scholarly journals In vitro microtubule-nucleating activity of spindle pole bodies in fission yeast Schizosaccharomyces pombe: cell cycle-dependent activation in xenopus cell-free extracts

1992 ◽  
Vol 117 (5) ◽  
pp. 1055-1066 ◽  
Author(s):  
H Masuda ◽  
M Sevik ◽  
WZ Cande
Keyword(s):  
Fission Yeast ◽  
Spindle Pole ◽  
Protein Kinase Inhibitors ◽  
Cyclin B ◽  
Microtubule Organizing Center ◽  
Cdc2 Kinase ◽  
Gamma Tubulin ◽  
In Cells

The spindle pole body (SPB) is the equivalent of the centrosome in fission yeast. In vivo it nucleates microtubules (MTs) during mitosis, but, unlike animal centrosomes, does not act as a microtubule organizing center (MTOC) during interphase. We have studied the MT-nucleating activity of SPBs in vitro and have found that SPBs in permeabilized cells retain in vivo characteristics. SPBs in cells permeabilized during mitosis can nucleate MTs, and are recognized by two antibodies: anti-gamma-tubulin and MPM-2 which recognizes phosphoepitopes. SPBs in cells permeabilized during interphase cannot nucleate MTs and are only recognized by anti-gamma-tubulin. Interphase SPBs which cannot nucleate can be converted to a nucleation competent state by incubation in cytostatic factor (CSF)-arrested Xenopus egg extracts. After incubation, they are recognized by MPM-2, and can nucleate MTs. The conversion does not occur in Xenopus interphase extract, but occurs in Xenopus interphase extract driven into mitosis by preincubation with exogenous cyclin B. The conversion is ATP dependent and inhibited by protein kinase inhibitors and alkaline phosphatase. Purified, active, cdc2 kinase/cyclin B complex in itself is not effective for activation of MT nucleation, although some interphase SPBs are now stained with MPM-2. These results suggest that the ability of SPBs in vitro to nucleate MTs after exposure to CSF-arrested extracts is activated through a downstream pathway which is regulated by cdc2 kinase.

scholarly journals Plk is an M-phase-specific protein kinase and interacts with a kinesin-like protein, CHO1/MKLP-1.

1995 ◽  
Vol 15 (12) ◽  
pp. 7143-7151 ◽  
Author(s):  
K S Lee ◽  
Y L Yuan ◽  
R Kuriyama ◽  
R L Erikson
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Maximum Level ◽  
Specific Protein ◽  
Cyclin B ◽  
Cdc2 Kinase ◽  
M Phase ◽  
Nih 3T3

PLK (STPK13) encodes a murine protein kinase closely related to those encoded by the Drosophila melanogaster polo gene and the Saccharomyces cerevisiae CDC5 gene, which are required for normal mitotic and meiotic divisions. Affinity-purified antibody generated against the C-terminal 13 amino acids of Plk specifically recognizes a single polypeptide of 66 kDa in MELC, NIH 3T3, and HeLa cellular extracts. The expression levels of both poly(A)+ PLK mRNA and its encoded protein are most abundant about 17 h after serum stimulation of NIH 3T3 cells. Plk protein begins to accumulate at the S/G2 boundary and reaches the maximum level at the G2/M boundary in continuously cycling cells. Concurrent with cyclin B-associated cdc2 kinase activity, Plk kinase activity sharply peaks at the onset of mitosis. Plk enzymatic activity gradually decreases as M phase proceeds but persists longer than cyclin B-associated cdc2 kinase activity. Plk is localized to the area surrounding the chromosomes in prometaphase, appears condensed as several discrete bands along the spindle axis at the interzone in anaphase, and finally concentrates at the midbody during telophase and cytokinesis. Plk and CHO1/mitotic kinesin-like protein 1 (MKLP-1), which induces microtubule bundling and antiparallel movement in vitro, are colocalized during late M phase. In addition, CHO1/MKLP-1 appears to interact with Plk in vivo and to be phosphorylated by Plk-associated kinase activity in vitro.

