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)

TOR (target of rapamycin) is a phosphatidylinositol kinase-related protein kinase that controls cell growth in response to nutrients. Rapamycin is an immunosuppressive and anticancer drug that acts by inhibiting TOR. The modes of action of TOR and rapamycin are remarkably conserved from S. cerevisiae to humans. The current understanding of TOR and rapamycin is derived largely from studies with S. cerevisiae. In this review, we discuss the contributions made by S. cerevisiae to understanding rapamycin action and TOR function.
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PMID:Elucidating TOR signaling and rapamycin action: lessons from Saccharomyces cerevisiae. 1245 83

Three phosphatidylinositol 4-kinase isoforms, PI4K 230, 92 and 55 have been cloned and sequenced allowing a much wider characterization than the previously employed enzymological typing into type II and III enzymes. PI4K 230 and 92 contain a highly conserved catalytic core, PI4K55 one with a much lower degree of similarity. Candidate kinase motifs, deduced from the protein kinase super family, are absolutely conserved in all isoforms. Kinase activities are described based on their sensitivity and reactivity towards wortmannin, phenylarsine oxide (PAO) and 5'-p-fluorosulfonylbenzoyladenosine (FSBA). Localization of all isoforms in the cell is reported. All enzymes contain nuclear localization and export sequence motifs (NLS and NES) leading to the expectation that they can be transferred to the nucleus. PI4K230 has been found in the nucleolus, PI4K92 in the nucleus, additionally further broadening the function of these enzymes. In the cytoplasm of neuronal cells, PI4K230 is distributed evenly on membranes that are ultra structurally cisterns of the rough endoplasmatic reticulum, outer membranes of mitochondria, multivesicular bodies, and are in close vicinity of synaptic contacts. PI4K92 is functionally characterized as a key enzyme regulating Golgi disintegration/reorganization during mitosis probably via phosphorylation by cyclin-dependent kinases on well-defined sites. PI4K55 is involved in the production of second messengers, diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (InsP3) at the plasma membrane, moreover, in the endocytotic pathway in the cytoplasm.
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PMID:Mammalian phosphatidylinositol 4-kinases. 1274 87

Corticotropin-releasing factor (CRF) receptors are members of the superfamily of G-protein coupled receptors that utilise adenylate cyclase and subsequent production of cAMP for signal transduction in many tissues. Activation of cAMP-dependent pathways, through elevation of intracellular cAMP levels is known to promote survival of a large variety of central and peripheral neuronal populations. Utilising cultured primary rat central nervous system neurons, we show that stimulation of endogenous cAMP signalling pathways by forskolin confers neuroprotection, whilst inhibition of this pathway triggers neuronal death. CRF and the related CRF family peptides urotensin I, urocortin, and sauvagine, which also induced cAMP production, prevented the apoptotic death of cerebellar granule neurons triggered by inhibition of phosphatidylinositol kinase-3 pathway activity with LY294002. These effects were negated by the highly selective CRF-R1 antagonist CP154,526. CRF even conferred neuroprotection when its application was delayed by up to 8 h following LY294002 addition. The CRF peptides also protected cortical and hippocampal neurons against death induced by beta-amyloid peptide (1-42), in a CRF-R1 dependent manner. In separate experiments, LY294002 reduced neuronal protein kinase B activity while increasing glycogen synthase kinase-3, whilst CRF (and related peptides) promoted phosphorylation of glycogen synthase kinase-3 without protein kinase B activation. Taken together, these results suggest that the neuroprotective activity of CRF may involve cAMP-dependent phosphorylation of glycogen synthase kinase-3.
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PMID:Corticotropin-releasing factor (CRF) and related peptides confer neuroprotection via type 1 CRF receptors. 1294 76

Eukaryotic messenger RNAs containing premature stop codons are selectively and rapidly degraded, a phenomenon termed nonsense-mediated mRNA decay (NMD). Previous studies with both Caenohabditis elegans and mammalian cells indicate that SMG-2/human UPF1, a central regulator of NMD, is phosphorylated in an SMG-1-dependent manner. We report here that smg-1, which is required for NMD in C. elegans, encodes a protein kinase of the phosphatidylinositol kinase superfamily of protein kinases. We identify null alleles of smg-1 and demonstrate that SMG-1 kinase activity is required in vivo for NMD and in vitro for SMG-2 phosphorylation. SMG-1 and SMG-2 coimmunoprecipitate from crude extracts, and this interaction is maintained in smg-3 and smg-4 mutants, both of which are required for SMG-2 phosphorylation in vivo and in vitro. SMG-2 is located diffusely through the cytoplasm, and its location is unaltered in mutants that disrupt the cycle of SMG-2 phosphorylation. We discuss the role of SMG-2 phosphorylation in NMD.
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PMID:SMG-1 is a phosphatidylinositol kinase-related protein kinase required for nonsense-mediated mRNA Decay in Caenorhabditis elegans. 1531 58

