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Miller WP, Ravi S, Martin TD, Kimball SR, Dennis MD. Activation of the Stress Response Kinase JNK (c-Jun N-terminal Kinase) Attenuates Insulin Action in Retina through a p70S6K1-dependent Mechanism. J Biol Chem 2016; 292:1591-1602. [PMID: 27965359 DOI: 10.1074/jbc.m116.760868] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/28/2016] [Indexed: 01/14/2023] Open
Abstract
Despite recent advances in therapeutics, diabetic retinopathy remains a leading cause of vision impairment. Improvement in the treatment of diabetic retinopathy requires a better understanding of the molecular mechanisms that cause neurovascular complications, particularly in type 2 diabetes. Recent studies demonstrate that rodents fed a high fat diet exhibit retinal dysfunction concomitant with attenuated Akt phosphorylation. The purpose of the present study was to evaluate the impact of a high fat/high sucrose diet on retinal insulin signaling and evaluate the mechanism(s) responsible for the changes. Mice fed a high fat/sucrose diet exhibited attenuated Akt phosphorylation in the retina as compared with mice fed normal chow. Retinas of mice fed a high fat/sucrose diet also exhibited elevated levels of activated JNK as well as enhanced p70S6K1 autoinhibitory domain phosphorylation. In cells, JNK activation enhanced p70S6K1 phosphorylation and mTORC1-dependent activation of the kinase, as evidenced by enhanced phosphorylation of key substrates. Rictor phosphorylation by p70S6K1 was specifically enhanced by the addition of phosphomimetic mutations in the autoinhibitory domain and was more sensitive to inhibition of the kinase as compared with rpS6. Notably, rictor and IRS-1 phosphorylation by p70S6K1 attenuate insulin action through a negative feedback pathway. Indeed, p70S6K1 inhibition prevented the repressive effect of JNK activation on insulin action in retinas. Overall, the results identify the JNK/S6K1 axis as a key molecular mechanism whereby a high fat/sucrose diet impairs insulin action in retina.
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Affiliation(s)
- William P Miller
- From the Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Suhana Ravi
- From the Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Tony D Martin
- From the Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Scot R Kimball
- From the Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Michael D Dennis
- From the Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033.
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52
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Teo CF, El-Karim EG, Wells L. Dissecting PUGNAc-mediated inhibition of the pro-survival action of insulin. Glycobiology 2016; 26:1198-1208. [PMID: 27072814 PMCID: PMC5884396 DOI: 10.1093/glycob/cww043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/01/2016] [Indexed: 01/02/2023] Open
Abstract
Previous studies utilizing PUGNAc, the most widely used β-N-acetylglucosaminidase (OGA) inhibitor to increase global O-N-acetylglucosamine (GlcNAc) levels, have reported a variety of effects including insulin resistance as a direct result of elevated O-GlcNAc levels. The notion of OGA inhibition causing insulin resistance was not replicated in studies in which elevated global O-GlcNAc levels were achieved using two other OGA inhibitors. Related to insulin action, work by others has suggested that O-GlcNAc elevation may inhibit the anti-apoptotic action of insulin. Thus, we examined the pro-survival action of insulin upon serum deprivation in the presence of PUGNAc as well as two selective OGA inhibitors (GlcNAcstatin-g and Thiamet-G), and a selective lysosomal hexosaminidase inhibitor (INJ2). We established that PUGNAc inhibits the pro-survival action of insulin but this effect is not recapitulated by the selective OGA inhibitors suggesting that elevation in O-GlcNAc levels alone is not responsible for PUGNAc's effect on the anti-apoptotic action of insulin. Further, we demonstrate that a selective hexosaminidase A/B (HexA/B) inhibitor does not impact insulin action suggesting that PUGNAc's effect is not due to inhibition of lysosomal hexosaminidase. Finally, we tested a combination of selective OGA and lysosomal hexosaminidase inhibitors but were not able to recapitulate the inhibition of insulin action generated by PUGNAc alone. These results strongly suggest that the defect in insulin action upon PUGNAc treatment does not derive from its inhibition of OGA or HexA/B, and that there is an unknown target of PUGNAc that is the likely culprit in inhibiting the protective effect of insulin from apoptosis.
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Affiliation(s)
- Chin Fen Teo
- Department of Biochemistry and Molecular Biology
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-1516, USA
| | - Enas Gad El-Karim
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-1516, USA
| | - Lance Wells
- Department of Biochemistry and Molecular Biology
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-1516, USA
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53
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Yan D, Cai X, Feng Y. miR-183 Modulates Cell Apoptosis and Proliferation in Tongue Squamous Cell Carcinoma SCC25 Cell Line. Oncol Res 2016; 24:399-404. [PMID: 28281960 PMCID: PMC7838737 DOI: 10.3727/096504016x14685034103239] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
This study was designed to investigate the role of miR-183 in modulating cell growth and apoptosis of tongue squamous cell carcinoma SCC25 cell line. Human squamous epithelial cell and squamous cell carcinoma cell line SCC25 was used, and miR-183 was inhibited. Cell growth, colony formation, and apoptotic rate, as well as the expression of caspase 3 and BCL-xL, were detected. Results showed that miR-183 was significantly overexpressed in the SCC25 cell line when compared with normal control. The miR-183 inhibitor reduced cell growth and colony formation, while the apoptosis percentage was significantly increased. The expression of activated caspase 3 and BCL-xL was obviously up- and downregulated in siRNA-transfected cells, respectively. In conclusion, miR-183 contributed to cell growth and proliferation, and suppressed cell apoptosis in SCC25 cells. Therefore, miR-183 might serve as a therapeutic target in tongue squamous cell carcinoma (TSCC).
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Affiliation(s)
- Dayong Yan
- *Oral and Maxillofacial Surgery, The Central Hospital of Zhengzhou, University of Zhengzhou, Zhengzhou, Henan, P.R. China
| | - Xiaoqing Cai
- *Oral and Maxillofacial Surgery, The Central Hospital of Zhengzhou, University of Zhengzhou, Zhengzhou, Henan, P.R. China
| | - Yu Feng
- †Anesthesia Medicine, The Central Hospital of Zhengzhou, University of Zhengzhou, Zhengzhou, Henan, P.R. China
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54
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Rajasekar N, Nath C, Hanif K, Shukla R. Intranasal Insulin Administration Ameliorates Streptozotocin (ICV)-Induced Insulin Receptor Dysfunction, Neuroinflammation, Amyloidogenesis, and Memory Impairment in Rats. Mol Neurobiol 2016; 54:6507-6522. [PMID: 27730514 DOI: 10.1007/s12035-016-0169-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 09/27/2016] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is associated with reduced insulin level and impairment of insulin receptor (IR) signaling in the brain, which correlates to amyloid pathology, neuroinflammation, and synaptic neurotoxicity. Clinical studies show that intranasal insulin improves memory in AD patients without peripheral hypoglycemia. However, neuroprotective molecular mechanism of the beneficial effect of intranasal insulin in AD pathology is unexplored. Therefore, we investigated the role of intranasal insulin on intracerebroventricular (ICV) streptozotocin (STZ)-induced memory impairment in rats as evaluated in the Morris water maze test. STZ (ICV) treated rats had shown memory impairment along with a significant decrease in IR signaling molecules (IR, pIRS-1, pAkt, and pGSK-3α/β expression) and IDE expression in both hippocampus and cerebral cortex. Intranasal insulin delivery prevented these changes. Moreover, intranasal insulin was found to inhibit significantly glial cell activation (GFAP and Iba-1 expression), neuroinflammation (COX-2 expression, NFκB translocation, TNF-α, and IL-10 level) and amyloidogenic protein expression (BACE-1 and Aβ1-42 expression) in STZ (ICV)-injected rats. STZ (ICV)-induced caspase activation and postsynaptic neurotoxicity were also prevented by treatment with intranasal insulin. Our findings reveal that insulin has the neuroprotective effect and clearly signifies the potential use of intranasal insulin delivery for the treatment of AD. Graphical Abstract Neuroprotective effects of intranasal insulin administration on streptozotocin (ICV)-induced memory impairment in rats.
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Affiliation(s)
- N Rajasekar
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Chennai, India
| | - Chandishwar Nath
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Chennai, India
| | - Kashif Hanif
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Chennai, India
| | - Rakesh Shukla
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
- Academy of Scientific and Innovative Research (AcSIR), Chennai, India.
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55
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Kong D, Gong L, Arnold E, Shanmugam S, Fort PE, Gardner TW, Abcouwer SF. Insulin-like growth factor 1 rescues R28 retinal neurons from apoptotic death through ERK-mediated BimEL phosphorylation independent of Akt. Exp Eye Res 2016; 151:82-95. [PMID: 27511131 DOI: 10.1016/j.exer.2016.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/27/2016] [Accepted: 08/05/2016] [Indexed: 10/21/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) can provide long-term neurotrophic support by activation of Akt, inhibition of FoxO nuclear localization and suppression of Bim gene transcription in multiple neuronal systems. However, MEK/ERK activation can also promote neuron survival through phosphorylation of BimEL. We explored the contribution of the PI3K/Akt/FoxO and MEK/ERK/BimEL pathways in IGF-1 stimulated survival after serum deprivation (SD) of R28 cells differentiated to model retinal neurons. IGF-1 caused rapid activation of Akt leading to FoxO1/3-T32/T24 phosphorylation, and prevented FoxO1/3 nuclear translocation and Bim mRNA upregulation in response to SD. IGF-1 also caused MAPK/MEK pathway activation as indicated by ERK1/2-T202/Y204 and Bim-S65 phosphorylation. Overexpression of FoxO1 increased Bim mRNA expression and amplified the apoptotic response to SD without shifting the serum response curve. Inhibition of Akt activation with LY294002 or by Rictor knockdown did not block the protective effect of IGF-1, while inhibition of MEK activity with PD98059 prevented Bim phosphorylation and blocked IGF-1 protection. In addition, knockdown of Bim expression was protective during SD, while co-silencing of FoxO1 and Fox03 expression had little effect. Thus, the PI3K/Akt/FoxO pathway was not essential for protection from SD-induced apoptosis by IGF-1 in R28 cells. Instead, IGF-1 protection was dependent on activation of the MEK/ERK pathway leading to BimEL phosphorylation, which is known to prevent Bax/Bak oligomerization and activation of the intrinsic mitochondrial apoptosis pathway. These studies demonstrate the requirement of the MEK/ERK pathway in a model of retinal neuron cell survival and highlight the cell specificity for IGF-1 signaling in this response.
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Affiliation(s)
- Dejuan Kong
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Lijie Gong
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Edith Arnold
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Sumathi Shanmugam
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Patrice E Fort
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Thomas W Gardner
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States
| | - Steven F Abcouwer
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States.
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56
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Palleria C, Leporini C, Maida F, Succurro E, De Sarro G, Arturi F, Russo E. Potential effects of current drug therapies on cognitive impairment in patients with type 2 diabetes. Front Neuroendocrinol 2016; 42:76-92. [PMID: 27521218 DOI: 10.1016/j.yfrne.2016.07.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/13/2016] [Accepted: 07/22/2016] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus is a complex metabolic disease that can cause serious damage to various organs. Among the best-known complications, an important role is played by cognitive impairment. Impairment of cognitive functioning has been reported both in type 1 and 2 diabetes mellitus. While this comorbidity has long been known, no major advances have been achieved in clinical research; it is clear that appropriate control of blood glucose levels represents the best current (although unsatisfactory) approach in the prevention of cognitive impairment. We have focused our attention on the possible effect on the brain of antidiabetic drugs, despite their effects on blood glucose levels, giving a brief rationale on the mechanisms (e.g. GLP-1, BDNF, ghrelin) that might be involved. Indeed, GLP-1 agonists are currently clinically studied in other neurodegenerative diseases (i.e. Parkinson's and Alzheimer's disease); furthermore, also other antidiabetic drugs have proven efficacy in preclinical studies. Overall, promising results are already available and finding new intervention strategies represents a current need in this field of research.
