified. Results: U937 secreted cytokines, chemokines and growth factors were characterized by cytokine antibody array. The major U937 secreted cytokines/chemokines were interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1/CCL2). When SUM149 cells were seeded in three dimensional (3D) models with media conditioned by U937 secreted cytokines, chemokines and growth factors; results showed: 1) changes in the morphology of IBC cells from epithelial to migratory spindle shape branched like structures; 2) Over-expression of adhesion molecule fibronectin and not E-cadherin. Further analysis revealed that over-expression of fibronectin may be mediated by IL-8 via PI3K/Akt signaling pathway. Conclusion: The present results suggested that cytokines secreted by human monocytes may promote chemotactic migration and spreading of IBC cell lines. Results also indicated that IL-8 the major secreted cytokine by U937 cells may play essential role in fibronectin expression by SUM149 cells via interaction with IL-8 specific receptors and stimulation of PI3K/Akt signaling pathway. http://www.biosignaling.com/content/10/1/3 Mona Mohamed Cell Communication and Signaling 2012, null:3 2012-02-10T00:00:00Z doi:10.1186/1478-811X-10-3 Monocyte signals in aggressive breast cancer Inflammatory breast cancer cells become more invasive when exposed to secretions from monocytes and the major drivers are identified as the cytokines chemotactic protein-1 and interleukin-8 (IL-8), with IL-8 up-regulating the adhesion molecule, fibronectin, via the PI3K/Akt signaling pathway. /content/figures/1478-811X-10-3-toc.gif Cell Communication and Signaling 1478-811X ${item.volume} 3 2012-02-10T00:00:00Z XML