scholarly journals Effects of Ferrocenyl 4-(Imino)-1,4-Dihydro-quinolines on Xenopus laevis Prophase I - Arrested Oocytes: Survival and Hormonal-Induced M-Phase Entry

2020 ◽  
Vol 21 (9) ◽  
pp. 3049
Author(s):  
Guillaume Marchand ◽  
Nathalie Wambang ◽  
Sylvain Pellegrini ◽  
Caroline Molinaro ◽  
Alain Martoriati ◽  
...  
Keyword(s):  
Organometallic Compounds ◽  
Inhibitory Effect ◽  
Cyclin B ◽  
Meiotic Spindle ◽  
Antimitotic Agent ◽  
New Class ◽  
Oocyte Meiosis ◽  
Anti Cancer ◽  
M Phase ◽  
Phase Entry

Xenopus oocytes were used as cellular and molecular sentinels to assess the effects of a new class of organometallic compounds called ferrocenyl dihydroquinolines that have been developed as potential anti-cancer agents. One ferrocenyl dihydroquinoline compound exerted deleterious effects on oocyte survival after 48 h of incubation at 100 μM. Two ferrocenyl dihydroquinoline compounds had an inhibitory effect on the resumption of progesterone induced oocyte meiosis, compared to controls without ferrocenyl groups. In these inhibited oocytes, no MPF (Cdk1/cyclin B) activity was detected by western blot analysis as shown by the lack of phosphorylation of histone H3. The dephosphorylation of the inhibitory Y15 residue of Cdk1 occurred but cyclin B was degraded. Moreover, two apoptotic death markers, the active caspase 3 and the phosphorylated histone H2, were detected. Only 7-chloro-1-ferrocenylmethyl-4-(phenylylimino)-1,4-dihydroquinoline (8) did not show any toxicity and allowed the assembly of a histologically normal metaphase II meiotic spindle while inhibiting the proliferation of cancer cell lines with a low IC50, suggesting that this compound appears suitable as an antimitotic agent.

scholarly journals SGK phosphorylates Cdc25 and Myt1 to trigger cyclin B–Cdk1 activation at the meiotic G2/M transition

2019 ◽  
Vol 218 (11) ◽  
pp. 3597-3611 ◽  
Author(s):  
Daisaku Hiraoka ◽  
Enako Hosoda ◽  
Kazuyoshi Chiba ◽  
Takeo Kishimoto
Keyword(s):  
Somatic Cell ◽  
Cyclin A ◽  
Pi3k Pathway ◽  
Cyclin B ◽  
Hormonal Stimulation ◽  
Oocyte Meiosis ◽  
M Phase ◽  
Mitosis And Meiosis ◽  
Cell Mitosis ◽  
Stimulation Of

The kinase cyclin B–Cdk1 complex is a master regulator of M-phase in both mitosis and meiosis. At the G2/M transition, cyclin B–Cdk1 activation is initiated by a trigger that reverses the balance of activities between Cdc25 and Wee1/Myt1 and is further accelerated by autoregulatory loops. In somatic cell mitosis, this trigger was recently proposed to be the cyclin A–Cdk1/Plk1 axis. However, in the oocyte meiotic G2/M transition, in which hormonal stimuli induce cyclin B–Cdk1 activation, cyclin A–Cdk1 is nonessential and hence the trigger remains elusive. Here, we show that SGK directly phosphorylates Cdc25 and Myt1 to trigger cyclin B–Cdk1 activation in starfish oocytes. Upon hormonal stimulation of the meiotic G2/M transition, SGK is activated by cooperation between the Gβγ-PI3K pathway and an unidentified pathway downstream of Gβγ, called the atypical Gβγ pathway. These findings identify the trigger in oocyte meiosis and provide insights into the role and activation of SGK.

Natural prenylated xanthones as potential inhibitors of PI3k/Akt/mTOR pathway in triple negative breast cancer cells

Planta Medica ◽  
2021 ◽  
Author(s):  
Thi Thu Ha Nguyen ◽  
Zhao Qu ◽  
Van Tuyen Nguyen ◽  
Thanh Tra Nguyen ◽  
Thi Tu Anh Le ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Inhibitory Effect ◽  
Positive Control ◽  
Phosphorylated Form ◽  
Anti Cancer ◽  
M Phase ◽  
Potential Inhibitors ◽  
Leading Compounds