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Affiliation(s)
- Caterina Palleria
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Christian Leporini
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Francesca Maida
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Elena Succurro
- Department of Medical and Surgical Sciences, Internal Medicine Unit of "Mater Domini", University Hospital, University "Magna Graecia" of Catanzaro, Policlinico "Mater Domini", Campus Universitario, Viale Europa, 88100 Catanzaro, Italy
| | - Giovambattista De Sarro
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Franco Arturi
- Department of Medical and Surgical Sciences, Internal Medicine Unit of "Mater Domini", University Hospital, University "Magna Graecia" of Catanzaro, Policlinico "Mater Domini", Campus Universitario, Viale Europa, 88100 Catanzaro, Italy
| | - Emilio Russo
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy.
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57
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Torabi S, DiMarco NM. Original Research: Polyphenols extracted from grape powder induce lipogenesis and glucose uptake during differentiation of murine preadipocytes. Exp Biol Med (Maywood) 2016; 241:1776-85. [PMID: 27190251 DOI: 10.1177/1535370216645213] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/28/2016] [Indexed: 12/22/2022] Open
Abstract
Assessing the effects of grapes and grape powder extracted polyphenols on lipogenesis and glucose uptake in adipocytes may clarify the risk/benefit of recommending them to individuals with obesity and insulin resistance. We investigated the effect of grape powder extracted polyphenols (GPEP) on intracellular fat accumulation and glucose uptake during differentiation of 3T3-F442A preadipocytes. Total polyphenols were extracted and measured based on gallic acid equivalents (GAE). There were 2167 mg of GAE polyphenols in 100 g of grape powder. 3T3-F442A cells were incubated with GPEP, extracted from 125-500 µg GP/mL of media, until day 8 of differentiation when the cells were collected for different assays. AdipoRed™ assay and Oil Red O staining showed that GPEP induced, in a dose-dependent manner, an increase in intracellular triacylglycerol (TAG) content of adipocytes. Concomitantly, grape powder extracted polyphenols increased, in a dose-dependent manner, glucose uptake by 3T3-F442A cells, and there was a strong positive correlation between glucose uptake and the amount of TAG accumulation (r = 0.826, n = 24, P ≤ 0.001). No changes in cell viability was measured by Trypan Blue staining, suggesting that these effects were independent of cytotoxicity. Western-blot showed that GPEP upregulated protein level of glucose transport protein 4 (GLUT4), p-PKB/Akt, and p-AMPK in 3T3-F442A adipocytes. LY294002 (10 µmol/L), a phosphatidyl-inositol 3 kinase inhibitor (PI3K), reversed the effects of grape powder extracted polyphenols on cellular lipid content and glucose uptake. Furthermore, quantitative real-time polymerase chain reaction showed that GPEP increased mRNA expression of GLUT4, fatty acid synthase, lipoprotein lipase, adiponectin, and peroxisome proliferator-activated receptor γ, while it decreased mRNA expression of leptin and Insig-1. Our results indicate that GPEP may induce adipocyte differentiation via upregulation of GLUT4, PI3K and adipogenic genes. Future research may be directed toward obese individuals with insulin resistance or individuals with diabetes.
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Affiliation(s)
- Sheida Torabi
- Department of Nutrition and Food Sciences and Institute for Women's Health, Texas Woman's University, Denton, TX 76204, USA
| | - Nancy M DiMarco
- Department of Nutrition and Food Sciences and Institute for Women's Health, Texas Woman's University, Denton, TX 76204, USA
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58
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Imai H, Misra GP, Wu L, Janagam DR, Gardner TW, Lowe TL. Subconjunctivally Implanted Hydrogels for Sustained Insulin Release to Reduce Retinal Cell Apoptosis in Diabetic Rats. Invest Ophthalmol Vis Sci 2016; 56:7839-46. [PMID: 26658505 DOI: 10.1167/iovs.15-16998] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Diabetic retinopathy (DR) is a leading cause of blindness in diabetic patients that involves early-onset retinal cell loss. Here, we report our recent work using subconjunctivally implantable hydrogels for sustained insulin release to the retina to prevent retinal degeneration. METHODS The hydrogels are synthesized by UV photopolymerization of N-isopropylacrylamide and a dextran macromer containing oligolactate-(2-hydroxyetheyl methacrylate) units. Insulin was loaded into the hydrogels during the synthesis. The ex vivo bioactivity of insulin released from the hydrogels was tested on fresh rat retinas using immunoprecipitation and immunoblotting to measure insulin receptor tyrosine and Akt phosphorylation. The biosafety and the effect on the blood glucose of the hydrogels were evaluated in rats 2 months after subconjunctival implantation. The release of insulin from the hydrogels was studied both in vitro in PBS (pH 7.4), and in vivo using confocal microscopy and RIA kit. The in vivo bioactivity of the released insulin was investigated in diabetic rats using DNA fragmentation method. RESULTS The hydrogels could load insulin with approximately 98% encapsulation efficiency and continuously release FITC-insulin in PBS (pH = 7.4) at 37°C for at least 5 months depending on their composition. Insulin lispro released from the hydrogels was biologically active by increasing insulin receptor tyrosine and Akt serine phosphorylation of ex vivo retinas. In vivo studies showed normal retinal histology 2 months post subconjunctival implantation. Insulin released from subconjunctivally implanted hydrogels could be detected in the retina by using confocal microscopy and RIA kit for 1 week. The implanted hydrogels with insulin lispro did not change the blood glucose level of normal and diabetic rats, but significantly reduced the DNA fragmentation of diabetic retinas for 1 week. CONCLUSIONS The developed hydrogels have great potential to sustain release of insulin to the retina via subconjunctival implantation to minimize DR without the risk of hypoglycemia.
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Affiliation(s)
- Hisanori Imai
- Department of Ophthalmology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States
| | - Gauri P Misra
- Department of Surgery, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States
| | - Linfeng Wu
- Department of Surgery, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States 3Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Dileep R Janagam
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Thomas W Gardner
- Department of Ophthalmology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States 4Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
| | - Tao L Lowe
- Department of Surgery, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States 3Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States
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59
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da Silva PGC, Domingues DD, de Carvalho LA, Allodi S, Correa CL. Neurotrophic factors in Parkinson's disease are regulated by exercise: Evidence-based practice. J Neurol Sci 2016; 363:5-15. [PMID: 27000212 DOI: 10.1016/j.jns.2016.02.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 02/05/2016] [Accepted: 02/07/2016] [Indexed: 12/24/2022]
Abstract
We carried out a qualitative review of the literature on the influence of forced or voluntary exercise in Parkinson's Disease (PD)-induced animals, to better understand neural mechanisms and the role of neurotrophic factors (NFs) involved in the improvement of motor behavior. A few studies indicated that forced or voluntary exercise may promote neuroprotection, through upregulation of NF expression, against toxicity of drugs that simulate PD. Forced training, such as treadmill exercise and forced-limb use, adopted in most studies, in addition to voluntary exercise on a running wheel are suitable methods for NFs upregulation.
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Affiliation(s)
- Paula Grazielle Chaves da Silva
- Laboratório de Neurobiologia Comparativa e do Desenvolvimento, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | - Daniel Desidério Domingues
- Laboratório de Neurobiologia Comparativa e do Desenvolvimento, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | - Litia Alves de Carvalho
- Laboratório de Neurobiologia Comparativa e do Desenvolvimento, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | - Silvana Allodi
- Laboratório de Neurobiologia Comparativa e do Desenvolvimento, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Programa de Pós-Graduação em Ciências Biológicas-Biofísica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | - Clynton Lourenço Correa
- Laboratório de Neurobiologia Comparativa e do Desenvolvimento, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Programa de Pós-Graduação em Educação Física, Universidade Federal do Rio de Janeiro, Brazil.
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60
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Hernández C, Bogdanov P, Corraliza L, García-Ramírez M, Solà-Adell C, Arranz JA, Arroba AI, Valverde AM, Simó R. Topical Administration of GLP-1 Receptor Agonists Prevents Retinal Neurodegeneration in Experimental Diabetes. Diabetes 2016; 65:172-87. [PMID: 26384381 DOI: 10.2337/db15-0443] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/08/2015] [Indexed: 11/13/2022]
Abstract
Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). Since glucagon-like peptide 1 (GLP-1) exerts neuroprotective effects in the central nervous system and the retina is ontogenically a brain-derived tissue, the aims of the current study were as follows: 1) to examine the expression and content of GLP-1 receptor (GLP-1R) in human and db/db mice retinas; 2) to determine the retinal neuroprotective effects of systemic and topical administration (eye drops) of GLP-1R agonists in db/db mice; and 3) to examine the underlying neuroprotective mechanisms. We have found abundant expression of GLP-1R in the human retina and retinas from db/db mice. Moreover, we have demonstrated that systemic administration of a GLP-1R agonist (liraglutide) prevents retinal neurodegeneration (glial activation, neural apoptosis, and electroretinographical abnormalities). This effect can be attributed to a significant reduction of extracellular glutamate and an increase of prosurvival signaling pathways. We have found a similar neuroprotective effect using topical administration of native GLP-1 and several GLP-1R agonists (liraglutide, lixisenatide, and exenatide). Notably, this neuroprotective action was observed without any reduction in blood glucose levels. These results suggest that GLP-1R activation itself prevents retinal neurodegeneration. Our results should open up a new approach in the treatment of the early stages of DR.
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Affiliation(s)
- Cristina Hernández
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
| | - Patricia Bogdanov
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
| | - Lidia Corraliza
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
| | - Marta García-Ramírez
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
| | - Cristina Solà-Adell
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
| | - José A Arranz
- Unidad de Metabolopatías, Laboratorios Clínicos, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Ana I Arroba
- CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Madrid, Spain
| | - Angela M Valverde
- CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Madrid, Spain
| | - Rafael Simó
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain CIBERDEM, Instituto de Salud Carlos III, Madrid, Spain
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61
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Hernández C, Dal Monte M, Simó R, Casini G. Neuroprotection as a Therapeutic Target for Diabetic Retinopathy. J Diabetes Res 2016; 2016:9508541. [PMID: 27123463 PMCID: PMC4830713 DOI: 10.1155/2016/9508541] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/29/2016] [Accepted: 03/16/2016] [Indexed: 02/07/2023] Open
Abstract
Diabetic retinopathy (DR) is a multifactorial progressive disease of the retina and a leading cause of vision loss. DR has long been regarded as a vascular disorder, although neuronal death and visual impairment appear before vascular lesions, suggesting an important role played by neurodegeneration in DR and the appropriateness of neuroprotective strategies. Upregulation of vascular endothelial growth factor (VEGF), the main target of current therapies, is likely to be one of the first responses to retinal hyperglycemic stress and VEGF may represent an important survival factor in early phases of DR. Of central importance for clinical trials is the detection of retinal neurodegeneration in the clinical setting, and spectral domain optical coherence tomography seems the most indicated technique. Many substances have been tested in animal studies for their neuroprotective properties and for possible use in humans. Perhaps, the most intriguing perspective is the use of endogenous neuroprotective substances or nutraceuticals. Together, the data point to the central role of neurodegeneration in the pathogenesis of DR and indicate neuroprotection as an effective strategy for treating this disease. However, clinical trials to determine not only the effectiveness and safety but also the compliance of a noninvasive route of drug administration are needed.
