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T Haga

Publications and source records attributed to T Haga.

At least 19 recordsLinked to original sources
PubMed1995

Molecular cloning and characterization of a new member of the RAC protein kinase family: association of the pleckstrin homology domain of three types of RAC protein kinase with protein kinase C subspecies and beta gamma subunits of G proteins.

cDNA clones encoding the third member of the RAC protein kinase family, termed RAC-PK gamma, were isolated from a rat brain cDNA library. The deduced amino acid sequence of RAC-PK gamma was highly related to those of previously identified family members, RAC-PK alpha and beta, that have a pleckstrin homology domain and a protein-serine/threonine kinase catalytic domain at the amino- and carboxyl-terminal regions, respectively. Northern blot analysis indicated that RAC-PK gamma was expressed abundantly in brain and testis. Specific activities of RAC-PK alpha, beta, and gamma purified from transfected COS-7 cells were similar when measured by using myelin basic protein as a phosphate acceptor. Analysis using fusion proteins of glutathione S-transferase revealed that the pleckstrin homology domain of the three subtypes of RAC-PK associate with both protein kinase C subspecies and beta gamma subunits of G proteins. These results suggest that the pleckstrin homology domains of RAC protein kinase family could associate more than one protein to regulate the activity and/or intracellular distribution of this enzyme family by different ways.

Amino Acid Sequence↗
PubMed1995

Characterization of Gq family G proteins GL1 alpha (G14 alpha), GL2 alpha (G11 alpha), and Gq alpha expressed in the baculovirus-insect cell system.

The alpha subunits of Gq family G proteins, GL1 alpha (G14 alpha), GL2 alpha(G11 alpha), and Gq alpha were expressed with G protein beta 1 and gamma 2 subunits in insect cells using a baculovirus system. The trimeric forms of G proteins, GL1 (GL1 alpha beta gamma), GL2 (GL2 alpha beta gamma), and Gq (Gq alpha beta gamma), were solubilized by 1% sodium cholate and purified by sequential chromatography on three kinds of columns. GL1, GL2, and Gq activated phospholipase C-beta purified from bovine brain in the presence of aluminum fluoride to the same extent. Muscarinic acetylcholine receptor m1 subtype stimulated the guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) binding to GL1, GL2, and Gq in the presence of similar concentrations of carbamylcholine. When m1 receptor, G protein, and phospholipase C-beta were reconstituted in lipid vesicles, each subtype of Gq family G proteins mediated the activation of phospholipase C-beta by carbamylcholine in the presence of either 1 microM GTP gamma S or 1 mM GTP. Phospholipase C-beta stimulated the GTPase activity of GL1, GL2, and Gq in the presence of m1 receptor and carbamylcholine but did not stimulate the GTPase activity of GO. Protein kinase C phosphorylated m1 receptor and phospholipase C-beta, but the phosphorylation did not significantly affect the ability of the m1 receptor to stimulate phospholipase C-beta in the reconstitution system of purified proteins.

Animals↗
PubMed1995

Ligand binding properties of muscarinic acetylcholine receptor subtypes (m1-m5) expressed in baculovirus-infected insect cells.

Five subtypes of muscarinic acetylcholine receptors (m1-m5) have been expressed in insect cells (Spodoptera frugiperda, Sf9) using the baculovirus system. Up to 6 nmol of muscarinic acetylcholine receptors were produced by 1 liter culture; 0.3 to 0.6 (human m1), 3 to 6 (human m2), 2 to 4 (rat m3), 1 to 2 (rat m4) and 0.5 to 1 (human m5) nmol. Pirenzepine, AF-DX116 and hexahidrosiladifenidol showed the highest affinity for the m1, m2 and m3 subtype, respectively, indicating that these receptors expressed in Sf9 cells retain the same substrate specificity as those in mammalian tissues or cultured cells. Among 32 kinds of muscarinic ligands examined in the present studies, prifinium was found to have the highest affinity for the m4 subtype, and pilocarpine, oxotremorine, McN-A343 and promethazine the highest affinity for the m5 subtype, although the differences in the affinities among the five subtypes were less than 10-fold. Alcuronium increased the binding of [3H]N-methylscopalamine to the m2 subtype, but not the m1, m4 and m5 subtypes and only slightly to the m3 subtype. Similar but smaller effects of fangchinoline and tetrandrine were found for [3H]N-methylscopalamine binding to only the m3 subtype. These effects may also be useful for the discrimination of individual subtypes.

