1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Primary retinal cultures as a tool for modeling diabetic retinopathy: an overview. BIOMED RESEARCH INTERNATIONAL 2015; 2015:364924. [PMID: 25688355 PMCID: PMC4320900 DOI: 10.1155/2015/364924] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/04/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
Experimental models of diabetic retinopathy (DR) have had a crucial role in the comprehension of the pathophysiology of the disease and the identification of new therapeutic strategies. Most of these studies have been conducted in vivo, in animal models. However, a significant contribution has also been provided by studies on retinal cultures, especially regarding the effects of the potentially toxic components of the diabetic milieu on retinal cell homeostasis, the characterization of the mechanisms on the basis of retinal damage, and the identification of potentially protective molecules. In this review, we highlight the contribution given by primary retinal cultures to the study of DR, focusing on early neuroglial impairment. We also speculate on possible themes into which studies based on retinal cell cultures could provide deeper insight.
Collapse
|
3
|
Neuroprotection by rat Müller glia against high glucose-induced neurodegeneration through a mechanism involving ERK1/2 activation. Exp Eye Res 2014; 125:20-9. [DOI: 10.1016/j.exer.2014.05.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/17/2014] [Accepted: 05/15/2014] [Indexed: 12/15/2022]
|
4
|
Matteucci A, Varano M, Gaddini L, Mallozzi C, Villa M, Pricci F, Malchiodi-Albedi F. Neuroprotective effects of citicoline in in vitro models of retinal neurodegeneration. Int J Mol Sci 2014; 15:6286-97. [PMID: 24736780 PMCID: PMC4013628 DOI: 10.3390/ijms15046286] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/11/2014] [Accepted: 03/25/2014] [Indexed: 01/19/2023] Open
Abstract
In recent years, citicoline has been the object of remarkable interest as a possible neuroprotectant. The aim of this study was to investigate if citicoline affected cell survival in primary retinal cultures and if it exerted neuroprotective activity in conditions modeling retinal neurodegeneration. Primary retinal cultures, obtained from rat embryos, were first treated with increasing concentrations of citicoline (up to 1000 μM) and analyzed in terms of apoptosis and caspase activation and characterized by immunocytochemistry to identify neuronal and glial cells. Subsequently, excitotoxic concentration of glutamate or High Glucose-containing cell culture medium (HG) was administered as well-known conditions modeling neurodegeneration. Glutamate or HG treatments were performed in the presence or not of citicoline. Neuronal degeneration was evaluated in terms of apoptosis and loss of synapses. The results showed that citicoline did not cause any damage to the retinal neuroglial population up to 1000 μM. At the concentration of 100 μM, it was able to counteract neuronal cell damage both in glutamate- and HG-treated retinal cultures by decreasing proapoptotic effects and contrasting synapse loss. These data confirm that citicoline can efficiently exert a neuroprotective activity. In addition, the results suggest that primary retinal cultures, under conditions inducing neurodegeneration, may represent a useful system to investigate citicoline neuroprotective mechanisms.
Collapse
Affiliation(s)
- Andrea Matteucci
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
| | - Monica Varano
- GB Bietti Eye Foundation IRCCS, Via Livenza, 3, Rome 00198, Italy.
| | - Lucia Gaddini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
| | - Cinzia Mallozzi
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
| | - Marika Villa
- GB Bietti Eye Foundation IRCCS, Via Livenza, 3, Rome 00198, Italy.
