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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. FASEB J 2024; 38:e23522. [PMID: 38445789 PMCID: PMC10949407 DOI: 10.1096/fj.202302491r] [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: 12/02/2023] [Revised: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 03/07/2024]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (APOB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic depletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor-associated cholesterol deposits, and photoreceptor cell death, and loss of rod but not cone function. RPE-specific reduction in Mttp had no significant effect on plasma lipids and lipoproteins. While APOB was decreased in the RPE, most ocular retinoids remained unchanged, with the exception of the storage form of retinoid, retinyl ester. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but is not directly involved in plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570418. [PMID: 38105975 PMCID: PMC10723417 DOI: 10.1101/2023.12.06.570418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or to age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (apoB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic deletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor -associated cholesterol deposits and photoreceptor cell death, and loss of rod but not cone function. RPE-specific ablation of Mttp had no significant effect on plasma lipids and lipoproteins. While, apoB was decreased in the RPE, ocular retinoid concentrations remained unchanged. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but not directly involved in ocular retinoid and plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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Rios ACH, Nasner SLC, Londoño-Gil M, Gonzalez-Herrera LG, Lopez-Herrera A, Flórez JCR. Genome-wide association study for reproduction traits in Colombian Creole Blanco Orejinegro cattle. Trop Anim Health Prod 2023; 55:429. [PMID: 38044379 DOI: 10.1007/s11250-023-03847-2] [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: 06/20/2023] [Accepted: 11/27/2023] [Indexed: 12/05/2023]
Abstract
The profitability of the beef cattle production system relies heavily on reproductive traits. Unfortunately, certain traits, such as age at first calving (AFC), calving interval (CI), and gestation length (GL), can pose challenges in traditional breeding programs because of their low heritability (0.01-0.12) and sex-limited characteristics. Another important aspect is the conservation of the genetic resources of animals adapted to the Colombian regions, which implies the preservation and rational use of the creole breeds in the country market. Therefore, this study aimed to identify genomic regions in the creole cattle breed Blanco Orejinegro (BON) that influence the reproductive traits in females. The dataset comprised 439 animals and 118,116 single-nucleotide polymorphisms' (SNPs) markers. The GS3 program was used to identify the SNP effects employing the BAYES Cπ methodology. The number of SNPs with effect for AFC was 25, 1527 for CI, and 23 for GL. Some of the genes found associated with reproductive and growth traits as well as immune response and environmental adaptation ECE1, EPH, EPHB2, SMARCAL1, IGFBP5, IGFBP2, FCGRT, EGFR, MUL1, PINK1, STPG1, CNGB1, TGFB1, OXTR, IL22RA1, MYOM3, OXTR, CNR2, HIVEP3, CTPS1, CXCL8, FCGRT, MREG, TMEM169, PECR, and MC1R. Our results evidenced a high contribution of the genetic architecture of the Colombian creole cattle breed Blanco Orejinegro that may impact should be included in implementing genetic improvement and conservation programs.
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Affiliation(s)
- Ana Cristina Herrera Rios
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Medellín, Carrera 65 N 59A-110, 050034, Medellín, Colombia.
- Grupo de Investigación Nutri-Solla, SOLLA S.A., Cra 42 #33-80, Itagüí, Antioquia, Colombia.
| | - Sindy Liliana Caivio Nasner
- Grupo de Investigación Biomolecular y Pecuaria BIOPEC, Universidad Tecnológica de Pereira, Cra. 27 N10-02, 660003, Pereira, Risaralda, Colombia
| | - Marisol Londoño-Gil
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Medellín, Carrera 65 N 59A-110, 050034, Medellín, Colombia
| | - Luis Gabriel Gonzalez-Herrera
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Medellín, Carrera 65 N 59A-110, 050034, Medellín, Colombia
| | - Albeiro Lopez-Herrera
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Medellín, Carrera 65 N 59A-110, 050034, Medellín, Colombia
| | - Juan Carlos Rincón Flórez
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Medellín, Carrera 65 N 59A-110, 050034, Medellín, Colombia
- Grupo de Investigación Biodiversidad y Genética Molecular (BIOGEM), Universidad Nacional de Colombia Sede Palmira, Carrera 32 N 12 - 00, PC 763352, Palmira, Colombia
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Krivoruchko A, Likhovid A, Kanibolotskaya A, Saprikina T, Safaryan E, Yatsyk O. Genome-Wide Search for Associations with Meat Production Parameters in Karachaevsky Sheep Breed Using the Illumina BeadChip 600 K. Genes (Basel) 2023; 14:1288. [PMID: 37372468 DOI: 10.3390/genes14061288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/16/2023] [Accepted: 06/17/2023] [Indexed: 06/29/2023] Open
Abstract
In a group of Karachaevsky rams, a genome-wide associations analysis of single nucleotide polymorphisms (SNPs) with live parameters of meat production was performed. We used for genotyping the Ovine Infinium HD BeadChip 600 K, which consists of points to detection of 606,000 polymorphisms. A total of 12 SNPs was found to be significantly associated with live meat quality parameters of the corpus and legs and ultrasonic traits. In this case, 11 candidate genes were described, the polymorphic variants of which can change in sheep body parameters. We found SNPs in the exons, introns, and other regions of some genes and transcripts: CLVS1, EVC2, KIF13B, ENSOART00000000511.1, KCNH5, NEDD4, LUZP2, MREG, KRT20, KRT23 and FZD6. The described genes involved in the metabolic pathways of cell differentiation, proliferation and apoptosis are connected with the regulation of the gastrointestinal, immune and nervous systems. In known productivity genes (MSTN, MEF2B, FABP4, etc.), loci were not found to be a significant presence of influence on the meat productivity of the Karachaevsky sheep phenotypes. Our study confirms the possible involvement of the identified candidate genes in the formation of the phenotypes of productivity traits in sheep and indicates the need for new research into candidate genes structure in point to detect their polymorphisms.
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Affiliation(s)
- Alexander Krivoruchko
- Federal Seфey Budgetary Scientific Institution, North Caucasian Federal Scientific Agrarian Centre, 356241 Mikhailovsk, Russia
- Department of Genetic and Selection, FSAEIHE, North-Caucasus Federal University, 355017 Stavropol, Russia
| | - Andrey Likhovid
- Department of Genetic and Selection, FSAEIHE, North-Caucasus Federal University, 355017 Stavropol, Russia
| | - Anastasiya Kanibolotskaya
- Federal Seфey Budgetary Scientific Institution, North Caucasian Federal Scientific Agrarian Centre, 356241 Mikhailovsk, Russia
| | - Tatiana Saprikina
- Federal Seфey Budgetary Scientific Institution, North Caucasian Federal Scientific Agrarian Centre, 356241 Mikhailovsk, Russia
| | - Elena Safaryan
- Federal Seфey Budgetary Scientific Institution, North Caucasian Federal Scientific Agrarian Centre, 356241 Mikhailovsk, Russia
| | - Olesya Yatsyk
- Federal Seфey Budgetary Scientific Institution, North Caucasian Federal Scientific Agrarian Centre, 356241 Mikhailovsk, Russia
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Moreira LR, Smith BT. Convergent genomic signatures of local adaptation across a continental-scale environmental gradient. SCIENCE ADVANCES 2023; 9:eadd0560. [PMID: 37205757 PMCID: PMC10198635 DOI: 10.1126/sciadv.add0560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 04/17/2023] [Indexed: 05/21/2023]
Abstract
Convergent local adaptation offers a glimpse into the role of constraint and stochasticity in adaptive evolution, in particular the extent to which similar genetic mechanisms drive adaptation to common selective forces. Here, we investigated the genomics of local adaptation in two nonsister woodpeckers that are codistributed across an entire continent and exhibit remarkably convergent patterns of geographic variation. We sequenced the genomes of 140 individuals of Downy (Dryobates pubescens) and Hairy (Dryobates villosus) woodpeckers and used a suite of genomic approaches to identify loci under selection. We showed evidence that convergent genes have been targeted by selection in response to shared environmental pressures, such as temperature and precipitation. Among candidates, we found multiple genes putatively linked to key phenotypic adaptations to climate, including differences in body size (e.g., IGFPB) and plumage (e.g., MREG). These results are consistent with genetic constraints limiting the pathways of adaptation to broad climatic gradients, even after genetic backgrounds diverge.
