1
|
Min J, Zeng T, Roux M, Lazar D, Chen L, Tudzarova S. The Role of HIF1α-PFKFB3 Pathway in Diabetic Retinopathy. J Clin Endocrinol Metab 2021; 106:2505-2519. [PMID: 34019671 PMCID: PMC8372643 DOI: 10.1210/clinem/dgab362] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Indexed: 12/13/2022]
Abstract
Diabetic retinopathy (DR) is the leading cause of blindness for adults in developed countries. Both microvasculopathy and neurodegeneration are implicated in mechanisms of DR development, with neuronal impairment preceding microvascular abnormalities, which is often underappreciated in the clinic. Most current therapeutic strategies, including anti-vascular endothelial growth factor (anti-VEGF)-antibodies, aim at treating the advanced stages (diabetic macular edema and proliferative diabetic retinopathy) and fail to target the neuronal deterioration. Hence, new therapeutic approach(es) intended to address both vascular and neuronal impairment are urgently needed. The hypoxia-inducible factor 1α (HIF1α)-6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) pathway is critically implicated in the islet pathology of diabetes. Recent evidence highlighted the pathway relevance for pathologic angiogenesis and neurodegeneration, two key aspects in DR. PFKFB3 is key to the sprouting angiogenesis, along with VEGF, by determining the endothelial tip-cell competition. Also, PFKFB3-driven glycolysis compromises the antioxidative capacity of neurons leading to neuronal loss and reactive gliosis. Therefore, the HIF1α-PFKFB3 signaling pathway is unique as being a pervasive pathological component across multiple cell types in the retina in the early as well as late stages of DR. A metabolic point-of-intervention based on HIF1α-PFKFB3 targeting thus deserves further consideration in DR.
Collapse
Affiliation(s)
- Jie Min
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Larry L. Hillblom Islet Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Tianshu Zeng
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Margaretha Roux
- Groote Schuur and Red Cross Children’s Hospital, University of Cape Town, South Africa
| | - David Lazar
- Lazar Retina Ophthalmology, Los Angeles, CA, USA
| | - Lulu Chen
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Lulu Chen, PhD, Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Ave, Wuhan, Hubei, 430022, China.
| | - Slavica Tudzarova
- Larry L. Hillblom Islet Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Correspondence: Slavica Tudzarova, PhD, Larry Hillblom Islet Research Center, University of California Los Angeles, 10833 Le Conte Ave, CHS 33-165, Los Angeles, CA 90095, USA.
| |
Collapse
|
2
|
Miller WP, Sunilkumar S, Dennis MD. The stress response protein REDD1 as a causal factor for oxidative stress in diabetic retinopathy. Free Radic Biol Med 2021; 165:127-136. [PMID: 33524531 PMCID: PMC7956244 DOI: 10.1016/j.freeradbiomed.2021.01.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 12/12/2022]
Abstract
Diabetic Retinopathy (DR) is a major cause of visual dysfunction, yet much remains unknown regarding the specific molecular events that contribute to diabetes-induced retinal pathophysiology. Herein, we review the impact of oxidative stress on DR, and explore evidence that supports a key role for the stress response protein regulated in development and DNA damage (REDD1) in the development of diabetes-induced oxidative stress and functional defects in vision. It is well established that REDD1 mediates the cellular response to a number of diverse stressors through repression of the central metabolic regulator known as mechanistic target of rapamycin complex 1 (mTORC1). A growing body of evidence also supports that REDD1 acts independent of mTORC1 to promote oxidative stress by both enhancing the production of reactive oxygen species and suppressing the antioxidant response. Collectively, there is strong preclinical data to support a key role for REDD1 in the development and progression of retinal complications caused by diabetes. Furthermore, early proof-of-concept clinical trials have found a degree of success in combating ischemic retinal disease through intravitreal delivery of an siRNA targeting the REDD1 mRNA. Overall, REDD1-associated signaling represents an intriguing target for novel clinical therapies that go beyond addressing the symptoms of diabetes by targeting the underlying molecular mechanisms that contribute to DR.
Collapse
Affiliation(s)
- William P Miller
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Siddharth Sunilkumar
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA; Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, 17033, USA.
| |
Collapse
|
3
|
Zhang P, Li T, Wu X, Nice EC, Huang C, Zhang Y. Oxidative stress and diabetes: antioxidative strategies. Front Med 2020; 14:583-600. [PMID: 32248333 DOI: 10.1007/s11684-019-0729-1] [Citation(s) in RCA: 220] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 10/29/2019] [Indexed: 12/20/2022]
Abstract
Diabetes mellitus is one of the major public health problems worldwide. Considerable recent evidence suggests that the cellular reduction-oxidation (redox) imbalance leads to oxidative stress and subsequent occurrence and development of diabetes and related complications by regulating certain signaling pathways involved in β-cell dysfunction and insulin resistance. Reactive oxide species (ROS) can also directly oxidize certain proteins (defined as redox modification) involved in the diabetes process. There are a number of potential problems in the clinical application of antioxidant therapies including poor solubility, storage instability and nonselectivity of antioxidants. Novel antioxidant delivery systems may overcome pharmacokinetic and stability problem and improve the selectivity of scavenging ROS. We have therefore focused on the role of oxidative stress and antioxidative therapies in the pathogenesis of diabetes mellitus. Precise therapeutic interventions against ROS and downstream targets are now possible and provide important new insights into the treatment of diabetes.
Collapse
Affiliation(s)
- Pengju Zhang
- Department of Pharmacology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China
| | - Tao Li
- Department of Pharmacology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China
| | - Xingyun Wu
- Department of Pharmacology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China
| | - Edouard C Nice
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Canhua Huang
- Department of Pharmacology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China.
| | - Yuanyuan Zhang
- Department of Pharmacology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China.
| |
Collapse
|
4
|
Park HJ, Shin KC, Yoou SK, Kang M, Kim JG, Sung DJ, Yu W, Lee Y, Kim SH, Bae YM, Park SW. Hydrogen peroxide constricts rat arteries by activating Na +-permeable and Ca 2+-permeable cation channels. Free Radic Res 2018; 53:94-103. [PMID: 30526150 DOI: 10.1080/10715762.2018.1556394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Oxidative stress is associated with many cardiovascular diseases, such as hypertension and arteriosclerosis. Oxidative stress reportedly activates the L-type voltage-gated calcium channel (VDCCL) and elevates [Ca2+]i in many cells. However, how oxidative stress activates VDCCL under clinical setting and the consequence for arteries are unclear. Here, we examined the hypothesis that hydrogen peroxide (H2O2) regulates membrane potential (Em) by altering Na+ influx through cation channels, which consequently activates VDCCL to induce vasoconstriction in rat mesenteric arteries. To measure the tone of the endothelium-denuded arteries, a conventional isometric organ chamber was used. Membrane currents and Em were recorded by the patch-clamp technique. [Ca2+]i and [Na+]i were measured with microfluorometry using Fura2-AM and SBFI-AM, respectively. We found that H2O2 (10 and 100 µM) increased arterial contraction, and nifedipine blocked the effects of H2O2 on isometric contraction. H2O2 increased [Ca2+]i as well as [Na+]i, and depolarised Em. Gd3+ (1 µM) blocked all these H2O2-induced effects including Em depolarisation and increases in [Ca2+]i and [Na+]i. Although both nifedipine (30 nM) and low Na+ bath solution completely prevented the H2O2-induced increase in [Na+], they only partly inhibited the H2O2-induced effects on [Ca2+]i and Em. Taken together, the results suggested that H2O2 constricts rat arteries by causing Em depolarisation and VDCCL activation through activating Gd3+-and nifedipine-sensitive, Na+-permeable channels as well as Gd3+-sensitive Ca2+-permeable cation channels. We suggest that unidentified Na+-permeable cation channels as well as Ca2+-permeable cation channels may function as important mediators for oxidative stress-induced vascular dysfunction.
Collapse
Affiliation(s)
- Hyun Ji Park
- a Department of Physiology, KU Open Innovation Center , Research Institute of Medical Science, Konkuk University School of Medicine , Chungju , Republic of Korea
| | - Kyung Chul Shin
- a Department of Physiology, KU Open Innovation Center , Research Institute of Medical Science, Konkuk University School of Medicine , Chungju , Republic of Korea
| | - Soon-Kyu Yoou
- b Department of Emergency Medical Services , Eulji University , Seongnam , Republic of Korea
| | - Myeongsin Kang
- b Department of Emergency Medical Services , Eulji University , Seongnam , Republic of Korea
| | - Jae Gon Kim
- a Department of Physiology, KU Open Innovation Center , Research Institute of Medical Science, Konkuk University School of Medicine , Chungju , Republic of Korea
| | - Dong Jun Sung
- c Division of Sport and Health Science, College of Biomedical and Health Science , Konkuk University , Chungju , Republic of Korea
| | - Wonjong Yu
- d Department of Physical Therapy , Eulji University , Eulji , Republic of Korea
| | - Youngjin Lee
- e Department of Radiological Science , Gachon University , Yeonsu-gu , Republic of Korea
| | - Sung Hea Kim
- f Department of Cardiology , Konkuk University School of Medicine , Seoul , Republic of Korea
| | - Young Min Bae
- a Department of Physiology, KU Open Innovation Center , Research Institute of Medical Science, Konkuk University School of Medicine , Chungju , Republic of Korea
| | - Sang Woong Park
- b Department of Emergency Medical Services , Eulji University , Seongnam , Republic of Korea
| |
Collapse
|
5
|
The Oxidative Stress and Mitochondrial Dysfunction during the Pathogenesis of Diabetic Retinopathy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:3420187. [PMID: 30254714 PMCID: PMC6145164 DOI: 10.1155/2018/3420187] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/27/2018] [Accepted: 08/14/2018] [Indexed: 12/14/2022]
Abstract
Diabetic retinopathy is one of the most serious microvascular complications induced by hyperglycemia via five major pathways, including polyol, hexosamine, protein kinase C, and angiotensin II pathways and the accumulation of advanced glycation end products. The hyperglycemia-induced overproduction of reactive oxygen species (ROS) induces local inflammation, mitochondrial dysfunction, microvascular dysfunction, and cell apoptosis. The accumulation of ROS, local inflammation, and cell death are tightly linked and considerably affect all phases of diabetic retinopathy pathogenesis. Furthermore, microvascular dysfunction induces ischemia and local inflammation, leading to neovascularization, macular edema, and neurodysfunction, ultimately leading to long-term blindness. Therefore, it is crucial to understand and elucidate the detailed mechanisms underlying the development of diabetic retinopathy. In this review, we summarized the existing knowledge about the pathogenesis and current strategies for the treatment of diabetic retinopathy, and we believe this systematization will help and support further research in this area.
