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Sample records for beta-catenin signaling levels

  1. Negative regulation of {beta}-catenin/Tcf signaling by naringenin in AGS gastric cancer cell

    SciTech Connect

    Lee, Ju Hyung; Park, Chi Hoon; Jung, Kyung Chae; Rhee, Ho Sung; Yang, Chul Hak . E-mail: chulyang@plaza.snu.ac.kr

    2005-09-30

    Functional activation of {beta}-catenin/Tcf signaling plays an important role in early events in carcinogenesis. We examined the effect of naringenin against {beta}-catenin/Tcf signaling in gastric cancer cells. Reporter gene assay showed that naringenin inhibited {beta}-catenin/Tcf signaling efficiently. In addition, the inhibition of {beta}-catenin/Tcf signaling by naringenin in HEK293 cells transiently transfected with constitutively mutant {beta}-catenin gene, whose product is not phosphorylated by GSK3{beta}, indicates that its inhibitory mechanism was related to {beta}-catenin itself or downstream components. To investigate the precise inhibitory mechanism, we performed immunofluorescence, Western blot, and EMSA. As a result, our data revealed that the {beta}-catenin distribution and the levels of nuclear {beta}-catenin and Tcf-4 proteins were unchanged after naringenin treatment. Moreover, the binding activities of Tcf complexes to consensus DNA were not affected by naringenin. Taken together, these data suggest that naringenin inhibits {beta}-catenin/Tcf signaling in gastric cancer with unknown mechanisms.

  2. Roles of Wnt/{beta}-catenin signaling in epithelial differentiation of mesenchymal stem cells

    SciTech Connect

    Wang, Yajing; Sun, Zhaorui; Qiu, Xuefeng; Li, Yan; Qin, Jizheng; Han, Xiaodong

    2009-12-25

    Bone marrow-derived mesenchymal stem cells (MSCs) have been demonstrated to be able to differentiate into epithelial lineage, but the precise mechanisms controlling this process are unclear. Our aim is to explore the roles of Wnt/{beta}-catenin in the epithelial differentiation of MSCs. Using indirect co-culture of rat MSCs with rat airway epithelial cells (RTE), MSCs expressed several airway epithelial markers (cytokeratin 18, tight junction protein occudin, cystic fibrosis transmembrance regulator). The protein levels of some important members in Wnt/{beta}-catenin signaling were determined, suggested down-regulation of Wnt/{beta}-catenin with epithelial differentiation of MSCs. Furthermore, Wnt3{alpha} can inhibit the epithelial differentiation of MSCs. A loss of {beta}-catenin induced by Dickkopf-1 can enhance MSCs differentiation into epithelial cells. Lithium chloride transiently activated {beta}-catenin expression and subsequently decreased {beta}-catenin level and at last inhibited MSCs to differentiate into airway epithelium. Taken together, our study indicated that RTE cells can trigger epithelial differentiation of MSCs. Blocking Wnt/{beta}-catenin signaling may promote MSCs to differentiate towards airway epithelial cells.

  3. Parkin protects dopaminergic neurons from excessive Wnt/{beta}-catenin signaling

    SciTech Connect

    Rawal, Nina; Corti, Olga; Sacchetti, Paola; Ardilla-Osorio, Hector; Sehat, Bita; Brice, Alexis; Arenas, Ernest

    2009-10-23

    Parkinson's disease (PD) is caused by degeneration of the dopaminergic (DA) neurons of the substantia nigra but the molecular mechanisms underlying the degenerative process remain elusive. Several reports suggest that cell cycle deregulation in post-mitotic neurons could lead to neuronal cell death. We now show that Parkin, an E3 ubiquitin ligase linked to familial PD, regulates {beta}-catenin protein levels in vivo. Stabilization of {beta}-catenin in differentiated primary ventral midbrain neurons results in increased levels of cyclin E and proliferation, followed by increased levels of cleaved PARP and loss of DA neurons. Wnt3a signaling also causes death of post-mitotic DA neurons in parkin null animals, suggesting that both increased stabilization and decreased degradation of {beta}-catenin results in DA cell death. These findings demonstrate a novel regulation of Wnt signaling by Parkin and suggest that Parkin protects DA neurons against excessive Wnt signaling and {beta}-catenin-induced cell death.

  4. beta-Galactosidase enzyme fragment complementation for the measurement of Wnt/beta-catenin signaling.

    PubMed

    Verkaar, Folkert; Blankesteijn, W Matthijs; Smits, Jos F M; Zaman, Guido J R

    2010-04-01

    Wnt/beta-catenin signaling is an important regulator of cell polarity, proliferation, and stem cell maintenance during development and adulthood. Wnt proteins induce the nuclear accumulation of beta-catenin, which regulates the expression of Wnt-responsive genes through association with TCF/LEF transcription factors. Aberrant Wnt/beta-catenin signaling has been implicated in a plethora of pathologies and, most notably, underlies initiation and expansion of several cancers. Here, we apply enzyme fragment complementation to measure the nuclear accumulation of beta-catenin. beta-Catenin was tagged with a peptide fragment of beta-galactosidase and transfected into cells expressing a corresponding deletion mutant of the enzyme exclusively in the nucleus. Stimulation of the cells with recombinant Wnt-3a restored beta-galactosidase activity in a dose-dependent manner with nanomolar potency. Using the assay, we confirmed that Wnt-5a represses beta-catenin-driven reporter gene activity downstream of nuclear entry of beta-catenin. In addition, we tested a library of >2000 synthetic chemical compounds for their ability to induce beta-catenin nuclear accumulation. The immunosuppressive protein kinase C inhibitor sotrastaurin (AEB-071) was identified as an activator of Wnt/beta-catenin signaling at micromolar concentrations. It was confirmed that the compound stabilizes endogenous beta-catenin protein and can induce TCF/LEF-dependent gene transcription. Subsequent biochemical profiling of >200 kinases revealed both isoforms of glycogen synthase kinase 3, as previously unappreciated targets of sotrastaurin. We show that the beta-catenin nuclear accumulation assay contributes to our knowledge of molecular interactions within the Wnt/beta-catenin pathway and can be used to find new therapeutics targeting Wnt/beta-catenin signaling.-Verkaar, F., Blankesteijn, W. M., Smits, J. F. M., Zaman, G. J. R. beta-Galactosidase enzyme fragment complementation for the measurement of Wnt/beta-catenin

  5. Prenylated Rab acceptor 1 (PRA1) inhibits TCF/{beta}-catenin signaling by binding to {beta}-catenin

    SciTech Connect

    Kim, Jong-Tae; Cho, Mi-Young; Choi, Seung-Chul; Kim, Jung Woo; Chae, Suhn-Kee; Yoon, Do-Young; Kim, Jae Wha . E-mail: wjkim@kribb.re.kr; Lim, Jong-Seok . E-mail: jslim@sookmyung.ac.kr

    2006-10-13

    The prenylated Rab acceptor 1 (PRA1) is a ubiquitously expressed 21 kDa protein containing two transmembrane domains that possibly induce its localization to the Golgi complex. It binds to prenylated Rab GTPases and VAMP2. In this study, we report that PRA1-overexpressing cells exhibited a significantly retarded growth rate as compared to that of the mock-transfected cells, and the transcriptional activity of TCF, as evaluated by TOPflash luciferase reporter assay, was profoundly reduced in the PRA1-overexpressed cells. These intracellular functions of PRA1 were verified by introducing deletion mutant or site-directed mutants, or small interfering RNA of PRA1. In addition, the translocation of {beta}-catenin from the cytosol to the nucleus was blocked to a significant degree in the PRA1-cells, and the interaction of PRA1 and {beta}-catenin was identified by confocal microscopy and immunoprecipitation analysis. Finally, we observed that the inhibition of TCF/{beta}-catenin signaling by PRA1 is associated with ERK1/2 dephosphorylation. Therefore, our data suggest that the in vivo modulation of PRA1 may be involved in TCF/{beta}-catenin signaling, as well as cellular proliferation and tumorigenesis.

  6. Activation of Beta-Catenin Signaling in Androgen Receptor–Negative Prostate Cancer Cells

    PubMed Central

    Wan, Xinhai; Liu, Jie; Lu, Jing-Fang; Tzelepi, Vassiliki; Yang, Jun; Starbuck, Michael W.; Diao, Lixia; Wang, Jing; Efstathiou, Eleni; Vazquez, Elba S.; Troncoso, Patricia; Maity, Sankar N.; Navone, Nora M.

    2012-01-01

    Purpose To study Wnt/beta-catenin in castrate-resistant prostate cancer (CRPC) and understand its function independently of the beta-catenin–androgen receptor (AR) interaction. Experimental Design We performed beta-catenin immunocytochemical analysis, evaluated TOP-flash reporter activity (a reporter of beta-catenin–mediated transcription), and sequenced the beta-catenin gene in MDA PCa 118a, MDA PCa 118b, MDA PCa 2b, and PC-3 prostate cancer (PCa) cells. We knocked down beta-catenin in AR-negative MDA PCa 118b cells and performed comparative gene-array analysis. We also immunohistochemically analyzed beta-catenin and AR in 27 bone metastases of human CRPCs. Results Beta-catenin nuclear accumulation and TOP-flash reporter activity were high in MDA PCa 118b but not in MDA PCa 2b or PC-3 cells. MDA PCa 118a and 118b cells carry a mutated beta-catenin at codon 32 (D32G). Ten genes were expressed differently (false discovery rate, 0.05) in MDA PCa 118b cells with downregulated beta-catenin. One such gene, hyaluronan synthase 2 (HAS2), synthesizes hyaluronan, a core component of the extracellular matrix. We confirmed HAS2 upregulation in PC-3 cells transfected with D32G-mutant beta-catenin. Finally, we found nuclear localization of beta-catenin in 10 of 27 human tissue specimens; this localization was inversely associated with AR expression (P = 0.056, Fisher’s exact test), suggesting that reduced AR expression enables Wnt/beta-catenin signaling. Conclusion We identified a previously unknown downstream target of beta-catenin, HAS2, in PCa, and found that high beta-catenin nuclear localization and low or no AR expression may define a subpopulation of men with bone-metastatic PCa. These findings may guide physicians in managing these patients. PMID:22298898

  7. Beta-catenin signaling mediates CD4 expression on mature CD8+ T cells.

    PubMed

    Schenkel, Jason M; Zloza, Andrew; Li, Wei; Narasipura, Srinivas D; Al-Harthi, Lena

    2010-08-15

    Upon activation, a subset of mature human CD8(+) T cells re-expresses CD4 dimly. This CD4(dim)CD8(bright) T cell population is genuine and enriched in antiviral CD8(+) T cell responses. The signaling pathway that leads to CD4 re-expression on mature CD8(+) T cells is not clear. Given that Wnt/beta-catenin signaling plays a critical role in the transition of CD4(-)CD8(-) to CD4(+)CD8(+) thymocytes, we determined whether beta-catenin mediates CD4 expression on mature CD8(+) T cells. We demonstrate that active beta-catenin expression is 20-fold higher on CD4(dim)CD8(bright) than CD4(-)CD8(+) T cells. Activation of beta-catenin signaling, through LiCl or transfection with a constitutively active construct of beta-catenin, induced CD4 on CD8(+) T cells by approximately 10-fold. Conversely, inhibition of beta-catenin signaling through transfection with a dominant-negative construct for T cell factor-4, a downstream effector of beta-catenin signaling, diminished CD4 expression on CD8(+) T cells by 50% in response to T cell activation. Beta-catenin-mediated induction of CD4 on CD8(+) T cells is transcriptionally regulated, as it induced CD4 mRNA, and T cell factor/lymphoid enhancer factor sites were identified within the human CD4 promoter. Further, beta-catenin expression induced the antiapoptotic factor BcL-xL, suggesting that beta-catenin may mediate protection against activation-induced cell death. Collectively, these data demonstrate that beta-catenin is critical in inducing CD4 expression on mature CD8(+) T cells, suggesting that it is a common pathway for CD4 upregulation among thymocytes and mature CD8(+) T cells. PMID:20631314

  8. Excessive Wnt/beta-catenin signaling promotes midbrain floor plate neurogenesis, but results in vacillating dopamine progenitors.

    PubMed

    Nouri, Navid; Patel, Meera J; Joksimovic, Milan; Poulin, Jean-Francois; Anderegg, Angela; Taketo, M Mark; Ma, Yong-Chao; Awatramani, Rajeshwar

    2015-09-01

    The floor plate (FP), a ventral midline structure of the developing neural tube, has differential neurogenic capabilities along the anterior-posterior axis. The midbrain FP, unlike the hindbrain and spinal cord floor plate, is highly neurogenic and produces midbrain dopaminergic (mDA) neurons. Canonical Wnt/beta-catenin signaling, at least in part, is thought to account for the difference in neurogenic capability. Removal of beta-catenin results in mDA progenitor specification defects as well as a profound reduction of neurogenesis. To examine the effects of excessive Wnt/beta-catenin signaling on mDA specification and neurogenesis, we have analyzed a model wherein beta-catenin is conditionally stabilized in the Shh+domain. Here, we show that the Foxa2+/Lmx1a+ domain is extended rostrally in mutant embryos, suggesting that canonical Wnt/beta-catenin signaling can drive FP expansion along the rostrocaudal axis. Although excess canonical Wnt/beta-catenin signaling generally promotes neurogenesis at midbrain levels, less tyrosine hydroxylase (Th)+, mDA neurons are generated, particularly impacting the Substantia Nigra pars compacta. This is likely because of improper progenitor specification. Excess canonical Wnt/beta-catenin signaling causes downregulation of net Lmx1b, Shh and Foxa2 levels in mDA progenitors. Moreover, these progenitors assume a mixed identity to that of Lmx1a+/Lmx1b+/Nkx6-1+/Neurog1+ progenitors. We also show by lineage tracing analysis that normally, Neurog1+ progenitors predominantly give rise to Pou4f1+ neurons, but not Th+ neurons. Accordingly, in the mutant embryos, Neurog1+ progenitors at the midline generate ectopic Pou4f1+ neurons at the expense of Th+ mDA neurons. Our study suggests that an optimal dose of Wnt/beta-catenin signaling is critical for proper establishment of the mDA progenitor character. Our findings will impact embryonic stem cell protocols that utilize Wnt pathway reagents to derive mDA neuron models and therapeutics for

  9. Osteopontin induces {beta}-catenin signaling through activation of Akt in prostate cancer cells

    SciTech Connect

    Robertson, Brian W.; Chellaiah, Meenakshi A.

    2010-01-01

    Secretion of osteopontin (OPN) by cancer cells is a known mediator of tumorigenesis and cancer progression in both experimental and clinical studies. Our work demonstrates that OPN can activate Akt, an important step in cancer progression. Both ILK and PI3K are integral proteins in the OPN/Akt pathway, as inhibition of either kinase leads to a loss of OPN-mediated Akt activation. Subsequent to OPN-induced Akt activation, we observe inactivation of GSK-3{beta}, a regulator of {beta}-catenin. Osteopontin stimulation leads to an overall increase in {beta}-catenin protein levels with a resultant transfer of {beta}-catenin to the nucleus. Through the nuclear import of {beta}-catenin, OPN increases both the transcription and protein levels of MMP-7 and CD44, which are known TCF/LEF transcription targets. This work describes an important aspect of cancer progression induced by OPN.

  10. Ligand-dependent inhibition of beta-catenin/TCF signaling by androgen receptor.

    PubMed

    Chesire, Dennis R; Isaacs, William B

    2002-12-01

    Beta-catenin signaling may contribute to prostate cancer (CaP) progression. Although beta-catenin is known to upregulate T cell factor (TCF) target gene expression in CaP cells, recent evidence demonstrates its capacity to enhance ligand-dependent androgen receptor (AR) function. Thus, we wished to further understand the interaction between these two pathways. We find in both CaP cells (CWR22-Rv1, LAPC-4, DU145) and non-CaP cells (HEK-293, TSU, SW480, HCT-116) that beta-catenin/TCF-related transcription (CRT), as measured by activation of a synthetic promoter and that of cyclin D1, is inhibited by androgen treatment. This inhibition is AR-dependent, as it only occurs in cells expressing AR endogenously or transiently, and is abrogated by AR antagonists. Additional analyses convey that the ligand-dependent nature of CRT suppression depends on transactivation-competent AR in the nucleus, but not on indirect effects stemming from AR target gene expression. Given the recent work identifying an AR/beta-catenin interaction, and from our finding that liganded AR does not prompt gross changes in the constitutive nuclear localization of TCF4 or mutant beta-catenin, we hypothesized that transcription factor (i.e. AR and TCF) competition for beta-catenin recruitment may explain, in part, androgen-induced suppression of CRT. To address this idea, we expressed an AR mutant lacking its DNA-binding domain (DBD). This receptor could not orchestrate ligand-dependent CRT repression, thereby providing support for those recent data implicating the AR DBD/LBD as necessary for beta-catenin interaction. Further supporting this hypothesis, TCF/LEF over-expression counteracts androgen-induced suppression of CRT, and requires beta-catenin binding activity to do so. Interestingly, TCF4 over-expression potently antagonizes AR function; however, this inhibition may occur independently of beta-catenin/TCF4 interaction. These results from TCF4 over-expression analyses, taken together, provide

  11. Sonic hedgehog acts as a negative regulator of {beta}-catenin signaling in the adult tongue epithelium.

    PubMed

    Schneider, Fabian T; Schänzer, Anne; Czupalla, Cathrin J; Thom, Sonja; Engels, Knut; Schmidt, Mirko H H; Plate, Karl H; Liebner, Stefan

    2010-07-01

    Wnt/beta-catenin signaling has been implicated in taste papilla development; however, its role in epithelial maintenance and tumor progression in the adult tongue remains elusive. We show Wnt/beta-catenin pathway activation in reporter mice and by nuclear beta-catenin staining in the epithelium and taste papilla of adult mouse and human tongues. beta-Catenin activation in APC(min/+) mice, which carry a mutation in adenomatous poliposis coli (APC), up-regulates Sonic hedgehog (Shh) and Jagged-2 (JAG2) in the tongue epithelium without formation of squamous cell carcinoma (SCC). We demonstrate that Shh suppresses beta-catenin transcriptional activity in a signaling-dependent manner in vitro and in vivo. A similar regulation and function was observed for JAG2, suggesting that both pathways negatively regulate beta-catenin, thereby preventing SCC formation in the tongue. This was supported by reduced nuclear beta-catenin in the tongue epithelium of Patched(+/-) mice, exhibiting dominant active Shh signaling. At the invasive front of human tongue cancer, nuclear beta-catenin and Shh were increased, suggesting their participation in tumor progression. Interestingly, Shh but not JAG2 was able to reduce beta-catenin signaling in SCC cells, arguing for a partial loss of negative feedback on beta-catenin transcription in tongue cancer. We show for the first time that the putative Wnt/beta-catenin targets Shh and JAG2 control beta-catenin signaling in the adult tongue epithelium, a function that is partially lost in lingual SCC. PMID:20508033

  12. Wnt/{beta}-catenin signaling regulates cancer stem cells in lung cancer A549 cells

    SciTech Connect

    Teng, Ying; Wang, Xiuwen; Wang, Yawei; Ma, Daoxin

    2010-02-12

    Wnt/{beta}-catenin signaling plays an important role not only in cancer, but also in cancer stem cells. In this study, we found that {beta}-catenin and OCT-4 was highly expressed in cisplatin (DDP) selected A549 cells. Stimulating A549 cells with lithium chloride (LiCl) resulted in accumulation of {beta}-catenin and up-regulation of a typical Wnt target gene cyclin D1. This stimulation also significantly enhanced proliferation, clone formation, migration and drug resistance abilities in A549 cells. Moreover, the up-regulation of OCT-4, a stem cell marker, was observed through real-time PCR and Western blotting. In a reverse approach, we inhibited Wnt signaling by knocking down the expression of {beta}-catenin using RNA interference technology. This inhibition resulted in down-regulation of the Wnt target gene cyclin D1 as well as the proliferation, clone formation, migration and drug resistance abilities. Meanwhile, the expression of OCT-4 was reduced after the inhibition of Wnt/{beta}-catenin signaling. Taken together, our study provides strong evidence that canonical Wnt signaling plays an important role in lung cancer stem cell properties, and it also regulates OCT-4, a lung cancer stem cell marker.

  13. Snail/beta-catenin signaling protects breast cancer cells from hypoxia attack

    SciTech Connect

    Scherbakov, Alexander M.; Stefanova, Lidia B.; Sorokin, Danila V.; Semina, Svetlana E.; Berstein, Lev M.; Krasil’nikov, Mikhail A.

    2013-12-10

    The tolerance of cancer cells to hypoxia depends on the combination of different factors – from increase of glycolysis (Warburg Effect) to activation of intracellular growth/apoptotic pathways. Less is known about the influence of epithelial–mesenchymal transition (EMT) and EMT-associated pathways on the cell sensitivity to hypoxia. The aim of this study was to explore the role of Snail signaling, one of the key EMT pathways, in the mediating of hypoxia response and regulation of cell sensitivity to hypoxia, using as a model in vitro cultured breast cancer cells. Earlier we have shown that estrogen-independent HBL-100 breast cancer cells differ from estrogen-dependent MCF-7 cells with increased expression of Snail1, and demonstrated Snail1 involvement into formation of hormone-resistant phenotype. Because Snail1 belongs to hypoxia-activated proteins, here we studied the influence of Snail1 signaling on the cell tolerance to hypoxia. We found that Snail1-enriched HBL-100 cells were less sensitive to hypoxia-induced growth suppression if compared with MCF-7 line (31% MCF-7 vs. 71% HBL-100 cell viability after 1% O{sub 2} atmosphere for 3 days). Snail1 knock-down enhanced the hypoxia-induced inhibition of cell proliferation giving the direct evidence of Snail1 involvement into cell protection from hypoxia attack. The protective effect of Snail1 was shown to be mediated, at least in a part, via beta-catenin which positively regulated expression of HIF-1-dependent genes. Finally, we found that cell tolerance to hypoxia was accompanied with the failure in the phosphorylation of AMPK – the key energy sensor, and demonstrated an inverse relationship between AMPK and Snail/beta-catenin signaling. Totally, our data show that Snail1 and beta-catenin, besides association with loss of hormone dependence, protect cancer cells from hypoxia and may serve as an important target in the treatment of breast cancer. Moreover, we suggest that the level of these proteins as well

  14. Snail/beta-catenin signaling protects breast cancer cells from hypoxia attack.

    PubMed

    Scherbakov, Alexander M; Stefanova, Lidia B; Sorokin, Danila V; Semina, Svetlana E; Berstein, Lev M; Krasil'nikov, Mikhail A

    2013-12-10

    The tolerance of cancer cells to hypoxia depends on the combination of different factors--from increase of glycolysis (Warburg Effect) to activation of intracellular growth/apoptotic pathways. Less is known about the influence of epithelial-mesenchymal transition (EMT) and EMT-associated pathways on the cell sensitivity to hypoxia. The aim of this study was to explore the role of Snail signaling, one of the key EMT pathways, in the mediating of hypoxia response and regulation of cell sensitivity to hypoxia, using as a model in vitro cultured breast cancer cells. Earlier we have shown that estrogen-independent HBL-100 breast cancer cells differ from estrogen-dependent MCF-7 cells with increased expression of Snail1, and demonstrated Snail1 involvement into formation of hormone-resistant phenotype. Because Snail1 belongs to hypoxia-activated proteins, here we studied the influence of Snail1 signaling on the cell tolerance to hypoxia. We found that Snail1-enriched HBL-100 cells were less sensitive to hypoxia-induced growth suppression if compared with MCF-7 line (31% MCF-7 vs. 71% HBL-100 cell viability after 1% O2 atmosphere for 3 days). Snail1 knock-down enhanced the hypoxia-induced inhibition of cell proliferation giving the direct evidence of Snail1 involvement into cell protection from hypoxia attack. The protective effect of Snail1 was shown to be mediated, at least in a part, via beta-catenin which positively regulated expression of HIF-1-dependent genes. Finally, we found that cell tolerance to hypoxia was accompanied with the failure in the phosphorylation of AMPK - the key energy sensor, and demonstrated an inverse relationship between AMPK and Snail/beta-catenin signaling. Totally, our data show that Snail1 and beta-catenin, besides association with loss of hormone dependence, protect cancer cells from hypoxia and may serve as an important target in the treatment of breast cancer. Moreover, we suggest that the level of these proteins as well the level of

  15. Dibenzocyclooctadiene lignans, gomisins J and N inhibit the Wnt/{beta}-catenin signaling pathway in HCT116 cells

    SciTech Connect

    Kang, Kyungsu; Lee, Kyung-Mi; Yoo, Ji-Hye; Lee, Hee Ju; Kim, Chul Young; Nho, Chu Won

    2012-11-16

    Graphical abstract: Schematic diagram of the possible molecular mechanism underlying the inhibition of the Wnt/{beta}-catenin signaling pathway and the induction of G0/G1-phase arrest by gomisins J and N, derived from the fruits of S. chinensis, in HCT116 human colon cancer cells. Highlights: Black-Right-Pointing-Pointer Gomisins J and N inhibited Wnt/{beta}-catenin signaling pathway in HCT116 cells. Black-Right-Pointing-Pointer Gomisins J and N disrupted the binding of {beta}-catenin to specific DNA sequences, TBE. Black-Right-Pointing-Pointer Gomisins J and N inhibited the HCT116 cell proliferation through G0/G1 phase arrest. Black-Right-Pointing-Pointer Gomisins J and N inhibited the expression of Cyc D1, a Wnt/{beta}-catenin target gene. -- Abstract: Here, we report that gomisin J and gomisin N, dibenzocyclooctadiene type lignans isolated from Schisandra chinensis, inhibit Wnt/{beta}-catenin signaling in HCT116 cells. Gomisins J and N appear to inhibit Wnt/{beta}-catenin signaling by disrupting the interaction between {beta}-catenin and its specific target DNA sequences (TCF binding elements, TBE) rather than by altering the expression of the {beta}-catenin protein. Gomisins J and N inhibit HCT116 cell proliferation by arresting the cell cycle at the G0/G1 phase. The G0/G1 phase arrest induced by gomisins J and N appears to be caused by a decrease in the expression of Cyclin D1, a representative target gene of the Wnt/{beta}-catenin signaling pathway, as well as Cdk2, Cdk4, and E2F-1. Therefore, gomisins J and N, the novel Wnt/{beta}-catenin inhibitors discovered in this study, may serve as potential agents for the prevention and treatment of human colorectal cancers.

  16. Interactions between SOX factors and Wnt/beta-catenin signaling in development and disease.

    PubMed

    Kormish, Jay D; Sinner, Débora; Zorn, Aaron M

    2010-01-01

    The SOX family of transcription factors have emerged as modulators of canonical Wnt/beta-catenin signaling in diverse development and disease contexts. There are over 20 SOX proteins encoded in the vertebrate genome and recent evidence suggests that many of these can physically interact with beta-catenin and modulate the transcription of Wnt-target genes. The precise mechanisms by which SOX proteins regulate beta-catenin/TCF activity are still being resolved and there is evidence to support a number of models including: protein-protein interactions, the binding of SOX factors to Wnt-target gene promoters, the recruitment of co-repressors or co-activators, modulation of protein stability, and nuclear translocation. In some contexts, Wnt signaling also regulates SOX expression resulting in feedback regulatory loops that fine-tune cellular responses to beta-catenin/TCF activity. In this review, we summarize the examples of Sox-Wnt interactions and examine the underlying mechanisms of this potentially widespread and underappreciated mode of Wnt-regulation. PMID:19655378

  17. Jade-1 inhibits Wnt signalling by ubiquitylating beta-catenin and mediates Wnt pathway inhibition by pVHL.

    PubMed

    Chitalia, Vipul C; Foy, Rebecca L; Bachschmid, Markus M; Zeng, Liling; Panchenko, Maria V; Zhou, Mina I; Bharti, Ajit; Seldin, David C; Lecker, Stewart H; Dominguez, Isabel; Cohen, Herbert T

    2008-10-01

    The von Hippel-Lindau protein pVHL suppresses renal tumorigenesis in part by promoting the degradation of hypoxia-inducible HIF-alpha transcription factors; additional mechanisms have been proposed. pVHL also stabilizes the plant homeodomain protein Jade-1, which is a candidate renal tumour suppressor that may correlate with renal cancer risk. Here we show that Jade-1 binds the oncoprotein beta-catenin in Wnt-responsive fashion. Moreover, Jade-1 destabilizes wild-type beta-catenin but not a cancer-causing form of beta-catenin. Whereas the well-established beta-catenin E3 ubiquitin ligase component beta-TrCP ubiquitylates only phosphorylated beta-catenin, Jade-1 ubiquitylates both phosphorylated and non-phosphorylated beta-catenin and therefore regulates canonical Wnt signalling in both Wnt-off and Wnt-on phases. Thus, the different characteristics of beta-TrCP and Jade-1 may ensure optimal Wnt pathway regulation. Furthermore, pVHL downregulates beta-catenin in a Jade-1-dependent manner and inhibits Wnt signalling, supporting a role for Jade-1 and Wnt signalling in renal tumorigenesis. The pVHL tumour suppressor and the Wnt tumorigenesis pathway are therefore directly linked through Jade-1.

  18. Wnt-dependent beta-catenin signaling is activated after unilateral ureteral obstruction, and recombinant secreted frizzled-related protein 4 alters the progression of renal fibrosis.

    PubMed

    Surendran, Kameswaran; Schiavi, Susan; Hruska, Keith A

    2005-08-01

    beta-Catenin functions as a transducer of Wnt signals to the nucleus, where it interacts with the T cell factor (TCF) family of DNA binding proteins to regulate gene expression. On the basis of the genes regulated by beta-catenin and TCF in various biologic settings, two predicted functions of beta-catenin/TCF-dependent transcription are to mediate the loss of epithelial polarity and to promote fibroblast activities, such as the increased synthesis of fibronectin during chronic renal disease. These predictions were tested by determination of the expression and function of an inhibitor of Wnt signaling, secreted frizzled-related protein 4 (sFRP4), during renal tubular epithelial injury initiated by unilateral ureteral obstruction (UUO). Despite increased sFRP4 gene expression in perivascular regions of injured kidneys, total sFRP4 protein levels decreased after injury. The decreased sFRP4 protein levels after UUO accompanied increased Wnt-dependent beta-catenin signaling in tubular epithelial and interstitial cells, along with increased expression of markers of fibrosis. Administration of recombinant sFRP4 protein caused a reduction in tubular epithelial beta-catenin signaling and suppressed the progression of renal fibrosis, as evidenced by a partial maintenance of E-cadherin mRNA expression and a reduction in the amount of fibronectin and alpha-smooth muscle actin proteins. Furthermore, recombinant sFRP4 reduced the number of myofibroblasts, a central mediator of fibrosis. It is concluded that beta-catenin signaling is activated in tubular epithelial and interstitial cells after renal injury, and recombinant sFRP4 can interfere with epithelial de-differentiation and with fibroblast differentiation and function during progression of renal fibrosis.

  19. Beta-catenin versus the other armadillo catenins: assessing our current view of canonical Wnt signaling.

    PubMed

    Miller, Rachel K; Hong, Ji Yeon; Muñoz, William A; McCrea, Pierre D

    2013-01-01

    The prevailing view of canonical Wnt signaling emphasizes the role of beta-catenin acting downstream of Wnt activation to regulate transcriptional activity. However, emerging evidence indicates that other armadillo catenins in vertebrates, such as members of the p120 subfamily, convey parallel signals to the nucleus downstream of canonical Wnt pathway activation. Their study is thus needed to appreciate the networked mechanisms of canonical Wnt pathway transduction, especially as they may assist in generating the diversity of Wnt effects observed in development and disease. In this chapter, we outline evidence of direct canonical Wnt effects on p120 subfamily members in vertebrates and speculate upon these catenins' roles in conjunction with or aside from beta-catenin. PMID:23481204

  20. Apc bridges Wnt/{beta}-catenin and BMP signaling during osteoblast differentiation of KS483 cells

    SciTech Connect

    Miclea, Razvan L.; Horst, Geertje van der; Robanus-Maandag, Els C.; Loewik, Clemens W.G.M.; Oostdijk, Wilma; Wit, Jan M.; Karperien, Marcel

    2011-06-10

    The canonical Wnt signaling pathway influences the differentiation of mesenchymal cell lineages in a quantitative and qualitative fashion depending on the dose of {beta}-catenin signaling. Adenomatous polyposis coli (Apc) is the critical intracellular regulator of {beta}-catenin turnover. To better understand the molecular mechanisms underlying the role of Apc in regulating the differentiation capacity of skeletal progenitor cells, we have knocked down Apc in the murine mesenchymal stem cell-like KS483 cells by stable expression of Apc-specific small interfering RNA. In routine culture, KSFrt-Apc{sub si} cells displayed a mesenchymal-like spindle shape morphology, exhibited markedly decreased proliferation and increased apoptosis. Apc knockdown resulted in upregulation of the Wnt/{beta}-catenin and the BMP/Smad signaling pathways, but osteogenic differentiation was completely inhibited. This effect could be rescued by adding high concentrations of BMP-7 to the differentiation medium. Furthermore, KSFrt-Apc{sub si} cells showed no potential to differentiate into chondrocytes or adipocytes. These results demonstrate that Apc is essential for the proliferation, survival and differentiation of KS483 cells. Apc knockdown blocks the osteogenic differentiation of skeletal progenitor cells, a process that can be overruled by high BMP signaling.

  1. AMP-activated protein kinase (AMPK) cross-talks with canonical Wnt signaling via phosphorylation of {beta}-catenin at Ser 552

    SciTech Connect

    Zhao, Junxing; Yue, Wanfu; Zhu, Mei J.; Sreejayan, Nair; Du, Min

    2010-04-23

    AMP-activated protein kinase (AMPK) is a key regulator of energy metabolism; its activity is regulated by a plethora of physiological conditions, exercises and many anti-diabetic drugs. Recent studies show that AMPK involves in cell differentiation but the underlying mechanism remains undefined. Wingless Int-1 (Wnt)/{beta}-catenin signaling pathway regulates the differentiation of mesenchymal stem cells through enhancing {beta}-catenin/T-cell transcription factor 1 (TCF) mediated transcription. The objective of this study was to determine whether AMPK cross-talks with Wnt/{beta}-catenin signaling through phosphorylation of {beta}-catenin. C3H10T1/2 mesenchymal cells were used. Chemical inhibition of AMPK and the expression of a dominant negative AMPK decreased phosphorylation of {beta}-catenin at Ser 552. The {beta}-catenin/TCF mediated transcription was correlated with AMPK activity. In vitro, pure AMPK phosphorylated {beta}-catenin at Ser 552 and the mutation of Ser 552 to Ala prevented such phosphorylation, which was further confirmed using [{gamma}-{sup 32}P]ATP autoradiography. In conclusion, AMPK phosphorylates {beta}-catenin at Ser 552, which stabilizes {beta}-catenin, enhances {beta}-catenin/TCF mediated transcription, expanding AMPK from regulation of energy metabolism to cell differentiation and development via cross-talking with the Wnt/{beta}-catenin signaling pathway.

  2. Wnt/beta-Catenin Signaling and Small Molecule Inhibitors

    PubMed Central

    Voronkov, Andrey; Krauss, Stefan

    2012-01-01

    Wnt/β-catenin signaling is a branch of a functional network that dates back to the first metazoans and it is involved in a broad range of biological systems including stem cells, embryonic development and adult organs. Deregulation of components involved in Wnt/β-catenin signaling has been implicated in a wide spectrum of diseases including a number of cancers and degenerative diseases. The key mediator of Wnt signaling, β-catenin, serves several cellular functions. It functions in a dynamic mode at multiple cellular locations, including the plasma membrane, where β-catenin contributes to the stabilization of intercellular adhesive complexes, the cytoplasm where β-catenin levels are regulated and the nucleus where β-catenin is involved in transcriptional regulation and chromatin interactions. Central effectors of β-catenin levels are a family of cysteine-rich secreted glycoproteins, known as Wnt morphogens. Through the LRP5/6-Frizzled receptor complex, Wnts regulate the location and activity of the destruction complex and consequently intracellular β- catenin levels. However, β-catenin levels and their effects on transcriptional programs are also influenced by multiple other factors including hypoxia, inflammation, hepatocyte growth factor-mediated signaling, and the cell adhesion molecule E-cadherin. The broad implications of Wnt/β-catenin signaling in development, in the adult body and in disease render the pathway a prime target for pharmacological research and development. The intricate regulation of β-catenin at its various locations provides alternative points for therapeutic interventions. PMID:23016862

  3. Anticancer activity of Panax notoginseng extract 20(S)-25-OCH3-PPD: Targetting beta-catenin signalling.

    PubMed

    Bi, Xiuli; Zhao, Yuqing; Fang, Wenfeng; Yang, Wancai

    2009-11-01

    1. The Wnt/beta-catenin pathway plays a critical role in carcinogenesis and so agents that target Wnt/beta-catenin may have potential in cancer prevention and therapy. The aim of the present study was to evaluate the anticancer activity of the novel natural product dammarane-type triterpene sapogenin (20(S)-25-OCH3-PPD; PPD25) isolated from the leaves of Panax notoginseng. 2. The anticancer activity of PPD25 was evaluated in three colon cancer cell lines and in one lung cancer cell line. The effects of PPD25 to inhibit proliferation and to induce apoptosis were evaluated. In addition, the potential mechanisms underlying the effects of PPD25 were investigated. 3. It was found that the addition of 5 or 25 micromol/L PPD25 to the culture medium significantly inhibited cell proliferation and induced apoptosis in all four cancer cell lines. Mechanistic studies revealed that PPD25 significantly reduced the expression of beta-catenin, a key mediator in the Wnt pathway, as well as transcriptional targets of beta-catenin, namely c-myc, cyclin D1, cdk4 and T cell factor (TCF)-4. In addition, beta-catenin/TCF transcriptional activity was significantly suppressed by PPD25. 4. The data demonstrate that the PPD25 exerts its anticancer effect by targetting beta-catenin signalling, suggesting that PPD25 may have potential as a chemotherapeutic and/or chemopreventive agent for colon and lung cancer. PMID:19413587

  4. Homeodomain-interacting protein kinase 2 (HIPK2) targets {beta}-catenin for phosphorylation and proteasomal degradation

    SciTech Connect

    Kim, Eun-A; Kim, Ji Eon; Sung, Ki Sa; Choi, Dong Wook; Lee, Byeong Jae; Choi, Cheol Yong

    2010-04-16

    The regulation of intracellular {beta}-catenin levels is central in the Wnt/{beta}-catenin signaling cascade and the activation of the Wnt target genes. Here, we show that homeodomain-interacting protein kinase 2 (HIPK2) acts as a negative regulator of the Wnt/{beta}-catenin pathway. Knock-down of endogenous HIPK2 increases the stability of {beta}-catenin and results in the accumulation of {beta}-catenin in the nucleus, consequently enhancing the expression of Wnt target genes and cell proliferation both in vivo and in cultured cells. HIPK2 inhibits TCF/LEF-mediated target gene activation via degradation of {beta}-catenin. HIPK2 phosphorylates {beta}-catenin at its Ser33 and Ser37 residues without the aid of a priming kinase. Substitutions of Ser33 and Ser37 for alanines abolished the degradation of {beta}-catenin associated with HIPK2. In ex vivo mouse model, HIPK2 knock-down resulted in accumulation of {beta}-catenin, thereby potentiated {beta}-catenin-mediated cell proliferation and tumor formation. Furthermore, the axis duplication induced by the ectopic expression of {beta}-catenin was blocked by co-injection of HIPK2 mRNAs into Xenopus embryos. Taken together, HIPK2 appears to function as a novel negative regulator of {beta}-catenin through its phosphorylation and proteasomal degradation.

  5. Inhibition of {beta}-catenin-mediated transactivation by flavanone in AGS gastric cancer cells

    SciTech Connect

    Park, Chi Hoon; Hahm, Eun Ryeong; Lee, Ju Hyung; Jung, Kyung Chae; Yang, Chul Hak . E-mail: chulyang@plaza.snu.ac.kr

    2005-06-17

    Recently, data which prove that Wnt pathway activation may be an early event in multistep carcinogenesis in the stomach have been accumulating. We examined the effect of flavanone against {beta}-catenin/Tcf signaling in AGS gastric cancer cells. Reporter gene assay showed that flavanone inhibited {beta}-catenin/Tcf signaling efficiently. In addition, the inhibition of {beta}-catenin/Tcf signaling by flavanone in HEK293 cells transiently transfected with constitutively mutant {beta}-catenin gene, whose product is not phosphorylated by GSK3{beta}, indicates that its inhibitory mechanism was related to {beta}-catenin itself or downstream components. To investigate the precise inhibitory mechanism, we performed immunofluorescence, Western blot, and EMSA. As a result, our data revealed that there is no change of {beta}-catenin distribution and of nuclear {beta}-catenin levels through flavanone. In addition, the binding of Tcf complexes to DNA is not influenced by flavanone. The {beta}-catenin/Tcf transcriptional target gene cyclinD1 was downregulated by flavanone. These data suggest that flavanone inhibits the transcription of {beta}-catenin/Tcf responsive genes, by modulating Tcf activity without disrupting {beta}-catenin/Tcf complex formation.

  6. Rhesus lymphocryptovirus latent membrane protein 2A activates {beta}-catenin signaling and inhibits differentiation in epithelial cells

    SciTech Connect

    Siler, Catherine A.; Raab-Traub, Nancy

    2008-08-01

    Rhesus lymphocryptovirus (LCV) is a {gamma}-herpesvirus closely related to Epstein-Barr virus (EBV). The rhesus latent membrane protein 2A (LMP2A) is highly homologous to EBV LMP2A. EBV LMP2A activates the phosphatidylinositol 3-kinase (PI3K) and {beta}-catenin signaling pathways in epithelial cells and affects differentiation. In the present study, the biochemical and biological properties of rhesus LMP2A in epithelial cells were investigated. The expression of rhesus LMP2A in epithelial cells induced Akt activation, GSK3{beta} inactivation and accumulation of {beta}-catenin in the cytoplasm and nucleus. The nuclear translocation, but not accumulation of {beta}-catenin was dependent on Akt activation. Rhesus LMP2A also impaired epithelial cell differentiation; however, this process was not dependent upon Akt activation. A mutant rhesus LMP2A lacking six transmembrane domains functioned similarly to wild-type rhesus LMP2A indicating that the full number of transmembrane domains is not required for effects on {beta}-catenin or cell differentiation. These results underscore the similarity of LCV to EBV and the suitability of the macaque as an animal model for studying EBV pathogenesis.

  7. The low-density lipoprotein receptor-related protein 10 is a negative regulator of the canonical Wnt/{beta}-catenin signaling pathway

    SciTech Connect

    Jeong, Young-Hee; Sekiya, Manami; Hirata, Michiko; Ye, Mingjuan; Yamagishi, Azumi; Lee, Sang-Mi; Kang, Man-Jong; Hosoda, Akemi; Fukumura, Tomoe; Kim, Dong-Ho; Saeki, Shigeru

    2010-02-19

    Wnt signaling pathways play fundamental roles in the differentiation, proliferation and functions of many cells as well as developmental, growth, and homeostatic processes in animals. Low-density lipoprotein receptor (LDLR)-related protein (LRP) 5 and LRP6 serve as coreceptors of Wnt proteins together with Frizzled receptors, triggering activation of canonical Wnt/{beta}-catenin signaling. Here, we found that LRP10, a new member of the LDLR gene family, inhibits the canonical Wnt/{beta}-catenin signaling pathway. The {beta}-catenin/T cell factor (TCF) transcriptional activity in HEK293 cells was activated by transfection with Wnt3a or LRP6, which was then inhibited by co-transfection with LRP10. Deletion of the extracellular domain of LRP10 negated its inhibitory effect. The inhibitory effect of LRP10 was consistently conserved in HEK293 cells even when GSK3{beta} phosphorylation was inhibited by incubation with lithium chloride and co-transfection with constitutively active S33Y-mutated {beta}-catenin. Nuclear {beta}-catenin accumulation was unaffected by LRP10. The present studies suggest that LRP10 may interfere with the formation of the {beta}-catenin/TCF complex and/or its binding to target DNA in the nucleus, and that the extracellular domain of LRP10 is critical for inhibition of the canonical Wnt/{beta}-catenin signaling pathway.

  8. beta-catenin can be transported into the nucleus in a Ran-unassisted manner.

    PubMed

    Yokoya, F; Imamoto, N; Tachibana, T; Yoneda, Y

    1999-04-01

    The nuclear accumulation of beta-catenin plays an important role in the Wingless/Wnt signaling pathway. This study describes an examination of the nuclear import of beta-catenin in living mammalian cells and in vitro semi-intact cells. When injected into the cell cytoplasm, beta-catenin rapidly migrated into the nucleus in a temperature-dependent and wheat germ agglutinin-sensitive manner. In the cell-free import assay, beta-catenin rapidly migrates into the nucleus without the exogenous addition of cytosol, Ran, or ATP/GTP. Cytoplasmic injection of mutant Ran defective in its GTP hydrolysis did not prevent beta-catenin import. Studies using tsBN2, a temperature-sensitive mutant cell line that possesses a point mutation in the RCC1 gene, showed that the import of beta-catenin is insensitive to nuclear Ran-GTP depletion. These results show that beta-catenin possesses the ability to constitutively translocate through the nuclear pores in a manner similar to importin beta in a Ran-unassisted manner. We further showed that beta-catenin also rapidly exits the nucleus in homokaryons, suggesting that the regulation of nuclear levels of beta-catenin involves both nuclear import and export of this molecule.

  9. Transcription factor Egr1 acts as an upstream regulator of beta-catenin signalling through up-regulation of TCF4 and p300 expression during trans-differentiation of endometrial carcinoma cells.

    PubMed

    Saegusa, M; Hashimura, M; Kuwata, T; Hamano, M; Watanabe, J; Kawaguchi, M; Okayasu, I

    2008-12-01

    The beta-catenin/TCF4/p300 pathway is involved in early signalling for trans-differentiation towards the morular phenotype of endometrial carcinoma cells, but little is known about the upstream regulators. Here we show that transcription factor early growth response 1 (Egr1) acts as an initial mediator through up-regulating the expression of TCF4 and p300. In an endometrial carcinoma cell line with abundant oestrogen receptor alpha, Egr1 expression at both mRNA and protein levels was significantly increased by serum and 17beta-oestradiol stimuli. Serum-stimulated cells also showed increased expression of TCF4 and p300, while inhibition of Egr1 by specific siRNAs resulted in decreased expression. Transfection of Egr1 led to transactivation of TCF4 as well as p300 genes, through specific binding to a promoter region, and thus in turn resulted in nuclear accumulation of beta-catenin mediated by the up-regulating TCF4. The overexpression also caused inhibition of beta-catenin/TCF4/p300-mediated transcription, probably through sequestration of p300. Egr1 promoter activity was increased by serum but not 17beta-oestradiol, in contrast to the marked repression associated with TCF4, p300, and Egr1 itself, indicating that the regulation involves several feedback loops. In clinical samples, cells immunopositive for nuclear Egr1, as well as beta-catenin and TCF4, were found to be sporadically distributed in glandular components of endometrial carcinoma with morules. A significant positive correlation between nuclear beta-catenin and TCF4 was observed, but no such link was evident for Egr1, probably due to the existence of negative feedback regulation. Together, these data indicate that Egr1 may participate in modulation of the beta-catenin/TCF4/p300 signalling pathway as an initial event during trans-differentiation of endometrial carcinoma cells, through its impact on several signalling networks.

  10. Prenatal cadmium exposure dysregulates sonic hedgehog and Wnt/beta-catenin signaling in the thymus resulting in altered thymocyte development

    SciTech Connect

    Hanson, Miranda L.; Brundage, Kathleen M.; Schafer, Rosana; Tou, Janet C.; Barnett, John B.

    2010-01-15

    Cadmium (Cd) is both an environmental pollutant and a component of cigarette smoke. Although evidence demonstrates that adult exposure to Cd causes changes in the immune system, there are limited reports in the literature of immunomodulatory effects of prenatal exposure to Cd. The sonic hedgehog (Shh) and Wnt/beta-catenin pathways are required for thymocyte maturation. Several studies have demonstrated that Cd exposure affects these pathways in different organ systems. This study was designed to investigate the effect of prenatal Cd exposure on thymocyte development, and to determine if these effects were linked to dysregulation of Shh and Wnt/beta-catenin pathways. Pregnant C57Bl/6 mice were exposed to an environmentally relevant dose (10 ppm) of Cd throughout pregnancy and effects on the thymus were assessed on the day of birth. Thymocyte phenotype was determined by flow cytometry. A Gli:luciferase reporter cell line was used to measure Shh signaling. Transcription of target genes and translation of key components of both signaling pathways were assessed using real-time RT-PCR and western blot, respectively. Prenatal Cd exposure increased the number of CD4{sup +} cells and a subpopulation of double-negative cells (DN; CD4{sup -}CD8{sup -}), DN4 (CD44{sup -}CD25{sup -}). Shh and Wnt/beta-catenin signaling were both decreased in the thymus. Target genes of Shh (Patched1 and Gli1) and Wnt/beta-catenin (c-fos, and c-myc) were affected differentially among thymocyte subpopulations. These findings suggest that prenatal exposure to Cd dysregulates two signaling pathways in the thymus, resulting in altered thymocyte development.

  11. Nodal signaling in Xenopus gastrulae is cell-autonomous and patterned by beta-catenin.

    PubMed

    Hashimoto-Partyka, Minako K; Yuge, Masahiro; Cho, Ken W Y

    2003-01-01

    The classical three-signal model of amphibian mesoderm induction and more recent modifications together propose that an activin-like signaling activity is uniformly distributed across the vegetal half of the Xenopus blastula and that this activity contributes to mesoderm induction. In support of this, we have previously shown that the activin-response element (DE) of the goosecoid promoter is uniformly activated across the vegetal half of midgastrula-stage embryos. Here, we further examine the nature of this activity by measuring DE activation by endogenous signals over time. We find that the spatiotemporal pattern of DE activation is much more dynamic than was previously appreciated and also conclude that DE(6X)Luc activity reflects endogenous nodal signaling in the embryo. Using both the DE(6X)Luc construct and endogenous Xbra and Xgsc expression as read-outs for nodal activity, and the cleavage-mutant version of Xnr2 (CmXnr2) to regionally suppress endogenous nodal activity, we demonstrate that nodal signals act cell-autonomously in Xenopus gastrulae. Nodal-expressing cells are unable to rescue either reporter gene activation or target gene expression in distant nodal-deficient cells, suggesting that nodals function at short range in this context. Finally, we show that DE activation by endogenous signals occurs in the absence of dorsal beta-catenin-mediated signaling, but that the timing of dorsal initiation is altered. We conclude that nodal signals in Xenopus gastrulae function cell autonomously at short ranges and that the spatiotemporal pattern of this signaling along the dorsoventral axis is regulated by maternal Wnt-like signaling. PMID:12490202

  12. Nuclear Hormone Receptor LXRα Inhibits Adipocyte Differentiation of Mesenchymal Stem Cells with Wnt/beta-catenin Signaling

    PubMed Central

    Matsushita, Kenichi; Morello, Fulvio; Zhang, Zhiping; Masuda, Tomoko; Iwanaga, Shiro; Steffensen, Knut R.; Gustafsson, Jan-Åke; Pratt, Richard E.; Dzau, Victor J.

    2015-01-01

    Nuclear hormone receptor liver X receptor-alpha (LXRα) plays a vital role in cholesterol homeostasis and is reported to play a role in adipose function and obesity although this is controversial. Conversely, mesenchymal stem cells (MSCs) are suggested to be a major source of adipocyte generation. Accordingly, we examined the role of LXRα in adipogenesis of MSCs. Adult murine MSCs (mMSCs) were isolated from wild type (WT) and LXR-null mice. Using WT mMSCs, we further generated cell lines stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) or GFP alone (mMSC/GFP) by retroviral infection. Confluent mMSCs were differentiated into adipocytes by the established protocol. Compared with MSCs isolated from WT mice, MSCs from LXR-null mice showed significantly increased adipogenesis, as determined by lipid droplet accumulation and adipogenesis-related gene expression. Moreover, mMSCs stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) exhibited significantly decreased adipogenesis compared with mMSCs overexpressing GFP alone (mMSC/GFP). Since Wnt/beta-catenin signaling is reported to inhibit adipogenesis, we further examined it. The LXR-null group showed significantly decreased Wnt expression accompanied by a decrease of cellular beta-catenin (vs. WT). The mMSC/LXRα/GFP group exhibited significantly increased Wnt expression accompanied by an increase of cellular beta-catenin (vs. mMSC/GFP). These data demonstrate that LXRα has an inhibitory effect on adipogenic differentiation in murine mesenchymal stem cells with Wnt/beta-catenin signaling. These results provide important insights into the pathophysiology of obesity and obesity related consequences such as metabolic syndrome and may identify potential therapeutic targets. PMID:26595172

  13. Wnt/{beta}-catenin signaling changes C2C12 myoblast proliferation and differentiation by inducing Id3 expression

    SciTech Connect

    Zhang, Long; Shi, Songting; Zhang, Juan; Zhou, Fangfang; Dijke, Peter ten

    2012-03-02

    Highlights: Black-Right-Pointing-Pointer Expression of Id3 but not Id1 is induced by Wnt3a stimulation in C2C12 cells. Black-Right-Pointing-Pointer Wnt3a induces Id3 expression via canonical Wnt/{beta}-catenin pathway. Black-Right-Pointing-Pointer Wnt3a-induced Id3 expression does not depend on BMP signaling activation. Black-Right-Pointing-Pointer Induction of Id3 expression is critical determinant in Wnt3a-induced cell proliferation and differentiation. -- Abstract: Canonical Wnt signaling plays important roles in regulating cell proliferation and differentiation. In this study, we report that inhibitor of differentiation (Id)3 is a Wnt-inducible gene in mouse C2C12 myoblasts. Wnt3a induced Id3 expression in a {beta}-catenin-dependent manner. Bone morphogenetic protein (BMP) also potently induced Id3 expression. However, Wnt-induced Id3 expression occurred independent of the BMP/Smad pathway. Functional studies showed that Id3 depletion in C2C12 cells impaired Wnt3a-induced cell proliferation and alkaline phosphatase activity, an early marker of osteoblast cells. Id3 depletion elevated myogenin induction during myogenic differentiation and partially impaired Wnt3a suppressed myogenin expression in C2C12 cells. These results suggest that Id3 is an important Wnt/{beta}-catenin induced gene in myoblast cell fate determination.

  14. Inhibition of Drosophila Wg signaling involves competition between Mad and Armadillo/beta-catenin for dTcf binding.

    PubMed

    Zeng, Yi Arial; Rahnama, Maryam; Wang, Simon; Lee, Wendy; Verheyen, Esther M

    2008-01-01

    Precisely regulated signal transduction pathways are crucial for the regulation of developmental events and prevention of tumorigenesis. Both the Transforming Growth Factor beta (TGFbeta)/Bone morphogenetic protein (BMP) and Wnt/Wingless (Wg) pathways play essential roles in organismal patterning and growth, and their deregulation can lead to cancers. We describe a mechanism of interaction between Drosophila Wg and BMP signaling in which Wg target gene expression is antagonized by BMP signaling. In vivo, high levels of both an activated BMP receptor and the BMP effector Mad can inhibit the expression of Wg target genes. Conversely, loss of mad can induce Wg target gene expression. In addition, we find that ectopic expression in vivo of the Wg transcription factor dTcf is able to suppress the inhibitory effect caused by ectopic Mad. In vitro binding studies revealed competition for dTcf binding between Mad and the Wnt effector beta-catenin/Armadillo (Arm). Our in vivo genetic analyses and target gene studies support a mechanism consistent with the in vitro binding and competition studies, namely that BMP pathway components can repress Wg target gene expression by influencing the binding of Arm and dTcf. PMID:19065265

  15. Activation of the Wnt/{beta}-catenin signaling pathway is associated with glial proliferation in the adult spinal cord of ALS transgenic mice

    SciTech Connect

    Chen, Yanchun; Guan, Yingjun; Liu, Huancai; Wu, Xin; Yu, Li; Wang, Shanshan; Zhao, Chunyan; Du, Hongmei; Wang, Xin

    2012-04-06

    Highlights: Black-Right-Pointing-Pointer Wnt3a and Cyclin D1 were upregulated in the spinal cord of the ALS mice. Black-Right-Pointing-Pointer {beta}-catenin translocated from the cell membrane to the nucleus in the ALS mice. Black-Right-Pointing-Pointer Wnt3a, {beta}-catenin and Cyclin D1 co-localized for astrocytes were all increased. Black-Right-Pointing-Pointer BrdU/Cyclin D1 double-positive cells were increased in the spinal cord of ALS mice. Black-Right-Pointing-Pointer BrdU/Cyclin D1/GFAP triple-positive cells were detected in the ALS mice. -- Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive and fatal loss of motor neurons. In ALS, there is a significant cell proliferation in response to neurodegeneration; however, the exact molecular mechanisms of cell proliferation and differentiation are unclear. The Wnt signaling pathway has been shown to be involved in neurodegenerative processes. Wnt3a, {beta}-catenin, and Cyclin D1 are three key signaling molecules of the Wnt/{beta}-catenin signaling pathway. We determined the expression of Wnt3a, {beta}-catenin, and Cyclin D1 in the adult spinal cord of SOD1{sup G93A} ALS transgenic mice at different stages by RT-PCR, Western blot, and immunofluorescence labeling techniques. We found that the mRNA and protein of Wnt3a and Cyclin D1 in the spinal cord of the ALS mice were upregulated compared to those in wild-type mice. In addition, {beta}-catenin translocated from the cell membrane to the nucleus and subsequently activated transcription of the target gene, Cyclin D1. BrdU and Cyclin D1 double-positive cells were increased in the spinal cord of these mice. Moreover, Wnt3a, {beta}-catenin, and Cyclin D1 were also expressed in both neurons and astrocytes. The expression of Wnt3a, {beta}-catenin or Cyclin D1 in mature GFAP{sup +} astrocytes increased. Moreover, BrdU/Cyclin D1/GFAP triple-positive cells were detected in the ALS mice. Our findings suggest that

  16. Protease-activated receptor-1 (PAR1) acts via a novel Galpha13-dishevelled axis to stabilize beta-catenin levels.

    PubMed

    Turm, Hagit; Maoz, Myriam; Katz, Vered; Yin, Yong-Jun; Offermanns, Steffan; Bar-Shavit, Rachel

    2010-05-14

    We have previously shown a novel link between hPar-1 (human protease-activated receptor-1) and beta-catenin stabilization. Although it is well recognized that Wnt signaling leads to beta-catenin accumulation, the role of PAR1 in the process is unknown. We provide here evidence that PAR1 induces beta-catenin stabilization independent of Wnt, Fz (Frizzled), and the co-receptor LRP5/6 (low density lipoprotein-related protein 5/6) and identify selective mediators of the PAR1-beta-catenin axis. Immunohistological analyses of hPar1-transgenic (TG) mouse mammary tissues show the expression of both Galpha(12) and Galpha(13) compared with age-matched control counterparts. However, only Galpha(13) was found to be actively involved in PAR1-induced beta-catenin stabilization. Indeed, a dominant negative form of Galpha(13) inhibited both PAR1-induced Matrigel invasion and Lef/Tcf (lymphoid enhancer factor/T cell factor) transcription activity. PAR1-Galpha(13) association is followed by the recruitment of DVL (Dishevelled), an upstream Wnt signaling protein via the DIX domain. Small interfering RNA-Dvl silencing leads to a reduction in PAR1-induced Matrigel invasion, inhibition of Lef/Tcf transcription activity, and decreased beta-catenin accumulation. It is of note that PAR1 also promotes the binding of beta-arrestin-2 to DVL, suggesting a role for beta-arrestin-2 in PAR1-induced DVL phosphorylation dynamics. Although infection of small interfering RNA-LRP5/6 or the use of the Wnt antagonists, SFRP2 (soluble Frizzled-related protein 2) or SFRP5 potently reduced Wnt3A-mediated beta-catenin accumulation, no effect was observed on PAR1-induced beta-catenin stabilization. Collectively, our data show that PAR1 mediates beta-catenin stabilization independent of Wnt. We propose here a novel cascade of PAR1-induced Galpha(13)-DVL axis in cancer and beta-catenin stabilization. PMID:20223821

  17. Mouse model of human ovarian endometrioid adenocarcinoma based on somatic defects in the Wnt/beta-catenin and PI3K/Pten signaling pathways.

    PubMed

    Wu, Rong; Hendrix-Lucas, Neali; Kuick, Rork; Zhai, Yali; Schwartz, Donald R; Akyol, Aytekin; Hanash, Samir; Misek, David E; Katabuchi, Hidetaka; Williams, Bart O; Fearon, Eric R; Cho, Kathleen R

    2007-04-01

    One histologic subtype of ovarian carcinoma, ovarian endometrioid adenocarcinoma (OEA), frequently harbors mutations that constitutively activate Wnt/beta-catenin-dependent signaling. We now show that defects in the PI3K/Pten and Wnt/beta-catenin signaling pathways often occur together in a subset of human OEAs, suggesting their cooperation during OEA pathogenesis. Deregulation of these two pathways in the murine ovarian surface epithelium by conditional inactivation of the Pten and Apc tumor suppressor genes results in the formation of adenocarcinomas morphologically similar to human OEAs with 100% penetrance, short latency, and rapid progression to metastatic disease in upwards of 75% of mice. The biological behavior and gene expression patterns of the murine cancers resemble those of human OEAs with defects in the Wnt/beta-catenin and PI3K/Pten pathways.

  18. Generation and behavioral characterization of beta-catenin forebrain-specific conditional knock-out mice.

    PubMed

    Gould, Todd D; O'Donnell, Kelley C; Picchini, Alyssa M; Dow, Eliot R; Chen, Guang; Manji, Husseini K

    2008-05-16

    The canonical Wnt pathway and beta-catenin have been implicated in the pathophysiology of mood disorders. We generated forebrain-specific CRE-mediated conditional beta-catenin knock-out mice to begin exploring the behavioral implications of decreased Wnt pathway signaling in the central nervous system. In situ hybridization revealed a progressive knock-out of beta-catenin that began between 2 and 4 weeks of age, and by 12 weeks resulted in considerably decreased beta-catenin expression in regions of the forebrain, including the frontal cortex, hippocampus, and striatum. A significant decrease in protein levels of beta-catenin in these brain regions was observed by Western blot. Behavioral characterization of these mice in several tests (including the forced swim test, tail suspension test (TST), learned helplessness, response and sensitization to stimulants, and light/dark box among other tests) revealed relatively circumscribed alterations. In the TST, knock-out mice spent significantly less time struggling (a depression-like phenotype). However, knock-out mice did not differ from their wild-type littermates in the other behavioral tests of mood-related or anxiety-related behaviors. These results suggest that a 60-70% beta-catenin reduction in circumscribed brain regions is only capable of inducing subtle behavioral changes. Alternatively, regulating beta-catenin may modulate drug effects rather than being a model of mood disorder pathophysiology per se.

  19. DKK1, a negative regulator of Wnt signaling, is a target of the beta-catenin/TCF pathway.

    PubMed

    Niida, Atsushi; Hiroko, Takatoshi; Kasai, Mana; Furukawa, Yoichi; Nakamura, Yusuke; Suzuki, Yutaka; Sugano, Sumio; Akiyama, Tetsu

    2004-11-01

    Wnt signaling plays an important role in embryonic development and tumorigenesis. These biological effects are exerted by activation of the beta-catenin/TCF transcription complex and consequent regulation of a set of downstream genes. TCF-binding elements have been found in the promoter regions of many TCF target genes and characterized by a highly conserved consensus sequence. Utilizing this consensus sequence, we performed an in silico screening for new TCF target genes. Through computational screening and subsequent experimental analysis, we identified a novel TCF target gene, DKK1, which has been shown to be a potent inhibitor of Wnt signaling. Our finding suggests the existence of a novel feedback loop in Wnt signaling. PMID:15378020

  20. {beta}-Catenin up-regulates Nanog expression through interaction with Oct-3/4 in embryonic stem cells

    SciTech Connect

    Takao, Yukinari; Yokota, Takashi; Koide, Hiroshi . E-mail: hkoide@med.kanazawa-u.ac.jp

    2007-02-16

    It is well known that mouse embryonic stem (ES) cells can be maintained by the presence of leukemia inhibitory factor (LIF). Recent studies have revealed that Wnt also exhibits activity similar to LIF. The molecular mechanism behind the maintenance of ES cells by these factors, however, is not fully understood. In this study, we found that LIF enhances level of nuclear {beta}-catenin, a component of the Wnt signaling pathway. Expression of an activated mutant of {beta}-catenin led to the long-term proliferation of ES cells, even in the absence of LIF. Furthermore, it was found that {beta}-catenin up-regulates Nanog in an Oct-3/4-dependent manner and that {beta}-catenin physically associates with Oct-3/4. These results suggest that up-regulating Nanog through interaction with Oct-3/4 involves {beta}-catenin in the LIF- and Wnt-mediated maintenance of ES cell self-renewal.

  1. Increased beta-catenin protein and somatic APC mutations in sporadic aggressive fibromatoses (desmoid tumors).

    PubMed

    Alman, B A; Li, C; Pajerski, M E; Diaz-Cano, S; Wolfe, H J

    1997-08-01

    Sporadic aggressive fibromatosis (also called desmoid tumor) is a monoclonal proliferation of spindle (fibrocyte-like) cells that is locally invasive but does not metastasize. A similarity to abdominal fibromatoses (desmoids) in familial adenomatous polyposis and a cytogenetic study showing partial deletion of 5q in a subset of aggressive fibromatoses suggests that the adenomatous polyposis coli (APC) gene plays a role in its pathogenesis. APC helps regulate the cellular level of beta-catenin, which is a downstream mediator in Wnt (Wingless) signaling. beta-Catenin has a nuclear function (binds transcription factors) and a cell membrane function (is a component of epithelial cell adherens junctions). Six cases of aggressive fibromatosis of the extremities from patients without familial adenomatous polyposis, or a family history of colon cancer, were studied. Immunohistochemistry, using carboxy and amino terminus antibodies to APC, and DNA sequencing showed that three of the six contained an APC-truncating mutation, whereas normal tissues did not contain a mutation. Western blot and Northern dot blot showed that all six tumors had a higher level of beta-catenin protein than surrounding normal tissues, despite containing similar levels of beta-catenin mRNA. Immunohistochemistry localized beta-catenin throughout the cell in tumor tissues, although it localized more to the periphery in cells from normal tissues. Reverse transcription polymerase chain reaction showed that the tumors expressed N-cadherin but not E-cadherin (a pattern of expression of proteins making up adherens junctions similar to fibrocytes), suggesting that the specific adherens junctions present in epithelial cells are not necessary for beta-catenin function. Increased beta-catenin may cause the growth advantage of cells in this tumor through a nuclear mechanism. The increased protein level, relative to the RNA level, suggests that beta-catenin is degraded at a lower rate compared with normal tissues

  2. Increased beta-catenin protein and somatic APC mutations in sporadic aggressive fibromatoses (desmoid tumors).

    PubMed Central

    Alman, B. A.; Li, C.; Pajerski, M. E.; Diaz-Cano, S.; Wolfe, H. J.

    1997-01-01

    Sporadic aggressive fibromatosis (also called desmoid tumor) is a monoclonal proliferation of spindle (fibrocyte-like) cells that is locally invasive but does not metastasize. A similarity to abdominal fibromatoses (desmoids) in familial adenomatous polyposis and a cytogenetic study showing partial deletion of 5q in a subset of aggressive fibromatoses suggests that the adenomatous polyposis coli (APC) gene plays a role in its pathogenesis. APC helps regulate the cellular level of beta-catenin, which is a downstream mediator in Wnt (Wingless) signaling. beta-Catenin has a nuclear function (binds transcription factors) and a cell membrane function (is a component of epithelial cell adherens junctions). Six cases of aggressive fibromatosis of the extremities from patients without familial adenomatous polyposis, or a family history of colon cancer, were studied. Immunohistochemistry, using carboxy and amino terminus antibodies to APC, and DNA sequencing showed that three of the six contained an APC-truncating mutation, whereas normal tissues did not contain a mutation. Western blot and Northern dot blot showed that all six tumors had a higher level of beta-catenin protein than surrounding normal tissues, despite containing similar levels of beta-catenin mRNA. Immunohistochemistry localized beta-catenin throughout the cell in tumor tissues, although it localized more to the periphery in cells from normal tissues. Reverse transcription polymerase chain reaction showed that the tumors expressed N-cadherin but not E-cadherin (a pattern of expression of proteins making up adherens junctions similar to fibrocytes), suggesting that the specific adherens junctions present in epithelial cells are not necessary for beta-catenin function. Increased beta-catenin may cause the growth advantage of cells in this tumor through a nuclear mechanism. The increased protein level, relative to the RNA level, suggests that beta-catenin is degraded at a lower rate compared with normal tissues

  3. Threonine 393 of beta-catenin regulates interaction with Axin.

    PubMed

    Wu, Hao; Symes, Karen; Seldin, David C; Dominguez, Isabel

    2009-09-01

    CK2 is a regulatory kinase implicated in embryonic development and in cancer. Among the CK2 substrates is beta-catenin, a protein with dual function in Wnt signaling and cell adhesion. Previously, we reported that CK2 activity is required for beta-catenin stability and we identified threonine (T) 393 as a major CK2 phosphorylation site in beta-catenin. However, it is not known whether phosphorylation at T393 increases beta-catenin stability and if so, what is the mechanism. In this study we investigate the molecular mechanism of beta-catenin stabilization through phosphorylation at T393. We found that pseudophosphorylation of beta-catenin at T393 resulted in a stable activated form of beta-catenin with decreased affinity for Axin in vitro. This phosphomimetic mutant also displayed decreased regulation by Axin in vivo in a bioassay in Xenopus laevis embryos. In contrast, the binding of T393 pseudophosphorylated beta-catenin to E-cadherin was unaffected. Further analysis showed that pseudophosphorylation at T393 did not prevent beta-catenin phosphorylation by GSK3beta. Interestingly, we found that in the presence of pseudophophorylated beta-catenin and another activated form of beta-catenin, the recruitment of GSK3beta to Axin is enhanced. These findings indicate that phosphorylation of T393 by CK2 may affect the stability of beta-catenin through decreased binding to Axin. In addition, the increased recruitment of GSK3beta to the destruction complex in the presence of activated beta-catenin mutants could be a feedback mechanism to suppress overactive Wnt signaling.

  4. Beta-catenin--a supporting role in the skeleton.

    PubMed

    Case, Natasha; Rubin, Janet

    2010-06-01

    In the last 5 years a role for beta-catenin in the skeleton has been cemented. Beginning with mutations in the Lrp5 receptor that control beta-catenin canonical downstream signals, and progressing to transgenic models with bone-specific alteration of beta-catenin, research has shown that beta-catenin is required for normal bone development. A cell critical to bone in which beta-catenin activity determines function is the marrow-derived mesenchymal stem cell (MSC), where sustained beta-catenin prevents its distribution into adipogenic lineage. beta-Catenin actions are less well understood in mature osteoblasts: while beta-catenin contributes to control of osteoclastic bone resorption via alteration of the osteoprotegerin/RANKL ratio, a specific regulatory role during osteoblast bone synthesis has not yet been determined. The proven ability of mechanical factors to prevent beta-catenin degradation and induce nuclear translocation through Lrp-independent mechanisms suggests processes by which exercise might modulate bone mass via control of lineage allocation, in particular, by preventing precursor distribution into the adipocyte pool. Effects resulting from mechanical activation of beta-catenin in mature osteoblasts and osteocytes likely modulate bone resorption, but whether beta-catenin is involved in osteoblast synthetic function remains to be proven for both mechanical and soluble mediators. As beta-catenin appears to support the downstream effects of multiple osteogenic factors, studies clarifying when and where beta-catenin effects occur will be relevant for translational approaches aimed at preventing bone loss and terminal adipogenic conversion.

  5. Homeodomain-interacting protein kinases (Hipks) promote Wnt/Wg signaling through stabilization of beta-catenin/Arm and stimulation of target gene expression.

    PubMed

    Lee, Wendy; Swarup, Sharan; Chen, Joanna; Ishitani, Tohru; Verheyen, Esther M

    2009-01-01

    The Wnt/Wingless (Wg) pathway represents a conserved signaling cascade involved in diverse biological processes. Misregulation of Wnt/Wg signal transduction has profound effects on development. Homeodomain-interacting protein kinases (Hipks) represent a novel family of serine/threonine kinases. Members of this group (in particular Hipk2) are implicated as important factors in transcriptional regulation to control cell growth, apoptosis and development. Here, we provide genetic and phenotypic evidence that the sole Drosophila member of this family, Hipk, functions as a positive regulator in the Wg pathway. Expression of hipk in the wing rescues loss of the Wg signal, whereas loss of hipk can enhance decreased wg signaling phenotypes. Furthermore, loss of hipk leads to diminished Arm protein levels, whereas overexpression of hipk promotes the Wg signal by stabilizing Arm, resulting in activation of Wg responsive targets. In Wg transcriptional assays, Hipk enhanced Tcf/Arm-mediated gene expression in a kinase-dependent manner. In addition, Hipk can bind to Arm and Drosophila Tcf, and phosphorylate Arm. Using both in vitro and in vivo assays, Hipk was found to promote the stabilization of Arm. We observe similar molecular interactions between Lef1/beta-catenin and vertebrate Hipk2, suggesting a direct and conserved role for Hipk proteins in promoting Wnt signaling. PMID:19088090

  6. Glucagon-like peptide-2 activates beta-catenin signaling in the mouse intestinal crypt: role of insulin-like growth factor-I.

    PubMed

    Dubé, Philip E; Rowland, Katherine J; Brubaker, Patricia L

    2008-01-01

    Chronic administration of glucagon-like peptide-2 (GLP-2) induces intestinal growth and crypt cell proliferation through an indirect mechanism requiring IGF-I. However, the intracellular pathways through which IGF-I mediates GLP-2-induced epithelial tropic signaling remain undefined. Because beta-catenin and Akt are important regulators of crypt cell proliferation, we hypothesized that GLP-2 activates these signaling pathways through an IGF-I-dependent mechanism. In this study, fasted mice were administered Gly(2)-GLP-2 or LR(3)-IGF-I (positive control) for 0.5-4 h. Nuclear translocation of beta-catenin in non-Paneth crypt cells was assessed by immunohistochemistry and expression of its downstream proliferative markers, c-myc and Sox9, by quantitative RT-PCR. Akt phosphorylation and activation of its targets, glycogen synthase kinase-3beta and caspase-3, were determined by Western blot. IGF-I receptor (IGF-IR) and IGF-I signaling were blocked by preadministration of NVP-AEW541 and through the use of IGF-I knockout mice, respectively. We found that GLP-2 increased beta-catenin nuclear translocation in non-Paneth crypt cells by 72 +/- 17% (P < 0.05) and increased mucosal c-myc and Sox9 mRNA expression by 90 +/- 20 and 376 +/- 170%, respectively (P < 0.05-0.01), with similar results observed with IGF-I. This effect of GLP-2 was prevented by blocking the IGF-IR as well as ablation of IGF-I signaling. GLP-2 also produced a time- and dose-dependent activation of Akt in the intestinal mucosa (P < 0.01), most notably in the epithelium. This action was reduced by IGF-IR inhibition but not IGF-I knockout. We concluded that acute administration of GLP-2 activates beta-catenin and proliferative signaling in non-Paneth murine intestinal crypt cells as well as Akt signaling in the mucosa. However, IGF-I is required only for the GLP-2-induced alterations in beta-catenin.

  7. RhoA GTPase interacts with beta-catenin signaling in clinorotated osteoblasts

    PubMed Central

    Wan, Qiaoqiao; Cho, Eunhye; Yokota, Hiroki; Na, Sungsoo

    2014-01-01

    Bone is a dynamic tissue under constant remodeling in response to various signals including mechanical loading. A lack of proper mechanical loading induces disuse osteoporosis that reduces bone mass and structural integrity. β-catenin signaling together with a network of GTPases is known to play a primary role in load-driven bone formation, but little is known about potential interactions of β-catenin signaling and GTPases in bone loss. In this study, we addressed a question: Does unloading suppress an activation level of RhoA GTPase and β-catenin signaling in osteoblasts? If yes, what is the role of RhoA GTPase and actin filaments in osteoblasts in regulating β-catenin signaling? Using a fluorescence resonance energy transfer (FRET) technique with a biosensor for RhoA together with a fluorescent T-cell factor/lymphoid enhancer factor (TCF/LEF) reporter, we examined the effects of clinostat-driven simulated unloading. The results revealed that both RhoA activity and TCF/LEF activity were downregulated by unloading. Reduction in RhoA activity was correlated to a decrease in cytoskeletal organization of actin filaments. Inhibition of β-catenin signaling blocked unloading-induced RhoA suppression, and dominant negative RhoA inhibited TCF/LEF suppression. On the other hand, a constitutively active RhoA enhanced unloading-induced reduction of TCF/LEF activity. The TCF/LEF suppression by unloading was enhanced by co-culture with osteocytes, but it was independent on organization of actin filaments, myosin II activity, or a myosin light chain kinase. Collectively, the results suggest that β-catenin signaling is required for unloading-driven regulation of RhoA, and RhoA, but not actin cytoskeleton or intracellular tension, mediates the responsiveness of β-catenin signaling to unloading. PMID:23529802

  8. Inhibition of beta-catenin signaling by Pb leads to incomplete fracture healing.

    PubMed

    Beier, Eric E; Sheu, Tzong-Jen; Buckley, Taylor; Yukata, Kiminori; O'Keefe, Regis; Zuscik, Michael J; Puzas, J Edward

    2014-11-01

    There is strong evidence in the clinical literature to suggest that elevated lead (Pb) exposure impairs fracture healing. Since Pb has been demonstrated to inhibit bone formation, and Wnt signaling is an important anabolic pathway in chondrocyte maturation and endochondral ossification, we investigated the impact of Wnt therapy on Pb-exposed mice undergoing bone repair in a mouse tibial fracture model. We established that tibial fracture calluses from Pb-treated mice were smaller and contained less mineralized tissue than vehicle controls. This resulted in the persistence of immature cartilage in the callus and decreased β-catenin levels. Reduction of β-catenin protein was concurrent with systemic elevation of LRP5/6 antagonists DKK1 and sclerostin in Pb-exposed mice throughout fracture healing. β-catenin stimulation by the GSK3 inhibitor BIO reversed these molecular changes and restored the amount of mineralized callus. Overall, Pb is identified as a potent inhibitor of endochondral ossification in vivo with correlated effects on bone healing with noted deficits in β-catenin signaling, suggesting the Wnt/β-catenin as a pivotal pathway in the influence of Pb on fracture repair. PMID:25044211

  9. [Effect of phenylhexyl isothiocyanate on Wnt/beta-catenin signaling pathway in Jurkat cell line].

    PubMed

    Lin, Juan; Huang, Yi-Qun; Ma, Xu-Dong

    2013-04-01

    This study was purposed to investigate the effect of phenylhexyl isothiocyanate (PHI) on Wnt/β-catenin signaling pathway, histone acetylation, histone methylation and cell apoptosis in Jurkat cell line. The viability of Jurkat cells after treatment with PHI was tested by MTT. Apoptotic rate of Jurkat cells was measured by flow cytometry. The levels of Wnt/β-catenin related proteins including β-catenin, TCF, c-myc, and cyclinD1, histone acetylated H3 and H4, histone methylated H3K9 and H3K4 were detected by Western blot. The results showed that PHI inhibited the cell growth and induced apoptosis in Jurkat cells in time-and dose-dependent manners. Its IC50 at 48 h was about 20 µmol/L. Expression of histone acetylated H3, H4 and histone methylated H3k4 increased after exposure to PHI for 3 h, while histone methylated H3K9 decreased. Expression of β-catenin was not changed after exposure to PHI for 3 h, but expression of β-catenin, and its cell cycle-related genes such as TCF, c-myc and cyclinD1 decreased after exposure to PHI for 7 h. It is concluded that PHI regulates acetylation and methylation of histone, inhibits Wnt/β-catenin signal pathway, and is able to induce apoptosis and inhibits growth of Jurkat cells. PMID:23628033

  10. Bisindoylmaleimide I suppresses adipocyte differentiation through stabilization of intracellular {beta}-catenin protein

    SciTech Connect

    Cho, Munju; Park, Seoyoung; Gwak, Jungsug; Kim, Dong-Eun; Yea, Sung Su; Shin, Jae-Gook; Oh, Sangtaek

    2008-02-29

    The Wnt/{beta}-catenin signaling pathway plays important roles in cell differentiation. Activation of this pathway, likely by Wnt-10b, has been shown to inhibit adipogenesis in cultured 3T3-L1 preadipocytes and mice. Here we revealed that bisindoylmaleimide I (BIM), which is widely used as a specific inhibitor of protein kinase C (PKC), inhibits adipocyte differentiation through activation of the Wnt/{beta}-catenin signaling pathway. BIM increased {beta}-catenin responsive transcription (CRT) and up-regulated intracellular {beta}-catenin levels in HEK293 cells and 3T3-L1 preadipocytes. BIM significantly decreased intracellular lipid accumulation and reduced expression of important adipocyte marker genes including peroxisome-proliferator-activated receptor {gamma} (PPAR{gamma}) and CAATT enhancer-binding protein {alpha} (C/EBP{alpha}) in 3T3-L1 preadipocytes. Taken together, our findings indicate that BIM inhibits adipogenesis by increasing the stability of {beta}-catenin protein in 3T3-L1 preadipocyte cells.

  11. BETA-CATENIN SIGNALING, LIVER REGENERATION AND HEPATOCELLULAR CANCER: SORTING THE GOOD FROM THE BAD

    PubMed Central

    Nejak-Bowen, Kari Nichole; Monga, Satdarshan P. S.

