Hypertensive rats produced by in vivo introduction of the human renin gene

A Combination of Dexmedetomidine and Lidocaine Is a Cardiovascularly Safe Dental Local Anesthetic for Hypertensive Rats Treated With a Nonselective β-Adrenergic Antagonist

Hypertensive patients receiving nonselective β-adrenergic antagonists are vulnerable to hypertension and bradycardia when injected with dental local anesthetic formulations containing epinephrine. Dexmedetomidine (DEX), an α₂-adrenergic agonist, has been reported to prolong and enhance the local anesthetic effects of lidocaine. The cardiovascular effects of the DEX-lidocaine combination have not yet been investigated in the presence of nonselective β-adrenergic antagonists. Therefore, we assessed the cardiovascular effects of the DEX-lidocaine combination in spontaneously hypertensive rats (SHR) treated with a nonselective β-adrenergic antagonist (propranolol). We injected propranolol-treated rats with various concentrations of DEX alone, 100 μg/kg epinephrine alone, or 5 μg/kg DEX combined with 2% lidocaine and measured their blood pressure (BP) and heart rates (HR) to assess the cardiovascular effects. The BP of propranolol-treated SHR was significantly increased by treatment with 100 μg/kg epinephrine alone. The BP and HR of propranolol-treated SHR were not significantly changed by treatment with low concentrations of DEX, but they were significantly decreased by treatment with a high concentration of DEX (50 μg/kg). Moreover, there was no significant difference in the BP and HR of propranolol-treated SHR after the injection of a combination of 5 μg/kg DEX and 2% lidocaine. Thus, the DEX-lidocaine combination may be an acceptable addition to dental local anesthetic solutions from a cardiovascular standpoint for hypertensive patients receiving nonselective β-adrenergic antagonists.

Oral adsorbent AST-120 ameliorates endothelial dysfunction independent of renal function in rats with subtotal nephrectomy

It is important to consider a strategy to halt the development of cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Oral adsorbent AST-120 retards deterioration in renal function, reducing indoxyl sulfate (IS) accumulation. The aim of this study was to determine whether AST-120 improves endothelial dysfunction by reducing oxidative/nitrative stress in a rat-CKD model. Subtotally nephrectomized (Nx) rats aged 17 weeks were divided into two groups: control rats and rats orally treated with AST-120. Two weeks after initiation of AST-120, serum and urinary IS levels, renal histological scores and endothelium-dependent vascular responses (EDVRs) in the aorta were investigated. EDVR in 5-h incubation with 250 microg ml(-1) IS was also examined in normal rat aortas. Nitrotyrosine content, mRNA expression of p47phox, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase component, and expression and phosphorylation (serine-1177) of endothelial nitric oxide synthase (eNOS) in the aorta were examined in untreated and treated Nx rats. At the end of treatment, renal function and histological scores were not different in the two groups. AST-120 prevented the elevation of serum IS level in Nx rats, reducing urinary IS excretion, and ameliorated decreased EDVR in Nx rats. Incubation with IS tended to reduce EDVR in normal aortas, albeit insignificantly. AST-120 also suppressed nitrotyrosine accumulation and inhibited p47phox expression in Nx rats. The eNOS expression and phosphorylation were similar in the two groups. In conclusion, AST-120 ameliorated endothelial dysfunction and alleviated oxidative/nitrative stress in the aorta through reduced accumulation of IS, independent of renal function, in a rat CKD model.

