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Biomedical subjects

U Kikkawa

Publications and source records attributed to U Kikkawa.

At least 127 records · Page 7Linked to original sources
PubMed1987

Monoclonal antibodies against rat brain protein kinase C and their application to immunocytochemistry in nervous tissues.

Three monoclonal antibodies were prepared against rat brain soluble protein kinase C. Two of the antibodies, CKI-97 (IgG2b subclass) and CKII-90 (IgG1 subclass), showed weak binding to native protein kinase C. The third antibody, CKI-33 (IgG2b subclass), showed no binding. However, the mixture of CKI-97, CKII-90, and CKI-33 exhibited much stronger binding activity to this protein kinase than any of the antibodies alone. Although none of these antibodies showed protein kinase C-neutralizing activity, Western blot analysis indicated that these antibodies reacted specifically with protein kinase C, presumably its subspecies, that is present predominantly in nervous tissues. Immunocytochemical studies shows that these antibodies can be used for identification of this enzyme in nervous tissues. In rat Purkinje cells, the immunoreactive material was present throughout the cytoplasm, including dendrites and axons, but was poorly represented in the cell nucleus. In cerebellum, the localization of protein kinase C appears to be very similar to that of cGMP-dependent protein kinase.

Animals↗
PubMed1986

Stereospecificity of diacylglycerol for stimulus-response coupling in platelets.

In intact platelets, a permeable diacylglycerol having a 1,2-sn- but not 2,3-sn- configuration activated protein kinase C directly. In the presence of Ca2+-ionophore this diacylglycerol caused full activation of platelet release reaction. 1,3-Isomer was inactive. Among these isomers only 1,2-sn-diacylglycerol was converted rapidly to the corresponding phosphatidic acid in both intact and broken cell preparations. Thus, the diacylglycerol which functions in stimulus-response coupling possesses a 1,2-sn-glycerol backbone, and other isomers are not involved in the signal transduction through the protein kinase C pathway.

Blood Platelets↗
PubMed1986

Two types of complementary DNAs of rat brain protein kinase C. Heterogeneity determined by alternative splicing.

Two types of complementary DNA clones for rat brain protein kinase C were isolated. These clones encode 671 and 673 amino acid sequences, which differ from each other only in the carboxyl-terminal regions of approx. 50 amino acid residues. This difference seems to result from alternative splicing. Elucidation of the sequences of these cDNA clones as well as some peptides from the purified rat brain enzyme suggests the existence of an additional species of protein kinase C in this tissue. It is attractive to imagine that the heterogeneity of protein kinase C may reflect diverse pathways of signal transduction into the cell.

Amino Acid Sequence↗
PubMed1986

Cloning of rat brain protein kinase C complementary DNA.

Four peptides derived from rat brain protein kinase C were partially sequenced. Using synthetic oligonucleotides deduced from the amino acid sequences as probes, a clone of complementary DNA (cDNA) was isolated from a cDNA library prepared from the same tissue. The nucleotide sequence of this cDNA clone revealed the primary structure of the carboxyl-terminal region as having 224 amino acids, with significant sequence homology with cyclic AMP-dependent and cyclic GMP-dependent protein kinases.

Amino Acid Sequence↗
PubMed1986

Rapid purification of protein kinase C by high performance liquid chromatography.

Protein kinase C was purified from rat brain cytosol by using a high performance liquid chromatography (HPLC), Pharmacia FPLC system. This procedure employed a column chromatography on DE-52, followed by three steps of HPLC procedures with threonine-Sepharose (prepared as described in this report), TSK gel Phenyl-5PW (Toyo Soda), and TSK gel G3000SW (Toyo Soda) columns. Starting from about 30 g of rat brain, approximately 200 micrograms of pure enzyme was obtained. The procedure was very simple and highly reproducible. The enzyme thus obtained was nearly pure by silver staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the presence of 10% (w/v) glycerol and 0.05% (w/v) Triton X-100, the enzyme could be stored at -80 degrees C for several months.

Animals↗
PubMed1986

Role of protein kinase C in calcium-mediated signal transduction.