    2011-01-01

    Among the adult organs, liver is unique for its ability to regenerate. A concerted signaling cascade enables optimum initiation of the regeneration process following insults brought about by surgery or a toxicant. Additionally, there exists a cellular redundancy, whereby a transiently amplifying progenitor population appears and expands to ensure regeneration, when differentiated cells of the liver are unable to proliferate in both experimental and clinical scenarios. One such pathway of relevance in these phenomena is Wnt/β-catenin signaling, which is activated relatively early during regeneration mostly through post-translational modifications. Once activated, β-catenin signaling drives the expression of target genes that are critical for cell cycle progression and contribute to initiation of the regeneration process. The role and regulation of Wnt/β-catenin signaling is now documented in rats, mice, zebrafish and patients. More recently, a regenerative advantage of the livers in β-catenin overexpressing mice was reported, as was also the case after exogenous Wnt-1 delivery to the liver paving the way for assessing means to stimulate the pathway for therapeutics in liver failure. β-Catenin is also pertinent in hepatic oval cell activation and differentiation. However, aberrant activation of the Wnt/β-catenin signaling is reported in a significant subset of hepatocellular cancers (HCC). While many mechanisms of such activation have been reported, the most functional means of aberrant and sustained activation is through mutations in the β-catenin gene or in AXIN1/2, which encodes for a scaffolding protein critical for β-catenin degradation. Intriguingly, in experimental models hepatic overexpression of normal or mutant β-catenin is insufficient for tumorigenesis. In fact β-catenin loss promoted chemical carcinogenesis in the liver due to alternate mechanisms. Since most HCC occur in the backdrop of chronic hepatic injury, where hepatic regeneration is

  12. O-GlcNAc-glycosylation of {beta}-catenin regulates its nuclear localization and transcriptional activity

    SciTech Connect

    Sayat, Ria; Leber, Brian; Grubac, Vanja; Wiltshire, Lesley; Persad, Sujata

    2008-09-10

    {beta}-catenin plays a role in intracellular adhesion and regulating gene expression. The latter role is associated with its oncogenic properties. Phosphorylation of {beta}-catenin controls its intracellular expression but mechanism/s that regulates the nuclear localization of {beta}-catenin is unknown. We demonstrate that O-GlcNAc glycosylation (O-GlcNAcylation) of {beta}-catenin negatively regulates its levels in the nucleus. We show that normal prostate cells (PNT1A) have significantly higher amounts of O-GlcNAcylated {beta}-catenin compared to prostate cancer (CaP) cells. The total nuclear levels of {beta}-catenin are higher in the CaP cells than PNT1A but only a minimal fraction of the nuclear {beta}-catenin in the CaP cells are O-GlcNAcylated. Increasing the levels of O-GlcNAcylated {beta}-catenin in the CaP cells with PUGNAc (O- (2-acetamido-2-deoxy-D-gluco-pyranosylidene) amino-N-phenylcarbamate) treatment is associated with a progressive decrease in the levels of {beta}-catenin in the nucleus. TOPFlash reporter assay and mRNA expressions of {beta}-catenin's target genes indicate that O-GlcNAcylation of {beta}-catenin results in a decrease in its transcriptional activity. We define a novel modification of {beta}-catenin that regulates its nuclear localization and transcriptional function.

  13. Activation of the canonical Wnt/{beta}-catenin pathway enhances monocyte adhesion to endothelial cells

    SciTech Connect

    Lee, Dong Kun . E-mail: leedk@memorialhealthsource.com; Nathan Grantham, R.; Trachte, Aaron L.; Mannion, John D.; Wilson, Colleen L.

    2006-08-18

    Monocyte adhesion to vascular endothelium has been reported to be one of the early processes in the development of atherosclerosis. In an attempt to develop strategies to prevent or delay atherosclerosis progression, we analyzed effects of the Wnt/{beta}-catenin signaling pathway on monocyte adhesion to various human endothelial cells. Adhesion of fluorescein-labeled monocytes to various human endothelial cells was analyzed under a fluorescent microscope. Unlike sodium chloride, lithium chloride enhanced monocyte adhesion to endothelial cells in a dose-dependent manner. We further demonstrated that inhibitors for glycogen synthase kinase (GSK)-3{beta} or proteosome enhanced monocyte-endothelial cell adhesion. Results of semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) indicated that activation of Wnt/{beta}-catenin pathway did not change expression levels of mRNA for adhesion molecules. In conclusion, the canonical Wnt/{beta}-catenin pathway enhanced monocyte-endothelial cell adhesion without changing expression levels of adhesion molecules.

  14. The human DEK oncogene stimulates beta catenin signaling, invasion and mammosphere formation in breast cancer

    PubMed Central

    Privette Vinnedge, Lisa M.; McClaine, Rebecca; Wagh, Purnima K.; Wikenheiser-Brokamp, Kathryn A.; Waltz, Susan E.; Wells, Susanne I.

    2011-01-01

    Breast cancer is a major cause of cancer-related deaths in American women; therefore, the identification of novel breast-cancer related molecules for the discovery of new markers and drug targets remains essential. The human DEK gene, which encodes a chromatin-binding protein and DNA topology regulator, is up-regulated in many types of cancer. DEK has been implicated as an oncogene in breast cancer based on mRNA expression studies, but its functional significance in breast cancer growth and progression has not yet been tested directly. We demonstrate that DEK is highly expressed in breast cancer cells compared to normal tissue, and functionally important for cellular growth, invasion and mammosphere formation. DEK over-expression in non-tumorigenic MCF10A cells resulted in increased growth and motility with a concomitant down-regulation of E-cadherin. Conversely, DEK knockdown in MCF7 and MDA-MB-468 breast cancer cells resulted in decreased growth and motility with up-regulation of E-cadherin. The use of DEK-proficient and -deficient breast cancer cells in orthotopic xenografts provided further in vivo evidence that DEK contributes to tumor growth. Activation of the β-catenin signaling pathway is important for normal and cancer stem cell character, growth and metastasis. We show that DEK expression stimulated and DEK knockdown repressed β-catenin nuclear translocation and activity. Importantly, the expression of constitutively active β-catenin rescued breast cancer invasion defects of DEK knockdown cells. Together, our data indicate that DEK expression stimulates the growth, stem cell character, and motility of breast cancer cells, and that DEK-dependent cellular invasion occurs at least in part via β-catenin activation. PMID:21317931

  15. Loss of p53 expression is accompanied by upregulation of beta-catenin in meningiomas: a concomitant reciprocal expression.

    PubMed

    Pećina-Šlaus, Nives; Kafka, Anja; Vladušić, Tomislav; Tomas, Davor; Logara, Monika; Skoko, Josip; Hrašćan, Reno

    2016-04-01

    Crosstalk between Wnt and p53 signalling pathways in cancer has long been suggested. Therefore in this study we have investigated the involvement of these pathways in meningiomas by analysing their main effector molecules, beta-catenin and p53. Cellular expression of p53 and beta-catenin proteins and genetic changes in TP53 were analysed by immunohistochemistry, PCR/RFLP and direct sequencing of TP53 exon 4. All the findings were analysed statistically. Our analysis showed that 47.5% of the 59 meningiomas demonstrated loss of expression of p53 protein. Moderate and strong p53 expression in the nuclei was observed in 8.5% and 6.8% of meningiomas respectively. Gross deletion of TP53 gene was observed in one meningioma, but nucleotide alterations were observed in 35.7% of meningiomas. In contrast, beta-catenin, the main Wnt signalling molecule, was upregulated in 71.2%, while strong expression was observed in 28.8% of meningiomas. The concomitant expressions of p53 and beta-catenin were investigated in the same patients. In the analysed meningiomas, the levels of the two proteins were significantly negatively correlated (P = 0.002). This indicates that meningiomas with lost p53 upregulate beta-catenin and activate Wnt signalling. Besides showing the reciprocal relationship between proteins, we also showed that the expression of p53 was significantly (P = 0.021) associated with higher meningioma grades (II and III), while beta-catenin upregulation was not associated with malignancy grades. Additionally, women exhibited significantly higher values of p53 loss when compared to males (P = 0.005). Our findings provide novel information about p53 involvement in meningeal brain tumours and reveal the complex relationship between Wnt and p53 signalling, they suggest an important role for beta-catenin in these tumours.

  16. Inhibition of the Tcf/beta-catenin complex increases apoptosis and impairs adrenocortical tumor cell proliferation and adrenal steroidogenesis

    PubMed Central

    Leal, Letícia F.; Bueno, Ana Carolina; Gomes, Débora C.; Abduch, Rafael; de Castro, Margaret; Antonini, Sonir R.

    2015-01-01

    Background To date, there is no effective therapy for patients with advanced/metastatic adrenocortical cancer (ACC). The activation of the Wnt/beta-catenin signaling is frequent in ACC and this pathway is a promising therapeutic target. Aim To investigate the effects of the inhibition of the Wnt/beta-catenin in ACC cells. Methods Adrenal (NCI-H295 and Y1) and non-adrenal (HeLa) cell lines were treated with PNU-74654 (5–200 μM) for 24–96 h to assess cell viability (MTS-based assay), apoptosis (Annexin V), expression/localization of beta-catenin (qPCR, immunofluorescence, immunocytochemistry and western blot), expression of beta-catenin target genes (qPCR and western blot), and adrenal steroidogenesis (radioimmunoassay, qPCR and western blot). Results In NCI-H295 cells, PNU-74654 significantly decreased cell proliferation 96 h after treatment, increased early and late apoptosis, decreased nuclear beta-catenin accumulation, impaired CTNNB1/beta-catenin expression and increased beta-catenin target genes 48 h after treatment. No effects were observed on HeLa cells. In NCI-H295 cells, PNU-74654 decreased cortisol, testosterone and androstenedione secretion 24 and 48 h after treatment. Additionally, in NCI-H295 cells, PNU-74654 decreased SF1 and CYP21A2 mRNA expression as well as the protein levels of STAR and aldosterone synthase 48 h after treatment. In Y1 cells, PNU-74654 impaired corticosterone secretion 24 h after treatment but did not decrease cell viability. Conclusions Blocking the Tcf/beta-catenin complex inhibits the Wnt/beta-catenin signaling in adrenocortical tumor cells triggering increased apoptosis, decreased cell viability and impairment of adrenal steroidogenesis. These promising findings pave the way for further experiments inhibiting the Wnt/beta-catenin pathway in pre-clinical models of ACC. The inhibition of this pathway may become a promising adjuvant therapy for patients with ACC. PMID:26515592

  17. R-ETODOLAC DECREASES BETA-CATENIN LEVELS ALONG WITH SURVIVAL AND PROLIFERATION OF HEPATOMA CELLS

    PubMed Central

    Behari, Jaideep; Zeng, Gang; Otruba, Wade; Thompson, Michael; Muller, Peggy; Micsenyi, Amanda; Sekhon, Sandeep S.; Leoni, Lorenzo; Monga, Satdarshan P. S.

    2007-01-01

    Background Inhibition of hepatoma cells by cyclooxygenase (COX)-2 dependent and independent mechanisms has been shown previously. Here, we examine the effect of Celecoxib, a COX-2-inhibitor and R-Etodolac, an enantiomer of the nonsteroidal anti-inflammatory drug Etodolac, which lacks COX-inhibitory activity, on the Wnt/β-catenin pathway and human hepatoma cells. Methods Hep3B and HepG2 cell lines were treated with Celecoxib or R-Etodolac, and examined for viability, DNA synthesis, Wnt/β-catenin pathway components, and downstream target gene expression. Results Celecoxib at high doses affected β-catenin protein by inducing its degradation via GSK3β and APC along with diminished tumor cell proliferation and survival. R-Etodolac at physiological doses caused decrease in total and activated β-catenin protein secondary to decrease in its gene expression and post-translationally through GSK3β activation. In addition, increased β-catenin-E-cadherin was also observed at the membrane. An associated inhibition of β-catenin-dependent Tcf reporter activity, decreased levels of downstream target gene products glutamine synthetase and cyclin-D1, and decreased proliferation and survival of hepatoma cells was evident. Conclusion The antitumor effects of Celecoxib (at high concentrations) and R-Etodolac (at physiological doses) on HCC cells were accompanied by the down-regulation of β-catenin demonstrating a useful therapeutic strategy in hepatocellular cancer. PMID:17275129

  18. {beta}-Catenin mediates the anti-adipogenic effect of baicalin

    SciTech Connect

    Lee, Haeyong; Bae, Sungmin; Kim, Kijeong; Kim, Wonyong; Chung, Sang-In; Yoon, Yoosik

    2010-08-06

    Research highlights: {yields} Baicalin maintains the levels of {beta}-Catenin during adipogenesis. {yields} {beta}-Catenin mediates the anti-adipogenic effect of baicalin. {yields} Baicalin maintains the WNT/{beta}-Catenin pathway during adipogenesis. -- Abstract: {beta}-Catenin reportedly inhibits adipogenesis through the down-regulations of peroxisome proliferator-activated receptor (PPAR){gamma} and CCAAT/enhancer binding protein (C/EBP){alpha}. We report that baicalin, a natural flavonoid compound, inhibits adipogenesis by modulating {beta}-Catenin. During 3T3-L1 cell adipogenesis, {beta}-Catenin was down-regulated, but baicalin treatment maintained {beta}-Catenin expression. Anti-adipogenic effects of baicalin were significantly attenuated by {beta}-Catenin siRNA transfection. {beta}-Catenin siRNA rescued the reduced expressions of PPAR{gamma}, C/EBP{alpha}, fatty acid binding protein 4 and lipoprotein lipase by baicalin. Furthermore, baicalin modulated members of the WNT/{beta}-Catenin pathway by maintaining the expressions of low-density lipoprotein receptor-related protein 6, disheveled (DVL)2 and DVL3. These findings suggest that {beta}-Catenin mediates the anti-adipogenic effects of baicalin.

  19. N-cadherin mediated distribution of beta-catenin alters MAP kinase and BMP-2 signaling on chondrogenesis-related gene expression.

    PubMed

    Modarresi, Rozbeh; Lafond, Toulouse; Roman-Blas, Jorge A; Danielson, Keith G; Tuan, Rocky S; Seghatoleslami, M Reza

    2005-05-01

    We have examined the effect of calcium-dependent adhesion, mediated by N-cadherin, on cell signaling during chondrogenesis of multipotential embryonic mouse C3H10T1/2 cells. The activity of chondrogenic genes, type II collagen, aggrecan, and Sox9 were examined in monolayer (non-chondrogenic), and micromass (chondrogenic) cultures of parental C3H10T1/2 cells and altered C3H10T1/2 cell lines that express a dominant negative form of N-cadherin (delta390-T1/2) or overexpress normal N-cadherin (MNCD2-T1/2). Our findings show that missexpression or inhibition of N-cadherin in C3H10T1/2 cells results in temporal and spatial changes in expression of the chondrogenic genes Sox9, aggrecan, and collagen type II. We have also analyzed activity of the serum response factor (SRF), a nuclear target of MAP kinase signaling implicated in chondrogenesis. In semi-confluent monolayer cultures (minimum cell-cell contact) of C3H10T1/2, MNCD2-T1/2, or delta390-T1/2 cells, there was no significant change in the pattern of MAP kinase or bone morphogenetic protein-2 (BMP-2) regulation of SRF. However, in micromass cultures, the effect of MAP kinase and BMP-2 on SRF activity was proportional to the nuclear localization of beta-catenin, a Wnt stabilized cytoplasmic factor that can associate with lymphoid enhancer-binding factor (LEF) to serve as a transcription factor. Our findings suggest that the extent of adherens junction formation mediated by N-cadherin can modulate the potential Wnt-induced nuclear activity of beta-catenin. PMID:15723280

  20. Beta-catenin-mediated cell-adhesion is vital for embryonic forebrain development.

    PubMed

    Junghans, Dirk; Hack, Iris; Frotscher, Michael; Taylor, Verdon; Kemler, Rolf

    2005-06-01

    Forming a complex structure such as the mammalian brain requires a complex interplay between cells and different signalling cascades during embryonic development. beta-catenin plays pivotal roles in these processes by mediating cadherin-based cell adhesion and Wnt signalling. We show for the first time that beta-catenin functions predominantly as a mediator of cell adhesion during early development of the mammalian telencephalon. Immunohistochemical analysis demonstrates that beta-catenin is localized, together with N-cadherin, to adhesion junctions at the apical lining of the neuroepithelium. The ablation of beta-catenin specifically from the forebrain leads to a disruption of apical adherens junctions and a breakdown of neuroepithelial structures. We show that beta-catenin-deficient neuroepithelial cells delaminate and undergo apoptosis. Newborn beta-catenin mutants lack the entire forebrain and anterior facial structures. Our data also indicate a lack of TCF/LEF-beta-catenin-dependent transcriptional activity in the telencephalon of Wnt reporter embryos. Together with the absence of nuclear beta-catenin, this finding suggests that canonical Wnt signalling is not active during early telencephalic development. In summary, we demonstrate that beta-catenin mediates cell-cell adhesion in the early telencephalon and is vital for maintaining the structural integrity of the neuroepithelium.

  1. Essential role of T-cell factor/beta-catenin in regulation of Rad6B: a potential mechanism for Rad6B overexpression in breast cancer cells.

    PubMed

    Shekhar, Malathy P V; Tait, Larry; Gerard, Brigitte

    2006-10-01

    We have previously shown that the postreplication DNA repair gene Rad6B plays a critical role in the maintenance of genomic integrity of human breast cells. Whereas normal breast cells express low levels of Rad6B, increases in Rad6B expression occur in hyperplasia with overexpression in breast carcinomas. Here, we show that the human Rad6B gene is a transcriptional target of T-cell factor (TCF)-4/beta-catenin/p300. Rad6B promoter activity is subject to negative regulation in normal human MCF10A breast cells whereas it is constitutively active in metastatic MDA-MB-231 breast cancer cells. Derepression and activation of Rad6B promoter in MCF10A cells require coexpression of beta-catenin and p300. Using electrophoresis mobility shift assay, Western blot analysis of electrophoresis mobility shift assay, UV cross-linking, and chromatin immunoprecipitation assay, we show that Rad6B transcriptional repression in MCF10A cells is due to paucity of transcriptionally active beta-catenin assembled on the TCF binding sequence in the Rad6B promoter rather than to a deficit/decreased affinity of TCF-4 for the TCF binding element in Rad6B promoter. Three-dimensional epithelial acini generated in vitro from MCF10A cells cotransfected with beta-catenin and p300 showed beta-catenin expression on the membrane, cytoplasm, and/or nuclei with concomitant Rad6 overexpression, whereas control acini showed beta-catenin on the membranes and negligible Rad6 expression. Immunohistochemical analysis of 12 breast carcinomas showed an approximately 80% correlation between Rad6 and beta-catenin expression, and combined nuclear and cytoplasmic staining of beta-catenin and Rad6 was detected in 25% of the breast carcinomas. In vivo implantation of MCF10A-Rad6B cells produced hyperplastic lesions. These data reveal a potentially important role for transcriptionally active beta-catenin in the regulation of Rad6B gene expression, and link aberrant beta-catenin signaling with transcriptional deregulation

  2. Inhibition of GSK3 differentially modulates NF-{kappa}B, CREB, AP-1 and {beta}-catenin signaling in hepatocytes, but fails to promote TNF-{alpha}-induced apoptosis

    SciTech Connect

    Goetschel, Frank; Kern, Claudia; Lang, Simona; Sparna, Titus; Markmann, Cordula; Schwager, Joseph; McNelly, Sabine; Weizsaecker, Fritz von; Laufer, Stefan; Hecht, Andreas Merfort, Irmgard

    2008-04-01

    Glycogen synthase kinase-3 (GSK-3) is known to modulate cell survival and apoptosis through multiple intracellular signaling pathways. However, its hepatoprotective function and its role in activation of NF-{kappa}B and anti-apoptotic factors are poorly understood and remain controversial. Here we investigated whether inhibition of GSK-3 could induce apoptosis in the presence of TNF-{alpha} in primary mouse hepatocytes. We show that pharmacological inhibition of GSK-3 in primary mouse hepatocytes does not lead to TNF-{alpha}-induced apoptosis despite reduced NF-{kappa}B activity. Enhanced stability of I{kappa}B-{alpha} appears to be responsible for lower levels of nuclear NF-{kappa}B and hence reduced transactivation. Additionally, inhibition of GSK-3 was accompanied by marked upregulation of {beta}-catenin, AP-1, and CREB transcription factors. Stimulation of canonical Wnt signaling and CREB activity led to elevated levels of anti-apoptotic factors. Hence, survival of primary mouse hepatocytes may be caused by the activation and/or upregulation of other key regulators of liver homeostasis and regeneration. These signaling molecules may compensate for the compromised anti-apoptotic function of NF-{kappa}B and allow survival of hepatocytes in the presence of TNF-{alpha} and GSK-3 inhibition.

  3. ICAT Inhibits beta-Catenin Binding to Tcf/Lef-Family Transcription Factors and in the General Coactivator p300 Using Independent Structural Modules

    SciTech Connect

    Daniels, D. L.

    2002-01-01

    In the canonical Wnt signaling pathway, {beta}-catenin activates target genes through its interactions with Tcf/Lef-family transcription factors and additional transcriptional coactivators. The crystal structure of ICAT, an inhibitor of {beta}-catenin-mediated transcription, bound to the armadillo repeat domain of {beta}-catenin, has been determined. ICAT contains an N-terminal helilical domain that binds to repeats 11 and 12 of {beta}-catenin, and an extended C-terminal region that binds to repeats 5-10 in a manner similar that of Tcfs and other {beta}-catenin ligands. Full-length ICAT dissociates complexes of {beta}-catenin, Lef-1, and the transcriptional coactivator p300, whereas the helical domain alone selectively blocks binding to p300. The C-terminal armadillo repeats of {beta}-catenin may be an attractive target for compounds designed to disrupt aberrant {beta}-catenin-mediated transcription associated with various cancers.

  4. {beta}-Catenin/LEF1 activated enamelin expression in ameloblast-like cells

    SciTech Connect

    Tian, Hua; Lv, Ping; Ma, Kangtao; Zhou, Chunyan; Gao, Xuejun

    2010-07-30

    Research highlights: {yields} {beta}-Catenin/LEF1 complex could activate enamelin gene transcription. {yields} {beta}-Catenin/LEF1 can directly bind to enamelin 5' regulatory region. {yields} Wnt/{beta}-catenin signaling can upregulate enamelin expression in ameloblast-like cells. -- Abstract: Enamelin is an ameloblast-specific matrix protein believed to play essential roles in enamel formation. However, mechanisms of enamelin transcription regulation are not clear. {beta}-Catenin/LEF1 is a key transcriptional complex involved in tooth development. In this study, the role of {beta}-catenin/LEF1 in enamelin expression was investigated. The 5'-flanking region of the mouse enamelin gene was analyzed and cloned. Co-transfection analysis and mutation assays revealed that two conserved LEF1 responsive elements located at -1002 and -597 bp upstream of the enamelin translation initiation site could augment transcriptional activity of the enamelin. The interaction between the enamelin elements and {beta}-catenin/LEF1 was further confirmed by electrophoresis mobility shift assays and chromatin immunoprecipitation assays. In addition, LiCl treatment induced nuclear translocation of {beta}-catenin and elevated endogenous enamelin expression in mouse ameloblast-like cells. The results suggested that Wnt/{beta}-catenin signaling could function in enamelin gene expression by direct interaction through two conserved LEF1 responsive elements on the enamelin gene in ameloblast-like cells.

  5. Stimulation of Wnt/beta-Catenin Signaling Pathway with Wnt Agonist Reduces Organ Injury after Hemorrhagic Shock

    PubMed Central

    Kuncewitch, Michael; Yang, Weng-Lang; Jacob, Asha; Khader, Adam; Giangola, Matthew; Nicastro, Jeffrey; Coppa, Gene F.; Wang, Ping

    2014-01-01

    Background Hemorrhagic shock is a leading cause of morbidity and mortality in surgery and trauma patients. Despite a large number of preclinical trials conducted to develop therapeutic strategies against hemorrhagic shock, there is still an unmet need exist for effective therapy for hemorrhage victims. Wnt/β-catenin signaling controls developmental processes and cellular regeneration owing to its central role in cell survival and proliferation. We therefore hypothesized that the activation of Wnt signaling reduces systemic injury caused by hemorrhagic shock. Methods Adult male Sprague-Dawley rats underwent hemorrhagic shock by controlled bleeding of the femoral artery to maintain a mean arterial pressure (MAP) of 30 mmHg for 90 min, followed by resuscitation with crystalloid equal to two times the shed blood volume. After resuscitation, animals were infused with Wnt agonist (5 mg/kg) or Vehicle (20% DMSO in saline). Blood and tissue samples were collected 6 h after resuscitation for analysis. Results Hemorrhagic shock increased serum levels of AST, lactate, and LDH. Treatment with Wnt agonist significantly reduced these levels by 40%, 36%, and 77%, respectively. Wnt agonist also decreased BUN and creatinine by 34% and 56%, respectively. Treatment reduced lung myeloperoxidase activity and IL-6 mRNA by 55% and 68% respectively and, significantly improved lung histology. Wnt agonist treatment increased Bcl-2 protein to Sham values and decreased cleaved caspase-3 by 46% indicating attenuation of hemorrhage-induced apoptosis in the lungs. Hemorrhage resulted in significant reductions of β-catenin protein levels in the lungs as well as down-regulation of a Wnt target gene, Cyclin-D1, while Wnt agonist treatment preserved these levels. Conclusions The administration of Wnt agonist attenuated hemorrhage-induced organ injury, inflammation and apoptosis. This was correlated with preservation of the Wnt signaling pathway. Thus, Wnt/β-catenin activation could be protective

  6. Regulation of beta catenin signaling and parathyroid hormone anabolic effects in bone by the matricellular protein periostin.

    PubMed

    Bonnet, Nicolas; Conway, Simon J; Ferrari, Serge L

    2012-09-11

    Periostin (Postn) is a matricellular protein preferentially expressed by osteocytes and periosteal osteoblasts in response to mechanical stimulation and parathyroid hormone (PTH). Whether and how periostin expression influences bone anabolism, however, remains unknown. We investigated the skeletal response of adult Postn(-/-) and Postn(+/+) mice to intermittent PTH. Compared with Postn(+/+), Postn(-/-) mice had a lower bone mass, cortical bone volume, and strength response to PTH. PTH-stimulated bone-forming indices were all significantly lower in Postn(-/-) mice, particularly at the periosteum. Furthermore, in vivo stimulation of Wnt-β-catenin signaling by PTH, as evaluated in TOPGAL reporter mice, was inhibited in the absence of periostin (TOPGAL;Postn(-/-) mice). PTH stimulated periostin and inhibited MEF2C and sclerostin (Sost) expression in bone and osteoblasts in vitro. Recombinant periostin also suppressed Sost expression, which was mediated through the integrin αVβ3 receptor, whereas periostin-blocking antibody prevented inhibition of MEF2C and Sost by PTH. In turn, administration of a Sost-blocking antiboby partially restored the PTH-mediated increase in bone mass in Postn(-/-) mice. In addition, primary osteoblasts from Postn(-/-) mice showed a lower proliferation, mineralization, and migration, both spontaneously and in response to PTH. Osteoblastic gene expression levels confirmed a defect of Postn(-/-) osteoblast differentiation with and without PTH, as well as an increased osteoblast apoptosis in the absence of periostin. These data elucidate the complex role of periostin on bone anabolism, through the regulation of Sost, Wnt-β-catenin signaling, and osteoblast differentiation.

  7. URG11 mediates hypoxia-induced epithelial-to-mesenchymal transition by modulation of E-cadherin and {beta}-catenin

    SciTech Connect

    Du, Rui; Huang, Chen; Bi, Qian; Zhai, Ying; Xia, Lin; Liu, Jie; Sun, Shiren; Fan, Daiming

    2010-01-01

    Upregulated gene 11 (URG11), recently identified as a new HBx-upregulated gene that may activate {beta}-catenin and Wnt signaling, was found to be upregulated in a human tubule cell line under low oxygen. Here, we investigated the potential role of URG11 in hypoxia-induced renal tubular epithelial-to-mesenchymal (EMT). Overexpression of URG11 in a human proximal tubule cell line (HK2) promoted a mesenchymal phenotype accompanied by reduced expression of the epithelial marker E-cadherin and increased expression of the mesenchymal markers vimentin and {alpha}-SMA, while URG11 knockdown by siRNA effectively reversed hypoxia-induced EMT. URG11 promoted the expression of {beta}-catenin and increased its nuclear accumulation under normoxic conditions through transactivation of the {beta}-catenin promoter. This in turn upregulated {beta}-catenin/T-cell factor (TCF) and its downstream effector genes, vimentin, and {alpha}-SMA. In vivo, strong expression of URG11 was observed in the tubular epithelia of 5/6-nephrectomized rats, and a Western blot analysis demonstrated a close correlation between HIF-1{alpha} and URG11 protein levels. Altogether, our results indicate that URG11 mediates hypoxia-induced EMT through the suppression of E-cadherin and the activation of the {beta}-catenin/TCF pathway.

  8. Regulation of beta catenin signaling and parathyroid hormone anabolic effects in bone by the matricellular protein periostin

    PubMed Central

    Bonnet, Nicolas; Conway, Simon J.; Ferrari, Serge L.

    2012-01-01

    Periostin (Postn) is a matricellular protein preferentially expressed by osteocytes and periosteal osteoblasts in response to mechanical stimulation and parathyroid hormone (PTH). Whether and how periostin expression influences bone anabolism, however, remains unknown. We investigated the skeletal response of adult Postn−/− and Postn+/+ mice to intermittent PTH. Compared with Postn+/+, Postn−/− mice had a lower bone mass, cortical bone volume, and strength response to PTH. PTH-stimulated bone-forming indices were all significantly lower in Postn−/− mice, particularly at the periosteum. Furthermore, in vivo stimulation of Wnt-β-catenin signaling by PTH, as evaluated in TOPGAL reporter mice, was inhibited in the absence of periostin (TOPGAL;Postn−/− mice). PTH stimulated periostin and inhibited MEF2C and sclerostin (Sost) expression in bone and osteoblasts in vitro. Recombinant periostin also suppressed Sost expression, which was mediated through the integrin αVβ3 receptor, whereas periostin-blocking antibody prevented inhibition of MEF2C and Sost by PTH. In turn, administration of a Sost-blocking antiboby partially restored the PTH-mediated increase in bone mass in Postn−/− mice. In addition, primary osteoblasts from Postn−/− mice showed a lower proliferation, mineralization, and migration, both spontaneously and in response to PTH. Osteoblastic gene expression levels confirmed a defect of Postn−/− osteoblast differentiation with and without PTH, as well as an increased osteoblast apoptosis in the absence of periostin. These data elucidate the complex role of periostin on bone anabolism, through the regulation of Sost, Wnt-β-catenin signaling, and osteoblast differentiation. PMID:22927401

  9. A WNT/beta-catenin signaling activator, R-spondin, plays positive regulatory roles during skeletal myogenesis.

    PubMed

    Han, Xiang Hua; Jin, Yong-Ri; Seto, Marianne; Yoon, Jeong Kyo

    2011-03-25

    R-spondins (RSPOs) are a recently characterized family of secreted proteins that activate WNT/β-catenin signaling. In this study, we investigated the potential roles of the RSPO proteins during myogenic differentiation. Overexpression of the Rspo1 gene or administration of recombinant RSPO2 protein enhanced mRNA and protein expression of a basic helix-loop-helix (bHLH) class myogenic determination factor, MYF5, in both C2C12 myoblasts and primary satellite cells, whereas MYOD or PAX7 expression was not affected. RSPOs also promoted myogenic differentiation and induced hypertrophic myotube formation in C2C12 cells. In addition, Rspo2 and Rspo3 gene knockdown by RNA interference significantly compromised MYF5 expression, myogenic differentiation, and myotube formation. Furthermore, Myf5 expression was reduced in the developing limbs of mouse embryos lacking the Rspo2 gene. Finally, we demonstrated that blocking of WNT/β-catenin signaling by DKK1 or a dominant-negative form of TCF4 reversed MYF5 expression, myogenic differentiation, and hypertrophic myotube formation induced by RSPO2, indicating that RSPO2 exerts its activity through the WNT/β-catenin signaling pathway. Our results provide strong evidence that RSPOs are key positive regulators of skeletal myogenesis acting through the WNT/β-catenin signaling pathway.

  10. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

    PubMed

    Li, Xiao; Florez, Sergio; Wang, Jianbo; Cao, Huojun; Amendt, Brad A

    2013-01-01

    Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  11. LRP4 mutations alter Wnt/beta-catenin signaling and cause limb and kidney malformations in Cenani-Lenz syndrome.

    PubMed

    Li, Yun; Pawlik, Barbara; Elcioglu, Nursel; Aglan, Mona; Kayserili, Hülya; Yigit, Gökhan; Percin, Ferda; Goodman, Frances; Nürnberg, Gudrun; Cenani, Asim; Urquhart, Jill; Chung, Boi-Dinh; Ismail, Samira; Amr, Khalda; Aslanger, Ayca D; Becker, Christian; Netzer, Christian; Scambler, Pete; Eyaid, Wafaa; Hamamy, Hanan; Clayton-Smith, Jill; Hennekam, Raoul; Nürnberg, Peter; Herz, Joachim; Temtamy, Samia A; Wollnik, Bernd

    2010-05-14

    Cenani-Lenz syndrome (CLS) is an autosomal-recessive congenital disorder affecting distal limb development. It is characterized mainly by syndactyly and/or oligodactyly and is now shown to be commonly associated with kidney anomalies. We used a homozygosity-mapping approach to map the CLS1 locus to chromosome 11p11.2-q13.1. By sequencing candidate genes, we identified recessive LRP4 mutations in 12 families with CLS. LRP4 belongs to the low-density lipoprotein (LDL) receptor-related proteins (LRPs), which are essential for various developmental processes. LRP4 is known to antagonize LRP6-mediated activation of canonical Wnt signaling, a function that is lost by the identified mutations. Our findings increase the spectrum of congenital anomalies associated with abnormal lipoprotein receptor-dependent signaling.

  12. Casein kinase iepsilon in the wnt pathway: regulation of beta-catenin function.

    PubMed

    Sakanaka, C; Leong, P; Xu, L; Harrison, S D; Williams, L T

    1999-10-26

    Wnt and its intracellular effector beta-catenin regulate developmental and oncogenic processes. Using expression cloning to identify novel components of the Wnt pathway, we isolated casein kinase Iepsilon (CKIepsilon). CKIepsilon mimicked Wnt in inducing a secondary axis in Xenopus, stabilizing beta-catenin, and stimulating gene transcription in cells. Inhibition of endogenous CKIepsilon by kinase-defective CKIepsilon or CKIepsilon antisense-oligonucleotides attenuated Wnt signaling. CKIepsilon was in a complex with axin and other downstream components of the Wnt pathway, including Dishevelled. CKIepsilon appears to be a positive regulator of the pathway and a link between upstream signals and the complexes that regulate beta-catenin. PMID:10535959

  13. Organized emergence of multiple-generations of teeth in snakes is dysregulated by activation of Wnt/beta-catenin signalling.

    PubMed

    Gaete, Marcia; Tucker, Abigail S

    2013-01-01

    In contrast to mammals, most reptiles constantly regenerate their teeth. In the snake, the epithelial dental lamina ends in a successional lamina, which proliferates and elongates forming multiple tooth generations, all linked by a permanent dental lamina. To investigate the mechanisms used to control the initiation of new tooth germs in an ordered sequential pattern we utilized the polyphodont (multiple-generation) corn snake (Pantherophis guttatus). We observed that the dental lamina expressed the transcription factor Sox2, a multipotent stem cell marker, whereas the successional lamina cells expressed the transcription factor Lef1, a Wnt/β-catenin pathway target gene. Activation of the Wnt/β-catenin pathway in culture increased the number of developing tooth germs, in comparison to control untreated cultures. These additional tooth germs budded off from ectopic positions along the dental lamina, rather than in an ordered sequence from the successional lamina. Wnt/β-catenin activation enhanced cell proliferation, particularly in normally non-odontogenic regions of the dental lamina, which widely expressed Lef1, restricting the Sox2 domain. This suggests an expansion of the successional lamina at the expense of the dental lamina. Activation of the Wnt/β-catenin pathway in cultured snake dental organs, therefore, led to changes in proliferation and to the molecular pattern of the dental lamina, resulting in loss of the organised emergence of tooth germs. These results suggest that epithelial compartments are critical for the arrangement of organs that develop in sequence, and highlight the role of Wnt/β-catenin signalling in such processes.

  14. Organized Emergence of Multiple-Generations of Teeth in Snakes Is Dysregulated by Activation of Wnt/Beta-Catenin Signalling

    PubMed Central

    Gaete, Marcia; Tucker, Abigail S.

    2013-01-01

    In contrast to mammals, most reptiles constantly regenerate their teeth. In the snake, the epithelial dental lamina ends in a successional lamina, which proliferates and elongates forming multiple tooth generations, all linked by a permanent dental lamina. To investigate the mechanisms used to control the initiation of new tooth germs in an ordered sequential pattern we utilized the polyphodont (multiple-generation) corn snake (Pantherophis guttatus). We observed that the dental lamina expressed the transcription factor Sox2, a multipotent stem cell marker, whereas the successional lamina cells expressed the transcription factor Lef1, a Wnt/β-catenin pathway target gene. Activation of the Wnt/β-catenin pathway in culture increased the number of developing tooth germs, in comparison to control untreated cultures. These additional tooth germs budded off from ectopic positions along the dental lamina, rather than in an ordered sequence from the successional lamina. Wnt/β-catenin activation enhanced cell proliferation, particularly in normally non-odontogenic regions of the dental lamina, which widely expressed Lef1, restricting the Sox2 domain. This suggests an expansion of the successional lamina at the expense of the dental lamina. Activation of the Wnt/β-catenin pathway in cultured snake dental organs, therefore, led to changes in proliferation and to the molecular pattern of the dental lamina, resulting in loss of the organised emergence of tooth germs. These results suggest that epithelial compartments are critical for the arrangement of organs that develop in sequence, and highlight the role of Wnt/β-catenin signalling in such processes. PMID:24019968

  15. Murrayafoline A attenuates the Wnt/{beta}-catenin pathway by promoting the degradation of intracellular {beta}-catenin proteins

    SciTech Connect

    Choi, Hyuk; Gwak, Jungsug; Cho, Munju; Ryu, Min-Jung; Lee, Jee-Hyun; Kim, Sang Kyum; Kim, Young Ho; Lee, Gye Won; Yun, Mi-Young; Cuong, Nguyen Manh; Shin, Jae-Gook; Song, Gyu-Yong; Oh, Sangtaek

    2010-01-01

    Molecular lesions in Wnt/{beta}-catenin signaling and subsequent up-regulation of {beta}-catenin response transcription (CRT) occur frequently during the development of colon cancer. To identify small molecules that suppress CRT, we screened natural compounds in a cell-based assay for detection of TOPFalsh reporter activity. Murrayafoline A, a carbazole alkaloid isolated from Glycosmis stenocarpa, antagonized CRT that was stimulated by Wnt3a-conditioned medium (Wnt3a-CM) or LiCl, an inhibitor of glycogen synthase kinase-3{beta} (GSK-3{beta}), and promoted the degradation of intracellular {beta}-catenin without altering its N-terminal phosphorylation at the Ser33/37 residues, marking it for proteasomal degradation, or the expression of Siah-1, an E3 ubiquitin ligase. Murrayafoline A repressed the expression of cyclin D1 and c-myc, which is known {beta}-catenin/T cell factor (TCF)-dependent genes and thus inhibited the proliferation of various colon cancer cells. These findings indicate that murrayafoline A may be a potential chemotherapeutic agent for use in the treatment of colon cancer.

  16. Excess beta-catenin promotes accumulation of transcriptionally active p53.

    PubMed Central

    Damalas, A; Ben-Ze'ev, A; Simcha, I; Shtutman, M; Leal, J F; Zhurinsky, J; Geiger, B; Oren, M

    1999-01-01

    beta-catenin is a multifunctional protein, acting both as a structural component of the cell adhesion machinery and as a transducer of extracellular signals. Deregulated beta-catenin protein expression, due to mutations in the beta-catenin gene itself or in its upstream regulator, the adenomatous polyposis coli (APC) gene, is prevalent in colorectal cancer and in several other tumor types, and attests to the potential oncogenic activity of this protein. Increased expression of beta-catenin is an early event in colorectal carcinogenesis, and is usually followed by a later mutational inactivation of the p53 tumor suppressor. To examine whether these two key steps in carcinogenesis are interrelated, we studied the effect of excess beta-catenin on p53. We report here that overexpression of beta-catenin results in accumulation of p53, apparently through interference with its proteolytic degradation. This effect involves both Mdm2-dependent and -independent p53 degradation pathways, and is accompanied by augmented transcriptional activity of p53 in the affected cells. Increased p53 activity may provide a safeguard against oncogenic deregulation of beta-catenin, and thus impose a pressure for mutational inactivation of p53 during the later stages of tumor progression. PMID:10357817

  17. PECAM-1 affects GSK-3beta-mediated beta-catenin phosphorylation and degradation.

    PubMed

    Biswas, Purba; Canosa, Sandra; Schoenfeld, David; Schoenfeld, Jonathan; Li, Puyau; Cheas, Lydia C; Zhang, Jin; Cordova, Alfredo; Sumpio, Bauer; Madri, Joseph A

    2006-07-01

    Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) regulates a variety of endothelial and immune cell biological responses. PECAM-1-null mice exhibit prolonged and increased permeability after inflammatory insults. We observed that in PECAM-1-null endothelial cells (ECs), beta-catenin remained tyrosine phosphorylated, coinciding with a sustained increase in permeability. Src homology 2 domain containing phosphatase 2 (SHP-2) association with beta-catenin was diminished in PECAM-1-null ECs, suggesting that lack of PECAM-1 inhibits the ability of this adherens junction component to become dephosphorylated, promoting a sustained increase in permeability. beta-Catenin/Glycogen synthase kinase 3 (GSK-3beta) association and beta-catenin serine phosphorylation levels were increased and beta-catenin expression levels were reduced in PECAM-1-null ECs. Glycogen synthase kinase 3 (GSK-3beta) serine phosphorylation (inactivation) was blunted in PECAM-1-null ECs after histamine treatment or shear stress. Our data suggest that PECAM-1 serves as a critical dynamic regulator of endothelial barrier permeability. On stimulation by a vasoactive substance or shear stress, PECAM-1 became tyrosine phosphorylated, enabling recruitment of SHP-2 and tyrosine-phosphorylated beta-catenin to its cytoplasmic domain, facilitating dephosphorylation of beta-catenin, and allowing reconstitution of adherens junctions. In addition, PECAM-1 modulated the levels of beta-catenin by regulating the activity of GSK-3beta, which in turn affected the serine phosphorylation of beta-catenin and its proteosomal degradation, affecting the ability of the cell to reform adherens junctions in a timely fashion. PMID:16816383

  18. An ancient role for nuclear beta-catenin in the evolution of axial polarity and germ layer segregation

    NASA Technical Reports Server (NTRS)

    Wikramanayake, Athula H.; Hong, Melanie; Lee, Patricia N.; Pang, Kevin; Byrum, Christine A.; Bince, Joanna M.; Xu, Ronghui; Martindale, Mark Q.

    2003-01-01

    The human oncogene beta-catenin is a bifunctional protein with critical roles in both cell adhesion and transcriptional regulation in the Wnt pathway. Wnt/beta-catenin signalling has been implicated in developmental processes as diverse as elaboration of embryonic polarity, formation of germ layers, neural patterning, spindle orientation and gap junction communication, but the ancestral function of beta-catenin remains unclear. In many animal embryos, activation of beta-catenin signalling occurs in blastomeres that mark the site of gastrulation and endomesoderm formation, raising the possibility that asymmetric activation of beta-catenin signalling specified embryonic polarity and segregated germ layers in the common ancestor of bilaterally symmetrical animals. To test whether nuclear translocation of beta-catenin is involved in axial identity and/or germ layer formation in 'pre-bilaterians', we examined the in vivo distribution, stability and function of beta-catenin protein in embryos of the sea anemone Nematostella vectensis (Cnidaria, Anthozoa). Here we show that N. vectensis beta-catenin is differentially stabilized along the oral-aboral axis, translocated into nuclei in cells at the site of gastrulation and used to specify entoderm, indicating an evolutionarily ancient role for this protein in early pattern formation.

  19. Functional correlates of mutation of the Asp32 and Gly34 residues of beta-catenin.

    PubMed

    Provost, Elayne; McCabe, Anthony; Stern, Jessica; Lizardi, Isabel; D'Aquila, Thomas G; Rimm, David L

    2005-04-14

    Beta-catenin is a multifunctional protein involved in both cadherin-mediated adhesion and the wnt signaling cascade. Mutations in exon 3 of beta-catenin have been identified in many cancers. In addition to disruption of key serine and threonine residues, mutations are frequently reported in other residues in exon 3 that are not kinase substrates. The most frequently mutated nonserine/threonine residues are D32 and G34. Since D32 and G34 are part of the ubiquitination destruction motif, DSGPhiXS, we hypothesize that this motif may contribute to disruption of beta-catenin homeostasis and lead to cellular transformation. We demonstrate that the mutants D32A and G34A exhibit no change in phosphorylation by GSK3beta, but display reduced ubiquitination compared to wild-type and S33A mutant beta-catenin. To assess the functional implications of these mutations, we created stable MDCK cell lines expressing these constructs. We found that stable cell lines harboring D32A-mutated beta-catenin were highly transformed, while S33A and G34 demonstrated only weak transforming properties in our assays. Despite altered ubiquitination status and increased transformation, the D32A mutant cell line does not display transcriptional activation of standard target genes. Therefore, D32A mutation may mediate transformation by an alternative beta-catenin-mediated signaling pathway.

  20. Caveolin-1-mediated suppression of cyclooxygenase-2 via a beta-catenin-Tcf/Lef-dependent transcriptional mechanism reduced prostaglandin E2 production and survivin expression.

    PubMed

    Rodriguez, Diego A; Tapia, Julio C; Fernandez, Jaime G; Torres, Vicente A; Muñoz, Nicolas; Galleguillos, Daniela; Leyton, Lisette; Quest, Andrew F G

    2009-04-01

    Augmented expression of cyclooxygenase-2 (COX-2) and enhanced production of prostaglandin E(2) (PGE(2)) are associated with increased tumor cell survival and malignancy. Caveolin-1 is a scaffold protein that has been proposed to function as a tumor suppressor in human cancer cells, although mechanisms underlying this ability remain controversial. Intriguingly, the possibility that caveolin-1 regulates the expression of COX-2 has not been explored. Here we show that augmented caveolin-1 expression in cells with low basal levels of this protein, such as human colon cancer (HT29, DLD-1), breast cancer (ZR75), and embryonic kidney (HEK293T) cells reduced COX-2 mRNA and protein levels and beta-catenin-Tcf/Lef and COX-2 gene reporter activity, as well as the production of PGE(2) and cell proliferation. Moreover, COX-2 overexpression or PGE(2) supplementation increased levels of the inhibitor of apoptosis protein survivin by a transcriptional mechanism, as determined by PCR analysis, survivin gene reporter assays and Western blotting. Furthermore, addition of PGE(2) to the medium prevented effects attributed to caveolin-1-mediated inhibition of beta-catenin-Tcf/Lef-dependent transcription. Finally, PGE(2) reduced the coimmunoprecipitation of caveolin-1 with beta-catenin and their colocalization at the plasma membrane. Thus, by reducing COX-2 expression, caveolin-1 interrupts a feedback amplification loop involving PGE(2)-induced signaling events linked to beta-catenin/Tcf/Lef-dependent transcription of tumor survival genes including cox-2 itself and survivin. PMID:19244345

  1. SIRT1 inhibits proliferation of pancreatic cancer cells expressing pancreatic adenocarcinoma up-regulated factor (PAUF), a novel oncogene, by suppression of {beta}-catenin

    SciTech Connect

    Cho, Il-Rae; Koh, Sang Seok; Malilas, Waraporn; Srisuttee, Ratakorn; Moon, Jeong; Choi, Young-Whan; Horio, Yoshiyuki; Oh, Sangtaek; Chung, Young-Hwa

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer SIRT1 inhibits protein levels of {beta}-catenin and its transcriptional activity. Black-Right-Pointing-Pointer Nuclear localization of SIRT1 is not required for the decrease of {beta}-catenin expression. Black-Right-Pointing-Pointer SIRT1-mediated degradation of {beta}-catenin is not required for GSK-3{beta} and Siah-1 but for proteosome. Black-Right-Pointing-Pointer SIRT1 activation inhibits proliferation of pancreatic cancer cells expressing PAUF. -- Abstract: Because we found in a recent study that pancreatic adenocarcinoma up-regulated factor (PAUF), a novel oncogene, induces a rapid proliferation of pancreatic cells by up-regulation of {beta}-catenin, we postulated that {beta}-catenin might be a target molecule for pancreatic cancer treatment. We thus speculated whether SIRT1, known to target {beta}-catenin in a colon cancer model, suppresses {beta}-catenin in those pancreatic cancer cells that express PAUF (Panc-PAUF). We further evaluated whether such suppression would lead to inhibition of the proliferation of these cells. The ectopic expression of either SIRT1 or resveratrol (an activator of SIRT1) suppressed levels of {beta}-catenin protein and its transcriptional activity in Panc-PAUF cells. Conversely, suppression of SIRT1 expression by siRNA enhanced {beta}-catenin expression and transcriptional activity. SIRT1 mutant analysis showed that nuclear localization of SIRT1 is not required for reduction of {beta}-catenin. Treatment with MG132, a proteasomal inhibitor, restored {beta}-catenin protein levels, suggesting that SIRT1-mediated degradation of {beta}-catenin requires proteasomal activity. It was reported that inhibition of GSK-3{beta} or Siah-1 stabilizes {beta}-catenin in colon cancer cells, but suppression of GSK-3{beta} or Siah-1 using siRNA in the presence of resveratrol instead diminished {beta}-catenin protein levels in Panc-PAUF cells. This suggests that GSK-3{beta} and Siah-1 are not involved in SIRT1

  2. beta-Catenin/TCF pathway plays a vital role in selenium induced-growth inhibition and apoptosis in esophageal squamous cell carcinoma (ESCC) cells.

    PubMed

    Zhang, Wei; Yan, Shuang; Liu, Mei; Zhang, Guo; Yang, Shangbin; He, Shun; Bai, Jinfeng; Quan, Lanping; Zhu, Hongxia; Dong, Yan; Xu, Ningzhi

    2010-10-01

    Epidemiological and experimental studies have indicated selenium could reduce the risk of some cancers. In our present study, growth inhibition and apoptosis were detected upon methylseleninic acid (MSA) treatment in human esophageal squamous cell carcinoma cell lines EC9706 and KYSE150. MSA reduced beta-catenin protein levels, while there was no significant change observed on transcriptional levels. Moreover, we found MSA accelerated the degradation of beta-catenin and activated glycogen synthase kinase 3beta (GSK-3beta). Some targets of beta-catenin/TCF pathway and apoptosis-related genes altered after MSA treatment. Notably, utilizing the inducible 293-TR/beta-catenin cell line, we found the apoptotic phenotypes induced by MSA were partially reversed by the overexpression of beta-catenin. Overall, our data indicate the effects induced by MSA in ESCC cells may act on the inhibition of beta-catenin/TCF pathway.

  3. MiR-214 inhibits cell growth in hepatocellular carcinoma through suppression of {beta}-catenin

    SciTech Connect

    Wang, Xiaojun; Chen, Ji; Li, Feng; Lin, Yanting; Zhang, Xiaoping; Lv, Zhongwei; Jiang, Jiaji

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer miR-214 is frequently downregulated in human HCC cell lines and tissues. Black-Right-Pointing-Pointer miR-214 overexpression inhibits HCC cell growth in vitro and in vivo. Black-Right-Pointing-Pointer miR-214 directly targets {beta}-catenin 3 Prime -UTR in HCC cells. Black-Right-Pointing-Pointer miR-214 regulates {beta}-catenin downstream signaling molecules. -- Abstract: Mounting evidence has shown that microRNAs (miRNAs) are implicated in carcinogenesis and can function as oncogenes or tumor suppressor genes in human cancers. Recent profile studies of miRNA expression have documented a deregulation of miRNA (miR-214) in hepatocellular carcinoma (HCC). However, its potential functions and underlying mechanisms in hepatocarcinogenesis remain largely unknown. Here, we confirmed that miR-214 is significantly downregulated in HCC cells and specimens. Ectopic overexpression of miR-214 inhibited proliferation of HCC cells in vitro and tumorigenicity in vivo. Further studies revealed that miR-214 could directly target the 3 Prime -untranslated region (3 Prime -UTR) of {beta}-catenin mRNA and suppress its protein expression. Similar to the restoring miR-214 expression, {beta}-catenin downregulation inhibited cell growth, whereas restoring the {beta}-catenin expression abolished the function of miR-214. Moreover, miR-214-mediated reduction of {beta}-catenin resulted in suppression of several downstream genes including c-Myc, cyclinD1, TCF-1, and LEF-1. These findings indicate that miR-214 serves as tumor suppressor and plays substantial roles in inhibiting the tumorigenesis of HCC through suppression of {beta}-catenin. Given these, miR-214 may serve as a useful prognostic or therapeutic target for treatment of HCC.

  4. Opposite Interplay between PPAR Gamma and Canonical Wnt/Beta-Catenin Pathway in Amyotrophic Lateral Sclerosis.

    PubMed

    Lecarpentier, Yves; Vallée, Alexandre

    2016-01-01

    The opposite interplay between peroxisome proliferator-activated receptor gamma (PPAR gamma) and Wnt/beta-catenin signaling has led to the categorization of neurodegenerative diseases (NDs) as either NDs in which PPAR gamma is downregulated while the canonical Wnt/beta-catenin pathway is upregulated [amyotrophic lateral sclerosis (ALS), Parkinson's disease, Huntington's disease, multiple sclerosis, Friedreich's ataxia] or NDs in which PPAR gamma is upregulated while the canonical Wnt/beta-catenin signaling is downregulated (bipolar disorder, schizophrenia, Alzheimer's disease). ALS, a common adult-onset debilitating ND, is characterized by a chronic and progressive degeneration of upper and lower motor neurons resulting in muscular atrophy, paralysis, and ultimately death. The intent of this review is to provide an analysis of the integration of these two opposed systems, i.e., canonical Wnt/beta-catenin and PPAR gamma, in ALS. Understanding this integration may aid in the development of novel ALS therapies. Although the canonical Wnt/beta-catenin pathway is upregulated in ALS, riluzole, an enhancer of the canonical Wnt signaling, is classically prescribed in this disease in humans. However, studies carried out on ALS transgenic mice have shown beneficial effects after treatment by PPAR gamma agonists partly due to their anti-inflammatory effects. PMID:27445967

  5. Opposite Interplay between PPAR Gamma and Canonical Wnt/Beta-Catenin Pathway in Amyotrophic Lateral Sclerosis

    PubMed Central

    Lecarpentier, Yves; Vallée, Alexandre

    2016-01-01

    The opposite interplay between peroxisome proliferator-activated receptor gamma (PPAR gamma) and Wnt/beta-catenin signaling has led to the categorization of neurodegenerative diseases (NDs) as either NDs in which PPAR gamma is downregulated while the canonical Wnt/beta-catenin pathway is upregulated [amyotrophic lateral sclerosis (ALS), Parkinson’s disease, Huntington’s disease, multiple sclerosis, Friedreich’s ataxia] or NDs in which PPAR gamma is upregulated while the canonical Wnt/beta-catenin signaling is downregulated (bipolar disorder, schizophrenia, Alzheimer’s disease). ALS, a common adult-onset debilitating ND, is characterized by a chronic and progressive degeneration of upper and lower motor neurons resulting in muscular atrophy, paralysis, and ultimately death. The intent of this review is to provide an analysis of the integration of these two opposed systems, i.e., canonical Wnt/beta-catenin and PPAR gamma, in ALS. Understanding this integration may aid in the development of novel ALS therapies. Although the canonical Wnt/beta-catenin pathway is upregulated in ALS, riluzole, an enhancer of the canonical Wnt signaling, is classically prescribed in this disease in humans. However, studies carried out on ALS transgenic mice have shown beneficial effects after treatment by PPAR gamma agonists partly due to their anti-inflammatory effects. PMID:27445967

  6. Induction of a secondary body axis in Xenopus by antibodies to beta-catenin.

    PubMed

    McCrea, P D; Brieher, W M; Gumbiner, B M

    1993-10-01

    We have obtained evidence that a known intracellular component of the cadherin cell-cell adhesion machinery, beta-catenin, contributes to the development of the body axis in the frog Xenopus laevis. Vertebrate beta-catenin is homologous to the Drosophila segment polarity gene product armadillo, and to vertebrate plakoglobin (McCrea, P. D., C. W. Turck, and B. Gumbiner. 1991. Science (Wash. DC). 254: 1359-1361.). Beta-Catenin was found present in all Xenopus embryonic stages examined, and associated with C-cadherin, the major cadherin present in early Xenopus embryos. To test beta-catenin's function, affinity purified Fab fragments were injected into ventral blastomeres of developing four-cell Xenopus embryos. A dramatic phenotype, the duplication of the dorsoanterior embryonic axis, was observed. Furthermore, Fab injections were capable of rescuing dorsal features in UV-ventralized embryos. Similar phenotypes have been observed in misexpression studies of the Wnt and other gene products, suggesting that beta-catenin participates in a signaling pathway which specifies embryonic patterning. PMID:8408227

  7. {beta}-Catenin can act as a nuclear import receptor for its partner transcription factor, lymphocyte enhancer factor-1 (lef-1)

    SciTech Connect

    Asally, Munehiro; Yoneda, Yoshihiro . E-mail: yyoneda@anat3.med.osaka-u.ac.jp

    2005-08-15

    Nuclear accumulation of {beta}-catenin plays an important role in the Wnt signaling pathway. In the nucleus, {beta}-catenin acts as a transcriptional co-activator for TCF/LEF family of transcription factors. It has been shown that lef-1 contains a typical basic type nuclear localization signal (NLS) and is transported into the nucleus by the conventional import pathway. In this study, we found that a mutant lef-1 lacking the classical NLS accumulated in the nucleus of living cells, when {beta}-catenin was co-expressed. In addition, in a cell-free import assay, lef-1 migrated into the nucleus in the presence of {beta}-catenin alone without any other soluble factors. In contrast, another mutant lef-1 lacking the {beta}-catenin binding domain failed to migrate into the nucleus, even in the presence of {beta}-catenin. These findings indicate that {beta}-catenin alone can mediate the nuclear import of lef-1 through the direct binding. Collectively, we propose that there are two distinct pathways for the nuclear import of lef-1: importin {alpha}/{beta}-mediated and {beta}-catenin-mediated one, which provides a novel paradigm for Wnt signaling pathway.

  8. Tau overexpression in transgenic mice induces glycogen synthase kinase 3beta and beta-catenin phosphorylation.

    PubMed

    Shim, S B; Lim, H J; Chae, K R; Kim, C K; Hwang, D Y; Jee, S W; Lee, S H; Sin, J S; Leem, Y H; Lee, S H; Cho, J S; Lee, H H; Choi, S Y; Kim, Y K

    2007-05-11

    The abnormal phosphorylations of tau, GSK3beta, and beta-catenin have been shown to perform a crucial function in the neuropathology of Alzheimer's disease (AD). The primary objective of the current study was to determine the manner in which overexpressed htau23 interacts and regulates the behavior and phosphorylation characteristics of tau, GSK3beta, and beta-catenin. In order to accomplish this, transgenic mice expressing neuron-specific enolase (NSE)-controlled human wild-type tau (NSE/htau23) were created. Transgenic mice evidenced the following: (i) tendency toward memory impairments at later stages, (ii) dramatic overexpression of the tau transgene, coupled with increased tau phosphorylation and paired helical filaments (PHFs), (iii) high levels of GSK3beta phosphorylation with advanced age, resulting in increases in the phosphorylations of tau and beta-catenin, (iv) an inhibitory effect of lithium on the phosphorylations of tau, GSK3beta, and beta-catenin, but not in the non-transgenic littermate group. Therefore, the overexpression of NSE/htau23 in the brains of transgenic mice induces abnormal phosphorylations of tau, GSK3beta, and beta-catenin, which are ultimately linked to neuronal degeneration in cases of AD. These transgenic mice are expected to prove useful for the development of new drugs for the treatment of AD.

  9. APP induces neuronal apoptosis through APP-BP1-mediated downregulation of beta-catenin.

    PubMed

    Chen, Y Z

    2004-07-01

    Alzheimer's disease (AD) is a neurodegenerative disease associated with progressive dementia. This mini-review focuses on how the amyloid precursor protein (APP) plays a central role in AD and Down syndrome as the regulator of the APP-BP1/hUba3 activated neddylation pathway. It is argued that the physiological function of APP is to downregulate the level of beta-catenin. However, this APP function is abnormally amplified in patients with familial AD (FAD) mutations in APP and presenilins, resulting in the hyperactivation of neddylation and the decrease of beta-catenin below a threshold level. Evidence in the literature is summarized to show that dysfunction of APP in downregulating beta-catenin may underlie the mechanism of neuronal death in AD and Down syndrome. PMID:15192323

  10. Overexpression of Wnt-1 in thyrocytes enhances cellular growth but suppresses transcription of the thyroperoxidase gene via different signaling mechanisms.

    PubMed

    Kim, Won Bae; Lewis, Christopher J; McCall, Kelly D; Malgor, Ramiro; Kohn, Aimee D; Moon, Randall T; Kohn, Leonard D

    2007-04-01

    Wnt binding to cell surface receptors can activate a 'canonical' pathway that increases cellular beta-catenin or a 'noncanonical' Ca(++) pathway which can increase protein kinase C (PKC) activity. Although components of both Wnt/beta-catenin-signaling pathways exist in thyrocytes, their biological role is largely unknown. In evaluating the biological role of Wnt signaling in differentiated FRTL-5 thyroid cells, we showed that TSH increased canonical Wnt-1 but, surprisingly, decreased the active form of beta-catenin. Transient overexpression of Wnt-1 or beta-catenin in FRTL-5 cells increased active beta-catenin (ABC), decreased thyroperoxidase (TPO) mRNA, and suppressed TPO-promoter activity. The target of beta-catenin suppressive action was a consensus T cell factor/lymphoid enhancing factor (TCF/LEF)-binding site 5'-A/T A/T CAAAG-3', -137 to -129 bp on the rat TPO promoter. beta-Catenin overexpression significantly increased complex formation between beta-catenin/TCF-1 and an oligonucleotide containing the TCF/LEF sequence, suggesting that the beta-catenin/TCF-1 complex acts as a transcriptional repressor of the TPO gene. Stable over-expression of Wnt-1 in FRTL-5 cells significantly increased the growth rate without increasing beta-catenin levels. Increased growth was blunted by a PKC inhibitor, staurosporin. Wnt-1 overexpression increased serine phosphorylation, without affecting tyrosine phosphorylation, of signal transducers and activators of transcription 3 (STAT3) protein. In addition, these final results suggest that TSH-induced increase in Wnt-1 levels in thyrocytes contributes to enhanced cellular growth via a PKC pathway that increases STAT3 serine phosphorylation and activation, whereas TSH-induced decrease in activation of beta-catenin simultaneously relieves transcriptional suppression of TPO. We hypothesize that Wnt signaling contributes to the ability of TSH to simultaneously increase cell growth and functional, thyroid-specific, gene expression

  11. Pleiotrophin induces neurite outgrowth and up-regulates growth-associated protein (GAP)-43 mRNA through the ALK/GSK3beta/beta-catenin signaling in developing mouse neurons.

    PubMed

    Yanagisawa, Hiroko; Komuta, Yukari; Kawano, Hitoshi; Toyoda, Masashi; Sango, Kazunori

    2010-01-01

    Pleiotrophin (PTN) is highly expressed in the nervous system during embryogenesis; however, little is known about its functional role in neural development. By using whole mount in situ hybridization, we observed that the expression pattern of PTN was similar to that of Wnt3a; PTN mRNA was abundant in the nervous tissue along the dorsal midline and in the forelimb and hindlimb buds of embryonic mice (E8.5-E12.5). Treatment with recombinant PTN (100ng/ml) induced phosphorylation of glycogen synthase kinase 3beta (GSK3beta), nuclear localization of beta-catenin and up-regulation of growth-associated protein (GAP)-43 mRNA in cultured embryonic mouse (E14.5) neurons. Furthermore, recombinant PTN enhanced neurite outgrowth from cortical explants embedded in Matrigel. These PTN-induced biochemical changes and neurite outgrowth were attenuated by the co-treatment with anti-anaplastic lymphoma kinase (ALK) antibodies, but not with anti-protein tyrosine phosphatase (PTP)zeta antibodies. These findings imply that ALK is involved in the PTN signaling on neural development.

  12. Spatio-temporal Model of Endogenous ROS and Raft-Dependent WNT/Beta-Catenin Signaling Driving Cell Fate Commitment in Human Neural Progenitor Cells

    PubMed Central

    Haack, Fiete; Lemcke, Heiko; Ewald, Roland; Rharass, Tareck; Uhrmacher, Adelinde M.

    2015-01-01

    Canonical WNT/β-catenin signaling is a central pathway in embryonic development, but it is also connected to a number of cancers and developmental disorders. Here we apply a combined in-vitro and in-silico approach to investigate the spatio-temporal regulation of WNT/β-catenin signaling during the early neural differentiation process of human neural progenitors cells (hNPCs), which form a new prospect for replacement therapies in the context of neurodegenerative diseases. Experimental measurements indicate a second signal mechanism, in addition to canonical WNT signaling, being involved in the regulation of nuclear β-catenin levels during the cell fate commitment phase of neural differentiation. We find that the biphasic activation of β-catenin signaling observed experimentally can only be explained through a model that combines Reactive Oxygen Species (ROS) and raft dependent WNT/β-catenin signaling. Accordingly after initiation of differentiation endogenous ROS activates DVL in a redox-dependent manner leading to a transient activation of down-stream β-catenin signaling, followed by continuous auto/paracrine WNT signaling, which crucially depends on lipid rafts. Our simulation studies further illustrate the elaborate spatio-temporal regulation of DVL, which, depending on its concentration and localization, may either act as direct inducer of the transient ROS/β-catenin signal or as amplifier during continuous auto-/parcrine WNT/β-catenin signaling. In addition we provide the first stochastic computational model of WNT/β-catenin signaling that combines membrane-related and intracellular processes, including lipid rafts/receptor dynamics as well as WNT- and ROS-dependent β-catenin activation. The model’s predictive ability is demonstrated under a wide range of varying conditions for in-vitro and in-silico reference data sets. Our in-silico approach is realized in a multi-level rule-based language, that facilitates the extension and modification of the

  13. Isoreserpine promotes {beta}-catenin degradation via Siah-1 up-regulation in HCT116 colon cancer cells

    SciTech Connect

    Gwak, Jungsug; Song, Taeyun; Song, Jie-Young; Yun, Yeon-Sook; Choi, Il-Whan; Jeong, Yongsu; Shin, Jae-Gook; Oh, Sangtaek

    2009-09-25

    Aberrant accumulation of intracellular {beta}-catenin in intestinal epithelial cells is a frequent early event during the development of colon cancer. To identify small molecules that decrease the level of intracellular {beta}-catenin, we performed cell-based chemical screening using genetically engineered HEK293 reporter cells to detect compounds that inhibit TOPFlash reporter activity, which was stimulated by Wnt3a-conditioned medium. We found that isoreserpine promoted the degradation of intracellular {beta}-catenin by up-regulation of Siah-1 in HEK293 and HCT116 colon cancer cells. Moreover, isoreserpine repressed the expression of {beta}-catenin/T-cell factor (TCF)-dependent genes, such as cyclin D1 and c-myc, resulting in the suppression of HCT116 cell proliferation. Our findings suggest that isoreserpine can potentially be used as a chemotherapeutic agent against colon cancer.

  14. Frequent beta-catenin mutations in juvenile nasopharyngeal angiofibromas.

    PubMed

    Abraham, S C; Montgomery, E A; Giardiello, F M; Wu, T T

    2001-03-01

    Juvenile nasopharyngeal angiofibromas (JNAs) are locally aggressive vascular tumors occurring predominantly in adolescent males. The pathogenesis of JNAs is unknown. Recently, JNAs have been reported to occur at increased frequency among patients with familial adenomatous polyposis, suggesting that alterations of the adenomatous polyposis coli (APC)/beta-catenin pathway might also be involved in the pathogenesis of sporadic JNAs. We analyzed somatic beta-catenin and APC gene mutations in 16 sporadic JNAs from nonfamilial adenomatous polyposis patients using immunohistochemistry for beta-catenin, and direct DNA sequencing for exon 3 of the beta-catenin gene and the mutation cluster region of the APC gene. Nuclear accumulation of beta-catenin was diffusely present in the stromal cells but not in the endothelial cells of all 16 JNAs. Activating beta-catenin gene mutations were present in 75% (12 of 16) of JNAs. Six JNA patients also had recurrent tumors after surgery, and in all cases the beta-catenin gene status of the recurrent JNA was identical to the initial tumor. No mutations in the mutation cluster region of the APC gene were detected in the four JNAs without beta-catenin mutations. The high frequency of beta-catenin mutations in sporadic JNAs and the presence of identical beta-catenin gene mutations in recurrent tumors indicates that activating beta-catenin gene mutations are important in the pathogenesis of JNAs. The immunohistochemical localization of beta-catenin only to the nuclei of stromal cells further suggests that the stromal cells, rather than endothelial cells, are the neoplastic cells of JNAs.

  15. Stabilization of beta-catenin in XY gonads causes male-to-female sex-reversal.

    PubMed

    Maatouk, Danielle M; DiNapoli, Leo; Alvers, Ashley; Parker, Keith L; Taketo, Makoto M; Capel, Blanche

    2008-10-01

    During mammalian sex determination, expression of the Y-linked gene Sry shifts the bipotential gonad toward a testicular fate by upregulating a feed-forward loop between FGF9 and SOX9 to establish SOX9 expression in somatic cells. We previously proposed that these signals are mutually antagonistic with counteracting signals in XX gonads and that a shift in the balance of these factors leads to either male or female development. Evidence in mice and humans suggests that the male pathway is opposed by the expression of two signals, WNT4 and R-SPONDIN-1 (RSPO1), that promote the ovarian fate and block testis development. Both of these ligands can activate the canonical Wnt signaling pathway. Duplication of the distal portion of chromosome 1p, which includes both WNT4 and RSPO1, overrides the male program and causes male-to-female sex reversal in XY patients. To determine whether activation of beta-catenin is sufficient to block the testis pathway, we have ectopically expressed a stabilized form of beta-catenin in the somatic cells of XY gonads. Our results show that activation of beta-catenin in otherwise normal XY mice effectively disrupts the male program and results in male-to-female sex-reversal. The identification of beta-catenin as a key pro-ovarian and anti-testis signaling molecule will further our understanding of the mechanisms controlling sex determination and the molecular mechanisms that lead to sex-reversal. PMID:18617533

  16. Gamma-secretase-dependent and -independent effects of presenilin1 on beta-catenin.Tcf-4 transcriptional activity.

    PubMed

    Raurell, Imma; Codina, Montserrat; Casagolda, David; Del Valle, Beatriz; Baulida, Josep; de Herreros, Antonio García; Duñach, Mireia

    2008-01-01

    Presenilin1 (PS1) is a component of the gamma-secretase complex mutated in cases of Familial Alzheimer's disease (FAD). PS1 is synthesized as a 50 kDa peptide subsequently processed to two 29 and 20 kDa subunits that remain associated. Processing of PS1 is inhibited by several mutations detected in FAD patients. PS1 acts as negative modulator of beta-catenin.Tcf-4 transcriptional activity. In this article we show that in murine embryonic fibroblasts (MEFs) the mechanisms of action of the processed and non-processed forms of PS1 on beta-catenin.Tcf-4 transcription are different. Whereas non-processed PS1 inhibits beta-catenin.Tcf-4 activity through a mechanism independent of gamma-secretase and associated with the interaction of this protein with plakoglobin and Tcf-4, the effect of processed PS1 is prevented by gamma-secretase inhibitors, and requires its interaction with E- or N-cadherin and the generation of cytosolic terminal fragments of these two cadherins, which in turn destabilize the beta-catenin transcriptional cofactor CBP. Accordingly, the two forms of PS1 interact differently with E-cadherin or beta-catenin and plakoglobin: whereas processed PS1 binds E-cadherin with high affinity and beta-catenin or plakoglobin weakly, the non-processed form behaves inversely. Moreover, contrarily to processed PS1, that decreases the levels of c-fos RNA, non-processed PS1 inhibits the expression c-myc, a known target of beta-catenin.Tcf-4, and does not block the activity of other transcriptional factors requiring CBP. These results indicate that prevention of PS1 processing in FAD affects the mechanism of repression of the transcriptional activity dependent on beta-catenin. PMID:19114997

  17. The APC tumor suppressor binds to C-terminal binding protein to divert nuclear beta-catenin from TCF.

    PubMed

    Hamada, Fumihiko; Bienz, Mariann

    2004-11-01

    Adenomatous polyposis coli (APC) is an important tumor suppressor in the colon. APC antagonizes the transcriptional activity of the Wnt effector beta-catenin by promoting its nuclear export and its proteasomal destruction in the cytoplasm. Here, we show that a third function of APC in antagonizing beta-catenin involves C-terminal binding protein (CtBP). APC is associated with CtBP in vivo and binds to CtBP in vitro through its conserved 15 amino acid repeats. Failure of this association results in elevated levels of beta-catenin/TCF complexes and of TCF-mediated transcription. Notably, CtBP is neither associated with TCF in vivo nor does mutation of the CtBP binding motifs in TCF-4 alter its transcriptional activity. This questions the idea that CtBP is a direct corepressor of TCF. Our evidence indicates that APC is an adaptor between beta-catenin and CtBP and that CtBP lowers the availability of free nuclear beta-catenin for binding to TCF by sequestering APC/beta-catenin complexes. PMID:15525529

  18. Interaction of synaptic scaffolding molecule and Beta -catenin.

    PubMed

    Nishimura, Wataru; Yao, Ikuko; Iida, Junko; Tanaka, Noriaki; Hata, Yutaka

    2002-02-01

    Synaptic scaffolding molecule (S-SCAM) is a synaptic membrane-associated guanylate kinase with inverted domain organization (MAGI) that interacts with NMDA receptor subunits and neuroligin. In epithelial cells, the non-neuronal isoform of S-SCAM (MAGI-1) is localized at tight or adherens junctions. Recent studies have revealed that the polarized targeting of MAGI-1 to the lateral membrane is mediated by its C-terminal region and that MAGI-1 interacts with beta-catenin in epithelial cells. In this article, we report that S-SCAM interacts with beta-catenin in neurons. beta-Catenin is coimmunoprecipitated with S-SCAM from rat brain. Both S-SCAM and beta-catenin are localized at synapses and are partially colocalized. The C-terminal region of S-SCAM binds to the C-terminal region of beta-catenin. We have tested how the interaction between S-SCAM and beta-catenin plays a role in the synaptic targeting of S-SCAM and beta-catenin. S-SCAM is targeted to synapses via the C-terminal postsynaptic density-95/Dlg-A/ZO-1 (PDZ) domain. beta-Catenin is targeted to synapses with armadillo repeats. The overexpressed C-terminal region of beta-catenin blocks the synaptic targeting of S-SCAM. The overexpressed C-terminal region of S-SCAM is partially targeted to synapses and forms a small number of clusters. In the presence of overexpressed beta-catenin, the C-terminal region of S-SCAM forms more clusters at synapses. These data suggest that the synaptic targeting of S-SCAM is mediated by the interaction with beta-catenin.

  19. beta-catenin-dependent and -independent effects of DeltaN-plakoglobin on epidermal growth and differentiation.

    PubMed

    Teulière, J; Faraldo, M M; Shtutman, M; Birchmeier, W; Huelsken, J; Thiery, J P; Glukhova, M A

    2004-10-01

    Both beta-catenin and plakoglobin can stimulate the expression of Lef/Tcf target genes in vitro. beta-Catenin is known to associate with Lef/Tcf factors and to participate directly in transactivation in vivo, whereas the role of plakoglobin in transcriptional regulation has been less studied. To analyze the functions of plakoglobin in vivo, we generated transgenic mice expressing in the epidermis N-terminally truncated plakoglobin (DeltaN122-PG) lacking the glycogen synthase kinase 3beta phosphorylation sites and therefore protected against degradation (transgenic line K5-DeltaN122-PG). The expression of DeltaN122-PG led to the formation of additional hair germs, hyperplastic hair follicles, and noninvasive hair follicle tumors, a phenotype reminiscent of that induced by expression of N-terminally truncated beta-catenin. However, if expressed in beta-catenin-null epidermis, DeltaN122-PG did not induce new hair follicle germs and follicular tumors. Thus, DeltaN122-PG cannot substitute for beta-catenin in its signaling functions in vivo and the phenotype observed in K5-DeltaN122-PG mouse skin must be due to the aberrant activation of beta-catenin signaling. On the other hand, the expression of DeltaN122-PG in beta-catenin-null skin significantly increased the survival rate of mutant mice, rescued differentiation, and limited excessive proliferation in the interfollicular epidermis, suggesting that plakoglobin may be involved in the intracellular signaling events essential for epidermal differentiation. PMID:15367683

  20. BCR-ABL1-Associated Reduction of Beta Catenin Antagonist Chibby1 in Chronic Myeloid Leukemia

    PubMed Central

    Aluigi, Michela; Luatti, Simona; Castagnetti, Fausto; Testoni, Nicoletta; Soverini, Simona; Santucci, Maria Alessandra; Martinelli, Giovanni

    2013-01-01

    Beta Catenin signaling is critical for the self-renewal of leukemic stem cells in chronic myeloid leukemia. It is driven by multiple events, enhancing beta catenin stability and promoting its transcriptional co-activating function. We investigated the impact of BCR-ABL1 on Chibby1, a beta catenin antagonist involved in cell differentiation and transformation. Relative proximity of the Chibby1 encoding gene (C22orf2) on chromosome 22q12 to the BCR breakpoint (22q11) lets assume its involvement in beta catenin activation in chronic myeloid leukemia as a consequence of deletions of distal BCR sequences encompassing one C22orf2 allele. Forty patients with chronic myeloid leukemia in chronic phase were analyzed for C22orf2 relocation and Chibby1 expression. Fluorescent in situ hybridization analyses established that the entire C22orf2 follows BCR regardless of chromosomes involved in the translocation. In differentiated hematopoietic progenitors (bone marrow mononuclear cell fractions) of 30/40 patients, the expression of Chibby1 protein was reduced below 50% of the reference value (peripheral blood mononuclear cell fractions of healthy persons). In such cell context, Chibby1 protein reduction is not dependent on C22orf2 transcriptional downmodulation; however, it is strictly dependent upon BCR-ABL1 expression because it was not observed at the moment of major molecular response under tyrosine kinase inhibitor therapy. Moreover, it was not correlated with the disease prognosis or response to therapy. Most importantly, a remarkable Chibby1 reduction was apparent in a putative BCR-ABL1+ leukemic stem cell compartment identified by a CD34+ phenotype compared to more differentiated hematopoietic progenitors. In CD34+ cells, Chibby1 reduction arises from transcriptional events and is driven by C22orf2 promoter hypermethylation. These results advance low Chibby1 expression associated with BCR-ABL1 as a component of beta catenin signaling in leukemic stem cells. PMID:24339928

  1. Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling

    SciTech Connect

    Kim, Jae-Sung; Park, Min-Gyeong; Lee, Seul Ah; Park, Sun-Young; Kim, Heung-Joong; Yu, Sun-Kyoung; Kim, Chun Sung; Kim, Su-Gwan; Oh, Ji-Su; You, Jae-Seek; Kim, Jin-Soo; Seo, Yo-Seob; Chun, Hong Sung; Park, Joo-Cheol; Kim, Do Kyung

    2014-04-18

    Highlights: • miR-663 is significantly up-regulated during MDPC-23 odontoblastic cell differentiation. • miR-663 accelerates mineralization in MDPC-23 odontoblastic cells without cell proliferation. • miR-663 promotes odontoblastic cell differentiation by targeting APC and activating Wnt/β-catenin signaling in MDPC-23 cells. - Abstract: MicroRNAs (miRNAs) regulate cell differentiation by inhibiting mRNA translation or by inducing its degradation. However, the role of miRNAs in odontogenic differentiation is largely unknown. In this present study, we observed that the expression of miR-663 increased significantly during differentiation of MDPC-23 cells to odontoblasts. Furthermore, up-regulation of miR-663 expression promoted odontogenic differentiation and accelerated mineralization without proliferation in MDPC-23 cells. In addition, target gene prediction for miR-663 revealed that the mRNA of the adenomatous polyposis coli (APC) gene, which is associated with the Wnt/β-catenin signaling pathway, has a miR-663 binding site in its 3′-untranslated region (3′UTR). Furthermore, APC expressional was suppressed significantly by miR-663, and this down-regulation of APC expression triggered activation of Wnt/β-catenin signaling through accumulation of β-catenin in the nucleus. Taken together, these findings suggest that miR-663 promotes differentiation of MDPC-23 cells to odontoblasts by targeting APC-mediated activation of Wnt/β-catenin signaling. Therefore, miR-663 can be considered a critical regulator of odontoblast differentiation and can be utilized for developing miRNA-based therapeutic agents.

  2. Effects of short-hairpin RNA-inhibited {beta}-catenin expression on the growth of human multiple myeloma cells in vitro and in vivo

    SciTech Connect

    Liang, Wenqing; Yang, Chengwei; Qian, Yu; Fu, Qiang

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer {beta}-Catenin expression were markedly down-regulated by CTNNB1 shRNA. Black-Right-Pointing-Pointer CTNNB1 shRNA could inhibit the proliferation of RPMI8226 cells. Black-Right-Pointing-Pointer Significantly profound apoptotic cell death in CTNNB1 shRNA cells. Black-Right-Pointing-Pointer In vivo, CTNNB1 silence led to a growth inhibition of myeloma growth. Black-Right-Pointing-Pointer c-myc and {beta}-catenin in the expression cells of cleaved caspase-3 were increased. -- Abstract: Multiple myeloma (MM) is thrombogenic as a consequence of multiple hemostatic effects. Overexpression of {beta}-catenin has been observed in several types of malignant tumors, including MM. However, the relationship between {beta}-catenin expression and MM remains unclear. In the present study, RNA interference was used to inhibit {beta}-catenin expression in RPMI8226 cells. RT-PCR and Western blotting analyses showed that {beta}-catenin mRNA and protein expression were markedly down-regulated by CTNNB1 shRNA. Western blotting showed that the protein levels of cyclin D1 and glutamine synthetase were downregulated and supported the transcriptional regulatory function of {beta}-catenin. The MTT assay showed that CTNNB1 shRNA could have significant inhibitory effects on the proliferation of RPMI8226 cells. The TOPflash reporter assay demonstrated significant downregulation after CTNNB1 shRNA transfection in RPMI8226 cells. Flow cytometric analyses also showed significantly profound apoptosis in CTNNB1 shRNA cells. We found CTNNB1 silence led to growth inhibition of MM growth in vivo. Immunohistochemical analyses showed that c-myc and {beta}-catenin were reduced in CTNNB1 shRNA tumor tissues, but that expression of cleaved caspase-3 was increased. These results show that {beta}-catenin could be a new therapeutic agent that targets the biology of MM cells.

