Amelioration of Cold Injury-Induced Cortical Brain Edema Formation by Selective Endothelin ETB Receptor Antagonists in Mice

Brain edema is a potentially fatal pathological condition that often occurs in stroke and head trauma. Following brain insults, endothelins (ETs) are increased and promote several pathophysiological responses. This study examined the effects of ET_B antagonists on brain edema formation and disruption of the blood-brain barrier in a mouse cold injury model (Five- to six-week-old male ddY mice). Cold injury increased the water content of the injured cerebrum, and promoted extravasation of both Evans blue and endogenous albumin. In the injury area, expression of prepro-ET-1 mRNA and ET-1 peptide increased. Intracerebroventricular (ICV) administration of BQ788 (ET_B antagonist), IRL-2500 (ET_B antagonist), or {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317 (ET_A antagonist) prior to cold injury significantly attenuated the increase in brain water content. Bolus administration of BQ788, IRL-2500, or {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317 also inhibited the cold injury-induced extravasation of Evans blue and albumin. Repeated administration of BQ788 and IRL-2500 beginning at 24 h after cold injury attenuated both the increase in brain water content and extravasation of markers. In contrast, {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317 had no effect on edema formation when administrated after cold injury. Cold injury stimulated induction of glial fibrillary acidic protein-positive reactive astrocytes in the injured cerebrum. Induction of reactive astrocytes after cold injury was attenuated by ICV administration of BQ788 or IRL-2500. These results suggest that ET_B receptor antagonists may be an effective approach to ameliorate brain edema formation following brain insults.     

Phosphorylation of the amino-terminal region of X11L regulates its interaction with APP

X11-like (X11L) is neuronal adaptor protein that interacts with the amyloid β-protein precursor (APP) and regulates its metabolism. The phosphotyrosine interaction/binding (PI/PTB) domain of X11L interacts with the cytoplasmic region of APP695. We found that X11L–APP interaction is enhanced in osmotically stressed cells and X11L modification is required for the enhancement. Amino acids 221–250 (X11L^221–250) are required for the enhanced association with APP in osmotically stressed cells; this motif is 118 amino acids closer to the amino-terminal end of the protein than the PI/PTB domain (amino acids 368–555). We identified two phosphorylatable seryl residues, Ser236 and Ser238, in X11L^221–250 and alanyl substitution of either seryl residue diminished the enhanced association with APP. In brain Ser238 was found to be phosphorylated and phosphorylation of X11L was required for the interaction of X11L and APP. Both seryl residues in X11L^221–250 are conserved in neuronal X11, but not in X11L2, a non-neuronal X11 family member that did not exhibit enhanced APP association in osmotically stressed cells. These findings indicate that the region of X11L that regulates association with APP is located outside of, and amino-terminal to, the PI/PTB domain. Modification of this regulatory region may alter the conformation of the PI/PTB domain to modulate APP binding.     

Participation of prostaglandin E receptor EP4 subtype in duodenal bicarbonate secretion in rats

We examined, by using a specific PGE receptor subtype EP4 agonist and antagonist, the involvement of EP4 receptors in duodenal HCO(3)(-) secretion induced by PGE(2) and mucosal acidification in rats. Mucosal acidification was achieved by exposing a duodenal loop to 10 mM HCl for 10 min, and various EP agonists were given intravenously 10 min before the acidification. Secretion of HCO(3)(-) was dose-dependently stimulated by AE1-329 (EP4 agonist), the maximal response being equivalent to that induced by sulprostone (EP1/EP3 agonist) or PGE(2). The stimulatory action of AE1-329 and PGE(2) but not sulprostone was attenuated by AE3-208, a specific EP4 antagonist. This antagonist also significantly mitigated the acid-induced HCO(3)(-) secretion. Coadministration of sulprostone and AE1-329 caused a greater secretory response than either agent alone. IBMX potentiated the stimulatory action of both sulprostone and AE1-329, whereas verapamil mitigated the effect of sulprostone but not AE1-329. Chemical ablation of capsaicin-sensitive afferent neurons did not affect the response to any of the EP agonists used. We conclude that EP4 receptors are involved in the duodenal HCO(3)(-) response induced by PGE(2) or acidification in addition to EP3 receptors. The process by which HCO(3)(-) is secreted through these receptors differs regarding second-messenger coupling. Stimulation through EP4 receptors is mediated by cAMP, whereas that through EP3 receptors is regulated by both cAMP and Ca(2+); yet there is cooperation between the actions mediated by these two receptors. The neuronal reflex pathway is not involved in stimulatory actions of these prostanoids.     