Collapse
|
6
|
Temporal diabetes-induced biochemical changes in distinctive layers of mouse retina. Sci Rep 2018; 8:1096. [PMID: 29348593 PMCID: PMC5773523 DOI: 10.1038/s41598-018-19425-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 11/20/2017] [Indexed: 02/08/2023] Open
Abstract
To discover the mechanisms underlying the progression of diabetic retinopathy (DR), a more comprehensive understanding of the biomolecular processes in individual retinal cells subjected to hyperglycemia is required. Despite extensive studies, the changes in the biochemistry of retinal layers during the development of DR are not well known. In this study, we aimed to determine a more detailed understanding of the natural history of DR in Akita/+ (type 1 diabetes model) male mice with different duration of diabetes. Employing label-free spatially resolved Fourier transform infrared (FT-IR) chemical imaging engaged with multivariate analysis enabled us to identify temporal-dependent reproducible biomarkers of the individual retinal layers from mice with 6 weeks,12 weeks, 6 months, and 10 months of age. We report, for the first time, the nature of the biochemical alterations over time in the biochemistry of distinctive retinal layers namely photoreceptor retinal layer (PRL), inner nuclear layer (INL), and plexiform layers (OPL, IPL). Moreover, we present the molecular factors associated with the changes in the protein structure and cellular lipids of retinal layers induced by different duration of diabetes. Our paradigm provides a new conceptual framework for a better understanding of the temporal cellular changes underlying the progression of DR.
Collapse
|
7
|
Ruia S, Saxena S, Prasad S, Sharma SR, Akduman L, Khanna VK. Correlation of biomarkers thiobarbituric acid reactive substance, nitric oxide and central subfield and cube average thickness in diabetic retinopathy: a cross-sectional study. Int J Retina Vitreous 2016; 2:8. [PMID: 27847626 PMCID: PMC5088447 DOI: 10.1186/s40942-016-0033-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/26/2016] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND To evaluate the role of thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) as biochemical biomarkers and central subfield (CST) and cube average thickness (CAT) as biomarkers for medical imaging in diabetic retinopathy. METHODS Forty consecutive cases of diabetic retinopathy and 20 healthy controls were included. Cases were divided into two groups: non proliferative diabetic retinopathy (n = 20) and proliferative diabetic retinopathy (n = 20) according to ETDRS classification. LogMAR visual acuity was documented. Plasma levels of TBARS, NO and glycated hemoglobin (HbA1c) were measured using standard protocol. CST and CAT were analyzed on spectral domain optical coherence tomography. Data was analyzed statistically. RESULTS Increased severity of diabetic retinopathy was associated with an increase in plasma levels of TBARS (F = 10.92; p < 0.001), NO (F = 21.8; p < 0.001) and HbA1c (F = 5.87; p = 0.001). Increase in CST (F = 61.51; p < 0.001) and CAT (F = 60.84; p < 0.001) was also found to be associated with increased severity of diabetic retinopathy. Pearson's correlation analysis revealed a positive correlation of TBARS with CST (r = 0.29; p = 0.038) and CAT (r = 0.31; p = 0.04). A positive correlation of NO with CST (r = 0.27; p = 0.03) and CAT (r = 0.7; p = 0.001) was also observed. On univariate analysis with logMAR visual acuity as dependent variable, a significant increase in visual acuity was observed with increase in independent variables TBARS (B = 0.22; p = 0.004), NO (B = 0.006; p < 0.001), CST (B = 0.005; p < 0.001) and CAT (B = 0.005; p < 0.001). On multivariate linear regression analysis with logMAR visual acuity as dependent variable and adjusting for other factors like duration of diabetes and HbA1c, it was observed that increase in independent variables TBARS (B = 0.07), NO (B = 0.001) and CST (B = 0.004) independently predict increase in logMAR visual acuity (p < 0.001). CONCLUSION Thiobarbituric acid reactive substance and nitric oxide serve as potential biochemical markers whereas central subfield and cube average thickness serve as potential biomarkers for medical imaging for severity of diabetic retinopathy. In a clinical retinal setting, CAT and CST will help in early recognition of increase in severity of diabetic retinopathy.
Collapse
Affiliation(s)
- Surabhi Ruia
- Department of Ophthalmology, King George’s Medical University, Lucknow, India
| | - Sandeep Saxena
- Department of Ophthalmology, King George’s Medical University, Lucknow, India
| | - S. Prasad
- Department of Community Medicine, King George’s Medical University, Lucknow, India
| | - Shashi R. Sharma
- Department of Ophthalmology, King George’s Medical University, Lucknow, India
| | - Levent Akduman
- Department of Ophthalmology, Saint Louis University Eye Institute, Saint Louis University, Saint Louis, MO USA
| | - Vinay K. Khanna
- Developmental Toxicology Division, Indian Institute of Toxicology Research, Lucknow, India
| |
Collapse
|
8
|
Oxidative stress mediates the conversion of endothelial cells into myofibroblasts via a TGF-β1 and TGF-β2-dependent pathway. J Transl Med 2014; 94:1068-82. [PMID: 25068653 DOI: 10.1038/labinvest.2014.100] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 12/31/2022] Open
Abstract
During the pathogenesis of systemic inflammation, reactive oxygen species (ROS) circulate in the bloodstream and interact with endothelial cells (ECs), increasing intracellular oxidative stress. Although endothelial dysfunction is crucial in the pathogenesis of systemic inflammation, little is known about the effects of oxidative stress on endothelial dysfunction. Oxidative stress induces several functions, including cellular transformation. A singular process of cell conversion is tendothelial-to-mesenchymal transition, in which ECs become myofibroblasts, thus losing their endothelial properties and gaining fibrotic behavior. However, the participation of oxidative stress as an inductor of conversion of ECs into myofibroblasts is not known. Thus, we studied the role played by oxidative stress in this conversion and investigated the underlying mechanism. Our results show that oxidative stress induces conversion of ECs into myofibroblasts through decreasing the levels of endothelial markers and increasing those of fibrotic and ECM proteins. The underlying mechanism depends on the ALK5/Smad3/NF-κB pathway. Oxidative stress induces the expression and secretion of TGF-β1 and TGF-β2 and p38 MAPK phosphorylation. Downregulation of TGF-β1 and TGF-β2 by siRNA technology abolished the H2O2-induced conversion. To our knowledge, this is the first report showing that oxidative stress is able to induce conversion of ECs into myofibroblasts via TGF-β secretion, emerging as a source for oxidative stress-based vascular dysfunction. Thus, oxidative stress emerges as a decisive factor in inducing conversion of ECs into myofibroblasts through a TGF-β-dependent mechanism, changing the ECs protein expression profile, and converting normal ECs into pathological ones. This information will be useful in designing new and improved therapeutic strategies against oxidative stress-mediated systemic inflammatory diseases.
Collapse
|
9
|
Hussain N, Irshad F, Jabeen Z, Shamsi IH, Li Z, Jiang L. Biosynthesis, structural, and functional attributes of tocopherols in planta; past, present, and future perspectives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:6137-49. [PMID: 23713813 DOI: 10.1021/jf4010302] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Tocopherols are lipophilic molecules, ubiquitously synthesized in all photosynthetic organisms. Being a group of vitamin E compounds, they play an essential role in human nutrition and health. Despite their structural and functional attributes as important antioxidants in plants, it would be misleading to ignore the potential roles of tocopherols beyond their antioxidant properties in planta. Detailed characterization of mutants and transgenic plants, including Arabidopsis (vte1, vte2, vte4, and so on), maize (sxd1) mutants, and transgenic potato and tobacco lines altered in tocopherol biosynthesis and contents, has led to surprising outcomes regarding the additional functions of these molecules. Thus, the aim of this review is to highlight the past and present research findings on tocopherols' structural, biosynthesis, and functional properties in plants. Special emphasis is given to their suggested functions in planta, such as cell signaling, hormonal interactions, and coordinated response of tocopherols to other antioxidants under abiotic stresses. Moreover, some important questions about possible new functions of tocopherols will be discussed as future prospects to stimulate further research.
Collapse
Affiliation(s)
- Nazim Hussain
- Key Laboratory of Crop Germplasm Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, 866 Yu-Hang-Tang Road, Hangzhou 310058, People's Republic of China
| | | | | | | | | | | |
Collapse
|
10
|
Lirangi M, Meydani M, Zingg JM, Azzi A. α-Tocopheryl-phosphate regulation of gene expression in preadipocytes and adipocytes. Biofactors 2012; 38:450-7. [PMID: 23047815 DOI: 10.1002/biof.1051] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/31/2012] [Indexed: 01/18/2023]
Abstract
A correct function of adipocytes in connection with cellular fatty acid loading and release is a vital aspect of energy homeostasis; dysregulation of these reactions can result in obesity and type 2 diabetes mellitus. In addition, adipocytes have been proposed to play a major role in preventing lipotoxicity by removing excess fatty acids from the circulation and converting them into triglycerides and thus decreasing the exposure of other cells to their potentially harmful effects. We report here that the addition of α-tocopheryl phosphate (but not α-tocopherol) to NIH3T3-L1 preadipocytes transcriptionally activates a set of genes TRB3 (Tribbles Homolog 3), Sestrin-2 (SESN2), and Insulin-Induced Gene 1 (INSIG1)] potentially preventing fat accumulation in these cells. In contrast, in differentiated adipocytes, α-tocopheryl phosphate is responsible for the transcriptional inhibition of the same genes, possibly facilitating fat uptake and storage. In conclusion, it appears that in proliferating preadipocytes α-tocopheryl phosphate foils fat accumulation, whereas in adipocytes it enhances it. These processes may be relevant in the regulation of excess fat accumulation and in prevention of lipotoxicity.
Collapse
Affiliation(s)
- Melania Lirangi
- Laboratorio di Biochimica, Chimica e Nutrizione, Università Campus Bio-Medico, Roma, Italy
| | | | | | | |
Collapse
|
11
|
Hajiani M, Razi F, Golestani A, Frouzandeh M, Owji AA, Khaghani S, Ghannadian N, Shariftabrizi A, Pasalar P. Time- and dose-dependent differential regulation of copper-zinc superoxide dismutase and manganese superoxide dismutase enzymatic activity and mRNA level by vitamin E in rat blood cells. Redox Rep 2012; 17:101-7. [PMID: 22732938 PMCID: PMC6837400 DOI: 10.1179/1351000212y.0000000008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Vitamin E is the most important lipid-soluble antioxidant. Recently, it has been proposed as a gene regulator, and its gene modulation effects have been observed at different levels of gene expression and cell signaling. This study was performed to investigate the effects of vitamin E on the activity and expression of the most important endogenous antioxidant enzyme, superoxide dismutase (SOD), in rat plasma. METHODS Twenty-eight male Sprauge-Dawley rats were divided into four groups: control group and three dosing groups. The control group received the vehicle (liquid paraffin), and the dosing groups received twice-weekly intraperitoneal injections of 10, 30, and 100 mg/kg of vitamin E ((±)-α-Tocopherol) for 6 weeks. Quantitative real-time reverse transcription-polymerase chain reaction and enzyme assays were used to assess the levels of Cu/Zn-SOD and Mn-SOD mRNA and enzyme activity levels in blood cells at 0, 2, 4, and 6 weeks following vitamin E administration. Catalase enzyme activity and total antioxidant capacity were also assessed in plasma at the same time intervals. RESULTS Mn-SOD activity was significantly increased in the 100 and 30 mg/kg dosing groups after 4 and 6 weeks, with corresponding significant increase in their mRNA levels. Cu/Zn-SOD activity was not significantly changed in response to vitamin E administration at any time points, whereas Cu/Zn-SOD mRNA levels were significantly increased after longer time points with high doses (30 and 100 mg/kg) of vitamin E. Catalase enzyme activity was transiently but significantly increased after 4 weeks of vitamin E treatment in 30 and 100 mg/kg dosing groups. Total antioxidant status was significantly increased after 4 and 6 weeks in the 100 mg/kg dosing group. CONCLUSION Only the chronic administration of higher doses of alpha-tocopherol is associated with the increased activity and expression of Mn-SOD in rats. Cu/Zn-SOD activity and expression does not dramatically change in response to vitamin E.
