Tsang, Siu Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 107-121). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.v / Table of Contents --- p.vi / List of Abbreviations --- p.x / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Renin-angiotensin system (RAS) --- p.1 / Chapter 1.1.1 --- Circulating RAS --- p.2 / Chapter 1.1.2 --- Tissue-specific RAS --- p.5 / Chapter 1.2 --- RAS inhibitors --- p.7 / Chapter 1.2.1 --- Angiotensin converting enzyme inhibitor --- p.8 / Chapter 1.2.2 --- Non-specific angiotensin II receptor blocker --- p.9 / Chapter 1.2.3 --- Specific AT1 receptor antagonist --- p.10 / Chapter 1.2.4 --- Specific AT2 receptor antagonist --- p.11 / Chapter 1.3 --- Pancreas and functions of exocrine pancreas --- p.14 / Chapter 1.3.1 --- Structure of pancreas --- p.14 / Chapter 1.3.2 --- Exocrine secretions and pancreatic enzymes --- p.16 / Chapter 1.3.3 --- Regulation of exocrine secretions --- p.17 / Chapter 1.4 --- Pancreatic RAS --- p.18 / Chapter 1.4.1 --- Expression and localization --- p.18 / Chapter 1.4.2 --- Regulation --- p.19 / Chapter 1.4.3 --- Clinical relevance to the pancreas --- p.20 / Chapter 1.5 --- Acute pancreatitis --- p.21 / Chapter 1.5.1 --- Pathogenesis --- p.21 / Chapter 1.5.2 --- Experimental models of acute pancreatitis --- p.22 / Chapter 1.5.3 --- Criteria of acute pancreatitis --- p.23 / Chapter 1.5.4 --- Oxidative stress in acute pancreatitis --- p.24 / Chapter 1.6 --- RAS and acute pancreatitis in exocrine pancreas --- p.26 / Chapter 1.6.1 --- RAS and acute pancreatitis --- p.26 / Chapter 1.6.2 --- RAS and pancreatic microcirculation --- p.26 / Chapter 1.6.3 --- RAS and tissue injury --- p.27 / Chapter 1.6.4 --- Exocrine pancreatic RAS and acute pancreatitis-induced injury --- p.28 / Chapter 1.7 --- Aims of study --- p.29 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Animal models and RAS inhibitors --- p.30 / Chapter 2.1.1 --- Cerulein-induced acute pancreatitis --- p.30 / Chapter 2.1.2 --- Prophylactic treatment with RAS inhibitors --- p.31 / Chapter 2.1.3 --- Therapeutic treatment with RAS inhibitors --- p.32 / Chapter 2.2 --- Evaluation of pancreatic injury --- p.32 / Chapter 2.2.1 --- Assessment of pancreatic water content --- p.33 / Chapter 2.2.2 --- Measurement of α-amylase activity in plasma --- p.33 / Chapter 2.2.3 --- Measurement of lipase activity in plasma --- p.34 / Chapter 2.3 --- Histopathological examinations --- p.34 / Chapter 2.3.1 --- Preparation of paraffin blocks --- p.35 / Chapter 2.3.2 --- Hematoxylin and eosin staining --- p.35 / Chapter 2.4 --- Biochemical assay of pancreatic oxidative status --- p.37 / Chapter 2.4.1 --- Sample preparation --- p.37 / Chapter 2.4.2 --- Quantification of protein content --- p.37 / Chapter 2.4.3 --- Measurement of glutathione levels --- p.38 / Chapter 2.4.4 --- Assessment of protein oxidation --- p.38 / Chapter 2.4.5 --- Assessment of lipid peroxidation --- p.39 / Chapter 2.4.6 --- Measurement of NADPH oxidase activity --- p.40 / Chapter 2.5 --- Studies of pancreatic digestive enzyme secretions from isolated acini --- p.40 / Chapter 2.5.1 --- Dissociation of acini from pancreatic tissue --- p.40 / Chapter 2.5.2 --- Treatment with peptides and RAS inhibitors --- p.42 / Chapter 2.5.3 --- Quantification of protein and DNA contents --- p.43 / Chapter 2.5.4 --- Measurement of a-amylase and lipase secretions --- p.44 / Chapter 2.5.5 --- RT-PCR analysis of RAS components in acinar cells --- p.44 / Chapter 2.6 --- Studies of RAS inhibitors on acute pancreatitis-induced systemic inflammation --- p.45 / Chapter 2.6.1 --- Systemic inflammation treatment --- p.45 / Chapter 2.6.2 --- Measurement of myeloperoxidase activity in lung and liver --- p.46 / Chapter 2.7 --- Statistical analysis --- p.47 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Time-course experiment of acute pancreatitis model --- p.48 / Chapter 3.1.1 --- Effect of acute pancreatitis on tissue injury --- p.48 / Chapter 3.1.2 --- Effects of acute pancreatitis on oxidative status --- p.48 / Chapter 3.2 --- Evaluation of ramiprilat and saralasin on changes of acute pancreatitis- induced pancreatic injury --- p.50 / Chapter 3.2.1 --- Changes in tissue injury and histopathology --- p.50 / Chapter 3.2.2 --- Changes in oxidative status --- p.57 / Chapter 3.3 --- Evaluation of losartan and PD123319 on changes of acute pancreatitis- induced pancreatic injury --- p.61 / Chapter 3.3.1 --- Changes in tissue injury and histopathology --- p.61 / Chapter 3.3.2 --- Changes in oxidative status --- p.68 / Chapter 3.4 --- Evaluation of acinar secretions of digestive enzymes --- p.71 / Chapter 3.4.1 --- Cholecystokinin octapeptide-induced acinar secretions --- p.71 / Chapter 3.4.2 --- Angiotensin II-induced acinar secretions --- p.71 / Chapter 3.4.3 --- Effects of losartan and PD 123319 on α-amylase secretion --- p.74 / Chapter 3.5 --- Existence and regulation of acinar RAS by acute pancreatitis --- p.75 / Chapter 3.5.1 --- Expression of angiotensinogen and its regulation by acute pancreatitis in acini --- p.76 / Chapter 3.5.2 --- Expression of AT1 receptor and its regulation by acute pancreatitis in acini --- p.76 / Chapter 3.5.3 --- Expression of AT2 receptor and its regulation by acute pancreatitis in acini --- p.76 / Chapter 3.5.4 --- Evaluation of RAS inhibitors in acute pancreatitis-induced acinar cells --- p.80 / Chapter 3.6 --- Preliminary data on acute pancreatitis-induced systemic inflammation --- p.81 / Chapter 3.6.1 --- Time-course experiment on lung injury --- p.81 / Chapter 3.6.2 --- Time-course experiment on liver injury --- p.83 / Chapter 3.6.3 --- Evaluation of losartan on systemic inflammation --- p.85 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- "Actions of RAS inhibitors on the changes of tissue injury, oxidative status and histopathology in acute pancreatitis-induced pancreas" --- p.87 / Chapter 4.1.1 --- Differential effects of ramiprilat and saralasin --- p.88 / Chapter 4.1.2 --- Differential effects of losartan and PD123319 --- p.92 / Chapter 4.2 --- Potential functions of RAS in pancreatic acinar secretions --- p.95 / Chapter 4.2.1 --- Potential role of AT1 receptor --- p.96 / Chapter 4.2.2 --- Potential role of AT2 receptor --- p.98 / Chapter 4.3 --- Regulation of RAS in acute pancreatitis-induced acini --- p.98 / Chapter 4.3.1 --- Regulation of RAS components in acinar cells --- p.99 / Chapter 4.3.2 --- Differential actions of losartan and PD123319 --- p.100 / Chapter 4.4 --- Potential role of RAS in acute pancreatitis --- p.102 / Chapter 4.4.1 --- Regulation of RAS components by acute pancreatitis --- p.102 / Chapter 4.4.2 --- Differential functions of AT1 and AT2 receptors in acute pancreatitis --- p.103 / Chapter 4.5 --- Conclusion --- p.104 / Chapter 4.6 --- Further studies --- p.105 / Chapter Chapter 5 --- Bibliography --- p.107

