The Experts below are selected from a list of 123558 Experts worldwide ranked by ideXlab platform
Lucy Liaw - One of the best experts on this subject based on the ideXlab platform.
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through cyclin dependent kinase inhibitor 1b
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale:Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective:Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared with uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMCs. Methods and Results:In human primary VSMCs, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27kip1 were observed downstream of Jag-1/Notch2 signaling and were required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination, and prolonged half-life of p27kip1. Jag-1/Notch2 signaling robustly decreased S-phase kinase–associated protein, an F-box protein that degrades p27kip1 during G1. Overexpression of S-phase kinase–as...
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through p27kip1
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale: Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective: Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared to uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMC. Methods and Results: In human primary VSMC, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27 kip1 were observed downstream of Jag-1/Notch2 signaling, and required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination and prolonged half-life of p27 kip1 . Jag-1/Notch2 signaling robustly decreased S-phase kinase associated protein (Skp2), an F-box protein that degrades p27 kip1 during G1. Over expression of Skp2 prior to Notch activation by Jag-1 suppressed the induction of p27 kip1 . Additionally, increased Notch2 andp27 kip1 expression was co-localized to the non-proliferative zone of injured arteries as indicated by co-staining with proliferating cell nuclear antigen (PCNA), whereas Notch3 was expressed throughout normal and injured arteries, suggesting Notch2 may negatively regulate lesion formation. Conclusions: We propose a receptor specific function for Notch2 in regulating Jag-1-induced p27 kip1 expression and growth arrest in VSMC. During vascular remodeling, co-localization of Notch2 and p27 kip1 to the non-proliferating region supports a model where Notch2 activation may negatively regulate VSMC proliferation to lessen the severity of the lesion. Thus Notch2 is a potential target for control of VSMC hyperplasia.
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Hairy-Related Transcription Factors Inhibit Notch-Induced Smooth Muscle α-Actin Expression by Interfering With Notch Intracellular Domain/CBF-1 Complex Interaction With the CBF-1–Binding Site
Circulation Research, 2008Co-Authors: Yuefeng Tang, Lucy LiawAbstract:Notch signaling regulates smooth muscle cell phenotype and is critical for vascular development. One Notch target is smooth muscle α-actin (SMA), a differentiated smooth muscle cell marker. The Notch intracellular domain (NotchICD) forms a complex with CBF-1 (C-promoter– binding factor-1) and directly induces SMA expression. Using primary human smooth muscle cells, we show that expression of the constitutive active ICD of human Notch1, Notch2, or Notch4 receptors increase SMA levels. NotchICD also induce expression of the transcriptional repressors HRT1 (Hairy-related transcription factor 1) and HRT2, in a CBF-1–dependent manner. However, unlike the activating effects of NotchICD, HRT1 or HRT2 represses basal SMA expression, and both are strong antagonists of NotchICD-induced SMA upregulation. This antagonism does not depend on histone deacetylase activity and occurs at the transcriptional level. Competitive coimmunoprecipitation experiments demonstrate that HRT does not disrupt the association of NotchICD and CBF-1, which form a complex in the presence or absence of HRTs. However, HRT suppresses NotchICD/CBF-1 binding to the SMA promoter, as measured by chromatin immunoprecipitation, and transactivation of an SMA promoter reporter spanning sequences −124/+32. SMA expression was regulated similarly following endogenous Notch activation in smooth muscle cells by coculture with endothelial cells, and this effect was also sensitive to HRT inhibition. Temporally defined HRT activity may constitute a negative feedback mechanism of Notch signaling. Our study presents a novel mechanism by which a balance between Notch signaling and HRT activity determines the expression of smooth muscle differentiation markers including SMA.
Shivendra V Singh - One of the best experts on this subject based on the ideXlab platform.
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The role of polycomb group protein Bmi-1 and Notch4 in breast cancer stem cell inhibition by benzyl isothiocyanate
Breast Cancer Research and Treatment, 2015Co-Authors: Shivendra V SinghAbstract:We showed previously that garden cress constituent benzyl isothiocyanate (BITC) inhibits self-renewal of breast cancer stem cells (bCSC) in vitro and in vivo. The present study offers novel insights into the mechanism by which BITC inhibits bCSC. Flow cytometry and mammosphere assay were performed to quantify bCSC fraction. Protein expression was determined by western blotting. Apoptosis was assessed by flow cytometry using Annexin V-propidium iodide method. Cell migration was determined by Boyden chamber assay. BITC treatment resulted in a marked decrease in protein level of polycomb group protein B-lymphoma Moloney murine leukemia virus insertion region-1 (Bmi-1) in cultured human breast cancer cells (MCF-7, SUM159, MDA-MB-231, and MDA-MB-361) and MDA-MB-231 xenografts in vivo. Overexpression (MCF-7) or knockdown (SUM159, and MDA-MB-231) of Bmi-1 protein had no meaningful impact on the BITC’s ability to inhibit cell viability and cell migration and/or induce apoptosis. On the other hand, inhibition of bCSC markers (aldehyde dehydrogenase 1 activity and mammosphere frequency) resulting from BITC exposure was significantly altered by Bmi-1 overexpression and knockdown. BITC was previously shown to cause activation of Notch1, Notch2, and Notch4 in association with induction of γ-secretase complex component Nicastrin, which are also implicated in maintenance of cancer stemness. BITC-mediated inhibition of bCSC was augmented by knockdown of Notch4 and Nicastrin, but not by RNA interference of Notch1 or Notch2. The present study highlights important roles for Bmi-1 and Notch4 in BITC-mediated suppression of bCSC.