| | - Flavia Pricci
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
| | - Fiorella Malchiodi-Albedi
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
| |
Collapse
|
5
|
Pan Y, Huang Y, Wang Z, Fang Q, Sun Y, Tong C, Peng K, Wang Y, Miao L, Cai L, Zhao Y, Liang G. Inhibition of MAPK-mediated ACE expression by compound C66 prevents STZ-induced diabetic nephropathy. J Cell Mol Med 2013; 18:231-41. [PMID: 24330074 PMCID: PMC3930410 DOI: 10.1111/jcmm.12175] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 10/02/2013] [Indexed: 01/09/2023] Open
Abstract
A range of in vitro, experimental and clinical intervention studies have implicated an important role for hyperglycaemia-induced activation of the renin-angiotensin system (RAS) in the development and progression of diabetic nephropathy (DN). Blockade of RAS by angiotensin converting enzyme (ACE) inhibitors is an effective strategy in treating diabetic kidney diseases. However, few studies demonstrate the mechanism by which hyperglycaemia up-regulates the expression of ACE gene. Our previous studies have identified a novel curcumin analogue, (2E,6E)-2,6-bis(2-(trifluoromethyl)benzylidene)cyclohexanone (C66), which could inhibit the high glucose (HG)-induced phosphorylation of mitogen-activated protein kinases in mouse macrophages. In this study, we found that the renal protection of C66 in diabetic mice was associated with mitogen-activated protein kinase (MAPK) inactivation and ACE/angiotensin II (Ang II) down-regulation. Generally, MAPKs have been considered as a downstream signalling of Ang II and a mediator for Ang II-induced pathophysiological actions. However, using C66 and specific inhibitors as small molecule probes, in vitro experiments demonstrate that the MAPK signalling pathway regulates ACE expression under HG stimulation, which contributes to renal Ang II activation and the development of DN. This study indicates that C66 is a potential candidate of DN therapeutic agents, and more importantly, that reduction in ACE expression by MAPKs inhibition seems to be an alternative strategy for the treatment of DN.
Collapse
Affiliation(s)
- Yong Pan
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China; Chinese-American Research Institute for Diabetic Complications, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Chong ZZ, Maiese K. Mammalian target of rapamycin signaling in diabetic cardiovascular disease. Cardiovasc Diabetol 2012; 11:45. [PMID: 22545721 PMCID: PMC3398846 DOI: 10.1186/1475-2840-11-45] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 04/30/2012] [Indexed: 12/15/2022] Open
Abstract
Diabetes mellitus currently affects more than 170 million individuals worldwide and is expected to afflict another 200 million individuals in the next 30 years. Complications of diabetes as a result of oxidant stress affect multiple systems throughout the body, but involvement of the cardiovascular system may be one of the most severe in light of the impact upon cardiac and vascular function that can result in rapid morbidity and mortality for individuals. Given these concerns, the signaling pathways of the mammalian target of rapamycin (mTOR) offer exciting prospects for the development of novel therapies for the cardiovascular complications of diabetes. In the cardiovascular and metabolic systems, mTOR and its multi-protein complexes of TORC1 and TORC2 regulate insulin release and signaling, endothelial cell survival and growth, cardiomyocyte proliferation, resistance to β-cell injury, and cell longevity. Yet, mTOR can, at times, alter insulin signaling and lead to insulin resistance in the cardiovascular system during diabetes mellitus. It is therefore vital to understand the complex relationship mTOR and its downstream pathways hold during metabolic disease in order to develop novel strategies for the complications of diabetes mellitus in the cardiovascular system.
Collapse
|
7
|
Maiese K, Chong ZZ, Shang YC, Hou J. Novel avenues of drug discovery and biomarkers for diabetes mellitus. J Clin Pharmacol 2011; 51:128-52. [PMID: 20220043 PMCID: PMC3033756 DOI: 10.1177/0091270010362904] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.
Collapse
Affiliation(s)
- Kenneth Maiese
- Department of Neurology, 8C-1 UHC, Wayne State University School of Medicine, 4201 St. Antoine, Detroit, MI 48201, USA.
| | | | | | | |
Collapse
|
8
|
Maiese K, Shang YC, Chong ZZ, Hou J. Diabetes mellitus: channeling care through cellular discovery. Curr Neurovasc Res 2010; 7:59-64. [PMID: 20158461 DOI: 10.2174/156720210790820217] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 12/29/2009] [Indexed: 12/13/2022]
Abstract
Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.
Collapse
Affiliation(s)
- Kenneth Maiese
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
| | | | | | | |
Collapse
|
9
|
Maiese K, Hou J, Chong ZZ, Shang YC. Erythropoietin, forkhead proteins, and oxidative injury: biomarkers and biology. ScientificWorldJournal 2009; 9:1072-104. [PMID: 19802503 PMCID: PMC2762199 DOI: 10.1100/tsw.2009.121] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO), and members of the mammalian forkhead transcription factors of the O class (FoxOs), may offer the greatest promise for new treatment regimens, since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. Yet, EPO and FoxOs may sometimes have unexpected and undesirable effects that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as the complex role that EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.
Collapse
Affiliation(s)
- Kenneth Maiese
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, Michigan, USA.
| | | | | | | |
Collapse
|