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14-3-3 interacts with the tumor suppressor tuberin at Akt phosphorylation site(s).

Tuberin, the product of the tuberous sclerosis complex 2 tumor suppressor gene, is a phosphoprotein that negatively regulates phosphatidylinositol 3'-kinase signaling downstream of Akt. Several high stringency 14-3-3 binding sites that overlapped with Akt phosphorylation sites were identified in tuberin in silico. Recognition of tuberin by an alpha-14-3-3 binding site-specific antibody correlated with mitogen-induced phosphorylation of tuberin and recognition of tuberin by an alpha-Akt phosphorylation substrate antibody. Recognition of tuberin by both antibodies was blocked by inhibiting phosp…

Late-onset corticohippocampal neurodepletion attributable to catastrophic failure of oxidative phosphorylation in MILON mice.

We generated mitochondrial late-onset neurodegeneration (MILON) mice with postnatal disruption of oxidative phosphorylation in forebrain neurons. They develop normally and display no overt behavioral disturbances or histological changes during the first 5 months of life. The MILON mice display reduced levels of mitochondrial DNA and mitochondrial RNA from 2 and 4 months of age, respectively, and severely respiratory chain-deficient neurons from 4 months of age. Surprisingly, these respiratory chain-deficient neurons are viable for at least 1 month without showing signs of neurodegeneration or …

Nitric oxide increases albumin permeability of isolated rat glomeruli via a phosphorylation-dependent mechanism.

Nitric oxide (NO) has been implicated in the induction of proteinuria in acute inflammatory glomerulonephritis and in the increased vascular … n, could largely prevent the effect of SNAP and DETA-NONOate confirmed the crucial role of tyrosine phosphorylation in the NO-induced increase of P(a). Furthermore, the tyrosine phosphatase inhibitor, phenylarsine oxide (PAO), could mimic the action of NO on P(a). NO-enhanced tyrosine phosphorylation was further confirmed by immunofluorescence staining, where pos …

TSC2 missense mutations inhibit tuberin phosphorylation and prevent formation of the tuberin-hamartin complex.

Tuberous sclerosis (TSC) is an autosomal dominant disorder characterized by a broad phenotypic spectrum that includes seizures, mental retar … mportant for the interaction with hamartin to be pin-pointed. In addition, the results confirm that phosphorylation may play an important role in the formation of the tuberin-hamartin complex. Although mutations that prevent tuberin tyrosine phosphorylation also inhibit tuberin-hamartin binding and the chaperone function, our results indicate that only hamartin i …

Cerebral ischemia and seizures induce tyrosine phosphorylation of PYK2 in neurons and microglial cells.

The nonreceptor tyrosine kinase PYK2 represents a stress-sensitive mediator of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK) signaling pathways in many cell types. In the present study, we assessed the tyrosine phosphorylation of PYK2 under normal and pathological conditions in the CNS. We generated a polyclonal antibody that selectively recognizes tyrosine-phosphorylated PYK2 at its major autophosphorylation site. By using this antibody, we demonstrate that the phosphorylation profile of PYK2 after focal cerebral ischemia is biphasic. The first phase occurs within 1 …

Nitric oxide inhibits chondrocyte response to IGF-I: inhibition of IGF-IRbeta tyrosine phosphorylation.

Chondrocytes in arthritic cartilage respond poorly to insulin-like growth factor I (IGF-I). Studies with inducible nitric oxide synthase (iN … dium nitrite, and proteoglycan synthesis was measured as incorporation of (35)SO(4). IGF-I receptor phosphorylation was evaluated with Western analysis. SNAP, DETA NONOate, endogenously synthesized NO in Ad-iNOS-transduced cells, or IL-1 activation decreased IGF-I-stimulated proteoglycan synthesis in cartilage and monolayer cultures of chondrocytes. OA cartilage …

Phosphorylation of presenilin-2 regulates its cleavage by caspases and retards progression of apoptosis.

Mutations within the Presenilin-2 (PS-2) gene are associated with early onset familial Alzheimer's disease. The gene encodes a polytopic transmembrane protein that undergoes endoproteolytic processing resulting in the generation of N-terminal and C-terminal fragments (CTFs). PS-2 is also cleaved by proteases of the caspase family during apoptotic cell death. CTFs of PS-2 were shown to inhibit apoptosis, suggesting an important role in the regulation of programmed cell death. Recently, we found that the CTF of PS-2 is phosphorylated in vivo. We mapped the in vivo phosphorylation sites of PS-2 t…

Ser16 prevails over Thr17 phospholamban phosphorylation in the beta-adrenergic regulation of cardiac relaxation.

