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Landowski M, Gogoi P, Ikeda S, Ikeda A. Roles of transmembrane protein 135 in mitochondrial and peroxisomal functions - implications for age-related retinal disease. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1355379. [PMID: 38576540 PMCID: PMC10993500 DOI: 10.3389/fopht.2024.1355379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Aging is the most significant risk factor for age-related diseases in general, which is true for age-related diseases in the eye including age-related macular degeneration (AMD). Therefore, in order to identify potential therapeutic targets for these diseases, it is crucial to understand the normal aging process and how its mis-regulation could cause age-related diseases at the molecular level. Recently, abnormal lipid metabolism has emerged as one major aspect of age-related symptoms in the retina. Animal models provide excellent means to identify and study factors that regulate lipid metabolism in relation to age-related symptoms. Central to this review is the role of transmembrane protein 135 (TMEM135) in the retina. TMEM135 was identified through the characterization of a mutant mouse strain exhibiting accelerated retinal aging and positional cloning of the responsible mutation within the gene, indicating the crucial role of TMEM135 in regulating the normal aging process in the retina. Over the past decade, the molecular functions of TMEM135 have been explored in various models and tissues, providing insights into the regulation of metabolism, particularly lipid metabolism, through its action in multiple organelles. Studies indicated that TMEM135 is a significant regulator of peroxisomes, mitochondria, and their interaction. Here, we provide an overview of the molecular functions of TMEM135 which is crucial for regulating mitochondria, peroxisomes, and lipids. The review also discusses the age-dependent phenotypes in mice with TMEM135 perturbations, emphasizing the importance of a balanced TMEM135 function for the health of the retina and other tissues including the heart, liver, and adipose tissue. Finally, we explore the potential roles of TMEM135 in human age-related retinal diseases, connecting its functions to the pathobiology of AMD.
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Affiliation(s)
- Michael Landowski
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, United States
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Purnima Gogoi
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, United States
| | - Sakae Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, United States
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Akihiro Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, United States
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
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Masson EAY, Serrano J, Leger-Charnay E, Acar N. Cholesterol and oxysterols in retinal neuron-glia interactions: relevance for glaucoma. FRONTIERS IN OPHTHALMOLOGY 2024; 3:1303649. [PMID: 38983043 PMCID: PMC11182186 DOI: 10.3389/fopht.2023.1303649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 12/04/2023] [Indexed: 07/11/2024]
Abstract
Cholesterol is an essential component of cellular membranes, crucial for maintaining their structural and functional integrity. It is especially important for nervous tissues, including the retina, which rely on high amounts of plasma membranes for the transmission of the nervous signal. While cholesterol is by far the most abundant sterol, the retina also contains cholesterol precursors and metabolites, especially oxysterols, which are bioactive molecules. Cholesterol lack or excess is deleterious and some oxysterols are known for their effect on neuron survival. Cholesterol homeostasis must therefore be maintained. Retinal glial cells, especially Müller cells, the principal glial cells of the vertebrate retina, provide mechanical, nutritional, and metabolic support for the neighboring neurons. Several pieces of evidence indicate that Müller cells are major actors of cholesterol homeostasis in the retina, as it is known for other glial cells in the brain. This process is based on a close cooperation with neurons, and sterols can be signaling molecules participating in glia-neuron interactions. While some implication of cholesterol in age-related macular degeneration is now recognized, based on epidemiological and laboratory data, evidence for its role in glaucoma is still scarce. The association between cholesterolemia and glaucoma is controversial, but experimental data suggest that sterols could take part in the pathological processes. It has been demonstrated that Müller glial cells are implicated in the development of glaucoma through an ambivalent reactive retinal gliosis process. The early steps contribute to maintaining retinal homeostasis and favor the survival of ganglion cells, which are targeted during glaucoma. If gliosis persists, dysregulation of the neuroprotective functions, cytotoxic effects of gliotic Müller cells and disruption of glia-neuron interactions lead to an acceleration of ganglion cell death. Sterols could play a role in the glial cell response to glaucomatous injury. This represents an understudied but attractive topic to better understand glaucoma and conceive novel preventive or curative strategies. The present review describes the current knowledge on i) sterol metabolism in retinal glial cells, ii) the potential role of cholesterol in glaucoma, and iii) the possible relationships between cholesterol and oxysterols, glial cells and glaucoma. Focus is put on glia-neuron interactions.
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Affiliation(s)
- Elodie A Y Masson
- Eye and Nutrition Research Group, Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, Dijon, France
| | - Jeanne Serrano
- Eye and Nutrition Research Group, Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, Dijon, France
- Sensory Perception, Glia/Neuron Interaction Research Group, Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, Dijon, France
| | - Elise Leger-Charnay
- Eye and Nutrition Research Group, Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, Dijon, France
| | - Niyazi Acar
- Eye and Nutrition Research Group, Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, Dijon, France
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Rus AA, Militaru IV, Popa I, Munteanu CVA, Sima LE, Platt N, Platt FM, Petrescu ȘM. NPC1 plays a role in the trafficking of specific cargo to melanosomes. J Biol Chem 2023; 299:105024. [PMID: 37423302 PMCID: PMC10407747 DOI: 10.1016/j.jbc.2023.105024] [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: 03/21/2023] [Revised: 06/20/2023] [Accepted: 06/23/2023] [Indexed: 07/11/2023] Open
Abstract
Niemann-Pick type C1 (NPC1) protein is a multimembrane spanning protein of the lysosome limiting membrane that facilitates intracellular cholesterol and sphingolipid transport. Loss-of-function mutations in the NPC1 protein cause Niemann-Pick disease type C1, a lysosomal storage disorder characterized by the accumulation of cholesterol and sphingolipids within lysosomes. To investigate whether the NPC1 protein could also play a role in the maturation of the endolysosomal pathway, here, we have investigated its role in a lysosome-related organelle, the melanosome. Using a NPC1-KO melanoma cell model, we found that the cellular phenotype of Niemann-Pick disease type C1 is associated with a decreased pigmentation accompanied by low expression of the melanogenic enzyme tyrosinase. We propose that the defective processing and localization of tyrosinase, occurring in the absence of NPC1, is a major determinant of the pigmentation impairment in NPC1-KO cells. Along with tyrosinase, two other pigmentation genes, tyrosinase-related protein 1 and Dopachrome-tautomerase have lower protein levels in NPC1 deficient cells. In contrast with the decrease in pigmentation-related protein expression, we also found a significant intracellular accumulation of mature PMEL17, the structural protein of melanosomes. As opposed to the normal dendritic localization of melanosomes, the disruption of melanosome matrix generation in NPC1 deficient cells causes an accumulation of immature melanosomes adjacent to the plasma membrane. Together with the melanosomal localization of NPC1 in WT cells, these findings suggest that NPC1 is directly involved in tyrosinase transport from the trans-Golgi network to melanosomes and melanosome maturation, indicating a novel function for NPC1.
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Affiliation(s)
- Alina Adriana Rus
- Department of Molecular Cell Biology, Institute of Biochemistry, Bucharest, Romania
| | - Ioana V Militaru
- Department of Molecular Cell Biology, Institute of Biochemistry, Bucharest, Romania
| | - Ioana Popa
- Department of Molecular Cell Biology, Institute of Biochemistry, Bucharest, Romania
| | - Cristian V A Munteanu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry, Bucharest, Romania
| | - Livia Elena Sima
- Department of Molecular Cell Biology, Institute of Biochemistry, Bucharest, Romania
| | - Nick Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Ștefana M Petrescu
- Department of Molecular Cell Biology, Institute of Biochemistry, Bucharest, Romania.
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Pfrieger FW. The Niemann-Pick type diseases – A synopsis of inborn errors in sphingolipid and cholesterol metabolism. Prog Lipid Res 2023; 90:101225. [PMID: 37003582 DOI: 10.1016/j.plipres.2023.101225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023]
Abstract
Disturbances of lipid homeostasis in cells provoke human diseases. The elucidation of the underlying mechanisms and the development of efficient therapies represent formidable challenges for biomedical research. Exemplary cases are two rare, autosomal recessive, and ultimately fatal lysosomal diseases historically named "Niemann-Pick" honoring the physicians, whose pioneering observations led to their discovery. Acid sphingomyelinase deficiency (ASMD) and Niemann-Pick type C disease (NPCD) are caused by specific variants of the sphingomyelin phosphodiesterase 1 (SMPD1) and NPC intracellular cholesterol transporter 1 (NPC1) or NPC intracellular cholesterol transporter 2 (NPC2) genes that perturb homeostasis of two key membrane components, sphingomyelin and cholesterol, respectively. Patients with severe forms of these diseases present visceral and neurologic symptoms and succumb to premature death. This synopsis traces the tortuous discovery of the Niemann-Pick diseases, highlights important advances with respect to genetic culprits and cellular mechanisms, and exposes efforts to improve diagnosis and to explore new therapeutic approaches.
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Emri E, Cappa O, Kelly C, Kortvely E, SanGiovanni JP, McKay BS, Bergen AA, Simpson DA, Lengyel I. Zinc Supplementation Induced Transcriptional Changes in Primary Human Retinal Pigment Epithelium: A Single-Cell RNA Sequencing Study to Understand Age-Related Macular Degeneration. Cells 2023; 12:773. [PMID: 36899910 PMCID: PMC10000409 DOI: 10.3390/cells12050773] [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: 02/05/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Zinc supplementation has been shown to be beneficial to slow the progression of age-related macular degeneration (AMD). However, the molecular mechanism underpinning this benefit is not well understood. This study used single-cell RNA sequencing to identify transcriptomic changes induced by zinc supplementation. Human primary retinal pigment epithelial (RPE) cells could mature for up to 19 weeks. After 1 or 18 weeks in culture, we supplemented the culture medium with 125 µM added zinc for one week. RPE cells developed high transepithelial electrical resistance, extensive, but variable pigmentation, and deposited sub-RPE material similar to the hallmark lesions of AMD. Unsupervised cluster analysis of the combined transcriptome of the cells isolated after 2, 9, and 19 weeks in culture showed considerable heterogeneity. Clustering based on 234 pre-selected RPE-specific genes divided the cells into two distinct clusters, we defined as more and less differentiated cells. The proportion of more differentiated cells increased with time in culture, but appreciable numbers of cells remained less differentiated even at 19 weeks. Pseudotemporal ordering identified 537 genes that could be implicated in the dynamics of RPE cell differentiation (FDR < 0.05). Zinc treatment resulted in the differential expression of 281 of these genes (FDR < 0.05). These genes were associated with several biological pathways with modulation of ID1/ID3 transcriptional regulation. Overall, zinc had a multitude of effects on the RPE transcriptome, including several genes involved in pigmentation, complement regulation, mineralization, and cholesterol metabolism processes associated with AMD.
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Affiliation(s)
- Eszter Emri
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University of Belfast, Belfast BT97BL, UK
- Section Ophthalmogenetics, Department of Human Genetics, Queen Emma Centre for Precision Medicine, Amsterdam UMC, Location AMC, 1105AZ Amsterdam, The Netherlands
| | - Oisin Cappa
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University of Belfast, Belfast BT97BL, UK
| | - Caoimhe Kelly
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University of Belfast, Belfast BT97BL, UK
| | - Elod Kortvely
- Immunology, Infectious Diseases and Ophthalmology (I2O) Discovery and Translational Area, Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., 4070 Basel, Switzerland
| | - John Paul SanGiovanni
- Biosciences Research Laboratories, BIO5 Institute, University of Arizona, 1230 North Cherry Avenue, Tucson, AZ 85724, USA
| | - Brian S. McKay
- Department of Ophthalmology and Vision Science, University of Arizona, 1656 E. Mabel Street, Tucson, AZ 85724, USA
| | - Arthur A. Bergen
- Section Ophthalmogenetics, Department of Human Genetics, Queen Emma Centre for Precision Medicine, Amsterdam UMC, Location AMC, 1105AZ Amsterdam, The Netherlands
- The Netherlands Institute for Neuroscience (NIN-KNAW), 1105AZ Amsterdam, The Netherlands
| | - David A. Simpson
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University of Belfast, Belfast BT97BL, UK
| | - Imre Lengyel
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University of Belfast, Belfast BT97BL, UK
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Origin of Retinal Oscillatory Potentials in the Mouse, a Tool to Specifically Locate Retinal Damage. Int J Mol Sci 2023; 24:ijms24043126. [PMID: 36834538 PMCID: PMC9958948 DOI: 10.3390/ijms24043126] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023] Open
Abstract
To determine the origin of oscillatory potentials (OPs), binocular electroretinogram (ERG) recordings were performed under light and dark adaptation on adult healthy C57BL/6J mice. In the experimental group, 1 μL of PBS was injected into the left eye, while the right eye was injected with 1 μL of PBS containing different agents: APB, GABA, Bicuculline, TPMPA, Glutamate, DNQX, Glycine, Strychnine, or HEPES. The OP response depends on the type of photoreceptors involved, showing their maximum response amplitude in the ERG induced by mixed rod/cone stimulation. The oscillatory components of the OPs were affected by the injected agents, with some drugs inducing the complete abolition of oscillations (APB, GABA, Glutamate, or DNQX), whereas other drugs merely reduced the oscillatory amplitudes (Bicuculline, Glycine, Strychnine, or HEPES) or did not even affect the oscillations (TPMPA). Assuming that rod bipolar cells (RBC) express metabotropic Glutamate receptors, GABAA, GABAC, and Glycine receptors and that they release glutamate mainly on Glycinergic AII amacrine cells and GABAergic A17 amacrine cells, which are differently affected by the mentioned drugs, we propose that RBC-AII/A17 reciprocal synapses are responsible for the OP generation in the ERG recordings in the mice. We conclude that the reciprocal synapses between RBC and AII/A17 are the basis of the ERG OP oscillations of the light response, and this fact must be taken into consideration in any ERG test that shows a decrease in the OPs' amplitude.
