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https://www.readbyqxmd.com/read/27913219/tbx2-regulates-anterior-neural-specification-by-repressing-fgf-signaling-pathway
#1
Gun-Sik Cho, Dong-Seok Park, Sun-Cheol Choi, Jin-Kwan Han
During early embryogenesis, FGF signals regulate the antero-posterior (AP) patterning of the neural plate by promoting posterior cell fates. In particular, BMP signal-mediated attenuation of FGF pathway plays a critical role in the determination of the anterior neural region. Here we show that Tbx2, a T-box transcriptional repressor regulates anterior neural specification by suppressing FGF8 signaling pathway in Xenopus embryo. Tbx2 is expressed in the anterior edge of the neural plate in early neurulae. Overexpression and knockdown of Tbx2 induce expansion and reduction in the expression of anterior neural markers, respectively...
November 29, 2016: Developmental Biology
https://www.readbyqxmd.com/read/27906638/gene-duplications-and-losses-among-vertebrate-deoxyribonucleoside-kinases-of-the-non-tk1-family
#2
Zeeshan Mutahir, Louise Slot Christiansen, Anders R Clausen, Martin W Berchtold, Zoran Gojkovic, Birgitte Munch-Petersen, Wolfgang Knecht, Jure Piškur
Deoxyribonucleoside kinases (dNKs) salvage deoxyribonucleosides (dNs) and catalyze the rate limiting step of this salvage pathway by converting dNs into corresponding monophosphate forms. These enzymes serve as an excellent model to study duplicated genes and their evolutionary history. So far, among vertebrates only four mammalian dNKs have been studied for their substrate specificity and kinetic properties. However, some vertebrates, such as fish, frogs, and birds, apparently possess a duplicated homolog of deoxycytidine kinase (dCK)...
December 2016: Nucleosides, Nucleotides & Nucleic Acids
https://www.readbyqxmd.com/read/27906618/expression-of-a-human-npt1-slc17a1-missense-variant-which-increases-urate-export
#3
Masayuki Sakiyama, Hirotaka Matsuo, Shushi Nagamori, Wei Ling, Yusuke Kawamura, Akiyoshi Nakayama, Toshihide Higashino, Toshinori Chiba, Kimiyoshi Ichida, Yoshikatsu Kanai, Nariyoshi Shinomiya
Human sodium-dependent phosphate cotransporter type 1 (NPT1/SLC17A1) is one of the urate transporters in the kidney. Our recent study revealed that a common missense variant, I269T (rs1165196), of NPT1 decreases the risk of renal underexcretion gout. Moreover, we demonstrated that human NPT1 is localized to the apical membrane of the renal proximal tubule, and that I269T is the gain-of-function variant which increases the NPT1-mediated urate export. However, the mechanism by which I269T variant increases the urate export remains to be clarified...
December 2016: Nucleosides, Nucleotides & Nucleic Acids
https://www.readbyqxmd.com/read/27903806/oschx14-is-involved-in-the-k-homeostasis-in-rice-oryza-sativa-flowers
#4
Yi Chen, Jingkun Ma, Anthony J Miller, Bingbing Luo, Mei Wang, Zhen Zhu, Pieter B F Ouwerkerk
Previously we showed in the osjar1 mutants that the lodicule senescence which controls the closing of rice flowers was delayed. This resulted in florets staying open longer when compared with the wild type. The gene OsJAR1 is silenced in osjar1 mutants and is a key member of the jasmonic acid (JA) signaling pathway. We found that K concentrations in lodicules and flowers of osjar1-2 were significantly elevated compared with the wild type, indicating that K(+) homeostasis may play a role in regulating the closure of rice flowers...
