Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The protein kinase inhibitors 2-aminopurine (2-AP) and 6-dimethylaminopurine (6-DMAP) were used to examine the effects of protein dephosphorylation on the control of mitosis in mammalian cells. Both 2-AP and 6-DMAP induced premature mitosis in hamster fibroblasts that were arrested in S phase. This response was characterized by changes in cell morphology, breakdown of the nuclear envelope, and premature chromosome condensation. Premature mitosis was followed by a return to interphase morphology and reformation of the nuclear envelope around decondensed and fragmented chromatin to form numerous micronuclei. The activity of both compounds was dependent upon new protein synthesis but not new RNA synthesis. 2-AP and 6-DMAP acted cooperatively with each other and with caffeine, suggesting a common mechanism of action. In exponentially growing cells, 2-AP and 6-DMAP did not induce premature mitosis but did increase the frequency of binucleated cells by blocking cytokinesis. These findings support a role for protein dephosphorylation in the control of mitosis and indicate that cell cycle perturbations can modify this regulation.
...
PMID:Premature mitosis induced in mammalian cells by the protein kinase inhibitors 2-aminopurine and 6-dimethylaminopurine. 170

The puromycin analog N6,N6-dimethyladenine (6-dimethylaminopurine or 6-DMAP) was found to inhibit meiosis reinitiation in starfish oocytes stimulated by the natural hormone 1-methyladenine. Increasing concentrations of this agent delayed and eventually blocked germinal vesicle breakdown. They were found to be effective even when applied during the hormone-independent period, after the oocytes had been already committed to reinitiate meiosis. 6-DMAP mimics most of the effects of emetine since it induces protein dephosphorylation, inhibits polar body formation, and promotes the precocious appearance of resting nuclei. However, unlike emetine, 6-DMAP does not affect protein synthesis. The effect of this agent cannot be accounted for by a stimulation of the protease or phosphoprotein phosphatase activities since the rate and extent of protein dephosphorylation do not increase in its presence. Data from in vivo and in vitro endogenous protein phosphorylation experiments suggest rather that 6-DMAP may directly or indirectly affect the activity of a relevant c-AMP and Ca2+-independent protein kinase which is stimulated after hormone addition and seems to support starfish oocyte maturation.
...
PMID:6-Dimethylaminopurine blocks starfish oocyte maturation by inhibiting a relevant protein kinase activity. 283 30

The expression of circadian rhythmicity in Gonyaulax polyedra is strikingly altered by an inhibitor of protein phosphorylation. The effects of 6-dimethylaminopurine (6-DMAP), known to reversibly block cell division in many systems through inhibition of protein kinase activity, are described here for Gonyaulax. Its action appears to be exclusively tonic in nature; in cells continuously exposed, the period is lengthened in a concentration-dependent fashion. Shorter treatments at a higher concentration of 6-DMAP (5 mM) apparently stop the circadian oscillator, but reversibly so, since the rhythm resumes after drug removal with a phase delay approximately equal to the duration of the treatment. Pulses of the inhibitor are effective in causing phase delays at all times of the circadian cycle. In addition, 6-DMAP completely blocks light-induced phase advances and is effective in inhibiting many Gonyaulax protein kinases in vitro.
...
PMID:An inhibitor of protein phosphorylation stops the circadian oscillator and blocks light-induced phase shifting in Gonyaulax polyedra. 794 3

Phosphorylation is considered as a common post-translational modification implicated in the control of various key enzymes. In somatic and germinal cells, important regulators of the cell cycle are controlled by their phosphorylation status, and some act as kinases or phosphatases themselves. Bovine oocytes are blocked in the germinal vesicle (GV) stage until either an LH surge occurs or until oocytes are released from the inhibitory influence of the follicle. Meiotic resumption in vitro is therefore an excellent model for the study of phosphorylation events that occur in the G2/M transition, a control point of the cellular cycle. To better understand this transition, we have modulated, either directly or indirectly, kinases using known effectors (epidermal growth factor, EGF; isobutylmethylxanthine-forskolin, Bx-Fk; 6-dimethylaminopurine, 6-DMAP) or phosphatases (okadaic acid, OA) or cycloheximide, which is known to inhibit maturation through protein synthesis suppression. With this procedure, influence on meiotic resumption and phosphoprotein patterns was verified. Both EGF and OA accelerated nuclear maturation after 9 hr of culture. Only 23% (n = 140) and 9% (n = 111) of oocytes were still at GV stage with EGF and OA, respectively, compared to 41% (n = 105) of control oocytes. The different treatments changed the protein patterns in oocytes. In cumulus cells, the patterns were especially modified by the OA treatment. Characteristic changes that occur in germ cells were also identified. Nuclear maturation was inhibited by modulators of kinase (6-DMAP, GV = 74%, n = 126; cAMP dependent protein kinase (PKA) stimulators, Bx-Fk, GV = 71%, n = 129) likewise, phosphoprotein patterns were affected, especially in oocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Effects of different kinases and phosphatases on nuclear and cytoplasmic maturation of bovine oocytes. 856 45

