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1.
Sergiy Kostenko Alexey Shiryaev Nancy Gerits Gianina Dumitriu Helle Klenow Mona Johannessen Ugo Moens 《Cellular and molecular life sciences : CMLS》2011,68(5):847-862
The mitogen-activated protein kinase-activated protein kinase-5 (MK5) resides predominantly in the nucleus of resting cells,
but p38MAPK, extracellular signal-regulated kinases-3 and -4 (ERK3 and ERK4), and protein kinase A (PKA) induce nucleocytoplasmic redistribution
of MK5. The mechanism by which PKA causes nuclear export remains unsolved. In the study reported here we demonstrated that
Ser-115 is an in vitro PKA phosphoacceptor site, and that PKA, but not p38MAPK, ERK3 or ERK4, is unable to redistribute MK5 S115A to the cytoplasm. However, the phosphomimicking MK5 S115D mutant resides
in the cytoplasm in untreated cells. While p38MAPK, ERK3 and ERK4 fail to trigger nuclear export of the kinase dead T182A and K51E MK5 mutants, S115D/T182A and K51E/S115D mutants
were able to enter the cytoplasm of resting cells. Finally, we demonstrated that mutations in Ser-115 affect the biological
properties of MK5. Taken together, our results suggest that Ser-115 plays an essential role in PKA-regulated nuclear export
of MK5, and that it also may regulate the biological functions of MK5. 相似文献
2.
Vandré Casagrande Figueiredo James F. Markworth David Cameron-Smith 《Cellular and molecular life sciences : CMLS》2017,74(14):2537-2545
The mammalian target of rapamycin (mTOR) complex exerts a pivotal role in protein anabolism and cell growth. Despite its importance, few studies adequately address the complexity of phosphorylation of the mTOR protein itself to enable conclusions to be drawn on the extent of kinase activation following this event. In particular, a large number of studies in the skeletal muscle biology field have measured Serine 2448 (Ser2448) phosphorylation as a proxy of mTOR kinase activity. However, the evidence to be described is that Ser2448 is not a measure of mTOR kinase activity nor is a target of AKT activity and instead has inhibitory effects on the kinase that is targeted by the downstream effector p70S6K in a negative feedback loop mechanism, which is evident when revisiting muscle research studies. It is proposed that this residue modification acts as a fine-tuning mechanism that has been gained during vertebrate evolution. In conclusion, it is recommended that Ser2448 is an inadequate measure and that preferential analysis of mTORC1 activation should focus on the downstream and effector proteins, including p70S6K and 4E-BP1, along mTOR protein partners that bind to mTOR protein to form the active complexes 1 and 2. 相似文献
3.
S. P. Yun M. Y. Lee J. M. Ryu H. J. Han 《Cellular and molecular life sciences : CMLS》2009,66(9):1603-1616
Identifying the small molecules that permit precise regulation of embryonic stem (ES) cell proliferation should further support
our understanding of the underlying molecular mechanisms of self renewal. In the present study, we showed that PGE2 increased [3H]-thymidine incorporation in a time and dose dependent manner. In addition, PGE2 increased the expression of cell cycle regulatory proteins, the percentage of cells in S phase and the total number of cells.
PGE2 obviously increased E-type prostaglandin (EP) receptor 1 mRNA expression level compare to 2, 3, 4 subtypes. EP1 antagonist
also blocked PGE2-induced cell cycle regulatory protein expression and thymidine incorporation. PGE2 caused phosphorylation of protine kinase C, Src, epidermal growth factor (EGF) receptor, phosphatidylinositol 3-kinase (PI3K)/Akt
phosphorylation, and p44/42 mitogen-activated protein kinase (MAPK), which were blocked by each inhibitors. In conclusion,
PGE2-stimulated proliferation is mediated by MAPK via EP1 receptor-dependent PKC and EGF receptor-dependent PI3K/Akt signaling
pathways in mouse ES cells.
Received 30 January 2009; received after revision 03 March 2009; accepted 10 March 2009 相似文献
4.
