Redes de señalización en la producción de biopelículas en bacterias: quorum sensing, di-GMPc y óxido nítrico / Networks involving quorum sensing, cyclic-di-GMP and nitric oxide on biofilm production in bacteria

Las bacterias forman biopelículas de manera ubicua, y esta característica les otorga una flexibilidad que es resultado, en parte, de una matriz compleja construida según las exigencias de las condiciones ambientales. Aunque los estadios de la formación de las biopelículas bacterianas se conocen con detalle, para entender con profundidad la formación de las biopelículas es deseable un conocimiento mayor de los mecanismos de señalización. Las bacterias detectan cambios en la densidad de población por regulación del quórum y condiciones específicas, empleando señales como el di-GMPc y el óxido nítrico. La importancia del conocimiento de estas vías de señalización radica en que controlan una variedad de funciones, como la formación de biopelículas y la movilidad, y proporcionan a las bacterias beneficios en la colonización del hospedador, la defensa contra competidores y los cambios adversos del entorno. Por la trascendencia que revisten estos aspectos, revisamos aquí las redes de regulación y la conexión de la señalización entre quorum sensing, di-GMPc y óxido nítrico

Bacterial biofilms are ubiquitous in nature, and their flexibility is derived in part from a complex extracellular matrix that can be made-to-order to cope with environmental demand. Although common developmental stages leading to biofilm formation have been described, an in-depth knowledge of genetic and signaling is required to understand biofilm formation. Bacteria detect changes in population density by quorum sensing and particular environmental conditions, using signals such as cyclic di-GMP or nitric oxide. The significance of understanding these signaling pathways lies in that they control a broad variety of functions such as biofilm formation, and motility, providing benefits to bacteria as regards host colonization, defense against competitors, and adaptation to changing environments. Due to the importance of these features, we here review the signaling network and regulatory connections among quorum sensing, c-di-GMP and nitric oxide involving biofilm formation

Identification of mechanisms involved in the relaxation of rabbit cavernous smooth muscle by a new nitric oxide donor ruthenium compound

PURPOSE: The aim of this study was to evaluate the relaxation in vitro of cavernous smooth muscle induced by a new NO donor of the complex nitrosil-ruthenium, named trans-[Ru(NH3)4(caffeine)(NO)]C13 (Rut-Caf) and sodium nitroprusside (SNP). MATERIALS AND METHODS: The tissues, immersed in isolated bath systems, were pre-contracted with phenilephrine (PE) (1 µM) and then concentration-response curves (10-12 - 10-4 M) were obtained. To clarify the mechanism of action involved, it was added to the baths ODQ (10 µM, 30 µM), oxyhemoglobin (10 µM), L-cysteine (100 µM), hydroxicobalamine (100 µM), glibenclamide, iberotoxin and apamine. Tissue samples were frozen in liquid nitrogen to measure the amount of cGMP and cAMP produced. RESULTS: The substances provoked significant relaxation of the cavernous smooth muscle. Both Rut-Caf and SNP determined dose-dependent relaxation with similar potency (pEC50) and maximum effect (Emax). The substances showed activity through activation of the soluble guanylyl cyclase (sGC), because the relaxations were inhibited by ODQ. Oxyhemoglobin significantly diminished the relaxation effect of the substances. L-cysteine failed to modify the relaxations caused by the agents. Hydroxicobalamine significantly diminished the relaxation effect of Rut-Caf. Glibenclamide significantly increased the efficacy of Rut-Caf (pEC50 4.09 x 7.09). There were no alterations of potency or maximum effect of the substances with the addition of the other ion channel blockers. Rut-Caf induced production of significant amounts of cGMP and cAMP during the relaxation process. CONCLUSIONS: In conclusion, Rut-Caf causes relaxation of smooth muscle of corpus cavernosum by means of activation of sGC with intracellular production of cGMP and cAMP; and also by release of NO in the intracellular environment. Rut-Caf releases the NO free radical and it does not act directly on the potassium ion channels.

Prostaglandin E2 stimulates angiogenesis by activating the nitric oxide/cGMP pathway in human umbilical vein endothelial cells

Prostaglandin E2(PGE2), a major product of cyclooxygenase, has been implicated in modulating angiogenesis, vascular function, and inflammatory processes, but the underlying mechanism is not clearly elucidated. We here investigated the molecular mechanism by which PGE 2 regulates angiogenesis. Treatment of human umbilical vein endothelial cells (HUVEC) with PGE 2 increased angiogenesis. PGE 2 increased phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), eNOS activity, and nitric oxide (NO) production by the activation of cAMP-dependent protein kinase (PKA) and phosphatidylinositol 3-kinase (PI3K). Dibutyryl cAMP (DB-cAMP) mimicked the role of PGE 2 in angiogenesis and the signaling pathway, suggesting that cAMP is a down-stream mediator of PGE 2. Furthermore, PGE 2 increased endothelial cell sprouting from normal murine aortic segments, but not from eNOS-deficient ones, on Matrigel. The angiogenic effects of PGE 2 were inhibited by the inhibitors of PKA, PI3K, eNOS, and soluble guanylate cyclase, but not by phospholipase C inhibitor. These results clearly show that PGE 2 increased angiogenesis by activating the NO/cGMP signaling pathway through PKA/PI3K/Akt-dependent increase in eNOS activity.

