by Lai Wing Hong Kevin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 63-74). / Acknowledgments --- p.i / Abbreviations --- p.ii / Abstract --- p.1 / Chapter Chapter 1 --- General Introduction --- p.3 / Chapter 1.1 --- Advantages of Antisense Oligonucleotides Inhibition --- p.4 / Chapter 1.2 --- The Uses of Antisense Oligonucleotide in Leukemic Therapy --- p.5 / Chapter 1.3 --- Oncogenes in the Pathogenesis of Leukemia --- p.6 / Chapter 1.4 --- Apoptosis and Apoptosis-Related Genes --- p.9 / Chapter 1.5 --- Protooncogene bcl-2 --- p.10 / Chapter 1.6 --- Bcl-2 Homologues --- p.11 / Chapter 1.7 --- Regulation of Apoptosis by Other Genes --- p.13 / Chapter 1.8 --- Promyelocytic Leukemia HL-60 Cell Line --- p.15 / Chapter 1.9 --- Aim of Project --- p.16 / Chapter Chapter 2 --- Chemical Synthesis of DNA Oligonucleotides / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Materials and Methods --- p.20 / Chapter 2.3 --- Results --- p.24 / Chapter 2.4 --- Discussion --- p.26 / Chapter Chapter 3 --- The Apoptotic Effects of TPA and Ouabain on the Promyelocytic Leukemic HL-60 cell line / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Materials and methods --- p.33 / Chapter 3.3 --- Results --- p.40 / Chapter 3.4 --- Discussion --- p.44 / Chapter Chapter 4 --- Effect of Antisense Oligonucleotides on TPA-Induced Apoptosisin Leukemic HL-60 cells / Chapter 4.1 --- Introduction --- p.48 / Chapter 4.2 --- Materials and Methods --- p.49 / Chapter 4.3 --- Results --- p.52 / Chapter 4.4 --- Discussion --- p.54 / Chapter Chapter 5 --- General Discussion --- p.57 / References --- p.63

Doctor of Philosophy (Medicine) / Glutamate transporters play a role in removing extracellular excitatory neurotransmitter, L-glutamate into the cells. The rate of the uptake depends on the density of the transporters at the membrane. Some studies claimed that glutamate transporters could transit between the cytoplasm and the membrane on a time-scale of minutes. The present study examined the distribution of glutamate transporter GLAST predominantly expressed in rat cortical cultured astrocytes between the membrane and the cytoplasm by using deconvolution microscopy and then analyzing the images. The regulation of the distribution of GLAST was studied in the presence of glutamate transporter substrate (D-aspartate), purinergic receptor activators (α,β-methylene ATP, adenosine), neuroleptic drugs (clozapine, haloperidol), ammonia (hyperammonia) and Na+/K+-ATPase inhibitors (ouabain, digoxin and FCCP). It was demonstrated that the translocation of GLAST towards the plasma membrane was induced by D-aspartate, α,β-methylene ATP, adenosine, clozapine and ammonia (at 100 μM and very high concentrations of 10 mM). However, the inhibition of Na+/K+-ATPase activity had an opposite effect, resulting in redistribution of GLAST away from the membrane. It has previously been claimed that the membrane-cytoplasm trafficking of GLAST was regulated by phosphorylation catalysed by protein kinase C delta (PKC-delta). Involvement of this mechanism has, however, been put to doubt when rottlerin, a PKC-delta inhibitor, used to test the hypothesis showed to inhibit Na+/K+-ATPase-mediated uptake of Rb+, suggesting that rottlerin influenced the activity of Na+/K+-ATPase. As Na+/K+-ATPase converts ATP to energy and pumps Na+, K+ ions, thus helping to maintain normal electrochemical and ionic gradients across the cell membrane. Its inhibition also reduced