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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CD5 acts as a coreceptor on T lymphocytes and plays an important role in T-cell signaling and T-cell-B-cell interactions. Costimulation of T lymphocytes with anti-CD5 antibodies results in an increase of the intracellular Ca2+ levels, and subsequently in the activation of Ca2+/calmodulin-dependent (CaM) kinase type IV. In the present study, we have characterized the initial signaling pathway induced by anti-CD5 costimulation. The activation of phosphatidylinositol (PI) 3-kinase through tyrosine phosphorylation of its p85 subunit is a proximal event in the CD5-signaling pathway and leads to the activation of the lipid kinase activity of the p110 subunit. The PI 3-kinase inhibitors wortmannin and LY294002 inhibit the CD5-induced response as assessed in interleukin-2 (IL-2) secretion experiments. The expression of an inactivated Rac1 mutant (Rac1.N17) in T lymphocytes transfected with an IL-2 promoter-driven reporter construct also abrogates the response to CD5 costimulation, while the expression of a constitutively active Rac1 mutant (Rac1-V12) completely replaces the CD5 costimulatory signal. The Rac1-specific guanine nucleotide exchange factor Vav is heavily phosphorylated on tyrosine residues upon CD5 costimulation, which is a prerequisite for its activation. A role for Vav in the CD5-induced signaling pathway is further supported by the findings that the expression of a dominant negative Vav mutant (Vav-C) completely abolishes the response to CD5 costimulation while the expression of a constitutively active Vav mutant [Vav(delta1-65)] makes the CD5 costimulation signal superfluous. Wortmannin is unable to block the Vav(delta1-65)- or Rac1.V12-induced signals, indicating that both Vav and Rac1 function downstream from PI 3-kinase. Vav and Rac1 both act upstream from the CD5-induced activation of CaM kinase IV, since KN-62, an inhibitor of CaM kinases, and a dominant negative CaM kinase IV mutant block the Vav(delta1-65)-and Rac1.V12-mediated signals. We propose a model for the CD5-induced signaling pathway in which the PI 3-kinase lipid products, together with tyrosine phosphorylation, activate Vav, resulting in the activation of Rac1 by the Vav-mediated exchange of GDP for GTP.
Mol Cell Biol 1998 Mar
PMID:Signaling through CD5 activates a pathway involving phosphatidylinositol 3-kinase, Vav, and Rac1 in human mature T lymphocytes. 948 89

Ca2+/calmodulin-dependent protein kinase (CaM kinase) I and IV are thought to be activated by CaM kinase kinases (CaMKK). We examined the distribution of mRNAs for two isoforms (alpha and beta) of CaMKKs in the brain by in situ hybridization histochemistry. In the adult rat brain, CaMKK alpha mRNAs are widely distributed throughout the brain, whereas CaMKK beta mRNAs are restricted to some neuronal populations, particularly the cerebellar granule cells.
Brain Res Mol Brain Res 1998 Mar 01
PMID:Localization of the mRNAs for two isoforms of Ca2+/calmodulin-dependent protein kinase kinases in the adult rat brain. 955 71

The control of glucose homeostasis by insulin requires, in addition to the glucose-induced insulin release, a highly dynamic control of insulin biosynthesis. Although elevated glucose concentrations have been shown to trigger insulin biosynthesis at the levels of transcription and translation, the molecular mechanisms underlying the immediate transcriptional control are poorly understood. By investigating signal transduction pathways involved in the "glucose-dependent" transcriptional control, thereby analyzing endogenous (prepro)insulin mRNA levels and monitoring on-line insulin promoter-driven GFP expression, we provide, for the first time, evidence that physiologically stimulated insulin secretion from the pancreatic beta cell promotes insulin biosynthesis by enhancing insulin gene transcription in an autocrine manner. We show that secreted insulin acts via beta-cell insulin receptors and up-regulates insulin gene transcription by signaling through the IRS-2/PI-3 kinase/p70 s6k and CaM kinase pathways.
Mol Cell 1998 May
PMID:Exocytosis of insulin promotes insulin gene transcription via the insulin receptor/PI-3 kinase/p70 s6 kinase and CaM kinase pathways. 966 Sep 77

To investigate the molecular mechanisms of stimuli-induced transcriptional activation in neuronal cells, we have investigated the light-induced gene expression in the neural retina of rats. The immunoreactivity for phosphorylated cAMP responsive element binding protein (PCREB-IR) was expressed in the outer half of the inner nuclear layer (INL) and the ganglion cell layer (GCL) after 5 min exposure to steady light also in mice. In addition to these cells, PCREB-IR was also detected in the inner border of the INL after 5 min exposure to flashing light. Both steady and flashing lights induced c-fos mRNA in the same types of cells as the PCREB-IR-positive cells. Majority of PCREB immunoreactive nuclei in the outer half of the INL were also immunopositive for anti-protein kinase C alpha (PKC alpha), a marker of rod bipolar cells, while CaM kinase IV immunoreactivity was not detected in these cells. PCREB-IR and c-fos gene expression in the PKC alpha positive rod bipolar cells were lost in mice lacking metabotropic glutamate receptor 6 (mGluR6). Thus, we propose that the transcriptional response of CREB to light stimulation in rod bipolar cells is regulated via mGluR6.
Brain Res Mol Brain Res 1998 Jun 15
PMID:CREB-induced transcriptional activation depends on mGluR6 in rod bipolar cells. 967 22

