Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcium tolerant rabbit cardiomyocytes, isolated by collagenase perfusion, were preincubated for varying periods of time followed by resuspension in fresh media and centrifugation into an ischaemic pellet with restricted extracellular fluid. Pellets were incubated for 240 min under oil at 37 degrees C to mimic severe ischaemia. Time to onset of ischaemic contracture (rod to square transformation) and trypan blue permeability following resuspension in 85 mOSM media were monitored at sequential times. The protocol of Series 1 was a 5-10 min pre-incubation, immediately followed by ischaemic pelleting. Preincubation with pinacidil (50 microM) protected cells from ischaemic insult, but pinacidil added only into the ischaemic pellet did not protect. Protection was abolished by the protein kinase (PKC) inhibitors chelerythrine (10 microM) added with pinacidil and calphostin C (200nM) added only into the ischaemic pellet. Neither PKC inhibitor had an effect on injury of untreated ischaemic myocytes (data not shown). Series 2-5 were preconditioning protocols with a 10 min intervention period, followed by a 30 min oxygenated drug-free period, prior to ischaemic pelleting. In series 2 pinacidil protected cells from ischaemic insult and this protection was abolished when glyburide (10 microM) was present during preincubation, or during post-incubation and ischaemia. Glyburide only partially inhibited the protection when glyburide was added only into the ischaemic pellet. In Series 3, 8-sulfophenyltheophyline (SPT)(100 microM) or adenosine deaminase during preincubation, or SPT only added into the ischaemic pellet abolished pinacidil's protection. In Series 4, cardiomyocytes were ischaemically preconditioned by pelleting for 10 min followed by 30 min reoxygenation. Glyburide during initial ischaemic blocked protection, but when added during post incubation and into the final pellet protection was not reduced. In Series 5 8-cyclopentyl-1,3,dipropylxanthine (DPCPX) (10 microM) added into the final pellet abolished protection by pinacidil, but not protection following ischaemic preconditioning. In contrast to pinacidil, ischaemically preconditioned cells maintain protection in the presence of glyburide, indicating that: (1) pinacidil does not exactly mimic preconditioning and (2) ischaemically preconditioned cells do not require opened K+ATP channels for protection, although they appear to be important during initiation of the preconditioned state. It is hypothesized that pinacidil opening of K+ channels may facilitate induction of preconditioning.
J Mol Cell Cardiol 1995 Aug
PMID:Potassium channels and preconditioning of isolated rabbit cardiomyocytes: effects of glyburide and pinacidil. 852 37

Estradiol is active in proliferation and differentiation of sex-related tissues like ovary and breast. Glandular steroid metabolism was for a long time believed to dominate the estrogenic milieu around any cell of the organism. Recent reports verified the expression of estrogen receptors in "non-target" tissues as well as the extraglandular expression of steroid metabolizing enzymes. Extraglandular steroid metabolism proved to be important in the brain, skin and in stromal cells of hormone responsive tumors. Aromatase converts testosterone into estradiol and androstenedione into estrone, thereby activating estrogen precursors. The group of 17 beta-hydroxysteroid dehydrogenases catalyzes the oxidation and/or reduction of the forementioned compounds, e.g. estradiol/estrone, thereby either activating or inactivating estradiol. Aromatase is expressed and regulated in the human THP 1 myeloid leukemia cell line after vitamin D/GMCSF-propagated differentiation. Aromatase expression is stimulated by dexamethasone, phorbolesters and granulocyte/macrophage stimulating factor (GMCSF). Exons I.2 and I.4 are expressed in PMA-stimulated cells only, exon I.3 in both PMA- and dexamethasone-stimulated cells. Vitamin D-differentiated THP 1 cells produce a net excess of estradiol in culture supernatants, if testosterone is given as aromatase substrate. In contrast, the 17 beta-hydroxysteroid dehydrogenase type 4 (17 beta-HSD 4) is abundantly expressed in unstimulated THP 1 cells and is further stimulated by glucocorticoids (2-fold). The expression is unchanged after vitamin D/GMCSF-propagated differentiation. 17 beta-HSD 4 expression is not altered by phorbolester treatment in undifferentiated cells but is abolished after vitamin D-propagated differentiation along with downregulation of beta-actin. Protein kinase C activation therefore appears to dissociate the expression of aromatase and 17 beta-HSD 4 in this differentiation stage along the monocyte/phagocyte pathway of THP 1 myeloid cells. The expression of steroid metabolizing enzymes in myeloid cells is able to create a microenvironment which is uncoupled from dominating systemic estrogens. These findings may be relevant in the autocrine, paracrine or iuxtacrine cellular crosstalk of myeloid cells in their respective states of terminal differentiation, e.g. in bone metabolism and inflammation.
J Steroid Biochem Mol Biol 1995 Dec
PMID:Expression and regulation of aromatase and 17 beta-hydroxysteroid dehydrogenase type 4 in human THP 1 leukemia cells. 854 82

