Greatwall Kinase Participates in the Cdc2 Autoregulatory Loop in Xenopus Egg Extracts
161
Citation
35
Reference
10
Related Paper
Citation Trend
Keywords:
Maturation promoting factor
Germinal vesicle
Maturation promoting factor
Cite
Citations (157)
This study demonstrated the effects of phosphate on the 2-cell block of AKR/N mouse embryos at the molecular level and focused on changes in the kinase activity and the phosphorylation state of cdc2, which is shown to regulate the cell division cycle. Removal of phosphate from the culture medium dramatically increased developmental rates to the 4-cell (91.8%) and blastocyst (42.6%) stages compared with those of embryos cultured in 1.17 mM phosphate (3.3% and 0%, respectively). The rate of development to the 4-cell stage was significantly inhibited by 0.001 mM phosphate (p < 0.05), and no morula formation was observed at 1.0 mM. The patterns of cdc2 kinase activity during the first cell cycle in AKR/N embryos were similar to those of control MCH embryos, showing the highest activity at M phase and low activity during the interphase. The phosphorylated form of cdc2 increased during the interphase, indicating that the synthesis of cyclin B and accumulation of inactive pre-maturation-promoting factor (pre-MPF) as well as abrupt dephosphorylation of cdc2 at the first cleavage correlated with the activation of cdc2 kinase. When phosphate was absent, the activation pattern of cdc2 kinase during the second cell cycle in AKR/N embryos was similar to that in the first cell cycle. On the other hand, no dephosphorylation of cdc2 was observed and the kinase activity remained at a low level until 56 h after insemination in the presence of phosphate, although an increase in phosphorylated cdc2 was observed as in the phosphate-free group. Treatment of AKR/N embryos arrested at the 2-cell stage with okadaic acid resulted in the dephosphorylation and activation of cdc2, confirming the presence of a sufficient amount of pre-MPF. These results show that phosphate has a deteriorative effect on the in vitro development of AKR/N embryos and suggest that this effect was not on the synthesis of cyclin B but on the dephosphorylation of phosphorylated cdc2.
Maturation promoting factor
Dephosphorylation
Interphase
Cite
Citations (30)
During the conversion to the mitotic state, higher eukaryotic cells activate a cascade of reactions which result in the disintegration of the nuclear envelope, the condensation of the DNA into chromosomes, and the reorganization of the cytoskeleton. In Xenopus, the induction of the mitotic state appears to be under the control of a cytoplasmic factor(s) known as mitosis-promoting factor or MPF. We have developed a rapid and highly sensitive version of an in vitro assay for MPF. The assay uses reconstituted nuclei in interphase cytoplasm from activated Xenopus eggs. The MPF-induced conversion from interphase to mitosis is conveniently monitored by the visual observation of the loss of the nuclear envelope from the substrate nuclei. At near saturating concentrations of MPF, nuclear breakdown requires 20-30 min. Preincubation experiments have revealed that the action of MPF requires only a few minutes and that the disassembly process itself takes up the remainder of the incubation period. Using this cell-free system, we have investigated the observation that protein synthesis is required for the progression through each successive mitotic cycle in the developing Xenopus embryo. A simple explanation for this finding would be that MPF is degraded after each mitosis and then resynthesized before the next mitotic cycle. However, using in vitro reactivation experiments, we have found that MPF is present in a latent, inactive form during interphase. These results suggest that the block in the cell cycle induced by inhibitors of protein synthesis is due to the lack of production of an activator of MPF.
Interphase
Maturation promoting factor
Premature chromosome condensation
Cite
Citations (69)
Maturation promoting factor
Schizosaccharomyces
Immunoprecipitation
Cite
Citations (886)
In all systems examined so far, the G2/M phase transition is controlled by the M-phase promoting factor (MPF), a complex of cdc2 (CDK1) and cyclin B1. Histone H1 kinase activity and MPF components are present in pachytene spermatocytes (PS). However, it has not been demonstrated yet that direct inhibition of MPF activity prevents the G2/M transition in these cells. When roscovitine, a potent inhibitor of CDK1, CDK2, and CDK5 activities, was added to cocultures of PS with Sertoli cells, the number of both secondary spermatocytes and round spermatids formed were lower than in control cultures, despite similar cell viability. This effect of roscovitine was reversible, did not involve the Sertoli cells, and was dependent on the concentration of the inhibitor. Roscovitine did not modify the amount of MPF in these germ cells but inhibited the CDK1- or CDK2-associated histone H1 kinase activity of PS. Hence a functional relationship between cyclin-dependent kinase activity and the spontaneous processing of the first meiotic division and, for the first time, of the second meiotic division of male germ cells is shown.
Maturation promoting factor
Cyclin B
Cyclin B1
Cyclin A
Cite
Citations (29)
The cAMP dependent protein kinase (PKA) stimulator cAMP and thermal stable inhibitor PKI (protein kinase A inhibitor) were microinjected into mouse 1-cell stage fertilized eggs in order to study the effect of PKA on M-phase promoting factor (MPF) activity and cell cycle progression.For the control group,MPF activity began to rise at 27\^5 hours after adding HCG,after 0\^5 hours reached to a plateau of about 1 hour and then decreased rapidly.The PKA activity sustained a high level during the interphase before 27 hours and after 29 hours after adding HCG and low during M phase (28—29 hours after adding HCG).In the cAMP group,PKA activity sustained a high level at the first 28 hours and the MPF activity reached to a high plateau after 30 min.In the PKI group,the PKA activity was low in the period from 27 hours to 29 hours,but the MPF activity reached to a high value at 27\^5 hours and lasted for 1\^5 hours at that level.These results showed that both the activities of PKA and MPF oscillated during the cell cycle.PKA activity was high during interphase and low during M phase,stimulation of PKA induced interphase arrest preventing the activation of the M phase promoting factor.Inhibition of endogenous PKA in interphase increased MPF activity,hastened the onset of mitosis.
