Notch Signaling In B-ALL Reveals PLK1 As A Potential Therapeutic Target In B-ALL: PLK1-Selective Inhibitor Poloxin Modulates Cyclin B and P53 Pathways, Leading To Growth Arrest and Apoptosis

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2912-2912 ◽  
Author(s):  
Sankaranarayanan Kannan ◽  
Mandy A Hall ◽  
Leonard S Golfman ◽  
Patrick A Zweidler-McKay
Keyword(s):  
Cell Cycle ◽  
Notch Signaling ◽  
Growth Arrest ◽  
Selective Inhibitor ◽  
Cyclin B ◽  
Cell Type ◽  
Specific Effects ◽  
Cell Cycle Regulator ◽  
Cell Type Specific ◽  
Novel Therapeutic

Abstract Background Notch is a well-known oncogene in T-ALL, yet appears to have tumor suppressor effects in B-ALL. These cell type-specific effects of Notch signaling mirror consequences seen in early lymphocyte development and raises the question of how Notch leads to such divergent consequences in closely related cell types. In exploring these Notch mechanisms we discovered a B-ALL specific Notch-mediated reduction in the cell cycle regulator Polo-like kinase-1 (PLK1), revealing a novel targetable kinase in B-ALL. Approach To explore the consequences of Notch-mediated down regulation of cell cycle regulator kinase PLK1, we targeted PLK1 kinase function with the novel PLK1-selective inhibitor poloxin in human B-ALL lines. Results PLK1 is highly expressed in B-ALL verses normal tissues (panel A), correlates with cyclin B expression, is expressed >2-fold higher in B-ALL with t(1;19) than other B-ALL samples, and may predict response of ALL to methotrexate. In our panel of human B-ALL cell lines poloxin induced G2/M growth arrest and decreased cell number by >80% (panel B), and decreased survival in B-ALL cells (>75% AnnexinV+, panel C). PLK1 inhibition led to tumor suppressor p53 stabilization, revealing >5-fold increase in p53 protein levels following poloxin treatment in B-ALL (panel D). Mechanistically, PLK1 inhibition leads to both cytoplasmic re-localization of cyclin B, disrupting the CDC2-cyclinB complex, as well as phosphorylation of p53 at Ser20, which destabilizes p53-MDM2 interaction and thus accumulation of p53. Conclusions While exploring the mechanisms of cell type-specific effects of Notch signaling in ALL, we have found a novel therapeutic target, the cell cycle regulator PLK1. Our findings reveal a novel therapeutic approach whereby PLK1-selective inhibition via poloxin induces growth arrest and apoptosis in human B-ALL via consequences on cyclin B and p53 pathways. Disclosures: No relevant conflicts of interest to declare.

Notch/HES1 Signaling Stabilizes p53 Expression Via a Novel PARP1-Chfr-PLK1-Mediated Mechanism in B-ALL

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1292-1292
Author(s):  
Sankaranarayanan Kannan ◽  
Patrick A Zweidler-McKay
Keyword(s):  
Cell Cycle ◽  
T Cell ◽  
B Cell ◽  
Notch Signaling ◽  
Critical Role ◽  
Growth Arrest ◽  
Cyclin B ◽  
Cell Type ◽  
Cell Type Specific ◽  
Notch Activation

Abstract Abstract 1292 Background: Notch signaling contributes to T cell leukemogenesis. However, we have found that activation of Notch signaling in human B-ALL promotes growth arrest and apoptosis. These contrasting effects of Notch in B versus T cell ALL, mirror effects seen in early lymphocyte development. As the Notch receptors are common between T and B cells, we hypothesized that these differences rely on the cell-type specific downstream mechanisms. We previously reported a critical role for Notch/HES1-mediated activation of Poly ADP-Ribose Polymerase 1 (PARP1) function in this B cell specific mechanism. Approach: To explore the cell-type specific downstream mechanisms of Notch activation in B-ALL, we used cell fractionation, westerns and immunoprecipitation to identify cell cycle regulators which were altered by Notch activation via HES1 expression in human B-ALL lines. Results: Notch activation in a panel of human B-ALL lines led to consistent growth arrest and apoptosis. Indeed, ligands, activated receptors and the Notch target gene HES1 all induced these leukemia lihibiting effects in B-ALL but not T-ALL lines. In this study we report a mechanism whereby HES1-mediated activation of PARP1 leads to PARylation of the E3 ligase Checkpoint with FHA and RING finger (CHFR) (Panel A) which results in targeting and ubiquitination of the cell cycle regulator Polo-Like Kinase 1 (PLK1) (Panel B). PLK1 is highly expressed in B vs. T-ALL and plays a critical role in B cell growth and survival. Following Notch activation, loss of ubiquitionated PLK1 through proteosomal degradation leads to cell cycle arrest through two mechanisms, namely cytoplasmic relocalization of cyclin B, disrupting the CDC2-cyclinB complex, as well as phosphorylation of p53 at S20, which leads to decreased weakened p53-MDM2 interaction and accumulation of p53 (Panel C). siRNA to CHFR reveal that this mechanism is dependent on CHFR (Panel C). Importantly this mechanism is not seen in T-ALL cells as the activation of PARP1 by HES1 does not occur in T-ALL cells. Conclusions: Our findings reveal a novel molecular mechanism whereby Notch signaling induces disruption of the cell cycle in a cell type specific manner in B-ALL. Activation of PARP1, PARylation of CHFR, ubiquitination of PLK1 resulting in loss of nuclear cyclin B and accumulation of p53 demonstrates a series of events which can be initiated through activation of Notch in B-ALL. This mechanism reveals a potentially targetable approach to B-ALL. Disclosures: No relevant conflicts of interest to declare.