Liu ZM Chen GG Vlantis AC Tse GM Shum CK van Hasselt CA 《Cellular and molecular life sciences : CMLS》2007,64(11):1428-1436
The molecular mechanism responsible for cadmium-induced cell death in thyroid cancer cells (FRO) is unknown. We demonstrated
that apoptosis of FRO cells induced by cadmium was concentration and time dependent. Cadmium caused the rapid elevation of
intracellular calcium and induced phosphorylation of Akt, p53, JNK, ERK and p38. Inhibition of PI3K/Akt attenuated the cadmium-induced
apoptosis, but the inhibition of JNK inhibitor, ERK or p38 aggravated it, indicating that activation of PI3K/Akt was a pro-apoptosis
signal in response to cadmium treatment, whereas the activation of stress-activated protein kinase JNK, ERK and p38 functioned
as survival signals to counteract the cadmium-induced apoptosis. Buffering of the calcium response attenuated mitochondrial
impairment, recovered the cadmium-activated Akt, p53, JNK, ERK and p38, and subsequently blocked the apoptosis. These results
suggested that apoptosis induced by cadmium in FRO cells was initiated by the rapid elevation of intracellular calcium, followed
by calcium-mediated activation of PI3K/Akt and mitochondrial impairment.
Received 28 February 2007; received after revision 2 April 2007; accepted 23 April 2007 相似文献
5.
6.
The Wnt/β-catenin signaling pathway plays important roles in embryonic development and tissue homeostasis, and is implicated
in human disease. Wnts transduce signals via transmembrane receptors of the Frizzled (Fzd/Fz) family and the low density lipoprotein
receptor-related protein 5/6 (Lrp5/6). A key mechanism in their signal transduction is that Wnts induce Lrp6 signalosomes,
which become phosphorylated at multiple conserved sites, notably at PPSPXS motifs. Lrp6 phosphorylation is crucial to β-catenin
stabilization and pathway activation by promoting Axin and Gsk3 recruitment to phosphorylated sites. Here, we summarize how
proline-directed kinases (Gsk3, PKA, Pftk1, Grk5/6) and non-proline-directed kinases (CK1 family) act upon Lrp6, how the phosphorylation
is regulated by ligand binding and mitosis, and how Lrp6 phosphorylation leads to β-catenin stabilization. 相似文献
7.
8.
The effects of serotonin on the formation of inositol phosphates and protein phosphorylation were examined in cultured smooth muscle cells. Serotonin stimulated the formation of [3H]inositol monophosphate, [3H]inositol bisphosphate and [3H]inositol trisphosphate. This effect was prevented by 5-HT2 specific antagonist, 6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid, 2-hydroxy-1-methylpropyl ester [Z]-2-butenedioate (LY53857). Serotonin stimulated the phosphorylation of many polypeptides, among which a 20 kDa polypeptide was the most prominent. The phosphorylation was also inhibited by LY53857. LY53857 alone produced no effects on protein phosphorylation. The 20 kDa polypeptides were also phosphorylated by the addition of 12-O-tetradecanoylphorbol-13-acetate. These results suggest that serotonin stimulates protein phosphorylation through 5-HT2 receptors and possibly activates protein kinase C in intact vascular smooth muscle cells. 相似文献
9.
10.
Felipe Ortega Raquel Pérez-Sen Verónica Morente Esmerilda G. Delicado Maria Teresa Miras-Portugal 《Cellular and molecular life sciences : CMLS》2010,67(10):1723-1733
Glycogen synthase kinase-3 (GSK3) is a key player in the regulation of neuronal survival. Herein, we report evidence of an
interaction between P2X7 receptors with NMDA and BDNF receptors at the level of GSK3 signalling and neuroprotection. The activation
of these receptors in granule neurons led to a sustained pattern of GSK3 phosphorylation that was mainly PKC-dependent. BDNF
was the most potent at inducing GSK3 phosphorylation, which was also dependent on PI3K. The P2X7 agonist, BzATP, exhibited
additive effects with both NMDA and BDNF to rescue granule neurons from cell death induced by PI3K inhibition. This survival
effect was mediated by the PKC-dependent GSK3 pathway. In addition, ERK1/2 proteins were also involved in BDNF protective
effect. These results show the function of ATP in amplifying neuroprotective actions of glutamate and neurotrophins, and support
the role of GSK3 as an important convergence point for these survival promoting factors in granule neurons. 相似文献
11.