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Affiliation(s)
- Lucas R. Moreira
- Department of Ecology, Evolution and Environmental Biology, Columbia University, NY, USA
- Department of Ornithology, American Museum of Natural History, New York City, NY, USA
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Brian Tilston Smith
- Department of Ornithology, American Museum of Natural History, New York City, NY, USA
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6
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Cui X, Kim HJ, Cheng CH, Jenny LA, Lima de Carvalho JR, Chang YJ, Kong Y, Hsu CW, Huang IW, Ragi SD, Lin CS, Li X, Sparrow JR, Tsang SH. Long-term vitamin A supplementation in a preclinical mouse model for RhoD190N-associated retinitis pigmentosa. Hum Mol Genet 2022; 31:2438-2451. [PMID: 35195241 PMCID: PMC9307315 DOI: 10.1093/hmg/ddac032] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/10/2022] [Accepted: 01/25/2022] [Indexed: 01/12/2023] Open
Abstract
Retinitis pigmentosa (RP) is caused by one of many possible gene mutations. The National Institutes of Health recommends high daily doses of vitamin A palmitate for RP patients. There is a critical knowledge gap surrounding the therapeutic applicability of vitamin A to patients with the different subtypes of the disease. Here, we present a case report of a patient with RP caused by a p.D190N mutation in Rhodopsin (RHO) associated with abnormally high quantitative autofluorescence values after long-term vitamin A supplementation. We investigated the effects of vitamin A treatment strategy on RP caused by the p.D190N mutation in RHO by exposing Rhodopsin p.D190N (RhoD190N/+) and wild-type (WT) mice to experimental vitamin A-supplemented and standard control diets. The patient's case suggests that the vitamin A treatment strategy should be further studied to determine its effect on RP caused by p.D190N mutation in RHO and other mutations. Our mouse experiments revealed that RhoD190N/+ mice on the vitamin A diet exhibited higher levels of autofluorescence and lipofuscin metabolites compared to WT mice on the same diet and isogenic controls on the standard control diet. Vitamin A supplementation diminished photoreceptor function in RhoD190N/+ mice while preserving cone response in WT mice. Our findings highlight the importance of more investigations into the efficacy of clinical treatments like vitamin A for patients with certain genetic subtypes of disease and of genotyping in the precision care of inherited retinal degenerations.
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Affiliation(s)
- Xuan Cui
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
- School of Optometry and Ophthalmology, Tianjin Medical University Eye Institute, Tianjin Medical University Eye Hospital, Tianjin Medical University, Tianjin 300384, China
- Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA
| | - Hye Jin Kim
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Chia-Hua Cheng
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Laura A Jenny
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Jose Ronaldo Lima de Carvalho
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Ya-Ju Chang
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Yang Kong
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Chun-Wei Hsu
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - I-Wen Huang
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Sara D Ragi
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
| | - Chyuan-Sheng Lin
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Xiaorong Li
- School of Optometry and Ophthalmology, Tianjin Medical University Eye Institute, Tianjin Medical University Eye Hospital, Tianjin Medical University, Tianjin 300384, China
| | - Janet R Sparrow
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
- Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Stephen H Tsang
- Jonas Children’s Vision Care, and the Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY 10032, USA
- Department of Ophthalmology, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA
- Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
- Institute of Human Nutrition, Columbia University, New York, NY 10032, USA
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Hazim RA, Williams DS. Microtubule Motor Transport of Organelles in a Specialized Epithelium: The RPE. Front Cell Dev Biol 2022; 10:852468. [PMID: 35309899 PMCID: PMC8930850 DOI: 10.3389/fcell.2022.852468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a uniquely polarized epithelium that lies adjacent to the photoreceptor cells in the retina, and is essential for photoreceptor function and viability. Two major motile organelles present in the RPE are the melanosomes, which are important for absorbing stray light, and phagosomes that result from the phagocytosis of the distal tips of the photoreceptor cilium, known as the photoreceptor outer segment (POS). These organelles are transported along microtubules, aligned with the apical-basal axis of the RPE. Although they undergo a directional migration, the organelles exhibit bidirectional movements, indicating both kinesin and dynein motor function in their transport. Apical melanosome localization requires dynein; it has been suggested that kinesin contribution might be complex with the involvement of more than one type of kinesin. POS phagosomes undergo bidirectional movements; roles of both plus- and minus-end directed motors appear to be important in the efficient degradation of phagosomes. This function is directly related to retinal health, with defects in motor proteins, or in the association of the phagosomes with the motors, resulting in retinal degenerative pathologies.
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Affiliation(s)
- Roni A. Hazim
- Department of Ophthalmology and Stein Eye Institute, Los Angeles, CA, United States
| | - David S. Williams
- Department of Ophthalmology and Stein Eye Institute, Los Angeles, CA, United States
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States
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8
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Li A, Wu N, Sun J. E2F1-induced microRNA-224-5p expression is associated with hepatocellular carcinoma cell migration, invasion and epithelial-mesenchymal transition via MREG. Oncol Lett 2022; 23:82. [PMID: 35126724 PMCID: PMC8805181 DOI: 10.3892/ol.2022.13202] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 12/08/2021] [Indexed: 11/05/2022] Open
Abstract
MicroRNA (miR)-224-5p has been reported to be associated with multiple types of cancer. However, its biological role and underlying mechanism in hepatocellular carcinoma (HCC) has yet to be fully elucidated. The aim of the present study was to investigate whether miR-224-5p mRNA expression level was increased in hepatocellular carcinoma and whether it was associated with poor prognosis. Decreased mRNA expression level of miR-224-5p was shown to suppress liver cancer cell migration, invasion and epithelial-mesenchymal transition (EMT). Mechanistically, E2F1 was found to regulate miR-224-5p expression by binding to its promoter region. Melanoregulin (MREG) was identified as the direct target of miR-224-5p by searching the TargetScan, miRDB and StarBase databases. Overexpression of MREG could attenuate liver cancer cell migration, invasion and EMT. Rescue experiments further confirmed that MREG was associated with the regulation of miR-224-5p in liver cancer. In addition, the E2F1/miR-224-5p axis was shown to promote liver cancer cell migration, invasion and EMT by regulating MREG expression. These results suggested that E2F1-induced upregulation of miR-224-5p may serve an important role in MREG-induced liver cancer cell migration, invasion and EMT, and highlights the regulatory function of miR-224-5p in liver cancer. Therefore, the E2F1/miR-224-5p/MREG axis may provide a theoretical basis for the clinical treatment of hepatocellular carcinoma.
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Affiliation(s)
- An Li
- Department of Radiotherapy, Shanxi Yuncheng Central Hospital, Yuncheng, Shanxi 044000, P.R. China
| | - Ning Wu
- Department of Oncology, Shanghai Pudong New Area Gongli Hospital, Shanghai 200135, P.R. China
| | - Jingyu Sun
- Department of Cardiology, Shanxi Yuncheng Central Hospital, Yuncheng, Shanxi 044000, P.R. China
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9
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Peña-Oyarzún D, San Martin C, Hernández-Cáceres MP, Lavandero S, Morselli E, Budini M, Burgos PV, Criollo A. Autophagy in aging-related oral diseases. Front Endocrinol (Lausanne) 2022; 13:903836. [PMID: 35992149 PMCID: PMC9390882 DOI: 10.3389/fendo.2022.903836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/13/2022] [Indexed: 11/17/2022] Open
Abstract
Autophagy is an intracellular degradation mechanism that allows recycling of organelles and macromolecules. Autophagic function increases metabolite availability modulating metabolic pathways, differentiation and cell survival. The oral environment is composed of several structures, including mineralized and soft tissues, which are formed by complex interactions between epithelial and mesenchymal cells. With aging, increased prevalence of oral diseases such as periodontitis, oral cancer and periapical lesions are observed in humans. These aging-related oral diseases are chronic conditions that alter the epithelial-mesenchymal homeostasis, disrupting the oral tissue architecture affecting the quality of life of the patients. Given that autophagy levels are reduced with age, the purpose of this review is to discuss the link between autophagy and age-related oral diseases.