Animals↗
PubMed1994

Sequestration of muscarinic acetylcholine receptor m2 subtypes. Facilitation by G protein-coupled receptor kinase (GRK2) and attenuation by a dominant-negative mutant of GRK2.

Sequestration of m2 receptors (muscarinic acetylcholine receptor m2 subtypes), which was assessed as loss of N-[3H]methylscopolamine ([3H]NMS) binding activity from the cell surface, was examined in COS 7 and BHK-21 cells that had been transfected with expression vectors encoding the m2 receptor and, independently, vectors encoding a G protein-coupled receptor kinase (GRK2) (beta-adrenergic receptor kinase 1) or a GRK2 dominant-negative mutant (DN-GRK2). The sequestration of m2 receptors became apparent when the cells were treated with 10(-5) M or higher concentrations of carbamylcholine. In this case, approximately 40% or 20-25% of the [3H]NMS binding sites on COS 7 or BHK-21 cells, respectively, were sequestered with a half-life of 15-25 min. In cells in which GRK2 was also expressed, the sequestration became apparent in the presence of 10(-7) M carbamylcholine. Approximately 40% of the [3H]NMS binding sites on both COS 7 and BHK-21 cells were sequestered in the presence of 10(-6) M or higher concentrations of carbamylcholine. When DN-GRK2 was expressed in COS 7 cells, the proportion of [3H]NMS binding sites sequestered in the presence of 10(-5) M or higher concentrations of carbamylcholine was reduced to 20-30%. These results indicate that the phosphorylation of m2 receptors by GRK2 facilitates their sequestration. These results are in contrast with the absence of a correlation between sequestration and the phosphorylation of beta-adrenergic receptors by the GRK2 and suggests that the consequences of phosphorylation by GRK2 are different for different receptors.

Animals↗
PubMed1994

Activation of a GTP-binding protein and a GTP-binding-protein-coupled receptor kinase (beta-adrenergic-receptor kinase-1) by a muscarinic receptor m2 mutant lacking phosphorylation sites.

A mutant of the human muscarinic acetylcholine receptor m2 subtype (m2 receptor), lacking a large part of the third intracellular loop, was expressed and purified using the baculovirus/insect cell culture system. The mutant was not phosphorylated by beta-adrenergic-receptor kinase, as expected from the previous assignment of phosphorylation sites to the central part of the third intracellular loop. However, the m2 receptor mutant was capable of stimulating beta-adrenergic-receptor-kinase-1-mediated phosphorylation of a glutathione S-transferase fusion protein containing the m2 phosphorylation sites in an agonist-dependent manner. Both mutant and wild-type m2 receptors reconstituted with the guanine-nucleotide-binding regulatory proteins (G protein), G(o) and G(i)2, displayed guanine-nucleotide-sensitive high-affinity agonist binding, as assessed by displacement of [3H]quinuclidinyl-benzilate binding with carbamoylcholine, and both stimulated guanosine 5'-3-O-[35S]thiotriphosphate ([35S]GTP[S]) binding in the presence of carbamoylcholine and GDP. The Ki values of carbamoylcholine effects on [3H]quinuclidinyl-benzilate binding were indistinguishable for the mutant and wild-type m2 receptors. Moreover, the phosphorylation of the wild-type m2 receptor by beta-adrenergic-receptor kinase-1 did not affect m2 interaction with G proteins as assessed by the binding of [3H]quinuclidinyl benzilate or [35S]GTP[S]. These results indicate that (a) the m2 receptor serves both as an activator and as a substrate of beta-adrenergic-receptor kinase, and (b) a large part of the third intracellular loop of the m2 receptor does not contribute to interaction with G proteins and its phosphorylation by beta-adrenergic-receptor kinase does not uncouple the receptor and G proteins in reconstituted lipid vesicles.

