Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P67775 (alpha isoform)
 797 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preconditioning of the myocardium rapidly induces a number of transcription factors, which are likely to be responsible for a cascade of transcriptional changes underlying the development of delayed adaptation. Identifying these changes provides insight into the molecular pathways elicited by sub-lethal ischaemia and the mechanism leading to delayed adaptation. Genes up-regulated in rabbit myocardium in vivo by ischaemic preconditioning following reperfusion for 2 h, 4 h and 6 h post-treatment were identified by representational difference analysis of cDNA (cDNA. RDA). The area of the left ventricle rendered ischaemic by preconditioning or the equivalent area of sham-treated animals was isolated and cDNA.RDA performed. Three novel genes and six genes with known function where identified, including the TGFbeta receptor interacting protein 1, the alpha isoform of the A subunit of PP2 and the cap binding protein NCBP1. To determine whether expression of these genes correlated with preconditioning per se, expression was measured in myocardium after both ischaemic as well as heat shock induced preconditioning following 2 h, 4 h, and 6 h reperfusion. These genes were induced in rabbit myocardium in vivo by both ischaemia and heat shock, consistent with a fundamental role in the development of delayed adaptation. The well described role of PP2 in modulating the mitogen-activated protein kinase pathway and promoting cell survival is consistent with our previous work, which identified the reperfusion injury salvage kinase pathway in mediating the protective effects of ischaemic preconditioning. Expression of Trip1 and Ncbp1 also implicates TGFbeta signalling pathways and RNA processing and transport in delayed adaptation to stress in the myocardium.
Exp Mol Med 2005 Aug 31
PMID:Representational difference analysis of cDNA identifies novel genes expressed following preconditioning of the heart. 1615 8

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a promiscuous bHLH-PAS (Per-ARNT-Sim) protein that forms heterodimeric transcriptional regulator complexes with several other bHLH-PAS subunits to control a variety of biological pathways, some of which are centrally involved in disease initiation and/or progression. One of these is the hypoxia response pathway, which allows eukaryotic cells to respond to low oxygen tension via the formation of a heterodimeric complex between ARNT and another bHLH-PAS protein, the hypoxia-inducible factor alpha (HIF-alpha). We have previously shown that the C-terminal PAS domains of an HIF-alpha isoform (HIF-2alpha) and ARNT interact in vitro, and that mutations in the solvent-exposed beta-sheet surface of the HIF-2alpha domain not only disrupt this interaction, but also greatly attenuate the hypoxia response in living cells. Here, we have solved the solution structure of the corresponding PAS domain of ARNT and show that it utilizes a very similar interface for the interaction with the HIF-2alpha PAS domain. We also show that this domain self-associates in a concentration-dependent manner, and that the interface used in this homodimeric complex is very similar to that used in the formation of heterodimer. In addition, using experimentally derived NMR restraints, we used the program HADDOCK to calculate a low-resolution model of the complex formed in solution by these two PAS domains, and confirm the validity of this model using site-directed spin labeling to obtain long-range distance information in solution. With this information, we propose a model for the mode of multi-PAS domain interaction in bHLH-PAS transcriptional activation complexes.
J Mol Biol 2005 Oct 28
PMID:Structural basis of ARNT PAS-B dimerization: use of a common beta-sheet interface for hetero- and homodimerization. 1618 39

Evidence shows that the CD38 molecule, recently involved in the two main features of asthma, bronchial hyper-responsiveness and airway inflammation, could represent a new potential therapeutic target for asthma. In this study, we investigated whether glucocorticoid (GC), the most effective treatment for lung diseases, can affect CD38 expression in human airway smooth muscle (ASM) cells treated with different pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNFalpha) and interferons (IFNs). We found that CD38 expression induced by TNFalpha alone was completely abrogated by fluticasone (100 nM), dexamethasone (1 microM), or budesonide (100 nM). In contrast, the synergistic induction of CD38 by the combination of TNFalpha with IFNgamma or IFNbeta, but not with IL-1beta or IL-13, was completely insensitive to the GC inhibitory effects. We also found that TNFalpha and IFNgamma impaired GC responsiveness by inhibiting steroid induced both 1) GRalpha-DNA binding activity and 2) GC-responsive element-(GRE)-dependent gene transcription. Although levels of the GC receptor (GR) alpha isoform remained unchanged, expression of GRbeta, the dominant-negative GR isoform, was synergistically increased by TNFalpha and IFNgamma with a GRalpha/GRbeta ratio of 1 to 3. More importantly, fluticasone failed to induce GRE-dependent gene transcription and to suppress TNFalpha-induced CD38 expression in ASM cells transfected with constitutively active GRbeta. We conclude that, upon pro-inflammatory cytokine stimulation, CD38 expression becomes insensitive to GC action by a mechanism involving the up-regulation of GRbeta isoform, thus providing a novel in vitro cellular model to dissect GC resistance in primary cells.
Mol Pharmacol 2006 Feb
PMID:CD38 expression is insensitive to steroid action in cells treated with tumor necrosis factor-alpha and interferon-gamma by a mechanism involving the up-regulation of the glucocorticoid receptor beta isoform. 1629 71