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Affiliation(s)
- Daniel Peña-Oyarzún
- Physiology Department, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Interdisciplinary Center for Research in Territorial Health of the Aconcagua Valley (CIISTe Aconcagua), School of Medicine, Faculty of Medicine, San Felipe Campus, Universidad de Valparaíso, San Felipe, Chile
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
| | - Carla San Martin
- Interdisciplinary Center for Research in Territorial Health of the Aconcagua Valley (CIISTe Aconcagua), School of Medicine, Faculty of Medicine, San Felipe Campus, Universidad de Valparaíso, San Felipe, Chile
| | - María Paz Hernández-Cáceres
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- Cardiology Division, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Eugenia Morselli
- Department of Basic Sciences, Faculty of Medicine and Sciences, Universidad San Sebastián, Santiago de Chile, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
| | - Mauricio Budini
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
| | - Patricia V. Burgos
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
- Centro de Envejecimiento y Regeneración (CARE-UC), Facultad de Ciencias Biológicas, Pontificia Universidad Católica, Santiago, Chile
- Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Alfredo Criollo
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
- *Correspondence: Alfredo Criollo,
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10
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Butler JM, Supharattanasitthi W, Yang YC, Paraoan L. RNA-seq analysis of ageing human retinal pigment epithelium: Unexpected up-regulation of visual cycle gene transcription. J Cell Mol Med 2021; 25:5572-5585. [PMID: 33934486 PMCID: PMC8184696 DOI: 10.1111/jcmm.16569] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 02/06/2023] Open
Abstract
Ageing presents adverse effects on the retina and is the primary risk factor for age‐related macular degeneration (AMD). We report the first RNA‐seq analysis of age‐related transcriptional changes in the human retinal pigment epithelium (RPE), the primary site of AMD pathogenesis. Whole transcriptome sequencing of RPE from human donors ranging in age from 31 to 93 reveals that ageing is associated with increasing transcription of main RPE‐associated visual cycle genes (including LRAT, RPE65, RDH5, RDH10, RDH11; pathway enrichment BH‐adjusted P = 4.6 × 10−6). This positive correlation is replicated in an independent set of 28 donors and a microarray dataset of 50 donors previously published. LRAT expression is positively regulated by retinoid by‐products of the visual cycle (A2E and all‐trans‐retinal) involving modulation by retinoic acid receptor alpha transcription factor. The results substantiate a novel age‐related positive feedback mechanism between accumulation of retinoid by‐products in the RPE and the up‐regulation of visual cycle genes.
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Affiliation(s)
- Joe M Butler
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Wasu Supharattanasitthi
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Yit C Yang
- Department of Ophthalmology, Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, UK
| | - Luminita Paraoan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
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11
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A Re-Appraisal of Pathogenic Mechanisms Bridging Wet and Dry Age-Related Macular Degeneration Leads to Reconsider a Role for Phytochemicals. Int J Mol Sci 2020; 21:ijms21155563. [PMID: 32756487 PMCID: PMC7432893 DOI: 10.3390/ijms21155563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 07/31/2020] [Accepted: 08/01/2020] [Indexed: 12/14/2022] Open
Abstract
Which pathogenic mechanisms underlie age-related macular degeneration (AMD)? Are they different for dry and wet variants, or do they stem from common metabolic alterations? Where shall we look for altered metabolism? Is it the inner choroid, or is it rather the choroid–retinal border? Again, since cell-clearing pathways are crucial to degrade altered proteins, which metabolic system is likely to be the most implicated, and in which cell type? Here we describe the unique clearing activity of the retinal pigment epithelium (RPE) and the relevant role of its autophagy machinery in removing altered debris, thus centering the RPE in the pathogenesis of AMD. The cell-clearing systems within the RPE may act as a kernel to regulate the redox homeostasis and the traffic of multiple proteins and organelles toward either the choroid border or the outer segments of photoreceptors. This is expected to cope with the polarity of various domains within RPE cells, with each one owning a specific metabolic activity. A defective clearance machinery may trigger unconventional solutions to avoid intracellular substrates’ accumulation through unconventional secretions. These components may be deposited between the RPE and Bruch’s membrane, thus generating the drusen, which remains the classic hallmark of AMD. These deposits may rather represent a witness of an abnormal RPE metabolism than a real pathogenic component. The empowerment of cell clearance, antioxidant, anti-inflammatory, and anti-angiogenic activity of the RPE by specific phytochemicals is here discussed.
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12
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Domingo-Gonzalez R, Zanini F, Che X, Liu M, Jones RC, Swift MA, Quake SR, Cornfield DN, Alvira CM. Diverse homeostatic and immunomodulatory roles of immune cells in the developing mouse lung at single cell resolution. eLife 2020; 9:e56890. [PMID: 32484158 PMCID: PMC7358008 DOI: 10.7554/elife.56890] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/13/2020] [Indexed: 12/20/2022] Open
Abstract
At birth, the lungs rapidly transition from a pathogen-free, hypoxic environment to a pathogen-rich, rhythmically distended air-liquid interface. Although many studies have focused on the adult lung, the perinatal lung remains unexplored. Here, we present an atlas of the murine lung immune compartment during early postnatal development. We show that the late embryonic lung is dominated by specialized proliferative macrophages with a surprising physical interaction with the developing vasculature. These macrophages disappear after birth and are replaced by a dynamic mixture of macrophage subtypes, dendritic cells, granulocytes, and lymphocytes. Detailed characterization of macrophage diversity revealed an orchestration of distinct subpopulations across postnatal development to fill context-specific functions in tissue remodeling, angiogenesis, and immunity. These data both broaden the putative roles for immune cells in the developing lung and provide a framework for understanding how external insults alter immune cell phenotype during a period of rapid lung growth and heightened vulnerability.
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Affiliation(s)
- Racquel Domingo-Gonzalez
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
- Center for Excellence in Pulmonary Biology, Stanford University School of MedicineStanfordUnited States
| | - Fabio Zanini
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Prince of Wales Clinical School, Lowy Cancer Research Centre, University of New South WalesSydneyAustralia
| | - Xibing Che
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
- Center for Excellence in Pulmonary Biology, Stanford University School of MedicineStanfordUnited States
- Division of Pulmonary, Asthma and Sleep Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
| | - Min Liu
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
- Center for Excellence in Pulmonary Biology, Stanford University School of MedicineStanfordUnited States
| | - Robert C Jones
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | - Michael A Swift
- Department of Chemical and Systems Biology, Stanford UniversityStanfordUnited States
| | - Stephen R Quake
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Chan Zuckerberg BiohubSan FranciscoUnited States
- Department of Applied Physics, Stanford UniversityStanfordUnited States
| | - David N Cornfield
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
- Center for Excellence in Pulmonary Biology, Stanford University School of MedicineStanfordUnited States
- Division of Pulmonary, Asthma and Sleep Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
| | - Cristina M Alvira
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of MedicineStanfordUnited States
- Center for Excellence in Pulmonary Biology, Stanford University School of MedicineStanfordUnited States
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13
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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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14
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Milenkovic A, Schmied D, Tanimoto N, Seeliger MW, Sparrow JR, Weber BHF. The Y227N mutation affects bestrophin-1 protein stability and impairs sperm function in a mouse model of Best vitelliform macular dystrophy. Biol Open 2019; 8:bio.041335. [PMID: 31201163 PMCID: PMC6679414 DOI: 10.1242/bio.041335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Human bestrophin-1 (BEST1) is an integral membrane protein known to function as a Ca2+-activated and volume-regulated chloride channel. The majority of disease-associated mutations in BEST1 constitute missense mutations and were shown in vitro to lead to a reduction in mutant protein half-life causing Best disease (BD), a rare autosomal dominant macular dystrophy. To further delineate BEST1-associated pathology in vivo and to provide an animal model useful to explore experimental treatment efficacies, we have generated a knock-in mouse line (Best1Y227N). Heterozygous and homozygous mutants revealed no significant ocular abnormalities up to 2 years of age. In contrast, knock-in animals demonstrated a severe phenotype in the male reproductive tract. In heterozygous Best1Y227N males, Best1 protein was significantly reduced in testis and almost absent in homozygous mutant mice, although mRNA transcription of wild-type and knock-in allele is present and similar in quantity. Degradation of mutant Best1 protein in testis was associated with adverse effects on sperm motility and the capability to fertilize eggs. Based on these results, we conclude that mice carrying the Best1 Y227N mutation reveal a reproducible pathologic phenotype and thus provide a valuable in vivo tool to evaluate efficacy of drug therapies aimed at restoring Best1 protein stability and function.