Three prenylated xanthones, garcinone E (1), bannaxanthone D (2) and bannanxanthone E (3) were isolated from the leaves of Garcinia mckeaniana Graib. Their structures were elucidated by spectral methods and compared with literature data. To evaluate their anti-proliferative effects in tumor cells, firstly, cisplatin was used as a positive control and the effects of compound 1-3 were determined by performing MTT assay in MDA-MB-231, CNE-2 and A549 cancer cells. The results showed compound 1-3 exhibited stronger inhibitory effect than cisplatin in MDA-MB-231. Further effects of compound 1-3 in TNBC MDA-MB-231 and MDA-MB-468 cells were examined by performing cell cycle and apoptosis assays. The results indicated that compound 1-3 had ability to arrest cell cycle at G2/M phase and induce apoptosis. Furthermore, compound 2 significantly down-regulated PI3K, Akt and mTOR levels in both total proteins and phosphorylated form, which is its potential anti-cancer mechanism. These findings indicated that those prenylated xanthones might serve as promising leading compounds for the development of anticancer drug for TNBC.

scholarly journals Mutant MyoD Lacking Cdc2 Phosphorylation Sites Delays M-Phase Entry

2004 ◽  
Vol 24 (4) ◽  
pp. 1809-1821 ◽  
Author(s):  
Lionel A. J. Tintignac ◽  
Valentina Sirri ◽  
Marie Pierre Leibovitch ◽  
Yann Lécluse ◽  
Maria Castedo ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Kinase Activity ◽  
Expression Patterns ◽  
Cyclin B ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Cdc2 Kinase ◽  
Specific Expression ◽  
M Phase ◽  
Phase Entry

ABSTRACT The transcription factors MyoD and Myf-5 control myoblast identity and differentiation. MyoD and Myf-5 manifest opposite cell cycle-specific expression patterns. Here, we provide evidence that MyoD plays a pivotal role at the G2/M transition by controlling the expression of p21Waf1/Cip1 (p21), which is believed to regulate cyclin B-Cdc2 kinase activity in G2. In growing myoblasts, MyoD reaccumulates during G2 concomitantly with p21 before entry into mitosis; MyoD is phosphorylated on Ser5 and Ser200 by cyclin B-Cdc2, resulting in a decrease of its stability and down-regulation of both MyoD and p21. Inducible expression of a nonphosphorylable MyoD A5/A200 enhances the MyoD interaction with the coactivator P/CAF, thereby stimulating the transcriptional activation of a luciferase reporter gene placed under the control of the p21 promoter. MyoD A5/A200 causes sustained p21 expression, which inhibits cyclin B-Cdc2 kinase activity in G2 and delays M-phase entry. This G2 arrest is not observed in p21−/− cells. These results show that in cycling cells MyoD functions as a transcriptional activator of p21 and that MyoD phosphorylation is required for G2/M transition.

scholarly journals asunder Is a Critical Regulator of Dynein–Dynactin Localization during Drosophila Spermatogenesis

2009 ◽  
Vol 20 (11) ◽  
pp. 2709-2721 ◽  
Author(s):  
Michael A. Anderson ◽  
Jeanne N. Jodoin ◽  
Ethan Lee ◽  
Karen G. Hales ◽  
Thomas S. Hays ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Spindle ◽  
Nuclear Surface ◽  
Drastic Reduction ◽  
Cell Cycles ◽  
M Phase ◽  
Microtubule Motor ◽  
Phase Entry ◽  
Prophase Of Meiosis ◽  
Drosophila Mutant

Spermatogenesis uses mitotic and meiotic cell cycles coordinated with growth and differentiation programs to generate functional sperm. Our analysis of a Drosophila mutant has revealed that asunder (asun), which encodes a conserved protein, is an essential regulator of spermatogenesis. asun spermatocytes arrest during prophase of meiosis I. Strikingly, arrested spermatocytes contain free centrosomes that fail to stably associate with the nucleus. Spermatocytes that overcome arrest exhibit severe defects in meiotic spindle assembly, chromosome segregation, and cytokinesis. Furthermore, the centriole-derived basal body is detached from the nucleus in asun postmeiotic spermatids, resulting in abnormalities later in spermatogenesis. We find that asun spermatocytes and spermatids exhibit drastic reduction of perinuclear dynein–dynactin, a microtubule motor complex. We propose a model in which asun coordinates spermatogenesis by promoting dynein–dynactin recruitment to the nuclear surface, a poorly understood process required for nucleus–centrosome coupling at M phase entry and fidelity of meiotic divisions.

scholarly journals The M Phase Kinase Greatwall (Gwl) Promotes Inactivation of PP2A/B55δ, a Phosphatase Directed Against CDK Phosphosites