  3. CONSORT: Sam68 Is Directly Regulated by MiR-204 and Promotes the Self-Renewal Potential of Breast Cancer Cells by Activating the Wnt/Beta-Catenin Signaling Pathway

    PubMed Central

    Wang, Lan; Tian, Han; Yuan, Jie; Wu, Hongmei; Wu, Jueheng; Zhu, Xun

    2015-01-01

    Abstract Breast cancer stem cells (BCSCs) are considered to be responsible for recurrence in breast cancer. The 68 kDa Src-associated protein in mitosis (Sam68) has been linked to the development and progression of breast cancer; however, the posttranscriptional regulation and role of Sam68 in BCSC self-renewal remain unclear. Sam68 was ectopically overexpressed or knocked down using a siRNA; the self-renewal potential of breast cancer cell lines was assessed using flow cytometry, in vitro mammosphere culture and a xenograft model in NOD/SCID mice. Activation of beta-catenin was assessed by immunohistochemical staining, Western blotting, and luciferase reporter gene assays. The ArrayExpress dataset GSE45666 was used to identify conserved microRNAs downregulated in breast cancer; real-time PCR, Western blotting, luciferase reporter assay, and xenografted tumor model were used to confirm miR-204 regulated Sam68. We found that endogenous Sam68 expression correlated positively with the self-renewal potential of breast cancer cell lines. Overexpression of Sam68 promoted, whereas knockdown reduced, breast cancer cell self-renewal potential in vitro and tumorigenicity in vivo. The Wnt/beta-catenin pathway was identified as a functional mediator of Sam68-induced self-renewal in SKBR-3 and MCF-7 cells. Furthermore, miR-204 was found to be frequently downregulated in human breast cancer and confirmed to directly target Sam68; miR-204 inhibited the self-renewal of breast cancer cell lines by targeting and suppressing Sam68. Our study reveals that Sam68 is regulated by miR-204 and may play an important role in the self-renewal of BCSCs via activating the Wnt/beta-catenin pathway. Sam68 may represent a novel therapeutic target for breast cancer. PMID:26656364

  4. Alzheimer Disease: Crosstalk between the Canonical Wnt/Beta-Catenin Pathway and PPARs Alpha and Gamma

    PubMed Central

    Vallée, Alexandre; Lecarpentier, Yves

    2016-01-01

    The molecular mechanisms underlying the pathophysiology of Alzheimer's disease (AD) are still not fully understood. In AD, Wnt/beta-catenin signaling has been shown to be downregulated while the peroxisome proliferator-activated receptor (PPAR) gamma (mARN and protein) is upregulated. Certain neurodegenerative diseases share the same Wnt/beta-catenin/PPAR gamma profile, such as bipolar disorder and schizophrenia. Conversely, other NDs share an opposite profile, such as amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, multiple sclerosis, and Friedreich's ataxia. AD is characterized by the deposition of extracellular Abeta plaques and the formation of intracellular neurofibrillary tangles in the central nervous system (CNS). Activation of Wnt signaling or inhibition of both glycogen synthase kinase-3beta and Dickkopf 1, two key negative regulators of the canonical Wnt pathway, are able to protect against Abeta neurotoxicity and to ameliorate cognitive performance in AD patients. Although PPAR gamma is upregulated in AD patients, and despite the fact that it has been shown that the PPAR gamma and Wnt/beta catenin pathway systems work in an opposite manner, PPAR gamma agonists diminish learning and memory deficits, decrease Abeta activation of microglia, and prevent hippocampal and cortical neurons from dying. These beneficial effects observed in AD transgenic mice and patients might be partially due to the anti-inflammatory properties of PPAR gamma agonists. Moreover, activation of PPAR alpha upregulates transcription of the alpha-secretase gene and represents a new therapeutic treatment for AD. This review focuses largely on the behavior of two opposing pathways in AD, namely Wnt/beta-catenin signaling and PPAR gamma. It is hoped that this approach may help to develop novel AD therapeutic strategies integrating PPAR alpha signaling. PMID:27807401

  5. WISP-1 is a Wnt-1- and beta-catenin-responsive oncogene.

    PubMed

    Xu, L; Corcoran, R B; Welsh, J W; Pennica, D; Levine, A J

    2000-03-01

    WISP-1 (Wnt-1 induced secreted protein 1) is a member of the CCN family of growth factors. This study identifies WISP-1 as a beta-catenin-regulated gene that can contribute to tumorigenesis. The promoter of WISP-1 was cloned and shown to be activated by both Wnt-1 and beta-catenin expression. TCF/LEF sites played a minor role, whereas the CREB site played an important role in this transcriptional activation. WISP-1 demonstrated oncogenic activities; overexpression of WISP-1 in normal rat kidney fibroblast cells (NRK-49F) induced morphological transformation, accelerated cell growth, and enhanced saturation density. Although these cells did not acquire anchorage-independent growth in soft agar, they readily formed tumors in nude mice, suggesting that appropriate cellular attachment is important for signaling oncogenic events downstream of WISP-1.

  6. {beta}-Catenin stabilization imparts crypt progenitor phenotype to hyperproliferating colonic epithelia

    SciTech Connect

    Sellin, Joseph H.; Wang Yu; Singh, Pomila; Umar, Shahid

    2009-01-01

    Utilizing the Citrobacter rodentium (CR)-induced transmissible murine colonic hyperplasia (TMCH) model, we provide mechanistic basis of changes in {beta}-catenin/APC/CKI{epsilon} leading to progression and/or regression of hyperplasia in vivo. In response to CR-induced TMCH, crypt lengths increased significantly between days 6-27 post-infection, followed by a steep decline by day 34. {beta}-Cat{sup 45}/total {beta}-catenin were elevated on day 1 post-infection, preceding changes in crypt length, and persisted for 27 days before declining by day 34. Importantly, cellular CKI{epsilon} and {beta}-catenin co-immunoprecipitated and exhibited remarkable parallel changes in kinetics during hyperplasia/regression phases. {beta}-catenin, phosphorylated at Ser33,37 and Thr41 ({beta}-cat{sup 33,37/41}), was low till day 12, followed by gradual increase until day 27 before declining by day 34. GSK-3{beta} exhibited significant Ser{sup 9}-phosphorylation/inactivation at days 6-12 with partial recovery at days 27-34. Wild type (wt) APC (p312) levels increased at day 6 with transient proteolysis/truncation to p130 form between days 12 and 15; p312 reappeared by day 19 and returned to baseline by day 34. The kinetics of {beta}-Cat{sup 45}/{beta}-catenin nuclear accumulation and acetylation (Ac-{beta}-Cat{sup Lys49}) from days 6 to 27, followed by loss of phosphorylation/acetylation by day 34 was almost identical; Tcf-4 co-immunoprecipitated with {beta}-Cat{sup 45}/{beta}-catenin and localized immunohistochemically to {beta}-Cat{sup 41/45}-positive regions leading to elevated cyclin D1 expression, during the hyperproliferative, but not regression phases of TMCH. CKI{epsilon} mediated phosphorylation of {beta}-Cat{sup 45}, resulting in stabilization/nuclear translocation of {beta}-Cat{sup 45} may be critical for maintaining proliferation at days 6-27. Reversal of GSK-3{beta} phosphorylation and APC changes may be equally critical during the regression phase from days 27 to 34.

  7. Wnt/beta-catenin pathway activation and myogenic differentiation are induced by cholesterol depletion.

    PubMed

    Mermelstein, Cláudia S; Portilho, Débora M; Mendes, Fábio A; Costa, Manoel L; Abreu, José Garcia

    2007-03-01

    Myogenic differentiation is a multistep process that begins with the commitment of mononucleated precursors that withdraw from cell cycle. These myoblasts elongate while aligning to each other, guided by the recognition between their membranes. This step is followed by cell fusion and the formation of long and striated multinucleated myotubes. We have recently shown that cholesterol depletion by methyl-beta-cyclodextrin (MbetaCD) induces myogenic differentiation by enhancing myoblast recognition and fusion. Here, we further studied the signaling pathways responsible for early steps of myogenesis. As it is known that Wnt plays a role in muscle differentiation, we used the chemical MbetaCD to deplete membrane cholesterol and investigate the involvement of the Wnt/beta-catenin pathway during myogenesis. We show that cholesterol depletion promoted a significant increase in expression of beta-catenin, its nuclear translocation and activation of the Wnt pathway. Moreover, we show that the activation of the Wnt pathway after cholesterol depletion can be inhibited by the soluble protein Frzb-1. Our data suggest that membrane cholesterol is involved in Wnt/beta-catenin signaling in the early steps of myogenic differentiation.

  8. Rad6B is a positive regulator of beta-catenin stabilization.

    PubMed

    Shekhar, Malathy P V; Gerard, Brigitte; Pauley, Robert J; Williams, Bart O; Tait, Larry

    2008-03-15

    Mutations in beta-catenin or other Wnt pathway components that cause beta-catenin accumulation occur rarely in breast cancer. However, there is some evidence of beta-catenin protein accumulation in a subset of breast tumors. We have recently shown that Rad6B, an ubiquitin-conjugating enzyme, is a transcriptional target of beta-catenin/TCF. Here, we show that forced Rad6B overexpression in MCF10A breast cells induces beta-catenin accumulation, which despite being ubiquitinated is stable and transcriptionally active. A similar relationship between Rad6B, beta-catenin ubiquitination, and transcriptional activity was found in WS-15 and MDA-MB-231 breast cancer cells, and mouse mammary tumor virus-Wnt-1 mammary tumor-derived cells, implicating Rad6B in physiologic regulation of beta-catenin stability and activity. Ubiquitinated beta-catenin was detectable in chromatin immunoprecipitations performed with beta-catenin antibody in MDA-MB-231 but not MCF10A cells. Rad6B silencing caused suppression of beta-catenin monoubiquitination and polyubiquitination, and transcriptional activity. These effects were accompanied by a reduction in intracellular beta-catenin but with minimal effects on cell membrane-associated beta-catenin. Measurement of beta-catenin protein stability by cycloheximide treatment showed that Rad6B silencing specifically decreases the stability of high molecular beta-catenin with minimal effect upon the 90-kDa nascent form. In vitro ubiquitination assays confirmed that Rad6B mediates beta-catenin polyubiquitination, and ubiquitin chain extensions involve lysine 63 residues that are insensitive to 26S proteasome. These findings, combined with our previous data that Rad6B is a transcriptional target of beta-catenin, reveal a positive regulatory feedback loop between Rad6B and beta-catenin and a novel mechanism of beta-catenin stabilization/activation in breast cancer cells.

  9. Concurrent Transient Activation of Wnt/{beta}-Catenin Pathway Prevents Radiation Damage to Salivary Glands

    SciTech Connect

    Hai Bo; Yang Zhenhua; Shangguan Lei; Zhao Yanqiu; Boyer, Arthur; Liu, Fei

    2012-05-01

    Purpose: Many head and neck cancer survivors treated with radiotherapy suffer from permanent impairment of their salivary gland function, for which few effective prevention or treatment options are available. This study explored the potential of transient activation of Wnt/{beta}-catenin signaling in preventing radiation damage to salivary glands in a preclinical model. Methods and Materials: Wnt reporter transgenic mice were exposed to 15 Gy single-dose radiation in the head and neck area to evaluate the effects of radiation on Wnt activity in salivary glands. Transient Wnt1 overexpression in basal epithelia was induced in inducible Wnt1 transgenic mice before together with, after, or without local radiation, and then saliva flow rate, histology, apoptosis, proliferation, stem cell activity, and mRNA expression were evaluated. Results: Radiation damage did not significantly affect activity of Wnt/{beta}-catenin pathway as physical damage did. Transient expression of Wnt1 in basal epithelia significantly activated the Wnt/{beta}-catenin pathway in submandibular glands of male mice but not in those of females. Concurrent transient activation of the Wnt pathway prevented chronic salivary gland dysfunction following radiation by suppressing apoptosis and preserving functional salivary stem/progenitor cells. In contrast, Wnt activation 3 days before or after irradiation did not show significant beneficial effects, mainly due to failure to inhibit acute apoptosis after radiation. Excessive Wnt activation before radiation failed to inhibit apoptosis, likely due to extensive induction of mitosis and up-regulation of proapoptosis gene PUMA while that after radiation might miss the critical treatment window. Conclusion: These results suggest that concurrent transient activation of the Wnt/{beta}-catenin pathway could prevent radiation-induced salivary gland dysfunction.

  10. Natural derivatives of curcumin attenuate the Wnt/{beta}-catenin pathway through down-regulation of the transcriptional coactivator p300

    SciTech Connect

    Ryu, Min-Jung; Cho, Munju; Song, Jie-Young; Yun, Yeon-Sook; Choi, Il-Whan; Kim, Dong-Eun; Park, Byeoung-Soo; Oh, Sangtaek

    2008-12-26

    Curcumin, a component of turmeric (Curcuma longa), has been reported to suppress {beta}-catenin response transcription (CRT), which is aberrantly activated in colorectal cancer. However, the effects of its natural analogs (demethoxycurcumin [DMC] and bisdemethoxycurcumin [BDMC]) and metabolite (tetrahydrocurcumin [THC]) on the Wnt/{beta}-catenin pathway have not been investigated. Here, we show that DMC and BDMC suppressed CRT that was activated by Wnt3a conditioned-medium (Wnt3a-CM) without altering the level of intracellular {beta}-catenin, and inhibited the growth of various colon cancer cells, with comparable potency to curcumin. Additionally, DMC and BDMC down-regulated p300, which is a positive regulator of the Wnt/{beta}-catenin pathway. Notably, THC also inhibited CRT and cell proliferation, but to a much lesser degree than curcumin, DMC, or BDMC, indicating that the conjugated bonds in the central seven-carbon chain of curcuminoids are essential for the inhibition of Wnt/{beta}-catenin pathway and the anti-proliferative activity of curcuminoids. Thus, our findings suggest that curcumin derivatives inhibit the Wnt/{beta}-catenin pathway by decreasing the amount of the transcriptional coactivator p300.

  11. Natural derivatives of curcumin attenuate the Wnt/beta-catenin pathway through down-regulation of the transcriptional coactivator p300.

    PubMed

    Ryu, Min-Jung; Cho, Munju; Song, Jie-Young; Yun, Yeon-Sook; Choi, Il-Whan; Kim, Dong-Eun; Park, Byeoung-Soo; Oh, Sangtaek

    2008-12-26

    Curcumin, a component of turmeric (Curcuma longa), has been reported to suppress beta-catenin response transcription (CRT), which is aberrantly activated in colorectal cancer. However, the effects of its natural analogs (demethoxycurcumin [DMC] and bisdemethoxycurcumin [BDMC]) and metabolite (tetrahydrocurcumin [THC]) on the Wnt/beta-catenin pathway have not been investigated. Here, we show that DMC and BDMC suppressed CRT that was activated by Wnt3a conditioned-medium (Wnt3a-CM) without altering the level of intracellular beta-catenin, and inhibited the growth of various colon cancer cells, with comparable potency to curcumin. Additionally, DMC and BDMC down-regulated p300, which is a positive regulator of the Wnt/beta-catenin pathway. Notably, THC also inhibited CRT and cell proliferation, but to a much lesser degree than curcumin, DMC, or BDMC, indicating that the conjugated bonds in the central seven-carbon chain of curcuminoids are essential for the inhibition of Wnt/beta-catenin pathway and the anti-proliferative activity of curcuminoids. Thus, our findings suggest that curcumin derivatives inhibit the Wnt/beta-catenin pathway by decreasing the amount of the transcriptional coactivator p300.

  12. Beta-catenin in schizophrenia: Possibly deleterious novel mutation.

    PubMed

    Levchenko, Anastasia; Davtian, Stepan; Freylichman, Olga; Zagrivnaya, Maria; Kostareva, Anna; Malashichev, Yegor

    2015-08-30

    Schizophrenia is a debilitating psychiatric disorder, affecting approximately 1% of the human population. Mostly genetic factors contribute to schizophrenia, but the genetics are complex and various aspects of brain functioning and structure, from development to synapse plasticity, seem to be involved in the pathogenesis. The goal of the study was to look for novel mutations in genes, implicated in molecular networks, important in schizophrenia. In the study four candidate genes taking part in the WNT signaling pathway were analyzed by sequencing in a cohort of 87 schizophrenia patients from Saint Petersburg, Russia. The gene list included CTNNB1 (beta-catenin), GSK3B, WNT2B and WNT7B. The impact of discovered variants on the protein function was analyzed in silico. We found three variants in the genes CTNNB1 and WNT7B, absent in healthy controls, including 212 controls from the same geographic area. The novel mutation c.1943A>G (p.N648S) in CTNNB1 seems to be the best candidate for disease-associated mutation in this study, as it damages the protein product in silico. This is the first study reporting mutations in CTNNB1 in schizophrenia.

  13. Retinoic acid and Wnt/beta-catenin have complementary roles in anterior/posterior patterning embryos of the basal chordate amphioxus.

    PubMed

    Onai, Takayuki; Lin, Hsiu-Chin; Schubert, Michael; Koop, Demian; Osborne, Peter W; Alvarez, Susana; Alvarez, Rosana; Holland, Nicholas D; Holland, Linda Z

    2009-08-15

    A role for Wnt/beta-catenin signaling in axial patterning has been demonstrated in animals as basal as cnidarians, while roles in axial patterning for retinoic acid (RA) probably evolved in the deuterostomes and may be chordate-specific. In vertebrates, these two pathways interact both directly and indirectly. To investigate the evolutionary origins of interactions between these two pathways, we manipulated Wnt/beta-catenin and RA signaling in the basal chordate amphioxus during the gastrula stage, which is the RA-sensitive period for anterior/posterior (A/P) patterning. The results show that Wnt/beta-catenin and RA signaling have distinctly different roles in patterning the A/P axis of the amphioxus gastrula. Wnt/beta-catenin specifies the identity of the ends of the embryo (high Wnt = posterior; low Wnt = anterior) but not intervening positions. Thus, upregulation of Wnt/beta-catenin signaling induces ectopic expression of posterior markers at the anterior tip of the embryo. In contrast, RA specifies position along the A/P axis, but not the identity of the ends of the embryo-increased RA signaling strongly affects the domains of Hox expression along the A/P axis but has little or no effect on the expression of either anterior or posterior markers. Although the two pathways may both influence such things as specification of neuronal identity, interactions between them in A/P patterning appear to be minimal.

  14. SLIT2 attenuation during lung cancer progression deregulates beta-catenin and E-cadherin and associates with poor prognosis.

    PubMed

    Tseng, Ruo-Chia; Lee, Shih-Hua; Hsu, Han-Shui; Chen, Ben-Han; Tsai, Wan-Ching; Tzao, Ching; Wang, Yi-Ching

    2010-01-15

    Chromosome 4p15.3 is frequently deleted in late-stage lung cancer. We investigated the significance of the SLIT2 gene located in this region to lung cancer progression. SLIT2 encodes an extracellular glycoprotein that can suppress breast cancer by regulating beta-catenin. In this study, we examined alterations in the structure or expression of SLIT2, its receptor ROBO1, and beta-catenin, along with the AKT/glycogen synthase kinase 3beta (GSK3beta)/beta-transducin repeat-containing protein (betaTrCP) pathway in lung cancer cell lines and patients. Low SLIT2 expression correlated with an upward trend of pathological stage and poorer survival in lung cancer patients. Importantly, SLIT2, betaTrCP, and beta-catenin expression levels predicted postoperative recurrence of lung cancer in patients. Stimulating SLIT2 expression by various methods increased the level of E-cadherin caused by attenuation of its transcriptional repressor SNAI1. Conversely, knocking down SLIT2 expression increased cell migration and reduced cell adhesion through coordinated deregulation of beta-catenin and E-cadherin/SNAI1 in the AKT/GSK3beta/betaTrCP pathway. Our findings indicate that SLIT2 suppresses lung cancer progression, defining it as a novel "theranostic" factor with potential as a therapeutic target and prognostic predictor in lung cancer. Cancer Res; 70(2); 543-51.

  15. Proteomic analysis of beta-catenin activation in mouse liver by DIGE analysis identifies glucose metabolism as a new target of the Wnt pathway.

    PubMed

    Chafey, Philippe; Finzi, Laetitia; Boisgard, Raphael; Caüzac, Michèle; Clary, Guillem; Broussard, Cédric; Pégorier, Jean-Paul; Guillonneau, François; Mayeux, Patrick; Camoin, Luc; Tavitian, Bertrand; Colnot, Sabine; Perret, Christine

    2009-08-01

    The Wnt/beta-catenin signaling pathway has been increasingly implicated in liver development and physiology. Aberrant activation of this pathway is one of the major genetic events observed during the process of human HCC development. To gain insight into the mechanism underlying beta-catenin action in the liver, we conducted a quantitative differential proteomic analysis using 2-D DIGE combined with MS, in mice with liver-specific deletion of Apc resulting in acute activation of beta-catenin signaling (Apc(KOliv) mice). We identified 94 protein spots showing differential expression between mutant Apc(KOliv) and control mice, corresponding to 56 individual proteins. Most of the proteins identified were associated with metabolic pathways, such as ammonia and glucose metabolism. Our analysis showed an increase in lactate dehydrogenase activity together with a downregulation of two mitochondrial ATPase subunits (ATP5a1 and ATP5b). These observations indicate that beta-catenin signaling may induce a shift in the glucose metabolism from oxidative phosphorylation to glycolysis, known as the "Warburg effect". Imaging with (18)F-fluoro-2-deoxy-D-glucose-positron emission tomography suggests that the specific metabolic reprogramming induced by beta-catenin in the liver does not imply the first step of glycolysis. This observation may explain why some HCCs are difficult to assess by fluoro-2-deoxy-D-glucose-positron emission tomography imaging.

  16. Resveratrol augments the canonical Wnt signaling pathway in promoting osteoblastic differentiation of multipotent mesenchymal cells

    SciTech Connect

    Zhou, Haibin; Shang, Linshan; Li, Xi; Zhang, Xiyu; Gao, Guimin; Guo, Chenhong; Chen, Bingxi; Liu, Qiji; Gong, Yaoqin; Shao, Changshun

    2009-10-15

    Resveratrol has been shown to possess many health-benefiting effects, including the promotion of bone formation. In this report we investigated the mechanism by which resveratrol promotes osteoblastic differentiation from pluripotent mesenchymal cells. Since Wnt signaling is well documented to induce osteoblastogenesis and bone formation, we characterized the factors involved in Wnt signaling in response to resveratrol treatment. Resveratrol treatment of mesenchymal cells led to an increase in stabilization and nuclear accumulation of {beta}-catenin dose-dependently and time-dependently. As a consequence of the increased nuclear accumulation of {beta}-catenin, the ability to activate transcription of {beta}-catenin-TCF/LEF target genes that are required for osteoblastic differentiation was upregulated. However, resveratrol did not affect the initial step of the Wnt signaling pathway, as resveratrol was as effective in upregulating the activity of {beta}-catenin in cells in which Lrp5 was knocked down as in control cells. In addition, while conditioned medium enriched in Wnt signaling antagonist Dkk1 was able to inhibit Wnt3a-induced {beta}-catenin upregulation, this inhibitory effect can be abolished in resveratrol-treated cells. Furthermore, we showed that the level of glycogen synthase kinase 3{beta} (GSK-3{beta}), which phosphorylates and destabilizes {beta}-catenin, was reduced in response to resveratrol treatment. The phosphorylation of GSK-3{beta} requires extracellular signal-regulated kinase (ERK)1/2. Together, our data indicate that resveratrol promotes osteoblastogenesis and bone formation by augmenting Wnt signaling.

  17. MicroRNA-320a suppresses human colon cancer cell proliferation by directly targeting {beta}-catenin

    SciTech Connect

    Sun, Jian-Yong; Huang, Yi; Li, Ji-Peng; Zhang, Xiang; Wang, Lei; Meng, Yan-Ling; Yan, Bo; Bian, Yong-Qian; Zhao, Jing; Wang, Wei-Zhong; and others

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer miR-320a is downregulated in human colorectal carcinoma. Black-Right-Pointing-Pointer Overexpression of miR-320a inhibits colon cancer cell proliferation. Black-Right-Pointing-Pointer {beta}-Catenin is a direct target of miR-320a in colon cancer cells. Black-Right-Pointing-Pointer miR-320a expression inversely correlates with mRNA expression of {beta}-catenin's target genes in human colon carcinoma. -- Abstract: Recent profile studies of microRNA (miRNA) expression have documented a deregulation of miRNA (miR-320a) in human colorectal carcinoma. However, its expression pattern and underlying mechanisms in the development and progression of colorectal carcinoma has not been elucidated clearly. Here, we performed real-time PCR to examine the expression levels of miR-320a in colon cancer cell lines and tumor tissues. And then, we investigated its biological functions in colon cancer cells by a gain of functional strategy. Further more, by the combinational approaches of bioinformatics and experimental validation, we confirmed target associations of miR-320a in colorectal carcinoma. Our results showed that miR-320a was frequently downregulated in cancer cell lines and colon cancer tissues. And we demonstrated that miR-320a restoration inhibited colon cancer cell proliferation and {beta}-catenin, a functionally oncogenic molecule was a direct target gene of miR-320a. Finally, the data of real-time PCR showed the reciprocal relationship between miR-320a and {beta}-catenin's downstream genes in colon cancer tissues. These findings indicate that miR-320a suppresses the growth of colon cancer cells by directly targeting {beta}-catenin, suggesting its application in prognosis prediction and cancer treatment.

  18. CD133 expression correlates with membrane beta-catenin and E-cadherin loss from human hair follicle placodes during morphogenesis.

    PubMed

    Gay, Denise L; Yang, Chao-Chun; Plikus, Maksim V; Ito, Mayumi; Rivera, Charlotte; Treffeisen, Elsa; Doherty, Laura; Spata, Michelle; Millar, Sarah E; Cotsarelis, George

    2015-01-01

    Genetic studies suggest that the major events of human hair follicle development are similar to those in mice, but detailed analyses of this process are lacking. In mice, hair follicle placode "budding" is initiated by invagination of Wnt-induced epithelium into the underlying mesenchyme. Modification of adherens junctions (AJs) is clearly required for budding. Snail-mediated downregulation of AJ component E-cadherin is important for placode budding in mice. Beta-catenin, another AJ component, has been more difficult to study owing to its essential functions in Wnt signaling, a prerequisite for hair follicle placode induction. Here, we show that a subset of human invaginating hair placode cells expresses the stem cell marker CD133 during early morphogenesis. CD133 associates with membrane beta-catenin in early placodes, and its continued expression correlates with loss of beta-catenin and E-cadherin from the cell membrane at a time when E-cadherin transcriptional repressors Snail and Slug are not implicated. Stabilization of CD133 via anti-CD133 antibody treatment of human fetal scalp explants depresses beta-catenin and E-cadherin membrane localization. We discuss this unique correlation and suggest a hypothetical model whereby CD133 promotes morphogenesis in early hair follicle placodes through the localized removal of membrane beta-catenin proteins and subsequent AJ dissolution.

  19. CD133 expression correlates with membrane beta-catenin and e-cadherin loss from human hair follicle placodes during morphogenesis

    PubMed Central

    Gay, Denise; Yang, Chao-Chun; Plikus, Maksim; Ito, Mayumi; Rivera, Charlotte; Treffeisen, Elsa; Doherty, Laura; Spata, Michelle; Millar, Sarah E.; Cotsarelis, George

    2014-01-01

    Genetic studies suggest that the major events of human hair follicle development are similar to those in mice, but detailed analyses of this process are lacking. In mice, hair follicle placode ‘budding’ is initiated by invagination of Wnt-induced epithelium into the underlying mesenchyme. Modification of adherens junctions is clearly required for budding. Snail-mediated downregulation of adherens junction component E-cadherin is important for placode budding in mice. Beta-catenin, another adherens junction component, has been more difficult to study due to its essential functions in Wnt signaling, a prerequisite for hair follicle placode induction. Here, we show that a subset of human invaginating hair placode cells expresses the stem cell marker CD133 during early morphogenesis. CD133 associates with membrane beta-catenin in early placodes and its continued expression correlates with loss of beta-catenin and E-cadherin from the cell membrane at a time when E-cadherin transcriptional repressors Snail and Slug are not implicated. Stabilization of CD133 via anti-CD133 antibody treatment of human fetal scalp explants depresses beta-catenin and E-cadherin membrane localization. We discuss this unique correlation and suggest a hypothetical model whereby CD133 promotes morphogenesis in early hair follicle placodes through the localized removal of membrane beta-catenin proteins and subsequent adherens junction dissolution. PMID:25010141

  20. Overexpression of EB1 in human esophageal squamous cell carcinoma (ESCC) may promote cellular growth by activating beta-catenin/TCF pathway.

    PubMed

    Wang, Yihua; Zhou, Xiaobo; Zhu, Hongxia; Liu, Shuang; Zhou, Cuiqi; Zhang, Guo; Xue, Liyan; Lu, Ning; Quan, Lanping; Bai, Jinfeng; Zhan, Qimin; Xu, Ningzhi

    2005-10-01

    Esophageal squamous cell carcinoma (ESCC) has a multifactorial etiology involving environmental and/or genetic factors. End-binding protein 1 (EB1), which was cloned as an interacting partner of the adenomatous polyposis coli (APC) tumor suppressor protein, was previously found overexpressed in ESCC. However, the precise role of EB1 in the development of this malignancy has not yet been elucidated. In this study, we analysed freshly resected ESCC specimens and demonstrated that EB1 was overexpressed in approximately 63% of tumor samples compared to matched normal tissue. We report that overexpression of EB1 in the ESCC line EC9706 significantly promotes cell growth, whereas suppression of EB1 protein level by RNA interference significantly inhibited growth of esophageal tumor cells. In addition, EB1 overexpression induced nuclear accumulation of beta-catenin and promoted the transcriptional activity of beta-catenin/T-cell factor (TCF). These effects were partially or completely abolished by coexpression of APC or DeltaN TCF4, respectively. Also, we found that EB1 affected the interaction between beta-catenin and APC. Furthermore, EB1 overexpression was correlated with cytoplasmic/nuclear accumulation of beta-catenin in primary human ESCC. Taken together, these results support the novel hypothesis that EB1 overexpression may play a role in the development of ESCC by affecting APC function and activating the beta-catenin/TCF pathway.

  1. Molecular mechanisms of hormone-mediated Müllerian duct regression: involvement of beta-catenin.

    PubMed

    Allard, S; Adin, P; Gouédard, L; di Clemente, N; Josso, N; Orgebin-Crist, M C; Picard, J Y; Xavier, F

    2000-08-01

    and cell fate during Müllerian duct regression. To our knowledge, this is the first report that beta-catenin, known for its role in Wnt signaling, may mediate anti-Müllerian hormone action.

  2. Brain Metastases from Lung Cancer Show Increased Expression of DVL1, DVL3 and Beta-Catenin and Down-Regulation of E-Cadherin

    PubMed Central

    Kafka, Anja; Tomas, Davor; Beroš, Vili; Pećina, Hrvoje Ivan; Zeljko, Martina; Pećina-Šlaus, Nives

    2014-01-01

    The susceptibility of brain to secondary formation from lung cancer primaries is a well-known phenomenon. In contrast, the molecular basis for invasion and metastasis to the brain is largely unknown. In the present study, 31 brain metastases that originated from primary lung carcinomas were analyzed regarding over expression of Dishevelled-1 (DVL1), Dishevelled-3 (DVL3), E-cadherin (CDH1) and beta-catenin (CTNNB1). Protein expressions and localizations were analyzed by immunohistochemistry. Genetic alterations of E-cadherin were tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH). Heteroduplex was used to investigate mutations in beta-catenin. DVL1 and DVL3 showed over expression in brain metastasis in 87.1% and 90.3% of samples respectively. Nuclear staining was observed in 54.8% of cases for DVL1 and 53.3% for DVL3. The main effector of the Wnt signaling, beta-catenin, was up-regulated in 56%, and transferred to the nucleus in 36% of metastases. When DVL1 and DVL3 were up-regulated the number of cases with nuclear beta-catenin significantly increased (p = 0.0001). Down-regulation of E-cadherin was observed in 80% of samples. Genetic analysis showed 36% of samples with LOH of the CDH1. In comparison to other lung cancer pathologies, the diagnoses adenocarcinoma and small cell lung cancer (SCLC) were significantly associated to CDH1 LOH (p = 0.001). Microsatellite instability was detected in one metastasis from adenocarcinoma. Exon 3 of beta-catenin was not targeted. Altered expression of Dishevelled-1, Dishevelled-3, E-cadherin and beta-catenin were present in brain metastases which indicates that Wnt signaling is important and may contribute to better understanding of genetic profile conditioning lung cancer metastasis to the brain. PMID:24933634

  3. Brain metastases from lung cancer show increased expression of DVL1, DVL3 and beta-catenin and down-regulation of E-cadherin.

    PubMed

    Kafka, Anja; Tomas, Davor; Beroš, Vili; Pećina, Hrvoje Ivan; Zeljko, Martina; Pećina-Šlaus, Nives

    2014-06-13

    The susceptibility of brain to secondary formation from lung cancer primaries is a well-known phenomenon. In contrast, the molecular basis for invasion and metastasis to the brain is largely unknown. In the present study, 31 brain metastases that originated from primary lung carcinomas were analyzed regarding over expression of Dishevelled-1 (DVL1), Dishevelled-3 (DVL3), E-cadherin (CDH1) and beta-catenin (CTNNB1). Protein expressions and localizations were analyzed by immunohistochemistry. Genetic alterations of E-cadherin were tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH). Heteroduplex was used to investigate mutations in beta-catenin. DVL1 and DVL3 showed over expression in brain metastasis in 87.1% and 90.3% of samples respectively. Nuclear staining was observed in 54.8% of cases for DVL1 and 53.3% for DVL3. The main effector of the Wnt signaling, beta-catenin, was up-regulated in 56%, and transferred to the nucleus in 36% of metastases. When DVL1 and DVL3 were up-regulated the number of cases with nuclear beta-catenin significantly increased (p=0.0001). Down-regulation of E-cadherin was observed in 80% of samples. Genetic analysis showed 36% of samples with LOH of the CDH1. In comparison to other lung cancer pathologies, the diagnoses adenocarcinoma and small cell lung cancer (SCLC) were significantly associated to CDH1 LOH (p=0.001). Microsatellite instability was detected in one metastasis from adenocarcinoma. Exon 3 of beta-catenin was not targeted. Altered expression of Dishevelled-1, Dishevelled-3, E-cadherin and beta-catenin were present in brain metastases which indicates that Wnt signaling is important and may contribute to better understanding of genetic profile conditioning lung cancer metastasis to the brain.

  4. Reactive oxygen species mediate arsenic induced cell transformation and tumorigenesis through Wnt/{beta}-catenin pathway in human colorectal adenocarcinoma DLD1 cells

    SciTech Connect

    Zhang Zhuo; Wang Xin; Cheng Senping; Sun Lijuan; Son, Young-Ok; Yao Hua; Li Wenqi; Budhraja, Amit; Li Li; Shelton, Brent J.; Tucker, Thomas; Arnold, Susanne M.; Shi Xianglin

    2011-10-15

    Long term exposure to arsenic can increase incidence of human cancers, such as skin, lung, and colon rectum. The mechanism of arsenic induced carcinogenesis is still unclear. It is generally believed that reactive oxygen species (ROS) may play an important role in this process. In the present study, we investigate the possible linkage between ROS, {beta}-catenin and arsenic induced transformation and tumorigenesis in human colorectal adenocarcinoma cell line, DLD1 cells. Our results show that arsenic was able to activate p47{sup phox} and p67{sup phox}, two key proteins for activation of NADPH oxidase. Arsenic was also able to generate ROS in DLD1 cells. Arsenic increased {beta}-catenin expression level and its promoter activity. ROS played a major role in arsenic-induced {beta}-catenin activation. Treatment of DLD1 cells by arsenic enhanced both transformation and tumorigenesis of these cells. The tumor volumes of arsenic treated group were much larger than those without arsenic treatment. Addition of either superoxide dismutase (SOD) or catalase reduced arsenic induced cell transformation and tumor formation. The results indicate that ROS are involved in arsenic induced cell transformation and tumor formation possible through Wnt/{beta}-catenin pathway in human colorectal adenocarcinoma cell line DLD1 cells. - Highlights: > Arsenic activates NADPH oxidase and increases reactive oxygen species generation in DLD1 cells. > Arsenic increases {beta}-catenin expression. > Inhibition of ROS induced by arsenic reduce {beta}-catenin expression. > Arsenic increases cell transformation in DLD1 cells and tumorigenesis in nude mice. > Blockage of ROS decrease cell transformation and tumorigenesis induced by arsenic.

  5. The protein tyrosine phosphatase Pez is a major phosphatase of adherens junctions and dephosphorylates beta-catenin.

    PubMed

    Wadham, Carol; Gamble, Jennifer R; Vadas, Mathew A; Khew-Goodall, Yeesim

    2003-06-01

    Cell-cell adhesion regulates processes important in embryonal development, normal physiology, and cancer progression. It is regulated by various mechanisms including tyrosine phosphorylation. We have previously shown that the protein tyrosine phosphatase Pez is concentrated at intercellular junctions in confluent, quiescent monolayers but is nuclear in cells lacking cell-cell contacts. We show here with an epithelial cell model that Pez localizes to the adherens junctions in confluent monolayers. A truncation mutant lacking the catalytic domain acts as a dominant negative mutant to upregulate tyrosine phosphorylation at adherens junctions. We identified beta-catenin, a component of adherens junctions, as a substrate of Pez by a "substrate trapping" approach and by in vitro dephosphorylation with recombinant Pez. Consistent with this, ectopic expression of the dominant negative mutant caused an increase in tyrosine phosphorylation of beta-catenin, demonstrating that Pez regulates the level of tyrosine phosphorylation of adherens junction proteins, including beta-catenin. Increased tyrosine phosphorylation of adherens junction proteins has been shown to decrease cell-cell adhesion, promoting cell migration as a result. Accordingly, the dominant negative Pez mutant enhanced cell motility in an in vitro "wound" assay. This suggests that Pez is also a regulator of cell motility, most likely through its action on cell-cell adhesion. PMID:12808048

  6. Transactivation of vimentin by beta-catenin in human breast cancer cells.

    PubMed

    Gilles, Christine; Polette, Myriam; Mestdagt, Mélanie; Nawrocki-Raby, Béatrice; Ruggeri, Philippe; Birembaut, Philippe; Foidart, Jean-Michel

    2003-05-15

    The cytoplasmic and nuclear redistribution of beta-catenin and the de novo expression of vimentin are frequently involved in the epithelial-to-mesenchymal transition associated with increased invasive/migratory properties of epithelial cells. Because beta-catenin can act as a coactivator of transcription through its binding to the T-cell factor (TCF)/lymphoid enhancer factor 1 transcription factor family, we have explored the possibility that beta-catenin/TCF could directly transactivate vimentin. We first compared vimentin expression in relation with the localization of beta-catenin in eight breast cancer cell lines displaying various degrees of invasiveness and in a model of cell migration using human mammary MCF10A cells. We could thus show a cytoplasmic and/or nuclear distribution of beta-catenin in invasive/migratory cells expressing vimentin, but not in noninvasive/stationary vimentin-negative cell lines. In addition, the human vimentin promoter was found to be up-regulated by beta-catenin and TCF-4 cotransfection. Varying with the cellular background, a diminution of this up-regulation was observed when the putative beta-catenin/TCF binding site of the vimentin promoter was mutated. Our results therefore demonstrate that the vimentin promoter is a target of the beta-catenin/TCF pathway and strongly suggest an implication of this regulation in epithelial cell migration/invasion.

  7. The Wnt/beta-catenin pathway is activated during advanced arterial aging in humans.

    PubMed

    Marchand, Alexandre; Atassi, Fabrice; Gaaya, Amira; Leprince, Pascal; Le Feuvre, Claude; Soubrier, Florent; Lompré, Anne-Marie; Nadaud, Sophie

    2011-04-01

    Aging is the main risk factor for cardiovascular diseases, but the associated molecular mechanisms are poorly understood. The Wnt signaling pathway was shown to be induced during aging in muscle and in the skin, but the regulation and role of Wnt signaling in the aged vessel have not yet been addressed. While screening for age-related changes in gene expression in the intima/media of human mammary arteries, we observed that the expression of frizzled 4 (Fzd4), a Wnt receptor, and of several targets of the Wnt/β-catenin/TCF signaling pathway [Wnt-inducible secreted protein 1 (WISP1), versican, osteopontin (SPP1), insulin-like growth factor binding protein 2 (IGFBP-2), and p21] were modified with age, suggesting an activation of the Wnt/β-catenin pathway. In contrast, we did not observe any regulation of forkhead transcription factor (FoxO) target genes. Beta-catenin-activating phosphorylation at position Ser675 was increased in aging mammary arteries, confirming the activation of this pathway. We confirmed in vitro that Wnt3a or Wnt1 treatment of human vascular smooth muscle cells (VSMCs) induced β-catenin phosphorylation at Ser675 and WISP1, SPP1, and IGFBP-2 expression. In vitro, Wnt treatment induced proliferation and cyclin D1 expression in VSMC from young (6 weeks old) rats but not in cells from older rats (8 months old), even though low-density lipoprotein receptor-related protein 6 and β-catenin phosphorylation, and β-catenin nuclear translocation demonstrated β-catenin activation in both cell types. Beta-catenin silencing demonstrated that Wnt induction of cyclin D1 expression is β-catenin dependent. Altogether, our data show that the Wnt/β-catenin/TCF pathway is activated in aging human mammary artery cells, but fails to induce the proliferation of aging vascular cells. PMID:21108734

  8. Genomic organization of the human {beta}-catenin gene (CTNNB1)

    SciTech Connect

    Nollet, F.; Berx, G.; Molemans, F.; Roy, F. van

    1996-03-05

    The cytoplasmic {beta}-catenin protein is implicated in signal transduction and associates with both the cell-cell adhesion protein E-cadherin and the tumor suppressor gene product APC. We determined the primary structure of the human {beta}-catenin gene (CTNNB1) by analysis cDNA and genomic clones. The size of the complete gene was determined to be 23.2 kb. Restriction mapping and partial sequence analysis revealed 16 exons. All splice donor and acceptor sites were conformable to the GT/AG rule. The exon size ranged from 61 to 790 bp. Half of the introns were smaller than 550 bp, with the smallest being 84 pb and the longest being 6700 bp. The intron-exon boundaries did not coincide either with conserved sites in the 12 armadillo repeat sequences of {beta}-catenin or with intron-exon boundaries in the armadillo gene of Drosophila. A major site for transcription initiation was identified as an A residue 214 nucleotides upstream of the ATG initiation codon. The resulting transcript is 3362 nucleotides long. Compared to the previously published mRNA sequence, additional residues were identified, 16 at the 5{prime} end and 766 at the 3{prime} end of the mRNA. An alternative splice acceptor site within exon 16 reduced the 3{prime} UTR sequence by 159 bp. Polymerase chain reaction on cDNA from 14 human cell lines demonstrated the general occurrence of both splice variants. The 5{prime}-flanking region is highly GC-rich and lacks a CCAAT box, but contains a TATA box and potential binding sites for several transcription factors, such as NFkB, SP1, AP2, and EGR1. Both a 437-bp fragment and a 6-kb fragment, containing about 4.7 kb of the 5{prime}-flanking region in addition to the noncoding exon 1 and 1 kb of intron 1, showed clear promoter activity when these fragments were linked to a secreted alkaline phosphatase reporter gene and transfected into a mouse epithelial cell line. 53 refs., 5 figs., 2 tabs.

  9. Sequencing of the rat beta-catenin gene (Ctnnb1) and mutational analysis of liver tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline.

    PubMed

    Li, Qingjie; Dixon, Brian M; Al-Fageeh, Mohamed; Blum, Carmen A; Dashwood, Roderick H

    2002-01-23

    beta-Catenin, a protein that functions in cadherin-mediated cell-cell adhesion as well as in signal transduction, has received increasing attention in recent years due to its role as an oncogene in various human cancers. The primary sequence of the human beta-catenin gene (CTNNB1) has been known for some time, but that of the rat beta-catenin gene (Ctnnb1) has not heretofore been studied in detail. We report here the primary structure of Ctnnb1 using PCR-based methods and direct sequencing. The size of the complete Ctnnb1 gene was determined to be 9082 bp. We found the rat Ctnnb1 gene to contain 14 exons, ranging in size from 61 to 356 bp, and 13 introns ranging in size from 76 to 2524 bp. The transcription start site appears to be 157 bp upstream of the ATG codon located in exon 1. The resulting transcript is 2650 nucleotides long (encoding a protein of 781 amino acids). We found the 5' UTR to consist of 157 nucleotides and the 3' UTR to be 147 nucleotides long. The region coding for the glycogen synthase kinase-3beta domain of beta-catenin is located in exon 2 of rat Ctnnb1, in contrast to human CTNNB1 in which it is found in exon 3. Based on the newly acquired knowledge of the primary sequence, more than a dozen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced rat liver tumors were screened for the presence or absence of mutations in all 14 exons of rat Ctnnb1. Surprisingly, no mutations were found. The results are discussed in the context of the organ-specificity of IQ-induced mutations in beta-catenin, being highly prevalent in colon tumors, but much less common in liver tumors.

  10. beta-catenin is strongly elevated in rat colonic epithelium following short-term intermittent treatment with 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and a high-fat diet.

    PubMed

    Wang, Rong; Dashwood, W Mohaiza; Löhr, Christiane V; Fischer, Kay A; Nakagama, Hitoshi; Williams, David E; Dashwood, Roderick H

    2008-09-01

    Colon tumors expressing high levels of beta-catenin and c-myc have been reported in male F344 rats given three short cycles of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) alternating with a high-fat (HF) diet. Using the same experimental protocol, rats were euthanized 24 h after the last dose of PhIP so as to examine early changes in colonic crypt homeostasis and beta-catenin expression, before the onset of frank tumors. PhIP/HF dosing caused a significant increase in the bromodeoxyuridine labeling index throughout the entire colon, and within the colonic crypt column cleaved caspase-3 was elevated in the basal and central zones, but reduced in the luminal region. In vehicle/HF controls, beta-catenin was immunolocalized primarily at the border between cells at the top of the crypt, whereas in rats given PhIP/HF diet there was strong cytoplasmic staining, which appeared as a gradient of increased beta-catenin extending from the base of the crypt column to the luminal region. Quantitative real-time PCR and immunoblot analyses confirmed that beta-catenin and c-myc were increased significantly in the colonic mucosa of rats given PhIP/HF diet. Collectively, these findings suggest that PhIP/HF cycling alters beta-catenin and c-myc expression in the colonic mucosa, resulting in expansion of the proliferative zone and redistribution of apoptotic cells from the lumen to the central and basal regions of the colonic crypt. Thus, during the early stages of colon carcinogenesis, alternating exposure to heterocyclic amines and a high-fat diet might facilitate molecular changes resulting in dysregulated beta-catenin and c-myc expression.

  11. Bioinformatics Knowledge Map for Analysis of Beta-Catenin Function in Cancer

    PubMed Central

    Arighi, Cecilia N.; Wu, Cathy H.

    2015-01-01

    Given the wealth of bioinformatics resources and the growing complexity of biological information, it is valuable to integrate data from disparate sources to gain insight into the role of genes/proteins in health and disease. We have developed a bioinformatics framework that combines literature mining with information from biomedical ontologies and curated databases to create knowledge “maps” of genes/proteins of interest. We applied this approach to the study of beta-catenin, a cell adhesion molecule and transcriptional regulator implicated in cancer. The knowledge map includes post-translational modifications (PTMs), protein-protein interactions, disease-associated mutations, and transcription factors co-activated by beta-catenin and their targets and captures the major processes in which beta-catenin is known to participate. Using the map, we generated testable hypotheses about beta-catenin biology in normal and cancer cells. By focusing on proteins participating in multiple relation types, we identified proteins that may participate in feedback loops regulating beta-catenin transcriptional activity. By combining multiple network relations with PTM proteoform-specific functional information, we proposed a mechanism to explain the observation that the cyclin dependent kinase CDK5 positively regulates beta-catenin co-activator activity. Finally, by overlaying cancer-associated mutation data with sequence features, we observed mutation patterns in several beta-catenin PTM sites and PTM enzyme binding sites that varied by tissue type, suggesting multiple mechanisms by which beta-catenin mutations can contribute to cancer. The approach described, which captures rich information for molecular species from genes and proteins to PTM proteoforms, is extensible to other proteins and their involvement in disease. PMID:26509276

  12. Bioinformatics Knowledge Map for Analysis of Beta-Catenin Function in Cancer.

    PubMed

    Çelen, İrem; Ross, Karen E; Arighi, Cecilia N; Wu, Cathy H

    2015-01-01

    Given the wealth of bioinformatics resources and the growing complexity of biological information, it is valuable to integrate data from disparate sources to gain insight into the role of genes/proteins in health and disease. We have developed a bioinformatics framework that combines literature mining with information from biomedical ontologies and curated databases to create knowledge "maps" of genes/proteins of interest. We applied this approach to the study of beta-catenin, a cell adhesion molecule and transcriptional regulator implicated in cancer. The knowledge map includes post-translational modifications (PTMs), protein-protein interactions, disease-associated mutations, and transcription factors co-activated by beta-catenin and their targets and captures the major processes in which beta-catenin is known to participate. Using the map, we generated testable hypotheses about beta-catenin biology in normal and cancer cells. By focusing on proteins participating in multiple relation types, we identified proteins that may participate in feedback loops regulating beta-catenin transcriptional activity. By combining multiple network relations with PTM proteoform-specific functional information, we proposed a mechanism to explain the observation that the cyclin dependent kinase CDK5 positively regulates beta-catenin co-activator activity. Finally, by overlaying cancer-associated mutation data with sequence features, we observed mutation patterns in several beta-catenin PTM sites and PTM enzyme binding sites that varied by tissue type, suggesting multiple mechanisms by which beta-catenin mutations can contribute to cancer. The approach described, which captures rich information for molecular species from genes and proteins to PTM proteoforms, is extensible to other proteins and their involvement in disease. PMID:26509276

  13. Tyrosine residues 654 and 670 in {beta}-cat enin are crucial in regulation of Met-{beta}-catenin interactions

    SciTech Connect

    Zeng, Gang; Apte, Udayan; Micsenyi, Amanda; Bell, Aaron; Monga, Satdarshan P.S. . E-mail: smonga@pitt.edu

    2006-11-01

    {beta}-catenin, a key component of the canonical Wnt pathway, is also regulated by tyrosine phosphorylation that regulates its association to E-cadherin. Previously, we reported its association with the hepatocyte growth factor (HGF) receptor Met at the membrane. HGF induced Met-{beta}-catenin dissociation and nuclear translocation of {beta}-catenin, which was tyrosine-phosphorylation-dependent. Here, we further investigate the Met-{beta}-catenin interaction by selectively mutating several tyrosine residues, alone or in combination, in {beta}-catenin. The mutants were subcloned into FLAG-CMV vector and stably transfected into rat hepatoma cells, which were treated with HGF. All single or double-mutant-transfected cells continued to show HGF-induced nuclear translocation of FLAG-{beta}-catenin except the mutations affecting 654 and 670 simultaneously (Y654/670F), which coincided with the lack of formation of {beta}-catenin-TCF complex and DNA synthesis, in response to the HGF treatment. In addition, the Y654/670F-transfected cells also showed no phosphorylation of {beta}-catenin or dissociation from Met in response to HGF. Thus, intact 654 and 670 tyrosine residues in {beta}-catenin are crucial in HGF-mediated {beta}-catenin translocation, activation and mitogenesis.

  14. Expression of e-cadherin, alpha-catenins and Beta-catenins in human gastric carcinomas - correlation with histology and tumor progression.

    PubMed

    Yasui, W; Kuniyasu, H; Akama, Y; Kitahara, K; Nagafuchi, A; Ishihara, S; Tsukita, S; Tahara, E

    1995-01-01

    The expression of cell-cell adhesion molecule, E-cadherin and its associated proteins, alpha- and beta-catenins in human gastric carcinomas was examined by Western blotting. All the seven gastric carcinoma cell lines expressed E-cadherin except KATOIII, which was derived from pleural effusion of a scirrhous type stomach cancer or Borrmann's type-4 carcinoma. The expression of alpha-catenin was not detected in HSC43 derived from scirrhous carcinoma, while HSC39 expressed abnormal beta-catenin caused by genetic alteration. In gastric carcinoma cases, the levels of E-cadherin and alpha-catenin were significantly lower in poorly differentiated adenocarcinomas and scirrhous carcinomas when compared to other types of gastric carcinomas. Deeply invasive carcinomas expressed E-cadherin and alpha-catenin at lower levels. However, the expression level of alpha-catenin was not necessarily consistent with that of E-cadherin. One of 10 gastric carcinomas examined showed complete deletion of alpha-catenin gene in Southern blotting. beta-catenin was expressed at lower level in poorly differentiated adenocarcinomas than in well-differentiated adenocarcinomas. These findings suggest that reduction in the expression of E-cadherin and its associated molecules, catenins, is involved in the development and infiltrative growth of scirrhous type gastric carcinomas. PMID:21597700

  15. Polymeric black tea polyphenols inhibit 1,2-dimethylhydrazine induced colorectal carcinogenesis by inhibiting cell proliferation via Wnt/{beta}-catenin pathway

    SciTech Connect

    Patel, Rachana; Ingle, Arvind; Maru, Girish B.

    2008-02-15

    Tea polyphenols like epigallocatechin gallate and theaflavins are established chemopreventive agents for colorectal carcinogenesis. However, studies on evaluating similar chemopreventive properties of thearubigins or polymeric black tea polyphenols (PBPs), the most abundant polyphenols in black tea, are limited. Hence, in the present study we aim to investigate chemopreventive effects along with probable mechanisms of action of PBP extract employing 1,2-dimethylhydrazine (DMH)-induced colorectal carcinogenesis in Sprague-Dawley rats as experimental model. The present study suggests that PBPs, like other tea polyphenols, also inhibit DMH-induced colorectal tumorigenesis by decreasing tumor volume and multiplicity. This study also shows that although the pretreatment with PBP extract could induce detoxifying enzymes in hepatic and colorectal tissue, it did not show any additional chemopreventive effects when compared to treatments with PBP extract after initiation with DMH. Mechanistically, PBP extract may inhibit colorectal carcinogenesis by decreasing DMH-induced cell proliferation via Wnt/{beta}-catenin pathway. Treatments with PBP extract showed decreased levels of COX-2, c-MYC and cyclin D1 proteins which aid cell proliferation probably by regulating {beta}-catenin by maintaining expression of APC and decreasing inactivation of GSK3{beta}. DMH-induced activation of MAP kinases such as ERK and JNK was also found to be inhibited by treatments with PBP extract. In conclusion, the protective effects of PBP extract could be attributed to inhibition of DMH-induced cellular proliferation probably through {beta}-catenin regulation.

  16. Dog as model for down-expression of E-cadherin and beta-catenin in tubular epithelial cells in renal fibrosis.

    PubMed

    Aresu, Luca; Rastaldi, Maria Pia; Pregel, Paola; Valenza, Federico; Radaelli, Enrico; Scanziani, Eugenio; Castagnaro, Massimo

    2008-12-01

    Mechanism of renal fibrosis leading to end stage kidney remains still a challenge of interest in humans. The pathogenesis of chronic kidney disease is characterized by progressive loss of kidney function and fibrosis. The mechanism of epithelial-mesenchymal transition (EMT) has been predominantly studied in in vitro studies, and we previously demonstrated the EMT of tubular epithelial cells in dogs. In this study, we examined and quantified the modifications of cadherin-catenin complex by immunohistochemistry of E-cadherin and beta-catenin and the mesenchymal marker vimentin in 25 dogs with three different spontaneous inflammatory renal diseases. Results showed a significant down-expression of levels of E-cadherin and beta-catenin directly correlated with the tubular-interstitial damage (TID). In TID grades 2 and 3, E-cadherin expression was significantly reduced (p < 0.001). beta-catenin expression was overall similar to E-cadherin. The mesenchymal-associated protein, vimentin, was de novo identified in tubules within areas of inflammation. In this work, we identified the loss of cadherin or catenin expression as a progressive mechanism in tubulo-interstitial fibrosis, which allows dissociation of structural integrity of renal epithelia and loss of epithelial polarity. The dog might result more significant as model for new therapies.

  17. Pharmacological modulation of beta-catenin and its applications in cancer therapy

    PubMed Central

    Thakur, Ravi; Mishra, Durga Prasad

    2013-01-01

    Beta-catenin (β-catenin) is a multifunction protein with a central role in physiological homeostasis. Its abnormal expression leads to various diseases including cancer. In normal physiology, β-catenin either maintains integrity of epithelial tissues or controls transcription of various genes on extracellular instigations. In epithelial tissues, β-catenin functions as a component of the cadherin protein complex and regulates epithelial cell growth and intracellular adhesion. In Wnt signalling, β-catenin is a major transcriptional modulator and plays a crucial role in embryogenesis, stem cell renewal and organ regeneration. Aberrant expression of β-catenin can induce malignant pathways in normal cells and its abnormal activity is also exploited by existing malignant programmes. It acts as an oncogene and modulates transcription of genes to drive cancer initiation, progression, survival and relapse. Abnormal expression and function of β-catenin in cancer makes it a putative drug target. In the past decade, various attempts have been made to identify and characterize various pharmacological inhibitors of β-catenin. Many of these inhibitors are currently being investigated for their anticancer activities in a variety of cancers. The first half of this review will focus on the role of β-catenin in cancer initiation, maintenance, progression and relapse whereas the second half will briefly summarize the recent progress in development of agents for the pharmacological modulation of β-catenin activity in cancer therapeutics. PMID:23490077

  18. The destruction complex of beta-catenin in colorectal carcinoma and colonic adenoma

    PubMed Central

    Bourroul, Guilherme Muniz; Fragoso, Hélio José; Gomes, José Walter Feitosa; Bourroul, Vivian Sati Oba; Oshima, Celina Tizuko Fujiyama; Gomes, Thiago Simão; Saba, Gabriela Tognini; Palma, Rogério Tadeu; Waisberg, Jaques

    2016-01-01

    ABSTRACT Objective To evaluate the destruction complex of beta-catenin by the expression of the proteins beta-catetenin, adenomatous polyposis coli, GSK3β, axin and ubiquitin in colorectal carcinoma and colonic adenoma. Methods Tissue samples from 64 patients with colorectal carcinoma and 53 patients with colonic adenoma were analyzed. Tissue microarray blocks and slides were prepared and subjected to immunohistochemistry with polyclonal antibodies in carcinoma, adjacent non-neoplastic mucosa, and adenoma tissues. The immunoreactivity was evaluated by the percentage of positive stained cells and by the intensity assessed through of the stained grade of proteins in the cytoplasm and nucleus of cells. In the statistical analysis, the Spearman correlation coefficient, Student’s t, χ2, Mann-Whitney, and McNemar tests, and univariate logistic regression analysis were used. Results In colorectal carcinoma, the expressions of beta-catenin and adenomatous polyposis coli proteins were significantly higher than in colonic adenomas (p<0.001 and p<0.0001, respectively). The immunoreactivity of GSK3β, axin 1 and ubiquitin proteins was significantly higher (p=0.03, p=0.039 and p=0.03, respectively) in colorectal carcinoma than in the colonic adenoma and adjacent non-neoplastic mucosa. The immunohistochemistry staining of these proteins did not show significant differences with the clinical and pathological characteristics of colorectal cancer and colonic adenoma. Conclusions These results suggest that, in adenomas, the lower expression of the beta-catenin, axin 1 and GSK3β proteins indicated that the destruction complex of beta-catenin was maintained, while in colorectal carcinoma, the increased expression of beta-catenin, GSK3β, axin 1, and ubiquitin proteins indicated that the destruction complex of beta-catenin was disrupted. PMID:27462886

  19. Decreased nuclear beta-catenin, tau hyperphosphorylation and neurodegeneration in GSK-3beta conditional transgenic mice.

    PubMed

    Lucas, J J; Hernández, F; Gómez-Ramos, P; Morán, M A; Hen, R; Avila, J

    2001-01-15

    Glycogen synthase kinase-3beta (GSK-3beta) has been postulated to mediate Alzheimer's disease tau hyperphosphorylation, beta-amyloid-induced neurotoxicity and presenilin-1 mutation pathogenic effects. By using the tet-regulated system we have produced conditional transgenic mice overexpressing GSK-3beta in the brain during adulthood while avoiding perinatal lethality due to embryonic transgene expression. These mice show decreased levels of nuclear beta-catenin and hyperphosphorylation of tau in hippocampal neurons, the latter resulting in pretangle-like somatodendritic localization of tau. Neurons displaying somatodendritic localization of tau often show abnormal morphologies and detachment from the surrounding neuropil. Reactive astrocytosis and microgliosis were also indicative of neuronal stress and death. This was further confirmed by TUNEL and cleaved caspase-3 immunostaining of dentate gyrus granule cells. Our results demonstrate that in vivo overexpression of GSK-3beta results in neurodegeneration and suggest that these mice can be used as an animal model to study the relevance of GSK-3beta deregulation to the pathogenesis of Alzheimer's disease.

  20. Promoter swapping between the genes for a novel zinc finger protein and beta-catenin in pleiomorphic adenomas with t(3;8)(p21;q12) translocations.

    PubMed

    Kas, K; Voz, M L; Röijer, E; Aström, A K; Meyen, E; Stenman, G; Van de Ven, W J

    1997-02-01

    Pleiomorphic adenoma of the salivary glands is a benign epithelial tumour occurring primarily in the major and minor salivary glands. It is by far the most common type of salivary gland tumour. Microscopically, pleiomorphic adenomas show a marked histological diversity with epithelial, myoepithelial and mesenchymal components in a variety of patterns. In addition to a cytogenetic subgroup with normal karyotypes, pleiomorphic adenomas are characterized by recurrent chromosome rearrangements, particularly reciprocal translocations, with breakpoints at 8q12, 3p21, and 12q13-15, in that order of frequency. The most common abnormality is a reciprocal t(3;8)(p21;q12). We here demonstrate that the t(3;8)(p21;q12) results in promoter swapping between PLAG1, a novel, developmentally regulated zinc finger gene at 8q12, and the constitutively expressed gene for beta-catenin (CTNNB1), a protein interface functioning in the WG/WNT signalling pathway and specification of cell fate during embryogenesis. Fusions occur in the 5'-non-coding regions of both genes, exchanging regulatory control elements while preserving the coding sequences. Due to the t(3;8)(p21;q12), PLAG1 is activated and expression levels of CTNNB1 are reduced. Activation of PLAG1 was also observed in an adenoma with a variant translocation t(8;15)(q12;q14). Our results indicate that PLAG1 activation due to promoter swapping is a crucial event in salivary gland tumourigenesis.

  1. Localized decrease of {beta}-catenin contributes to the differentiation of human embryonic stem cells

    SciTech Connect

    Lam, Hayley; Patel, Shyam; Wong, Janelle; Chu, Julia; Li, Adrian; Li, Song

    2008-08-08

    Human embryonic stem cells (hESC) are pluripotent, and can be directed to differentiate into different cell types for therapeutic applications. To expand hESCs, it is desirable to maintain hESC growth without differentiation. As hESC colonies grow, differentiated cells are often found at the periphery of the colonies, but the underlying mechanism is not well understood. Here, we utilized micropatterning techniques to pattern circular islands or strips of matrix proteins, and examined the spatial pattern of hESC renewal and differentiation. We found that micropatterned matrix restricted hESC differentiation at colony periphery but allowed hESC growth into multiple layers in the central region, which decreased hESC proliferation and induced hESC differentiation. In undifferentiated hESCs, {beta}-catenin primarily localized at cell-cell junctions but not in the nucleus. The amount of {beta}-catenin in differentiating hESCs at the periphery of colonies or in multiple layers decreased significantly at cell-cell junctions. Consistently, knocking down {beta}-catenin decreased Oct-4 expression in hESCs. These results indicate that localized decrease of {beta}-catenin contributes to the spatial pattern of differentiation in hESC colonies.

  2. A specific domain in alpha-catenin mediates binding to beta-catenin or plakoglobin.

    PubMed

    Huber, O; Krohn, M; Kemler, R

    1997-08-01

    The E-cadherin-catenin adhesion complex has been the subject of many structural and functional studies because of its importance in development, normal tissue function and carcinogenesis. It is well established that the cytoplasmic domain of E-cadherin binds either beta-catenin or plakoglobin, which both can assemble alpha-catenin into the complex. Recently we have identified an alpha-catenin binding site in beta-catenin and plakoglobin and postulated, based on sequence analysis, that these protein-protein interactions are mediated by a hydrophobic interaction mechanism. Here we have now identified the reciprocal complementary binding site in alpha-catenin which mediates its interaction with beta-catenin and plakoglobin. Using in vitro association assays with C-terminal truncations of alpha-catenin expressed as recombinant fusion proteins, we found that the N-terminal 146 amino acids are required for this interaction. We then identified a peptide of 27 amino acids within this sequence (amino acid positions 117-143) which is necessary and sufficient to bind beta-catenin or plakoglobin. As shown by mutational analysis, hydrophobic amino acids within this binding site are important for the interaction. The results described here, together with our previous work, give strong support for the idea that these proteins associate by hydrophobic interactions of two alpha-helices.

  3. Hit to lead studies on (hetero)arylpyrimidines--agonists of the canonical Wnt-beta-catenin cellular messaging system.

    PubMed

    Gilbert, Adam M; Bursavich, Matthew G; Alon, Nippa; Bhat, Bheem M; Bex, Frederick J; Cain, Michael; Coleburn, Valerie; Gironda, Virginia; Green, Paula; Hauze, Diane B; Kharode, Yogendra; Krishnamurthy, Girija; Kirisits, Matthew; Lam, Ho-Sun; Liu, Yao-Bin; Lombardi, Sabrina; Matteo, Jeanne; Murrills, Richard; Robinson, John A; Selim, Sally; Sharp, Michael; Unwalla, Raymond; Varadarajan, Usha; Zhao, Weiguang; Yaworsky, Paul J

    2010-01-01

    A series of (hetero)arylpyrimidines agonists of the Wnt-beta-catenin cellular messaging system have been prepared. These compounds show activity in U2OS cells transfected with Wnt-3a, TCF-luciferase, Dkk-1 and tk-Renilla. Selected compounds show minimal GSK-3beta inhibition indicating that the Wnt-beta-catenin agonism activity most likely comes from interaction at Wnt-3a/Dkk-1. Two examples 1 and 25 show in vivo osteogenic activity in a mouse calvaria model. One example 1 is shown to activate non-phosphorylated beta-catenin formation in bone. PMID:19897365

  4. [CELL CONTACT PROTEIN BETA-CATENIN IN EPENDYMAL AND EPITHELIAL CELLS OF THE CHOROID PLEXUS OF THE CEREBRAL LATERAL VENTRICLES].

    PubMed

    Kirik, O V; Sufieyva, D A; Nazarenkova, A V; Korzhevskiy, D E

    2016-01-01

    The purpose of this study was to examine the distribution pattern of cellular contacts protein beta-catenin in the choroid plexus and ependyma of lateral ventricles of the brain. The study was conducted on frontal sections of the brain of Wistar rats (n = 10) using polyclonal antibodies against beta-catenin. The obtained preparations were analyzed by microscopy in transmitted light and using confocal laser microscopy. To study the distribution of beta-catenin in different projections, three-dimensional reconstruction was performed. The study demonstrated different distribution patterns of this protein in ependyma and choroid plexus. Unlike ependyma, in the cells of the choroid plexus beta-catenin was distributed in the same way as in simple epithelial tissues (on the basal and lateral borders of the cells). This may indicate different tissue attribution of the ependyma and the choroid plexus epithelium, despite their common origin. PMID:27487660

  5. Chondroitin Sulfate-E Is a Negative Regulator of a Pro-Tumorigenic Wnt/Beta-Catenin-Collagen 1 Axis in Breast Cancer Cells

    PubMed Central

    Willis, Catherine M.; Klüppel, Michael

    2014-01-01

    Expression of the glycosaminoglycan chondroitin sulfate-E (CS-E) is misregulated in many human cancers, including breast cancer. Cell-surface associated CS-E has been shown to have pro-tumorigenic functions, and pharmacological treatment with exogenous CS-E has been proposed to interfere with tumor progression mediated by endogenous CS-E. However, the effects of exogenous CS-E on breast cancer cell behavior, and the molecular mechanisms deployed by CS-E are not well understood. We show here that treatment with CS-E, but not other chondroitin forms, could interfere with the invasive protrusion formation and migration of breast cancer cells in three-dimensional organotypic cultures. Microarray analysis identified transcriptional programs controlled by CS-E in these cells. Importantly, negative regulation of the pro-metastatic extracellular matrix gene Col1a1 was required for the anti-migratory effects of exogenous CS-E. Knock-down of Col1a1 gene expression mimics the effects of CS-E treatment, while exposing cells to a preformed collagen I matrix interfered with the anti-migratory effects of CS-E. In addition, CS-E specifically interfered with Wnt/beta-catenin signaling, a known pro-tumorigenic pathway. Lastly, we demonstrate that Col1a1 is a positively regulated target gene of the Wnt/beta-catenin pathway in breast cancer cells. Together, our data identify treatment with exogenous CS-E as negative regulatory mechanism of breast cancer cell motility through interference with a pro-tumorigenic Wnt/beta-catenin - Collagen I axis. PMID:25090092

  6. Stimulation of Na{sup +}/K{sup +} ATPase activity and Na{sup +} coupled glucose transport by {beta}-catenin

    SciTech Connect

    Sopjani, Mentor; Alesutan, Ioana; Wilmes, Jan; Dermaku-Sopjani, Miribane; Lam, Rebecca S.; Jakupi, Muharrem; Foeller, Michael; Lang, Florian

    2010-11-19

    Research highlights: {yields} The oncogenic transcription factor {beta}-catenin stimulates the Na{sup +}/K{sup +}-ATPase. {yields} {beta}-Catenin stimulates SGLT1 dependent Na{sup +}, glucose cotransport. {yields} The effects are independent of transcription. {yields} {beta}-Catenin sensitive transport may contribute to properties of proliferating cells. -- Abstract: {beta}-Catenin is a multifunctional protein stimulating as oncogenic transcription factor several genes important for cell proliferation. {beta}-Catenin-regulated genes include the serum- and glucocorticoid-inducible kinase SGK1, which is known to stimulate a variety of transport systems. The present study explored the possibility that {beta}-catenin influences membrane transport. To this end, {beta}-catenin was expressed in Xenopus oocytes with or without SGLT1 and electrogenic transport determined by dual electrode voltage clamp. As a result, expression of {beta}-catenin significantly enhanced the ouabain-sensitive current of the endogeneous Na{sup +}/K{sup +}-ATPase. Inhibition of vesicle trafficking by brefeldin A revealed that the stimulatory effect of {beta}-catenin on the endogenous Na{sup +}/K{sup +}-ATPase was not due to enhanced stability of the pump protein in the cell membrane. Expression of {beta}-catenin further enhanced glucose-induced current (Ig) in SGLT1-expressing oocytes. In the absence of SGLT1 Ig was negligible irrespective of {beta}-catenin expression. The stimulating effect of {beta}-catenin on both Na{sup +}/K{sup +} ATPase and SGLT1 activity was observed even in the presence of actinomycin D, an inhibitor of transcription. The experiments disclose a completely novel function of {beta}-catenin, i.e. the regulation of transport.

  7. Direct interaction of tumor suppressor CEACAM1 with beta catenin: identification of key residues in the long cytoplasmic domain.

    PubMed

    Jin, Lan; Li, Yun; Chen, Charng-Jui; Sherman, Mark A; Le, Keith; Shively, John E

    2008-07-01

    CEACAM1-4L (carcinoembryonic antigen cell adhesion molecule 1, with 4 extracellular Ig-like domains and a long, 71 amino acid cytoplasmic domain) is expressed in epithelial cells and activated T-cells, but is down-regulated in most epithelial cell cancers and T-cell leukemias. A highly conserved sequence within the cytoplasmic domain has ca 50% sequence homology with Tcf-3 and -4, transcription factors that bind beta-catenin, and to a lesser extent (32% homology), with E-cadherin that also binds beta-catenin. We show by quantitative yeast two-hybrid, BIAcore, GST-pull down, and confocal analyses that this domain directly interacts with beta-catenin, and that H-469 and K-470 are key residues that interact with the armadillo repeats of beta-catenin. Jurkat cells transfected with CEACAM1-4L have 2-fold less activity in the TOPFLASH reporter assay, and in MCF7 breast cancer cells that fail to express CEACAM1, transfection with CEACAM1 and growth in Ca2+ media causes redistribution of beta-catenin from the cytoplasm to the cell membrane, demonstrating a functional role for the long cytoplasmic domain of CEACAM1 in regulation of beta-catenin activity.

  8. Neurofilament heavy polypeptide regulates the Akt-beta-catenin pathway in human esophageal squamous cell carcinoma.

    PubMed

    Kim, Myoung Sook; Chang, Xiaofei; LeBron, Cynthia; Nagpal, Jatin K; Lee, Juna; Huang, Yiping; Yamashita, Keishi; Trink, Barry; Ratovitski, Edward A; Sidransky, David

    2010-01-01

    Aerobic glycolysis and mitochondrial dysfunction are common features of aggressive cancer growth. We observed promoter methylation and loss of expression in neurofilament heavy polypeptide (NEFH) in a significant proportion of primary esophageal squamous cell carcinoma (ESCC) samples that were of a high tumor grade and advanced stage. RNA interference-mediated knockdown of NEFH accelerated ESCC cell growth in culture and increased tumorigenicity in vivo, whereas forced expression of NEFH significantly inhibited cell growth and colony formation. Loss of NEFH caused up-regulation of pyruvate kinase-M2 type and down-regulation of pyruvate dehydrogenase, via activation of the Akt/beta-catenin pathway, resulting in enhanced aerobic glycolysis and mitochondrial dysfunction. The acceleration of glycolysis and mitochondrial dysfunction in NEFH-knockdown cells was suppressed in the absence of beta-catenin expression, and was decreased by the treatment of 2-Deoxyglucose, a glycolytic inhibitor, or API-2, an Akt inhibitor. Loss of NEFH activates the Akt/beta-catenin pathway and increases glycolysis and mitochondrial dysfunction. Cancer cells with methylated NEFH can be targeted for destruction with specific inhibitors of deregulated downstream pathways.

  9. De novo mutations in beta-catenin (CTNNB1) appear to be a frequent cause of intellectual disability: expanding the mutational and clinical spectrum.

    PubMed

    Kuechler, Alma; Willemsen, Marjolein H; Albrecht, Beate; Bacino, Carlos A; Bartholomew, Dennis W; van Bokhoven, Hans; van den Boogaard, Marie Jose H; Bramswig, Nuria; Büttner, Christian; Cremer, Kirsten; Czeschik, Johanna Christina; Engels, Hartmut; van Gassen, Koen; Graf, Elisabeth; van Haelst, Mieke; He, Weimin; Hogue, Jacob S; Kempers, Marlies; Koolen, David; Monroe, Glen; de Munnik, Sonja; Pastore, Matthew; Reis, André; Reuter, Miriam S; Tegay, David H; Veltman, Joris; Visser, Gepke; van Hasselt, Peter; Smeets, Eric E J; Vissers, Lisenka; Wieland, Thomas; Wissink, Willemijn; Yntema, Helger; Zink, Alexander Michael; Strom, Tim M; Lüdecke, Hermann-Josef; Kleefstra, Tjitske; Wieczorek, Dagmar

    2015-01-01

    Recently, de novo heterozygous loss-of-function mutations in beta-catenin (CTNNB1) were described for the first time in four individuals with intellectual disability (ID), microcephaly, limited speech and (progressive) spasticity, and functional consequences of CTNNB1 deficiency were characterized in a mouse model. Beta-catenin is a key downstream component of the canonical Wnt signaling pathway. Somatic gain-of-function mutations have already been found in various tumor types, whereas germline loss-of-function mutations in animal models have been shown to influence neuronal development and maturation. We report on 16 additional individuals from 15 families in whom we newly identified de novo loss-of-function CTNNB1 mutations (six nonsense, five frameshift, one missense, two splice mutation, and one whole gene deletion). All patients have ID, motor delay and speech impairment (both mostly severe) and abnormal muscle tone (truncal hypotonia and distal hypertonia/spasticity). The craniofacial phenotype comprised microcephaly (typically -2 to -4 SD) in 12 of 16 and some overlapping facial features in all individuals (broad nasal tip, small alae nasi, long and/or flat philtrum, thin upper lip vermillion). With this detailed phenotypic characterization of 16 additional individuals, we expand and further establish the clinical and mutational spectrum of inactivating CTNNB1 mutations and thereby clinically delineate this new CTNNB1 haploinsufficiency syndrome.

  10. Beta-catenin inhibits cell growth of a malignant mesothelioma cell line, NCI-H28, with a 3p21.3 homozygous deletion.

    PubMed

    Usami, Noriyasu; Sekido, Yoshitaka; Maeda, Osamu; Yamamoto, Kazuhito; Minna, John D; Hasegawa, Yoshinori; Yoshioka, Hiromu; Imaizumi, Munehisa; Ueda, Yuichi; Takahashi, Masahide; Shimokata, Kaoru

    2003-09-11

    We have found that a malignant mesothelioma cell line, NCI-H28, had a chromosome 3p21.3 homozygous deletion containing the beta-catenin gene (CTNNB1), which suggested that the deletion of beta-catenin might have a growth advantage in the development of this tumor. To determine whether beta-catenin has a growth-inhibitory activity, we transfected wild-type beta-catenin, Ser37Cys mutant beta-catenin as an activated type, and C-terminus deletion mutant beta-catenin that lacks the transcription activity, into the NCI-H28 cells. A non-small cell lung cancer cell line, NCI-H1299, which expressed endogenous beta-catenin, was also studied. We tested the localization of exogenous beta-catenin in the NCI-H28 cells with immunofluorescence, and found that the wild-type beta-catenin and the C-terminus deletion mutant were more strongly expressed in the plasma membrane and cytoplasm than in the nucleus, while the Ser37Cys mutant was more in the nucleus than in the cytoplasm. By using luciferase-reporter assay, the beta-catenin/T-cell factor 4-mediated transactivity of the Ser37Cys mutant was shown to be higher than that of the wild-type beta-catenin in both cell lines. However, the transactivity of the C-terminus deletion mutant was strongly reduced in both. Colony formation of the NCI-H28 cells was reduced by 50% after transfection with the wild-type beta-catenin, and 60% with the Ser37Cys mutant, but only 20% with the C-terminus deletion mutant compared to the vector control. Inhibition of colony formation in NCI-H28 cells was because of apoptosis, manifested by positive staining of Annexin V and TUNEL assays in transfected cells. In contrast, when transfected with the wild-type beta-catenin, no significant reduction in colony formation was seen in beta-catenin wild-type NCI-H1299 cells. In conclusion, our data indicate that inactivation of beta-catenin by a 3p21.3 homozygous deletion might be a crucial event in the development of the mesothelioma NCI-H28 cells. Thus, while

  11. Beta-catenin (CTNNB1) induces Bmp expression in urogenital sinus epithelium and participates in prostatic bud initiation and patterning

    PubMed Central

    Mehta, Vatsal; Schmitz, Christopher T.; Keil, Kimberly P.; Joshi, Pinak S.; Abler, Lisa L.; Lin, Tien-Min; Taketo, Makoto M.; Sun, Xin; Vezina, Chad M.

    2013-01-01

    Fetal prostate development is initiated by androgens and patterned by androgen dependent and independent signals. How these signals integrate to control epithelial cell differentiation and prostatic bud patterning is not fully understood. To test the role of beta-catenin (Ctnnb1) in this process, we used a genetic approach to conditionally delete or stabilize Ctnnb1 in urogenital sinus (UGS) epithelium from which the prostate derives. Two opposing mechanisms of action were revealed. By deleting Ctnnb1, we found it is required for separation of UGS from cloaca, emergence or maintenance of differentiated UGS basal epithelium and formation of prostatic buds. By genetically inducing a patchy subset of UGS epithelial cells to express excess CTNNB1, we found its excess abundance increases Bmp expression and leads to a global impairment of prostatic bud formation. Addition of NOGGIN partially restores prostatic budding in UGS explants with excess Ctnnb1. These results indicate a requirement for Ctnnb1 in UGS basal epithelial cell differentiation, prostatic bud initiation and bud spacing and suggest some of these actions are mediated in part through activation of BMP signaling. PMID:23396188

  12. Secreted Frizzled-related protein-2 (sFRP2) augments canonical Wnt3a-induced signaling

    SciTech Connect

    Marschall, Zofia von; Fisher, Larry W.

    2010-09-24

    Research highlights: {yields} sFRP2 enhances the Wnt3a-induced {beta}-catenin stabilization and its nuclear translocation. {yields} sFRP2 enhances LRP6 phosphorylation and Wnt3a/{beta}-catenin transcriptional reporter activity. {yields} Dickkopf-1 (DKK1) fully antagonizes both Wnt3a/sFRP2-induced LRP6 phosphorylation and transcriptional activity. {yields} sFRP2 enhances expression of genes known to be regulated by Wnt3a signaling. -- Abstract: Secreted Frizzled-related proteins (sFRP) are involved in embryonic development as well as pathological conditions including bone and myocardial disorders and cancer. Because of their sequence homology with the Wnt-binding domain of Frizzled, they have generally been considered antagonists of canonical Wnt signaling. However, additional activities of various sFRPs including both synergism and mimicry of Wnt signaling as well as functions other than modulation of Wnt signaling have been reported. Using human embryonic kidney cells (HEK293A), we found that sFRP2 enhanced Wnt3a-dependent phosphorylation of LRP6 as well as both cytosolic {beta}-catenin levels and its nuclear translocation. While addition of recombinant sFRP2 had no activity by itself, Top/Fop luciferase reporter assays showed a dose-dependent increase of Wnt3a-mediated transcriptional activity. sFRP2 enhancement of Wnt3a signaling was abolished by treatment with the Wnt antagonist, Dickkopf-1 (DKK1). Wnt-signaling pathway qPCR arrays showed that sFRP2 enhanced the Wnt3a-mediated transcriptional up-regulation of several genes regulated by Wnt3a including its antagonists, DKK1, and Naked cuticle-1 homolog (NKD1). These results support sFRP2's role as an enhancer of Wnt/{beta}-catenin signaling, a result with biological impact for both normal development and diverse pathologies such as tumorigenesis.

