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:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The growth arrest and DNA damage-inducible protein (GADD34) mediates growth arrest and apoptosis in response to DNA damage, negative growth signals, and protein malfolding. GADD34 binds to protein phosphatase-1 (PP1) and can attenuate translational elongation of key transcriptional factors through dephosphorylation of eukaryotic initiation factor-2alpha. We reported previously that the human trithorax leukemia fusion protein (HRX) can bind to GADD34 and abrogate GADD34-mediated apoptosis in response to UV irradiation. We found that hSNF5/INI1, a component of the hSWI/SNF chromatin remodeling complex, also binds to GADD34 and can coexist with GADD34 and HRX fusion proteins as a trimolecular complexes in vivo. In the present report, we demonstrate that hSNF5/INI1 binds to GADD34 in part through the PP1 docking site within a domain homologous to herpes simplex virus-1 ICP34.5. We found that hSNF5/INI1 can bind PP1 independently and weakly stimulate its phosphatase activity in solution and in complex with GADD34. hSNF5/INI1 and PP1 do not compete for binding to GADD34 but rather form a stable heterotrimeric complex with GADD34. We also show that Epstein-Barr nuclear protein 2, which binds hSNF5/INI1, can disrupt hSNF5/INI1 binding to GADD34 and partially reverse the GADD34-mediated growth suppression function in Ha-ras expressing HIH-3T3 (3T3-ras) cells. These results implicate hSNF5/INI1 in the function of GADD34 and suggest that hSNF5/INI1 may regulate PP1 activity in vivo.
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PMID:The human SNF5/INI1 protein facilitates the function of the growth arrest and DNA damage-inducible protein (GADD34) and modulates GADD34-bound protein phosphatase-1 activity. 1201 8

NF-kappa B plays crucial roles in the nervous system, including potential roles in long-term responses to synaptic plasticity, pro- or antiapoptotic effects during developmental cell death, and neurodegenerative disorders. We report here the characterization of signaling pathways leading to the constitutive activation of NF-kappa B in primary cultures of neonatal cerebellar granule neurons, consecutive to calcium entry into the cytosol. We found that opening of calcium channels at the plasma membrane and at intracellular stores is indispensable for the basal NF-kappa B activity. We demonstrated further that three cellular sensors of the cytosolic Ca(2+) levels, calmodulin, protein kinases C (PKCs), and the p21(ras)/phosphatidylinositol 3-kinase (PI3K)/Akt pathway are simultaneously involved in the steps linking the Ca(2+) second messenger to NF-kappa B activity. Calmodulin triggers the activity of calcineurin, a phosphatase which plays a role in the basal NF-kappa B activity, while stimulation of both the calmodulin kinase II and Akt kinase pathways results in the up-regulation of the transcriptional potential of the p65 subunit of NF-kappa B. Finally, using pharmacological and molecular approaches, we analyze interactions between these three pathways at different levels and demonstrate a connection between PKCs and PI3K. All three components converge towards NF-kappa B, at the level of both nuclear translocation and transcriptional activity. These results stand in contrast to the situation in nonneuronal cells, which either do not respond to Ca(2+) or do not simultaneously activate all three cascades. By using a global approach in studying signaling pathways in neurons, these results provide further evidence to validate the concept of networks of transducing cascades, specific to cells and to physiological situations.
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PMID:From calcium to NF-kappa B signaling pathways in neurons. 1266 71

Cyclin-dependent kinase 2 (Cdk2) phosphorylates Thr320 of protein phosphatase 1alpha (PP1alpha) in late G(1), thereby inhibiting its activity. Phosphorylation-resistant PP1alphaT320A, acting as a constitutively active (CA) mutant, causes a late G(1) arrest by preventing the phosphorylation and inactivation of the retinoblastoma protein (pRb). Both PP1alpha-mediated G(1) arrest and PP1alpha phosphorylation in late G(1) require the presence of pRb, indicating that PP1alpha is a crucial regulator of the pRb pathway, which is almost invariably mutated in human cancer. These findings prompted us to investigate whether PP1alpha interferes with oncogenic transformation. The ability of NIH 3T3 cells to form foci after transformation with ras/cyclin D1 was significantly inhibited by co-transfection with PP1alphaT320A, but not PP1alpha. Likewise, cells expressing PP1alphaT320A or PP1alphaT320A fused to green fluorescent protein (GFP) were unable to form colonies in soft agar, regardless of whether PP1alpha constructs were co-transfected with ras/cyclin D1 or transfected into stably transformed cells. Overexpressed wild-type (Wt) PP1alpha and GFP-PP1alpha were phosphorylated in Thr320, most likely explaining its lack of effect. Expression of GFP-PP1alphaT320A was associated with caspase-cleaved pRb in Western blots (WB) and morphological signs of cell death. These findings demonstrate that PP1alpha activity can override oncogenic signaling by causing cell-cycle arrest and/or apoptosis rather than restoring contact inhibition or anchorage dependence.
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PMID:Protein phosphatase 1alpha activity prevents oncogenic transformation. 1655 Jun 9