2009 ◽  
Vol 20 (22) ◽  
pp. 4777-4789 ◽  
Author(s):  
Priscila V. Castilho ◽  
Byron C. Williams ◽  
Satoru Mochida ◽  
Yong Zhao ◽  
Michael L. Goldberg
Keyword(s):  
Cyclin B ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinases ◽  
M Phase ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Greatwall Kinase ◽  
Xenopus Egg Extracts ◽  
Phase Entry ◽  
Dependent Mechanism

We have previously shown that Greatwall kinase (Gwl) is required for M phase entry and maintenance in Xenopus egg extracts. Here, we demonstrate that Gwl plays a crucial role in a novel biochemical pathway that inactivates, specifically during M phase, “antimitotic” phosphatases directed against phosphorylations catalyzed by cyclin-dependent kinases (CDKs). A major component of this phosphatase activity is heterotrimeric PP2A containing the B55δ regulatory subunit. Gwl is activated during M phase by Cdk1/cyclin B (MPF), but once activated, Gwl promotes PP2A/B55δ inhibition with no further requirement for MPF. In the absence of Gwl, PP2A/B55δ remains active even when MPF levels are high. The removal of PP2A/B55δ corrects the inability of Gwl-depleted extracts to enter M phase. These findings support the hypothesis that M phase requires not only high levels of MPF function, but also the suppression, through a Gwl-dependent mechanism, of phosphatase(s) that would otherwise remove MPF-driven phosphorylations.

scholarly journals SGK phosphorylates Cdc25 and Myt1 to trigger cyclin B-Cdk1 activation at the meiotic G2/M transition

2018 ◽  
Author(s):  
Daisaku Hiraoka ◽  
Enako Hosoda ◽  
Kazuyoshi Chiba ◽  
Takeo Kishimoto
Keyword(s):  
Somatic Cell ◽  
Cyclin A ◽  
Pi3k Pathway ◽  
Cyclin B ◽  
Hormonal Stimulation ◽  
Oocyte Meiosis ◽  
M Phase ◽  
Mitosis And Meiosis ◽  
Cell Mitosis ◽  
Stimulation Of

The kinase cyclin B-Cdk1 complex is a master regulator of M-phase in both mitosis and meiosis. At the G2/M transition, cyclin B-Cdk1 activation is initiated by a trigger that reverses the balance of activities between Cdc25 and Wee1/Myt1, and is further accelerated by autoregulatory loops. In somatic cell mitosis, this trigger was recently proposed to be the cyclin A-Cdk1/Plk1 axis. However, in the oocyte meiotic G2/M transition, in which hormonal stimuli induce cyclin B-Cdk1 activation, cyclin A-Cdk1 is non-essential and hence the trigger remains elusive. Here, we show that SGK directly phosphorylates Cdc25 and Myt1 to trigger cyclin B-Cdk1 activation in starfish oocytes. After hormonal stimulation of the meiotic G2/M transition, SGK is activated by cooperation between the Gβγ-PI3K pathway and an unidentified pathway downstream of Gβγ, called the atypical Gβγ pathway. These findings identify the trigger in oocyte meiosis and provide insights into the role and activation of SGK.

scholarly journals M-Phase oscillations in PP1 activity are essential for accurate progression through mammalian oocyte meiosis

2021 ◽  
Author(s):  
Nicole J Camlin ◽  
Ilakkiya Venkatachalam ◽  
Janice P Evans
Keyword(s):  
Phase Transitions ◽  
Mouse Oocyte ◽  
Experimental Systems ◽  
Oocyte Meiosis ◽  
Chromosome Alignment ◽  
M Phase ◽  
Active Pool ◽  
Phase Regulation ◽  
Phase Entry ◽  
Metaphase I

Tightly controlled fluctuations in kinase and phosphatase activity play important roles in regulating M-Phase transitions (e.g., G2/M). Protein Phosphatase 1 (PP1) is one of these phosphatases, with oscillations in activity driving mitotic M-Phase entry, progression, and exit, with evidence from a variety of experimental systems pointing to roles in meiosis as well. Here we report that PP1 is important for M-Phase transitions through mouse oocyte meiosis. Employing a unique small-molecule approach to inhibit or activate PP1 at distinct phases of mouse oocyte meiosis, we found that aberrations in normal cyclical PP1 activity leads to meiotic abnormalities. We report here that temporal control of PP1 activity is essential for G2/M transition, metaphase I/anaphase I transition, and the formation of a normal metaphase II oocyte. Our data also reveal that inappropriate activation of PP1 is more deleterious at G2/M transition than at prometaphase I-to-metaphase I, and that an active pool of PP1 during prometaphase I is vital for metaphase I/anaphase I transition and metaphase II chromosome alignment. Taken together, these results establish that loss of oscillations in PP1 activity causes a range of severe meiotic defects, pointing to essential roles for PP1 in oocytes and female fertility, and more broadly, M-Phase regulation.