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7
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Yang J, Chen Y, Zou T, Xue B, Yang F, Wang X, Huo Y, Yan B, Xu Y, He S, Yin Y, Wang J, Zhu X, Zhang L, Zhou Y, Tai Z, Shuai P, Yu M, Luo Q, Cheng Y, Gong B, Zhu X, Zhang J, Sun X, Lin Y, Zhang H, Yang Z. Cholesterol homeostasis regulated by ABCA1 is critical for retinal ganglion cell survival. SCIENCE CHINA. LIFE SCIENCES 2023; 66:211-225. [PMID: 35829808 DOI: 10.1007/s11427-021-2126-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 06/17/2022] [Indexed: 10/17/2022]
Abstract
Genome-wide association studies have suggested a link between primary open-angle glaucoma and the function of ABCA1. ABCA1 is a key regulator of cholesterol efflux and the biogenesis of high-density lipoprotein (HDL) particles. Here, we showed that the POAG risk allele near ABCA1 attenuated ABCA1 expression in cultured cells. Consistently, POAG patients exhibited lower ABCA1 expression, reduced HDL, and higher cholesterol in white blood cells. Ablation of Abca1 in mice failed to form HDL, leading to elevated cholesterol levels in the retina. Counting retinal ganglion cells (RGCs) by using an artificial intelligence (AI) program revealed that Abca1-deficient mice progressively lost RGCs with age. Single-cell RNA sequencing (scRNA-seq) revealed aberrant oxidative phosphorylation in the Abca1-/- retina, as well as activation of the mTORC1 signaling pathway and suppression of autophagy. Treatment of Abca1-/- mice using atorvastatin reduced the cholesterol level in the retina, thereby improving metabolism and protecting RGCs from death. Collectively, we show that lower ABCA1 expression and lower HDL are risk factors for POAG. Accumulated cholesterol in the Abca1-/- retina causes profound aberrant metabolism, leading to a POAG-like phenotype that can be prevented by atorvastatin. Our findings establish statin use as a preventive treatment for POAG associated with lower ABCA1 expression.
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Affiliation(s)
- Jialiang Yang
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Yuhong Chen
- Department of Ophthalmology and Visual Science, Eye and Ear Nose Throat (ENT) Hospital, Fudan University, Shanghai, 200032, China
| | - Tongdan Zou
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Bai Xue
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Fang Yang
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Xiangzhou Wang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Yibo Huo
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Boyun Yan
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Yuxia Xu
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Shiyu He
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Yi Yin
- Institute of Chengdu Biology, Sichuan Translational Medicine Hospital, Chinese Academy of Sciences, Chengdu, 610093, China
| | - Jing Wang
- Institute of Chengdu Biology, Sichuan Translational Medicine Hospital, Chinese Academy of Sciences, Chengdu, 610093, China
| | - Xiong Zhu
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Lin Zhang
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Yu Zhou
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Zhengfu Tai
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Ping Shuai
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Man Yu
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Qian Luo
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Yilian Cheng
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Bo Gong
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, 610072, China
| | - Xianjun Zhu
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, 610072, China
| | - Jing Zhang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Xinghuai Sun
- Department of Ophthalmology and Visual Science, Eye and Ear Nose Throat (ENT) Hospital, Fudan University, Shanghai, 200032, China
| | - Ying Lin
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Houbin Zhang
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China.
| | - Zhenglin Yang
- Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China.
- Institute of Chengdu Biology, Sichuan Translational Medicine Hospital, Chinese Academy of Sciences, Chengdu, 610093, China.
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, 610072, China.
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Intartaglia D, Giamundo G, Conte I. Autophagy in the retinal pigment epithelium: a new vision and future challenges. FEBS J 2022; 289:7199-7212. [PMID: 33993621 PMCID: PMC9786786 DOI: 10.1111/febs.16018] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/07/2021] [Accepted: 05/12/2021] [Indexed: 01/13/2023]
Abstract
The retinal pigment epithelium (RPE) is a highly specialized monolayer of polarized, pigmented epithelial cells that resides between the vessels of the choriocapillaris and the neural retina. The RPE is essential for the maintenance and survival of overlying light-sensitive photoreceptors, as it participates in the formation of the outer blood-retinal barrier, phagocytosis, degradation of photoreceptor outer segment (POS) tips, maintenance of the retinoid cycle, and protection against light and oxidative stress. Autophagy is an evolutionarily conserved 'self-eating' process, designed to maintain cellular homeostasis. The daily autophagy demands in the RPE require precise gene regulation for the digestion and recycling of intracellular and POS components in lysosomes in response to light and stress conditions. In this review, we discuss selective autophagy and focus on the recent advances in our understanding of the mechanism of cell clearance in the RPE for visual function. Understanding how this catabolic process is regulated by both transcriptional and post-transcriptional mechanisms in the RPE will promote the recognition of pathological pathways in genetic disease and shed light on potential therapeutic strategies to treat visual impairments in patients with retinal disorders associated with lysosomal dysfunction.
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Affiliation(s)
| | | | - Ivan Conte
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy,Department of BiologyUniversity of Naples Federico IINaplesItaly
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Li JK, Rao YQ, Koh SK, Zhao P, Zhou L, Li J. Proteomic analysis of s-acylated proteins in human retinal pigment epithelial cells and the role of palmitoylation of Niemann-Pick type C1 protein in cholesterol transport. Front Aging Neurosci 2022; 14:965943. [PMID: 36262888 PMCID: PMC9576141 DOI: 10.3389/fnagi.2022.965943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Palmitoylation is a dynamic process that regulates the activity of the modified proteins. Retinal pigment epithelial (RPE) cells play pivotal roles in the visual cycle and maintaining healthy photoreceptor cells. Dysfunctional RPE cells are often associated with degenerative retinal diseases. The aim of the study was to identify potentially palmitoylated proteins in human RPE cells. By using the detergent-resistant membrane, we found 312 potentially palmitoylated peptides which corresponded to 192 proteins in RPE cells, including 55 new candidate proteins which were not reported before. Gene enrichment analysis highlighted significant enrichment of palmitoylated proteins in cell-matrix adhesion, cell-cell recognition, protein cellular localization, and translation, among others. We further studied the effect of 3 potential palmitoylation sites (Cys 799, 900, and 816) of Niemann-Pick type C1 protein (NPC1) on cholesterol accumulation. We found that mutation of any single Cys alone had no significant effect on intracellular cholesterol accumulation while simultaneous mutation of Cys799 and 800 caused significant cholesterol accumulation in the late endosome. No further cholesterol accumulation was observed by adding another mutation at Cys 816. However, the mutation did not alter the cellular localization of the protein. Conclusion: PRE cells have an abundant number of palmitoylated proteins which are involved in cellular processes critical to visual function. The palmitoylation at Cys799 and 800 was needed for cholesterol export, but not the intracellular localization of NPC1.
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Affiliation(s)
- Jia Kai Li
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Qing Rao
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Siew Kwan Koh
- Singapore Eye Research Institute, Singapore, Singapore
| | - Peiquan Zhao
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lei Zhou
- Singapore Eye Research Institute, Singapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Research Program, Duke-NUS Medical School, National University of Singapore, Singapore, Singapore
- *Correspondence: Lei Zhou,
| | - Jing Li
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Jing Li,
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10
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Loss of the Bardet-Biedl protein Bbs1 alters photoreceptor outer segment protein and lipid composition. Nat Commun 2022; 13:1282. [PMID: 35277505 PMCID: PMC8917222 DOI: 10.1038/s41467-022-28982-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 02/23/2022] [Indexed: 12/22/2022] Open
Abstract
Primary cilia are key sensory organelles whose dysfunction leads to ciliopathy disorders such as Bardet-Biedl syndrome (BBS). Retinal degeneration is common in ciliopathies, since the outer segments (OSs) of photoreceptors are highly specialized primary cilia. BBS1, encoded by the most commonly mutated BBS-associated gene, is part of the BBSome protein complex. Using a bbs1 zebrafish mutant, we show that retinal development and photoreceptor differentiation are unaffected by Bbs1-loss, supported by an initially unaffected transcriptome. Quantitative proteomics and lipidomics on samples enriched for isolated OSs show that Bbs1 is required for BBSome-complex stability and that Bbs1-loss leads to accumulation of membrane-associated proteins in OSs, with enrichment in proteins involved in lipid homeostasis. Disruption of the tightly regulated OS lipid composition with increased OS cholesterol content are paralleled by early functional visual deficits, which precede progressive OS morphological anomalies. Our findings identify a role for Bbs1/BBSome in OS lipid homeostasis, suggesting a pathomechanism underlying retinal degeneration in BBS. Primary cilia are key sensory organelles whose dysfunction leads to ciliopathy disorders such as Bardet-Biedl syndrome (BBS). Here they identify a role for Bbs1 in lipid homeostasis of photoreceptor outer segments in zebrafish, which may contribute to vision loss in patients with Bardet-Biedl syndrome.
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Glial contribution to cyclodextrin-mediated reversal of cholesterol accumulation in murine NPC1-deficient neurons in vivo. Neurobiol Dis 2021; 158:105469. [PMID: 34364974 DOI: 10.1016/j.nbd.2021.105469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/17/2021] [Accepted: 08/02/2021] [Indexed: 12/11/2022] Open
Abstract
Niemann-Pick type C disease is a rare and fatal lysosomal storage disorder presenting severe neurovisceral symptoms. Disease-causing mutations in genes encoding either NPC1 or NPC2 protein provoke accumulation of cholesterol and other lipids in specific structures of the endosomal-lysosomal system and degeneration of specific cells, notably neurons in the central nervous system (CNS). 2-hydroxypropyl-beta-cyclodextrin (CD) emerged as potential therapeutic approach based on animal studies and clinical data, but the mechanism of action in neurons has remained unclear. To address this topic in vivo, we took advantage of the retina as highly accessible part of the CNS and intravitreal injections as mode of drug administration. Coupling CD to gold nanoparticles allowed us to trace its intracellular location. We report that CD enters the endosomal-lysosomal system of neurons in vivo and enables the release of lipid-laden lamellar inclusions, which are then removed from the extracellular space by specific types of glial cells. Our data suggest that CD induces a concerted action of neurons and glial cells to restore lipid homeostasis in the central nervous system.
