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Cellular Signalling

Toshiaki Tanaka, Kaoru Goto, Mitsuyoshi Iino
Sec8 is one of the subunits of the exocyst, which is an evolutionarily conserved complex of eight proteins, comprising Sec3 (EXOC1), Sec5 (EXOC2), Sec6 (EXOC3), Sec8 (EXOC4), Sec10 (EXOC5), Sec15 (EXOC6), Exo70 (EXOC7), and Exo84 (EXOC8) subunits. Sec8 knockout mice embryos initiate gastrulation but are unable to progress beyond the primitive streak stage and die shortly. During embryonic development, the first epithelial-mesenchymal transition (EMT) event occurs at gastrulation. Sec8 may be involved in the early embryonic development through EMT...
October 18, 2016: Cellular Signalling
Michael B Lazarus, Rebecca S Levin, Kevan M Shokat
Elongation Factor-2 Kinase (eEF2K) in an unusual mammalian enzyme that has one known substrate, elongation factor-2. It belongs to a class of kinases, called alpha kinases, that has little sequence identity to the >500 conventional protein kinases, but performs the same reaction and has similar catalytic residues. The phosphorylation of eEF2 blocks translation elongation, which is thought to be critical to regulating cellular energy usage. Here we report a system for discovering new substrates of alpha kinases and identify the first new substrates of eEF2K including AMPK and alpha4, and determine a sequence motif for the kinase that shows a requirement for threonine residues as the target of phosphorylation...
October 17, 2016: Cellular Signalling
Schammim Ray Amith, Krista Marie Vincent, Jodi Marie Wilkinson, Lynne Marie Postovit, Larry Fliegel
Mounting evidence supports a major role for the Na(+)/H(+) exchanger NHE1 in cancer progression and metastasis. NHE1 is hyperactive at the onset of oncogenic transformation, resulting in intracellular alkalinization and extracellular microenvironmental acidification. These conditions promote invasion and facilitate metastasis. However, the signal pathways governing the regulation of exchanger activity are still unclear. This is especially important in the aggressively metastatic, triple-negative basal breast cancer subtype...
October 15, 2016: Cellular Signalling
Sili Liu, Gabrielle L Boulianne
Neuralized Homology Repeats (NHRs) were first identified in Neuralized, an E3-ubiquitin ligase that plays a key role in the Notch signalling pathway. Since their original discovery, NHR domains have been shown to regulate protein-protein interactions in a broad range of developmental processes and in a wide variety of species from flies to humans. The NHR family of proteins can be categorized into three groups: (1) those that contain a RING finger, (2) those that contain a SOCS box and, (3) those that only have NHR domains...
October 14, 2016: Cellular Signalling
Elisa Wiedemann, Stefanie Jellinghaus, Georg Ende, Antje Augstein, Ronny Sczech, Ben Wielockx, Sönke Weinert, Ruth H Strasser, David M Poitz
Endothelial migration and proliferation are fundamental processes in angiogenesis and wound healing of injured or inflamed vessels. The present study aimed to investigate the regulation of the Eph/ephrin-system during endothelial proliferation and the impact of the ligand ephrin-A1 on proliferation and migration of human umbilical venous (HUVEC) and arterial endothelial cells (HUAEC). Endothelial cells that underwent contact inhibition showed a massive induction of ephrin-A1. In contrast, an injury to a confluent endothelial layer, associated with induction of migration and proliferation, showed reduced ephrin-A1 levels...
October 11, 2016: Cellular Signalling
Susanne Muehlich, Margot Rehm, Astrid Ebenau, Margarete Goppelt-Struebe
Changes in cell morphology that involve alterations of the actin cytoskeleton are a hallmark of diseased renal tubular epithelial cells. While the impact of actin remodeling on gene expression has been analyzed in many model systems based on cell lines, this study investigated human primary tubular epithelial cells isolated from healthy parts of tumor nephrectomies. Latrunculin B (LatB) and cytochalasin D (CytoD) were used to modulate G-actin levels in a receptor-independent manner. Both compounds (at 0.5μM) profoundly altered F-actin structures in a Rho kinase-dependent manner, but only CytoD strongly induced the pro-fibrotic factor CTGF (connective tissue growth factor)...
October 7, 2016: Cellular Signalling
Laura Hildebrand, Katja Stange, Alexandra Deichsel, Manfred Gossen, Petra Seemann
Patients with Fibrodysplasia Ossificans Progressiva (FOP) suffer from ectopic bone formation, which progresses during life and results in dramatic movement restrictions. Cause of the disease are point mutations in the Activin A receptor type 1 (ACVR1), with p.R206H being most common. In this study we compared the signalling responses of ACVR1(WT) and ACVR1(R206H) to different ligands. ACVR1(WT), but not ACVR1(R206H) inhibited BMP signalling of BMP2 or BMP4 in a ligand binding domain independent manner. Likewise, the basal BMP signalling activity of the receptor BMPR1A or BMPR1B was inhibited by ACVR1(WT), but enhanced by ACVR1(R206H)...