D-aspartate transport and could impact on the cytoplasm-to-membrane traffic of GLAST molecules. Furthermore, rottlerin decreased the activity of Na+/K+-ATPase by acting as a mitochondrial inhibitor. The present study has focused on the inhibition of Na+/K+-ATPase activity by rottlerin, ouabain and digoxin in homogenates prepared from rat kidney and cultured astrocytes. The activity of Na+/K+-ATPase was measured by the absorption of inorganic phosphate product generated from the hydrolysis of ATP and the fluorescent transition of the dye RH421 induced by the movement of Na+/K+-ATPase. This approach has a potential to test whether the rottlerin effect on Na+/K+-ATPase is a direct inhibition of the enzyme activity. Rottlerin has been found to block the activity of Na+/K+-ATPase in a dose-dependent manner in both rat kidney and astrocyte homogenates. Therefore, rottlerin inhibited the activity of Na+/K+-ATPase directly in a cell-free preparation, thus strongly indicating that the effect was direct on the enzyme. In parallel experiments, ouabain and digoxin produced similar inhibitions of Na+/K+-ATPase activity in rat kidney while digoxin blocked the activity of Na+/K+-ATPase to a greater extent than ouabain in rat cortical cultured astrocytes. In a separate set of experiments, Na+/K+-ATPase in the astrocytic membrane was found to be unsaturated in E1(Na+)3 conformation in the presence of Na+ ions and this could explain the differences between the effects of digoxin and ouabain on the activity of Na+/K+-ATPase in rat astrocytes. In addition, it was found that at low concentrations of rottlerin, the activity of Na+/K+-ATPase was increased rather than inhibited. This effect was further investigated by studying rottlerin interactions with membrane lipids. The activity of Na+/K+-ATPase has been reported to be regulated by membrane lipids. The enzyme activity can be enhanced by increasing fluidity of the lipid membrane. I have, therefore, proposed that rottlerin binds to the membrane lipids and the effects of rottlerin on Na+/K+-ATPase are mediated by changes in the properties (fluidity) of the membrane. The hypothesis was tested by comparing rottlerin and a detergent, DOC (sodium deoxycholate), for their binding to the lipids by using a DMPC (1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine) monolayer technique. DOC has been shown to both increase and inhibit activity of Na+/K+-ATPase in a manner similar to that displayed by rottlerin. The effects of rottlerin and DOC on the DMPC monolayers were studied by measuring the surface pressure of DMPC monolayers and surface area per DMPC molecule. I established that both rottlerin and DOC decreased the surface pressure of DMPC monolayers and increased the surface area per DMPC molecule. This indicates that both rottlerin and DOC penetrated into the DMPC monolayers. If rottlerin can interact with the lipids, changes in fluidity of the lipid membrane cannot be ruled out and should be considered as a possible factor contributing to the effects of rottlerin on the activity of Na+/K+-ATPase. Overall, the study demonstrates that rottlerin is not only a PKC-delta inhibitor but can have additional effects, both on the enzyme activities (Na+/K+-ATPase) and/or on lipid-containing biological structures such as membranes. The findings have implication not only for studies where rottlerin was used as a supposedly specific PKC-delta inhibitor but also for mechanisms of its toxicity.