The testis is a complex organ in which local control is achieved by signalling between its constituent cells. Herein we describe the responses of cultured rat testicular cells and a mouse Sertoli cell-line to stimulation by endothelin and ATP, and elsewhere we have shown that rat peritubular myoid cells possess phosphoinositidase C-coupled V1a-vasopressin receptors identical to those of liver (Howl, J. et al, 1995, Endocrinology 136: 2206-2213). 1. Peritubular myoid cells from pre-pubertal rats responded through ETA receptors with PtdIns(4,5)P2 hydrolysis [EC50 for endothelin-1 (ET-1) approximately 0.4 nM], elevation of intracellular [Ca2+], and tyrosine phosphorylation of a variety of cellular proteins. They also showed enhanced adenylate cyclase activity, with an EC50 for ET-1 of approximately 3 nM, also through ETA receptors. Pharmacological elevation of [cAMP] did not immediately change the ET-1-stimulated formation of inositol phosphates, but attenuated the response after several hours. 2. Pre-pubertal rat Sertoli cells showed no detectable responses to ET-1, but responded to FSH with elevated [cAMP] and to ATP with PtdIns(4,5)P2 hydrolysis. PtdIns(4,5)P2 hydrolysis was equally responsive to ATP and UTP, and so appears to be activated by P2U-purinergic receptors. This response was enhanced by protein kinase C inhibition and attenuated by PKC activation. 3. Despite its lack of effect on rat Sertoli cells in primary culture, ET-1 provoked PtdIns(4,5)P2 hydrolysis in the TM4 murine Sertoli cell line (EC50 approximately 0.6 nM), and this response was negatively regulated by protein kinase C activation. 5. No receptor-stimulated activation of phosphoinositase C was detected in 'germ cell' populations, but the non-specific G protein activator A1F4-provoked inositol phosphate accumulation in these cells, so demonstrating their potential to respond through yet to be identified G protein-coupled receptors with phosphoinositidase C activation. 6. Immunoblotting studies showed the presence in rat testis of phosphoinositidase C-beta 1 and the alpha-subunits(s) of the G-protein(s) Gq and/or G11. These studies show that testicular myoid and Sertoli cells use at least three G protein-coupled receptors (V1a-vasopressins, ETA-endothelin and P2U-purinergic) to signal through phosphoinositidase C activation, that ET-1 can activate multiple signalling pathways in myoid cells, and that the ET-1-stimulated phosphoinositidase C responses of myoid and Sertoli cells have different regulatory characteristics.
Mol Cell Biochem
PMID:Inositol lipid-mediated signalling in response to endothelin and ATP in the mammalian testis. 856 25

The neuronal phosphoprotein B-50/GAP-43 is associated with neuronal growth and regeneration and is involved in the calcium/CaM and G(o) signal transduction systems. In particular, B-50 interacts uniquely with CaM by binding in the absence of Ca2+. Previously identified as a major neuronal substrate for protein kinase C, which releases CaM via phosphorylation, B-50 has more recently been shown to be a substrate for endogenous ADP-ribosyltransferases. In the present study, we utilized amino acid modification with iodoacetamide and chemical stability to mercury and neutral hydroxylamine to demonstrate that the predominant site of ADP-ribosylation is Cys 3 and/or Cys 4. Chymotryptic peptide mapping further revealed a second, less labelled site of ribosylation in the C-terminal region. The results also demonstrate that, in contrast to PKC phosphorylation, ADP-ribosylation of B-50 does not mediate CaM binding. Since Cys 3 and Cys 4, by palmitoylation, are important for membrane anchoring, our findings suggest that ADP-ribosylation of B-50 may have a role in directing the intracellular localization of the protein. Hence, ribosylation of B-50 may mediate where B-50 interacts with signal transduction pathways.
Mol Cell Biochem
PMID:Evidence for multisite ADP-ribosylation of neuronal phosphoprotein B-50/GAP-43. 856 28