As it is known that ryanodine receptor type 3 is expressed in the hippocampus, we examined the contribution of this receptor to contextual fear conditioning behavior and to the activation of Ca(2+)/calmodulin-dependent protein kinase II using mice lacking the receptor. Ryanodine receptor type 3-deficient mice exhibited impairments of performance in the contextual fear conditioning test, passive avoidance test, and Y-maze learning test. Both the activities of Ca(2+)/calmodulin-dependent protein kinase IIbeta and Ca(2+)/calmodulin-dependent protein kinase IIalpha were significantly increased in the experimental group compared to the control group in the hippocampus, but not in the cingulate cortex on the testing day 24 h after contextual fear training. However, the activities of Ca(2+)/calmodulin-dependent protein kinase IIbeta and alpha were almost the same in the experimental and control groups in the hippocampus on the training day. Ryanodine receptor type 3-deficient mice did not show the increment of Ca(2+)/calmodulin-dependent protein kinase IIbeta and alpha activities in the hippocampus on the testing day. In addition, these mutant mice showed the reduction of fear response in the elevated plus-maze test. The present results suggest that calcium-induced calcium release through the activation of ryanodine receptor type 3 in the hippocampus is important to the expression of the performance of contextual learning through the elevation of Ca(2+)/calmodulin-dependent protein kinase IIbeta and alpha activities.
Brain Res Mol Brain Res 2000 Mar 10
PMID:Mutant mice lacking ryanodine receptor type 3 exhibit deficits of contextual fear conditioning and activation of calcium/calmodulin-dependent protein kinase II in the hippocampus. 1071 24

1. Changes in the phosphorylation state of AMPA-type glutamate receptors are thought to underlie activity-dependent synaptic modification. It has been established that the GluR1 subunit is phosphorylated on two distinct sites, Ser-831 and Ser-845, by CaMKII and by PKA, respectively, and that phosphorylation by either kinase correlates with an increase in the AMPA receptor-mediated current. GluR1 is concentrated in postsynaptic densities and it is expected that this particular receptor pool is involved in synaptic modification. The present study describes the regulation of the phosphorylation state of GluR1 in isolated postsynaptic densities. 2. Addition of Ca2+/calmodulin to the postsynaptic density fraction promotes phosphorylation of GluR1, and under these conditions, dephosphorylation is prevented by the inclusion of phosphatase type 1 inhibitors, microcystin-LR and Inhibitor-1. CaMKII and phosphatase type 1 are also found to be enriched in the PSD fraction compared to the parent fractions. 3. On the other hand, the addition of cAMP, either by itself or with exogenous PKA, does not change the phosphorylation state of GluR1. Prior incubation of PSDs under dephosphorylating conditions results in only a small PKA-mediated phosphorylation of GluR1. 4. These results support the hypothesis that PSDs contain the molecular machinery to promote the phosphorylation as well as the dephosphorylation of GluR1 on Ser-831, while Ser-845, the site phosphorylated by PKA, appears to be mostly occluded. Thus, it is possible that a large pool of PSD-associated GluR1 is regulated through modification of the phosphorylation state of the Ser-831 site only.
Cell Mol Neurobiol 2000 Aug
PMID:Regulation of the phosphorylation state of the AMPA receptor GluR1 subunit in the postsynaptic density. 1090 Dec 66

The decrease in mu-opioid receptor activity after chronic agonist exposure (1 microM [D-Ala(2),N-MePhe(4),Gly-ol(5)]-enkephalin) is largely due to kinase-mediated phosphorylation of intracellular receptor domains. We have recently shown that the substitution of two putative Ca(2+)/calmodulin-dependent protein kinase II (CaMK II) phosphorylation sites, S261 and S266, by alanines in the third intracellular loop of the rat mu-opioid receptor (rMOR1) confers resistance to CaMK II-induced receptor desensitization. In the present study, we show that the injection of active CaMK II in Xenopus laevis oocytes led to the desensitization of S261A but not S266A receptor mutant, indicating that S266 is the primary CaMK II phosphorylation site of the rMOR1. For the corresponding phosphorylation site in the human mu-opioid receptor (hMOR), an allelic variation S268P has been recently identified. After expression in X. laevis oocytes and human embryonic kidney 293 cells, this human S268P receptor and a corresponding rat S266P receptor mutant revealed a loss of CaMK II-induced receptor desensitization and a decreased G protein coupling compared with the wild-type receptors. Our results suggest that serines 266 (rMOR1) and 268 (hMOR) play crucial role in receptor desensitization and signaling and that the allelic variation S268P results in a human receptor type with a weaker but persistent G protein coupling after agonist treatment.
Mol Pharmacol 2000 Aug
PMID:Allelic variation S268P of the human mu-opioid receptor affects both desensitization and G protein coupling. 1090