Collapse
Affiliation(s)
- Maliheh Hajiani
- Department of BiochemistryTehran University of Medical Sciences, Tehran, Iran
| | - Farideh Razi
- Endocrinology and Metabolism CenterShariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mehdi Frouzandeh
- Department of BiotechnologyTabiat Moddares University, Tehran, Iran
| | - Ali Akbar Owji
- Department of BiochemistryShiraz University of Medical Sciences, Shiraz, Iran
| | - Shahnaz Khaghani
- Department of BiochemistryTehran University of Medical Sciences, Tehran, Iran
| | - Naghmeh Ghannadian
- Students' Scientific Research Center (SSRC)Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Shariftabrizi
- Department of BiochemistryTehran University of Medical Sciences, Tehran, Iran
| | - Parvin Pasalar
- Department of BiochemistryTehran University of Medical Sciences, Tehran, Iran
- Center for Research on Occupational Diseases (GRAD)Tehran, Iran
| |
Collapse
|
12
|
Lee SG, Lee CG, Yun IH, Hur DY, Yang JW, Kim HW. Effect of lipoic acid on expression of angiogenic factors in diabetic rat retina. Clin Exp Ophthalmol 2011; 40:e47-57. [PMID: 21902786 DOI: 10.1111/j.1442-9071.2011.02695.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND This study evaluated the effect of a lipoic acid on reactive oxygen species formation and the simultaneous changes of several angiogenic factors in an experimental diabetic rat retina. METHODS Diabetes was induced chemically by intraperitoneal injection of streptozotocin in 30 Sprague-Dawley rats. After inducing diabetes, lipoic acid (10 mg/kg) was administered to 10 rats orally. The rats were divided into normal, diabetes mellitus, and lipoic acid-treated groups (each group n = 10). The eyeballs were harvested 8 weeks after inducing diabetes. The expression of vascular endothelial growth factor, erythropoietin, angiopoietin 1 and 2 and NADPH oxidase was examined in the rat retina using reverse transcription-polymerase chain reaction and Western blot. Superoxide formation was examined using dihydroethidium stain. RESULTS Dihydroethidium analyses showed increased superoxide formation in the retina of the diabetic group. The superoxide formation was suppressed with lipoic acid treatment. Western blot analysis showed that NADPH oxidase was decreased in the diabetic group and returned to normal level in the lipoic acid-treated group. Treatment with lipoic acid blocked hyperglycaemia induced increases of vascular endothelial growth factor, angiopoietin 2 and erythropoietin shown by reverse transcription-polymerase chain reaction and Western blot analysis. CONCLUSIONS Lipoic acid treatment suppressed expression of vascular endothelial growth factor, angiopoietin 2 and erythropoietin via blockade of superoxide formation. Antioxidant treatment is suspected to have an antiangiogenic effect.
Collapse
Affiliation(s)
- Sul Gee Lee
- Department of Ophthalmology, College of Medicine, Inje University, Busan Paik Hospital, Busan, Korea
| | | | | | | | | | | |
Collapse
|
13
|
Nuñez-Villena F, Becerra A, Echeverría C, Briceño N, Porras O, Armisén R, Varela D, Montorfano I, Sarmiento D, Simon F. Increased expression of the transient receptor potential melastatin 7 channel is critically involved in lipopolysaccharide-induced reactive oxygen species-mediated neuronal death. Antioxid Redox Signal 2011; 15:2425-38. [PMID: 21539414 DOI: 10.1089/ars.2010.3825] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AIMS To assess the mechanisms involved in lipopolysaccharide (LPS)-induced neuronal cell death, we examined the cellular consequences of LPS exposure in differentiated PC12 neurons and primary hippocampal neurons. RESULTS Our data show that LPS is able to induce PC12 neuronal cell death without the participation of glial cells. Neuronal cell death was mediated by an increase in cellular reactive oxygen species (ROS) levels. Considering the prevalent role of specific ion channels in mediating the deleterious effect of ROS, we assessed their contribution to this process. Neurons exposed to LPS showed a significant intracellular Ca(2+) overload, and nonselective cationic channel blockers inhibited LPS-induced neuronal death. In particular, we observed that both LPS and hydrogen peroxide exposure strongly increased the expression of the transient receptor protein melastatin 7 (TRPM7), which is an ion channel directly implicated in neuronal cell death. Further, both LPS-induced TRPM7 overexpression and LPS-induced neuronal cell death were decreased with dithiothreitol, dipheniliodonium, and apocynin. Finally, knockdown of TRPM7 expression using small interference RNA technology protected primary hippocampal neurons and differentiated PC12 neurons from the LPS challenge. INNOVATION This is the first report showing that TRPM7 is a key protein involved in neuronal death after LPS challenge. CONCLUSION We conclude that LPS promotes an abnormal ROS-dependent TRPM7 overexpression, which plays a crucial role in pathologic events, thus leading to neuronal dysfunction and death.
Collapse
Affiliation(s)
- Felipe Nuñez-Villena
- Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Miriyala S, Holley AK, St Clair DK. Mitochondrial superoxide dismutase--signals of distinction. Anticancer Agents Med Chem 2011; 11:181-90. [PMID: 21355846 DOI: 10.2174/187152011795255920] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/17/2011] [Indexed: 11/22/2022]
Abstract
Mitochondrial superoxide dismutase (MnSOD) neutralizes the highly reactive superoxide radical (O(2)(˙-)), the first member in a plethora of mitochondrial reactive oxygen species (ROS). Over the past decades, research has extended the prevailing view of mitochondrion well beyond the generation of cellular energy to include its importance in cell survival and cell death. In the normal state of a cell, endogenous antioxidant enzyme systems maintain the level of reactive oxygen species generated by the mitochondrial respiratory chain. Mammalian mitochondria are important to the production of reactive oxygen species, which underlie oxidative damage in many pathological conditions and contribute to retrograde redox signaling from the organelle to the cytosol and nucleus. Mitochondria are further implicated in various metabolic and aging-related diseases that are now postulated to be caused by misregulation of physiological systems rather than pure accumulation of oxidative damage. Thus, the signaling mechanisms within mitochondria, and between the organelle and its environment, have gained interest as potential drug targets. Here, we discuss redox events in mitochondria that lead to retrograde signaling, the role of redox events in disease, and their potential to serve as therapeutic targets.
Collapse
Affiliation(s)
- Sumitra Miriyala
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
| | | | | |
Collapse
|
15
|
Campbell SE, Rudder B, Phillips RB, Whaley SG, Stimmel JB, Leesnitzer LM, Lightner J, Dessus-Babus S, Duffourc M, Stone WL, Menter DG, Newman RA, Yang P, Aggarwal BB, Krishnan K. γ-Tocotrienol induces growth arrest through a novel pathway with TGFβ2 in prostate cancer. Free Radic Biol Med 2011; 50:1344-54. [PMID: 21335085 DOI: 10.1016/j.freeradbiomed.2011.02.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 02/07/2011] [Accepted: 02/09/2011] [Indexed: 12/24/2022]
Abstract
Regions along the Mediterranean and in southern Asia have lower prostate cancer incidence compared to the rest of the world. It has been hypothesized that one of the potential contributing factors for this low incidence includes a higher intake of tocotrienols. Here we examine the potential of γ-tocotrienol (GT3) to reduce prostate cancer proliferation and focus on elucidating pathways by which GT3 could exert a growth-inhibitory effect on prostate cancer cells. We find that the γ and δ isoforms of tocotrienol are more effective at inhibiting the growth of prostate cancer cell lines (PC-3 and LNCaP) compared with the γ and δ forms of tocopherol. Knockout of PPAR-γ and GT3 treatment show inhibition of prostate cancer cell growth, through a partially PPAR-γ-dependent mechanism. GT3 treatment increases the levels of the 15-lipoxygenase-2 enzyme, which is responsible for the conversion of arachidonic acid to the PPAR-γ-activating ligand 15-S-hydroxyeicosatrienoic acid. In addition, the latent precursor and the mature forms of TGFβ2 are down-regulated after treatment with GT3, with concomitant disruptions in TGFβ receptor I, SMAD-2, p38, and NF-κB signaling.
Collapse
Affiliation(s)
- Sharon E Campbell
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Okoh V, Deoraj A, Roy D. Estrogen-induced reactive oxygen species-mediated signalings contribute to breast cancer. Biochim Biophys Acta Rev Cancer 2010; 1815:115-33. [PMID: 21036202 DOI: 10.1016/j.bbcan.2010.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/12/2010] [Accepted: 10/14/2010] [Indexed: 01/01/2023]
Abstract
Elevated lifetime estrogen exposure is a major risk factor for breast cancer. Recent advances in the understanding of breast carcinogenesis clearly indicate that induction of estrogen receptor (ER) mediated signaling is not sufficient for the development of breast cancer. The underlying mechanisms of breast susceptibility to estrogen's carcinogenic effect remain elusive. Physiologically achievable concentrations of estrogen or estrogen metabolites have been shown to generate reactive oxygen species (ROS). Recent data implicated that these ROS induced DNA synthesis, increased phosphorylation of kinases, and activated transcription factors, e.g., AP-1, NRF1, E2F, NF-kB and CREB of non-genomic pathways which are responsive to both oxidants and estrogen. Estrogen-induced ROS by increasing genomic instability and by transducing signal through influencing redox sensitive transcription factors play important role (s) in cell transformation, cell cycle, migration and invasion of the breast cancer. The present review discusses emerging data in support of the role of estrogen induced ROS-mediated signaling pathways which may contribute in the development of breast cancer. It is envisioned that estrogen induced ROS mediated signaling is a key complementary mechanism that drives the carcinogenesis process. ROS mediated signaling however occurs in the context of other estrogen induced processes such as ER-mediated signaling and estrogen reactive metabolite-associated genotoxicity. Importantly, estrogen-induced ROS can function as independent reversible modifiers of phosphatases and activate kinases to trigger the transcription factors of downstream target genes which participate in cancer progression.