scholarly journals Cyclin B/cdc2 Induces c-Mos Stability by Direct Phosphorylation in Xenopus Oocytes

2001 ◽  
Vol 12 (9) ◽  
pp. 2660-2671 ◽  
Author(s):  
Anna Castro ◽  
Marion Peter ◽  
Laura Magnaghi-Jaulin ◽  
Suzanne Vigneron ◽  
Simon Galas ◽  
...  
Keyword(s):  
Xenopus Oocytes ◽  
Phosphorylation Site ◽  
Cyclin B ◽  
Mobility Shift ◽  
Cdc2 Kinase ◽  
Phosphopeptide Analysis ◽  
Vertebrate Eggs ◽  
The One

The c-Mos proto-oncogene product plays an essential role during meiotic divisions in vertebrate eggs. In Xenopus, it is required for progression of oocyte maturation and meiotic arrest of unfertilized eggs. Its degradation after fertilization is essential to early embryogenesis. In this study we investigated the mechanisms involved in c-Mos degradation. We present in vivo evidence for ubiquitin-dependent degradation of c-Mos in activated eggs. We found that c-Mos degradation is not directly dependent on the anaphase-promoting factor activator Fizzy/cdc20 but requires cyclin degradation. We demonstrate that cyclin B/cdc2 controls in vivo c-Mos phosphorylation and stabilization. Moreover, we show that cyclin B/cdc2 is capable of directly phosphorylating c-Mos in vitro, inducing a similar mobility shift to the one observed in vivo. Tryptic phosphopeptide analysis revealed a practically identical in vivo and in vitro phosphopeptide map and allowed identification of serine-3 as the largely preferential phosphorylation site as previously described ( Freeman et al., 1992 ). Altogether, these results demonstrate that, in vivo, stability of c-Mos is directly regulated by cyclin B/cdc2 kinase activity.

Functionally homologous DNA replication genes in fission and budding yeast

1999 ◽  
Vol 112 (14) ◽  
pp. 2381-2390
Author(s):  
M. Sanchez ◽  
A. Calzada ◽  
A. Bueno
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Kinase Activity ◽  
Budding Yeast ◽  
S Phase ◽  
Yeast Gene ◽  
Cdc2 Kinase ◽  
Initiation Of Dna Replication

The cdc18(+) gene of the fission yeast Schizosaccharomyces pombe is involved in the initiation of DNA replication as well as in coupling the S phase to mitosis. In this work, we show that the Saccharomyces cerevisiae CDC6 gene complements cdc18-K46 ts and cdc18 deletion mutant S. pombe strains. The budding yeast gene suppresses both the initiation and the checkpoint defects associated with the lack of cdc18(+). The Cdc6 protein interacts in vivo with Cdc2 kinase complexes. Interestingly, Cdc6 is an in vitro substrate for Cdc13/Cdc2 and Cig1/Cdc2, but not for Cig2/Cdc2-associated kinases. Overexpression of Cdc6 in fission yeast induces multiple rounds of S-phase in the absence of mitosis and cell division. This CDC6-dependent continuous DNA synthesis phenotype is independent of the presence of a functional cdc18(+) gene product and, significantly, requires only Cig2/Cdc2-associated kinase activity. Finally, these S. pombe over-replicating cells do not require any protein synthesis other than that of Cdc6. Our data strongly suggest that CDC6 and cdc18(+) are functional homologues and also support the idea that controls restricting genome duplication diverge in fission and budding yeast.

scholarly journals Human gamma-tubulin functions in fission yeast.