Cell Specific Consequences of Notch Signaling: PARP1/HES1 Interaction Reveals a Novel Tumor Suppressor Mechanism.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2388-2388
Author(s):  
Sankaranarayanan Kannan ◽  
Patrick A. Zweidler-McKay
Keyword(s):  
Tumor Suppressor ◽  
Notch Signaling ◽  
Lymphoblastic Leukemia ◽  
Growth Arrest ◽  
Protein Sequencing ◽  
The Novel ◽  
Cell Type ◽  
Adp Ribosylation ◽  
Suppressor Mechanism ◽  
Cell Type Specific

Abstract Abstract 2388 Poster Board II-365 The Notch signaling pathway is a critical regulator of cell fate determination and differentiation during development, which is highly cell type specific. Similarly, Notch signaling plays both oncogenic and tumor suppressor roles in a wide variety of malignancies, depending on cell type. In contrast to T cell acute lymphoblastic leukemia (T-ALL) where Notch activation promotes leukemogenesis, induction of Notch signaling in B-ALL leads to growth arrest and apoptosis. The Notch target gene Hairy/Enhancer of Split1 (HES1) is sufficient to reproduce this tumor suppressor phenotype in B-ALL, however the mechanism is not yet known. Here we report the novel finding that HES1 forms distinct complexes in B-ALL versus T-ALL. This suggests that HES1 interacting proteins may contribute to the cell-type specific consequences of Notch/HES1 signaling. During characterization of these complexes, we identified the novel interaction between HES1 and PARP1 through immunoprecipitation and MALDI-TOF protein sequencing. This interaction was dependent on the HES1 bHLH and Orange domains and PARP1 and HES1 co-localize to a genomic HES1 binding site by ChIP. This interaction both inhibits HES1 repressor function and induces PARP1 activation in B-ALL. HES1-induced PARP1 cleavage leads to enhanced poly ADP ribosylation of PARP1, consumption of NAD+, diminished ATP levels, and translocation of the Apoptosis Inducing Factor (AIF) from mitochondria to the nucleus, resulting in apoptosis in B-ALL, but not T-ALL. Importantly the potential therapeutic Notch agonist peptide “DSL” also induces cell-specific growth arrest and apoptosis (A+B), followed by poly-ADP ribosylation of PARP1 (C), and nuclear translocation of AIF in B-ALL but not T-ALL cells (D). These data reveal a novel interaction of HES1 and PARP1 in B-ALL which modulates the function of the HES1 transcriptional complex and signals through PARP1 to induce apoptosis. This novel tumor suppressor mechanism involving a Notch driven, cell-type specific pro-apoptotic pathway may lead to the development of Notch agonist-based cancer therapeutics. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Cell type-specific effects of asbestos on intracellular ROS levels, DNA oxidation and G1 cell cycle checkpoint

Oncogene ◽  
2004 ◽  
Vol 23 (54) ◽  
pp. 8834-8840 ◽  
Author(s):  
Pavel B Kopnin ◽  
Irina V Kravchenko ◽  
Vladimir A Furalyov ◽  
Lev N Pylev ◽  
Boris P Kopnin
Keyword(s):  
Cell Cycle ◽  
Dna Oxidation ◽  
Cell Cycle Checkpoint ◽  
Cell Type ◽  
Specific Effects ◽  
Intracellular Ros ◽  
Cycle Checkpoint ◽  
Cell Type Specific

scholarly journals Histone modifications form a cell-type-specific chromosomal bar code that persists through the cell cycle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
John A. Halsall ◽  
Simon Andrews ◽  
Felix Krueger ◽  
Charlotte E. Rutledge ◽  
Gabriella Ficz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Histone Modifications ◽  
Expression Patterns ◽  
Cell Types ◽  
Cell Type ◽  
Bar Code ◽  
Genes Encoding ◽  
Cell Type Specific ◽  
Rolling Windows

