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Iannitelli AF, Weinshenker D. Riddles in the dark: Decoding the relationship between neuromelanin and neurodegeneration in locus coeruleus neurons. Neurosci Biobehav Rev 2023; 152:105287. [PMID: 37327835 PMCID: PMC10523397 DOI: 10.1016/j.neubiorev.2023.105287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/11/2023] [Accepted: 06/13/2023] [Indexed: 06/18/2023]
Abstract
The noradrenergic locus coeruleus (LC) is among the first regions of the brain affected by pathology in both Alzheimer's disease (AD) and Parkinson's disease (PD), but the reasons for this selective vulnerability are not completely understood. Several features of LC neurons have been proposed as contributing factors to this dysfunction and degeneration, and this review will focus on the presence of neuromelanin (NM). NM is a dark pigment unique to catecholaminergic cells that is formed of norepinephrine (NE) and dopamine (DA) metabolites, heavy metals, protein aggregates, and oxidated lipids. We cover what is currently known about NM and the limitations of historical approaches, then discuss the new human tyrosinase (hTyr) model of NM production in rodent catecholamine cells in vivo that offers unique opportunities for studying its neurobiology, neurotoxicity, and potential of NM-based therapeutics for treating neurodegenerative disease.
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Affiliation(s)
- Alexa F Iannitelli
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David Weinshenker
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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Using Sepia melanin as a PD model to describe the binding characteristics of neuromelanin – A critical review. J Chem Neuroanat 2015; 64-65:20-32. [DOI: 10.1016/j.jchemneu.2015.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/03/2015] [Accepted: 02/03/2015] [Indexed: 12/15/2022]
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Sharifi AM, Mousavi SH. Studying the effects of lead on DNA fragmentation and proapoptotic bax and antiapoptotic bcl-2 protein expression in PC12 cells. Toxicol Mech Methods 2012; 18:75-9. [PMID: 20020893 DOI: 10.1080/15376510701665814] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
ABSTRACT The nervous system is one of the most important targets of lead poisoning. Despite decades of study, the exact mechanism of lead toxicity has not been fully elucidated. One of the suggested mechanisms of lead toxicity is induction of apoptosis, which has not been shown yet in some neuronal cells such as pheochromocytoma cells (PC12). Therefore, the present study sought to examine the effect of lead poisoning on apoptosis in PC12 cells as a suitable model of neuronal cell study. The present results showed that lead could induce toxicity in PC12 cells after 24 hours with as little as 1 muM in a concentration-dependent manner. In Western blot analysis, the ratio of Bax/Bcl-2 protein expression in cells incubated with 3, 30, and 90 muM lead acetate significantly increased compared to controls. Additionally, a DNA laddering pattern in lead-treated cells was shown, which could indicate nuclear fragmentation. It might be concluded that lead could cause PC12 cell death, in which apoptosis or programmed cell death plays an important role.
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Affiliation(s)
- Ali M Sharifi
- Department of Pharmacology and Cellular and Molecular Research Center, School of Medicine, Iran University of Medical Sciences, P.O. Box 14155-6183, Tehran, Iran
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Sehlin D, Englund H, Simu B, Karlsson M, Ingelsson M, Nikolajeff F, Lannfelt L, Pettersson FE. Large aggregates are the major soluble Aβ species in AD brain fractionated with density gradient ultracentrifugation. PLoS One 2012; 7:e32014. [PMID: 22355408 PMCID: PMC3280222 DOI: 10.1371/journal.pone.0032014] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 01/17/2012] [Indexed: 01/18/2023] Open
Abstract
Soluble amyloid-β (Aβ) aggregates of various sizes, ranging from dimers to large protofibrils, have been associated with neurotoxicity and synaptic dysfunction in Alzheimer's Disease (AD). To investigate the properties of biologically relevant Aβ species, brain extracts from amyloid β protein precursor (AβPP) transgenic mice and AD patients as well as synthetic Aβ preparations were separated by size under native conditions with density gradient ultracentrifugation. The fractionated samples were then analyzed with atomic force microscopy (AFM), ELISA, and MTT cell viability assay. Based on AFM appearance and immunoreactivity to our protofibril selective antibody mAb158, synthetic Aβ42 was divided in four fractions, with large aggregates in fraction 1 and the smallest species in fraction 4. Synthetic Aβ aggregates from fractions 2 and 3 proved to be most toxic in an MTT assay. In AβPP transgenic mouse brain, the most abundant soluble Aβ species were found in fraction 2 and consisted mainly of Aβ40. Also in AD brains, Aβ was mainly found in fraction 2 but primarily as Aβ42. All biologically derived Aβ from fraction 2 was immunologically discriminated from smaller species with mAb158. Thus, the predominant species of biologically derived soluble Aβ, natively separated by density gradient ultracentrifugation, were found to match the size of the neurotoxic, 80–500 kDa synthetic Aβ protofibrils and were equally detected with mAb158.