October 4, 2016: Cellular Signalling
Jeanna Jacobi, Mónica García-Barros, Shyam Rao, Jimmy A Rotolo, Chris Thompson, Aviram Mizrachi, Regina Feldman, Katia Manova, Alicja Bielawska, Jacek Bielawska, Zvi Fuks, Richard Kolesnick, Adriana Haimovitz-Friedman
Despite great promise, combining anti-angiogenic and conventional anti-cancer drugs has produced limited therapeutic benefit in clinical trials, presumably because mechanisms of anti-angiogenic tissue response remain only partially understood. Here we define a new paradigm, in which anti-angiogenic drugs can be used to chemosensitize tumors by targeting the endothelial acid sphingomyelinase (ASMase) signal transduction pathway. We demonstrate that paclitaxel and etoposide, but not cisplatin, confer ASMase-mediated endothelial injury within minutes...
October 1, 2016: Cellular Signalling
Xiujuan Zhang, Ying Chen, Ying Ye, Jianfeng Wang, Hong Wang, Guohong Yuan, Zhe Lin, Yihui Wu, Yan Zhang, Xinhua Lin
Wnt signaling plays essential roles in both embryonic pattern formation and postembryonic tissue homoestasis. High levels of Wnt activity repress foregut identity and facilitate hindgut fate through forming a gradient of Wnt signaling activity along the anterior-posterior axis. Here, we examined the mechanisms of Wnt signaling in hindgut development by differentiating human embryonic stem cells (hESCs) into the hindgut progenitors. We observed severe morphological changes when Wnt signaling was blocked by using Wnt antagonist Dkk1...
September 29, 2016: Cellular Signalling
Li-Ni Zhao, Ping Wang, Yun-Hui Liu, Heng Cai, Jun Ma, Li-Bo Liu, Zhuo Xi, Zhi-Qing Li, Xiao-Bai Liu, Yi-Xue Xue
Malignant glioma is undoubtedly the most vascularized tumor of central nervous system. Angiogenesis, playing a predominant role in tumor progression, is widely considered as a key point of tumor treatment. The aim of this study was to investigate the potential effects of miR-383 on proliferation, migration, tube formation and angiogenesis of glioma-exposed endothelial cells (GECs) in vitro and to further elucidate its possible molecular mechanisms. The expression of miR-383 in GECs was significantly downregulated compared with that in normal endothelial cells (ECs)...
September 27, 2016: Cellular Signalling
Xinyong Tian, Tomomi Ohmura, Alok S Shah, Sophia Son, Yufeng Tian, Anna A Birukova
Rapid changes in microtubule (MT) polymerization dynamics affect regional activity of small GTPases RhoA and Rac1, which play a key role in the regulation of actin cytoskeleton and endothelial cell (EC) permeability. This study tested the role of End Binding Protein-1 (EB1) in the mechanisms of increased and decreased EC permeability caused by thrombin and hepatocyte growth factor (HGF) and mediated by RhoA and Rac1 GTPases, respectively. Stimulation of human lung EC with thrombin inhibited peripheral MT growth, which was monitored by morphological and biochemical evaluation of peripheral MT and the levels of stabilized MT...
September 23, 2016: Cellular Signalling
Maeve Kiely, David R Adams, Sheri L Hayes, Rosemary O'Connor, George S Baillie, Patrick A Kiely
Conflicting reports implicate the scaffolding protein RACK1 in the progression of breast cancer. RACK1 has been identified as a key regulator downstream of growth factor and adhesion signalling and as a direct binding partner of PP2A. Our objective was to further characterise the interaction between PP2A and RACK1 and to advance our understanding of this complex in breast cancer cells. We examined how the PP2A holoenzyme is assembled on the RACK1 scaffold in MCF-7 cells. We used immobilized peptide arrays representing the entire PP2A-catalytic subunit to identify candidate amino acids on the C subunit of PP2A that might be involved in binding of RACK1...
September 3, 2016: Cellular Signalling
Lixing Zhang, Mohammad Adileh, Maria Laura Martin, Stefan Klingler, Julie White, Xiaojing Ma, Louise R Howe, Anthony M C Brown, Richard Kolesnick
Recent evidence suggests that mammary cells expressing R-spondin receptor and Wnt pathway regulator Lgr5, regarded as a stem cell marker in multiple tissues, might represent mammary stem cells (MaSCs). Whether L gr5 marks a multipotent subpopulation of Lin-CD24(low/med)CD49f(high) MaSCs remains controversial. To some extent the differing results reflect different assays used to assess properties of stemness, including lineage tracing in vivo, mammosphere culture, and mammary fat pad transplantation assays. To address this issue directly, we isolated Lgr5(+) cells from mammary glands of Lgr5-lacZ mice and established organoids based on principles adapted from studies of Wnt-driven Lgr5(+) cell populations in other organs...
