Ca2+ pulsation in BY-2 cells and evidence for control of mechanosensory Ca2+-selective channels by the plasmalemmal reticulum

2005 ◽  
Vol 32 (10) ◽  
pp. 863 ◽  
Author(s):  
Barbara G. Pickard ◽  
Masaaki Fujiki
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Arabinogalactan Protein ◽  
Cation Channels ◽  
Carrier Solution ◽  
Cytoskeletal Structure ◽  
Yariv Reagent ◽  
Yariv Phenylglycoside ◽  
Plasmalemmal Reticulum ◽  
Oscillation Rate

A previously unknown cytoskeletal structure, now named the plasmalemmal reticulum (Gens et al. 2000, Protoplasma 212, 115–134), was found in cultured BY-2 tobacco cells during a search for a force-focusing mechanism that might enhance signal transduction by the cells’ mechanosensory Ca2+-selective cation channels (MCaCs). This polyhedral structure, which links cell wall, plasma membrane, and internal cytoplasm, prominently contains arabinogalactan protein (AGP). To check for reticulum-promoted Ca2+ elevation, the AGP-binding reagent (β-d-glucosyl)3 Yariv phenylglycoside has been applied to BY-2 cells expressing a free cameleon Ca2+ reporter. Ca2+ elevation was substantial and prolonged. Moreover it occurred in the nucleus as well as the cytoplasm. Cells treated with non-binding mannosyl Yariv reagent could not be discriminated from untreated controls or those treated with carrier solution alone. Supply of the MCaC inhibiter Gd3+ just before treatment with Yariv reagent prevented Ca2+ rise. These data strongly support the hypothesis that the plasmalemmal reticulum controls MCaC activity. The massive inward spread of Ca2+ suggested that entry of the ion through the channels initiated a wave of release from the ER, and YCX in the ER showed Ca2+ levels consistent with this premise. Cytosolic and nuclear Ca2+ often pulsed in control cells in near synchrony and at rates ranging from zero to five cycles per ∼20-min recording. (Pulsation was over-ridden by the applied amounts of glucosyl Yariv compound.) Suggestively but very crudely, oscillation rate was assessed as possibly correlating with stage of cell cycle. Because cell Ca2+ was lowered and pulsation was eliminated by Gd3+, MCaCs appear to participate in these endogenous fluctuations. The extent to which pulsing plays regulatory roles in relatively undifferentiated types of cells should be evaluated.

Structure of the exudate gum from Meryta sinclairii

2020 ◽  
Author(s):  
Ian Sims ◽  
Richard Furneaux
Keyword(s):  
Average Molecular Weight ◽  
Gum Arabic ◽  
Arabinogalactan Protein ◽  
Weight Average Molecular Weight ◽  
1H And 13C Nmr ◽  
One Dimensional ◽  
Linkage Analyses ◽  
Yariv Reagent ◽  
Native Tree ◽  
High Level

A gum that exudes from the wounded trunk of the New Zealand native tree Meryta sinclairii has been isolated. The gum was completely precipitated by the β-glucosyl Yariv reagent and was thus determined to be an arabinogalactan-protein (AGP). It contained >95% w/w carbohydrate and only 2% w/w protein with a high level of hydroxyproline. SEC-MALLS showed that the gum had a weight-average molecular weight of 4.45×106Da compared with 6.02×105Da for gum arabic. Constituent sugar and linkage analyses were consistent with polymers comprised of a highly branched backbone of 1,3-linked galactopyranosyl (Galp) residues, with side-chains made up of arabinofuranose- (Araf) containing oligosaccharides, terminated variously by rhamnopyranosyl (Rhap), arabinopyranosyl (Arap), Galp and glucuronopyranosyl (GlcpA) residues. Analysis by one-dimensional and two-dimensional 1H and 13C NMR experiments confirmed the linkage analyses. The structure of the gum is discussed in comparison with the structure of gum arabic and other AGPs. © 2003 Elsevier Science Ltd. All rights reserved.

scholarly journals Iodide- and Glucose-Handling Gene Expression Regulated by Sorafenib or Cabozantinib in Papillary Thyroid Cancer

2015 ◽  
Vol 100 (5) ◽  
pp. 1771-1779 ◽  
Author(s):  
Maomei Ruan ◽  
Min Liu ◽  
Qianggang Dong ◽  
Libo Chen
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Proliferation ◽  
Thyroid Cancer ◽  
Western Blot ◽  
Glucose Transporter ◽  
Signal Transduction Pathways ◽  
Papillary Thyroid ◽  
Cycle Arrest