Pioglitazone enhances the antihypertensive and renoprotective effects of candesartan in Zucker obese rats fed a high-protein diet

The metabolic syndrome is a risk factor for the development of chronic kidney disease. Angiotensin II type 1 receptor blockers (ARBs) and thiazolidinediones (TZDs) provide renovascular protection, probably in the metabolic syndrome. However, the effect of both agents administered together in patients with metabolic syndrome remains to be determined. The aim of this study was to assess the effects of ARB plus TZD combination therapy in Zucker obese rats fed a high-protein diet, an animal model of metabolic syndrome and renal injury. Zucker obese rats were fed a high-protein diet (OHP; n=6), a high-protein diet containing candesartan, an ARB (OHP+C; n=6), or a high-protein diet containing both candesartan and pioglitazone (OHP+CP; n=6) for 12 weeks. Systolic blood pressure and urinary protein excretion were measured throughout the study, and renal histology and immunohistochemistry were assessed at 12 weeks. OHP rats developed hypertension (157+/-4 mmHg) and proteinuria (178+/-44 mg/d), and these conditions were significantly ameliorated by candesartan (to 143+/-3 mmHg and 84+/-25 mg/d, respectively). Pioglitazone enhanced the antihypertensive and anti-proteinuric effects of candesartan (121+/-3 mmHg, 16+/-8 mg/d, respectively). Histologically, candesartan ameliorated glomerulosclerosis, podocyte injury, interstitial fibrosis and monocyte/macrophage infiltration into the tubulointerstitium in the kidneys of OHP rats. Pioglitazone abrogated residual interstitial fibrosis in the kidneys of OHP+C rats. Our results suggested that pioglitazone augmented the antihypertensive, anti-proteinuric and possibly renal anti-fibrotic actions of candesartan in Zucker obese rats fed a high-protein diet. The combination therapy of ARB and TZD may protect against renal injury in patients with metabolic syndrome.

Pioglitazone ameliorates endothelial dysfunction in obese rats with nephropathy

Endothelial dysfunction is a key event in the development of renovascular complications in the metabolic syndrome. The aim of this study was to elucidate the pathogenetic mechanisms involved in renovascular injuries in the Zucker obese rat, a model of the metabolic syndrome, and to examine the therapeutic effects of pioglitazone, a thiazolidinedione. Obese rats fed high-protein diet (OHP) for 12 weeks exhibited nephropathy and endothelial dysfunction, which were improved by pioglitazone. Accumulation of nitrotyrosine, a tracer of nitrative stress, was increased in aorta of the OHP group. The mRNA expressions of NADPH oxidase components and inducible nitric oxide synthase in the aorta were enhanced in the OHP group. Pioglitazone reduced nitrotyrosine in the aorta of the OHP group, inhibiting the augmented expression levels of both. These results suggest that nitrative stress could cause endothelial dysfunction in the rat model of metabolic syndrome with nephropathy, and that pioglitazone ameliorates these injuries, presumably by reducing nitrative stress.

Transcription factor decoy oligonucleotide-based therapeutic strategy for renal disease

Renal disease, including slight renal injuries, has come to be seen as one of the risk factors for cardiovascular events. At present, most conventional therapy is inefficient, and tends to treat the symptoms rather than the underlying causes of the disorder. Gene therapy based on oligonucleotides (ODN) offers a novel approach for the prevention and treatment of renal diseases. Gene transfer into somatic cells to interfere with the pathogenesis contributing to renal disease may provide such an approach, leading to the better prevention and treatment of renal disease. The major development of gene transfer methods has made an important contribution to an intense investigation of the potential of gene therapy in renal diseases. Amazing advances in molecular biology have provided the dramatic improvement in the technology that is necessary to transfer target genes into somatic cells. Gene transfer methods, especially when mediated by several viral vectors, have improved to a surprising extent. In fact, some (retroviral vectors, adenoviral vectors, or liposome-based vectors, etc.) have already been used in clinical trials. On the other hand, recent progress in molecular biology has provided new techniques to inhibit target gene expression. The transfer of cis-element double-stranded ODN (= decoy) has been reported to be a powerful novel tool in a new class of antigene strategies for gene therapy. The transfer of decoy ODN corresponding to the cis sequence will result in attenuation of the authentic cis-trans interaction, leading to the removal of trans-factors from the endogenous cis-elements with a subsequent modulation of gene expression.