July 2016: Plant & Cell Physiology
https://www.readbyqxmd.com/read/27901080/block-of-nicotinic-acetylcholine-receptors-by-philanthotoxins-is-strongly-dependent-on-their-subunit-composition
#5
Hamid S Kachel, Rohit N Patel, Henrik Franzyk, Ian R Mellor
Philanthotoxin-433 (PhTX-433) is an active component of the venom from the Egyptian digger wasp, Philanthus triangulum. PhTX-433 inhibits several excitatory ligand-gated ion channels, and to improve selectivity two synthetic analogues, PhTX-343 and PhTX-12, were developed. Previous work showed a 22-fold selectivity of PhTX-12 over PhTX-343 for embryonic muscle-type nicotinic acetylcholine receptors (nAChRs) in TE671 cells. We investigated their inhibition of different neuronal nAChR subunit combinations as well as of embryonic muscle receptors expressed in Xenopus oocytes...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27898723/pth1r-mutants-found-in-patients-with-primary-failure-of-tooth-eruption-disrupt-g-protein-signaling
#6
Hariharan Subramanian, Frank Döring, Sina Kollert, Natalia Rukoyatkina, Julia Sturm, Stepan Gambaryan, Angelika Stellzig-Eisenhauer, Philipp Meyer-Marcotty, Martin Eigenthaler, Erhard Wischmeyer
AIM: Primary failure of tooth eruption (PFE) is causally linked to heterozygous mutations of the parathyroid hormone receptor (PTH1R) gene. The mutants described so far lead to exchange of amino acids or truncation of the protein that may result in structural changes of the expressed PTH1R. However, functional effects of these mutations have not been investigated yet. MATERIALS AND METHODS: In HEK293 cells, PTH1R wild type was co-transfected with selected PTH1R mutants identified in patients with PFE...
2016: PloS One
https://www.readbyqxmd.com/read/27898416/sgk3-sensitivity-of-large-conductance-ca2-activated-k-channel
#7
Musaab Ahmed, Myriam Fezai, Florian Lang
BACKGROUND/AIMS: Large conductance Ca2+-activated K+ channels (maxi K+ channels or BK channels) are rapidly activated by increase of cytosolic Ca2+ activity. The channels participate in the regulation of diverse functions including neuronal excitation and cell volume. The BK channels may be modified by kinases. Channel regulating kinases include the serum & glucocorticoid inducible kinase 3 (SGK3). The present study explored whether SGK3 modifies the activity of BK channels. METHODS: cRNA encoding the Ca2+ insensitive BK channel mutant BKM513I+Δ899-903 was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding wild-type SGK3, constitutively active S419DSGK3, or catalytically inactive K191NSGK3...
November 30, 2016: Neuro-Signals
https://www.readbyqxmd.com/read/27896006/ultrahigh-speed-phase-sensitive-full-field-interferometric-confocal-microscopy-for-quantitative-microscale-physiology
#8
Ikbal Sencan, Brendan K Huang, Yong Bian, Emily Mis, Mustafa K Khokha, Hui Cao, Michael Choma
We developed ultra-high-speed, phase-sensitive, full-field reflection interferometric confocal microscopy (FFICM) for the quantitative characterization of in vivo microscale biological motions and flows. We demonstrated 2D frame rates in excess of 1 kHz and pixel throughput rates up to 125 MHz. These fast FFICM frame rates were enabled by the use of a low spatial coherence, high-power laser source. Specifically, we used a dense vertical cavity surface emitting laser (VCSEL) array that synthesized low spatial coherence light through a large number of narrowband, mutually-incoherent emitters...
November 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/27894914/the-unexpected-teratogenicity-of-rxr-antagonist-uvi3003-via-activation-of-ppar%C3%AE-in-xenopus-tropicalis
#9
Jingmin Zhu, Amanda Janesick, Lijiao Wu, Lingling Hu, Weiyi Tang, Bruce Blumberg, Huahong Shi
The RXR agonist (triphenyltin, TPT) and the RXR antagonist (UVI3003) both show teratogenicity and, unexpectedly, induce similar malformations in Xenopus tropicalis embryos. In the present study, we exposed X. tropicalis embryos to UVI3003 in seven specific developmental windows and identified changes in gene expression. We further measured the ability of UVI3003 to activate Xenopus RXRα (xRXRα) and PPARγ (xPPARγ) in vitro and in vivo. We found that UVI3003 activated xPPARγ either in Cos7 cells (in vitro) or Xenopus embryos (in vivo)...
November 25, 2016: Toxicology and Applied Pharmacology
https://www.readbyqxmd.com/read/27893298/replication-checkpoint-suppression-and-structure-of-centromeric-dna
#10
Francesco Romeo, Lucia Falbo, Vincenzo Costanzo
Human centromeres contain large amounts of repetitive DNA sequences known as α satellite DNA, which can be difficult to replicate and whose functional role is unclear. Recently, we have characterized protein composition, structural organization and checkpoint response to stalled replication forks of centromeric chromatin reconstituted in Xenopus laevis egg extract. We showed that centromeric DNA has high affinity for SMC2-4 subunits of condensins and for CENP-A, it is enriched for DNA repair factors and suppresses the ATR checkpoint to ensure its efficient replication...
