Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

A number of clinical observations concerning cases of glycemic fluctuation have prompted us to study whether or not a rapid change in blood glucose concentration can aggravate retinal microvascular pathology during the early stage of diabetic retinopathy. We conducted a comparative study of retinal capillary pericytes and endothelial cells in vitro. Both types of cells, either in single culture or in co-culture, were initially incubated in medium with high glucose (20-40 mmol/l), followed by a rapid reduction of glucose to 3.5, 1, or 0.5 mmol/1. This type of reduction of extracellular glucose resulted in depletion of intracellular glucose, occurring much faster in pericytes than in endothelial cells. The abrupt reduction in glucose caused pericyte cell shrinkage and nuclear condensation associated with DNA fragmentation, followed by loss of cell viability. All of these pericyte changes are apoptosis-like characteristics. This apoptotic process was prevented by the addition of cycloheximide, a protein synthesis inhibitor, or by platelet-derived growth factor BB, which is known competent factor for pericyte growth. In analysis of signalling pathways during the abrupt fluctuation of glucose, the occurrence of pericyte apoptosis was an intracellular calcium-dependent, protein kinase C and protein kinase A mediated, and poly (ADP-ribose) synthetase-dependent process. Interestingly, a larger degree of DNA fragmentation was observed with a higher magnitude and a longer duration of pre-existing hyperglycaemia. These results suggest that the magnitude and duration of pre-existing hyperglycaemia prime the apoptotic responsiveness of pericytes. Retinal capillary endothelial cells, after an identical glucose fluctuation treatment did not undergo an apoptotic process.
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PMID:Cultured retinal capillary pericytes die by apoptosis after an abrupt fluctuation from high to low glucose levels: a comparative study with retinal capillary endothelial cells. 873 13

In recent years, several laboratories have explored the possibility of using antisense oligodeoxynucleotides for specific manipulation of gene expression leading to cancer treatment. The enhanced expression of the RIalpha subunit of cyclic AMP-dependent protein kinase type I (PKA-I) has been correlated with cancer cell growth. In the present study, the effects of an antisense oligodeoxynucleotide targeted against RIalpha subunit of PKA-I on growth inhibition and apoptosis in MDA-MB-231 human breast cancer cells were investigated. The growth inhibitory effects of RIalpha antisense oligodeoxynucleotide correlated with a decrease in the RIalpha mRNA and protein levels. The growth inhibition was accompanied by changes in the cell cycle phase distribution, cell morphology, cleavage of poly (ADP-ribose) polymerase (PARP), and appearance of apoptotic nuclei. By comparison, mismatched control oligodeoxynucleotide had no effect. On the basis of these results, it can be suggested that the RIalpha antisense oligodeoxynucleotide, which efficiently depletes the growth stimulatory RIalpha and induces apoptosis/differentiation, could be used as a therapeutic agent for breast cancer treatment.
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PMID:Antisense depletion of RIalpha subunit of protein kinase A induces apoptosis and growth arrest in human breast cancer cells. 969 92

Anchorage removal like growth factor removal induces apoptosis. In the present study we have characterized signaling pathways that can prevent this cell death using a highly growth factor- and anchorage-dependent line of lung fibroblasts (CCL39). After anchorage removal from exponentially growing cells, annexin V-FITC labeling can be detected after 8 h. Apoptosis was confirmed by analysis of sub-G1 DNA content and Western blotting of the caspase substrate poly (ADP-ribose) polymerase. Growth factor withdrawal accelerates and potentiates suspension-induced cell death. Activation of Raf-1 kinase in suspension cultures of CCL39 or Madin-Darby canine kidney cells stably expressing an estrogen-inducible activated-Raf-1 construct (DeltaRaf-1:ER) suppresses apoptosis induced by growth factor and/or anchorage removal. This protective effect appears to be mediated by the Raf, mitogen- or extracellular signal-regulated kinase kinase (MEK), and mitogen-activated protein kinase module because it is sensitive to pharmacological inhibition of MEK-1 and it can be mimicked by expression of constitutively active MEK-1 in CCL39 cells. Finally, apoptosis induced by disruption of the actin cytoskeleton with the Rho-directed toxin B (Clostridium difficile) is prevented by activation of the DeltaRaf-1:ER chimeric construct. These findings highlight the ability of p42/p44 mitogen-activated protein kinase to generate survival signals that counteract cell death induced by loss of matrix contact, cytoskeletal integrity, and extracellular mitogenic factors.
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PMID:The p42/p44 MAP kinase pathway prevents apoptosis induced by anchorage and serum removal. 1071 23