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Affiliation(s)
- Cristina Hernández
- CIBERDEM (CIBER de Diabetes y Enfermedades Metabolicas Asociadas) and Diabetes and Metabolism Research Unit, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autonoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
- *Cristina Hernández: and
| | - Massimo Dal Monte
- Department of Biology, University of Pisa, Via San Zeno 31, 56127 Pisa, Italy
- Interdepartmental Research Center Nutrafood “Nutraceuticals and Food for Health”, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy
| | - Rafael Simó
- CIBERDEM (CIBER de Diabetes y Enfermedades Metabolicas Asociadas) and Diabetes and Metabolism Research Unit, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autonoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Giovanni Casini
- Department of Biology, University of Pisa, Via San Zeno 31, 56127 Pisa, Italy
- Interdepartmental Research Center Nutrafood “Nutraceuticals and Food for Health”, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy
- *Giovanni Casini:
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Baptista FI, Castilho ÁF, Gaspar JM, Liberal JT, Aveleira CA, Ambrósio AF. Long-term exposure to high glucose increases the content of several exocytotic proteins and of vesicular GABA transporter in cultured retinal neural cells. Neurosci Lett 2015; 602:56-61. [PMID: 26141610 DOI: 10.1016/j.neulet.2015.06.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 06/21/2015] [Accepted: 06/22/2015] [Indexed: 11/21/2022]
Abstract
Diabetic retinopathy is a leading cause of vision loss and blindness. Increasing evidence has shown that the neuronal components of the retina are affected even before the detection of vascular lesions. Hyperglycemia is considered the main pathogenic factor for the development of diabetic complications. Nevertheless, other factors like neuroinflammation, might also contribute for neural changes. To clarify whether hyperglycemia can be the main trigger of synaptic changes, we evaluated whether prolonged elevated glucose per se, mimicking chronic hyperglycemia, is able to change the content and distribution of several exocytotic proteins and vesicular glutamate and GABA transporters in retinal neurons. Moreover, we also tested the hypothesis that an inflammatory stimulus (interleukin-1β) could exacerbate the effects induced by exposure to elevated glucose, contributing for changes in synaptic proteins in retinal neurons. Rat retinal neural cells were cultured for 9 days. Cells were exposed to elevated D-glucose (30 mM) or D-mannitol (osmotic control), for 7 days, or were exposed to interleukin-1β (10 ng/ml) or LPS (1 μg/ml) for 24 h. The protein content and distribution of SNARE proteins (SNAP-25, syntaxin-1, VAMP-2), synapsin-1, synaptotagmin-1, rabphilin 3a, VGluT-1 and VGAT, were evaluated by western blotting and immunocytochemistry. The protein content and immunoreactivity of syntaxin-1, synapsin-1, rabphilin 3a and VGAT increased in retinal neural cells exposed to high glucose. No changes were detected when cells were exposed to interleukin-1β, LPS or mannitol per se. Particularly, exposure to interleukin-1β for 24 h did not exacerbate the effect of high glucose on the content and immunoreactivity of exocytotic proteins, suggesting the primordial role of hyperglycemia for neuronal changes. In summary, prolonged exposure to elevated glucose alters the total content of several proteins involved in exocytosis, suggesting that hyperglycemia per se is a fundamental factor for neuronal changes caused by diabetes.
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Affiliation(s)
- Filipa I Baptista
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Áurea F Castilho
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana M Gaspar
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana T Liberal
- CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | | | - António F Ambrósio
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal; AIBILI, 3004-548 Coimbra, Portugal.
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63
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Chang P, Wang Q, Xu H, Yang M, Lin X, Li X, Zhang Z, Zhang X, Zhao F, Zhao X, Bai F, Yu J. Tetrahydrobiopterin reverse left ventricular hypertrophy and diastolic dysfunction through the PI3K/p-Akt pathway in spontaneously hypertensive rats. Biochem Biophys Res Commun 2015; 463:1012-20. [PMID: 26093301 DOI: 10.1016/j.bbrc.2015.06.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 06/08/2015] [Indexed: 11/23/2022]
Abstract
Hypertension induced hypertrophy and diastolic dysfunction and is associated with cardiac oxidation and reduced NO production. We hypothesized that tetrahydrobiopterin (BH4) can regulate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway and reverse cardiac hypertrophy and diastolic dysfunction in spontaneously hypertensive rats. Ten-week-old male spontaneously hypertensive rats (SHR) and age-matched normotensive control Wistar-Kyoto (WKY) rats were divided into five groups, WKY, WKY + BH4, SHR, SHR + BH4 and SHR + VAL. In SHR, diastolic dysfunction was accompanied by concentric hypertrophy, cardiac oxidation, and reduced cardiac BH4 and NO production. Four-week BH4 and valsartan administration reversed hypertrophy and improved diastolic function. BH4 and valsartan blunted the expression of hypertrophy markers α-skeletal actin (α-SA) and β-myosin heavy chain (β-MHC). Only BH4 reduced hypertension and induced myocardial fibrosis and expression of transforming growth factor-β1 (TGF-β1). BH4 reduced cardiac oxidant stress and increased NO production. Exogenous BH4 increased phosphorylated Akt levels and increased Bcl-2 expression. In conclusion, less BH4 and reduced NO increases myocardial hypertrophy and cardiac oxidative stress, which exacerbates diastolic dysfunction. Exogenous BH4 ameliorates cardiac hypertrophy and diastolic dysfunction through the PI3K/p-Akt pathway. BH4 may be a potent therapy for hypertension with diastolic dysfunction.
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Affiliation(s)
- Peng Chang
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Qiongying Wang
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Han Xu
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Mina Yang
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Xin Lin
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Xiuli Li
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Zhengyi Zhang
- Department of General Medicine, Lanzhou University Second Hospital, Gansu, China
| | - Xiaowei Zhang
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Feng Zhao
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Xu Zhao
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Feng Bai
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China
| | - Jing Yu
- Department of Cardiology, Lanzhou University Second Hospital, Gansu, China.
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64
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Gu RP, Fu LL, Jiang CH, Xu YF, Wang X, Yu J. Retina Is Protected by Neuroserpin from Ischemic/Reperfusion-Induced Injury Independent of Tissue-Type Plasminogen Activator. PLoS One 2015; 10:e0130440. [PMID: 26176694 PMCID: PMC4503687 DOI: 10.1371/journal.pone.0130440] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 05/20/2015] [Indexed: 11/18/2022] Open
Abstract
The purpose of the present study was to investigate the potential neuroprotective effect of neuroserpin (NSP) on acute retinal ischemic/reperfusion-induced (IR) injury. An IR injury model was established by elevating intraocular pressure (IOP) for 60 minutes in wild type and tPA-deficient (tPA-/-) mice. Prior to IR injury, 1 μL of 20 μmol/L NSP or an equal volume of bovine serum albumin (BSA) was intravitreally administered. Retinal function was evaluated by electroretinograph (ERG) and the number of apoptotic neurons was determined via TUNEL labeling. Caspase-3, -8, -9,poly (ADP-ribose) polymerase (PARP)and their cleaved forms were subsequently analyzed. It was found that IR injury significantly damaged retinal function, inducing apoptosis in the retina, while NSP attenuated the loss of retinal function and significantly reduced the number of apoptotic neurons in both wild type and tPA-/- mice. The levels of cleaved caspase-3, cleaved PARP (the substrate of caspase-3) and caspase-9 (the modulator of the caspase-3), which had increased following IR injury, were significantly inhibited by NSP in both wild type and tPA-/- mice. NSP increased ischemic tolerance in the retina at least partially by inhibiting the intrinsic cell death signaling pathway of caspase-3. It was therefore concluded that the protective effect of neuroserpin maybe independent from its canonical interaction with a tissue-type plasminogen activator.
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Affiliation(s)
- R. P. Gu
- Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
| | - L. L. Fu
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - C. H. Jiang
- Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
- Department of Ophthalmology, No. 5 people’s Hospital of Shanghai, Shanghai, 200240, China
| | - Y. F. Xu
- Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
| | - X. Wang
- Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
| | - J. Yu
- Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
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65
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Genes related with apoptosis by inflammation in diabetic keratocytes. Genes Genomics 2015. [DOI: 10.1007/s13258-015-0290-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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66
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Transgenic Mice Overexpressing Serum Retinol-Binding Protein Develop Progressive Retinal Degeneration through a Retinoid-Independent Mechanism. Mol Cell Biol 2015; 35:2771-89. [PMID: 26055327 DOI: 10.1128/mcb.00181-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 06/01/2015] [Indexed: 12/19/2022] Open
Abstract
Serum retinol-binding protein 4 (RBP4) is the sole specific transport protein for retinol in the blood, but it is also an adipokine with retinol-independent, proinflammatory activity associated with obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. Moreover, two separate studies reported that patients with proliferative diabetic retinopathy have increased serum RBP4 levels compared to patients with mild or no retinopathy, yet the effect of increased levels of RBP4 on the retina has not been studied. Here we show that transgenic mice overexpressing RBP4 (RBP4-Tg mice) develop progressive retinal degeneration, characterized by photoreceptor ribbon synapse deficiency and subsequent bipolar cell loss. Ocular retinoid and bisretinoid levels are normal in RBP4-Tg mice, demonstrating that a retinoid-independent mechanism underlies retinal degeneration. Increased expression of pro-interleukin-18 (pro-IL-18) mRNA and activated IL-18 protein and early-onset microglia activation in the retina suggest that retinal degeneration is driven by a proinflammatory mechanism. Neither chronic systemic metabolic disease nor other retinal insults are required for RBP4 elevation to promote retinal neurodegeneration, since RBP4-Tg mice do not have coincident retinal vascular pathology, obesity, dyslipidemia, or hyperglycemia. These findings suggest that elevation of serum RBP4 levels could be a risk factor for retinal damage and vision loss in nondiabetic as well as diabetic patients.
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Camargo LM, Zhang XD, Loerch P, Caceres RM, Marine SD, Uva P, Ferrer M, de Rinaldis E, Stone DJ, Majercak J, Ray WJ, Yi-An C, Shearman MS, Mizuguchi K. Pathway-based analysis of genome-wide siRNA screens reveals the regulatory landscape of APP processing. PLoS One 2015; 10:e0115369. [PMID: 25723573 PMCID: PMC4344212 DOI: 10.1371/journal.pone.0115369] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/14/2014] [Indexed: 01/08/2023] Open
Abstract
The progressive aggregation of Amyloid-β (Aβ) in the brain is a major trait of Alzheimer's Disease (AD). Aβ is produced as a result of proteolytic processing of the β-amyloid precursor protein (APP). Processing of APP is mediated by multiple enzymes, resulting in the production of distinct peptide products: the non-amyloidogenic peptide sAPPα and the amyloidogenic peptides sAPPβ, Aβ40, and Aβ42. Using a pathway-based approach, we analyzed a large-scale siRNA screen that measured the production of different APP proteolytic products. Our analysis identified many of the biological processes/pathways that are known to regulate APP processing and have been implicated in AD pathogenesis, as well as revealing novel regulatory mechanisms. Furthermore, we also demonstrate that some of these processes differentially regulate APP processing, with some mechanisms favouring production of certain peptide species over others. For example, synaptic transmission having a bias towards regulating Aβ40 production over Aβ42 as well as processes involved in insulin and pancreatic biology having a bias for sAPPβ production over sAPPα. In addition, some of the pathways identified as regulators of APP processing contain genes (CLU, BIN1, CR1, PICALM, TREM2, SORL1, MEF2C, DSG2, EPH1A) recently implicated with AD through genome wide association studies (GWAS) and associated meta-analysis. In addition, we provide supporting evidence and a deeper mechanistic understanding of the role of diabetes in AD. The identification of these processes/pathways, their differential impact on APP processing, and their relationships to each other, provide a comprehensive systems biology view of the “regulatory landscape” of APP.