High salt intake contributes to the development of hypertension in salt-sensitive humans and animals and the mechanistic causes are poorly understood. In Dahl salt-sensitive (S) but not salt-resistant (R) rats, high salt diet increases cerebrospinal fluid (CSF) [Na+] and activates an aldosterone-mineralocorticoid receptor-epithelial sodium channel-endogenous ouabain (MR-ENaC-EO) neuromodulatory pathway in the brain that enhances the activity of sympatho-excitatory angiotensinergic and glutamatergic pathways, leading to an increase in sympathetic nerve activity (SNA) and blood pressure (BP). We hypothesize that high salt diet in Dahl S rats enhances Ang II release in the paraventricular nucleus (PVN), causing a decrease in local nitric oxide (NO) action and an increase in local glutamate release thereby elevating SNA, BP and heart rate (HR). The present study evaluated the effects of agonists or blockers of MR, ENaC, EO, nitric oxide synthase (NOS) or glutamate and AT1-receptors on the BP and HR responses to acute infusions of Na+ rich aCSF, intracerebroventricularly (icv), or in the PVN of Dahl S, R or Wistar rats or to high salt diet in Dahl S and R rats. In Wistar rats, aldosterone in the PVN enhanced the BP and HR responses to infusion of Na+ rich aCSF in the PVN, but not in the CSF, and only the enhancement was prevented by blockers of MR, ENaC and EO in the PVN. AT1-receptor blockers in the PVN fully blocked the enhancement by aldosterone and the responses to infusion of Na+ rich aCSF icv, or in the PVN. Na+ rich aCSF in the PVN caused larger increases in BP and HR in Dahl S vs. R rats and the responses to Na+ were fully blocked by an AT1-receptor blocker in the PVN. BP and HR responses to a NOS blocker in the PVN were the same, but L-NAME enhanced Na+ effects more in Dahl R than S rats. High salt diet attenuated increases in BP from L-NAME in the PVN of Dahl S but not R rats. AT1 and glutamate receptor blockers candesartan and kynurenate in the PVN decreased BP in Dahl S but not R rats on high salt diet. At the peak BP response to candesartan, kynurenate in the PVN further decreased BP whereas candesartan did not further decrease BP at the peak BP response to kynurenate. Our findings indicate that both an acute increase in CSF [Na+] and high salt intake in Dahl S rats increases AT1-receptor activation and decreases NO action in the PVN thereby contributing to the pressor responses to Na+ and presumably, to dietary salt-induced hypertension. The increased BP response to AT1-receptor activation in the PVN of Dahl S is mediated by enhanced local glutamate receptor activation. An MR-ENaC-EO pathway in the PVN can be functionally active and further studies need to assess its role in Dahl S rats on high salt intake.

Thesis (M.S.)--University of Toledo, 2009. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Science." Title from title page of PDF document. Bibliography: p. 39-48.

Doctor of Philosophy (Medicine) / Glutamate transporters play a role in removing extracellular excitatory neurotransmitter, L-glutamate into the cells. The rate of the uptake depends on the density of the transporters at the membrane. Some studies claimed that glutamate transporters could transit between the cytoplasm and the membrane on a time-scale of minutes. The present study examined the distribution of glutamate transporter GLAST predominantly expressed in rat cortical cultured astrocytes between the membrane and the cytoplasm by using deconvolution microscopy and then analyzing the images. The regulation of the distribution of GLAST was studied in the presence of glutamate transporter substrate (D-aspartate), purinergic receptor activators (α,β-methylene ATP, adenosine), neuroleptic drugs (clozapine, haloperidol), ammonia (hyperammonia) and Na+/K+-ATPase inhibitors (ouabain, digoxin and FCCP). It was demonstrated that the translocation of GLAST towards the plasma membrane was induced by D-aspartate, α,β-methylene ATP, adenosine, clozapine and ammonia (at 100 μM and very high concentrations of 10 mM). However, the inhibition of Na+/K+-ATPase activity had an opposite effect, resulting in redistribution of GLAST away from the membrane. It has previously been claimed that the membrane-cytoplasm trafficking of GLAST was regulated by phosphorylation catalysed by protein kinase C delta (PKC-delta). Involvement of this mechanism has, however, been put to doubt when rottlerin, a PKC-delta inhibitor, used to test the hypothesis showed to inhibit Na+/K+-ATPase-mediated uptake of Rb+, suggesting that rottlerin influenced the activity of Na+/K+-ATPase. As Na+/K+-ATPase converts ATP to energy and pumps Na+, K+ ions, thus helping to maintain