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withaferin a causes activation of notch2 and notch4 in human breast cancer cells
Breast Cancer Research and Treatment, 2012Co-Authors: Joomin Lee, Anuradha Sehrawat, Shivendra V SinghAbstract:Ayurvedic medicine plants continue to draw attention for the discovery of novel anticancer agents. Withaferin A (WA) is one such small-molecule constituent of the ayurvedic medicine plant Withania somnifera with efficacy against cultured and xenografted human breast cancer cells. However, the mechanism underlying anticancer effect of WA is not fully understood. This study was undertaken to determine the role of Notch signaling in anticancer effects of WA using human breast cancer cells as a model. Notably, Notch signaling is often hyperactive in human breast cancers. Exposure of MDA-MB-231 and MCF-7 human breast cancer cells to pharmacological concentrations of WA resulted in cleavage (activation) of Notch2 as well as Notch4, which was accompanied by transcriptional activation of Notch as evidenced by RBP-Jk, HES-1A/B, and HEY-1 luciferase reporter assays. On the other hand, WA treatment caused a decrease in levels of both transmembrane and cleaved Notch1. The WA-mediated activation of Notch was associated with induction of γ-secretase complex components presenilin1 and/or nicastrin. Inhibition of MDA-MB-231 and MDA-MB-468 cell migration resulting from WA exposure was significantly augmented by knockdown of Notch2 as well as Notch4 protein. Activation of Notch2 was not observed in cells treated with withanone or withanolide A, which are structural analogs of WA. The results of this study indicate that WA treatment activates Notch2 and Notch4, which impede inhibitory effect of WA on breast cancer cell migration.
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Notch2 activation by benzyl isothiocyanate impedes its inhibitory effect on breast cancer cell migration
Breast Cancer Research and Treatment, 2012Co-Authors: Anuradha Sehrawat, Shivendra V SinghAbstract:Benzyl isothiocyanate (BITC) is a promising anticancer constituent of edible cruciferous vegetables with in vivo efficacy against chemically induced as well as oncogene-driven breast cancer in experimental rodents. However, the mechanism underlying anticancer effect of BITC is not fully understood. This study was undertaken to determine the role of Notch signaling in anticancer responses to BITC as this pathway is often hyperactive in human breast cancer. Exposure of MCF-7, MDA-MB-231, and SUM159 human breast cancer cells to pharmacologic concentrations of BITC (2.5 and 5 μM) resulted in cleavage (activation) of Notch1, Notch2, and Notch4, which was accompanied by induction of γ-secretase complex components Presenilin1 and/or Nicastrin. The BITC-mediated cleavage of Notch was associated with its transcriptional activation as revealed by RBP-Jk and Hes-1A/B luciferase reporter assays. Inhibition of cell migration or cell viability resulting from BITC exposure was not influenced by pharmacological suppression of Notch1 using a γ-secretase inhibitor or RNA interference of Notch1 as well as Notch4. On the other hand, the BITC-mediated inhibition of cell migration, but not cell viability, was significantly augmented by siRNA and shRNA knockdown of Notch2 protein. Furthermore, the BITC-mediated inhibition of MDA-MB-231 xenograft growth in vivo was associated with a significant increase in nuclear levels of cleaved Notch2 and Hes-1 proteins. In conclusion, the results of this study indicate that (a) BITC treatment activates Notch2 in cultured and xenografted human breast cancer cells, and (b) Notch2 activation impedes inhibitory effect of BITC on cell migration.
Joshua M Boucher - One of the best experts on this subject based on the ideXlab platform.
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through cyclin dependent kinase inhibitor 1b
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale:Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective:Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared with uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMCs. Methods and Results:In human primary VSMCs, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27kip1 were observed downstream of Jag-1/Notch2 signaling and were required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination, and prolonged half-life of p27kip1. Jag-1/Notch2 signaling robustly decreased S-phase kinase–associated protein, an F-box protein that degrades p27kip1 during G1. Overexpression of S-phase kinase–as...