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Affiliation(s)
- Luiz Miguel Camargo
- Merck Research Laboratories, Merck & Co, Boston, United States of America
- * E-mail:
| | | | - Patrick Loerch
- Merck Research Laboratories, Merck & Co, Boston, United States of America
| | | | - Shane D. Marine
- Merck Research Laboratories, Merck & Co, North Wales, United States of America
| | - Paolo Uva
- Merck Research Laboratories, Instituto di Recerca di Biologia Molecolare, Pomezia, Italy
| | - Marc Ferrer
- Merck Research Laboratories, Merck & Co, North Wales, United States of America
| | - Emanuele de Rinaldis
- Merck Research Laboratories, Instituto di Recerca di Biologia Molecolare, Pomezia, Italy
| | - David J. Stone
- Merck Research Laboratories, Merck & Co, West Point, United States of America
| | - John Majercak
- Merck Research Laboratories, Merck & Co, West Point, United States of America
| | - William J. Ray
- Merck Research Laboratories, Merck & Co, West Point, United States of America
| | - Chen Yi-An
- National Institute of Biomedical Innovation, Osaka, Japan
| | - Mark S. Shearman
- Merck Research Laboratories, Merck & Co, Boston, United States of America
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Boriushkin E, Wang JJ, Li J, Jing G, Seigel GM, Zhang SX. Identification of p58IPK as a novel neuroprotective factor for retinal neurons. Invest Ophthalmol Vis Sci 2015; 56:1374-86. [PMID: 25655802 DOI: 10.1167/iovs.14-15196] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PURPOSE Endoplasmic reticulum (ER)-resident chaperone protein p58(IPK) plays a vital role in regulation of protein folding and biosynthesis. The goal of this study was to examine the role of p58(IPK) in retinal neuronal cells under normal and stressed conditions. METHODS Retinal expression of p58(IPK), retinal morphology, apoptosis, ER stress, and apoptotic gene expression were examined in p58(IPK) knockout (KO) and/or wild-type (WT) mice with or without intravitreal injection of N-methyl-D-aspartic acid (NMDA). In in vitro experiments, differentiated R28 retinal neuronal cells transduced with adenovirus encoding p58(IPK) (Ad-p58(IPK)) or control virus (Ad-LacZ) were exposed to tunicamycin (TM) or hydrogen peroxide (H2O2). Levels of ER stress, apoptosis, and cell survival were evaluated. RESULTS Chaperone protein p58(IPK) is expressed predominantly in retinal ganglion cells (RGC), inner retinal neurons, and the photoreceptor inner segments. Mice lacking p58(IPK) exhibited increased CHOP expression and loss of RGCs with aging (8-10 months). Intravitreal injection of NMDA induced retinal ER stress and increased p58(IPK) expression in WT mice; this resulted in greater ER stress and enhanced RGC apoptosis in p58(IPK) KO mice. In cultured R28 cells, overexpression of p58(IPK) significantly reduced eIF2α phosphorylation, decreased CHOP expression, and alleviated the activation of caspase-3 and PARP. Overexpression of p58(IPK) also protected against oxidative and ER stress-induced cell apoptosis. Furthermore, p58(IPK) downregulated the proapoptotic gene Bax and upregulated the antiapoptotic gene Bcl-2 expression in stressed R28 cells. CONCLUSIONS Our study has demonstrated a protective role of p58(IPK) in retinal neurons, which may act in part through a mechanism involving modulation of ER homeostasis and apoptosis, particularly under conditions of cellular stresses.
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Affiliation(s)
- Evgenii Boriushkin
- Department of Ophthalmology and Biochemistry/Ross Eye Institute, University at Buffalo/SUNY, Buffalo, New York, United States SUNY Eye Institute, State University of New York, Buffalo, New York, United States
| | - Joshua J Wang
- Department of Ophthalmology and Biochemistry/Ross Eye Institute, University at Buffalo/SUNY, Buffalo, New York, United States
| | - Junhua Li
- Department of Ophthalmology and Biochemistry/Ross Eye Institute, University at Buffalo/SUNY, Buffalo, New York, United States SUNY Eye Institute, State University of New York, Buffalo, New York, United States
| | - Guangjun Jing
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Gail M Seigel
- SUNY Eye Institute, State University of New York, Buffalo, New York, United States Center for Hearing & Deafness, University at Buffalo, Buffalo/SUNY, New York, United States
| | - Sarah X Zhang
- Department of Ophthalmology and Biochemistry/Ross Eye Institute, University at Buffalo/SUNY, Buffalo, New York, United States
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Ola MS, Alhomida AS. Neurodegeneration in diabetic retina and its potential drug targets. Curr Neuropharmacol 2014; 12:380-6. [PMID: 25342945 PMCID: PMC4207077 DOI: 10.2174/1570159x12666140619205024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/27/2014] [Accepted: 06/19/2014] [Indexed: 12/04/2022] Open
Abstract
Diabetic retinopathy (DR) is one of the major complications of diabetes causing vision loss and blindness worldwide. DR is widely recognized as a neurodegenerative disease as evidenced from early changes at cellular and molecular levels in the neuronal component of the diabetic retina, which is further supported by various retinal functional tests indicating functional deficits in the retina soon after diabetes progression. Diabetes alters the level of a number of neurodegenerative metabolites, which increases influx through several metabolic pathways which in turn induce an increase in oxidative stress and a decrease in neurotrophic factors, thereby damage retinal neurons. Loss of neurons may implicate in vascular pathology, a clinical signs of DR observed at later stages of the disease. Here, we discuss diabetes-induced potential metabolites known to be detrimental to neuronal damage and their mechanism of action. In addition, we highlight important neurotrophic factors, whose level have been found to be dysregulated in diabetic retina and may damage neurons. Furthermore, we discuss potential drugs and strategies based on targeting diabetes-induced metabolites, metabolic pathways, oxidative stress, and neurotrophins to protect retinal neurons, which may ameliorate vision loss and vascular damage in DR.
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Affiliation(s)
- Mohammad Shamsul Ola
- Department of Biochemistry, College of Science, King Saud University, Riyadh, KSA, Saudi Arabia
| | - Abdullah S Alhomida
- Department of Biochemistry, College of Science, King Saud University, Riyadh, KSA, Saudi Arabia
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Wang H, Liao S, Geng R, Zheng Y, Liao R, Yan F, Thrimawithana T, Little PJ, Feng ZP, Lazarovici P, Zheng W. IGF-1 signaling via the PI3K/Akt pathway confers neuroprotection in human retinal pigment epithelial cells exposed to sodium nitroprusside insult. J Mol Neurosci 2014; 55:931-40. [PMID: 25339505 DOI: 10.1007/s12031-014-0448-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/13/2014] [Indexed: 02/01/2023]
Abstract
The pathological increase in the levels of the second messenger nitric oxide (NO) in the vitreous cavity and retina leads to injury and cell death of the retinal pigment epithelium (RPE) cells and eventually may contribute to the occurrence and development of diabetic retinopathy. In this study, we developed a cellular model of retinopathy using D407 cells (a human RPE cell line) exposed to sodium nitroprusside (SNP) and investigated the protective effect of the insulin-like growth factor-1 (IGF-1) towards this insult. Cell death and apoptosis were examined by the methyl thiazolyl tetrazolium assay and Hoechst staining, respectively. Specific inhibitors were used and phosphorylation of relevant signaling proteins was determined by Western blotting. SNP, in a concentration-dependent fashion, increased the production of reactive oxygen species (ROS) and lipid peroxidation process causing cell death by apoptosis of D407 cells. IGF-1, in a time- and dose-dependent manner, conferred protection towards SNP-mediated insult. Both phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase (MAPK) were activated by IGF-1 in relation to the protective effect. Blockade of the PI3K/Akt pathway abolished the protective effect of IGF-1 whereas inhibition of the MAPK pathway was ineffective. SNP decreased the phosphorylation of Akt in the cells while IGF-1 reversed this inhibitory effect. These results indicate that the protective effect of IGF-1 on D407 exposed to SNP insult is mediated by the PI3K/Akt pathway. This proposal may be exploited in the clinic to improve the viability of insulted retinal cells for maintaining physiological vision.
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Affiliation(s)
- Haitao Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
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Yang SD, Bai ZL, Zhang F, Ma L, Yang DL, Ding WY. Levofloxacin increases the effect of serum deprivation on anoikis of rat nucleus pulposus cells via Bax/Bcl-2/caspase-3 pathway. Toxicol Mech Methods 2014; 24:688-96. [PMID: 25224805 DOI: 10.3109/15376516.2014.963772] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Levofloxacin, a fluoroquinolone, is a widely-used and effective antibiotic. However, various adverse side effects are associated with levofloxacin. The purpose of this study was to further explore the effects of levofloxacin on rat nucleus pulposus cells (NPCs). Inverted phase-contrast microscopy, flow cytometry and caspase-3 activity assays were used and revealed that serum deprivation induced apoptosis, which was markedly increased by levofloxacin in a dose-dependent manner. Simultaneously, levofloxacin decreased cell binding to type II collagen (COL2). Thus, levofloxacin-induced apoptosis exhibits characteristics of anoikis, the process by which cell death is triggered by separation from the extracellular matrix, which contains COL2. Furthermore, real-time quantitative RT-PCR was used to further confirm that levofloxacin downregulates COL2 expression in a dose-dependent manner. At last, western blot was used to find that levofloxacin increased the ratio of Bax/Bcl-2 and active caspase-3 in a dose-dependent manner. Levofloxacin therefore increases the effects of serum deprivation on anoikis by downregulating COL2 in rat NPCs in vitro via Bax/Bcl-2/caspase-3 pathway. This research provides a novel insight into the mechanisms of levofloxacin-induced toxicity and may potentially lead to a better understanding of the clinical effects of levofloxacin, especially in terms of intervertebral disc degeneration.
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72
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Kuang H, Sun M, Lv J, Li J, Wu C, Chen N, Bo L, Wei X, Gu X, Liu Z, Mao C, Xu Z. Hippocampal apoptosis involved in learning deficits in the offspring exposed to maternal high sucrose diets. J Nutr Biochem 2014; 25:985-90. [DOI: 10.1016/j.jnutbio.2014.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/28/2014] [Accepted: 04/26/2014] [Indexed: 01/24/2023]
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Rajasekar N, Dwivedi S, Nath C, Hanif K, Shukla R. Protection of streptozotocin induced insulin receptor dysfunction, neuroinflammation and amyloidogenesis in astrocytes by insulin. Neuropharmacology 2014; 86:337-52. [PMID: 25158313 DOI: 10.1016/j.neuropharm.2014.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 08/12/2014] [Accepted: 08/14/2014] [Indexed: 01/04/2023]
Abstract
Impaired insulin signaling, amyloid pathology and neuroinflammation are closely associated with neurodegenerative disorder like Alzheimer's disease (AD). Our earlier studies showed that intracerebroventricular streptozotocin (STZ) induces insulin receptor (IR) signaling defect in the hippocampus, which is associated with memory impairment in rats. Astrocytes are the most abundant cells in the brain and play a major role in neuroinflammation. However, involvement of astrocytes in STZ induced IR dysfunction has not received much attention. Therefore, the present study was planned to explore the effect of STZ on IR signaling, proinflammatory markers and amyloidogenesis in rat astrocytoma cell line, (C6). STZ (100 μM) treatment in astrocytes (n = 3) for 24 h, resulted significant decrease in IR mRNA and protein expression, phosphorylation of IRS-1, Akt, GSK-3α and GSK-3β (p < 0.01). Further STZ induced amyloidogenic protein expression as evidenced by the increase in APP, BACE-1 and Aβ1-42 expression (p < 0.05) in astrocytes. STZ also significantly induced astrocytes activation as evidenced by increased expression of GFAP and p-P38 MAPK (p < 0.05). STZ treatment caused enhanced translocation of p65 NF-kB, triggered over expression of TNF-α, IL-1β, COX-2, oxidative/nitrosative stress and caspase activation (p < 0.05) in astrocytes. Insulin (25-100 nM) pretreatment (n = 3) significantly prevented changes in IR signaling, amyloidogenic protein expression and levels of proinflammatory markers (p < 0.05) in STZ treated astroglial cells. In the present study, the protective effect of insulin suggests that, IR dysfunction along with amyloidogenesis and neuroinflammation may have played a major role in STZ induced toxicity in astrocytes which are relevant to AD pathology.
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Affiliation(s)
- N Rajasekar
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Subhash Dwivedi
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Chandishwar Nath
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Kashif Hanif
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Rakesh Shukla
- Divisions of Pharmacology and Toxicology, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), India.