August 7, 2016: Cellular Signalling
Deng Pan, Somdutta Roy, Philippe Gascard, Jianxin Zhao, Chira Chen-Tanyolac, Thea D Tlsty
Endogenous Plastic Somatic (ePS) cells isolated from adult human tissues exhibit extensive lineage plasticity in vitro and in vivo. Here we visualize these rare ePS cells in a latent state, i.e. lacking SOX2, OCT3/4 and NANOG (SON) expression, in non-diseased breast specimens through immunohistochemical analysis of previously identified ePS-specific biomarkers (CD73(+), EpCAM(+) and CD90(-)). We also report a novel mechanism by which these latent ePS cells acquire SON expression and plasticity in vitro. Four extracellular factors are necessary for the acquisition of SON expression and lineage plasticity in ePS cells: adenosine (which is produced by the 5' ecto-nucleotidase CD73 and activates in turn the PKA-dependent IL6/STAT3 pathway through the adenosine receptor ADORA2b), IL6, FGF2 and ACTIVIN A...
December 2016: Cellular Signalling
Glen M Scholz, Nur S Sulaiman, Sahar Al Baiiaty, Mei Qi Kwa, Eric C Reynolds
Keratinocytes are central to the barrier functions of surface epithelia, such as the gingiva and epidermis. RIPK4 is a key regulator of keratinocyte differentiation; however, the signalling pathways in which it functions remain poorly defined. In this study, we identified a regulatory relationship between RIPK4 and ELF3, an ETS family transcription factor. RIPK4 was shown to be important for the upregulation of ELF3 gene expression by the PKC agonist PMA in both oral and epidermal keratinocytes. RIPK4 promotes keratinocyte differentiation in part by phosphorylating and thereby activating the IRF6 transcription factor...
December 2016: Cellular Signalling
Jisoo Park, Quangdon Tran, Kisun Mun, Kouhei Masuda, So Hee Kwon, Seon-Hwan Kim, Dong-Hoon Kim, George Thomas, Jongsun Park
The major biological function of mitochondria is to generate cellular energy through oxidative phosphorylation. Apart from cellular respiration, mitochondria also play a key role in signaling processes, including aging and cancer metabolism. It has been shown that S6K1-knockout mice are resistant to obesity due to enhanced beta-oxidation, with an increased number of large mitochondria. Therefore, in this report, the possible involvement of S6K1 in regulating mitochondria dynamics and function has been investigated in stable lenti-shS6K1-HeLa cells...
December 2016: Cellular Signalling
Kati Kemppainen, Nina Wentus, Taru Lassila, Asta Laiho, Kid Törnquist
Sphingosylphosphorylcholine (SPC) is a bioactive sphingolipid which regulates many cancer-related processes, including cellular proliferation. The Hippo signaling pathway consists of a cascade of tumor suppressive kinases Mst1/2 and Lats1/2 and their downstream targets YAP and TAZ which are generally pro-proliferative transcriptional regulators. Direct phosphorylation by Lats1/2 causes inhibition or degradation of YAP/TAZ and down-regulation of their target genes. We found SPC treatment of MDA-MB-435S breast cancer cells to strongly inhibit their proliferation and to induce a sustained Lats2 protein expression (6-24h)...
December 2016: Cellular Signalling
Doan Duy Hai Tran, Alexandra Koch, Aldrige Allister, Shashank Saran, Florian Ewald, Martina Koch, Björn Nashan, Teruko Tamura
Over 100 putative driver genes that are associated with multiple recurrently altered pathways were detected in hepatocellular carcinoma (HCC), suggesting that multiple pathways will need to be inhibited for any therapeutic method to be effective. In this context, functional modification of the RNA regulating protein, tristetraprolin (TTP) that regulates approximately 2500 genes represents a promising strategy in HCC therapy. Since overexpression of TTP induces cell death in all cell types, it would be useful to target the regulator of TTP...
December 2016: Cellular Signalling
Ilaria Canobbio, Caterina Visconte, Barbara Oliviero, Gianni Guidetti, Marta Zarà, Giordano Pula, Mauro Torti
Vascular dysfunctions and Alzheimer's disease show significant similarities and overlaps. Cardiovascular risk factors (hypercholesterolemia, hypertension, obesity, atherosclerosis and diabetes) increase the risk of vascular dementia and Alzheimer's disease. Conversely, Alzheimer's patients have considerably increased predisposition of ischemic and hemorrhagic strokes. Platelets are major players in haemostasis and thrombosis and are involved in inflammation. We have investigated morphology and function of platelets in 3xTg-AD animals, a consolidate murine model for Alzheimer's disease...
December 2016: Cellular Signalling
Dakshayini G Chandrashekarappa, Rhonda R McCartney, Allyson F O'Donnell, Martin C Schmidt
Saccharomyces cerevisiae express three isoforms of Snf1 kinase that differ by which β subunit is present, Gal83, Sip1 or Sip2. Here we investigate the abundance, activation, localization and signaling specificity of the three Snf1 isoforms. The relative abundance of these isoforms was assessed by quantitative immunoblotting using two different protein extraction methods and by fluorescence microscopy. The Gal83 containing isoform is the most abundant in all assays while the abundance of the Sip1 and Sip2 isoforms is typically underestimated especially in glass-bead extractions...
December 2016: Cellular Signalling
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