  13. Gonadal Identity in the Absence of Pro-Testis Factor SOX9 and Pro-Ovary Factor Beta-Catenin in Mice.

    PubMed

    Nicol, Barbara; Yao, Humphrey H-C

    2015-08-01

    Sex-reversal cases in humans and genetic models in mice have revealed that the fate of the bipotential gonad hinges upon the balance between pro-testis SOX9 and pro-ovary beta-catenin pathways. Our central query was: if SOX9 and beta-catenin define the gonad's identity, then what do the gonads become when both factors are absent? To answer this question, we developed mouse models that lack either Sox9, beta-catenin, or both in the somatic cells of the fetal gonads and examined the morphological outcomes and transcriptome profiles. In the absence of Sox9 and beta-catenin, both XX and XY gonads progressively lean toward the testis fate, indicating that expression of certain pro-testis genes requires the repression of the beta-catenin pathway, rather than a direct activation by SOX9. We also observed that XY double knockout gonads were more masculinized than their XX counterpart. To identify the genes responsible for the initial events of masculinization and to determine how the genetic context (XX vs. XY) affects this process, we compared the transcriptomes of Sox9/beta-catenin mutant gonads and found that early molecular changes underlying the XY-specific masculinization involve the expression of Sry and 21 SRY direct target genes, such as Sox8 and Cyp26b1. These results imply that when both Sox9 and beta-catenin are absent, Sry is capable of activating other pro-testis genes and drive testis differentiation. Our findings not only provide insight into the mechanism of sex determination, but also identify candidate genes that are potentially involved in disorders of sex development.

  14. Fyn is a downstream target of the pleiotrophin/receptor protein tyrosine phosphatase beta/zeta-signaling pathway: regulation of tyrosine phosphorylation of Fyn by pleiotrophin.

    PubMed

    Pariser, Harold; Ezquerra, Laura; Herradon, Gonzalo; Perez-Pinera, Pablo; Deuel, Thomas F

    2005-07-01

    Pleiotrophin (PTN the protein, Ptn the gene) signals downstream targets through inactivation of its receptor, the transmembrane receptor protein tyrosine phosphatase (RPTP)beta/zeta, disrupting the balanced activity of RPTPbeta/zeta and the activity of a constitutively active tyrosine kinase. As a consequence of the inactivation of RPTPbeta/zeta, PTN stimulates a sharp increase in the levels of tyrosine phosphorylation of the substrates of RPTPbeta/zeta in PTN-stimulated cells. We now report that the Src family member Fyn interacts with the intracellular domain of RPTPbeta/zeta in a yeast two-hybrid system. We further demonstrate that Fyn is a substrate of RPTPbeta/zeta, and that tyrosine phosphorylation of Fyn is sharply increased in PTN-stimulated cells. In previous studies, we demonstrated that beta-catenin and beta-adducin are targets of the PTN/RPTPbeta/zeta-signaling pathway and defined the mechanisms through which tyrosine phosphorylation of beta-catenin and beta-adducin disrupts cytoskeletal protein complexes. We conclude that Fyn is a downstream target of the PTN/RPTPbeta/zeta-signaling pathway and suggest that PTN coordinately regulates tyrosine phosphorylation of beta-catenin, beta-adducin, and Fyn through the PTN/RPTPbeta/zeta-signaling pathway and that together Fyn, beta-adducin, and beta-catenin may be effectors of the previously described PTN-stimulated disruption of cytoskeletal stability, increased cell plasticity, and loss of cell-cell adhesion that are characteristic of PTN-stimulated cells and a feature of many human malignant cells in which mutations have established constitutive expression of the Ptn gene.

  15. Nr-CAM is a target gene of the beta-catenin/LEF-1 pathway in melanoma and colon cancer and its expression enhances motility and confers tumorigenesis.

    PubMed

    Conacci-Sorrell, Maralice E; Ben-Yedidia, Tamar; Shtutman, Michael; Feinstein, Elena; Einat, Paz; Ben-Ze'ev, Avri

    2002-08-15

    beta-catenin and plakoglobin (gamma-catenin) are homologous molecules involved in cell adhesion, linking cadherin receptors to the cytoskeleton. beta-catenin is also a key component of the Wnt pathway by being a coactivator of LEF/TCF transcription factors. To identify novel target genes induced by beta-catenin and/or plakoglobin, DNA microarray analysis was carried out with RNA from cells overexpressing either protein. This analysis revealed that Nr-CAM is the gene most extensively induced by both catenins. Overexpression of either beta-catenin or plakoglobin induced Nr-CAM in a variety of cell types and the LEF/TCF binding sites in the Nr-CAM promoter were required for its activation by catenins. Retroviral transduction of Nr-CAM into NIH3T3 cells stimulated cell growth, enhanced motility, induced transformation, and produced rapidly growing tumors in nude mice. Nr-CAM and LEF-1 expression was elevated in human colon cancer tissue and cell lines and in human malignant melanoma cell lines but not in melanocytes or normal colon tissue. Dominant negative LEF-1 decreased Nr-CAM expression and antibodies to Nr-CAM inhibited the motility of B16 melanoma cells. The results indicate that induction of Nr-CAM transcription by beta-catenin or plakoglobin plays a role in melanoma and colon cancer tumorigenesis, probably by promoting cell growth and motility. PMID:12183361

  16. A genome-wide RNAi screen for Wnt/beta-catenin pathway components identifies unexpected roles for TCF transcription factors in cancer.

    PubMed

    Tang, Wei; Dodge, Michael; Gundapaneni, Deepika; Michnoff, Carolyn; Roth, Michael; Lum, Lawrence

    2008-07-15

    The Wnt family of secreted proteins coordinate cell fate decision-making in a broad range of developmental and homeostatic contexts. Corruption of Wnt signal transduction pathways frequently results in degenerative diseases and cancer. We have used an iterative genome-wide screening strategy that employs multiple nonredundant RNAi reagents to identify mammalian genes that participate in Wnt/beta-catenin pathway response. Among the genes that were assigned high confidence scores are two members of the TCF/LEF family of DNA-binding proteins that control the transcriptional output of the pathway. Surprisingly, we found that the presumed cancer-promoting gene TCF7L2 functions instead as a transcriptional repressor that restricts colorectal cancer (CRC) cell growth. Mutations in TCF7L2 identified from cancer genome sequencing efforts abolish its ability to function as a transcriptional regulator and result in increased CRC cell growth. We describe a growth-promoting transcriptional program that is likely activated in CRC tumors with compromised TCF7L2 function. Taken together, the results from our screen and studies focused on members of the TCF/LEF gene family refine our understanding of how aberrant Wnt pathway activation sustains CRC growth.

  17. Palmitate Antagonizes Wnt/Beta-catenin Signaling in 3T3-L1 Pre-adipocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long chain saturated free fatty acids such as palmitate (PA) produce insulin resistance, endoplasmic reticulum stress, and apoptosis in mature adipocytes and pre-adipocytes. In pre-adipocytes, saturated free fatty acids also promote adipogenic induction in the presence of adipogenic hormones. Wnt/be...

  18. P38 MAPK / beta-catenin canonical wnt signaling mediated bone formation effects of blueberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Appropriate nutrition is one of the critical factors that influences bone development. We studied the effects of dietary blueberry supplementation on bone growth in weanling rats. Weanling male and female rats were fed AIN-93G semi-purified diets supplemented with 10% whole blueberry powder for 14 a...

  19. Wnt signaling and colon tumorigenesis - A view from the periphery

    SciTech Connect

    Burgess, Antony W.; Faux, Maree C.; Layton, Meredith J.; Ramsay, Robert G.

    2011-11-15

    In this brief overview we discuss the association between Wnt signaling and colon cell biology and tumorigenesis. Our current understanding of the role of Apc in the {beta}-catenin destruction complex is compared with potential roles for Apc in cell adhesion and migration. The requirement for phosphorylation in the proteasomal-mediated degradation of {beta}-catenin is contrasted with roles for phospho-{beta}-catenin in the activation of transcription, cell adhesion and migration. The synergy between Myb and {beta}-catenin regulation of transcription in crypt stem cells during Wnt signaling is discussed. Finally, potential effects of growth factor regulatory systems, Apc or truncated-Apc on crypt morphogenesis, stem cell localization and crypt fission are considered.

  20. Canonical Wnt signaling in differentiated osteoblasts controls osteoclast differentiation.

    PubMed

    Glass, Donald A; Bialek, Peter; Ahn, Jong Deok; Starbuck, Michael; Patel, Millan S; Clevers, Hans; Taketo, Mark M; Long, Fanxin; McMahon, Andrew P; Lang, Richard A; Karsenty, Gerard

    2005-05-01

    Inactivation of beta-catenin in mesenchymal progenitors prevents osteoblast differentiation; inactivation of Lrp5, a gene encoding a likely Wnt coreceptor, results in low bone mass (osteopenia) by decreasing bone formation. These observations indicate that Wnt signaling controls osteoblast differentiation and suggest that it may regulate bone formation in differentiated osteoblasts. Here, we study later events and find that stabilization of beta-catenin in differentiated osteoblasts results in high bone mass, while its deletion from differentiated osteoblasts leads to osteopenia. Surprisingly, histological analysis showed that these mutations primarily affect bone resorption rather than bone formation. Cellular and molecular studies showed that beta-catenin together with TCF proteins regulates osteoblast expression of Osteoprotegerin, a major inhibitor of osteoclast differentiation. These findings demonstrate that beta-catenin, and presumably Wnt signaling, promote the ability of differentiated osteoblasts to inhibit osteoclast differentiation; thus, they broaden our knowledge of the functions Wnt proteins have at various stages of skeletogenesis. PMID:15866165

  1. Attenuated Response to Methamphetamine Sensitization and Deficits in Motor Learning and Memory after Selective Deletion of [beta]-Catenin in Dopamine Neurons

    ERIC Educational Resources Information Center

    Diaz-Ruiz, Oscar; Zhang, YaJun; Shan, Lufei; Malik, Nasir; Hoffman, Alexander F.; Ladenheim, Bruce; Cadet, Jean Lud; Lupica, Carl R.; Tagliaferro, Adriana; Brusco, Alicia; Backman, Cristina M.

    2012-01-01

    In the present study, we analyzed mice with a targeted deletion of [beta]-catenin in DA neurons (DA-[beta]cat KO mice) to address the functional significance of this molecule in the shaping of synaptic responses associated with motor learning and following exposure to drugs of abuse. Relative to controls, DA-[beta]cat KO mice showed significant…

  2. Circadian rhythms, Wnt/beta-catenin pathway and PPAR alpha/gamma profiles in diseases with primary or secondary cardiac dysfunction

    PubMed Central

    Lecarpentier, Yves; Claes, Victor; Duthoit, Guillaume; Hébert, Jean-Louis

    2014-01-01

    Circadian clock mechanisms are far-from-equilibrium dissipative structures. Peroxisome proliferator-activated receptors (PPAR alpha, beta/delta, and gamma) play a key role in metabolic regulatory processes, particularly in heart muscle. Links between circadian rhythms (CRs) and PPARs have been established. Mammalian CRs involve at least two critical transcription factors, CLOCK and BMAL1 (Gekakis et al., 1998; Hogenesch et al., 1998). PPAR gamma plays a major role in both glucose and lipid metabolisms and presents circadian properties which coordinate the interplay between metabolism and CRs. PPAR gamma is a major component of the vascular clock. Vascular PPAR gamma is a peripheral regulator of cardiovascular rhythms controlling circadian variations in blood pressure and heart rate through BMAL1. We focused our review on diseases with abnormalities of CRs and with primary or secondary cardiac dysfunction. Moreover, these diseases presented changes in the Wnt/beta-catenin pathway and PPARs, according to two opposed profiles. Profile 1 was defined as follows: inactivation of the Wnt/beta-catenin pathway with increased expression of PPAR gamma. Profile 2 was defined as follows: activation of the Wnt/beta-catenin pathway with decreased expression of PPAR gamma. A typical profile 1 disease is arrhythmogenic right ventricular cardiomyopathy, a genetic cardiac disease which presents mutations of the desmosomal proteins and is mainly characterized by fatty acid accumulation in adult cardiomyocytes mainly in the right ventricle. The link between PPAR gamma dysfunction and desmosomal genetic mutations occurs via inactivation of the Wnt/beta-catenin pathway presenting oscillatory properties. A typical profile 2 disease is type 2 diabetes, with activation of the Wnt/beta-catenin pathway and decreased expression of PPAR gamma. CRs abnormalities are present in numerous pathologies such as cardiovascular diseases, sympathetic/parasympathetic dysfunction, hypertension, diabetes

  3. Beta-catenin-activated hepatocellular adenoma showing hyperintensity on hepatobiliary-phase gadoxetic-enhanced magnetic resonance imaging and overexpression of OATP8.

    PubMed

    Yoneda, Norihide; Matsui, Osamu; Kitao, Azusa; Kozaka, Kazuto; Gabata, Toshifumi; Sasaki, Motoko; Nakanuma, Yasuni; Murata, Kiyoshi; Tani, Toru

    2012-11-01

    We report a male case of beta-catenin-activated hepatocellular adenoma (HCA) focusing on findings of gadoxetic-acid-enhanced magnetic resonance imaging (EOB-MRI) and discussing the molecular background and possible clinical significance. The patient was a 31-year-old man in whom computed tomography (CT) showed a large nodule of 14 cm in diameter in the right liver lobe. On dynamic contrast-enhanced CT, heterogeneous and slight to moderate enhancement was observed during the early phase, with washout in the late phase. Focal fat deposits and a scar-like portion in the lesion were also seen. Most of the lesion was slightly hyperintense compared with the background liver on the hepatobiliary phase of EOB-MRI. After operation, this patient was confirmed pathologically as having beta-catenin-activated HCA with a portion suggestive of malignant transformation. In addition, intense organic anion transporter polypeptide 8 expression was observed throughout the tumor by immunohistochemical staining.

  4. Tumor Endothelial Marker 8 Amplifies Canonical Wnt Signaling in Blood Vessels

    PubMed Central

    Verma, Kiran; Gu, Jingsheng; Werner, Erica

    2011-01-01

    Tumor Endothelial Marker 8/Anthrax Toxin Receptor 1 (TEM8/ANTXR1) expression is induced in the vascular compartment of multiple tumors and therefore, is a candidate molecule to target tumor therapies. This cell surface molecule mediates anthrax toxin internalization, however, its physiological function in blood vessels remains largely unknown. We identified the chicken chorioallantoic membrane (CAM) as a model system to study the endogenous function of TEM8 in blood vessels as we found that TEM8 expression was induced transiently between day 10 and 12 of embryonic development, when the vascular tree is undergoing final development and growth. We used the cell-binding component of anthrax toxin, Protective Antigen (PA), to engage endogenous TEM8 receptors and evaluate the effects of PA-TEM8 complexes on vascular development. PA applied at the time of highest TEM8 expression reduced vascular density and disrupted hierarchical branching as revealed by quantitative morphometric analysis of the vascular tree after 48h. PA-dependent reduced branching phenotype was partially mimicked by Wnt3a application and ameliorated by the Wnt antagonist, Dikkopf-1. These results implicate TEM8 expression in endothelial cells in regulating the canonical Wnt signaling pathway at this day of CAM development. Consistent with this model, PA increased beta catenin levels acutely in CAM blood vessels in vivo and in TEM8 transfected primary human endothelial cells in vitro. TEM8 expression in Hek293 cells, which neither express endogenous PA-binding receptors nor Wnt ligands, stabilized beta catenin levels and amplified beta catenin-dependent transcriptional activity induced by Wnt3a. This agonistic function is supported by findings in the CAM, where the increase in TEM8 expression from day 10 to day 12 and PA application correlated with Axin 2 induction, a universal reporter gene for canonical Wnt signaling. We postulate that the developmentally controlled expression of TEM8 modulates

  5. The catenin p120{sup ctn} inhibits Kaiso-mediated transcriptional repression of the {beta}-catenin/TCF target gene matrilysin

    SciTech Connect

    Spring, Christopher M.; Kelly, Kevin F.; O'Kelly, Ita; Graham, Monica; Crawford, Howard C.; Daniel, Juliet M. . E-mail: danielj@mcmaster.ca

    2005-05-01

    The POZ-zinc finger transcription factor Kaiso was first identified as a specific binding partner for the Armadillo catenin and cell adhesion cofactor, p120{sup ctn}. Kaiso is a unique POZ protein with bi-modal DNA-binding properties; it associates with a sequence-specific DNA consensus Kaiso binding site (KBS) or methylated CpG dinucleotides, and regulates transcription of artificial promoters containing either site. Interestingly, the promoter of the Wnt/{beta}-catenin/TCF target gene matrilysin possesses two conserved copies of the KBS, which suggested that Kaiso might regulate matrilysin expression. In this study, we demonstrate using chromatin immunoprecipitation analysis that Kaiso associates with the matrilysin promoter in vivo. Minimal promoter assays further confirmed that Kaiso specifically repressed transcription of the matrilysin promoter; mutation of the KBS element or RNAi-mediated depletion of Kaiso abrogated this effect. More importantly, Kaiso blocked {beta}-catenin-mediated activation of the matrilysin promoter. Consistent with our previous findings, both Kaiso-DNA binding and Kaiso-mediated transcriptional repression of the matrilysin promoter were inhibited by overexpression of wild-type p120{sup ctn}, but not by a p120{sup ctn} mutant exhibiting impaired nuclear import. Collectively, our data establish Kaiso as a sequence-specific transcriptional repressor of the matrilysin promoter, and suggest that p120{sup ctn} and {beta}-catenin act in a synergistic manner, via distinct mechanisms, to activate matrilysin expression.

  6. Leukocyte Beta-Catenin Expression Is Disturbed in Systemic Lupus Erythematosus.

    PubMed

    Orme, Jacob J; Du, Yong; Vanarsa, Kamala; Wu, Tianfu; Satterthwaite, Anne B; Mohan, Chandra

    2016-01-01

    Wnt/β-catenin signaling is relatively understudied in immunity and autoimmunity. β-catenin blocks inflammatory mediators and favors tolerogenic dendritic cell (DC) phenotypes. We show here that leukocytes from lupus-prone mice and SLE patients express diminished β-catenin transcriptional activity, particularly in myeloid cells, although other leukocytes revealed similar trends. Serum levels of DKK-1, an inhibitor under transcriptional control of Wnt/β-catenin, were also decreased in lupus-prone mice. Surprisingly, however, preemptive deletion of β-catenin from macrophages appears to have no effect on lupus development, even in mice with varying genetic loads for lupus. Although myeloid-specific loss of β-catenin does not seem to be important for lupus development, the potential role of this transcription factor in other leukocytes and renal cells remain to be elucidated. PMID:27548498

  7. Leukocyte Beta-Catenin Expression Is Disturbed in Systemic Lupus Erythematosus.

    PubMed

    Orme, Jacob J; Du, Yong; Vanarsa, Kamala; Wu, Tianfu; Satterthwaite, Anne B; Mohan, Chandra

    2016-01-01

    Wnt/β-catenin signaling is relatively understudied in immunity and autoimmunity. β-catenin blocks inflammatory mediators and favors tolerogenic dendritic cell (DC) phenotypes. We show here that leukocytes from lupus-prone mice and SLE patients express diminished β-catenin transcriptional activity, particularly in myeloid cells, although other leukocytes revealed similar trends. Serum levels of DKK-1, an inhibitor under transcriptional control of Wnt/β-catenin, were also decreased in lupus-prone mice. Surprisingly, however, preemptive deletion of β-catenin from macrophages appears to have no effect on lupus development, even in mice with varying genetic loads for lupus. Although myeloid-specific loss of β-catenin does not seem to be important for lupus development, the potential role of this transcription factor in other leukocytes and renal cells remain to be elucidated.

  8. Leukocyte Beta-Catenin Expression Is Disturbed in Systemic Lupus Erythematosus

    PubMed Central

    Orme, Jacob J.; Du, Yong; Vanarsa, Kamala; Wu, Tianfu; Satterthwaite, Anne B.

    2016-01-01

    Wnt/β-catenin signaling is relatively understudied in immunity and autoimmunity. β-catenin blocks inflammatory mediators and favors tolerogenic dendritic cell (DC) phenotypes. We show here that leukocytes from lupus-prone mice and SLE patients express diminished β-catenin transcriptional activity, particularly in myeloid cells, although other leukocytes revealed similar trends. Serum levels of DKK-1, an inhibitor under transcriptional control of Wnt/β-catenin, were also decreased in lupus-prone mice. Surprisingly, however, preemptive deletion of β-catenin from macrophages appears to have no effect on lupus development, even in mice with varying genetic loads for lupus. Although myeloid-specific loss of β-catenin does not seem to be important for lupus development, the potential role of this transcription factor in other leukocytes and renal cells remain to be elucidated. PMID:27548498

  9. Multinuclear giant cell formation is enhanced by down-regulation of Wnt signaling in gastric cancer cell line, AGS

    SciTech Connect

    Kim, Shi-Mun; Kim, Rockki; Ryu, Jae-Hyun; Jho, Eek-Hoon; Song, Ki-Joon; Jang, Shyh-Ing; Kee, Sun-Ho . E-mail: keesh@korea.ac.kr

    2005-08-01

    AGS cells, which were derived from malignant gastric adenocarcinoma tissue, lack E-cadherin-mediated cell adhesion but have a high level of nuclear {beta}-catenin, which suggests altered Wnt signal. In addition, approximately 5% of AGS cells form multinuclear giant cells in the routine culture conditions, while taxol treatment causes most AGS cells to become giant cells. The observation of reduced nuclear {beta}-catenin levels in giant cells induced by taxol treatment prompted us to investigate the relationship between Wnt signaling and giant cell formation. After overnight serum starvation, the shape of AGS cells became flattened, and this morphological change was accompanied by decrease in Myc expression and an increase in the giant cell population. Lithium chloride treatment, which inhibits GSK3{beta} activity, reversed these serum starvation effects, which suggests an inverse relationship between Wnt signaling and giant cell formation. Furthermore, the down-regulation of Wnt signaling caused by the over-expression of ICAT, E-cadherin, and Axin enhanced giant cell formation. Therefore, down-regulation of Wnt signaling may be related to giant cell formation, which is considered to be a survival mechanism against induced cell death.

  10. Next-generation sequencing is highly sensitive for the detection of beta-catenin mutations in desmoid-type fibromatoses.

    PubMed

    Aitken, Sarah J; Presneau, Nadège; Kalimuthu, Sangeetha; Dileo, Palma; Berisha, Fitim; Tirabosco, Roberto; Amary, M Fernanda; Flanagan, Adrienne M

    2015-08-01

    Desmoid-type fibromatoses are locally aggressive and frequently recurrent tumours, and an accurate diagnosis is essential for patient management. The majority of sporadic lesions harbour beta-catenin (CTNNB1) mutations. We used next-generation sequencing to detect CTNNB1 mutations and to compare the sensitivity and specificity of next-generation sequencing with currently employed mutation detection techniques: mutation-specific restriction enzyme digestion and polymerase chain reaction amplification. DNA was extracted from formalin-fixed paraffin-embedded needle biopsy or resection tissue sections from 144 patients with sporadic desmoid-type fibromatoses, four patients with syndrome-related desmoid-type fibromatoses and 11 morphological mimics. Two primer pairs were designed for CTNNB1 mutation hotspots. Using ≥10 ng of DNA, libraries were generated by Fluidigm and sequenced on the Ion Torrent Personal Genome Machine. Next-generation sequencing had a sensitivity of 92.36 % (133/144, 95 % CIs: 86.74 to 96.12 %) and a specificity of 100 % for the detection of CTNNB1 mutations in desmoid-type fibromatoses-like spindle cell lesions. All mutations detected by mutation-specific restriction enzyme digestion were identified by next-generation sequencing. Next-generation sequencing identified additional mutations in 11 tumours that were not detected by mutation-specific restriction enzyme digestion, two of which have not been previously described. Next-generation sequencing is highly sensitive for the detection of CTNNB1 mutations. This multiplex assay has the advantage of detecting additional mutations compared to those detected by mutation-specific restriction enzyme digestion (sensitivity 82.41 %). The technology requires minimal DNA and is time- and cost-efficient.

  11. Second hit in cervical carcinogenesis process: involvement of wnt/beta catenin pathway

    PubMed Central

    Perez-Plasencia, Carlos; Duenas-Gonzalez, Alfonso; Alatorre-Tavera, Brenda

    2008-01-01

    The Human papillomavirus plays an important role in the initiation and progression of cervical cancer. However, it is a necessary but not sufficient cause to develop invasive carcinoma; hence, other factors are required in the pathogenesis of this malignancy. In this review we explore the hypothesis of the deregulation of wnt/β-catenin signaling pathway as a "second hit" required to develop cervical cancer. PMID:18606007

  12. The balance of TCF7L2 variants with differential activities in Wnt-signaling is regulated by lithium in a GSK3{beta}-independent manner

    SciTech Connect

    Struewing, Ian; Boyechko, Tania; Barnett, Corey; Beildeck, Marcy; Byers, Stephen W.; Mao, Catherine D.

    2010-08-20

    Research highlights: {yields} Identification of a novel effect of lithium on the expression of TCF7L2 RNA isoforms and protein variants. {yields} The extent of lithium-induced TCF7L2 form switch mirrors cell responsiveness to Wnt/{beta}-catenin signaling. {yields} Demonstration that lithium has dual GSK3{beta}-dependent and -independent effects on TCF7L2 expression. {yields} Demonstration that TCF7L2 expression is repressed by the transcriptionally active TCF7L2E form. {yields} Evidence for a lithium-induced de-repression mechanism of TCF7L2 expression via TCF7L2 variant switch. -- Abstract: TCF7L2 transcription factor is a downstream effector of the canonical Wnt/{beta}-catenin signaling, which controls cell fate and homeostasis. However, the complexity of TCF7L2 expression with numerous mRNA isoforms coding for proteins with distinct N- and C-termini allows variability in TCF7L2 functions and regulations. Here, we show that although TCF7L2 mRNA isoforms distinguish fetal, immortalized and adult differentiated endothelial cells (EC), they cannot explain the lack of significant {beta}-catenin/TCF7 activities in ECs. Lithium, a Wnt-signaling activator, increases TCF7L2 mRNA levels and induces an RNA isoform switch favoring the expression of TCF7L2-short forms lacking the C-termini domains. Although the latter occurs in different cell types, its extent depends on the overall increase of TCF7L2 transcription, which correlates with cell responsiveness to Wnt/{beta}-catenin signaling. While GSK3{beta} down-regulation increases TCF7L2 expression, there is no concomitant change in TCF7L2 mRNA isoforms, which demonstrate the dual effects of lithium on TCF7L2 expression via a GSK3{beta}-dependent up-regulation and a GSK3{beta}-independent modulation of RNA splicing. TCF7L2E-long forms display a repressor activity on TCF7L2-promoter reporters and lithium induces a decrease of the endogenous TCF7L2 forms bound to native TCF7L2-promoter chromatin at two novel distal TCF7

  13. Alterations of the Wnt/beta-catenin pathway and its target genes for the N- and C-terminal domains of parathyroid hormone-related protein in bone from diabetic mice.

    PubMed

    Portal-Núñez, S; Lozano, D; de Castro, L Fernández; de Gortázar, A R; Nogués, X; Esbrit, P

    2010-07-16

    Type 1 diabetes mellitus (T1D) is associated with bone loss. Given that the Wnt/beta-catenin pathway is a major regulator of bone accrual, we assessed this pathway in mice with streptozotozin-induced T1D. In diabetic mouse long bones, we found alterations favouring the suppression of this pathway by using PCR arrays and beta-catenin immunostaining. Downregulation of sclerostin, an inhibitor of this pathway, also occurred, and related to increased osteocyte apoptosis. Our data show that both N- and C-terminal parathyroid hormone-related peptide fragments might exert osteogenic effects in this setting by targeting several genes of this pathway and increasing beta-catenin in osteoblastic cells.

  14. Beta-Catenin and Plakoglobin Expression during Zebrafish Tooth Development and Replacement.

    PubMed

    Verstraeten, Barbara; van Hengel, Jolanda; Huysseune, Ann

    2016-01-01

    We analyzed the protein distribution of two cadherin-associated molecules, plakoglobin and β-catenin, during the different stages of tooth development and tooth replacement in zebrafish. Plakoglobin was detected at the plasma membrane already at the onset of tooth development in the epithelial cells of the tooth. This pattern remained unaltered during further tooth development. The mesenchymal cells only showed plakoglobin from cytodifferentiation onwards. Plakoglobin 1a morpholino-injected embryos showed normal tooth development with proper initiation and differentiation. Although plakoglobin is clearly present during normal odontogenesis, the loss of plakoglobin 1a does not influence tooth development. β-catenin was found at the cell borders of all cells of the successional lamina but also in the nuclei of surrounding mesenchymal cells. Only membranous, not nuclear, β-catenin, was found during morphogenesis stage. However, during cytodifferentiation stage, both nuclear and membrane-bound β-catenin was detected in the layers of the enamel organ as well as in the differentiating odontoblasts. Nuclear β-catenin is an indication of an activated Wnt pathway, therefore suggesting a possible role for Wnt signalling during zebrafish tooth development and replacement.

  15. Beta-Catenin and Plakoglobin Expression during Zebrafish Tooth Development and Replacement

    PubMed Central

    Verstraeten, Barbara; van Hengel, Jolanda; Huysseune, Ann

    2016-01-01

    We analyzed the protein distribution of two cadherin-associated molecules, plakoglobin and β-catenin, during the different stages of tooth development and tooth replacement in zebrafish. Plakoglobin was detected at the plasma membrane already at the onset of tooth development in the epithelial cells of the tooth. This pattern remained unaltered during further tooth development. The mesenchymal cells only showed plakoglobin from cytodifferentiation onwards. Plakoglobin 1a morpholino-injected embryos showed normal tooth development with proper initiation and differentiation. Although plakoglobin is clearly present during normal odontogenesis, the loss of plakoglobin 1a does not influence tooth development. β-catenin was found at the cell borders of all cells of the successional lamina but also in the nuclei of surrounding mesenchymal cells. Only membranous, not nuclear, β-catenin, was found during morphogenesis stage. However, during cytodifferentiation stage, both nuclear and membrane-bound β-catenin was detected in the layers of the enamel organ as well as in the differentiating odontoblasts. Nuclear β-catenin is an indication of an activated Wnt pathway, therefore suggesting a possible role for Wnt signalling during zebrafish tooth development and replacement. PMID:26938059

  16. Molecular genetic alterations in endometrioid carcinomas of the ovary: similar frequency of beta-catenin abnormalities but lower rate of microsatellite instability and PTEN alterations than in uterine endometrioid carcinomas.

    PubMed

    Catasús, Lluis; Bussaglia, Elena; Rodrguez, Ingrid; Gallardo, Alberto; Pons, Cristina; Irving, Julie A; Prat, Jaime

    2004-11-01

    Endometrioid carcinomas of the ovary closely resemble their uterine counterparts. It has been suggested that the former tumors have the same molecular alterations (microsatellite instability [MSI], PTEN, and beta-catenin) described in endometrioid carcinomas of the uterus. We analyzed 55 ovarian carcinomas, including 22 endometrioid, 18 clear cell, and 15 mixed types. MSI was detected in 5 of 39 cases (13%). MLH1 promoter hypermethylation was identified in 2 of the 5 MSI-positive tumors. PTEN was mutated in 5 of 54 cases (9%); of these, 3 had MSI and exhibited frameshift mutations in short-coding mononucleotide repeats. Beta-catenin nuclear expression was detected in 11 of 54 cases (20%) by immunostaining; of these, 7 exhibited CTNNB1 gene mutations. These alterations were found more frequently in endometrioid carcinomas than in tumors of the other 2 groups. Among the former tumors, MSI was detected in 3 of 17 cases (17.5%); PTEN mutations, in 3 of 21 (14%); and beta-catenin, in 8 of 21 (38%). The molecular alterations were found more often in tumors associated with endometriosis than in tumors without endometriosis. Six endometrioid tumors demonstrating matrix metalloproteinase-7 (MMP-7) immunoreactivity with nuclear accumulation of beta-catenin had good outcomes, in contrast to poor outcomes in 7 of 9 predominantly nonendometrioid tumors demonstrating expression of MMP-7 only. We found a similar frequency of beta-catenin abnormalities but lower rates of MSI and PTEN alterations than in uterine endometrioid carcinomas. Alterations in beta-catenin and PTEN genes, as well as MSI, are frequent in low-stage ovarian carcinomas of endometrioid type that have a favorable prognosis.

  17. R-Spondin 1/Dickkopf-1/Beta-Catenin Machinery Is Involved in Testicular Embryonic Angiogenesis

    PubMed Central

    Caruso, Maria; Ferranti, Francesca; Corano Scheri, Katia; Dobrowolny, Gabriella; Ciccarone, Fabio; Grammatico, Paola

    2015-01-01

    Testicular vasculogenesis is one of the key processes regulating male gonad morphogenesis. The knowledge of the molecular cues underlining this phenomenon is one of today’s most challenging issues and could represent a major contribution toward a better understanding of the onset of testicular morphogenetic disorders. R-spondin 1 has been clearly established as a candidate for mammalian ovary determination. Conversely, very little information is available on the expression and role of R-spondin 1 during testicular morphogenesis. This study aims to clarify the distribution pattern of R-spondin 1 and other partners of its machinery during the entire period of testicular morphogenesis and to indicate the role of this system in testicular development. Our whole mount immunofluorescence results clearly demonstrate that R-spondin 1 is always detectable in the testicular coelomic partition, where testicular vasculature is organized, while Dickkopf-1 is never detectable in this area. Moreover, organ culture experiments of embryonic male UGRs demonstrated that Dickkopf-1 acted as an inhibitor of testis vasculature formation. Consistent with this observation, real-time PCR analyses demonstrated that DKK1 is able to slightly but significantly decrease the expression level of the endothelial marker Pecam1. The latter experiments allowed us to observe that DKK1 administration also perturbs the expression level of the Pdgf-b chain, which is consistent with some authors’ observations relating this factor with prenatal testicular patterning and angiogenesis. Interestingly, the DKK1 induced inhibition of testicular angiogenesis was rescued by the co-administration of R-spondin 1. In addition, R-spondin 1 alone was sufficient to enhance, in culture, testicular angiogenesis. PMID:25910078

  18. Beta-Catenin Regulated ALDH1A1 is a Target in Ovarian Cancer Spheroids

    PubMed Central

    Condello, Salvatore; Morgan, Cynthia A.; Nagdas, Sarbajeet; Cao, Liyun; Turek, John; Hurley, Thomas D.; Matei, Daniela

    2014-01-01

    Cancer cells form three dimensional (3D) multicellular aggregates (or spheroids) under non-adherent culture conditions. In ovarian cancer (OC), spheroids serve as a vehicle for cancer cell dissemination in the peritoneal cavity, protecting cells from environmental stress-induced anoikis. To identify new targetable molecules in OC spheroids, we investigated gene expression profiles and networks upregulated in three dimensional (3D) versus traditional monolayer culture conditions. We identified ALDH1A1, a cancer stem cell marker as being overexpressed in OC spheroids and directly connected to key elements of the β-catenin pathway. B-catenin function and ALDH1A1 expression were increased in OC spheroids vs. monolayers and in successive spheroid generations, suggesting that 3D aggregates are enriched in cells with stem cell characteristics. B-catenin knockdown decreased ALDH1A1 expression levels and β-catenin coimmunoprecipitated with the ALDH1A1 promoter, suggesting that ALDH1A1 is a direct β-catenin target. Both siRNA mediated β-catenin knockdown and A37, a novel ALDH1A1 small molecule enzymatic inhibitor described here for the first time, disrupted OC spheroid formation and cell viability (p<0.001). B-catenin knockdown blocked tumor growth and peritoneal metastasis in an OC xenograft model. These data strongly support the role of β-catenin regulated ALDH1A1 in the maintenance of OC spheroids and propose new ALDH1A1 inhibitors targeting this cell population. PMID:24954508

  19. Collagen type I may influence the expression of E-cadherin and beta-catenin in carcinoma ex-pleomorphic adenoma.

    PubMed

    Araújo, Vera C; Demasi, Ana Paula Dias; Furuse, Cristiane; Altemani, Albina; Alves, Venâncio A; Freitas, Leandro L; Araújo, Ney S

    2009-07-01

    Carcinoma ex-pleomorphic adenoma (CXPA) is an aggressive salivary gland malignancy, usually derived from a long-standing or a recurrent benign tumor, the pleomorphic adenoma (PA). In the context of dynamic reciprocity, changes in the composition and structure of extracellular matrix proteins and cell surface receptors have been frequently associated with dysfunctional adhesion and invasive behavior of tumor cells. It is not fully understood if these changes are involved in the conversion of PA to CXPA. In this study, different progression stages of CXPA were investigated regarding the expression of the major extracellular matrix proteins, collagen type I, and of E-cadherin and beta-catenin, the components of adherens junctions. By immunohistochemical analysis, we have demonstrated that direct contact of tumor cells with fibrillar type I collagen, particularly near the invasive front and in invasive areas prevailing small nests of CXPA cells, could be associated with reduced expression of the E-cadherin and beta-catenin adhesion molecules and with invasive behavior of epithelial, but not of CXPA with myoepithelial component. Our results also suggested that this association could depend on the organization of collagen molecules, being prevented by high-order polymeric structures. These findings could implicate the local microenvironment in the transition from the premalignant PA to invasive CXPA.

  20. Loss of epithelial differentiation and gain of invasiveness correlates with tyrosine phosphorylation of the E-cadherin/beta-catenin complex in cells transformed with a temperature-sensitive v-SRC gene

    PubMed Central

    1993-01-01

    Loss of histotypic organization of epithelial cells is a common feature in normal development as well as in the invasion of carcinomas. Here we show that the v-src oncogene is a potent effector of epithelial differentiation and invasiveness. MDCK epithelial cells transformed with a temperature-sensitive mutant of v-src exhibit a strictly epithelial phenotype at the nonpermissive temperature for pp60v-src activity (40.5 degrees C) but rapidly loose cell-to-cell contacts and acquire a fibroblast-like morphology after culture at the permissive temperature (35 degrees C). Furthermore, the invasiveness of the cells into collagen gels or into chick heart fragments was increased at the permissive temperature. The profound effects of v-src on intercellular adhesion were not linked to changes in the levels of expression of the epithelial cell adhesion molecule E-cadherin. Rather, we observed an increase in tyrosine phosphorylation of E-cadherin and, in particular, of the associated protein beta-catenin. These results suggest a mechanism by which v-src counteracts junctional assembly and thereby promotes invasiveness and dedifferentiation of epithelial cells through phosphorylation of the E-cadherin/catenin complex. PMID:8425900

  1. Suppression of wnt /beta-catenin signaling in bone of female rats exposed to ethanol post-lactation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chronic alcohol abuse is a major risk factor for development of osteoporosis. However, the mechanisms through which chronic alcohol intake induces bone loss remain unclear. Alcohol-induced oxidative stress might be the key event in tissue injury. In this report, we chronically infused EtOH (12g/kg/d...

  2. Dietary induced serum phenolic acids promote bone growth via p38 MAPK / Beta-Catenin Canonical Wnt signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diet and nutritional status are critical factors that influences bone development. In this report, we demonstrate that a mixture of phenolic acids found in the serum of young rats fed blueberries (BB), significantly stimulated osteoblast differentiation, resulting in significantly increased bone mas...

  3. Determination of the Role of CBP- and p300-Mediated Wnt Signaling on Colonic Cells

    PubMed Central

    Lazarova, Darina Lazarova

    2016-01-01

    Background The Wnt signaling pathway, mediated through active beta-catenin, is responsible for initiating the majority of cases of human colorectal cancer (CRC), and we have previously shown that hyperactivation of this pathway by histone deacetylase inhibitors (HDACis), such as butyrate, can induce the death of CRC cells. An important cellular switch that mediates the effects of Wnt-signaling activation is variation in the association between beta-catenin and the transcriptional coactivators cAMP response element binding (CREB) binding protein (CBP) and p300. Association of CBP with beta-catenin is thought to activate a set of genes linked to cell proliferation, while the p300-mediated Wnt genetic program is believed to promote cell differentiation. Small molecule agents have been discovered that modulate CBP/p300 Wnt transcriptional programs by altering the association of CBP and p300 to beta-catenin. ICG-001 and ICG-427 inhibit CBP- and p300-mediated Wnt activity, respectively, while IQ-1 prevents the shift from CBP-mediated to a p300-mediated Wnt activity. Objective Aim 1 of this proposal is designed to determine the role of CBP- and p300-mediated Wnt signaling in the response of CRC cells to HDACis. Aim 2 is to determine the role of CBP and p300 in the maintenance of high- and low-Wnt fractions in CRC cell line. Aim 3 will compare the effects of CBP- and p300-mediated Wnt activity on CRC initiation and progression. Methods In Aim 1, cells will be cotreated with HDACis and ICG-001, ICG-427, or IQ-1 and the levels of Wnt activity, apoptosis, proliferation, differentiation, and CBP- or p300-beta-catenin binding measured. Aim 2 of this proposal may mirror similar heterogeneity observed in human tumors and which may be of clinical significance. Aim 3 will use CRC cell line model systems of initiation and progression: the normal colon cell lines CCD-841CoN, the adenoma line LT97, the primary colon carcinoma cell line SW480, and the lymph node metastasis cell line SW

  4. The effects of dickkopf 1 on gene expression and Wnt signaling by melanocytes: mechanisms underlying its suppression of melanocyte function and proliferation.

    PubMed

    Yamaguchi, Yuji; Passeron, Thierry; Watabe, Hidenori; Yasumoto, Ken-ichi; Rouzaud, Francois; Hoashi, Toshihiko; Hearing, Vincent J

    2007-05-01

    Dickkopf 1 (DKK1), which is expressed at high mRNA levels by fibroblasts in the dermis of human skin on the palms and soles, inhibits the function and proliferation of melanocytes in the epidermis of those areas via the suppression of beta-catenin and microphthalmia-associated transcription factor (MITF). In this study, we investigated the protein expression levels of DKK1 between palmoplantar and non-palmoplantar areas and the effects of DKK1 on melanocyte gene expression profiles and on Wnt signaling pathways using DNA microarray technology, reverse transcriptase-PCR, Western blot, 3-dimensional reconstructed skin, immunocytochemistry, and immunohistochemistry. DKK1-responsive genes included those encoding proteins involved in the regulation of melanocyte development, growth, differentiation, and apoptosis (including Kremen 1, G-coupled receptor 51, lipoprotein receptor-related protein 6, low-density lipoprotein receptor, tumor necrosis factor receptor super-family 10, growth arrest and DNA-damage-inducible gene 45beta, and MITF). Of special interest was the rapid decrease in expression of MITF in melanocytes treated with DKK1, which is concurrent with the decreased activities of beta-catenin and of glucose-synthase kinase 3beta via phosphorylation at Ser9 and with the upregulated expression of protein kinase C alpha. These results further clarify the mechanism by which DKK1 suppresses melanocyte density and differentiation, and help explain why DKK1-rich palmoplantar epidermis is paler than non-palmoplantar epidermis via mesenchymal-epithelial interactions.

  5. Glucagon Like Peptide-1 Promotes Adipocyte Differentiation via the Wnt4 Mediated Sequestering of Beta-Catenin.

    PubMed

    Liu, Rui; Li, Na; Lin, Yi; Wang, Mei; Peng, Yongde; Lewi, Keidren; Wang, Qinghua

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) plays a role in the regulation of adipogenesis; however, the precise underlying molecular mechanism has not been fully defined. Wnt was recently identified as an important regulator of adipogenesis. This study aimed to investigate the involvement of the Wnt signaling pathway in the effects of GLP-1 on adipocyte differentiation. 3T3-L1 cells were induced to differentiate. The changes in the expression levels of adipogenic transcription factors and Wnts and the phosphorylation level and subcellular localization of β-catenin were quantified after GLP-1 treatment. GLP-1 stimulated adipocyte differentiation and lipid accumulation, which were accompanied by the expression of adipocyte marker genes. The expression of Wnt4 was upregulated in the process of adipocyte differentiation, which was further enhanced by treatment with GLP-1. β-catenin, an important mediator of the Wnt pathway, was immediately dephosphorylated and translocated from cytoplasm to nucleus when differentiation was induced. In the presence of GLP-1, however, β-catenin was redirected to the cell plasma membrane leading to its decreased accumulation in the nucleus. Knockdown of Wnt4 blocked the effect of GLP-1 on the cellular localization of β-catenin and expression level of adipogenic transcription factors. Our findings showed that GLP-1 promoted adipogenesis through the modulation of the Wnt4/β-catenin signaling pathway, suggesting that the GLP-1-Wntβ-catenin system might be a new target for the treatment of metabolic disease. PMID:27504979

  6. Glucagon Like Peptide-1 Promotes Adipocyte Differentiation via the Wnt4 Mediated Sequestering of Beta-Catenin

    PubMed Central

    Liu, Rui; Li, Na; Lin, Yi; Wang, Mei; Peng, Yongde; Lewi, Keidren; Wang, Qinghua

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) plays a role in the regulation of adipogenesis; however, the precise underlying molecular mechanism has not been fully defined. Wnt was recently identified as an important regulator of adipogenesis. This study aimed to investigate the involvement of the Wnt signaling pathway in the effects of GLP-1 on adipocyte differentiation. 3T3-L1 cells were induced to differentiate. The changes in the expression levels of adipogenic transcription factors and Wnts and the phosphorylation level and subcellular localization of β-catenin were quantified after GLP-1 treatment. GLP-1 stimulated adipocyte differentiation and lipid accumulation, which were accompanied by the expression of adipocyte marker genes. The expression of Wnt4 was upregulated in the process of adipocyte differentiation, which was further enhanced by treatment with GLP-1. β-catenin, an important mediator of the Wnt pathway, was immediately dephosphorylated and translocated from cytoplasm to nucleus when differentiation was induced. In the presence of GLP-1, however, β-catenin was redirected to the cell plasma membrane leading to its decreased accumulation in the nucleus. Knockdown of Wnt4 blocked the effect of GLP-1 on the cellular localization of β-catenin and expression level of adipogenic transcription factors. Our findings showed that GLP-1 promoted adipogenesis through the modulation of the Wnt4/β-catenin signaling pathway, suggesting that the GLP-1-Wntβ-catenin system might be a new target for the treatment of metabolic disease. PMID:27504979

  7. Human I-mfa domain proteins specifically interact with KSHV LANA and affect its regulation of Wnt signaling-dependent transcription

    SciTech Connect

    Kusano, Shuichi; Eizuru, Yoshito

    2010-06-04

    Kaposi's sarcoma-associated herpes virus (KSHV)-encoded latency-associated nuclear antigen (LANA) protein has been reported to interact with glycogen synthase kinase 3{beta} (GSK-3{beta}) and to negatively regulate its activity, leading to stimulation of GSK-3{beta}-dependent {beta}-catenin degradation. We show here that the I-mfa domain proteins, HIC (human I-mfa domain-containing protein) and I-mfa (inhibitor of MyoD family a), interacted in vivo with LANA through their C-terminal I-mfa domains. This interaction affected the intracellular localization of HIC, inhibited the LANA-dependent transactivation of a {beta}-catenin-regulated reporter construct, and decreased the level of the LANA.GSK-3{beta} complex. These data reveal for the first time that I-mfa domain proteins interact with LANA and negatively regulate LANA-mediated activation of Wnt signaling-dependent transcription by inhibiting the formation of the LANA.GSK-3{beta} complex.

  8. A Method for Serial Tissue Processing and Parallel Analysis of Aberrant Crypt Morphology, Mucin Depletion, and Beta-Catenin Staining in an Experimental Model of Colon Carcinogenesis

    PubMed Central

    2010-01-01

    The use of architectural and morphological characteristics of cells for establishing prognostic indicators by which individual pathologies are assigned grade and stage is a well-accepted practice. Advances in automated micro- and macroscopic image acquisition and digital image analysis have created new opportunities in the field of prognostic assessment; but, one area in experimental pathology, animal models for colon cancer, has not taken advantage of these opportunities. This situation is primarily due to the methods available to evaluate the colon of the rodent for the presence of premalignant and malignant pathologies. We report a new method for the excision and processing of the entire colon of the rat and illustrate how this procedure permitted the quantitative assessment of aberrant crypt foci (ACF), a premalignant colon pathology, for characteristics consistent with progression to malignancy. ACF were detected by methylene blue staining and subjected to quantitative morphometric analysis. Colons were then restained with high iron diamine–alcian blue for assessment of mucin depletion using an image overlay to associate morphometric data with mucin depletion. The subsequent evaluation of ACF for beta-catenin staining is also demonstrated. The methods described are particularly relevant to the screening of compounds for cancer chemopreventive activity. PMID:21406072

  9. Sfrp1, Sfrp2, and Sfrp5 regulate the Wnt/beta-catenin and the planar cell polarity pathways during early trunk formation in mouse.

    PubMed

    Satoh, Wataru; Matsuyama, Makoto; Takemura, Hiromasa; Aizawa, Shinichi; Shimono, Akihiko

    2008-02-01

    Sfrp is a secreted Wnt antagonist that directly interacts with Wnt ligand. We show here that inactivation of Sfrp1, Sfrp2, and Sfrp5 leads to fused somites formation in early-somite mouse embryos, simultaneously resulting in defective convergent extension (CE), which causes severe shortening of the anteroposterior axis. These observations indicate the redundant roles of Sfrp1, Sfrp2, and Sfrp5 in early trunk formation. The roles of the Sfrps were genetically distinguished in terms of the regulation of Wnt pathways. Genetic analysis combining Sfrps mutants and Loop-tail mice revealed the involvement of Sfrps in CE through the regulation of the planar cell polarity pathway. Furthermore, Dkk1-deficient embryos carrying Sfrp1 homozygous and Sfrp2 heterozygous mutations display irregular somites and indistinct intersomitic boundaries, which indicates that Sfrps-mediated inhibition of the Wnt/beta-catenin pathway is necessary for somitogenesis. Our results suggest that Sfrps regulation of the canonical and noncanonical pathways is essential for proper trunk formation. PMID:18257070

  10. Canonical Wnt signaling maintains the quiescent stage of hepatic stellate cells

    SciTech Connect

    Kordes, Claus Sawitza, Iris; Haeussinger, Dieter

    2008-02-29

    It is well known that hepatic stellate cells (HSC) develop into cells, which are thought to contribute to liver fibrogenesis. Recent data suggest that HSC are progenitor cells with the capacity to differentiate into cells of endothelial and hepatocyte lineages. The present study shows that {beta}-catenin-dependent canonical Wnt signaling is active in freshly isolated HSC of rats. Mimicking of the canonical Wnt pathway in cultured HSC by TWS119, an inhibitor of the glycogen synthase kinase 3{beta}, led to reduced {beta}-catenin phosphorylation, induced nuclear translocation of {beta}-catenin, elevated glutamine synthetase production, impeded synthesis of {alpha}-smooth muscle actin and Wnt5a, but promoted the expression of glial fibrillary acidic protein, Wnt10b, and paired-like homeodomain transcription factor 2c. In addition, canonical Wnt signaling lowered DNA synthesis and hindered HSC from entering the cell cycle. The findings demonstrate that {beta}-catenin-dependent Wnt signaling maintains the quiescent state of HSC and, similar to stem and progenitor cells, influences their developmental fate.

  11. A Nexus Consisting of Beta-Catenin and Stat3 Attenuates BRAF Inhibitor Efficacy and Mediates Acquired Resistance to Vemurafenib.

    PubMed

    Sinnberg, Tobias; Makino, Elena; Krueger, Marcel A; Velic, Ana; Macek, Boris; Rothbauer, Ulrich; Groll, Nicola; Pötz, Oliver; Czemmel, Stefan; Niessner, Heike; Meier, Friedegund; Ikenberg, Kristian; Garbe, Claus; Schittek, Birgit

    2016-06-01

    Acquired resistance to second generation BRAF inhibitors (BRAFis), like vemurafenib is limiting the benefits of long term targeted therapy for patients with malignant melanomas that harbor BRAF V600 mutations. Since many resistance mechanisms have been described, most of them causing a hyperactivation of the MAPK- or PI3K/AKT signaling pathways, one potential strategy to overcome BRAFi resistance in melanoma cells would be to target important common signaling nodes. Known factors that cause secondary resistance include the overexpression of receptor tyrosine kinases (RTKs), alternative splicing of BRAF or the occurrence of novel mutations in MEK1 or NRAS. In this study we show that β-catenin is stabilized and translocated to the nucleus in approximately half of the melanomas that were analyzed and which developed secondary resistance towards BRAFi. We further demonstrate that β-catenin is involved in the mediation of resistance towards vemurafenib in vitro and in vivo. Unexpectedly, β-catenin acts mainly independent of the TCF/LEF dependent canonical Wnt-signaling pathway in resistance development, which partly explains previous contradictory results about the role of β-catenin in melanoma progression and therapy resistance. We further demonstrate that β-catenin interacts with Stat3 after chronic vemurafenib treatment and both together cooperate in the acquisition and maintenance of resistance towards BRAFi. PMID:27428425

  12. Biphasic role of chondroitin sulfate in cardiac differentiation of embryonic stem cells through inhibition of Wnt/β-catenin signaling.

    PubMed

    Prinz, Robert D; Willis, Catherine M; van Kuppevelt, Toin H; Klüppel, Michael

    2014-01-01

    The glycosaminoglycan chondroitin sulfate is a critical component of proteoglycans on the cell surface and in the extracellular matrix. As such, chondroitin sulfate side chains and the sulfation balance of chondroitin play important roles in the control of signaling pathways, and have a functional importance in human disease. In contrast, very little is known about the roles of chondroitin sulfate molecules and sulfation patterns during mammalian development and cell lineage specification. Here, we report a novel biphasic role of chondroitin sulfate in the specification of the cardiac cell lineage during embryonic stem cell differentiation through modulation of Wnt/beta-catenin signaling. Lineage marker analysis demonstrates that enzymatic elimination of endogenous chondroitin sulfates leads to defects specifically in cardiac differentiation. This is accompanied by a reduction in the number of beating cardiac foci. Mechanistically, we show that endogenous chondroitin sulfate controls cardiac differentiation in a temporal biphasic manner through inhibition of the Wnt/beta-catenin pathway, a known regulatory pathway for the cardiac lineage. Treatment with a specific exogenous chondroitin sulfate, CS-E, could mimic these biphasic effects on cardiac differentiation and Wnt/beta-catenin signaling. These results establish chondroitin sulfate and its sulfation balance as important regulators of cardiac cell lineage decisions through control of the Wnt/beta-catenin pathway. Our work suggests that targeting the chondroitin biosynthesis and sulfation machinery is a novel promising avenue in regenerative strategies after heart injury.

  13. Evidence for the Nucleo-Apical Shuttling of a Beta-Catenin Like Plasmodium falciparum Armadillo Repeat Containing Protein

    PubMed Central

    Mitra, Pallabi; Gupta, Enna Dogra; Sahar, Tajali; Pandey, Alok K.; Dangi, Poonam; Reddy, K. Sony; Chauhan, Virander Singh; Gaur, Deepak

    2016-01-01

    Eukaryotic Armadillo (ARM) repeat proteins are multifaceted with prominent roles in cell-cell adhesion, cytoskeletal regulation and intracellular signaling among many others. One such ARM repeat containing protein, ARM Repeats Only (ARO), has recently been demonstrated in both Toxoplasma (TgARO) and Plasmodium (PfARO) parasites to be targeted to the rhoptries during the late asexual stages. TgARO has been implicated to play an important role in rhoptry positioning i.e. directing the rhoptry towards the apical end of the parasite. Here, we report for the first time that PfARO exhibits a DNA binding property and a dynamic sub-cellular localization between the nucleus (early schizont) and rhoptry (late schizont) during the different stages of the asexual blood-stage life cycle. PfARO possesses a putative nuclear export signal (NES) and the nucleo-apical shuttling was sensitive to Leptomycin B (LMB) suggesting that the nuclear export was mediated by CRM1. Importantly, PfARO specifically bound an A-T rich DNA sequence of the P. falciparum Gyrase A (PfgyrA) gene, suggesting that the DNA binding specificity of PfARO is likely due to the AT-richness of the probe. This is a novel functional characteristic that has not been reported previously for any P. falciparum ARM containing protein and suggests a putative role for PfARO in gene regulation. This study describes for the first time a conserved P. falciparum ARM repeat protein with a high degree of functional versatility. PMID:26828945

  14. Evidence for the Nucleo-Apical Shuttling of a Beta-Catenin Like Plasmodium falciparum Armadillo Repeat Containing Protein.

    PubMed

    Mitra, Pallabi; Gupta, Enna Dogra; Sahar, Tajali; Pandey, Alok K; Dangi, Poonam; Reddy, K Sony; Chauhan, Virander Singh; Gaur, Deepak

    2016-01-01

    Eukaryotic Armadillo (ARM) repeat proteins are multifaceted with prominent roles in cell-cell adhesion, cytoskeletal regulation and intracellular signaling among many others. One such ARM repeat containing protein, ARM Repeats Only (ARO), has recently been demonstrated in both Toxoplasma (TgARO) and Plasmodium (PfARO) parasites to be targeted to the rhoptries during the late asexual stages. TgARO has been implicated to play an important role in rhoptry positioning i.e. directing the rhoptry towards the apical end of the parasite. Here, we report for the first time that PfARO exhibits a DNA binding property and a dynamic sub-cellular localization between the nucleus (early schizont) and rhoptry (late schizont) during the different stages of the asexual blood-stage life cycle. PfARO possesses a putative nuclear export signal (NES) and the nucleo-apical shuttling was sensitive to Leptomycin B (LMB) suggesting that the nuclear export was mediated by CRM1. Importantly, PfARO specifically bound an A-T rich DNA sequence of the P. falciparum Gyrase A (PfgyrA) gene, suggesting that the DNA binding specificity of PfARO is likely due to the AT-richness of the probe. This is a novel functional characteristic that has not been reported previously for any P. falciparum ARM containing protein and suggests a putative role for PfARO in gene regulation. This study describes for the first time a conserved P. falciparum ARM repeat protein with a high degree of functional versatility. PMID:26828945

  15. Klotho inhibits angiotensin II-induced cardiomyocyte hypertrophy through suppression of the AT1R/beta catenin pathway.

    PubMed

    Yu, Liangzhu; Meng, Wei; Ding, Jieqiong; Cheng, Menglin

    2016-04-29

    Myocardial hypertrophy is an independent risk factor for cardiac morbidity and mortality. The antiaging protein klotho reportedly possesses a protective role in cardiac diseases. However, the precise mechanisms underlying the cardioprotective effects of klotho remain unknown. This study was aimed to determine the effects of klotho on angiotensin II (Ang II)-induced hypertrophy in neonatal rat cardiomyocytes and the possible mechanism of actions. We found that klotho significantly inhibited Ang II-induced hypertrophic growth of neonatal cardiomyocytes, as evidenced by decreased [(3)H]-Leucine incorporation, cardiomyocyte surface area and β-myosin heavy chain (β-MHC) mRNA expression. Meanwhile, klotho inhibited Ang II-stimulated activation of the Wnt/β-catenin pathway in cardiomyocytes, as evidenced by decreased protein expression of active β-catenin, downregulated protein and mRNA expression of the β-catenin target genes c-myc and cyclin D1, and increased β-catenin phosphorylation. Inhibition of the Wnt/β-catenin pathway by the specific inhibitor XAV939 markedly attenuated Ang II-induced cardiomyocyte hypertrophy. The further study revealed that klotho treatment significantly downregulated protein expression of Ang II receptor type I (AT1R) but not type II (AT2R). The AT1R antagonist losartan inhibited Ang II-stimulated activation of the Wnt/β-catenin pathway and cardiomyocyte hypertrophy. Our findings suggest that klotho inhibits Ang II-induced cardiomyocyte hypertrophy through suppression of the AT1R/β-catenin signaling pathway, which may provide new insights into the mechanism underlying the protective effects of klotho in heart diseases, and raise the possibility that klotho may act as an endogenous antihypertrophic factor by inhibiting the Ang II signaling pathway. PMID:26970306

  16. Beta-catenin in disease

    PubMed Central

    Prakash, Sharada; Swaminathan, Uma; Nagamalini, BR; Krishnamurthy, Ashwini Balkuntla

    2016-01-01

    In continuation with the previous review on “β-catenin in health”, in this review we discuss the role of β-catenin in the pathogenesis of common oral lesions in the oral and maxillofacial region- oral potentially malignant disorders, their progression to oral squamous cell carcinoma, salivary gland tumors and odontogenic tumours. This review is based on a pubmed search of all the lesions included in the review. PMID:27601825

  17. Beta-catenin in disease

    PubMed Central

    Prakash, Sharada; Swaminathan, Uma; Nagamalini, BR; Krishnamurthy, Ashwini Balkuntla

    2016-01-01

    In continuation with the previous review on “β-catenin in health”, in this review we discuss the role of β-catenin in the pathogenesis of common oral lesions in the oral and maxillofacial region- oral potentially malignant disorders, their progression to oral squamous cell carcinoma, salivary gland tumors and odontogenic tumours. This review is based on a pubmed search of all the lesions included in the review.

  18. Beta-catenin in disease.

    PubMed

    Prakash, Sharada; Swaminathan, Uma; Nagamalini, B R; Krishnamurthy, Ashwini Balkuntla

    2016-01-01

    In continuation with the previous review on "β-catenin in health", in this review we discuss the role of β-catenin in the pathogenesis of common oral lesions in the oral and maxillofacial region- oral potentially malignant disorders, their progression to oral squamous cell carcinoma, salivary gland tumors and odontogenic tumours. This review is based on a pubmed search of all the lesions included in the review. PMID:27601825

  19. Integration of telencephalic Wnt and hedgehog signaling center activities by Foxg1.

    PubMed

    Danesin, Catherine; Peres, João N; Johansson, Marie; Snowden, Victoria; Cording, Amy; Papalopulu, Nancy; Houart, Corinne

    2009-04-01

    The forebrain is patterned along the dorsoventral (DV) axis by Sonic Hedgehog (Shh). However, previous studies have suggested the presence of an Shh-independent mechanism. Our study identifies Wnt/beta-catenin-activated from the telencephalic roof-as an Shh-independent pathway that is essential for telencephalic pallial (dorsal) specification during neurulation. We demonstrate that the transcription factor Foxg1 coordinates the activity of two signaling centers: Foxg1 is a key downstream effector of the Shh pathway during induction of subpallial (ventral) identity, and it inhibits Wnt/beta-catenin signaling through direct transcriptional repression of Wnt ligands. This inhibition restricts the dorsal Wnt signaling center to the roof plate and consequently limits pallial identities. Concomitantly to these roles, Foxg1 controls the formation of the compartment boundary between telencephalon and basal diencephalon. Altogether, these findings identify a key direct target of Foxg1, and uncover a simple molecular mechanism by which Foxg1 integrates two opposing signaling centers.

  20. Programming Body Composition in Offspring by Maternal Obesity Is Associated with Increased Adipogenesis and Decreased WNT/ Beta-Catenin Signaling in the Adipose Tissue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maternal obesity during pregnancy significantly influences the risk of obesity in the offspring. We recently demonstrated that maternal obesity at conception programs obesity in the offspring. Obese dam offspring when weaned on high-fat diets gain significantly greater body weight/adiposity (via NMR...

  1. A role for ethanol-induced oxidative stress in controlling lineage commitment of mesenchymal stromal cells through inhibition of wnt/beta-catenin signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mechanisms by which chronic ethanol intake induces bone loss remain unclear. In females, the skeletal response to ethanol varies depending on physiologic status (viz. cycling, pregnancy, lactation). Ethanol-induced oxidative stress appears to be a key event leading to skeletal toxicity. In the c...

  2. A crucial role for ethanol-induced oxidative stress in controlling lineage commitment of mesenchymal stromal cells through inhibition of wnt/beta-catenin signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Female skeletal responses to ethanol may vary depending on the physiologic status (viz. cycling, pregnancy, lactation). Nonetheless, ethanol-induced oxidative stress appears to be the key event leading to skeletal toxicity. In the current study, we chronically infused EtOH-containing liquid diets ...

  3. A crucial role for ethanol-induced oxidative stress in controlling lineage commitment of mesenchymal stromal cells through Inhibition of Wnt / Beta-catenin Signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mechanisms by which chronic ethanol intake induces bone loss remain largely unclear. Especially in females, skeletal response to ethanol may vary depending on the physiologic status (viz. cycling, pregnancy, lactation). Nonetheless, ethanol-induced oxidative stress appears to be the key event le...

  4. Colonic inflammation and enhanced-beta-catenin signaling accompany an increase of the Lachnospiraceae/Streptococcaceae in the hind gut of high-fat diet-fed mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumption of an obesigenic / high-fat (HF) diet is associated with an increase of inflammation-related colon cancer risk and may alter the gut microbiota. To test the hypothesis that a HF feeding accelerates inflammatory processes and changes gut microbiome composition, C57BL/6 mice were fed a HF ...

  5. Colonic inflammation and enhanced-beta-catenin signaling accompany an increase of the Lachnospiraceae/Streptococcaceae in the hind gut of high-fat diet-fed mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumption of an obesigenic / high-fat (HF) diet is associated with a high colon cancer risk, and may alter the gut microbiota. To test the hypothesis that a HF feeding accelerates inflammatory process and changes gut microbiome composition, C57BL/6 mice were fed a HF (45% energy) or low-fat (LF) (...

  6. Alcohol consumption promotes diethylnitrosamine-induced hepatocarcinogenesis in male mice through the activation of the Wnt/Beta-catenin signaling pathway

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although alcohol effects within the liver have been extensively studied, the complex mechanisms by which alcohol causes liver cancer are not well understood. It has been suggested that ethanol (EtOH) metabolism promotes tumor growth by increasing hepatocyte proliferation. In this study, we develop...

  7. WNT signaling controls expression of pro-apoptotic BOK and BAX in intestinal cancer

    SciTech Connect

    Zeilstra, Jurrit; Joosten, Sander P.J.; Wensveen, Felix M.; Dessing, Mark C.; Schuetze, Denise M.; Eldering, Eric; Spaargaren, Marcel; Pals, Steven T.

    2011-03-04

    Research highlights: {yields} Intestinal adenomas initiated by aberrant activation of the WNT pathway displayed an increased sensitivity to apoptosis. {yields} Expression profiling of apoptosis-related genes in Apc{sup Min/+} mice revealed the differential expression of pro-apoptotic Bok and Bax. {yields} APC-mutant adenomatous crypts in FAP patients showed strongly increased BAX immunoreactivity. {yields} Blocking of {beta}-catenin/TCF-4-mediated signaling in colon cancer cells reduced the expression of BOK and BAX. -- Abstract: In a majority of cases, colorectal cancer is initiated by aberrant activation of the WNT signaling pathway. Mutation of the genes encoding the WNT signaling components adenomatous polyposis coli or {beta}-catenin causes constitutively active {beta}-catenin/TCF-mediated transcription, driving the transformation of intestinal crypts to cancer precursor lesions, called dysplastic aberrant crypt foci. Deregulated apoptosis is a hallmark of adenomatous colon tissue. However, the contribution of WNT signaling to this process is not fully understood. We addressed this role by analyzing the rate of epithelial apoptosis in aberrant crypts and adenomas of the Apc{sup Min/+} mouse model. In comparison with normal crypts and adenomas, aberrant crypts displayed a dramatically increased rate of apoptotic cell death. Expression profiling of apoptosis-related genes along the crypt-villus axis and in Apc mutant adenomas revealed increased expression of two pro-apoptotic Bcl-2 family members in intestinal adenomas, Bok and Bax. Analysis of the colon of familial adenomatous polyposis (FAP) patients along the crypt-to-surface axis, and of dysplastic crypts, corroborated this expression pattern. Disruption of {beta}-catenin/TCF-4-mediated signaling in the colorectal cancer cell line Ls174T significantly decreased BOK and BAX expression, confirming WNT-dependent regulation in intestinal epithelial cells. Our results suggest a feedback mechanism by which

  8. Smad6 promotes neuronal differentiation in the intermediate zone of the dorsal neural tube by inhibition of the Wnt/beta-catenin pathway.

    PubMed

    Xie, Zhihui; Chen, Yongfeng; Li, Zhenfei; Bai, Ge; Zhu, Yue; Yan, Rui; Tan, Fangzhi; Chen, Ye-Guang; Guillemot, Francois; Li, Lin; Jing, Naihe

    2011-07-19

    Proliferation of the neural/neuronal progenitor cells (NPCs) at the ventricular zone of the dorsal spinal cord requires the stimuli of Wnt and bone morphogenic protein (BMP). However, how these two signaling pathways are regulated to initiate differentiation in the NPCs as they enter the intermediate zone is not known. Here, we show that Smad6, a negative regulator of BMP signaling, is expressed in the intermediate zone of the chick dorsal spinal cord. Knockdown experiments show that Smad6 is required for promoting NPCs to exit the cell cycle and differentiate into neurons. Although we find that Smad6 inhibits BMP signaling, as expected, we also find that Smad6 unexpectedly inhibits the Wnt/β-catenin pathway. The inhibition of the Wnt/β-catenin pathway by Smad6 is independent of its effect on the BMP pathway. Rather, Smad6 through its N-terminal domain and link region enhances the interaction of C-terminal binding protein with the β-catenin/T cell factor (TCF) complex and the TCF-binding element to inhibit β-catenin-mediated transcriptional activation. Our study provides evidence that transition of NPCs from a proliferative state to a differentiating state is controlled by the dual inhibitory role of Smad6 to both BMP and Wnt signaling at the level of transcription.

  9. MAP3K1 functionally interacts with Axin1 in the canonical Wnt signalling pathway.

    PubMed

    Sue Ng, Ser; Mahmoudi, Tokameh; Li, Vivian S W; Hatzis, Pantelis; Boersema, Paul J; Mohammed, Shabaz; Heck, Albert J; Clevers, Hans

    2010-01-01

    A central point of regulation in the Wnt/beta-catenin signalling pathway is the formation of the beta-catenin destruction complex. Axin1, an essential negative regulator of Wnt signalling, serves as a scaffold within this complex and is critical for rapid turnover of beta-catenin. To examine the mechanism by which Wnt signalling disables the destruction complex, we used an immunoprecipitation-coupled proteomics approach to identify novel endogenous binding partners of Axin1. We found mitogen-activated protein kinase kinase kinase 1 (MAP3K1) as an Axin1 interactor in Ls174T colorectal cancer (CRC) cells. Importantly, confirmation of this interaction in HEK293T cells indicated that the Axin1-MAP3K1 interaction is induced and modulated by Wnt stimulation. siRNA depletion of MAP3K1 specifically abrogated TCF/LEF-driven transcription and Wnt3A-driven endogenous gene expression in both HEK293T as well as DLD-1 CRC. Expression of ubiquitin ligase mutants of MAP3K1 abrogated TCF/LEF transcription, whereas kinase mutants had no effect in TCF-driven activity, highlighting the essential role of the MAP3K1 E3 ubiquitin ligase activity in regulation of the Wnt/beta-catenin pathway. These results suggest that MAP3K1, previously reported as an Axin1 inter-actor in c-Jun NH(2)-terminal kinase pathway, is also involved in the canonical Wnt signalling pathway and positively regulates expression of Wnt target genes. PMID:20128690

  10. Identifying the sea level signal: Surf's up

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    Of all the dire consequences of the greenhouse effect, global sea level rise is potentially the most destructive to human life and property. But the processes that increase the volume of the oceans are so poorly understood that theoreticians are taking their lead from scientists trying to actually measure current changes in sea level that might be caused by the greenhouse effect. As with surface temperature, precipitation, and other measures of climate change, identifying the greenhouse signal is a daunting problem.Climate models that predict mean temperature increases around the world of up to several degrees C in the next 50-100 years in response to human-induced global warming have given rise to a scientific consensus that mountain glaciers and ice sheets will begin to melt and the water in oceans will slightly expand, raising sea level. Such increases would inundate some of the most densely populated and highly cultivated areas on the planet, displacing and endangering many millions of people at a devastating economic and social cost.

  11. Effects of curcumin in pediatric epithelial liver tumors: inhibition of tumor growth and alpha-fetoprotein in vitro and in vivo involving the NFkappaB- and the beta-catenin pathways

    PubMed Central

    Bortel, Nicola; Armeanu-Ebinger, Sorin; Schmid, Evi; Kirchner, Bettina; Frank, Jan; Kocher, Alexa; Schiborr, Christina; Warmann, Steven; Fuchs, Jörg; Ellerkamp, Verena

    2015-01-01

    In children with hepatocellular carcinoma (pHCC) the 5-year overall survival rate is poor. Effects of cytostatic therapies such as cisplatin and doxorubicin are limited due to chemoresistance and tumor relapse. In adult HCC, several antitumor properties are described for the use of curcumin. Curcumin is one of the best-investigated phytochemicals in complementary oncology without relevant side effects. Its use is limited by low bioavailability. Little is known about the influence of curcumin on pediatric epithelial hepatic malignancies. We investigated the effects of curcumin in combination with cisplatin on two pediatric epithelial liver tumor cell lines. As mechanisms of action inhibition of NFkappaB, beta-catenin, and decrease of cyclin D were identified. Using a mouse xenograft model we could show a significant decrease of alpha-fetoprotein after combination therapy of oral micellar curcumin and cisplatin. Significant concentrations of curcuminoids were found in blood samples, organ lysates, and tumor tissue after oral micellar curcumin administration. Micellar curcumin in combination with cisplatin can be a promising strategy for treatment of pediatric HCC. PMID:26515460

  12. Effects of curcumin in pediatric epithelial liver tumors: inhibition of tumor growth and alpha-fetoprotein in vitro and in vivo involving the NFkappaB- and the beta-catenin pathways.

    PubMed

    Bortel, Nicola; Armeanu-Ebinger, Sorin; Schmid, Evi; Kirchner, Bettina; Frank, Jan; Kocher, Alexa; Schiborr, Christina; Warmann, Steven; Fuchs, Jörg; Ellerkamp, Verena

    2015-12-01

    In children with hepatocellular carcinoma (pHCC) the 5-year overall survival rate is poor. Effects of cytostatic therapies such as cisplatin and doxorubicin are limited due to chemoresistance and tumor relapse. In adult HCC, several antitumor properties are described for the use of curcumin. Curcumin is one of the best-investigated phytochemicals in complementary oncology without relevant side effects. Its use is limited by low bioavailability. Little is known about the influence of curcumin on pediatric epithelial hepatic malignancies. We investigated the effects of curcumin in combination with cisplatin on two pediatric epithelial liver tumor cell lines. As mechanisms of action inhibition of NFkappaB, beta-catenin, and decrease of cyclin D were identified. Using a mouse xenograft model we could show a significant decrease of alpha-fetoprotein after combination therapy of oral micellar curcumin and cisplatin. Significant concentrations of curcuminoids were found in blood samples, organ lysates, and tumor tissue after oral micellar curcumin administration. Micellar curcumin in combination with cisplatin can be a promising strategy for treatment of pediatric HCC.

  13. FGF signaling inhibitor, SPRY4, is evolutionarily conserved target of WNT signaling pathway in progenitor cells.

    PubMed

    Katoh, Yuriko; Katoh, Masaru

    2006-03-01

    WNT, FGF and Hedgehog signaling pathways network together during embryogenesis, tissue regeneration, and carcinogenesis. FGF16, FGF18, and FGF20 genes are targets of WNT-mediated TCF/LEF-beta-catenin-BCL9/BCL9L-PYGO transcriptional complex. SPROUTY (SPRY) and SPRED family genes encode inhibitors for receptor tyrosine kinase signaling cascades, such as those of FGF receptor family members and EGF receptor family members. Here, transcriptional regulation of SPRY1, SPRY2, SPRY3, SPRY4, SPRED1, SPRED2, and SPRED3 genes by WNT/beta-catenin signaling cascade was investigated by using bioinformatics and human intelligence (humint). Because double TCF/LEF-binding sites were identified within the 5'-promoter region of human SPRY4 gene, comparative genomics analyses on SPRY4 orthologs were further performed. SPRY4-FGF1 locus at human chromosome 5q31.3 and FGF2-NUDT6-SPATA5-SPRY1 locus at human chromosome 4q27-q28.1 were paralogous regions within the human genome. Chimpanzee SPRY4 gene was identified within NW_107083.1 genome sequence. Human, chimpanzee, rat and mouse SPRY4 orthologs, consisting of three exons, were well conserved. SPRY4 gene was identified as the evolutionarily conserved target of WNT/beta-catenin signaling pathway based on the conservation of double TCF/LEF-binding sites within 5'-promoter region of mammalian SPRY4 orthologs. Human SPRY4 mRNA was expressed in embryonic stem (ES) cells, brain, pancreatic islet, colon cancer, head and neck tumor, melanoma, and pancreatic cancer. WNT signaling activation in progenitor cells leads to the growth regulation of progenitor cells themselves through SPRY4 induction, and also to the growth stimulation of proliferating cells through FGF secretion. Epigenetic silencing and loss-of-function mutations of SPRY4 gene in progenitor cells could lead to carcinogenesis. SPRY4 is the pharmacogenomics target in the fields of oncology and regenerative medicine. PMID:16465403

  14. β-Catenin Signaling Biases Multipotent Lingual Epithelial Progenitors to Differentiate and Acquire Specific Taste Cell Fates.

    PubMed

    Gaillard, Dany; Xu, Mingang; Liu, Fei; Millar, Sarah E; Barlow, Linda A

    2015-05-01

    Continuous taste bud cell renewal is essential to maintain taste function in adults; however, the molecular mechanisms that regulate taste cell turnover are unknown. Using inducible Cre-lox technology, we show that activation of β-catenin signaling in multipotent lingual epithelial progenitors outside of taste buds diverts daughter cells from a general epithelial to a taste bud fate. Moreover, while taste buds comprise 3 morphological types, β-catenin activation drives overproduction of primarily glial-like Type I taste cells in both anterior fungiform (FF) and posterior circumvallate (CV) taste buds, with a small increase in Type II receptor cells for sweet, bitter and umami, but does not alter Type III sour detector cells. Beta-catenin activation in post-mitotic taste bud precursors likewise regulates cell differentiation; forced activation of β-catenin in these Shh+ cells promotes Type I cell fate in both FF and CV taste buds, but likely does so non-cell autonomously. Our data are consistent with a model where β-catenin signaling levels within lingual epithelial progenitors dictate cell fate prior to or during entry of new cells into taste buds; high signaling induces Type I cells, intermediate levels drive Type II cell differentiation, while low levels may drive differentiation of Type III cells.

  15. Amino acid limitation induces down-regulation of WNT5a at transcriptional level

    SciTech Connect

    Wang Zuguang; Chen Hong

    2009-01-23

    An aberrant WNT signaling contributes to the development and progression of multiple cancers. WNT5a is one of the WNT signaling molecules. This study was designed to test the hypothesis that amino acid deprivation induces changes in the WNT signaling pathway in colon cancer cells. Results showed that targets of the amino acid response pathway, ATF3 and p21, were induced in the human colon cancer cell line SW480 during amino acid limitation. There was a significant decrease in the WNT5a mRNA level following amino acid deprivation. The down-regulation of WNT5a mRNA by amino acid deprivation is not due to mRNA destabilization. There is a reduction of nuclear {beta}-catenin protein level by amino acid limitation. Under amino acid limitation, phosphorylation of ERK1/2 was increased and the blockage of ERK1/2 by the inhibitor U0126 partially restored WNT5a mRNA level. In conclusion, amino acid limitation in colon cancer cells induces phosphorylation of ERK1/2, which then down-regulates WNT5a expression.

  16. A monoclonal antibody against the Wnt signaling inhibitor dickkopf-1 inhibits osteosarcoma metastasis in a preclinical model

    PubMed Central

    Goldstein, Seth D.; Trucco, Matteo; Guzman, Wendy Bautista; Hayashi, Masanori; Loeb, David M.

    2016-01-01

    The outcome of patients with metastatic osteosarcoma has not improved since the introduction of chemotherapy in the 1970s. Development of therapies targeting the metastatic cascade is a tremendous unmet medical need. The Wnt signaling pathway has been the focus of intense investigation in osteosarcoma because of its role in normal bone development. Although the role of Wnt signaling in the pathogenesis of osteosarcoma is controversial, there are several reports of dickkopf-1 (DKK-1), a Wnt signaling antagonist, possibly playing a pro-tumorigenic role. In this work we investigated the effect of anti-DKK-1 antibodies on the growth and metastasis of patient-derived osteosarcoma xenografts. We were able to detect human DKK-1 in the blood of tumor-bearing mice and found a correlation between DKK-1 level and tumor proliferation. Treatment with the anti-DKK-1 antibody, BHQ880, slowed the growth of orthotopically implanted patient-derived osteosarcoma xenografts and inhibited metastasis. This effect was correlated with increased nuclear beta-catenin staining and increased expression of the bone differentiation marker osteopontin. These findings suggest that Wnt signaling is anti-tumorigenic in osteosarcoma, and support the targeting of DKK-1 as an anti-metastatic strategy for patients with osteosarcoma. PMID:27049730

  17. The pan-PI3K inhibitor GDC-0941 activates canonical WNT signaling to confer resistance in TNBC cells: resistance reversal with WNT inhibitor.

    PubMed

    Tzeng, Huey-En; Yang, Lixin; Chen, Kemin; Wang, Yafan; Liu, Yun-Ru; Pan, Shiow-Lin; Gaur, Shikha; Hu, Shuya; Yen, Yun

    2015-05-10

    The pan-PI3K inhibitors are one treatment option for triple-negative breast cancer (TNBC). However, this treatment is ineffective for unknown reasons. Here, we report that aberrant expression of wingless-type MMTV integration site family (WNT) and activated WNT signals, which crosstalk with the PI3K-AKT-mTOR signaling pathway through GSK3β, plays the most critical role in resistance to pan-PI3K inhibitors in TNBC cells. GDC-0941 is a pan-PI3K inhibitor that activates the WNT/beta-catenin pathway in TNBC cells through stimulation of WNT secretion. GDC-0941-triggered WNT/beta-catenin pathway activation was observed in MDA-MB-231 and HCC1937 cells, which are TNBC cell lines showing aberrant WNT/beta-catenin activation, and not in SKBR3 and MCF7 cells. This observation is further investigated in vivo. GDC-0941 exhibited minimal tumor inhibition in MDA-MB-231 cells, but it significantly suppressed tumor growth in HER-positive SK-BR3 cells. In vivo mechanism study revealed the activation of WNT/beta-catenin pathway by GDC-0941. A synergistic effect was observed when combined treatment with GDC-0941 and the WNT inhibitor LGK974 at low concentrations in MDA-MB-231 cells. These findings indicated that WNT pathway activation conferred resistance in TNBC cells treated with GDC-0941. This resistance may be further circumvented through combined treatment with pan-PI3K and WNT inhibitors. Future clinical trials of these two inhibitors are warranted.