Biological role of AKT, and regulation of AKT signaling pathway by thymoquinone: perspectives in cancer therapeutics

2020 ◽  
Vol 20 ◽  
Author(s):  
Md. Junaid ◽  
Yeasmin Akter ◽  
Syeda Samira Afrose ◽  
Mousumi Tania ◽  
Md. Asaduzzaman Khan
Keyword(s):  
Clinical Trials ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Inhibitory Effect ◽  
Akt Signaling ◽  
Review Article ◽  
Therapeutic Drug ◽  
Akt Signaling Pathway ◽  
Anti Cancer

Background: AKT/PKB is an important enzyme with numerous biological functions, and its overexpression is related to the carcinogenesis. AKT stimulates different signaling pathways that are downstream of activated tyrosine kinases and phosphatidylinositol 3-kinase, hence functions as an important target for anti-cancer drugs. Objective: In this review article, we have interpreted the role of AKT signaling pathways in cancer and natural inhibitory effect of Thymoquinone (TQ) in AKT and its possible mechanism. Method: We have collected the updated information and data on AKT, their role in cancer and inhibitory effect of TQ in AKT signaling pathway from google scholar, PubMed, Web of Science, Elsevier, Scopus and many more. Results: There are many drugs already developed, which can target AKT, but very few among them have passed clinical trials. TQ is a natural compound, mainly found in black cumin, which has been found to have potential anti-cancer activities. TQ targets numerous signaling pathways, including AKT, in different cancers. In fact, many studies revealed that AKT is one of the major targets of TQ. The preclinical success of TQ suggests its clinical studies on cancer. Conclusion: This review article summarizes the role of AKT in carcinogenesis, its potent inhibitors in clinical trials, and how TQ acts as an inhibitor of AKT and TQ’s future as a cancer therapeutic drug.

Synergistic Antitumor Effect of 5-Fluorouracil Combined with Constituents from Pleurospermum lindleyanum in Hepatocellular carcinoma SMMC-7721 Cells

2020 ◽  
Vol 20 ◽  
Author(s):  
Xiao-Feng Zhu ◽  
Xiao-Jin Li ◽  
Zhong-Lian Cao ◽  
Xiu-Jie Liu ◽  
Ping Yang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Treatment Effectiveness ◽  
Synergistic Effects ◽  
Folk Medicine ◽  
Inhibitory Effect ◽  
Caspase 9 ◽  
Whole Plant ◽  
Anti Cancer ◽  
Induced Apoptosis

Background: A Chinese folk medicine plant Pleurospermum lindleyanum possesses pharmacological activities of heat-clearing, detoxifying and preventing from hepatopathy, coronary heart disease, hypertension, and high altitude sickness. We isolated and characterized its constituents to investigate its synergistic effects against human hepatoma SMMC-7721 cells. Objective: The aim of this study was to explore the synergistic anti-cancer activities of isolates from P. lindleyanum with 5-FU on hepatoma SMMC-7721 cells in vitro and their primary mechanisms. Methods: Sequential chromatographic techniques were conducted for the isolation studies. The isolates structures were established by spectroscopic analysis as well as X-ray crystallographic diffraction. Growth inhibition was detected by MTT assay. The isobologram method was used to assess the effect of drug combinations. Flow cytometry and western blot were used to examine apoptosis and protein expression. Results: A new coumarin (16), along with sixteen known compounds, were isolated from the whole plant of P. lindleyanum and their structures were elucidated by spectroscopic methods. Four coumarins (2, 3, 5, and 16), two flavonoids (8 and 9) and three phytosterols and triterpenes (12-14) were found to synergistically enhance the inhibitory effect of 5-FU against SMMC-7721 cells. Among them, compounds 3 and 16 exhibited the best synergistic effects with IC50 of 5-FU reduced by 16-fold and 22-fold possessing the minimum Combination Index (CI) 0.34 and 0.27. The mechanism of action of combinations might be through synergistic arresting for the cell cycle at G1 phases and the induction of apoptosis. Moreover, western blotting and molecular docking revealed that compounds 3 or 5 might promote 5-FU-induced apoptosis by regulating the expression of Caspase 9 and PARP. Conclusion: Constituents from P. lindleyanum may improve the treatment effectiveness of 5-FU against hepatocellular carcinoma cells.

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