Animals↗
PubMed1994

Necrotising fasciitis due to group A streptococci in western Norway: incidence and clinical features.

During November, 1992, to May, 1994, 13 patients were treated at Haukeland University Hospital, Norway, for necrotising fasciitis due to group A beta-haemolytic streptococci. 3 patients died, 1 before admission. Mucoid group A streptococci were isolated from affected tissue (12 patients) and/or blood (5). Strains from 11 patients were serotype M-1 (5 patients), M-3 (2), M-6 (2), M-28 (1), and M-untypable (T-1, opacity factor negative) (1). For the 12 patients admitted alive, the following preoperative events were recorded: 8 had clinical signs of shock with systolic blood pressure of 90 mm Hg or less, 8 had impaired renal function, and 7 had biochemical markers of disseminated intravascular coagulation. At least 6 patients fulfilled the criteria for streptococcal toxic shock syndrome. Preoperative C-reactive protein was substantially raised ( > 200 mg/L) in 10 patients. The 12 patients were given high doses of antibiotics and were operated on with aggressive debridement of necrotic skin and fascia, 7 of them within 24 h of admission. The increasing incidence of necrotising fasciitis in western Norway reflects the resurgence of invasive group A streptococcal infections documented in Scandinavia since 1987. The high case-fatality rate can be reduced by early diagnosis and aggressive surgery combined with adequate antibiotic therapy.

Adult↗
PubMed1994

Solubilization of muscarinic receptor subtypes from baculovirus infected Sf9 insect cells.

Five different subtypes (human m1, m2, m5 and rat m3, m4) of muscarinic acetylcholine receptors (mAChR) were produced in insect Sf9 cells by infection with recombinant baculoviruses. N-[3H]methylscopolamine ([3H]NMS) has a similar affinity to each of these mAChR subtypes in cell membranes, while pirenzepine, 11-((2-[(diethylamino)methyl]-1-piperidinyl)acetyl)-5,11-dihydro-6H-pyri do- (2,3-b)(1,4)benzo-diazepin-6-on (AF-DX 116) and (+/-)-p-fluoro-hexahydrosiladifenidol (p-F-HHSiD) have a higher affinity for m1, m2 and m3, respectively, than for the other subtypes, indicating the maintenance of subtype specificity of mAChR in this system. Digitonin (1%, w/w) with sodium cholate (0.1%, w/w) solubilized 51% of m1, 36% of m2, 3% of m3, 28% of m4 and 17% of m5 mAChR from these cell membranes with retention of the [3H]NMS binding activity. Optimization of cholate concentrations resulted in solubilization of up to 50-60% for m1, m2 and m4, but up to 25% for m5 and 7% for m3. Optimal concentrations of cholate differed from one subtype to another. Sucrose monolaurate solubilized 21-43% of m1, m2 and m4, but only up to 12% for m5 and 2% for m3. 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate (CHAPS) was practically ineffective in mAChR solubilization from Sf9 cell membranes for all subtypes investigated. Solubilization with digitonin and cholate had little influence on [3H]NMS affinity for m2 and m4, but decreased m1 and m5 affinity by 10-fold and that of m3 by more than 50-fold. These results indicate that the solubility and stability of mAChR in detergents differ among the subtypes, in spite of their structural similarities. These differences should be taken into account when comparing the five subtypes, particularly when determining the proportion of each subtype in a given tissue by precipitating the solubilized mAChR with subtype-specific antibodies.

Animals↗
PubMed1994

Role of cytoplasmic tail phosphorylation sites of platelet-activating factor receptor in agonist-induced desensitization.