Phospholamban is a critical regulator of sarcoplasmic reticulum Ca2+-ATPase and myocardial contractility. To determine the extent of cross signaling between Ca2+ and cAMP pathways, we have investigated the beta-adrenergic-induced phosphorylation of Ser16 and Thr17 of phospholamban in perfused rat hearts using antibodies recognizing phospholamban phosphorylated at either position. Isoproterenol caused the dose-dependent phosphorylation of Ser16 and Thr17 with strikingly different half-maximal values (EC50 = 4.5 +/- 1.6 and 28. 2 +/- 1.4 nmol/l, respectively). The phosphorylation of Ser16 induce…

Inhibition of the insulin receptor kinase phosphorylation by nitric oxide: functional and structural aspects.

Previous studies on cultured skeletal muscle cells have indicated that the insulin-induced expression of GLUT4 transporter protein is inhibited by nitric oxide (NO). Therefore, we determined the effect of NO on the insulin-induced autophosphorylation of the insulin receptor kinase (IRK), i.e., the first step in the insulin-mediated signal transduction pathway. The experiments showed that the insulin-induced autophosphorylation of the insulin receptor beta-chain is strongly inhibited by the NO donors 1,1-diethyl-2-hydroxy-2-nitrosohydrazine (DEA-NO) or S-nitroso-N-acetylpenicillamine (SNAP). Th…

CFTR activation: additive effects of stimulatory and inhibitory phosphorylation sites in the R domain.

To investigate the functional significance of individual consensus phosphorylation sites within the R domain of cystic fibrosis transmembrane conductance regulator (CFTR), serines were eliminated by substituting them with alanine. Included in this analysis were serine-660, -670, -686, -700, -712, -737, -768, -795, and -813, which lie within protein kinase A consensus sequences, and serine-641, which does not. Elimination of single potential phosphorylation sites altered the sensitivity of CFTR (expressed in Xenopus oocytes) to activating conditions in a manner that was highly site dependent. S…

Phosphorylation by neuronal cdc2-like protein kinase promotes dimerization of Tau protein in vitro.

In Alzheimer's disease, the microtubule-associated protein tau forms paired helical filaments (PHFs) that are the major structural component of neurofibrillary tangles. Although tau isolated from PHFs (PHF-tau) is abnormally phosphorylated, the role of this abnormal phosphorylation in PHF assembly is not known. Previously, neuronal cdc2-like protein kinase (NCLK) was shown to phosphorylate tau on sites that are abnormally phosphorylated in PHF-tau (Paudel, H. K., Lew, J., Ali, Z., and Wang, J. H. (1993) J. Biol. Chem. 268, 23512-23518). In this study, phosphorylation by NCLK was found to promo…

The GPI-anchored adhesion molecule F3 induces tyrosine phosphorylation: involvement of the FNIII repeats.

The glycosyl-phosphatidylinositol (GPI)-anchored F3 molecule, a member of the Ig superfamily made up of Ig and FNIII-like domains, is involved in cell-cell adhesion, neuronal pathfinding and fasciculation. Little is known about the mechanism(s) that governs the F3-mediated cell-cell recognition. In particular, it is not known whether F3 transduces signals across the membrane. Here we show that in F3-transfected CHO cells (1A cells) an increase in tyrosine phosphorylation occurs during F3-mediated aggregation. Moreover, under aggregation conditions F3 immunoprecipitated from 32P-metabolically l…

Voltage-dependent potentiation of neuronal L-type calcium channels due to state-dependent phosphorylation.

Modulation of Ca2+ channels during repetitive activity in excitable cells can have an important role in altering cellular function. In mammalian parasympathetic and dorsal root ganglion neurons, L-type Ca2+ channels are potentiated by single depolarizing prepulses or trains of short high-frequency depolarizing pulses. This type of potentiation takes place regardless of whether Ca2+ or Ba2+ is the charge carrier and requires phosphorylation by a adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase. The magnitude of facilitation was correlated with frequency of conditioning train…

Stage-specific changes in protein phosphorylation during spore germination in Dictyostelium: role of calmodulin.

