scholarly journals Loss of APC induces polyploidy as a result of a combination of defects in mitosis and apoptosis

2007 ◽  
Vol 176 (2) ◽  
pp. 183-195 ◽  
Author(s):  
Dina Dikovskaya ◽  
David Schiffmann ◽  
Ian P. Newton ◽  
Abigail Oakley ◽  
Karin Kroboth ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Chromosomal Instability ◽  
Suppressor Gene ◽  
Early Event ◽  
Mitotic Progression ◽  
Partial Loss ◽  
Checkpoint Proteins ◽  
Hct116 Cells

Mutations in the adenomatous polyposis coli (APC) tumor suppressor gene initiate a majority of colorectal cancers. Acquisition of chromosomal instability is an early event in these tumors. We provide evidence that the loss of APC leads to a partial loss of interkinetochore tension at metaphase and alters mitotic progression. Furthermore, we show that inhibition of APC in U2OS cells compromises the mitotic spindle checkpoint. This is accompanied by a decrease in the association of the checkpoint proteins Bub1 and BubR1 with kinetochores. Additionally, APC depletion reduced apoptosis. As expected from this combination of defects, tetraploidy and polyploidy are consequences of APC inhibition in vitro and in vivo. The removal of APC produced the same defects in HCT116 cells that have constitutively active β-catenin. These data show that the loss of APC immediately induces chromosomal instability as a result of a combination of mitotic and apoptotic defects. We suggest that these defects amplify each other to increase the incidence of tetra- and polyploidy in early stages of tumorigenesis.

scholarly journals HURP controls spindle dynamics to promote proper interkinetochore tension and efficient kinetochore capture

2006 ◽  
Vol 173 (6) ◽  
pp. 879-891 ◽  
Author(s):  
Jim Wong ◽  
Guowei Fang
Keyword(s):  
Mitotic Spindle ◽  
Metaphase Plate ◽  
Mitotic Progression ◽  
Specific Mechanism ◽  
Microtubule Polymerization ◽  
Chromosome Congression ◽  
Spindle Dynamics ◽  
Spindle Stability

Through a functional genomic screen for mitotic regulators, we identified hepatoma up-regulated protein (HURP) as a protein that is required for chromosome congression and alignment. In HURP-depleted cells, the persistence of unaligned chromosomes and the reduction of tension across sister kinetochores on aligned chromosomes resulted in the activation of the spindle checkpoint. Although these defects transiently delayed mitotic progression, HeLa cells initiated anaphase without resolution of these deficiencies. This bypass of the checkpoint arrest provides a tumor-specific mechanism for chromosome missegregation and genomic instability. Mechanistically, HURP colocalized with the mitotic spindle in a concentration gradient increasing toward the chromosomes. HURP binds directly to microtubules in vitro and enhances their polymerization. In vivo, HURP stabilizes mitotic microtubules, promotes microtubule polymerization and bipolar spindle formation, and decreases the turnover rate of the mitotic spindle. Thus, HURP controls spindle stability and dynamics to achieve efficient kinetochore capture at prometaphase, timely chromosome congression to the metaphase plate, and proper interkinetochore tension for anaphase initiation.

scholarly journals Therapeutic Application of Brain-Specific Angiogenesis Inhibitor 1 for Cancer Therapy

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3562
Author(s):  
Mitra Nair ◽  
Chelsea Bolyard ◽  
Tae Jin Lee ◽  
Balveen Kaur ◽  
Ji Young Yoo
Keyword(s):  
Angiogenesis Inhibitor ◽  
Suppressor Gene ◽  
Chemotherapeutic Agents ◽  
Tumor Models ◽  
In Vivo Models ◽  
Herpes Simplex Viruses ◽  
Multiple Tumor ◽  
And Function

