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

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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)

cAMP has neutrotrophic effects in the nervous system. We have investigated whether there is a correlation between cAMP-induced neurite outgrowth and induction of chromogranin B and synapsin I gene expression. These genes encode marker proteins of distinct populations of vesicles in neurons, neuroendocrine and endocrine cells, and in addition, they contain a cAMP response element (CRE) in their upstream regions, making it likely that cAMP-induced neuronal differentiation might be accompanied by increased transcription of these genes. We increased intracellular cAMP levels in neuronal and neuroendocrine cells and analyzed the levels of chromogranin B and synapsin I mRNA. Our data revealed that, while chromogranin B mRNA was in fact induced following cAMP stimulation, synapsin I mRNA was not affected. To analyze the cis-acting sequences, we constructed hybrid genes containing the upstream region of the mouse chromogranin B gene fused to a reporter gene. Similar plasmids containing the synapsin I or the glucagon promoter were constructed. Transfections of neuronal and endocrine cells, together with deletion mutagenesis, revealed that the CRE of the chromogranin B gene mediated the effect of cAMP upon transcription. This effect was mimicked by overexpression of the catalytic subunit of the cAMP-dependent protein kinase. In addition, overexpression of the negative-acting CRE-binding protein CREB-2 revealed that the chromogranin B CRE functions as a bifunctional genetic regulatory element in that it mediates basal as well as cAMP-stimulated transcription. Synapsin I gene expression, however, was not induced by either elevated intracellular cAMP concentration or by overexpression of protein kinase A, although a similar pattern of proteins, including CREB, bound to the synapsin I and chromogranin B CRE in vitro. Thus while the CRE element in the chromogranin B gene promoter is responsive to cAMP, the same element, when present in the synapsin I promoter, does not confer cAMP inducibility.
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PMID:Differential regulation of chromogranin B and synapsin I gene promoter activity by cAMP and cAMP-dependent protein kinase. 752 78

The Tax protein of the human T-cell leukemia virus type 1 (HTLV-1) has been implicated in human T-cell immortalization. The primary function of Tax is to transcriptionally activate the HTLV-1 promoter, but Tax is also known to stimulate expression of cellular genes. It has been reported to associate with several transcription factors, as well as proteins not involved in transcription. To better characterize potential cellular targets of Tax present in infected cells, a Saccharomyces cerevisiae two-hybrid screening was performed with a cDNA library constructed from the HTLV-1-infected MT2 cell line. From this study, we found 158 positive clones representing seven different cDNAs. We focused our attention on the cDNA encoding the transcription factor CREB-2. CREB-2 is an unconventional member of the ATF/CREB family in that it lacks a protein kinase A (PKA) phosphorylation site and has been reported to negatively regulate transcription from the cyclic AMP response element of the human enkephalin promoter. In this study, we demonstrate that CREB-2 cooperates with Tax to enhance viral transcription and that its basic-leucine zipper C-terminal domain is required for both in vitro and in vivo interactions with Tax. Our results confirm that the activation of the HTLV-1 promoter through Tax and factors of the ATF/CREB family is PKA independent.
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PMID:CREB-2, a cellular CRE-dependent transcription repressor, functions in association with Tax as an activator of the human T-cell leukemia virus type 1 promoter. 973 79

Cytokines and free radicals are mediators of beta-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1beta (IL-1beta) + gamma-interferon (IFN-gamma) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic beta-cells. We have previously shown, by microarray analysis of primary beta-cells, that IL-1beta + IFN-gamma decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca(2+) ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress-related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein). In the present study we show that cytokine-induced apoptosis and necrosis in primary rat beta-cells and INS-1E cells largely depends on NO production. IL-1beta + IFN-gamma, via NO synthesis, markedly decreased SERCA2b protein expression and depleted ER Ca(2+) stores. Of note, beta-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca(2+) depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol-requiring ER-to-nucleus signal kinase 1alpha (IRE1alpha) and PRK (RNA-dependent protein kinase)-like ER kinase (PERK)/activating transcription factor 4 (ATF4), but not ATF6. In contrast, the ER stress-inducing agent thapsigargin triggered these four pathways in parallel. In conclusion, our results suggest that the IL-1beta + IFN-gamma-induced decrease in SERCA2b expression, with subsequent depletion of ER Ca(2+) and activation of the ER stress pathway, is a potential contributory mechanism to beta-cell death.
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PMID:Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+ ATPase 2b and deplete endoplasmic reticulum Ca2+, leading to induction of endoplasmic reticulum stress in pancreatic beta-cells. 1567 3