Extensive protein phosphorylation occurs during all phases of spore germination in Dictyostelium discoideum. The developmental changes were prevented when germination was inhibited by inhibitors of calmodulin function. In addition, differences in patterns of phosphorylation were detected based upon the method of spore activation. Several phosphoproteins were lost in heat activated as compared to autoactivated spores. In spite of the fact that several aspects (i.e. autoactivation, emergence) are calmodulin-dependent, there was no evidence that calcium- or calmodulin-dependent protein kinase act…

Нейрональные и глиальные включения в различные неврологические заболевания имеют общие характеристики фосфорилации.

Аккумуляция тау в виде парных вертолётных ниток (PHF) в мозге болезни Альцгеймера считается аномальной фосфорилированной на отдельных участках. Для сравнения состояния фосфорилации тау-позитивных нейронных интеграций среди различных неврологических заболеваний мы провели обследование этих повреждений с помощью трех четко определенных PHF/tau моноклоналов, C5, M4 и tau 1, которые, скорее всего, распознают три участка фосфорилирования с пролинным курсом в PHF-tau. В мозге болезни Альцгеймера все три моноклана, сильно иммунизированные внутриклеточные нейрофибрилляторы, нейропильные нити, старинны

Совпадение в аннотации оригинала
Tau accumulating as paired helical filaments (PHF) in Alzheimer's disease brain is considered to be abnormally phosphorylated on distinct sites. To compare the phosphorylation state of tau-positive neuronal inclusions among diverse neurologic diseases, we have probed these lesions with three well-defined PHF/tau monoclonals, C5, M4 and tau 1, that most likel…

Rat submandibular and parotid protein phosphorylation and exocytosis: effect of site-selective cAMP analogs.

A series of cAMP analogs that have different specificities for the two different binding sites on the regulatory subunit of type I and type II cAMP-dependent protein kinase (PKA) were used to determine whether selective activation of type I or type II PKA could link either or both isozyme forms of PKA with exocytosis and specific protein phosphorylation in salivary gland cells. Using dispersed rat submandibular or parotid cells, selective activation of either type I or type II resulted in a synergistic response for both rat submandibular mucin and parotid amylase secretion and the phosphorylat…

Studies on mitochondrial oxidative phosphorylation in permeabilized human skin fibroblasts: application to mitochondrial encephalomyopathies.

In this report we describe that the functional capacity of the mitochondrial oxidative phosphorylation system can be studied in cultured skin fibroblasts permeabilized with a limited amount of digitonin. By using a variety of different oxidizable substrates, information can be obtained on the functional activity of complex I, for instance, which is important since different diseases in man have recently been identified in which complex I is deficient. The method described may contribute to the biochemical characterization of patients suffering from one of a variety of encephalomyopathies.

Expression of myosin regulatory light-chain isoforms and regulation of phosphorylation in smooth muscle.

Our objectives were to 1) determine how growth state and cell density affect the expression of the smooth muscle (SM) and nonmuscle (NM) isoforms of the 20-kDa myosin regulatory light chains (MLC20) in cultured rat aortic smooth muscle cells (SMC) and 2) to determine whether angiotensin II stimulates differential phosphorylation of SM and NM MLC20 isoforms in an effort to assess whether the SM and NM isoforms may subserve different cellular functions. The results demonstrated that changes in the SM MLC20 isoform content were inversely correlated with cell growth but independent of cell density…

Ethanol modulates epidermal growth factor-stimulated tyrosine kinase and phosphorylation of PLC-gamma 1.

A431 cells have an abundance of Epidermal Growth Factor (EGF) receptors which possess intrinsic tyrosine kinase activity. Treatment of membranes isolated from A431 cells with EGF caused a 2-3 fold increase in phosphorylation of a synthetic peptide (Arg-Arg-Leu-Ile-Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Gly) which is a substrate for tyrosine kinase. Treatment of these membranes with 0.1 to 100 mM ethanol altered basal tyrosine kinase activity in a biphasic manner; increase at 10 mM and decrease at 100 mM ethanol. The treatment of the membranes with the same concentrations of ethanol also altered EGF's…

Oxidative phosphorylation in human muscle in patients with ocular myopathy and after general anaesthesia.

The fuel preference of human muscle mitochondria has been given. Substrates which are oxidized with low velocity cannot be used to detect defects in oxidative phosphorylation. After general anaesthesia, the oxygen uptake with the different substrates is much lower than after local analgesia. The latter was therefore used in the subsequent study. In 15 out of 18 patients with ocular myopathy, defects in oxidative phosphorylation could be detected in isolated muscle mitochondria prepared from freshly biopsied tissue. Measurement of the activity of segments of the respiratory chain in homogenate …