During meiotic maturation or after fertilization of invertebrate and vertebrate oocytes, many of the quiescent stored mRNAs are recruited into polysomes. In the clam, Spisula solidissima, such masked messages include the abundant mRNAs encoding cyclin A and the small subunit of ribonucleotide reductase. We have previously shown that mRNA-specific unmasking of these two messages can be achieved in vitro, in oocyte cell-free extracts, by the addition of antisense RNAs corresponding to a fairly short (130-140 nucleotides) segment in their cognate 3' untranslated regions. We postulated that the antisense RNAs prevented the binding of a masking repressor protein (Standart et al., 1990). Here we report UV-crosslinking and gel retardation studies which show that the masking portions of the translationally regulated mRNAs bind an oocyte protein of 82 kDa (p82), which is phosphorylated after fertilization. This modification was accompanied by altered RNP complex formation in gel retardation assays. These changes presumably reflect the activation of translation of the masked mRNAs. The role of p82 phosphorylation in maternal mRNA unmasking was assessed in a novel in vitro activation system developed from clam oocytes, based upon the natural rise in pH which accompanies fertilization. Concomitant with mRNA unmasking, several kinases, including cdc2 and MAP kinases were activated in this system, as was p82 phosphorylation. Inhibitors of serine/threonine kinases, including 6-DMAP, staurosporine, and H7 inhibited p82 phosphorylation, whereas inhibitors of tyrosine kinases, protein kinase C, cAMP-dependent protein kinase, and p70s6k did not prevent this modification. A specific inhibitor of cdc2 kinase, p27Kip1, prevented p82 phosphorylation and translational activation, strongly suggesting that p82 modification is required for unmasking.
...
PMID:Unmasking mRNA in clam oocytes: role of phosphorylation of a 3' UTR masking element-binding protein at fertilization. 857 30

The high incidence of chromosomally abnormal human embryos is frequently assumed to be due to a lack of checkpoint controls operating during early embryogenesis. In our study we have analysed when these mechanisms first become functional. Mouse oocytes treated in late metaphase I with either of two different cyclin-dependent kinase inhibitors [butyrolactone 1 (BL1) or 6-dimethylaminopurine (6-DMAP)] form nuclei in the cytoplasm. BL1-treated eggs enter S-phase at 16-18 h post-treatment and, after completion of DNA synthesis, cleave to 2-cell stage embryos. 6-DMAP treatment results in the rapid initiation of DNA synthesis, its completion by 12 h and then arrest in the G2 phase. Thus, two different cell cycle stages can be obtained at the same time point after the initiation of treatment: G1- after BL1 and G2-staged nuclei after 6-DMAP treatment. That this approach greatly facilitates cell cycle studies has been shown by analysing checkpoint function during the first division. Whilst G2-staged eggs enter M phase within 2-3 h when 6-DMAP is washed out, the onset of M phase is delayed after their fusion to G1 (BL1) cells. Here M phase occurs only after the less advanced nucleus completes DNA replication. Our results indicate that checkpoints in mammalian eggs are functional during the first mitotic cycle.
...
PMID:Checkpoint control of the G2/M phase transition during the first mitotic cycle in mammalian eggs. 1035 80

To investigate the mechanisms of fertilization in the teleostean egg, the relationship between the nuclear behavior and the activity of histone H1 kinase was examined in medaka, Oryzias latipes, eggs that were anesthetized at sperm penetration. Inseminated in the anesthetized state, most eggs failed to undergo the propagative waves of increase in cytoplasmic Ca(2+) and exocytosis of cortical alveoli (CABD). The sperm-penetrated eggs that exhibited no or partial CABD only around the animal pole underwent a transient contraction of the cortical cytoplasm toward the animal pole region and were designated nonactivated eggs. Temporary compaction of the second meiotic metaphase (MII) chromosomes was accompanied by contractile movement of the cortical cytoplasm, but not by completion of the second meiotic division. The activity of histone H1 kinase in nonactivated eggs remained high, although it decreased slightly concurrent with sperm penetration. Cyclin B and cdc2 levels remained unchanged as well. The nonactivated eggs began to transform the penetrated sperm nucleus into metaphase chromosomes in the cortical cytoplasm facing the inner end of micropylar canal within 20 min postinsemination (PI). Two figures of typical metaphase chromosomes were found in the animal pole area at </=40 min PI. Chromosome condensation in nonactivated eggs was not inhibited by actinomycin D, nor was the high activity of histone H1 kinase reduced. In the presence of cycloheximide or 6-dimethylaminopurine (6-DMAP), however, the compact sperm nucleus and the MII chromosomes transformed to interphase nuclei without CABD or extrusion of the polar body, although the activity of histone H1 kinase remained high. These results suggest that in the fish egg, transformation of MII chromosomes to an interphase nucleus may not be caused by loss of MPF activity, but rather than by the loss of activity of a short-lived protein kinase(s), sensitive to 6-DMAP that is independent of CABD in the cascade reactions triggered by increased cytoplasmic calcium. Copyright 1999 Wiley-Liss, Inc.
...
PMID:Studies on fertilization in the teleost. III. The relationship between nuclear behavior and the histone H1 kinase activity in anesthetized medaka eggs 1044 Aug 48

