Regulation of intracellular pH by phospholipase A2 and protein kinase C upon neutrophil adhesion to solid substrata

AbstractAdhesion to solid substrata has been shown to increase intracellular pH (pH(i)) of fibroblasts and of other cells (FEBS Lett. (1988) 234, 449–450; Proc. Natl. Acad. Sci. USA (1989) 86, 4525–4529; J. Biol. Chem. (1990) 265, 1327–1332; Exp. Cell Res. (1992) 200, 211–214; FEBS Lett. (1995) 374,17–20). We have found that the inhibitors of PLA2, 4-bromophenacyl bromide and manoalide, completely blocked the increase of pH(i) and spreading of neutrophils upon adhesion to solid substrata. Inhibition of phospholipase C with neomycin or removal of extracellular Ca2+ affects neither neutrophil spreading nor their pH(i). Inhibition of PKC with H-7 or staurosporin increased pH(i). PMA, an activator of PKC, dramatically decreased pH(i) but did not impair the spreading of neutrophils. The effect of arachidonic acid, a product of PLA2 activity, on neutrophil pH(i) and spreading was similar to that of PMA. H-7, an inhibitor of PKC, partially blocked the effect of arachidonic acid (AA) on pH(i). BW755C, an inhibitor of AA metabolism by cyclooxygenase or lipoxygenase, affected neither the pH(i) nor cell spreading. We propose that the increase of pH(i) upon neutrophil adhesion is mediated by PLA2 activity, while PKC decreased pH(i). AA produced by PLA2 activates PKC, thus forming a feedback regulation of pH(i)

Regulation of intracellular pH by cell-cell adhesive interactions

AbstractAs was shown in our previous work, the intracellular pH (pHi) of cultured human fibroblasts depends on cell density. The pHi is low in single cells, higher in cells, forming small groups and maximal in a sparse monolayer. On the other hand, the pHi is low in areas of confluent monolayers. In the present work, we show that the effects of inhibitors of various pH-controlling mechanisms as well as inhibitors of key enzymes in signal transduction pathways depend on the local cell density. We have found that N-ethylmaleimide and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, known as inhibitors of V-type H+ ATPase, inhibit the elevation of pHi induced by cell-cell contact interactions; meanwhile Cd2+ ions, which inhibit H+ conductive pathway, cause an increase of pHi in a confluent monolayer. Our data revealed also that the Na+/H+ antiporter does not play an essential role in the pHi regulation by intercellular contacts.Inhibitors of phospholipase A2 (4-bromophenacyl-bromide), phospholipase C (neomycin) and protein kinase C (H-7) dramatically change the way the pHi is modulated by local cell density. It is suggested that cell-cell interactions regulate cell activities via modulation of pHi, which is under positive control from phospholipase A2 and under negative control from protein kinase C

Anti-acetylcholinesterase, antidiabetic, anti-inflammatory, antityrosinase and antixanthine oxidase activities of Moroccan propolis

Biological properties of Moroccan propolis have been scarcely studied. In the present work, the total phenols and flavonoids from 21 samples of propolis collected in different places of Morocco or 3 supplied in the market were determined, as well as the invitro capacity for inhibiting the activities of acetylcholinesterase, -glucosidase, -amylase, lipoxygenase, tyrosinase, xanthine oxidase and hyaluronidase. The results showed that samples 1 (region Fez-Boulemane, Sefrou city) (IC50=0.065, 0.006, 0.020, 0.050, 0.014mgmL(-1)) and 23 (marketed) (IC50=0.018, 0.002, 0.046, 0.037, 0.008mgmL(-1)) had the best invitro capacity for inhibiting the -amylase, -glucosidase, lipoxygenase, tyrosinase and xanthine oxidase activities, respectively. A negative correlation between IC50 values and concentration of phenols, flavones and flavanones was found. These activities corresponded to the generally higher amounts of phenols and flavonoids. In the same region, propolis samples have dissimilar phenol content and enzyme inhibitory activities

Effects of abasic sites on structural, thermodynamic and kinetic properties of quadruplex structures