  18. The pan-PI3K inhibitor GDC-0941 activates canonical WNT signaling to confer resistance in TNBC cells: resistance reversal with WNT inhibitor

    PubMed Central

    Tzeng, Huey-En; Yang, Lixin; Chen, Kemin; Wang, Yafan; Liu, Yun-Ru; Pan, Shiow-Lin; Gaur, Shikha; Hu, Shuya; Yen, Yun

    2015-01-01

    The pan-PI3K inhibitors are one treatment option for triple-negative breast cancer (TNBC). However, this treatment is ineffective for unknown reasons. Here, we report that aberrant expression of wingless-type MMTV integration site family (WNT) and activated WNT signals, which crosstalk with the PI3K-AKT-mTOR signaling pathway through GSK3β, plays the most critical role in resistance to pan-PI3K inhibitors in TNBC cells. GDC-0941 is a pan-PI3K inhibitor that activates the WNT/beta-catenin pathway in TNBC cells through stimulation of WNT secretion. GDC-0941-triggered WNT/beta-catenin pathway activation was observed in MDA-MB-231 and HCC1937 cells, which are TNBC cell lines showing aberrant WNT/beta-catenin activation, and not in SKBR3 and MCF7 cells. This observation is further investigated in vivo. GDC-0941 exhibited minimal tumor inhibition in MDA-MB-231 cells, but it significantly suppressed tumor growth in HER-positive SK-BR3 cells. In vivo mechanism study revealed the activation of WNT/beta-catenin pathway by GDC-0941. A synergistic effect was observed when combined treatment with GDC-0941 and the WNT inhibitor LGK974 at low concentrations in MDA-MB-231 cells. These findings indicated that WNT pathway activation conferred resistance in TNBC cells treated with GDC-0941. This resistance may be further circumvented through combined treatment with pan-PI3K and WNT inhibitors. Future clinical trials of these two inhibitors are warranted. PMID:25857298

  19. IGF-1 Receptor and Adhesion Signaling: An Important Axis in Determining Cancer Cell Phenotype and Therapy Resistance

    PubMed Central

    Cox, Orla T.; O’Shea, Sandra; Tresse, Emilie; Bustamante-Garrido, Milan; Kiran-Deevi, Ravi; O’Connor, Rosemary

    2015-01-01

    IGF-1R expression and activation levels generally cannot be correlated in cancer cells, suggesting that cellular proteins may modulate IGF-1R activity. Strong candidates for such modulation are found in cell-matrix and cell–cell adhesion signaling complexes. Activated IGF-1R is present at focal adhesions, where it can stabilize β1 integrin and participate in signaling complexes that promote invasiveness associated with epithelial mesenchymal transition (EMT) and resistance to therapy. Whether IGF-1R contributes to EMT or to non-invasive tumor growth may be strongly influenced by the degree of extracellular matrix engagement and the presence or absence of key proteins in IGF-1R-cell adhesion complexes. One such protein is PDLIM2, which promotes both cell polarization and EMT by regulating the stability of transcription factors including NFκB, STATs, and beta catenin. PDLIM2 exhibits tumor suppressor activity, but is also highly expressed in certain invasive cancers. It is likely that distinct adhesion complex proteins modulate IGF-1R signaling during cancer progression or adaptive responses to therapy. Thus, identifying the key modulators will be important for developing effective therapeutic strategies and predictive biomarkers. PMID:26191041

  20. [Cytokines in bone diseases. Wnt signaling and osteoporosis-pseudoglioma syndrome].

    PubMed

    Ozono, Keiichi

    2010-10-01

    Wnt signaling system plays essential roles in development, cancer and bone metabolism. Canonical wnt signaling, which involves wnt ligands, receptor named frizzled and co-receptors LRP5/6, beta-catenin and transcription factors named LEF/TCF is well characterized and its defect causes bone abnormalities. The loss-of-function type of the LRP5 gene mutation is responsible for osteoporosis-pseudoglioma syndrome. In addition, the LRP6 gene mutation leads to osteoporosis and metabolic syndrome. Thus, wnt signaling system is one of determinant factors for bone mineral density. PMID:20890034

  1. Enhancing Beta-Catenin Activity via GSK3beta Inhibition Protects PC12 Cells against Rotenone Toxicity through Nurr1 Induction

    PubMed Central

    Wei, Lei; Mo, Mingshu; Feng, Junmin; Sun, Congcong; Xiao, Yousheng; Luo, Qin; Li, Shaomin; Yang, Xinling; Xu, Pingyi

    2016-01-01

    Parkinson’s disease (PD) is characterized by progressive degeneration of dopaminergic (DA) neurons in the substantial nigra pars compacta. Increasing evidence showed that Wnt/β-catenin pathway and the orphan nuclear receptor Nurr1 play crucial roles in the survival and functional maintenance of DA neurons in the midbrain and GSK-3β antagonists LiCl and SB216763 were used to activate Wnt/β-catenin pathway experimentally. However, the detail mechanism underlying the neuroprotection against apoptosis on DA neuron is still unclear and the interaction between Wnt/β-catenin and Nurr1 remains undisclosed. In this study, using cell biological assay we investigated the function of Wnt/β-catenin and its crosstalk with Nurr1 on the course of PC12 cell degeneration in vitro. Our data showed that PC12 cell viability was inhibited by rotenone, but attenuated by GSK-3β antagonists LiCl or SB216763. The activity of Wnt/β-catenin pathway was deregulated on exposure of rotenone in a concentration-dependent manner. After the interference of β-catenin with siRNA, LiCl or SB216763 failed to protect PC12 cells from apoptosis by the rotenone toxicity. Our data confirmed that Wnt/β-catenin signaling activated by LiCl or SB216763 enhanced Nurr1 expression to 2.75 ± 0.55 and 4.06 ± 0.41 folds respectively compared with control detected by real-time PCR and the interaction of β-catenin with Nurr1 was identified by co-immunoprecipitate analysis. In conclusion, the data suggested that Wnt/β-catenin and Nurr1 are crucial factors in the survival of DA neurons, and the activation of Wnt/β-catenin pathway exerts protective effects on DA neurons partly by mean of a co-active pattern with Nurr1. This finding may shed a light on the potential treatment of Parkinson disease. PMID:27045591

  2. The frizzled extracellular domain is a ligand for Van Gogh/Stbm during nonautonomous planar cell polarity signaling.

    PubMed

    Wu, Jun; Mlodzik, Marek

    2008-09-01

    The Frizzled (Fz) receptor is required cell autonomously in Wnt/beta-catenin and planar cell polarity (PCP) signaling. In addition to these requirements, Fz acts nonautonomously during PCP establishment: wild-type cells surrounding fz(-) patches reorient toward the fz(-) cells. The molecular mechanism(s) of nonautonomous Fz signaling are unknown. Our in vivo studies identify the extracellular domain (ECD) of Fz, in particular its CRD (cysteine rich domain), as critical for nonautonomous Fz-PCP activity. Importantly, we demonstrate biochemical and physical interactions between the FzECD and the transmembrane protein Van Gogh/Strabismus (Vang/Stbm). We show that this function precedes cell-autonomous interactions and visible asymmetric PCP factor localization. Our data suggest that Vang/Stbm can act as a FzECD receptor, allowing cells to sense Fz activity/levels of their neighbors. Thus, direct Fz-Vang/Stbm interactions represent an intriguing mechanism that may account for the global orientation of cells within the plane of their epithelial field.

  3. Inhibitory mechanisms of two Uncaria tomentosa extracts affecting the Wnt-signaling pathway.

    PubMed

    Gurrola-Díaz, Carmen Magdalena; García-López, Pedro Macedonio; Gulewicz, Krzysztof; Pilarski, Radoslaw; Dihlmann, Susanne

    2011-06-15

    Uncaria tomentosa ("uña de gato"; "cat's claw"), a woody vine native to the Amazon rainforest, is commonly used in South American traditional medicine to treat a broad spectrum of diseases. Although recent studies have reported anti-inflammatory and anti-proliferative properties of different alkaloids extracted from this plant, the underlying molecular mechanisms of these effects have not been elucidated yet. Our study investigates the inhibitory mechanisms of Uncaria tomentosa extracts on the Wnt-signaling pathway, a central regulator of development and tissue homoeostasis. A modified cell-based luciferase assay for screening inhibitors of the Wnt-pathway was used for analysis. Three cancer cell lines displaying different levels of aberrant Wnt-signaling activity were transfected with Wnt-signaling responsive Tcf-reporter plasmids and treated with increasing concentrations of two Uncaria tomentosa bark extracts. Wnt-signaling activity was assessed by luciferase activity and by expression of Wnt-responsive target genes. We show that both, an aqueous and an alkaloid-enriched extract specifically inhibit Wnt-signaling activity in HeLa, HCT116 and SW480 cancer cells resulting in reduced expression of the Wnt-target gene: c-Myc. The alkaloid-enriched extract (B/S(rt)) was found to be more effective than the aqueous extract (B/W(37)). The strongest effect was observed in SW480 cells, displaying the highest endogenous Wnt-signaling activity. Downregulation of Wnt-signaling by a dominant negative-TCF-4 variant in non-cancer cells rendered the cells insensitive towards treatment with B/S(rt). B/Srt was less toxic in non-cancer cells than in cancer cells. Our data suggest that the broad spectrum of pharmacological action of Uncaria tomentosa involves inhibition of the Wnt-signaling pathway, downstream of beta-Catenin activity.

  4. Inhibitory mechanisms of two Uncaria tomentosa extracts affecting the Wnt-signaling pathway.

    PubMed

    Gurrola-Díaz, Carmen Magdalena; García-López, Pedro Macedonio; Gulewicz, Krzysztof; Pilarski, Radoslaw; Dihlmann, Susanne

    2011-06-15

    Uncaria tomentosa ("uña de gato"; "cat's claw"), a woody vine native to the Amazon rainforest, is commonly used in South American traditional medicine to treat a broad spectrum of diseases. Although recent studies have reported anti-inflammatory and anti-proliferative properties of different alkaloids extracted from this plant, the underlying molecular mechanisms of these effects have not been elucidated yet. Our study investigates the inhibitory mechanisms of Uncaria tomentosa extracts on the Wnt-signaling pathway, a central regulator of development and tissue homoeostasis. A modified cell-based luciferase assay for screening inhibitors of the Wnt-pathway was used for analysis. Three cancer cell lines displaying different levels of aberrant Wnt-signaling activity were transfected with Wnt-signaling responsive Tcf-reporter plasmids and treated with increasing concentrations of two Uncaria tomentosa bark extracts. Wnt-signaling activity was assessed by luciferase activity and by expression of Wnt-responsive target genes. We show that both, an aqueous and an alkaloid-enriched extract specifically inhibit Wnt-signaling activity in HeLa, HCT116 and SW480 cancer cells resulting in reduced expression of the Wnt-target gene: c-Myc. The alkaloid-enriched extract (B/S(rt)) was found to be more effective than the aqueous extract (B/W(37)). The strongest effect was observed in SW480 cells, displaying the highest endogenous Wnt-signaling activity. Downregulation of Wnt-signaling by a dominant negative-TCF-4 variant in non-cancer cells rendered the cells insensitive towards treatment with B/S(rt). B/Srt was less toxic in non-cancer cells than in cancer cells. Our data suggest that the broad spectrum of pharmacological action of Uncaria tomentosa involves inhibition of the Wnt-signaling pathway, downstream of beta-Catenin activity. PMID:21156346

  5. Negative blood oxygen level dependent signals during speech comprehension.

    PubMed

    Rodriguez Moreno, Diana; Schiff, Nicholas D; Hirsch, Joy

    2015-05-01

    Speech comprehension studies have generally focused on the isolation and function of regions with positive blood oxygen level dependent (BOLD) signals with respect to a resting baseline. Although regions with negative BOLD signals in comparison to a resting baseline have been reported in language-related tasks, their relationship to regions of positive signals is not fully appreciated. Based on the emerging notion that the negative signals may represent an active function in language tasks, the authors test the hypothesis that negative BOLD signals during receptive language are more associated with comprehension than content-free versions of the same stimuli. Regions associated with comprehension of speech were isolated by comparing responses to passive listening to natural speech to two incomprehensible versions of the same speech: one that was digitally time reversed and one that was muffled by removal of high frequencies. The signal polarity was determined by comparing the BOLD signal during each speech condition to the BOLD signal during a resting baseline. As expected, stimulation-induced positive signals relative to resting baseline were observed in the canonical language areas with varying signal amplitudes for each condition. Negative BOLD responses relative to resting baseline were observed primarily in frontoparietal regions and were specific to the natural speech condition. However, the BOLD signal remained indistinguishable from baseline for the unintelligible speech conditions. Variations in connectivity between brain regions with positive and negative signals were also specifically related to the comprehension of natural speech. These observations of anticorrelated signals related to speech comprehension are consistent with emerging models of cooperative roles represented by BOLD signals of opposite polarity.

  6. In Hyperthermia Increased ERK and WNT Signaling Suppress Colorectal Cancer Cell Growth

    PubMed Central

    Bordonaro, Michael; Shirasawa, Senji; Lazarova, Darina L.

    2016-01-01

    Although neoplastic cells exhibit relatively higher sensitivity to hyperthermia than normal cells, hyperthermia has had variable success as an anti-cancer therapy. This variable outcome might be due to the fact that cancer cells themselves have differential degrees of sensitivity to high temperature. We hypothesized that the varying sensitivity of colorectal cancer (CRC) cells to hyperthermia depends upon the differential induction of survival pathways. Screening of such pathways revealed that Extracellular Signal-Regulated Kinase (ERK) signaling is augmented by hyperthermia, and the extent of this modulation correlates with the mutation status of V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS). Through clonal growth assays, apoptotic analyses and transcription reporter assays of CRC cells that differ only in KRAS mutation status we established that mutant KRAS cells are more sensitive to hyperthermia, as they exhibit sustained ERK signaling hyperactivation and increased Wingless/Integrated (WNT)/beta-catenin signaling. We propose that whereas increased levels of WNT and ERK signaling and a positive feedback between the two pathways is a major obstacle in anti-cancer therapy today, under hyperthermia the hyperinduction of the pathways and their positive crosstalk contribute to CRC cell death. Ascertaining the causative association between types of mutations and hyperthermia sensitivity may allow for a mutation profile-guided application of hyperthermia as an anti-cancer therapy. Since KRAS and WNT signaling mutations are prevalent in CRC, our results suggest that hyperthermia-based therapy might benefit a significant number, but not all, CRC patients. PMID:27187477

  7. Monitoring coastal sea level using reflected GNSS signals

    NASA Astrophysics Data System (ADS)

    Löfgren, Johan S.; Haas, Rüdiger; Johansson, Jan M.

    2011-01-01

    A continuous monitoring of coastal sea level changes is important for human society since it is predicted that up to 332 million people in coastal and low-lying areas will be directly affected by flooding from sea level rise by the end of the 21st century. The traditional way to observe sea level is using tide gauges that give measurements relative to the Earth’s crust. However, in order to improve the understanding of the sea level change processes it is necessary to separate the measurements into land surface height changes and sea surface height changes. These measurements should then be relative to a global reference frame. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed. The GNSS-based tide gauge makes use of both GNSS signals that are directly received and GNSS signals that are reflected from the sea surface. An experimental installation at the Onsala Space Observatory (OSO) shows that the reflected GNSS signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS signals. Furthermore, a comparison of local sea level observations from the GNSS-based tide gauge with two stilling well gauges, located approximately 18 and 33 km away from OSO, gives a pairwise root-mean-square agreement on the order of 4 cm. This indicates that the GNSS-based tide gauge gives valuable results for sea level monitoring.

  8. MicroRNA-449a Overexpression, Reduced NOTCH1 Signals and Scarce Goblet Cells Characterize the Small Intestine of Celiac Patients

    PubMed Central

    Tinto, Nadia; Montanaro, Donatella; Capobianco, Valentina; Izzo, Valentina; Tucci, Francesca; Troncone, Giancarlo; Greco, Luigi; Sacchetti, Lucia

    2011-01-01

    MiRNAs play a relevant role in regulating gene expression in a variety of physiological and pathological conditions including autoimmune disorders. MiRNAs are also important in the differentiation and function of the mouse intestinal epithelium. Our study was aimed to look for miRNA-based modulation of gene expression in celiac small intestine, and particularly for genes involved in cell intestinal differentiation/proliferation mechanisms. A cohort of 40 children (20 with active CD, 9 on a gluten-free diet (GFD), and 11 controls), were recruited at the Paediatrics Department (University of Naples Federico II). The expression of 365 human miRNAs was quantified by TaqMan low-density arrays. We used bioinformatics to predict putative target genes of miRNAs and to select biological pathways. The presence of NOTCH1, HES1, KLF4, MUC-2, Ki67 and beta-catenin proteins in the small intestine of CD and control children was tested by immunohistochemistry. The expression of about 20% of the miRNAs tested differed between CD and control children. We found that high miR-449a levels targeted and reduced both NOTCH1 and KLF4 in HEK-293 cells. NOTCH1, KLF4 signals and the number of goblet cells were lower in small intestine of children with active CD and in those on a GFD than in controls, whereas more nuclear beta-catenin staining, as a sign of the WNT pathway activation, and more Ki67 staining, as sign of proliferation, were present in crypts from CD patients than in controls. In conclusion we first demonstrate a miRNA mediated gene regulation in small intestine of CD patients. We also highlighted a reduced NOTCH1 pathway in our patients, irrespective of whether the disease was active or not. We suggest that NOTCH pathway could be constitutively altered in the celiac small intestine and could drive the increased proliferation and the decreased differentiation of intestinal cells towards the secretory goblet cell lineage. PMID:22194996

  9. Quadrupole mass spectrometer driver with higher signal levels

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Aalami, Dean (Inventor); Darrach, Murray (Inventor); Orient, Otto (Inventor)

    2003-01-01

    Driving a quadrapole mass spectrometer includes obtaining an air core transformer with a primary and a secondary, matching the secondary to the mass spectrometer, and driving the primary based on first and second voltage levels. Driving of the primary is via an isolating stage that minimizes low level drive signal coupling.

  10. Casein kinase 1 gamma couples Wnt receptor activation to cytoplasmic signal transduction.

    PubMed

    Davidson, Gary; Wu, Wei; Shen, Jinlong; Bilic, Josipa; Fenger, Ursula; Stannek, Peter; Glinka, Andrei; Niehrs, Christof

    2005-12-01

    Signalling by Wnt proteins (Wingless in Drosophila) has diverse roles during embryonic development and in adults, and is implicated in human diseases, including cancer. LDL-receptor-related proteins 5 and 6 (LRP5 and LRP6; Arrow in Drosophila) are key receptors required for transmission of Wnt/beta-catenin signalling in metazoa. Although the role of these receptors in Wnt signalling is well established, their coupling with the cytoplasmic signalling apparatus remains poorly defined. Using a protein modification screen for regulators of LRP6, we describe the identification of Xenopus Casein kinase 1 gamma (CK1gamma), a membrane-bound member of the CK1 family. Gain-of-function and loss-of-function experiments show that CK1gamma is both necessary and sufficient to transduce LRP6 signalling in vertebrates and Drosophila cells. In Xenopus embryos, CK1gamma is required during anterio-posterior patterning to promote posteriorizing Wnt/beta-catenin signalling. CK1gamma is associated with LRP6, which has multiple, modular CK1 phosphorylation sites. Wnt treatment induces the rapid CK1gamma-mediated phosphorylation of these sites within LRP6, which, in turn, promotes the recruitment of the scaffold protein Axin. Our results reveal an evolutionarily conserved mechanism that couples Wnt receptor activation to the cytoplasmic signal transduction apparatus. PMID:16341016

  11. Human evoked cortical activity to signal-to-noise ratio and absolute signal level.

    PubMed

    Billings, Curtis J; Tremblay, Kelly L; Stecker, G Christopher; Tolin, Wendy M

    2009-08-01

    The purpose of this study was to determine the effect of signal level and signal-to-noise ratio (SNR) on the latency and amplitude of evoked cortical activity to further our understanding of how the human central auditory system encodes signals in noise. Cortical auditory evoked potentials (CAEPs) were recorded from 15 young normal-hearing adults in response to a 1000 Hz tone presented at two tone levels in quiet and while continuous background noise levels were varied in five equivalent SNR steps. These 12 conditions were used to determine the effects of signal level and SNR level on CAEP components P1, N1, P2, and N2. Based on prior signal-in-noise experiments conducted in animals, we hypothesized that SNR, would be a key contributor to human CAEP characteristics. As hypothesized, amplitude increased and latency decreased with increasing SNR; in addition, there was no main effect of tone level across the two signal levels tested (60 and 75 dB SPL). Morphology of the P1-N1-P2 complex was driven primarily by SNR, highlighting the importance of noise when recording CAEPs. Results are discussed in terms of the current interest in recording CAEPs in hearing aid users.

  12. SNS LINAC Wire Scanner System : Signal Levels and Accuracy.

    SciTech Connect

    Plum, M. A.; Christensen, W.; Myer, R. E.; Rose, C. R.

    2002-01-01

    The linac wire scanner system for the Spallation Neutron Source (SNS) at Oak Ridge, TN, USA, calls for 5 units in the medium energy beam transport (MEBT), 5 in the drift tube linac (DTL), and 10 in the coupled cavity linac (CCL). In this paper we present expected signal levels and an analysis of the error in the beam size measurement as functions of wire position and electrical signal errors.

  13. Effects of age, signal level, and signal rate on the auditory middle latency response.

    PubMed

    Tucker, D A; Ruth, R A

    1996-04-01

    The effects of age, signal rate, and signal level on the maturing auditory middle latency response (AMLR) were evaluated in 50 normal-hearing subjects ranging in age from 2 days to 35 years. Ipsilateral and contralateral AMLR waveforms were recorded in newborns (n = 10), children (n = 10), preteens (n = 10), teens (n = 10), and adults (n = 10). The AMLR Pa waveform was obtained in 70 to 100 percent of all subjects. The variables of age, signal level, and site of recording significantly affected Pa peak amplitude and absolute latency. However, stimulus rate did not significantly affect the response.

  14. Effects of age, signal level, and signal rate on the auditory middle latency response.

    PubMed

    Tucker, D A; Ruth, R A

    1996-04-01

    The effects of age, signal rate, and signal level on the maturing auditory middle latency response (AMLR) were evaluated in 50 normal-hearing subjects ranging in age from 2 days to 35 years. Ipsilateral and contralateral AMLR waveforms were recorded in newborns (n = 10), children (n = 10), preteens (n = 10), teens (n = 10), and adults (n = 10). The AMLR Pa waveform was obtained in 70 to 100 percent of all subjects. The variables of age, signal level, and site of recording significantly affected Pa peak amplitude and absolute latency. However, stimulus rate did not significantly affect the response. PMID:8652873

  15. Canonical Wnt signaling transiently stimulates proliferation and enhances neurogenesis in neonatal neural progenitor cultures

    SciTech Connect

    Hirsch, Cordula; Campano, Louise M.; Woehrle, Simon; Hecht, Andreas . E-mail: andreas.hecht@mol-med.uni-freiburg.de

    2007-02-01

    Canonical Wnt signaling triggers the formation of heterodimeric transcription factor complexes consisting of {beta}-catenin and T cell factors, and thereby controls the execution of specific genetic programs. During the expansion and neurogenic phases of embryonic neural development canonical Wnt signaling initially controls proliferation of neural progenitor cells, and later neuronal differentiation. Whether Wnt growth factors affect neural progenitor cells postnatally is not known. Therefore, we have analyzed the impact of Wnt signaling on neural progenitors isolated from cerebral cortices of newborn mice. Expression profiling of pathway components revealed that these cells are fully equipped to respond to Wnt signals. However, Wnt pathway activation affected only a subset of neonatal progenitors and elicited a limited increase in proliferation and neuronal differentiation in distinct subsets of cells. Moreover, Wnt pathway activation only transiently stimulated S-phase entry but did not support long-term proliferation of progenitor cultures. The dampened nature of the Wnt response correlates with the predominant expression of inhibitory pathway components and the rapid actuation of negative feedback mechanisms. Interestingly, in differentiating cell cultures activation of canonical Wnt signaling reduced Hes1 and Hes5 expression suggesting that during postnatal neural development, Wnt/{beta}-catenin signaling enhances neurogenesis from progenitor cells by interfering with Notch pathway activity.

  16. Wnt signaling in heart valve development and osteogenic gene induction

    PubMed Central

    Alfieri, Christina M.; Cheek, Jonathan; Chakraborty, Santanu; Yutzey, Katherine E.

    2009-01-01

    Wnt signaling mediated by beta-catenin has been implicated in early endocardial cushion development, but its roles in later stages of heart valve maturation and homeostasis have not been identified. Multiple Wnt ligands and pathway genes are differentially expressed during heart valve development. At E12.5, Wnt2 is expressed in cushion mesenchyme, whereas Wnt4 and Wnt9b are predominant in overlying endothelial cells. At E17.5, both Wnt3a and Wnt7b are expressed in the remodeling atrioventricular (AV) and semilunar valves. In addition, the TOPGAL Wnt reporter transgene is active throughout the developing AV and semilunar valves at E16.5, with more localized expression in the stratified valve leaflets after birth. In chicken embryo aortic valves, genes characteristic of osteogenic cell lineages including periostin, osteonectin, and Id2 are expressed specifically in the collagen-rich fibrosa layer at E14. Treatment of E14 aortic valve interstitial cells (VIC) in culture with osteogenic media results in increased expression of multiple genes associated with bone formation. Treatment of VIC with Wnt3a leads to nuclear localization of beta-catenin and induction of periostin and matrix gla-protein, but does not induce genes associated with later stages of osteogenesis. Together, these studies provide evidence for Wnt signaling as a regulator of endocardial cushion maturation as well as valve leaflet stratification, homeostasis and pathogenesis. PMID:19961844

  17. Glucocorticoid suppresses the canonical Wnt signal in cultured human osteoblasts

    SciTech Connect

    Ohnaka, Keizo . E-mail: oonaka@geriat.med.kyushu-u.ac.jp; Tanabe, Mizuho; Kawate, Hisaya; Nawata, Hajime; Takayanagi, Ryoichi

    2005-04-01

    To explore the mechanism of glucocorticoid-induced osteoporosis, we investigated the effect of glucocorticoid on canonical Wnt signaling that emerged as a novel key pathway for promoting bone formation. Wnt3a increased the T-cell factor (Tcf)/lymphoid enhancer factor (Lef)-dependent transcriptional activity in primary cultured human osteoblasts. Dexamethasone suppressed this transcriptional activity in a dose-dependent manner, while 1,25-dihydroxyvitamin D3 increased this transcriptional activity. LiCl, an inhibitor of glycogen synthase kinase-3{beta}, also enhanced the Tcf/Lef-dependent transcriptional activity, which was, however, not inhibited by dexamethasone. The addition of anti-dickkopf-1 antibody partially restored the transcriptional activity suppressed by dexamethasone. Dexamethasone decreased the cytosolic amount of {beta}-catenin accumulated by Wnt3a and also inhibited the nuclear translocation of {beta}-catenin induced by Wnt3a. These data suggest that glucocorticoid suppresses the canonical Wnt signal in cultured human osteoblasts, partially through the enhancement of the dickkopf-1 production.

  18. Generation of two-mode optical signals with broadband frequency tunability and low spurious signal level.

    PubMed

    Song, Ho-Jin; Shimizu, Naofumi; Nagatsuma, Tadao

    2007-10-29

    For continuous millimeter and terahertz-wave applications, a two-mode optical signal generation technique that uses two arrayed waveguide gratings and two optical switch units is presented. In addition to easy and fast operation, this scheme offers broadband frequency tunability and high signal purity with a low spurious mode level. Mode spacing, which corresponds to the frequency of the generated MM/THz-wave signal after photomixing, was successfully swept in the range of 200 ~ 550 GHz and the optical spurious mode suppression ratio higher than 25 dBc was achieved. In addition, spurious modes characteristics were investigated by using second harmonic generation (SHG) autocorrelation methods for several frequencies.

  19. pangolin encodes a Lef-1 homologue that acts downstream of Armadillo to transduce the Wingless signal in Drosophila.

    PubMed

    Brunner, E; Peter, O; Schweizer, L; Basler, K

    1997-02-27

    Members of the Wnt/Wingless (Wg) family of signalling proteins organize many aspects of animal development by regulating the expression of particular target genes in responding cells. Recent biochemical studies indicate that the vertebrate HMG-domain proteins Lef-1 and XTcf-3 can physically interact with beta-catenin, a homologue of Drosophila Armadillo (Arm), the most downstream component known in the Wnt signal transduction pathway. However, these studies do not address whether the endogenous Lef/Tcf family members are required in vivo to transduce Wnt signals. Using genetic methods in Drosophila, we define a new segment polarity gene, pangolin (pan), and show that its product is required in vivo for Wg signal transduction in embryos and in developing adult tissues. In addition, we show that pan encodes a Lef/Tcf homologue and provide evidence that its protein product binds to the beta-catenin homologue Armadillo in vivo. Finally, we demonstrate that Pan functions downstream of Arm to transduce the Wg signal. Thus, our results indicate that Pan is an essential component of the Wg transduction pathway and suggest that it acts directly to regulate gene transcription in response to Wg signalling.

  20. Dubble or nothing? Is HAUSP deubiquitylating enzyme the final arbiter of p53 levels?

    PubMed

    Wood, Stephen A

    2002-07-30

    Signal transduction processes can be regulated by biochemical modifications that affect protein activity or localization and by protein stability. Proteins implicated in cancer, such as beta-catenin and p53, are regulated by a combination of posttranslational modifications and protein degradation by the ubiquitin-proteasome pathway. Wood explores how ubiquitylation of these proteins may not be as unidirectional as previously thought. With the identification of substrate-specific deubiquitylating enzymes, ubiquitylation may not always lead to protein destruction, but may provide another finely tunable step for controlling protein activity. PMID:12149513

  1. Dubble or nothing? Is HAUSP deubiquitylating enzyme the final arbiter of p53 levels?

    PubMed

    Wood, Stephen A

    2002-07-30

    Signal transduction processes can be regulated by biochemical modifications that affect protein activity or localization and by protein stability. Proteins implicated in cancer, such as beta-catenin and p53, are regulated by a combination of posttranslational modifications and protein degradation by the ubiquitin-proteasome pathway. Wood explores how ubiquitylation of these proteins may not be as unidirectional as previously thought. With the identification of substrate-specific deubiquitylating enzymes, ubiquitylation may not always lead to protein destruction, but may provide another finely tunable step for controlling protein activity.

  2. Thalidomide induces limb deformities by perturbing the Bmp/Dkk1/Wnt signaling pathway.

    PubMed

    Knobloch, Jürgen; Shaughnessy, John D; Rüther, Ulrich

    2007-05-01

    Thalidomide, a sedative originally used to treat morning sickness and now used to treat leprosy and multiple myeloma, is also a teratogen that induces birth defects in humans such as limb truncations and microphthalmia. However, the teratogenic mechanism of action of this drug remains obscure. Thalidomide induces limb and eye defects in the chicken embryo at an EC50 of 50 microg/kg egg wt and apoptosis in primary human embryonic fibroblasts (HEFs) at an EC50 of 8.9 microM. Using these model systems, we demonstrate by semiquantitative reverse transcriptase-polymerase chain reaction and whole-mount in situ hybridization that thalidomide-induced oxidative stress enhances signaling through bone morphogenetic proteins (Bmps). This leads to up-regulation of the Bmp target gene and Wnt antagonist Dickkopf1 (Dkk1) with subsequent inhibition of canonical Wnt/beta-catenin signaling and increased cell death as shown by trypan blue and terminal deoxynucleotidyl transferase-mediated nick end labeling staining. Thalidomide-induced cell death was dramatically reduced in HEFs and in embryonic limb buds by the use of inhibitors against Bmps, Dkk1, and Gsk3beta, a beta-catenin antagonist acting downstream of Dkk1 in the Wnt pathway. Most interestingly, blocking of Dkk1 or Gsk3beta dramatically counteracts thalidomide-induced limb truncations and microphthalmia. From this, we conclude that perturbing of Bmp/Dkk1/Wnt signaling is central to the teratogenic effects of thalidomide.

  3. Medicarpin, a Natural Pterocarpan, Heals Cortical Bone Defect by Activation of Notch and Wnt Canonical Signaling Pathways

    PubMed Central

    Gupta, Chandra Prakash; Kureel, Jyoti; Mansoori, Mohd Nizam; Shukla, Priyanka; John, Aijaz A.; Singh, Kavita; Purohit, Dipak; Awasthi, Pallavi; Singh, Divya; Goel, Atul

    2015-01-01

    We evaluated the bone regeneration and healing effect of Medicarpin (med) in cortical bone defect model that heals by intramembranous ossification. For the study, female Sprague–Dawley rats were ovariectomized and rendered osteopenic. A drill hole injury was generated in mid femoral bones of all the animals. Med treatment was commenced the day after and continued for 15 days. PTH was taken as a reference standard. Fifteen days post-treatment, animals were sacrificed. Bones were collected for histomorphometry studies at the injury site by micro-computed tomography (μCT) and confocal microscopy. RNA and protein was harvested from newly generated bone. For immunohistochemistry, 5μm sections of decalcified femur bone adjoining the drill hole site were cut. By μCT analysis and calcein labeling of newly generated bone it was found that med promotes bone healing and new bone formation at the injury site and was comparable to PTH in many aspects. Med treatment led to increase in the Runx-2 and osteocalcin signals indicating expansion of osteoprogenitors at the injury site as evaluated by qPCR and immunohistochemical localization. It was observed that med promoted bone regeneration by activating canonical Wnt and notch signaling pathway. This was evident by increased transcript and protein levels of Wnt and notch signaling components in the defect region. Finally, we confirmed that med treatment leads to elevated bone healing in pre-osteoblasts by co localization of beta catenin with osteoblast marker alkaline phosphatase. In conclusion, med treatment promotes new bone regeneration and healing at the injury site by activating Wnt/canonical and notch signaling pathways. This study also forms a strong case for evaluation of med in delayed union and non-union fracture cases. PMID:26657206

  4. Proinsulin C-peptide antagonizes the profibrotic effects of TGF-beta1 via up-regulation of retinoic acid and HGF-related signaling pathways.

    PubMed

    Hills, Claire E; Willars, Gary B; Brunskill, Nigel J

    2010-04-01

    Novel signaling roles for C-peptide have recently been discovered with evidence that it can ameliorate complications of type 1 diabetes. Here we sought to identify new pathways regulated by C-peptide of relevance to the pathophysiology of diabetic nephropathy. Microarray analysis was performed to identify genes regulated by either C-peptide and/or TGF-beta1 in a human proximal tubular cell line, HK-2. Expression of retinoic acid receptor beta (RARbeta), hepatocyte growth factor (HGF), cellular retinoic acid-binding protein II (CRABPII), vimentin, E-cadherin, Snail, and beta-catenin was assessed by immunoblotting. The cellular localization of vimentin and beta-catenin was determined by immunocytochemistry. Changes in cell morphology were assessed by phase contrast microscopy. Gene expression profiling demonstrated differential expression of 953 and 1458 genes after C-peptide exposure for 18 h or 48 h, respectively. From these, members of the antifibrotic retinoic acid (RA)- and HGF-signaling pathways were selected. Immunoblotting demonstrated that C-peptide increased RARbeta, CRABPII, and HGF. We confirmed a role for RA in reversal of TGF-beta1-induced changes associated with epithelial-mesenchymal transition, including expression changes in Snail, E-cadherin, vimetin, and redistribution of beta-catenin. Importantly, these TGF-beta1-induced changes were inhibited by C-peptide. Further, effects of TGF-beta1 on Snail and E-cadherin expression were blocked by HGF, and inhibitory effects of C-peptide were removed by blockade of HGF activity. This study identifies a novel role for HGF as an effector of C-peptide, possibly via an RA-signaling pathway, highlighting C-peptide as a potential therapy for diabetic nephropathy. PMID:20197308

  5. Signal Transduction at the Single-Cell Level: Approaches to Study the Dynamic Nature of Signaling Networks.

    PubMed

    Handly, L Naomi; Yao, Jason; Wollman, Roy

    2016-09-25

    Signal transduction, or how cells interpret and react to external events, is a fundamental aspect of cellular function. Traditional study of signal transduction pathways involves mapping cellular signaling pathways at the population level. However, population-averaged readouts do not adequately illuminate the complex dynamics and heterogeneous responses found at the single-cell level. Recent technological advances that observe cellular response, computationally model signaling pathways, and experimentally manipulate cells now enable studying signal transduction at the single-cell level. These studies will enable deeper insights into the dynamic nature of signaling networks.

  6. Noncanonical Wnt-4 signaling enhances bone regeneration of mesenchymal stem cells in craniofacial defects through activation of p38 MAPK.

    PubMed

    Chang, Jia; Sonoyama, Wataru; Wang, Zhuo; Jin, Qiming; Zhang, Chengfei; Krebsbach, Paul H; Giannobile, William; Shi, Songtao; Wang, Cun-Yu

    2007-10-19

    Mesenchymal stem cells (MSCs) are multipotent cells that can be differentiated into osteoblasts and provide an excellent cell source for bone regeneration and repair. Recently, the canonical Wnt/beta-catenin signaling pathway has been found to play a critical role in skeletal development and osteogenesis, implying that Wnts can be utilized to improve de novo bone formation mediated by MSCs. However, it is unknown whether noncanonical Wnt signaling regulates osteogenic differentiation. Here, we find that Wnt-4 enhanced in vitro osteogenic differentiation of MSCs isolated from human adult craniofacial tissues and promoted bone formation in vivo. Whereas Wnt-4 did not stabilize beta-catenin, it activated p38 MAPK in a novel noncanonical signaling pathway. The activation of p38 was dependent on Axin and was required for the enhancement of MSC differentiation by Wnt-4. Moreover, using two different models of craniofacial bone injury, we found that MSCs genetically engineered to express Wnt-4 enhanced osteogenesis and improved the repair of craniofacial defects in vivo. Taken together, our results reveal that noncanonical Wnt signaling could also play a role in osteogenic differentiation. Wnt-4 may have a potential use in improving bone regeneration and repair of craniofacial defects.

  7. Dissecting nuclear Wingless signalling: recruitment of the transcriptional co-activator Pygopus by a chain of adaptor proteins.

    PubMed

    Städeli, Reto; Basler, Konrad

    2005-11-01

    Members of the Wingless (Wg)/Wnt family of secreted glycoproteins control cell fate during embryonic development and adult homeostasis. Wnt signals regulate the expression of target genes by activating a conserved signal transduction pathway. Upon receptor activation, the signal is transmitted intracellularly by stabilization of Armadillo (Arm)/beta-catenin. Arm/beta-catenin translocates to the nucleus, interacts with DNA-binding factors of the Pangolin (Pan)/TCF/LEF class and activates transcription of target genes in cooperation with the recently identified proteins Legless/BCL9 (Lgs) and Pygopus (Pygo). Here, we analyse the mode of action of Pan, Arm, Lgs, and Pygo in Drosophila cultured cells. We provide evidence that together these four proteins form a 'chain of adaptors' linking the NH2-terminal homology domain (NHD) of Pygo to the DNA-binding domain of Pan. We show that the NHD has potent transcriptional activation capacity, which differs from that of acidic activator domains and depends on a conserved NPF tripeptide. A single point mutation within this NPF motif abolishes the transcriptional activity of the Pygo NHD in vitro and strongly reduces Wg signalling in vivo. Together, our results suggest that the transcriptional output of Wg pathway activity largely relies on a 'chain of adaptors' design to direct the Pygo NHD to Wg target promoters in an Arm-dependent manner. PMID:16169192

  8. Dissecting nuclear Wingless signalling: recruitment of the transcriptional co-activator Pygopus by a chain of adaptor proteins.

    PubMed

    Städeli, Reto; Basler, Konrad

    2005-11-01

    Members of the Wingless (Wg)/Wnt family of secreted glycoproteins control cell fate during embryonic development and adult homeostasis. Wnt signals regulate the expression of target genes by activating a conserved signal transduction pathway. Upon receptor activation, the signal is transmitted intracellularly by stabilization of Armadillo (Arm)/beta-catenin. Arm/beta-catenin translocates to the nucleus, interacts with DNA-binding factors of the Pangolin (Pan)/TCF/LEF class and activates transcription of target genes in cooperation with the recently identified proteins Legless/BCL9 (Lgs) and Pygopus (Pygo). Here, we analyse the mode of action of Pan, Arm, Lgs, and Pygo in Drosophila cultured cells. We provide evidence that together these four proteins form a 'chain of adaptors' linking the NH2-terminal homology domain (NHD) of Pygo to the DNA-binding domain of Pan. We show that the NHD has potent transcriptional activation capacity, which differs from that of acidic activator domains and depends on a conserved NPF tripeptide. A single point mutation within this NPF motif abolishes the transcriptional activity of the Pygo NHD in vitro and strongly reduces Wg signalling in vivo. Together, our results suggest that the transcriptional output of Wg pathway activity largely relies on a 'chain of adaptors' design to direct the Pygo NHD to Wg target promoters in an Arm-dependent manner.

  9. Enhanced BMP signaling results in supernumerary tooth formation in USAG-1 deficient mouse

    SciTech Connect

    Murashima-Suginami, Akiko; Takahashi, Katsu Sakata, Tomoko; Tsukamoto, Hiroko; Sugai, Manabu; Yanagita, Motoko; Shimizu, Akira; Sakurai, Takeshi; Slavkin, Harold C.; Bessho, Kazuhisa

    2008-05-16

    Uterine sensitization associated gene-1 (USAG-1) is a BMP antagonist, and also modulates Wnt signaling. We previously reported that USAG-1 deficient mice have supernumerary teeth. The supernumerary maxillary incisor appears to form as a result of the successive development of the rudimentary upper incisor. USAG-1 abrogation rescued apoptotic elimination of odontogenic mesenchymal cells. We confirmed that BMPs were expressed in both the epithelium and mesenchyme of the rudimentary incisor at E14 and E15. BMP signaling in the rudimentary maxillary incisor, assessed by expressions of Msx1 and Dlx2 and the phosphorylation of Smad protein, was significantly enhanced. Wnt signaling as demonstrated by the nuclear localization of {beta}-catenin was also up-regulated. Inhibition of BMP signaling rescues supernumerary tooth formation in E15 incisor explant culture. Based upon these results, we conclude that enhanced BMP signaling results in supernumerary teeth and BMP signaling was modulated by Wnt signaling in the USAG-1 deficient mouse model.

  10. Intestinal tumor progression is promoted by decreased apoptosis and dysregulated Wnt signaling in Ceacam1-/- mice.

    PubMed

    Leung, N; Turbide, C; Balachandra, B; Marcus, V; Beauchemin, N

    2008-08-21

    The carcinoembryonic antigen cell adhesion molecule 1 (CEACAM1) is downregulated in colonic and intestinal hyperplastic lesions as well as in other cancers, where it functions as a tumor suppressor. To investigate the functions of CEACAM1 in the normal intestine and in intestinal tumors, we generated a compound knockout mouse model and examined both Ceacam1(-/-) and Apc(1638N/+):Ceacam1(-/-) mice. Ceacam1(-/-) intestinal cells exhibited a significant decrease in apoptosis, with no change in proliferation or migration, however. Compound Apc(1638N/+):Ceacam1(-/-) mice demonstrated an increase in intestinal tumor multiplicity and tumor progression. Increases in intussusceptions and desmoid lesions were also observed. We have shown that CEACAM1-L associates with beta-catenin by co-immunoprecipitation and colocalization in CEACAM1-L-transfected CT26 and CT51 mouse colon carcinoma cells. Ceacam1(-/-) enterocytes displayed decreased glycogen synthase kinase 3-beta activity with corresponding nuclear localization of beta-catenin. Increased T-cell factor/Lef transcriptional activity was observed in CEACAM1-null CT51 colonic cells and in Caco2 colon cancer cells in which CEACAM1 was downregulated. A significant increased expression in c-Myc and cyclin D1 targets of the Wnt signaling pathway was also revealed in the Ceacam1(-/-) intestine. CEACAM1 therefore actively participates in Wnt signaling in intestinal cells and its downregulation in intestinal tissue contributes to malignancy by augmenting tumor multiplicity and progression.

  11. Local Sea Level Derived from Reflected GNSS Signals

    NASA Astrophysics Data System (ADS)

    Löfgren, J. S.; Haas, R.; Scherneck, H.; Bos, M. S.

    2011-12-01

    The traditional way to observe sea level is to use tide gauges, resulting in measurements relative to the Earth's crust. However, in order to measure the sea-level change due to changes in ocean water volume and/or other oceanographic phenomena, all types of crustal motion at the measurement site need to be known. We present a remote sensing technique for measuring local sea level using standard geodetic-type Global Navigation Satellite System (GNSS) receivers. The installation consists of a zenith-looking Right Hand Circular Polarized (RHCP) antenna, receiving the direct signals, and a nadir-looking Left Hand Circular Polarized antenna, receiving the signals reflected of the sea surface. Each antenna is connected to a receiver and the antenna pair is deployed back-to-back at a coastal site. Estimating the vertical baseline between the two antennas, using standard geodetic analysis, the local sea level and its temporal variations can be determined. The advantage of this technique is that it allows to measure both sea surface height changes with relative positioning and land surface height changes, e.g., by precise point positioning of the RHCP antenna. Furthermore, the combined measurements of local sea level are automatically corrected for land motion, meaning that this installation could provide continuously reliable sea-level estimates in tectonic active regions. This GNSS-based tide gauge has been operating continuously at the Onsala Space Observatory (OSO) on the west coast of Sweden since September 2010. We present results from several months of operations and compare them to sea-level measurements from two stilling well gauges about 18 km south and 33 km north of OSO. We find a high degree of agreement between the time series with correlation coefficients of larger than 0.95. The root-mean-square differences between the GNSS-derived sea level and the stilling well gauge measurements are 5.9 cm and 5.5 cm, which is lower than between the two stilling well (6

  12. Levels of complexity in scale-invariant neural signals.

    PubMed

    Ivanov, Plamen Ch; Ma, Qianli D Y; Bartsch, Ronny P; Hausdorff, Jeffrey M; Nunes Amaral, Luís A; Schulte-Frohlinde, Verena; Stanley, H Eugene; Yoneyama, Mitsuru

    2009-04-01

    Many physical and physiological signals exhibit complex scale-invariant features characterized by 1/f scaling and long-range power-law correlations, indicating a possibly common control mechanism. Specifically, it has been suggested that dynamical processes, influenced by inputs and feedback on multiple time scales, may be sufficient to give rise to 1/f scaling and scale invariance. Two examples of physiologic signals that are the output of hierarchical multiscale physiologic systems under neural control are the human heartbeat and human gait. Here we show that while both cardiac interbeat interval and gait interstride interval time series under healthy conditions have comparable 1/f scaling, they still may belong to different complexity classes. Our analysis of the multifractal scaling exponents of the fluctuations in these two signals demonstrates that in contrast to the multifractal behavior found in healthy heartbeat dynamics, gait time series exhibit less complex, close to monofractal behavior. Further, we find strong anticorrelations in the sign and close to random behavior for the magnitude of gait fluctuations at short and intermediate time scales, in contrast to weak anticorrelations in the sign and strong positive correlation for the magnitude of heartbeat interval fluctuations-suggesting that the neural mechanisms of cardiac and gait control exhibit different linear and nonlinear features. These findings are of interest because they underscore the limitations of traditional two-point correlation methods in fully characterizing physiological and physical dynamics. In addition, these results suggest that different mechanisms of control may be responsible for varying levels of complexity observed in physiological systems under neural regulation and in physical systems that possess similar 1/f scaling.

  13. Modeling signalized intersection safety with corridor-level spatial correlations.

    PubMed

    Guo, Feng; Wang, Xuesong; Abdel-Aty, Mohamed A

    2010-01-01

    Intersections in close spatial proximity along a corridor should be considered as correlated due to interacted traffic flows as well as similar road design and environmental characteristics. It is critical to incorporate this spatial correlation for assessing the true safety impacts of risk factors. In this paper, several Bayesian models were developed to model the crash data from 170 signalized intersections in the state of Florida. The safety impacts of risk factors such as geometric design features, traffic control, and traffic flow characteristics were evaluated. The Poisson and Negative Binomial Bayesian models with non-informative priors were fitted but the focus is to incorporate spatial correlations among intersections. Two alternative models were proposed to capture this correlation: (1) a mixed effect model in which the corridor-level correlation is incorporated through a corridor-specific random effect and (2) a conditional autoregressive model in which the magnitude of correlations is determined by spatial distances among intersections. The models were compared using the Deviance Information Criterion. The results indicate that the Poisson spatial model provides the best model fitting. Analysis of the posterior distributions of model parameters indicated that the size of intersection, the traffic conditions by turning movement, and the coordination of signal phase have significant impacts on intersection safety.

  14. Cellular chromophores and signaling in low level light therapy

    NASA Astrophysics Data System (ADS)

    Hamblin, Michael R.; Demidova-Rice, Tatiana N.

    2007-02-01

    particular, signaling cascades are initiated via cyclic adenosine monophosphate (cAMP) and nuclear factor kappa B (NF-κB). These signal transduction pathways in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increases in anti-apoptotic proteins. The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing in chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury and retinal toxicity.

  15. Integral estimation of number of resolvable signal levels of digital cameras

    NASA Astrophysics Data System (ADS)

    Cheremkhin, P. A.; Evtikhiev, N. N.; Krasnov, V. V.; Kurbatova, E. A.; Starikov, R. S.; Starikov, S. N.

    2016-08-01

    Number of signal levels of modern photo- and videocameras equals thousands and tens of thousands. However because of temporal and spatial camera pixels noises and linear dynamic range limitation, number of resolvable signal levels is significantly lower. Earlier iterative method of estimation of number of resolvable signal levels of cameras was proposed. In this paper integral method of estimation of number of resolvable signal levels of cameras is proposed and applied to consumer camera.

  16. Influencing of warning label signal words on perceived hazard level.

    PubMed

    Wogalter, M S; Jarrard, S W; Simpson, S N

    1994-09-01

    This experiment investigated the influence of warnings, signal words, and a signal icon on perceived hazard of consumer products. Under the guise of a marketing research study, 135 people (high school students, college students, and participants from a shopping mall) rated product labels on six dimensions, including how hazardous they perceived the products to be. A total of 16 labels from actual household products were used: 9 carried the experimental conditions, and 7 were filler product labels that never carried a warning. Five conditions presented the signal words NOTE, CAUTION, WARNING, DANGER, and LETHAL together with a brief warning message. In another two conditions, a signal icon (exclamation point surrounded by a triangle) was presented together with the terms DANGER and LETHAL. In the final two conditions, one lacked a signal word but retained the warning message, and the other lacked both the warning message and the signal word. Results showed that the presence of a signal word increased perceived product hazard compared with its absence. Significant differences were noted between extreme terms (e.g., NOTE and DANGER) but not between terms usually recommended in warning design guidelines (e.g., CAUTION and WARNING). The signal icon showed no significant effect on hazard perception. Implications of the results and the value of the methodology for future warnings investigations are discussed. PMID:7989055

  17. Genomic response to Wnt signalling is highly context-dependent - Evidence from DNA microarray and chromatin immunoprecipitation screens of Wnt/TCF targets

    SciTech Connect

    Railo, Antti; Pajunen, Antti; Itaeranta, Petri; Naillat, Florence; Vuoristo, Jussi; Kilpelaeinen, Pekka; Vainio, Seppo

    2009-10-01

    Wnt proteins are important regulators of embryonic development, and dysregulated Wnt signalling is involved in the oncogenesis of several human cancers. Our knowledge of the downstream target genes is limited, however. We used a chromatin immunoprecipitation-based assay to isolate and characterize the actual gene segments through which Wnt-activatable transcription factors, TCFs, regulate transcription and an Affymetrix microarray analysis to study the global transcriptional response to the Wnt3a ligand. The anti-{beta}-catenin immunoprecipitation of DNA-protein complexes from mouse NIH3T3 fibroblasts expressing a fusion protein of {beta}-catenin and TCF7 resulted in the identification of 92 genes as putative TCF targets. GeneChip assays of gene expression performed on NIH3T3 cells and the rat pheochromocytoma cell line PC12 revealed 355 genes in NIH3T3 and 129 genes in the PC12 cells with marked changes in expression after Wnt3a stimulus. Only 2 Wnt-regulated genes were shared by both cell lines. Surprisingly, Disabled-2 was the only gene identified by the chromatin immunoprecipitation approach that displayed a marked change in expression in the GeneChip assay. Taken together, our approaches give an insight into the complex context-dependent nature of Wnt pathway transcriptional responses and identify Disabled-2 as a potential new direct target for Wnt signalling.

  18. The emerging role of Wnt/PCP signaling in organ formation.

    PubMed

    Dale, Rodney M; Sisson, Barbara E; Topczewski, Jacek

    2009-03-01

    Over the last two decades zebrafish has been an excellent model organism to study vertebrate development. Mutant analysis combined with gene knockdown and other manipulations revealed an essential role of Wnt signaling, independent of beta-catenin, during development. Especially well characterized is the function of Wnt/planar cell polarity (PCP) signaling in the regulation of gastrulation movements and neurulation, described in other reviews within this special issue. Here, we set out to highlight some of the new and exciting research that is being carried out in zebrafish to elucidate the role that Wnt/PCP signaling plays in the formation of specific organs, including the lateral line, craniofacial development, and regeneration. We also summarized the emerging connection of the Wnt/PCP pathway with primary cilia function, an essential organelle in several organ activities.

  19. Noncanonical Wnt signaling promotes osteoclast differentiation and is facilitated by the human immunodeficiency virus protease inhibitor ritonavir

    SciTech Connect

    Santiago, Francisco; Oguma, Junya; Brown, Anthony M.C.; Laurence, Jeffrey

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer First demonstration of direct role for noncanonical Wnt in osteoclast differentiation. Black-Right-Pointing-Pointer Demonstration of Ryk as a Wnt5a/b receptor in inhibition of canonical Wnt signaling. Black-Right-Pointing-Pointer Modulation of noncanonical Wnt signaling by a clinically important drug, ritonavir. Black-Right-Pointing-Pointer Establishes a mechanism for an important clinical problem: HIV-associated bone loss. -- Abstract: Wnt proteins that signal via the canonical Wnt/{beta}-catenin pathway directly regulate osteoblast differentiation. In contrast, most studies of Wnt-related effects on osteoclasts involve indirect changes. While investigating bone mineral density loss in the setting of human immunodeficiency virus (HIV) infection and its treatment with the protease inhibitor ritonavir (RTV), we observed that RTV decreased nuclear localization of {beta}-catenin, critical to canonical Wnt signaling, in primary human and murine osteoclast precursors. This occurred in parallel with upregulation of Wnt5a and Wnt5b transcripts. These Wnts typically stimulate noncanonical Wnt signaling, and this can antagonize the canonical Wnt pathway in many cell types, dependent upon Wnt receptor usage. We now document RTV-mediated upregulation of Wnt5a/b protein in osteoclast precursors. Recombinant Wnt5b and retrovirus-mediated expression of Wnt5a enhanced osteoclast differentiation from human and murine monocytic precursors, processes facilitated by RTV. In contrast, canonical Wnt signaling mediated by Wnt3a suppressed osteoclastogenesis. Both RTV and Wnt5b inhibited canonical, {beta}-catenin/T cell factor-based Wnt reporter activation in osteoclast precursors. RTV- and Wnt5-induced osteoclast differentiation were dependent upon the receptor-like tyrosine kinase Ryk, suggesting that Ryk may act as a Wnt5a/b receptor in this context. This is the first demonstration of a direct role for Wnt signaling pathways and Ryk in

  20. Overexpression of {alpha}-catenin increases osteoblastic differentiation in mouse mesenchymal C3H10T1/2 cells

    SciTech Connect

    Kim, Dohee; Yang, Jae-Yeon; Shin, Chan Soo

    2009-05-15

    {alpha}- and {beta}-Catenin link cadherins to the actin-based cytoskeleton at adherens junctions and regulate cell-cell adhesion. Although roles of cadherins and canonical Wnt-/{beta}-catenin-signaling in osteoblastic differentiation have been extensively studied, the role of {alpha}-catenin is not known. Murine embryonic mesenchymal stem cells, C3H10T1/2 cells, were transduced with retrovirus encoding {alpha}-catenin (MSCV-{alpha}-catenin-HA-GFP). In the presence of Wnt-3A conditioned medium or osteogenic medium ({beta}-glycerol phosphate and ascorbic acid), cells overexpressing {alpha}-catenin showed enhanced osteoblastic differentiation as measured by alkaline phosphatase (ALP) staining and ALP activity assay compared to cells transduced with empty virus (MSCV-GFP). In addition, mRNA expression of osteocalcin and Runx2 was significantly increased compared to control. Cell aggregation assay revealed that {alpha}-catenin overexpression has significantly increased cell-cell aggregation. However, cellular {beta}-catenin levels (total, cytoplasmic-nuclear ratio) and {beta}-catenin-TCF/LEF transcriptional activity did not change by overexpression of {alpha}-catenin. Knock-down of {alpha}-catenin using siRNA decreased osteoblastic differentiation as measured by ALP assay. These results suggest that {alpha}-catenin overexpression increases osteoblastic differentiation by increasing cell-cell adhesion rather than Wnt-/{beta}-catenin-signaling.

  1. FET comparator detects analog signal levels without loading analog device

    NASA Technical Reports Server (NTRS)

    Wallace, H. L.

    1966-01-01

    FET comparator circuit detects discrete analog computer output levels without excessively loading the output amplifier of the computer. An FET common source amplifier is coupled by a differential amplifier to a bistable transistor flip-flop. This circuit provides a digital output for analog voltages above or below a predetermined level.

  2. WRM-1 activates the LIT-1 protein kinase to transduce anterior/posterior polarity signals in C. elegans.

    PubMed

    Rocheleau, C E; Yasuda, J; Shin, T H; Lin, R; Sawa, H; Okano, H; Priess, J R; Davis, R J; Mello, C C

    1999-06-11

    During C. elegans development, Wnt/WG signaling is required for differences in cell fate between sister cells born from anterior/posterior divisions. A beta-catenin-related gene, wrm-1, and the lit-1 gene are effectors of this signaling pathway and appear to downregulate the activity of POP-1, a TCF/LEF-related protein, in posterior daughter cells. We show here that lit-1 encodes a serine/threonine protein kinase homolog related to the Drosophila tissue polarity protein Nemo. We demonstrate that the WRM-1 protein binds to LIT-1 in vivo and that WRM-1 can activate the LIT-1 protein kinase when coexpressed in vertebrate tissue culture cells. This activation leads to phosphorylation of POP-1 and to apparent changes in its subcellular localization. Our findings provide evidence for novel regulatory avenues for an evolutionarily conserved Wnt/WG signaling pathway. PMID:10380924

  3. Signaling profiling at the single-cell level identifies a distinct signaling signature in murine hematopoietic stem cells

    PubMed Central

    Du, Juan; Wang, Jinyong; Kong, Guangyao; Jiang, Jing; Zhang, Jingfang; Liu, Yangang; Tong, Wei; Zhang, Jing

    2012-01-01

    Hematopoietic stem cell (HSC) function is tightly regulated by cytokine signaling. Although phospho-flow cytometry allows us to study signaling in defined populations of cells, there has been tremendous hurdle to carry out this study in rare HSCs due to unrecoverable critical HSC markers, low HSC number, and poor cell recovery rate. Here, we overcame these difficulties and developed a “HSC phospho-flow” method to analyze cytokine signaling in murine HSCs at the single-cell level and compare HSC signaling profile to that of multipotent progenitors (MPPs), a cell type immediately downstream of HSCs, and commonly used Lin− cKit+ cells (LK cells, enriched for myeloid progenitors). We chose to study signaling evoked from three representative cytokines, stem cell factor (SCF) and thrombopoietin (TPO) that are essential for HSC function, and granulocyte macrophage-colony stimulating factor (GM-CSF) that is dispensable for HSCs. HSCs display a distinct TPO and GM-CSF signaling signature from MPPs and LK cells, which highly correlates with receptor surface expression. In contrast, although majority of LK cells express lower levels of cKit than HSCs and MPPs, SCF-evoked ERK1/2 activation in LK cells shows a significantly increased magnitude for a prolonged period. These results suggest that specific cellular context plays a more important role than receptor surface expression in SCF signaling. Our study of HSC signaling at the homeostasis stage paves the way to investigate signaling changes in HSCs under conditions of stress, aging, and hematopoietic diseases. PMID:22628264

  4. The inhibitory effect of superparamagnetic iron oxide nanoparticle (Ferucarbotran) on osteogenic differentiation and its signaling mechanism in human mesenchymal stem cells

    SciTech Connect

    Chen, Ying-Chun; Hsiao, Jong-Kai; Liu, Hon-Man; Lai, I-Yin; Yao, Ming; Hsu, Szu-Chun; Ko, Bor-Sheng; Chen, Yao-Chang; Yang, Chung-Shi; Huang, Dong-Ming

    2010-06-01

    Superparamagnetic iron oxide (SPIO) nanoparticles are very useful for monitoring cell trafficking in vivo and distinguish whether cellular regeneration originated from an exogenous cell source, which is a key issue for developing successful stem cell therapies. However, the impact of SPIO labeling on stem cell behavior remains uncertain. Here, we show the inhibitory effect of Ferucarbotran, an ionic SPIO, on osteogenic differentiation and its signaling mechanism in human mesenchymal stem cells. Ferucarbotran caused a dose-dependent inhibition of osteogenic differentiation, abolished the differentiation at high concentration, promoted cell migration, and activated the signaling molecules, {beta}-catenin, a cancer/testis antigen, SSX, and matrix metalloproteinase 2 (MMP2). An iron chelator, desferrioxamine, suppressed all the above Ferucarbotran-induced actions, demonstrating an important role of free iron in the inhibition of osteogenic differentiation that is mediated by the promotion of cell mobilization, involving the activation of a specific signaling pathway.

  5. Identification of earthquake signals from groundwater level records using the HHT method

    NASA Astrophysics Data System (ADS)

    Chen, Chieh-Hung; Wang, Chung-Ho; Liu, Jann-Yenq; Liu, Chen; Liang, Wen-Tzong; Yen, Horng-Yuan; Yeh, Yih-Hsiung; Chia, Yee-Ping; Wang, Yetmen

    2010-03-01

    Coseismic signals of groundwater levels are generally obtained by subtracting the responses of atmospheric pressure, Earth tides and precipitation from the observed data. However, if the observations are conducted without nearby barometers, pluviometers or Earth tide data for correction, coseismic signals are often difficult to extract. In this case, the Hilbert-Huang transform (HHT) is used to obtain the instantaneous frequencies and amplitudes for every point of the decomposed intrinsic mode functions (IMFs) from groundwater level data for differentiating the related frequency-dependent responses without a further auxiliary input. The extracted coseismic signals show intense amplitude pulses that are clearly seen in the third IMF. In addition, two types of coseismic signals can be readily distinguished in the results from the HHT transform. One is an instantaneous short-time signal induced by the passing of seismic waves. Another coseismic signal is a sustained signal induced by the near-field earthquake occurring near the Hualien station, Taiwan and shows a positive correlation between the earthquake distance and magnitude. Our results generally show that using the HHT transform improves our understanding of automatic detection of the coseismic signals from the groundwater level.

  6. Rac1 and Cdc42 GTPases regulate shear stress-driven β-catenin signaling in osteoblasts

    SciTech Connect

    Wan, Qiaoqiao; Cho, Eunhye; Yokota, Hiroki; Na, Sungsoo

    2013-04-19

    Highlights: •Shear stress increased TCF/LEF activity and stimulated β-catenin nuclear localization. •Rac1, Cdc42, and RhoA displayed distinct dynamic activity patterns under flow. •Rac1 and Cdc42, but not RhoA, regulate shear stress-driven TCF/LEF activation. •Cytoskeleton did not significantly affect shear stress-induced TCF/LEF activation. -- Abstract: Beta-catenin-dependent TCF/LEF (T-cell factor/lymphocyte enhancing factor) is known to be mechanosensitive and an important regulator for promoting bone formation. However, the functional connection between TCF/LEF activity and Rho family GTPases is not well understood in osteoblasts. Herein we investigated the molecular mechanisms underlying oscillatory shear stress-induced TCF/LEF activity in MC3T3-E1 osteoblast cells using live cell imaging. We employed fluorescence resonance energy transfer (FRET)-based and green fluorescent protein (GFP)-based biosensors, which allowed us to monitor signal transduction in living cells in real time. Oscillatory (1 Hz) shear stress (10 dynes/cm{sup 2}) increased TCF/LEF activity and stimulated translocation of β-catenin to the nucleus with the distinct activity patterns of Rac1 and Cdc42. The shear stress-induced TCF/LEF activity was blocked by the inhibition of Rac1 and Cdc42 with their dominant negative mutants or selective drugs, but not by a dominant negative mutant of RhoA. In contrast, constitutively active Rac1 and Cdc42 mutants caused a significant enhancement of TCF/LEF activity. Moreover, activation of Rac1 and Cdc42 increased the basal level of TCF/LEF activity, while their inhibition decreased the basal level. Interestingly, disruption of cytoskeletal structures or inhibition of myosin activity did not significantly affect shear stress-induced TCF/LEF activity. Although Rac1 is reported to be involved in β-catenin in cancer cells, the involvement of Cdc42 in β-catenin signaling in osteoblasts has not been identified. Our findings in this study demonstrate

  7. Myocardial signal density levels and beam-hardening artifact attenuation using dual-energy computed tomography.

    PubMed

    Rodriguez-Granillo, Gaston A; Carrascosa, Patricia; Cipriano, Silvina; de Zan, Macarena; Deviggiano, Alejandro; Capunay, Carlos; Cury, Ricardo C

    2015-01-01

    The assessment of myocardial perfusion using single-energy (SE) imaging is influenced by beam-hardening artifacts (BHA). We sought to explore the ability of dual-energy (DE) imaging to attenuate the presence of BHA. Myocardial signal density (SD) was evaluated in 2240 myocardial segments (112 for each energy level) and in 320 American Heart Association segments among the SE group. Compared to DE reconstructions at the best energy level, SE acquisitions showed no significant differences overall regarding myocardial SD or signal-to-noise ratio. The segments most commonly affected by BHA showed significantly lower myocardial SD at the lowest energy levels, progressively normalizing at higher energy levels.

  8. Bone morphogenetic protein (BMP) signaling regulates mitotic checkpoint protein levels in human breast cancer cells.

    PubMed

    Yan, Hualong; Zhu, Songcheng; Song, Chenlin; Liu, Naifa; Kang, Jiuhong

    2012-04-01

    Aberrant expression of mitotic checkpoint genes compromises mitotic checkpoint, leads to chromosome instability and tumorigenesis. However, the cell signals that control mitotic checkpoint gene expression have not been reported so far. In the present study we show that, in human breast cancer cells, chemical inhibition of Bone morphogenetic proteins (BMPs), but not Transforming Growth Factor-β (TGF-β), abrogates the mitotic arrest induced by nocodazole. Protein expression analysis reveals that inhibition of BMP signaling dramatically down regulates protein levels of mitotic checkpoint components BUB3, Hec1, TTK and MAD2, but inhibition of TGF-β has relatively minor effect on the expression of these proteins. Activation of BMP signaling specifically up regulates BUB3, and activation of Activin A signaling globally down regulates these proteins level. Furthermore, overexpressing MAD2, TTK, BUB3 or Hec1 significantly rescues the mitotic arrest defect caused by BMP inhibition. Our results demonstrated for the first time that TGF-β family cytokines are cellular signals regulating mitotic checkpoint and perturbations in intrinsic BMP signaling could lead to suppression of mitotic checkpoint signaling by downregulating key checkpoint proteins. The results suggest a possible mechanism by which dysregulation of TGF-β signaling causes mitotic checkpoint defects and drives tumorigenesis. The finding also provides a potential and more specific strategy for cancer prevention by targeting BMP and mitotic checkpoint connection. PMID:22234345

  9. Fusion of multi-sensory NDT data for reliable detection of surface cracks: Signal-level vs. decision-level

    NASA Astrophysics Data System (ADS)

    Heideklang, René; Shokouhi, Parisa

    2016-02-01

    We present and compare two different approaches for NDT multi-sensor data fusion at signal (low) and decision (high) levels. Signal-level fusion is achieved by applying simple algebraic rules to strategically post-processed images. This is done in the original domain or in the domain of a suitable signal transform. The importance of signal normalization for low-level fusion applications is emphasized in regard to heterogeneous NDT data sets. For fusion at decision level, we develop a procedure based on assembling joint kernel density estimation (KDE). The procedure involves calculating KDEs for individual sensor detections and aggregating them by applying certain combination rules. The underlying idea is that if the detections from more than one sensor fall spatially close to one another, they are likely to result from the presence of a defect. On the other hand, single-senor detections are more likely to be structural noise or false alarm indications. To this end, we design the KDE combination rules such that it prevents single-sensor domination and allows data-driven scaling to account for the influence of individual sensors. We apply both fusion rules to a three-sensor dataset consisting in ET, MFL/GMR and TT data collected on a specimen with built-in surface discontinuities. The performance of the fusion rules in defect detection is quantitatively evaluated and compared against those of the individual sensors. Both classes of data fusion rules result in a fused image of fewer false alarms and thus improved defect detection. Finally, we discuss the advantages and disadvantages of low-level and high-level NDT data fusion with reference to our experimental results.

  10. Spatial Four Wave Mixing, Probe Images, and Fluorescence Signals in Dressed Three-Level System

    NASA Astrophysics Data System (ADS)

    Lan, Huayan; Sun, Jia; Wu, Zhenkun; Zhang, Dan; Zhang, Yiqi; Zheng, Huaibin; Zhang, Yanpeng

    2013-10-01

    We investigate the spatial images of the probe, generated four wave mixing (FWM) signal and the accompanying fluorescence spectrum signal simultaneously in FWM process in a cascade three-level atomic system for the first time. We experimentally observe and theoretically investigate the three spectrum signals versus the probe field as well as the dressing field frequency detunings. Utilizing the experimental results of spectrum signals, the cross phase modulation and the relative position between the weak and strong beams, we analyze the characteristics indicated in the spatial images of probe transmission and FWM, such as focusing or defocusing, shift and splitting in detail. Such studies can be used in all-optical controlled spatial signal transmission.

  11. Knowledge representation model for systems-level analysis of signal transduction networks.

    PubMed

    Lee, Dong-Yup; Zimmer, Ralf; Lee, Sang-Yup; Hanisch, Daniel; Park, Sunwon

    2004-01-01

    A Petri-net based model for knowledge representation has been developed to describe as explicitly and formally as possible the molecular mechanisms of cell signaling and their pathological implications. A conceptual framework has been established for reconstructing and analyzing signal transduction networks on the basis of the formal representation. Such a conceptual framework renders it possible to qualitatively understand the cell signaling behavior at systems-level. The mechanisms of the complex signaling network are explored by applying the established framework to the signal transduction induced by potent proinflammatory cytokines, IL-1beta and TNF-alpha The corresponding expert-knowledge network is constructed to evaluate its mechanisms in detail. This strategy should be useful in drug target discovery and its validation.

  12. Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level

    PubMed Central

    Billings, Curtis J.; Miller, Christi W.; Tremblay, Kelly L.

    2016-01-01

    Purpose This study investigated (a) the effect of amplification on cortical auditory evoked potentials (CAEPs) at different signal levels when signal-to-noise ratios (SNRs) were equated between unaided and aided conditions, and (b) the effect of absolute signal level on aided CAEPs when SNR was held constant. Method CAEPs were recorded from 13 young adults with normal hearing. A 1000-Hz pure tone was presented in unaided and aided conditions with a linear analog hearing aid. Direct audio input was used, allowing recorded hearing aid noise floor to be added to unaided conditions to equate SNRs between conditions. An additional stimulus was created through scaling the noise floor to study the effect of signal level. Results Amplification resulted in delayed N1 and P2 peak latencies relative to the unaided condition. An effect of absolute signal level (when SNR was constant) was present for aided CAEP area measures, such that larger area measures were found at higher levels. Conclusion Results of this study further demonstrate that factors in addition to SNR must also be considered before CAEPs can be used to clinically to measure aided thresholds. PMID:26953543

  13. Hedgehog signalling controls zebrafish neural keel morphogenesis via its level-dependent effects on neurogenesis.

    PubMed

    Takamiya, Masanari; Campos-Ortega, Jose A

    2006-04-01

    We investigated the role of hedgehog (Hh) signalling on zebrafish neurulation, focusing on the intimate relationship between neurogenesis and morphogenesis during the neural keel stage. Through the analyses of Hh loss- and gain-of-function phenotypes, we found that Hh signalling controls the neural keel morphogenesis. To investigate underlying mechanisms, we examined cellular elongation polarity in the neural keel of Hh loss- and gain-of-function phenotypes and compared this with the deficient phenotype of a planar cell polarity (PCP) molecule, Trilobite/Strabismus. We found that Hh signalling controls cell elongation polarity of the neuroepithelium at least in part by means of PCP pathway; however, its effects are not strong enough per se to affect keel morphogenesis; instead Hh signalling mainly controls keel morphogenesis by means of affecting both medial and lateral neurogenesis. We devised a method for precise evaluation of neurogenesis in loss- and gain-of-Hh phenotypes that compensates for its delay caused by disturbed morphogenesis. We present a model that Hh signalling exerts level-dependent and binary-opposite effects on medial neurogenesis, whose modification to explain lateral neurogenesis reveals regional differences of underlying mechanisms between the two proneural domains. Such differences seem to be created in part by regional effector signalling; the effects of high Hh-signalling on medial neurogenesis can be reversed in accordance to medial Tri/Stbm level, in a polarity independent manner.

  14. The neural basis of the blood-oxygen-level-dependent functional magnetic resonance imaging signal.

    PubMed Central

    Logothetis, Nikos K

    2002-01-01

    Magnetic resonance imaging (MRI) has rapidly become an important tool in clinical medicine and biological research. Its functional variant (functional magnetic resonance imaging; fMRI) is currently the most widely used method for brain mapping and studying the neural basis of human cognition. While the method is widespread, there is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity. This paper reviews the basic principles of MRI and fMRI, and subsequently discusses in some detail the relationship between the blood-oxygen-level-dependent (BOLD) fMRI signal and the neural activity elicited during sensory stimulation. To examine this relationship, we conducted the first simultaneous intracortical recordings of neural signals and BOLD responses. Depending on the temporal characteristics of the stimulus, a moderate to strong correlation was found between the neural activity measured with microelectrodes and the BOLD signal averaged over a small area around the microelectrode tips. However, the BOLD signal had significantly higher variability than the neural activity, indicating that human fMRI combined with traditional statistical methods underestimates the reliability of the neuronal activity. To understand the relative contribution of several types of neuronal signals to the haemodynamic response, we compared local field potentials (LFPs), single- and multi-unit activity (MUA) with high spatio-temporal fMRI responses recorded simultaneously in monkey visual cortex. At recording sites characterized by transient responses, only the LFP signal was significantly correlated with the haemodynamic response. Furthermore, the LFPs had the largest magnitude signal and linear systems analysis showed that the LFPs were better than the MUAs at predicting the fMRI responses. These findings, together with an analysis of the neural signals, indicate that the BOLD signal primarily measures the input

  15. R26-WntVis reporter mice showing graded response to Wnt signal levels.

    PubMed

    Takemoto, Tatsuya; Abe, Takaya; Kiyonari, Hiroshi; Nakao, Kazuki; Furuta, Yasuhide; Suzuki, Hitomi; Takada, Shinji; Fujimori, Toshihiko; Kondoh, Hisato

    2016-06-01

    The canonical Wnt signaling pathway plays a major role in the regulation of embryogenesis and organogenesis, where signal strength-dependent cellular responses are of particular importance. To assess Wnt signal levels in individual cells, and to circumvent the integration site-dependent bias shown in previous Wnt reporter lines, we constructed a new Wnt signal reporter mouse line R26-WntVis. Heptameric TCF/LEF1 binding sequences were combined with a viral minimal promoter to confer a graded response to the reporter depending on Wnt signal strengths. The histone H2B-EGFP fusion protein was chosen as the fluorescent reporter to facilitate single-cell resolution analyses. This WntVis reporter gene was then inserted into the ROSA26 locus in an orientation opposite to that of the endogenous gene. The R26-WntVis allele was introduced into Wnt3a(-/-) and Wnt3a(vt/-) mutant mouse embryos and compared with wild-type embryos to assess its performance. The R26-WntVis reporter was activated in known Wnt-dependent tissues and responded in a graded fashion to signal intensity. This analysis also indicated that the major Wnt activity early in embryogenesis switched from Wnt3 to Wnt3a around E7.5. The R26-WntVis mouse line will be widely useful for the study of Wnt signal-dependent processes.

  16. Controlled levels of canonical Wnt signaling are required for neural crest migration.

    PubMed

    Maj, Ewa; Künneke, Lutz; Loresch, Elisabeth; Grund, Anita; Melchert, Juliane; Pieler, Tomas; Aspelmeier, Timo; Borchers, Annette

    2016-09-01

    Canonical Wnt signaling plays a dominant role in the development of the neural crest (NC), a highly migratory cell population that generates a vast array of cell types. Canonical Wnt signaling is required for NC induction as well as differentiation, however its role in NC migration remains largely unknown. Analyzing nuclear localization of β-catenin as readout for canonical Wnt activity, we detect nuclear β-catenin in premigratory but not migratory Xenopus NC cells suggesting that canonical Wnt activity has to decrease to basal levels to enable NC migration. To define a possible function of canonical Wnt signaling in Xenopus NC migration, canonical Wnt signaling was modulated at different time points after NC induction. This was accomplished using either chemical modulators affecting β-catenin stability or inducible glucocorticoid fusion constructs of Lef/Tcf transcription factors. In vivo analysis of NC migration by whole mount in situ hybridization demonstrates that ectopic activation of canonical Wnt signaling inhibits cranial NC migration. Further, NC transplantation experiments confirm that this effect is tissue-autonomous. In addition, live-cell imaging in combination with biophysical data analysis of explanted NC cells confirms the in vivo findings and demonstrates that modulation of canonical Wnt signaling affects the ability of NC cells to perform single cell migration. Thus, our data support the hypothesis that canonical Wnt signaling needs to be tightly controlled to enable migration of NC cells. PMID:27341758

  17. Controlled levels of canonical Wnt signaling are required for neural crest migration.

    PubMed

    Maj, Ewa; Künneke, Lutz; Loresch, Elisabeth; Grund, Anita; Melchert, Juliane; Pieler, Tomas; Aspelmeier, Timo; Borchers, Annette

    2016-09-01

    Canonical Wnt signaling plays a dominant role in the development of the neural crest (NC), a highly migratory cell population that generates a vast array of cell types. Canonical Wnt signaling is required for NC induction as well as differentiation, however its role in NC migration remains largely unknown. Analyzing nuclear localization of β-catenin as readout for canonical Wnt activity, we detect nuclear β-catenin in premigratory but not migratory Xenopus NC cells suggesting that canonical Wnt activity has to decrease to basal levels to enable NC migration. To define a possible function of canonical Wnt signaling in Xenopus NC migration, canonical Wnt signaling was modulated at different time points after NC induction. This was accomplished using either chemical modulators affecting β-catenin stability or inducible glucocorticoid fusion constructs of Lef/Tcf transcription factors. In vivo analysis of NC migration by whole mount in situ hybridization demonstrates that ectopic activation of canonical Wnt signaling inhibits cranial NC migration. Further, NC transplantation experiments confirm that this effect is tissue-autonomous. In addition, live-cell imaging in combination with biophysical data analysis of explanted NC cells confirms the in vivo findings and demonstrates that modulation of canonical Wnt signaling affects the ability of NC cells to perform single cell migration. Thus, our data support the hypothesis that canonical Wnt signaling needs to be tightly controlled to enable migration of NC cells.

  18. R26-WntVis reporter mice showing graded response to Wnt signal levels.

    PubMed

    Takemoto, Tatsuya; Abe, Takaya; Kiyonari, Hiroshi; Nakao, Kazuki; Furuta, Yasuhide; Suzuki, Hitomi; Takada, Shinji; Fujimori, Toshihiko; Kondoh, Hisato

    2016-06-01

    The canonical Wnt signaling pathway plays a major role in the regulation of embryogenesis and organogenesis, where signal strength-dependent cellular responses are of particular importance. To assess Wnt signal levels in individual cells, and to circumvent the integration site-dependent bias shown in previous Wnt reporter lines, we constructed a new Wnt signal reporter mouse line R26-WntVis. Heptameric TCF/LEF1 binding sequences were combined with a viral minimal promoter to confer a graded response to the reporter depending on Wnt signal strengths. The histone H2B-EGFP fusion protein was chosen as the fluorescent reporter to facilitate single-cell resolution analyses. This WntVis reporter gene was then inserted into the ROSA26 locus in an orientation opposite to that of the endogenous gene. The R26-WntVis allele was introduced into Wnt3a(-/-) and Wnt3a(vt/-) mutant mouse embryos and compared with wild-type embryos to assess its performance. The R26-WntVis reporter was activated in known Wnt-dependent tissues and responded in a graded fashion to signal intensity. This analysis also indicated that the major Wnt activity early in embryogenesis switched from Wnt3 to Wnt3a around E7.5. The R26-WntVis mouse line will be widely useful for the study of Wnt signal-dependent processes. PMID:27030109

  19. Study of Signal Detection, Integration, and Propagation in Quorum Sensing at the Single Cell Level

    NASA Astrophysics Data System (ADS)

    Long, Tao; Bassler, Bonnie; Wingreen, Ned

    2007-03-01

    Bacteria respond to their environment and to each other and accordingly adjust their gene-expression levels. Accurate signal detection, appropriate signal integration, and faithful signal propagation are essential for a cell to make correct adjustments in response to various extracellular cues. To better understand this information processing by living cells, we studied a model system -- the quorum-sensing circuit in Vibrio harveyi. Quorum sensing is a process in which bacteria communicate with each other by diffusible chemical molecules, termed ``autoinducers'', to commit to coordinated developmental decisions. Three types of autoinducers are detected coincidently by three parallel receptors. The signals are then integrated into the same signaling pathway and propagated by phosphorylation or dephosphorylation of the pathway components. To quantitatively measure the intracellular response, we applied a fluorescent protein reporter, whose production is regulated by a phosphorylated protein in the pathway. By single-cell microscopy, we can explore features of this information-processing circuit such as coincidence detection, signal integration, noise reduction or filtering, and especially the fidelity in signal processing achieved in the presence of inevitable fluctuations.