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Affiliation(s)
- Andrea Milenkovic
- Institute of Human Genetics, University of Regensburg, 93053 Regensburg, Germany
| | - Denise Schmied
- Institute of Human Genetics, University of Regensburg, 93053 Regensburg, Germany
| | - Naoyuki Tanimoto
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, 72076 Tübingen, Germany.,Department of Ophthalmology, University of Kiel, 24105 Kiel, Germany
| | - Mathias W Seeliger
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, 72076 Tübingen, Germany
| | - Janet R Sparrow
- Department of Ophthalmology, Harkness Eye Institute, Columbia University Medical Center, 10032 New York, USA
| | - Bernhard H F Weber
- Institute of Human Genetics, University of Regensburg, 93053 Regensburg, Germany
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15
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The Late Endosomal Pathway Regulates the Ciliary Targeting of Tetraspanin Protein Peripherin 2. J Neurosci 2019; 39:3376-3393. [PMID: 30819798 PMCID: PMC6495125 DOI: 10.1523/jneurosci.2811-18.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/18/2019] [Accepted: 02/10/2019] [Indexed: 12/11/2022] Open
Abstract
Peripherin 2 (PRPH2) is a tetraspanin protein concentrated in the light-sensing cilium (called the outer segment) of the vertebrate photoreceptor. The mechanism underlying the ciliary targeting of PRPH2 and the etiology of cone dystrophy caused by PRPH2 mutations remain elusive. Here we show that the late endosome (LE) is the main waystation that critically sorts newly synthesized PRPH2 to the cilium. PRPH2 is expressed in the luminal membrane of the LE. We delineate multiple C-terminal motifs of PRPH2 that distinctively regulate its LE and ciliary targeting through ubiquitination and binding to ESCRT (Endosomal Sorting Complexes Required for Transport) component Hrs. Using the newly developed TetOn-inducible system in transfected male and female mouse cones in vivo, we show that the entry of nascent PRPH2 into the cone outer segment can be blocked by either cone dystrophy-causing C-terminal mutations of PRPH2, or by short-term perturbation of the LE or recycling endosomal traffic. These findings open new avenues of research to explore the biological role of the LE in the biosynthetic pathway and the etiology of cone dystrophy caused by PRPH2 mutations and/or malfunctions of the LE.SIGNIFICANCE STATEMENT Peripherin 2 (PRPH2) is a tetraspanin protein abundantly expressed in the light-sensing cilium, the outer segment, of the vertebrate photoreceptor. The mechanism underlying the ciliary transport of PRPH2 is unclear. The present study reveals a novel ciliary targeting pathway, in which the newly synthesized PRPH2 is first targeted to the lumen of the late endosome (LE) en route to the cilia. We deciphered the protein motifs and the machinery that regulates the LE trafficking of PRPH2. Using a novel TetOn-inducible system in transfected mouse cones, we showed that the LE pathway of PRPH2 is critical for its outer segment expression. A cone dystrophy-causing mutation impairs the LE and ciliary targeting of PRPH2, implicating the relevance of LE to cone/macular degenerative diseases.
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16
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Dhingra A, Bell BA, Peachey NS, Daniele LL, Reyes-Reveles J, Sharp RC, Jun B, Bazan NG, Sparrow JR, Kim HJ, Philp NJ, Boesze-Battaglia K. Microtubule-Associated Protein 1 Light Chain 3B, (LC3B) Is Necessary to Maintain Lipid-Mediated Homeostasis in the Retinal Pigment Epithelium. Front Cell Neurosci 2018; 12:351. [PMID: 30349463 PMCID: PMC6186781 DOI: 10.3389/fncel.2018.00351] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/19/2018] [Indexed: 12/25/2022] Open
Abstract
Like other neurons, retinal cells utilize autophagic pathways to maintain cell homeostasis. The mammalian retina relies on heterophagy and selective autophagy to efficiently degrade and metabolize ingested lipids with disruption in autophagy associated degradation contributing to age related retinal disorders. The retinal pigment epithelium (RPE) supports photoreceptor cell renewal by daily phagocytosis of shed photoreceptor outer segments (OS). The daily ingestion of these lipid-rich OS imposes a constant degradative burden on these terminally differentiated cells. These cells rely on Microtubule-Associated Protein 1 Light Chain 3 (LC3) family of proteins for phagocytic clearance of the ingested OS. The LC3 family comprises of three highly homologous members, MAP1LC3A (LC3A), MAP1LC3B (LC3B), and MAP1LC3C (LC3C). The purpose of this study was to determine whether the LC3B isoform plays a specific role in maintaining RPE lipid homeostasis. We examined the RPE and retina of the LC3B-/- mouse as a function of age using in vivo ocular imaging and electroretinography coupled with ex vivo, lipidomic analyses of lipid mediators, assessment of bisretinoids as well as imaging of lipid aggregates. Deletion of LC3B resulted in defects within the RPE including increased phagosome accumulation, decreased fatty acid oxidation and a subsequent increase in RPE and sub-RPE lipid deposits. Age-dependent RPE changes included elevated levels of oxidized cholesterol, deposition of 4-HNE lipid peroxidation products, bisretinoid lipofuscin accumulation, and subretinal migration of microglia, collectively likely contributing to loss of retinal function. These observations are consistent with a critical role for LC3B-dependent processes in the maintenance of normal lipid homeostasis in the aging RPE, and suggest that LC3 isoform specific disruption in autophagic processes contribute to AMD-like pathogenesis.
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Affiliation(s)
- Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Brent A Bell
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Neal S Peachey
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Lauren L Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Juan Reyes-Reveles
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Rachel C Sharp
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, United States
| | - Hye Jin Kim
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, United States
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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17
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Campbell LJ, West MC, Jensen AM. A high content, small molecule screen identifies candidate molecular pathways that regulate rod photoreceptor outer segment renewal. Sci Rep 2018; 8:14017. [PMID: 30228302 PMCID: PMC6143611 DOI: 10.1038/s41598-018-32336-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 09/05/2018] [Indexed: 01/04/2023] Open
Abstract
The outer segment of the vertebrate rod photoreceptor is a highly modified cilium composed of many discrete membranous discs that are filled with the protein machinery necessary for phototransduction. The unique outer segment structure is renewed daily with growth at the base of the outer segment where new discs are formed and shedding at the distal end where old discs are phagocytized by the retinal pigment epithelium. In order to understand how outer segment renewal is regulated to maintain outer segment length and function, we used a small molecule screening approach with the transgenic (hsp70:HA-mCherryTM) zebrafish, which expresses a genetically-encoded marker of outer segment renewal. We identified compounds with known bioactivity that affect five content areas: outer segment growth, outer segment shedding, clearance of shed outer segment tips, Rhodopsin mislocalization, and differentiation at the ciliary marginal zone. Signaling pathways that are targeted by the identified compounds include cyclooxygenase in outer segment growth, γ-Secretase in outer segment shedding, and mTor in RPE phagocytosis. The data generated by this screen provides a foundation for further investigation of the signaling pathways that regulate photoreceptor outer segment renewal.
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Affiliation(s)
- Leah J Campbell
- Biology Department, University of Massachusetts, Amherst, MA, 01003, USA.,Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Megan C West
- Biology Department, University of Massachusetts, Amherst, MA, 01003, USA
| | - Abbie M Jensen
- Biology Department, University of Massachusetts, Amherst, MA, 01003, USA. .,Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, 01003, USA.
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18
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Rout AK, Wu X, Starich MR, Strub MP, Hammer JA, Tjandra N. The Structure of Melanoregulin Reveals a Role for Cholesterol Recognition in the Protein's Ability to Promote Dynein Function. Structure 2018; 26:1373-1383.e4. [PMID: 30174147 DOI: 10.1016/j.str.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 06/12/2018] [Accepted: 07/24/2018] [Indexed: 01/24/2023]
Abstract
Melanoregulin (Mreg) is a small, highly charged, multiply palmitoylated protein present on the membrane of melanosomes. Mreg is implicated in the transfer of melanosomes from melanocytes to keratinocytes, and in promoting the microtubule minus end-directed transport of these organelles. The possible molecular function of Mreg was identified by solving its structure using nuclear magnetic resonance (NMR) spectroscopy. Mreg contains six α helices forming a fishhook-like fold in which positive and negative charges occupy opposite sides of the protein's surface and sandwich a putative, cholesterol recognition sequence (CRAC motif). Mreg containing a point mutation within its CRAC motif still targets to late endosomes/lysosomes, but no longer promotes their microtubule minus end-directed transport. Moreover, wild-type Mreg does not promote the microtubule minus end-directed transport of late endosomes/lysosomes in cells transiently depleted of cholesterol. Finally, reversing the charge of three clustered acidic residues partially inhibits Mreg's ability to drive these organelles to microtubule minus ends.