1994 ◽  
Vol 126 (6) ◽  
pp. 1465-1473 ◽  
Author(s):  
T Horio ◽  
B R Oakley
Keyword(s):  
Fission Yeast ◽  
Normal Growth ◽  
Spindle Pole ◽  
Microtubule Assembly ◽  
Microtubule Organizing Center ◽  
Microtubule Organization ◽  
Microtubule Organizing Centers ◽  
Functional Conservation ◽  
Gamma Tubulin ◽  
Tubulin Immunofluorescence

gamma-Tubulin is a phylogenetically conserved component of microtubule-organizing centers that is essential for viability and microtubule function. To examine the functional conservation of gamma-tubulin, we have tested the ability of human gamma-tubulin to function in the fission yeast Schizosaccharomyces pombe. We have found that expression of a human gamma-tubulin cDNA restores viability and a near-normal growth rate to cells of S. pombe lacking endogenous gamma-tubulin. Immunofluorescence microscopy showed that these cells contained normal mitotic spindles and interphase microtubule arrays, and that human gamma-tubulin, like S. pombe gamma-tubulin, localized to spindle pole bodies, the fungal microtubule-organizing centers. These results demonstrate that human gamma-tubulin functions in fission yeast, and they suggest that in spite of the great morphological differences between the microtubule-organizing centers of humans and fission yeasts, gamma-tubulin is likely to perform the same tasks in both. They suggest, moreover, that the proteins that interact with gamma-tubulin, including, most obviously, microtubule-organizing center proteins, must also be conserved. We have also found that a fivefold overexpression of S. pombe gamma-tubulin causes no reduction in growth rates or alteration of microtubule organization. We hypothesize that the excess gamma-tubulin is maintained in the cytoplasm in a form incapable of nucleating microtubule assembly. Finally, we have found that expression of human gamma-tubulin or overexpression of S. pombe gamma-tubulin causes no significant alteration of resistance to the antimicrotubule agents benomyl, thiabendazole and nocodazole.

The fission yeast gamma-tubulin is essential for mitosis and is localized at microtubule organizing centers

1991 ◽  
Vol 99 (4) ◽  
pp. 693-700 ◽  
Author(s):  
T. Horio ◽  
S. Uzawa ◽  
M.K. Jung ◽  
B.R. Oakley ◽  
K. Tanaka ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Essential Gene ◽  
Spindle Pole ◽  
Gene Encoding ◽  
Cytoplasmic Microtubule ◽  
Microtubule Organizing Centers ◽  
Tubulin Antibodies ◽  
Gamma Tubulin ◽  
Tubulin Immunofluorescence

gamma-Tubulin exists in fission yeast as the product of an essential gene, encoding a 446 amino acid protein that is 77.3% identical to Aspergillus nidulans gamma-tubulin. The gene disruption caused cell lethality, displaying condensed, undivided chromosomes with aberrant spindle structures. Anti-gamma-tubulin staining showed that gamma-tubulin is located, throughout the wild-type cell cycle, at the spindle pole bodies (SPBs), indicating that gamma-tubulin associates with interphase SPB in the absence of microtubules. In addition, anti-gamma-tubulin immunofluorescence staining revealed cytoplasmic, cell-equatorial putative MTOCs (microtubule organizing centers), which appear only during mitotic telophase and cytokinesis, and are located at the centers for the new cytoplasmic microtubule arrays of the two daughter cells. In the multiple-SPB mutant cut1-cdc11, anti-gamma-tubulin antibodies revealed many dots on the periphery of the nucleus. These results confirm that gamma-tubulin is an important member of the tubulin superfamily, suggest that it may be a universal component of MTOCs, and are consistent with a role for gamma-tubulin in controlling microtubule formation in vivo.