Collapse
Affiliation(s)
- Victor Okoh
- Department of Environmental and Occupational Health, Florida International University, Miami, FL, USA
| | | | | |
Collapse
|
17
|
Al-Shabrawey M, Smith S. Prediction of diabetic retinopathy: role of oxidative stress and relevance of apoptotic biomarkers. EPMA J 2010; 1:56-72. [PMID: 23199041 PMCID: PMC3405307 DOI: 10.1007/s13167-010-0002-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Accepted: 01/25/2010] [Indexed: 12/15/2022]
Abstract
Diabetic retinopathy (DR) is the foremost cause of blindness in working-aged worldwide; it is characterized by vascular and neuronal degeneration. Features of DR include leukocyte adhesion, increased vascular permeability, neovascularization and neuronal cell death. Early diagnosis and intervention are important to prevent or at least ameliorate the development of DR. Recent reports indicate that pathophysiological mechanisms leading to diabetic retinopathy include oxidative stress and retinal cell death cascades. Circulating biomarkers of oxidative stress such as malondialdehyde (MDA), thiobarbituric acid reacting substances (TBARS), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl, 8-hydroxydeoxyguanosin (8-OHdG), nitrotyrosine, and F(2) isoprostanes and pro-apoptosis molecules (caspase-3, Fas, and Bax) are associated with increased susceptibility to develop DR in diabetic subjects. Thus, identification of oxidative stress and cell death biomarkers in diabetic patients could be in favor of predicting, diagnosis, and prevention of DR, and to target for novel therapeutic interventions.
Collapse
Affiliation(s)
- Mohamed Al-Shabrawey
- Oral Biology and Anatomy, School of Dentistry, Medical College of Georgia, Augusta, GA 30912 USA
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, Augusta, GA 30912 USA
- Opthalmology, King Saud University, Riyadh, Saudi Arabia
| | - Sylvia Smith
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, Augusta, GA 30912 USA
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912 USA
| |
Collapse
|
18
|
Cha JD, Moon SE, Kim HY, Cha IH, Lee KY. Essential Oil of Artemisia Capillaris Induces Apoptosis in KB Cells via Mitochondrial Stress and Caspase Activation Mediated by MAPK-Stimulated Signaling Pathway. J Food Sci 2009; 74:T75-81. [DOI: 10.1111/j.1750-3841.2009.01355.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
19
|
Madsen-Bouterse SA, Kowluru RA. Oxidative stress and diabetic retinopathy: pathophysiological mechanisms and treatment perspectives. Rev Endocr Metab Disord 2008; 9:315-27. [PMID: 18654858 DOI: 10.1007/s11154-008-9090-4] [Citation(s) in RCA: 201] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Retinopathy is one of the most severe ocular complications of diabetes and is a leading cause of acquired blindness in young adults. The cellular components of the retina are highly coordinated but very susceptible to the hyperglycemic environment. The microvasculature of the retina responds to hyperglycemic milieu through a number of biochemical changes, including increased oxidative stress and polyol pathway, PKC activation and advanced glycation end product formation. Oxidative stress is considered as one of the crucial contributors in the pathogenesis of diabetic retinopathy, but oxidative stress appears to be highly interrelated with other biochemical imbalances that lead to structural and functional changes and accelerated loss of capillary cells in the retinal microvasculature and, ultimately, pathological evidence of the disease. One such potential connection that links oxidative stress to metabolic alterations is gyceraldehyde-3-phosphate dehydrogenase whose activity is impaired in diabetes, and that results in activation of other major pathways implicated in the pathogenesis of diabetic retinopathy. Alterations associated with oxidative stress offer many potential therapeutic targets making this an area of great interest to the development of safe and effective treatments for diabetic retinopathy. Animal models of diabetic retinopathy have shown beneficial effects of antioxidants on the development of retinopathy, but clinical trials (though very limited in numbers) have provided somewhat ambiguous results. Although antioxidants are being used for other chronic diseases, controlled clinical trials are warranted to investigate potential beneficial effects of antioxidants in the development of retinopathy in diabetic patients.
Collapse
Affiliation(s)
- Sally A Madsen-Bouterse
- K-404, Kresge Eye Institute, Wayne State University, 4717 St. Antoine, Detroit, MI, 48201, USA
| | | |
Collapse
|
20
|
McIntyre BS, Briski KP, Gapor A, Sylvester PW. Antiproliferative and Apoptotic Effects of Tocopherols and Tocotrienols on Preneoplastic and Neoplastic Mouse Mammary Epithelial Cells. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1525-1373.2000.22434.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
21
|
Kowluru RA, Chan PS. Oxidative stress and diabetic retinopathy. EXPERIMENTAL DIABETES RESEARCH 2008; 2007:43603. [PMID: 17641741 PMCID: PMC1880867 DOI: 10.1155/2007/43603] [Citation(s) in RCA: 393] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Accepted: 02/08/2007] [Indexed: 12/11/2022]
Abstract
Oxygen metabolism is essential for sustaining aerobic life, and normal cellular homeostasis works on a fine balance between the formation and elimination of reactive oxygen species (ROS). Oxidative stress, a cytopathic consequence of excessive production of ROS and the suppression of ROS removal by antioxidant defense system, is implicated in the development of many diseases, including Alzheimer's disease, and diabetes and its complications. Retinopathy, a debilitating microvascular complication of diabetes, is the leading cause of acquired blindness in developed countries. Many diabetes-induced metabolic abnormalities are implicated in its development, and appear to be influenced by elevated oxidative stress; however the exact mechanism of its development remains elusive. Increased superoxide concentration is considered as a causal link between elevated glucose and the other metabolic abnormalities important in the pathogenesis of diabetic complications. Animal studies have shown that antioxidants have beneficial effects on the development of retinopathy, but the results from very limited clinical trials are somewhat ambiguous. Although antioxidants are being used for other chronic diseases, controlled clinical trials are warranted to investigate potential beneficial effects of antioxidants in the development of retinopathy in diabetic patients.
Collapse
Affiliation(s)
- Renu A Kowluru
- Kresge Eye Institute, Wayne State University, Detroit, MI 48201, USA.
| | | |
Collapse
|
22
|
Villacorta L, Azzi A, Zingg JM. Regulatory role of vitamins E and C on extracellular matrix components of the vascular system. Mol Aspects Med 2007; 28:507-37. [PMID: 17624419 DOI: 10.1016/j.mam.2007.05.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 05/17/2007] [Indexed: 12/14/2022]
Abstract
The protective effect of vitamins E (alpha-tocopherol) and C (L-ascorbic acid) in the prevention of cardiovascular disease (CVD) has been shown in a number of situations but a secure correlation is not universally accepted. Under certain conditions, both, L-ascorbic acid and alpha-tocopherol can exhibit antioxidant properties and thus may reduce the formation of oxidized small molecules, proteins and lipids, which are a possible cause of cellular de-regulation. However, non-antioxidant effects have also been suggested to play a role in the prevention of atherosclerosis. Vitamin E and C can modulate signal transduction and gene expression and thus affect many cellular reactions such as the proliferation of smooth muscle cells, the expression of cell adhesion and extracellular matrix molecules, the production of O(2)(-) by NADPH-oxidase, the aggregation of platelets and the inflammatory response. Vitamins E and C may modulate the extracellular matrix environment by affecting VSMC differentiation and the expression of connective tissue proteins involved in vascular remodeling as well as the maintenance of vascular wall integrity. This review summarizes individually the molecular activities of vitamins E and C on the cells within the connective tissue of the vasculature, which are centrally involved in the maintenance of an intact vascular wall as well as in the repair of atherosclerotic lesions during disease development.
Collapse
Affiliation(s)
- Luis Villacorta
- Cardiovascular Research Center, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | | | | |
Collapse
|
23
|
Chan PS, Kowluru RA. Role of retinal mitochondria in the development of diabetic retinopathy. EXPERT REVIEW OF OPHTHALMOLOGY 2007. [DOI: 10.1586/17469899.2.2.237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
24
|
Abstract
The endothelium is a complex organ system that controls the homeostasis of the vasculature by integrating signals between the vascular wall and the vessel lumen. Under physiological conditions, it maintains a normal vascular tone and blood fluidity by elaborating a variety of factors, such as nitric oxide, prostacyclin and endothelin. However, in pathological situations the endothelium can also modify its phenotype facilitating vasoconstriction, inflammation, and thrombotic events. These abnormal responses manifest in different clinical settings, such as hypercholesterolemia, hypertension, diabetes mellitus, and occur in the absence of any morphological change of the vessel. The etiology of these altered endothelial functions is multi-factorial, and the mechanisms underlying them are complex and not yet fully elucidated. Today, there is substantial evidence that many endothelial functions are sensitive to the presence of reactive oxygen species and subsequent oxidative stress. Here, I will review the increasing number of studies showing that exogenous antioxidants can modulate the endothelium-dependent vasodilation responses, the homeostatic endothelium-leukocyte interactions, the balance between pro- and anti-thrombotic properties, and the vascular apoptotic responses. Finally, the non-antioxidant activities of some antioxidant will also be described.
Collapse
Affiliation(s)
- Domenico Praticò
- The Center for Experimental Therapeutics, Department of Pharmacology, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA.
| |
Collapse
|
25
|
Sarangarajan R, Apte SP. Ocular Melanogenesis: The Role of Antioxidants. Ophthalmic Res 2004; 36:303-11. [PMID: 15627830 DOI: 10.1159/000081632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Indexed: 11/19/2022]
Abstract
Given the propensity of a large number of melanogenic pathways that can be modulated by cellular redox status, a causal role of the deficiency of ocular pigments such as melanin in the pathogenesis of age-related macular degeneration and evidence that melanin production does occur in the adult eye, it seems not improbable that antioxidants (or agents that modify cellular redox status) may have melanin stimulatory (or inhibitory) effects that are superimposible on their effects as mere free radical scavengers. More empirical studies are needed to investigate this phenomenon so that antioxidant therapy may prove more beneficial to patients with ocular degenerative diseases.