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12
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Hopf S, Hennermann JB, Schuster AK, Pfeiffer N, Pitz S. Vertical saccadic palsy and foveal retinal thinning in Niemann-Pick disease type C. PLoS One 2021; 16:e0252825. [PMID: 34086834 PMCID: PMC8177533 DOI: 10.1371/journal.pone.0252825] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/23/2021] [Indexed: 11/25/2022] Open
Abstract
Introduction Niemann-Pick type C (NPC) is a lysosomal storage disease that is progressive and life-limiting, with an estimated incidence of 1:120,000 live births. In addition to systemic manifestation with (hepato-)splenomegaly, there are a number of neurological manifestations (ataxia, dysarthria, dementia, cataplexy, epileptic seizures, and psychiatric disorders). Characteristic is vertical supranuclear gaze palsy, which is often overlooked. Early diagnosis and start of therapy improve quality of life. This study aimed to characterize oculomotor dysfunction of NPC patients, and to provide ophthalmologic data including retinal imaging. Methods Eighteen patients with biochemically or genetically diagnosed NPC completed oculomotor and ophthalmologic examination. Ten of them performed saccadometry by infrared based video-oculography. Saccadic parameters were compared to 100 healthy controls, and were correlated with clinical variables. Another subgroup of eight patients received optical coherence tomography (OCT) of the optic disc and the macula, of which the segmented layers were analysed using a crude linear mixed model, and one adjusted for age, sex, and spherical equivalent. Results Saccadometry revealed slowed peak velocity compared to controls most evident vertically. Peak velocity correlated negatively with SARA-Score, but correlation with clinical assessment of saccades was not significant. Clinical features in the assessment of vertical saccades were intensive blinking and head movements to initiate gaze changes, and lateral trajectory of the eyes. Macular OCT revealed significant total retinal thinning in the fovea, specifically of the outer nuclear layer and outer retinal layer. Para- and perifoveal retinal thicknesses, as well as peripapillary retinal nerve fibre layer were normal. Conclusions Foveal thinning was revealed in NPC. It remains to be shown, whether OCT will prove to be useful to monitor progression. Saccadic impairment reflects CNS involvement and therefore is a parameter to demonstrate the progression of NPC, and potentially also the efficacy of new therapies. Saccadometry, in contrast to clinical investigation, allows the precise evaluation of saccades.
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Affiliation(s)
- Susanne Hopf
- Department of Ophthalmology, University Medical Center Mainz, Mainz, Germany
- * E-mail:
| | - Julia B. Hennermann
- Department of Pediatric and Adolescent Medicine, University Medical Center Mainz, Mainz, Germany
| | | | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Center Mainz, Mainz, Germany
| | - Susanne Pitz
- Department of Ophthalmology, University Medical Center Mainz, Mainz, Germany
- Orbital Center, Ophthalmic Clinic, Bürgerhospital Frankfurt, Frankfurt, Germany
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13
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Abstract
Cholesterol is a quantitatively and biologically significant constituent of all mammalian cell membrane, including those that comprise the retina. Retinal cholesterol homeostasis entails the interplay between de novo synthesis, uptake, intraretinal sterol transport, metabolism, and efflux. Defects in these complex processes are associated with several congenital and age-related disorders of the visual system. Herein, we provide an overview of the following topics: (a) cholesterol synthesis in the neural retina; (b) lipoprotein uptake and intraretinal sterol transport in the neural retina and the retinal pigment epithelium (RPE); (c) cholesterol efflux from the neural retina and the RPE; and (d) biology and pathobiology of defects in sterol synthesis and sterol oxidation in the neural retina and the RPE. We focus, in particular, on studies involving animal models of monogenic disorders pertinent to the above topics, as well as in vitro models using biochemical, metabolic, and omic approaches. We also identify current knowledge gaps and opportunities in the field that beg further research in this topic area.
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Affiliation(s)
- Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA.
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14
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Understanding and Treating Niemann-Pick Type C Disease: Models Matter. Int J Mol Sci 2020; 21:ijms21238979. [PMID: 33256121 PMCID: PMC7730076 DOI: 10.3390/ijms21238979] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
Biomedical research aims to understand the molecular mechanisms causing human diseases and to develop curative therapies. So far, these goals have been achieved for a small fraction of diseases, limiting factors being the availability, validity, and use of experimental models. Niemann–Pick type C (NPC) is a prime example for a disease that lacks a curative therapy despite substantial breakthroughs. This rare, fatal, and autosomal-recessive disorder is caused by defects in NPC1 or NPC2. These ubiquitously expressed proteins help cholesterol exit from the endosomal–lysosomal system. The dysfunction of either causes an aberrant accumulation of lipids with patients presenting a large range of disease onset, neurovisceral symptoms, and life span. Here, we note general aspects of experimental models, we describe the line-up used for NPC-related research and therapy development, and we provide an outlook on future topics.
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15
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Kwon W, Freeman SA. Phagocytosis by the Retinal Pigment Epithelium: Recognition, Resolution, Recycling. Front Immunol 2020; 11:604205. [PMID: 33281830 PMCID: PMC7691529 DOI: 10.3389/fimmu.2020.604205] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022] Open
Abstract
Tissue-resident phagocytes are responsible for the routine binding, engulfment, and resolution of their meals. Such populations of cells express appropriate surface receptors that are tailored to recognize the phagocytic targets of their niche and initiate the actin polymerization that drives internalization. Tissue-resident phagocytes also harbor enzymes and transporters along the endocytic pathway that orchestrate the resolution of ingested macromolecules from the phagolysosome. Solutes fluxed from the endocytic pathway and into the cytosol can then be reutilized by the phagocyte or exported for their use by neighboring cells. Such a fundamental metabolic coupling between resident phagocytes and the tissue in which they reside is well-emphasized in the case of retinal pigment epithelial (RPE) cells; specialized phagocytes that are responsible for the turnover of photoreceptor outer segments (POS). Photoreceptors are prone to photo-oxidative damage and their long-term health depends enormously on the disposal of aged portions of the outer segment. The phagocytosis of the POS by the RPE is the sole means of this turnover and clearance. RPE are themselves mitotically quiescent and therefore must resolve the ingested material to prevent their toxic accumulation in the lysosome that otherwise leads to retinal disorders. Here we describe the sequence of events underlying the healthy turnover of photoreceptors by the RPE with an emphasis on the signaling that ensures the phagocytosis of the distal POS and on the transport of solutes from the phagosome that supersedes its resolution. While other systems may utilize different receptors and transporters, the biophysical and metabolic manifestations of such events are expected to apply to all tissue-resident phagocytes that perform regular phagocytic programs.
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Affiliation(s)
- Whijin Kwon
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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16
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Bird A. Role of retinal pigment epithelium in age-related macular disease: a systematic review. Br J Ophthalmol 2020; 105:1469-1474. [PMID: 32950958 DOI: 10.1136/bjophthalmol-2020-317447] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/27/2020] [Accepted: 09/04/2020] [Indexed: 02/07/2023]
Abstract
Age-related macular disease (AMD) is a major cause of blindness and there is little treatment currently available by which the progress of the basic disorder can be modulated. Histological and clinical studies show that the major tissues involved are the outer retina, retinal pigment epithelium, Bruch's membrane and choroid. Because of a wide variation of phenotype from one case to another, it has been suggested that accurate phenotyping would be necessary for assessment of the effectiveness of treatment that is tissue-directed. However, based on findings from the study of human donor material and animal models of disease and of cell culture, it is concluded that retinal pigment epithelial dysfunction plays a central role in the disease process in most, if not all, cases of early AMD. The metabolism of phagosomal material, particularly lipids, and energy generation are interdependent, and dysfunction of both appears to be important in the genesis of disease. Evidence exists to suggest that both can be modulated therapeutically. These metabolic functions are amenable to further investigation in both the normal state and in disease. Once fully characterised, it is likely that treatment could be directed towards a limited number of functions in single tissue, thus simplifying treatment strategies.
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Affiliation(s)
- Alan Bird
- Genetics, Moorfields Eye Hospital NHS Foundation Trust, London, UK
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17
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Storm T, Burgoyne T, Futter CE. Membrane trafficking in the retinal pigment epithelium at a glance. J Cell Sci 2020; 133:133/16/jcs238279. [PMID: 32855284 DOI: 10.1242/jcs.238279] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a highly specialised pigmented monolayer sandwiched between the choroid and the photoreceptors in the retina. Key functions of the RPE include transport of nutrients to the neural retina, removal of waste products and water from the retina to the blood, recycling of retinal chromophores, absorption of scattered light and phagocytosis of the tips of the photoreceptor outer segments. These functions place a considerable membrane trafficking burden on the RPE. In this Cell Science at a Glance article and the accompanying poster, we focus on RPE-specific adaptations of trafficking pathways. We outline mechanisms underlying the polarised expression of membrane proteins, melanosome biogenesis and movement, and endocytic trafficking, as well as photoreceptor outer segment phagocytosis and degradation. We also briefly discuss theories of how dysfunction in trafficking pathways contributes to retinal disease.
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Affiliation(s)
- Tina Storm
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Thomas Burgoyne
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Clare E Futter
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
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18
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Retinal axonal degeneration in Niemann-Pick type C disease. J Neurol 2020; 267:2070-2082. [PMID: 32222928 PMCID: PMC7320959 DOI: 10.1007/s00415-020-09796-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 11/21/2022]
Abstract
Objective Niemann–Pick disease type C1 (NPC1) is a rare autosomal-recessive lysosomal storage disorder presenting with a broad clinical spectrum ranging from a severe infantile-onset neurovisceral disorder to late-onset neurodegenerative disease. Optical coherence tomography (OCT) is established to detect retinal degeneration in vivo. We examined NPC1-patients (NPC1-P), clinically asymptomatic NPC1-mutation carriers (NPC1-MC), and healthy controls (HC) to (1) identify retinal degeneration in NPC1-disease and (2) to investigate possible subclinical retinal degeneration in NPC1-MC. Methods Fourteen NPC1-P, 17 NPC1-MC, and 31 age-matched HC were examined using spectral-domain OCT. Neurological examinations, clinical scales [modified Disability Rating Scale (mDRS); Scale for the Rating and Assessment of Ataxia (SARA); Spinocerebellar Ataxia Functional Index (SCAFI)], and video-oculography (VOG) were correlated with OCT data. Results Macular retinal nerve fiber layer and volumes of combined ganglion cell and inner plexiform layer were significantly lower in NPC1-P compared to HC [mRNFL (µm):0.13 ± 0.01 vs. 0.14 ± 0.02; p = 0.01; GCIPL (mm3):0.60 ± 0.05 vs. 0.62 ± 0.04; p = 0.04]. No significant differences were found in NPC1-MC in comparison to HC. In NPC1-P, the amplitude of upward vertical saccades showed positive associations with peripapillary RNFL (ρ = 0.645; p < 0.05), and thinned GCIP (ρ = 0.609; p < 0.05), but not in NPC1-MC. In NPC1-P correlations between combined outer plexiform layer and outer nuclear layer (OPONL) with mDRS (r = − 0.617; p < 0.05) and GCIP with SARA (r = − 0.622; p < 0.05) were observed. Furthermore, in NPC1-MC, motor scores were negatively associated with pRNFL (ρ = − 0.677; p < 0.01). Conclusions Using OCT, we showed retinal degeneration in NPC1-P and significant correlation between retinal neuroaxonal degeneration with clinical measurements. We observed a non-significant trend of retinal degeneration in NPC1-MC correlating with subclinical motor abnormalities. Based on these preliminary data, OCT may be an important marker of neurodegeneration in NPC1-disease after onset of clinical symptoms.
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19
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Lakkaraju A, Umapathy A, Tan LX, Daniele L, Philp NJ, Boesze-Battaglia K, Williams DS. The cell biology of the retinal pigment epithelium. Prog Retin Eye Res 2020; 78:100846. [PMID: 32105772 PMCID: PMC8941496 DOI: 10.1016/j.preteyeres.2020.100846] [Citation(s) in RCA: 185] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023]
Abstract
The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically situated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and function. Dysfunction of the RPE underlies many inherited and acquired diseases that cause permanent blindness. Decades of research have yielded valuable insight into the cell biology of the RPE. In recent years, new technologies such as live-cell imaging have resulted in major advancement in our understanding of areas such as the daily phagocytosis and clearance of photoreceptor outer segment tips, autophagy, endolysosome function, and the metabolic interplay between the RPE and photoreceptors. In this review, we aim to integrate these studies with an emphasis on appropriate models and techniques to investigate RPE cell biology and metabolism, and discuss how RPE cell biology informs our understanding of retinal disease.
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Affiliation(s)
- Aparna Lakkaraju
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Ankita Umapathy
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Li Xuan Tan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Lauren Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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20
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Song JY, Wang XG, Zhang ZY, Che L, Fan B, Li GY. Endoplasmic reticulum stress and the protein degradation system in ophthalmic diseases. PeerJ 2020; 8:e8638. [PMID: 32117642 PMCID: PMC7036270 DOI: 10.7717/peerj.8638] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/26/2020] [Indexed: 12/16/2022] Open
Abstract
Objective Endoplasmic reticulum (ER) stress is involved in the pathogenesis of various ophthalmic diseases, and ER stress-mediated degradation systems play an important role in maintaining ER homeostasis during ER stress. The purpose of this review is to explore the potential relationship between them and to find their equilibrium sites. Design This review illustrates the important role of reasonable regulation of the protein degradation system in ER stress-mediated ophthalmic diseases. There were 128 articles chosen for review in this study, and the keywords used for article research are ER stress, autophagy, UPS, ophthalmic disease, and ocular. Data sources The data are from Web of Science, PubMed, with no language restrictions from inception until 2019 Jul. Results The ubiquitin proteasome system (UPS) and autophagy are important degradation systems in ER stress. They can restore ER homeostasis, but if ER stress cannot be relieved in time, cell death may occur. However, they are not independent of each other, and the relationship between them is complementary. Therefore, we propose that ER stability can be achieved by adjusting the balance between them. Conclusion The degradation system of ER stress, UPS and autophagy are interrelated. Because an imbalance between the UPS and autophagy can cause cell death, regulating that balance may suppress ER stress and protect cells against pathological stress damage.