Antigen-specific T-cell signalling via T-cell antigen receptor stimulation was carried out in BALB/c mice immunized with the 57 kDa major antigenic component of Shigella dysenteriae 1 outer-membrane proteins. In presence of anti-CD3, the 57 kDa antigen was found to increase the level of IL-2 significantly instead of IL-4. IL-2 production in T cells was consistent with an increase in intracellular free Ca(2+) [(Ca(2+))i] concentration. The antigen-specific modulation was observed during T-cell signalling, with enhanced release of [(Ca(2+))i]. IL-2-receptor stimulation via IL-2 did not significantly induce the release of IL-2 with consistent intracellular Ca(2+) production. Furthermore, the protein tyrosine kinase was activated during anti-CD3 stimulation, which up-regulated the phosphatidylinositol kinase of p85-mediated serine kinase protein kinase-C of p70. Phosphoinositide-specific kinases are regulated by the phosphorylation of tyrosine kinase through the activation of the T-cell antigen receptor. The above findings indicate that phosphotidylinositol-3 kinase-mediated signals are up-regulated through [(Ca(2+))i], which is essential for Th1-type responses.
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PMID:Phosphotidylinositol-3 kinase-mediated signals in mice immunized with the 57 kDa major antigenic outer-membrane protein of Shigella dysenteriae type 1. 1594 27

We have investigated whether Ca(2+)-binding proteins, which have been implicated in the control of neurons and neuroendocrine secretion, play a role in controlling mast cell function. These studies have identified synaptotagmins (Syts) II, III, and IX as well as neuronal Ca(2+) sensor 1 (NCS-1) as important regulators of mast cell function. Strikingly, we find that these Ca(2+)-binding proteins contribute to mast cell function by regulating specific endocytic pathways. Syt II, the most abundant Syt homologue in mast cells, resides in an amine-free lysosomal compartment. Studying the function of Syt II-knocked down rat basophilic leukemia cells has shown a dual function of this homologue. Syt II is required for the downregulation of protein kinase Calpha, but it negatively regulates lysosomal exocytosis. Syt III, the next most abundant homologue, localizes to early endosomes and is required for the formation of the endocytic recycling compartment (ERC). Syt IX and NCS-1 localize to the ERC and regulate ERC export, NCS-1 by activating phosphatidylinositol 4-kinase beta. Finally, we show that recycling through the ERC is needed for secretory granule protein sorting as well as for the activation of the mitogen-activated protein kinases, extracellular signal-regulated kinase 1 and 2. Accordingly, NCS-1 stimulates Fc epsilon RI-triggered exocytosis and release of arachidonic acid metabolites.
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PMID:The mast cell: where endocytosis and regulated exocytosis meet. 1749 67

TOR complex 1 (TORC1), an oligomer of the mTOR (mammalian target of rapamycin) protein kinase, its substrate binding subunit raptor, and the polypeptide Lst8/GbetaL, controls cell growth in all eukaryotes in response to nutrient availability and in metazoans to insulin and growth factors, energy status, and stress conditions. This review focuses on the biochemical mechanisms that regulate mTORC1 kinase activity, with special emphasis on mTORC1 regulation by amino acids. The dominant positive regulator of mTORC1 is the GTP-charged form of the ras-like GTPase Rheb. Insulin, growth factors, and a variety of cellular stressors regulate mTORC1 by controlling Rheb GTP charging through modulating the activity of the tuberous sclerosis complex, the Rheb GTPase activating protein. In contrast, amino acids, especially leucine, regulate mTORC1 by controlling the ability of Rheb-GTP to activate mTORC1. Rheb binds directly to mTOR, an interaction that appears to be essential for mTORC1 activation. In addition, Rheb-GTP stimulates phospholipase D1 to generate phosphatidic acid, a positive effector of mTORC1 activation, and binds to the mTOR inhibitor FKBP38, to displace it from mTOR. The contribution of Rheb's regulation of PL-D1 and FKBP38 to mTORC1 activation, relative to Rheb's direct binding to mTOR, remains to be fully defined. The rag GTPases, functioning as obligatory heterodimers, are also required for amino acid regulation of mTORC1. As with amino acid deficiency, however, the inhibitory effect of rag depletion on mTORC1 can be overcome by Rheb overexpression, whereas Rheb depletion obviates rag's ability to activate mTORC1. The rag heterodimer interacts directly with mTORC1 and may direct mTORC1 to the Rheb-containing vesicular compartment in response to amino acid sufficiency, enabling Rheb-GTP activation of mTORC1. The type III phosphatidylinositol kinase also participates in amino acid-dependent mTORC1 activation, although the site of action of its product, 3'OH-phosphatidylinositol, in this process is unclear.
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PMID:Amino acid regulation of TOR complex 1. 1876 78