AbstractChromatin configuration influences gene expression in eukaryotes at multiple levels, from individual nucleosomes to chromatin domains several Mb long. Post-translational modifications (PTM) of core histones seem to be involved in chromatin structural transitions, but how remains unclear. To explore this, we used ChIP-seq and two cell types, HeLa and lymphoblastoid (LCL), to define how changes in chromatin packaging through the cell cycle influence the distributions of three transcription-associated histone modifications, H3K9ac, H3K4me3 and H3K27me3. We show that chromosome regions (bands) of 10–50 Mb, detectable by immunofluorescence microscopy of metaphase (M) chromosomes, are also present in G1 and G2. They comprise 1–5 Mb sub-bands that differ between HeLa and LCL but remain consistent through the cell cycle. The same sub-bands are defined by H3K9ac and H3K4me3, while H3K27me3 spreads more widely. We found little change between cell cycle phases, whether compared by 5 Kb rolling windows or when analysis was restricted to functional elements such as transcription start sites and topologically associating domains. Only a small number of genes showed cell-cycle related changes: at genes encoding proteins involved in mitosis, H3K9 became highly acetylated in G2M, possibly because of ongoing transcription. In conclusion, modified histone isoforms H3K9ac, H3K4me3 and H3K27me3 exhibit a characteristic genomic distribution at resolutions of 1 Mb and below that differs between HeLa and lymphoblastoid cells but remains remarkably consistent through the cell cycle. We suggest that this cell-type-specific chromosomal bar-code is part of a homeostatic mechanism by which cells retain their characteristic gene expression patterns, and hence their identity, through multiple mitoses.

scholarly journals Cell type-specific effects ofYersinia pseudotuberculosisvirulence effectors

2009 ◽  
Vol 11 (12) ◽  
pp. 1750-1767 ◽  
Author(s):  
Anna Fahlgren ◽  
Linda Westermark ◽  
Karen Akopyan ◽  
Maria Fällman
Keyword(s):  
Cell Type ◽  
Specific Effects ◽  
Cell Type Specific

scholarly journals Cell type-specific effects of isoflurane on two distinct afferent inputs to cortical layer 1

2020 ◽  
Author(s):  
Caitlin A. Murphy ◽  
Matthew I. Banks
Keyword(s):  
Ex Vivo ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Cellular Level ◽  
Cortical Layer ◽  
Cell Type ◽  
Specific Effects ◽  
Primary Mouse ◽  
Cell Type Specific ◽  
Synaptic Responses

ABSTRACTBackgroundWhile their behavioral effects are well-characterized, the mechanisms by which anaesthetics induce loss of consciousness are largely unknown. Anaesthetics may disrupt integration and propagation of information in corticothalamic networks. Recent studies have shown that isoflurane diminishes synaptic responses of thalamocortical (TC) and corticocortical (CC) afferents in a pathway-specific manner. However, whether the synaptic effects of isoflurane observed in extracellular recordings persist at the cellular level has yet to be explored.MethodsHere, we activate TC and CC layer 1 inputs in non-primary mouse neocortex in ex vivo brain slices and explore the degree to which isoflurane modulates synaptic responses in pyramidal cells and in two inhibitory cell populations, somatostatin-positive (SOM+) and parvalbumin-positive (PV+) interneurons.ResultsWe show that the effects of isoflurane on synaptic responses and intrinsic properties of these cells varies among cell type and by cortical layer. Layer 1 inputs to L4 pyramidal cells were suppressed by isoflurane at both TC and CC synapses, while those to L2/3 pyramidal cells and PV+ interneurons were not. TC inputs to SOM+ cells were rarely observed at all, while CC inputs to SOM+ interneurons were robustly suppressed by isoflurane.ConclusionsThese results suggest a mechanism by which isoflurane disrupts integration and propagation of thalamocortical and intracortical signals.

Cell type-specific effects of BDNF in modulating dendritic architecture of hippocampal neurons

2018 ◽  
Vol 223 (8) ◽  
pp. 3689-3709 ◽  
Author(s):  
Marta Zagrebelsky ◽  
N. Gödecke ◽  
A. Remus ◽  
Martin Korte
Keyword(s):  
Hippocampal Neurons ◽  
Cell Type ◽  
Specific Effects ◽  
Cell Type Specific

scholarly journals Cell type-specific effects of p27KIP1 loss on retinal development

2017 ◽  
Vol 12 (1) ◽  
Author(s):  
Mariko Ogawa ◽  
Fuminori Saitoh ◽  
Norihiro Sudou ◽  
Fumi Sato ◽  
Hiroki Fujieda
Keyword(s):  
Retinal Development ◽  
Cell Type ◽  
Specific Effects ◽  
Cell Type Specific
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