Alkaloids as Anticancer Agents: A Review of Chinese Patents in Recent 5 Years

2020 ◽  
Vol 15 (1) ◽  
pp. 2-13 ◽  
Author(s):  
Hongyu Tao ◽  
Ling Zuo ◽  
Huanli Xu ◽  
Cong Li ◽  
Gan Qiao ◽  
...  
Keyword(s):  
Anticancer Activity ◽  
Anticancer Agents ◽  
Kinase Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Cdk Inhibitors ◽  
Comprehensive Overview ◽  
P53 Expression ◽  
Study Results

Background: In recent years, many novel alkaloids with anticancer activity have been found in China, and some of them are promising for developing as anticancer agents. Objective: This review aims to provide a comprehensive overview of the information about alkaloid anticancer agents disclosed in Chinese patents, and discusses their potential to be developed as anticancer drugs used clinically. Methods: Anticancer alkaloids disclosed in Chinese patents in recent 5 years were presented according to their mode of actions. Their study results published on PubMed, and SciDirect databases were presented. Results: More than one hundred anticancer alkaloids were disclosed in Chinese patents and their mode of action referred to arresting cell cycle, inhibiting protein kinases, affecting DNA synthesis and p53 expression, etc. Conclusion: Many newly found alkaloids displayed potent anticancer activity both in vitro and in vivo, and some of the anticancer alkaloids acted as protein kinase inhibitors or CDK inhibitors possess the potential for developing as novel anticancer agents.

Biologic Aspects of Expression of Stably Integrated Transgenes in Cells of the Skin In Vitro and In Vivo

1999 ◽  
Vol 111 (3) ◽  
pp. 198-205 ◽  
Author(s):  
Gerald G. Krueger ◽  
Jeffery R. Morgan ◽  
Marta J. Petersen
Keyword(s):  
In Cells

scholarly journals 1592U89, a novel carbocyclic nucleoside analog with potent, selective anti-human immunodeficiency virus activity.

1997 ◽  
Vol 41 (5) ◽  
pp. 1082-1093 ◽  
Author(s):  
S M Daluge ◽  
S S Good ◽  
M B Faletto ◽  
W H Miller ◽  
M H St Clair ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Oral Bioavailability ◽  
Human Peripheral Blood ◽  
Cross Resistance ◽  
Immunodeficiency Virus ◽  
Carbocyclic Nucleoside ◽  
Hiv 1 ◽  
In Cells

1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, is a carbocyclic nucleoside with a unique biological profile giving potent, selective anti-human immunodeficiency virus (HIV) activity. 1592U89 was selected after evaluation of a wide variety of analogs containing a cyclopentene substitution for the 2'-deoxyriboside of natural deoxynucleosides, optimizing in vitro anti-HIV potency, oral bioavailability, and central nervous system (CNS) penetration. 1592U89 was equivalent in potency to 3'-azido-3'-deoxythymidine (AZT) in human peripheral blood lymphocyte (PBL) cultures against clinical isolates of HIV type 1 (HIV-1) from antiretroviral drug-naive patients (average 50% inhibitory concentration [IC50], 0.26 microM for 1592U89 and 0.23 microM for AZT). 1592U89 showed minimal cross-resistance (approximately twofold) with AZT and other approved HIV reverse transcriptase (RT) inhibitors. 1592U89 was synergistic in combination with AZT, the nonnucleoside RT inhibitor nevirapine, and the protease inhibitor 141W94 in MT4 cells against HIV-1 (IIIB). 1592U89 was anabolized intracellularly to its 5'-monophosphate in CD4+ CEM cells and in PBLs, but the di- and triphosphates of 1592U89 were not detected. The only triphosphate found in cells incubated with 1592U89 was that of the guanine analog (-)-carbovir (CBV). However, the in vivo pharmacokinetic, distribution, and toxicological profiles of 1592U89 were distinct from and improved over those of CBV, probably because CBV itself was not appreciably formed from 1592U89 in cells or animals (<2%). The 5'-triphosphate of CBV was a potent, selective inhibitor of HIV-1 RT, with Ki values for DNA polymerases (alpha, beta, gamma, and epsilon which were 90-, 2,900-, 1,200-, and 1,900-fold greater, respectively, than for RT (Ki, 21 nM). 1592U89 was relatively nontoxic to human bone marrow progenitors erythroid burst-forming unit and granulocyte-macrophage CFU (IC50s, 110 microM) and human leukemic and liver tumor cell lines. 1592U89 had excellent oral bioavailability (105% in the rat) and penetrated the CNS (rat brain and monkey cerebrospinal fluid) as well as AZT. Having demonstrated an excellent preclinical profile, 1592U89 has progressed to clinical evaluation in HIV-infected patients.