Brain-specific angiogenesis inhibitor 1 (BAI1/ADGRB1) is an adhesion G protein-coupled receptor that has been found to play key roles in phagocytosis, inflammation, synaptogenesis, the inhibition of angiogenesis, and myoblast fusion. As the name suggests, it is primarily expressed in the brain, with a high expression in the normal adult and developing brain. Additionally, its expression is reduced in brain cancers, such as glioblastoma (GBM) and peripheral cancers, suggesting that BAI1 is a tumor suppressor gene. Several investigators have demonstrated that the restoration of BAI1 expression in cancer cells results in reduced tumor growth and angiogenesis. Its expression has also been shown to be inversely correlated with tumor progression, neovascularization, and peri-tumoral brain edema. One method of restoring BAI1 expression is by using oncolytic virus (OV) therapy, a strategy which has been tested in various tumor models. Oncolytic herpes simplex viruses engineered to express the secreted fragment of BAI1, called Vasculostatin (Vstat120), have shown potent anti-tumor and anti-angiogenic effects in multiple tumor models. Combining Vstat120-expressing oHSVs with other chemotherapeutic agents has also shown to increase the overall anti-tumor efficacy in both in vitro and in vivo models. In the current review, we describe the structure and function of BAI1 and summarize its application in the context of cancer treatment.

scholarly journals Astrocytes derived from p53-deficient mice provide a multistep in vitro model for development of malignant gliomas.

1995 ◽  
Vol 15 (8) ◽  
pp. 4249-4259 ◽  
Author(s):  
A M Yahanda ◽  
J M Bruner ◽  
L A Donehower ◽  
R S Morrison
Keyword(s):  
Genomic Instability ◽  
Malignant Transformation ◽  
Nude Mice ◽  
Malignant Gliomas ◽  
Early Event ◽  
Wild Type ◽  
Early Passage ◽  
Wild Type P53

Loss or mutation of p53 is thought to be an early event in the malignant transformation of many human astrocytic tumors. To better understand the role of p53 in their growth and transformation, we developed a model employing cultured neonatal astrocytes derived from mice deficient in one (p53 +/-) or both (p53 -/-) p53 alleles, comparing them with wild-type (p53 +/+) cells. Studies of in vitro and in vivo growth and transformation were performed, and flow cytometry and karyotyping were used to correlate changes in growth with genomic instability. Early-passage (EP) p53 -/- astrocytes achieved higher saturation densities and had more rapid growth than EP p53 +/- and +/+ cells. The EP p53 -/- cells were not transformed, as they were unable to grow in serum-free medium or in nude mice. With continued passaging, p53 -/- cells exhibited a multistep progression to a transformed phenotype. Late-passage p53 -/- cells achieved saturation densities 50 times higher than those of p53 +/+ cells and formed large, well-vascularized tumors in nude mice. p53 +/- astrocytes exhibited early loss of the remaining wild-type p53 allele and then evolved in a manner phenotypically similar to p53 -/- astrocytes. In marked contrast, astrocytes retaining both wild-type p53 alleles never exhibited a transformed phenotype and usually senesced after 7 to 10 passages. Dramatic alterations in ploidy and karyotype occurred and were restricted to cells deficient in wild-type p53 following repeated passaging. The results of these studies suggest that loss of wild-type p53 function promotes genomic instability, accelerated growth, and malignant transformation in astrocytes.

scholarly journals RanBP2 and SENP3 Function in a Mitotic SUMO2/3 Conjugation-Deconjugation Cycle on Borealin

2009 ◽  
Vol 20 (1) ◽  
pp. 410-418 ◽  
Author(s):  
Ulf R. Klein ◽  
Markus Haindl ◽  
Erich A. Nigg ◽  
Stefan Muller
Keyword(s):  
Mammalian Cells ◽  
Spindle Assembly Checkpoint ◽  
Critical Role ◽  
Specific Interaction ◽  
Regulatory Function ◽  
Mitotic Progression ◽  
Chromosome Congression ◽  
Chromosomal Passenger