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through p27kip1
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale: Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective: Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared to uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMC. Methods and Results: In human primary VSMC, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27 kip1 were observed downstream of Jag-1/Notch2 signaling, and required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination and prolonged half-life of p27 kip1 . Jag-1/Notch2 signaling robustly decreased S-phase kinase associated protein (Skp2), an F-box protein that degrades p27 kip1 during G1. Over expression of Skp2 prior to Notch activation by Jag-1 suppressed the induction of p27 kip1 . Additionally, increased Notch2 andp27 kip1 expression was co-localized to the non-proliferative zone of injured arteries as indicated by co-staining with proliferating cell nuclear antigen (PCNA), whereas Notch3 was expressed throughout normal and injured arteries, suggesting Notch2 may negatively regulate lesion formation. Conclusions: We propose a receptor specific function for Notch2 in regulating Jag-1-induced p27 kip1 expression and growth arrest in VSMC. During vascular remodeling, co-localization of Notch2 and p27 kip1 to the non-proliferating region supports a model where Notch2 activation may negatively regulate VSMC proliferation to lessen the severity of the lesion. Thus Notch2 is a potential target for control of VSMC hyperplasia.
Douglas W. Ball - One of the best experts on this subject based on the ideXlab platform.
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Notch1 and notch2 have opposite effects on embryonal brain tumor growth.
Cancer research, 2004Co-Authors: Xing Fan, Douglas W. Ball, Irina Mikolaenko, Ihab Elhassan, Yunyue Wang, Daniel J. Brat, Arie Perry, Charles G. EberhartAbstract:The role of Notch signaling in tumorigenesis can vary; Notch1 acts as an oncogene in some neoplasms, and a tumor suppressor in others. Here, we show that different Notch receptors can have opposite effects in a single tumor type. Expression of truncated, constitutively active Notch1 or Notch2 in embryonal brain tumor cell lines caused antagonistic effects on tumor growth. Cell proliferation, soft agar colony formation, and xenograft growth were all promoted by Notch2 and inhibited by Notch1. We also found that Notch2 receptor transcripts are highly expressed in progenitor cell-derived brain tumors such as medulloblastomas, whereas Notch1 is scarce or undetectable. This parallels normal cerebellar development, during which Notch2 is predominantly expressed in proliferating progenitors and Notch1 in postmitotic differentiating cells. Given the oncogenic effects of Notch2, we analyzed its gene dosage in 40 embryonal brain tumors, detecting an increased copy number in 15% of cases. Notch2 gene amplification was confirmed by fluorescence in situ hybridization in one case with extremely high Notch2 mRNA levels. In addition, expression of the Notch pathway target gene Hes1 in medulloblastomas was associated with significantly shorter patient survival (P = 0.01). Finally, pharmacological inhibition of Notch signaling suppresses growth of medulloblastoma cells. Our data indicate that Notch1 and Notch2 can have opposite effects on the growth of a single tumor type, and show that Notch2 can be overexpressed after gene amplification in human tumors.
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notch signaling induces rapid degradation of achaete scute homolog 1
Molecular and Cellular Biology, 2002Co-Authors: Virote Sriuranpong, Michael Borges, Barry D. Nelkin, Christopher L Strock, Eric K Nakakura, Neil D Watkins, Christine M Blaumueller, Douglas W. BallAbstract:In neural development, Notch signaling plays a key role in restricting neuronal differentiation, promoting the maintenance of progenitor cells. Classically, Notch signaling causes transactivation of Hairy-enhancer of Split (HES) genes which leads to transcriptional repression of neural determination and differentiation genes. We now report that in addition to its known transcriptional mechanism, Notch signaling also leads to rapid degradation of the basic helix-loop-helix (bHLH) transcription factor human achaete-scute homolog 1 (hASH1). Using recombinant adenoviruses expressing active Notch1 in small-cell lung cancer cells, we showed that the initial appearance of Notch1 coincided with the loss of hASH1 protein, preceding the full decay of hASH1 mRNA. Overexpression of HES1 alone was capable of down-regulating hASH1 mRNA but could not replicate the acute reduction of hASH1 protein induced by Notch1. When adenoviral hASH1 was coinfected with Notch1, we still observed a dramatic and abrupt loss of the exogenous hASH1 protein, despite high levels of ongoing hASH1 RNA expression. Notch1 treatment decreased the apparent half-life of the adenoviral hASH1 protein and increased the fraction of hASH1 which was polyubiquitinylated. The proteasome inhibitor MG132 reversed the Notch1-induced degradation. The Notch RAM domain was dispensable but a lack of the OPA and PEST domains inactivated this Notch1 action. Overexpression of the hASH1-dimerizing partner E12 could protect hASH1 from degradation. This novel function of activated Notch to rapidly degrade a class II bHLH protein may prove to be important in many contexts in development and in cancer.