Tumor growth is the orchestration of various oncogenes and tumor suppressors, and the regulation of these genes offers a rational therapeutic approach to cancer treatment. In this study, we found a new regulator of tumor growth, phosphatidylinositol 4-kinase type IIalpha (PI4KIIalpha), the mechanism of which is involved in angiogenesis and hypoxia-inducible factor HIF-1alpha regulation. Results obtained from a human cancer tissue microarray showed that PI4KIIalpha protein expression increases markedly in seven types of cancers compared with normal tissues. Suppression of PI4KIIalpha leads to retarded tumor growth in nude mice. Downregulation of PI4KIIalpha in cancer cells eliminates tumor cell-induced endothelial cell tubulogenesis and migration, and results in impaired angiogenesis. Further investigation showed that PI4KIIalpha can directly regulate HIF-1alpha expression and that the expression of these two proteins is correlated in vivo. At the same time, downregulation of PI4KIIalpha markedly reduces HER-2 autophosphorylation, and PI4KIIalpha specifically triggers HIF-1alpha accumulation through a phosphatidylinositol 3-kinase (PI3K)- and extracellular signal-regulated protein kinase (ERK)-dependent pathway, suggesting that PI4KIIalpha may regulate HIF-1alpha through the HER-2/PI3K, ERK cascade. In summary, we discovered a pivotal role for PI4KIIalpha in the regulation of tumor growth. Our results shed new light on understanding the novel functions of PI4KIIalpha in cancer and suggest that PI4KIIalpha may be a promising specific target for tumor therapy.
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PMID:PI4KIIalpha is a novel regulator of tumor growth by its action on angiogenesis and HIF-1alpha regulation. 2015 17

Phosphorylation is an important mechanism used by cells for the posttranslational regulation of protein function. While it has been shown that many of the phosphorylation systems are concentrated in the synaptic junction, we have found that oligodendroglial plasma membranes also have active protein kinase and phosphatidylinositol kinase systems as well. Four major phosphoproteins were identified in the plasma proteins with molecular weights of 67,000, 61,000, 53,000 and 44,000 Da. The 44,000 Da protein was phosphorylated by multiple protein kinases, while the phosphorylation of the three other proteins was affected by the lot of fetal calf serum used during the culture of the oligodendroglia. This suggests that these phosphoproteins are affected by the presence of agents such as growth factors or hormones which are present in serum. When the phosphorylation of the proteins was compared with that of the lipids, phosphatidylinositol 4-monophosphate exhibited a 20-fold increase in radioactivity. Thus active phosphatidylinositol kinase and phospholipase enzymes are also present in these plasma membranes.
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PMID:Four major phosphoproteins and active phosphatidylinositol turnover in oligodendroglial plasma membranes. 2050 51

Phagocytosis is a pivotal process by which macrophages eliminate microorganisms after recognition by pathogen sensors. Here we unexpectedly found that the self ligand and cell surface receptor SLAM functioned not only as a costimulatory molecule but also as a microbial sensor that controlled the killing of gram-negative bacteria by macrophages. SLAM regulated activity of the NADPH oxidase NOX2 complex and phagolysosomal maturation after entering the phagosome, following interaction with the bacterial outer membrane proteins OmpC and OmpF. SLAM recruited a complex containing the intracellular class III phosphatidylinositol kinase Vps34, its regulatory protein kinase Vps15 and the autophagy-associated molecule beclin-1 to the phagosome, which was responsible for inducing the accumulation of phosphatidylinositol-3-phosphate, a regulator of both NOX2 function and phagosomal or endosomal fusion. Thus, SLAM connects the gram-negative bacterial phagosome to ubiquitous cellular machinery responsible for the control of bacterial killing.
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PMID:SLAM is a microbial sensor that regulates bacterial phagosome functions in macrophages. 2081 96


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