scholarly journals SART1 localizes to spindle poles forming a SART1 cap and promotes centrosome and spindle assembly

2021 ◽  
Author(s):  
Hideki Yokoyama ◽  
Kaoru Takizawa ◽  
Jian Ma ◽  
Daniel Moreno-Andrés ◽  
Wolfram Antonin ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Physiological Function ◽  
Spindle Assembly ◽  
Scaffold Protein ◽  
Human Cells ◽  
Dependent Manner ◽  
Normal Cells ◽  
Spindle Poles ◽  
Egg Extracts ◽  
Centrosomal Proteins

Abstract SART1 is overexpressed in various cancers. However, its physiological function and cancer relevance remains elusive. Here we identify SART1 as a mitotic-specific and Ran-regulated microtubule-associated protein. SART1 downregulation in human cells as well as its depletion from frog egg extracts disrupts spindle assembly. While SART1 is nuclear in interphase, it localizes during mitosis to spindle poles in a microtubule-dependent manner. SART1 accumulates close to centrosomes forming a half circle which we designate as SART1 cap. Immunoprecipitation of SART1 identifies the centrosome scaffold protein Cep192 as an interaction partner. Accordingly, Cep192 downregulation abolishes SART1 localization to spindle poles, and SART1 downregulation displaces centrosomal proteins like Ninein from centrosomes, but does not affect γ-tubulin localization. Furthermore, SART1 downregulation selectively kills cancer cells and prevents normal cells from oncogenic transformation. Our data unravel a novel function of SART1 for centrosome organization and spotlight SRAT1 as a potential target for anticancer therapies.

scholarly journals The centriolar satellite protein SSX2IP promotes centrosome maturation

2013 ◽  
Vol 202 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Felix Bärenz ◽  
Daigo Inoue ◽  
Hideki Yokoyama ◽  
Justus Tegha-Dunghu ◽  
Stephanie Freiss ◽  
...  
Keyword(s):  
Somatic Cells ◽  
Spindle Assembly ◽  
Xenopus Laevis Oocyte ◽  
Dependent Manner ◽  
Vertebrate Development ◽  
Spindle Poles ◽  
M Phase ◽  
Egg Extracts ◽  
Ring Complex ◽  
Pericentriolar Material

Meiotic maturation in vertebrate oocytes is an excellent model system for microtubule reorganization during M-phase spindle assembly. Here, we surveyed changes in the pattern of microtubule-interacting proteins upon Xenopus laevis oocyte maturation by quantitative proteomics. We identified the synovial sarcoma X breakpoint protein (SSX2IP) as a novel spindle protein. Using X. laevis egg extracts, we show that SSX2IP accumulated at spindle poles in a Dynein-dependent manner and interacted with the γ-tubulin ring complex (γ-TuRC) and the centriolar satellite protein PCM-1. Immunodepletion of SSX2IP impeded γ-TuRC loading onto centrosomes. This led to reduced microtubule nucleation and spindle assembly failure. In rapidly dividing blastomeres of medaka (Oryzias latipes) and in somatic cells, SSX2IP knockdown caused fragmentation of pericentriolar material and chromosome segregation errors. We characterize SSX2IP as a novel centrosome maturation and maintenance factor that is expressed at the onset of vertebrate development. It preserves centrosome integrity and faithful mitosis during the rapid cleavage division of blastomeres and in somatic cells.

scholarly journals The wages of CIN

2008 ◽  
Vol 180 (4) ◽  
pp. 661-663 ◽  
Author(s):  
Karen W. Yuen ◽  
Arshad Desai
Keyword(s):  
Cancer Cells ◽  
Solid Tumors ◽  
Chromosomal Instability ◽  
Chromosome Instability ◽  
Spindle Checkpoint ◽  
Human Cells ◽  
Normal Cells ◽  
Chromosome Missegregation ◽  
Cell Biol ◽  
The Relationship

Aneuploidy and chromosome instability (CIN) are hallmarks of the majority of solid tumors, but the relationship between them is not well understood. In this issue, Thompson and Compton (Thompson, S.L., and D.A. Compton. 2008. Examining the link between chromosomal instability and aneuploidy in human cells. J. Cell. Biol. 180:665–672) investigate the mechanism of CIN in cancer cells and find that CIN arises primarily from defective kinetochore–spindle attachments that evade detection by the spindle checkpoint and persist into anaphase. They also explore the consequences of artificially elevating chromosome missegregation in otherwise karyotypically normal cells. Their finding that induced aneuploidy is rapidly selected against suggests that the persistence of aneuploid cells in tumors requires not only chromosome missegregation but also additional, as yet poorly defined events.

scholarly journals Bimodal Interaction of Mammalian Polo-Like Kinase 1 and a Centrosomal Scaffold, Cep192, in the Regulation of Bipolar Spindle Formation