Parathyroid hormone (PTH), a powerful bone-resorbing agent, is capable of stimulating interstitial collagenase (MMP-13) mRNA production in osteoblastic cells. In this study, a PEA3 consensus binding sequence (-80; AGGAAGT) in addition to a 'TRE-like' sequence (-89; CGACTCA) in the 5' upstream regulatory region of the rat MMP-13 gene were examined. In response to PTH, there was a time-dependent increase in binding of nuclear factors to an oligonucleotide containing the PEA3 region (-95 to -71). This increase in binding was first observed at 0.5 h, peaked at 4 h (7. 6-fold) then returned to basal levels by 24 h. Mutagenesis of the PEA3 site in a chloramphenicol acetyl transferase (CAT) construct containing 5' upstream regulatory sequence of the rat MMP-13 gene significantly decreased activation by PTH. PTH-mediated binding of nuclear factors to an oligonucleotide containing the mutant PEA3 sequence was decreased as compared with the wild type. Mutation or deletion of the TRE-like sequence affected basal as well as PTH-mediated induction of corresponding CAT constructs. Treatment with KN93, a Ca(2+)/calmodulin-dependent protein kinase II specific inhibitor, greatly reduced the amount of protein binding to the PEA3 region in response to PTH which correlated to a notable decrease in the amount of MMP-13 mRNA produced in response to PTH. Antibodies against Ets-1, cyclic AMP response element (CREB)-binding protein (CBP) and CREB were capable of supershifting proteins binding to the oligonucleotide containing the PEA3 region. These data suggest a possible co-operative interaction of factors binding to the PEA3 and TRE-like sequences and provide the first indication of a role for a calcium-mediated pathway in the PTH induction of MMP-13 mRNA in osteoblastic cells.
J Mol Endocrinol 2000 Aug
PMID:Parathyroid hormone induces rat interstitial collagenase mRNA through Ets-1 facilitated by cyclic AMP response element-binding protein and Ca(2+)/calmodulin-dependent protein kinase II in osteoblastic cells. 1091 20

Different isoforms of the microtubule-associated protein 2 (MAP2) are somatodendritic components of neurons that seem to regulate the stability of the dendritic cytoskeleton. MAP2 localization into dendrites appears to be a complex multicausal mechanism that involves the specific recruitment of MAP2 mRNAs into dendritic compartments. Recently, we have functionally characterized a 640-nucleotide dendritic targeting element (DTE) in the 3' untranslated region (3' UTR) of MAP2 transcripts that mediates extrasomatic mRNA localization in primary neurons (Blichenberg et al. , 1999). In analogy to molecular mechanisms regulating cytoplasmic RNA translocation in other cell systems, we propose that, in vivo, the cis-acting MAP2-DTE interacts with specific protein factors present in neurons. To identify putative trans-acting DTE-binding proteins, we performed in vitro ultraviolet crosslinking assays. Using this experimental system, two 90-kDa and 65-kDa MAP2-RNA trans-acting proteins, MARTA1 and MARTA2, were identified in rat-brain extracts. Both MARTAs bind with high affinity to the MAP2-DTE, but not to other investigated regions of MAP2 transcripts or the somatically restricted alpha-tubulin mRNA. Moreover, MARTA1 and MARTA2 do not bind significantly to other dendritically localized transcripts encoding vasopressin and arg3.1, nor to a dendritic trafficking element from the mRNA encoding the alpha-subunit of the Ca(2+)/calmodulin-dependent protein kinase II. Binding of MARTA1 and MARTA2 to the MAP2-DTE occurs with an affinity in the nanomolar range. Whereas MARTA1 is clearly detectable in crude lysates, cytosolic and ribosomal salt-wash fractions, and in nuclear extracts, MARTA2 is preferentially found in the ribosomal salt-wash preparation. Neither MARTA is restricted to rat brain, and both are present in a number of other rat tissues. Thus, both proteins may be involved in a variety of nuclear and cytoplasmic events that regulate RNA metabolism in different cell types.
Brain Res Mol Brain Res 2000 Jun 23
PMID:Two trans-acting rat-brain proteins, MARTA1 and MARTA2, interact specifically with the dendritic targeting element in MAP2 mRNAs. 1092 59

Skeletal muscle differentiation is controlled by associations between myogenic basic-helix-loop-helix and MEF2 transcription factors. We show that chromatin associated with muscle genes regulated by these transcription factors becomes acetylated during myogenesis and that class II histone deacetylases (HDACs), which interact with MEF2, specifically suppress myoblast differentiation. These HDACs do not interact directly with MyoD, yet they suppress its myogenic activity through association with MEF2. Elevating the level of MyoD can override the repression imposed by HDACs on muscle genes. HDAC-mediated repression of myogenesis also can be overcome by CaM kinase and insulin-like growth factor (IGF) signaling. These findings reveal central roles for HDACs in chromatin remodeling during myogenesis and as intranuclear targets for signaling pathways controlled by IGF and CaM kinase.
Mol Cell 2000 Aug
PMID:Regulation of skeletal myogenesis by association of the MEF2 transcription factor with class II histone deacetylases. 1098 72


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