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Affiliation(s)
- Dag Sehlin
- Molecular Geriatrics, Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden.
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Oberländer U, Pletinckx K, Döhler A, Müller N, Lutz MB, Arzberger T, Riederer P, Gerlach M, Koutsilieri E, Scheller C. Neuromelanin is an immune stimulator for dendritic cells in vitro. BMC Neurosci 2011; 12:116. [PMID: 22085464 PMCID: PMC3225309 DOI: 10.1186/1471-2202-12-116] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 11/15/2011] [Indexed: 12/25/2022] Open
Abstract
Background Parkinson's disease (PD) is characterized at the cellular level by a destruction of neuromelanin (NM)-containing dopaminergic cells and a profound reduction in striatal dopamine. It has been shown recently that anti-melanin antibodies are increased in sera of Parkinson patients, suggesting that NM may act as an autoantigen. In this study we tested whether NM is being recognized by dendritic cells (DCs), the major cell type for inducing T- and B-cell responses in vivo. This recognition of NM by DCs is a prerequisite to trigger an adaptive autoimmune response directed against NM-associated structures. Results Murine DCs were treated with NM of substantia nigra (SN) from human subjects or with synthetic dopamine melanin (DAM). DCs effectively phagocytized NM and subsequently developed a mature phenotype (CD86high/MHCIIhigh). NM-activated DCs secreted the proinflammatory cytokines IL-6 and TNF-α. In addition, they potently triggered T cell proliferation in a mixed lymphocyte reaction, showing that DC activation was functional to induce a primary T cell response. In contrast, DAM, which lacks the protein and lipid components of NM but mimics the dopamine-melanin backbone of NM, had only very little effect on DC phenotype and function. Conclusions NM is recognized by DCs in vitro and triggers their maturation. If operative in vivo, this would allow the DC-mediated transport and presentation of SN antigens to the adaptive immune system, leading to autoimmmunity in susceptible individuals. Our data provide a rationale for an autoimmune-based pathomechanism of PD with NM as the initial trigger.
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Affiliation(s)
- Uwe Oberländer
- University of Würzburg, Institute of Virology and Immunobiology, Würzburg, Germany
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He AY, Qiu LJ, Gao Y, Zhu Y, Xu ZW, Xu JM, Zhang ZH. The role of oxidative stress in neuromelanin synthesis in PC12 cells. Neuroscience 2011; 189:43-50. [PMID: 21624436 DOI: 10.1016/j.neuroscience.2011.05.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/07/2011] [Accepted: 05/14/2011] [Indexed: 10/18/2022]
Abstract
Previous research has indicated that neuromelanin (NM) is involved in the pathogenesis of Parkinson's disease (PD). Increased reactive oxygen species (ROS) generation in PD sufferers is thought to be related to enhanced tyrosine hydroxylase (TH) activity and NM production. However, few reports have confirmed this hypothesis. In this study, PC12 cells of all experiments were exposed to 50 μmol/L levodopa (l-DOPA) to generate a model for NM synthesis. Meanwhile, PC12 cells were treated with glucose oxidase (GO) at different concentrations to generate oxidative stress. Finally, cell viability, TH activity, and NM generation in PC12 cells were measured. The results showed that GO dose-dependently stimulated oxidative stress generation in PC12 cells. Moderate increases in oxidative stress enhanced the viability of PC12 cells. However, an excessive level of oxidative stress can lead to the degeneration of PC12 cells. Notably, in the surviving PC12 cells, ROS significantly increased the TH activity, and the NM production was also upregulated. Thus, oxidative stress may upregulate the synthesis of NM, which may be a result of the increased TH activity observed in response to the elevated ROS in l-DOPA-treated PC12 cells.