Pericytes, progenitor cells embedded in the microvascular wall, are crucial for vascular homeostasis. Renin is the rate-limiting enzyme that regulates blood pressure and fluid/electrolyte balance. Previous work suggested the relationship between renin-expressing/ producing cells and pericytes, however human kidney pericytes have not been characterized in depth and the molecular switch controlling renin cell plasticity is not understood. Here, I describe a method of isolation of CD146+CD34-CD45-CD56- pericytes, putative progenitors for renin-producing cells, from the human foetal kidney and demonstrate their potential in vitro to express and produce renin. Co-staining of pericyte markers (CD146 and NG2) and renin showed coincidence in the juxtaglomerular region and along renal arterioles in the human foetal kidney. I have obtained primary cultures of renal pericytes from the developing human kidney that were purified via fluorescence-activated cell sorting. Primary cultures of renal pericytes exhibited tri-lineage mesodermal differentiation potential. Renin expression was triggered by cAMP induction (10μM forskolin and 100μM 3-isobutyl-1- methylxanthine [IBMX] and resulted in 64.3 fold increase of renin mRNA (p <0.01) and 41.5 fold increase in enzymatic activity of renin (p <0.05) over controls. Pericytes derived from non-renal tissues (placenta and foetal adrenal glands) also expressed renin in an inducible fashion. Renin positive cells following induction were confirmed to be CD146+/NG2+. Interestingly, alpha-smooth muscle actin expression was not always correlated with renin immunostaining. Wnt/β-catenin signalling plays a crucial role during kidney development and in disease, specifically; in pericyte modulation of the Wnt pathway has been shown to regulate cell differentiation. CHIR 99021, a specific inhibitor of glycogen synthase kinase 3, mimicking Wnt signalling, and C59, a potent Porcupine acyltransferase inhibitor that is required for Wnt biological activity, were tested in renin induction experiments. Preliminary data showed that renin expression was blocked by Wnt activation, whereas Wnt suppression increased renin mRNA levels above the level of stimulation achieved with cAMP inducers. These findings provide evidence that renin expression is an intrinsic feature of pericytes and can be regulated through the Wnt pathway.