Collapse
Affiliation(s)
- Rangaprasad Sarangarajan
- Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences, Worcester, Mass., USA
| | | |
Collapse
|
26
|
Song HJ, Lee TS, Jeong JH, Min YS, Shin CY, Sohn UD. Hydrogen Peroxide-Induced Extracellular Signal-Regulated Kinase Activation in Cultured Feline Ileal Smooth Muscle Cells. J Pharmacol Exp Ther 2004; 312:391-8. [PMID: 15328380 DOI: 10.1124/jpet.104.074401] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
H(2)O(2) has been shown to act as a signaling molecule involved in many cellular functions such as apoptosis and proliferation. In the present study, we characterized the effects of H(2)O(2) on the activation of mitogen-activated protein (MAP) kinases and examined the factors involved in the process of extracellular signal-regulated kinase (ERK) activation by H(2)O(2) in ileal smooth muscle cells (ISMC). ISMC were cultured and exposed to H(2)O(2). Western blot analysis was performed with phosphospecific MAP kinase antibodies. Potent activation of ERK and moderate activation of stress-activated protein kinase/c-Jun NH(2)-terminal kinase occurred within 30 min of 1 mM H(2)O(2) treatment. However, p38 MAP kinase was not activated by H(2)O(2). The activation of ERK by H(2)O(2) was reduced by the mitogen-activated/ERK-activating kinase inhibitor PD98059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one], Ras inhibitor S-farnesylthiosalicylic acid, removal of extracellular Ca(2+), depletion of the intracellular Ca(2+) pool by thapsigargin, or pretreatment of ISMC with the calmodulin antagonist W-7. Also, H(2)O(2)-induced ERK activation was attenuated by a receptor tyrosine kinase inhibitor, tyrphostin 51, but not by down-regulation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate or by a PKC inhibitor, GF109203X [3-[1-(dimethylaminopropyl)indol-3-yl]-4-(indol-3-yl)maleimide hydrochloride]. Growth factor receptor antagonist suramin pretreatment inhibited H(2)O(2)-induced ERK activation, highlighting a role for growth factor receptors in this activation. Furthermore, the ERK activation by H(2)O(2) was blocked by pretreatment with either N-acetyl-cysteine, o-phenanthroline, or mannitol indicating that metal-catalyzed free radical formation may mediate the initiation of signal transduction by H(2)O(2). These data suggest that short-term stimulation with H(2)O(2) activates the signaling pathways of cell mitogenic effects which are thought to be a protective response against intestinal oxidative stress.
Collapse
Affiliation(s)
- Hyun Ju Song
- Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul 156-756 Korea, Republic of Korea
| | | | | | | | | | | |
Collapse
|
27
|
Abstract
Atherosclerosis and its complications such as coronary heart disease, myocardial infarction and stroke are the leading causes of death in the developed world. High blood pressure, diabetes, smoking and a diet high in cholesterol and lipids clearly increase the likelihood of premature atherosclerosis, albeit other factors, such as the individual genetic makeup, may play an additional role. Several epidemiological studies and intervention trials have been performed with vitamin E, and some of them showed that it prevents atherosclerosis. For a long time, vitamin E was assumed to act by decreasing the oxidation of LDL, a key step in atherosclerosis initiation. However, at the cellular level, vitamin E acts by inhibition of smooth muscle cell proliferation, platelet aggregation, monocyte adhesion, oxLDL uptake and cytokine production, all reactions implied in the progression of atherosclerosis. Recent research revealed that these effects are not the result of the antioxidant activity of vitamin E, but rather of precise molecular actions of this compound. It is assumed that specific interactions of vitamin E with enzymes and proteins are at the basis of its non-antioxidant effects. Vitamin E influences the activity of several enzymes (e.g. PKC, PP2A, COX-2, 5-lipooxygenase, nitric oxide synthase, NADPH-oxidase, superoxide dismutase, phopholipase A2) and modulates the expression of genes that are involved in atherosclerosis (e.g. scavenger receptors, integrins, selectins, cytokines, cyclins). These interactions promise to reveal the biological properties of vitamin E and allow designing better strategies for the protection against atherosclerosis progression.
Collapse
Affiliation(s)
- Adelina Munteanu
- Institute of Biochemistry and Molecular Biology, University of Bern, Bern, Switzerland
| | | | | |
Collapse
|
28
|
Schock BC, Van der Vliet A, Corbacho AM, Leonard SW, Finkelstein E, Valacchi G, Obermueller-Jevic U, Cross CE, Traber MG. Enhanced inflammatory responses in alpha-tocopherol transfer protein null mice. Arch Biochem Biophys 2004; 423:162-9. [PMID: 14871478 DOI: 10.1016/j.abb.2003.12.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Revised: 12/02/2003] [Indexed: 11/17/2022]
Abstract
The liver preferentially secretes alpha-tocopherol into plasma under the control of the hepatic alpha-tocopherol transfer protein (alpha-TTP). alpha-TTP-null mice (Ttpa(-/-) mice) are vitamin E deficient, therefore were used for investigations of in vivo responses to sub-normal tissue alpha-tocopherol concentrations during inflammation. Increased basal oxidative stress in Ttpa(-/-) mice was documented by increased plasma lipid peroxidation, and superoxide production by bone marrow-derived neutrophils stimulated in vitro with phorbol 12-myristate 13-acetate. Lipopolysaccharide (LPS) injected intraperitoneally induced increases in lung and liver HO-1 and iNOS, as well as plasma NO(x) in Ttpa(+/+) mice. LPS induced more modest increases in these markers in Ttpa(-/-) mice, while more marked increases in plasma IL-10 and lung lavage TNF alpha were observed. Taken together, these results demonstrate that alpha-tocopherol is important for proper modulation of inflammatory responses and that sub-optimal alpha-tocopherol concentrations may derange inflammatory-immune responses.
Collapse
Affiliation(s)
- Bettina C Schock
- Division of Pulmonary and Critical Care Medicine and Center for Comparative Respiratory Biology and Medicine, University of California School of Medicine, Davis, CA 95616, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Chuang LY, Guh JY, Liu SF, Hung MY, Liao TN, Chiang TA, Huang JS, Huang YL, Lin CF, Yang YL. Regulation of type II transforming-growth-factor-beta receptors by protein kinase C iota. Biochem J 2003; 375:385-93. [PMID: 12841849 PMCID: PMC1223681 DOI: 10.1042/bj20030522] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2003] [Revised: 06/16/2003] [Accepted: 07/04/2003] [Indexed: 11/17/2022]
Abstract
TGF-beta (transforming growth factor-beta) is implicated in the pathogenesis of diabetic nephropathy. We previously demonstrated that up-regulation of type II TGF-beta receptor (TbetaRII) induced by high glucose might contribute to distal tubular hypertrophy [Yang, Guh, Yang, Lai, Tsai, Hung, Chang and Chuang (1998) J. Am. Soc. Nephrol. 9, 182-193]. We have elucidated the mechanism by using cultured Madin-Darby canine kidney cells. Enhancer assay and electrophoretic-mobility-shift assay were used to estimate the involvement of transcription factors. Western blotting and an in vitro kinase assay were used to evaluate the level and activity of protein kinase. We showed that glucose (100-900 mg/dl) induced an increase in mRNA level and promoter activity of TbetaRII (note: 'mg/dl' are the units commonly used in diabetes studies). The promoter region -209 to -177 appeared to contribute to positive transactivation of TbetaRII promoter by comparing five TbetaRII-promoter-CAT (chloramphenicol acetyl-transferase) plasmids. Moreover, the transcription factor AP-1 (activator protein 1) was significantly activated and specifically binds to TbetaRII promoter (-209 to -177). More importantly, we found that atypical PKC iota might be pivotal for high glucose-induced increase in both AP-1 binding and TbetaRII promoter activity. First, high glucose induced cytosolic translocation, activation and autophosphorylation of PKC iota. Secondly, antisense PKC iota expression plasmids attenuated high-glucose-induced increase in AP-1 binding and TbetaRII promoter activity; moreover, sense PKC iota expression plasmids enhanced these instead. Finally, we showed that antisense PKC iota expression plasmids might partly attenuate a high-glucose/TGF-beta1-induced increase in fibronectin. We conclude that PKC iota might mediate high-glucose-induced increase in TbetaRII promoter activity. In addition, antisense PKC iota expression plasmid effectively suppressed up-regulation of TbetaRII and fibronectin in hyperglycaemic distal-tubule cells.
Collapse
MESH Headings
- Analysis of Variance
- Animals
- Blotting, Northern
- Cell Line
- Cell Membrane/enzymology
- Chloramphenicol O-Acetyltransferase/genetics
- Chloramphenicol O-Acetyltransferase/metabolism
- Cytosol/enzymology
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Gene Expression Regulation/drug effects
- Glucose/pharmacology
- Immunoblotting
- Isoenzymes/metabolism
- Kidney Tubules, Distal/cytology
- Kidney Tubules, Distal/drug effects
- Kidney Tubules, Distal/metabolism
- Promoter Regions, Genetic/genetics
- Protein Binding/drug effects
- Protein Kinase C/metabolism
- Protein Serine-Threonine Kinases
- Protein Transport/drug effects
- RNA, Messenger/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/genetics
- Receptors, Transforming Growth Factor beta/metabolism
- Recombinant Fusion Proteins/drug effects
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Transcription Factor AP-1/metabolism
- Transcription Factors/metabolism
Collapse
Affiliation(s)
- Lea-Yea Chuang
- Department of Biochemistry, Kaohsiung Medical University, Tainan, Taiwan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Gopalakrishna R, Gundimeda U. Antioxidant regulation of protein kinase C in cancer prevention. J Nutr 2002; 132:3819S-3823S. [PMID: 12468631 DOI: 10.1093/jn/132.12.3819s] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Besides scavenging free radicals, antioxidants inhibit signaling enzymes such as protein kinase C (PKC) that play a crucial role in tumor promotion. By having different oxidation susceptible regions, PKC can respond to both oxidant tumor promoters and cancer-preventive antioxidants to elicit opposite cellular responses. Oxidant tumor promoters activate PKC by reacting with zinc-thiolates present within the regulatory domain. In contrast, the oxidized forms of some cancer-preventive agents, such as polyphenolics (ellagic acid, 4-hydroxytamoxifen and curcumin) and selenocompounds, can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. This brings an efficient counteractive mechanism to block the signal transduction induced by tumor promoters at the first step itself. Because prostate cancer prevention clinical trials in large human population are under way, we have focused more on understanding the cancer-preventive mechanism of selenium. Methylselenol, the postulated cancer-preventive metabolite, has no direct effect on PKC activity. However, methylseleninic acid, locally generated by the reaction of membrane methylselenol with PKC-bound tumor-promoting fatty acid hydroperoxides, selectively inactivates PKC. This mechanism clarifies how the volatile methylselenol that is present in a low concentration induces the inactivation of PKC selectively in the promoting precancer cells. Selenoprotein thioredoxin reductase reverses selenium-induced inactivation of PKC, suggesting that selenoproteins may serve as a safeguard against the toxicity induced by selenometabolites. Moreover, this also explains how a resistance to selenium develops in advanced malignant cells. The redox-mediated inactivation of PKC may, at least in part, be responsible for the antioxidant-induced inhibition of tumor promotion and cell growth, as well as for the induction of cell death.