The steel factor (SLF) and c-Kit growth factor/receptor pair are key molecules governing mast cell development and survival. SLF is expressed on stromal cells as a membrane-bound molecule (mSLF) which can be cleaved by proteases to release a soluble form (sSLF). We investigated the importance of phospholipase C (PLC) activation in mast cells stimulated by sSLF and mSLF. PLC antagonists U73122, neomycin sulfate and oleic acid inhibited mast cell thymidine incorporation stimulated by mSLF, but not by sSLF. These antagonists suppressed sSLF-induced Ca2+ transients but did not significantly interfere with c-Kit phosphorylation or PLC-gamma2 recruitment. p85, the regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase), was found to be efficiently recruited to c-Kit following stimulation by sSLF or mSLF. However PKB/Akt, a kinase activated by PI3-kinase products, was phosphorylated following sSLF stimulation, but not with mSLF. Taken together, these studies demonstrate the importance of PLC activation by mSLF in supporting mast cells. 相似文献
12.
The rapid migration of intestinal epithelial cells (IEC) is important for the healing of mucosal wounds. We have previously
shown that polyamine depletion inhibits migration of IEC-6 cells. Akt activation and its downstream target GSK-3β have been
implicated in the regulation of migration. Here we investigated the significance of elevated phosphatidylinositol 3-kinase
(PI3K)/Akt signaling on migration of polyamine-depleted cells. Polyamine-depleted cells had high Akt (Ser473) and GSK-3β (Ser9)
phosphorylation. Pretreatment with 20 μM LY294002 (PI3K inhibitor) for 30 min inhibited phosphorylation of Akt, increased
migration by activating Rac1 in polyamine-depleted IEC-6 cells, and restored the actin structure similar to that in cells
grown in control medium. Treatment of cells with a GSK-3β inhibitor (AR-A014418) altered the actin cytoskeleton and inhibited
migration, mimicking the effects of polyamine depletion. Thus, our results indicate that sustained activation of Akt in response
to polyamine depletion inhibits migration through GSK-3β and Rac1.
Received 25 August 2006; received after revision 3 October 2006; accepted 16 October 2006 相似文献
13.
Huiyu Low Chun Song Chua Tiow-Suan Sim 《Cellular and molecular life sciences : CMLS》2009,66(18):3081-3090
A mitogen-activated protein kinase (MAPK), Pfmap2, has been identified in Plasmodium falciparum. However, its bona fide activator remains elusive as no MAPK kinase (MAPKK) homologues have been found so far. Instead, Pfnek3,
a NIMA (never in mitosis, Aspergillus)-related kinase, was earlier reported to display a MAPKK-like activity due to its activating effect on Pfmap2. In this study,
the regulatory mechanism of Pfnek3 was investigated. Pfnek3 was found to possess a SSEQSS motif within its activation loop
that fulfills the consensus SXXXS/T phospho-activating sequence of MAPKKs. Functional analyses of the SSEQSS motif by site-directed
mutagenesis revealed that phosphorylation of residues S221 and S226 is essential for mediating Pfnek3 activity. Moreover,
via tandem mass-spectrometry, residue T82 was uncovered as an additional phosphorylation site involved in Pfnek3 activation.
Collectively, these results provide valuable insights into the potential in vivo regulation of Pfnek3, with residues T82,
S221 and S226 functioning as phospho-activating sites. 相似文献
14.
15.