Information from certain extracellular signals, including a group of peptide hormones and some neurotransmitters, appears to flow from the cell surface into the cell interior through two pathways, protein kinase C activation and Ca2+ mobilization, both of which become available by a single ligand-receptor interaction. Under normal conditions protein kinase C is activated by association with membrane phospholipids in the presence of 1,2-diacylglycerol. This diacylglycerol may arise in the membrane only transiently from the receptor-mediated hydrolysis of inositol phospholipids. By using a synthetic permeable diacylglycerol or tumour-promoting phorbol ester (as a substitute for active diacylglycerol) it has been shown that signal passage through this protein kinase pathway is an essential prerequisite, often synergistic to that via the Ca2+ pathway, for full physiological responses, such as transmitter release and exocytosis, to be obtained. Presumably, such a role of protein kinase C may be extrapolated to the activation of many other cellular processes, including membrane conductance, gene expression and some metabolic reactions, as well as to the modulation of other receptor-mediated signal pathways. Some morphological findings with monoclonal antibodies raised against protein kinase C are presented.

Animals↗
PubMed1986

Rapid assay of binding of tumor-promoting phorbol esters to protein kinase C1.

Protein kinase C is generally accepted to be a receptor protein of tumor-promoting phorbol esters. The binding of [3H]phorbol-12,13-dibutyrate to protein kinase C can be assayed by a rapid filtration procedure using a glass-fiber filter that has been treated with a cationic polymer, polyethylenimine. The phorbol ester specifically binds to the protein kinase only in the presence of phosphatidylserine and calcium. Non-specific binding is less than 10%, at most, of the total binding. The binding is linear with respect to the concentration of protein kinase C, is dependent on the concentrations of phorbol ester and phosphatidylserine in a saturative manner, and is inhibited by diacylglycerol (an endogenous activator of the protein kinase).

Animals↗
PubMed1986

[The role of protein kinase C in cell surface signal transduction and tumor promotion].

Information from certain extracellular signals, including a group of peptide hormones, some neurotransmitters and many other biologically active substances flows from the cell surface into the cell interior by means of two mechanisms, Ca2+ mobilization and protein kinase C activation. These two signal pathways are activated by the receptor-mediated hydrolysis of phosphatidylinositol-4, 5-bisphosphate. Both protein kinase C activation and Ca2+ mobilization are essential for short-term responses as well as long-term responses. However, additional receptor occupation by growth factor is necessary to induce full activation of cell proliferation, and the signal pathway through protein kinase C appears to be separate from and synergistic to that via growth factors. Several functional proteins in many tissues have been reported to serve as substrates of protein kinase C. The phosphorylation of some of these proteins is apparently related to down-regulation or negative feedback control of cellular function activation. It is possible that protein kinase C has a dual action in the positive as well as the negative phase of regulation depending on the function of each target substrate protein. This article summarizes the possible roles of this unique protein kinase system.

Calcium↗
PubMed1985

Rat brain and liver soluble phospholipase C: resolution of two forms with different requirements for calcium.

Two forms of phospholipase C, hydrolyzing specifically inositol phospholipids, are resoluted and partially purified from rat brain as well as liver cytosol by DEAE-cellulose followed by heparin-Sepharose, Sephacryl S-400, and aminohexyl-Sepharose column chromatographies. With phosphatidylinositol as substrate, at pH 7.4 one is most active at 10(-6) M Ca2+ (Type I) whereas the other requires 10(-3) M Ca2+ (Type II). At pH 5.5 both Type I and II are active at 10(-3) M Ca2+ but essentially inactive at lower concentrations of this divalent cation. Both Type I and II hydrolyze preferentially polyphosphoinositides particularly at lower concentrations of Ca2+.

Animals↗
PubMed1984

Activation of protein kinase C by non-phorbol tumor promoter, mezerein.

Mezerein, classified as a second-stage tumor promoter, has no diacylglycerol-like structure in its molecule, but can activate protein kinase C both in vitro and in vivo. This non-phorbol diterpene competitively inhibits the specific binding of a radioactive tumor-promoting phorbol ester to the enzyme. It is suggestive that tumor-promoting phorbol esters and mezerein cause analogous changes in the membrane to activate protein kinase C, and utilize this protein kinase as a common receptive protein for tumor promotion.

Animals↗
PubMed1984

Activation of calcium-activated, phospholipid-dependent protein kinase (protein kinase C) by new classes of tumor promoters: teleocidin and debromoaplysiatoxin.

The new potent tumor promoters teleocidin and debromoaplysiatoxin , which are structurally unrelated to phorbol esters, activate Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C). The concentrations of 12-O-tetradecanoylphorbol-13-acetate, teleocidin and debromoaplysiatoxin for half-maximum activation of protein kinase C were found to be approximately 3 ng/ml, 40 ng/ml and 400 ng/ml, respectively. These three types of tumor promoters bind to protein kinase C, and appear to exhibit their pleiotropic actions through activation of this enzyme.

Alkaloids↗