Collapse
Affiliation(s)
- Rayudu Gopalakrishna
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles 90089, USA.
| | | |
Collapse
|
31
|
Gopalakrishna R, Gundimeda U. Protein kinase C as a molecular target for cancer prevention by selenocompounds. Nutr Cancer 2002; 40:55-63. [PMID: 11799924 DOI: 10.1207/s15327914nc401_11] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Selenium is a very effective cancer-preventive agent, suppressing tumor promotion and early stages of tumor progression. However, the mechanisms by which selenium exerts these cancer-preventive actions are not known. Protein kinase C (PKC) is a receptor for certain tumor promoters and also plays a crucial role in events related to tumor progression. Therefore, it is not only a potential target for the cancer-preventive activity of selenium, but also it has the structural basis for interaction with selenium. Redox-active selenocompounds can inactivate PKC, particularly the Ca(2+)-dependent isozymes, by reacting with the critical cysteine-rich regions present within the catalytic domain while, in some cases, also reacting with the cysteine residues present within the zinc-fingers of the regulatory domain. The selenoprotein thioredoxin reductase (TR), acting through thioredoxin, reverses the inactivation of PKC induced by selenometabolites. Furthermore, TR, through a direct interaction involving its selenosulfur center with the zinc-thiolates of PKC, can reverse the redox modification of this kinase induced by selenometabolites. Thus the selenometabolite-induced toxicity is reversed by a selenoprotein, and therefore an interrelationship exists between these two mechanisms of selenium actions. Moreover, this also explains how a resistance to selenium develops in advanced tumor cells probably due to an overexpression of functional TR. Selenium-induced inactivation of PKC may, at least in part, be responsible for the selenium-induced inhibition of tumor promotion, cell growth, invasion, and metastasis, as well as for the induction of apoptosis.
Collapse
Affiliation(s)
- R Gopalakrishna
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
| | | |
Collapse
|
32
|
Iles KE, Dickinson DA, Watanabe N, Iwamoto T, Forman HJ. AP-1 activation through endogenous H(2)O(2) generation by alveolar macrophages. Free Radic Biol Med 2002; 32:1304-13. [PMID: 12057768 DOI: 10.1016/s0891-5849(02)00840-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Reactive oxygen species released during the respiratory burst are known to participate in cell signaling. Here we demonstrate that hydrogen peroxide produced by the respiratory burst activates AP-1 binding. Stimulation of the macrophage cell line NR8383 with respiratory burst agonists ADP and C5a increased AP-1 binding activity. Importantly, this increase in binding was blocked by catalase, confirming mediation by endogenous H(2)O(2). Moreover, exogenously added H(2)O(2) mimicked the agonists, and also activated AP-1. Antibodies revealed that the activated AP-1 complex is composed predominantly of c-Fos/c-Jun heterodimers. Treatment of the cells with ADP, C5a and H(2)O(2) (100 microM) all increased the phosphorylation of c-Jun. c-Fos protein was increased in cells treated with C5a or high dose (200 microM) H(2)O(2), but not in cells treated with ADP. The MEK inhibitor, PD98059, partially blocked the C5a-mediated increase in AP-1 binding. A novel membrane-permeable peptide inhibitor of JNK, JNKi, also inhibited AP-1 activation. Together these data suggest that C5a-mediated AP-1 activation requires both the activation of the ERK and JNK pathways, whereas activation of the JNK pathway is sufficient to increase AP-1 binding with ADP. Thus, AP-1 activation joins the list of pathways for which the respiratory burst signals downstream events in the macrophage.
Collapse
Affiliation(s)
- Karen E Iles
- Department of Environmental Health Sciences, University of Alabama at Birmingham, 35294-0022, USA
| | | | | | | | | |
Collapse
|
33
|
Inoue K, Cynshi O, Kawabe Y, Nakamura M, Miyauchi K, Kimura T, Daida H, Hamakubo T, Yamaguchi H, Kodama T. Effect of BO-653 and probucol on c-MYC and PDGF-A messenger RNA of the iliac artery after balloon denudation in cholesterol-fed rabbits. Atherosclerosis 2002; 161:353-63. [PMID: 11888518 DOI: 10.1016/s0021-9150(01)00662-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Antioxidants have been proposed as a promising treatment for restenosis after percutaneous transluminal coronary angioplasty (PTCA), but their mechanism of action remains unclear. Here, we investigated the effect of antioxidants on gene expression in the artery after balloon denudation. We developed a sensitive ribonuclease (RNase) protection assay for the messenger RNA (mRNA) levels of immediate early (IE) genes (c-jun, c-fos and c-myc), as well as platelet-derived growth factor-A (PDGF-A), platelet-derived growth factor-beta receptor, transforming growth factor-beta 1, and vascular endothelial growth factor. New Zealand White rabbits were fed a 0.17% cholesterol diet containing vehicle, BO-653 or probucol, and balloon denudation for iliac arteries was performed. The iliac arteries were then removed at 4 h after the denudation, for IE genes, and 10 days after for growth factors and receptors. Both BO-653 and probucol significantly reduced neointimal thickening, compared with the control. In terms of gene expression, BO-653, but not probucol, significantly inhibited c-myc induction. On the other hand, probucol, but not BO-653, significantly inhibited PDGF-A expression. Neither treatment had any effect on the expression of other genes. These results suggest that antioxidants affect the gene expression of the neointimal response and that both BO-653 and probucol inhibit gene expression in specific manners.
Collapse
Affiliation(s)
- Kenji Inoue
- Department Molecular Biology and Medicine, The University of Tokyo, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Maggi-Capeyron MF, Ceballos P, Cristol JP, Delbosc S, Le Doucen C, Pons M, Léger CL, Descomps B. Wine phenolic antioxidants inhibit AP-1 transcriptional activity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2001; 49:5646-5652. [PMID: 11714372 DOI: 10.1021/jf010595x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Some of the beneficial effects of moderate wine consumption may be related to the antioxidant properties of polyphenolic compounds containing tannins, flavonoids, and phenolic acids. Cellular actions have recently been reported and may involve the modulation of transcriptional factors such as AP-1 (activator protein-1), which controls the expression of various genes implicated in inflammation processes, cell differentiation, and proliferation. The aim of this study was to evaluate the modulation of AP-1 activity by the phenolic acids (gallic, caffeic, protocatechic, paracoumaric, sinapic, and ferulic acids) that are present in wine and to compare their modulating pathways to those of lipophilic or hydrophilic "chain-breaking" antioxidants (such as DL-alpha-tocopherol or trolox) vitamin C, nitric oxide, and reduced glutathione. AP-1 response was studied on a cell line (MTLN) derived from MCF-7 cells transfected with luciferase gene under TRE sequence control. After stimulation by phorbol 12-myristate 13-acetate (PMA; 100 nM, 6 h, 10(-7) M), luciferase activity was determined by a luminescence method in the presence of luciferine/coenzyme A solution using a luminometer (LKB 1251, Finland). Antioxidants to be tested were incubated with cells in the presence or absence of PMA. Stimulation with PMA resulted in an AP-1-mediated increase in luciferase gene expression corresponding to an 8-fold increase in luciferase activity. After stimulation by PMA, a dose-dependent inhibition of AP-1 was observed with the six phenolic acids in the 20 nM-20 microM concentration range: gallic acid > caffeic > protocatechic, paracoumaric, sinapic acids > ferulic acid. Inhibition was more pronounced with phenolic acids than with DL-alpha-tocopherol (IC(50) = 5 +/- 4.5 microM for gallic acid vs 85 +/- 11 microM for vitamin E). None of the hydrophilic antioxidants inhibited PMA-induced AP-1 activation. None of the antioxidants tested in the absence of PMA stimulation induced any activation or inhibition of AP-1. Our results suggest that phenolic acids may act directly on cell signaling via inhibition of AP-1 transcriptional activity. In addition to preventing LDL oxidation in the arterial wall, our observations indicate that phenolic acids have a cell-mediated capacity to prevent some of the processes involved in atherosclerosis in a plasma concentration range compatible with nutritional intakes.
Collapse
Affiliation(s)
- M F Maggi-Capeyron
- EA Nutrition Humaine et Athérogénèse, Hôpital Lapeyronie, Avenue du Doyen Gaston Giraud, 34090 Montpellier, France
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Aksoy MO, Bin W, Yang Y, Yun-You D, Kelsen SG. Nuclear factor-kappa B augments beta(2)-adrenergic receptor expression in human airway epithelial cells. Am J Physiol Lung Cell Mol Physiol 2001; 281:L1271-8. [PMID: 11597920 DOI: 10.1152/ajplung.2001.281.5.l1271] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Interleukin (IL)-1 beta increases beta(2)-adrenergic receptor (beta(2)-AR) mRNA and density by protein kinase C (PKC)-dependent mechanisms in human airway epithelial cells. The present study examined the role of several nuclear transcription factors in the PKC-activated upregulation of beta(2)-AR expression. BEAS-2B cells were exposed to the PKC activator phorbol 12-myristate 13-acetate (PMA; 0.1 microM for 2-18 h). PMA had no effect on activator protein (AP)-2 or cAMP response element binding protein DNA binding activity but markedly increased nuclear factor (NF)-kappa B and AP-1 binding as assessed by electrophoretic gel mobility shift assay. PMA also increased the activity of a beta(2)-AR promoter-luciferase reporter construct in transiently transfected cells. These effects were inhibited by the PKC inhibitors Ro-31-8220 and calphostin C. Furthermore, with increasing Ro-31-8220, beta(2)-AR promoter-reporter activity correlated closely with both NF-kappa B and AP-1 activities (r > 0.89 for both). Finally, the selective NF-kappa B inhibitor MG-132 dose dependently reduced NF-kappa B binding and beta(2)-AR promoter activity but increased AP-1 binding. We conclude that PKC-induced upregulation of beta(2)-AR expression in human airway epithelial cells appears to be mediated, at least in part, by increases in NF-kappa B activity.
Collapse
Affiliation(s)
- M O Aksoy
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
| | | | | | | | | |
Collapse
|
36
|
Kowluru RA, Kennedy A. Therapeutic potential of anti-oxidants and diabetic retinopathy. Expert Opin Investig Drugs 2001; 10:1665-76. [PMID: 11772276 DOI: 10.1517/13543784.10.9.1665] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Retinopathy, a severely disabling complication of diabetes mellitus, is today the leading cause of acquired blindness among young adults in developed countries. Good glycaemic control can attenuate the development of diabetic retinopathy but such metabolic control is often difficult to achieve and maintain and additional therapies need to be identified by which retinopathy can be prevented or arrested. Hyperglycaemia plays a critical role in the development and progression of retinopathy, but the mechanism by which hyperglycaemia results in the development of retinopathy is not clear. Oxidative stress is increased in the retina in diabetes. The possible sources of increased oxidative stress might include increased generation of free radicals or impaired anti-oxidant defence system. Dietary supplementation with anti-oxidants in animal models of diabetic retinopathy inhibits retinal metabolic abnormalities and retinal histopathology, suggesting that oxidative stress is associated with the development of retinopathy. The mechanism by which anti-oxidants inhibit retinopathy in diabetes warrants further investigation, but animal studies show that increasing the diversity of anti-oxidants provides significantly more protection than using any single anti-oxidant. Thus, supplementation with anti-oxidants represents an achievable adjunct therapy to help preserve vision in diabetic patients.