November 28, 2016: Nucleus
https://www.readbyqxmd.com/read/27888632/ventx-induces-expansion-of-primitive-erythroid-cells-and-contributes-to-the-development-of-acute-myeloid-leukemia-in-mice
#11
Eva Gentner, Naidu M Vegi, Medhanie A Mulaw, Tamoghna Mandal, Shiva Bamezai, Rainer Claus, Alpaslan Tasdogan, Leticia Quintanilla-Martinez, Alexander Grunenberg, Konstanze Döhner, Hartmut Döhner, Lars Bullinger, Torsten Haferlach, Christian Buske, Vijay P S Rawat, Michaela Feuring-Buske
Homeobox genes are key regulators in normal and malignant hematopoiesis. The human Vent-like homeobox gene VENTX, a putative homolog of the Xenopus laevis Xvent-2 gene, was shown to be highly expressed in normal myeloid cells and in patients with acute myeloid leukemia. We now demonstrate that constitutive expression of VENTX suppresses expression of genes responsible for terminal erythroid differentiation in normal CD34+ stem and progenitor cells. Transplantation of bone marrow progenitor cells retrovirally engineered to express VENTX caused massive expansion of primitive erythroid cells and partly acute erythroleukemia in transplanted mice...
November 24, 2016: Oncotarget
https://www.readbyqxmd.com/read/27875771/nemo-like-kinase-1-nlk1-and-paraxial-protocadherin-papc-cooperatively-control-xenopus-gastrulation-through-regulation-of-wnt-planar-cell-polarity-pcp-signaling
#12
Rahul Kumar, Anja Ciprianidis, Susanne Theiß, Herbert Steinbeißer, Lilian T Kaufmann
The Wnt/planar cell polarity (PCP) pathway directs cell migration during vertebrate gastrulation and is essential for proper embryonic development. Paraxial protocadherin (PAPC, Gene Symbol pcdh8.2) is an important activator of Wnt/PCP signaling during Xenopus gastrulation, but how PAPC activity is controlled is incompletely understood. Here we show that Nemo-like kinase 1 (Nlk1), an atypical mitogen-activated protein (MAP) kinase, physically associates with the C-terminus of PAPC. This interaction mutually stabilizes both proteins by inhibiting polyubiquitination...
October 28, 2016: Differentiation; Research in Biological Diversity
https://www.readbyqxmd.com/read/27875263/reversible-developmental-stasis-in-response-to-nutrient-availability-in-the-xenopus-laevis-cns
#13
C R McKeown, C K Thompson, H T Cline
Many organisms confront intermittent nutrient restriction, but the mechanisms to cope with nutrient fluctuations during development are not well understood. This is particularly true of the brain, the development and function of which is energy intensive. Here we examine the effects of nutrient availability on visual system development in Xenopus laevis tadpoles. During the first week of development, tadpoles draw nutrients from maternally-provided yolk. Upon yolk depletion, animals forage for food. By altering access to external nutrients after yolk depletion, we identified a period of reversible stasis during tadpole development...
November 10, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27872142/cohesin-acetylation-and-wapl-pds5-oppositely-regulate-translocation-of-cohesin-along-dna
#14
Mai Kanke, Eri Tahara, Pim J Huis In't Veld, Tomoko Nishiyama
Cohesin is a ring-shaped protein complex that plays a crucial role in sister chromatid cohesion and gene expression. The dynamic association of cohesin with chromatin is essential for these functions. However, the exact nature of cohesin dynamics, particularly cohesin translocation, remains unclear. We evaluated the dynamics of individual cohesin molecules on DNA and found that the cohesin core complex possesses an intrinsic ability to traverse DNA in an adenosine triphosphatase (ATPase)-dependent manner. Translocation ability is suppressed in the presence of Wapl-Pds5 and Sororin; this suppression is alleviated by the acetylation of cohesin and the action of mitotic kinases...
November 21, 2016: EMBO Journal
https://www.readbyqxmd.com/read/27871365/mechanism-and-regulation-of-dna-protein-crosslink-repair-by-the-dna-dependent-metalloprotease-sprtn
#15
Julian Stingele, Roberto Bellelli, Ferdinand Alte, Graeme Hewitt, Grzegorz Sarek, Sarah L Maslen, Susan E Tsutakawa, Annabel Borg, Svend Kjær, John A Tainer, J Mark Skehel, Michael Groll, Simon J Boulton
Covalent DNA-protein crosslinks (DPCs) are toxic DNA lesions that interfere with essential chromatin transactions, such as replication and transcription. Little was known about DPC-specific repair mechanisms until the recent identification of a DPC-processing protease in yeast. The existence of a DPC protease in higher eukaryotes is inferred from data in Xenopus laevis egg extracts, but its identity remains elusive. Here we identify the metalloprotease SPRTN as the DPC protease acting in metazoans. Loss of SPRTN results in failure to repair DPCs and hypersensitivity to DPC-inducing agents...