Activation of glucuronidation through reduction of a disulfide bond in rat UDP-glucuronosyltransferase 1A6

UDP-glucuronosyltransferase- (UGT-) dependent glucuronidation is an important detoxification process for many endogenous and exogenous compounds in mammals. Treatment of rat hepatic microsomes with the reducing reagent dithiothreitol (DTT) resulted in a significant increase in p-nitrophenol (p-NP) glucuronidation in a time- and concentration-dependent manner. The DTT-dependent activation of glucuronidation was specific for planar phenols but not for bilirubin or testosterone without membrane perturbation of the microsomes. p-NP glucuronidation in Gunn rat hepatic microsomes lacking UGT1 isozymes was not affected by DTT, indicating that UGT1A6 in the microsomes is mainly involved in the activation. The DTT-dependent activation was inhibited by 1,6-bis(maleimido)hexane (BMH) but not by N-ethylmaleimide, indicating that cross-linking between cysteine residues in UGT1A6 is responsible for the activation. Immunoblot analysis of rat hepatic microsomes on nonreducing SDS-PAGE gels revealed that most of the UGT1A6 migrated as a monomer, suggesting that DTT could affect an intramolecular disulfide bond in the UGT1A6 that may be responsible for the activation. To identify which of the ten cysteines in UGT1A6 are involved in the disulfide bond, rat UGT1A6 wild type and a set of mutants, each with a cysteine to serine substitution, were constructed and expressed in COS cells. Treatment of COS microsomes with DTT had no effect on the activity of the wild type but BMH showed significant inhibition, suggesting that UGT1A6 expressed in COS cells may be in the reduced and activated state. Replacement of either Cys 121 or Cys 125 with serine showed insensitivity to the BMH-dependent inhibition. These results demonstrate that both Cys 121 and Cys 125 are responsible for the activation of the activity through the disulfide bond in rat UGT1A6.     

Is the Fatty Acid Composition of Phospholipids Important for the Function of the Circadian Clock in Neurospora crassa?

Effects of pheriylmethanol (PM), 2-phenylethanol (PE) and 3-phenyl-1-propanol(PP) on the conidiation rhythm and on the fatty acid compositionof phospholipids were examined in Neurospora crassa. The periodfor the conidiation rhythm was shortened in proportion to theconcentration used of PE of more than 1 mM. PM at 10 mM andPP at 3 mM, however, did not cause a decrease in the lengthof the period. PE did not affect the temperature compensationof the length of the period or the amplitude of the phase shiftby light. The ratio of linolenic acid to Hnoleic acid decreased in proportionto the concentrations of PE, PM, and PP in all the phospholipidsexamined. The proportion of phosphatidic acid+diphosphatidylglycerolto the total phospholipids also was decreased by these compounds.Period shortening by PE can not be explained by the change inthe phospholipid fatty acid composition. (Received April 18, 1983; Accepted June 22, 1983)     

The ret oncogene can induce melanogenesis and melanocyte development in Wv/Wv mice.

We recently reported the establishment of transgenic mouse lines carrying the mouse metallothionein/ret fusion gene in which severe melanosis and melanocytic tumors developed. In the present study, we demonstrate that a significant number of pigmented hairs developed in Wv/Wv mice crossed to one of the transgenic mouse lines. The pigmented hair of Wv/Wv mice carrying the ret oncogene did not lose color during aging and reappeared after shaving, indicating that the melanocytes in the hair follicle function. The melanocytic tumors also developed in these mice, although the incidence was lower than that in the wild transgenic mice. Furthermore, the neutral tube culture of mouse embryos indicated that neural crest cells of the transgenic mice gave rise to a cell population that autonomously produced melanin even in the absence of melanocyte stimulating hormone. These results strongly suggested that the introduced ret oncogene could compensate for the defect of c-kit in Wv mice during both embryogenesis and postnatal life and induce a high level of melanin synthesis in the process of melanocyte development.     