Maturation promoting factor
Interphase
Cite
Citations (0)
We measured mitosis-promoting factor (MPF) activity in two cell lines, CHO and HeLa, extensively used at mitosis as inducers in the assay of premature chromosome condensation to study the yield and the repair kinetics of radiation damage in interphase chromosomes of diverse cell lines. We found a 2.5-fold higher MPF activity in HeLa as compared to CHO mitotic cells per mg of crude extract protein. HeLa mitotic cells, when used as inducers of premature chromosome condensation, uncovered two times more interphase chromosome breaks in irradiated, nonstimulated human lymphocytes as compared to CHO mitotic cells. A 2-fold increase in the yield of interphase chromosome breaks with HeLa mitotics was also observed in G1 cells from plateau-phase CHO cultures. Thus, MPF activity may be a contributing factor of the process that transforms radiation-induced DNA damage to chromosome breaks, and subsequently to other types of lethal chromosome aberrations. We speculate that the level and the control in the cell cycle of MPF activity may influence the radiosensitivity of cells to killing. The results strongly suggest that a direct comparison between the yields of interphase chromosome breaks measured in different laboratories may not be possible unless similar inducer cells with similar MPF activity are used.
Premature chromosome condensation
Interphase
Maturation promoting factor
HeLa
Radiosensitivity
Cite
Citations (28)
Abstract Mitosis promoting factor (MPF) plays a central role during the first mitosis of mouse embryo. We demonstrated that MPF activity increased when one‐cell stage mouse embryo initiated G2/M transition following the decrease of cyclic adenosine 3′, 5′‐monophosphate (cAMP) and cAMP‐dependent protein kinase (PKA) activity. When cAMP and PKA activity increases again, MPF activity decreases and mouse embryo starts metaphase–anaphase transition. In the downstream of cAMP/PKA, there are some effectors such as polo‐like kinase 1 (Plk1), Cdc25, Mos (mitogen‐activated protein kinase kinase kinase), MEK (mitogen‐activated protein kinase kinase), mitogen‐activated protein kinase (MAPK), Wee1, anaphase‐promoting complex (APC), and phosphoprotein phosphatase that are involved in the regulation of MPF activity. Here, we demonstrated that following activation of MPF, MAPK activity was steady, whereas Plk1 activity fluctuated during the first cell cycle. Plk1 activity was the highest at metaphase and decreased at metaphase–anaphase transition. Further, we established a mathematical model using Gepasi algorithm and the simulation was in agreement with the experimental data. Above all the evidences, we suggested that cAMP and PKA might be the upstream factors which were included in the regulation of the first cell cycle development of mouse embryo. Mol. Reprod. Dev. 75: 489–495, 2008. © 2007 Wiley‐Liss, Inc.
Maturation promoting factor
Wee1
Cite
Citations (10)
Microinjection of the pure inhibitor (1) of cAMP dependent protein kinases (1.5 muM) into Xenopus oocytes triggered 100% germinal vesicle break down (GVBD), faster than progesterone and slower than the maturation promoting factor (MPF). Cholera toxin does not block (I) induced maturation; however cycloheximide inhibits (I) but not MPF induced GVBD.
Germinal vesicle
Maturation promoting factor
Cholera toxin
Cite
Citations (2)
CDK-activating kinase (CAK) phosphorylates threonine 161 (T161) of CDC2, a catalytic subunit of maturation/M-phase promoting factor (MPF), and is essential for MPF activation in mitosis. CAK has been thought to consist of a catalytic subunit, a regulatory subunit and an assembly factor: CDK7, CCNH (also known as cyclin H), and MNAT1 (also known as MAT1), respectively. Although it is known that the meiotic progression of oocytes is regulated by MPF activity, the role of CAK in meiosis is still unclear. In the present study, we attempted to confirm the involvement of CAK in the meiotic progression of porcine immature oocytes. The T161 phosphorylation of CDC2 was found around germinal vesicle breakdown (GVBD) and thereafter from 18 to 48 h of culture. The GVBD rate at 18 h was increased by the overexpression of CDC2 but not mutated CDC2 (T161 replaced by alanine). Transcripts of CDK7, CCNH, and MNAT1 were detectable throughout the culture period, and their protein distribution patterns during oocyte maturation were the same as those reported in mitotic somatic cells. Overexpression of CDK7 or CCNH accelerated the meiotic events, such as meiotic resumption, T161 phosphorylation of CDC2, CCNB (also known as Cyclin B) synthesis, and MPF activation. On the contrary, knockdown of CDK7 or CCNH caused the inhibition of these meiotic events. In contrast, overexpression and antisense RNA injection of MNAT1 had no influence on meiotic resumption, the status of T161 phosphorylation of CDC2, or MPF activity. These results suggest that CDK7 and CCNH activate CDC2 by T161 phosphorylation and make up CAK, which is required for normal meiotic progression during porcine oocyte maturation.
Maturation promoting factor
Germinal vesicle
Cyclin B1
Cyclin B
Cyclin-dependent kinase 7
Cite
Citations (31)