The renin-angiotensin system (RAS) is critical for the control of blood pressure (BP) and salt balance in mammals. Studies reveal that local RAS are present in the rat brain and renin is the first effector of the brain RAS for generating angiotensin II (Ang II) which exerts diverse physiological actions in both peripheral and central nervous system. The existence of renin within the brain has now been demonstrated by numerous studies. Previous studies suggest that renin may go through angiotensin-dependent and independent pathway to influence vascular tone, by Ang II type 1 receptor (AT1R) and renin specific (pro)renin receptor (PRR), respectively. Studies also indicate that AT1R and PRR are highly expressed in the nucleus tractus solitarii (NTS), which is important for central feedback regulation of BP. Further studies have shown that Ang II contributes to the release of NO, which plays an important role in cardiovascular regulation in the NTS. These results indicate that renin plays cardiovascular modulatory role in the NTS. However, the mechanisms how renin modulate cardiovascular functions in the NTS remained unclear. In the present study, I investigated the molecular mechanisms of renin-induced cardiovascular effects in the NTS. Unilateral microinjection of renin into the NTS of WKY rats produced prominent depressor and bradycardic effects. Pretreatment with a non-selective NOS inhibitor L-NAME, eNOS specific inhibitor L-NIO, Akt inhibitor IV, and PI3K inhibitor LY294002 significantly attenuated the cardiovascular response evoked by renin, whereas nNOS specific inhibitor Vinyl-L-NIO and MEK inhibitor PD98059 did not cause significant changes. Western blot studies showed renin increased eNOSS1177 and AktS473 phosphorylation instead of nNOSS1416 and ERK1/2T202/Y204 phosphorylation, and pretreatment with LY294002 blocked renin-induced eNOSS1177 and AktS473 phosphorylation. These results indicated that renin might go through PI3K-Akt-eNOS pathway to increase eNOS activity and ultimately result in NO release. The cardiovascular effects of renin were also attenuated by renin specific inhibitor aliskiren, angiotensin converting enzyme inhibitor lisinopril, AT1R antagonist losartan, and intracellular Ca2+ chelator, BAPTA-AM instead of G protein £]£^ subunit inhibitor gallein, PLC inhibitor U73122, calmodulin inhibitor (W-7) and (pro)renin receptor blocker, handle region peptide. These results indicated that renin mainly through AT1R to regulate BP. Therefore, my results indicated that the modulation of cardiovascular effects of renin in the NTS involves AT1R-PI3K-Akt pathway to activate eNOS activation.

