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Query: EC:2.7.11.1 (
protein kinase
)
81,284
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
MRL-lpr/lpr mice have a Fas receptor mutation that leads to abnormalities of apoptosis, lymphoproliferation, and a lupus-like autoimmune disease associated with the production of autoantibodies. Other than Fas pathway defects, little is known about molecular abnormalities that predispose to autoimmunity. Protein kinase CK2 (also termed
casein kinase II
), a
serine-threonine protein kinase
whose targets include many critical regulators of cellular growth, is highly expressed in a lymphoproliferative disease of cattle and in many human cancers. Overexpression of the CK2alpha catalytic subunit in lymphocytes of transgenic mice leads to T cell lymphoma. We hypothesized that CK2 dysregulation and Fas mutation might cooperatively augment lymphocyte proliferation and transformation. We find that in MRL-lpr/lpr mice bearing the CK2alpha transgene, the lymphoproliferative process is dramatically exacerbated, as these mice develop massive splenomegaly and lymphadenopathy by 12 wk of age in association with increased autoantibody production and accelerated renal disease. The lymphoid organs are filled with the unusual B220+CD4-CD8- T cells typically seen in MRL-lpr/lpr mice, not the B220-CD4+CD8+ or B220-CD4-CD8+ T cells typically seen in CK2a transgenic lymphomas. The T cells do not fulfill the criteria for transformation, as they are polyclonal and not transplantable or immortal in cell culture. Thus, although the lpr lymphoproliferative and autoimmune syndrome is potentiated by the presence of the CK2a transgene, this combination of apoptotic and proliferative abnormalities appears to be insufficient to transform lymphoid cells.
...
PMID:Acceleration of lpr lymphoproliferative and autoimmune disease by transgenic protein kinase CK2 alpha. 982 Apr 86
Raf is a key
serine-threonine protein kinase
which participates in the transmission of growth, anti-apoptotic and differentiation messages. These signals can be initiated after receptor ligation and are transmitted to members of the MAP kinase cascade that subsequently activate transcription factors controlling gene expression. Raf is a member of a multigene family which includes:
Raf-1
, A-Raf and B-Raf. The roles that individual Raf kinases play in the regulation of normal and malignant hematopoietic cell growth are not clear. The following studies show that all three Raf kinases are functionally present in certain human hematopoietic cells, and their aberrant expression can result in abrogation of cytokine dependency. Cytokine-dependent TF-1 cells were infected with retroviruses encoding amino-terminal deleted (delta) A-Raf, B-Raf and
Raf-1
proteins. These Raf proteins were conditionally inducible as they were fused to the hormone-binding domain of the estrogen receptor (ER). A hierarchy in the abilities of Raf-containing retroviruses to abrogate cytokine dependency was observed as deltaA-Raf:ER was 20- to 200-fold more efficient than either deltaRaf-1:ER or deltaB-Raf:ER, respectively. This result was unexpected as A-Raf is an intrinsically weaker kinase than either
Raf-1
or B-Raf. The activated Raf proteins induced downstream MEK and MAP (ERK1 and ERK2) kinase activities in the cells which proliferated in response to Raf activation. Furthermore, a functional MEK signaling pathway was necessary as treatment of the cells with a MEK1-inhibitor suppressed Raf-mediated proliferation. To determine whether the regulatory phosphorylation residues contained in the modified Raf oncoproteins were necessary for transformation, they were altered by site-directed mutagenesis. Substitution of the regulatory phosphorylation tyrosine residues with phenylalanine in either A-Raf or
Raf-1
reduced the capacity of these oncoproteins to abrogate cytokine dependency. In contrast, changing the critical aspartic acid residues of B-Raf to either tyrosine or phenylalanine increased the frequency of estradiol-responsive cells. Thus, the amino acids present in the regulatory residues modulated the capability of Raf proteins to abrogate the cytokine dependency of TF-1 cells. Differences in the levels of Raf and downstream kinase activities were observed between cytokine-dependent and estradiol-responsive deltaRaf:ER-infected cells as estradiol-responsive cells usually expressed more Raf and MEK activity than GM-CSF-dependent, deltaRaf:ER-infected cells. Abrogation of cytokine dependency by the activated deltaRaf:ER proteins was associated with autocrine growth factor synthesis which was sufficient to promote the growth of uninfected TF-1 cells. In summary, these observations indicate that the aberrant expression of certain activated deltaRaf:ER oncoproteins can alter the cytokine dependency of human hematopoietic TF-1 cells. These cells will be useful in evaluating the roles of the individual Raf oncoproteins in signal transduction, cell cycle progression, autocrine transformation, regulation of apoptosis and differentiation. Moreover, these Raf-infected cells may be important in evaluating the efficacy of novel anticancer drugs designed to inhibit Raf and downstream signal transduction molecules.
...