Collapse
Affiliation(s)
- R A Kowluru
- Kresge Eye Institute, Wayne State University, 4717 St. Antoine, Detroit, MI 48201, USA.
| | | |
Collapse
|
37
|
Kowluru RA, Tang J, Kern TS. Abnormalities of retinal metabolism in diabetes and experimental galactosemia. VII. Effect of long-term administration of antioxidants on the development of retinopathy. Diabetes 2001; 50:1938-42. [PMID: 11473058 DOI: 10.2337/diabetes.50.8.1938] [Citation(s) in RCA: 297] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Antioxidants were administered to diabetic rats and experimentally galactosemic rats to evaluate the ability of these agents to inhibit the development of diabetic retinopathy. Alloxan diabetic rats and nondiabetic rats that were fed 30% galactose randomly received standard diets or the diets supplemented with ascorbic acid and alpha-tocopherol (vitamins C+E diet) or a more comprehensive mixture of antioxidants (multi-antioxidant diet), including Trolox, alpha-tocopherol, N-acetyl cysteine, ascorbic acid, beta-carotene, and selenium. Diabetes or galactose feeding of at least 12 months resulted in pericyte loss, acellular capillaries, and basement membrane thickening. Compared with diabetic controls, the development of acellular capillaries was inhibited by 50% (P < 0.05) in diabetic rats that received supplemental vitamins C+E, and the number of pericyte ghosts tended to be reduced. The vitamins C+E supplement had no beneficial effect in galactosemic rats, but these rats consumed only approximately half as much of the antioxidants as the diabetic rats. The multi-antioxidant diet significantly inhibited ( approximately 55-65%) formation of both pericyte ghosts and acellular capillaries in diabetic rats and galactosemic rats (P < 0.05 vs. controls), without affecting the severity of hyperglycemia. Parameters of retinal oxidative stress, protein kinase C activity, and nitric oxides remained elevated for at least 1 year of hyperglycemia, and these abnormalities were normalized by multi-antioxidant therapy. Thus, long-term administration of antioxidants can inhibit the development of the early stages of diabetic retinopathy, and the mechanism by which this action occurs warrants further investigation. Supplementation with antioxidants can offer an achievable and inexpensive adjunct therapy to help inhibit the development of retinopathy in diabetes.
Collapse
Affiliation(s)
- R A Kowluru
- Kresge Eye Institute, Wayne State University, Detroit, Michigan 48201, USA
| | | | | |
Collapse
|
38
|
|
39
|
Fernandes D, Vlahos R, Stewart AG. Thrombin-stimulated DNA synthesis in human cultured airway smooth muscle occurs independently of products of cyclo-oxygenase or 5-lipoxygenase. Pulm Pharmacol Ther 2001; 13:241-8. [PMID: 11001867 DOI: 10.1006/pupt.2000.0251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Arachidonic acid (AA) liberation and metabolism via cyclo-oxygenase or lipoxygenases may be an important regulatory pathway for mitogenic signalling in human cultured airway smooth muscle (ASM) cells. In cytokine-treated cells, thrombin markedly enhances production of the anti-mitogenic arachidonic acid metabolite, PGE(2). In this study, in the absence of cytokines, we examined the role of endogenous AA metabolism in thrombin-stimulated ASM DNA synthesis. Selective inhibitors of cyclo-oxygenase of 5-lipoxygenase metabolism had no significant effect on 0.3 U/ml thrombin-stimulated DNA synthesis. However, the non-selective, redox-active lipoxygenase inhibitors NDGA and BWA4C inhibited thrombin-stimulated DNA synthesis. Under basal conditions, and following stimulation by thrombin, the levels of the AA metabolites PGE(2), TxA(2), and LTC(4), remained below assay detection limits. Exogenous addition of AA, LTD(4), or 5-, 12-, and 15-HETE and HpETE metabolites had no consistent or substantial stimulatory effect on either basal or thrombin-stimulated DNA synthesis. These data suggest that the non-selective lipoxygenase inhibitors influence DNA synthesis via effects unrelated to lipoxygenase inhibition. The lack of detection of AA metabolites, the lack of influence of selective antagonists/inhibitors of the AA pathway, and the failure of selected AA metabolites to either enhance or directly stimulate DNA synthesis suggest that in the absence of cytokines, cyclo-oxygenase and lipoxygenase metabolism has little role in signalling of human ASM DNA synthesis by thrombin.
Collapse
Affiliation(s)
- D Fernandes
- Department of Pharmacology, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | | | | |
Collapse
|
40
|
Traber MG. Does vitamin E decrease heart attack risk? summary and implications with respect to dietary recommendations. J Nutr 2001; 131:395S-7S. [PMID: 11160568 DOI: 10.1093/jn/131.2.395s] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The hypothesis that oxidative stress has a role in atherosclerosis rests on a large body of experimental work carried out in animal models of heart disease. The situation is more complex in humans, in that the results from vitamin E supplementation trials have been conflicting. Nonetheless, there is emerging information that alpha-tocopherol may play a critical role in maintaining the function of key cellular components in the atherosclerotic process through its ability to inhibit the activity of protein kinase C, a key player in many signal transduction pathways. alpha-Tocopherol modulates pathways of platelet aggregation, endothelial cell nitric oxide production, monocyte/macrophage superoxide production and smooth muscle cell proliferation. Regulation of adhesion molecule expression and inflammatory cell cytokine production by alpha-tocopherol has also been reported. More studies are required to relate alpha-tocopherol intakes to optimal tissue responses in humans.
Collapse
Affiliation(s)
- M G Traber
- Department of Nutrition and Food Management, Linus Pauling Institute, Oregon State University, Corvallis, OR 97331-6512, USA
| |
Collapse
|
41
|
Domenicotti C, Paola D, Vitali A, Nitti M, d'Abramo C, Cottalasso D, Maloberti G, Biasi F, Poli G, Chiarpotto E, Marinari UM, Pronzato MA. Glutathione depletion induces apoptosis of rat hepatocytes through activation of protein kinase C novel isoforms and dependent increase in AP-1 nuclear binding. Free Radic Biol Med 2000; 29:1280-90. [PMID: 11118818 DOI: 10.1016/s0891-5849(00)00429-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Treatment of isolated rat hepatocytes with the glutathione depleting agents L-buthionine-S,R-sulfoximine or diethylmaleate reproduced various cellular conditions of glutathione depletion, from moderate to severe, similar to those occurring in a wide spectrum of human liver diseases. To evaluate molecular changes and possible cellular dysfunction and damage consequent to a pathophysiologic level of GSH depletion, the effects of this condition on protein kinase C (PKC) isoforms were investigated, since these are involved in the intracellular specific regulatory processes and are potentially sensitive to redox changes. Moreover, a moderate perturbation of cellular redox state was found to activate novel PKC isoforms, and a clear relationship was shown between novel kinase activation and nuclear binding of the redox-sensitive transcription factor, activator protein-1 (AP-1). Apoptotic death of a significant number of cells, confirmed in terms of internucleosomal DNA fragmentation was a possible effect of these molecular reactions, and was triggered by a condition of glutathione depletion usually detected in human liver diseases. Finally, the inhibition of novel PKC enzymatic activity in cells co-treated with rottlerin, a selective novel kinase inhibitor, prevented glutathione-dependent novel PKC up-regulation, markedly moderated AP-1 activation, and protected cells against apoptotic death. Taken together, these findings indicate the existence of an apoptotic pathway dependent on glutathione depletion, which occurs through the up-regulation of novel PKCs and AP-1.
Collapse
Affiliation(s)
- C Domenicotti
- Department of Experimental Medicine, General Pathology Section, University of Genova, Genova, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Kowluru RA, Engerman RL, Kern TS. Abnormalities of retinal metabolism in diabetes or experimental galactosemia VIII. Prevention by aminoguanidine. Curr Eye Res 2000; 21:814-9. [PMID: 11120572 DOI: 10.1076/ceyr.21.4.814.5545] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Aminoguanidine has been found to inhibit the development of some retinal lesions in diabetic rats and diabetic dogs, thereby raising a possibility that the formation of glycation end products (AGEs) may be an essential step in the pathogenesis of the retinopathy. The purpose of this study is to investigate the effect of aminoguanidine administration on other metabolic abnormalities which might be involved in the development of retinopathy in two models of the retinopathy, alloxan diabetes and experimental galactosemia. METHODS Oxidative stress, nitric oxide (NO) and the activity of protein kinase C (PKC, total activity) were measured in the retina of the rats experimentally diabetic or galactosemic for 2 months. Effect of aminoguanidine administration on the inhibition of hyperglycemia-induced retinal dysmetabolism was investigated. RESULTS Two months of diabetes or experimental galactosemia in rats resulted in elevation of retinal oxidative stress (increase in thiobarbituric acid reactive substances, TBARS, and decrease in glutathione, GSH), NO, and PKC activity. Aminoguanidine supplementation (2.5 g aminoguanidine/kg rat diet) significantly inhibited each of these abnormalities in retinas of diabetic rats and galactosemic rats, and did so without lowering the blood hexose levels of these animals. CONCLUSIONS The ability of aminoguanidine to normalize the hyperglycemia-induced increases in retinal oxidative stress, NO and PKC in diabetic rats and galactose-fed rats suggests that these abnormalities may be inter-related in the retina, and that the biochemical mechanism by which aminoguanidine inhibits retinal microvascular disease in diabetes may be complex.
Collapse
Affiliation(s)
- R A Kowluru
- Kresge Eye Institute, Wayne State University, Detroit, Michigan 48201, USA.
| | | | | |
Collapse
|
43
|
McIntyre BS, Briski KP, Gapor A, Sylvester PW. Antiproliferative and apoptotic effects of tocopherols and tocotrienols on preneoplastic and neoplastic mouse mammary epithelial cells. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 2000; 224:292-301. [PMID: 10964265 DOI: 10.1046/j.1525-1373.2000.22434.x] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Studies were conducted to determine the comparative effects of tocopherols and tocotrienols on preneoplastic (CL-S1), neoplastic (-SA), and highly malignant (+SA) mouse mammary epithelial cell growth and viability in vitro. Over a 5-day culture period, treatment with 0-120 microM alpha- and gamma-tocopherol had no effect on cell proliferation, whereas growth was inhibited 50% (IC50) as compared with controls by treatment with the following: 13, 7, and 6 microM tocotrienol-rich-fraction of palm oil (TRF); 55, 47, and 23 microM delta-tocopherol; 12, 7, and 5 microM alpha-tocotrienol; 8, 5, and 4 microM gamma-tocotrienol; or 7, 4, and 3 microM delta-tocotrienol in CL-S1, -SA and +SA cells, respectively. Acute 24-hr exposure to 0-250 microM alpha- or gamma-tocopherol (CL-S1, -SA, and +SA) or 0-250 microM delta-tocopherol (CL-S1) had no effect on cell viability, whereas cell viability was reduced 50% (LD50) as compared with controls by treatment with 166 or 125 microM delta-tocopherol in -SA and +SA cells, respectively. Additional LD50 doses were determined as the following: 50, 43, and 38 microM TRF; 27, 28, and 23 microM alpha-tocotrienol; 19, 17, and 14 microM gamma-tocotrienol; or 16, 15, or 12 microM delta-tocotrienol in CL-S1, -SA, and +SA cells, respectively. Treatment-induced cell death resulted from activation of apoptosis, as indicated by DNA fragmentation. Results also showed that CL-S1, -SA, and +SA cells preferentially accumulate tocotrienols as compared with tocopherols, and this may partially explain why tocotrienols display greater biopotency than tocopherols. These data also showed that highly malignant +SA cells were the most sensitive, whereas the preneoplastic CL-S1 cells were the least sensitive to the antiproliferative and apoptotic effects of tocotrienols, and suggest that tocotrienols may have potential health benefits in preventing and/or reducing the risk of breast cancer in women.