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Baptista FI, Pinto MJ, Elvas F, Martins T, Almeida RD, Ambrósio AF. Diabetes induces changes in KIF1A, KIF5B and dynein distribution in the rat retina: implications for axonal transport. Exp Eye Res 2014; 127:91-103. [PMID: 25064602 DOI: 10.1016/j.exer.2014.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
Abstract
Diabetic retinopathy is a leading cause of vision loss and blindness. Disruption of axonal transport is associated with many neurodegenerative diseases and might also play a role in diabetes-associated disorders affecting nervous system. We investigated the impact of type 1 diabetes (2 and 8 weeks duration) on KIF1A, KIF5B and dynein motor proteins in the retina. Additionally, since hyperglycemia is considered the main trigger of diabetic complications, we investigated whether prolonged exposure to elevated glucose could affect the content and distribution of motor proteins in retinal cultures. The immunoreactivity of motor proteins was evaluated by immunohistochemistry in retinal sections and by immunoblotting in total retinal extracts from streptozotocin-induced diabetic and age-matched control animals. Primary retinal cultures were exposed to high glucose (30 mM) or mannitol (osmotic control; 24.5 mM plus 5.5 mM glucose), for seven days. Diabetes decreased the content of KIF1A at 8 weeks of diabetes as well as KIF1A immunoreactivity in the majority of retinal layers, except for the photoreceptor and outer nuclear layer. Changes in KIF5B immunoreactivity were also detected by immunohistochemistry in the retina at 8 weeks of diabetes, being increased at the photoreceptor and outer nuclear layer, and decreased in the ganglion cell layer. Regarding dynein immunoreactivity there was an increase in the ganglion cell layer after 8 weeks of diabetes. No changes were detected in retinal cultures. These alterations suggest that axonal transport may be impaired under diabetes, which might contribute to early signs of neural dysfunction in the retina of diabetic patients and animal models.
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Affiliation(s)
- Filipa I Baptista
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Maria J Pinto
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; PhD Programme in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Filipe Elvas
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Tiago Martins
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Ramiro D Almeida
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - António F Ambrósio
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; AIBILI, 3004-548 Coimbra, Portugal.
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75
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Ghasemi R, Zarifkar A, Rastegar K, maghsoudi N, Moosavi M. Insulin protects against Aβ-induced spatial memory impairment, hippocampal apoptosis and MAPKs signaling disruption. Neuropharmacology 2014; 85:113-20. [PMID: 24881967 DOI: 10.1016/j.neuropharm.2014.01.036] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 01/15/2014] [Accepted: 01/21/2014] [Indexed: 12/26/2022]
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disease characterized by extracellular deposits of beta amyloid (Aβ) and neuronal loss particularly in the hippocampus. Accumulating evidences have implied that insulin signaling impairment plays a key role in the pathology of AD; as much as it is considered as type 3 Diabetes. MAPKs are a group of signaling molecules which are involved in pathobiology of AD. Therefore this study was designed to investigate if intrahippocampal insulin hinders Aβ-related memory deterioration, hippocampal apoptosis and MAPKs signaling alteration induced by Aβ. Adult male Sprague-Dawely rats weighing 250-300 g were used in this study. The canules were implanted bilaterally into CA1 region. Aβ25-35 was administered during first 4 days after surgery (5 μg/2.5 μL/daily). Insulin treatment (0.5 or 6 mU) was done during days 4-9. The animal's learning and memory capability was assessed on days 10-13 using Morris water maze. After finishing of behavioral studies the hippocampi was isolated and the amount of hippocampal cleaved caspase 3 (the landmark of apoptosis) and the phosphorylated (activated) forms of P38, JNK and ERK was analyzed by western blot. The results showed that insulin in 6 but not 0.5 mU reversed the memory loss induced by Aβ25-35. Western blot analysis revealed that Aβ25-35 induced elevation of caspase-3 and all 3 MAPks subfamily activity, while insulin in 6 mu restored ERK and P38 activation but has no effect on JNK. This study disclosed that intrahippocampal insulin treatment averts not only Aβ-induced memory deterioration but also hippocampal caspase-3, ERK and P38 activation.
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Affiliation(s)
- Rasoul Ghasemi
- Department of Physiology and Shiraz Neuroscience Research Centre, Shiraz University of Medical sciences, Shiraz, Iran
| | - Asadollah Zarifkar
- Department of Physiology and Shiraz Neuroscience Research Centre, Shiraz University of Medical sciences, Shiraz, Iran.
| | - Karim Rastegar
- Department of Physiology and Shiraz Neuroscience Research Centre, Shiraz University of Medical sciences, Shiraz, Iran
| | - Nader maghsoudi
- Neuroscience Research Centre, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Moosavi
- Department of Physiology and Shiraz Neuroscience Research Centre, Shiraz University of Medical sciences, Shiraz, Iran.
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76
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Retinal neurodegenerative changes in the adult insulin receptor substrate-2 deficient mouse. Exp Eye Res 2014; 124:1-10. [PMID: 24792588 DOI: 10.1016/j.exer.2014.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/17/2014] [Accepted: 04/22/2014] [Indexed: 11/23/2022]
Abstract
Insulin receptor substrate-2 (Irs2) mediates peripheral insulin action and is essential for retinal health. Previous investigations have reported severe photoreceptor degeneration and abnormal visual function in Irs2-deficient mice. However, molecular changes in the Irs2(-)(/)(-) mouse retina have not been described. In this study, we examined retinal degenerative changes in neuronal and glial cells of adult (9- and 12-week old) Irs2(-)(/)(-) mice by immunohistochemistry. 9-week old Irs2(-)(/)(-) mice showed significant thinning of outer retinal layers, concomitant to Müller and microglial cell activation. Photoreceptor cells displayed different signs of degeneration, such as outer/inner segment atrophy, redistribution of rod- and cone-opsins and spatial disorganization of cone cells. This was accompanied by synaptic changes at the outer plexiform layer, including the retraction of rod-spherules, reduction of photoreceptor synaptic ribbons and synaptic remodeling in second order neurons (i.e. loss and sprouting of dendritic processes in rod bipolar and horizontal cells). By 12 weeks of age, the thickness of inner retinal layers was severely affected. Although inner plexiform layer stratification remained unchanged at this stage, rod bipolar cell axon terminals were significantly depleted. Significant loss of Brn3a(+) retinal ganglion cells occurred in 12-week old Irs2(-)(/)(-) mice, in contrast to younger ages. Adult Irs2(-)(/)(-) mice showed clear hallmarks of neurodegeneration and disruption of the inner retina with increasing age. Pharmacological stimulation of Irs2 signaling pathway may provide additional neuroprotection in certain degenerative retinopathies.
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77
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Abcouwer SF, Gardner TW. Diabetic retinopathy: loss of neuroretinal adaptation to the diabetic metabolic environment. Ann N Y Acad Sci 2014; 1311:174-90. [PMID: 24673341 DOI: 10.1111/nyas.12412] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Diabetic retinopathy (DR) impairs vision of patients with type 1 and type 2 diabetes, associated with vascular dysfunction and occlusion, retinal edema, hemorrhage, and inappropriate growth of new blood vessels. The recent success of biologic treatments targeting vascular endothelial growth factor (VEGF) demonstrates that treating the vascular aspects in the later stages of the disease can preserve vision in many patients. It would also be highly desirable to prevent the onset of the disease or arrest its progression at a stage preceding the appearance of overt microvascular pathologies. The progression of DR is not necessarily linear but may follow a series of steps that evolve over the course of multiple years. Abundant data suggest that diabetes affects the entire neurovascular unit of the retina, with an early loss of neurovascular coupling, gradual neurodegeneration, gliosis, and neuroinflammation occurring before observable vascular pathologies. In this article, we consider the pathology of DR from the point of view that diabetes causes measurable dysfunctions in the complex integral network of cell types that produce and maintain human vision.
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Affiliation(s)
- Steven F Abcouwer
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan
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Celik F, Ulaş F, Ozünal ZG, Fırat T, Celebi S, Doğan U. Comparison of the effect of intravitreal bevacizumab and intravitreal fasudil on retinal VEGF, TNFα, and caspase 3 levels in an experimental diabetes model. Int J Ophthalmol 2014; 7:57-61. [PMID: 24634864 DOI: 10.3980/j.issn.2222-3959.2014.01.10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/27/2013] [Indexed: 02/06/2023] Open
Abstract
AIM To evaluate the influence of an intravitreal injection of bevacizumab and fasudil on the retinal vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNFα), and caspase 3 levels in a diabetic rabbit model. METHODS The study included 6 healthy rabbits (Group 1), 6 rabbits with experimentally induced diabetes mellitus (DM) (Group 2), 7 rabbits with experimentally induced DM to which intravitreal bevacizumab was administered (Group 3), and 7 rabbits with experimentally induced DM to which intravitreal fasudil was administered (Group 4). An intravitreal injection of 1.25mg/50µL bevacizumab in the right eye of rabbits in Group 3 and an intravitreal injection of 0.0064mg/50µL fasudil in the right eye of rabbits in Group 4 were administered on day 21 after the induction of DM. The studied eyes of the rabbits were enucleated three days after the intravitreal injection. The TNFα, VEGF, and caspase 3 levels were determined using the ELISA method. RESULTS There was a statistically significant difference in the VEGF and caspase 3 levels between groups (P=0.005 and P =0.013, respectively), but the TNFα level did not differ significantly between groups (P=0.792). It was found that VEGF levels were significantly lower in Group 1 and Group 3 than in Group 2 using the Mann-Whitney U test with the Bonferroni correction (P=0.004 for both comparison). There was no statistically significant difference between other groups with regard to VEGF levels (the P value ranged between 0.015 and 0.886). Although the P values of the caspase 3 levels were 0.015 for Group 1 and Group 4, 0.038 for Group 2 and Group 3, and 0.018 for Group 3 and Group 4, these P values remained above the threshold P value of 0.0083, which was the statistically significant level for post hoc tests. CONCLUSION An intravitreal injection of bevacizumab decreased both the VEGF level, which plays a role in angiogenesis, and the caspase 3 level, which plays a role in apoptosis. Although not as effective as bevacizumab, fasudil had a beneficial effect on the VEGF levels but significantly increased the caspase 3 levels.
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Affiliation(s)
- Fatih Celik
- Department of Ophthalmology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
| | - Fatih Ulaş
- Department of Ophthalmology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
| | - Zeynep Güneş Ozünal
- Department of Medical Pharmacology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
| | - Tülin Fırat
- Department of Histology and Embryology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
| | - Serdal Celebi
- Department of Ophthalmology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
| | - Umit Doğan
- Department of Ophthalmology, Faculty of Medicine, Abant Izzet Baysal University, Bolu 14280, Turkey
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79
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Propranolol inhibits growth of hemangioma-initiating cells but does not induce apoptosis. Pediatr Res 2014; 75:381-8. [PMID: 24296797 PMCID: PMC3951485 DOI: 10.1038/pr.2013.231] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/26/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND Infantile hemangioma (IH) is the most common tumor of infancy. The first-line therapy for IH is propranolol, a nonselective β-adrenergic receptor antagonist. However, mechanisms for the therapeutic effect of propranolol and regrowth of IH following cessation of treatment in some cases are not clear. We have recently shown that IH arises from multipotent stem cells. Whether IH stem cells are responsive to propranolol and are selectively targeted is unknown, and this is the focus of this study. METHODS IH stem cells were exposed to propranolol and were assayed for cellular and molecular alterations. We used endothelial cells (ECs) as controls and bone marrow-derived mesenchymal progenitor cells (bm-MPCs) as normal stem/progenitor counterparts to determine selectivity. RESULTS Our results show that propranolol significantly reduced IH stem cell growth but failed to induce caspase-3 activation. Normal bm-MPCs and mature ECs showed maintained or increased caspase-3 activation and significantly reduced cyclin-D1 levels. We further show that IH stem cells may escape apoptosis by inducing antiapoptotic pathways. CONCLUSION This study reveals that propranolol does not induce apoptosis in IH stem cells, which is in contrast with the result for ECs. Escape from apoptosis in IH stem cells may involve induction of antiapoptotic pathways.