PMID:Differential abilities of activated Raf oncoproteins to abrogate cytokine dependency, prevent apoptosis and induce autocrine growth factor synthesis in human hematopoietic cells. 984 21
Protein kinase CK2 (
casein kinase II
) is a
serine-threonine protein kinase
with a wide range of substrates, many of which are involved in cell cycle regulation. CK2 activity is elevated in a variety of human tumors and we have used a transgenic mouse model to demonstrate that dysregulated expression of CK2 can induce lymphoma. Thus, CK2 fulfills the definition of an oncogene: A mutated, dysregulated, or mis-expressed gene that contributes to cancer in a dominant fashion. CK2 cooperates in transforming cells with other lymphoid oncogenes such as myc and tal-1, and here we show cooperativity with loss of the tumor suppressor gene p53. To understand more about the physiological and pathological role of CK2, we are cloning the murine CK2alpha' cDNA and gene. CK2alpha' will be used to generate transgenic and knockout mice and the regulatory elements for gene expression will be analyzed.
...
PMID:Murine protein kinase CK2: gene and oncogene. 1009 94
Ca2+/calmodulin dependent
protein kinase
IV (CaMKIV) is a multifunctional,
serine-threonine protein kinase
that is activated in the presence of increased intracellular calcium (Ca2+). CaMKIV is a potent mediator of Ca2+ induced gene expression, primarily through its ability to phosphorylate and activate transcription factors such as CREB. CaMKIV-dependent activation of CREB is a key event in the expression of genes involved in the processes of T-cell activation and neuronal long term potentiation. The focus of this review is to describe the biochemical regulation of CaMKIV and examine how CaMKIV activates transcription in response to calcium in both cell and animal models.
...
PMID:Ca2+/calmodulin-dependent protein kinase IV and calcium signaling. 1019 97
BRCA1 is a cell cycle-regulated nuclear protein that is phosphorylated mainly on serine and to a lesser extent on threonine residues. Changes in phosphorylation occur in response to cell cycle progression and DNA damage. Specifically, BRCA1 undergoes hyperphosphorylation during late G1 and S phases of the cell cycle. Here we report that BRCA1 is phosphorylated in vivo at serine 1497 (S1497), which is part of a
cyclin-dependent kinase
(
CDK
) consensus site. S1497 can be phosphorylated in vitro by CDK2-cyclin A or E. BRCA1 coimmunoprecipitates with an endogenous
serine-threonine protein kinase
activity that phosphorylates S1497 in vitro. This cellular kinase activity is sensitive to transfection of a dominant negative form of CDK2 as well as the application of the
CDK
inhibitors p21 and butyrolactone I but not p16. Furthermore, BRCA1 coimmunoprecipitates with CDK2 and cyclin A. These results suggest that the endogenous kinase activity is composed of CDK2-cyclin complexes, at least in part, concordant with the G1/S-specific increase in BRCA1 phosphorylation.
...
PMID:BRCA1 is phosphorylated at serine 1497 in vivo at a cyclin-dependent kinase 2 phosphorylation site. 1037 34
This study tests the hypothesis that activation of protein kinase C (PKC) is a critical step for early recovery from spontaneous nystagmus after unilateral ablation of the vestibular periphery. Halothane-NO(2)-O(2)-anesthetized Long-Evans rats received a 5-microl intracerebroventricular bolus of vehicle (distilled water, six rats), PKC inhibitor [Iso-H-7 (10 mM, four rats; 50 mM, five rats) or bisindolemaleimide I (Bis-I, 10 microM six rats)], PKG and
PKA
inhibitor (A-3, 1 mM, six rats), or the
serine-threonine protein kinase
inhibitor H-7 (1 mM, five rats; 10 mM, five rats). Surgical unilateral labyrinthectomy (UL) was completed within 15 min. Sham control groups showed no nystagmus. Bis-I and Iso-H-7 significantly retarded the disappearance of spontaneous nystagmus quick phases for 8 h after UL (p<0.05). The effects of Iso-H-7 were dose-dependent: more nystagmus quick phases (p<0.05) were present in the 50 mM than the 10 mM group at 7 and 8 h post-UL. The rats given A-3 showed a delayed retardation of nystagmus loss, which differed significantly (p<0.05) from controls at 4-8 h after labyrinthectomy. The number of nystagmus quick phases was significantly greater than controls (p<0. 05) in the 10 mM H-7 group at 4, 5, 6 and 48 h post-UL, but only at 6 and 24 h post-UL in the 1 mM H-7 group. Thus, PKC activation is an important early requirement for vestibular compensation during the acute post-labyrinthectomy period, while cyclic-nucleotide dependent kinases may be important in a later time frame.
...
PMID:Protein kinase C inhibition blocks the early appearance of vestibular compensation. 1052 48
The Ras oncogene regulates cellular proliferation, differentiation, transformation, and survival through multiple downstream signals. Ras signals through its effector phosphoinositide 3 (PI3) kinase to the Pak
protein kinase
(p65(pak)), but the steps from Ras to Pak remain to be elucidated. PI3 kinase can stimulate the small G protein, Rac, a direct activator of Pak, as well as the Akt proto-oncogene, a
serine-threonine protein kinase
. We found that activated Akt stimulated Pak, whereas a dominant negative Akt inhibited Ras activation of Pak in transfection assays. Akt stimulation of Pak was not inhibited by dominant negative mutants of either Rac or Cdc42 suggesting that Akt activated Pak through a GTPase-independent mechanism. We also developed a novel cell-free system to study Ras activation of Pak. In this system Ras activated Pak only in the presence of a crude cell extract but failed to activate Pak when Akt was immunodepleted from the extract. Akt protects cells from apoptosis through phosphorylation of downstream targets such as the Bcl-2 family member, Bad. We found that activated Pak decreased apoptosis and increased phosphorylation of Bad, whereas dominant negative Pak increased apoptosis and decreased phosphorylation of Bad. These studies define a new oncogene-mediated cell survival signal.