Cell death by apoptosis is an efficient mechanism of eliminating unwanted or aberrant cells. Triggering of Fas, a member of the tumor necrosis factor (TNF) receptor superfamily, by anti-Fas antibodies or by the Fas ligand (FasL), has been shown to cause cell death by apoptosis. A recent study from our laboratory has demonstrated that Fas crosslinking leads to the dephosphorylation of the tumor suppressor retinoblastoma protein (Rb) and that this dephosphorylation is inhibited by calyculin A, a serine/threonine phosphatase inhibitor. In this investigation, we compared the effect of Fas crosslinking by CH11, an anti-Fas mAb, with two cyclin-dependent kinase (CDK) inhibitors, a peptide that specifically inhibits CDK2 (cdk2 inh) and roscovitine, which inhibits CDK2, CDC2, and CDK5. We illustrate that roscovitine induced DNA fragmentation, whereas cdk2 inh did not. In contrast to Fas-induced apoptosis, roscovitine-induced apoptosis was resistant to calyculin A. Both cdk2 inh and roscovitine induced cleavage of poly (ADP-ribose) polymerase (PARP) within 2 h. Roscovitine, however, led to the degradation of Rb, whereas cdk2 inh did not. Furthermore, both CH11 and roscovitine caused cell cycle arrest in S phase. In contrast, cdk2 inh did not have any effect on Jurkat cell cycle progression. Taken together, our results strongly suggest that the maintenance of Rb in its hyperphosphorylated form during S phase may be necessary for cell survival and that Rb dephosphorylation during S phase may constitute a crucial step in Fas-induced apoptosis.
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PMID:Evidence that Fas-induced apoptosis leads to S phase arrest. 1129 63

Double-stranded (ds) RNA-induced sequence-specific interference with gene expression, RNA interference (RNAi), has been extensively used in invertebrates, allowing for efficient and high-throughput gene silencing and gene function analysis. In vertebrates, however, use of RNAi to study gene function has been limited due to non-specific effects induced by double-stranded RNA (dsRNA)-dependent protein kinase and interferon activation. dsRNA-induced specific inhibition of vertebrate gene expression has only been shown in embryonic and non-differentiated mammalian cells. In this report, we demonstrate dsRNA-induced specific interference of gene expression and gene function in partially as well as fully differentiated mouse neuroblastoma cells. Specific silencing was observed in the expression of an integrated transgene coding for green fluorescent protein and a variety of endogenous genes. Moreover, we show that RNAi-mediated inhibition of poly (ADP-ribose) polymerase (PARP) expression induced cellular resistance to oxygen-glucose deprivation, consistent with the role of PARP in ischemia-induced brain damage. Our results indicate that RNAi can be used as a powerful tool to study gene function in neural cells.
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PMID:Specific interference with gene expression and gene function mediated by long dsRNA in neural cells. 1246 5

Herpes simplex virus type 1 (HSV-1) triggered apoptosis in hippocampal cultures, as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and immunohistochemistry with antibody specific for the large fragment of activated caspase 3. The levels of phosphorylated (activated) c-Jun N-terminal kinase (JNK) were also increased in HSV-1-infected hippocampal cultures as were the levels of activated c-Jun, its target. JNK activation was involved in HSV-1-induced apoptosis as evidenced by apoptosis inhibition with the JNK inhibitor SP600125. HSV-2 activated the mitogen-activated protein kinase/extracellular regulated protein kinase (MEK/ERK) survival pathway and did not trigger apoptosis in hippocampal cultures. The MEK specific inhibitor U0126 inhibited ERK activation and caused a significant increase in the percent TUNEL(+) cells in HSV-2-infected cultures, indicating that the failure of HSV-2 to trigger apoptosis is due to its ability to activate the MEK/ERK survival pathway. JNK was also activated in brain tissues from patients with HSV-associated acute focal encephalitis (HSE) that were positive for HSV-1 antigen. JNK activation correlated with apoptosis, as determined by immunohistochemistry with antibody to activated caspase 3 or cleaved poly (ADP-ribose) polymerase (PARP). The data suggest that HSE has an apoptotic component that may contribute to disease pathogenesis.
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PMID:Herpes simplex virus type 1-induced encephalitis has an apoptotic component associated with activation of c-Jun N-terminal kinase. 1258 73

Perturbations of neuronal physiological homeostasis are likely to underscore neuronal demise/impairments that are reportedly associated with aging of the central nervous system and age-related neurodegenerative diseases such as Alzheimer's disease (AD). A number of age- and/or disease-associated neurotoxic events has been described. These include abnormally modified proteins such as beta amyloid and hyper-phosphorylated Tau, cytokines such as tumour necrosis factor-alpha (TNFalpha), high levels of free radicals conducive to oxidative stress, and impaired/decreased neuronal trophic support by neurotrophic factors. Overall, it could be argued that toxic events in the aged brain are either active, such as those due to a direct action of cytokines, or passive, such as those due to lack of growth factor support. It is therefore conceivable that cellular responses to such diverse toxic stimuli are different, suggesting that interventions should be targeted accordingly. In order to begin answering this question, we determined in PC12 cells the time course of activity, in response to TNFalpha (active) or growth factor withdrawal (passive), of protein kinase c-zeta (PKCzeta), nuclear factor kappa B (NFkappaB), caspases 3 and 8, and poly (ADP-ribose) polymerase (PARP), key signal transduction elements associated with modulation of cell death/survival in PC12 cells. We found that the overall activity of PKCzeta, NFkappaB and caspase 8 was significantly different depending on the apoptotic initiator. The pattern of caspase 3 and PARP activity, however, was not statistically different between serum-free- and TNFalpha-induced cell death conditions. This suggests that two distinct cell responses are elicited that converge at caspase 3, which then induces downstream events involved in the execution of a common apoptotic programme. These results contribute to the aim of differentially targeting neuronal death in the aged brain (characterized by neurotrophic factor impairments) or in the diseased brain (e.g. AD, characterized by elevated levels of pro-inflammatory cytokines).
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PMID:Tumour necrosis factor-alpha- vs. growth factor deprivation-promoted cell death: distinct converging pathways. 1457 Feb 32