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Affiliation(s)
- Ashok K Rout
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xufeng Wu
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary R Starich
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Marie-Paule Strub
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - John A Hammer
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Nico Tjandra
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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Meng X, Dong Y, Yu X, Wang D, Wang S, Chen S, Pang S. MREG suppresses thyroid cancer cell invasion and proliferation by inhibiting Akt-mTOR signaling. Biochem Biophys Res Commun 2017; 491:72-78. [DOI: 10.1016/j.bbrc.2017.07.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/08/2017] [Indexed: 10/19/2022]
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20
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Reyes-Reveles J, Dhingra A, Alexander D, Bragin A, Philp NJ, Boesze-Battaglia K. Phagocytosis-dependent ketogenesis in retinal pigment epithelium. J Biol Chem 2017; 292:8038-8047. [PMID: 28302729 DOI: 10.1074/jbc.m116.770784] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/13/2017] [Indexed: 11/06/2022] Open
Abstract
Daily, the retinal pigment epithelium (RPE) ingests a bolus of lipid and protein in the form of phagocytized photoreceptor outer segments (OS). The RPE, like the liver, expresses enzymes required for fatty acid oxidation and ketogenesis. This suggests that these pathways play a role in the disposal of lipids from ingested OS, as well as providing a mechanism for recycling metabolic intermediates back to the outer retina. In this study, we examined whether OS phagocytosis was linked to ketogenesis. We found increased levels of β-hydroxybutyrate (β-HB) in the apical medium following ingestion of OS by human fetal RPE and ARPE19 cells cultured on Transwell inserts. No increase in ketogenesis was observed following ingestion of oxidized OS or latex beads. Our studies further defined the connection between OS phagocytosis and ketogenesis in wild-type mice and mice with defects in phagosome maturation using a mouse RPE explant model. In explant studies, the levels of β-HB released were temporally correlated with OS phagocytic burst after light onset. In the Mreg-/- mouse where phagosome maturation is delayed, there was a temporal shift in the release of β-HB. An even more pronounced shift in maximal β-HB production was observed in the Abca4-/- RPE, in which loss of the ATP-binding cassette A4 transporter results in defective phagosome processing and accumulation of lipid debris. These studies suggest that FAO and ketogenesis are key to supporting the metabolism of the RPE and preventing the accumulation of lipids that lead to oxidative stress and mitochondrial dysfunction.
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Affiliation(s)
- Juan Reyes-Reveles
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Anuradha Dhingra
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Desiree Alexander
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Alvina Bragin
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Nancy J Philp
- the Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19146
| | - Kathleen Boesze-Battaglia
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
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21
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Kim BK, Kim I, Lee AR, Yoo HI, Yoon SK. Mouse-specific up-regulation of Ccnb1 expression by miR-199a-5p in keratinocyte. FEBS Open Bio 2016; 6:1131-1140. [PMID: 27833853 PMCID: PMC5095150 DOI: 10.1002/2211-5463.12133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/10/2016] [Accepted: 09/04/2016] [Indexed: 01/07/2023] Open
Abstract
MicroRNA (miRNA) are a class of single-stranded, small non-coding RNA that regulate various biological processes, including skin and hair cycle regulation, by modulating the expression of specific genes at the post-transcriptional level. Recently, several studies reported that miRNA directly or indirectly up-regulate target genes. Previously, we performed microarray analysis to identify the target genes of miR-199a-5p in a mouse skin keratinocyte cell line and detected more than 200 genes whose expression was significantly increased by miR-199a-5p overexpression (> 1.5-fold). In this study, we further investigated these genes and found that cyclin B1 (Ccnb1) expression was positively regulated by miR-199a-5p in keratinocyte. Moreover, Ccnb1 expression was inversely correlated with miR-199a-5p expression during the mouse hair cycle. Cell cycle analysis showed that the proportion of cells in S phase was slightly increased, while the proportion of cells in G2/M phase decreased by miR-199-5p. Using luciferase assay, we found that the 3' untranslated region of Ccnb1 was a direct target of miR-199a-5p. We also found that the regulation of Ccnb1 expression by miR-199a-5p is mouse specific. CCNB1 expression was not affected in the human and monkey cell lines. These results provide a new relationship between Ccnb1 and miR-199a-5p in both mouse keratinocyte and miRNA biology.
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Affiliation(s)
- Bong-Kyu Kim
- Department of Medical Lifesciences The Catholic University of Korea Seoul Korea
| | - Injung Kim
- Department of Medical Lifesciences The Catholic University of Korea Seoul Korea
| | - Ah-Reum Lee
- Department of Medical Lifesciences The Catholic University of Korea Seoul Korea
| | - Hye-In Yoo
- Department of Medical Lifesciences The Catholic University of Korea Seoul Korea
| | - Sungjoo Kim Yoon
- Department of Medical Lifesciences The Catholic University of Korea Seoul Korea
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22
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Sethna S, Chamakkala T, Gu X, Thompson TC, Cao G, Elliott MH, Finnemann SC. Regulation of Phagolysosomal Digestion by Caveolin-1 of the Retinal Pigment Epithelium Is Essential for Vision. J Biol Chem 2016; 291:6494-506. [PMID: 26814131 DOI: 10.1074/jbc.m115.687004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 01/09/2023] Open
Abstract
Caveolin-1 associates with the endo/lysosomal machinery of cells in culture, suggesting that it functions at these organelles independently of its contribution to cell surface caveolae. Here we explored mice lacking caveolin-1 specifically in the retinal pigment epithelium (RPE). The RPE supports neighboring photoreceptors via diurnal phagocytosis of spent photoreceptor outer segment fragments. Like mice lacking caveolin-1 globally, (RPE)CAV1(-/-) mice developed a normal RPE and neural retina but showed reduced rod photoreceptor light responses, indicating that lack of caveolin-1 affects photoreceptor function in a non-cell-autonomous manner. (RPE)CAV1(-/-) RPE in situ showed normal particle engulfment but delayed phagosome clearance and reversed diurnal profiles of levels and activities of lysosomal enzymes. Therefore, eliminating caveolin-1 specifically impairs phagolysosomal degradation by the RPE in vivo. Endogenous caveolin-1 was recruited to maturing phagolysosomes in RPE cells in culture. Consistent with these in vivo data, a moderate increase (to ∼ 2.5-fold) or decrease (by half) of caveolin-1 protein levels in RPE cells in culture was sufficient to accelerate or impair phagolysosomal digestion, respectively. A mutant form of caveolin-1 that fails to reach the cell surface augmented degradation like wild-type caveolin-1. Acidic lysosomal pH and increased protease activity are essential for digestion. We show that halving caveolin-1 protein levels significantly alkalinized lysosomal pH and decreased lysosomal enzyme activities. Taken together, our results reveal a novel role for intracellular caveolin-1 in modulating phagolysosomal function. Moreover, they show, for the first time, that organellar caveolin-1 significantly affects tissue functionality in vivo.
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Affiliation(s)
- Saumil Sethna
- From the Department of Biological Sciences, Center for Cancer Genetic Diseases and Gene Regulation, Fordham University, Bronx, New York 10458
| | - Tess Chamakkala
- From the Department of Biological Sciences, Center for Cancer Genetic Diseases and Gene Regulation, Fordham University, Bronx, New York 10458
| | - Xiaowu Gu
- the Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | - Timothy C Thompson
- the Department of Genitourinary Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Guangwen Cao
- the Department of Genitourinary Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Michael H Elliott
- the Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | - Silvia C Finnemann
- From the Department of Biological Sciences, Center for Cancer Genetic Diseases and Gene Regulation, Fordham University, Bronx, New York 10458,
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Huang RL, Zheng Z, Wang QH, Zhao XX, Deng YW, Jiao Y, Du XD. Mantle Branch-Specific RNA Sequences of Moon Scallop Amusium pleuronectes to Identify Shell Color-Associated Genes. PLoS One 2015; 10:e0141390. [PMID: 26496197 PMCID: PMC4619886 DOI: 10.1371/journal.pone.0141390] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/06/2015] [Indexed: 12/31/2022] Open
Abstract
Amusium pleuronectes (Linnaeus) that secretes red- and white-colored valves in two branches of mantle tissues is an excellent model for shell color research. High-throughput transcriptome sequencing and profiling were applied in this project to reveal the detailed molecular mechanism of this phenotype differentiation. In this study, 50,796,780 and 54,361,178 clean reads were generated from the left branch (secreting red valve, RS) and right branch (secreting white valve, WS) using the Illumina Hiseq 2000 platform. De novo assembly generated 149,375 and 176,652 unigenes with an average length of 764 bp and 698 bp in RS and WS, respectively. Kyoto encyclopedia of genes and genomes (KEGG) metabolic pathway analysis indicated that the differentially expressed genes were involved in 228 signaling pathways, and 43 genes were significantly enriched (P<0.01). Nineteen of 20 differentially expressed vitellogenin genes showed significantly high expression in RS, which suggested that they probably played a crucial role in organic pigment assembly and transportation of the shell. Moreover, 687 crystal formation-related (or biomineralization-related) genes were detected in A. pleuronectes, among which 144 genes exhibited significant difference between the two branches. Those genes could be classified into shell matrix framework participants, crystal nucleation and growth-related elements, upstream regulation factors, Ca level regulators, and other classifications. We also identified putative SNP and SSR markers from these samples which provided the markers for genetic diversity analysis, genetic linkage, QTL analysis. These results provide insight into the complexity of shell color differentiation in A. pleuronectes so as valuable resources for further research.