An efficient gene transfer method mediated by ultrasound and microbubbles into the kidney

BACKGROUND

Safety issues are of paramount importance in clinical human gene therapy. From this point of view, it would be better to develop a novel non-viral efficient gene transfer method. Recently, it was reported that ultrasound exposure could induce cell membrane permeabilization and enhance gene expression.

METHODS

In this study, we examined the potential of ultrasound for gene transfer into the kidney. First, we transfected rat left kidney with luciferase plasmid mixed with microbubbles, Optison, to optimize the conditions (duration of ultrasound and concentration of Optison). Then, 4, 7, 14 and 21 days after gene transfer, luciferase activity was measured. Next, localization of gene expression was assessed by measuring luciferase activity and green fluorescent protein (GFP) expression. Expression of GFP plasmid was examined under a fluorescence microscope at 4 and 14 days after gene transfer. Finally, to examine the side effects of this gene transfer method, biochemical assays for aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine (Cre) were performed.

RESULTS

Optison and/or ultrasound significantly enhanced the efficiency of gene transfer and expression in the kidney. Especially, 70-80% of total glomeruli could be transfected. Also, a significant dose-dependent effect of Optison was observed as assessed by luciferase assay (Optison 25%: 12.5 x 10(5) relative light units (RLU)/g tissue; 50%: 31.3 x 10(5) RLU/g tissue; 100%: 57.9 x 10(5) RLU/g tissue). GFP expression could be observed in glomeruli, tubules and interstitial area. Results of blood tests did not change significantly after gene transfer.

CONCLUSIONS

Overall, an ultrasound-mediated gene transfer method with Optison enhanced the efficiency of gene transfer and expression in the rat kidney. This novel non-viral method may be useful for gene therapy for renal disease.

Therapeutic potential of decoy oligonucleotides strategy in cardiovascular diseases

Recent progress in molecular biology has provided several new techniques to inhibit target gene expression. In particular, the application of DNA technology, such as an antisense strategy, to regulate the transcription of disease-related genes in vivo has important therapeutic potential. Recently, transfer of cis-element double-stranded oligonucleotides (ODN) (= decoy) has been reported as a new powerful tool in a new class of antigene strategies for gene therapy. Transfer of the double-stranded ODN corresponding to the cis-sequence will result in attenuation of the authentic cis-trans interaction, leading to removal of trans-factors from the endogenous cis-elements with subsequent modulation of gene expression.

Genetic targeting of the renin-angiotensin system for long-term control of hypertension

Although traditional approaches are effective for the treatment and control of hypertension, they have not succeeded in curing the disease, and have therefore reached a plateau. As a result of the completion of the Human Genome Project and the continuous advancement in gene delivery systems, it is now possible to investigate genetic means for the treatment and possible cure for hypertension. In this review we discuss the potential of genetic targeting of the renin-angiotensin system for the treatment of hypertension. We provide examples of various approaches that have used antisense technology with a high degree of success. We focus on our own research, which targets the use of antisense of the angiotensin type I receptor in various models of hypertension. Finally, we discuss the future of antisense technology in the treatment of human hypertension.

Novel molecular therapeutic approach to cardiovascular disease based on hepatocyte growth factor

Gene therapy techniques are being developed as potential treatments for cardiovascular diseases. During the past decade, many gene transfer methods including viral transfer techniques have been developed, and some are being applied clinically in human gene therapy studies. Recently, we have developed a novel gene transfer method mediated by Hemagglutinating Virus of Japan (HVJ) liposome, with which we have already reported several cases of successful gene transfer in vivo. Since the virus is inactivated by ultraviolet light, there is little potential for biological hazard with this method as compared to other viral gene transfer approaches. We also developed a novel strategy of gene therapy for cardiovascular diseases utilizing hepatocyte growth factor (HGF) which is an endothelial cell specific growth factor and an angiogenic growth factor. Based on these facts, we hypothesized that HGF may prevent restenosis after angioplasty through re endothelialization and myocardial infarction through induction of angiogenesis. The present results provide evidence of the efficacy of supplemental therapy with HGF by gene transfer in cardiovascular diseases. These data suggest the efficacy of novel molecular therapeutic approaches as gene therapy for cardiovascular diseases such as restenosis and myocardial infarction.