  20. Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages

    PubMed Central

    Nagendran, Monica; Arora, Prateek; Gori, Payal; Mulay, Aditya; Ray, Shinjini; Jacob, Tressa; Sonawane, Mahendra

    2015-01-01

    The patterning and morphogenesis of body appendages – such as limbs and fins – is orchestrated by the activities of several developmental pathways. Wnt signalling is essential for the induction of limbs. However, it is unclear whether a canonical Wnt signalling gradient exists and regulates the patterning of epithelium in vertebrate appendages. Using an evolutionarily old appendage – the median fin in zebrafish – as a model, we show that the fin epithelium exhibits graded changes in cellular morphology along the proximo-distal axis. This epithelial pattern is strictly correlated with the gradient of canonical Wnt signalling activity. By combining genetic analyses with cellular imaging, we show that canonical Wnt signalling regulates epithelial cell morphology by modulating the levels of laminins, which are extracellular matrix components. We have unravelled a hitherto unknown mechanism involved in epithelial patterning, which is also conserved in the pectoral fins – evolutionarily recent appendages that are homologous to tetrapod limbs. PMID:25519245

  1. Energy-Efficient Crowdsensing of Human Mobility and Signal Levels in Cellular Networks.

    PubMed

    Foremski, Paweł; Gorawski, Michał; Grochla, Krzysztof; Polys, Konrad

    2015-09-02

    The paper presents a practical application of the crowdsensing idea to measure human mobility and signal coverage in cellular networks. Currently, virtually everyone is carrying a mobile phone, which may be used as a sensor to gather research data by measuring, e.g., human mobility and radio signal levels. However, many users are unwilling to participate in crowdsensing experiments. This work begins with the analysis of the barriers for engaging people in crowdsensing. A survey showed that people who agree to participate in crowdsensing expect a minimum impact on their battery lifetime and phone usage habits. To address these requirements, this paper proposes an application for measuring the location and signal strength data based on energy-efficient GPS tracking, which allows one to perform the measurements of human mobility and radio signal levels with minimum energy utilization and without any engagement of the user. The method described combines measurements from the accelerometer with effective management of the GPS to monitor the user mobility with the decrease in battery lifetime by approximately 20%. To show the applicability of the proposed platform, the sample results of signal level distribution and coverage maps gathered for an LTE network and representing human mobility are shown.

  2. Energy-Efficient Crowdsensing of Human Mobility and Signal Levels in Cellular Networks

    PubMed Central

    Foremski, Paweł; Gorawski, Michał; Grochla, Krzysztof; Polys, Konrad

    2015-01-01

    The paper presents a practical application of the crowdsensing idea to measure human mobility and signal coverage in cellular networks. Currently, virtually everyone is carrying a mobile phone, which may be used as a sensor to gather research data by measuring, e.g., human mobility and radio signal levels. However, many users are unwilling to participate in crowdsensing experiments. This work begins with the analysis of the barriers for engaging people in crowdsensing. A survey showed that people who agree to participate in crowdsensing expect a minimum impact on their battery lifetime and phone usage habits. To address these requirements, this paper proposes an application for measuring the location and signal strength data based on energy-efficient GPS tracking, which allows one to perform the measurements of human mobility and radio signal levels with minimum energy utilization and without any engagement of the user. The method described combines measurements from the accelerometer with effective management of the GPS to monitor the user mobility with the decrease in battery lifetime by approximately 20%. To show the applicability of the proposed platform, the sample results of signal level distribution and coverage maps gathered for an LTE network and representing human mobility are shown. PMID:26340633

  3. Comparing Infants' Preference for Correlated Audiovisual Speech with Signal-Level Computational Models

    ERIC Educational Resources Information Center

    Hollich, George; Prince, Christopher G.

    2009-01-01

    How much of infant behaviour can be accounted for by signal-level analyses of stimuli? The current paper directly compares the moment-by-moment behaviour of 8-month-old infants in an audiovisual preferential looking task with that of several computational models that use the same video stimuli as presented to the infants. One type of model…

  4. Nerves Control Redox Levels in Mature Tissues Through Schwann Cells and Hedgehog Signaling

    PubMed Central

    Meda, Francesca; Gauron, Carole; Rampon, Christine; Teillon, Jérémie; Volovitch, Michel

    2016-01-01

    Abstract Aims: Recent advances in redox biology have emphasized the role of hydrogen peroxide (H2O2) in the modulation of signaling pathways and revealed that H2O2 plays a role in cellular remodeling in adults. Thus, an understanding of the mechanisms that control H2O2 levels in mature tissue would be of great interest. Results: We used a denervation strategy to demonstrate that sensory neurons are responsible for controlling H2O2 levels under normal conditions and after being lesioned. Moreover, we demonstrate that severed nerves respond to appendage amputation via the induction of Hedgehog signaling and that this signaling is responsible for H2O2 production in the wounded epidermis. Finally, we show that H2O2 and nerve growth are regulated via reciprocal action in adults. Innovation and Conclusion: These data support a new paradigm for the regulation of tissue homeostasis: H2O2 attracts nerves and nerves control H2O2 levels in a positive feedback loop. This finding suggests that the peripheral nerve redox environment could be a target for manipulating cell plasticity in adults. Antioxid. Redox Signal. 24, 299–311. PMID:26442784

  5. Ultrasensitive electrochemical aptasensor for ochratoxin A based on two-level cascaded signal amplification strategy.

    PubMed

    Yang, Xingwang; Qian, Jing; Jiang, Ling; Yan, Yuting; Wang, Kan; Liu, Qian; Wang, Kun

    2014-04-01

    Ochratoxin A (OTA) has a number of toxic effects to both humans and animals, so developing sensitive detection method is of great importance. Herein, we describe an ultrasensitive electrochemical aptasensor for OTA based on the two-level cascaded signal amplification strategy with methylene blue (MB) as a redox indicator. In this method, capture DNA, aptamers, and reporter DNA functionalized-gold nanoparticles (GNPs) were immobilized on the electrode accordingly, where GNPs were used as the first-level signal enhancer. To receive the more sensitive response, a larger number of guanine (G)-rich DNA was bound to the GNPs' surface to provide abundant anchoring sites for MB to achieve the second-level signal amplification. By employing this novel strategy, an ~8.5 (±0.3) fold amplification in signal intensity was obtained. Afterward, OTA was added to force partial GNPs/G-rich DNA to release from the sensing interface and thus decreased the electrochemical response. An effective sensing range from 2.5pM to 2.5nM was received with an extremely low detection limit of 0.75 (±0.12) pM. This amplification strategy has the potential to be the main technology for aptamer-based electrochemical biosensor in a variety of fields.

  6. Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

    PubMed

    Astafiev, Serguei V; Shulman, Gordon L; Metcalf, Nicholas V; Rengachary, Jennifer; MacDonald, Christine L; Harrington, Deborah L; Maruta, Jun; Shimony, Joshua S; Ghajar, Jamshid; Diwakar, Mithun; Huang, Ming-Xiong; Lee, Roland R; Corbetta, Maurizio

    2015-08-15

    Concussion, or mild traumatic brain injury (mTBI), can cause persistent behavioral symptoms and cognitive impairment, but it is unclear if this condition is associated with detectable structural or functional brain changes. At two sites, chronic mTBI human subjects with persistent post-concussive symptoms (three months to five years after injury) and age- and education-matched healthy human control subjects underwent extensive neuropsychological and visual tracking eye movement tests. At one site, patients and controls also performed the visual tracking tasks while blood-oxygen-level-dependent (BOLD) signals were measured with functional magnetic resonance imaging. Although neither neuropsychological nor visual tracking measures distinguished patients from controls at the level of individual subjects, abnormal BOLD signals were reliably detected in patients. The most consistent changes were localized in white matter regions: anterior internal capsule and superior longitudinal fasciculus. In contrast, BOLD signals were normal in cortical regions, such as the frontal eye field and intraparietal sulcus, that mediate oculomotor and attention functions necessary for visual tracking. The abnormal BOLD signals accurately differentiated chronic mTBI patients from healthy controls at the single-subject level, although they did not correlate with symptoms or neuropsychological performance. We conclude that subjects with persistent post-concussive symptoms can be identified years after their TBI using fMRI and an eye movement task despite showing normal structural MRI and DTI.

  7. Caffeine and REM sleep deprivation: Effect on basal levels of signaling molecules in area CA1.

    PubMed

    Alkadhi, Karim A; Alhaider, Ibrahim A

    2016-03-01

    We have investigated the neuroprotective effect of chronic caffeine treatment on basal levels of memory-related signaling molecules in area CA1 of sleep-deprived rats. Animals in the caffeine groups were treated with caffeine in drinking water (0.3g/l) for four weeks before they were REM sleep-deprived for 24h in the Modified Multiple Platforms paradigm. Western blot analysis of basal protein levels of plasticity- and memory-related signaling molecules in hippocampal area CA1 showed significant down regulation of the basal levels of phosphorylated- and total-CaMKII, phosphorylated- and total-CREB as well as those of BDNF and CaMKIV in sleep deprived rats. All these changes were completely prevented in rats that chronically consumed caffeine. The present findings suggest an important neuroprotective property of caffeine in sleep deprivation.

  8. Caffeine and REM sleep deprivation: Effect on basal levels of signaling molecules in area CA1.

    PubMed

    Alkadhi, Karim A; Alhaider, Ibrahim A

    2016-03-01

    We have investigated the neuroprotective effect of chronic caffeine treatment on basal levels of memory-related signaling molecules in area CA1 of sleep-deprived rats. Animals in the caffeine groups were treated with caffeine in drinking water (0.3g/l) for four weeks before they were REM sleep-deprived for 24h in the Modified Multiple Platforms paradigm. Western blot analysis of basal protein levels of plasticity- and memory-related signaling molecules in hippocampal area CA1 showed significant down regulation of the basal levels of phosphorylated- and total-CaMKII, phosphorylated- and total-CREB as well as those of BDNF and CaMKIV in sleep deprived rats. All these changes were completely prevented in rats that chronically consumed caffeine. The present findings suggest an important neuroprotective property of caffeine in sleep deprivation. PMID:26767416

  9. Signal window minimum average error algorithm for multi-phase level computer-generated holograms

    NASA Astrophysics Data System (ADS)

    El Bouz, Marwa; Heggarty, Kevin

    2000-06-01

    This paper extends the article "Signal window minimum average error algorithm for computer-generated holograms" (JOSA A 1998) to multi-phase level CGHs. We show that using the same rule for calculating the complex error diffusion weights, iterative-algorithm-like low-error signal windows can be obtained for any window shape or position (on- or off-axis) and any number of CGH phase levels. Important algorithm parameters such as amplitude normalisation level and phase freedom diffusers are described and investigated to optimize the algorithm. We show that, combined with a suitable diffuser, the algorithm makes feasible the calculation of high performance CGHs far larger than currently practical with iterative algorithms yet now realisable with modern fabrication techniques. Preliminary experimental optical reconstructions are presented.

  10. The vacuolar-ATPase inhibitor bafilomycin and mutant VPS35 inhibit canonical Wnt signaling.

    PubMed

    George, Ana; Leahy, Hannah; Zhou, Jianhua; Morin, Peter J

    2007-04-01

    Endosomal acidification and transport are essential functions in signal transduction. Recent data suggest that Wnt signaling requires intact endosomal transport machinery but the effects of endosomal acidification on Wnt signal transduction have not been evaluated. Here we report that bafilomycin, a specific inhibitor of the vacuolar proton ATPase that blocks endosomal acidification, inhibits canonical Wnt signal transduction initiated by Wnt ligand and partially inhibits signaling initiated by disheveled. Bafilomycin does not affect Tcf promoter activation by beta-catenin. These data indicate that endosomal acidification is necessary for Wnt signaling. To identify interactions between endosomal transport proteins and Wnt receptors, we performed a GST fusion protein pulldown experiment and identified a possible indirect interaction between the LRP6 intracellular domain and vacuolar protein sorting protein 35 (VPS35). We show that an N-terminal deletion mutant of VPS35 reduces canonical Wnt signaling in HEK-293 cells expressing exogenous Wnt-1. These data suggest that endosomal V-type ATPase activity and retromer trafficking proteins are functionally important in Wnt signal transduction. PMID:17239604

  11. Receptor for advanced glycation end products inhibits proliferation in osteoblast through suppression of Wnt, PI3K and ERK signaling

    SciTech Connect

    Li, Guofeng; Xu, Jingren; Li, Zengchun

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer RAGE overexpression suppresses cell proliferation in MC3T3-E1 cells. Black-Right-Pointing-Pointer RAGE overexpression decreases Wnt/{beta}-catenin signaling. Black-Right-Pointing-Pointer RAGE overexpression decreases ERK and PI3K signaling. Black-Right-Pointing-Pointer Inhibition of Wnt signaling abolishes PI3K signaling restored by RAGE blockade. Black-Right-Pointing-Pointer Inhibition of Wnt signaling abolishes ERK signaling restored by RAGE blockade. -- Abstract: Expression of receptor for advanced glycation end products (RAGE) plays a crucial role in bone metabolism. However, the role of RAGE in the control of osteoblast proliferation is not yet evaluated. In the present study, we demonstrate that RAGE overexpression inhibits osteoblast proliferation in vitro. The negative regulation of RAGE on cell proliferation results from suppression of Wnt, PI3K and ERK signaling, and is restored by RAGE neutralizing antibody. Prevention of Wnt signaling using Sfrp1 or DKK1 rescues RAGE-decreased PI3K and ERK signaling and cell proliferation, indicating that the altered cell growth in RAGE overexpressing cells is in part secondary to alterations in Wnt signaling. Consistently, RAGE overexpression inhibits the expression of Wnt targets cyclin D1 and c-myc, which is partially reversed by RAGE blockade. Overall, these results suggest that RAGE inhibits osteoblast proliferation via suppression of Wnt, PI3K and ERK signaling, which provides novel mechanisms by which RAGE regulates osteoblast growth.

  12. Phylogenetic diversity and co-evolutionary signals among trophic levels change across a habitat edge.

    PubMed

    Peralta, Guadalupe; Frost, Carol M; Didham, Raphael K; Varsani, Arvind; Tylianakis, Jason M

    2015-03-01

    Incorporating the evolutionary history of species into community ecology enhances understanding of community composition, ecosystem functioning and responses to environmental changes. Phylogenetic history might partly explain the impact of fragmentation and land-use change on assemblages of interacting organisms and even determine potential cascading effects across trophic levels. However, it remains unclear whether phylogenetic diversity of basal resources is reflected at higher trophic levels in the food web. In particular, phylogenetic determinants of community structure have never been incorporated into habitat edge studies, even though edges are recognized as key factors affecting communities in fragmented landscapes. Here, we test whether phylogenetic diversity at different trophic levels (plants, herbivores and parasitoids) and signals of co-evolution (i.e. phylogenetic congruence) among interacting trophic levels change across an edge gradient between native and plantation forests. To ascertain whether there is a signal of co-evolution across trophic levels, we test whether related consumer species generally feed on related resource species. We found differences across trophic levels in how their phylogenetic diversity responded to the habitat edge gradient. Plant and native parasitoid phylogenetic diversity changed markedly across habitats, while phylogenetic variability of herbivores (which were predominantly native) did not change across habitats, though phylogenetic evenness declined in plantation interiors. Related herbivore species did not appear to feed disproportionately on related plant species (i.e. there was no signal of co-evolution) even when considering only native species, potentially due to the high trophic generality of herbivores. However, related native parasitoid species tended to feed on related herbivore species, suggesting the presence of a co-evolutionary signal at higher trophic levels. Moreover, this signal was stronger in

  13. Phylogenetic diversity and co-evolutionary signals among trophic levels change across a habitat edge.

    PubMed

    Peralta, Guadalupe; Frost, Carol M; Didham, Raphael K; Varsani, Arvind; Tylianakis, Jason M

    2015-03-01

    Incorporating the evolutionary history of species into community ecology enhances understanding of community composition, ecosystem functioning and responses to environmental changes. Phylogenetic history might partly explain the impact of fragmentation and land-use change on assemblages of interacting organisms and even determine potential cascading effects across trophic levels. However, it remains unclear whether phylogenetic diversity of basal resources is reflected at higher trophic levels in the food web. In particular, phylogenetic determinants of community structure have never been incorporated into habitat edge studies, even though edges are recognized as key factors affecting communities in fragmented landscapes. Here, we test whether phylogenetic diversity at different trophic levels (plants, herbivores and parasitoids) and signals of co-evolution (i.e. phylogenetic congruence) among interacting trophic levels change across an edge gradient between native and plantation forests. To ascertain whether there is a signal of co-evolution across trophic levels, we test whether related consumer species generally feed on related resource species. We found differences across trophic levels in how their phylogenetic diversity responded to the habitat edge gradient. Plant and native parasitoid phylogenetic diversity changed markedly across habitats, while phylogenetic variability of herbivores (which were predominantly native) did not change across habitats, though phylogenetic evenness declined in plantation interiors. Related herbivore species did not appear to feed disproportionately on related plant species (i.e. there was no signal of co-evolution) even when considering only native species, potentially due to the high trophic generality of herbivores. However, related native parasitoid species tended to feed on related herbivore species, suggesting the presence of a co-evolutionary signal at higher trophic levels. Moreover, this signal was stronger in

  14. Carotenoid-dependent signals and the evolution of plasma carotenoid levels in birds.

    PubMed

    Simons, Mirre J P; Maia, Rafael; Leenknegt, Bas; Verhulst, Simon

    2014-12-01

    Sexual selection has resulted in a wide array of ornaments used in mate choice, and such indicator traits signal quality honestly when they bear costs, precluding cheating. Carotenoid-dependent coloration has attracted considerable attention in this context, because investing carotenoids in coloration has to be traded off against its physiological functions; carotenoids are antioxidants and increase immunocompetence. This trade-off is hypothesized to underlie the honesty of carotenoid-dependent coloration, signaling the "handicap" of allocating carotenoids away from somatic maintenance toward sexual display. Utilizing recent advances in modeling adaptive evolution, we used a comparative approach to investigate the evolution of plasma carotenoid levels using a species-level phylogeny of 178 bird species. We find that the evolutionary optimum for carotenoid levels is higher in lineages that evolved carotenoid-dependent coloration, with strong attraction toward this optimum. Hence, carotenoids do not appear to be limiting, given that higher carotenoid levels readily evolve in response to the evolution of carotenoid-dependent coloration. These findings challenge the assumption that carotenoids are a scarce resource and thus also challenge the hypothesis that physiological resource value of carotenoids underlies honesty of carotenoid-dependent traits. Therefore, the comparative evidence suggests that other factors, such as the acquisition and incorporation of carotenoids, are involved in maintaining signal honesty.

  15. A microchip platform for interrogating tumor-macrophage paracrine signaling at the single-cell level.

    PubMed

    Elitas, Meltem; Brower, Kara; Lu, Yao; Chen, Jonathan J; Fan, Rong

    2014-09-21

    It is increasingly recognized that infiltrating immune cells contribute to the pathogenesis of a wide range of solid tumors. The paracrine signaling between the tumor and the immune cells alters the functional state of individual tumor cells and, correspondingly, the anticipated response to radiation or chemotherapies, which is of great importance to clinical oncology. Here we present a high-density microchip platform capable of measuring a panel of paracrine signals associated with heterotypic tumor-immune cell interactions in the single-cell, pair-wise manner. The device features a high-content cell capture array of 5000+ sub-nanoliter microchambers for the isolation of single and multi-cell combinations and a multi-plex antibody "barcode" array for multiplexed protein secretion analysis from each microchamber. In this work, we measured a panel of 16 proteins produced from individual glioma cells, individual macrophage cells and varying heterotypic multi-cell combinations of both on the same device. The results show changes of tumor cell functional phenotypes that cannot be explained by an additive effect from isolated single cells and, presumably, can be attributed to the paracrine signaling between macrophage and glioma cells. The protein correlation analysis reveals the key signaling nodes altered by tumor-macrophage communication. This platform enables the novel pair-wise interrogation of heterotypic cell-cell paracrine signaling at the individual cell level with an in-depth analysis of the changing functional phenotypes for different co-culture cell combinations.

  16. Psychotropic drugs have contrasting skeletal effects that are independent of their effects on physical activity levels.

    PubMed

    Warden, Stuart J; Hassett, Sean M; Bond, Julie L; Rydberg, Johanna; Grogg, Jamie D; Hilles, Erin L; Bogenschutz, Elizabeth D; Smith, Heather D; Fuchs, Robyn K; Bliziotes, M Michael; Turner, Charles H

    2010-04-01

    disorders. Likewise, the anabolic effect of GSK-3[beta] inhibition using lithium reconfirms the importance of Wnt/beta-catenin signaling in the skeleton and it's targeting by recent drug discovery efforts. In conclusion, the current study demonstrates that different psychotropic drugs with differing underlying mechanisms of action have contrasting skeletal effects and that these effects do not result indirectly via the generation of animal physical inactivity.

  17. Crack Level Estimation Approach for Planetary Gear Sets Based on Simulation Signal and GRA

    NASA Astrophysics Data System (ADS)

    Cheng, Zhe; Hu, Niaoqing; Zuo, Mingjian; Fan, Bin

    2012-05-01

    The planetary gearbox is a critical mechanism in helicopter transmission systems. Tooth failures in planetary gear sets will cause great risk to helicopter operations. A crack level estimation methodology has been devised in this paper by integrating a physical model for simulation signal generation and a grey relational analysis (GRA) algorithm for damage level estimation. The proposed method was calibrated firstly with fault seeded test data and then validated with the data of other tests from a helicopter transmission test rig. The estimation results of test data coincide with the actual test records, showing the effectiveness and accuracy of the method in providing a novel way to hybrid model based methods and signal analysis methods for more accurate health monitoring and condition prediction.

  18. Wnt induction of chondrocyte hypertrophy through the Runx2 transcription factor.

    PubMed

    Dong, Yu-Feng; Soung, Do Y; Schwarz, Edward M; O'Keefe, Regis J; Drissi, Hicham

    2006-07-01

    We investigated the molecular mechanisms underlying canonical Wnt-mediated regulation of chondrocyte hypertrophy using chick upper sternal chondrocytes. Replication competent avian sarcoma (RCAS) viral over-expression of Wnt8c and Wnt9a, upregulated type X collagen (col10a1) and Runx2 mRNA expression thereby inducing chondrocyte hypertrophy. Wnt8c and Wnt9a strongly inhibited mRNA levels of Sox9 and type II collagen (col2a1). Wnt8c further enhanced canonical bone morphogenetic proteins (BMP-2)-induced expression of Runx2 and col10a1 while Wnt8c and Wnt9a inhibited TGF-beta-induced expression of Sox9 and col2a1. Over-expression of beta-catenin mimics the effect of Wnt8c and Wnt9a by upregulating Runx2, col10a1, and alkaline phosphatase (AP) mRNA levels while it inhibits col2a1 transcription. Western blot analysis shows that Wnt8c and beta-catenin also induces Runx2 protein levels in chondrocytes. Thus, our results indicate that activation of the canonical beta-catenin Wnt signaling pathway induces chondrocyte hypertrophy and maturation. We further investigated the effects of beta-catenin-TCF/Lef on Runx2 promoter. Co-transfection of lymphoid enhancer factor (Lef1) and beta-catenin in chicken upper sternal chondrocytes together with deletion constructs of the Runx2 promoter shows that the proximal region spanning the first 128 base pairs of this promoter is responsible for the Wnt-mediated induction of Runx2. Mutation of the TCF/Lef binding site in the -128 fragment of the Runx2 promoter resulted in loss of its responsiveness to beta-catenin. Additionally, gel-shift assay analyses determined the DNA/protein interaction of the TCF/Lef binding sites on the Runx2 promoter. Finally, our site-directed mutagenesis data demonstrated that the Runx2 site on type X collagen promoter is required for canonical Wnt induction of col10a1. Altogether we demonstrate that Wnt/beta-catenin signaling is regulated by TGF-beta and BMP-2 in chick upper sternal chondrocytes, and mediates

  19. Electroencephalograph (EEG) signal processing method of motor imaginary potential for attention level classification.

    PubMed

    Ming, Dong; Xi, Youyuan; Zhang, Mingming; Qi, Hongzhi; Cheng, Longlong; Wan, Baikun; Li, Liyong

    2009-01-01

    Research of visual attention is one of the important domains of psychology and neurophysiology. In this study, an attention related electroencephalograph (EEG) signal processing method was proposed to distinguish the different levels of people's attention during the imaginary limbs motor. There were two EEG feedback experiments (playing tennis and walking) to measure the different levels of visual attention. Three imaginary motor tasks (attention, inattention, and rest task) were performed with the flash stimulus displayed on the screen in the experiments. A nonlinear dynamics parameter of multi-scale entropy (MSE) was extracted from those EEG data recorded. According to the statistics analysis of 14 subjects, there was an obvious declining tendency of MSE with the level of attention declining, which validated the effectiveness of the proposed method to classify the visual attention level.

  20. Note: Improving low-light-level image detection sensitivity with higher speed using auxiliary sinusoidal light signal.

    PubMed

    Tang, Hongying; Yu, Zhengtao

    2015-06-01

    An improved active imaging method, which upgraded the detection sensitivity by applying an auxiliary sawtooth wave light signal, was reported. Nevertheless, such method sacrificed the imaging speed. To speed up imaging, a sinusoidal light signal is used instead and superposed with the undetectable low-light-level signal on the image sensor. After acquiring a superimposed image set in one sine wave cycle, an unbiased low-light-level image estimation is obtained by using least-square optimization. Through probabilistic analysis and experimental study, we demonstrate that the sinusoidal signal could improve the detection sensitivity 1/3 faster than the sawtooth wave signal.

  1. Note: Improving low-light-level image detection sensitivity with higher speed using auxiliary sinusoidal light signal

    NASA Astrophysics Data System (ADS)

    Tang, Hongying; Yu, Zhengtao

    2015-06-01

    An improved active imaging method, which upgraded the detection sensitivity by applying an auxiliary sawtooth wave light signal, was reported. Nevertheless, such method sacrificed the imaging speed. To speed up imaging, a sinusoidal light signal is used instead and superposed with the undetectable low-light-level signal on the image sensor. After acquiring a superimposed image set in one sine wave cycle, an unbiased low-light-level image estimation is obtained by using least-square optimization. Through probabilistic analysis and experimental study, we demonstrate that the sinusoidal signal could improve the detection sensitivity 1/3 faster than the sawtooth wave signal.

  2. FIPSER: Performance study of a readout concept with few digitization levels for fast signals

    NASA Astrophysics Data System (ADS)

    Limyansky, B.; Reese, R.; Cressler, J. D.; Otte, A. N.; Taboada, I.; Ulusoy, C.

    2016-11-01

    We discuss the performance of a readout system, Fixed Pulse Shape Efficient Readout (FIPSER), to digitize signals from detectors with a fixed pulse shape. In this study we are mainly interested in the readout of fast photon detectors like photomultipliers or Silicon photomultipliers. But the concept can be equally applied to the digitization of other detector signals. FIPSER is based on the flash analog to digital converter (FADC) concept, but has the potential to lower costs and power consumption by using an order of magnitude fewer discrete voltage levels. Performance is bolstered by combining the discretized signal with the knowledge of the underlying pulse shape. Simulated FIPSER data was reconstructed with two independent methods. One using a maximum likelihood method and the other using a modified χ2 test. Both methods show that utilizing 12 discrete voltage levels with a sampling rate of 4 samples per full width half maximum (FWHM) of the pulse achieves an amplitude resolution that is better than the Poisson limit for photon-counting experiments. The time resolution achieved in this configuration ranges between 0.02 and 0.16 FWHM and depends on the pulse amplitude. In a situation where the waveform is composed of two consecutive pulses the pulses can be separated if they are at least 0.05-0.30 FWHM apart with an amplitude resolution that is better than 20%.

  3. Ethylene Regulates Levels of Ethylene Receptor/CTR1 Signaling Complexes in Arabidopsis thaliana.

    PubMed

    Shakeel, Samina N; Gao, Zhiyong; Amir, Madiha; Chen, Yi-Feng; Rai, Muneeza Iqbal; Haq, Noor Ul; Schaller, G Eric

    2015-05-01

    The plant hormone ethylene is perceived by a five-member family of receptors in Arabidopsis thaliana. The receptors function in conjunction with the Raf-like kinase CTR1 to negatively regulate ethylene signal transduction. CTR1 interacts with multiple members of the receptor family based on co-purification analysis, interacting more strongly with receptors containing a receiver domain. Levels of membrane-associated CTR1 vary in response to ethylene, doing so in a post-transcriptional manner that correlates with ethylene-mediated changes in levels of the ethylene receptors ERS1, ERS2, EIN4, and ETR2. Interactions between CTR1 and the receptor ETR1 protect ETR1 from ethylene-induced turnover. Kinetic and dose-response analyses support a model in which two opposing factors control levels of the ethylene receptor/CTR1 complexes. Ethylene stimulates the production of new complexes largely through transcriptional induction of the receptors. However, ethylene also induces turnover of receptors, such that levels of ethylene receptor/CTR1 complexes decrease at higher ethylene concentrations. Implications of this model for ethylene signaling are discussed.

  4. Wnt5a signaling is a substantial constituent in bone morphogenetic protein-2-mediated osteoblastogenesis

    SciTech Connect

    Nemoto, Eiji; Ebe, Yukari; Kanaya, Sousuke; Tsuchiya, Masahiro; Nakamura, Takashi; Tamura, Masato; Shimauchi, Hidetoshi

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Wnt5a is identified in osteoblasts in tibial growth plate and bone marrow. Black-Right-Pointing-Pointer Osteoblastic differentiation is associated with increased expression of Wnt5a/Ror2. Black-Right-Pointing-Pointer Wnt5a/Ror2 signaling is important for BMP-2-mediated osteoblastic differentiation. Black-Right-Pointing-Pointer Wnt5a/Ror2 operates independently of BMP-Smad pathway. -- Abstract: Wnts are secreted glycoproteins that mediate developmental and post-developmental physiology by regulating cellular processes including proliferation, differentiation, and apoptosis through {beta}-catenin-dependent canonical and {beta}-catenin-independent noncanonical pathway. It has been reported that Wnt5a activates noncanonical Wnt signaling through receptor tyrosine kinase-like orphan receptor 2 (Ror2). Although it appears that Wnt5a/Ror2 signaling supports normal bone physiology, the biological significance of noncanonical Wnts in osteogenesis is essentially unknown. In this study, we identified expression of Wnt5a in osteoblasts in the ossification zone of the tibial growth plate as well as bone marrow of the rat tibia as assessed by immunohistochemistry. In addition, we show that osteoblastic differentiation mediated by BMP-2 is associated with increased expression of Wnt5a and Ror2 using cultured pre-osteoblasts, MC3T3-E1 cells. Silencing gene expression of Wnt5a and Ror2 in MC3T3-E1 cells results in suppression of BMP-2-mediated osteoblastic differentiation, suggesting that Wnt5a and Ror2 signaling are of substantial importance for BMP-2-mediated osteoblastic differentiation. BMP-2 stimulation induced phosphorylation of Smad1/5/8 in a similar fashion in both siWnt5a-treated cells and control cells, suggesting that Wnt5a was dispensable for the phosphorylation of Smads by BMP-2. Taken together, our results suggest that Wnt5a/Ror2 signaling appears to be involved in BMP-2-mediated osteoblast differentiation in a Smad independent

  5. SPX proteins regulate Pi homeostasis and signaling in different subcellular level.

    PubMed

    Zhou, Zhipeng; Wang, Zhiye; Lv, Qundan; Shi, Jing; Zhong, Yongjia; Wu, Ping; Mao, Chuanzao

    2015-01-01

    To cope with low phosphate (Pi) availability, plants have to adjust its gene expression profile to facilitate Pi acquisition and remobilization. Sensing the levels of Pi is essential for reprogramming the gene expression profile to adapt to the fluctuating Pi environment. AtPHR1 in Arabidopsis and OsPHR2 in rice are central regulators of Pi signaling, which regulates the expression of phosphate starvation-induced (PSI) genes by binding to the P1BS elements in the promoter of PSI genes. However, how the Pi level affects the central regulator to regulate the PSI genes have puzzled us for a decade. Recent progress in SPX proteins indicated that the SPX proteins play important role in regulating the activity of central regulator AtPHR1/OsPHR2 in a Pi dependent manner at different subcellular levels.

  6. Current and sea-level signals in periplatform ooze (Neogene, Maldives, Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Betzler, Christian; Lüdmann, Thomas; Hübscher, Christian; Fürstenau, Jörn

    2013-05-01

    Periplatform ooze is an admixture of pelagic carbonate and sediment derived from neritic carbonate platforms. Compositional variations of periplatform ooze allow the reconstruction of past sea-level changes. Periplatform ooze formed during sea-level highstands is finer grained and richer in aragonite through the elevated input of material from the flooded platform compared to periplatform ooze formed during the episodes of lowered sea level. In many cases, however, the sea floor around carbonate platforms is subjected to bottom currents which are expected to affect sediment composition, i.e. through winnowing of the fine fraction. The interaction of sea-level driven highstand shedding and current impact on the formation of periplatform ooze has hitherto not been analyzed. To test if a sea-level driven input signal in periplatform ooze is influenced or even distorted by changing current activity, an integrated study using seismic, hydroacoustic and sedimentological data has been performed on periplatform ooze deposited in the Inner Sea of the Maldives. The Miocene to Pleistocene succession of drift deposits is subdivided into nine units; limits of seismostratigraphic units correspond to changes or turnarounds in grain size trends in cores recovered at ODP Site 716 and NEOMA Site 1143. For the Pleistocene it can be shown how changes in grain size occur in concert with sea-level changes and changes of the monsoonal system, which is thought to be a major driver of bottom currents in the Maldives. A clear highstand shedding pattern only appears in the data at a time of relaxation of monsoonal strength during the last 315 ky. Results imply (1) that drift sediments provide a potential target for analyzing past changes in oceanic currents and (2) that the ooze composition bears a mixed signal of input and physical winnowing at the sea floor.

  7. Three months of local sea level derived from reflected GNSS signals

    NASA Astrophysics Data System (ADS)

    LöFgren, J. S.; Haas, R.; Scherneck, H.-G.; Bos, M. S.

    2011-12-01

    By receiving Global Navigation Satellite System (GNSS) signals that are reflected off the sea surface, together with directly received GNSS signals (using standard geodetic-type receivers), it is possible to monitor the sea level using regular single difference geodetic processing. We show results from our analysis of three months of data from the GNSS-based tide gauge at the Onsala Space Observatory (OSO) on the west coast of Sweden. The GNSS-derived time series of local sea level is compared with independent data from two stilling well gauges at Ringhals and Gothenburg about 18 km south and 33 km north of OSO, respectively. A high degree of agreement is found in the time domain, with correlation coefficients of up to 0.96. The root-mean-square differences between the GNSS-derived sea level and the stilling well gauge observations are 5.9 cm and 5.5 cm, which is lower than for the stilling well gauges together (6.1 cm). A frequency domain comparison reveals high coherence of the data sets up to 6 cycles per day, which corresponds well to the propagation of gravity waves in the shallow waters at the Kattegat coast. Amplitudes and phases of some major tides were determined by a tidal harmonic analysis and compared to model predictions. From the GNSS-based tide gauge results we find significant ocean tidal signals at fortnightly, diurnal, semi-diurnal, and quarter-diurnal periods. As an example, the amplitudes of the semi-diurnal M2 and the diurnal O1 tide are determined with 1σ uncertainties of 11 mm and 12 mm, respectively. The comparison to model calculations shows that global ocean tide models have limited accuracy in the Kattegat area.

  8. Anomalous ocean load tide signal observed in lake-level variations in Tierra del Fuego

    NASA Astrophysics Data System (ADS)

    Richter, A.; Hormaechea, J. L.; Dietrich, R.; Perdomo, R.; Fritsche, M.; Del Cogliano, D.; Liebsch, G.; Mendoza, L.

    2009-03-01

    We demonstrate the application of a 100 km long lake as a sensor for studying the tidal effects on Tierra del Fuego main island. The lake-level variations observed in Lago Fagnano reflect both the direct response to the tidal potential and the indirect effect of the ocean tidal loading. Modeling both contributions explains the observed tidal signal in the lake to about 70%. Underestimated model load tide amplitudes are found to be probably responsible for the remaining difference. We interpret this discrepancy as a hint for regional elastic lithosphere properties differing substantially from those represented by currently available global models.

  9. Identification and validation of genetic variants that influence transcription factor and cell signaling protein levels.

    PubMed

    Hause, Ronald J; Stark, Amy L; Antao, Nirav N; Gorsic, Lidija K; Chung, Sophie H; Brown, Christopher D; Wong, Shan S; Gill, Daniel F; Myers, Jamie L; To, Lida Anita; White, Kevin P; Dolan, M Eileen; Jones, Richard Baker

    2014-08-01

    Many genetic variants associated with human disease have been found to be associated with alterations in mRNA expression. Although it is commonly assumed that mRNA expression changes will lead to consequent changes in protein levels, methodological challenges have limited our ability to test the degree to which this assumption holds true. Here, we further developed the micro-western array approach and globally examined relationships between human genetic variation and cellular protein levels. We collected more than 250,000 protein level measurements comprising 441 transcription factor and signaling protein isoforms across 68 Yoruba (YRI) HapMap lymphoblastoid cell lines (LCLs) and identified 12 cis and 160 trans protein level QTLs (pQTLs) at a false discovery rate (FDR) of 20%. Whereas up to two thirds of cis mRNA expression QTLs (eQTLs) were also pQTLs, many pQTLs were not associated with mRNA expression. Notably, we replicated and functionally validated a trans pQTL relationship between the KARS lysyl-tRNA synthetase locus and levels of the DIDO1 protein. This study demonstrates proof of concept in applying an antibody-based microarray approach to iteratively measure the levels of human proteins and relate these levels to human genome variation and other genomic data sets. Our results suggest that protein-based mechanisms might functionally buffer genetic alterations that influence mRNA expression levels and that pQTLs might contribute phenotypic diversity to a human population independently of influences on mRNA expression.

  10. Nitrogen oxide cycle regulates nitric oxide levels and bacterial cell signaling

    PubMed Central

    Sasaki, Yasuyuki; Oguchi, Haruka; Kobayashi, Takuya; Kusama, Shinichiro; Sugiura, Ryo; Moriya, Kenta; Hirata, Takuya; Yukioka, Yuriya; Takaya, Naoki; Yajima, Shunsuke; Ito, Shinsaku; Okada, Kiyoshi; Ohsawa, Kanju; Ikeda, Haruo; Takano, Hideaki; Ueda, Kenji; Shoun, Hirofumi

    2016-01-01

    Nitric oxide (NO) signaling controls various metabolic pathways in bacteria and higher eukaryotes. Cellular enzymes synthesize and detoxify NO; however, a mechanism that controls its cellular homeostasis has not been identified. Here, we found a nitrogen oxide cycle involving nitrate reductase (Nar) and the NO dioxygenase flavohemoglobin (Fhb), that facilitate inter-conversion of nitrate, nitrite, and NO in the actinobacterium Streptomyces coelicolor. This cycle regulates cellular NO levels, bacterial antibiotic production, and morphological differentiation. NO down-regulates Nar and up-regulates Fhb gene expression via the NO-dependent transcriptional factors DevSR and NsrR, respectively, which are involved in the auto-regulation mechanism of intracellular NO levels. Nitrite generated by the NO cycles induces gene expression in neighboring cells, indicating an additional role of the cycle as a producer of a transmittable inter-cellular communication molecule. PMID:26912114

  11. Crack level estimation approach for planetary gearbox based on simulation signal and GRA

    NASA Astrophysics Data System (ADS)

    Cheng, Zhe; Hu, Niaoqing; Zhang, Xiaofei

    2012-12-01

    The planetary gearbox is a critical mechanism in helicopter transmission systems. A crack level estimation methodology for planetary gearbox has been devised by integrating a physical model for simulation signal generation, a statistic algorithm for feature selection and a grey relational analysis (GRA) algorithm for damage level estimation. The physical model is used to generate simulation datasets for developing and evaluating the diagnostic scheme that will be further calibrated with real world test data during application. The proposed method was calibrated with historical test data and then validated with real-time test data. The estimation results coincide with the actual test records, showing the effectiveness and accuracy of this method in providing a novel way for more accurate health monitoring and condition prediction.

  12. Tight interconnection and multi-level control of Arabidopsis MYB44 in MAPK cascade signalling.

    PubMed

    Persak, Helene; Pitzschke, Andrea

    2013-01-01

    Abiotic stress poses a huge, ever-increasing problem to plants and agriculture. The dissection of signalling pathways mediating stress tolerance is a prerequisite to develop more resistant plant species. Mitogen-activated protein kinase (MAPK) cascades are universal signalling modules. In Arabidopsis, the MAPK MPK3 and its upstream regulator MAPK kinase MKK4 initiate the adaptation response to numerous abiotic and biotic stresses. Yet, molecular steps directly linked with MKK4-MPK3 activation are largely unknown. Starting with a yeast-two-hybrid screen for interacting partners of MKK4, we identified a transcription factor, MYB44. MYB44 is controlled at multiple levels by and strongly inter-connected with MAPK signalling. As we had shown earlier, stress-induced expression of the MYB44 gene is regulated by a MPK3-targeted bZIP transcription factor VIP1. At the protein level, MYB44 interacts with MPK3 in vivo. MYB44 is phosphorylated by MPK3 in vitro at a single residue, Ser145. Although replacement of Ser145 by a non-phosphorylatable (S145A) or phosphomimetic (S145D) residue did not alter MYB44 subcellular localisation, dimerization behaviour nor DNA-binding characteristics, abiotic stress tolerance tests in stable transgenic Arabidopsis plants clearly related S145 phosphorylation to MYB44 function: Compared to Arabidopsis wild type plants, MYB44 overexpressing lines exhibit an enhanced tolerance to osmotic stress and are slightly more sensitive to abscisic acid. Interestingly, overexpression of the S145A variant revealed that impaired phosphorylation does not render the MYB44 protein non-functional. Instead, S145A lines are highly sensitive to abiotic stress, and thereby remarkably similar to mpk3-deficient plants. Its in vivo interaction with the nuclear sub-pools of both MPK3 and MKK4 renders MYB44 the first plant transcription factor to have a second function as putative MAPK cascade scaffolding protein.

  13. Uncoupling protein 3 expression levels influence insulin sensitivity, fatty acid oxidation, and related signaling pathways.

    PubMed

    Senese, Rosalba; Valli, Vivien; Moreno, Maria; Lombardi, Assunta; Busiello, Rosa Anna; Cioffi, Federica; Silvestri, Elena; Goglia, Fernando; Lanni, Antonia; de Lange, Pieter

    2011-01-01

    Controversy exists on whether uncoupling protein 3 (UCP3) positively or negatively influences insulin sensitivity in vivo, and the underlying signaling pathways have been scarcely studied. We studied how a progressive reduction in UCP3 expression (using UCP3 +/+, UCP3 +/-, and UCP3 -/- mice) modulates insulin sensitivity and related metabolic parameters. In order to further validate our observations, we also studied animals in which insulin resistance was induced by administration of a high-fat diet (HFD). In UCP3 +/- and UCP3 -/- mice, gastrocnemius muscle Akt/protein kinase B (Akt/PKB) (serine 473) and AMP-activated protein kinase (AMPK) (threonine 171) phosphorylation, and glucose transporter 4 (GLUT4) membrane levels were reduced compared to UCP3 +/+ mice. The HOMA-IR index (insulin resistance parameter) was increased both in the UCP3 +/- and UCP3 -/- mice. In these mice, insulin administration normalized Akt/PKB phosphorylation between genotypes while AMPK phosphorylation was further reduced, and sarcolemmal GLUT4 levels were induced but did not reach control levels. Furthermore, non-insulin-stimulated muscle fatty acid oxidation and the expression of several involved genes both in muscle and in liver were reduced. HFD administration induced insulin resistance in UCP3 +/+ mice and the aforementioned parameters resulted similar to those of chow-fed UCP3 +/- and UCP3 -/- mice. In conclusion, high-fat-diet-induced insulin resistance in wild-type mice mimics that of chow-fed UCP3 +/- and UCP3 -/- mice showing that progressive reduction of UCP3 levels results in insulin resistance. This is accompanied by decreased fatty acid oxidation and a less intense Akt/PKB and AMPK signaling.

  14. Enterovirus 71 Disrupts Interferon Signaling by Reducing the Level of Interferon Receptor 1

    PubMed Central

    Lu, Jing; Yi, Lina; Zhao, Jin; Yu, Jun; Chen, Ying; Lin, Marie C.; Kung, Hsiang-Fu

    2012-01-01

    The recent outbreak of enterovirus 71 (EV71) infected millions of children and caused over 1,000 deaths. To date, neither an effective vaccine nor antiviral treatment is available for EV71 infection. Interferons (IFNs) have been successfully applied to treat patients with hepatitis B and C viral infections for decades but have failed to treat EV71 infections. Here, we provide the evidence that EV71 antagonizes type I IFN signaling by reducing the level of interferon receptor 1 (IFNAR1). We show that the host cells could sense EV71 infection and stimulate IFN-β production. However, the induction of downstream IFN-stimulated genes is inhibited by EV71. Also, only a slight interferon response and antiviral effects could be detected in cells treated with recombinant type I IFNs after EV71 infection. Further studies reveal that EV71 blocks the IFN-mediated phosphorylation of STAT1, STAT2, Jak1, and Tyk2 by reducing IFNAR1. Finally, we identified the 2A protease encoded by EV71 as an antagonist of IFNs and show that the protease activity is required for reducing IFNAR1 levels. Taken together, our study for the first time uncovers a mechanism used by EV71 to antagonize type I IFN signaling and provides new targets for future antiviral strategies. PMID:22258259

  15. Improving Signal Levels in Intravital Multiphoton Microscopy using an Objective Correction Collar.

    PubMed

    Muriello, Pamela A; Dunn, Kenneth W

    2008-04-01

    Multiphoton microscopy has enabled biologists to collect high-resolution images hundreds of microns into biological tissues, including tissues of living animals. While the depth of imaging exceeds that possible from any other form of light microscopy, multiphoton microscopy is nonetheless generally limited to depths of less than a millimeter. Many of the advantages of multiphoton microscopy for deep tissue imaging accrue from the unique nature of multiphoton fluorescence excitation. However, the quadratic relationship between illumination level and fluorescence excitation makes multiphoton microscopy especially susceptible to factors that degrade the illumination focus. Here we examine the effect of spherical aberration on multiphoton microscopy in fixed kidney tissues and in the kidneys of living animals. We find that spherical aberration, as evaluated from axial asymmetry in the point spread function, can be corrected by adjustment of the correction collar of a water immersion objective lens. Introducing a compensatory positive spherical aberration into the imaging system decreased the depth-dependence of signal levels in images collected from living animals, increasing signal by up to 50%.

  16. Improving Signal Levels in Intravital Multiphoton Microscopy using an Objective Correction Collar

    PubMed Central

    Muriello, Pamela A.; Dunn, Kenneth W.

    2008-01-01

    Multiphoton microscopy has enabled biologists to collect high-resolution images hundreds of microns into biological tissues, including tissues of living animals. While the depth of imaging exceeds that possible from any other form of light microscopy, multiphoton microscopy is nonetheless generally limited to depths of less than a millimeter. Many of the advantages of multiphoton microscopy for deep tissue imaging accrue from the unique nature of multiphoton fluorescence excitation. However, the quadratic relationship between illumination level and fluorescence excitation makes multiphoton microscopy especially susceptible to factors that degrade the illumination focus. Here we examine the effect of spherical aberration on multiphoton microscopy in fixed kidney tissues and in the kidneys of living animals. We find that spherical aberration, as evaluated from axial asymmetry in the point spread function, can be corrected by adjustment of the correction collar of a water immersion objective lens. Introducing a compensatory positive spherical aberration into the imaging system decreased the depth-dependence of signal levels in images collected from living animals, increasing signal by up to 50%. PMID:19343075

  17. Melatonin Signaling Controls the Daily Rhythm in Blood Glucose Levels Independent of Peripheral Clocks.

    PubMed

    Owino, Sharon; Contreras-Alcantara, Susana; Baba, Kenkichi; Tosini, Gianluca

    2016-01-01

    Melatonin is rhythmically secreted by both the pineal gland and retina in a circadian fashion, with its peak synthesis occurring during the night. Once synthesized, melatonin exerts its effects by binding to two specific G-protein coupled receptors-melatonin receptor type 1(MT1) and melatonin receptor type 2(MT2). Recent studies suggest the involvement of MT1 and MT2 in the regulation of glucose homeostasis; however the ability of melatonin signaling to impart timing cues on glucose metabolism remains poorly understood. Here we report that the removal of MT1 or MT2 in mice abolishes the daily rhythm in blood glucose levels. Interestingly, removal of melatonin receptors produced small effects on the rhythmic expression patterns of clock genes within skeletal muscle, liver, and adipose tissue. Taken together, our data suggest that the loss of the daily rhythm in blood glucose observed in MT1(-/-) and MT2(-/-) mice does not occur as a consequence of 'disrupted' clocks within insulin sensitive tissues. Finally our results highlight a diurnal contribution of melatonin receptor signaling in the daily regulation of blood glucose levels.

  18. Low level exposure to the flame retardant BDE-209 reduces thyroid hormone levels and disrupts thyroid signaling in fathead minnows

    PubMed Central

    Noyes, Pamela D.; Lema, Sean C.; Macaulay, Laura J.; Douglas, Nora K.; Stapleton, Heather M.

    2013-01-01

    Polybrominated diphenyl ether (PBDE) flame retardants have been shown to disrupt thyroid hormone regulation, neurodevelopment, and reproduction in some animals. However, effects of the most heavily used PBDE, decabromodiphenyl ether (BDE-209), on thyroid functioning remain unclear. This study examined low-dose effects of BDE-209 on thyroid hormone levels and signaling in fathead minnows. Adult males received dietary exposures of BDE-209 at a low dose (~3 ng/g bw-day) and high dose (~300 ng/g bw-day) for 28 days followed by a 14-day depuration to evaluate recovery. Compared to controls, fish exposed to the low dose for 28 days experienced a 53% and 46% decline in circulating total thyroxine (TT4) and 3,5,3'-triiodothyronine (TT3), respectively, while TT4 and TT3 deficits at the high dose were 59% and 62%. Brain deiodinase activity (T4-ORD) was reduced by ~65% at both doses. BDE-209 elevated the relative mRNA expression of genes encoding deiodinases, nuclear thyroid receptors, and membrane transporters in the brain and liver in patterns that varied with time and dose, likely in compensation to hypothyroidism. Declines in the gonadal-somatic index (GSI) and increased mortality were also measured. Effects at the low dose were consistent with the high dose, suggesting non-linear relationships between BDE-209 exposures and thyroid dysfunction. PMID:23899252

  19. Dynamics of biosonar signals in free-swimming and stationary dolphins: The role of source levels on the characteristics of the signals.

    PubMed

    Au, Whitlow W L; Martin, Stephen W; Moore, Patrick W; Branstetter, Brian; Copeland, Adrienne M

    2016-03-01

    The biosonar signals of two free-swimming Atlantic bottlenose dolphins performing a complex sonar search for a bottom target in San Diego Bay were compared with the biosonar signals of a dolphin performing a target discrimination task in a net pen in the same bay. A bite-plate device carried by the free-swimming dolphins supported a hydrophone that extended directly in front of the dolphin. A biosonar measuring tool attached to the bite plate measured the outgoing biosonar signals while the dolphins conducted sonar searches. Each of the free-swimming dolphins used different biosonar search strategy in solving the problem and the dolphins' biosonar signals reflect the difference in strategy. The dolphin in the pen stationed in a hoop while echolocating on a target 6 m away and reported if the indentation on a spherical target was directed toward it. The signals were parameterized by determining the peak-to-peak source levels, source energy flux density, peak frequency, center frequency, root-mean-square (rms) bandwidth, rms duration, and the Q of the signals. Some parameters were similar for the free-swimming and stationary dolphins while some were significantly different, suggesting biosonar signals used by free-swimming animals may be different than signals used by dolphins in a pen.

  20. Dynamics of biosonar signals in free-swimming and stationary dolphins: The role of source levels on the characteristics of the signals.

    PubMed

    Au, Whitlow W L; Martin, Stephen W; Moore, Patrick W; Branstetter, Brian; Copeland, Adrienne M

    2016-03-01

    The biosonar signals of two free-swimming Atlantic bottlenose dolphins performing a complex sonar search for a bottom target in San Diego Bay were compared with the biosonar signals of a dolphin performing a target discrimination task in a net pen in the same bay. A bite-plate device carried by the free-swimming dolphins supported a hydrophone that extended directly in front of the dolphin. A biosonar measuring tool attached to the bite plate measured the outgoing biosonar signals while the dolphins conducted sonar searches. Each of the free-swimming dolphins used different biosonar search strategy in solving the problem and the dolphins' biosonar signals reflect the difference in strategy. The dolphin in the pen stationed in a hoop while echolocating on a target 6 m away and reported if the indentation on a spherical target was directed toward it. The signals were parameterized by determining the peak-to-peak source levels, source energy flux density, peak frequency, center frequency, root-mean-square (rms) bandwidth, rms duration, and the Q of the signals. Some parameters were similar for the free-swimming and stationary dolphins while some were significantly different, suggesting biosonar signals used by free-swimming animals may be different than signals used by dolphins in a pen. PMID:27036275

  1. Detection of Cracking Levels in Brittle Rocks by Parametric Analysis of the Acoustic Emission Signals

    NASA Astrophysics Data System (ADS)

    Moradian, Zabihallah; Einstein, Herbert H.; Ballivy, Gerard

    2016-03-01

    Determination of the cracking levels during the crack propagation is one of the key challenges in the field of fracture mechanics of rocks. Acoustic emission (AE) is a technique that has been used to detect cracks as they occur across the specimen. Parametric analysis of AE signals and correlating these parameters (e.g., hits and energy) to stress-strain plots of rocks let us detect cracking levels properly. The number of AE hits is related to the number of cracks, and the AE energy is related to magnitude of the cracking event. For a full understanding of the fracture process in brittle rocks, prismatic specimens of granite containing pre-existing flaws have been tested in uniaxial compression tests, and their cracking process was monitored with both AE and high-speed video imaging. In this paper, the characteristics of the AE parameters and the evolution of cracking sequences are analyzed for every cracking level. Based on micro- and macro-crack damage, a classification of cracking levels is introduced. This classification contains eight stages (1) crack closure, (2) linear elastic deformation, (3) micro-crack initiation (white patch initiation), (4) micro-crack growth (stable crack growth), (5) micro-crack coalescence (macro-crack initiation), (6) macro-crack growth (unstable crack growth), (7) macro-crack coalescence and (8) failure.

  2. A novel small-molecule inhibitor of NF-{kappa}B signaling

    SciTech Connect

    Nakajima, Hiroto; Fujiwara, Hideyasu; Furuichi, Yasuhiro Tanaka, Keiji Shimbara, Naoki

    2008-04-18

    The inducible transcription factor NF-{kappa}B regulates divergent signaling pathways including inflammatory response and cancer development. Selective inhibitors for NF-{kappa}B signaling are potentially useful for treatment of inflammation and cancer. NF-{kappa}B is canonically activated by preferential disposal of its inhibitory protein; I{kappa}B, which suppresses the nuclear translocation of NF-{kappa}B. I{kappa}B{alpha} (a major member of I{kappa}B family proteins) is phosphorylated with an I{kappa}B kinase (IKK) and subsequently polyubiquitylated by SCF{sup {beta}}{sup TrCP1} ubiquitin-ligase in the presence of E1 and E2 prior to proteasomal degradation. Here, we describe a novel inhibitor termed GS143, which suppressed I{kappa}B{alpha} ubiquitylation, but not I{kappa}B{alpha} phosphorylation, MDM2-directed p53 ubiquitylation, and proteasome activity in vitro. GS143 markedly suppressed the destruction of I{kappa}B{alpha} stimulated by TNF{alpha} and a set of downstream responses coupled to NF-{kappa}B signaling but not those of p53 and {beta}-catenin in vivo. Our results indicate that GS143 serves as an effective inhibitor of multiple pathways served by NF-{kappa}B signaling.

  3. The Wnt signaling regulator R-spondin 3 promotes angioblast and vascular development.

    PubMed

    Kazanskaya, Olga; Ohkawara, Bisei; Heroult, Melanie; Wu, Wei; Maltry, Nicole; Augustin, Hellmut G; Niehrs, Christof

    2008-11-01

    The vertebrate embryonic vasculature develops from angioblasts, which are specified from mesodermal precursors and develop in close association with blood cells. The signals that regulate embryonic vasculogenesis and angiogenesis are incompletely understood. Here, we show that R-spondin 3 (Rspo3), a member of a novel family of secreted proteins in vertebrates that activate Wnt/beta-catenin signaling, plays a key role in these processes. In Xenopus embryos, morpholino antisense knockdown of Rspo3 induces vascular defects because Rspo3 is essential for regulating the balance between angioblast and blood cell specification. In mice, targeted disruption of Rspo3 leads to embryonic lethality caused by vascular defects. Specifically in the placenta, remodeling of the vascular plexus is impaired. In human endothelial cells, R-spondin signaling promotes proliferation and sprouting angiogenesis in vitro, indicating that Rspo3 can regulate endothelial cells directly. We show that vascular endothelial growth factor is an immediate early response gene and a mediator of R-spondin signaling. The results identify Rspo3 as a novel, evolutionarily conserved angiogenic factor in embryogenesis.

  4. Canonical WNT signaling pathway and human AREG.

    PubMed

    Katoh, Yuriko; Katoh, Masaru

    2006-06-01

    AREG (Amphiregulin), BTC (beta-cellulin), EGF, EPGN (Epigen), EREG (Epiregulin), HBEGF, NRG1, NRG2, NRG3, NRG4 and TGFA (TGFalpha) constitute EGF family ligands for ERBB family receptors. Cetuximab (Erbitux), Pertuzumab (Omnitarg) and Trastuzumab (Herceptin) are anti-cancer drugs targeted to EGF family ligands, while Gefitinib (Iressa), Erlotinib (Tarceva) and Lapatinib (GW572016) are anti-cancer drugs targeted to ERBB family receptors. AREG and TGFA are biomarkers for Gefitinib non-responders. The TCF/LEF binding sites within the promoter region of human EGF family members were searched for by using bioinformatics and human intelligence (Humint). Because three TCF/LEF-binding sites were identified within the 5'-promoter region of human AREG gene, comparative genomics analyses on AREG orthologs were further performed. The EPGN-EREG-AREG-BTC cluster at human chromosome 4q13.3 was linked to the PPBP-CXCL segmental duplicons. AREG was the paralog of HBEGF at human chromosome 5q31.2. Chimpanzee AREG gene, consisting of six exons, was located within NW_105918.1 genome sequence. Chimpanzee AREG was a type I transmembrane protein showing 98.0% and 71.4% total amino-acid identity with human AREG and mouse Areg, respectively. Three TCF/LEF-binding sites within human AREG promoter were conserved in chimpanzee AREG promoter, but not in rodent Areg promoters. Primate AREG promoters were significantly divergent from rodent Areg promoters. AREG mRNA was expressed in a variety of human tumors, such as colorectal cancer, liver cancer, gastric cancer, breast cancer, prostate cancer, esophageal cancer and myeloma. Because human AREG was characterized as potent target gene of WNT/beta-catenin signaling pathway, WNT signaling activation could lead to Gefitinib resistance through AREG upregulation. AREG is a target of systems medicine in the field of oncology. PMID:16685431

  5. Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation

    PubMed Central

    Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.

    2011-01-01

    Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 minutes after acute oral administration of zolpidem (0, 5, 10, or 20 mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20 mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem’s modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABAA receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. PMID:21640782

  6. Regulation of tooth number by fine-tuning levels of receptor-tyrosine kinase signaling.

    PubMed

    Charles, Cyril; Hovorakova, Maria; Ahn, Youngwook; Lyons, David B; Marangoni, Pauline; Churava, Svatava; Biehs, Brian; Jheon, Andrew; Lesot, Hervé; Balooch, Guive; Krumlauf, Robb; Viriot, Laurent; Peterkova, Renata; Klein, Ophir D

    2011-09-01

    Much of our knowledge about mammalian evolution comes from examination of dental fossils, because the highly calcified enamel that covers teeth causes them to be among the best-preserved organs. As mammals entered new ecological niches, many changes in tooth number occurred, presumably as adaptations to new diets. For example, in contrast to humans, who have two incisors in each dental quadrant, rodents only have one incisor per quadrant. The rodent incisor, because of its unusual morphogenesis and remarkable stem cell-based continuous growth, presents a quandary for evolutionary biologists, as its origin in the fossil record is difficult to trace, and the genetic regulation of incisor number remains a largely open question. Here, we studied a series of mice carrying mutations in sprouty genes, the protein products of which are antagonists of receptor-tyrosine kinase signaling. In sprouty loss-of-function mutants, splitting of gene expression domains and reduced apoptosis was associated with subdivision of the incisor primordium and a multiplication of its stem cell-containing regions. Interestingly, changes in sprouty gene dosage led to a graded change in incisor number, with progressive decreases in sprouty dosage leading to increasing numbers of teeth. Moreover, the independent development of two incisors in mutants with large decreases in sprouty dosage mimicked the likely condition of rodent ancestors. Together, our findings indicate that altering genetic dosage of an antagonist can recapitulate ancestral dental characters, and that tooth number can be progressively regulated by changing levels of activity of a single signal transduction pathway.

  7. Asymmetric signal amplification for simultaneous SERS detection of multiple cancer markers with significantly different levels.

    PubMed

    Ye, Sujuan; Wu, Yanying; Zhai, Xiaomo; Tang, Bo

    2015-08-18

    Simultaneous detection of cancer biomarkers holds great promise for the early diagnosis of different cancers. However, in the presence of high-concentration biomarkers, the signals of lower-expression biomarkers are overlapped. Existing techniques are not suitable for simultaneously detecting multiple biomarkers at concentrations with significantly different orders of magnitude. Here, we propose an asymmetric signal amplification method for simultaneously detecting multiple biomarkers with significantly different levels. Using the bifunctional probe, a linear amplification mode responds to high-concentration markers, and quadratic amplification mode responds to low-concentration markers. With the combined biobarcode probe and hybridization chain reaction (HCR) amplification method, the detection limits of microRNA (miRNA) and ATP via surface-enhanced Raman scattering (SERS) detection are 0.15 fM and 20 nM, respectively, with a breakthrough of detection concentration difference over 11 orders of magnitude. Furthermore, successful determination of miRNA and ATP in cancer cells supports the practicability of the assay. This methodology promises to open an exciting new avenue for the detection of various types of biomolecules. PMID:26218034

  8. Programming neural Hoxd10: in vivo evidence that early node-associated signals predominate over paraxial mesoderm signals at posterior spinal levels.

    PubMed

    Omelchenko, Natalia; Lance-Jones, Cynthia

    2003-09-01

    Studies of the programming of Hox patterns at anterior spinal levels suggest that these events are accomplished through an integration of Hensen's node-derived and paraxial mesoderm signaling. We have used in vivo tissue manipulation in the avian embryo to examine the respective roles of node- derived and other local signals in the programming of a Hox pattern at posterior spinal levels. Hoxd10 is highly expressed in the lumbosacral (LS) spinal cord and adjacent paraxial mesoderm. At stages of LS neural tube formation (stages 12-14), the tailbud contains the remnants of Hensen's node and the primitive streak. Hoxd10 expression was analyzed after transposition of LS neural segments with and without the tailbud, after isolation of normally positioned LS segments from the stage 13 tailbud, and after axial displacement of posterior paraxial mesoderm. Data suggest that inductive signals from the tailbud are primarily responsible for the programming of Hoxd10 at neural plate and the earliest neural tube stages. After these stages, the LS neural tube appears to differ from more anterior neural segments in its lack of dependence on Hox-inductive signals from local tissues, including paraxial mesoderm. Our data also suggest that a graded system of repressive signals for posterior Hox genes is present at cervical and thoracic levels and likely to originate from paraxial mesoderm.

  9. Multilevel-3D Bit Patterned Magnetic Media with 8 Signal Levels Per Nanocolumn

    PubMed Central

    Amos, Nissim; Butler, John; Lee, Beomseop; Shachar, Meir H.; Hu, Bing; Tian, Yuan; Hong, Jeongmin; Garcia, Davil; Ikkawi, Rabee M.; Haddon, Robert C.; Litvinov, Dmitri; Khizroev, Sakhrat

    2012-01-01

    This letter presents an experimental study that shows that a 3rd physical dimension may be used to further increase information packing density in magnetic storage devices. We demonstrate the feasibility of at least quadrupling the magnetic states of magnetic-based data storage devices by recording and reading information from nanopillars with three magnetically-decoupled layers. Magneto-optical Kerr effect microscopy and magnetic force microscopy analysis show that both continuous (thin film) and patterned triple-stack magnetic media can generate eight magnetically-stable states. This is in comparison to only two states in conventional magnetic recording. Our work further reveals that ferromagnetic interaction between magnetic layers can be reduced by combining Co/Pt and Co/Pd multilayers media. Finally, we are showing for the first time an MFM image of multilevel-3D bit patterned media with 8 discrete signal levels. PMID:22808105

  10. Optimum method of applying and removing a shaped-function signal for low-light-level image detection.

    PubMed

    Li, Gang; Zhao, Longfei; Zhou, Mei; Wang, Mengjun; Lin, Ling

    2013-11-20

    This paper presents an optimum method that exploits the principle of diffuse scattering and employs the least squares method (LSM) to apply and remove a shaped-function signal for low-light-level image detection. With the help of a sawtooth-shaped-function light signal applied to an image sensor, the LSM is employed to remove the sawtooth signal from the captured images and restore the weak image signal. The experiment process and result verify that this method can not only maintain the capability of upgrading the image sensor's sensitivity and signal-to-noise ratio like the previous method, but it also can improve the imaging speed in the low-light level, decrease the computation cost of the extraction process, and eliminate the influence of the environment light to satisfy the requirement of long-distance detection.

  11. Oncogenic signaling in Amphiregulin and EGFR-expressing PTEN-null human breast cancer

    PubMed Central

    Kappler, Christiana S.; Guest, Stephen T.; Irish, Jonathan C.; Garrett-Mayer, Elizabeth; Kratche, Zachary; Wilson, Robert C.; Ethier, Stephen P.

    2014-01-01

    A subset of triple negative breast cancer (TNBC) is characterized by overexpression of the epidermal growth factor receptor (EGFR) and loss of PTEN, and patients with these determinants have a poor prognosis. We used cell line models of EGFR-positive/PTEN null TNBC to elucidate the signaling networks that drive the malignant features of these cells and cause resistance to EGFR inhibitors. In these cells, amphiregulin (AREG)-mediated activation of EGFR results in up-regulation of fibronectin (FN1), which is known to be a mediator of invasive capacity via interaction with integrin β1. EGFR activity in this PTEN null background also results in Wnt/beta-catenin signaling and activation of NF-κB. In addition, AKT is constitutively phosphorylated in these cells and is resistant to gefitinib. Expression profiling demonstrated that AREG-activated EGFR regulates gene expression differently than EGF-activated EGFR, and functional analysis via genome-scale shRNA screening identified a set of genes, including PLK1 and BIRC5, that are essential for survival of SUM-149 cells, but are uncoupled from EGFR signaling. Thus, our results demonstrate that in cells with constitutive EGFR activation and PTEN loss, critical survival genes are uncoupled from regulation by EGFR, which likely mediates resistance to EGFR inhibitors. PMID:25454348

  12. Wnt signaling and heterotrimeric G-proteins: strange bedfellows or a classic romance?

    PubMed

    Malbon, C C; Wang, H; Moon, R T

    2001-09-28

    Wnts are secreted ligands with diverse roles in animal development. Wnts bind to cell surface membrane proteins termed Frizzleds. Molecular cloning of members of the Frizzled family revealed hydropathy plots with seven putative, transmembrane-spanning regions, conserved in Frizzleds characterized in mice, humans, flies, and worms. Understanding how Frizzled translates binding of their cognate Wnts into intracellular signals controlling aspects of development has been an elusive goal. Earlier observations gathered from a variety of model systems provided compelling, but indirect, support that the Frizzled receptors may be members of the superfamily of G-protein-coupled receptors that possess seven transmembrane-spanning domains. Search for a linkage between Frizzled and possible downstream heterotrimeric G-proteins has been advanced by the use of bacterial toxins, antisense DNA, and novel chimeric receptor constructs. New data establish that Frizzleds are indeed bona fide G-protein-coupled receptors. Frizzled-1 couples via G-proteins Go and Gq to the canonical beta-catenin-Lef-Tcf pathway. Frizzled-2 couples via Gq and Gt to downstream effectors including calcium mobilization. Frizzleds and G-proteins might once have been considered strange bedfellows, not likely partners in signaling. The new data, consistent with the properties known for virtually all members of the G-protein-coupled receptors, reveal a more classic romance of signaling elements controlling aspects of early development.

  13. Wingless signaling and the control of cell shape in Drosophila wing imaginal discs.

    PubMed

    Widmann, Thomas J; Dahmann, Christian

    2009-10-01

    The control of cell morphology is important for shaping animals during development. Here we address the role of the Wnt/Wingless signal transduction pathway and two of its target genes, vestigial and shotgun (encoding E-cadherin), in controlling the columnar shape of Drosophila wing disc cells. We show that clones of cells mutant for arrow (encoding an essential component of the Wingless signal transduction pathway), vestigial or shotgun undergo profound cell shape changes and are extruded towards the basal side of the epithelium. Compartment-wide expression of a dominant-negative form of the Wingless transducer T-cell factor (TCF/Pangolin), or double-stranded RNA targeting vestigial or shotgun, leads to abnormally short cells throughout this region, indicating that these genes act cell autonomously to maintain normal columnar cell shape. Conversely, overexpression of Wingless, a constitutively-active form of the Wingless transducer beta-catenin/Armadillo, or Vestigial, results in precocious cell elongation. Co-expression of Vestigial partially suppresses the abnormal cell shape induced by dominant-negative TCF. We conclude that Wingless signal transduction plays a cell-autonomous role in promoting and maintaining the columnar shape of wing disc cells. Furthermore, our data suggest that Wingless controls cell shape, in part, through maintaining vestigial expression. PMID:19627985

  14. Wingless signaling and the control of cell shape in Drosophila wing imaginal discs.

    PubMed

    Widmann, Thomas J; Dahmann, Christian

    2009-10-01

    The control of cell morphology is important for shaping animals during development. Here we address the role of the Wnt/Wingless signal transduction pathway and two of its target genes, vestigial and shotgun (encoding E-cadherin), in controlling the columnar shape of Drosophila wing disc cells. We show that clones of cells mutant for arrow (encoding an essential component of the Wingless signal transduction pathway), vestigial or shotgun undergo profound cell shape changes and are extruded towards the basal side of the epithelium. Compartment-wide expression of a dominant-negative form of the Wingless transducer T-cell factor (TCF/Pangolin), or double-stranded RNA targeting vestigial or shotgun, leads to abnormally short cells throughout this region, indicating that these genes act cell autonomously to maintain normal columnar cell shape. Conversely, overexpression of Wingless, a constitutively-active form of the Wingless transducer beta-catenin/Armadillo, or Vestigial, results in precocious cell elongation. Co-expression of Vestigial partially suppresses the abnormal cell shape induced by dominant-negative TCF. We conclude that Wingless signal transduction plays a cell-autonomous role in promoting and maintaining the columnar shape of wing disc cells. Furthermore, our data suggest that Wingless controls cell shape, in part, through maintaining vestigial expression.

  15. Peripheral Signals of Food Intake in Response to Low Leptin Levels Induced by Centrifugation

    NASA Technical Reports Server (NTRS)

    Moran, M. M.; Wade, Charles E.; Stein, T. P.; Dalton, Bonnie P. (Technical Monitor)

    2001-01-01

    The focus of the study was to examine leptin and other peripheral signals of energy balance, following hypergravity. The study was conducted in two experiments. In experiment 1 rats were centrifuged at either 1.5, 2, or remained at 1 G. During days 8 to 14 of experiment 1, mean body mass of the 1.5 and 2 G groups was significantly (p<0.05) lower than controls. No differences were found in food intake (g/day/100 g body mass). Epididymal fat in the 2 G group was 21% lower than controls and 14% lower than the 1.5 G group. Plasma leptin was reduced from controls in the 1.5 and 2 G groups by 45 and 63%, respectively. A significant correlation was found between G load and urinary catecholamines. In experiment 2, rats were centrifuged at either 1.25, 1.5, or remained at 1 G. During days 8 to 14, body mass and food intake were similar between the 1, 1.25, and 1.5 G groups. Epididymal fat was reduced from controls in the 1.25 (14%) and 1.5 (19%) G groups. Leptin was reduced from controls in the 1.25 (45%) and 1.5 (46%) G groups. No differences were found in urinary epinephrine. Urinary norepinephrine levels were significantly higher than controls in each centrifuge group. During hypergravity exposure, food intake is the result of a complex relationship between multiple pathways, which abates the importance of leptin as a primary signal.

  16. A multi-level model accounting for the effects of JAK2-STAT5 signal modulation in erythropoiesis.

    PubMed

    Lai, Xin; Nikolov, Svetoslav; Wolkenhauer, Olaf; Vera, Julio

    2009-08-01

    We develop a multi-level model, using ordinary differential equations, based on quantitative experimental data, accounting for murine erythropoiesis. At the sub-cellular level, the model includes a description of the regulation of red blood cell differentiation through Epo-stimulated JAK2-STAT5 signalling activation, while at the cell population level the model describes the dynamics of (STAT5-mediated) red blood cell differentiation from their progenitors. Furthermore, the model includes equations depicting the hypoxia-mediated regulation of hormone erythropoietin blood levels. Take all together, the model constitutes a multi-level, feedback loop-regulated biological system, involving processes in different organs and at different organisational levels. We use our model to investigate the effect of deregulation in the proteins involved in the JAK2-STAT5 signalling pathway in red blood cells. Our analysis results suggest that down-regulation in any of the three signalling system components affects the hematocrit level in an individual considerably. In addition, our analysis predicts that exogenous Epo injection (an already existing treatment for several blood diseases) may compensate the effects of single down-regulation of Epo hormone level, STAT5 or EpoR/JAK2 expression level, and that it may be insufficient to counterpart a combined down-regulation of all the elements in the JAK2-STAT5 signalling cascade. PMID:19660986

  17. An activated Notch1 signaling pathway inhibits cell proliferation and induces apoptosis in human esophageal squamous cell carcinoma cell line EC9706.

    PubMed

    Lu, Zhaoming; Liu, Hongtao; Xue, Lexun; Xu, Peirong; Gong, Tianxiao; Hou, Guiqin

    2008-03-01

    Previous studies have demonstrated that Notch1 signaling pathway plays a major role in maintaining the balance of cell proliferation, differentiation and apoptosis, and is closely associated with tumorigenesis. However, roles of Notch1 signaling pathway in esophageal squamous cell carcinoma (ESCC), which is a common cause of mortality in China, remain poorly understood. Therefore, a novel strategy for seeking a rational molecular therapeutic target for ESCC is urgently needed. The purpose of this study is to examine the effect of the active Notch1 signaling pathway on the proliferation and apoptosis of ESCC cells and to investigate the underlying molecular mechanisms in carcinogenesis of the esophagus. The results revealed that a constitutively activated Notch1 signaling pathway was observed in ESCC cell line EC9706, through a pcNICD vector mediated expression system. Clearly, the activated Notch1 signaling pathway gave rise to proliferation suppression of the cells, accompanied with a cell cycle inhibition at the G0/G1 phase and apoptosis. In contrast to the expression of CDK2, cyclin D1 and cyclin E observed in EC9706 cells untreated and transfected with pcDNA3.1, there was a markedly decrease in the cells stably expressing Notch1 NICD. Up- and down-regulations of GSK3 beta and beta-catenin, respectively, indicated that Notch1 inhibited proliferation and induced apoptosis of EC9706 cells through Wnt-mediated signaling pathway. These findings suggest that Notch1 signaling pathway may participate in carcinogenesis of the esophagus.

  18. CYLD Inhibits Tumorigenesis and Metastasis by Blocking JNK/AP1 Signaling at Multiple Levels

    PubMed Central

    de Marval, Paula Miliani; Lutfeali, Shazia; Jin, Jane Y.; Leshin, Benjamin; Selim, M. Angelica; Zhang, Jennifer Y.

    2011-01-01

    CYLD has been recognized as a tumor suppressor due to its dominant genetic linkage to multiple types of epidermal tumors and a range of other cancers. The molecular mechanisms governing CYLD control of skin cancer are still unclear. Here, we demonstrated that K14-driven epidermal expression of a patient relevant and catalytically deficient CYLD truncation mutant (CYLDm) sensitized mice to skin tumor development in response to DMBA/TPA-challenge. Tumors developed on transgenic mice were prone to malignant progression and lymph node metastasis, and displayed increased activation of JNK and the downstream c-Jun and c-Fos proteins. Most importantly, topical application of a pharmacological JNK inhibitor significantly reduced tumor development and abolished metastasis in the transgenic mice. Further in line with these animal data, exogenous expression of CYLDm in A431, a human squamous cell carcinoma (SCC) cell line, markedly enhanced cell growth, migration and subcutaneous tumor growth in an AP1-depdendent manner. In contrast, expression of the wild type CYLD inhibited SCC tumorigenesis and AP1 function. Most importantly, CYLDm not only increased JNK activation but also induced an upregulation of K63-ubiquitination on both c-Jun and c-Fos, leading to sustained AP1 activation. Our findings uncovered c-Jun and c-Fos as novel CYLD-targets and underscore that CYLD controls epidermal tumorigenesis through blocking the JNK/AP1 signaling pathway at multiple levels. PMID:21478324

  19. Multi-level signaling in the Stokes space and its application to large-capacity optical communications.

    PubMed

    Kikuchi, Kazuro; Kawakami, Shojiro

    2014-04-01

    The Stokes vector of an optical signal does not depend on its absolute phase; therefore, we can construct the phase-insensitive optical communication system, using the Stokes vector as a modulation parameter. In such a system, multi-level optical signals can effectively be designed in the three-dimensional Stokes space and demodulated either by direct detection or by coherent detection, where low-complexity digital-signal processing (DSP) is employed. Although this system has the disadvantage that adaptive equalizers can hardly be implemented in the digital domain, it is still an attractive solution to large-capacity (≥ 100 Gbit/s) and medium-or short-reach (≤ 100 km) transmission. In this paper, we discuss the receiver configuration for the multi-level signal in the Stokes space and the efficient DSP algorithm for demodulating such a signal. Simulation results demonstrate that 2-, 4-, 8-, 16-, and 32-ary signals in the Stokes space have good bit-error rate (BER) characteristics. Especially, the 16-ary signal at the moderate symbol rate of 25 Gsymbol/s can reach the bit rate of 100 Gbit/s even by using direct detection.

  20. Shock, stress or signal? Implications of freshwater flows for a top-level estuarine predator.

    PubMed

    Taylor, Matthew D; van der Meulen, Dylan E; Ives, Matthew C; Walsh, Chris T; Reinfelds, Ivars V; Gray, Charles A

    2014-01-01

    Physicochemical variability in estuarine systems plays an important role in estuarine processes and in the lifecycles of estuarine organisms. In particular, seasonality of freshwater inflow to estuaries may be important in various aspects of fish lifecycles. This study aimed to further understand these relationships by studying the movements of a top-level estuarine predator in response to physicochemical variability in a large, temperate south-east Australian estuary (Shoalhaven River). Mulloway (Argyrosomus japonicus, 47-89 cm total length) were surgically implanted with acoustic transmitters, and their movements and migrations monitored over two years via fixed-position VR2W acoustic receivers configured in a linear array along the length of the estuary. The study period included a high degree of abiotic variability, with multiple pulses (exponentially high flows over a short period of time) in fresh water to the estuary, as well as broader seasonal variation in flow, temperature and conductivity. The relative deviation of fish from their modal location in the estuary was affected primarily by changes in conductivity, and smaller fish (n = 4) tended to deviate much further downstream from their modal position in the estuary than larger fish (n = 8). High-flow events which coincided with warmer temperatures tended to drive mature fish down the estuary and potentially provided a spawning signal to stimulate aggregation of adults near the estuary mouth; however, this relationship requires further investigation. These findings indicate that pulse and press effects of freshwater inflow and associated physicochemical variability play a role in the movements of mulloway, and that seasonality of large freshwater flows may be important in spawning. The possible implications of river regulation and the extraction of freshwater for consumptive uses on estuarine fishes are discussed.

  1. Characterization of the tissue-level Ca2+ signals in spontaneously contracting human myometrium

    PubMed Central

    Bru-Mercier, Gilles; Gullam, Joanna E; Thornton, Steven; Blanks, Andrew M; Shmygol, Anatoly

    2012-01-01

    In the labouring uterus, millions of myocytes forming the complex geometrical structure of myometrium contract in synchrony to increase intrauterine pressure, dilate the cervix and eventually expel the foetus through the birth canal. The mechanisms underlying the precise coordination of contractions in human myometrium are not completely understood. In the present study, we have characterized the spatio-temporal properties of tissue-level [Ca2+]i transients in thin slices of intact human myometrium. We found that the waveform of [Ca2+]i transients and isotonic contractions recorded from thin slices was similar to the waveform of isometric contractions recorded from the larger strips in traditional organ bath experiments, suggesting that the spatio-temporal information obtained from thin slices is representative of the whole tissue. By comparing the time course of [Ca2+]i transients in individual cells to that recorded from the bundles of myocytes we found that the majority of myocytes produce rapidly propagating long-lasting [Ca2+]i transients accompanied by contractions. We also found a small number of cells showing desynchronized [Ca2+]i oscillations that did not trigger contractions. The [Ca2+]i oscillations in these cells were insensitive to nifedipine, but readily inhibited by the T-type Ca2+ channel inhibitor NNC55-0396. In conclusion, our data suggest that the spread of [Ca2+]i signals in human myometrium is achieved via propagation of long-lasting action potentials. The propagation was fast when action potentials propagated along bundles of myocytes and slower when propagating between the bundles of uterine myocytes. PMID:22947266

  2. Shock, Stress or Signal? Implications of Freshwater Flows for a Top-Level Estuarine Predator

    PubMed Central

    Taylor, Matthew D.; van der Meulen, Dylan E.; Ives, Matthew C.; Walsh, Chris T.; Reinfelds, Ivars V.; Gray, Charles A.

    2014-01-01

    Physicochemical variability in estuarine systems plays an important role in estuarine processes and in the lifecycles of estuarine organisms. In particular, seasonality of freshwater inflow to estuaries may be important in various aspects of fish lifecycles. This study aimed to further understand these relationships by studying the movements of a top-level estuarine predator in response to physicochemical variability in a large, temperate south-east Australian estuary (Shoalhaven River). Mulloway (Argyrosomus japonicus, 47–89 cm total length) were surgically implanted with acoustic transmitters, and their movements and migrations monitored over two years via fixed-position VR2W acoustic receivers configured in a linear array along the length of the estuary. The study period included a high degree of abiotic variability, with multiple pulses (exponentially high flows over a short period of time) in fresh water to the estuary, as well as broader seasonal variation in flow, temperature and conductivity. The relative deviation of fish from their modal location in the estuary was affected primarily by changes in conductivity, and smaller fish (n = 4) tended to deviate much further downstream from their modal position in the estuary than larger fish (n = 8). High-flow events which coincided with warmer temperatures tended to drive mature fish down the estuary and potentially provided a spawning signal to stimulate aggregation of adults near the estuary mouth; however, this relationship requires further investigation. These findings indicate that pulse and press effects of freshwater inflow and associated physicochemical variability play a role in the movements of mulloway, and that seasonality of large freshwater flows may be important in spawning. The possible implications of river regulation and the extraction of freshwater for consumptive uses on estuarine fishes are discussed. PMID:24752585

  3. The evolution and origin of animal Toll-like receptor signaling pathway revealed by network-level molecular evolutionary analyses.