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Affiliation(s)
- Rong-lian Huang
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
| | - Zhe Zheng
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
| | - Qing-heng Wang
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
| | - Xiao-xia Zhao
- Environment Protection Monitoring Station, Environmental Protection Agency of Zhanjiang, Zhanjiang, China
| | - Yue-wen Deng
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
| | - Yu Jiao
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
| | - Xiao-dong Du
- Fishery College, Guangdong Ocean University, Zhanjiang, China
- Laboratory of Marine Pearl Culture, Zhanjiang, China
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24
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Ferrington DA, Sinha D, Kaarniranta K. Defects in retinal pigment epithelial cell proteolysis and the pathology associated with age-related macular degeneration. Prog Retin Eye Res 2015; 51:69-89. [PMID: 26344735 DOI: 10.1016/j.preteyeres.2015.09.002] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 08/29/2015] [Accepted: 09/01/2015] [Indexed: 12/12/2022]
Abstract
Maintenance of protein homeostasis, also referred to as "Proteostasis", integrates multiple pathways that regulate protein synthesis, folding, translocation, and degradation. Failure in proteostasis may be one of the underlying mechanisms responsible for the cascade of events leading to age-related macular degeneration (AMD). This review covers the major degradative pathways (ubiquitin-proteasome and lysosomal involvement in phagocytosis and autophagy) in the retinal pigment epithelium (RPE) and summarizes evidence of their involvement in AMD. Degradation of damaged and misfolded proteins via the proteasome occurs in coordination with heat shock proteins. Evidence of increased content of proteasome and heat shock proteins in retinas from human donors with AMD is consistent with increased oxidative stress and extensive protein damage with AMD. Phagocytosis and autophagy share key molecules in phagosome maturation as well as degradation of their cargo following fusion with lysosomes. Phagocytosis and degradation of photoreceptor outer segments ensures functional integrity of the neural retina. Autophagy rids the cell of toxic protein aggregates and defective mitochondria. Evidence suggesting a decline in autophagic flux includes the accumulation of autophagic substrates and damaged mitochondria in RPE from AMD donors. An age-related decrease in lysosomal enzymatic activity inhibits autophagic clearance of outer segments, mitochondria, and protein aggregates, thereby accelerating the accumulation of lipofuscin. This cumulative damage over a person's lifetime tips the balance in RPE from a state of para-inflammation, which strives to restore cell homeostasis, to the chronic inflammation associated with AMD.
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Affiliation(s)
- Deborah A Ferrington
- Department of Ophthalmology and Visual Neurosciences, 2001 6th St SE, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Debasish Sinha
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Room M035 Robert and Clarice Smith Bldg, 400 N Broadway, Baltimore, MD, 21287, USA.
| | - Kai Kaarniranta
- Department of Ophthalmology, University of Eastern Finland and Kuopio University Hospital, P.O. Box 100, 70029 KYS, Finland.
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25
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Frost LS, Lopes VS, Bragin A, Reyes-Reveles J, Brancato J, Cohen A, Mitchell CH, Williams DS, Boesze-Battaglia K. The Contribution of Melanoregulin to Microtubule-Associated Protein 1 Light Chain 3 (LC3) Associated Phagocytosis in Retinal Pigment Epithelium. Mol Neurobiol 2014; 52:1135-1151. [PMID: 25301234 DOI: 10.1007/s12035-014-8920-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/29/2014] [Indexed: 02/07/2023]
Abstract
A main requisite in the phagocytosis of ingested material is a coordinated series of maturation steps which lead to the degradation of ingested cargo. Photoreceptor outer segment (POS) renewal involves phagocytosis of the distal disk membranes by the retinal pigment epithelium (RPE). Previously, we identified melanoregulin (MREG) as an intracellular cargo-sorting protein required for the degradation of POS disks. Here, we provide evidence that MREG-dependent processing links both autophagic and phagocytic processes in LC3-associated phagocytosis (LAP). Ingested POS phagosomes are associated with endogenous LC3 and MREG. The LC3 association with POSs exhibited properties of LAP; it was independent of rapamycin pretreatment, but dependent on Atg5. Loss of MREG resulted in a decrease in the extent of LC3-POS association. Studies using DQ-BSA suggest that loss of MREG does not compromise the association and fusion of LC3-positive phagosomes with lysosomes. Furthermore, the mechanism of MREG action is likely through a protein complex that includes LC3, as determined by colocalization and immunoprecipitation in both RPE cells and macrophages. We posit that MREG participates in coordinating the association of phagosomes with LC3 for content degradation with the loss of MREG leading to phagosome accumulation.
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Affiliation(s)
- Laura S Frost
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Vanda S Lopes
- UCLA School of Medicine, Jules Stein Eye Institute, Los Angeles, CA, 90095, USA
| | - Alvina Bragin
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Juan Reyes-Reveles
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jennifer Brancato
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Art Cohen
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David S Williams
- UCLA School of Medicine, Jules Stein Eye Institute, Los Angeles, CA, 90095, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Frost LS, Mitchell CH, Boesze-Battaglia K. Autophagy in the eye: implications for ocular cell health. Exp Eye Res 2014; 124:56-66. [PMID: 24810222 DOI: 10.1016/j.exer.2014.04.010] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/10/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
Autophagy, a catabolic process by which a cell "eats" itself, turning over its own cellular constituents, plays a key role in cellular homeostasis. In an effort to maintain normal cellular function, autophagy is often up-regulated in response to environmental stresses and excessive organelle damage to facilitate aggregated protein removal. In the eye, virtually all cell types from those comprising the cornea in the front of the eye to the retinal pigment epithelium (RPE) providing a protective barrier for the retina at the back of the eye, rely on one or more aspects of autophagy to maintain structure and/or normal physiological function. In the lens autophagy plays a critical role in lens fiber cell maturation and the formation of the organelle free zone. Numerous studies delineating the role of Atg5, Vsp34 as well as FYCO1 in maintenance of lens transparency are discussed. Corneal endothelial dystrophies are also characterized as having elevated levels of autophagic proteins. Therefore, novel modulators of autophagy such as lithium and melatonin are proposed as new therapeutic strategies for this group of dystrophies. In addition, we summarize how corneal Herpes Simplex Virus (HSV-1) infection subverts the cornea's response to infection by inhibiting the normal autophagic response. Using glaucoma models we analyze the relative contribution of autophagy to cell death and cell survival. The cytoprotective role of autophagy is further discussed in an analysis of photoreceptor cell heath and function. We focus our analysis on the current understanding of autophagy in photoreceptor and RPE health, specifically on the diverse role of autophagy in rods and cones as well as its protective role in light induced degeneration. Lastly, in the RPE we highlight hybrid phagocytosis-autophagy pathways. This comprehensive review allows us to speculate on how alterations in various stages of autophagy contribute to glaucoma and retinal degenerations.