The ubiquitin-like SUMO system controls cellular key functions, and several lines of evidence point to a critical role of SUMO for mitotic progression. However, in mammalian cells mitotic substrates of sumoylation and the regulatory components involved are not well defined. Here, we identify Borealin, a component of the chromosomal passenger complex (CPC), as a mitotic target of SUMO. The CPC, which additionally comprises INCENP, Survivin, and Aurora B, regulates key mitotic events, including chromosome congression, the spindle assembly checkpoint, and cytokinesis. We show that Borealin is preferentially modified by SUMO2/3 and demonstrate that the modification is dynamically regulated during mitotic progression, peaking in early mitosis. Intriguingly, the SUMO ligase RanBP2 interacts with the CPC, stimulates SUMO modification of Borealin in vitro, and is required for its modification in vivo. Moreover, the SUMO isopeptidase SENP3 is a specific interaction partner of Borealin and catalyzes the removal of SUMO2/3 from Borealin. These data thus delineate a mitotic SUMO2/3 conjugation–deconjugation cycle of Borealin and further assign a regulatory function of RanBP2 and SENP3 in the mitotic SUMO pathway.

scholarly journals CSPα reduces aggregates and rescues striatal dopamine release in αsynuclein transgenic mice

2020 ◽  
Author(s):  
L Caló ◽  
E Hidari ◽  
M Wegrzynowicz ◽  
JW Dalley ◽  
BL Schneider ◽  
...  
Keyword(s):  
Dopamine Release ◽  
Early Stage ◽  
Synaptic Function ◽  
Snare Complex ◽  
Early Event ◽  
Vesicle Recycling ◽  
Cysteine String Protein ◽  
And Function

AbstractαSynuclein aggregation at the synapse is an early event in Parkinson’s disease and is associated with impaired striatal synaptic function and dopaminergic neuronal death. The cysteine string protein (CSPα) and αsynuclein have partially overlapping roles in maintaining synaptic function and mutations in each cause neurodegenerative diseases. CSPα is a member of the DNAJ/HSP40 family of co-chaperones and like αsynuclein, chaperones the SNARE complex assembly and neurotransmitter release. αSynuclein can rescue neurodegeneration in CSPαKO mice. However, whether αsynuclein aggregation alters CSPα expression and function is unknown. Here we show that αsynuclein aggregation at the synapse induces a decrease in synaptic CSPα and a reduction in the complexes that CSPα forms with HSC70 and STGa. We further show that viral delivery of CSPα rescues in vitro the impaired vesicle recycling in PC12 cells with αsynuclein aggregates and in vivo reduces synaptic αsynuclein aggregates restoring normal dopamine release in 1-120hαsyn mice. These novel findings reveal a mechanism by which αsynuclein aggregation alters CSPα at the synapse, and show that CSPα rescues αsynuclein aggregation-related phenotype in 1-120hαsyn mice similar to the effect of αsynuclein in CSPαKO mice. These results implicate CSPα as a potential therapeutic target for the treatment of early-stage PD.

scholarly journals Transcriptional role of p53 in interferon-mediated antiviral immunity

2008 ◽  
Vol 205 (8) ◽  
pp. 1929-1938 ◽  
Author(s):  
César Muñoz-Fontela ◽  
Salvador Macip ◽  
Luis Martínez-Sobrido ◽  
Lauren Brown ◽  
Joseph Ashour ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Viral Replication ◽  
Viral Infections ◽  
Suppressor Gene ◽  
Central Component ◽  
Type I ◽  
Infected Cells