In vivo transfer of antisense oligonucleotide against urinary kininase blunts deoxycorticosterone acetate-salt hypertension in rats

We have previously reported that the renal kallikrein-kinin system suppressed the development of deoxycorticosterone acetate (DOCA)-salt hypertension. Kinins were degraded in the kidney mainly by carboxypeptidase Y (CPY)-like kininase. Blockade of renal kinin degradation may reduce hypertension in the developmental stage. We constructed an antisense oligonucleotide against rat CPY homologue (5'-CAT-CTC-TGC-TTC-CTT-GTG-TC-3', AS) and its randomized control oligonucleotide (5'-TCC-TTC-CTG-CTT-GAG-TTC-CT-3', RC), and prepared an HVJ-liposome complex that prolongs and increases the effectiveness of the antisense oligonucleotide. Antisense oligonucleotide was transfected (25 nmole rat(-1), in terms of nucleotide) into the kidney from the renal artery. Blood pressure was measured through a catheter inserted into the abdominal aorta. Mean blood pressure (MBP) in DOCA-salt treated (for 2 weeks) Sprague Dawley strain rats was 130+/-3 mmHg (n=11), and was reduced significantly (P<0.05) more by AS transfection (122+/-4 mmHg, n=6) than by RC treatment (137+/-6 mmHg, n=5) 4 days after the transfection. This reduction in MBP was accompanied by increased urinary sodium excretion (AS, 8.4+/-1.5 mmole day(-1); RC, 4.6+/-0.5 mmole day(-1), P<0.05) and a reduction in urinary CPY-like kininase activity. Ebelactone B (5 mg kg(-1), twice a day, p.o.), an inhibitor for urinary CPY-like kininase, also reduced MBP and induced natriuresis to the same degree as AS. Lisinopril, an inhibitor for angiotensin converting enzyme (ACE) failed to reduce the elevated MBP. These results suggest that CPY-like kininase may have more contribution than ACE to degrade kinin in the kidney, and that knockdown of CPY-like kininase in the kidney may partly prevent rat DOCA-salt hypertension.

Transcription factor decoy for NFkappaB inhibits cytokine and adhesion molecule expressions in synovial cells derived from rheumatoid arthritis

OBJECTIVE

Numerous cytokines are expressed in lesions of synovial hyperplasia of patients with rheumatoid arthritis (RA), and their pathophysiological contributions have been the subject of speculation. These genes are regulated by the transcription factor NFkappaB which in turn is activated by tumour necrosis factor-alpha (TNF-alpha) and cytokines. In this study we examined the inhibition of the production of pro-inflammatory cytokines, adhesion molecule and matrix metalloproteinase (MMP) from synovial tissue of patients with RA by the introduction of synthetic double-stranded DNA with high affinity for the NFkappaB binding site.

METHOD

NFkappaB decoy oligonucleotides (ODN) were introduced with the aid of the haemagglutinating virus of Japan (HVJ)-liposome method into synovial tissue or synovial cells derived from patients with RA. The levels of interleukin-1beta (IL-1beta), IL-6, TNF-alpha, intercellular adhesion molecule-1 (ICAM-1) and MMP-1 were determined by means of enzyme-linked immunosorbent assay (ELISA) and Northern blotting analysis. A cell counting kit was used to study the effect of NFkappaB decoy ODN on synovial cell proliferation.