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Affiliation(s)
- Laura S Frost
- Department of Biochemistry, University of Pennsylvania, SDM, Philadelphia, PA 19104, USA
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, SDM, Philadelphia, PA 19104, USA
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Mazzoni F, Safa H, Finnemann SC. Understanding photoreceptor outer segment phagocytosis: use and utility of RPE cells in culture. Exp Eye Res 2014; 126:51-60. [PMID: 24780752 DOI: 10.1016/j.exer.2014.01.010] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 12/21/2022]
Abstract
RPE cells are the most actively phagocytic cells in the human body. In the eye, RPE cells face rod and cone photoreceptor outer segments at all times but contribute to shedding and clearance phagocytosis of distal outer segment tips only once a day. Analysis of RPE phagocytosis in situ has succeeded in identifying key players of the RPE phagocytic mechanism. Phagocytic processes comprise three distinct phases, recognition/binding, internalization, and digestion, each of which is regulated separately by phagocytes. Studies of phagocytosis by RPE cells in culture allow specifically analyzing and manipulating these distinct phases to identify their molecular mechanisms. Here, we compare similarities and differences of primary, immortalized, and stem cell-derived RPE cells in culture to RPE cells in situ with respect to phagocytic function. We discuss in particular potential pitfalls of RPE cell culture phagocytosis assays. Finally, we point out considerations for phagocytosis assay development for future studies.
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Affiliation(s)
- Francesca Mazzoni
- Department of Biological Sciences, Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, USA
| | - Hussein Safa
- Department of Biological Sciences, Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, USA
| | - Silvia C Finnemann
- Department of Biological Sciences, Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, USA.
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28
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Poliakov E, Strunnikova NV, Jiang JK, Martinez B, Parikh T, Lakkaraju A, Thomas C, Brooks BP, Redmond TM. Multiple A2E treatments lead to melanization of rod outer segment-challenged ARPE-19 cells. Mol Vis 2014; 20:285-300. [PMID: 24644403 PMCID: PMC3955416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 03/11/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Daily phagocytosis of outer segments (OSs) and retinoid recycling by the RPE lead to the accumulation of storage bodies in the RPE containing autofluorescent lipofuscin, which consists of lipids and bisretinoids such as A2E and its oxidation products. Accumulation of A2E and its oxidation products is implicated in the pathogenesis of several retinal degenerative diseases. However, A2E accumulates in the RPE during normal aging. In this study, we used a cell model to determine the homeostatic mechanisms of RPE cells in response to A2E accumulation. METHODS To distinguish between pathologic and normal responses of the RPE to A2E accumulation, we treated established ARPE-19 cells (cultured for 3 weeks after reaching confluence) with low micromolar amounts of A2E for several weeks. We compared the lysosomal function, lysosomal pH, degree of OS digestion, and melanization of the treated cells to untreated control cells in response to a challenge of purified rod OSs (ROSs). A2E was analyzed with high-performance liquid chromatography (HPLC); and A2E and melanin were identified with mass spectrometry. RESULTS We found that post-confluent ARPE-19 cells took up and accumulated A2E under dim light conditions. Spectral analysis of the HPLC separations and mass spectrometry showed that A2E-fed cells contained A2E and oxidized A2E (furan-A2E). A2E accumulation led to a modest increase (up to 0.25 unit) in lysosomal pH in these cells. The specific activity of cathepsin D and lysosomal acid phosphatase was reduced in the A2E-treated cells, but ROS degradation was not impaired. We found that, upon challenge with ROSs, melanin pigment was induced in the lysosomal fraction of the A2E-treated ARPE-19 cells. Thus, the ARPE-19 cells responded to the A2E treatment and ROS challenge by producing a melanin-containing lysosome fraction. We speculate that this prevents them from becoming impaired in OS processing. CONCLUSIONS We used a modified ARPE-19 cell model in which melanization was elicited as a response to chronic accumulation of A2E. We found that although A2E treatment led, as has been previously reported, to modest lysosomal alkalinization and lysosomal impairment of ARPE-19 cells, a potential homeostatic mechanism may involve production of a special type of lysosomes containing melanin.
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Affiliation(s)
- Eugenia Poliakov
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | | | - Jian-kang Jiang
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, NIH, Rockville, MD
| | - Bianca Martinez
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | - Toral Parikh
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | - Aparna Lakkaraju
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Craig Thomas
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, NIH, Rockville, MD
| | - Brian P. Brooks
- Ophthalmic Genetics and Visual Function Branch, NEI, NIH, Bethesda, MD
| | - T. Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
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29
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Animal Models, in "The Quest to Decipher RPE Phagocytosis". ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:77-83. [PMID: 24664683 DOI: 10.1007/978-1-4614-3209-8_10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Renewal and elimination of aged photoreceptor outer segment (POS) tips by cells from the retinal pigment epithelial (RPE) is a daily rhythmic process that is crucial for long-term vision. Anomalies can arise during any of the sequential steps required for completion of this phagocytic function, from POS recognition to complete digestion of POS components. During the past 15 years, many animal models helped us characterize the molecular machinery implicated in RPE phagocytosis as well as understand associated defects leading to various retinal pathologies. Depending on which part of the machinery is flawed, phenotypes can either appear early in life, such as retinitis pigmentosa or Usher syndrome, or develop with aging of the individual, like age-related macular degeneration, affecting first either the peripheral or the central retina. This chapter describes mouse and rat models related to defective phagocytosis, and how they have been a tremendous help for us to comprehend RPE phagocytosis, its rhythm, and its failures.
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Loss of melanoregulin (MREG) enhances cathepsin-D secretion by the retinal pigment epithelium. Vis Neurosci 2013; 30:55-64. [PMID: 23611523 DOI: 10.1017/s0952523813000096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cathepsin-D (Cat-D) is a major proteolytic enzyme in phagocytic cells. In the retinal pigment epithelium (RPE), it is responsible for the daily degradation of photoreceptor outer segments (POSs) to maintain retinal homeostasis. Melanoregulin (MREG)-mediated loss of phagocytic capacity has been linked to diminished intracellular Cat-D activity. Here, we demonstrate that loss of MREG enhances the secretion of intermediate Cat-D (48 kDa), resulting in a net enhancement of extracellular Cat-D activity. These results suggest that MREG is required to maintain Cat-D homeostasis in the RPE and likely plays a protective role in retinal health. In this regard, in the Mreg dsu/dsu mouse, we observe increased basal laminin. Loss of the Mreg dsu allele is not lethal and therefore leads to slow age-dependent changes in the RPE. Thus, we propose that this model will allow us to study potential dysregulatory functions of Cat-D in retinal disease.
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Wu XS, Martina JA, Hammer JA. Melanoregulin is stably targeted to the melanosome membrane by palmitoylation. Biochem Biophys Res Commun 2012; 426:209-14. [PMID: 22940130 PMCID: PMC3456999 DOI: 10.1016/j.bbrc.2012.08.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/15/2012] [Indexed: 11/22/2022]
Abstract
In mammals, pigments are made by melanocytes within a specialized organelle, the melanosome. Mature, pigment-laden melanosomes are then transferred to keratinocytes to drive the visible pigmentation of the animal's hair and skin. The dilute suppressor (dsu) locus encodes an extragenic suppressor of the pigmentation defect exhibited by mice lacking myosin Va (i.e. dilute mice). We recently showed that melanoregulin, the product of the dsu locus, functions as a negative regulator of a shedding mechanism that drives the intercellular transfer of melanosomes from the melanocyte to the keratinocyte. Here we address melanoregulin's localization within the melanocyte, as well as the molecular basis for its localization. First, we confirm and extend recently published results using exogenous, GFP-tagged melanoregulin by showing that endogenous melanoregulin also targets extensively to melanosomes. Second, using site-directed mutagenesis, metabolic labeling with H(3)-palmitate, and an inhibitor of palmitoylation in vivo, we show that the targeting of melanoregulin to the limiting membranes of melanosomes in melanocytes and lysosomes in CV1 cells depends critically on the palmitoylation of one or more of six closely-spaced cysteine residues located near melanoregulin's N-terminus. Finally, using Fluorescence Recovery after Photobleaching (FRAP), we show that melanoregulin-GFP exhibits little if any tendency to cycle in and out of the melanosome membrane. We conclude that multiple palmitoylation serves to stably anchor melanoregulin in the melanosome membrane.
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Affiliation(s)
- Xufeng S Wu
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8017, USA.