normal electrochemical and ionic gradients across the cell membrane. Its inhibition also reduced D-aspartate transport and could impact on the cytoplasm-to-membrane traffic of GLAST molecules. Furthermore, rottlerin decreased the activity of Na+/K+-ATPase by acting as a mitochondrial inhibitor. The present study has focused on the inhibition of Na+/K+-ATPase activity by rottlerin, ouabain and digoxin in homogenates prepared from rat kidney and cultured astrocytes. The activity of Na+/K+-ATPase was measured by the absorption of inorganic phosphate product generated from the hydrolysis of ATP and the fluorescent transition of the dye RH421 induced by the movement of Na+/K+-ATPase. This approach has a potential to test whether the rottlerin effect on Na+/K+-ATPase is a direct inhibition of the enzyme activity. Rottlerin has been found to block the activity of Na+/K+-ATPase in a dose-dependent manner in both rat kidney and astrocyte homogenates. Therefore, rottlerin inhibited the activity of Na+/K+-ATPase directly in a cell-free preparation, thus strongly indicating that the effect was direct on the enzyme. In parallel experiments, ouabain and digoxin produced similar inhibitions of Na+/K+-ATPase activity in rat kidney while digoxin blocked the activity of Na+/K+-ATPase to a greater extent than ouabain in rat cortical cultured astrocytes. In a separate set of experiments, Na+/K+-ATPase in the astrocytic membrane was found to be unsaturated in E1(Na+)3 conformation in the presence of Na+ ions and this could explain the differences between the effects of digoxin and ouabain on the activity of Na+/K+-ATPase in rat astrocytes. In addition, it was found that at low concentrations of rottlerin, the activity of Na+/K+-ATPase was increased rather than inhibited. This effect was further investigated by studying rottlerin interactions with membrane lipids. The activity of Na+/K+-ATPase has been reported to be regulated by membrane lipids. The enzyme activity can be enhanced by increasing fluidity of the lipid membrane. I have, therefore, proposed that rottlerin binds to the membrane lipids and the effects of rottlerin on Na+/K+-ATPase are mediated by changes in the properties (fluidity) of the membrane. The hypothesis was tested by comparing rottlerin and a detergent, DOC (sodium deoxycholate), for their binding to the lipids by using a DMPC (1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine) monolayer technique. DOC has been shown to both increase and inhibit activity of Na+/K+-ATPase in a manner similar to that displayed by rottlerin. The effects of rottlerin and DOC on the DMPC monolayers were studied by measuring the surface pressure of DMPC monolayers and surface area per DMPC molecule. I established that both rottlerin and DOC decreased the surface pressure of DMPC monolayers and increased the surface area per DMPC molecule. This indicates that both rottlerin and DOC penetrated into the DMPC monolayers. If rottlerin can interact with the lipids, changes in fluidity of the lipid membrane cannot be ruled out and should be considered as a possible factor contributing to the effects of rottlerin on the activity of Na+/K+-ATPase. Overall, the study demonstrates that rottlerin is not only a PKC-delta inhibitor but can have additional effects, both on the enzyme activities (Na+/K+-ATPase) and/or on lipid-containing biological structures such as membranes. The findings have implication not only for studies where rottlerin was used as a supposedly specific PKC-delta inhibitor but also for mechanisms of its toxicity.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Made available in DSpace on 2015-04-01T14:16:00Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 5574506 bytes, checksum: a2d785f5339e8cb5e573693458ab5abd (MD5) Previous issue date: 2011-09-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Ouabain, known as a cardiotonic glycoside capable of inhibiting the Na+/K+ ATPase, was widely used for heart failure treatment. Identified as an endogenous substance, ouabain is capable of interfering with various physiological functions, including immune system modulation. Besides that, little is known about the involvement of this substance in nociceptive and inflammatory processes. The present study investigated the role of ouabain in acute peripheral inflammation induced by intraplantar administrartion of different phlogistic agents (carrageenan, compound 48/80, histamine, bradykinin, and PGE2) and in nociceptive processes (abdominal writhing induced by acetic acid and hot plate). Ouabain produced a significant reduction in the mouse paw edema induced by carrageenan and compound 48/80. This antiinflammatory effect