Existence of heme oxygenase-carbon monoxide-cyclic guanosine monophosphate pathway in human trabecular meshwork cells in vitro / 华中科技大学学报（医学）（英德文版）

To confirm the existence of heme oxygenase (HO)- carbon monoxide (CO)- cyclic guanosine monophosphate (cGMP) pathway in the cultured human trabecular meshwork cells (HT-MCs) in vitro, and to evaluate the inductive role of hemin on this pathway, HTMCs of the third to fourth generation were cultured in vitro. Reverse transcripase-polymerase chain reaction (RT-PCR) was employed for detection of HO-1 and HO-2 mRNA. Immunohistochemical staining was used to detect HO-1 and HO-2 proteins. Hemin was added into the culture solution. The HO-1 mRNA levels were quantified by RT-PCR. The relative amount of carbon monoxide released into the media was measured with the quantifying carbon monoxide hemoglobin (HbCO) by spectrophotometry. Radioimmunoassay was used to determine changes of cGMP in HTMCs. The results showed that cultured cells had the specific characteristics of HTMCs. Both HO-1 and HO-2 genes were expressed in HTMCs, as well as HO-1 and HO-2 proteins in HTMCs. Hemin induced HO-1 mRNA, HbCO and cGMP in a dose-dependent manner. In conclusion, HO-CO-cGMP pathway exists in the cultured HTMCs and can be induced by hemin. Pharmacological stimulation of HO-CO-cGMP pathway may constitute a novel therapeutic approach to rescuing glaucoma.

Papel de las PDE Ic en la contracción del músculo liso de las vías aéreas: futuras drogas broncorelajadoras / Peiper of the PDE Ic in the contraction airway smooth muscle bronchorelaxing drugs future

En el músculo liso traqueal, los antagonistas muscarínicos (atropina) incrementan simultáneamente los niveles basales de los nucleóticos cíclicos (AMPc, GMPc), dependiendo del tiempo y dosis con máximo a 15 min y pEC50 7.4 mas o menos 0.2. El IBMX (10 µM), inhibidor no selectivo de PDEs, induce una respuesta similar. Sin embargo, la atropina potencial los incrementos del AMPc inducidos por 10 µM Rolipram (inhibidor PDE-IV) y los del GMPc producidos por µM Zaprinast (inhibidor PDE-V), sugiriendo la inhibición de una PDE que hidrolice ambos nucleótidos. La Vinpocetina (20 µM), inhibidor de PDE-Ic no dependiente de Calmodulina, produjo una respuesta semejante al antagonista muscarínic. Además, la atropia inhibió la PDE-Ic de las membranas celulares y no afectó la PDE-I cistosólca. Los antagonistas muscarínicos actúan como "agonistas inversos" sobre los m2/m3 AChR del sarcolema, iniciando una novedosa cascada que inhibe la PDE-Ic, provocando el incremento simultáneo del AMPc y GMPc en este tejido

Partial characterization of an ANF/urodilatin-like substance released from perfused rabbit kidney under hypoxia

An ANF-like material was detected by radioimmunoassay in the isolated perfused rabbit kidney. The production of ANF-like material after 90 min of perfusion under hypoxia was 3000 pg/ml vs 500 pg/ml under normoxia or control conditions. This material is partially inactivated by heat treatment at 100 degrees C for 5 min and is absorbed on a SEP-PAK column (C18, Waters) but, unlike ANF, cannot be recovered from the column. On Sephadex G25 chromatography, elution in water yielded two active fractions, one corresponding to the solvent front and the second obtained after one column volume. Four fractions with biological activity were eluted with water from Sephacryl 200. Several fractions were tested on rabbit aorta preconstricted with 1 microM phenylephrine, without removal of endothelial cells. Treatment of T84 cells in culture by the crude material promoted a dose-related increase (1:2, 1:5, 1:10) of the generation of cyclic GMP. In contrast to our material, ANF (atriopeptin III, 1 microM-10 fM) failed to activate guanylate cyclase in T84 cells, while the heat-stable E. coli enterotoxin (STa) significantly increased cyclic GMP levels at the dose of 5 microM. We propose that a new ANF/urodilatin/ST-like material was generated by the hypoxic kidney under perfusion, which we name FNS (Factor Natriureticus Similis)