Unfolded protein response (UPR) is a cellular adaptive response that functions to reduce stress caused by malfolded proteins in the endoplasmic reticulum (ER). UPR can be induced under physiological or pathological conditions and is responsible for the pathogenesis of many human diseases. Hepatitis C virus (HCV) is a single-stranded, positive-sense RNA virus causing chronic diseases. Its genome encodes two envelope proteins E1 and E2, which mature in the ER to form a noncovalently bound, native complex and disulfide aggregates and have previously been shown to induce expression of the molecular chaperone immunoglobulin heavy chain binding protein. In this study, we show that HCV envelope protein expression regulates another stress indicator CCAAT/enhancer-binding protein-homologous protein (CHOP). The ER-stress element and the activating transcription factor 4 element in the CHOP promoter were activated to a similar extent by HCV envelope protein expression. Using mouse embryonic fibroblasts deficient in the ER stress kinase RNA-activated protein kinase-like ER-resident kinase (PERK), we showed that PERK was necessary and sufficient for activating the CHOP promoter. Expression of HCV E1 and/or E2 also induced splicing of X-box binding protein 1 and transactivation of the unfolded protein response element, leading to the speculation that HCV E1 and E2 not only regulate the UPR but also ER-associated degradation.
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PMID:Hepatitis C virus envelope proteins regulate CHOP via induction of the unfolded protein response. 1600 26

In response to environmental stresses, a family of protein kinases phosphorylate eIF2 (eukaryotic initiation factor 2) to alleviate cellular injury or alternatively induce apoptosis. Phosphorylation of eIF2 reduces global translation, allowing cells to conserve resources and to initiate a reconfiguration of gene expression to effectively manage stress conditions. Accompanying this general protein synthesis control, eIF2 phosphorylation induces translation of specific mRNAs, such as that encoding the bZIP (basic leucine zipper) transcriptional regulator ATF4 (activating transcription factor 4). ATF4 also enhances the expression of additional transcription factors, ATF3 and CHOP (CCAAT/enhancer-binding protein homologous protein)/GADD153 (growth arrest and DNA-damage-inducible protein), that assist in the regulation of genes involved in metabolism, the redox status of the cells and apoptosis. Reduced translation by eIF2 phosphorylation can also lead to activation of stress-related transcription factors, such as NF-kappaB (nuclear factor kappaB), by lowering the steady-state levels of short-lived regulatory proteins such as IkappaB (inhibitor of NF-kappaB). While many of the genes induced by eIF2 phosphorylation are shared between different environmental stresses, eIF2 kinases function in conjunction with other stress-response pathways, such as those regulated by mitogen-activated protein kinases, to elicit gene expression programmes that are tailored for the specific stress condition. Loss of eIF2 kinase pathways can have important health consequences. Mice devoid of the eIF2 kinase GCN2 [general control non-derepressible-2 or EIF2AK4 (eIF2alpha kinase 4)] show sensitivity to nutritional deficiencies and aberrant eating behaviours, and deletion of PEK [pancreatic eIF2alpha kinase or PERK (RNA-dependent protein kinase-like endoplasmic reticulum kinase) or EIF2AK3] leads to neonatal insulin-dependent diabetes, epiphyseal dysplasia and hepatic and renal complications.
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PMID:Coping with stress: eIF2 kinases and translational control. 1624 68

The supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamo-neurohypophyseal system (HNS) undergo a dramatic function-related plasticity during dehydration. We hypothesize that alterations in steady-state transcript levels might be partially responsible for this remodeling. In turn, regulation of transcript abundance might be mediated by transcription factors. We used microarrays to identify changes in the expression of mRNAs encoding transcription factors in response to water deprivation in the SON. We observed downregulation of 10 and upregulation of 28 transcription factor transcripts. For five of the upregulated mRNAs, namely gonadotropin inducible ovarian transcription factor 1 (Giot1), Giot2, cAMP-responsive element binding protein 3-like 1, CCAAT/enhancer binding protein beta, and activating transcription factor 4, in situ hybridization was used to confirm the array results, demonstrating a significant increase in expression in SON and PVN magnocellular neurons (MCNs) after 3 d of water deprivation and, in some cases, upregulation in parvocellular PVN neurons. Using a viral vector expressing a potent inhibitor of cAMP-dependent protein kinase A (PKA), we show that the osmotically induced increase in the abundance of transcripts encoding Giot1 is mediated in vivo by the PKA pathway. We thus suggest that signaling pathways activated by dehydration in MCNs mediate transcription factor gene activation, which, in turn, regulate target genes that mediate HNS remodeling.
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PMID:Transcription factor expression in the hypothalamo-neurohypophyseal system of the dehydrated rat: upregulation of gonadotrophin inducible transcription factor 1 mRNA is mediated by cAMP-dependent protein kinase A. 1732 16