Tumor suppressor p53 is activated by several stimuli, including DNA damage and oncogenic stress. Previous studies (Takaoka, A., S. Hayakawa, H. Yanai, D. Stoiber, H. Negishi, H. Kikuchi, S. Sasaki, K. Imai, T. Shibue, K. Honda, and T. Taniguchi. 2003. Nature. 424:516–523) have shown that p53 is also induced in response to viral infections as a downstream transcriptional target of type I interferon (IFN) signaling. Moreover, many viruses, including SV40, human papillomavirus, Kaposi's sarcoma herpesvirus, adenoviruses, and even RNA viruses such as polioviruses, have evolved mechanisms designated to abrogate p53 responses. We describe a novel p53 function in the activation of the IFN pathway. We observed that infected mouse and human cells with functional p53 exhibited markedly decreased viral replication early after infection. This early inhibition of viral replication was mediated both in vitro and in vivo by a p53-dependent enhancement of IFN signaling, specifically the induction of genes containing IFN-stimulated response elements. Of note, p53 also contributed to an increase in IFN release from infected cells. We established that this p53-dependent enhancement of IFN signaling is dependent to a great extent on the ability of p53 to activate the transcription of IFN regulatory factor 9, a central component of the IFN-stimulated gene factor 3 complex. Our results demonstrate that p53 contributes to innate immunity by enhancing IFN-dependent antiviral activity independent of its functions as a proapoptotic and tumor suppressor gene.

Xanthine oxidase/dehydrogenase in mammary gland of mouse: relationship to mammogenesis and lactogenesis in vivo and in vitro

1991 ◽  
Vol 58 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Thomas J. Hayden ◽  
Denise Brennan ◽  
Katherine Quirke ◽  
Paddie Murphy
Keyword(s):  
Mammary Gland ◽  
Xanthine Oxidase ◽  
Post Partum ◽  
Explant Culture ◽  
Placental Lactogen ◽  
Early Event ◽  
Histological Differentiation ◽  
Variant Enzyme

SummaryXanthine oxidase/dehydrogenase (XO/XDH) increases at mid gestation in mammary gland but not in liver of the mouse and remains elevated until the pups are weaned at 20 d post partum. The increase in enzyme activity is due neither to alteration in activators or inhibitors nor to a production of a variant enzyme with altered catalytic properties. The increase is preceded in vivo by a surge of prolactin-like activity (placental lactogen) in plasma, and prolactin is required for induction of XO/XDH in explant culture in vitro. Induction of XO/XDH in vivo and in vitro precedes the full histological differentiation of the gland. In addition, induction of XO/XDH in vitro occurs more rapidly and at lower concentrations of prolactin than does histological differentiation. Thus although XO/XDH is present in milk, increased XO/XDH activity is an early event in mammogenesis in vivo and in vitro rather than a terminal component of differentiation.

scholarly journals The Human Candidate Tumor Suppressor Gene HIC1 Recruits CtBP through a Degenerate GLDLSKK Motif

2002 ◽  
Vol 22 (13) ◽  
pp. 4890-4901 ◽  
Author(s):  
Sophie Deltour ◽  
Sébastien Pinte ◽  
Cateline Guerardel ◽  
Bohdan Wasylyk ◽  
Dominique Leprince
Keyword(s):  
Binding Site ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Trichostatin A ◽  
Suppressor Gene ◽  
Close Relative ◽  
Consensus Binding Site ◽  
Candidate Tumor Suppressor Gene

ABSTRACT HIC1 (hypermethylated in cancer) and its close relative HRG22 (HIC1-related gene on chromosome 22) encode transcriptional repressors with five C2H2 zinc fingers and an N-terminal BTB/POZ autonomous transcriptional repression domain that is unable to recruit histone deacetylases (HDACs). Alignment of the HIC1 and HRG22 proteins from various species highlighted a perfectly conserved GLDLSKK/R motif highly related to the consensus CtBP interaction motif (PXDLSXK/R), except for the replacement of the virtually invariant proline by a glycine. HIC1 strongly interacts with mCtBP1 both in vivo and in vitro through this conserved GLDLSKK motif, thus extending the CtBP consensus binding site. The BTB/POZ domain does not interact with mCtBP1, but the dimerization of HIC1 through this domain is required for the interaction with mCtBP1. When tethered to DNA by fusion with the Gal4 DNA-binding domain, the HIC1 central region represses transcription through interactions with CtBP in a trichostatin A-sensitive manner. In conclusion, our results demonstrate that HIC1 mediates transcriptional repression by both HDAC-independent and HDAC-dependent mechanisms and show that CtBP is a HIC1 corepressor that is recruited via a variant binding site.