2015 ◽  
Vol 35 (15) ◽  
pp. 2626-2640 ◽  
Author(s):  
Lingjun Meng ◽  
Jung-Eun Park ◽  
Tae-Sung Kim ◽  
Eun Hye Lee ◽  
Suk-Youl Park ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Spindle Assembly ◽  
Human Cells ◽  
Mitotic Progression ◽  
Spindle Formation ◽  
Content Type ◽  
Bipolar Spindle ◽  
Egg Extracts ◽  
Cultured Human Cells ◽  
Bipolar Spindles

Serving as microtubule-organizing centers, centrosomes play a key role in forming bipolar spindles. The mechanism of how centrosomes promote bipolar spindle assembly in various organisms remains largely unknown. A recent study withXenopus laevisegg extracts suggested that the Plk1 ortholog Plx1 interacts with the phospho-T46 (p-T46) motif ofXenopusCep192 (xCep192) to form an xCep192-mediated xAurA-Plx1 cascade that is critical for bipolar spindle formation. Here, we demonstrated that in cultured human cells, Cep192 recruits AurA and Plk1 in a cooperative manner, and this event is important for the reciprocal activation of AurA and Plk1. Strikingly, Plk1 interacted with Cep192 through either the p-T44 (analogous toXenopusp-T46) or the newly identified p-S995 motif via its C-terminal noncatalytic polo-box domain. The interaction between Plk1 and the p-T44 motif was prevalent in the presence of Cep192-bound AurA, whereas the interaction of Plk1 with the p-T995 motif was preferred in the absence of AurA binding. Notably, the loss of p-T44- and p-S995-dependent Cep192-Plk1 interactions induced an additive defect in recruiting Plk1 and γ-tubulin to centrosomes, which ultimately led to a failure in proper bipolar spindle formation and mitotic progression. Thus, we propose that Plk1 promotes centrosome-based bipolar spindle formation by forming two functionally nonredundant complexes with Cep192.

scholarly journals RanGTP induces an effector gradient of XCTK2 and importin α/β for spindle microtubule cross-linking

2019 ◽  
Author(s):  
Stephanie C. Ems-McClung ◽  
Mackenzie Emch ◽  
Stephanie Zhang ◽  
Serena Mahnoor ◽  
Lesley N. Weaver ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Tail Domain ◽  
Inhibitory Effects ◽  
Cross Link ◽  
Spindle Microtubule ◽  
Spindle Poles ◽  
Importin Α ◽  
Combined Actions

AbstractHigh RanGTP around chromatin is important for governing spindle assembly during meiosis and mitosis by releasing the inhibitory effects of importin α/β. Here we examine how the Ran gradient regulates Kinesin-14 function to control spindle organization. We show that Xenopus Kinesin-14, XCTK2, and importin α/β form an effector gradient, which is highest at the poles that diminishes toward the chromatin and is inverse of the RanGTP gradient. Importin α/β preferentially inhibit XCTK2 anti-parallel microtubule cross-linking and sliding by decreasing the microtubule affinity of the XCTK2 tail domain. This change in microtubule affinity enables RanGTP to target endogenous XCTK2 to the spindle. We propose that these combined actions of the Ran pathway are critical to promote Kinesin-14 parallel microtubule cross-linking at the spindle poles to cluster centrosomes in cancer cells. Furthermore, our work illustrates that RanGTP regulation in the spindle is not simply a switch, but rather generates effector gradients where RanGTP gradually tunes the activities of spindle assembly factors.SummaryEms-McClung et al. visualize a RanGTP effector gradient of association between XCTK2 and importin α/β in the spindle. The importins preferentially inhibit XCTK2-mediate anti-parallel microtubule cross-linking and sliding, which allows XCTK2 to cross-link parallel microtubules and help focus spindle poles.

scholarly journals Spindle Assembly in Xenopus Egg Extracts: Respective Roles of Centrosomes and Microtubule Self-Organization

1997 ◽  
Vol 138 (3) ◽  
pp. 615-628 ◽  
Author(s):  
Rebecca Heald ◽  
Régis Tournebize ◽  
Anja Habermann ◽  
Eric Karsenti ◽  
Anthony Hyman
Keyword(s):  
Spindle Assembly ◽  
Cytoplasmic Dynein ◽  
Microtubule Organization ◽  
Spindle Poles ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Sperm Nuclei ◽  
Xenopus Egg Extracts ◽  
Microtubule Stabilizing Agent ◽  
Mitotic Chromatin