Many of the treatments directed towards alleviation of symptoms in Alzheimer's disease assume that target receptor systems are functionally intact. However, there is now considerable evidence that this is not the case. In human post-mortem brain tissue samples, the function of the GTP-binding protein Gs in regulating adenylyl cyclase is severely disabled, whereas that of Gi is intact. This difference in the function of the two G-protein types is also found in G-protein regulation of high- and low-affinity receptor recognition site populations. Measurement of G-protein densities using selective antibodies has indicated that the dysfunction in Gs-stimulation of cAMP production correlates with the ratio of the large to small molecular weight isoforms of the Gs alpha subunit. With respect to intracellular second messenger effects, there is a dramatic decrease in the density of brain receptor recognition sites for Ins(1,4,5)P3 that is not accompanied by a corresponding change in the Ins(1,3,4,5)P4 recognition site density. Protein kinase C function is also altered in Alzheimer's disease, a finding that may be of importance for the control of beta-amyloid production. These studies indicate that signal transduction processes are severely compromised in Alzheimer's disease. Some of these disturbances are also seen in cultured fibroblasts from Alzheimer's disease patients, indicating that they are neither restricted to areas of histopathological change, nor non-specific changes found late in the course of the disease. Cellular models to investigate the relation between amyloid production and deficits in signal transduction are also discussed.
Mol Cell Biochem
PMID:Disturbances in signal transduction mechanisms in Alzheimer's disease. 856 42

EGF has been reported to promote oocyte maturation in several species, although the mechanism of action is not yet known. The present study is designed to determine the pathway used by EGF to enhance porcine oocyte maturation. Oocytes were aspirated from 2-5 mm follicles and cultured with various treatments in Medium-199 at 37 degrees C, 100% relative humidity, and 5% CO2 for 48 hr for the maturation study and 3 hr for intracellular cAMP measurement. Although treatment with 100 IU/ml hCG stimulated both intracellular cAMP formation and oocyte maturation, 10 ng/ml EGF stimulated oocyte maturation only. Dibutyryl cAMP (dbcAMP) inhibited oocyte maturation at 10(-5), 10(-4), and 10(-3) M concentration s in the control medium. However, in the presence of 10 ng/ml EGF, dbcAMP inhibited oocyte maturation only at a concentration of 10(-3) M. Increasing concentrations of EGF (i.e., 25 and 50 ng/ml) were ineffective in overcoming the inhibitory effect of dbcAMP at 10(-3) M. In contrast, EGF reversed the decreased maturation rate caused by transforming growth factor-beta. Phorbol myristate acetate (PMA), a tumor-promoting phorbol ester, enhanced the spontaneous maturation rate; 4 alpha-phorbol dideconoate, an inactive phorbol ester, did not show this effect. PMA- and EGF-stimulated porcine oocyte maturation is reversed by calphostin-C, a PKC inhibitor. In conclusion, EGF's promotional activity on porcine oocyte maturation is independent of the cAMP pathway and probably mediated by the PKC pathway.
Mol Reprod Dev 1995 Nov
PMID:Mechanism of action of epidermal growth factor-induced porcine oocyte maturation. 857 45