The platelet-activating factor (PAF) receptor couples with multiple signaling pathways such as activation of phospholipase C, phospholipase A2, and mitogen-activated protein kinase and the inhibition of adenylate cyclase. The PAF-induced signals are attenuated by repetitive or long standing applications of the agonist (homologous desensitization). To investigate mechanisms underlying the agonist-induced desensitization, we constructed mutant forms of the cloned guinea pig PAF receptor and stably expressed them in Chinese hamster ovary cells. The cells expressing the wild type receptor transiently activated phospholipase C in response to PAF. Intracellular inositol 1,4,5-trisphosphate level and intracellular Ca2+ concentration reached the maximal levels within 20 s and returned to the basal levels in several minutes, even in the continuous presence of the ligand. In contrast, a truncated PAF receptor lacking the carboxyl-terminal cytoplasmic tail induced sustained elevations of inositol 1,4,5-trisphosphate and intracellular Ca2+ concentrations. Similar findings were noted in another mutant, in which the Ser/Thr residues in the carboxyl-terminal tail were substituted with Ala. Both mutant PAF receptors more potently activated the other signals (mitogen-activated protein kinase kinase, arachidonate release, and inhibition of adenylate cyclase) than did the wild type receptor. Thus, while the carboxyl-terminal cytoplasmic tail of the PAF receptor is not required for the forward activation of multiple signals, it does have a critical role for signal attenuation induced by the agonist through phosphate accepters. We also noted that the synthetic peptide of the PAF receptor carboxyl-terminal tail was strongly phosphorylated by the recombinant beta-adrenergic receptor kinase 1, suggesting that it or its relatives might be involved in PAF receptor phosphorylation and homologous desensitization.

Amino Acid Sequence↗
PubMed1994

Synergistic activation of a G protein-coupled receptor kinase by G protein beta gamma subunits and mastoparan or related peptides.

Muscarinic acetylcholine receptors (mAChR, m2 subtype) are phosphorylated in an agonist-dependent manner by a G protein-coupled receptor kinase (GR kinase) at sites located in the central part of mAChR. The GR kinase phosphorylated a glutathione S-transferase fusion protein containing the m2 phosphorylation sites (13-GST). Phosphorylation of 13-GST was markedly stimulated by mastoparan: the Km for 13-GST decreased from 7.3 to 0.17 microM in the presence of 100 microM mastroparan and the Vmax increased 23-fold. beta gamma Subunits of G proteins synergistically stimulated the phosphorylation of 13-GST in the presence of 1-10 microM mastoparan by increasing the affinity of mastoparan for the GR kinase. The phosphorylation of mAChR by the GR kinase was also synergistically stimulated by 1-10 microM mastoparan in the presence of beta gamma subunits, but was inhibited by 100 microM mastoparan. Similar stimulatory and inhibitory effects on the phosphorylation of 13-GST and mAChR were observed using synthetic peptides of 15-20 amino acid residues corresponding to sequences of intracellular segments adjacent to the transmembrane segments of mAChR. These results are consistent with and support the idea that the GR kinase is synergistically activated by both G protein beta gamma subunits and agonist-bound receptors.

Amino Acid Sequence↗
PubMed1994

Location of agonist-dependent-phosphorylation sites in the third intracellular loop of muscarinic acetylcholine receptors (m2 subtype).