...
PMID:The Akt proto-oncogene links Ras to Pak and cell survival signals. 1073 42
Pulmonary neuroendocrine cells function as hypoxia-sensitive chemoreceptors, and they release peptides and biogenic amines that are important mediators of pulmonary neonatal adaptation. Some of these products additionally act as autocrine growth factors. Increased numbers of pulmonary neuroendocrine cells have been observed in several smoking-associated pediatric lung disorders such as bronchopulmonary dysplasia, cystic fibrosis, sudden infant death syndrome, and asthma. Disturbed pulmonary neuroendocrine function has been implicated in the etiology of this disease complex. One of the most common smoking-associated lung cancer types, small cell lung carcinoma, expresses phenotypic and functional features of pulmonary neuroendocrine cells. We, as well as others, have shown that the release of the autocrine growth factors 5-hydroxytryptamine (5-HT, serotonin) and mammalian bombesin/gastrin releasing peptide (MB/GRP) by cell lines derived from human small cell lung carcinoma or fetal hamster pulmonary neuroendocrine cells are regulated by a neuronal nicotinic acetylcholine receptor comprised of alpha(7) subunits. In radio-receptor assays, nicotine and the nicotine-derived carcinogenic nitrosamines NNNN. Binding of nicotine or NNK to the alpha(7) receptor resulted in calcium influx and overexpression and activation of the
serine-threonine protein kinase
Raf-1
. In turn, this event lead to overexpression and activation of the mitogen activated (MAP) kinases extracellular signal regulated kinase 1 (ERK1) and extracellular signal regulated kinase 2 (ERK2) and stimulation of DNA synthesis accompanied by an increase in cell numbers in fetal pulmonary neuroendocrine cells and small cell carcinoma cells. Exposure of fetal pulmonary neuroendocrine cells for 6 days to NNK caused a prominant up-regulation of
Raf-1
. Our findings suggest that chronic exposure to nicotine and NNK in pregnant women who smoke may up-regulate the alpha(7) nicotinic receptor as well as components of its associated mitogenic signal transduction pathway, thus increasing the susceptibilities of the infants for the development of pediatric lung disorders. Similarly, up-regulation of one or several components of this nicotinic receptor pathway in smokers may be an important factor for the development of small cell lung carcinoma.
...
PMID:Interaction of tobacco-specific toxicants with the neuronal alpha(7) nicotinic acetylcholine receptor and its associated mitogenic signal transduction pathway: potential role in lung carcinogenesis and pediatric lung disorders. 1077 Oct 23
The p21-activated kinase (PAK1) is a
serine-threonine protein kinase
that is activated by binding to the Rho family small G proteins Rac and Cdc42hs. Both Rac and Cdc42hs have been shown to regulate the activity of the transcription factor NFkappaB. Here we show that expression of active Ras,
Raf-1
, or Rac1 in fibroblasts stimulates NFkappaB in a PAK1-dependent manner and that expression of active PAK1 can stimulate NFkappaB on its own. Similarly, in macrophages activation of NFkappaB as well as transcription from the tumor necrosis factor alpha promoter depends on PAK1. In these cells lipopolysaccharide is a potent activator of PAK1 kinase activity. We also demonstrate that expression of active PAK1 stimulates the nuclear translocation of the p65 subunit of NFkappaB but does not activate the inhibitor of kappaB kinases alpha or beta. These data demonstrate that PAK1 is a crucial signaling molecule involved in NFkappaB activation by multiple stimuli.
...
PMID:Stimulation of NFkappa B activity by multiple signaling pathways requires PAK1. 1077 25
Myotonic dystrophy protein kinase (DMPK) is a
serine-threonine protein kinase
encoded by the myotonic dystrophy (DM) locus on human chromosome 19q13.3. It is a close relative of other kinases that interact with members of the Rho family of small GTPases. We show here that the actin cytoskeleton-linked GTPase Rac-1 binds to DMPK, and coexpression of Rac-1 and DMPK activates its transphosphorylation activity in a GTP-sensitive manner. DMPK can also bind
Raf-1
kinase, the Ras-activated molecule of the MAP kinase pathway. Purified
Raf-1
kinase phosphorylates and activates DMPK. The interaction of DMPK with these distinct signals suggests that it may play a role as a nexus for cross-talk between their respective pathways and may partially explain the remarkable pleiotropy of DM.
...
PMID:Rac-1 and Raf-1 kinases, components of distinct signaling pathways, activate myotonic dystrophy protein kinase. 1086 70
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