In Xenopus egg extracts, spindles assembled around sperm nuclei contain a centrosome at each pole, while those assembled around chromatin beads do not. Poles can also form in the absence of chromatin, after addition of a microtubule stabilizing agent to extracts. Using this system, we have asked (a) how are spindle poles formed, and (b) how does the nucleation and organization of microtubules by centrosomes influence spindle assembly? We have found that poles are morphologically similar regardless of their origin. In all cases, microtubule organization into poles requires minus end–directed translocation of microtubules by cytoplasmic dynein, which tethers centrosomes to spindle poles. However, in the absence of pole formation, microtubules are still sorted into an antiparallel array around mitotic chromatin. Therefore, other activities in addition to dynein must contribute to the polarized orientation of microtubules in spindles. When centrosomes are present, they provide dominant sites for pole formation. Thus, in Xenopus egg extracts, centrosomes are not necessarily required for spindle assembly but can regulate the organization of microtubules into a bipolar array.

scholarly journals Cell autonomous angiotensin II signaling controls the pleiotropic functions of oncogenic K-Ras

2020 ◽  
pp. jbc.RA120.015188
Author(s):  
Daniela Volonte ◽  
Morgan Sedorovitz ◽  
Victoria E. Cespedes ◽  
Maria L. Beecher ◽  
Ferruccio Galbiati
Keyword(s):  
Lung Cancer ◽  
Angiotensin Ii ◽  
Cancer Cells ◽  
Lung Tumor ◽  
Tumor Formation ◽  
Lung Cancer Cells ◽  
Human Lung Cancer ◽  
Dependent Manner ◽  
Ang Ii ◽  
Normal Cells

Oncogenic K-Ras (K-RasG12V) promotes senescence in normal cells but fuels transformation of cancer cells after the senescence barrier is bypassed. The mechanisms regulating this pleiotropic function of K-Ras remain to be fully established and bear high pathological significance. We find that K-RasG12V activates the angiotensinogen (AGT) gene promoter and promotes AGT protein expression in a Kruppel Like Factor 6 (KLF6)-dependent manner in normal cells. We show that AGT is then converted to angiotensin II (Ang II) in a cell-autonomous manner by cellular proteases. We show that blockade of the Ang II receptor type 1 (AT1-R) in normal cells inhibits oncogene-induced senescence (OIS). We provide evidence that the oncogenic K-Ras-induced synthesis of Ang II and AT1-R activation promote senescence through caveolin-1-dependent and NOX2-mediated oxidative stress. Interestingly, we find that expression of AGT remains elevated in lung cancer cells but in a KLF6-independent and High Mobility Group AT-Hook 1 (HMGA1)-dependent manner. We show that Ang II-mediated activation of the AT1-R promotes cell proliferation and anchorage-independent growth of lung cancer cells through a STAT3-dependent pathway. Finally, we find that expression of AGT is elevated in lung tumors of K-RasLA2-G12D mice, a mouse model of lung cancer, and human lung cancer. Treatment with the AT1-R antagonist losartan inhibits lung tumor formation in K-RasLA2-G12D mice. Together, our data provide evidence of the existence of a novel cell-autonomous and pleiotropic Ang II-dependent signaling pathway through which oncogenic K-Ras promotes OIS in normal cells while fueling transformation in cancer cells.

scholarly journals Dynamic Changes of pStat3 are Involved in Meiotic Spindle Assembly in Mouse Oocytes

2020 ◽  
Author(s):  
Seiki Haraguchi ◽  
Mitsumi Ikeda ◽  
Satoshi Akagi ◽  
Yuji Hirao
Keyword(s):  
Oocyte Maturation ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Dual Function ◽  
Dependent Manner ◽  
Vitro Fertilization ◽  
Spindle Poles ◽  
Activation Of Transcription ◽  
Transcription 3

The signal transducer and activator of transcription 3 (Stat3) is activated in response to the phosphorylation of Y705 (pStat3) and has the dual function of signal transduction and activation of transcription. Our previous study suggested that pStat3 is functional during oocyte maturation when transcription is silenced. Therefore, we speculated that pStat3 may have another function. Immunocytochemical analysis revealed that pStat3 emerges at the microtubule asters and spindle and then localizes at the spindle poles concomitant with a Pericentrin during mouse oocyte maturation. When we examined conditionally knocked out Stat3−/− oocytes, we detected Stat3 and pStat3 proteins. The localization of the pStat3 was the same as that of Stat3+/+ oocytes, and the oocyte maturation proceeded normally, suggesting that pStat3 was still functioning. The oocytes were treated either with the Stat3 specific inhibitors, Stattic and BP-1-102, or anti-pStat3 antibody injection. This caused significant abnormal spindle assembly and chromosome mis-location in a dose-dependent manner, in which the pStat3 was either negative or localized improperly. Moreover, development of pre-implantation stage embryos derived from inhibitor-treated oocytes was also hampered significantly after in vitro fertilization. These findings indicate a novel function of pStat3 involved in spindle assembly.

Innovative dual system for selective eradication of cancer cells using exosomes carrying natural bacterial toxin-antitoxin (TA).