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80
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Insulin, IGF-1 and GLP-1 signaling in neurodegenerative disorders: targets for disease modification? Prog Neurobiol 2014; 118:1-18. [PMID: 24582776 DOI: 10.1016/j.pneurobio.2014.02.005] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 02/09/2014] [Accepted: 02/20/2014] [Indexed: 12/13/2022]
Abstract
Insulin and Insulin Growth Factor-1 (IGF-1) play a major role in body homeostasis and glucose regulation. They also have paracrine/autocrine functions in the brain. The Insulin/IGF-1 signaling pathway contributes to the control of neuronal excitability, nerve cell metabolism and cell survival. Glucagon like peptide-1 (GLP-1), known as an insulinotropic hormone has similar functions and growth like properties as insulin/IGF-1. Growing evidence suggests that dysfunction of these pathways contribute to the progressive loss of neurons in Alzheimer's disease (AD) and Parkinson's disease (PD), the two most frequent neurodegenerative disorders. These findings have led to numerous studies in preclinical models of neurodegenerative disorders targeting insulin/IGF-1 and GLP-1 signaling with currently available anti-diabetics. These studies have shown that administration of insulin, IGF-1 and GLP-1 agonists reverses signaling abnormalities and has positive effects on surrogate markers of neurodegeneration and behavioral outcomes. Several proof-of-concept studies are underway that attempt to translate the encouraging preclinical results to patients suffering from AD and PD. In the first part of this review, we discuss physiological functions of insulin/IGF-1 and GLP-1 signaling pathways including downstream targets and receptors distribution within the brain. In the second part, we undertake a comprehensive overview of preclinical studies targeting insulin/IGF-1 or GLP-1 signaling for treating AD and PD. We then detail the design of clinical trials that have used anti-diabetics for treating AD and PD patients. We close with future considerations that treat relevant issues for successful translation of these encouraging preclinical results into treatments for patients with AD and PD.
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81
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Szabadfi K, Pinter E, Reglodi D, Gabriel R. Neuropeptides, trophic factors, and other substances providing morphofunctional and metabolic protection in experimental models of diabetic retinopathy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 311:1-121. [PMID: 24952915 DOI: 10.1016/b978-0-12-800179-0.00001-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vision is the most important sensory modality for many species, including humans. Damage to the retina results in vision loss or even blindness. One of the most serious complications of diabetes, a disease that has seen a worldwide increase in prevalence, is diabetic retinopathy. This condition stems from consequences of pathological metabolism and develops in 75% of patients with type 1 and 50% with type 2 diabetes. The development of novel protective drugs is essential. In this review we provide a description of the disease and conclude that type 1 diabetes and type 2 diabetes lead to the same retinopathy. We evaluate existing experimental models and recent developments in finding effective compounds against this disorder. In our opinion, the best models are the long-term streptozotocin-induced diabetes and Otsuka Long-Evans Tokushima Fatty and spontaneously diabetic Torii rats, while the most promising substances are topically administered somatostatin and pigment epithelium-derived factor analogs, antivasculogenic substances, and systemic antioxidants. Future drug development should focus on these.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - Erika Pinter
- Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary; Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary
| | - Dora Reglodi
- Department of Anatomy, PTE MTA Lendulet-PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary
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82
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Woo JE, Kwon MY, Chung SW, Woo JM. Expression of TonEBP by Hypertonic and Hyperosmolar Stress in RGC-5 Cells. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2014. [DOI: 10.3341/jkos.2014.55.8.1195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Jong Eun Woo
- Department of Ophthalmology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
| | - Min Young Kwon
- School of Biological Sciences, College of Natural Science, University of Ulsan, Ulsan, Korea
| | - Su Wol Chung
- School of Biological Sciences, College of Natural Science, University of Ulsan, Ulsan, Korea
| | - Je Moon Woo
- Department of Ophthalmology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
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83
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Jung SY, Kim DY, Yune TY, Shin DH, Baek SB, Kim CJ. Treadmill exercise reduces spinal cord injury-induced apoptosis by activating the PI3K/Akt pathway in rats. Exp Ther Med 2013; 7:587-593. [PMID: 24520250 PMCID: PMC3919853 DOI: 10.3892/etm.2013.1451] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/19/2013] [Indexed: 01/05/2023] Open
Abstract
Apoptosis occurring secondary to spinal cord injury (SCI) causes further neural damage and functional loss. In this study, a rat model was used to investigate the effect of treadmill exercise on SCI-induced apoptosis and expression of neurotrophic factors. To produce SCI, a contusion injury (10 g × 25 mm) was applied subsequent to laminectomy at the T9–T10 level. Following SCI, treadmill exercise was performed for six weeks. Hindlimb motor function was evaluated with a grid-walking test. The expression of neurotrophic factors and the level of apoptosis at the site of SCI were determined by western blotting. SCI reduced hindlimb motor function and suppressed expression of neurotrophin (NT)-3 and insulin-like growth factor (IGF)-1. Expression of phosphatidylinositol 3-kinase (PI3K), the ratio of phosphorylated Akt to Akt (pAkt/Akt) and the ratio of B-cell lymphoma 2 (Bcl-2) to Bax (Bcl-2/Bax) were decreased, and cleaved caspase-3 expression was increased by SCI. Treadmill exercise enhanced hindlimb motor function and increased expression of nerve growth factor (NGF), NT-3 and IGF-1 in the SCI rats. Treadmill exercise increased PI3K expression, the pAkt/Akt and the Bcl-2/Bax ratios, and suppressed cleaved caspase-3 expression in the injured spinal cord. This study demonstrated that treadmill exercise promotes the recovery of motor function by suppressing apoptosis in the injured spinal cord. The beneficial effect of exercise may be attributed to the increase in expression of neurotrophic factors via activation of the PI3K/Akt pathway.
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Affiliation(s)
- Sun-Young Jung
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea
| | - Dae-Young Kim
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea
| | - Tae Young Yune
- Department of Biochemistry and Molecular Biology, Age-Related and Brain Diseases Research Centre, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea
| | - Dong-Hoon Shin
- Department of Food and Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Sang-Bin Baek
- Department of Psychiatry, Gangneung Asan Hospital, Ulsan University, Gangneung 210-711, Republic of Korea
| | - Chang-Ju Kim
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul 136-701, Republic of Korea
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84
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Kato S, Matsukawa T, Koriyama Y, Sugitani K, Ogai K. A molecular mechanism of optic nerve regeneration in fish: the retinoid signaling pathway. Prog Retin Eye Res 2013; 37:13-30. [PMID: 23994437 DOI: 10.1016/j.preteyeres.2013.07.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/30/2013] [Accepted: 07/30/2013] [Indexed: 12/20/2022]
Abstract
The fish optic nerve regeneration process takes more than 100 days after axotomy and comprises four stages: neurite sprouting (1-4 days), axonal elongation (5-30 days), synaptic refinement (35-80 days) and functional recovery (100-120 days). We screened genes specifically upregulated in each stage from axotomized fish retina. The mRNAs for heat shock protein 70 and insulin-like growth factor-1 rapidly increased in the retinal ganglion cells soon after axotomy and function as cell-survival factors. Purpurin mRNA rapidly and transiently increased in the photoreceptors and purpurin protein diffusely increased in all nuclear layers at 1-4 days after injury. The purpurin gene has an active retinol-binding site and a signal peptide. Purpurin with retinol functions as a sprouting factor for thin neurites. This neurite-sprouting effect was closely mimicked by retinoic acid and blocked by its inhibitor. We propose that purpurin works as a retinol transporter to supply retinoic acid to damaged RGCs which in turn activates target genes. We also searched for genes involved in the second stage of regeneration. The mRNA of retinoid-signaling molecules increased in retinal ganglion cells at 7-14 days after injury and tissue transglutaminase and neuronal nitric oxide synthase mRNAs, RA-target genes, increased in retinal ganglion cells at 10-30 days after injury. They function as factors for the outgrowth of thick, long neurites. Here we present a retinoid-signaling hypothesis to explain molecular events during the early stages of optic nerve regeneration in fish.
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Affiliation(s)
- Satoru Kato
- Department of Molecular Neurobiology, Graduate School of Medicine, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8640, Japan.
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85
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Rajala A, Gupta VK, Anderson RE, Rajala RVS. Light activation of the insulin receptor regulates mitochondrial hexokinase. A possible mechanism of retinal neuroprotection. Mitochondrion 2013; 13:566-76. [PMID: 23993956 DOI: 10.1016/j.mito.2013.08.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/03/2013] [Accepted: 08/15/2013] [Indexed: 12/23/2022]
Abstract
The serine/threonine kinase Akt has been shown to mediate the anti-apoptotic activity through hexokinase (HK)-mitochondria interaction. We previously reported that Akt activation in retinal rod photoreceptor cells is mediated through the light-dependent insulin receptor (IR)/PI3K pathway. Our data indicate that light-induced activation of IR/PI3K/Akt results in the translocation of HK-II to mitochondria. We also found that PHLPPL, a serine/threonine phosphatase, enhanced the binding of HK-II to mitochondria. We found a mitochondrial targeting signal in PHLPPL and our study suggests that Akt translocation to mitochondria could be mediated through PHLPPL. Our results suggest that the light-dependent IR/PI3K/Akt pathway regulates hexokinase-mitochondria interaction in photoreceptors. Down-regulation of IR signaling has been associated with ocular diseases of retinitis pigmentosa, diabetic retinopathy, and Leber Congenital Amaurosis-type 2, and agents that enhance the binding interaction between hexokinase and mitochondria may have therapeutic potential against these ocular diseases.
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Affiliation(s)
- Ammaji Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK 73104, USA
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86
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Chihara E. Myopia and diabetes mellitus as modificatory factors of glaucomatous optic neuropathy. Jpn J Ophthalmol 2013; 58:16-25. [PMID: 23942995 DOI: 10.1007/s10384-013-0267-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 06/19/2013] [Indexed: 12/16/2022]
Abstract
Myopic deformation of the eye and metabolic alterations of the nerve tissue of patients with diabetes may modify glaucomatous optic neuropathy (GON). Blockage of axonal transport of neurotrophic factors (NTFs) is the event crucial to understanding the factors that affect GON. The primary, but not sole, blockage site is at the lamina cribrosa (LC). Other than this primary site of damage at the LC, 7 other factors may explain atypical nerve fiber layer (NFL) defects and the vulnerability of the nerve fibers in eyes with high myopia and glaucoma: a second point of blockage at the edge of the posterior scleral foramen; ectatic strain on the NFL; ectasia and distortion of the LC; association of a hypoplastic optic disc; thin and weak collagen fibers; peripapillary chorioretinal atrophy; and myopic neuropathy. Among diabetic patients, diabetic neuropathy in the retinal NFL is present initially, and increased resistance to aqueous outflow leads to ocular hypertension. Superimposition of GON on diabetic neuropathy and ocular hypertension in patients with diabetes may enhance their susceptibility to nerve damage. Results of a meta-analysis study suggested a positive association between diabetes mellitus and glaucoma whereas other reports suggested that leakage of vascular endothelial growth factor, a survival mechanism of ischemic neural tissue, and enhanced stiffness of the LC as a result of diabetic glycation may protect neurons from apoptosis. Thus, modification of GON as a result of diabetes remains controversial.
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Affiliation(s)
- Etsuo Chihara
- Sensho-Kai Eye Institute, Minamiyama 50-1, Iseda, Uji, Kyoto, 611-0043, Japan,
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87
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Rajala A, Dighe R, Agbaga MP, Anderson RE, Rajala RVS. Insulin receptor signaling in cones. J Biol Chem 2013; 288:19503-15. [PMID: 23673657 DOI: 10.1074/jbc.m113.469064] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In humans, age-related macular degeneration and diabetic retinopathy are the most common disorders affecting cones. In retinitis pigmentosa (RP), cone cell death precedes rod cell death. Systemic administration of insulin delays the death of cones in RP mouse models lacking rods. To date there are no studies on the insulin receptor signaling in cones; however, mRNA levels of IR signaling proteins are significantly higher in cone-dominant neural retina leucine zipper (Nrl) knock-out mouse retinas compared with wild type rod-dominant retinas. We previously reported that conditional deletion of the p85α subunit of phosphoinositide 3-kinase (PI3K) in cones resulted in age-related cone degeneration, and the phenotype was not rescued by healthy rods, raising the question of why cones are not protected by the rod-derived cone survival factors. Interestingly, systemic administration of insulin has been shown to delay the death of cones in mouse models of RP lacking rods. These observations led to the hypothesis that cones may have their own endogenous neuroprotective pathway, or rod-derived cone survival factors may be signaled through cone PI3K. To test this hypothesis we generated p85α(-/-)/Nrl(-/-) double knock-out mice and also rhodopsin mutant mice lacking p85α and examined the effect of the p85α subunit of PI3K on cone survival. We found that the rate of cone degeneration is significantly faster in both of these models compared with respective mice with competent p85α. These studies suggest that cones may have their own endogenous PI3K-mediated neuroprotective pathway in addition to the cone viability survival signals derived from rods.