November 17, 2016: Molecular Cell
https://www.readbyqxmd.com/read/27870909/variability-of-rheotaxis-behaviors-in-larval-bullfrogs-highlights-species-diversity-in-lateral-line-function
#16
Erika E A Brown, Andrea Megela Simmons
The morphology and distribution of lateral line neuromasts vary between ecomorphological types of anuran tadpoles, but little is known about how this structural variability contributes to differences in lateral-line mediated behaviors. Previous research identified distinct differences in one such behavior, positive rheotaxis towards the source of a flow, in two tadpole species, the African clawed frog (Xenopus laevis; type 1) and the American bullfrog (Rana catesbeiana; type 4). Because these two species had been tested under different flow conditions, we re-evaluated these findings by quantifying flow-sensing behaviors of bullfrog tadpoles in the same flow field in which X...
2016: PloS One
https://www.readbyqxmd.com/read/27870636/marveld3-regulates-the-c-jun-n-terminal-kinase-pathway-during-eye-development-in-xenopus
#17
Barbara Vacca, Elena Sanchez-Heras, Emily Steed, Maria S Balda, Shin-Ichi Ohnuma, Noriaki Sasai, Roberto Mayor, Karl Matter
Ocular morphogenesis requires several signalling pathways controlling the expression of transcription factors and cell-cycle regulators. However, despite a well-known mechanism, the dialogue between those signals and factors remains to be unveiled. Here, we identify a requirement for MarvelD3, a tight junction transmembrane protein, in eye morphogenesis in Xenopus MarvelD3 depletion led to an abnormally pigmented eye or even an eye-less phenotype, which was rescued by ectopic MarvelD3 expression. Altering MarvelD3 expression led to deregulated expression of cell-cycle regulators and transcription factors required for eye development...
November 15, 2016: Biology Open
https://www.readbyqxmd.com/read/27870267/thyroid-hormone-induced-activation-of-notch-signaling-is-required-for-adult-intestinal-stem-cell-development-during-xenopus-laevis-metamorphosis
#18
Takashi Hasebe, Kenta Fujimoto, Mitsuko Kajita, Liezhen Fu, Yun-Bo Shi, Atsuko Ishizuya-Oka
In Xenopus laevis intestine during metamorphosis, the larval epithelial cells are removed by apoptosis, and the adult epithelial stem (AE) cells appear concomitantly. They proliferate and differentiate to form the adult epithelium (Ep). Thyroid hormone (TH) is well established to trigger this remodeling by regulating the expression of various genes including Notch receptor. To study the role of Notch signaling, we have analyzed the expression of its components, including the ligands (DLL and Jag), receptor (Notch), and targets (Hairy), in the metamorphosing intestine by real-time reverse transcription-polymerase chain reaction and in situ hybridization or immunohistochemistry...
November 21, 2016: Stem Cells
https://www.readbyqxmd.com/read/27864772/use-of-xenopus-laevis-oocytes-to-study-auxin-transport
#19
Astrid Fastner, Birgit Absmanner, Ulrich Z Hammes
Xenopus laevis oocytes are an expression system that is particularly well suited for the characterization of membrane transporters. Oocytes possess only very little endogenous transport systems and therefore transporters can be studied with a high signal-to-noise ratio. This book chapter provides the basic methods to use Xenopus oocytes for the characterization of transporters by radiotracer experiments. While the methods described here were established to study auxin transport they can easily be adapted to study other hormone transporters and their substrates...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27864379/foxn4-promotes-gene-expression-required-for-multiple-motile-cilia-formation
#20
Evan P Campell, Ian K Quigley, Chris Kintner
Multiciliated cell (MCC) differentiation involves extensive organelle biogenesis required to extend hundreds of motile cilia. Key transcriptional regulators have been identified that drive gene expression required for organelle biogenesis during MCC differentiation, which are activated by, and act downstream, of two related, small coiled-coil proteins, Multicilin and Gemc1. Here we identify foxn4 as a new downstream target of Multicilin required for MCC differentiation in the Xenopus skin. When Foxn4 activity is inhibited in Xenopus embryos, MCCs show transient ciliogenesis defects similar to those observed in mutants in Foxj1, a known key regulator of genes required for motile ciliation...
November 18, 2016: Development
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