Amiodarone (AM) is a potent antidysrhythmic agent which can cause potentially life-threatening pulmonary fibrosis, and N-desethylamiodarone (DEA) is a metabolite of AM that may contribute to the toxicity of AM in vivo. Recent evidence has implicated the involvement of the renin-angiotensin system (RAS) in the initiation and progression of amiodarone-induced pulmonary toxicity. In cultured HPL1A human peripheral lung epithelial cells, we found AM to be converted to DEA minimally (< 2%) after 24 h of incubation, indicating that the HPL1A cell culture model can be used to study the effects of AM and DEA independently. Apoptotic cell death was assessed by annexin-V-FITC (ann-V) staining and by terminal deoxynucleotidyl transferase-mediated 2’-deoxyuridine 5’-triphosphate nick-end labeling (TUNEL), while necrotic cell death was determined by propidium iodide (PI) staining. The percentage of PI positive cells increased over six-fold after 24 h treatment with 20 μM AM (80.8%) compared to control (12.0%), and doubled after 24 h treatment with 3.5 μM DEA (20.4%) compared to control (10.8%). The percentage of ann-V positive cells decreased from 8.26% (control) to 1.56% following 24 h treatment with 10 μM AM and more than doubled after 24 h incubation with 3.5 μM DEA (22.0%) compared to control (9.86%) (p<0.05). Treatment for 24 h with 5.0 μM DEA caused the percentage of TUNEL positive cells to increase from 4.21% (control) to 26.7% (p<0.05). Vitamin E (5 – 20 μM) did not protect against AM or DEA cytotoxicity, as determined by ann-V and PI dual staining. Angiotensin II (100 pM – 1 μM) alone or in combination with AM or DEA did not alter cytotoxicity. Furthermore, the angiotensin converting enzyme inhibitor captopril did not protect against AM or DEA cytotoxicity. In conclusion, in vitro, AM activates primarily necrotic pathways, whereas DEA activates both necrotic and apoptotic pathways, and the RAS does not seem to be involved in AM or DEA cytotoxicity in HPL1A cells. Multiple mechanisms may contribute to the initiation of lung damage observed clinically, due to actions of both AM and its metabolite DEA. Keywords: amiodarone, desethylamiodarone, vitamin E, renin-angiotensin system / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2009-11-26 13:57:09.65

Thesis (Ph. D.)--Washington State University, August 2008. / Includes bibliographical references.

Thesis (doctoral)--Rijksuniversiteit te Groningen.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Robert J. Contreras, Florida State University, College of Arts and Sciences, Dept. of Psychology. Title and description from dissertation home page (viewed Jan. 24, 2006). Document formatted into pages; contains vi, 58 pages. Includes bibliographical references.

The renin angiotensin system (RAS) is critical for the regulation of blood pressure, electrolyte/fluid, and metabolic homeostasis. Regulation of the RAS is important in the development and treatment of hypertension. As part of the rate-limiting step in a cascade of events ending in the production of angiotensin II, renin is a major regulator of the RAS. Its expression is localized to the juxtaglomerular (JG) cells of the JG apparatus where it is exquisitely located to respond to various physiological cues. Understanding the regulation of renin expression and development of the juxtaglomerular cells is critical. Two regulatory elements, the enhancer and proximal promoter, have been found to be important in controlling cell- and tissue- specific baseline expression of the renin gene. Within the enhancer is a hormone response element (HRE) which confers a high level of activity to the enhancer. Nuclear receptors that bind this element have been found to bind the HRE and regulate renin promoter transcriptional activity. We have previously characterized the role of the orphan nuclear receptor Nr2f6 as a negative regulator of renin expression that mediates its effects through the HRE. However, gel shift assays indicate that there are other transcription factors binding this element. We have identified other orphan nuclear receptors that regulate renin expression. The first, Nr2f2 acts as a negative regulator of renin promoter activity but does not appear to affect baseline expression of the endogenous renin gene. The other, Nr4a1, is a positive regulator of renin expression, but it does not appear to mediate its effects through the HRE. The transcriptional regulation of gene expression is controlled by regulatory elements separated by large distances from promoters. We and others have found that short transgenes of the human renin (hREN) locus are not sufficient to protect them from positional effects that can be exerted upon them by neighboring regulatory elements. We discovered a random truncation in a large genomic construct of the hREN gene that resulted in ubiquitous expression of renin not seen with the intact form. By locating the genomic insertion site of that transgene in the Zbtb20 gene, we found that the hREN promoter had come under control of that gene's regulatory elements. The gene downstream of renin however maintained its tissue-specific expression. We found that CCCTC-binding factor (CTCF) bound to chromatin in and around the renin locus. The presence of CTCF suggests that insulator elements are present in the renin locus, and their loss likely explains the results above. Finally, we assessed the role of microRNAs in the development of renin expressing cells in the mouse kidneys by cell-specific deletion of the processing enzyme Dicer. This resulted in reduction of renin expression and a decrease in the number of renin expressing cells in the kidney. Mice were hypotensive and had several kidney abnormalities including a hypertrophied vasculature and striped fibrosis. These results indicate that Dicer and the miRNAs it processes are critical for the development and maintenance of renin expressing cells that contribute to normal kidney development.

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