Muscarinic acetylcholine receptors (mAChR, human m2 subtype) expressed in Sf9 (Spodoptera frugiperda) cells using the baculovirus system were purified and subjected to phosphorylation by a mAChR kinase, which was partially purified from porcine cerebrum. Two bands with apparent molecular masses of 59 kDa and 39 kDa as determined by SDS/PAGE were found to be phosphorylated in an agonist-dependent manner. Both bands were labeled by the irreversible muscarinic ligand [3H]propylbenzilylcholine mustard. Molecular masses of the [32P]phosphorylated or [3H]propylbenzilylcholine-mustard-labeled bands decreased following treatment with N-glycanase. The 59-kDa and 39-kDa bands were converted to 52-kDa and 32-kDa bands, respectively, indicating that both the 59-kDa and 39-kDa bands contain the amino-terminal region where glycosylation sites are present. The ratio of incorporated [32P]phosphate and bound [3H]propylbenzilylcholine mustard was essentially the same for the 59-kDa and 39-kDa bands, indicating that all the phosphorylation sites reside in the sequence of 39 kDa from the amino-terminal region. The amounts of incorporated [32P]phosphate were estimated to be 10-11/receptor, with 7-8 serine and 3-4 threonine, but no phosphorylated tyrosine residues. Further treatment of [32P]phosphorylated or [3H]propylbenzilylcholine-mustard-labeled receptors with V8 protease indicated that the phosphorylation sites were not present in 30-kDa amino-terminal segment. These results indicate that the phosphorylation sites are localized in the range 30-39 kDa from the amino terminus, which consists of primarily the central part of the third intracellular loop. Consistent with this conclusion, a fusion protein containing glutathione S-transferase linked to a peptide corresponding to residues 227-324 of the central part of the third intracellular loop was found to be phosphorylated by the mAChR kinase in a heparin-sensitive manner.

Amino Acid Sequence↗
PubMed1994

G protein-mediated inhibition of phosphoinositide metabolism evoked by metabotropic glutamate receptors in frog oocytes.

1. Metabotropic glutamate receptor subtype 1 (mGluR1), when expressed in Xenopus oocytes, activates phosphoinositide-specific phospholipase C (PLC) in a G protein-dependent manner. This reaction results in the activation of chloride channels in the oocytes, and can be monitored electrophysiologically. We expressed different G protein alpha-subunits together with mGluR1 in oocytes, and examined the effects of these G protein subunits on the PLC-mediated reaction. 2. The expression of the alpha-subunit of GL2, a bovine version of G11, which is a member of the Gq subgroup, potentiated the mGluR1-evoked reaction, whereas the alpha-subunit of GL1, a bovine G14, which is also a member of the Gq subgroup, strongly suppressed it. The expression of Gs alpha also suppressed this reaction. 3. We then expressed G beta 1 gamma 2-subunits in addition to the G alpha-subunits, and examined the mGluR1-evoked reactions. Both the potentiation and suppression by GL2 alpha and GL1 alpha, respectively, were more pronounced in the presence of the G beta 1 gamma 2-subunits. In contrast, the suppression by Gs alpha was completely reversed by G beta 1 gamma 2. 4. The direct activation of G proteins by the intracellular injection of either fluoride ions or guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) causes similar PLC-mediated reactions. The expression of GL2 alpha, GL1 alpha or Gs alpha caused potentiation, suppression and no change, respectively, on the fluoride- (or GTP gamma S-) evoked reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Focal spasms in clusters, focal delayed myelination, and hypsarrhythmia: unusual variant of West syndrome.

We report a patient who began to have clusters of seizures characterized by brief elevation of the right arm at 6 months of age. An interictal electroencephalogram (EEG) at 7 months revealed hypsarrhythmia without definite asymmetry. Simultaneous EEG and video recording disclosed that these focal spasms were associated with fast wave bursts superimposed on slow waves most markedly in the left centro-midtemporal region. The patient became seizure-free after synthetic ACTH therapy. The patient is developmentally normal at 3 years 5 months, but magnetic resonance imaging studies revealed findings suggestive of delayed myelination in the left frontal region. This patient is considered to have had an unusual variant of West syndrome associated with focal delayed myelination.

Adolescent↗
PubMed1994

[Regulation of G protein-coupled receptor kinase activity].

Recent progress on the activation of G protein-coupled receptor kinases is reviewed. beta-Adrenergic receptor kinase (beta ARK) is activated by G protein beta gamma -subunits, which interact with the carboxyl terminal portion of beta ARK. Muscarinic receptor m2-subtypes are phosphorylated by beta ARK1 in the central part of the third intracellular loop (I3). Phosphorylation of I3-GST fusion protein by beta ARK1 is synergistically stimulated by the beta gamma -subunits and mastoparan or a peptide corresponding to portions adjacent to the transmembrane segments of m2-receptors or by beta gamma -subunits and the agonist-bound I3-deleted m2 variant. These results indicate that agonist-bound receptors serve as both substrates and activators of beta ARK.