Collapse
Affiliation(s)
- B S McIntyre
- College of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana 71209-0470, USA
| | | | | | | |
Collapse
|
44
|
Zapolska-Downar D, Zapolski-Downar A, Markiewski M, Ciechanowicz A, Kaczmarczyk M, Naruszewicz M. Selective inhibition by alpha-tocopherol of vascular cell adhesion molecule-1 expression in human vascular endothelial cells. Biochem Biophys Res Commun 2000; 274:609-15. [PMID: 10924325 DOI: 10.1006/bbrc.2000.3197] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An early event in atherogenesis is the adhesion of monocytes to endothelium via adhesion molecules such as VCAM-1 and intracellular adhesion molecule-1 (ICAM-1). It has been suggested that VCAM-1 plays a very important role in recruitment of monocytes in atherosclerosis. Several studies suggest that vitamin E has antiatherosclerotic properties. However, the mechanism of its antiatherogenic effect awaits elucidation. The aim of our study was to evaluate whether alpha-tocopherol can influence expression of endothelial cell adhesion molecules and endothelial adhesiveness. The study was performed on cultured human umbilical vein endothelial cells (HUVEC). HUVEC were pretreated with alpha-tocopherol (50 micromol/l) in different times before stimulation with TNFalpha (100 U/ml) or IL-1beta (100 U/ml). Protein expression of VCAM-1 and ICAM-1 was measured by flow cytometry. mRNA expression of VCAM-1 was measured by reverse transcription polymerase chain reaction (RT-PCR). alpha-Tocopherol time dependently reduced agonist-induced VCAM-1 in both surface protein (about 40%, 48 h) and mRNA (about 35%, 48 h) expression in HUVEC but not ICAM-1 surface protein expression. Inhibitory effect of alpha-tocopherol was dependent on culture condition of HUVEC. Decreased VCAM-1 expression was associated with reduction (about 40%) of adherence between cytokine-stimulated HUVEC and peripheral blood mononuclear leukocytes (PBMC). Our results suggest that the antiatherogenic effect of alpha-tocopherol may in part be due to a downregulation of VCAM-1 expression.
Collapse
Affiliation(s)
- D Zapolska-Downar
- Regional Center for Atherosclerosis Research, Pomeranian Academy of Medicine, Szczecin, 70-111, Poland
| | | | | | | | | | | |
Collapse
|
45
|
Chae HJ, Kang JS, Han JI, Bang BG, Chae SW, Kim KW, Kim HM, Kim HR. Production of hydrogen peroxide by serum and its involvement in cell proliferation in ROS 17/2.8 osteoblasts. Immunopharmacol Immunotoxicol 2000; 22:317-37. [PMID: 10952034 DOI: 10.3109/08923970009016423] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The effects of hydrogen peroxide, which fetal bovine serum (FBS) releases, on proliferation have been studied in ROS 17/2.8 osteoblasts. Cell proliferation, when activated by FBS, was inhibited by catalase in ROS 17/2.8 osteoblasts, but did not in primary osteoblast-like cells. Serum-induced extracellular signal-regulated kinase(ERK) activity was reduced by the pretreated catalase in ROS 17/2.8 osteoblasts. In addition, the present studies demonstrate that addition of FBS led to an increase of fluorescence of dihydrorhodamine 123, indicating formation of free radicals including hydrogen peroxide in ROS 17/2.8 osteoblasts, but not in primary osteoblast-like cells. These phenomena may account for the generation of reactive oxygen species during cellular proliferation in ROS 17/2.8 osteoblasts.
Collapse
Affiliation(s)
- H J Chae
- Department of Dental Pharmacology, School of Dentistry, Wonkwang University, Iksan, Chonbuk, South Korea
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
Oxidative stress is involved in the pathogenesis of various degenerative diseases including cancer. It is now recognized that low levels of oxidants can modify cell-signaling proteins and that these modifications have functional consequences. Identifying the target proteins for redox modification is key to understanding how oxidants mediate pathological processes such as tumor promotion. These proteins are also likely to be important targets for chemopreventive antioxidants, which are known to block signaling induced by oxidants and to induce their own actions. Various antioxidant preventive agents also inhibit PKC-dependent cellular responses. Therefore, PKC is a logical candidate for redox modification by oxidants and antioxidants that may in part determine their cancer-promoting and anticancer activities, respectively. PKCs contain unique structural features that are susceptible to oxidative modification. The N-terminal regulatory domain contains zinc-binding, cysteine-rich motifs that are readily oxidized by peroxide. When oxidized, the autoinhibitory function of the regulatory domain is compromised and, consequently, cellular PKC activity is stimulated. The C-terminal catalytic domain contains several reactive cysteines that are targets for various chemopreventive antioxidants such as selenocompounds, polyphenolic agents such as curcumin, and vitamin E analogues. Modification of these cysteines decreases cellular PKC activity. Thus the two domains of PKC respond differently to two different type of agents: oxidants selectively react with the regulatory domain, stimulate cellular PKC, and signal for tumor promotion and cell growth. In contrast, antioxidant chemopreventive agents react with the catalytic domain, inhibit cellular PKC activity, and thus interfere with the action of tumor promoters.
Collapse
Affiliation(s)
- R Gopalakrishna
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | | |
Collapse
|
47
|
McIntyre BS, Briski KP, Tirmenstein MA, Fariss MW, Gapor A, Sylvester PW. Antiproliferative and apoptotic effects of tocopherols and tocotrienols on normal mouse mammary epithelial cells. Lipids 2000; 35:171-80. [PMID: 10757548 DOI: 10.1007/bf02664767] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Studies were conducted to determine the comparative effects of tocopherols and tocotrienols on normal mammary epithelial cell growth and viability. Cells isolated from midpregnant BALB/c mice were grown within collagen gels and maintained on serum-free media. Treatment with 0-120 microM alpha- and gamma-tocopherol had no effect, whereas 12.5-100m microM tocotrienol-rich fraction of palm oil (TRF), 100-120 microM delta-tocopherol, 50-60 microM alpha-tocotrienol, and 8-14 microM gamma- or delta-tocotrienol significantly inhibited cell growth in a dose-responsive manner. In acute studies, 24-h exposure to 0-250 microM alpha-, gamma-, and delta-tocopherol had no effect, whereas similar treatment with 100-250 microM TRF, 140-250 microM alpha-, 25-100 microM gamma- or delta-tocotrienol significantly reduced cell viability. Growth-inhibitory doses of TRF, delta-tocopherol, and alpha-, gamma-, and delta-tocotrienol were shown to induce apoptosis in these cells, as indicated by DNA fragmentation. Results also showed that mammary epithelial cells more easily or preferentially took up tocotrienols as compared to tocopherols, suggesting that at least part of the reason tocotrienols display greater biopotency than tocopherols is because of greater cellular accumulation. In summary, these findings suggest that the highly biopotent gamma- and delta-tocotrienol isoforms may play a physiological role in modulating normal mammary gland growth, function, and remodeling.
Collapse
Affiliation(s)
- B S McIntyre
- Colleges of Pharmacy, University of Louisiana, Monroe 71209-0470, USA
| | | | | | | | | | | |
Collapse
|
48
|
The Effects of Bioenergetic Stress and Redox Balance on the Expression of Genes Critical to Mitochondrial Function. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1568-1254(00)80017-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
49
|
Ruiz-Ginés JA, López-Ongil S, González-Rubio M, González-Santiago L, Rodríguez-Puyol M, Rodríguez-Puyol D. Reactive oxygen species induce proliferation of bovine aortic endothelial cells. J Cardiovasc Pharmacol 2000; 35:109-13. [PMID: 10630740 DOI: 10.1097/00005344-200001000-00014] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects of reactive oxygen species (ROS) on different cellular types are variable. In some conditions they can be harmful metabolites, but they can also act as intracellular messengers that are able to activate different transcription factors. Based on previous reports in which ROS were shown to stimulate the proliferation of mesenchymal cells, this study was carried out to assess this effect on bovine aortic endothelial cells (BAECs). When cells were incubated with glucose oxidase (GO), an enzyme that generates H2O2 continuously, a significant increase in BAEC proliferation was detected. BAEC proliferation was measured by the incorporation of [3H]-thymidine in the DNA of BAECs, and also by an increase in the number of cells. The effect observed with GO was maximal at 8-24 h. Catalase abolishes proliferation. We also tested the ability of GO to phosphorylate tyrosine residues in endothelial cell proteins. A significant increase in tyrosine phosphorylation was found, which might constitute the molecular basis for proliferative effect of GO. In conclusion, these results demonstrate the ability of H2O2 to stimulate BAEC proliferation at least under certain experimental conditions. We suggest a general activation of the cascade of tyrosine phosphorylation as one of the possible cellular mechanisms responsible for GO-induced BAEC proliferation.
Collapse
Affiliation(s)
- J A Ruiz-Ginés
- Department of Physiology, Alcala University, Alcalá de Henares, Madrid, Spain
| | | | | | | | | | | |
Collapse
|
50
|
Kowluru RA, Engerman RL, Kern TS. Diabetes-induced metabolic abnormalities in myocardium: effect of antioxidant therapy. Free Radic Res 2000; 32:67-74. [PMID: 10625218 DOI: 10.1080/10715760000300071] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Effects of hyperglycemia (both diabetes and experimental galactosemia) on cardiac metabolism have been determined. In addition, the effect of supplemental antioxidants on these hyperglycemia-induced abnormalities of cardiac metabolism has been investigated. Diabetes or experimental galactosemia of 2 months duration in rats significantly increased oxidative stress in myocardium, as demonstrated by elevation of thiobarbituric acid reactive substances (TBARS) and lipid fluorescent products in left ventricle. Activity of protein kinase C (PKC) was elevated in the myocardium, and the activities of (Na,K)-ATPase and calcium ATPases were subnormal. Administration of supplemental antioxidants containing a mixture of ascorbic acid, Trolox; alpha-tocopherol acetate, N-acetyl cysteine, beta-carotene, and selenium prevented both the diabetes-induced and galactosemia-induced elevation of oxidative stress and PKC activity, and inhibited the decreases of myocardial (Na,K)-ATPase and calcium ATPases. The results show that these metabolic abnormalities are not unique to diabetes per se, but are secondary to elevated blood hexose levels, and supplemental antioxidants inhibit these metabolic abnormalities. Our findings suggest that antioxidants inhibit abnormal metabolic processes that may contribute to the development of cardiac disease in diabetes, and offer a potential clinical means to inhibit cardiac abnormalities in diabetes.
Collapse
Affiliation(s)
- R A Kowluru
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison 57306, USA.
| | | | | |
Collapse
|