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Affiliation(s)
- Ammaji Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center and Dean A McGee Eye Institute, Oklahoma City, Oklahoma 73104, USA
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88
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Rajala A, Dilly AK, Rajala RV. Protein tyrosine phosphatase-1B regulates the tyrosine phosphorylation of the adapter Grb2-associated binder 1 (Gab1) in the retina. Cell Commun Signal 2013; 11:20. [PMID: 23521888 PMCID: PMC3637500 DOI: 10.1186/1478-811x-11-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 03/19/2013] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Gab1 (Grb2-associated binder 1) is a key coordinator that belongs to the insulin receptor substrate-1 like family of adaptor molecules and is tyrosine phosphorylated in response to various growth factors, cytokines, and numerous other molecules. Tyrosine phosphorylated Gab1 is able to recruit a number of signaling effectors including PI3K, SHP2 and PLC-γ. In this study, we characterized the localization and regulation of tyrosine phosphorylation of Gab1 in the retina. RESULTS Our immuno localization studies suggest that Gab1 is expressed in rod photoreceptor inner segments. We found that hydrogen peroxide activates the tyrosine phosphorylation of Gab1 ex vivo and hydrogen peroxide has been shown to inhibit the protein tyrosine phosphatase PTP1B activity. We found a stable association between the D181A substrate trap mutant of PTP1B and Gab1. Our studies suggest that PTP1B interacts with Gab1 through Tyrosine 83 and this residue may be the major PTP1B target residue on Gab1. We also found that Gab1 undergoes a light-dependent tyrosine phosphorylation and PTP1B regulates the phosphorylation state of Gab1. Consistent with these observations, we found an enhanced Gab1 tyrosine phosphorylation in PTP1B deficient mice and also in retinas treated ex vivo with a PTP1B specific allosteric inhibitor. CONCLUSIONS Our laboratory has previously reported that retinas deficient of PTP1B are resistant to light damage compared to wild type mice. Since Gab1 is negatively regulated by PTP1B, a part of the retinal neuroprotective effect we have observed previously in PTP1B deficient mice could be contributed by Gab1 as well. In summary, our data suggest that PTP1B regulates the phosphorylation state of retinal Gab1 in vivo.
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Affiliation(s)
- Ammaji Rajala
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
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89
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Ola MS, Nawaz MI, Khan HA, Alhomida AS. Neurodegeneration and neuroprotection in diabetic retinopathy. Int J Mol Sci 2013; 14:2559-72. [PMID: 23358247 PMCID: PMC3588002 DOI: 10.3390/ijms14022559] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 01/12/2013] [Accepted: 01/17/2013] [Indexed: 02/06/2023] Open
Abstract
Diabetic retinopathy is widely considered to be a neurovascular disease. This is in contrast to its previous identity as solely a vascular disease. Early in the disease progression of diabetes, the major cells in the neuronal component of the retina consist of retinal ganglion cells and glial cells, both of which have been found to be compromised. A number of retinal function tests also indicated a functional deficit in diabetic retina, which further supports dysfunction of neuronal cells. As an endocrinological disorder, diabetes alters metabolism both systemically and locally in several body organs, including the retina. A growing body of evidences indicates increased levels of excitotoxic metabolites, including glutamate, branched chain amino acids and homocysteine in cases of diabetic retinopathy. Also present, early in the disease, are decreased levels of folic acid and vitamin-B12, which are potential metabolites capable of damaging neurons. These altered levels of metabolites are found to activate several metabolic pathways, leading to increases in oxidative stress and decreases in the level of neurotrophic factors. As a consequence, they may damage retinal neurons in diabetic patients. In this review, we have discussed those potential excitotoxic metabolites and their implications in neuronal damage. Possible therapeutic targets to protect neurons are also discussed. However, further research is needed to understand the exact molecular mechanism of neurodegeneration so that effective neuroprotection strategies can be developed. By protecting retinal neurons early in diabetic retinopathy cases, damage of retinal vessels can be protected, thereby helping to ameliorate the progression of diabetic retinopathy, a leading cause of blindness worldwide.
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Affiliation(s)
- Mohammad Shamsul Ola
- Department of Biochemistry, Faculty of Science, King Saud University, Riyadh 11415, Saudi Arabia.
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90
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You Y, Gupta VK, Graham SL, Klistorner A. Anterograde degeneration along the visual pathway after optic nerve injury. PLoS One 2012; 7:e52061. [PMID: 23300590 PMCID: PMC3530579 DOI: 10.1371/journal.pone.0052061] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 11/08/2012] [Indexed: 01/21/2023] Open
Abstract
PURPOSE To investigate anterograde degenerative changes along the visual pathway in a rat model of optic nerve axotomy. METHODS Optic nerve transection was performed in adult Sprague-Dawley rats. Animals were sacrificed at regular time intervals and tissues harvested. Immunoblotting followed by densitometric analysis was used to determine the phosphorylation profile of Akt in the dorsal lateral geniculate nucleus (dLGN) and the primary visual cortex (V1). The neuronal cell size and cell density were measured in the dLGN and the V1 using Nissl staining. The prevalence of apoptosis was characterized by terminal deoxynucleotidyl-transferase-mediated biotin-dUTP nick end labelling (TUNEL) histochemistry. Caspase-3 antibodies were also used to identify apoptotic cells. Neurons and astrocytes were detected using NeuN and glial fibrillary acidic protein (GFAP), respectively. RESULTS An early and sustained loss of Akt phosphorylation was observed after optic nerve transection in both dLGN and V1. At week one, a decrease in the neuronal cell size (50.5±4.9 vs 60.3±5.0 µm(2), P = 0.042) and an increase of TUNEL positive cells (7.9±0.6 vs 1.4±0.5 ×10(2) cells/mm(2), P<0.001) were evident in the dLGN but not in V1. A significant decline in neuronal cell number (14.5±0.1 vs 17.4±1.3 ×10(2) cells/mm(2), P = 0.048), cell size (42.5±4.3 vs 62.1±4.7 µm(2), P = 0.001) and an increase in apoptotic cells (5.6±0.5 vs 2.0±0.4 ×10(2) cells/mm(2), P<0.001) appeared in V1 initially at one month post-transection. The changes in the visual pathway continued through two months. Both neuronal cells and GFAP-positive glial cells were affected in this anterograde degeneration along the visual pathway. CONCLUSIONS Anterograde degeneration along the visual pathway takes place in target relay (LGN) and visual cortex following the optic nerve injury. Apoptosis was observed in both neural and adjacent glial cells. Reduction of Akt phosphorylation preceded cellular and apoptotic changes.
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Affiliation(s)
- Yuyi You
- Department of Ophthalmology, Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Vivek K. Gupta
- Department of Ophthalmology, Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Stuart L. Graham
- Department of Ophthalmology, Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
- Save Sight Institute, Sydney University, Sydney, Australia
| | - Alexander Klistorner
- Department of Ophthalmology, Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
- Save Sight Institute, Sydney University, Sydney, Australia
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91
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Kador PF, Zhang P, Makita J, Zhang Z, Guo C, Randazzo J, Kawada H, Haider N, Blessing K. Novel diabetic mouse models as tools for investigating diabetic retinopathy. PLoS One 2012; 7:e49422. [PMID: 23251343 PMCID: PMC3520987 DOI: 10.1371/journal.pone.0049422] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 10/07/2012] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVE Mouse models possessing green fluorescent protein (GFP) and/or human aldose reductase (hAR) in vascular tissues have been established and crossed with naturally diabetic Akita mice to produce new diabetic mouse models. RESEARCH DESIGN AND METHODS Colonies of transgenic C57BL mice expressing GFP (SMAA-GFP), hAR (SMAA-hAR) or both (SMAA-GFP-hAR) in vascular tissues expressing smooth muscle actin were established and crossbred with C57BL/6-Ins2(Akita)/J (AK) mice to produce naturally diabetic offspring AK-SMAA-GFP and AK-SMAA-GFP-hAR. Aldose reductase inhibitor AL1576 (ARI) was administered in chow. Retinal and lenticular sorbitol levels were determined by HPLC. Retinal functions were evaluated by electroretinography (ERGs). Growth factor and signaling changes were determined by Western Blots using commercially available antibodies. Retinal vasculatures were isolated from the neural retina by enzymatic digestion. Flat mounts were stained with PAS-hematoxylin and analyzed. RESULTS Akita transgenics developed DM by 8 weeks of age with blood glucose levels higher in males than females. Sorbitol levels were higher in neural retinas of AK-SMAA-GFP-hAR compared to AK-SMAA-GFP mice. AK-SMAA-GFP-hAR mice also had higher VEGF levels and reduced ERG scotopic b-wave function, both of which were normalized by AL1576. AK-SMAA-GFP-hAR mice showed induction of the retinal growth factors bFGF, IGF-1, and TGFβ, as well as signaling changes in P-Akt, P-SAPK/JNK and P-44/42 MAPK that were also reduced by ARI treatment. Quantitative analysis of flat mounts in 18 week AK-SMAA-GFP-hAR mice revealed increased loss of nuclei/capillary length and a significant increase in the percentage of acellular capillaries present which was not seen in AK-SMAA-GFP-hAR treated with ARI. CONCLUSIONS/SIGNIFICANCE These new mouse models of early onset diabetes may be valuable tools for assessing both the role of hyperglycemia and AR in the development of retinal lesions associated with diabetic retinopathy.
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Affiliation(s)
- Peter F Kador
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
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92
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Fox TE, Young MM, Pedersen MM, Han X, Gardner TW, Kester M. Diabetes diminishes phosphatidic acid in the retina: a putative mediator for reduced mTOR signaling and increased neuronal cell death. Invest Ophthalmol Vis Sci 2012; 53:7257-67. [PMID: 22952117 DOI: 10.1167/iovs.11-7626] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
PURPOSE We demonstrated previously that pro-survival insulin receptor, PI3K-Akt, and p70 S6K signaling is diminished in models of diabetic retinopathy. As mammalian target of rapamycin (mTOR), an upstream activator of p70 S6Kinase is, in part, regulated by lipid-derived second messengers, such as phosphatidic acid (PA), we sought to determine if diminished mTOR/p70 S6Kinase signaling in diabetic retinas may reflect diminished PA levels. METHODS Alterations in PA mass from retinas of control and streptozotocin-induced diabetic rats were determined by mass spectrometry. The biochemical and biophysical mechanisms underlying the actions of PA on insulin-activated mTOR/p70 S6Kinase signaling were determined using R28 retinal neuronal cells. RESULTS We demonstrate a significant decrease in PA in R28 retinal neuronal cells exposed to hyperglycemia as well as in streptozotocin-induced diabetic rat retinas. Exogenous PA augmented insulin-induced protection from interleukin-1β-induced apoptosis. Moreover, exogenous PA and insulin cooperatively activated mTOR survival pathways in R28 neuronal cultures. Exogenous PA colocalized with activated mTOR/p70 S6kinase signaling elements within lipid microdomains. The biochemical consequences of this biophysical mechanism is reflected by differential phosphorylation of tuberin at threonine 1462 and serine 1798, respectively, by PA and insulin, which reduce this suppressor of mTOR/S6Kinase signaling within lipid microdomains. CONCLUSIONS These results identify PA-enriched microdomains as a putative lipid-based signaling element responsible for mTOR-dependent retinal neuronal survival. Moreover, diabetic retinal neuronal apoptosis may reflect diminished PA mass. Elevating PA concentrations and restoring mTOR signaling may be an effective therapeutic modality to reduce neuronal cell death in diabetic retinopathy.