RESULTS

The production of these mediators was significantly inhibited by the introduction of NFkappaB decoy ODN compared with the effect of scrambled decoy ODN. Transfection of NFkappaB decoy ODN resulted in a significant inhibition of synovial cell proliferation as compared with that of scrambled decoy ODN.

CONCLUSION

The results demonstrated in this study suggest the potential usefulness of NFkappaB decoy ODN for gene therapy of inflammatory synovitis of RA.

In vivo administration of a nuclear transcription factor-kappaB decoy suppresses experimental crescentic glomerulonephritis

Glomerular expression of cytokines, interleukin-1 (IL-1), and tumor necrosis factor-alpha (TNF-alpha), together with leukocytic infiltration, are prominent features in crescentic glomerulonephritis. Because these cytokines are targets for nuclear transcription factor-kappaB (NF-kappaB), the use of NF-kappaB decoy oligodeoxynucleotide (ODN) treatment was evaluated in an experimental disease model. Crescentic glomerulonephritis was induced in primed Wistar rats by injection of sheep antiglomerular basement membrane serum. Thirty minutes after injection, rats were anesthetized and the left kidney was perfused with NF-kappaB decoy ODN or scrambled ODN control mixed with a virus-liposome complex, and then killed 7 d later. Animals given the scrambled control ODN developed severe glomerulonephritis by day 7 with heavy proteinuria, glomerular crescents and interstitial lesions, marked leukocytic infiltration, and upregulated renal expression of cytokines (IL-1 and TNF-alpha) and adhesion molecules (intercellular adhesion molecule-1). In contrast, NF-kappaB decoy ODN treatment substantially inhibited the disease with a 50% reduction in proteinuria, a threefold reduction in histologic damage, a 50% reduction in leukocytic infiltration, and a 50 to 80% reduction in the renal expression of cytokines and leukocyte adhesion molecules. In conclusion, this study has demonstrated that NF-kappaB plays a key role in cytokine-mediated renal injury and that NF-kappaB decoy ODN treatment has clear therapeutic potential in rapidly progressive glomerulonephritis.

Prevention of hypoxic liver cell necrosis by in vivo human bcl-2 gene transfection

Prevention of hypoxic cell death is a key to successful liver transplantation. We developed a new method for preventing liver hypoxic cell death by introducing an anti-cell death gene directly into rat livers. When the human bcl-2 gene (hbcl-2) was directly transfected into rat livers together with non-histone chromosomal protein high mobility group 1 (HMG1) by the hemagglutinating virus of Japan (Sendai virus; HVJ)-liposome method, human Bcl-2 protein (hBcl-2) was efficiently expressed. Electron microscopy and fluorescence microscopy revealed that hepatocytes expressing exogenous hBcl-2 were almost completely protected the hypoxic cell necrosis. The expression of the hBcl-2 also inhibited activation of caspase-3 (-like) proteases and liver dysfunction. Thus, we conclude that transfection of the hbcl-2 gene through HVJ-liposome method is useful to prevent liver cell necrosis induced by hypoxia. This finding could lead to new strategies to avoid the hypoxic cell death, the major problem in liver transplantation.

In vivo direct gene transfer into articular cartilage by intraarticular injection mediated by HVJ (Sendai virus) and liposomes

OBJECTIVE

To establish a system for efficient, direct in vivo gene transfer into joints.

METHODS

A hemagglutinating virus of Japan (HVJ; Sendai virus)-liposome suspension containing SV40 large T antigen (SVT) gene was injected intraarticularly into knee joints of 6-week-old female Lewis rats. Rats were killed at various times for immunohistochemical analysis of the expression of SVT gene.

RESULTS

The expression of SVT gene was detected immunohistochemically in chondrocytes in the superficial and middle zones of articular cartilage in the knee joints. The average percentage of SVT-positive cells was estimated to be approximately 30% on days 3, 7, 14, and 21 after transfection. Moreover, no pathologic change caused by HVJ-liposome injection was observed in the joints.