Wang QY Guo P Duan LL Shen ZH Chen HL 《Cellular and molecular life sciences : CMLS》2005,62(2):171-178
After the transfection of -1,3-fucosyltransferase (FucT)-VII cDNA into H7721 human hepatocarcinoma cells, the protein expression of some cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDIs) p16INK4 and p21waf1/Cip1 were unchanged. However, CDI p27Kip1 protein, both the total amount and the amount that bound to CDK2, but not its mRNA, was significantly reduced. The de-inhibited CDK2 stimulated the phosphorylation of retinoblastoma (Rb) protein and facilitated the G1/S transition and growth rate of the cells. The decrease of p27Kip1 protein, the increase of CDK2 activity and Rb phosphorylation, as well as the cell growth and percentage of S phase cells were correlated to the increased amount of cell surface sialyl Lewis X (SLex) antigen in cells with different -1,3-FucT-VII expression. The reduction in p27Kip1 and the difference in its expression among different transfected cells were blocked by the SLex antibody KM93 in a dose-dependent manner, indicating that p27Kip1 expression was influenced by -1,3-FucT-VII and its product SLex. The MEK/MAPK signaling pathway was more important than the PI-3K pathway in the regulation of p27Kip1 expression.Received 5 August 2004; received after revision 25 October 2004; accepted 11 November 2005 相似文献
16.
T. Nakaki B. C. Wise D. M. Chuang R. Kato 《Cellular and molecular life sciences : CMLS》1989,45(9):879-881
Summary The effects of serotonin on the formation of inositol phosphates and protein phosphorylation were examined in cultured smooth muscle cells. Serotonin stimulated the formation of [3H]inositol monophosphate, [3H]inositol bisphosphate and [3H]inositol trisphosphate. This effect was prevented by 5-HT2 specific antagonist, 6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid, 2-hydroxy-1-methylpropyl ester [Z]-2-butenedioate (LY53857). Serotonin stimulated the phosphorylation of many polypeptides, among which a 20 kDa polypeptide was the most prominent. The phosphorylation was also inhibited by LY53857. LY53857 alone produced no effects on protein phosphorylation. The 20 kDa polypeptides were also phosphorylated by the addition of 12-O-tetradecanoylphorbol-13-acetate. These results suggest that serotonin stimulates protein phosphorylation through 5-HT2 receptors and possibly activates protein kinase C in intact vascular smooth muscle cells.Part of the data contained in this paper was presented at the 74th local meeting of the Japanese Society of Pharmacology at Kanagawa. 相似文献
17.
A. Deshmukh F. Salehzadeh S. Metayer-Coustard R. Fahlman K. S. Nair L. Al-Khalili 《Cellular and molecular life sciences : CMLS》2009,66(8):1457-1466
Excessive nutrients, especially amino acids, impair insulin action on glucose metabolism in skeletal muscle. We tested the
hypothesis that the branched-chain amino acid leucine reduces acute insulin action in primary myotubes via a negative feedback mechanism involving ribosomal protein S6 kinase 1 (S6K1). The effect of S6K1 on glucose metabolism was
determined by applying RNA interference (siRNA). Leucine (5 mM) reduced glucose uptake and incorporation to glycogen by 13%
and 22%, respectively, compared to the scramble siRNA-transfected control at the basal level. Leucine also reduced insulin-stimulated
Akt phosphorylation, glucose uptake and glucose incorporation to glycogen (39%, 39% and 37%, respectively), and this reduction
was restored after S6K1 silencing. Depletion of S6K1 enhanced basal glucose utilization and protected against the development
of impaired insulin action, in response to excessive leucine. In conclusion, S6K1 plays an important role in the regulation
of insulin action on glucose metabolism in skeletal muscle.
Received 22 December 2008; received after revision 19 February 2009; accepted 23 February 2009 相似文献
18.