The effect of incubation with the protein kinase C activator, 4 beta-phorbol 12,13-dibutyrate (beta-PDBu) on the electrophysiological responses to hypoxia and combined hypoxia and hypoglycemia was investigated in the rat hippocampal slice. Preincubation with beta-PDBu prevents adenosine-mediated inhibition of synaptic transmission under normoxic, normoglycemic conditions. beta-PDBu preincubation also reduces the adenosine-mediated hypoxia-induced depression of synaptic transmission revealing a substantial adenosine-independent hypoxia-induced depression of synaptic transmission. During combined hypoxia and hypoglycemia, slices preincubated in beta-PDBu display a significant shortening of the time of anoxic depolarization, an effect of beta-PDBu that is not mimicked by application of the adenosine antagonist cyclopentyltheophylline (8-CPT). It is concluded that the state of PKC activation may influence the electrophysiological responses to hypoxia and ischemia.
Mol Chem Neuropathol 1995 Sep
PMID:Phorbol ester alters the electrophysiological responses to hypoxia and ischemic-like conditions in the rat hippocampal slice. 858 22

Studies on physiological modulation of intercellular communication mediated by protein kinases are often complicated by the fact that cells express multiple gap junction proteins (connexins; Cx). Changes in cell coupling can be masked by simultaneous opposite regulation of the gap junction channel types expressed. We have examined the effects of activators and inhibitors of protein kinase A (PKA), PKC, and PKG on permeability and single channel conductance of gap junction channels composed of Cx45, Cx43, or Cx26 subunits. To allow direct comparison between these Cx, SKHep1 cells, which endogenously express Cx45, were stably transfected with cDNAs coding for Cx43 or Cx26. Under control conditions, the distinct types of gap junction channels could be distinguished on the basis of their permeability and single channel properties. Under various phosphorylating conditions, these channels behaved differently. Whereas agonists/antagonist of PKA did not affect permeability and conductance of all gap junction channels, variable changes were observed under PKC stimulation. Cx45 channels exhibited an additional conductance state, the detection of the smaller conductance states of Cx43 channels was favored, and Cx26 channels were less often observed. In contrast to the other kinases, agonists/antagonist of PKG affected permeability and conductance of Cx43 gap junction channels only. Taken together, these results show that distinct types of gap junction channels are differentially regulated by similar phosphorylating conditions. This differential regulation may be of physiological importance during modulation of cell-to-cell communication of more complex cell systems.
Mol Biol Cell 1995 Dec
PMID:Differential regulation of distinct types of gap junction channels by similar phosphorylating conditions. 859 Aug

Varied immunoreactive bands of protein kinase C delta (PKC delta), PKC eta, and PKC zeta were detected in crude extracts of wheat germ, lobster tail meat, and three strains of baker's yeast by analysis of Western blots. Protease-deficient and Fleischmann's Active Dry yeasts exhibited immunoreactivity of PKC delta, whereas wheat germ and Fleischmann's RapidRise yeast displayed immunoreactivities of both PKC delta and PKC zeta. Lobster tail meat showed immunoreactivities of PKC eta and PKC zeta. These positive and negative immunoreactivities reflected evolutionary conservation and divergence, respectively, of these PKC isozymes in eukaryotes.
Biochem Mol Biol Int 1995 Oct
PMID:Immunoreactivities of PKC delta, eta, zeta in baker's yeast, lobster and wheat germ. 859 81

Protein kinase C (PKC) isozymes regulate a number of cardiac functions including contractility, gene expression, and hypertrophy. There are at least six PKC isozymes in neonatal rat ventricular myocytes. We have shown previously that stimulation of cardiac myocytes in culture with norepinephrine (NE) or phorbol 12-myristate 13-acetate (PMA) results in translocation of each isozyme to distinct subcellular sites. In the present work, we demonstrated that PKC isozymes vary in their sensitivity to stimulation by acidic fibroblast growth factor (aFGF) and transforming growth factor-beta 1 (TGF-beta 1). Moreover, immunocytochemical studies indicated differences in the subcellular localization of activated isozymes following stimulation with each growth factor. These data suggest that the site of translocation and the resulting function of individual PKC isozymes are distinct for different PKC activators. Identification of the PKC isozymes that respond to aFGF and TGF-beta 1 and their subcellular localization may provide a molecular basis for the divergent cardiac functions mediated by these two growth factors.
J Mol Cell Cardiol 1995 Nov
PMID:Stimulus-dependent subcellular localization of activated protein kinase C; a study with acidic fibroblast growth factor and transforming growth factor-beta 1 in cardiac myocytes. 859 98


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