G protein-coupled receptor (GPCR) kinases (GRKs) phosphorylate agonist-activated GPCRs, initiating their homologous desensitization. In this article, we present data showing that GRK4 constitutively phosphorylates the D1 receptor in the absence of agonist activation. This constitutive phosphorylation is mediated exclusively by the alpha isoform of GRK4; the beta, gamma, and delta isoforms are ineffective in this regard. Mutational analysis reveals that the constitutive phosphorylation mediated by GRK4alpha is restricted to the distal region of the carboxyl terminus of the receptor, specifically to residues Thr428 and Ser431. Phosphorylation of the D1 receptor by GRK4alpha results in a decrease in cAMP accumulation, an increase in receptor internalization, and a decrease in total receptor number--all of which are abolished in a D1 receptor mutant containing T428V and S431A. The increase in internalized D1 receptors induced by GRK4alpha phosphorylation is due to enhanced receptor internalization rather than retarded trafficking of newly synthesized receptors to the cell surface. The constitutive phosphorylation of the D1 receptor by GRK4alpha does not alter agonist-induced desensitization of the receptor because dopamine pretreatment produced a similar decrease in cAMP accumulation in control cells versus cells expressing GRK4alpha. These observations shift the attenuation of D1 receptor signaling from a purely agonist-driven process to one that is additionally modulated by the complement of kinases that are coexpressed in the same cell. Furthermore, our data provide direct evidence that, in contrast to current dogma, GRKs can (at least in some instances) constitutively phosphorylate GPCRs in the absence of agonist activation resulting in constitutive desensitization.
Mol Pharmacol 2006 Mar
PMID:The D1 dopamine receptor is constitutively phosphorylated by G protein-coupled receptor kinase 4. 1633 46

Epithelial cells in vivo exist as confluent cell sheets, but this confluence is disrupted if the sheets are wounded, if the cells are undergoing morphogenesis, or if they are taking part in invasion and metastasis. Desmosomes are one of the principal types of adhesive junctions in epithelia and are responsible for maintaining tissue integrity. It is likely that modulation of desmosomal adhesion is required to facilitate cell motility in response to alterations in the tissue architecture. Desmosomal adhesion changes from a calcium-dependent state to a calcium-independent state when cells become confluent. Our laboratory has shown that the alpha isoform of protein kinase C is involved in signaling the response of desmosomes to calcium concentration and wounding, in cultured epithelial cells and in mouse epidermis (in vivo).
Methods Mol Biol 2006
PMID:Assays for the calcium sensitivity of desmosomes. 1679 98

The Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII)beta has morphogenic functions in neurons not shared by the alpha isoform. CaMKIIbeta contains three exons (v1, v3, and v4) not present in the CaMKIIalpha gene, and two of these exons (v1 and v4) are subject to differential alternative splicing. We show here that CaMKIIbeta, but not alpha, mediated bundling of F-actin filaments in vitro. Most importantly, inclusion of exon v1 was required for CaMKIIbeta association with the F-actin cytoskeleton within cells. CaMKIIbetae, which is the dominant variant around birth and lacks exon v1 sequences, failed to associate with F-actin. By contrast, CaMKIIbeta', which instead lacks exon v4, associated with F-actin as full-length CaMKIIbeta. Previous studies with CaMKIIbeta mutants have indicated a role of nonstimulated kinase activity in enhancing dendritic arborization. Here, we show that F-actin-targeted CaMKIIbeta, but not alpha, was able to phosphorylate actin in vitro even by nonstimulated basal activity in absence of Ca(2+)/CaM. In rat pancreatic islets and in skeletal muscle, the actin-associated CaMKIIbeta' and betaM were the predominant variants, respectively. Thus, cytoskeletal targeting may mediate functions of CaMKIIbeta variants also outside the nervous system.
Mol Biol Cell 2006 Nov
PMID:CaMKIIbeta association with the actin cytoskeleton is regulated by alternative splicing. 1692 58