Pan Q Qiao F Gao C Norman B Optican L Zelenka PS 《Cellular and molecular life sciences : CMLS》2011,68(20):3425-3436
The non-receptor tyrosine kinase Src is a critical regulator of cytoskeletal contraction, cell adhesion, and migration. In
normal cells, Src activity is stringently controlled by Csk-dependent phosphorylation of Src(Y530), and by Cullin-5-dependent
ubiquitinylation, which affects active Src(pY419) exclusively, leading to its degradation by the proteosome. Previous work
has shown that Src activity is also limited by Cdk5, a proline-directed kinase, which has been shown to phosphorylate Src(S75).
Here we show that this phosphorylation promotes the ubiquitin-dependent degradation of Src, thus restricting the availability
of active Src. We demonstrate that Src(S75) phosphorylation occurs in vivo in epithelial cells, and like ubiquitinylation,
is associated only with active Src. Preventing Cdk5-dependent phosphorylation of Src(S75), by site-specific mutation of S75
or by Cdk5 inhibition or suppression, increases Src(Y419) phosphorylation and kinase activity, resulting in Src-dependent
cytoskeletal changes. In transfected cells, ubiquitinylation of Src(S75A) is about 35% that of wild-type Src-V5, and its half-life
is approximately 2.5-fold greater. Cdk5 suppression leads to a comparable decrease in the ubiquitinylation of endogenous Src
and a similar increase in Src stability. Together, these findings demonstrate that Cdk5-dependent phosphorylation of Src(S75)
is a physiologically significant mechanism of regulating intracellular Src activity. 相似文献
19.
Lena Golick Youngah Han Yoo Kim Sang Won Park 《Cellular and molecular life sciences : CMLS》2018,75(10):1857-1869
Reduced hepatic expression levels of bromodomain-containing protein 7 (BRD7) have been suggested to play a role in the development of glucose intolerance in obesity. However, the molecular mechanism by which BRD7 regulates glucose metabolism has remained unclear. Here, we show that BRD7 increases phosphorylation of glycogen synthase kinase 3β (GSK3β) in response to activation of the insulin receptor-signaling pathway shortly after insulin stimulation and the nutrient-sensing pathway after feeding. BRD7 mediates phosphorylation of GSK3β at the Serine 9 residue and this effect on GSK3β occurs even in the absence of AKT activity. Using both in vitro and in vivo models, we further demonstrate that BRD7 mediates phosphorylation of ribosomal protein S6 kinase (S6K) and leads to increased phosphorylation of the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and, therefore, relieves its inhibition of the eukaryotic translation initiation factor 4E (eIF4E). However, the increase in phosphorylation of 4E-BP1 with BRD7 overexpression is blunted in the absence of AKT activity. In addition, using liver-specific BRD7 knockout (LBKO) mice, we show that BRD7 is required for mTORC1 activity on its downstream molecules. These findings show a novel basis for understanding the molecular dynamics of glucose metabolism and suggest the unique function of BRD7 in the regulation of glucose homeostasis. 相似文献
20.
Shachi P. Patel Suzanne J. Randle Sarah Gibbs Anne Cooke Heike Laman 《Cellular and molecular life sciences : CMLS》2017,74(8):1553-1566
G1 phase cell cycle proteins, such as cyclin-dependent kinase 6 (Cdk6) and its activating partners, the D-type cyclins, are important regulators of T-cell development and function. An F-box protein, called F-box only protein 7 (Fbxo7), acts as a cell cycle regulator by enhancing cyclin D-Cdk6 complex formation and stabilising levels of p27, a cyclin-dependent kinase inhibitor. We generated a murine model of reduced Fbxo7 expression to test its physiological role in multiple tissues and found that these mice displayed a pronounced thymic hypoplasia. Further analysis revealed that Fbxo7 differentially affected proliferation and apoptosis of thymocytes at various stages of differentiation in the thymus and also mature T-cell function and proliferation in the periphery. Paradoxically, Fbxo7-deficient immature thymocytes failed to undergo expansion in the thymus due to a lack of Cdk6 activity, while mature T cells showed enhanced proliferative capacity upon T-cell receptor engagement due to reduced p27 levels. Our studies reveal differential cell cycle regulation by Fbxo7 at different stages in T-cell development. 相似文献