Neural regulation of intestinal smooth muscle growth in vitro

2000 ◽  
Vol 279 (3) ◽  
pp. G511-G519 ◽  
Author(s):  
M. G. Blennerhassett ◽  
S. Lourenssen
Keyword(s):  
Smooth Muscle ◽  
Sympathetic Neurons ◽  
Muscle Growth ◽  
Scorpion Venom ◽  
Enteric Neurons ◽  
Intestinal Smooth Muscle ◽  
Early Event ◽  
Thymidine Uptake

The loss of intrinsic neurons is an early event in inflammation of the rat intestine that precedes the growth of intestinal smooth muscle cells (ISMC). To study this relationship, we cocultured ISMC and myenteric plexus neurons from the rat small intestine and examined the effect of scorpion venom, a selective neurotoxin, on ISMC growth. By 5 days after neuronal ablation, ISMC number increased to 141 ± 13% ( n = 6) and the uptake of [3H]thymidine in response to mitogenic stimulation was nearly doubled. Atropine caused a dose-dependent increase in [3H]thymidine uptake in cocultures, suggesting the involvement of neural stimulation of cholinergic receptors in regulation of ISMC growth. In contrast, coculture of ISMC with sympathetic neurons increased [3H]thymidine uptake by 45–80%, which was sensitive to propranolol (30 μM) and was lost when the neurons were separated from ISMC by a permeable filter. Western blotting showed that coculture with myenteric neurons increased α-smooth muscle-specific actin nearly threefold to a level close to ISMC in vivo. Therefore, factors derived from enteric neurons maintain the phenotype of ISMC through suppression of the growth response, whereas catecholamines released by neurons extrinsic to the intestine may stimulate their growth. Thus inflammation-induced damage to intestinal innervation may initiate or modulate ISMC hyperplasia.

Rhinovirus stimulation of interleukin-8 in vivo and in vitro: role of NF-κB

1997 ◽  
Vol 273 (4) ◽  
pp. L814-L824 ◽  
Author(s):  
Zhou Zhu ◽  
Weiliang Tang ◽  
Jack M. Gwaltney ◽  
Yang Wu ◽  
Jack A. Elias
Keyword(s):  
Transcriptional Activation ◽  
Neutrophil Infiltration ◽  
Binding Activity ◽  
Early Event ◽  
Mrna Accumulation ◽  
Additional Increase ◽  
Dna Binding Activity ◽  
Infected Cells

Neutrophil infiltration is a well-documented early event in the pathogenesis of rhinovirus (RV) infections. To further understand the mechanisms responsible for this neutrophilia, we determined whether interleukin (IL)-8 was present at sites of experimental RV infection in vivo and characterized the mechanism(s) by which RV stimulates IL-8 production in vitro. IL-8 was readily detectable in the nasal washings of all normal volunteers and did not increase with sham nasal inoculation. In contrast, RV infection caused a significant additional increase in nasal IL-8, the levels of which peaked 48–72 h after virus inoculation. RV was a potent stimulator of IL-8 protein production by A549 epithelial-like cells, MRC-5 fibroblasts, and normal human bronchial epithelial cells in vitro. This induction was associated with a significant increase in IL-8 mRNA accumulation and gene transcription. RV also stimulated IL-8 promoter-driven luciferase activity. This stimulation was significantly decreased by mutation of the nuclear factor (NF)-IL-6 site and was completely abrogated by mutation of the NF-κB site in this promoter. In addition, NF-κB-DNA binding activity was rapidly induced in RV-infected cells. This inducible binding was made up of p65 and, to a lesser extent, p50 NF-κB moieties. These studies demonstrate that IL-8 is present in normal nasal secretions and that the levels of IL-8 are further increased after RV infection. They also demonstrate that RVs are potent stimulators of IL-8 production and that this induction is mediated, at least in part, by an NF-κB-dependent transcriptional activation pathway. IL-8 may contribute to the pathogenesis of RV infection, and NF-κB activation may be a central event in RV-induced pathologies.

Sign in / Sign up

Export Citation Format

Share Document