    PubMed

    Song, Xiaojun; Jin, Ping; Qin, Sheng; Chen, Liming; Ma, Fei

    2012-01-01

    Genes carry out their biological functions through pathways in complex networks consisting of many interacting molecules. Studies on the effect of network architecture on the evolution of individual proteins will provide valuable information for understanding the origin and evolution as well as functional conservation of signaling pathways. However, the relationship between the network architecture and the individual protein sequence evolution is yet little known. In current study, we carried out network-level molecular evolution analysis on TLR (Toll-like receptor ) signaling pathway, which plays an important role in innate immunity in insects and mammals, and we found that: 1) The selection constraint of genes was negatively correlated with its position along TLR signaling pathway; 2) all genes in TLR signaling pathway were highly conserved and underwent strong purifying selection; 3) the distribution of selective pressure along the pathway was driven by differential nonsynonymous substitution levels; 4) The TLR signaling pathway might present in a common ancestor of sponges and eumetazoa, and evolve via the TLR, IKK, IκB and NF-κB genes underwent duplication events as well as adaptor molecular enlargement, and gene structure and conservation motif of NF-κB genes shifted in their evolutionary history. Our results will improve our understanding on the evolutionary history of animal TLR signaling pathway as well as the relationship between the network architecture and the sequences evolution of individual protein.

  4. The Evolution and Origin of Animal Toll-Like Receptor Signaling Pathway Revealed by Network-Level Molecular Evolutionary Analyses

    PubMed Central

    Qin, Sheng; Chen, Liming; Ma, Fei

    2012-01-01

    Genes carry out their biological functions through pathways in complex networks consisting of many interacting molecules. Studies on the effect of network architecture on the evolution of individual proteins will provide valuable information for understanding the origin and evolution as well as functional conservation of signaling pathways. However, the relationship between the network architecture and the individual protein sequence evolution is yet little known. In current study, we carried out network-level molecular evolution analysis on TLR (Toll-like receptor ) signaling pathway, which plays an important role in innate immunity in insects and mammals, and we found that: 1) The selection constraint of genes was negatively correlated with its position along TLR signaling pathway; 2) all genes in TLR signaling pathway were highly conserved and underwent strong purifying selection; 3) the distribution of selective pressure along the pathway was driven by differential nonsynonymous substitution levels; 4) The TLR signaling pathway might present in a common ancestor of sponges and eumetazoa, and evolve via the TLR, IKK, IκB and NF-κB genes underwent duplication events as well as adaptor molecular enlargement, and gene structure and conservation motif of NF-κB genes shifted in their evolutionary history. Our results will improve our understanding on the evolutionary history of animal TLR signaling pathway as well as the relationship between the network architecture and the sequences evolution of individual protein. PMID:23236523

  5. Wnt3a regulates proliferation and migration of HUVEC via canonical and non-canonical Wnt signaling pathways

    SciTech Connect

    Samarzija, Ivana; Sini, Patrizia; Schlange, Thomas; MacDonald, Gwen; Hynes, Nancy E.

    2009-08-28

    Untangling the signaling pathways involved in endothelial cell biology is of central interest for the development of antiangiogenesis based therapies. Here we report that Wnt3a induces the proliferation and migration of HUVECs, but does not affect their survival. Wnt3a-induced proliferation was VEGFR signaling independent, but reduced upon CamKII inhibition. In a search for the downstream mediators of Wnt3a's effects on HUVEC biology, we found that Wnt3a treatment leads to phosphorylation of DVL3 and stabilization of {beta}-catenin. Moreover, under the same conditions we observed an upregulation in c-MYC, TIE-2 and GJA1 mRNA transcripts. Although treatment of HUVECs with Wnt5a induced DVL3 phosphorylation, we did not observe any of the other effects seen upon Wnt3a stimulation. Taken together, our data indicate that Wnt3a induces canonical and non-canonical Wnt signaling in HUVECs, and stimulates their proliferation and migration.

  6. Signal voter

    DOEpatents

    Goodwin, Roy L.

    1981-01-01

    A voter for providing a single accurate output signal that is derived from the closest two signal levels of three input signals, each of which signals represents a measurement of the same phenomena. By means of the voting circuit, the signals are first sorted by level of amplitude and then ranked as highest, middle or lowest. The highest or lowest signal that is furthest from the middle signal is rejected, while the other highest or lowest signal is selected for processing. The selected high or low signal is then averaged with the middle signal to provide the output signal.

  7. Blood oxygenation level-dependent functional MRI signal turbulence caused by ultrahigh spatial resolution: numerical simulation and theoretical explanation

    PubMed Central

    Chen, Zikuan; Chen, Zeyuan; Calhoun, Vince

    2015-01-01

    High-spatial-resolution functional MRI (fMRI) can enhance image contrast and improve spatial specificity for brain activity mapping. As the voxel size is reduced, an irregular magnetic fieldmap will emerge as a result of less local averaging, and will lead to abnormal fMRI signal evolution with respect to the image acquisition TE. In this article, we report this signal turbulence phenomenon observed in simulations of ultrahigh-spatial-resolution blood oxygenation level-dependent (BOLD) fMRI (voxel size of less than 50 × 50 × 50 μm3). We present a four-level coarse-to-fine multiresolution BOLD fMRI signal simulation. Based on the statistical histogram of an intravoxel fieldmap, we reformulate the intravoxel dephasing summation (a form of Riemann sum) into a new formula that is a discrete Fourier transformation of the intravoxel fieldmap histogram (a form of Lebesgue sum). We interpret the BOLD signal formation by relating its magnitude (phase) to the even (odd) symmetry of the fieldmap histogram. Based on multiresolution BOLD signal simulation, we find that the signal turbulence mainly emerges at the vessel boundary, and that there are only a few voxels (less than 10%) in an ultrahigh-resolution image that reveal turbulence in the form of sparse point noise. Our simulation also shows that, for typical human brain imaging of the cerebral cortex with millimeter resolution, TE < 30 ms and B0 = 3 T, we are unlikely to observe BOLD signal turbulence. Overall, the main causes of voxel signal turbulence include a high spatial resolution, high field, long TE and large vessel. PMID:22927163

  8. Comparative study of the small signal gain coefficient and the dissipative losses evaluation methods of three-level microchip lasers

    NASA Astrophysics Data System (ADS)

    Mlynczak, J.; Belghachem, N.

    2015-08-01

    The paper describes the study of three methods of evaluation of the small signal gain coefficient and the dissipative losses of three-level microchip lasers. Engaging optimization procedure for cw lasers a very simple way to compare these methods was proposed. On the basis of laser generation investigations and calculations the most accurate method was chosen.

  9. Sample Entropy Analysis of EEG Signals via Artificial Neural Networks to Model Patients' Consciousness Level Based on Anesthesiologists Experience

    PubMed Central

    Jiang, George J. A.; Fan, Shou-Zen; Abbod, Maysam F.; Huang, Hui-Hsun; Lan, Jheng-Yan; Tsai, Feng-Fang; Chang, Hung-Chi; Yang, Yea-Wen; Chuang, Fu-Lan; Chiu, Yi-Fang; Jen, Kuo-Kuang; Wu, Jeng-Fu; Shieh, Jiann-Shing

    2015-01-01

    Electroencephalogram (EEG) signals, as it can express the human brain's activities and reflect awareness, have been widely used in many research and medical equipment to build a noninvasive monitoring index to the depth of anesthesia (DOA). Bispectral (BIS) index monitor is one of the famous and important indicators for anesthesiologists primarily using EEG signals when assessing the DOA. In this study, an attempt is made to build a new indicator using EEG signals to provide a more valuable reference to the DOA for clinical researchers. The EEG signals are collected from patients under anesthetic surgery which are filtered using multivariate empirical mode decomposition (MEMD) method and analyzed using sample entropy (SampEn) analysis. The calculated signals from SampEn are utilized to train an artificial neural network (ANN) model through using expert assessment of consciousness level (EACL) which is assessed by experienced anesthesiologists as the target to train, validate, and test the ANN. The results that are achieved using the proposed system are compared to BIS index. The proposed system results show that it is not only having similar characteristic to BIS index but also more close to experienced anesthesiologists which illustrates the consciousness level and reflects the DOA successfully. PMID:25738152

  10. Features for instantaneous emissions of low-level infrared signals of glucokinase enzyme from Pyrococcus furiosus.

    PubMed

    Torres, Sergio; Mella, Héctor; Reyes, Claudio; Meza, Pablo; Gallardo, Maria J; Staforelli, Juan P

    2015-03-10

    A noncontact infrared (IR) imaging-based methodology and signal recovery tools are applied on an enzyme reaction as a test target. The method is implemented by a long-wave (8-12 μm) IR microbolometer imaging array and a germanium-based IR optical vision. The reaction is carried out by the glucokinase, which produces a rapid exothermal release of energy that is weak, and, even worse, the IR video captured by the uncooled microbolometer detector is affected by spatial and temporal noise with specific complexities. Hitherto, IR-based signal recovery tools have worked with a standard acquisition frequency, which is clearly beyond the time scale of a real scenario. The implications of this (and similar) rapid reactions motivate the designs of a signal recovery method using prior information of the processes to extract and quantify the spontaneity of the enzymatic reaction in a three-dimensional (space and time) single and noncontact online measurement. PMID:25968383

  11. Seascape-level variation in turbulence- and wave-generated hydrodynamic signals experienced by plankton

    NASA Astrophysics Data System (ADS)

    Fuchs, Heidi L.; Gerbi, Gregory P.

    2016-02-01

    Plankton exhibit diverse and dramatic responses to fluid motions, and these behaviors are likely critical for survival and fitness. Fluid motions can be generated by organisms or by physical processes, including turbulence and surface gravity waves. Physical processes vary geographically in their intensity and generate hydrodynamic signals experienced by plankton as fluid forces on their sensory receptors. In this synthesis, we review how turbulence and waves vary in space, the scales and statistics of their motions, and the forces exerted on plankton. We then quantify the hydrodynamic signals produced by turbulence and waves in four seascape types - surf zones, inlets and estuaries, the continental shelf, and the open ocean - using published dissipation rates, wind and wave data from buoys, and observations from two coastal sites in Massachusetts, USA. We relate these geographic patterns in signals to the observed behaviors of example species and to the forces sensed by typical plankters with different receptor types. Turbulence-generated shears are largest in the surf zone, inlets and estuaries, while wave-generated accelerations are larger offshore; as a result, each seascape exhibits some range of combined shears and accelerations that is distinct. These signals generate forces on plankton that vary among habitats and with plankton size and swimming speed. Spatial patterns in fluid forces create a potential mechanism for dispersing larvae to distinguish habitats by their hydrodynamic signatures. However, turbulence can be strong in all seascapes and may cause widespread interference in signaling among predators and prey. Plankton with a single receptor type could identify nearshore habitats, while those with multiple receptor types potentially could distinguish inshore vs. offshore seascapes or decode signals produced by physical processes and by other organisms.

  12. Generating pancreatic beta-cells from embryonic stem cells by manipulating signaling pathways.

    PubMed

    Champeris Tsaniras, Spyridon; Jones, Peter M

    2010-07-01

    Type 1 diabetes results from an insufficiency of insulin production as a result of autoimmune destruction of the insulin-secreting pancreatic beta-cells. It can be treated by transplantation of islets of Langerhans from human donors, but widespread application of this therapy is restricted by the scarcity of donor tissue. Generation of functional beta-cells from embryonic stem (ES) cells in vitro could provide a source of an alternative graft material. Several ES cell differentiation protocols have reported the production of insulin-producing cells by mimicking the in vivo developmental stages of pancreatic organogenesis in which cells are transitioned through mesendoderm, definitive endoderm, foregut endoderm, pancreatic endoderm, and the endocrine precursor stage, until mature beta-cells are obtained. These studies provide proof of concept that recapitulating pancreatic development in vitro offers a useful strategy for generating beta-cells, but current differentiation protocols employ a bewildering variety of growth factors, mitogens, and pharmacological agents. In this review, we will attempt to clarify the functions of these agents in in vitro differentiation strategies by focusing on the intracellular signaling pathways through which they operate - phosphatidylinositol 3-kinase, transforming growth factor beta, Wnt/beta-catenin, Hedgehog, and Notch. PMID:20385725

  13. Low-level Ga-Al-As laser irradiation enhances osteoblast proliferation through activation of Hedgehog signaling pathway

    NASA Astrophysics Data System (ADS)

    Li, Qiushi; Qu, Zhou; Chen, Yingxin; Liu, Shujie; Zhou, Yanmin

    2014-12-01

    Low-level laser irradiation has been reported to promote bone formation, but the molecular mechanism is still unclear. Hedgehog signaling pathway has been reported to play an important role in promoting bone formation. The aim of the present study was to examine whether low-level Ga-Al-As laser (808 nm) irradiation could have an effect on Hedgehog signaling pathway during osteoblast proliferation in vitro. Mouse osteoblastic cell line MC3T3-E1 was cultured in vitro. The cultures after laser irradiation (3.75J/cm2) were treated with recombinant N-terminals Sonic Hedgehog (N-Shh)or Hedgehog inhibitor cyclopamine (cy). The experiment was divided into 4 group, group 1:laser irradiation, group 2: laser irradiation and N-Shh, group 3: laser irradiation and cy, group 4:control with no laser irradiation. On day 1,2 and 3,cell proliferation was determined by cell counting, Cell Counting Kit-8.On 12 h and 24 h, cell cycle was detected by flow cytometry. Proliferation activity of laser irradiation and N-Shh group was remarkably increased compared with those of laser irradiation group. Proliferation activity of laser irradiation and cy group was remarkably decreased compared with those of laser irradiation group, however proliferation activity of laser irradiation and cy group was remarkably increased compared with those of control group. These results suggest that low-level Ga-Al-As laser irradiation activate Hedgehog signaling pathway during osteoblast proliferation in vitro. Hedgehog signaling pathway is one of the signaling pathways by which low-level Ga-Al-As laser irradiation regulates osteoblast proliferation.

  14. Multiple target tracking and classification improvement using data fusion at node level using acoustic signals

    NASA Astrophysics Data System (ADS)

    Damarla, T. R.; Whipps, Gene

    2005-05-01

    Target tracking and classification using passive acoustic signals is difficult at best as the signals are contaminated by wind noise, multi-path effects, road conditions, and are generally not deterministic. In addition, microphone characteristics, such as sensitivity, vary with the weather conditions. The problem is further compounded if there are multiple targets, especially if some are measured with higher signal-to-noise ratios (SNRs) than the others and they share spectral information. At the U. S. Army Research Laboratory we have conducted several field experiments with a convoy of two, three, four and five vehicles traveling on different road surfaces, namely gravel, asphalt, and dirt roads. The largest convoy is comprised of two tracked vehicles and three wheeled vehicles. Two of the wheeled vehicles are heavy trucks and one is a light vehicle. We used a super-resolution direction-of-arrival estimator, specifically the minimum variance distortionless response, to compute the bearings of the targets. In order to classify the targets, we modeled the acoustic signals emanated from the targets as a set of coupled harmonics, which are related to the engine-firing rate, and subsequently used a multivariate Gaussian classifier. Independent of the classifier, we find tracking of wheeled vehicles to be intermittent as the signals from vehicles with high SNR dominate the much quieter wheeled vehicles. We used several fusion techniques to combine tracking and classification results to improve final tracking and classification estimates. We will present the improvements (or losses) made in tracking and classification of all targets. Although improvements in the estimates for tracked vehicles are not noteworthy, significant improvements are seen in the case of wheeled vehicles. We will present the fusion algorithm used.

  15. Canonical Wnt activity regulates trunk neural crest delamination linking BMP/noggin signaling with G1/S transition.

    PubMed

    Burstyn-Cohen, Tal; Stanleigh, Jonathan; Sela-Donenfeld, Dalit; Kalcheim, Chaya

    2004-11-01

    Delamination of premigratory neural crest cells depends on a balance between BMP/noggin and on successful G1/S transition. Here, we report that BMP regulates G1/S transition and consequent crest delamination through canonical Wnt signaling. Noggin overexpression inhibits G1/S transition and blocking G1/S abrogates BMP-induced delamination; moreover, transcription of Wnt1 is stimulated by BMP and by the developing somites, which concomitantly inhibit noggin production. Interfering with beta-catenin and LEF/TCF inhibits G1/S transition, neural crest delamination and transcription of various BMP-dependent genes, which include Cad6B, Pax3 and Msx1, but not that of Slug, Sox9 or FoxD3. Hence, we propose that developing somites inhibit noggin transcription in the dorsal tube, resulting in activation of BMP and consequent Wnt1 production. Canonical Wnt signaling in turn stimulates G1/S transition and generation of neural crest cell motility independently of its proposed role in earlier neural crest specification. PMID:15456730

  16. Constitutive Notch Signaling Causes Abnormal Development of the Oviducts, Abnormal Angiogenesis, and Cyst Formation in Mouse Female Reproductive Tract.

    PubMed

    Ferguson, Lydia; Kaftanovskaya, Elena M; Manresa, Carmen; Barbara, Agustin M; Poppiti, Robert J; Tan, Yingchun; Agoulnik, Alexander I

    2016-03-01

    The Notch signaling pathway is critical for the differentiation of many tissues and organs in the embryo. To study the consequences of Notch1 gain-of-function signaling on female reproductive tract development, we used a cre-loxP strategy and Amhr2-cre transgene to generate mice with conditionally activated Notch1 (Rosa(Notch1)). The Amhr2-cre transgene is expressed in the mesenchyme of developing female reproductive tract and in granulosa cells in the ovary. Double transgenic Amhr2-cre, Rosa(Notch1) females were infertile, whereas control Rosa(Notch1) mice had normal fertility. All female reproductive organs in mutants showed hemorrhaging of blood vessels progressing with age. The mutant oviducts did not develop coiling, and were instead looped around the ovary. There were multiple blockages in the lumen along the oviduct length, creating a barrier for sperm or oocyte passage. Mutant females demonstrated inflamed uteri with increased vascularization and an influx of inflammatory cells. Additionally, older females developed ovarian, oviductal, and uterine cysts. The significant change in gene expression was detected in the mutant oviduct expression of Wnt4, essential for female reproductive tract development. Similar oviductal phenotypes have been detected previously in mice with activated Smo and in beta-catenin, Wnt4, Wnt7a, and Dicer conditional knockouts, indicating a common regulatory pathway disrupted by these genetic abnormalities. PMID:26843448

  17. Dysregulation of the Wnt pathway inhibits timely myelination and remyelination in the mammalian CNS.

    PubMed

    Fancy, Stephen P J; Baranzini, Sergio E; Zhao, Chao; Yuk, Dong-In; Irvine, Karen-Amanda; Kaing, Sovann; Sanai, Nader; Franklin, Robin J M; Rowitch, David H

    2009-07-01

    The progressive loss of CNS myelin in patients with multiple sclerosis (MS) has been proposed to result from the combined effects of damage to oligodendrocytes and failure of remyelination. A common feature of demyelinated lesions is the presence of oligodendrocyte precursors (OLPs) blocked at a premyelinating stage. However, the mechanistic basis for inhibition of myelin repair is incompletely understood. To identify novel regulators of OLP differentiation, potentially dysregulated during repair, we performed a genome-wide screen of 1040 transcription factor-encoding genes expressed in remyelinating rodent lesions. We report that approximately 50 transcription factor-encoding genes show dynamic expression during repair and that expression of the Wnt pathway mediator Tcf4 (aka Tcf7l2) within OLPs is specific to lesioned-but not normal-adult white matter. We report that beta-catenin signaling is active during oligodendrocyte development and remyelination in vivo. Moreover, we observed similar regulation of Tcf4 in the developing human CNS and lesions of MS. Data mining revealed elevated levels of Wnt pathway mRNA transcripts and proteins within MS lesions, indicating activation of the pathway in this pathological context. We show that dysregulation of Wnt-beta-catenin signaling in OLPs results in profound delay of both developmental myelination and remyelination, based on (1) conditional activation of beta-catenin in the oligodendrocyte lineage in vivo and (2) findings from APC(Min) mice, which lack one functional copy of the endogenous Wnt pathway inhibitor APC. Together, our findings indicate that dysregulated Wnt-beta-catenin signaling inhibits myelination/remyelination in the mammalian CNS. Evidence of Wnt pathway activity in human MS lesions suggests that its dysregulation might contribute to inefficient myelin repair in human neurological disorders.

  18. Attention enhances stimulus representations in macaque visual cortex without affecting their signal-to-noise level.

    PubMed

    Daliri, Mohammad Reza; Kozyrev, Vladislav; Treue, Stefan

    2016-01-01

    The magnitude of the attentional modulation of neuronal responses in visual cortex varies with stimulus contrast. Whether the strength of these attentional influences is similarly dependent on other stimulus properties is unknown. Here we report the effect of spatial attention on responses in the medial-temporal area (MT) of macaque visual cortex to moving random dots pattern of various motion coherences, i.e. signal-to-noise ratios. Our data show that allocating spatial attention causes a gain change in MT neurons. The magnitude of this attentional modulation is independent of the attended stimulus' motion coherence, creating a multiplicative scaling of the neuron's coherence-response function. This is consistent with the characteristics of gain models of attentional modulation and suggests that attention strengthens the neuronal representation of behaviorally relevant visual stimuli relative to unattended stimuli, but without affecting their signal-to-noise ratios. PMID:27283275

  19. Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgments. Blood oxygen level dependent.

    PubMed

    Chee, M W; Hon, N; Lee, H L; Soon, C S

    2001-06-01

    The effect of relative language proficiency on the spatial distribution and magnitude of BOLD signal change was evaluated by studying two groups of right-handed English-Mandarin bilingual participants with contrasting language proficiencies as they made semantic judgments with words and characters. Greater language proficiency corresponded to shorter response times and greater accuracy in the semantic judgment task. Within the left prefrontal and parietal regions, the change in BOLD signal was smaller in a participant's more proficient language. The least proficient performance was associated with right, in addition to left, inferior frontal activation. The results highlight the importance of taking into consideration nature of task and relative language proficiency when drawing inferences from functional imaging studies of bilinguals.

  20. Attention enhances stimulus representations in macaque visual cortex without affecting their signal-to-noise level

    PubMed Central

    Daliri, Mohammad Reza; Kozyrev, Vladislav; Treue, Stefan

    2016-01-01

    The magnitude of the attentional modulation of neuronal responses in visual cortex varies with stimulus contrast. Whether the strength of these attentional influences is similarly dependent on other stimulus properties is unknown. Here we report the effect of spatial attention on responses in the medial-temporal area (MT) of macaque visual cortex to moving random dots pattern of various motion coherences, i.e. signal-to-noise ratios. Our data show that allocating spatial attention causes a gain change in MT neurons. The magnitude of this attentional modulation is independent of the attended stimulus’ motion coherence, creating a multiplicative scaling of the neuron’s coherence-response function. This is consistent with the characteristics of gain models of attentional modulation and suggests that attention strengthens the neuronal representation of behaviorally relevant visual stimuli relative to unattended stimuli, but without affecting their signal-to-noise ratios. PMID:27283275

  1. Temporal Processing of Vibratory Communication Signals at the Level of Ascending Interneurons in Nezara viridula (Hemiptera: Pentatomidae)

    PubMed Central

    Zorović, Maja

    2011-01-01

    During mating, males and females of N. viridula (Heteroptera: Pentatomidae) produce sex- and species-specific calling and courtship substrate-borne vibratory signals, grouped into songs. Recognition and localization of these signals are fundamental for successful mating. The recognition is mainly based on the temporal pattern, i.e. the amplitude modulation, while the frequency spectrum of the signals usually only plays a minor role. We examined the temporal selectivity for vibratory signals in four types of ascending vibratory interneurons in N. viridula. Using intracellular recording and labelling technique, we analyzed the neurons' responses to 30 pulse duration/interval duration (PD/ID) combinations. Two response arrays were created for each neuron type, showing the intensity of the responses either as time-averaged spike counts or as peak instantaneous spike rates. The mean spike rate response arrays showed preference of the neurons for short PDs (below 600 ms) and no selectivity towards interval duration; while the peak spike rate response arrays exhibited either short PD/long ID selectivity or no selectivity at all. The long PD/short ID combinations elicited the weakest responses in all neurons tested. No response arrays showed the receiver preference for either constant period or duty cycle. The vibratory song pattern selectivity matched the PD of N. viridula male vibratory signals, thus pointing to temporal filtering for the conspecific vibratory signals already at level of the ascending interneurons. In some neurons the responses elicited by the vibratory stimuli were followed by distinct, regular oscillations of the membrane potential. The distance between the oscillation peaks matched the temporal structure of the male calling song, indicating a possible resonance based mechanism for signal recognition. PMID:22053216

  2. Beyond the Canon: Within-Plant and Population-Level Heterogeneity in Jasmonate Signaling Engaged by Plant-Insect Interactions

    PubMed Central

    Li, Dapeng; Baldwin, Ian T.; Gaquerel, Emmanuel

    2016-01-01

    Plants have evolved sophisticated communication and defense systems with which they interact with insects. Jasmonates are synthesized from the oxylipin pathway and act as pivotal cellular orchestrators of many of the metabolic and physiological processes that mediate these interactions. Many of these jasmonate-dependent responses are tissue-specific and translate from modulations of the canonical jasmonate signaling pathway. Here we provide a short overview of within-plant heterogeneities in jasmonate signaling and dependent responses in the context of plant-insect interactions as illuminated by examples from recent work with the ecological model, Nicotiana attenuata. We then discuss means of manipulating jasmonate signaling by creating tissue-specific jasmonate sinks, and the micrografting of different transgenic plants. The metabolic phenotyping of these manipulations provides an integrative understanding of the functional significance of deviations from the canonical model of this hormonal pathway. Additionally, natural variation in jasmonate biosynthesis and signaling both among and within species can explain polymorphisms in resistance to insects in nature. In this respect, insect-guided explorations of population-level variations in jasmonate metabolism have revealed more complexity than previously realized and we discuss how different “omic” techniques can be used to exploit the natural variation that occurs in this important signaling pathway. PMID:27135234

  3. A Systems Level Analysis of Vasopressin-mediated Signaling Networks in Kidney Distal Convoluted Tubule Cells

    PubMed Central

    Cheng, Lei; Wu, Qi; Kortenoeven, Marleen L. A.; Pisitkun, Trairak; Fenton, Robert A.

    2015-01-01

    The kidney distal convoluted tubule (DCT) plays an essential role in maintaining body sodium balance and blood pressure. The major sodium reabsorption pathway in the DCT is the thiazide-sensitive NaCl cotransporter (NCC), whose functions can be modulated by the hormone vasopressin (VP) acting via uncharacterized signaling cascades. Here we use a systems biology approach centered on stable isotope labeling by amino acids in cell culture (SILAC) based quantitative phosphoproteomics of cultured mouse DCT cells to map global changes in protein phosphorylation upon acute treatment with a VP type II receptor agonist 1-desamino-8-D-arginine vasopressin (dDAVP). 6330 unique proteins, containing 12333 different phosphorylation sites were identified. 185 sites were altered in abundance following dDAVP. Basophilic motifs were preferential targets for upregulated sites upon dDAVP stimulation, whereas proline-directed motifs were prominent for downregulated sites. Kinase prediction indicated that dDAVP increased AGC and CAMK kinase families’ activities and decreased activity of CDK and MAPK families. Network analysis implicated phosphatidylinositol-4,5-bisphosphate 3-kinase or CAMKK dependent pathways in VP-mediated signaling; pharmacological inhibition of which significantly reduced dDAVP induced increases in phosphorylated NCC at an activating site. In conclusion, this study identifies unique VP signaling cascades in DCT cells that may be important for regulating blood pressure. PMID:26239621

  4. Receptor clustering affects signal transduction at the membrane level in the reaction-limited regime

    NASA Astrophysics Data System (ADS)

    Caré, Bertrand R.; Soula, Hédi A.

    2013-01-01

    Many types of membrane receptors are found to be organized as clusters on the cell surface. We investigate the potential effect of such receptor clustering on the intracellular signal transduction stage. We consider a canonical pathway with a membrane receptor (R) activating a membrane-bound intracellular relay protein (G). We use Monte Carlo simulations to recreate biochemical reactions using different receptor spatial distributions and explore the dynamics of the signal transduction. Results show that activation of G by R is severely impaired by R clustering, leading to an apparent blunted biological effect compared to control. Paradoxically, this clustering decreases the half maximal effective dose (ED50) of the transduction stage, increasing the apparent affinity. We study an example of inter-receptor interaction in order to account for possible compensatory effects of clustering and observe the parameter range in which such interactions slightly counterbalance the loss of activation of G. The membrane receptors’ spatial distribution affects the internal stages of signal amplification, suggesting a functional role for membrane domains and receptor clustering independently of proximity-induced receptor-receptor interactions.

  5. Cortical energy demands of signaling and nonsignaling components in brain are conserved across mammalian species and activity levels

    PubMed Central

    Hyder, Fahmeed; Rothman, Douglas L.; Bennett, Maxwell R.

    2013-01-01

    The continuous need for ion gradient restoration across the cell membrane, a prerequisite for synaptic transmission and conduction, is believed to be a major factor for brain’s high oxidative demand. However, do energy requirements of signaling and nonsignaling components of cortical neurons and astrocytes vary with activity levels and across species? We derived oxidative ATP demand associated with signaling (Ps) and nonsignaling (Pns) components in the cerebral cortex using species-specific physiologic and anatomic data. In rat, we calculated glucose oxidation rates from layer-specific neuronal activity measured across different states, spanning from isoelectricity to awake and sensory stimulation. We then compared these calculated glucose oxidation rates with measured glucose metabolic data for the same states as reported by 2-deoxy-glucose autoradiography. Fixed values for Ps and Pns were able to predict the entire range of states in the rat. We then calculated glucose oxidation rates from human EEG data acquired under various conditions using fixed Ps and Pns values derived for the rat. These calculated metabolic data in human cerebral cortex compared well with glucose metabolism measured by PET. Independent of species, linear relationship was established between neuronal activity and neuronal oxidative demand beyond isoelectricity. Cortical signaling requirements dominated energy demand in the awake state, whereas nonsignaling requirements were ∼20% of awake value. These predictions are supported by 13C magnetic resonance spectroscopy results. We conclude that mitochondrial energy support for signaling and nonsignaling components in cerebral cortex are conserved across activity levels in mammalian species. PMID:23319606

  6. Northeast Artificial Intelligence Consortium (NAIC). Volume 17. High-level adaptive signal processing. Final report, Sep 84-Dec 89

    SciTech Connect

    Nawab, H.; Lesser, V.

    1990-12-01

    The Northeast Artificial Intelligence Consortium (NAIC) was created by the Air Force Systems Command, Rome Air Development Center, and the Office of Scientific Research. Its purpose was to conduct pertinent research in artificial intelligence and to perform activities ancillary to this research. This report describes progress during the existence of the NAIC on the technical research tasks undertaken at the member universities. The topics covered in general are: versatile expert system for equipment maintenance, distributed AI for communications system control, automatic photointerpretation, time-oriented problem solving, speech understanding systems, knowledge base maintenance, hardware architectures for very large system, knowledge based reasoning and planning, and a knowledge acquisition, assistance, and explanation system. The specific topic for this volume is the integration of Artificial Intelligence and Signal Processing for allocating processing resources and adjusting parameters of low-level processing in accordance with evolving high-level interpretations of the signal generating environment.

  7. Systems-Level Lipid Analysis Methodologies for Qualitative and Quantitative Investigation of Lipid Signaling Events During Wound Healing

    PubMed Central

    Wijesinghe, Dayanjan S.; Chalfant, Charles E.

    2013-01-01

    Objective Accumulating evidence implicates a prominent role for lipid signaling molecules in the regulation of wound healing. These lipids regulate hemostasis, onset and resolution of inflammation, migration and proliferation cells, angiogenesis, epithelialization, and remodeling of collagen. The objective of this overview is to demonstrate the applicability of systems level lipid analyses to identify and quantify lipid involved in events leading to wound healing. Approach Current advances in liquid chromatography coupled to tandem mass spectrometry have provided the means for carrying out quantitative and qualitative analysis of lipids at a systems level. This emerging field is collectively referred to as lipidomics and its potential in wound healing research is largely ignored. Results While comprehensive applications of lipidomics in wound healing are limited, studies carried out by the authors as well as others demonstrate distinct changes in the lipidome during the wound healing process. Innovation Until recently, investigations into lipids were limited to the study of a few lipids at a time. Lipidomics approaches provide the capability to quantitatively and qualitatively assay almost the full complement of lipid signaling circuits at the same time. This allows obtaining a system level understanding of changes to the entire lipidome during the wound healing process. Conclusion The technology provides promising approach to understanding new signaling pathways based on lipids involved in wound healing. The understanding gained from such studies has the potential for the development of novel lipid based treatment strategies to promote wound healing. PMID:24527363

  8. Amplifier for measuring low-level signals in the presence of high common mode voltage

    NASA Technical Reports Server (NTRS)

    Lukens, F. E. (Inventor)

    1985-01-01

    A high common mode rejection differential amplifier wherein two serially arranged Darlington amplifier stages are employed and any common mode voltage is divided between them by a resistance network. The input to the first Darlington amplifier stage is coupled to a signal input resistor via an amplifier which isolates the input and presents a high impedance across this resistor. The output of the second Darlington stage is transposed in scale via an amplifier stage which has its input a biasing circuit which effects a finite biasing of the two Darlington amplifier stages.

  9. Acute exercise decreases PTP-1B protein level and improves insulin signaling in the liver of old rats

    PubMed Central

    2013-01-01

    It is now commonly accepted that chronic inflammation associated with obesity during aging induces insulin resistance in the liver. In the present study, we investigated whether the improvement in insulin sensitivity and insulin signaling, mediated by acute exercise, could be associated with modulation of protein-tyrosine phosphatase 1B (PTP-1B) in the liver of old rats. Aging rats were subjected to swimming for two 1.5-h long bouts, separated by a 45 min rest period. Sixteen hours after the exercise, the rats were sacrificed and proteins from the insulin signaling pathway were analyzed by immunoblotting. Our results show that the fat mass was increased in old rats. The reduction in glucose disappearance rate (Kitt) observed in aged rats was restored 16 h after exercise. Aging increased the content of PTP-1B and attenuated insulin signaling in the liver of rats, a phenomenon that was reversed by exercise. Aging rats also increased the IRβ/PTP-1B and IRS-1/PTP-1B association in the liver when compared with young rats. Conversely, in the liver of exercised old rats, IRβ/PTP-1B and IRS-1/PTP-1B association was markedly decreased. Moreover, in the hepatic tissue of old rats, the insulin signalling was decreased and PEPCK and G6Pase levels were increased when compared with young rats. Interestingly, 16 h after acute exercise, the PEPCK and G6Pase protein level were decreased in the old exercised group. These results provide new insights into the mechanisms by which exercise restores insulin signalling in liver during aging. PMID:23442260

  10. Large-Signal Injection-Level Spectroscopy of Impurities in Silicon

    SciTech Connect

    Ahrenkiel, R. K.; Johnston, S. W.

    1998-10-16

    Deep level defects in silicon are identified by measuring the recombination lifetime as a function of the injection level. The basic models for recombination at deep and shallow centers is developed. The defect used for the theoretical model is the well-known interstitial Fe ion in silicon. Data are presented on silicon samples ranging in defect content from intentionally Fe-doped samples to an ultra-pure float-zone grown sample. These data are analyzed in terms of the injection-level spectroscopy model.

  11. Disruption of canonical TGFβ-signaling in murine coronary progenitor cells by low level arsenic

    SciTech Connect

    Allison, Patrick; Huang, Tianfang; Broka, Derrick; Parker, Patti; Barnett, Joey V.; Camenisch, Todd D.

    2013-10-01

    Exposure to arsenic results in several types of cancers as well as heart disease. A major contributor to ischemic heart pathologies is coronary artery disease, however the influences by environmental arsenic in this disease process are not known. Similarly, the impact of toxicants on blood vessel formation and function during development has not been studied. During embryogenesis, the epicardium undergoes proliferation, migration, and differentiation into several cardiac cell types including smooth muscle cells which contribute to the coronary vessels. The TGFβ family of ligands and receptors is essential for developmental cardiac epithelial to mesenchymal transition (EMT) and differentiation into coronary smooth muscle cells. In this in vitro study, 18 hour exposure to 1.34 μM arsenite disrupted developmental EMT programming in murine epicardial cells causing a deficit in cardiac mesenchyme. The expression of EMT genes including TGFβ2, TGFβ receptor-3, Snail, and Has-2 are decreased in a dose-dependent manner following exposure to arsenite. TGFβ2 cell signaling is abrogated as detected by decreases in phosphorylated Smad2/3 when cells are exposed to 1.34 μM arsenite. There is also loss of nuclear accumulation pSmad due to arsenite exposure. These observations coincide with a decrease in vimentin positive mesenchymal cells invading three-dimensional collagen gels. However, arsenite does not block TGFβ2 mediated smooth muscle cell differentiation by epicardial cells. Overall these results show that arsenic exposure blocks developmental EMT gene programming in murine coronary progenitor cells by disrupting TGFβ2 signals and Smad activation, and that smooth muscle cell differentiation is refractory to this arsenic toxicity. - Highlights: • Arsenic blocks TGFβ2 induced expression of EMT genes. • Arsenic blocks TGFβ2 triggered Smad2/3 phosphorylation and nuclear translocation. • Arsenic blocks epicardial cell differentiation into cardiac mesenchyme.

  12. Clock genes and cancer.

    PubMed

    Wood, Patricia A; Yang, Xiaoming; Hrushesky, William J M

    2009-12-01

    Period genes ( Per2, Per1) are essential circadian clock genes. They also function as negative growth regulators. Per2 mutant mice show de novo and radiation-induced epithelial hyperplasia, tumors, and an abnormal DNA damage response. Human tumors show Period gene mutations or decreased expression. Other murine clock gene mutations are not associated with a tumor prone phenotype. Shift work and nocturnal light exposure are associated with circadian clock disruption and with increased cancer risk. The mechanisms responsible for the connection between the circadian clock and cancer are not well defined. We propose that circadian disruption per se is not uniformly tumor promoting and the mechanisms for tumor promotion by specific circadian clock disturbances will differ dependent upon the genes and pathways involved. We propose that Period clock gene mutations promote tumorigenesis by unique molecular pathways. Per2 and Per1 modulate beta-catenin and cell proliferation in colon and non-colon cancer cells. Per2 mutation increases intestinal beta-catenin levels and colon polyp formation. Per2 mutation also increases Apc(Min/+)-mediated intestinal and colonic polyp formation. Intestinal tumorigenesis per se may also alter clock function as a result of increased beta-catenin destabilizing PER2 protein. Levels and circadian rhythm of PER2 in Apc(Min/+) mouse intestine are markedly decreased, and selective abnormalities in intestinal clock gene and clock-controlled gene expression are seen. We propose that tumor promotion by loss of PERIOD clock proteins is unique to these clock genes as a result of altered beta-catenin signaling and DNA damage response. PERIOD proteins may offer new targets for cancer prevention and control.

  13. [Remote signaling of radiation damage to the extracellular space in mice with various levels of genetically determined radio sensitivity].

    PubMed

    Senuk, O F; Kovalev, V A; Krul', N I; Zhidkov, A V; Chemerskiĭ, G F; Kireev, S S; Gorovoĭ, L F; Gergeĭ, T

    2013-01-01

    The search results of "bystander" signals are presented at different model of influence of IR on Balb/c and C57bl/6 mice, characterized by different levels of genetically determined sensitivity to IR influence. We used the following models of IR influence: 1) external gamma-quanta influence from small samples of nuclear fuel from the CNPP 4th power unit modified in the course of the accident in 1986, which are 99% connected with 137Cs, with the total dose of irradiation of about 5.0 Gy for 16 hours and accumulated dose of 0.290 Gy for 231 day of exposure, 2) internal intake of 137Cs with water for 40 days. It is shown that cells of different types (splenocytes, hepatocytes, bone marrow and astroglia cells) irrespective of a model of IR influence produce the factors, which failed to be identified in this research, raising the SSF levels in the DNA of non-irradiated cells. Under conditions of a single exposure to gamma-field external irradiation at a dose of about 5.0 Gy, the intensity of production of "bystander" signals is higher in the mice with the raised level of genetically determined sensitivity to RI (Balb/c). Under the same conditions of gamma-field exposure, induction of additional levels of SSF in the DNA of non-irradiated cells is detected for at least one month after IR exposure. Intraperitoneal injection of melanin in the melanin-glucan complex from fungus F. fomentarius before irradiation exposure promotes an essential decrease in the production of "bystander" signals, testifying in favor of the free radical nature of their certain part.

  14. Ouabain binding to Na+,K+-ATPase relaxes cell attachment and sends a specific signal (NACos) to the nucleus.

    PubMed

    Contreras, R G; Flores-Maldonado, C; Lázaro, A; Shoshani, L; Flores-Benitez, D; Larré, I; Cereijido, M

    2004-04-01

    Abstract. In previous work we described a "P-->A mechanism" that transduces occupancy of the pump ( P) by ouabain into changes in phosphorylation, stimulation of mitogen-activated protein kinase (MAPK), and endocytosis of cell-cell- and cell-substrate-attaching molecules ( A), thereby causing a release of the cell from the monolayer. In the present work we try to understand the mechanism of this effect; whether, in order to trigger the P-->A mechanism, ouabain should block the pumping activity of Na(+),K(+)-ATPase as pump, or whether it would suffice that the drug occupies this enzyme as a receptor. We assay a series of drugs known to act on the pump, such as ouabain, digoxin, digitoxin, palytoxin, oligomycin, strophanthidin, neothyoside-A, proscillaridin-A, etc. We gauge their ability to block the pump by measuring the K(+) content in the cells, and their ability to detach the cells from the monolayer by determining the amount of protein remaining in the culturing well. None of the drugs tested was able to cause detachment without stopping the pump. Ouabain also enhances phosphorylation, yet pump inhibition and signal transduction do not seem to be intimately associated in a causal chain, but to occur simultaneously. To investigate the response of the site of cell attachment, we analyze the position of beta-catenin by fluorescence confocal microscopy, and find that this adherent junction-associated molecule is sent to the nucleus, where it is known to act as a transcriptional cofactor.

  15. Integrated CMOS photodetectors and signal processing for very low-level chemical sensing with the bioluminescent bioreporter integrated circuit

    NASA Technical Reports Server (NTRS)

    Bolton, Eric K.; Sayler, Gary S.; Nivens, David E.; Rochelle, James M.; Ripp, Steven; Simpson, Michael L.

    2002-01-01

    We report an integrated CMOS microluminometer optimized for the detection of low-level bioluminescence as part of the bioluminescent bioreporter integrated circuit (BBIC). This microluminometer improves on previous devices through careful management of the sub-femtoampere currents, both signal and leakage, that flow in the front-end processing circuitry. In particular, the photodiode is operated with a reverse bias of only a few mV, requiring special attention to the reset circuitry of the current-to-frequency converter (CFC) that forms the front-end circuit. We report a sub-femtoampere leakage current and a minimum detectable signal (MDS) of 0.15 fA (1510 s integration time) using a room temperature 1.47 mm2 CMOS photodiode. This microluminometer can detect luminescence from as few as 5000 fully induced Pseudomonas fluorescens 5RL bacterial cells. c2002 Elsevier Science B.V. All rights reserved.

  16. Plastidial fatty acid levels regulate resistance gene-dependent defense signaling in Arabidopsis.

    PubMed

    Chandra-Shekara, A C; Venugopal, Srivathsa C; Barman, Subhankar Roy; Kachroo, Aardra; Kachroo, Pradeep

    2007-04-24

    In Arabidopsis, resistance to Turnip Crinkle Virus (TCV) depends on the resistance (R) gene, HRT, and the recessive locus rrt. Resistance also depends on salicylic acid (SA), EDS1, and PAD4. Exogenous application of SA confers resistance in RRT-containing plants by increasing HRT transcript levels in a PAD4-dependent manner. Here we report that reduction of oleic acid (18:1) can also induce HRT gene expression and confer resistance to TCV. However, the 18:1-regulated pathway is independent of SA, rrt, EDS1, and PAD4. Reducing the levels of 18:1, via a mutation in the SSI2-encoded stearoyl-acyl carrier protein-desaturase, or by exogenous application of glycerol, increased transcript levels of HRT as well as several other R genes. Second-site mutations in the ACT1-encoded glycerol-3-phosphate acyltransferase or GLY1-encoded glycerol-3-phosphate dehydrogenase restored 18:1 levels in HRT ssi2 plants and reestablished a dependence on rrt. Resistance to TCV and HRT gene expression in HRT act1 plants was inducible by SA but not by glycerol, whereas that in HRT pad4 plants was inducible by glycerol but not by SA. The low 18:1-mediated induction of R gene expression was also dependent on ACT1 but independent of EDS1, PAD4, and RAR1. Intriguingly, TCV inoculation did not activate this 18:1-regulated pathway in HRT plants, but instead resulted in the induction of several genes that encode 18:1-synthesizing isozymes. These results suggest that the 18:1-regulated pathway may be specifically targeted during pathogen infection and that altering 18:1 levels may serve as a unique strategy for promoting disease resistance.

  17. Sea Level Rise and Land Subsidence Contributions to the Signals from the Tide Gauges of China

    NASA Astrophysics Data System (ADS)

    Parker, Albert

    2016-06-01

    The tide gauges measure the local oscillations of the sea level vs. the tide gauge instrument. The tide gauge instrument is generally subjected to the general subsidence or uplift of the nearby inland, plus some additional subsidence for land compaction and other localised phenomena. The paper proposes a non-linear model of the relative sea level oscillations including a long term trend for the absolute sea level rise, another term for the subsidence of the instrument, and finally a sinusoidal approximation for the cyclic oscillations of periodicities up to decades. This non-linear model is applied to the tide gauges of China. The paper shows that the limited information available for China does not permit to infer any proper trend for the relative rates of rise, as the tide gauge records are all short or incomplete and the vertical movement of the tide gauge instruments is unassessed. The only tide gauge record of sufficient length that may be assembled for China is obtained by combining the North Point and Quarry Bay tide gauges in Hong Kong (NPQB). This NQPB composite tide gauge record is shown to have similarities with the tide gauge records of Sydney, equally in the West pacific, and San Diego, in the east Pacific, oscillating about the longer term trend mostly determined by the local subsidence. As it is very well known that China generally suffers of land subsidence, and the tide gauge installations may suffer of additional subsidence vs. the inland, it may be concluded from the analysis of the other worldwide tide gauges that the sea levels of China are very likely rising about the same amount of the subsidence of the tide gauges, with the sea level acceleration component still negligible.

  18. Photoperiodic changes in endocannabinoid levels and energetic responses to altered signalling at CB1 receptors in Siberian hamsters.

    PubMed

    Ho, J M; Smith, N S; Adams, S A; Bradshaw, H B; Demas, G E

    2012-07-01

    Siberian hamsters (Phodopus sungorus) adapt to seasonal environmental conditions with marked changes in body mass, primarily in the form of adiposity. Winter-like conditions (e.g. short days) are sufficient to decrease body mass by approximately 30% in part via reductions in food intake. The neuroendocrine mechanisms responsible for these changes are not well understood, and homeostatic orexigenic/anorexigenic systems of the hypothalamus provide little explanation. We investigated the potential role of endocannabinoids, which are known modulators of appetite and metabolism, in mediating seasonal changes in energy balance. Specifically, we housed hamsters in long or short days for 0, 3, or 9 weeks and measured endocannabinoid levels in the hypothalamus, brainstem, liver and retroperitoneal white adipose tissue (RWAT). An additional group of males housed in short days for 25 weeks were also compared with long-day controls. Following 9 weeks in short days, levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) were significantly elevated in RWAT and reduced in brainstem, although they returned to long-day levels by week 25 in short-day males that had cycled back to summer-like energy balance. Endocannabinoid levels in these tissues correlated significantly with adiposity and change in body mass. No photoperiodic changes were observed in the hypothalamus or liver; however, sex differences in 2-AG levels were found in the liver (males > females). We further tested the effects of CB(1) receptor signalling on ingestive behaviour. Five daily injections of CB(1) antagonist SR141716 significantly reduced food intake and body mass but not food hoarding. Although the CB(1) agonist arachidonyl-2-chloroethylamide did not appreciably affect either ingestive behaviour, body mass was significantly elevated following 2 days of injections. Taken altogether, these findings demonstrate that endocannabinoid levels vary with sex and photoperiod in a site-specific manner, and that

  19. Diminished FoxP2 levels affect dopaminergic modulation of corticostriatal signaling important to song variability.

    PubMed

    Murugan, Malavika; Harward, Stephen; Scharff, Constance; Mooney, Richard

    2013-12-18

    Mutations of the FOXP2 gene impair speech and language development in humans and shRNA-mediated suppression of the avian ortholog FoxP2 disrupts song learning in juvenile zebra finches. How diminished FoxP2 levels affect vocal control and alter the function of neural circuits important to learned vocalizations remains unclear. Here we show that FoxP2 knockdown in the songbird striatum disrupts developmental and social modulation of song variability. Recordings in anesthetized birds show that FoxP2 knockdown interferes with D1R-dependent modulation of activity propagation in a corticostriatal pathway important to song variability, an effect that may be partly attributable to reduced D1R and DARPP-32 protein levels. Furthermore, recordings in singing birds reveal that FoxP2 knockdown prevents social modulation of singing-related activity in this pathway. These findings show that reduced FoxP2 levels interfere with the dopaminergic modulation of vocal variability, which may impede song and speech development by disrupting reinforcement learning mechanisms.

  20. Is there a signal of sea-level rise in Chesapeake Bay salinity?

    NASA Astrophysics Data System (ADS)

    Hilton, T. W.; Najjar, R. G.; Zhong, L.; Li, M.

    2008-09-01

    We evaluate the hypothesis that sea-level rise over the second half of the 20th century has led to detectable increases in Chesapeake Bay salinity. We exploit a simple, statistical model that predicts monthly mean salinity as a function of Susquehanna River flow in 23 segments of the main stem Chesapeake Bay. The residual (observed minus modeled) salinity exhibits statistically significant linear (p < 0.05) trends between 1949 and 2006 in 13 of the 23 segments of the bay. The salinity change estimated from the trend line over this period varies from -2.0 to 2.2, with 10 of the 13 cells showing positive changes. The mean and median salinity changes over all 23 cells are 0.47 and 0.72; over the 13 cells with significant trends they are 0.71 and 1.1. We ran a hydrodynamic model of the bay under present-day and reduced sea level conditions and found a bay-average salinity increase of about 0.5, which supports the hypothesis that the salinity residual trends have a significant component due to sea-level rise. Uncertainties remain, however, due to the spatial and temporal extent of historical salinity data and the infilling of the bay due to sedimentation. The salinity residuals also exhibit interannual variability, with peaks occurring at intervals of roughly 7 to 9 years, which are partially explained by Atlantic Shelf salinity, Potomac River flow and the meridional component of wind stress.

  1. Growth of Streptococcus mutans in Biofilms Alters Peptide Signaling at the Sub-population Level

    PubMed Central

    Shields, Robert C.; Burne, Robert A.

    2016-01-01

    Streptococcus mutans activates multiple cellular processes in response to the formation of a complex between comX-inducing peptide (XIP) and the ComR transcriptional regulator. Bulk phase and microfluidic experiments previously revealed that ComR-dependent activation of comX is altered by pH and by carbohydrate source. Biofilm formation is a major factor in bacterial survival and virulence in the oral cavity. Here, we sought to determine the response of S. mutans biofilm cells to XIP during different stages of biofilm maturation. Using flow cytometry and confocal microscopy, we showed that exogenous addition of XIP to early biofilms resulted in robust comX activation. However, as the biofilms matured, increasing amounts of XIP were required to activate comX expression. Single-cell analysis demonstrated that the entire population was responding to XIP with activation of comX in early biofilms, but only a sub-population was responding in mature biofilms. The sub-population response of mature biofilms was retained when the cells were dispersed and then treated with XIP. The proportion and intensity of the bi-modal response of mature biofilm cells was altered in mutants lacking the Type II toxins MazF and RelE, or in a strain lacking the (p)ppGpp synthase/hydrolase RelA. Thus, competence signaling is markedly altered in cells growing in mature biofilms, and pathways that control cell death and growth/survival decisions modulate activation of comX expression in these sessile populations. PMID:27471495

  2. Can upwelling signals be detected in intertidal fishes of different trophic levels?

    PubMed

    Pulgar, J; Poblete, E; Alvarez, M; Morales, J P; Aranda, B; Aldana, M; Pulgar, V M

    2013-11-01

    For intertidal fishes belonging to three species, the herbivore Scartichthys viridis (Blenniidae), the omnivore Girella laevifrons (Kyphosidae) and the carnivore Graus nigra (Kyphosidae), mass and body size relationships were higher in individuals from an upwelling zone compared with those from a non-upwelling zone. RNA:DNA were higher in the herbivores and omnivores from the upwelling zone. Higher biomass and RNA:DNA in the upwelling intertidal fishes may be a consequence of an increased exposure to higher nutrient availability, suggesting that increased physiological conditioning in vertebrates from upwelling areas can be detected and measured using intertidal fishes of different trophic levels.

  3. Arsenite and insulin exhibit opposing effects on epidermal growth factor receptor and keratinocyte proliferative potential

    SciTech Connect

    Patterson, Timothy J.; Rice, Robert H. . E-mail: rhrice@ucdavis.edu

    2007-05-15

    Previous work has suggested that arsenic exposure contributes to skin carcinogenesis by preserving the proliferative potential of human epidermal keratinocytes, thereby slowing the exit of putative target stem cells into the differentiation pathway. To find a molecular basis for this action, present work has explored the influence of arsenite on keratinocyte responses to epidermal growth factor (EGF). The ability of cultured keratinocytes to found colonies upon passaging several days after confluence was preserved by arsenite and EGF in an additive fashion, but neither was effective when the receptor tyrosine kinase activity was inhibited. Arsenite prevented the loss of EGF receptor protein and phosphorylation of tyrosine 1173, preserving its capability to signal. The level of nuclear {beta}-catenin was higher in cells treated with arsenite and EGF in parallel to elevated colony forming ability, and expression of a dominant negative {beta}-catenin suppressed the increase in both colony forming ability and yield of putative stem cells induced by arsenite and EGF. As judged by expression of three genes regulated by {beta}-catenin, this transcription factor had substantially higher activity in the arsenite/EGF-treated cells. Trivalent antimony exhibited the same effects as arsenite. A novel finding is that insulin in the medium induced the loss of EGF receptor protein, which was largely prevented by arsenite exposure.

  4. All-optical demultiplexing of 16-QAM signals into QPSK tributaries using four-level optical phase quantizers.

    PubMed

    Bogris, Adonis

    2014-04-01

    The potential of four-level optical phase quantizers toward coherent processing of advanced modulation formats, such as 16-QAM, is proposed and numerically demonstrated. The work shows that phase quantization achieved in fiber-based phase-sensitive amplifiers can demultiplex 16-QAM into two quadrature phase shift keying (QPSK) signals, enabling subchannel switching. The numerical study highlights the impact of the quantizer transfer function on the performance of the demultiplexing process and numerically calculates the bit error rate for each QPSK tributary after the demultiplexing procedure.

  5. Control of Neural Daughter Cell Proliferation by Multi-level Notch/Su(H)/E(spl)-HLH Signaling

    PubMed Central

    Bivik, Caroline; MacDonald, Ryan B.; Gunnar, Erika; Mazouni, Khalil; Schweisguth, Francois; Thor, Stefan

    2016-01-01

    The Notch pathway controls proliferation during development and in adulthood, and is frequently affected in many disorders. However, the genetic sensitivity and multi-layered transcriptional properties of the Notch pathway has made its molecular decoding challenging. Here, we address the complexity of Notch signaling with respect to proliferation, using the developing Drosophila CNS as model. We find that a Notch/Su(H)/E(spl)-HLH cascade specifically controls daughter, but not progenitor proliferation. Additionally, we find that different E(spl)-HLH genes are required in different neuroblast lineages. The Notch/Su(H)/E(spl)-HLH cascade alters daughter proliferation by regulating four key cell cycle factors: Cyclin E, String/Cdc25, E2f and Dacapo (mammalian p21CIP1/p27KIP1/p57Kip2). ChIP and DamID analysis of Su(H) and E(spl)-HLH indicates direct transcriptional regulation of the cell cycle genes, and of the Notch pathway itself. These results point to a multi-level signaling model and may help shed light on the dichotomous proliferative role of Notch signaling in many other systems. PMID:27070787

  6. Control of Neural Daughter Cell Proliferation by Multi-level Notch/Su(H)/E(spl)-HLH Signaling.

    PubMed

    Bivik, Caroline; MacDonald, Ryan B; Gunnar, Erika; Mazouni, Khalil; Schweisguth, Francois; Thor, Stefan

    2016-04-01

    The Notch pathway controls proliferation during development and in adulthood, and is frequently affected in many disorders. However, the genetic sensitivity and multi-layered transcriptional properties of the Notch pathway has made its molecular decoding challenging. Here, we address the complexity of Notch signaling with respect to proliferation, using the developing Drosophila CNS as model. We find that a Notch/Su(H)/E(spl)-HLH cascade specifically controls daughter, but not progenitor proliferation. Additionally, we find that different E(spl)-HLH genes are required in different neuroblast lineages. The Notch/Su(H)/E(spl)-HLH cascade alters daughter proliferation by regulating four key cell cycle factors: Cyclin E, String/Cdc25, E2f and Dacapo (mammalian p21CIP1/p27KIP1/p57Kip2). ChIP and DamID analysis of Su(H) and E(spl)-HLH indicates direct transcriptional regulation of the cell cycle genes, and of the Notch pathway itself. These results point to a multi-level signaling model and may help shed light on the dichotomous proliferative role of Notch signaling in many other systems. PMID:27070787

  7. Radiocarbon signal of a low and intermediate level radioactive waste disposal facility in nearby trees.

    PubMed

    Janovics, R; Kelemen, D I; Kern, Z; Kapitány, S; Veres, M; Jull, A J T; Molnár, M

    2016-03-01

    Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional (14)C level. The (14)C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the (14)C data of the atmospheric (14)C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site. PMID:26704325

  8. Effects of Varying Gravity Levels on fNIRS Headgear Performance and Signal Recovery

    NASA Technical Reports Server (NTRS)

    Mackey, Jeffrey R.; Harrivel, Angela R.; Adamovsky, Grigory; Lewandowski, Beth E.; Gotti, Daniel J.; Tin, Padetha; Floyd, Bertram M.

    2013-01-01

    This paper reviews the effects of varying gravitational levels on functional Near-Infrared Spectroscopy (fNIRS) headgear. The fNIRS systems quantify neural activations in the cortex by measuring hemoglobin concentration changes via optical intensity. Such activation measurement allows for the detection of cognitive state, which can be important for emotional stability, human performance and vigilance optimization, and the detection of hazardous operator state. The technique depends on coupling between the fNIRS probe and users skin. Such coupling may be highly susceptible to motion if probe-containing headgear designs are not adequately tested. The lack of reliable and self-applicable headgear robust to the influence of motion artifact currently inhibits its operational use in aerospace environments. Both NASAs Aviation Safety and Human Research Programs are interested in this technology as a method of monitoring cognitive state of pilots and crew.

  9. Radiocarbon signal of a low and intermediate level radioactive waste disposal facility in nearby trees.

    PubMed

    Janovics, R; Kelemen, D I; Kern, Z; Kapitány, S; Veres, M; Jull, A J T; Molnár, M

    2016-03-01

    Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional (14)C level. The (14)C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the (14)C data of the atmospheric (14)C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site.

  10. Notch-1 expression levels in 3T3-L1 cells influence ras signaling and transformation by oncogenic ras.

    PubMed

    Ruiz-Hidalgo, M J; Garcés, C; Laborda, J

    1999-04-01

    Notch proteins participate in interactions between several cell types involved on the specification of numerous cell fates during development. We previously showed that enforced downregulation of Notch-1 expression prevented adipogenesis of 3T3-L1 cells. Since adipogenesis of 3T3-L1 cells can be induced by oncogenic ras, we studied whether this was also the case in 3T3-L1 cells with decreased levels of Notch-1 expression. We found that oncogenic ras induces transformation and not differentiation of 3T3-L1 cells with diminished levels of Notch-1. This result suggests that Notch-1 is implicated in the interpretation of signals leading to activation of p21 Ras.

  11. Functional magnetic resonance imaging blood oxygenation level-dependent signal and magnetoencephalography evoked responses yield different neural functionality in reading.

    PubMed

    Vartiainen, Johanna; Liljeström, Mia; Koskinen, Miika; Renvall, Hanna; Salmelin, Riitta

    2011-01-19

    It is often implicitly assumed that the neural activation patterns revealed by hemodynamic methods, such as functional magnetic resonance imaging (fMRI), and electrophysiological methods, such as magnetoencephalography (MEG) and electroencephalography (EEG), are comparable. In early sensory processing that seems to be the case, but the assumption may not be correct in high-level cognitive tasks. For example, MEG and fMRI literature of single-word reading suggests differences in cortical activation, but direct comparisons are lacking. Here, while the same human participants performed the same reading task, analysis of MEG evoked responses and fMRI blood oxygenation level-dependent (BOLD) signals revealed marked functional and spatial differences in several cortical areas outside the visual cortex. Divergent patterns of activation were observed in the frontal and temporal cortex, in accordance with previous separate MEG and fMRI studies of reading. Furthermore, opposite stimulus effects in the MEG and fMRI measures were detected in the left occipitotemporal cortex: MEG evoked responses were stronger to letter than symbol strings, whereas the fMRI BOLD signal was stronger to symbol than letter strings. The EEG recorded simultaneously during MEG and fMRI did not indicate neurophysiological differences that could explain the observed functional discrepancies between the MEG and fMRI results. Acknowledgment of the complementary nature of hemodynamic and electrophysiological measures, as reported here in a cognitive task using evoked response analysis in MEG and BOLD signal analysis in fMRI, represents an essential step toward an informed use of multimodal imaging that reaches beyond mere combination of location and timing of neural activation.

  12. Specific induction of cranial placode cells from Xenopus ectoderm by modulating the levels of BMP, Wnt, and FGF signaling.

    PubMed

    Watanabe, Tomoko; Kanai, Yuna; Matsukawa, Shinya; Michiue, Tatsuo

    2015-10-01

    The neural-epidermal boundary tissues include the neural crest and preplacodal ectoderm (PPE) as primordial constituents. The PPE region is essential for the development of various sensory and endocrine organs, such as the anterior lobe of the pituitary, olfactory epithelium, lens, trigeminal ganglion, and otic vesicles. During gastrulation, a neural region is induced in ectodermal cells that interacts with mesendodermal tissue and responds to several secreted factors. Among them, inhibition of bone morphogenetic protein (BMP) in the presumptive neuroectoderm is essential for the induction of neural regions, and formation of a Wnt and fibroblast growth factor (FGF) signaling gradient along the midline determines anterior-posterior patterning. In this study, we attempted to specifically induce PPE cells from undifferentiated Xenopus cells by regulating BMP, Wnt, and FGF signaling. We showed that the proper level of BMP inhibition with an injection of truncated BMP receptor or treatment with a chemical antagonist triggered the expression of PPE genes. In addition, by varying the amount of injected chordin, we optimized specific expression of the PPE genes. PPE gene expression is increased by adding an appropriate dose of an FGF receptor antagonist. Furthermore, co-injection with either wnt8 or the Wnt inhibitor dkk-1 altered the expression levels of several region-specific genes according to the injected dose. We specifically induced PPE cell differentiation in animal cap cells from early-stage Xenopus embryos by modulating BMP, Wnt, and FGF signaling. This is not the first research on placode induction, but our simple method could potentially be applied to mammalian stem cell systems. PMID:26249012

  13. Endocannabinoid signaling enhances visual responses through modulation of intracellular chloride levels in retinal ganglion cells

    PubMed Central

    Miraucourt, Loïs S; Tsui, Jennifer; Gobert, Delphine; Desjardins, Jean-François; Schohl, Anne; Sild, Mari; Spratt, Perry; Castonguay, Annie; De Koninck, Yves; Marsh-Armstrong, Nicholas; Wiseman, Paul W; Ruthazer, Edward S

    2016-01-01

    Type 1 cannabinoid receptors (CB1Rs) are widely expressed in the vertebrate retina, but the role of endocannabinoids in vision is not fully understood. Here, we identified a novel mechanism underlying a CB1R-mediated increase in retinal ganglion cell (RGC) intrinsic excitability acting through AMPK-dependent inhibition of NKCC1 activity. Clomeleon imaging and patch clamp recordings revealed that inhibition of NKCC1 downstream of CB1R activation reduces intracellular Cl− levels in RGCs, hyperpolarizing the resting membrane potential. We confirmed that such hyperpolarization enhances RGC action potential firing in response to subsequent depolarization, consistent with the increased intrinsic excitability of RGCs observed with CB1R activation. Using a dot avoidance assay in freely swimming Xenopus tadpoles, we demonstrate that CB1R activation markedly improves visual contrast sensitivity under low-light conditions. These results highlight a role for endocannabinoids in vision and present a novel mechanism for cannabinoid modulation of neuronal activity through Cl− regulation. DOI: http://dx.doi.org/10.7554/eLife.15932.001 PMID:27501334

  14. Endocannabinoid signaling enhances visual responses through modulation of intracellular chloride levels in retinal ganglion cells.

    PubMed

    Miraucourt, Loïs S; Tsui, Jennifer; Gobert, Delphine; Desjardins, Jean-François; Schohl, Anne; Sild, Mari; Spratt, Perry; Castonguay, Annie; De Koninck, Yves; Marsh-Armstrong, Nicholas; Wiseman, Paul W; Ruthazer, Edward S

    2016-01-01

    Type 1 cannabinoid receptors (CB1Rs) are widely expressed in the vertebrate retina, but the role of endocannabinoids in vision is not fully understood. Here, we identified a novel mechanism underlying a CB1R-mediated increase in retinal ganglion cell (RGC) intrinsic excitability acting through AMPK-dependent inhibition of NKCC1 activity. Clomeleon imaging and patch clamp recordings revealed that inhibition of NKCC1 downstream of CB1R activation reduces intracellular Cl(-) levels in RGCs, hyperpolarizing the resting membrane potential. We confirmed that such hyperpolarization enhances RGC action potential firing in response to subsequent depolarization, consistent with the increased intrinsic excitability of RGCs observed with CB1R activation. Using a dot avoidance assay in freely swimming Xenopus tadpoles, we demonstrate that CB1R activation markedly improves visual contrast sensitivity under low-light conditions. These results highlight a role for endocannabinoids in vision and present a novel mechanism for cannabinoid modulation of neuronal activity through Cl(-) regulation. PMID:27501334

  15. Feature-level signal processing for near-real-time odor identification

    NASA Astrophysics Data System (ADS)

    Roppel, Thaddeus A.; Padgett, Mary Lou; Waldemark, Joakim T. A.; Wilson, Denise M.

    1998-09-01

    Rapid detection and classification of odor is of particular interest in applications such as manufacturing of consumer items, food processing, drug and explosives detection, and battlefield situation assessment. Various detection and classification techniques are under investigation so that end users can have access to useful information from odor sensor arrays in near-real-time. Feature-level data clustering and classification techniques are proposed that are (1) parallelizable to permit efficient hardware implementation, (2) adaptable to readily incorporate new data classes, (3) capable of gracefully handling outlier data points and failed sensor conditions, and (4) can provide confidence intervals and/or a traceable decision record along with each classification to permit validation and verification. Results from using specific techniques will be presented and compared. The techniques studied include principal components analysis, automated outlier determination, radial basis functions (RBF), multi-layer perceptrons (MLP), and pulse-coupled neural networks (PCNN). The results reported here are based on data from a testbed in which a gas sensor array is exposed to odor samples on a continuous basis. We have reported previously that more detailed and faster discrimination can be obtained by using sensor transient response in addition to steady state response. As the size of the data set grows we are able to more accurately model performance of a sensor array under realistic conditions.

  16. Distinguishing base-level change and climate signals in a Cretaceous alluvial sequence

    USGS Publications Warehouse

    White, T.; Witzke, B.; Ludvigson, G. A.; Brenner, R.

    2005-01-01

    We present the results of oxygen isotope and electron-microprobe analyses of sphaerosiderites obtained from Cretaceous paleosols in Iowa. The sphaerosiderite ??18O values record Cretaceous meteoric groundwater chemistry and an overall waning of brackish groundwater inundation during alluvial-plain aggradation and soil genesis. We focus on horizons that precipitated from freshwater, in which ??18O values ranging from -3.30??? to -6.8??? relative to the Peedee belemnite standard are interpreted to record variations in the Cretaceous atmospheric hydrologic cycle. During relative sea-level highstands, moisture was derived from the Cretaceous Western Interior Seaway, whereas during lowstands, when the seaway narrowed and occasionally withdrew from the Midcontinent, the dominance of hemispheric-scale atmospheric moisture transport initiated in the tropical Tethys Ocean led to decreased precipitation rates. These processes did not operate like a switch, but rather as a continuum of competing moisture sources and mechanisms of transport between the nearby epicontinental sea and the distant tropics. The sphaerosiderite data demonstrate (1) temporal variation in the intensity of hemispheric-scale atmospheric moisture transport and (2) long-term amplification of the global hydrologic cycle marked by extreme 18O depletion at the Albian-Cenomanian boundary. ?? 2005 Geological Society of America.

  17. Integument coloration signals reproductive success, heterozygosity, and antioxidant levels in chick-rearing black-legged kittiwakes

    NASA Astrophysics Data System (ADS)

    Leclaire, Sarah; White, Joël; Arnoux, Emilie; Faivre, Bruno; Vetter, Nathanaël; Hatch, Scott A.; Danchin, Étienne

    2011-09-01

    Carotenoid pigments are important for immunity and as antioxidants, and carotenoid-based colors are believed to provide honest signals of individual quality. Other colorless but more efficient antioxidants such as vitamins A and E may protect carotenoids from bleaching. Carotenoid-based colors have thus recently been suggested to reflect the concentration of such colorless antioxidants, but this has rarely been tested. Furthermore, although evidence is accruing for multiple genetic criteria for mate choice, carotenoid-based colors have rarely been shown to reflect both phenotypic and genetic quality. In this study, we investigated whether gape, tongue, eye-ring, and bill coloration of chick-rearing black-legged kittiwakes Rissa tridactyla reflected circulating levels of carotenoids and vitamins A and E. We further investigated whether integument coloration reflected phenotypic (body condition and fledging success) and genetic quality (heterozygosity). We found that the coloration of fleshy integuments was correlated with carotenoid and vitamin A levels and fledging success but only in males. Furthermore, the coloration of tongue and eye-ring was correlated with heterozygosity in both males and females. Integument colors might therefore be reliable signals of individual quality used by birds to adjust their parental care during the chick-rearing period.

  18. Integument coloration signals reproductive success, heterozygosity, and antioxidant levels in chick-rearing black-legged kittiwakes

    USGS Publications Warehouse

    Leclaire, S.; White, J.; Arnoux, E.; Faivre, B.; Vetter, N.; Hatch, Shyla A.; Danchin, E.

    2011-01-01

    Carotenoid pigments are important for immunity and as antioxidants, and carotenoid-based colors are believed to provide honest signals of individual quality. Other colorless but more efficient antioxidants such as vitamins A and E may protect carotenoids from bleaching. Carotenoid-based colors have thus recently been suggested to reflect the concentration of such colorless antioxidants, but this has rarely been tested. Furthermore, although evidence is accruing for multiple genetic criteria for mate choice, carotenoid-based colors have rarely been shown to reflect both phenotypic and genetic quality. In this study, we investigated whether gape, tongue, eye-ring, and bill coloration of chick-rearing black-legged kittiwakes Rissa tridactyla reflected circulating levels of carotenoids and vitamins A and E. We further investigated whether integument coloration reflected phenotypic (body condition and fledging success) and genetic quality (heterozygosity). We found that the coloration of fleshy integuments was correlated with carotenoid and vitamin A levels and fledging success but only in males. Furthermore, the coloration of tongue and eye-ring was correlated with heterozygosity in both males and females. Integument colors might therefore be reliable signals of individual quality used by birds to adjust their parental care during the chick-rearing period. ?? Springer-Verlag 2011.

  19. Instantaneous Real-Time Kinematic Decimeter-Level Positioning with BeiDou Triple-Frequency Signals over Medium Baselines

    PubMed Central

    He, Xiyang; Zhang, Xiaohong; Tang, Long; Liu, Wanke

    2015-01-01

    Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS) triple-frequency signals over medium distances. The ambiguities of two extra-wide-lane (EWL) combinations are fixed first, and then a wide lane (WL) combination is reformed based on the two EWL combinations for positioning. Theoretical analysis and empirical analysis is given of the ambiguity fixing rate and the positioning accuracy of the presented method. The results indicate that the ambiguity fixing rate can be up to more than 98% when using BDS medium baseline observations, which is much higher than that of dual-frequency Hatch-Melbourne-Wübbena (HMW) method. As for positioning accuracy, decimeter level accuracy can be achieved with this method, which is comparable to that of carrier-smoothed code differential positioning method. Signal interruption simulation experiment indicates that the proposed method can realize fast high-precision positioning whereas the carrier-smoothed code differential positioning method needs several hundreds of seconds for obtaining high precision results. We can conclude that a relatively high accuracy and high fixing rate can be achieved for triple-frequency WL method with single-epoch observations, displaying significant advantage comparing to traditional carrier-smoothed code differential positioning method. PMID:26703614

  20. Instantaneous Real-Time Kinematic Decimeter-Level Positioning with BeiDou Triple-Frequency Signals over Medium Baselines.

    PubMed

    He, Xiyang; Zhang, Xiaohong; Tang, Long; Liu, Wanke

    2015-01-01

    Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS) triple-frequency signals over medium distances. The ambiguities of two extra-wide-lane (EWL) combinations are fixed first, and then a wide lane (WL) combination is reformed based on the two EWL combinations for positioning. Theoretical analysis and empirical analysis is given of the ambiguity fixing rate and the positioning accuracy of the presented method. The results indicate that the ambiguity fixing rate can be up to more than 98% when using BDS medium baseline observations, which is much higher than that of dual-frequency Hatch-Melbourne-Wübbena (HMW) method. As for positioning accuracy, decimeter level accuracy can be achieved with this method, which is comparable to that of carrier-smoothed code differential positioning method. Signal interruption simulation experiment indicates that the proposed method can realize fast high-precision positioning whereas the carrier-smoothed code differential positioning method needs several hundreds of seconds for obtaining high precision results. We can conclude that a relatively high accuracy and high fixing rate can be achieved for triple-frequency WL method with single-epoch observations, displaying significant advantage comparing to traditional carrier-smoothed code differential positioning method. PMID:26703614

  1. Signal transduction pathways in erythrocyte nitric oxide metabolism under high fibrinogen levels

    NASA Astrophysics Data System (ADS)

    Saldanha, Carlota; Freitas, T.; Lopez de Almeida, J. P.; Silva-Herdade, A.

    2014-05-01

    Previous studies show that the fibrinogen molecule modulates the metabolism of nitric oxide (NO) in erythrocyte. The in vitro induced hiperfibrinogenemia interferes in the metabolism of the NO in the erythrocyte in dependence of the phosphorylation degree of the band 3. The soluble form of fibrinogen binds into CD47 protein present in the erythrocyte membrane. The soluble thrombomodulin is an inflammatory marker that binds to the erythrocyte CD47 in a site with a sequence peptide known as 4N1K. A study done in vitro shows that when hiperfibrinogenemia was induced in the presence of the peptide 4N1K agonist of CD47 it were observed variations in the efflux of NO from erythrocyte and an increase in the concentrations of GSNO, peroxinitrite, nitrite and nitrate of the erythrocytes. The aim of this work was to study the influence of the peptide 4N1K, on the metabolism of NO in the erythrocyte under high fibrinogen concentration and in the presence of inhibitors of the status of phosphorylation of protein band 3. In this in vitro study, whole blood samples were harvested from healthy subjects and NO, peroxynitrite, nitrite, nitrate and S-nitro-glutathione (GSNO) were determined in presence of 4N1K, calpeptine, Syk inhibitor and under high fibrinogen concentrations. The results obtained in erythrocytes under high fibrinogen levels when 4N1K is present with the Syk inhibitor or with calpeptine, showed in relation to the control samples increased significant concentrations of efflux of NO and of peroxynitrite, nitrite, nitrate and GSNO. In conclusion it was verified that in the in vitro model of hiperfibrinogenemia the peptide 4N1K, agonist of CD47, induces mobilization of NO in the erythrocyte in dependence of the status of phosphorylation of protein band 3.

  2. Canonical Wnt Pathway Signaling Suppresses VCAM-1 Expression by Marrow Stromal and Hematopoietic Cells

    PubMed Central

    Malhotra, Sachin; Kincade, Paul W.

    2009-01-01

    Objective The Wnt family may contribute to hematopoietic stem cell (HSC) maintenance in bone marrow, but many questions remain concerning mechanisms. Vascular cell adhesion molecule-1 (VCAM-1) is expressed in cellular compartments of the bone marrow and might contribute to the HSC niche, but mechanisms concerning its constitutive expression are largely unknown. We now explore the influence of Wnt signaling on cellular adhesion molecule (CAM) expression by bone marrow stromal and hematopoietic cells. Methods Recombinant Wnt ligands, retroviral Wnt transductions and co-cultures with Wnt secreting cells were used to analyze the effect of Wnt on adhesion molecule expression by stromal and hematopoietic cells. In vivo experiments were also done to assess the ability of Wnt3a induced, VCAM-1 deficient hematopoietic cells to engraft bone marrow. Results We now report that the beta-catenin dependent canonical Wnt signaling pathway negatively regulates VCAM-1 expression on two types of bone marrow cells. Wnt pathway inhibitors, Axin (intracellular) or Dkk1 (extracellular) blocked the regulation of VCAM-1 by diffusible Wnt3a. Interestingly, lipopolysaccharide (LPS) restored a substantial degree of VCAM-1 expression, suggesting functional cross-talk between Wnt and TLR4 signaling pathways. Decreasing VCAM-1 on HSC enriched Lin- Sca-1+ c-KitHi Thy1.1Lo cells by exposure to Wnt3a did not prevent their successful transplantation. Conclusions Our results suggest that cells comprising and residing in the HSC niche can respond to Wnt ligands and extinguish VCAM-1. This response may be important for export of hematopoietic cells. Given the known contribution of VCAM-1 to inflammation, this may represent a new avenue for therapeutic intervention. PMID:18951693

  3. TAK-1/p38/nNFκB signaling inhibits myoblast differentiation by increasing levels of Activin A

    PubMed Central

    2012-01-01

    Background Skeletal-muscle differentiation is required for the regeneration of myofibers after injury. The differentiation capacity of satellite cells is impaired in settings of old age, which is at least one factor in the onset of sarcopenia, the age-related loss of skeletal-muscle mass and major cause of frailty. One important cause of impaired regeneration is increased levels of transforming growth factor (TGF)-β accompanied by reduced Notch signaling. Pro-inflammatory cytokines are also upregulated in aging, which led us hypothesize that they might potentially contribute to impaired regeneration in sarcopenia. Thus, in this study, we further analyzed the muscle differentiation-inhibition pathway mediated by pro-inflammatory cytokines in human skeletal muscle cells (HuSKMCs). Methods We studied the modulation of HuSKMC differentiation by the pro-inflammatory cytokines interleukin (IL)-1α and tumor necrosis factor (TNF)-α The grade of differentiation was determined by either imaging (fusion index) or creatine kinase (CK) activity, a marker of muscle differentiation. Secretion of TGF-β proteins during differentiation was assessed by using a TGF-β-responsive reporter-gene assay and further identified by means of pharmacological and genetic inhibitors. In addition, signaling events were monitored by western blotting and reverse transcription PCR, both in HuSKMC cultures and in samples from a rat sarcopenia study. Results The pro-inflammatory cytokines IL-1α and TNF-α block differentiation of human myoblasts into myotubes. This anti-differentiation effect requires activation of TGF-β-activated kinase (TAK)-1. Using pharmacological and genetic inhibitors, the TAK-1 pathway could be traced to p38 and NFκB. Surprisingly, the anti-differentiation effect of the cytokines required the transcriptional upregulation of Activin A, which in turn acted through its established signaling pathway: ActRII/ALK/SMAD. Inhibition of Activin A signaling was able to rescue human

  4. Beta-Catenin Haplo Insufficient Male Mice Do Not Lose Bone in Response to Hindlimb Unloading.

    PubMed

    Maurel, Delphine B; Duan, Peipei; Farr, Joshua; Cheng, An-Lin; Johnson, Mark L; Bonewald, Lynda F

    2016-01-01

    As the β-catenin pathway has been shown to be involved in mechanotransduction, we sought to determine if haploinsufficiency would affect skeletal response to unloading. It has previously been shown that deletion of both alleles of β-catenin in bone cells results in a fragile skeleton highly susceptible to fracture, but deletion of one allele using Dmp1-Cre (Ctnnb1+/loxP; Dmp1-Cre, cKO HET) has little effect on the 2 mo old skeleton. We found that under normal housing conditions, trabecular bone volume was significantly less in 5 mo old male cKO HET mice compared to controls (Ctrl/HET:Tb. BV/TV = 13.96±2.71/8.92±0.95%, Tb.N. = 4.88±0.51/3.95±0.44/mm, Tb. Sp. = 0.20±0.02/0.26±0.03mm, a 36%, 19% and 30% change respectively) but not in females suggesting an age and gender related effect. Before performing suspension experiments and to control for the environmental effects, animals with the same tail attachment and housing conditions, but not suspended (NS), were compared to normally housed (NH) animals. Attachment and housing resulted in weight loss in both genders and phenotypes. Cortical bone loss was observed in the cKO HET males (NH/NS, Ct BV/TV: 90.45±0.72/89.12±0.56%) and both diaphyseal (0.19±0.01/0.17±0.01mm) and metaphyseal (0.10±0.01/0.08±0.01mm) thickness, but not in female cKO HET mice suggesting that male cKO HET mice are susceptible to attachment and housing conditions. These results with transgenic mice emphasizes the importance of proper controls when attributing skeletal responses to unloading. With suspension, cKO HET male mice did not lose bone unlike female cKO HET mice that had greater trabecular bone loss than controls (Ctrl 9%:cKO HET 21% decrease Tb. N; Ctrl 12%:cKO HET 27% increase Tb. Sp.). Suspended and non-suspended mice lost weight compared to normally housed animals. Taken together, the data suggest a protective effect of β-catenin against the effects of stress in males and partial protection against unloading in females. PMID:27410430

  5. Novel Cancer Chemotherapy Hits by Molecular Topology: Dual Akt and Beta-Catenin Inhibitors

    PubMed Central

    Morell, Cecilia; Rodríguez-Henche, Nieves; Recio-Iglesias, Maria Carmen; Garcia-Domenech, Ramon

    2015-01-01

    Background and Purpose Colorectal and prostate cancers are two of the most common types and cause of a high rate of deaths worldwide. Therefore, any strategy to stop or at least slacken the development and progression of malignant cells is an important therapeutic choice. The aim of the present work is the identification of novel cancer chemotherapy agents. Nowadays, many different drug discovery approaches are available, but this paper focuses on Molecular Topology, which has already demonstrated its extraordinary efficacy in this field, particularly in the identification of new hit and lead compounds against cancer. This methodology uses the graph theoretical formalism to numerically characterize molecular structures through the so called topological indices. Once obtained a specific framework, it allows the construction of complex mathematical models that can be used to predict physical, chemical or biological properties of compounds. In addition, Molecular Topology is highly efficient in selecting and designing new hit and lead drugs. According to the aforementioned, Molecular Topology has been applied here for the construction of specific Akt/mTOR and β-catenin inhibition mathematical models in order to identify and select novel antitumor agents. Experimental Approach Based on the results obtained by the selected mathematical models, six novel potential inhibitors of the Akt/mTOR and β-catenin pathways were identified. These compounds were then tested in vitro to confirm their biological activity. Conclusion and Implications Five of the selected compounds, CAS n° 256378-54-8 (Inhibitor n°1), 663203-38-1 (Inhibitor n°2), 247079-73-8 (Inhibitor n°3), 689769-86-6 (Inhibitor n°4) and 431925-096 (Inhibitor n°6) gave positive responses and resulted to be active for Akt/mTOR and/or β-catenin inhibition. This study confirms once again the Molecular Topology’s reliability and efficacy to find out novel drugs in the field of cancer. PMID:25910265

  6. Chronic alcohol consumption promotes hepatocarcinogenesis in mice through activation of beta-catenin.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alcohol abuse is the most common cause of liver cancer in the United States, Although alcohol effects within the liver have been extensively studied, the mechanism by which alcohol causes liver cancer is complex. One mechanism involves speeding up tumor growth (promotion) by increasing the number of...