Ras proteins control at least three crucial signalling networks responsible for several cellular processes including anchorage independence, survival, and proliferation. Point mutations in one of the three ras genes are frequent in human tumours. In these tumours, Ras oncoproteins contribute significantly to the malignant phenotype, including deregulation of tumour-cell growth, apoptosis and invasiveness, and the ability to induce angiogenesis. Although significant strides have been made in understanding Ras biology, the collaborative actions of Ras effectors are still poorly understood. Here, we describe a proteomics approach to study global changes in protein expression in Ras-transformed NIH3T3 cells. We exploited 2-D difference gel electrophoresis (DIGE) for pre-separation fluorescent protein labelling with three separate dyes to reduce gel-to-gel variability, to increase sensitivity and dynamic range of protein detection, and to enhance quantification of dysregulated proteins. Proteins dysregulated (> 1.5-fold) by oncogenic Ras transformation reported to be implicated in Ras-regulated pathways include S-methyl-5-thioadenosine phosphorylase, stress-induced-phosphoprotein 1, galectin-1, annexin A7 (synexin), 60S acidic ribosomal protein P0, serine/threonine protein phosphatase type 1 (PP1alpha) and prohibitin. Significantly, we report for the first time the expression of the newly discovered cytokine IL-25 (or IL-17E) in mouse embryonic fibroblast cells and its down-regulation (2.1-fold) upon Ras-induced oncogenic transformation.
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PMID:Analysis of Ras-induced oncogenic transformation of NIH-3T3 cells using differential-display 2-DE proteomics. 1752 45

In endothelial cells, binding of vascular endothelial growth factor (VEGF) to VEGF receptor 2 leads to the activation of the serine/threonine phosphatase calcineurin, dephosphorylation of the nuclear factor of activated T-cells (NF-AT) transcription factors, translocation of NF-AT to the nucleus, and expression of angiogenesis-related genes such as Cox-2. Down syndrome candidate region 1 (DSCR1) is transactivated by NF-AT nuclear translocation, and subsequently inhibits calcineurin activity, forming a negative feedback loop. While DSCR1 has a clearly defined role as an endogenous inhibitor of VEGF-calcineurin-mediated angiogenesis in endothelial cells, the function of the DSCR1 family member, DSCR1-like 1 (DSCR1-L1), has not yet been investigated in endothelial cells. Here we show that a panel of pro-angiogenic factors, including VEGF, basic fibroblast growth factor (bFGF), angiopoietin 1, hepatocyte growth factor, as well as triiodo-l-thyronine (T(3)), does not induce DSCR1-L1 up-regulation in endothelial cells, while VEGF potently up-regulates DSCR1. To investigate the effects of DSCR1-L1 on endothelial cell function, we cloned the gene into a lentiviral vector and overexpressed DSCR1-L1 in human umbilical vein endothelial cells. Constitutive DSCR1-L1 overexpression prevented the nuclear translocation of NF-ATc1 in response to VEGF, underscoring its role as a calcineurin inhibitor. Additionally, DSCR1-L1-transduced cells inhibited VEGF-induced endothelial cell migration, proliferation, and tube formation by 36, 77, and 39%, respectively, compared to cells infected with control virus. Overexpression of DSCR1-L1 in the transformed endothelial cell line Sven 1 ras also resulted in decreased proliferation. Our findings demonstrate that DSCR1-L1 is constitutively expressed in endothelial cells and acts similar to DSCR1 in inhibiting calcineurin activity and restraining VEGF-mediated angiogenesis.
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PMID:Down syndrome candidate region 1-like 1 (DSCR1-L1) mimics the inhibitory effects of DSCR1 on calcineurin signaling in endothelial cells and inhibits angiogenesis. 1761 Sep 1

Ectopic expression of conditional murine p53 (p53val135) and oncogenic ras is enough to induce a senescent-like growth arrest at the restrictive temperature. We took advantage of this cellular system to identify new key players in the ras/p53-induced senescence. Applying a retroviral-based genetic screen, we obtained an antisense RNA fragment against PPP1CA, the catalytic subunit of protein phosphatase 1alpha, whose loss of function bypasses ras/p53-induced growth arrest and senescence. Expression of a specific short hairpin (sh)RNA against PPP1CA impairs the p53-dependent induction of p21 after DNA damage and blocks the subsequent pRb dephosphorylation, thus bypassing p53-induced arrest. We found that oncogenic ras promotes an increase in the intracellular level of ceramides together with an increase in the PPP1CA protein levels. Addition of soluble ceramide to the cells induced a senescence phenotype that is blocked through PPP1CA downregulation by specific shRNA. Analysis of human tumors suggests that one of the PPP1CA alleles might be lost in a high percentage of carcinomas such as kidney and colorectal. The overexpression of two out of five PPP1CA alternative spliced variants reduced tumor cell growth and the downregulation of the protein to hemizygosity increased the anchorage-independent growth. We propose that oncogenic stress induced by ras causes ceramide accumulation, therefore, increasing PPP1CA activity, pRb dephosphorylation and onset of the p53-induced arrest, contributing to tumor suppression.
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PMID:PPP1CA contributes to the senescence program induced by oncogenic Ras. 1820 81