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e14635-e14635
Author(s):  
Shiran Shapira ◽  
Ilana Boustanai ◽  
Dina Kazanov ◽  
Ahmad Fokra ◽  
Ezra Bernstein ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Xenograft Model ◽  
Genetic Alterations ◽  
Bacterial Toxin ◽  
Genetic Profile ◽  
Dependent Manner ◽  
Normal Cells ◽  
Responsive Element

e14635 Background: Inactivation of P53 and activation of ras are frequent genetic alterations in cancer. We have shown in vitro and in vivo, that the TA system can selectively and effectively eradicate RAS-mutated cancer cells. Aim: Selective killing of cancer cells while sparing the normal cells based on tumor genetic signature. Methods: A “first generation” ΔE1/ΔE3 human type-5 adenoviral-vectors for gene delivery were designed and constructed to specifically target cancer cells. They are designated as "PY4-mazF-mCherry" (PY4, ras responsive element), "ΔPY4-mazF-mCherry" (control viruses) and "RGC-mazE-IRES-GFP" (RGC, P53 responsive element). Their potency was tested in vitro, by the enzymatic MTT assay, microscopic observation, colony formation assay and FACS analysis, and in a xenograft model of CRC. Next, we generated, small natural vesicles, exosomes, that directly targeted cancer through specific small antibody fragments against CD24 that is expressed in most cancer cells and rarely on normal cells. Results: The TA system ("PY4-mazF-mCherry"+"RGC-mazE-IRES-GFP") induced a massive cell death, in a dose-dependent manner in vitro, 69% as compared to 19% in control co-infected ("ΔPY4-mazF-mCherry"+"RGC-mazE-IRES-GFP") HCT116 CRC cells (mutated RAS and p53). In vivo, growth of HCT116-/- ( KRASmutand P53mut) and HCT116+/+ ( KRASmut and P53wt) tumors were significantly inhibited (70% and 65%, respectively). Conclusions: 1. Abusing the P53 genetic status and the activated Ras pathway holds promising effective and safe strategy to target tumor cells while sparing normal tissues. 2. It is a proof of concept for personalized cancer therapy based on the tumor genetic profile.

Chemotherapy in malignant disease

1970 ◽  
Vol 8 (4) ◽  
pp. 13-16
Keyword(s):  
Cancer Cells ◽  
Cancer Chemotherapy ◽  
Anticancer Agents ◽  
Antimicrobial Chemotherapy ◽  
Malignant Disease ◽  
Human Cells ◽  
Normal Cells ◽  
Different Types ◽  
Normal Human ◽  
Normal Human Cells

Cancer chemotherapy, unlike antimicrobial chemotherapy, is not based on absolute metabolic differences between cancer cells and normal human cells. Anticancer agents inhibit the growth of cells, whether normal or malignant, though different types of cell vary in their susceptibility to these agents, and in their capacity for recovery. The usefulness of these drugs is thus limited by their effects on normal cells.

scholarly journals Ethanolic Neem (Azadirachta indica) Leaf Extract Prevents Growth of MCF-7 and HeLa Cells and Potentiates the Therapeutic Index of Cisplatin

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Chhavi Sharma ◽  
Andrea J. Vas ◽  
Payal Goala ◽  
Taher M. Gheewala ◽  
Tahir A. Rizvi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cancer Cells ◽  
Time Dependent ◽  
Cytochrome P450 Monooxygenases ◽  
Dependent Manner ◽  
Morphological Examination ◽  
Cell Viability Assay ◽  
Normal Cells ◽  
Neem Leaves ◽  
Mcf 7

The present study was designed to gain insight into the antiproliferative activity of ethanolic neem leaves extract (ENLE) alone or in combination with cisplatin by cell viability assay on human breast (MCF-7) and cervical (HeLa) cancer cells. Nuclear morphological examination and cell cycle analysis were performed to determine the mode of cell death. Further, to identify its molecular targets, the expression of genes involved in apoptosis, cell cycle progression, and drug metabolism was analyzed by RT-PCR. Treatment of MCF-7, HeLa, and normal cells with ENLE differentially suppressed the growth of cancer cells in a dose- and time-dependent manner through apoptosis. Additionally, lower dose combinations of ENLE with cisplatin resulted in synergistic growth inhibition of these cells compared to the individual drugs (combination index <1). ENLE significantly modulated the expression of bax, cyclin D1, and cytochrome P450 monooxygenases (CYP 1A1 and CYP 1A2) in a time-dependent manner in these cells. Conclusively, these results emphasize the chemopreventive ability of neem alone or in combination with chemotherapeutic treatment to reduce the cytotoxic effects on normal cells, while potentiating their efficacy at lower doses. Thus, neem may be a prospective therapeutic agent to combat gynecological cancers.

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