Alpha4 phosphoprotein in the mTOR pathway is a prolactin (PRL)-downregulated gene product that interacts with the catalytic subunit of serine/threonine protein phosphatase 2A (PP2Ac) in rat Nb2 lymphoma cells. Transient overexpression of alpha4 in COS-1 cells inhibited PRL-inducible interferon-regulatory-1 (IRF-1) promoter activity, but the mechanism underlying this inhibition was not known. The present study showed a stable alpha4-PP2Ac complex that was not dissociated by rapamycin in COS-1 cells. Transient overexpression of alpha4 in COS-1 cells had no effect on endogenous PP2Ac protein levels but significantly increased PP2Ac carboxymethylation and PP2A activity as compared to controls. The increased PP2A activity was accompanied by decreased phosphorylation of eukaryotic initiation factor 4E-binding protein (4E-BP1) but had no effect on Stat phosphorylation. However, overexpressed alpha4 decreased arginine methylation of Stat1alpha and increased Stat1alpha binding to the Stat1alpha-specific inhibitor, PIAS1. In summary, ectopic alpha4 increased PP2A activity in COS-1 cells and this was accompanied by Stat1alpha hypomethylation and increased Stat1alpha-PIAS1 association. These events would inhibit Stat action and ultimately inhibit PRL-inducible IRF-1 promoter activity.
Mol Cell Endocrinol 2007 Jan 15
PMID:Overexpression of the mTOR alpha4 phosphoprotein activates protein phosphatase 2A and increases Stat1alpha binding to PIAS1. 1708 18

Lung development depends upon the differentiation and expansion of a variety of specialized epithelial cell types, including distal type I and type II pneumocytes in the late term. Previous studies have shown a strict dependence on the choline cytidylyltransferase alpha isoform (CCTalpha) to mediate membrane phospholipid formation in cultured cells and during preimplantation embryogenesis. CCTalpha expression is highest in lung, and there has long been speculation about its precise role, due to the dual requirement for phospholipid in proliferating cell membranes and for lung surfactant production from alveolar type II cells. We investigated the function of CCTalpha in lung development, using an inducible, epithelial cell-specific CCTalpha knockout mouse line. Deletion of CCTalpha beginning at embryonic day 7.5 did not restrict lung development but resulted in severe respiratory failure at birth. Alveolar lavage and lung lipid analyses showed significant decreases in the major surfactant phospholipid, dipalmitoyl-phosphatidylcholine. The fatty acids destined for the surfactant phospholipid were redirected to an expanded triglyceride pool. Transcripts encoding type II cell-specific markers were expressed in the knockout mice, indicating the expected progression of differentiation in lung epithelia. However, surfactant protein levels were reduced, with the exception of that for surfactant protein B, which was elevated. Ultrastructural analysis of the type II cells showed Golgi complex abnormalities and aberrant lamellar bodies, which deliver surfactant lipid and protein to the alveolar lumen. Thus, CCTalpha was not required for the proliferation or differentiation of lung epithelia but was essential for the secretory component of phospholipid synthesis and critical for the proper formation of lamellar bodies and surfactant protein homeostasis.
Mol Cell Biol 2007 Feb
PMID:Role of phosphocholine cytidylyltransferase alpha in lung development. 1713 Feb 38

The catalytic subunit of PP2A (PP2Ac) can be purified in milligram quantities from bovine heart using ethanol precipitation, ammonium sulfate precipitation, ion exchange and size exclusion chromatography. The detailed procedure is described to purify PP2Ac over 4 d.
Methods Mol Biol 2007
PMID:Purification of PP2Ac from bovine heart. 1720 May 59

Forkhead transcription factors of the O class (FOXOs) are important targets of the phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway. FOXOs have been implicated in the regulation of cell cycle progression, oxidative stress resistance, and apoptosis. Using DNA microarrays, we analyzed the transcriptional response to FOXO3a activation by gene expression analysis in DLD-1 colon cancer cells stably expressing a FOXO3a.A3-ER fusion protein. We found that activation of FOXO3a resulted in repression of a number of previously identified Myc target genes. Furthermore, FOXO3a activation induced expression of several members of the Mad/Mxd family of transcriptional repressors, most notably Mxi1. The induction of Mxi1 by FOXO3a was specific to the Mxi1-SR alpha isoform and was mediated by three highly conserved FOXO binding sites within the first intron of the gene. Activation of FOXO3a in response to inhibition of Akt also resulted in activation of Mxi1-SR alpha expression. Silencing of Mxi1 by small interfering RNA (siRNA) reduced FOXO3a-mediated repression of a number of Myc target genes. We also observed that FOXO3a activation induced a switch in promoter occupancy from Myc to Mxi1 on the E-box containing promoter regions of two Myc target genes, APEX and FOXM1. siRNA-mediated transient silencing of Mxi1 or all Mad/Mxd proteins reduced exit from S phase in response to FOXO3a activation, and stable silencing of Mxi1 or Mad1 reduced the growth inhibitory effect of FOXO3a. We conclude that induction of Mad/Mxd proteins contributes to the inhibition of proliferation in response to FOXO3a activation. Our results provide evidence of direct regulation of Mxi1 by FOXO3a and imply an additional mechanism through which the PI3-kinase/Akt/FOXO pathway can modulate Myc function.
Mol Cell Biol 2007 Jul
PMID:Induction of Mxi1-SR alpha by FOXO3a contributes to repression of Myc-dependent gene expression. 1745 51


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