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Affiliation(s)
- Todd E Fox
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
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93
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Ghasemi R, Haeri A, Dargahi L, Mohamed Z, Ahmadiani A. Insulin in the brain: sources, localization and functions. Mol Neurobiol 2012; 47:145-71. [PMID: 22956272 DOI: 10.1007/s12035-012-8339-9] [Citation(s) in RCA: 203] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/20/2012] [Indexed: 02/07/2023]
Abstract
Historically, insulin is best known for its role in peripheral glucose homeostasis, and insulin signaling in the brain has received less attention. Insulin-independent brain glucose uptake has been the main reason for considering the brain as an insulin-insensitive organ. However, recent findings showing a high concentration of insulin in brain extracts, and expression of insulin receptors (IRs) in central nervous system tissues have gathered considerable attention over the sources, localization, and functions of insulin in the brain. This review summarizes the current status of knowledge of the peripheral and central sources of insulin in the brain, site-specific expression of IRs, and also neurophysiological functions of insulin including the regulation of food intake, weight control, reproduction, and cognition and memory formation. This review also considers the neuromodulatory and neurotrophic effects of insulin, resulting in proliferation, differentiation, and neurite outgrowth, introducing insulin as an attractive tool for neuroprotection against apoptosis, oxidative stress, beta amyloid toxicity, and brain ischemia.
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Affiliation(s)
- Rasoul Ghasemi
- Department of Physiology, Faculty of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
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94
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Marçal AC, Leonelli M, Fiamoncini J, Deschamps FC, Rodrigues MAM, Curi R, Carpinelli AR, Britto LRG, Carvalho CRO. Diet-induced obesity impairs AKT signalling in the retina and causes retinal degeneration. Cell Biochem Funct 2012; 31:65-74. [PMID: 22915345 DOI: 10.1002/cbf.2861] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 06/18/2012] [Accepted: 07/05/2012] [Indexed: 11/06/2022]
Abstract
Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT(1) , eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- Anderson C Marçal
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas (ICB), Universidade de São Paulo (USP), SP, Brazil.
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95
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van Dijk HW, Verbraak FD, Kok PHB, Stehouwer M, Garvin MK, Sonka M, DeVries JH, Schlingemann RO, Abràmoff MD. Early neurodegeneration in the retina of type 2 diabetic patients. Invest Ophthalmol Vis Sci 2012; 53:2715-9. [PMID: 22427582 DOI: 10.1167/iovs.11-8997] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The purpose of this study was to determine whether diabetes type 2 causes thinning of retinal layers as a sign of neurodegeneration and to investigate the possible relationship between this thinning and duration of diabetes mellitus, diabetic retinopathy (DR) status, age, sex, and glycemic control (HbA1c). METHODS Mean layer thickness was calculated for retinal layers following automated segmentation of spectral domain optical coherence tomography images of diabetic patients with no or minimal DR and compared with controls. To determine the relationship between layer thickness and diabetes duration, DR status, age, sex, and HbA1c, a multiple linear regression analysis was used. RESULTS In the pericentral area of the macula, the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) were thinner in patients with minimal DR compared to controls (respective difference 1.9 μm, 95% confidence interval [CI] 0.3-3.5 μm; 5.2 μm, 95% CI 1.0-9.3 μm; 4.5 μm, 95% CI 2.2-6.7 μm). In the peripheral area of the macula, the RNFL and IPL were thinner in patients with minimal DR compared to controls (respective difference 3.2 μm, 95% CI 0.1-6.4 μm; 3.3 μm, 95% CI 1.2-5.4 μm). Multiple linear regression analysis showed DR status to be the only significant explanatory variable (R = 0.31, P = 0.03) for this retinal thinning. CONCLUSIONS This study demonstrated thinner inner retinal layers in the macula of type 2 diabetic patients with minimal DR than in controls. These results support the concept that early DR includes a neurodegenerative component.
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Affiliation(s)
- Hille W van Dijk
- Department of Ophthalmology, Academic Medical Center, Amsterdam, The Netherlands.
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96
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Jiang Y, Zhang Q, Soderland C, Steinle JJ. TNFα and SOCS3 regulate IRS-1 to increase retinal endothelial cell apoptosis. Cell Signal 2012; 24:1086-92. [PMID: 22266116 PMCID: PMC4073498 DOI: 10.1016/j.cellsig.2012.01.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/06/2012] [Accepted: 01/06/2012] [Indexed: 01/09/2023]
Abstract
Rates of diabetes are reaching epidemic levels. The key problem in both type 1 and type 2 diabetes is dysfunctional insulin signaling, either due to lack of production or due to impaired insulin sensitivity. A key feature of diabetic retinopathy in animal models is degenerate capillary formation. The goal of this present study was to investigate a potential mechanism for retinal endothelial cell apoptosis in response to hyperglycemia. The hypothesis was that hyperglycemia-induced TNFα leads to retinal endothelial cell apoptosis through inhibition of insulin signaling. To test the hypothesis, primary human retinal endothelial cells were grown in normal glucose (5 mM) or high glucose (25 mM) and treated with exogenous TNFα, TNFα siRNA or suppressor of cytokine signaling 3 (SOCS3) siRNA. Cell lysates were processed for Western blotting and ELISA analyses to verify TNFα and SOCS3 knockdown, as well as key pro- and anti-apoptotic factors, IRS-1, and Akt. Data indicate that high glucose culturing conditions significantly increase TNFα and SOCS3 protein levels. Knockdown of TNFα and SOCS3 significantly increases anti-apoptotic proteins, while decreasing pro-apoptotic proteins. Knockdown of TNFα leads to decreased phosphorylation of IRS-1(Ser307), which would promote normal insulin signaling. Knockdown of SOCS3 increased total IRS-1 levels, as well as decreased IR(Tyr960), both of which would inhibit retinal endothelial cell apoptosis through increased insulin signaling. Taken together, our findings suggest that increased TNFα inhibits insulin signaling in 2 ways: 1) increased phosphorylation of IRS-1(Ser307), 2) increased SOCS3 levels to decrease total IRS-1 and increase IR(Tyr960), both of which block normal insulin signal transduction. Resolution of the hyperglycemia-induced TNFα levels in retinal endothelial cells may prevent apoptosis through disinhibition of insulin receptor signaling.
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Affiliation(s)
- Youde Jiang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA
| | | | - Jena J. Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Duarte AI, Moreira PI, Oliveira CR. Insulin in central nervous system: more than just a peripheral hormone. J Aging Res 2012; 2012:384017. [PMID: 22500228 PMCID: PMC3303591 DOI: 10.1155/2012/384017] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 10/12/2011] [Accepted: 11/23/2011] [Indexed: 12/14/2022] Open
Abstract
Insulin signaling in central nervous system (CNS) has emerged as a novel field of research since decreased brain insulin levels and/or signaling were associated to impaired learning, memory, and age-related neurodegenerative diseases. Thus, besides its well-known role in longevity, insulin may constitute a promising therapy against diabetes- and age-related neurodegenerative disorders. More interestingly, insulin has been also faced as the potential missing link between diabetes and aging in CNS, with Alzheimer's disease (AD) considered as the "brain-type diabetes." In fact, brain insulin has been shown to regulate both peripheral and central glucose metabolism, neurotransmission, learning, and memory and to be neuroprotective. And a future challenge will be to unravel the complex interactions between aging and diabetes, which, we believe, will allow the development of efficient preventive and therapeutic strategies to overcome age-related diseases and to prolong human "healthy" longevity. Herewith, we aim to integrate the metabolic, neuromodulatory, and neuroprotective roles of insulin in two age-related pathologies: diabetes and AD, both in terms of intracellular signaling and potential therapeutic approach.
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Affiliation(s)
- Ana I. Duarte
- CNC, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Paula I. Moreira
- CNC, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
- Institute of Physiology, Faculty of Medicine, University of Coimbra, 3000-354 Coimbra, Portugal
| | - Catarina R. Oliveira
- CNC, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
- Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3000-354 Coimbra, Portugal
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98
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Abstract
The protein kinase C (PKC) family of enzymes regulates cell physiology through phosphorylation of serine and threonine residues of many proteins in most cell types. Here we identify PKC-β1 and PKC-γ as isoforms that are essential for rod photoreceptor differentiation in mouse retinas. Using ex vivo retinal explants, we found that phorbol ester 12-myristate 13-acetate and insulin-like growth factor 1 (IGF1) induced rod differentiation, as defined by opsin or Crx expression, in a PKC-dependent manner days ahead of rod development in untreated explants. PKC-β1 and PKC-γ were colocalized with proliferating cell nuclear antigen (PCNA)- and STAT3-positive progenitors through the later differentiation period. Pharmacological or genetic inhibition of either isoform resulted in a partial reduction in the appearance of rods, whereas removing both isoforms resulted in their complete absence. Furthermore, a significant decline of STAT3 tyrosine phosphorylation was observed by activation of PKC, while inhibition of PKC resulted in an increase of phosphorylated STAT3 along with a delayed cell cycle exit of progenitors with prolonged PCNA expression. In adult retinas, IGF1 activates PI-3 kinase (PI3K), but in neonatal retinas its action is identical to the action of an PI3K inhibitor. These data unveil a novel signaling cascade that coordinates and regulates rod differentiation through specific PKC isoforms in mammals.
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99
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West EL, Pearson RA, Duran Y, Gonzalez-Cordero A, MacLaren RE, Smith AJ, Sowden JC, Ali RR. Manipulation of the recipient retinal environment by ectopic expression of neurotrophic growth factors can improve transplanted photoreceptor integration and survival. Cell Transplant 2012; 21:871-87. [PMID: 22325046 DOI: 10.3727/096368911x623871] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Degeneration of the neural retina is the leading cause of untreatable blindness in the developed world. Stem cell replacement therapy offers a novel strategy for retinal repair. Postmitotic photoreceptor precursors derived from the early postnatal (P) retina are able to migrate and integrate into the adult mouse retina following transplantation into the subretinal space, but it is likely that a large number of these cells would be required to restore vision. The adult recipient retina presents a very different environment to that from which photoreceptor precursor donor cells isolated from the developing postnatal retina are derived. Here we considered the possibility that modulation of the recipient environment by ectopic expression of developmentally regulated growth factors, normally present during photoreceptor development, might enhance the migration and integration of transplanted cells into the adult neural retina. Adeno-associated viral (AAV) vectors were used to introduce three growth factors previously reported to play a role in photoreceptor development, IGF1, FGF2, and CNTF, into the adult retina, prior to transplantation of P4 cells derived from the Nrl.GFP(+ve) neural retina. At 3 weeks posttransplantation the number of integrated, differentiated photoreceptor cells present in AAV-mediated neurotrophic factor-treated eyes was assessed and compared to control treated contralateral eyes. We show, firstly, that it is possible to manipulate the recipient retinal microenvironment via rAAV-mediated gene transfer with respect to these developmentally relevant growth factors. Moreover, when combined with cell transplantation, AAV-mediated expression of IGF1 led to significantly increased levels of cell integration, while overexpression of FGF2 had no significant effect on integrated cell number. Conversely, expression of CNTF led to a significant decrease in cell integration and an exacerbated glial response that led to glial scarring. Together, these findings demonstrate the importance of the extrinsic environment of the recipient retina for photoreceptor cell transplantation and show for the first time that it is possible to manipulate this environment using viral vectors to influence photoreceptor transplantation efficiency.
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Affiliation(s)
- E L West
- Department of Genetics, University College London Institute of Ophthalmology, London, UK
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100
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Pandit J, Sultana Y. Vascular damage of retina in diabetic retinopathy and its treatment. EXPERT REVIEW OF OPHTHALMOLOGY 2012. [DOI: 10.1586/eop.11.81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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