Abstract Context: The aberrant silencing of iodide-handling genes accompanied by up-regulation of glucose metabolism presents a major challenge for radioiodine treatment of papillary thyroid cancer (PTC). Objective: This study aimed to evaluate the effect of tyrosine kinase inhibitors on iodide-handling and glucose-handling gene expression in BHP 2-7 cells harboring RET/PTC1 rearrangement. Main Outcome Measures: In this in vitro study, the effects of sorafenib or cabozantinib on cell growth, cycles, and apoptosis were investigated by cell proliferation assay, cell cycle analysis, and Annexin V-FITC apoptosis assay, respectively. The effect of both agents on signal transduction pathways was evaluated using the Western blot. Quantitative real-time PCR, Western blot, immunofluorescence, and radioisotope uptake assays were used to assess iodide-handling and glucose-handling gene expression. Results: Both compounds inhibited cell proliferation in a time-dependent and dose-dependent manner and caused cell cycle arrest in the G0/G1 phase. Sorafenib blocked RET, AKT, and ERK1/2 phosphorylation, whereas cabozantinib blocked RET and AKT phosphorylation. The restoration of iodide-handling gene expression and inhibition of glucose transporter 1 and 3 expression could be induced by either drug. The robust expression of sodium/iodide symporter induced by either agent was confirmed, and 125I uptake was correspondingly enhanced. 18F-fluorodeoxyglucose accumulation was significantly decreased after treatment by either sorafenib or cabozantinib. Conclusions: Sorafenib and cabozantinib had marked effects on cell proliferation, cell cycle arrest, and signal transduction pathways in PTC cells harboring RET/PTC1 rearrangement. Both agents could be potentially used to enhance the expression of iodide-handling genes and inhibit the expression of glucose transporter genes.

scholarly journals SAM68: Signal Transduction and RNA Metabolism in Human Cancer

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Paola Frisone ◽  
Davide Pradella ◽  
Anna Di Matteo ◽  
Elisa Belloni ◽  
Claudia Ghigna ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Nuclear Export ◽  
Cell Biology ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Splice Variants ◽  
Human Cancer ◽  
Rna Metabolism ◽  
Regulatory Sequences

Alterations in expression and/or activity of splicing factors as well as mutations incis-acting splicing regulatory sequences contribute to cancer phenotypes. Genome-wide studies have revealed more than 15,000 tumor-associated splice variants derived from genes involved in almost every aspect of cancer cell biology, including proliferation, differentiation, cell cycle control, metabolism, apoptosis, motility, invasion, and angiogenesis. In the past decades, several RNA binding proteins (RBPs) have been implicated in tumorigenesis. SAM68 (SRC associated in mitosis of 68 kDa) belongs to the STAR (signal transduction and activation of RNA metabolism) family of RBPs. SAM68 is involved in several steps of mRNA metabolism, from transcription to alternative splicing and then to nuclear export. Moreover, SAM68 participates in signaling pathways associated with cell response to stimuli, cell cycle transitions, and viral infections. Recent evidence has linked this RBP to the onset and progression of different tumors, highlighting misregulation of SAM68-regulated splicing events as a key step in neoplastic transformation and tumor progression. Here we review recent studies on the role of SAM68 in splicing regulation and we discuss its contribution to aberrant pre-mRNA processing in cancer.

Mathematical modeling and sensitivity analysis of G1/S phase in the cell cycle including the DNA-damage signal transduction pathway

Biosystems ◽  
2008 ◽  
Vol 94 (1-2) ◽  
pp. 109-117 ◽  
Author(s):  
Kazunari Iwamoto ◽  
Yoshihiko Tashima ◽  
Hiroyuki Hamada ◽  
Yukihiro Eguchi ◽  
Masahiro Okamoto
Keyword(s):  
Mathematical Modeling ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Sensitivity Analysis ◽  
Dna Damage ◽  
Signal Transduction Pathway ◽  
S Phase ◽  
Transduction Pathway

scholarly journals Coupling of Cell Division and Differentiation in Arabidopsis thaliana Cultured Cells with Interaction of Ethylene and ABA Signaling Pathways

Life ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 15
Author(s):  
Novikova ◽  
Stepanchenko ◽  
Zorina ◽  
Nosov ◽  
Rakitin ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Cell Differentiation ◽  
Signal Transduction Pathway ◽  
Transduction Pathway ◽  
Aba Signaling ◽  
Exogenous Aba ◽  
Ethylene Signal

Recent studies indicate direct links between molecular cell cycle and cell differentiation machineries. Ethylene and abscisic acid (ABA) are known to affect cell division and differentiation, but the mechanisms of such effects are poorly understood. As ethylene and ABA signaling routes may interact, we examined their involvement in cell division and differentiation in cell tissue cultures derived from several Arabidopsis thaliana plants: wild type (Col-0), and ethylene-insensitive mutants etr1-1, ctr1-1, and ein2-1. We designed an experimental setup to analyze the growth-related parameters and molecular mechanisms in proliferating cells upon short exposure to ABA. Here, we provide evidence for the ethylene–ABA signaling pathways’ interaction in the regulation of cell division and differentiation as follows: (1) when the ethylene signal transduction pathway is functionally active (Col-0), the cells actively proliferate, and exogenous ABA performs its function as an inhibitor of DNA synthesis and division; (2) if the ethylene signal is not perceived (etr1-1), then, in addition to cell differentiation (tracheary elements formation), cell death can occur. The addition of exogenous ABA can rescue the cells via increasing proliferation; (3) if the ethylene signal is perceived, but not transduced (ein2-1), then cell differentiation takes place—the latter is enhanced by exogenous ABA while cell proliferation is reduced; (4) when the signal transduction pathway is constitutively active, the cells begin to exit the cell cycle and proceed to endo-reduplication (ctr1-1). In this case, the addition of exogenous ABA promotes reactivation of cell division.

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