  7. Chronic alcohol consumption promotes hepatocarcinogenesis in mice through activation of beta-catenin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alcohol abuse is the most common cause of liver cancer in the United States, Although alcohol effects within the liver have been extensively studied, the mechanism by which alcohol causes liver cancer is complex. One mechanism involves speeding up tumor growth (promotion) by increasing the number of...

  8. Beta-Catenin Haplo Insufficient Male Mice Do Not Lose Bone in Response to Hindlimb Unloading

    PubMed Central

    Farr, Joshua; Cheng, An-Lin; Johnson, Mark L.; Bonewald, Lynda F.

    2016-01-01

    As the β-catenin pathway has been shown to be involved in mechanotransduction, we sought to determine if haploinsufficiency would affect skeletal response to unloading. It has previously been shown that deletion of both alleles of β-catenin in bone cells results in a fragile skeleton highly susceptible to fracture, but deletion of one allele using Dmp1-Cre (Ctnnb1+/loxP; Dmp1-Cre, cKO HET) has little effect on the 2 mo old skeleton. We found that under normal housing conditions, trabecular bone volume was significantly less in 5 mo old male cKO HET mice compared to controls (Ctrl/HET:Tb. BV/TV = 13.96±2.71/8.92±0.95%, Tb.N. = 4.88±0.51/3.95±0.44/mm, Tb. Sp. = 0.20±0.02/0.26±0.03mm, a 36%, 19% and 30% change respectively) but not in females suggesting an age and gender related effect. Before performing suspension experiments and to control for the environmental effects, animals with the same tail attachment and housing conditions, but not suspended (NS), were compared to normally housed (NH) animals. Attachment and housing resulted in weight loss in both genders and phenotypes. Cortical bone loss was observed in the cKO HET males (NH/NS, Ct BV/TV: 90.45±0.72/89.12±0.56%) and both diaphyseal (0.19±0.01/0.17±0.01mm) and metaphyseal (0.10±0.01/0.08±0.01mm) thickness, but not in female cKO HET mice suggesting that male cKO HET mice are susceptible to attachment and housing conditions. These results with transgenic mice emphasizes the importance of proper controls when attributing skeletal responses to unloading. With suspension, cKO HET male mice did not lose bone unlike female cKO HET mice that had greater trabecular bone loss than controls (Ctrl 9%:cKO HET 21% decrease Tb. N; Ctrl 12%:cKO HET 27% increase Tb. Sp.). Suspended and non-suspended mice lost weight compared to normally housed animals. Taken together, the data suggest a protective effect of β-catenin against the effects of stress in males and partial protection against unloading in females. PMID:27410430

  9. A Nascent Peptide Signal Responsive to Endogenous Levels of Polyamines Acts to Stimulate Regulatory Frameshifting on Antizyme mRNA*

    PubMed Central

    Yordanova, Martina M.; Wu, Cheng; Andreev, Dmitry E.; Sachs, Matthew S.; Atkins, John F.

    2015-01-01

    The protein antizyme is a negative regulator of cellular polyamine concentrations from yeast to mammals. Synthesis of functional antizyme requires programmed +1 ribosomal frameshifting at the 3′ end of the first of two partially overlapping ORFs. The frameshift is the sensor and effector in an autoregulatory circuit. Except for Saccharomyces cerevisiae antizyme mRNA, the frameshift site alone only supports low levels of frameshifting. The high levels usually observed depend on the presence of cis-acting stimulatory elements located 5′ and 3′ of the frameshift site. Antizyme genes from different evolutionary branches have evolved different stimulatory elements. Prior and new multiple alignments of fungal antizyme mRNA sequences from the Agaricomycetes class of Basidiomycota show a distinct pattern of conservation 5′ of the frameshift site consistent with a function at the amino acid level. As shown here when tested in Schizosaccharomyces pombe and mammalian HEK293T cells, the 5′ part of this conserved sequence acts at the nascent peptide level to stimulate the frameshifting, without involving stalling detectable by toe-printing. However, the peptide is only part of the signal. The 3′ part of the stimulator functions largely independently and acts at least mostly at the nucleotide level. When polyamine levels were varied, the stimulatory effect was seen to be especially responsive in the endogenous polyamine concentration range, and this effect may be more general. A conserved RNA secondary structure 3′ of the frameshift site has weaker stimulatory and polyamine sensitizing effects on frameshifting. PMID:25998126

  10. Cre-mediated stress affects sirtuin expression levels, peroxisome biogenesis and metabolism, antioxidant and proinflammatory signaling pathways.

    PubMed

    Xiao, Yu; Karnati, Srikanth; Qian, Guofeng; Nenicu, Anca; Fan, Wei; Tchatalbachev, Svetlin; Höland, Anita; Hossain, Hamid; Guillou, Florian; Lüers, Georg H; Baumgart-Vogt, Eveline

    2012-01-01

    Cre-mediated excision of loxP sites is widely used in mice to manipulate gene function in a tissue-specific manner. To analyze phenotypic alterations related to Cre-expression, we have used AMH-Cre-transgenic mice as a model system. Different Cre expression levels were obtained by investigation of C57BL/6J wild type as well as heterozygous and homozygous AMH-Cre-mice. Our results indicate that Cre-expression itself in Sertoli cells already has led to oxidative stress and lipid peroxidation (4-HNE lysine adducts), inducing PPARα/γ, peroxisome proliferation and alterations of peroxisome biogenesis (PEX5, PEX13 and PEX14) as well as metabolic proteins (ABCD1, ABCD3, MFP1, thiolase B, catalase). In addition to the strong catalase increase, a NRF2- and FOXO3-mediated antioxidative response (HMOX1 of the endoplasmic reticulum and mitochondrial SOD2) and a NF-κB activation were noted. TGFβ1 and proinflammatory cytokines like IL1, IL6 and TNFα were upregulated and stress-related signaling pathways were induced. Sertoli cell mRNA-microarray analysis revealed an increase of TNFR2-signaling components. 53BP1 recruitment and expression levels for DNA repair genes as well as for p53 were elevated and the ones for related sirtuin deacetylases affected (SIRT 1, 3-7) in Sertoli cells. Under chronic Cre-mediated DNA damage conditions a strong downregulation of Sirt1 was observed, suggesting that the decrease of this important coordinator between DNA repair and metabolic signaling might induce the repression release of major transcription factors regulating metabolic and cytokine-mediated stress pathways. Indeed, caspase-3 was activated and increased germ cell apoptosis was observed, suggesting paracrine effects. In conclusion, the observed wide stress-induced effects and metabolic alterations suggest that it is essential to use the correct control animals (Cre/Wt) with matched Cre expression levels to differentiate between Cre-mediated and specific gene-knock out

  11. Altered mTOR signaling and enhanced CYFIP2 expression levels in subjects with fragile X syndrome.

    PubMed

    Hoeffer, C A; Sanchez, E; Hagerman, R J; Mu, Y; Nguyen, D V; Wong, H; Whelan, A M; Zukin, R S; Klann, E; Tassone, F

    2012-04-01

    Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and autism. The protein (FMRP) encoded by the fragile X mental retardation gene (FMR1), is an RNA-binding protein linked to translational control. Recently, in the Fmr1 knockout mouse model of FXS, dysregulated translation initiation signaling was observed. To investigate whether an altered signaling was also a feature of subjects with FXS compared to typical developing controls, we isolated total RNA and translational control proteins from lymphocytes of subjects from both groups (38 FXS and 14 TD). Although we did not observe any difference in the expression level of messenger RNAs (mRNAs) for translational initiation control proteins isolated from participant with FXS, we found increased phosphorylation of the mammalian target of rapamycin (mTOR) substrate, p70 ribosomal subunit 6 kinase1 (S6K1) and of the mTOR regulator, the serine/threonine protein kinase (Akt), in their protein lysates. In addition, we observed increased phosphorylation of the cap binding protein eukaryotic initiation factor 4E (eIF4E) suggesting that protein synthesis is upregulated in FXS. Similar to the findings in lymphocytes, we observed increased phosphorylation of S6K1 in brain tissue from patients with FXS (n = 4) compared to normal age-matched controls (n = 4). Finally, we detected increased expression of the cytoplasmic FMR1-interacting protein 2 (CYFIP2), a known FMRP interactor. This data verify and extend previous findings using lymphocytes for studies of neuropsychiatric disorders and provide evidence that misregulation of mTOR signaling observed in the FXS mouse model also occurs in human FXS and may provide useful biomarkers for designing targeted treatments in FXS.

  12. The tumor suppressor p53 fine-tunes reactive oxygen species levels and neurogenesis via PI3 kinase signaling.

    PubMed

    Forsberg, Kirsi; Wuttke, Anja; Quadrato, Giorgia; Chumakov, Peter M; Wizenmann, Andrea; Di Giovanni, Simone

    2013-09-01

    Mounting evidence points to a role for endogenous reactive oxygen species (ROS) in cell signaling, including in the control of cell proliferation, differentiation, and fate. However, the function of ROS and their molecular regulation in embryonic mouse neural progenitor cells (eNPCs) has not yet been clarified. Here, we describe that physiological ROS are required for appropriate timing of neurogenesis in the developing telencephalon in vivo and in cultured NPCs, and that the tumor suppressor p53 plays a key role in the regulation of ROS-dependent neurogenesis. p53 loss of function leads to elevated ROS and early neurogenesis, while restoration of p53 and antioxidant treatment partially reverse the phenotype associated with premature neurogenesis. Furthermore, we describe that the expression of a number of neurogenic and oxidative stress genes relies on p53 and that both p53 and ROS-dependent induction of neurogenesis depend on PI3 kinase/phospho-Akt signaling. Our results suggest that p53 fine-tunes endogenous ROS levels to ensure the appropriate timing of neurogenesis in eNPCs. This may also have implications for the generation of tumors of neurodevelopmental origin.

  13. Use of the discriminant Fourier-derived cepstrum with feature-level post-processing for surface electromyographic signal classification.

    PubMed

    Chen, Xinpu; Zhu, Xiangyang; Zhang, Dingguo

    2009-12-01

    Myoelectrical pattern classification is a crucial part in multi-functional prosthesis control. This paper investigates a discriminant Fourier-derived cepstrum (DFC) and feature-level post-processing (FLPP) to discriminate hand and wrist motions using the surface electromyographic signal. The Fourier-derived cepstrum takes advantage of the Fourier magnitude or sub-band power energy of signals directly and provides flexible use of spectral information changing with different motions. Appropriate cepstral coefficients are selected by a proposed separability criterion to construct DFC features. For the post-processing, FLPP which combines features from several analysis windows is used to improve the feature performance further. In this work, two classifiers (a linear discriminant classifier and quadratic discriminant classifier) without hyper-parameter optimization are employed to simplify the training procedure and avoid the possible bias of feature evaluation. Experimental results of the 11-motion problem show that the proposed DFC feature outperforms traditional features such as time-domain statistics and autoregressive-derived cepstrum in terms of the classification accuracy, and it is a promising method for the multi-functionality and high-accuracy control of myoelectric prostheses.

  14. Cortical depth-specific microvascular dilation underlies laminar differences in blood oxygenation level-dependent functional MRI signal

    PubMed Central

    Tian, Peifang; Teng, Ivan C.; May, Larry D.; Kurz, Ronald; Lu, Kun; Scadeng, Miriam; Hillman, Elizabeth M. C.; De Crespigny, Alex J.; D’Arceuil, Helen E.; Mandeville, Joseph B.; Marota, John J. A.; Rosen, Bruce R.; Liu, Thomas T.; Boas, David A.; Buxton, Richard B.; Dale, Anders M.; Devor, Anna

    2010-01-01

    Changes in neuronal activity are accompanied by the release of vasoactive mediators that cause microscopic dilation and constriction of the cerebral microvasculature and are manifested in macroscopic blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals. We used two-photon microscopy to measure the diameters of single arterioles and capillaries at different depths within the rat primary somatosensory cortex. These measurements were compared with cortical depth-resolved fMRI signal changes. Our microscopic results demonstrate a spatial gradient of dilation onset and peak times consistent with “upstream” propagation of vasodilation toward the cortical surface along the diving arterioles and “downstream” propagation into local capillary beds. The observed BOLD response exhibited the fastest onset in deep layers, and the “initial dip” was most pronounced in layer I. The present results indicate that both the onset of the BOLD response and the initial dip depend on cortical depth and can be explained, at least in part, by the spatial gradient of delays in microvascular dilation, the fastest response being in the deep layers and the most delayed response in the capillary bed of layer I. PMID:20696904

  15. Cortical depth-specific microvascular dilation underlies laminar differences in blood oxygenation level-dependent functional MRI signal.

    PubMed

    Tian, Peifang; Teng, Ivan C; May, Larry D; Kurz, Ronald; Lu, Kun; Scadeng, Miriam; Hillman, Elizabeth M C; De Crespigny, Alex J; D'Arceuil, Helen E; Mandeville, Joseph B; Marota, John J A; Rosen, Bruce R; Liu, Thomas T; Boas, David A; Buxton, Richard B; Dale, Anders M; Devor, Anna

    2010-08-24

    Changes in neuronal activity are accompanied by the release of vasoactive mediators that cause microscopic dilation and constriction of the cerebral microvasculature and are manifested in macroscopic blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals. We used two-photon microscopy to measure the diameters of single arterioles and capillaries at different depths within the rat primary somatosensory cortex. These measurements were compared with cortical depth-resolved fMRI signal changes. Our microscopic results demonstrate a spatial gradient of dilation onset and peak times consistent with "upstream" propagation of vasodilation toward the cortical surface along the diving arterioles and "downstream" propagation into local capillary beds. The observed BOLD response exhibited the fastest onset in deep layers, and the "initial dip" was most pronounced in layer I. The present results indicate that both the onset of the BOLD response and the initial dip depend on cortical depth and can be explained, at least in part, by the spatial gradient of delays in microvascular dilation, the fastest response being in the deep layers and the most delayed response in the capillary bed of layer I.

  16. Decreased peroxisome proliferator-activated receptor γ level and signalling in sebaceous glands of patients with acne vulgaris.

    PubMed

    Dozsa, A; Mihaly, J; Dezso, B; Csizmadia, E; Keresztessy, T; Marko, L; Rühl, R; Remenyik, E; Nagy, L

    2016-07-01

    Little is known about the altered lipid metabolism-related transcriptional events occuring in sebaceous glands of patients with acne vulgaris. Peroxisome proliferator-activated receptor (PPAR)γ, a lipid-activated transcription factor, is implicated in differentiation and lipid metabolism of sebocytes. We have observed that PPARγ and its target genes, ADRP (adipose differentiation related protein) and PGAR (PPARγ angioprotein related protein) are expressed at lower levels in sebocytes from patients with acne than in those from healthy controls (HCs) Furthermore, endogenous PPARγ activator lipids such as arachidonic acid-derived keto-metabolites (e.g. 5KETE, 12KETE) are increased in acne-involved and nonacne-involved skin of patients with acne, compared with skin from healthy individuals. Our findings highlight the possible anti-inflammatory role of endogenous ligand-activated PPARγ signaling in human sebocyte biology, and suggest that modulating PPARγ- expression and thereby signaling might be a promising strategy for the clinical management of acne vulgaris.

  17. 4-(1-Ethyl-4-anisyl-imidazol-5-yl)-N-hydroxycinnamide - A new pleiotropic HDAC inhibitor targeting cancer cell signalling and cytoskeletal organisation.

    PubMed

    Mahal, Katharina; Kahlen, Philip; Biersack, Bernhard; Schobert, Rainer

    2015-08-15

    Histone deacetylases (HDAC) which play a crucial role in cancer cell proliferation are promising drug targets. However, HDAC inhibitors (HDACi) modelled on natural hydroxamic acids such as trichostatin A frequently lead to resistance or even an increased agressiveness of tumours. As a workaround we developed 4-(1-ethyl-4-anisyl-imidazol-5-yl)-N-hydroxycinnamide (etacrox), a hydroxamic acid that combines HDAC inhibition with synergistic effects of the 4,5-diarylimidazole residue. Etacrox proved highly cytotoxic against a panel of metastatic and resistant cancer cell lines while showing greater specificity for cancer over non-malignant cells when compared to the approved HDACi vorinostat. Like the latter, etacrox and the closely related imidazoles bimacroxam and animacroxam acted as pan-HDACi yet showed some specificity for HDAC6. Akt signalling and interference with nuclear beta-catenin localisation were elicited by etacrox at lower concentrations when compared to vorinostat. Moreover, etacrox disrupted the microtubule and focal adhesion dynamics of cancer cells and inhibited the proteolytic activity of prometastatic and proangiogenic matrix metalloproteinases. As a consequence, etacrox acted strongly antimigratory and antiinvasive against various cancer cell lines in three-dimensional transwell invasion assays and also antiangiogenic in vivo with respect to blood vessel formation in the chorioallantoic membrane assay. These pleiotropic effects and its water-solubility and tolerance by mice render etacrox a promising new HDACi candidate. PMID:26101158

  18. Development of a novel pixel-level signal processing chain for fast readout 3D integrated CMOS pixel sensors

    NASA Astrophysics Data System (ADS)

    Fu, Y.; Torheim, O.; Hu-Guo, C.; Degerli, Y.; Hu, Y.

    2013-03-01

    In order to resolve the inherent readout speed limitation of traditional 2D CMOS pixel sensors, operated in rolling shutter readout, a parallel readout architecture has been developed by taking advantage of 3D integration technologies. Since the rows of the pixel array are zero-suppressed simultaneously instead of sequentially, a frame readout time of a few microseconds is expected for coping with high hit rates foreseen in future collider experiments. In order to demonstrate the pixel readout functionality of such a pixel sensor, a 2D proof-of-concept chip including a novel pixel-level signal processing chain was designed and fabricated in a 0.13 μm CMOS technology. The functionalities of this chip have been verified through experimental characterization.

  19. Application of linear graph embedding as a dimensionality reduction technique and sparse representation classifier as a post classifier for the classification of epilepsy risk levels from EEG signals

    NASA Astrophysics Data System (ADS)

    Prabhakar, Sunil Kumar; Rajaguru, Harikumar

    2015-12-01

    The most common and frequently occurring neurological disorder is epilepsy and the main method useful for the diagnosis of epilepsy is electroencephalogram (EEG) signal analysis. Due to the length of EEG recordings, EEG signal analysis method is quite time-consuming when it is processed manually by an expert. This paper proposes the application of Linear Graph Embedding (LGE) concept as a dimensionality reduction technique for processing the epileptic encephalographic signals and then it is classified using Sparse Representation Classifiers (SRC). SRC is used to analyze the classification of epilepsy risk levels from EEG signals and the parameters such as Sensitivity, Specificity, Time Delay, Quality Value, Performance Index and Accuracy are analyzed.

  20. Sea level estimate from multi-frequency signal-to-noise ratio data collected by a single geodetic receiver

    NASA Astrophysics Data System (ADS)

    Roussel, Nicolas; Frappart, Frédéric; Ramillien, Guillaume; Darrozes, José; Cornu, Gwendolyne; Koummarasy, Khanithalath

    2016-04-01

    GNSS-Reflectometry (GNSS-R) altimetry has demonstrated a strong potential for sea level monitoring. Interference Pattern Technique (IPT) based on the analysis of the Signal-to-Noise Ratio (SNR) estimated by a GNSS receiver, presents the main advantage of being applicable everywhere by using a single geodetic antenna and receiver, transforming them to real tide gauges. Such a technique has already been tested in various configurations of acquisition of surface-reflected GNSS signals with an accuracy of a few centimeters. Nevertheless, the classical SNR analysis method for estimating the reflecting surface-antenna height is limited by an approximation: the vertical velocity of the reflecting surface must be negligible. Authors present a significant improvement of the SNR technique to solve this problem and broaden the scope of SNR-based tide monitoring. The performances achieved on the different GNSS frequency band (L1, L2 and L5) are analyzed. The method is based on a Least-Mean Square Resolution Method (LSM), combining simultaneous measurements from different GNSS constellations (GPS, GLONASS), which permits to take the dynamic of the surface into account. It was validated in situ [1], with an antenna placed at 60 meters above the Atlantic Ocean surface with variations reaching ±3 meters, and amplitude rate of the semi-diurnal tide up to 0.5 mm/s. Over the three months of SNR records on L1 frequency band for sea level determination, we found linear correlations of 0.94 by comparing with a classical tide gauge record. Our SNR-based time series was also compared to a tide theoretical model and amplitudes and phases of the main astronomical periods (6-, 12- and 24-h) were perfectly well detected. Waves and swell are also likely to be detected. If the validity of our method is already well-established with L1 band [1], the aim of our current study is to analyze the results obtained with the other GNSS frequency band: L2 and L5. L1 band seems to provide the best sea

  1. Effect of artemisinins and other endoperoxides on nitric oxide-related signaling pathway in RAW 264.7 mouse macrophage cells.

    PubMed

    Konkimalla, V Badireenath; Blunder, Martina; Korn, Bernhard; Soomro, Shahid A; Jansen, Herwig; Chang, Wonsuk; Posner, Gary H; Bauer, Rudolf; Efferth, Thomas

    2008-09-01

    Artemisinin is the active principle of the Chinese herb Artemisia annua L. In addition to its anti-malarial activity, artemisinin and its derivatives have been shown to exert profound anti-cancer activity. The endoperoxide moiety in the chemical structure of artemisinin is thought to be responsible for the bioactivity. Here, we analyzed the cytotoxicity and the ability of artemisinin, five of its derivatives, and two other endoperoxides to inhibit generation of nitric oxide (NO). In the RAW 264.7 mouse macrophage cell line, the well-established model cell line to analyze NO generation, artesunate revealed the highest ability to inhibit NO production among all compounds tested. In cytotoxicity assays (XTT assay), the IC(50) value of RAW 264.7 cells for artesunate was determined to be 3.1+/-0.7 microM. In order to associate the cytotoxic effects with specific alteration in gene expression related to NO metabolism and signaling, whole genome mRNA microarray analyses were conducted. RAW 264.7 cells were treated with artesunate using DMSO as vehicle control followed by microarray analysis. A total of 36 genes related to NO metabolism and signaling were found to be differentially expressed upon exposure to artesunate. Apart from NO-related genes, the expression of genes associated with other functional groups was also analyzed. Out of 24 functional groups, differential expression was most prominent in genes involved in cell-to-cell signaling and interactions. Further refinement of this analysis showed that the pathways for cAMP-mediated signaling and Wnt/beta-catenin signaling were most closely related to changes in mRNA expression. In conclusion, NO generation and signaling play a role in exhibiting cytotoxic activity of artesunate. In addition, other signaling pathways also contribute to the inhibitory effect of artesunate towards RAW 264.7 cells pointing to a multi-factorial mode of action of artesunate. PMID:18472018

  2. Resolution of Conflicting Signals at the Single-Cell Level in the Regulation of Cyanobacterial Photosynthesis and Nitrogen Fixation

    PubMed Central

    Mohr, Wiebke; Vagner, Tomas; Kuypers, Marcel M. M.; Ackermann, Martin; LaRoche, Julie

    2013-01-01

    Unicellular, diazotrophic cyanobacteria temporally separate dinitrogen (N2) fixation and photosynthesis to prevent inactivation of the nitrogenase by oxygen. This temporal segregation is regulated by a circadian clock with oscillating activities of N2 fixation in the dark and photosynthesis in the light. On the population level, this separation is not always complete, since the two processes can overlap during transitions from dark to light. How do single cells avoid inactivation of nitrogenase during these periods? One possibility is that phenotypic heterogeneity in populations leads to segregation of the two processes. Here, we measured N2 fixation and photosynthesis of individual cells using nanometer-scale secondary ion mass spectrometry (nanoSIMS) to assess both processes in a culture of the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii during a dark-light and a continuous light phase. We compared single-cell rates with bulk rates and gene expression profiles. During the regular dark and light phases, C. watsonii exhibited the temporal segregation of N2 fixation and photosynthesis commonly observed. However, N2 fixation and photosynthesis were concurrently measurable at the population level during the subjective dark phase in which cells were kept in the light rather than returned to the expected dark phase. At the single-cell level, though, cells discriminated against either one of the two processes. Cells that showed high levels of photosynthesis had low nitrogen fixing activities, and vice versa. These results suggest that, under ambiguous environmental signals, single cells discriminate against either photosynthesis or nitrogen fixation, and thereby might reduce costs associated with running incompatible processes in the same cell. PMID:23805199

  3. Comparative genomics of the vertebrate insulin/TOR signal transduction pathway: a network-level analysis of selective pressures.

    PubMed

    Alvarez-Ponce, David; Aguadé, Montserrat; Rozas, Julio

    2011-01-01

    Complexity of biological function relies on large networks of interacting molecules. However, the evolutionary properties of these networks are not fully understood. It has been shown that selective pressures depend on the position of genes in the network. We have previously shown that in the Drosophila insulin/target of rapamycin (TOR) signal transduction pathway there is a correlation between the pathway position and the strength of purifying selection, with the downstream genes being most constrained. In this study, we investigated the evolutionary dynamics of this well-characterized pathway in vertebrates. More specifically, we determined the impact of natural selection on the evolution of 72 genes of this pathway. We found that in vertebrates there is a similar gradient of selective constraint in the insulin/TOR pathway to that found in Drosophila. This feature is neither the result of a polarity in the impact of positive selection nor of a series of factors affecting selective constraint levels (gene expression level and breadth, codon bias, protein length, and connectivity). We also found that pathway genes encoding physically interacting proteins tend to evolve under similar selective constraints. The results indicate that the architecture of the vertebrate insulin/TOR pathway constrains the molecular evolution of its components. Therefore, the polarity detected in Drosophila is neither specific nor incidental of this genus. Hence, although the underlying biological mechanisms remain unclear, these may be similar in both vertebrates and Drosophila.

  4. Regulation of Smoothened Phosphorylation and High-Level Hedgehog Signaling Activity by a Plasma Membrane Associated Kinase.

    PubMed

    Li, Shuangxi; Li, Shuang; Han, Yuhong; Tong, Chao; Wang, Bing; Chen, Yongbin; Jiang, Jin

    2016-06-01

    Hedgehog (Hh) signaling controls embryonic development and adult tissue homeostasis through the G protein coupled receptor (GPCR)-family protein Smoothened (Smo). Upon stimulation, Smo accumulates on the cell surface in Drosophila or primary cilia in vertebrates, which is thought to be essential for its activation and function, but the underlying mechanisms remain poorly understood. Here we show that Hh stimulates the binding of Smo to a plasma membrane-associated kinase Gilgamesh (Gish)/CK1γ and that Gish fine-tunes Hh pathway activity by phosphorylating a Ser/Thr cluster (CL-II) in the juxtamembrane region of Smo carboxyl-terminal intracellular tail (C-tail). We find that CL-II phosphorylation is promoted by protein kinase A (PKA)-mediated phosphorylation of Smo C-tail and depends on cell surface localization of both Gish and Smo. Consistent with CL-II being critical for high-threshold Hh target gene expression, its phosphorylation appears to require higher levels of Hh or longer exposure to the same level of Hh than PKA-site phosphorylation on Smo. Furthermore, we find that vertebrate CK1γ is localized at the primary cilium to promote Smo phosphorylation and Sonic hedgehog (Shh) pathway activation. Our study reveals a conserved mechanism whereby Hh induces a change in Smo subcellular localization to promote its association with and activation by a plasma membrane localized kinase, and provides new insight into how Hh morphogen progressively activates Smo. PMID:27280464

  5. Regulation of Smoothened Phosphorylation and High-Level Hedgehog Signaling Activity by a Plasma Membrane Associated Kinase

    PubMed Central

    Tong, Chao; Wang, Bing; Chen, Yongbin; Jiang, Jin

    2016-01-01

    Hedgehog (Hh) signaling controls embryonic development and adult tissue homeostasis through the G protein coupled receptor (GPCR)-family protein Smoothened (Smo). Upon stimulation, Smo accumulates on the cell surface in Drosophila or primary cilia in vertebrates, which is thought to be essential for its activation and function, but the underlying mechanisms remain poorly understood. Here we show that Hh stimulates the binding of Smo to a plasma membrane-associated kinase Gilgamesh (Gish)/CK1γ and that Gish fine-tunes Hh pathway activity by phosphorylating a Ser/Thr cluster (CL-II) in the juxtamembrane region of Smo carboxyl-terminal intracellular tail (C-tail). We find that CL-II phosphorylation is promoted by protein kinase A (PKA)-mediated phosphorylation of Smo C-tail and depends on cell surface localization of both Gish and Smo. Consistent with CL-II being critical for high-threshold Hh target gene expression, its phosphorylation appears to require higher levels of Hh or longer exposure to the same level of Hh than PKA-site phosphorylation on Smo. Furthermore, we find that vertebrate CK1γ is localized at the primary cilium to promote Smo phosphorylation and Sonic hedgehog (Shh) pathway activation. Our study reveals a conserved mechanism whereby Hh induces a change in Smo subcellular localization to promote its association with and activation by a plasma membrane localized kinase, and provides new insight into how Hh morphogen progressively activates Smo. PMID:27280464

  6. Effects of Signal Level and Background Noise on Spectral Representations in the Auditory Nerve of the Domestic Cat

    PubMed Central

    Ramachandran, Ramnarayan; May, Bradford J.

    2010-01-01

    Background noise poses a significant obstacle for auditory perception, especially among individuals with hearing loss. To better understand the physiological basis of this perceptual impediment, the present study evaluated the effects of background noise on the auditory nerve representation of head-related transfer functions (HRTFs). These complex spectral shapes describe the directional filtering effects of the head and torso. When a broadband sound passes through the outer ear en route to the tympanic membrane, the HRTF alters its spectrum in a manner that establishes the perceived location of the sound source. HRTF-shaped noise shares many of the acoustic features of human speech, while communicating biologically relevant localization cues that are generalized across mammalian species. Previous studies have used parametric manipulations of random spectral shapes to elucidate HRTF coding principles at various stages of the cat’s auditory system. This study extended that body of work by examining the effects of sound level and background noise on the quality of spectral coding in the auditory nerve. When fibers were classified by their spontaneous rates, the coding properties of the more numerous low-threshold, high-spontaneous rate fibers were found to degrade at high presentation levels and in low signal-to-noise ratios. Because cats are known to maintain accurate directional hearing under these challenging listening conditions, behavioral performance may be disproportionally based on the enhanced dynamic range of the less common high-threshold, low-spontaneous rate fibers. PMID:20824483

  7. Hippocampal ProNGF Signaling Pathways and β-Amyloid Levels in Mild Cognitive Impairment and Alzheimer Disease

    PubMed Central

    Mufson, Elliott J.; He, Bin; Nadeem, Muhammad; Perez, Sylvia E.; Counts, Scott E.; Leurgans, Sue; Fritz, Jason; Lah, James; Ginsberg, Stephen D.; Wuu, Joanne; Scheff, Stephen W.

    2012-01-01

    Hippocampal precursor of nerve growth factor (proNGF)/NGF signaling occurs in conjunction with β-amyloid (Aβ) accumulations in Alzheimer disease (AD). To assess the involvement of this pathway in AD progression, we quantified these proteins and their downstream pathway activators in postmortem tissues from the brains of subjects with no cognitive impairment (NCI), mild cognitive impairment (MCI), and AD using immunoblotting and enzyme-linked immunosorbent assay (ELISA). Hippocampal proNGF was significantly greater in AD compared to NCI and MCI cases. TrkA was significantly reduced in MCI compared to NCI and AD, whereas p75NTR, sortilin, and neurotrophin receptor homolog-2 remained stable. Akt decreased from NCI to MCI to AD, whereas phospho-Akt and phosphor-Akt to Akt ratio were elevated in AD compared to MCI and NCI. No differences were found in phospho-Erk, Erk or their ratio across groups. c-jun kinase (JNK) remained stable across groups, while phospho-JNK and the phospho-JNK to JNK ratio increased significantly in AD compared to NCI and MCI. Expression levels of Aβ1-40, Aβ1-42 and Aβ40/42 ratio were stable. Statistical analysis revealed a strong positive correlation between proNGF and phospho-JNK, though only proNGF was negatively correlated with cognitive function and only TrkA was negatively associated with pathologic criteria. These findings suggest that alterations in the hippocampal NGF signaling pathway in MCI and AD favor proNGF-mediated pro-apoptotic pathways, and that this is independent of Aβ accumulation during AD progression. PMID:23095849

  8. Effects of Wnt3a on proliferation and differentiation of human epidermal stem cells

    SciTech Connect

    Jia Liwei; Zhou Jiaxi; Peng Sha; Li Juxue; Cao Yujing; Duan Enkui

    2008-04-11

    Epidermal stem cells maintain development and homeostasis of mammalian epidermis throughout life. However, the molecular mechanisms involved in the proliferation and differentiation of epidermal stem cells are far from clear. In this study, we investigated the effects of Wnt3a and Wnt/{beta}-catenin signaling on proliferation and differentiation of human fetal epidermal stem cells. We found both Wnt3a and active {beta}-catenin, two key members of the Wnt/{beta}-catenin signaling, were expressed in human fetal epidermis and epidermal stem cells. In addition, Wnt3a protein can promote proliferation and inhibit differentiation of epidermal stem cells in vitro culture. Our results suggest that Wnt/{beta}-catenin signaling plays important roles in human fetal skin development and homeostasis, which also provide new insights on the molecular mechanisms of oncogenesis in human epidermis.

  9. Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth

    PubMed Central

    Seibert, Anna-Maria; Koblitz, Jens C.; Denzinger, Annette; Schnitzler, Hans-Ulrich

    2015-01-01

    The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the “stealth” echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey. PMID:26352271

  10. Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth.

    PubMed

    Seibert, Anna-Maria; Koblitz, Jens C; Denzinger, Annette; Schnitzler, Hans-Ulrich

    2015-01-01

    The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the "stealth" echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey.

  11. Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth.

    PubMed

    Seibert, Anna-Maria; Koblitz, Jens C; Denzinger, Annette; Schnitzler, Hans-Ulrich

    2015-01-01

    The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the "stealth" echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey. PMID:26352271

  12. HDAC3 impacts multiple oncogenic pathways in colon cancer cells with effects on Wnt and vitamin D signaling.

    PubMed

    Godman, Cassandra A; Joshi, Rashmi; Tierney, Brendan R; Greenspan, Emily; Rasmussen, Theodore P; Wang, Hsin-Wei; Shin, Dong-Guk; Rosenberg, Daniel W; Giardina, Charles

    2008-10-01

    Histone deacetylase 3 (HDAC3) is overexpressed in approximately half of all colon adenocarcinomas. We took an RNAi approach to determine how HDAC3 influenced chromatin modifications and the expression of growth regulatory genes in colon cancer cells. A survey of histone modifications revealed that HDAC3 knockdown in SW480 cells significantly increased histone H4-K12 acetylation, a modification present during chromatin assembly that has been implicated in imprinting. This modification was found to be most prominent in proliferating cells in the intestinal crypt and in APC(Min) tumors, but was less pronounced in the tumors that overexpress HDAC3. Gene expression profiling of SW480 revealed that HDAC3 shRNA impacted the expression of genes in the Wnt and vitamin D signaling pathways. The impact of HDAC3 on Wnt signaling was complex, with both positive and negative effects observed. However, long-term knockdown of HDAC3 suppressed beta-catenin translocation from the plasma membrane to the nucleus, and increased expression of Wnt inhibitors TLE1, TLE4 and SMO. HDAC3 knockdown also enhanced expression of the TLE1 and TLE4 repressors in HT-29 and HCT116 cells. HDAC3 shRNA enhanced expression of the vitamin D receptor in SW480 and HCT116 cells, and rendered SW480 cells sensitive to 1,25-dihydroxyvitamin D3. We propose that HDAC3 overexpression alters the epigenetic programming of colon cancer cells to impact intracellular Wnt signaling and their sensitivity to external growth regulation by vitamin D.

  13. Glutathione levels discriminate between oxidative stress and transforming growth factor-beta signaling in activated rat hepatic stellate cells.

    PubMed

    De Bleser, P J; Xu, G; Rombouts, K; Rogiers, V; Geerts, A

    1999-11-26

    Reactive oxygen species are implicated in the pathogenesis of several diseases, including Alzheimer's disease, multiple sclerosis, human immunodeficiency virus, and liver fibrosis. With respect to liver fibrosis, we have investigated differences in antioxidant enzymes expression in stellate cells (SCs) and parenchymal cells from normal and CCl(4)-treated rat livers. We observed an increase in the expression of catalase in activated SCs. Treatment with transforming growth factor-beta (TGF-beta) increased the production of H(2)O(2). Treatment with catalase decreased TGF-beta expression. Addition of H(2)O(2) resulted in increased TGF-beta production. 3-Amino-1,2,4-triazole abolished the capacity of SCs to remove H(2)O(2). A paradoxical increase in capacity was observed when the cells were pretreated with diethyl maleate. Treatment with 3-amino-1, 2,4-triazole increased TGF-beta production. A paradoxical decrease of TGF-beta production was observed with diethyl maleate. Treatment of the cells with N-acetylcysteine resulted in increased TGF-beta production. TGF-beta decreased the capacity of the SCs to remove H(2)O(2.) An increase in the capacity to remove H(2)O(2) was observed when TGF-beta was removed by neutralizing antibodies. In conclusion, our results suggest: 1) a link between cellular GSH levels and TGF-beta production and 2) that cellular GSH levels discriminate whether H(2)O(2) is the result of oxidative stress or acts as second messenger in the TGF-beta signal transduction pathway.

  14. Evidence that Armadillo transduces wingless by mediating nuclear export or cytosolic activation of Pangolin.

    PubMed

    Chan, Siu-Kwong; Struhl, Gary

    2002-10-18

    Secreted proteins of the Wnt family have profound organizing roles during animal development and are transduced via the activities of the Frizzled (Fz) class of transmembrane receptors and the TCF/LEF/Pangolin class of transcription factors. beta-catenins, including Drosophila Armadillo (Arm), link activation of Fz at the cell surface to transcriptional regulation by TCF in the nucleus. The consensus view is that Wnt signaling induces beta-catenin to enter the nucleus and combine with TCF to form a transcription factor complex in which TCF binds DNA and the C-terminal domain of beta-catenin activates transcription. Here, we present findings, which challenge this view and suggest instead that beta-catenin may transduce Wnt signals by exporting TCF from the nucleus or activating it in the cytoplasm. PMID:12408870

  15. Evidence that Armadillo transduces wingless by mediating nuclear export or cytosolic activation of Pangolin.

    PubMed

    Chan, Siu-Kwong; Struhl, Gary

    2002-10-18

    Secreted proteins of the Wnt family have profound organizing roles during animal development and are transduced via the activities of the Frizzled (Fz) class of transmembrane receptors and the TCF/LEF/Pangolin class of transcription factors. beta-catenins, including Drosophila Armadillo (Arm), link activation of Fz at the cell surface to transcriptional regulation by TCF in the nucleus. The consensus view is that Wnt signaling induces beta-catenin to enter the nucleus and combine with TCF to form a transcription factor complex in which TCF binds DNA and the C-terminal domain of beta-catenin activates transcription. Here, we present findings, which challenge this view and suggest instead that beta-catenin may transduce Wnt signals by exporting TCF from the nucleus or activating it in the cytoplasm.

  16. LRP4 third β-propeller domain mutations cause novel congenital myasthenia by compromising agrin-mediated MuSK signaling in a position-specific manner.

    PubMed

    Ohkawara, Bisei; Cabrera-Serrano, Macarena; Nakata, Tomohiko; Milone, Margherita; Asai, Nobuyuki; Ito, Kenyu; Ito, Mikako; Masuda, Akio; Ito, Yasutomo; Engel, Andrew G; Ohno, Kinji

    2014-04-01

    Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. Using Sanger and exome sequencing in a CMS patient, we identified two heteroallelic mutations, p.Glu1233Lys and p.Arg1277His, in LRP4 coding for the postsynaptic low-density lipoprotein receptor-related protein 4. LRP4, expressed on the surface of the postsynaptic membrane of the neuromuscular junction, is a receptor for neurally secreted agrin, and LRP4 bound by agrin activates MuSK. Activated MuSK in concert with Dok-7 stimulates rapsyn to concentrate and anchor AChR on the postsynaptic membrane and interacts with other proteins implicated in the assembly and maintenance of the neuromuscular junction. LRP4 also functions as an inhibitor of Wnt/beta-catenin signaling. The identified mutations in LRP4 are located at the edge of its 3rd beta-propeller domain and decrease binding affinity of LRP4 for both MuSK and agrin. Mutations in the LRP4 3rd beta-propeller domain were previously reported to impair Wnt signaling and cause bone diseases including Cenani-Lenz syndactyly syndrome and sclerosteosis-2. By analyzing naturally occurring and artificially introduced mutations in the LRP4 3rd beta-propeller domain, we show that the edge of the domain regulates the MuSK signaling whereas its central cavity governs Wnt signaling. We conclude that LRP4 is a new CMS disease gene and that the 3rd beta propeller domain of LRP4 mediates the two signaling pathways in a position-specific manner.

  17. LRP4 third β-propeller domain mutations cause novel congenital myasthenia by compromising agrin-mediated MuSK signaling in a position-specific manner

    PubMed Central

    Ohkawara, Bisei; Cabrera-Serrano, Macarena; Nakata, Tomohiko; Milone, Margherita; Asai, Nobuyuki; Ito, Kenyu; Ito, Mikako; Masuda, Akio; Ito, Yasutomo; Engel, Andrew G.; Ohno, Kinji

    2014-01-01

    Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. Using Sanger and exome sequencing in a CMS patient, we identified two heteroallelic mutations, p.Glu1233Lys and p.Arg1277His, in LRP4 coding for the postsynaptic low-density lipoprotein receptor-related protein 4. LRP4, expressed on the surface of the postsynaptic membrane of the neuromuscular junction, is a receptor for neurally secreted agrin, and LRP4 bound by agrin activates MuSK. Activated MuSK in concert with Dok-7 stimulates rapsyn to concentrate and anchor AChR on the postsynaptic membrane and interacts with other proteins implicated in the assembly and maintenance of the neuromuscular junction. LRP4 also functions as an inhibitor of Wnt/beta-catenin signaling. The identified mutations in LRP4 are located at the edge of its 3rd beta-propeller domain and decrease binding affinity of LRP4 for both MuSK and agrin. Mutations in the LRP4 3rd beta-propeller domain were previously reported to impair Wnt signaling and cause bone diseases including Cenani–Lenz syndactyly syndrome and sclerosteosis-2. By analyzing naturally occurring and artificially introduced mutations in the LRP4 3rd beta-propeller domain, we show that the edge of the domain regulates the MuSK signaling whereas its central cavity governs Wnt signaling. We conclude that LRP4 is a new CMS disease gene and that the 3rd beta propeller domain of LRP4 mediates the two signaling pathways in a position-specific manner. PMID:24234652

  18. The human ubiquitin-conjugating enzyme Cdc34 controls cellular proliferation through regulation of p27{sup Kip1} protein levels

    SciTech Connect

    Butz, Nicole; Ruetz, Stephan; Natt, Francois; Hall, Jonathan; Weiler, Jan; Mestan, Juergen; Ducarre, Monique; Grossenbacher, Rita; Hauser, Patrick; Kempf, Dominique; Hofmann, Francesco . E-mail: francesco.hofmann@pharma.novartis.com

    2005-02-15

    Ubiquitin-mediated degradation of the cyclin-dependent kinase inhibitor p27{sup Kip1} was shown to be required for the activation of key cyclin-dependent kinases, thereby triggering the onset of DNA replication and cell cycle progression. Although the SCF{sup Skp2} ubiquitin ligase has been reported to mediate p27{sup Kip1} degradation, the nature of the human ubiquitin-conjugating enzyme involved in this process has not yet been determined at the cellular level. Here, we show that antisense oligonucleotides targeting the human ubiquitin-conjugating enzyme Cdc34 downregulate its expression, inhibit the degradation of p27{sup Kip1}, and prevent cellular proliferation. Elevation of p27{sup Kip1} protein level is found to be the sole requirement for the inhibition of cellular proliferation induced upon downregulation of Cdc34. Indeed, reducing the expression of p27{sup Kip1} with a specific antisense oligonucleotide is sufficient to reverse the anti-proliferative phenotype elicited by the Cdc34 antisense. Furthermore, downregulation of Cdc34 is found to specifically increase the abundance of the SCF{sup Skp2} ubiquitin ligase substrate p27{sup Kip1}, but has no concomitant effect on the level of IkB{alpha} and {beta}-catenin, which are known substrates of a closely related SCF ligase.

  19. Inhibitors of endocytosis prevent Wnt/Wingless signalling by reducing the level of basal β-catenin/Armadillo.

    PubMed

    Gagliardi, Maria; Hernandez, Ana; McGough, Ian J; Vincent, Jean-Paul

    2014-11-15

    A key step in the canonical Wnt signalling pathway is the inhibition of GSK3β, which results in the accumulation of nuclear β-catenin (also known as CTNNB1), and hence regulation of target genes. Evidence suggests that endocytosis is required for signalling, yet its role and the molecular understanding remains unclear. A recent and controversial model suggests that endocytosis contributes to Wnt signalling by causing the sequestration of the ligand-receptor complex, including LRP6 and GSK3 to multivesicular bodies (MVBs), thus preventing GSK3β from accessing β-catenin. Here, we use specific inhibitors (Dynasore and Dyngo-4a) to confirm the essential role of endocytosis in Wnt/Wingless signalling in human and Drosophila cells. However, we find no evidence that, in Drosophila cells or wing imaginal discs, LRP6/Arrow traffics to MVBs or that MVBs are required for Wnt/Wingless signalling. Moreover, we show that activation of signalling through chemical blockade of GSK3β is prevented by endocytosis inhibitors, suggesting that endocytosis impacts on Wnt/Wingless signalling downstream of the ligand-receptor complex. We propose that, through an unknown mechanism, endocytosis boosts the resting pool of β-catenin upon which GSK3β normally acts. PMID:25236598

  20. Inhibitors of endocytosis prevent Wnt/Wingless signalling by reducing the level of basal β-catenin/Armadillo.

    PubMed

    Gagliardi, Maria; Hernandez, Ana; McGough, Ian J; Vincent, Jean-Paul

    2014-11-15

    A key step in the canonical Wnt signalling pathway is the inhibition of GSK3β, which results in the accumulation of nuclear β-catenin (also known as CTNNB1), and hence regulation of target genes. Evidence suggests that endocytosis is required for signalling, yet its role and the molecular understanding remains unclear. A recent and controversial model suggests that endocytosis contributes to Wnt signalling by causing the sequestration of the ligand-receptor complex, including LRP6 and GSK3 to multivesicular bodies (MVBs), thus preventing GSK3β from accessing β-catenin. Here, we use specific inhibitors (Dynasore and Dyngo-4a) to confirm the essential role of endocytosis in Wnt/Wingless signalling in human and Drosophila cells. However, we find no evidence that, in Drosophila cells or wing imaginal discs, LRP6/Arrow traffics to MVBs or that MVBs are required for Wnt/Wingless signalling. Moreover, we show that activation of signalling through chemical blockade of GSK3β is prevented by endocytosis inhibitors, suggesting that endocytosis impacts on Wnt/Wingless signalling downstream of the ligand-receptor complex. We propose that, through an unknown mechanism, endocytosis boosts the resting pool of β-catenin upon which GSK3β normally acts.

  1. Graded Nodal/Activin Signaling Titrates Conversion of Quantitative Phospho-Smad2 Levels into Qualitative Embryonic Stem Cell Fate Decisions

    PubMed Central

    Orlov, Yuriy Lvovich; Yit, Le Yau; Yang, Henry; Ang, Lay Teng; Poellinger, Lorenz; Lim, Bing

    2011-01-01

    Nodal and Activin are morphogens of the TGFbeta superfamily of signaling molecules that direct differential cell fate decisions in a dose- and distance-dependent manner. During early embryonic development the Nodal/Activin pathway is responsible for the specification of mesoderm, endoderm, node, and mesendoderm. In contradiction to this drive towards cellular differentiation, the pathway also plays important roles in the maintenance of self-renewal and pluripotency in embryonic and epiblast stem cells. The molecular basis behind stem cell interpretation of Nodal/Activin signaling gradients and the undertaking of disparate cell fate decisions remains poorly understood. Here, we show that any perturbation of endogenous signaling levels in mouse embryonic stem cells leads to their exit from self-renewal towards divergent differentiation programs. Increasing Nodal signals above basal levels by direct stimulation with Activin promotes differentiation towards the mesendodermal lineages while repression of signaling with the specific Nodal/Activin receptor inhibitor SB431542 induces trophectodermal differentiation. To address how quantitative Nodal/Activin signals are translated qualitatively into distinct cell fates decisions, we performed chromatin immunoprecipitation of phospho-Smad2, the primary downstream transcriptional factor of the Nodal/Activin pathway, followed by massively parallel sequencing, and show that phospho-Smad2 binds to and regulates distinct subsets of target genes in a dose-dependent manner. Crucially, Nodal/Activin signaling directly controls the Oct4 master regulator of pluripotency by graded phospho-Smad2 binding in the promoter region. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titrates self-renewal against alternative differentiation programs by direct regulation of distinct target gene subsets and Oct4 expression. PMID

  2. 47 CFR Appendix I to Subpart E of... - A Procedure for Calculating PCS Signal Levels at Microwave Receivers (Appendix E of the...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... at Microwave Receivers (Appendix E of the Memorandum Opinion and Order) I Appendix I to Subpart E of... PERSONAL COMMUNICATIONS SERVICES Broadband PCS Pt. 24, Subpt. E, App. I Appendix I to Subpart E of Part 24—A Procedure for Calculating PCS Signal Levels at Microwave Receivers (Appendix E of the...

  3. Diverse phosphorylation patterns of B cell receptor-associated signaling in naïve and memory human B cells revealed by phosphoflow, a powerful technique to study signaling at the single cell level

    PubMed Central

    Toapanta, Franklin R.; Bernal, Paula J.; Sztein, Marcelo B.

    2012-01-01

    Following interaction with cognate antigens, B cells undergo cell activation, proliferation, and differentiation. Ligation of the B cell receptor (BCR) leads to the phosphorylation of BCR-associated signaling proteins within minutes of antigen binding, a process with profound consequences for the fate of the cells and development of effector immunity. Phosphoflow allows a rapid evaluation of various signaling pathways in complex heterogenous cell subsets. This novel technique was used in combination with multi-chromatic flow cytometry (FC) and fluorescent-cell barcoding (FCB) to study phosphorylation of BCR-associated signaling pathways in naïve and memory human B cell subsets. Proteins of the initiation (Syk), propagation (Btk, Akt), and integration (p38MAPK and Erk1/2) signaling units were studied. Switched memory (Sm) CD27+ and Sm CD27− phosphorylation patterns were similar when stimulated with anti-IgA or -IgG. In contrast, naïve and unswitched memory (Um) cells showed significant differences following IgM stimulation. Enhanced phosphorylation of Syk was observed in Um cells, suggesting a lower activation threshold. This is likely the result of higher amounts of IgM on the cell surface, higher pan-Syk levels, and enhanced susceptibility to phosphatase inhibition. All other signaling proteins evaluated also showed some degree of enhanced phosphorylation in Um cells. Furthermore, both the phospholipase C-γ2 (PLC-γ2) and phosphatidylinositol 3-kinase (PI3K) pathways were activated in Um cells, while only the PI3K pathway was activated on naïve cells. Um cells were the only ones that activated signaling pathways when stimulated with fluorescently labeled S. Typhi and S. pneumoniae. Finally, simultaneous evaluation of signaling proteins at the single cell level (multiphosphorylated cells) revealed that interaction with gram positive and negative bacteria resulted in complex and diverse signaling patterns. Phosphoflow holds great potential to accelerate

  4. The effects of graded levels of calorie restriction: VI. Impact of short-term graded calorie restriction on transcriptomic responses of the hypothalamic hunger and circadian signaling pathways.

    PubMed

    Derous, Davina; Mitchell, Sharon E; Green, Cara L; Chen, Luonan; Han, Jing-Dong J; Wang, Yingchun; Promislow, Daniel E L; Lusseau, David; Speakman, John R; Douglas, Alex

    2016-04-01

    Food intake and circadian rhythms are regulated by hypothalamic neuropeptides and circulating hormones, which could mediate the anti-ageing effect of calorie restriction (CR). We tested whether these two signaling pathways mediate CR by quantifying hypothalamic transcripts of male C57BL/6 mice exposed to graded levels of CR (10 % to 40 %) for 3 months. We found that the graded CR manipulation resulted in upregulation of core circadian rhythm genes, which correlated negatively with circulating levels of leptin, insulin-like growth factor 1 (IGF-1), insulin, and tumor necrosis factor alpha (TNF-α). In addition, key components in the hunger signaling pathway were expressed in a manner reflecting elevated hunger at greater levels of restriction, and which also correlated negatively with circulating levels of insulin, TNF-α, leptin and IGF-1. Lastly, phenotypes, such as food anticipatory activity and body temperature, were associated with expression levels of both hunger genes and core clock genes. Our results suggest modulation of the hunger and circadian signaling pathways in response to altered levels of circulating hormones, that are themselves downstream of morphological changes resulting from CR treatment, may be important elements in the response to CR, driving some of the key phenotypic outcomes.

  5. Vandetanib inhibits both VEGFR-2 and EGFR signalling at clinically relevant drug levels in preclinical models of human cancer.

    PubMed

    Brave, Sandra R; Odedra, Rajesh; James, Neil H; Smith, Neil R; Marshall, Gayle B; Acheson, Kerry L; Baker, Dawn; Howard, Zoe; Jackson, Lynsay; Ratcliffe, Kirsty; Wainwright, Anna; Lovick, Susan C; Hickinson, D Mark; Wilkinson, Robert W; Barry, Simon T; Speake, Georgina; Ryan, Anderson J

    2011-07-01

    Vandetanib is a multi-targeted receptor tyrosine kinase inhibitor that is in clinical development for the treatment of solid tumours. This preclinical study examined the inhibition of two key signalling pathways (VEGFR-2, EGFR) at drug concentrations similar to those achieved in the clinic, and their contribution to direct and indirect antitumour effects of vandetanib. For in vitro studies, receptor phosphorylation was assessed by Western blotting and ELISA, cell proliferation was assessed using a cell viability endpoint, and effects on cell cycle determined using flow cytometry. For in vivo studies, Western blotting, ELISA and immunohistochemistry (IHC) were used to assess receptor phosphorylation. Cell culture experiments demonstrated that anti-proliferative effects of vandetanib resulted from inhibition of either EGFR or VEGFR-2 signalling in endothelial cells, but were associated with inhibition of EGFR signalling in tumour cells. Vandetanib inhibited both EGFR and VEGFR-2 signalling in normal lung tissue and in tumour xenografts. In a lung cancer model expressing an activating EGFR mutation, the activity of vandetanib was similar to that of a highly selective EGFR inhibitor (gefitinib), and markedly greater than that of a highly selective VEGFR inhibitor (vatalanib). These data suggest that at the plasma exposures achieved in the clinic, vandetanib will significantly inhibit both VEGFR-2 and EGFR signalling, and that both inhibition of angiogenesis and direct inhibition of tumour cell growth can contribute to treatment response. PMID:21537841

  6. Down-regulated expression of the protein-tyrosine phosphatase 1B (PTP1B) is associated with aggressive clinicopathologic features and poor prognosis in hepatocellular carcinoma

    SciTech Connect

    Zheng, Long-Yi; Zhou, Dong-Xun; Lu, Jin; Zhang, Wen-Jun; Zou, Da-Jin

    2012-04-13

    Highlights: Black-Right-Pointing-Pointer PTP1B protein showed decreased expression in 67.79% of the HCC patients. Black-Right-Pointing-Pointer Low PTP1B expression predicts poor prognosis of HCC. Black-Right-Pointing-Pointer Low PTP1B expression is correlated with expansion of OV6{sup +} tumor-initiating cells. Black-Right-Pointing-Pointer Down-regulation of PTP1B is associated with activation of Wnt/{beta}-Catenin signaling. -- Abstract: The protein-tyrosine phosphatase 1B (PTP1B) is a classical non-transmembrane protein tyrosine phosphatase that plays a key role in metabolic signaling and can exert both tumor suppressing and tumor promoting effects in different cancers depending on the substrate involved and the cellular context. However, the expression level and function of PTP1B in hepatocellular carcinoma (HCC) remain unclear. In this study, PTP1B expression was detected by immunohistochemistry in normal liver tissue (n = 16) and hepatocellular carcinoma (n = 169). The correlations between PTP1B expression level and clinicopathologic features and patient survival were also analyzed. One hundred and eleven of 169 HCC patients (65.7%) had negative or low PTP1B expression in tumorous tissues, whereas normal tissues always expressed strong PTP1B. Decreased PTP1B expression was significantly associated with aggressive clinicopathologic features and poor prognosis. Immunohistochemistry also showed that low PTP1B expression level was correlated with high percentage of OV6{sup +} tumor-initiating cells (T-ICs) and high frequency of nuclear {beta}-Catenin expression in HCC specimens. Our findings demonstrate for the first time that the loss of inhibitory effect of PTP1B may contribute to progression and invasion of HCC through activation of Wnt/{beta}-Catenin signaling and expansion of liver T-ICs. PTP1B may serve as a valuable prognostic biomarker and potential therapeutic target in HCC.

  7. PTEN permits acute increases in D3-phosphoinositide levels following TCR stimulation but inhibits distal signaling events by reducing the basal activity of Akt.

    PubMed

    Seminario, Maria-Cristina; Precht, Patricia; Bunnell, Stephen C; Warren, Sarah E; Morris, Christa M; Taub, Dennis; Wange, Ronald L

    2004-11-01

    Phosphoinositide 3-kinase (PI3K) is important in TCR signaling. PI3K generates phosphatidylinositol 3, 4, 5-trisphosphate (PI-3,4,5-P3), which regulates membrane localization and/or activity of multiple signaling proteins. PTEN (phosphatase and tensin homologue deleted on chromosome 10) opposes PI3K, reversing this reaction. Maintaining the balance between these two enzymes is important for normal T cell function. Here we use the PTEN-null Jurkat T cell line to address the role of PTEN in modulating proximal and distal TCR-signaling events. PTEN expression at levels that restored low basal Akt phosphorylation (an indicator of PI-3,4,5-P3 levels), but which were not themselves cytotoxic, had minimal effect on TCR-stimulated activation of phospholipase Cgamma1 and Ca2+ flux, but reduced the duration of extracellular signal-regulated kinase (Erk) activation. Distal signaling events, including nuclear factor of activated T cells (NFAT) activation, CD69 expression and IL-2 production, were all inhibited by PTEN expression. Notably, PTEN did not block TCR-stimulated PI-3,4,5-P3 accumulation. The effect of PTEN on distal TCR signaling events was strongly correlated with the loss of the constitutive Akt activation and glycogen synthase kinase-3 (GSK3) inhibition that is typical of Jurkat cells, and could be reversed by expression of activated Akt or pharmacologic inhibition of GSK3. These results suggest that PTEN acts in T cells primarily to control basal PI-3,4,5-P3 levels, rather than opposing PI3K acutely during TCR stimulation.

  8. A plant flavonoid fisetin induces apoptosis in colon cancer cells by inhibition of COX2 and Wnt/EGFR/NF-kappaB-signaling pathways.

    PubMed

    Suh, Yewseok; Afaq, Farrukh; Johnson, Jeremy J; Mukhtar, Hasan

    2009-02-01

    Overexpression of cyclooxygenase 2 (COX2) and uncontrolled wingless and Int (Wnt)-signaling pathway have long been suggested to play crucial roles in colorectal cancer. Studies show that selective COX2 inhibitors possess great potential as chemopreventive agents for colon cancer. Recent studies suggest that targeting COX2 and epidermal growth factor receptor (EGFR) may provide better therapeutic strategy than inhibiting either single target and that this may alleviate the problem of COX2 inhibitor-associated side effects. Therefore, there have been intensive efforts to develop novel dietary substances that target COX2 and EGFR activation. Fisetin is a naturally occurring flavonoid commonly found in various vegetables and fruits. We found that the treatment of COX2-overexpressing HT29 human colon cancer cells with fisetin (30-120 microM) resulted in induction of apoptosis, downregulation of COX2 protein expression without affecting COX1 and inhibited the secretion of prostaglandin E2. Treatment of cells with fisetin also inhibited Wnt-signaling activity through downregulation of beta-catenin and T cell factor 4 and decreased the expression of target genes such as cyclin D1 and matrix metalloproteinase 7. Fisetin treatment of cells also inhibited the activation of EGFR and nuclear factor-kappa B (NF-kappaB). Finally, the formation of colonies in soft agar was suppressed by fisetin treatment. Taken together, we provide evidence that the plant flavonoid fisetin can induce apoptosis and suppress the growth of colon cancer cells by inhibition of COX2- and Wnt/EGFR/NF-kappaB-signaling pathways. We suggest that fisetin could be a useful agent for prevention and treatment of colon cancer.

  9. Fibulin-4 deficiency increases TGF-β signalling in aortic smooth muscle cells due to elevated TGF-β2 levels.

    PubMed

    Ramnath, N W M; Hawinkels, L J A C; van Heijningen, P M; te Riet, L; Paauwe, M; Vermeij, M; Danser, A H J; Kanaar, R; ten Dijke, P; Essers, J

    2015-11-26

    Fibulins are extracellular matrix proteins associated with elastic fibres. Homozygous Fibulin-4 mutations lead to life-threatening abnormalities such as aortic aneurysms. Aortic aneurysms in Fibulin-4 mutant mice were associated with upregulation of TGF-β signalling. How Fibulin-4 deficiency leads to deregulation of the TGF-β pathway is largely unknown. Isolated aortic smooth muscle cells (SMCs) from Fibulin-4 deficient mice showed reduced growth, which could be reversed by treatment with TGF-β neutralizing antibodies. In Fibulin-4 deficient SMCs increased TGF-β signalling was detected using a transcriptional reporter assay and by increased SMAD2 phosphorylation. Next, we investigated if the increased activity was due to increased levels of the three TGF-β isoforms. These data revealed slightly increased TGF-β1 and markedly increased TGF-β2 levels. Significantly increased TGF-β2 levels were also detectable in plasma from homozygous Fibulin-4(R/R) mice, not in wild type mice. TGF-β2 levels were reduced after losartan treatment, an angiotensin-II type-1 receptor blocker, known to prevent aortic aneurysm formation. In conclusion, we have shown increased TGF-β signalling in isolated SMCs from Fibulin-4 deficient mouse aortas, not only caused by increased levels of TGF-β1, but especially TGF-β2. These data provide new insights in the molecular interaction between Fibulin-4 and TGF-β pathway regulation in the pathogenesis of aortic aneurysms.

  10. Fibulin-4 deficiency increases TGF-β signalling in aortic smooth muscle cells due to elevated TGF-β2 levels

    PubMed Central

    Ramnath, N. W. M.; Hawinkels, L. J. A. C.; van Heijningen, P. M.; Riet, L. te; Paauwe, M.; Vermeij, M.; Danser, A. H. J.; Kanaar, R.; ten Dijke, P.; Essers, J.

    2015-01-01

    Fibulins are extracellular matrix proteins associated with elastic fibres. Homozygous Fibulin-4 mutations lead to life-threatening abnormalities such as aortic aneurysms. Aortic aneurysms in Fibulin-4 mutant mice were associated with upregulation of TGF-β signalling. How Fibulin-4 deficiency leads to deregulation of the TGF-β pathway is largely unknown. Isolated aortic smooth muscle cells (SMCs) from Fibulin-4 deficient mice showed reduced growth, which could be reversed by treatment with TGF-β neutralizing antibodies. In Fibulin-4 deficient SMCs increased TGF-β signalling was detected using a transcriptional reporter assay and by increased SMAD2 phosphorylation. Next, we investigated if the increased activity was due to increased levels of the three TGF-β isoforms. These data revealed slightly increased TGF-β1 and markedly increased TGF-β2 levels. Significantly increased TGF-β2 levels were also detectable in plasma from homozygous Fibulin-4R/R mice, not in wild type mice. TGF-β2 levels were reduced after losartan treatment, an angiotensin-II type-1 receptor blocker, known to prevent aortic aneurysm formation. In conclusion, we have shown increased TGF-β signalling in isolated SMCs from Fibulin-4 deficient mouse aortas, not only caused by increased levels of TGF-β1, but especially TGF-β2. These data provide new insights in the molecular interaction between Fibulin-4 and TGF-β pathway regulation in the pathogenesis of aortic aneurysms. PMID:26607280

  11. Increasing the endogenous NO level causes catalase inactivation and reactivation of intercellular apoptosis signaling specifically in tumor cells.

    PubMed

    Bauer, Georg

    2015-12-01

    Tumor cells generate extracellular superoxide anions and are protected against intercellular apoptosis-inducing HOCl- and NO/peroxynitrite signaling through the expression of membrane-associated catalase. This enzyme decomposes H2O2 and thus prevents HOCl synthesis. It efficiently interferes with NO/peroxynitrite signaling through oxidation of NO and decomposition of peroxynitrite. The regulatory potential of catalase at the crosspoint of ROS and RNS chemical biology, as well as its high local concentration on the outside of the cell membrane of tumor cells, establish tight control of intercellular signaling and thus prevent tumor cell apoptosis. Therefore, inhibition of catalase or its inactivation by singlet oxygen reactivate intercellular apoptosis-inducing signaling. Nitric oxide and peroxynitrite are connected with catalase in multiple and meaningful ways, as (i) NO can be oxidated by compound I of catalase, (ii) NO can reversibly inhibit catalase, (iii) peroxynitrite can be decomposed by catalase and (iv) the interaction between peroxynitrite and H2O2 leads to the generation of singlet oxygen that inactivates catalase. Therefore, modulation of the concentration of free NO through addition of arginine, inhibition of arginase, induction of NOS expression or inhibition of NO dioxygenase triggers an autoamplificatory biochemical cascade that is based on initial formation of singlet oxygen, amplification of superoxide anion/H2O2 and NO generation through singlet oxygen dependent stimulation of the FAS receptor and caspase-8. Finally, singlet oxygen is generated at sufficiently high concentration to inactivate protective catalase and to reactivate intercellular apoptosis-inducing ROS signaling. This regulatory network allows to establish several pathways for synergistic interactions, like the combination of modulators of NO metabolism with enhancers of superoxide anion generation, modulators of NO metabolism that act at different targets and between modulators of

  12. Increasing the endogenous NO level causes catalase inactivation and reactivation of intercellular apoptosis signaling specifically in tumor cells

    PubMed Central

    Bauer, Georg

    2015-01-01

    Tumor cells generate extracellular superoxide anions and are protected against intercellular apoptosis-inducing HOCl- and NO/peroxynitrite signaling through the expression of membrane-associated catalase. This enzyme decomposes H2O2 and thus prevents HOCl synthesis. It efficiently interferes with NO/peroxynitrite signaling through oxidation of NO and decomposition of peroxynitrite. The regulatory potential of catalase at the crosspoint of ROS and RNS chemical biology, as well as its high local concentration on the outside of the cell membrane of tumor cells, establish tight control of intercellular signaling and thus prevent tumor cell apoptosis. Therefore, inhibition of catalase or its inactivation by singlet oxygen reactivate intercellular apoptosis-inducing signaling. Nitric oxide and peroxynitrite are connected with catalase in multiple and meaningful ways, as (i) NO can be oxidated by compound I of catalase, (ii) NO can reversibly inhibit catalase, (iii) peroxynitrite can be decomposed by catalase and (iv) the interaction between peroxynitrite and H2O2 leads to the generation of singlet oxygen that inactivates catalase. Therefore, modulation of the concentration of free NO through addition of arginine, inhibition of arginase, induction of NOS expression or inhibition of NO dioxygenase triggers an autoamplificatory biochemical cascade that is based on initial formation of singlet oxygen, amplification of superoxide anion/H2O2 and NO generation through singlet oxygen dependent stimulation of the FAS receptor and caspase-8. Finally, singlet oxygen is generated at sufficiently high concentration to inactivate protective catalase and to reactivate intercellular apoptosis-inducing ROS signaling. This regulatory network allows to establish several pathways for synergistic interactions, like the combination of modulators of NO metabolism with enhancers of superoxide anion generation, modulators of NO metabolism that act at different targets and between modulators of

  13. Nicotine reduces the levels of surfactant proteins A and D via Wnt/β-catenin and PKC signaling in human airway epithelial cells.

    PubMed

    Zou, Weifeng; Liu, Sha; Hu, Jinxing; Sheng, Qing; He, Fang; Li, Bing; Ran, Pixin

    2016-01-15

    A deficiency of surfactant proteins A and D has been proposed as a mechanism in airway remodeling, which is one characteristic of chronic obstructive pulmonary disease (COPD). We recently showed that in vitro nicotine exposure induces Wnt3a/β-catenin activation, which is a pathway that has also been implicated in altering levels of SP-A and SP-D. Nicotine induced activation of protein kinase C(PKC), and the involvement of PKC in mediating Wnt signaling has been demonstrated previously. The main aim of this study was to investigate whether human bronchial epithelial cells reduce levels of SP-A and SP-D in vitro following nicotine stimulation via the Wnt3a/β-catenin and PKC signaling pathway. We showed that nicotine activated the Wnt3a/β-catenin and PKC signaling pathway, and this activation was accompanied by a decrease in SP-A and SP-D expression. Knockdown of Wnt3a with small interfering RNA (siRNA) prevented translocation of β-catenin into the nucleus and reduction levels of SP-A and SP-D. Furthermore, a PKC inhibitor partially prevented these effects,which suggests in HBECs, Wnt3a/β-catenin and PKC pathways interact during nicotine-reduced levels of SP-A and SP-D. These results suggest that HBECs reduce the levels of surfactant proteins A and D in vitro via the Wnt3a/β-catenin and PKC signaling pathway upon nicotine stimulation.

  14. Biometric Methods for Secure Communications in Body Sensor Networks: Resource-Efficient Key Management and Signal-Level Data Scrambling

    NASA Astrophysics Data System (ADS)

    Bui, Francis Minhthang; Hatzinakos, Dimitrios

    2007-12-01

    As electronic communications become more prevalent, mobile and universal, the threats of data compromises also accordingly loom larger. In the context of a body sensor network (BSN), which permits pervasive monitoring of potentially sensitive medical data, security and privacy concerns are particularly important. It is a challenge to implement traditional security infrastructures in these types of lightweight networks since they are by design limited in both computational and communication resources. A key enabling technology for secure communications in BSN's has emerged to be biometrics. In this work, we present two complementary approaches which exploit physiological signals to address security issues: (1) a resource-efficient key management system for generating and distributing cryptographic keys to constituent sensors in a BSN; (2) a novel data scrambling method, based on interpolation and random sampling, that is envisioned as a potential alternative to conventional symmetric encryption algorithms for certain types of data. The former targets the resource constraints in BSN's, while the latter addresses the fuzzy variability of biometric signals, which has largely precluded the direct application of conventional encryption. Using electrocardiogram (ECG) signals as biometrics, the resulting computer simulations demonstrate the feasibility and efficacy of these methods for delivering secure communications in BSN's.

  15. The effect of GSM and TETRA mobile handset signals on blood pressure, catechol levels and heart rate variability.

    PubMed

    Barker, Anthony T; Jackson, Peter R; Parry, Helen; Coulton, Leslie A; Cook, Greg G; Wood, Steven M

    2007-09-01

    An acute rise in blood pressure has been reported in normal volunteers during exposure to signals from a mobile phone handset. To investigate this finding further we carried out a double blind study in 120 healthy volunteers (43 men, 77 women) in whom we measured mean arterial pressure (MAP) during each of six exposure sessions. At each session subjects were exposed to one of six different radio frequency signals simulating both GSM and TETRA handsets in different transmission modes. Blood catechols before and after exposure, heart rate variability during exposure, and post exposure 24 h ambulatory blood pressure were also studied. Despite having the power to detect changes in MAP of less than 1 mmHg none of our measurements showed any effect which we could attribute to radio frequency exposure. We found a single statistically significant decrease of 0.7 mmHg (95% CI 0.3-1.2 mmHg, P = .04) with exposure to GSM handsets in sham mode. This may be due to a slight increase in operating temperature of the handsets when in this mode. Hence our results have not confirmed the original findings of an acute rise in blood pressure due to exposure to mobile phone handset signals. In light of this negative finding from a large study, coupled with two smaller GSM studies which have also proved negative, we are of the view that further studies of acute changes in blood pressure due to GSM and TETRA handsets are not required. PMID:17486598

  16. Rer1p maintains ciliary length and signaling by regulating γ-secretase activity and Foxj1a levels.

    PubMed

    Jurisch-Yaksi, Nathalie; Rose, Applonia J; Lu, Huiqi; Raemaekers, Tim; Munck, Sebastian; Baatsen, Pieter; Baert, Veerle; Vermeire, Wendy; Scales, Suzie J; Verleyen, Daphne; Vandepoel, Roel; Tylzanowski, Przemko; Yaksi, Emre; de Ravel, Thomy; Yost, H Joseph; Froyen, Guy; Arrington, Cammon B; Annaert, Wim

    2013-03-18

    Cilia project from the surface of most vertebrate cells and are important for several physiological and developmental processes. Ciliary defects are linked to a variety of human diseases, named ciliopathies, underscoring the importance of understanding signaling pathways involved in cilia formation and maintenance. In this paper, we identified Rer1p as the first endoplasmic reticulum/cis-Golgi-localized membrane protein involved in ciliogenesis. Rer1p, a protein quality control receptor, was highly expressed in zebrafish ciliated organs and regulated ciliary structure and function. Both in zebrafish and mammalian cells, loss of Rer1p resulted in the shortening of cilium and impairment of its motile or sensory function, which was reflected by hearing, vision, and left-right asymmetry defects as well as decreased Hedgehog signaling. We further demonstrate that Rer1p depletion reduced ciliary length and function by increasing γ-secretase complex assembly and activity and, consequently, enhancing Notch signaling as well as reducing Foxj1a expression.

  17. Rer1p maintains ciliary length and signaling by regulating γ-secretase activity and Foxj1a levels

    PubMed Central

    Jurisch-Yaksi, Nathalie; Rose, Applonia J.; Lu, Huiqi; Raemaekers, Tim; Munck, Sebastian; Baatsen, Pieter; Baert, Veerle; Vermeire, Wendy; Scales, Suzie J.; Verleyen, Daphne; Vandepoel, Roel; Tylzanowski, Przemko; Yaksi, Emre; de Ravel, Thomy; Yost, H. Joseph; Froyen, Guy; Arrington, Cammon B.

    2013-01-01

    Cilia project from the surface of most vertebrate cells and are important for several physiological and developmental processes. Ciliary defects are linked to a variety of human diseases, named ciliopathies, underscoring the importance of understanding signaling pathways involved in cilia formation and maintenance. In this paper, we identified Rer1p as the first endoplasmic reticulum/cis-Golgi–localized membrane protein involved in ciliogenesis. Rer1p, a protein quality control receptor, was highly expressed in zebrafish ciliated organs and regulated ciliary structure and function. Both in zebrafish and mammalian cells, loss of Rer1p resulted in the shortening of cilium and impairment of its motile or sensory function, which was reflected by hearing, vision, and left–right asymmetry defects as well as decreased Hedgehog signaling. We further demonstrate that Rer1p depletion reduced ciliary length and function by increasing γ-secretase complex assembly and activity and, consequently, enhancing Notch signaling as well as reducing Foxj1a expression. PMID:23479743

  18. Luminescence Dating of Tsunami sediments : Residual Signal Levels in Sediments from the 26th December 2004 Indian Ocean Event in Thailand.

    NASA Astrophysics Data System (ADS)

    Sanderson, D. C.; Bishop, P.; Hansom, J.; Curry, G.; Chaimanee, N.

    2007-05-01

    Luminescence dating has been applied in the past to several tsunami deposits, notably from Northern Australia, the Scilly Isles, Scotland and Chile. Providing initial signals levels are close to zero, optically stimulated luminescence (OSL) dating is a promising method for dating palaeo-tsunami sediments, and providing an indication of past frequencies of occurrence of at least large scale events. The time resolution available, however, is critically dependent on initial signal levels in zero age deposits. With that in mind we have undertaken a study of sediments deposited in Phang Nga province and Phuket in Thailand by the 26th December 2004 tsunami. Approximately 250 sediment samples were collected from a diverse range of settings early in 2005 and prior to monsoonal disturbance. A newly developed portable OSL reader was used to assist fieldwork by making real- time measurements during the fieldwork period of more than 100 samples. This proved invaluable in confirming that all tsunami deposited material retained measureable luminescence signals, and guiding sampling towards an examination of the underlying factors that influence residual levels. Samples were collected from pre-tsunami ground surfaces, from basal and superficial tsunami deposits, from stratified sediments showing multiple sequences of coarse and fine sediments associated with different parts of the wavetrain, from a series of open and shaded back-beach locations, and from a transect reaching inland for approximately 1 km. Laboratory studies have now been conducted to extend initial screening measurements to all samples, and to perform calibrated analyses of mineral separates from selected samples. The work has confirmed that non-zero initial signal levels are present in all samples. The magnitude of such signals ranges over 4 orders of magnitude apparently controlled by the inherited age of the source sediment being entrained in the tsunami wave prior to redeposition. The lowest residual signal

  19. A furin inhibitor downregulates osteosarcoma cell migration by downregulating the expression levels of MT1-MMP via the Wnt signaling pathway

    PubMed Central

    LIU, BINGSHAN; LI, GUOJUN; WANG, XIAO; LIU, YANG

    2014-01-01

    This study aimed to explore the exact mechanism of the effect of a furin inhibitor on the migration and invasion of MG-63 and Saos-2 osteosarcoma cells. MG-63 and Saos-2 osteosarcoma cells were treated with regular culture medium in the presence or absence of 480 nM α1-antitrypsin Portland (α1-PDX). Wound-healing and Transwell assays were used for the detection of the effects of α1-PDX on MG-63 and Saos-2 osteosarcoma cell migration and invasion. Western blot analysis and reverse transcription-polymerase chain reaction were performed to detect the expression levels of membrane type I matrix metalloproteinase (MT1-MMP), Wnt and β-catenin. A chromatin immunoprecipitation assay was used for detection of the levels of MT1-MMP gene transcription activity. The results showed that α1-PDX treatment significantly reduced the migration and invasion ability of the cells. Notably, the expression levels of MT1-MMP decreased evidently upon α1-PDX treatment, paralleled with reductions in the expression levels of Wnt and β-catenin. Further analysis of the transcriptional activity of MT1-MMP revealed that the α1-PDX-induced downregulation of the levels of MT1-MMP was mediated by the Wnt signaling pathway. These data suggest that α1-PDX plays a vital role in inhibiting MG-63 and Saos-2 osteosarcoma cell migration and invasion by downregulating the expression levels of MT1-MMP via the Wnt signaling pathway. PMID:24944664

  20. Measuring vascular reactivity with breath-holds after stroke: a method to aid interpretation of group-level BOLD signal changes in longitudinal fMRI studies.

    PubMed

    Geranmayeh, Fatemeh; Wise, Richard J S; Leech, Robert; Murphy, Kevin

    2015-05-01

    Blood oxygenation level-dependent (BOLD) contrast functional magnetic resonance imaging (fMRI) is a widely used technique to map brain function, and to monitor its recovery after stroke. Since stroke has a vascular etiology, the neurovascular coupling between cerebral blood flow and neural activity may be altered, resulting in uncertainties when interpreting longitudinal BOLD signal changes. The purpose of this study was to demonstrate the feasibility of using a recently validated breath-hold task in patients with stroke, both to assess group level changes in cerebrovascular reactivity (CVR) and to determine if alterations in regional CVR over time will adversely affect interpretation of task-related BOLD signal changes. Three methods of analyzing the breath-hold data were evaluated. The CVR measures were compared over healthy tissue, infarcted tissue and the peri-infarct tissue, both sub-acutely (∼2 weeks) and chronically (∼4 months). In this cohort, a lack of CVR differences in healthy tissue between the patients and controls indicates that any group level BOLD signal change observed in these regions over time is unlikely to be related to vascular alterations. CVR was reduced in the peri-infarct tissue but remained unchanged over time. Therefore, although a lack of activation in this region compared with the controls may be confounded by a reduced CVR, longitudinal group-level BOLD changes may be more confidently attributed to neural activity changes in this cohort. By including this breath-hold-based CVR assessment protocol in future studies of stroke recovery, researchers can be more assured that longitudinal changes in BOLD signal reflect true alterations in neural activity.