Animals↗
PubMed1993

[A survey of the initial course of tuberculosis chemotherapy under compulsory hospitalization on the basis of the revised Tuberculosis Prevention Law--report of the 32nd C series of controlled trials of chemotherapy--Cooperative Study Unit of Chemotherapy of Tuberculosis of the National Sanatoria in Japan].

We studied 2247 patients with pulmonary tuberculosis who were hospitalized for the initial course of chemotherapy under the provision of the revised Tuberculosis Prevention Law issued by Japanese Ministry of Welfare. The results were as follows. 1) There were more males than females with a ratio of 2.6: 1. 2) There were two peaks in their ages, 20s and 60s. 3) The average admission periods were 5.2 +/- 2.7 months for men and 5.1 +/- 2.8 months for women. 4) The average compulsory admission periods were 6.8 +/- 2.5 months for men and 6.4 +/- 2.3 months for women, so that the actual admission periods were shorter in the majority of the patients. 5) The sputum cultures were converted negative in three months in about 80 percent of the patients who were smear and/or culture positive on admission. 6) The appearance rate of INH-resistant and RFP-resistant strains were 2% and 1.4% respectively. 7) Most of the death from tuberculosis was observed in the early stages of admission. 8) With regards to the cost, there seemed to be no difference whether treated under the new or the old provisions. 9) The newly approved extension of the admission periods for those who had complications such as diabetes mellitus or pneumoconiosis and those who had INH and/or RFP positive bacilli seemed to be appropriate.

Adult↗
PubMed1992

Effects of magnesium ion on the interaction of atrial muscarinic acetylcholine receptors and GTP-binding regulatory proteins.

Muscarinic acetylcholine receptors (mAChR) purified from porcine atrium were reconstituted into lipid vesicles with GTP-binding regulatory proteins (G proteins, Gi, Go, or Gn) purified from porcine cerebrum. Apparent affinities of the reconstituted mAChR and G proteins for carbachol and GDP, respectively, were estimated from the effects of these ligands on the binding of [3H]-L-quinuclidinyl benzilate ([3H]QNB) to mAChR and [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) to G proteins in the presence of different concentrations of MgCl2. A total of 30-35% of reconstituted mAChRs exhibited low affinity for carbamylcholine, irrespective of the presence or absence of guanine nucleotides, and the remainder of the mAChRs showed high affinities for carbamylcholine in the absence of GTP or GDP and a low affinity in their presence. The affinity for carbamylcholine in the absence of guanine nucleotides, but not in their presence, increased with increases in MgCl2 concentration. Apparent Kd's for carbamylcholine were estimated to be approximately 100 microM in the presence of guanine nucleotides, 1.5 microM in the absence of guanine nucleotide and Mg2+ (< 0.1 microM), and 0.1 microM in the absence of guanine nucleotide and the presence of MgCl2 (10 mM). These results indicate that mAChRs may assume at least three different conformations that are characterized by different affinities for agonists. Furthermore, the data suggest that MgCl2 is not necessary for the formation of the mAChR-G protein complex, but can induce a conformational change in the complex. On the other hand, the presence of MgCl2 was necessary for carbamylcholine to influence the binding of guanine nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Silicone breast implants and collagen diseases].

Connective tissue disease has been reported to occur following implantation of silicone gel-filled prostheses to augment the breast. In this case report and review of the literature, two patients are described in whom connective tissue disease developed within one and three years respectively after cosmetic surgery. One developed dermatomyositis with lung fibrosis, and the other developed cutaneous lupus and a Sjögren-like syndrome. Both suffered serious complications due to vasculitis. Although evidence of a causal relationship between the implantation and the development of connective tissue disease is circumstantial, removal of the silicone prosthesis has been reported to result in subsequent remission.

Adult↗