A recent clinical trial (Chwalisz K, Larsen L, Mattia-Goldberg C, Edmonds A, Elger W, Winkel CA. Fertil Steril 87: 1399-1412, 2007) has demonstrated that the selective progesterone receptor modulator asoprisnil efficiently causes the shrinkage of uterine leiomyoma. The present study was conducted to examine whether asoprisnil elicits endoplasmic reticulum (ER) stress-induced apoptosis in cultured human uterine leiomyoma cells. After subculture in phenol red-free DMEM supplemented with 10% FBS for 120 h, cultured cells were stepped down to serum-free conditions with or without graded concentrations of asoprisnil. ER stress-associated and apoptosis-related proteins were assessed by reverse transcription-PCR analysis or Western blot analysis. RNA interference of growth-arrest- and DNA-damage-inducible gene 153 (GADD153) was performed using small interfering RNA. Terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL)-positive rates were assessed by TUNEL assay. Compared with untreated control cultures, treatment with 10(-7) M asoprisnil significantly (P < 0.05) increased the protein contents of ubiquitin at 2 h and phospho-double-stranded RNA-activated protein kinase-like ER kinase, phospho-eukaryotic initiation factor 2alpha, activating transcription factor 4, and glucose-regulated protein 78 kDa at 4 h, followed by the significant (P < 0.05) increase in GADD153 protein content at 6 h and cleaved poly(adenosine 5'-diphosphate ribose)polymerase (PARP) at 8 h. RNA interference of GADD153 suppressed protein contents of asoprisnil-induced cleaved PARP, Bax, Bak, GADD34, and tribbles-related protein 3 (TRB3) and TUNEL-positive rate but attenuated asoprisnil-induced reduction in Bcl-2 protein content in cultured leiomyoma cells. These results suggest that asoprisnil elicits ER stress-induced apoptosis in cultured leiomyoma cells and that GADD153 plays a role in asoprisnil-induced apoptosis by modulating the Bcl-2 family of proteins, GADD34, and TRB3.
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PMID:Selective progesterone receptor modulator asoprisnil induces endoplasmic reticulum stress in cultured human uterine leiomyoma cells. 1765 52

Carbon monoxide (CO), a reaction product of the cytoprotective heme oxygenase (HO)-1, is antiapoptotic in a variety of models of cellular injury, but the precise mechanisms remain to be established. In human umbilical vein endothelial cells, exogenous CO activated Nrf2 through the phosphorylation of protein kinase R-like endoplasmic reticulum kinase (PERK), resulting in HO-1 expression. CO-induced activation of PERK was followed by the phosphorylation of eukaryotic translation initiation factor 2alpha and the expression of activating transcription factor 4. However, CO fails to induce X-box binding protein-1 expression and activating transcription factor 6 cleavage. CO had no significant effect on synthesis of endoplasmic reticulum (ER) chaperone proteins such as the 78-kDa glucose-regulated proteins 78 and 94. Instead, CO prevented X-box binding protein 1 expression and activating transcription factor 6 cleavage induced by ER-stress inducers such as thapsigargin, tunicamycin and homocysteine. CO also prevented endothelial apoptosis triggered by these ER inducers through suppression of C/EBP homologous protein expression, which was associated with its activation of p38 mitogen-activated protein kinase. Similarly, endogenous CO produced from endothelial HO-1 induced by either exogenous CO or a pharmacological inducer was also cytoprotective against ER stress through C/EBP homologous protein suppression. Our findings suggest that CO renders endothelial cells resistant to ER stress not only by downregulating C/EBP homologous protein expression via p38 mitogen-activated protein kinase activation but also by upregulating Nrf2-dependent HO-1 expression via PERK activation. Thus, the HO-1/CO system might be potential therapeutics in vascular diseases associated with ER stress.
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PMID:Carbon monoxide induces heme oxygenase-1 via activation of protein kinase R-like endoplasmic reticulum kinase and inhibits endothelial cell apoptosis triggered by endoplasmic reticulum stress. 1796 96