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Affiliation(s)
- A-Y He
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China
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Double KL, Rowe DB, Carew-Jones FM, Hayes M, Chan DKY, Blackie J, Corbett A, Joffe R, Fung VS, Morris J, Riederer P, Gerlach M, Halliday GM. Anti-melanin antibodies are increased in sera in Parkinson's disease. Exp Neurol 2009; 217:297-301. [PMID: 19289120 DOI: 10.1016/j.expneurol.2009.03.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 02/22/2009] [Accepted: 03/05/2009] [Indexed: 01/01/2023]
Abstract
An increasing body of research suggests that a number of immune mechanisms play a role in degenerative pathways in Parkinson's disease (PD). In the current work we investigated a posited humoral immune response in this disorder. Sera from PD patients exhibited a significantly enhanced absorbance response on a novel ELISA for anti-melanin antibodies, compared to sera from age-matched control subjects. The enhanced ELISA absorbance response was specific for catecholamine-based melanins and was unrelated to antiparkinsonian dopaminergic medication. Further, the absorbance response was significantly and negatively correlated with disease duration. These data suggest that a specific humoral anti-melanin antibody response is present in PD and is more active in early disease. While the contribution of this novel immune response to the initiation and progression of this disorder is unclear, this finding supports the hypothesis that specific immune responses occurring in PD may respond to therapeutic interventions in this disorder.
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Affiliation(s)
- K L Double
- Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, Barker St, Randwick, NSW, 2031, Australia.
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Depboylu C, Matusch A, Tribl F, Zoriy M, Michel PP, Riederer P, Gerlach M, Becker S, Oertel WH, Höglinger GU. Glia Protects Neurons against Extracellular Human Neuromelanin. NEURODEGENER DIS 2007; 4:218-26. [PMID: 17596716 DOI: 10.1159/000101846] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Neuromelanin-containing neurons of the substantia nigra are highly vulnerable to degenerate in Parkinson's disease. Inhibition of the respiratory chain or formation of reactive oxygen species (ROS) by intracellular neuromelanin and triggering of inflammatory processes by extracellular neuromelanin emanating from melanized neurons after their demise are thought to be causally implicated in the high vulnerability of melanized neurons. OBJECTIVE We addressed the direct effect of purified neuromelanin on mitochondrial complex I activity, and its influence on ROS production and survival of primary mesencephalic neurons in the presence or absence of glia. METHODS Neuromelanin was isolated from midbrain of postmortem human brains. The content in iron and other elements was measured by inductively coupled mass spectrometry. The effect of neuromelanin on mitochondrial complex I activity was analyzed in post-nuclear extracts. Primary neuronal enriched and neuron-glia mixed cultures from midbrain were treated with different concentrations of neuromelanin. The generation of ROS was determined by fluorochrome detection. MAP2-positive and TH-positive neuronal viability was analyzed. RESULTS Neuromelanin did not affect complex I activity, but concentration-dependently increased ROS production in neurons and reduced the number of MAP2-positive and TH-positive cultured neurons. Glia protected neurons against the neuromelanin toxicity. CONCLUSION Extracellular neuromelanin is detrimental to neurons implicating a mechanism of intracellular ROS production, but not complex I inhibition. ROS formation may be catalyzed by iron, which was sensitively identified in purified neuromelanin (3.3 mg/g). Importantly, we demonstrate that glial cells have the potential to mitigate the neurotoxic effect of neuromelanin.