CONCLUSION

The transfection frequency and stability of expression recognized in this study indicate the possibility of a strategy for treatment of joint disorders, including arthritis, using direct gene transfer.

Efficient gene transfer method into the whole heart through the coronary artery with hemagglutinating virus of Japan liposome

OBJECTIVE

To confirm gene transfer techniques especially into the whole heart, we tried out a gene transfer method involving liposome with the viral envelope hemagglutinating virus of Japan liposome as an alternative to existing techniques such as cationic lipofection or other viral vectors.

METHOD

For this study, hemagglutinating virus of Japan liposome (H group) or cationic liposome (L group) was used to compare the efficacy of gene transfection of oligonucleotide labeled with fluorescein isothiocyanate and cDNA of beta-galactosidase and human manganese-superoxide dismutase. Fluorescein-labeled oligonucleotide, cDNA of beta-galactosidase, or manganese-superoxide dismutase was complexed with liposomes, DNA-binding nuclear protein, and the viral protein coat of hemagglutinating virus of Japan. After donor rat hearts arrested by cardioplegia had been harvested, the coronary artery during cardioplegic arrest was infused via an aortic cannula with the liposome-gene complex. Next, the hearts were transplanted into the abdomen of recipient rats of the same strain, and all recipients were put to death after 3 days of transfection.

RESULTS

Fluorescein isothiocyanate was detected in the nuclei of more than 70% of the myocytes (75% +/- 14%, n = 5) in the H group compared with fewer than 10% in the L group (7% +/- 5%, n = 5). The intensity of fluorescein isothiocyanate was significantly higher in the H group (979 +/- 112 FI) than in the L group (116 +/- 68 FI). beta-Galactosidase was expressed in the cytosol of more than 50% of the myocytes in the H group (61% +/- 7%, n = 5) compared with none in the L group (0%, n = 5). After 3 days of gene transfection, and when exposed to ischemia (30 minutes, 37 degrees C) and reperfusion (30 minutes, 37 degrees C) with Langendorff apparatus, the hearts transfected with manganese-superoxide dismutase (S group, n = 5) showed a significantly higher percentage of recovery of left ventricular end-diastolic pressure (S vs C, 86% +/- 3% vs 54% +/- 12%) and coronary flow (98% +/- 2% vs 66% +/- 12%) than did the control hearts (C group, n = 5). Western blotting analysis showed an apparent increased expression of manganese-superoxide dismutase in the hearts transfected with manganese-superoxide dismutase compared with the control hearts. These results clearly demonstrated that the donor hearts were transfected with fluorescein-labeled oligonucleotide and the beta-galactosidase gene as a result of coronary infusion of the hemagglutinating virus of Japan liposome during cardioplegic arrest at the time of harvest. Furthermore, the hearts transfected with manganese-superoxide dismutase showed significant improvement in tolerance against ischemia reperfusion injury.

CONCLUSION

We believe that this method represents a novel in vivo gene transfer technique for the heart and thus may provide a new tool for research and therapy of heart transplantation.

Specific receptor binding of renin on human mesangial cells in culture increases plasminogen activator inhibitor-1 antigen