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Affiliation(s)
- Jing-Yao Song
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun, China
| | - Xue-Guang Wang
- Department of Traumatic Orthopedics, Third People's Hospital of Jinan, Jinan, China
| | - Zi-Yuan Zhang
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun, China
| | - Lin Che
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun, China
| | - Bin Fan
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun, China
| | - Guang-Yu Li
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun, China
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21
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Bräuer AU, Kuhla A, Holzmann C, Wree A, Witt M. Current Challenges in Understanding the Cellular and Molecular Mechanisms in Niemann-Pick Disease Type C1. Int J Mol Sci 2019; 20:ijms20184392. [PMID: 31500175 PMCID: PMC6771135 DOI: 10.3390/ijms20184392] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 02/06/2023] Open
Abstract
Rare diseases are a heterogeneous group of very different clinical syndromes. Their most common causes are defects in the hereditary material, and they can therefore be passed on to descendants. Rare diseases become manifest in almost all organs and often have a systemic expressivity, i.e., they affect several organs simultaneously. An effective causal therapy is often not available and can only be developed when the underlying causes of the disease are understood. In this review, we focus on Niemann–Pick disease type C1 (NPC1), which is a rare lipid-storage disorder. Lipids, in particular phospholipids, are a major component of the cell membrane and play important roles in cellular functions, such as extracellular receptor signaling, intracellular second messengers and cellular pressure regulation. An excessive storage of fats, as seen in NPC1, can cause permanent damage to cells and tissues in the brain and peripheral nervous system, but also in other parts of the body. Here, we summarize the impact of NPC1 pathology on several organ systems, as revealed in experimental animal models and humans, and give an overview of current available treatment options.
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Affiliation(s)
- Anja U Bräuer
- Research Group Anatomy, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, D-26129 Oldenburg, Germany.
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, D-26129 Oldenburg, Germany.
| | - Angela Kuhla
- Institute for Experimental Surgery, Rostock University Medical Center, Schillingallee 69a, 18057 Rostock, Germany.
- Center of Transdisciplinary Neuroscience Rostock, D-18147 Rostock, Germany.
| | - Carsten Holzmann
- Center of Transdisciplinary Neuroscience Rostock, D-18147 Rostock, Germany.
- Institute of Medical Genetics, Rostock University Medical Center, D-18057 Rostock, Germany.
| | - Andreas Wree
- Center of Transdisciplinary Neuroscience Rostock, D-18147 Rostock, Germany.
- Institute of Anatomy, Rostock University Medical Center, D-18057 Rostock, Germany.
| | - Martin Witt
- Center of Transdisciplinary Neuroscience Rostock, D-18147 Rostock, Germany.
- Institute of Anatomy, Rostock University Medical Center, D-18057 Rostock, Germany.
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22
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Neßlauer AM, Gläser A, Gräler M, Engelmann R, Müller-Hilke B, Frank M, Burstein C, Rolfs A, Neidhardt J, Wree A, Witt M, Bräuer AU. A therapy with miglustat, 2-hydroxypropyl-ß-cyclodextrin and allopregnanolone restores splenic cholesterol homeostasis in Niemann-pick disease type C1. Lipids Health Dis 2019; 18:146. [PMID: 31248418 PMCID: PMC6598286 DOI: 10.1186/s12944-019-1088-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/11/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Niemann-Pick disease type C1 (NPC1) is an autosomal-recessive lipid-storage disorder with an estimated minimal incidence of 1/120,000 live births. Besides other neuronal and visceral symptoms, NPC1 patients develop spleen dysfunction, isolated spleno- or hepatosplenomegaly and infections. The mechanisms of splenomegaly and alterations of lipid metabolism-related genes in NPC1 disease are still poorly understood. METHODS Here, we used an NPC1 mouse model to study a splenoprotective effect of a treatment with miglustat, 2-hydroxypropyl-ß-cyclodextrin and allopregnanolone and showed that this treatment has a positive effect on spleen morphology and lipid metabolism. RESULTS Disease progress can be halted and blocked at the molecular level. Mutant Npc1 (Npc1-/-) mice showed increased spleen weight and increased lipid accumulation that could be avoided by our treatment. Also, FACS analyses showed that the increased number of splenic myeloid cells in Npc1-/- mice was normalized by the treatment. Treated Npc1-/- mice showed decreased numbers of cytotoxic T cells and increased numbers of T helper cells. CONCLUSIONS In summary, the treatment promotes normal spleen morphology, stabilization of lipid homeostasis and blocking of inflammation, but alters the composition of T cell subtypes.
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Affiliation(s)
- Anna-Maria Neßlauer
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstraße 9, 18057, Rostock, Germany
| | - Anne Gläser
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstraße 9, 18057, Rostock, Germany.,Research Group Anatomy, School of Medicine and Health Sciences, Department für Humanmedizin, Abteilung Anatomie, Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky Straße 9-11, 26129, Oldenburg, Germany
| | - Markus Gräler
- Department of Anesthesiology and Intensive Care Medicine, Center for Sepsis Control and Care (CSCC), and the Center for Molecular Biomedicine (CMB), Jena University Hospital, Hans-Knöll-Str. 2, 07745, Jena, Germany
| | - Robby Engelmann
- Institute of Immunology, Rostock University Medical Center, Schillingallee 70, 18057, Rostock, Germany
| | - Brigitte Müller-Hilke
- Institute of Immunology, Rostock University Medical Center, Schillingallee 70, 18057, Rostock, Germany
| | - Marcus Frank
- Medical Biology and Electron Microscopy Center, Rostock University Medical Center, Strempelstraße 14, 18057, Rostock, Germany
| | - Christine Burstein
- Institute of Clinical Chemistry and Pathobiochemistry, Rostock University Medical Center, Ernst-Heydemann-Straße 6, 18057, Rostock, Germany
| | - Arndt Rolfs
- Centogene AG, Am Strande 7, 18055, Rostock, Germany
| | - John Neidhardt
- Human Genetics, Faculty of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Andreas Wree
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstraße 9, 18057, Rostock, Germany
| | - Martin Witt
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstraße 9, 18057, Rostock, Germany
| | - Anja U Bräuer
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstraße 9, 18057, Rostock, Germany. .,Research Group Anatomy, School of Medicine and Health Sciences, Department für Humanmedizin, Abteilung Anatomie, Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky Straße 9-11, 26129, Oldenburg, Germany. .,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
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23
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Curcio CA. Antecedents of Soft Drusen, the Specific Deposits of Age-Related Macular Degeneration, in the Biology of Human Macula. Invest Ophthalmol Vis Sci 2018; 59:AMD182-AMD194. [PMID: 30357337 PMCID: PMC6733529 DOI: 10.1167/iovs.18-24883] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AMD pathobiology was irreversibly changed by the recent discovery of extracellular cholesterol-containing deposits in the subretinal space, between the photoreceptors and retinal pigment epithelium (RPE), called subretinal drusenoid deposits (SDDs). SDDs strikingly mirror the topography of rod photoreceptors in human macula, raising the question of whether an equivalent process results in a deposition related to foveal cones. Herein we propose that AMD's pathognomonic lesion-soft drusen and basal linear deposit (BLinD, same material, diffusely distributed)-is the leading candidate. Epidemiologic, clinical, and histologic data suggest that these deposits are most abundant in the central macula, under the fovea. Strong evidence presented in a companion article supports the idea that the dominant ultrastructural component is large apolipoprotein B,E-containing lipoproteins, constitutively secreted by RPE. Lipoprotein fatty acids are dominated by linoleate (implicating diet) rather than docosahexaenoate (implicating photoreceptors); we seek within the retina cellular relationships and dietary drivers to explain soft druse topography. The delivery of xanthophyll pigments to highly evolved and numerous Müller cells in the human fovea, through RPE, is one strong candidate, because Müller cells are the main reservoir of these pigments, which replenish from diet. We propose that the evolution of neuroglial relations and xanthophyll delivery that underlie exquisite human foveal vision came with a price, that is, soft drusen and sequela, long after our reproductive years.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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Witt M, Thiemer R, Meyer A, Schmitt O, Wree A. Main Olfactory and Vomeronasal Epithelium Are Differently Affected in Niemann-Pick Disease Type C1. Int J Mol Sci 2018; 19:ijms19113563. [PMID: 30424529 PMCID: PMC6274921 DOI: 10.3390/ijms19113563] [Citation(s) in RCA: 6] [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] [Received: 10/01/2018] [Revised: 11/01/2018] [Accepted: 11/08/2018] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Olfactory impairment is one of the earliest symptoms in neurodegenerative disorders that has also been documented in Niemann-Pick disease type C1 (NPC1). NPC1 is a very rare, neurovisceral lipid storage disorder, characterized by a deficiency of Npc1 gene function that leads to progressive neurodegeneration. Here, we compared the pathologic effect of defective Npc1 gene on the vomeronasal neuroepithelium (VNE) with that of the olfactory epithelium (OE) in an NPC1 mouse model. METHODS Proliferation in the VNE and OE was assessed by applying a bromodeoxyuridine (BrdU) protocol. We further compared the immunoreactivities of anti-olfactory marker protein (OMP), and the lysosomal marker cathepsin-D in both epithelia. To investigate if degenerative effects of both olfactory systems can be prevented or reversed, some animals were treated with a combination of miglustat/allopregnanolone/2-hydroxypropyl-cyclodextrin (HPβCD), or a monotherapy with HPβCD alone. RESULTS Using BrdU to label dividing cells of the VNE, we detected a proliferation increase of 215% ± 12% in Npc1-/- mice, and 270% ± 10% in combination- treated Npc1-/- animals. The monotherapy with HPβCD led to an increase of 261% ± 10.5% compared to sham-treated Npc1-/- mice. Similar to the OE, we assessed the high regenerative potential of vomeronasal progenitor cells. OMP reactivity in the VNE of Npc1-/- mice was not affected, in contrast to that observed in the OE. Concomitantly, cathepsin-D reactivity in the VNE was virtually absent. Conclusion: Vomeronasal receptor neurons are less susceptible against NPC1 pathology than olfactory receptor neurons. Compared to control mice, however, the VNE of Npc1-/- mice displays an increased neuroregenerative potential, indicating compensatory cell renewal.
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Affiliation(s)
- Martin Witt
- Department of Anatomy, University of Rostock, 18057 Rostock, Germany.
| | - René Thiemer
- Department of Anatomy, University of Rostock, 18057 Rostock, Germany.
| | - Anja Meyer
- Department of Anatomy, University of Rostock, 18057 Rostock, Germany.
| | - Oliver Schmitt
- Department of Anatomy, University of Rostock, 18057 Rostock, Germany.
| | - Andreas Wree
- Department of Anatomy, University of Rostock, 18057 Rostock, Germany.