Many studies have utilized the Inbred Long Sleep and Inbred Short Sleep mouse strains to model the genetic influence on initial sensitivity to ethanol. The mechanisms underlying this divergent phenotype are still not completely understood. In this study, we attempt to identify genes that are differentially expressed between these two strains and to identify baseline networks of co-expressed genes, which may provide insight regarding their phenotypic differences. We examined the whole brain and striatal transcriptomes of both strains, using next generation RNA sequencing techniques. Many genes were differentially expressed between strains, including several in chromosomal regions previously shown to influence initial sensitivity to ethanol. These results are in concordance with a similar sample of striatal transcriptomes measured using microarrays. In addition to the higher dynamic range, RNA-Seq is not hindered by high background noise or polymorphisms in probesets as with microarray technology, and we are able to analyze exome sequence of abundant genes. Furthermore, utilizing Weighted Gene Co-expression Network Analysis, we identified several modules of co-expressed genes corresponding to strain differences. Several candidate genes were identified, including protein phosphatase 1 regulatory unit 1b (Ppp1r1b), prodynorphin (Pdyn), proenkephalin (Penk), ras association (RalGDS/AF-6) domain family member 2 (Rassf2), myosin 1d (Myo1d) and transthyretin (Ttr). In addition, we propose a role for potassium channel activity as well as map kinase signaling in the observed phenotypic differences between the two strains.
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PMID:Transcriptome analysis of Inbred Long Sleep and Inbred Short Sleep mice. 2343 84

Although calcineurin inhibitors (CNIs) are very useful in preventing allograft rejection, they can mediate a rapid progression of post-transplantation malignancies. The CNI cyclosporine A (CsA) can promote renal tumor growth through activation of the proto-oncogene ras and over-expression of the angiogenic cytokine VEGF; the ras activation also induces over-expression of the cytoprotective enzyme HO-1, which promotes survival of renal cancer cells. Here, we show that the natural product honokiol significantly inhibited CsA-induced and Ras-mediated survival of renal cancer cells through the down-regulations of VEGF and HO-1. Thus, honokiol treatment may help to prevent tumor-promoting effects of CsA in transplant patients.
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PMID:The natural product honokiol inhibits calcineurin inhibitor-induced and Ras-mediated tumor promoting pathways. 2375 66

Hepatitis C virus (HCV) end stage liver disease is a main indication for liver transplantation (LT). Recurrent HCV always occurs when patients are transplanted with a detectable viral load, leading to cirrhosis in 20-30% of patients within 5 years. Achieving a sustained virological response (SVR) with antiviral treatment is the only way to improve patient and graft survival. Dual therapy based on pegylated interferon and ribavirin (PEG-IFN/RBV) was the standard of care for many years with limited efficacy and a poor safety profile. The addition of first generation NS3/4 protease inhibitors (PI) improved SVR rates from 30 to 50-60%. But the occurrence of serious adverse events and drug-drug interactions with calcineurin inhibitors have both been limiting factors for their use during LT. The preliminary results of the use of second generation direct acting antivirals (DAA) in transplant patients showed better efficacy with an SVR rate >70%. The pre- and post-transplantation safety profile is good. Although fewer drug-drug interactions are expected, some new DAA still interact with immunosuppressive drugs. Certain questions such as the use of RBV or the optimal duration of therapy have still not been resolved but should be answered by the many ongoing studies in the coming year.
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PMID:Optimal therapy in hepatitis C virus liver transplant patients with direct acting antivirals. 2537 40

Immediate-early response gene c-fos expression is repressed and not activated after serum stimulation of serum-starved fibroblasts transformed with E1A and cHa-ras oncogenes. We have previously shown that such stress factors as an anisomycin are able to activate c-fos gene transcription in E1A + cHa-ras transformants, wherein MEK/ERK signal pathway plays a major role in the activation. In the present paper, we investigated the role of MKP-1-dependent regulation of c-fos gene by dephosphorylation of ERK kinases. It has been shown that MKP-1 gene transcription in E1A + ras transformants is activated by anisomycin for a maximum of 1 h, and then a reduction in the level of transcription occurs. Use of inhibitors of MAP-kinase has revealed that MKP-1 gene transcription depends on MEK/ERK and JNK kinase cascades, but not om p38 cascade. The anisomycin-induced c-fos gene transcription intensified after transfection of siRNA MKP-1 into the cells. Thus, protein phosphatase MKP-1 carries a negative regulation of c-fos gene transcription by dephosphorylation of ERK kinases that are a key signal component under the action of such stress reagent as anisomycin on the E1A + ras-transformed cells.
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PMID:[Protein phosphatase MKP-1 participates in c-fos gene derepression under the action of stress factors on fibroblasts transformed with E1A and cHA-ras oncogenes]. 2547 4


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