The effects of the new cyclin-dependent kinase inhibitors, roscovitine and olomoucine, on oocytes and eggs of Xenopus laevis were investigated and compared with those of 6-dimethylamino purine (6-DMAP). The inhibitory properties of 6-DMAP, olomoucine and roscovitine towards p34cdc2-cyclin B isolated from Xenopus eggs revealed K-IC50 values of 300, 40 and 10 microM respectively. The three compounds inhibited progesterone-induced maturation with M-IC50 values of 200, 100 and 20 microM. These values were consistent with the K-IC50 values but the ratio M-IC50/K-IC50 was higher for roscovitine and olomoucine than for 6-DMAP. The disappearance of spindle and condensed chromosomes without pronucleus formation was observed when 1 mM 6-DMAP was applied for 4 h at germinal vesicle breakdown or at metaphase II, whereas no effect was observed using 1 mM olomoucine or 50 microM roscovitine. Changes in the electrophoretic mobility of p34cdc2 and erk2 were observed only in homogenates of matured oocytes or eggs exposed for 4 h to 1 mM 6-DMAP. When the drugs were microinjected into matured oocytes, olomoucine (100 microM) and roscovitine (50 microM) induced pronucleus formation more efficiently than did 6-DMAP (100 microM). Taken together, these results demonstrate that Xenopus oocytes possess a lower permeability to olomoucine and roscovitine and that these new compounds are suitable for in vivo studies after germinal vesicle breakdown provided they are microinjected.
...
PMID:Differential effects of 6-DMAP, olomoucine and roscovitine on Xenopus oocytes and eggs. 1084 Aug 69

Oocyte activation is one of the essential elements determining the success of nuclear transfer and the subsequent development of cloned embryos both in vitro and in vivo. Experiments were conducted to optimize the protocol for oocyte activation in a regular nuclear transfer study. In vivo derived oocytes were collected at 14-15 h from New Zealand white rabbits after ovulation treatment and were activated +18 h post-ovulation treatment. Single activation agents including calcium ionophore (A23187, 5 microM, 5 min), ethanol (Eth, 7%, 7 min), and thimerosal (200 microM, 10 min) were tested. Cleavage rates were highest in the ethanol-treated group (37%) compared to other treatments (19-25%). Very low blastocyst rates (2-3%) resulted which were not significantly different among treatments (P>0.05). Combined single agent treatment (calcium stimulators) with protein kinase inhibitor, 6-DMAP were used to achieve a full oocyte activation. Both pronuclear and blastocyst formation rates were significantly higher (P<0.05) in the Eth+6-DMAP treatment group (38 and 27%) than in the other groups (16-21 and 7-9%, respectively, P<0.05). Low (0.2mM) and high (2.5mM) concentrations of 6-DMAP treatments with different treatment lengths (1.5 and 3.5h) in the combined groups were also compared. Blastocyst formation and cleavage rates were greater in the high concentration with less treatment time groups (36% versus 4-20%, P<0.05). In conclusion, single activation agents, either Ca2+ stimulators or protein kinase inhibitors, could not fully activate mature rabbit oocytes. The best activation procedure obtained in this study was the Eth+6-DMAP combined treatment, which may be incorporated into regular nuclear transfer or cloning protocols.
...
PMID:Parthenogenesis of rabbit oocytes activated by different stimuli. 1194 96

We examined the effect of PGE1 on the expression of plasminogen activator inhibitor-1 (PAI-1) mRNA induced by tumor necrosis factor-alpha (TNF-alpha) in human mesangial cells, because PAI-1 is one of major factors for the progression of glomerulosclerosis. The expression of PAI-1 mRNA was increased after stimulation with TNF-alpha, and it was diminished by pre-incubation with PGE1. Next, we examined the effect of PGE1 on the phosphorylation of mitogen activated protein kinase (MAPK) family and Akt. TNF-alpha activated the phosphorylation of p44/42 MAPK, p38 MAPK, SAPK/JNK and Akt in mesangial cells. PGE1 inhibited the TNF-alpha induced phosphorylation of SAPK/JNK and Akt, but not p44/42 MAPK and p38 MAPK. The TNF-alpha induced expression of PAI-1 mRNA was not affected by PD98059, an inhibitor of MEK, SB203580, an inhibitor of p38 MAPK, nor LY294002, an inhibitor of PI3 K. However, DMAP, an inhibitor of SAPK/JNK, inhibited the expression of PAI-1 mRNA, suggesting that the TNF-alpha induced expression of PAI-1 mRNA is regulated by the SAPK/JNK dependent pathway in human mesangial cells. By the incubation with H8, an inhibitor of PKA, the inhibitory effect of PGE1 on the expression of PAI-1 mRNA was abolished, suggesting that PGE1 inhibited the PAI-1 mRNA expression via the PKA pathway. Our results suggest that the inhibition of PAI-1 synthesis by PGE1 in human mesangial cells may have therapeutic implications for glomerulosclerosis such as occurs in diabetic nephropathy.
...
PMID:PGE1 inhibits the expression of PAI-1 mRNA induced by TNF-alpha in human mesangial cells. 1602 96


1 2 Next >>

---