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Meyer A, Gläser A, Bräuer AU, Wree A, Strotmann J, Rolfs A, Witt M. Olfactory Performance as an Indicator for Protective Treatment Effects in an Animal Model of Neurodegeneration. Front Integr Neurosci 2018; 12:35. [PMID: 30154701 PMCID: PMC6102364 DOI: 10.3389/fnint.2018.00035] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/26/2018] [Indexed: 12/12/2022] Open
Abstract
Background: Neurodegenerative diseases are often accompanied by olfactory deficits. Here we use a rare neurovisceral lipid storage disorder, Niemann–Pick disease C1 (NPC1), to illustrate disease-specific dynamics of olfactory dysfunction and its reaction upon therapy. Previous findings in a transgenic mouse model (NPC1-/-) showed severe morphological and electrophysiological alterations of the olfactory epithelium (OE) and the olfactory bulb (OB) that ameliorated under therapy with combined 2-hydroxypropyl-ß-cyclodextrin (HPßCD)/allopregnanolone/miglustat or HPßCD alone. Methods: A buried pellet test was conducted to assess olfactory performance. qPCR for olfactory key markers and several olfactory receptors was applied to determine if their expression was changed under treatment conditions. In order to investigate the cell dynamics of the OB, we determined proliferative and apoptotic activities using a bromodeoxyuridine (BrdU) protocol and caspase-3 (cas-3) activity. Further, we performed immunohistochemistry and western blotting for microglia (Iba1), astroglia (GFAP) and tyrosine hydroxylase (TH). Results: The buried pellet test revealed a significant olfactory deterioration in NPC1-/- mice, which reverted to normal levels after treatment. At the OE level, mRNA for olfactory markers showed no changes; the mRNA level of classical olfactory receptor (ORs) was unaltered, that of unique ORs was reduced. In the OB of untreated NPC1-/- mice, BrdU and cas-3 data showed increased proliferation and apoptotic activity, respectively. At the protein level, Iba1 and GFAP in the OB indicated increased microgliosis and astrogliosis, which was prevented by treatment. Conclusion: Due to the unique plasticity especially of peripheral olfactory components the results show a successful treatment in NPC1 condition with respect to normalization of olfaction. Unchanged mRNA levels for olfactory marker protein and distinct olfactory receptors indicate no effects in the OE in NPC1-/- mice. Olfactory deficits are thus likely due to central deficits at the level of the OB. Further studies are needed to examine if olfactory performance can also be changed at a later onset and interrupted treatment of the disease. Taken together, our results demonstrate that olfactory testing in patients with NPC1 may be successfully used as a biomarker during the monitoring of the treatment.
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Affiliation(s)
- Anja Meyer
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Anne Gläser
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany.,Research Group Anatomy, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Anja U Bräuer
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany.,Research Group Anatomy, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Andreas Wree
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Jörg Strotmann
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Arndt Rolfs
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Martin Witt
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
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Ramachandra Rao S, Pfeffer BA, Más Gómez N, Skelton LA, Keiko U, Sparrow JR, Rowsam AM, Mitchell CH, Fliesler SJ. Compromised phagosome maturation underlies RPE pathology in cell culture and whole animal models of Smith-Lemli-Opitz Syndrome. Autophagy 2018; 14:1796-1817. [PMID: 29979914 PMCID: PMC6135634 DOI: 10.1080/15548627.2018.1490851] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 05/25/2018] [Accepted: 06/11/2018] [Indexed: 12/27/2022] Open
Abstract
Treatment of rats with the cholesterol pathway inhibitor AY9944 produces an animal model of Smith-Lemli-Opitz syndrome (SLOS), an autosomal recessive disease caused by defective cholesterol synthesis. This SLOS rat model undergoes progressive and irreversible degeneration of the neural retina, with associated pathological features of the retinal pigmented epithelium (RPE). Here, we provide further insights into the mechanism involved in the RPE pathology. In the SLOS rat model, markedly increased RPE apical autofluorescence is observed, compared to untreated animals, which correlates with increased levels of A2E and other bisretinoids. Utilizing cultured human induced pluripotent stem cell (iPSC)- derived SLOS RPE cells, we found significantly elevated steady-state levels of 7-dehydrocholesterol (7DHC) and decreased cholesterol levels (key biochemical hallmarks of SLOS). Western blot analysis revealed altered levels of the macroautophagy/autophagy markers MAP1LC3B-II and SQSTM1/p62, and build-up of ubiquitinated proteins. Accumulation of immature autophagosomes was accompanied by inefficient degradation of phagocytized, exogenously supplied retinal rod outer segments (as evidenced by persistence of the C-terminal 1D4 epitope of RHO [rhodopsin]) in SLOS RPE compared to iPSC-derived normal human control. SLOS RPE cells exhibited lysosomal pH levels and CTSD activity within normal physiological limits, thus discounting the involvement of perturbed lysosomal function. Furthermore, 1D4-positive phagosomes that accumulated in the RPE in both pharmacological and genetic rodent models of SLOS failed to fuse with lysosomes. Taken together, these observations suggest that defective phagosome maturation underlies the observed RPE pathology. The potential relevance of these findings to SLOS and the requirement of cholesterol for phagosome maturation are discussed.
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Affiliation(s)
- Sriganesh Ramachandra Rao
- Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, Jacobs School of Medicine and Biomedical Sciences, SUNY-University at Buffalo, Buffalo, NY, USA
- SUNY Eye Institute, Buffalo, NY, USA
- Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Bruce A. Pfeffer
- Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, Jacobs School of Medicine and Biomedical Sciences, SUNY-University at Buffalo, Buffalo, NY, USA
- SUNY Eye Institute, Buffalo, NY, USA
- Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Néstor Más Gómez
- Department of Anatomy & Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
| | - Lara A. Skelton
- Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, Jacobs School of Medicine and Biomedical Sciences, SUNY-University at Buffalo, Buffalo, NY, USA
- SUNY Eye Institute, Buffalo, NY, USA
- Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Ueda Keiko
- Departments of Ophthalmology (Harkness Eye Institute) and Pathology & Cell Biology, Columbia University, College of Physicians & Surgeons, NY, NY, USA
| | - Janet R. Sparrow
- Departments of Ophthalmology (Harkness Eye Institute) and Pathology & Cell Biology, Columbia University, College of Physicians & Surgeons, NY, NY, USA
| | - Aryn M. Rowsam
- Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, Jacobs School of Medicine and Biomedical Sciences, SUNY-University at Buffalo, Buffalo, NY, USA
- SUNY Eye Institute, Buffalo, NY, USA
- Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Claire H. Mitchell
- Department of Anatomy & Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
| | - Steven J. Fliesler
- Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, Jacobs School of Medicine and Biomedical Sciences, SUNY-University at Buffalo, Buffalo, NY, USA
- SUNY Eye Institute, Buffalo, NY, USA
- Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
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Onur İU, Aşula MF, Ekinci C, Mert M. Macula halo syndrome. Int Ophthalmol 2018; 39:1391-1395. [PMID: 29845436 DOI: 10.1007/s10792-018-0939-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 05/02/2018] [Indexed: 10/16/2022]
Abstract
INTRODUCTION Niemann-Pick disease (NPD) is a hereditary lysosomal storage disorder in which mutations in the sphingomyelin phosphodiesterase gene leads to partial or complete deficiency of the sphingomyelinase enzyme. Niemann-Pick Type B is the intermediate form associated with hepatosplenomegaly, foam cells in the bone marrow, hyperlipidemia and diffuse pulmonary infiltrates, which is generally diagnosed in late adolescence. Central nervous system is not affected, and some cases may display macular halo. CASE A 45-year-old female seen in ophthalmology clinic for the examination of the eyes. Extraocular motility was normal bilaterally, and the visual acuity was 20/25 for both eyes. Biomicroscopic examination revealed faint corneal haze bilaterally, Circular pale granular depositions were detected in the parafoveal retina on both eyes. Optical coherence tomography (OCT) revealed thin hyperreflective band corresponding to depositions located in the parafoveolar inner retina. Microperimeter showed slight depression in retinal sensitivity, which was more pronounced particularly on perifovea rather than parafovea. CONCLUSIONS Challenge to identify the NPD subtype of this case is associated with phenotypic characteristics on a wider spectrum that overlap the currently described subtypes.
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Affiliation(s)
- İsmail Umut Onur
- Bakirkoy Dr. Sadi Konuk Training & Research Hospital, İstanbul, Turkey
| | | | | | - Meral Mert
- Bakirkoy Dr. Sadi Konuk Training & Research Hospital, İstanbul, Turkey
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Marshall CA, Watkins-Chow DE, Palladino G, Deutsch G, Chandran K, Pavan WJ, Erickson RP. In Niemann-Pick C1 mouse models, glial-only expression of the normal gene extends survival much further than do changes in genetic background or treatment with hydroxypropyl-beta-cyclodextrin. Gene 2017; 643:117-123. [PMID: 29223359 DOI: 10.1016/j.gene.2017.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/01/2017] [Accepted: 12/06/2017] [Indexed: 11/19/2022]
Abstract
The Npc1nmf164 allele of Npc1 provides a mouse model for Niemann-Pick disease type C1 (NPC1), a genetic disease known to have a widely variable phenotype. The transfer of the Npc1nmf164 mutation from the C57BL/6J inbred strain to the BALB/cJ inbred strain increased the mean lifespan from 117.8days to 153.1days, confirming that the severity of the NPC1 phenotype is strongly influenced by genetic background. The transfer of another Npc1 allele, Npc1nih, to this background also extended survival of the homozygotes indicating that the modifying effect of BALB/cJ is not limited to a single allele of Npc1. The increased longevity due to the BALB/cJ background did not map to a previously mapped modifier on chromosome 19, indicating the presence of additional genes impacting disease severity. The previously studied Glial Fibrillary Acidic Protein promoter-Npc1 cDNA transgene (GFAP-Npc1) which only expresses NPC1 in astrocytes further extended the lifespan of Npc1nmf164 homozygotes on a BALB/cJ background (up to 600days). Hydroxypropyl-β-cyclodextrin (HPβCD) treatment, not previously tested in the Npc1nmf164 mutant, extended life in the Npc1nmf164 homozygotes but not the transgenic, Npc1nmf164 mice on the BALB/cJ background. In all cases, lack of weight gain and early cerebellar symptoms of loss of motor control were found. At termination, the one mouse sacrificed for histological studies showed severe, diffuse pulmonary alveolar proteinosis suggesting that pulmonary abnormalities in NPC1 mouse models are not unique to the Npc1nih allele.
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Affiliation(s)
- Craig A Marshall
- Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ 85724-5073, United States
| | - Dawn E Watkins-Chow
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Giampiero Palladino
- Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ 85724-5073, United States
| | - Gail Deutsch
- Department of Pathology, Seattle Children's Hospital, Seattle, WA, United States
| | - Keshav Chandran
- Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ 85724-5073, United States
| | - William J Pavan
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Robert P Erickson
- Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ 85724-5073, United States.
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Cuenca N, Ortuño-Lizarán I, Pinilla I. Cellular Characterization of OCT and Outer Retinal Bands Using Specific Immunohistochemistry Markers and Clinical Implications. Ophthalmology 2017; 125:407-422. [PMID: 29037595 DOI: 10.1016/j.ophtha.2017.09.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/16/2017] [Accepted: 09/14/2017] [Indexed: 02/01/2023] Open
Abstract
PURPOSE OCT has been a technological breakthrough in the diagnosis, treatment, and follow-up of many ocular diseases, especially retinal and neuro-ophthalmologic pathologic conditions. Until now, several controversies have arisen over the specific cell types that the bands observed in the OCT represent, especially over the 4 outer retinal bands. DESIGN To correlate the 4 outer hyperreflective bands observed in the OCT with the histologic structures using human retinal sections and immunocytochemistry at the fovea level. PARTICIPANTS Eyes from human donors. METHODS Vertical cryosections of human retinas were immunostained with antibodies specific for cones photoreceptors, bipolar cells, mitochondria, Müller cells, and retinal pigment epithelium (RPE) cells and were visualized using confocal microscopy. MAIN OUTCOME MEASURES Morphological correlation between histology and OCT at the fovea level. RESULTS Triple immunolabeling allowed distinguishing between cells types and different cell compartments. Immunostaining with guanine nucleotide-binding protein β 3 (GNB3) and cellular retinaldehyde-binding protein (CRALBP) antibodies showed all retinal layers at the foveola, especially the separation between the outer nuclear layer and the Henle fiber layer. CRALBP and cytochrome C (Cyt C) immunolabeling revealed that hyperreflective bands 1 and 2, observed in the OCT, correspond to the outer limiting membrane and the cone ellipsoids, respectively, separated by the cone myoids. CRALBP, cytochrome C, and GNB3 showed that the RPE interdigitations extend along the entire external segment of the cones, we do not believe them to be the structure responsible for forming the third band. However, the identification of small fragments of cone outer segments within the RPE led us to characterize the third band as the cone phagosomes located in the top of the RPE. Finally, we propose that the fourth band corresponds to the accumulation of mitochondria at the basal portion of the RPE, as identified by cytochrome C immunoreactivity, and that the hyporeflective band between bands 3 and 4 corresponds to the RPE nuclei and melanosomes zone. CONCLUSIONS This study proposes a new interpretation of the outer retinal bands that leads to a more accurate interpretation of OCT images, providing information about the health of cones and their relationship with the RPE, and could help to form a better understanding of retinal disease diagnosis and prognosis.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, Alicante University, Alicante, Spain; Alicante Institute for Health and Biomedical Research (ISABIAL-FISABIO Foundation), Alicante, Spain; Multidisciplinary Institute for Environmental Studies "Ramón Margalef," University of Alicante, Alicante, Spain.