scholarly journals Identification of circRNA circ-CSPP1 as a potent driver of colorectal cancer by directly targeting the miR-431/LASP1 axis

2021 ◽  
Vol 16 (1) ◽  
pp. 523-536
Author(s):  
Minghao Li ◽  
Jianbin Zhuang ◽  
Di Kang ◽  
Yuzhuo Chen ◽  
Weiliang Song
Keyword(s):  
Colorectal Cancer ◽  
Cancer Biology ◽  
Spindle Pole ◽  
Circular Rnas ◽  
Cell Progression ◽  
Crc Management ◽  
Common Malignancy

Abstract Colorectal cancer (CRC) is the third most common malignancy worldwide. Circular RNAs (circRNAs) have been implicated in cancer biology. The purpose of the current work is to investigate the precise parts of circRNA centrosome and spindle pole-associated protein 1 (circ-CSPP1) in the progression of CRC. Our data showed that circ-CSPP1 was significantly overexpressed in CRC tissues and cells. The knockdown of circ-CSPP1 attenuated cell proliferation, migration, invasion and promoted apoptosis in vitro and weakened tumor growth in vivo. circ-CSPP1 directly targeted miR-431, and circ-CSPP1 knockdown modulated CRC cell progression in vitro via upregulating miR-431. Moreover, LIM and SH3 protein 1 (LASP1) was a functional target of miR-431 in modulating CRC cell malignant progression. Furthermore, circ-CSPP1 in CRC cells functioned as a posttranscriptional regulator on LASP1 expression by targeting miR-431. Our present study identified the oncogenic role of circ-CSPP1 in CRC partially by the modulation of the miR-431/LASP1 axis, providing evidence for circ-CSPP1 as a promising biomarker for CRC management.

scholarly journals Targeting IDH1/2 mutant cancers with combinations of ATR and PARP inhibitors

NAR Cancer ◽  
2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Amrita Sule ◽  
Jinny Van Doorn ◽  
Ranjini K Sundaram ◽  
Sachita Ganesa ◽  
Juan C Vasquez ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Parp Inhibitor ◽  
Parp Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Isocitrate Dehydrogenase 1 ◽  
Normal Product ◽  
Synthetic Lethal Interactions ◽  
Mutant Cells

Abstract Mutations in the isocitrate dehydrogenase-1 and -2 (IDH1/2) genes were first identified in glioma and acute myeloid leukemia (AML), and subsequently found in multiple other tumor types. These neomorphic mutations convert the normal product of enzyme, α-ketoglutarate (αKG), to the oncometabolite 2-hydroxyglutarate (2HG). Our group recently demonstrated that 2HG suppresses the high-fidelity homologous recombination (HR) DNA repair pathway, resulting in a state referred to as ‘BRCAness’, which confers exquisite sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. In this study, we sought to elucidate sensitivity of IDH1/2-mutant cells to DNA damage response (DDR) inhibitors and, whether combination therapies could enhance described synthetic lethal interactions. Here, we report that ATR (ataxia telangiectasia and Rad3-related protein kinase) inhibitors are active against IDH1/2-mutant cells, and that this activity is further potentiated in combination with PARP inhibitors. We demonstrate this interaction across multiple cell line models with engineered and endogenous IDH1/2 mutations, with robust anti-tumor activity in vitro and in vivo. Mechanistically, we found ATR and PARP inhibitor treatment induces premature mitotic entry, which is significantly elevated in the setting of IDH1/2-mutations. These data highlight the potential efficacy of targeting HR defects in IDH1/2-mutant cancers and support the development of this combination in future clinical trials.

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