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Affiliation(s)
- Candan Depboylu
- Experimental Neurology, Department of Neurology, Philipps University Marburg, Marburg, Germany
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Ostergren A, Lindquist NG, Brittebo EB. Differential effects of dopamine melanin on norharman-induced toxicity in PC12 cells. J Neural Transm (Vienna) 2007; 114:909-18. [PMID: 17256107 DOI: 10.1007/s00702-006-0622-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
The food contaminant norharman structurally resembles MPTP a compound that selectively damages pigmented brain areas. Both compounds are sequestered and retained in melanin-containing neurons. The aim of the study was to examine whether intracellular melanin can modulate the toxicity of norharman in melanin-loaded PC12 cells. Dopamine melanin protected against norharman-induced upregulation of grp78, activation of caspase 3 and necrosis at low concentrations (5 and 50 microM). In contrast, at a high conentration (500 microM) there was a significantly increased expression of grp78, hsp90 and caspase 3 and a disassociation of melanin aggregates leading to dispersal of granules to swollen neurite terminals. In human populations, a long-term low-level exposure to toxicants with a high affinity to melanin will probably result in accumulation in melanin-containing neurons in vivo. Our data suggest that accumulation of a neurotoxicant in melanin-loaded cells may lead to increased cell stress, apoptotic signaling and disassociation of melanin aggregates.
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Affiliation(s)
- A Ostergren
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Biermann J, Lang D, Gorboulev V, Koepsell H, Sindic A, Schröter R, Zvirbliene A, Pavenstädt H, Schlatter E, Ciarimboli G. Characterization of regulatory mechanisms and states of human organic cation transporter 2. Am J Physiol Cell Physiol 2006; 290:C1521-31. [PMID: 16394027 DOI: 10.1152/ajpcell.00622.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polyspecific organic cation transporters (OCTs) have a large substrate binding pocket with different interaction domains. To determine whether OCT regulation is substrate specific, suitable fluorescent organic cations were selected by comparing their uptake in wild-type (WT) human embryonic kidney (HEK)-293 cells and in HEK-293 cells stably transfected with hOCT2. N-amidino-3,5-diamino-6-chloropyrazine-carboxamide (amiloride) and 4-[4-(dimethylamino)-styryl]- N-methylpyridinium (ASP) showed concentration-dependent uptake in hOCT2 at 37°C. After subtraction of unspecific uptake determined in WT at 37°C or in hOCT2 at 8°C saturable specific uptake of both substrates was measured. Kmvalues of hOCT2-mediated uptake of 95 μM amiloride and 24 μM ASP were calculated. Inhibition of amiloride and ASP uptake by several organic cations was also measured [IC50(in μM) for amiloride and ASP, respectively, tetraethylammonium (TEA) 98 and 30, cimetidine 14 and 26, and tetrapentylammonium (TPA) 7 and 2]. Amiloride and ASP uptake were significantly reduced by inhibition of Ca2+/CaM complex (−55 ± 5%, n = 10 and −63 ± 2%, n = 15, for amiloride and ASP, respectively) and stimulation of PKC (−54 ± 5%, n = 14, and −31 ± 6%, n = 26) and PKA (−16 ± 5%, n = 16, and −18 ± 4%, n = 40), and they were increased by inhibition of phosphatidylinositol 3-kinase (+28 ± 6%, n = 8, and +55 ± 17%, n = 16). Inhibition of Ca2+/CaM complex resulted in a significant decrease of Vmax(160–99 photons/s) that can be explained in part by a reduction of the membrane-associated hOCT2 (−22 ± 6%, n = 9) as determined using FACScan flow cytometry. The data indicate that saturable transport by hOCT2 can be measured by the fluorescent substrates amiloride and ASP and that transport activity for both substrates is regulated similarly. Inhibition of the Ca2+/CaM complex causes changes in transport capacity via hOCT2 trafficking.
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Affiliation(s)
- Jürgen Biermann
- Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Universitätsklinikum Münster, Domagkstrasse 3a, D-48149 Münster, Germany
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