Abasic sites represent the most frequent lesion in DNA. Since several events generating abasic sites concern guanines, this damage is particularly important in quadruplex forming G-rich sequences, many of which are believed to be involved in several biological roles. However, the effects of abasic sites in sequences forming quadruplexes have been poorly studied. Here, we investigated the effects of abasic site mimics on structural, thermodynamic and kinetic properties of parallel quadruplexes. Investigation concerned five oligodeoxynucleotides based on the sequence d(TGGGGGT), in which all guanines have been replaced, one at a time, by an abasic site mimic (dS). All sequences preserve their ability to form quadruplexes; however, both spectroscopic and kinetic experiments point to sequence-dependent different effects on the structural flexibility and stability. Sequences d(TSGGGGT) and d(TGGGGST) form quite stable quadruplexes; however, for the other sequences, the introduction of the dS in proximity of the 3′-end decreases the stability more considerably than the 5′-end. Noteworthy, sequence d(TGSGGGT) forms a quadruplex where dS does not hamper the stacking between the G-tetrads adjacent to it. These results strongly argue for the central role of apurinic/apyrimidinic site damages and they encourage the production of further studies to better delineate the consequences of their presence in the biological relevant regions of the genome

Caffeic acid phenethyl ester decreases acute pneumonitis after irradiation in vitro and in vivo

BACKGROUND: Lung cancer is relatively resistant to radiation treatment and radiation pneumonitis is a major obstacle to increasing the radiation dose. We previously showed that Caffeic acid phenethyl ester (CAPE) induces apoptosis and increases radiosensitivity in lung cancer. To determine whether CAPE, an antioxidant and an inhibitor of NF-kappa B, could be a useful adjuvant agent for lung cancer treatment, we examine the effects of CAPE on irradiated normal lung tissue in this study. METHODS: We compared the effects of CAPE on cytotoxicity and intracellular oxidative stress in normal lung fibroblast and a lung cancer cell line. For in vivo analysis, whole thorax radiation (single dose 10 Gy and 20 Gy) was delivered to BALB/c male mice with or without CAPE pretreatment. NF- kappaB activation and the expression levels of acute inflammatory cytokines were evaluated in mice after irradiation. RESULTS: The in vitro studies showed that CAPE cause no significant cytotoxicity in normal lung as compared to lung cancer cells. This is probably due to the differential effect on the expression of NF-kappa B between normal and malignant lung cells. The results from in vivo study showed that CAPE treatment decreased the expression of inflammatory cytokines including IL-1 alpha and beta, IL-6, TNF-alpha and TGF- beta, after irradiation. Moreover, histological and immunochemical data revealed that CAPE decreased radiation- induced interstitial pneumonitis and TGF-beta expression. CONCLUSION: This study suggests that CAPE decreases the cascade of inflammatory responses induced by thoracic irradiation without causing toxicity in normal lung tissue. This provides a rationale for combining CAPE and thoracic radiotherapy for lung cancer treatment in further clinical studies

Ceruloplasmin-derived peptide is the strongest regulator of oxidative stress and leukotriene synthesis in neutrophils

Ceruloplasmin, an acute-phase protein, can affect the activity of leukocytes through its various enzymatic activities and protein-protein interactions (with lactoferrin, myeloperoxidase, eosinophil peroxidase, serprocidins, and 5-lipoxygenase (5-LOX), among others). However, the molecular mechanisms of ceruloplasmin activity are not clearly understood. In this study, we tested the ability of two synthetic peptides, RPYLKVFNPR (883â 892) (P1) and RRPYLKVFNPRR (882â 893) (P2), corresponding to the indicated fragments of the ceruloplasmin sequence, to affect neutrophil activation. Leukotriene (LT) B4 is the primary eicosanoid product of polymorphonuclear leukocytes (PMNLs, neutrophils).We studied leukotriene synthesis in PMNLs upon interaction with Salmonella enterica serovar Typhimurium. Priming of neutrophils with phorbol 12-myristate 13-acetate (PMA) elicited the strong regulatory function of P2 peptide as a superoxide formation inducer and leukotriene synthesis inhibitor. Ceruloplasmin-derived P2 peptide appeared to be a strong inhibitor of 5-LOX product synthesis under conditions of oxidative stress.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author