Some proteases possess a membrane receptor that focalizes their proteolytic activity on the cell surface and may mediate a proliferative effect, such as urokinase on glomerular epithelial cells. Since some hypertensive states are associated with high concentrations of renin and proliferation of arteriolar smooth muscle cells, we asked whether renin, an aspartyl-protease, would bind to mesangial cells that are smooth-muscle derived cells, which would induce their proliferation. The binding of 125I labeled recombinant human renin (125I-R) was studied on human primary mesangial cells and mesangial cells immortalized by transfection with SV40-T antigen. At 37 degrees C, the binding of 125I-R was time dependent and reached a plateau after two hours. 125I-R was found to bind in a saturable and specific manner with a Kd = 0.4 nM and 1 nM and 8,000 and 2,000 binding sites/cell, for primary and immortalized cells, respectively. When binding experiments were performed in the presence RO 42-5892, a synthetic inhibitor of renin, RO 42-5892 could inhibit the specific binding of labeled renin only at concentrations 1,000 times superior to the IC 50, indicating that the renin-mesangial receptor interaction did not depend on the active site of renin. Analysis by SDS-PAGE and autoradiography of cross-linking experiments of 125I-R bound to a membrane preparation showed a band of approximately 110 to 120 kDa, suggesting a Mr of 70 to 80 kDa for the renin receptor. Incubation of mesangial cells with 100 nM renin for 24 hours provoked a 100% increase of 3H thymidine incorporation that was not accompanied by an increase of the cell number, even after a seven day period of incubation. However, the incubation of mesangial cells with renin for 24 hours induced a significant increase (170% of control, P = 0.04) of plasminogen activator inhibitor-1 (PAI1) antigen in the conditioned medium. In conclusion, we have shown that human mesangial cells in culture express a specific receptor for renin, and that the binding of renin increases 3H thymidine incorporation independently of renin enzymatic activity. The absence of cell proliferation, the increase of 3H thymidine incorporation and the increase of PAI1 antigen suggest that the binding of renin can induce mesangial cell activation, which is reflected by a change in the fibrinolytic capacity of the cells. The role of this receptor remains to be determined in nephropathies and hypertensive states associated with high plasma/tissue renin concentrations, hypertrophy of mesangial or smooth muscle cells and extracellular matrix remodeling.

Human gene therapy in gastrointestinal diseases: in vivo and in vitro approaches

The first clinical trial in human gene therapy began in 1989 with the successful introduction of marker genes into peripheral blood cells as tumor-infiltrating lymphocytes (TIL) in order to investigate the biological behavior of manipulated cells in humans. In further studies, it was possible to ameliorate clinical genetic diseases based on only one single genetic defect such as adenosine deaminase deficiency (ADA) by repeated infusion of manipulated peripheral blood cells. Meanwhile, a multitude of clinical gene transfer studies were initiated. Three main strategies have thus far been applied in human cancer gene therapy: (1) Reinforcement of the body's immune response by gene transfer into immunological cells; (2) reinforcement of the immune response by manipulating tumor cells; and (3) transfer of drug-sensitive genes into tumor cells with subsequent drug treatment. The first clinical trial in gene therapy for gastrointestinal diseases was performed in 1992 with the introduction of the low-density protein receptor gene (LDL) into liver tissue. Human cancer gene therapy of gastrointestinal diseases is still only in the initial phase of research.

Mechanism of cAMP regulation of renin gene transcription by proximal promoter

Renin is produced mainly by the kidney, and cAMP is a main positive regulator of its synthesis. This study was undertaken to analyze the molecular mechanism of cAMP-mediated regulation of Ren-1C gene transcription by the proximal promoter. We first showed that the promoter region from -365 to +16 of the mouse renin gene (Ren-1C) mediated the cAMP-induced chloramphenicol acetyltransferase gene expression in embryonic kidney-derived 293 cells. Deletion analysis and heterologous promoter assay disclosed that the proximal promoter region from -75 to +16 was able to activate chloramphenicol acetyltransferase expression by cAMP, and indicated that the proximal promoter element from -75 to -47 (RP-2 element) overlapping the TATA-like region was able to confer cAMP responsiveness. Electrophoretic mobility shift assay and DNase I footprinting analysis demonstrated that novel nuclear factors in 293 cells interacted with the RP-2 element, and that cAMP increased the binding activity of these nuclear factors to the RP-2 element. Furthermore, we demonstrated that cAMP enhanced the binding of nuclear factors derived from juxtaglomerular cells, the main production site of renin in the kidney, to the RP-2 element in vivo. These results suggest that the RP-2 element plays an important role in the cAMP-mediated regulation of Ren-1C gene transcription through the proximal promoter.