| | - Isabel Ortuño-Lizarán
- Department of Physiology, Genetics and Microbiology, Alicante University, Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa University Hospital, Zaragoza, Spain; Aragon Health Science Institute, Aragon, Spain
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Storti F, Raphael G, Griesser V, Klee K, Drawnel F, Willburger C, Scholz R, Langmann T, von Eckardstein A, Fingerle J, Grimm C, Maugeais C. Regulated efflux of photoreceptor outer segment-derived cholesterol by human RPE cells. Exp Eye Res 2017; 165:65-77. [PMID: 28943268 DOI: 10.1016/j.exer.2017.09.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/18/2017] [Indexed: 12/19/2022]
Abstract
Genetic studies have linked age-related macular degeneration (AMD) to genes involved in high-density lipoprotein (HDL) metabolism, including ATP-binding cassette transporter A1 (ABCA1). The retinal pigment epithelium (RPE) handles large amounts of lipids, among others cholesterol, partially derived from internalized photoreceptor outer segments (OS) and lipids physiologically accumulate in the aging eye. To analyze the potential function of ABCA1 in the eye, we measured cholesterol efflux, the first step of HDL generation, in RPE cells. We show the expression of selected genes related to HDL metabolism in mouse and human eyecups as well as in ARPE-19 and human primary RPE cells. Immunofluorescence staining revealed localization of ABCA1 on both sides of polarized RPE cells. This was functionally confirmed by directional efflux to apolipoprotein AI (ApoA-I) of 3H-labeled cholesterol given to the cells via serum or via OS. ABCA1 expression and activity was modulated using a liver-X-receptor (LXR) agonist and an ABCA1 neutralizing antibody, demonstrating that the efflux was ABCA1-dependent. We concluded that the ABCA1-mediated lipid efflux pathway, and hence HDL biosynthesis, is functional in RPE cells towards both the basal (choroidal) and apical (subretinal) space. Impaired activity of the pathway might cause age-related perturbations of lipid homeostasis in the outer retina and thus may contribute to disease development and/or progression.
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Affiliation(s)
- Federica Storti
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland
| | - Gabriele Raphael
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Vera Griesser
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Katrin Klee
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Faye Drawnel
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Carolin Willburger
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Rebecca Scholz
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | | | - Jürgen Fingerle
- Natural and Medical Sciences Institute, University of Tübingen, Tübingen, Germany
| | - Christian Grimm
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), University of Zurich, Zurich, Switzerland.
| | - Cyrille Maugeais
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
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Reversal of Pathologic Lipid Accumulation in NPC1-Deficient Neurons by Drug-Promoted Release of LAMP1-Coated Lamellar Inclusions. J Neurosci 2017; 36:8012-25. [PMID: 27466344 DOI: 10.1523/jneurosci.0900-16.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/15/2016] [Indexed: 02/05/2023] Open
Abstract
UNLABELLED Aging and pathologic conditions cause intracellular aggregation of macromolecules and the dysfunction and degeneration of neurons, but the mechanisms are largely unknown. Prime examples are lysosomal storage disorders such as Niemann-Pick type C (NPC) disease, where defects in the endosomal-lysosomal protein NPC1 or NPC2 cause intracellular accumulation of unesterified cholesterol and other lipids leading to neurodegeneration and fatal neurovisceral symptoms. Here, we investigated the impact of NPC1 deficiency on rodent neurons using pharmacologic and genetic models of the disease. Improved ultrastructural detection of lipids and correlative light and electron microscopy identified lamellar inclusions as the subcellular site of cholesterol accumulation in neurons with impaired NPC1 activity. Immunogold labeling combined with transmission electron microscopy revealed the presence of CD63 on internal lamellae and of LAMP1 on the membrane surrounding the inclusions, indicating their origins from intraluminal vesicles of late endosomes and of a lysosomal compartment, respectively. Lamellar inclusions contained cell-intrinsic cholesterol and surface-labeled GM1, indicating the incorporation of plasma membrane components. Scanning electron microscopy revealed that the therapeutic drug candidate β-cyclodextrin induces the subplasmalemmal location of lamellar inclusions and their subsequent release to the extracellular space. In parallel, β-cyclodextrin mediated the NPC1-independent redistribution of cholesterol within neurons and thereby abolished a deleterious cycle of enhanced cholesterol synthesis and its intracellular accumulation, which was indicated by neuron-specific transcript analysis. Our study provides new mechanistic insight into the pathologic aggregation of macromolecules in neurons and suggests exocytosis as cellular target for its therapeutic reversal. SIGNIFICANCE STATEMENT Many neurodegenerative diseases involve pathologic accumulation of molecules within neurons, but the subcellular location and the cellular impact are often unknown and therapeutic approaches lacking. We investigated these questions in the lysosomal storage disorder Niemann-Pick type C (NPC), where a defect in intracellular cholesterol transport causes loss of neurons and fatal neurovisceral symptoms. Here, we identify lamellar inclusions as the subcellular site of lipid accumulation in neurons, we uncover a vicious cycle of cholesterol synthesis and accretion, which may cause gradual neurodegeneration, and we reveal how β-cyclodextrin, a potential therapeutic drug, reverts these changes. Our study provides new mechanistic insight in NPC disease and uncovers new targets for therapeutic approaches.
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2-Hydroxypropyl-beta-cyclodextrin (HPβCD) reduces age-related lipofuscin accumulation through a cholesterol-associated pathway. Sci Rep 2017; 7:2197. [PMID: 28526856 PMCID: PMC5438378 DOI: 10.1038/s41598-017-02387-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 04/26/2017] [Indexed: 11/08/2022] Open
Abstract
Oxidative stress causes significant increases in both cholesterol uptake and intracellular accumulation of the aging biomarker lipofuscin. Here we show that HPβCD addition mitigates these adverse effects in human fibroblasts by significantly reducing LDLr and SREBP1 gene expression. In the absence of oxidative stress, HPβCD addition induces a paradoxical response, increasing cholesterol accumulation (but not lipofuscin) via upregulation of cholesterol biosynthesis. These two distinct, but opposite effects highlight a previously overlooked therapeutic consideration: the cholesterol content of the treated cell determines which cholesterol pathways, either beneficial or harmful, are responsive to HPβCD.
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Canterini S, Dragotto J, Dardis A, Zampieri S, De Stefano ME, Mangia F, Erickson RP, Fiorenza MT. Shortened primary cilium length and dysregulated Sonic hedgehog signaling in Niemann-Pick C1 disease. Hum Mol Genet 2017; 26:2277-2289. [DOI: 10.1093/hmg/ddx118] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/25/2017] [Indexed: 11/13/2022] Open
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Hindle SJ, Hebbar S, Schwudke D, Elliott CJH, Sweeney ST. A saposin deficiency model in Drosophila: Lysosomal storage, progressive neurodegeneration and sensory physiological decline. Neurobiol Dis 2016; 98:77-87. [PMID: 27913291 PMCID: PMC5319729 DOI: 10.1016/j.nbd.2016.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/10/2016] [Accepted: 11/25/2016] [Indexed: 02/06/2023] Open
Abstract
Saposin deficiency is a childhood neurodegenerative lysosomal storage disorder (LSD) that can cause premature death within three months of life. Saposins are activator proteins that promote the function of lysosomal hydrolases that mediate the degradation of sphingolipids. There are four saposin proteins in humans, which are encoded by the prosaposin gene. Mutations causing an absence or impaired function of individual saposins or the whole prosaposin gene lead to distinct LSDs due to the storage of different classes of sphingolipids. The pathological events leading to neuronal dysfunction induced by lysosomal storage of sphingolipids are as yet poorly defined. We have generated and characterised a Drosophila model of saposin deficiency that shows striking similarities to the human diseases. Drosophila saposin-related (dSap-r) mutants show a reduced longevity, progressive neurodegeneration, lysosomal storage, dramatic swelling of neuronal soma, perturbations in sphingolipid catabolism, and sensory physiological deterioration. Our data suggests a genetic interaction with a calcium exchanger (Calx) pointing to a possible calcium homeostasis deficit in dSap-r mutants. Together these findings support the use of dSap-r mutants in advancing our understanding of the cellular pathology implicated in saposin deficiency and related LSDs. Drosophila model of PSD recapitulates neurodegenerative phenotype of human PSD. Preferential degeneration of sensory regions correlates with loss of sensory function. Sphingosine levels rise with age with an imbalance in sphingosine/ceramide ratios. Genetic interaction with the Na +/Ca + exchanger points to a calcium regulation deficit.
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Affiliation(s)
| | - Sarita Hebbar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Dominik Schwudke
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | | | - Sean T Sweeney
- Department of Biology, University of York, York YO10 5DD, UK.
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Boya P, Esteban-Martínez L, Serrano-Puebla A, Gómez-Sintes R, Villarejo-Zori B. Autophagy in the eye: Development, degeneration, and aging. Prog Retin Eye Res 2016; 55:206-245. [PMID: 27566190 DOI: 10.1016/j.preteyeres.2016.08.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 02/06/2023]
Abstract
Autophagy is a catabolic pathway that promotes the degradation and recycling of cellular components. Proteins, lipids, and even whole organelles are engulfed in autophagosomes and delivered to the lysosome for elimination. In response to stress, autophagy mediates the degradation of cell components, which are recycled to generate the nutrients and building blocks required to sustain cellular homeostasis. Moreover, it plays an important role in cellular quality control, particularly in neurons, in which the total burden of altered proteins and damaged organelles cannot be reduced by redistribution to daughter cells through cell division. Research has only begun to examine the role of autophagy in the visual system. The retina, a light-sensitive tissue, detects and transmits electrical impulses through the optic nerve to the visual cortex in the brain. Both the retina and the eye are exposed to a variety of environmental insults and stressors, including genetic mutations and age-associated alterations that impair their function. Here, we review the main studies that have sought to explain autophagy's importance in visual function. We describe the role of autophagy in retinal development and cell differentiation, and discuss the implications of autophagy dysregulation both in physiological aging and in important diseases such as age-associated macular degeneration and glaucoma. We also address the putative role of autophagy in promoting photoreceptor survival and discuss how selective autophagy could provide alternative means of protecting retinal cells. The findings reviewed here underscore the important role of autophagy in maintaining proper retinal function and highlight novel therapeutic approaches for blindness and other diseases of the eye.
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Affiliation(s)
- Patricia Boya
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Lorena Esteban-Martínez
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Ana Serrano-Puebla
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Raquel Gómez-Sintes
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Beatriz Villarejo-Zori
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
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Fernández-Navarro J, Aldea P, de Hoz R, Salazar JJ, Ramírez AI, Rojas B, Gallego BI, Triviño A, Tejerina T, Ramírez JM. Neuroprotective Effects of Low-Dose Statins in the Retinal Ultrastructure of Hypercholesterolemic Rabbits. PLoS One 2016; 11:e0154800. [PMID: 27144842 PMCID: PMC4856380 DOI: 10.1371/journal.pone.0154800] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/19/2016] [Indexed: 11/19/2022] Open
Abstract
To evaluate the pleiotropic effects to statins, we analyze the qualitative and quantitative retinal changes in hypercholesterolemic rabbits after a low-dosage statin treatment. For this purpose, New Zealand rabbits were split into three groups: control (G0; n = 10), fed a standard diet; hypercholesterolemic (G1; n = 8), fed a 0.5% cholesterol-enriched diet for 8 months; and statins (G2; n = 8), fed a 0.5% cholesterol-enriched diet for 8 months, together with the administration of statin (pravastatin or fluvastatin sodium) at a dose of 2 mg / kg / day each diet. The retinas were analyzed by transmission electron microscopy and immunohistochemistry (glial fibrillary acidic protein). The retinal thickness of nuclear and plexiform layers were quantified in semi-thin sections. The results revealed that the low-statin-treated rabbits in comparison with the hypercholesterolemic group showed: i) a more preserved structure in all retinal layers; ii) a significant reduction in retinal thickness; iii) a decrease in cell death in the nuclear-and ganglion-cell layers; iv) a reduction of hydropic degeneration in the plexiform and nerve-fiber layers; v) a preservation of astrocytes and of the retinal area occupied by them; and vi) a better-preserved retinal vascular structure. Our findings indicate that low doses of statins can prevent retinal degeneration, acting on retinal macroglia, neurons and retinal vessels, despite that hypercholesterolemia remained unchanged. Thus, the pleiotropic effects of the statins may help safeguard the retinal ultrastructure.