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Notch Signaling Induces Cell Cycle Arrest in Small Cell Lung Cancer Cells
Cancer research, 2001Co-Authors: Virote Sriuranpong, Michael Borges, Rajani Ravi, Dagmar R. Arnold, Barry D. Nelkin, Stephen B. Baylin, Douglas W. BallAbstract:Among the various forms of human lung cancer, small cell lung cancer (SCLC) exhibits a characteristic neuroendocrine (NE) phenotype. Neural and NE differentiation in SCLC depend, in part, on the action of the basic-helix-loop-helix (bHLH) transcription factor human achaete-scute homologue-1 (hASH1). In nervous system development, the Notch signaling pathway is a critical negative regulator of bHLH factors, including hASH1, controlling cell fate commitment and differentiation. To characterize Notch pathway function in SCLC, we explored the consequences of constitutively active Notch signaling in cultured SCLC cells. Recombinant adenoviruses were used to overexpress active forms of Notch1, Notch2, or the Notch effector protein human hairy enhancer of split-1 (HES1) in DMS53 and NCI-H209 SCLC cells. Notch proteins, but not HES1 or control adenoviruses, caused a profound growth arrest, associated with a G 1 cell cycle block. We found up-regulation of p21 waf1/cip1 and p27 kip1 in concert with the cell cycle changes. Active Notch proteins also led to dramatic reduction in hASH1 expression, as well as marked activation of phosphorylated extracellular signal-regulated kinase (ERK)1 and ERK2, findings that have been shown to be associated with cell cycle arrest in SCLC cells. These data suggest that the previously described function of Notch proteins as proto-oncogenes is highly context-dependent. Notch activation, in the setting of a highly proliferative hASH1-dependent NE neoplasm, can be associated with growth arrest and apparent reduction in neoplastic potential.
Anne Harrington - One of the best experts on this subject based on the ideXlab platform.
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through cyclin dependent kinase inhibitor 1b
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale:Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective:Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared with uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMCs. Methods and Results:In human primary VSMCs, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27kip1 were observed downstream of Jag-1/Notch2 signaling and were required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination, and prolonged half-life of p27kip1. Jag-1/Notch2 signaling robustly decreased S-phase kinase–associated protein, an F-box protein that degrades p27kip1 during G1. Overexpression of S-phase kinase–as...
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a receptor specific function for notch2 in mediating vascular smooth muscle cell growth arrest through p27kip1
Circulation Research, 2013Co-Authors: Joshua M Boucher, Anne Harrington, Bahman Rostama, Volkhard Lindner, Lucy LiawAbstract:Rationale: Deregulated vascular smooth muscle cell (VSMC) proliferation contributes to multiple vascular pathologies, and Notch signaling regulates VSMC phenotype. Objective: Previous work focused on Notch1 and Notch3 in VSMC during vascular disease; however, the role of Notch2 is unknown. Because injured murine carotid arteries display increased Notch2 in VSMC as compared to uninjured arteries, we sought to understand the impact of Notch2 signaling in VSMC. Methods and Results: In human primary VSMC, Jagged-1 (Jag-1) significantly reduced proliferation through specific activation of Notch2. Increased levels of p27 kip1 were observed downstream of Jag-1/Notch2 signaling, and required for cell cycle exit. Jag-1 activation of Notch resulted in increased phosphorylation on serine 10, decreased ubiquitination and prolonged half-life of p27 kip1 . Jag-1/Notch2 signaling robustly decreased S-phase kinase associated protein (Skp2), an F-box protein that degrades p27 kip1 during G1. Over expression of Skp2 prior to Notch activation by Jag-1 suppressed the induction of p27 kip1 . Additionally, increased Notch2 andp27 kip1 expression was co-localized to the non-proliferative zone of injured arteries as indicated by co-staining with proliferating cell nuclear antigen (PCNA), whereas Notch3 was expressed throughout normal and injured arteries, suggesting Notch2 may negatively regulate lesion formation. Conclusions: We propose a receptor specific function for Notch2 in regulating Jag-1-induced p27 kip1 expression and growth arrest in VSMC. During vascular remodeling, co-localization of Notch2 and p27 kip1 to the non-proliferating region supports a model where Notch2 activation may negatively regulate VSMC proliferation to lessen the severity of the lesion. Thus Notch2 is a potential target for control of VSMC hyperplasia.