Exposure of pancreatic beta-cells to long-chain fatty acids leads to the activation of some components of the endoplasmic reticulum (ER) stress pathway and this mechanism may underlie the ability of certain fatty acids to promote beta-cell death. We have studied ER stress in BRIN-BD11 beta-cells exposed to either the saturated fatty acid palmitate (C16:0) or the monounsaturated palmitoleate (C16:1). Palmitate (0.025-0.25 mM) induced the expression of various markers of the RNA-dependent protein kinase-like ER eukaryotic initiation factor 2 alpha (eIF2 alpha) kinase (PERK)-dependent pathway of ER stress (phospho-eIF2 alpha; ATF4, activating transcription factor 4 and C/EBP homologous protein (CHOP-10)) although it failed to promote the expression of the ER chaperone GRP78. By contrast, palmitoleate did not induce any markers of the ER stress pathway even at concentrations as high as 1 mM. When palmitate and palmitoleate were added in combination, a marked attenuation of the ER stress response occurred. Under these conditions, the levels of phospho-eIF2 alpha, ATF4 and CHOP-10 were reduced to less than those found in control cells. Palmitoleate also attenuated the ER stress response to the protein glycosylation inhibitor, tunicamycin, and improved the viability of the cells exposed to this agent. Exposure of the BRIN-BD11 cells to the protein phosphatase inhibitor, salubrinal, in the absence of fatty acids resulted in increased eIF2 alpha phosphorylation but this was abolished by co-incubation with palmitoleate. We conclude that saturated fatty acids activate components of the PERK-dependent ER stress pathway in beta-cells, ultimately leading to increased apoptosis. This effect is antagonised by monounsaturates that may exert their anti-apoptotic actions by regulating the activity of one or more kinase enzymes involved in mediating the phosphorylation of eIF2 alpha.
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PMID:Differential regulation of the endoplasmic reticulum stress response in pancreatic beta-cells exposed to long-chain saturated and monounsaturated fatty acids. 1849 19

gamma-Tocotrienol, a member of the vitamin E family of compounds, induces apoptosis in a variety of cancer cell types. However, previous studies have clearly demonstrated that gamma-tocotrienol-induced apoptosis in neoplastic mouse +SA mammary epithelial cells is not mediated through mitochondrial stress or death receptor apoptotic signaling. Therefore, studies were conducted to determine the role of endoplasmic reticulum (ER) stress in mediating gamma-tocotrienol-induced apoptosis in +SA mammary tumor cells. Treatment with 15-40 microM gamma-tocotrienol induced +SA cell death in a dose-responsive manner, and these effects were associated with a corresponding increase in poly (ADP-ribose) polymerase (PARP)-cleavage and activation of protein kinase-like endoplasmic reticulum kinase/eukaryotic translational initiation factor/activating transcription factor 4 (PERK/eIF2alpha/ATF-4) pathway, a marker of ER stress response. These treatments also caused a large increase in C/EBP homologous protein (CHOP) levels, a key component of ER stress mediated apoptosis that increases expression of tribbles 3 (TRB3). Knockdown of CHOP by specific siRNAs attenuated gamma-tocotrienol-induced PARP-cleavage, CHOP and TRB3 expression. gamma-Tocotrienol treatment also reduced full-length caspase-12 levels, an indication of caspase-12 cleavage and activation. Intracellular levels of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase, an ER-transmembrane enzyme catalyzing the synthesis of mevalonate, decreased following gamma-tocotrienol treatment, but combined treatment with mevalonate did not reverse gamma-tocotrienol-induced apoptosis, suggesting that a decrease in HMGCoA reductase activity is not required for gamma-tocotrienol induced apoptosis. These results demonstrate that ER stress apoptotic signaling is associated with gamma-tocotrienol-induced apoptosis in +SA mammary tumor cells.
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PMID:Endoplasmic reticulum stress mediates gamma-tocotrienol-induced apoptosis in mammary tumor cells. 1977 20


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