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Affiliation(s)
- Judith Fernández-Navarro
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
| | - Pilar Aldea
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
| | - Rosa de Hoz
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Óptica y Optometría, UCM, Spain
| | - Juan J Salazar
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Óptica y Optometría, UCM, Spain
| | - Ana I Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Óptica y Optometría, UCM, Spain
| | - Blanca Rojas
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Medicina, UCM, Spain
| | - Beatriz I. Gallego
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Óptica y Optometría, UCM, Spain
| | - Alberto Triviño
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Medicina, UCM, Spain
| | - Teresa Tejerina
- Department of Pharmacology, School of Medicine, Complutense University, Madrid, Spain
| | - José M. Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo. Universidad Complutense Madrid (UCM), Spain
- Facultad de Medicina, UCM, Spain
- * E-mail:
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Perusek L, Sahu B, Parmar T, Maeno H, Arai E, Le YZ, Subauste CS, Chen Y, Palczewski K, Maeda A. Di-retinoid-pyridinium-ethanolamine (A2E) Accumulation and the Maintenance of the Visual Cycle Are Independent of Atg7-mediated Autophagy in the Retinal Pigmented Epithelium. J Biol Chem 2015; 290:29035-44. [PMID: 26468292 PMCID: PMC4661415 DOI: 10.1074/jbc.m115.682310] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/03/2015] [Indexed: 01/10/2023] Open
Abstract
Autophagy is an evolutionarily conserved catabolic mechanism that relieves cellular stress by removing/recycling damaged organelles and debris through the action of lysosomes. Compromised autophagy has been implicated in many neurodegenerative diseases, including retinal degeneration. Here we examined retinal phenotypes resulting from RPE-specific deletion of the autophagy regulatory gene Atg7 by generating Atg7(flox/flox);VMD2-rtTA-cre+ mice to determine whether autophagy is essential for RPE functions including retinoid recycling. Atg7-deficient RPE displayed abnormal morphology with increased RPE thickness, cellular debris and vacuole formation indicating that autophagy is important in maintaining RPE homeostasis. In contrast, 11-cis-retinal content, ERGs and retinal histology were normal in mice with Atg7-deficient RPE in both fasted and fed states. Because A2E accumulation in the RPE is associated with pathogenesis of both Stargardt disease and age-related macular degeneration (AMD) in humans, deletion of Abca4 was introduced into Atg7(flox/flox);VMD2-rtTA-cre+ mice to investigate the role of autophagy during A2E accumulation. Comparable A2E concentrations were detected in the eyes of 6-month-old mice with and without Atg7 from both Abca4(-/-) and Abca4(+/+) backgrounds. To identify other autophagy-related molecules involved in A2E accumulation, we performed gene expression array analysis on A2E-treated human RPE cells and found up-regulation of four autophagy related genes; DRAM1, NPC1, CASP3, and EIF2AK3/PERK. These observations indicate that Atg7-mediated autophagy is dispensable for retinoid recycling and A2E deposition; however, autophagy plays a role in coping with stress caused by A2E accumulation.
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Affiliation(s)
| | | | - Tanu Parmar
- From the Departments of Ophthalmology and Visual Sciences
| | - Hiroshi Maeno
- From the Departments of Ophthalmology and Visual Sciences
| | - Eisuke Arai
- From the Departments of Ophthalmology and Visual Sciences
| | - Yun-Zheng Le
- Departments of Medicine Endocrinology, Cell Biology, and Ophthalmology and Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Carlos S Subauste
- Medicine, Case Western Reserve University, Cleveland, Ohio 44106 and
| | - Yu Chen
- Pharmacology and Cleveland Center for Membrane and Structural Biology, and
| | | | - Akiko Maeda
- From the Departments of Ophthalmology and Visual Sciences, Pharmacology and Cleveland Center for Membrane and Structural Biology, and
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Palladino G, Loizzo S, Fortuna A, Canterini S, Palombi F, Erickson RP, Mangia F, Fiorenza MT. Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin. Orphanet J Rare Dis 2015; 10:133. [PMID: 26458950 PMCID: PMC4603821 DOI: 10.1186/s13023-015-0348-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 09/27/2015] [Indexed: 12/21/2022] Open
Abstract
Background The lysosomal storage disorder, Niemann Pick type C1 (NPC1), presents a variable phenotype including neurovisceral and neurological symptoms. 2-Hydroxypropyl-ß-cyclodextrin (HPßCD)-based therapies are presently the most promising route of intervention. While severe cerebellar dysfunction remains the main disabling feature of NPC1, sensory functions including auditory and olfactory ones are also affected. Morphological and functional anomalies of Npc1−/− mouse retina have also been observed, although the functional integrity of the visual pathway from retina to visual cortex is still unsettled. We have addressed this issue by characterizing the visual evoked potential (VEP) response of Npc1−/− mice and determining if/how HPßCD administration influences the VEPs of both Npc1−/− and Npc1+/+ mice. Methods VEP elicited by a brief visual stimulus were recorded from the scalp overlying the visual cortex of adult (PN, postnatal days 60, 75, 85 and 100) Npc1+/+ and Npc1−/− mice that had received repeated injections of either HPßCD or plain vehicle. The first injection was given at PN4 and was followed by a second one at PN7 and thereafter by weekly injections up to PN49. Cholesterol accumulation and myelin loss were finally assessed by filipin staining and myelin basic protein immunohistochemistry, respectively. Results and discussion We have found that the transmission of visual signals from retina to visual cortex is negatively influenced by the loss of Npc1 function. In fact, the VEP response of Npc1−/− mice displayed a highly significant increase in the latency compared to that of Npc1+/+ mice. HPßCD administration fully rescued this defect and counteracted the cholesterol accumulation in retinal ganglion cells and dorsal lateral geniculate nucleus neurons, as well as the myelin loss in optic nerve fibers and axons projecting to the visual cortex observed in of Npc1−/− mice. By contrast, HPßCD administration had no effect on the VEP response of Npc1+/+ mice, further strengthening the treatment efficacy. Conclusions This study pinpoints the analysis of VEP response as a potentially accurate and non-invasive approach to assess neural activity and visual information processing in NPC1 patients, as well as for monitoring the progression of the disease and assessing the efficacy of potential therapies. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0348-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Giampiero Palladino
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Stefano Loizzo
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, via Regina Elena 299, 00161, Rome, Italy
| | - Andrea Fortuna
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, via Regina Elena 299, 00161, Rome, Italy
| | - Sonia Canterini
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Fioretta Palombi
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161, Rome, Italy
| | - Robert P Erickson
- Department of Pediatrics, University of Arizona, Tucson, AZ, 85724-5073, USA
| | - Franco Mangia
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Maria Teresa Fiorenza
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy.
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Lacritin and other autophagy associated proteins in ocular surface health. Exp Eye Res 2015; 144:4-13. [PMID: 26318608 DOI: 10.1016/j.exer.2015.08.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/20/2015] [Accepted: 08/18/2015] [Indexed: 12/19/2022]
Abstract
Advantage may be taken of macroautophagy ('autophagy') to promote ocular health. Autophagy continually captures aged or damaged cellular material for lysosomal degradation and recyling. When autophagic flux is chronically elevated, or alternatively deficient, health suffers. Chronic elevation of flux and stress are the consequence of inflammatory cytokines or of dry eye tears but not normal tears invitro. Exogenous tear protein lacritin transiently accelerates flux to restore homeostasis invitro and corneal health invivo, and yet the monomeric active form of lacritin appears to be selectively deficient in dry eye. Tissue transglutaminase-dependent cross-linking of monomer decreases monomer quantity and monomer affinity for coreceptor syndecan-1 thereby abrogating activity. Tissue transglutaminase is elevated in dry eye. Mutation of arylsulfatase A, arylsulfatase B, ceroid-lipofuscinosis neuronal 3, mucolipin, or Niemann-Pick disease type C1 respectively underlie several diseases of apparently insufficient autophagic flux that affect the eye, including: metachromatic leukodystrophy, mucopolysaccharidosis type VI, juvenile-onset Batten disease, mucolipidosis IV, and Niemann-Pick type C associated with myelin sheath destruction of corneal sensory and ciliary nerves and of the optic nerve; corneal clouding, ocular hypertension, glaucoma and optic nerve atrophy; accumulation of 'ceroid-lipofuscin' in surface conjunctival cells, and in ganglion and neuronal cells; decreased visual acuity and retinal dystrophy; and neurodegeneration. For some, enzyme or gene replacement, or substrate reduction, therapy is proving to be successful. Here we discuss examples of restoring ocular surface homeostasis through alteration of autophagy, with particular attention to lacritin.
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Khoh-Reiter S, Sokolowski SA, Jessen B, Evans M, Dalvie D, Lu S. Contribution of membrane trafficking perturbation to retinal toxicity. Toxicol Sci 2015; 145:383-95. [PMID: 25771199 DOI: 10.1093/toxsci/kfv059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The retina is a highly structured tissue that is formed by layers containing 7 different cell types. The photoreceptor cell is a specialized type of neuron in the retina that is capable of absorbing and converting light into electrophysiological signals. There is a constant renewal process for photoreceptors consisting of intermittent shedding of the distal tips of the photosensitive outer segment and subsequent phagocytosis (uptake, degradation and recycling) by retinal pigmented epithelial (RPE) cells. This rebuilding process is essential for vision and the survival of photoreceptors and RPE cells. Drugs with a basic moiety have the potential to accumulate in the lysosome and impair its functions including the phagocytosis process, which could hinder clearance of outer segments and ultimately induce retinopathy. To determine the prevalence of this cellular mechanism in retinal toxicity, a collection of proprietary compounds associated with retinal toxicity were subjected to a battery of in vitro tests using the human adult retinal pigmented epithelium cell line, ARPE-19. The tests included a phagocytosis assay, and lysosomal and autophagosomal staining. The compounds that induced retinopathy clustered in the basic and lipophilic region, which drives lysosomal sequestration. This accumulation coincided with phagocytosis inhibition and an increase in autophagosome staining, suggesting a blockage of the membrane trafficking process. A correlation between the physicochemical properties and in vitro lysosomal pathway effects was established. These data reveal the importance of physicochemical properties of compounds and lysosome accumulation as a potential mechanism for drug-induced retinopathy and demonstrate the usefulness of in vitro screening in predicting this liability.
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Affiliation(s)
- Su Khoh-Reiter
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
| | - Sharon A Sokolowski
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
| | - Bart Jessen
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
| | - Mark Evans
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
| | - Deepak Dalvie
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
| | - Shuyan Lu
- *Drug Safety Research and Development, Pfizer Inc., San Diego, California, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., San Diego, California
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Yan X, Ma L, Hovakimyan M, Lukas J, Wree A, Frank M, Guthoff R, Rolfs A, Witt M, Luo J. Defects in the retina of Niemann-pick type C 1 mutant mice. BMC Neurosci 2014; 15:126. [PMID: 25472750 PMCID: PMC4267119 DOI: 10.1186/s12868-014-0126-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/12/2014] [Indexed: 11/24/2022] Open
Abstract
Background Niemann-Pick type C1 (NPC1) disease is an inherited lysosomal storage disease caused by mutation of the Npc1 gene, resulting in a progressive accumulation of unesterified cholesterol and glycolipids in lysosomes of multiple tissues and leading to neurodegeneration and other disease. In Npc1 mutant mice, retinal degeneration including impaired visual function, lipofuscin accumulation in the pigment epithelium and ganglion cells as well as photoreceptor defects has been found. However, the pathologies of other individual cell types of the retina in Npc1 mutant mice are still not fully clear. We hypothesized that horizontal cells, amacrine cells, bipolar cells and glial cells are also affected in the retina of Npc1 mutant mice. Results Immunohistochemistry and electron microscopy were used to investigate pathologies of ganglion cells, horizontal cells, amacrine cells, bipolar cells, and optic nerves as well as altered activity of glial cells in Npc1 mutant mice. Electron microscopy reveals that electron-dense inclusions are generally accumulated in ganglion cells, bipolar cells, Müller cells, and in the optic nerve. Furthermore, abnormal arborisation and ectopic processes of horizontal and amacrine cells as well as defective bipolar cells are observed by immunohistochemistry for specific cellular markers. Furthermore, hyperactivity of glial cells, including astrocytes, microglial cells, and Müller cells, is also revealed. Conclusions Our data extend previous findings to show multiple defects in the retina of Npc1 mutant mice, suggesting an important role of Npc1 protein in the normal function of the retina. Electronic supplementary material The online version of this article (doi:10.1186/s12868-014-0126-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xin Yan
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Gehlsheimer Strasse 20, D-18147, Rostock, Germany.
| | - Lucy Ma
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Gehlsheimer Strasse 20, D-18147, Rostock, Germany.
| | - Marina Hovakimyan
- Institute for Biomedical Engineering, Rostock University Medical Center, F.-Barnewitz Strasse 4, D-18119, Rostock, Germany.
| | - Jan Lukas
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Gehlsheimer Strasse 20, D-18147, Rostock, Germany.
| | - Andreas Wree
- Department of Anatomy, Rostock University Medical Center, Gertrudenstrsse 9, D-18055, Rostock, Germany.
| | - Marcus Frank
- Electron Microscopy Center, Rostock University Medical Center, Strempelstr. 14, D-18057, Rostock, Germany.
| | - Rudolf Guthoff
- Department of Ophthalmology, Rostock University Medical Center, Doberaner Strasse 140, D-18057, Rostock, Germany.
| | - Arndt Rolfs
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Gehlsheimer Strasse 20, D-18147, Rostock, Germany.
| | - Martin Witt
- Department of Anatomy, Rostock University Medical Center, Gertrudenstrsse 9, D-18055, Rostock, Germany.
| | - Jiankai Luo
- Albrecht-Kossel-Institute for Neuroregeneration, Rostock University Medical Center, Gehlsheimer Strasse 20, D-18147, Rostock, Germany.