of ouabain is associated to the inhibition of PGE2, bradykinin, and mast-cell degranulation, but not to histamine. Ouabain also presented a central and peripheral anti-nociceptive activity. This analgesic potential might be related to the inhibition of inflammatory mediators and to activation of opioid receptors, since it was reversed by naloxone, an opioid antagonist. Additionally, the analgesic effect of ouabain was not related to sedative effect or to motor function. Taken together, the present work demonstrated for the first time, in vivo, the antiinflammatory and analgesic potential of ouabain / A Ouabaína é um glicosídeo cardiotônico, inibidor da Na+/K+-ATPase, utilizada na clínica para o tratamento de insuficiência cardíaca. Atualmente, sabe-se que essa substância é endógena, e capaz de interferir em várias funções fisiológicas, inclusive em diversos aspectos do sistema imunológico. Apesar disso, pouco se sabe sobre seu envolvimento em processos inflamatórios e nociceptivos. Neste trabalho, foi avaliada a atividade da Ouabaína na inflamação aguda desencadeada pela administração de diversos agentes flogísticos (carragenina, composto 48/80, histamina, PGE2 e bradicinina) e em modelos nociceptivos (contorções abdominais induzidas por ácido acético e placa quente). A Ouabaína produziu uma redução no edema de pata produzido por carragenina e pelo composto 48/80. Esse potencial anti-inflamatório está relacionado ao bloqueio da degranulação de mastócitos, bem como pela inibição da via da PGE2 e da bradicinina, porém é independente da via da histamina. A Ouabaína também apresentou uma atividade anti-nociceptiva central e periférica. Esse efeito está vinculado à inibição da via dos mediadores inflamatórios e a mecanismos opióides, visto que foi revertido pela administração da naloxona, um inibidor dos receptores opióides. Adicionalmente, foi descrito que a inibição da dor pela Ouabaína não possui envolvimento com sedação ou diminuição da capacidade motora. O conjunto desses dados demonstra pela primeira vez, in vivo, a atividade anti-inflamatória e anti-nociceptiva da Ouabaína.

Na,K-ATPase é uma proteína de membrana que tem como função manter o equilíbrio osmótico nas células pela hidrólise de ATP. A ouabaína (OUA) se liga a Na,K-ATPase e é capaz de ativar cascatas de sinalização. As subunidades a da Na,K-ATPase possuem 4 isoformas que são distribuídas de forma diferenciada nos tecidos. As células da glia são importantes na resposta contra lesões no cérebro e também controlam a inflamação. Dados na literatura mostram que a OUA tem efeito protetor em alguns tipos de dano. O objetivo do estudo é avaliar a função da isoforma a2 na cultura de células da glia em resposta à OUA e ao LPS. Nós investigamos a ação da OUA em diversas concentrações e LPS (1g/mL) na viabilidade celular (LDH) e proliferação celular (MTT). O LPS foi utilizado como modelo de inflamação e uma das perguntas era se o tratamento prévio com OUA, seria capaz de reverter a ativação do fator de transcrição NF-kB que está envolvido com inflamação. O pré-tratamento com OUA diminuiu a ativação do NF-kB induzida pelo LPS. Após, nós silenciamos a isoforma a2 das células da glia com RNAi. Os nossos dados mostram que o pré-tratamento com OUA reverte o efeito na ativação do NF-kB causado pelo LPS. Provavelmente, a isoforma a2 está relacionada com alguma via de sinalização que interage com a via do LPS. / Na,K-ATPase is a conserved membrane protein which maintains the osmotic balance in the cell by the hydrolysis of ATP. Ouabain (OUA) binds to Na,K-ATPase and it can activate signaling pathways. The a subunits of Na,K-ATPase have 4 isoforms which are distributed in a different pattern in the tissues. Glial cells have an important role in the response against injury and they also control inflammation. Some data have reported that OUA can protect against some types of injury. The aim of this study is to evaluate the role of a2 isoform in glial cells in response to OUA and LPS stimulus. We investigated the action of OUA and LPS in cell viability (LDH) and cell proliferation (MTT). LPS was used as a model of inflammation and one of our questions was if the treatment with OUA before LPS was capable of reduce the activation of the transcription factor NF-kB which is involved in inflammation. The pre-treatment with OUA decreased the NF-kB activation induced by LPS. We also silenced the a2 isoform in culture glial cells with iRNA. Taken together our data showed that OUA pretreatment reversed the NF-kB activation induced by LPS in primary cultures of glial cells from mice. Probably,the a2 isoform is related with some signaling pathway that interacts with the LPS pathway.