The activation of coagulation factor X. Identity of cleavage sites in the alternative activation pathways and characterization of the COOH-terminal peptide.

Bovine Factor X can be activated by two alternative pathways. The first, favored at high concentrations of the complex of tissue factor and Factor VII, is initiated by the action of Factor VII on Factor X to cleave an activation peptide from the NH2 terminus of the heavy chain, to produce alpha-Xa. This is then converted autocatalytically to another form of Factor Xa, beta-Xa, by the loss of a 17-residue glycopeptide from the COOH terminus of the heavy chain, in a lipid-dependent reaction. The alternative pathway, favored at lower activator concentrations, is initiated by the action of Factor Xa on Factor X, in the presence of lipid, to release the same COOH-terminal peptide as is produced in the conversion of alpha-Xa to beta-Xa. The intermediate produced by the loss of this peptide from Factor X,I1, can be activated directly to beta-Xa by the tissue factor-Factor VII complex, with the loss of the same NH2-terminal peptide as is produced in the conversion of Factor X to alpha-Xa. The autocatalytic activation of Factor X by Factor Xa described previously occurs to a marked extent only at very low activator concentrations, and has been shown to proceed largely by the loss of the normal NH2-terminal peptide from the heavy chain of I1-Initial experiments show that neither peptide affects the rate of coagulation by either the extrinsic or intrinsic pathways. The amino acid sequences have been determined on both sides of the peptide cleavages, and it has been shown that the cleavage sites are the same, regardless of the pathway of activation. The amino acid sequence and carbohydrate composition of the COOH-terminal peptide have been determined. The carbohydrate moiety is attached via an O-glycosidic linkage at a threonine residue, and contains galactosamine but no glucosamine.     

Rotenoids and flavonoids with anti-invasion of HT1080, anti-proliferation of U937, and differentiation-inducing activity in HL-60 from Erycibe expansa

Principal rotenoids (deguelin, tephrosin, rotenone, and 12a-hydroxyrotenone) (3-30microM) isolated from the stems of Erycibe expansa significantly inhibited invasion of human fibrosarcoma HT1080 cells through Matrigel-coated filters and release of proMMPs-2 and 9. In addition, deguelin and tephrosin showed differentiation-inducing activity in human promyelocytic leukemia HL-60 cells. Furthermore, effects of various constituents isolated from the ethyl acetate-soluble fraction on proliferation of human leukemia U937 cells were examined. As a result, most of isoflavones and several flavans as well as rotenoids showed moderate or substantial anti-proliferative activities.     

Production of novel antioxidative prenyl naphthalen-ols by combinational bioconversion with dioxygenase PhnA1A2A3A4 and prenyltransferase NphB or SCO7190

We performed combinational bioconversion of substituted naphthalenes with PhnA1A2A3A4 (an aromatic dihydroxylating dioxygenase from marine bacterium Cycloclasticus sp. strain A5) and prenyltransferase NphB (geranyltransferase from Streptomyces sp. strain CL190) or SCO7190 (dimethylallyltransferase from Streptomyces coelicolor A3(2)) to produce prenyl naphthalen-ols. Using 2-methylnaphthalene, 1-methoxynaphthalene, and 1-ethoxynaphthalene as the starting substrates, 10 novel prenyl naphthalen-ols were produced by combinational bioconversion. These novel prenyl naphthalen-ols each showed potent antioxidative activity against a rat brain homogenate model. 2-(2,3-Dihydroxyphenyl)-5,7-dihydroxy-chromen-4-one (2',3'-dihydroxychrysin) generated with another aromatic dihydroxylating dioxygenase and subsequent dehydrogenase was also geranylated at the C-5'-carbon by the action of NphB.