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32
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Rachel RA, Nagashima K, O'Sullivan TN, Frost LS, Stefano FP, Marigo V, Boesze-Battaglia K. Melanoregulin, product of the dsu locus, links the BLOC-pathway and OA1 in organelle biogenesis. PLoS One 2012; 7:e42446. [PMID: 22984402 PMCID: PMC3439427 DOI: 10.1371/journal.pone.0042446] [Citation(s) in RCA: 11] [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: 05/29/2012] [Accepted: 07/05/2012] [Indexed: 12/27/2022] Open
Abstract
Humans with Hermansky-Pudlak Syndrome (HPS) or ocular albinism (OA1) display abnormal aspects of organelle biogenesis. The multigenic disorder HPS displays broad defects in biogenesis of lysosome-related organelles including melanosomes, platelet dense granules, and lysosomes. A phenotype of ocular pigmentation in OA1 is a smaller number of macromelanosomes, in contrast to HPS, where in many cases the melanosomes are smaller than normal. In these studies we define the role of the Mregdsu gene, which suppresses the coat color dilution of Myo5a, melanophilin, and Rab27a mutant mice in maintaining melanosome size and distribution. We show that the product of the Mregdsu locus, melanoregulin (MREG), interacts both with members of the HPS BLOC-2 complex and with Oa1 in regulating melanosome size. Loss of MREG function facilitates increase in the size of micromelanosomes in the choroid of the HPS BLOC-2 mutants ruby, ruby2, and cocoa, while a transgenic mouse overexpressing melanoregulin corrects the size of retinal pigment epithelium (RPE) macromelanosomes in Oa1ko/ko mice. Collectively, these results suggest that MREG levels regulate pigment incorporation into melanosomes. Immunohistochemical analysis localizes melanoregulin not to melanosomes, but to small vesicles in the cytoplasm of the RPE, consistent with a role for this protein in regulating membrane interactions during melanosome biogenesis. These results provide the first link between the BLOC pathway and Oa1 in melanosome biogenesis, thus supporting the hypothesis that intracellular G-protein coupled receptors may be involved in the biogenesis of other organelles. Furthermore these studies provide the foundation for therapeutic approaches to correct the pigment defects in the RPE of HPS and OA1.
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Affiliation(s)
- Rivka A. Rachel
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, Bethesda, Maryland, United States of America
| | - Kunio Nagashima
- Frederick National Laboratory for Cancer Research, SAIC-Frederick, Frederick, Maryland, United States of America
| | - T. Norene O'Sullivan
- National Cancer Institute-Frederick, Frederick, Maryland, United States of America
| | - Laura S. Frost
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Frank P. Stefano
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Live Cell Imaging Core, School of Dental Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Valeria Marigo
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Abstract
Modifier genes are an integral part of the genetic landscape in both humans and experimental organisms, but have been less well explored in mammals than other systems. A growing number of modifier genes in mouse models of disease nonetheless illustrate the potential for novel findings, while new technical advances promise many more to come. Modifier genes in mouse models include induced mutations and spontaneous or wild-derived variations captured in inbred strains. Identification of modifiers among wild-derived variants in particular should detect disease modifiers that have been shaped by selection and might therefore be compatible with high fitness and function. Here we review selected examples and argue that modifier genes derived from natural variation may provide a bias for nodes in genetic networks that have greater intrinsic plasticity and whose therapeutic manipulation may therefore be more resilient to side effects than conventional targets.
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Affiliation(s)
- Bruce A Hamilton
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, United States of America.
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34
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Ohbayashi N, Fukuda M. Role of Rab family GTPases and their effectors in melanosomal logistics. J Biochem 2012; 151:343-51. [DOI: 10.1093/jb/mvs009] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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35
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Ohbayashi N, Maruta Y, Ishida M, Fukuda M. Melanoregulin regulates retrograde melanosome transport through interaction with the RILP-p150Glued complex in melanocytes. J Cell Sci 2012; 125:1508-18. [PMID: 22275436 DOI: 10.1242/jcs.094185] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Melanoregulin (Mreg), a product of the dilute suppressor gene, has been implicated in the regulation of melanosome transport in mammalian epidermal melanocytes, given that Mreg deficiency was found to restore peripheral melanosome distribution from perinuclear melanosome aggregation in Rab27A-deficient melanocytes. However, the function of Mreg in melanosome transport has remained unclear. Here, we show that Mreg regulates microtubule-dependent retrograde melanosome transport through the dynein-dynactin motor complex. Mreg interacted with the C-terminal domain of Rab-interacting lysosomal protein (RILP) and formed a complex with RILP and p150(Glued) (also known as dynactin subunit 1, DCTN1), a component of the dynein-dynactin motor complex, in cultured cells. Overexpression of Mreg, RILP or both, in normal melanocytes induced perinuclear melanosome aggregation, whereas knockdown of Mreg or functional disruption of the dynein-dynactin motor complex restored peripheral melanosome distribution in Rab27A-deficient melanocytes. These findings reveal a new mechanism by which the dynein-dynactin motor complex recognizes Mreg on mature melanosomes through interaction with RILP and is involved in the centripetal movement of melanosomes.
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Affiliation(s)
- Norihiko Ohbayashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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Gouras P, Brown K, Ivert L, Neuringer M. A novel melano-lysosome in the retinal epithelium of rhesus monkeys. Exp Eye Res 2011; 93:937-46. [PMID: 22056912 PMCID: PMC6314486 DOI: 10.1016/j.exer.2011.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 10/05/2011] [Accepted: 10/18/2011] [Indexed: 02/02/2023]
Abstract
The large phagocytic load that confronts the retinal pigment epithelium (RPE) is thought to play a possible role in the pathogenesis of age related macular degeneration (AMD) that afflicts both humans and monkeys. Our knowledge of how RPE degrades phagosomes and other intra-cellular material by lysosomal action is still rudimentary. In this paper we examine organelles that play a role in this process, melanosome, lysosomes and phagosomes, in the RPE of young and old rhesus monkeys in order to better understand lysosomal autophagy and heterophagy in the RPE and its possible role in AMD. We used electron microscopy to detect and describe the characteristics of melanosomes and lysosome-like organelles in the macular RPE of rhesus monkeys (Macaca mulatta) that were 1, 6, 24, 24, 26 and 35 years of age. The measurements include the number, shape and size of these organelles located in the basal, middle and apical regions of RPE cells. Phaagosomes were also examined but not counted or measured for size or shape because of their rarity. Melanosomes were homogeneously dark with a circular or elliptical shape and decreased in number with age. Smaller melanosomes were more common at the basal side of the RPE. Among the small melanosomes, we found an organelle that was losing melanin in varying degrees; in some cases was nearly devoid of melanin. Because of the melanin loss, we considered this organelle to be a unique type of autophagic melano-lysosome, which we called a Type 1 lysosome. We found another organelle, more canonically lysosomal, which we called a Type 2 lysosome. This organelle was composed of a light matrix containing melanosomes in various stages of degradation. Type 2 lysosomes without melanosomes were rare. Type 2 lysosomes increased while Type 1 decreased in number with age. Phagosomes were rare in both young and old monkeys. They made close contact with Type 2 lysosomes which we considered responsible for their degradation. Melanosomes are being lost from monkey RPE with age. Much of this loss is carried out by two types of lysosomes. One, not defined as unique before, appears to be autophagic in digesting its own melanin; it has been called a Type 1 lysosome. The other, a more canonical lysosome, is both heterophagic in digesting phagosomes and autophagic in digesting local melanosomes; it has been called a Type 2 lysosome. Type 1 lysosomes decrease while type 2 lysosomes increase with age. The loss of melanin is considered to be detrimental to the RPE since it reduces melanin's protective action against light toxicity and oxidative stress. Phagosomes appear to be degraded by membrane contacts with Type 2 lysosomes. The loss of melanin and the buildup of Type 2 lysosomes occur at an earlier age in monkeys than humans implying that a greater vulnerability to senescence accelerates the rate of AMD in monkeys.
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Affiliation(s)
- Peter Gouras
- Department of Ophthalmology, Columbia University, 630 W 168th Street, New York, NY 10032, USA.
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Abstract
Advances in live-cell microscopy have revealed the extraordinarily dynamic nature of intracellular organelles. Moreover, movement appears to be critical in establishing and maintaining intracellular organization and organellar and cellular function. Motility is regulated by the activity of organelle-associated motor proteins, kinesins, dyneins and myosins, which move cargo along polar MT (microtubule) and actin tracks. However, in most instances, the motors that move specific organelles remain mysterious. Over recent years, pigment granules, or melanosomes, within pigment cells have provided an excellent model for understanding the molecular mechanisms by which motor proteins associate with and move intracellular organelles. In the present paper, we discuss recent discoveries that shed light on the mechanisms of melanosome transport and highlight future prospects for the use of pigment cells in unravelling general molecular mechanisms of intracellular transport.
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