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Buard I, Pfrieger FW. Relevance of neuronal and glial NPC1 for synaptic input to cerebellar Purkinje cells. Mol Cell Neurosci 2014; 61:65-71. [DOI: 10.1016/j.mcn.2014.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/27/2014] [Accepted: 06/05/2014] [Indexed: 10/25/2022] Open
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Cholesterol in the retina: the best is yet to come. Prog Retin Eye Res 2014; 41:64-89. [PMID: 24704580 DOI: 10.1016/j.preteyeres.2014.03.002] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023]
Abstract
Historically understudied, cholesterol in the retina is receiving more attention now because of genetic studies showing that several cholesterol-related genes are risk factors for age-related macular degeneration (AMD) and because of eye pathology studies showing high cholesterol content of drusen, aging Bruch's membrane, and newly found subretinal lesions. The challenge before us is determining how the cholesterol-AMD link is realized. Meeting this challenge will require an excellent understanding these genes' roles in retinal physiology and how chorioretinal cholesterol is maintained. In the first half of this review, we will succinctly summarize physico-chemical properties of cholesterol, its distribution in the human body, general principles of maintenance and metabolism, and differences in cholesterol handling in human and mouse that impact on experimental approaches. This information will provide a backdrop to the second part of the review focusing on unique aspects of chorioretinal cholesterol homeostasis, aging in Bruch's membrane, cholesterol in AMD lesions, a model for lesion biogenesis, a model for macular vulnerability based on vascular biology, and alignment of AMD-related genes and pathobiology using cholesterol and an atherosclerosis-like progression as unifying features. We conclude with recommendations for the most important research steps we can take towards delineating the cholesterol-AMD link.
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Fourgeux C, Martine L, Acar N, Bron AM, Creuzot-Garcher CP, Bretillon L. In vivo consequences of cholesterol-24S-hydroxylase (CYP46A1) inhibition by voriconazole on cholesterol homeostasis and function in the rat retina. Biochem Biophys Res Commun 2014; 446:775-81. [DOI: 10.1016/j.bbrc.2014.01.118] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 01/23/2014] [Indexed: 01/06/2023]
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Vance JE, Karten B. Niemann-Pick C disease and mobilization of lysosomal cholesterol by cyclodextrin. J Lipid Res 2014; 55:1609-21. [PMID: 24664998 DOI: 10.1194/jlr.r047837] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Indexed: 12/31/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is a lysosomal storage disease in which endocytosed cholesterol becomes sequestered in late endosomes/lysosomes (LEs/Ls) because of mutations in either the NPC1 or NPC2 gene. Mutations in either of these genes can lead to impaired functions of the NPC1 or NPC2 proteins and progressive neurodegeneration as well as liver and lung disease. NPC1 is a polytopic protein of the LE/L limiting membrane, whereas NPC2 is a soluble protein in the LE/L lumen. These two proteins act in tandem and promote the export of cholesterol from LEs/Ls. Consequently, a defect in either NPC1 or NPC2 causes cholesterol accumulation in LEs/Ls. In this review, we summarize the molecular mechanisms leading to NPC disease, particularly in the CNS. Recent exciting data on the mechanism by which the cholesterol-sequestering agent cyclodextrin can bypass the functions of NPC1 and NPC2 in the LEs/Ls, and mobilize cholesterol from LEs/Ls, will be highlighted. Moreover, the possible use of cyclodextrin as a valuable therapeutic agent for treatment of NPC patients will be considered.
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Affiliation(s)
- Jean E Vance
- The Group on Molecular and Cell Biology of Lipids and Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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Movassagh M, Mudvari P, Kokkinaki M, Edwards NJ, Golestaneh N, Horvath A. Analysis for co-occurring sequence features identifies link between common synonymous variant and an early-terminated NPC1 isoform. J Clin Bioinforma 2014. [DOI: 10.1186/2043-9113-4-14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Hovakimyan M, Meyer A, Lukas J, Luo J, Gudziol V, Hummel T, Rolfs A, Wree A, Witt M. Olfactory deficits in Niemann-Pick type C1 (NPC1) disease. PLoS One 2013; 8:e82216. [PMID: 24391715 PMCID: PMC3877006 DOI: 10.1371/journal.pone.0082216] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/24/2013] [Indexed: 01/22/2023] Open
Abstract
Background Niemann-Pick type C disease (NPC) is a rare autosomal recessive lipid storage disease characterized by progressive neurodegeneration. As only a few studies have been conducted on the impact of NPC on sensory systems, we used a mutant mouse model (NPC1−/−) to examine the effects of this disorder to morphologically distinct regions of the olfactory system, namely the olfactory epithelium (OE) and olfactory bulb (OB). Methodology/Principal findings For structural and functional analysis immunohistochemistry, electron microscopy, western blotting, and electrophysiology have been applied. For histochemistry and western blotting, we used antibodies against a series of neuronal and glia marker proteins, as well as macrophage markers. NPC1−/− animals present myelin-like lysosomal deposits in virtually all types of cells of the peripheral and central olfactory system. Especially supporting cells of the OE and central glia cells are affected, resulting in pronounced astrocytosis and microgliosis in the OB and other olfactory cortices. Up-regulation of Galectin-3, Cathepsin D and GFAP in the cortical layers of the OB underlines the critical role and location of the OB as a possible entrance gate for noxious substances. Unmyelinated olfactory afferents of the lamina propria seem less affected than ensheathing cells. Supporting the structural findings, electro-olfactometry of the olfactory mucosa suggests that NPC1−/− animals exhibit olfactory and trigeminal deficits. Conclusions/Significance Our data demonstrate a pronounced neurodegeneration and glia activation in the olfactory system of NPC1−/−, which is accompanied by sensory deficits.
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Affiliation(s)
- Marina Hovakimyan
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Anja Meyer
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Jan Lukas
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Jiankai Luo
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Volker Gudziol
- Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany
| | - Thomas Hummel
- Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany
| | - Arndt Rolfs
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Andreas Wree
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Martin Witt
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
- * E-mail:
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Mechanism of inflammation in age-related macular degeneration: an up-to-date on genetic landmarks. Mediators Inflamm 2013; 2013:435607. [PMID: 24369445 PMCID: PMC3863457 DOI: 10.1155/2013/435607] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/28/2013] [Indexed: 12/13/2022] Open
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment among people over 50 years of age, accounting for up to 50% of all cases of legal blindness in Western countries. Although the aging represents the main determinant of AMD, it must be considered a multifaceted disease caused by interactions among environmental risk factors and genetic backgrounds. Mounting evidence and/or arguments document the crucial role of inflammation and immune-mediated processes in the pathogenesis of AMD. Proinflammatory effects secondary to chronic inflammation (e.g., alternative complement activation) and heterogeneous types of oxidative stress (e.g., impaired cholesterol homeostasis) can result in degenerative damages at the level of crucial macular structures, that is photoreceptors, retinal pigment epithelium, and Bruch's membrane. In the most recent years, the association of AMD with genes, directly or indirectly, involved in immunoinflammatory pathways is increasingly becoming an essential core for AMD knowledge. Starting from the key basic-research notions detectable at the root of AMD pathogenesis, the present up-to-date paper reviews the best-known and/or the most attractive genetic findings linked to the mechanisms of inflammation of this complex disease.
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McNeill A, Roberti G, Lascaratos G, Hughes D, Mehta A, Garway-Heath DF, Schapira AH. Retinal thinning in Gaucher disease patients and carriers: results of a pilot study. Mol Genet Metab 2013; 109:221-3. [PMID: 23639447 PMCID: PMC3682181 DOI: 10.1016/j.ymgme.2013.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/02/2013] [Indexed: 12/02/2022]
Abstract
Both Gaucher disease patients and heterozygous glucocerebrosidase mutation carriers are at increased risk of Parkinson's disease. Retinal thinning has been reported in early Parkinson's disease. Here we used optical coherence tomography to demonstrate thinning of the retinal ganglion cell layer in Gaucher disease patients and carriers who manifest clinical markers of potential early neurodegeneration. Optical coherence tomography may help identify Gaucher disease patients and carriers at increased risk of developing Parkinson's disease.
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Affiliation(s)
- Alisdair McNeill
- Department of Clinical Neurosciences, UCL Institute of Neurology, UK
| | - Gloria Roberti
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Gerassimos Lascaratos
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Derralynn Hughes
- Lysosomal Storage Disorders Unit, Royal Free Hospital, London, UK
| | - Atul Mehta
- Lysosomal Storage Disorders Unit, Royal Free Hospital, London, UK
| | - David F. Garway-Heath
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Anthony H.V. Schapira
- Department of Clinical Neurosciences, UCL Institute of Neurology, UK
- Corresponding author at: Department of Clinical Neurosciences, Upper Level 3, UCL Institute of Neurology, Royal Free Campus, Pond Street, London NW3 2PF, UK. Fax: + 44 20 7472 6829.
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Zheng W, Reem RE, Omarova S, Huang S, DiPatre PL, Charvet CD, Curcio CA, Pikuleva IA. Spatial distribution of the pathways of cholesterol homeostasis in human retina. PLoS One 2012; 7:e37926. [PMID: 22629470 PMCID: PMC3358296 DOI: 10.1371/journal.pone.0037926] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 04/30/2012] [Indexed: 01/25/2023] Open
Abstract
Background The retina is a light-sensitive tissue lining the inner surface of the eye and one of the few human organs whose cholesterol maintenance is still poorly understood. Challenges in studies of the retina include its complex multicellular and multilayered structure; unique cell types and functions; and specific physico-chemical environment. Methodology/Principal Findings We isolated specimens of the neural retina (NR) and underlying retinal pigment epithelium (RPE)/choroid from six deceased human donors and evaluated them for expression of genes and proteins representing the major pathways of cholesterol input, output and regulation. Eighty-four genes were studied by PCR array, 16 genes were assessed by quantitative real time PCR, and 13 proteins were characterized by immunohistochemistry. Cholesterol distribution among different retinal layers was analyzed as well by histochemical staining with filipin. Our major findings pertain to two adjacent retinal layers: the photoreceptor outer segments of NR and the RPE. We demonstrate that in the photoreceptor outer segments, cholesterol biosynthesis, catabolism and regulation via LXR and SREBP are weak or absent and cholesterol content is the lowest of all retinal layers. Cholesterol maintenance in the RPE is different, yet the gene expression also does not appear to be regulated by the SREBPs and varies significantly among different individuals. Conclusions/Significance This comprehensive investigation provides important insights into the relationship and spatial distribution of different pathways of cholesterol input, output and regulation in the NR-RPE region. The data obtained are important for deciphering the putative link between cholesterol and age-related macular degeneration, a major cause of irreversible vision loss in the elderly.
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Affiliation(s)
- Wenchao Zheng
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Rachel E. Reem
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Saida Omarova
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Suber Huang
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
- University Hospitals, Cleveland, Ohio, United States of America
| | - Pier Luigi DiPatre
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Casey D. Charvet
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Christine A. Curcio
- Department of Ophthalmology, University of Alabama, Birmingham, Alabama, United States of America
| | - Irina A. Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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