Although tamoxifen (TAM), which is widely used in the treatment of breast cancer, also has a beneficial effect on cisplatin-refractory ovarian cancer, the biological mechanism of this effect has remained obscure. TAM, besides its action as an antiestrogen, also inhibits cell proliferation of estrogen receptor (ER)-negative cells by an unknown mechanism. Therefore, we examined the roles of the MAPK family in the antiproliferative effect of TAM on cisplatin-resistant Caov-3, which expresses ER and cisplatin-sensitive A2780, which does not express ER. The number of viable cells was reduced by TAM dose-dependently. TAM induced the activation of ERK, c-Jun N-terminal protein kinase (JNK), and p38 with different time courses. PD98059 canceled the reduction of the number of viable cells by 1 microM TAM and inhibited the TAM-induced cell-cycle arrest at the G(1) phase and dephosphorylation of the retinoblastoma protein. Either expression of dominant-negative JNK or pretreatment with SB203580 canceled the reduction of the number of viable cells by 5 microM TAM and inhibited the apoptotic nuclear changes and the cleavage of poly (ADP-ribose) polymerase induced by TAM. These results provide evidence that whereas the ERK cascade is involved in the induction of cell-cycle arrest at the G(1) phase by lower concentrations of TAM, the JNK or p38 cascade is involved in the induction of apoptosis by higher concentrations of TAM in both types of cells.
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PMID:Tamoxifen inhibits cell proliferation via mitogen-activated protein kinase cascades in human ovarian cancer cell lines in a manner not dependent on the expression of estrogen receptor or the sensitivity to cisplatin. 1464 10

We have previously reported that murine peritoneal macrophages exposed to ultraviolet B (UV-B; 100 mJ/cm2) undergo apoptosis, as indicated by alterations in cell morphology, caspase-3 activation, poly (ADP-ribose) polymerase (PARP) cleavage, DNA fragmentation, sustained activation of p38/c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) and inactivation of p42/44 MAPKs. It is now reported that macrophages undergoing UV-B-induced apoptosis show enhanced expression of protein kinase Cdelta (PKCdelta) in a time-dependent manner. Pretreatment of macrophages with PKCdelta-specific inhibitor rottlerin prior to the UV-B irradiation inhibits activation of caspase-3, PARP cleavage, DNA fragmentation and release of intracellular Ca2+. Inhibition of PKCdelta also blocks the sustained activation of p38 and JNK MAPKs as well as inactivation of p42/44 MAPKs. PKCalpha and PKCbeta1 expression also increases during UV-B-induced apoptosis in macrophages. Inhibition of these two isoforms with Go6976 slightly suppresses caspase-3 activation, PARP cleavage, DNA fragmentation and release of intracellular Ca2+, but has no effect on the sustained activation of p38/JNK MAPKs or inactivation of p42/44 MAPKs. It is, therefore, suggested that activation of PKCdelta might play an important role in the UV-B-induced apoptosis and that specific activated isoforms of PKC may have distinct functions in cell death.
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PMID:Role of protein kinase Cdelta in UV-B-induced apoptosis of macrophages in vitro. 1556 68

A novel histone deacetylase inhibitor, FK228, is a promising anticancer agent and has been proposed to modulate intracellular signaling, in addition to regulating gene transcription. We evaluated the effect of this agent on Akt-mediated signaling in relation to its cytotoxic activity using lung adenocarcinoma cell lines. Based on MTT assay and the appearance of cleaved poly (ADP-ribose) polymerase (PARP), we regarded A549 and PC14 cells as relatively sensitive and resistant cell lines, respectively. In A549 cells, FK228 suppressed the phosphorylation of Akt at Ser-473 and glycogen synthase kinase-3 without affecting these protein levels, indicating inhibition of the Akt-mediated signaling pathway. On the other hand, in PC14 cells, these biochemical reactions were not detected after treatment with FK228. The combination of FK228 and a phosphatidylinositol 3-kinase (PI3K)/Akt pathway inhibitor, LY294002, was determined to be synergistically cytotoxic in PC14 cells by isobologram analysis. This synergistic effect was attributable to the enhancement of apoptosis, as judged by flow cytometric analysis, and the appearance of cleaved PARP. The combination of FK228 with UCN-01, another PI3K/Akt pathway inhibitor, also exerted a synergistic effect. We concluded that FK228 suppresses the PI3K/Akt signaling pathway in a cell-specific manner, and this effect is a determinant of sensitivity to FK228.
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PMID:Suppression of phosphatidylinositol 3-kinase/Akt signaling pathway is a determinant of the sensitivity to a novel histone deacetylase inhibitor, FK228, in lung adenocarcinoma cells. 1570 21


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