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Patil H, Yi H, Cho KI, Ferreira PA. Proteostatic Remodeling of Small Heat Shock Chaperones─Crystallins by Ran-Binding Protein 2─and the Peptidyl-Prolyl cis-trans Isomerase and Chaperone Activities of Its Cyclophilin Domain. ACS Chem Neurosci 2024; 15:1967-1989. [PMID: 38657106 DOI: 10.1021/acschemneuro.3c00792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
Disturbances in protein phase transitions promote protein aggregation─a neurodegeneration hallmark. The modular Ran-binding protein 2 (Ranbp2) is a cytosolic molecular hub for rate-limiting steps of phase transitions of Ran-GTP-bound protein ensembles exiting nuclear pores. Chaperones also regulate phase transitions and proteostasis by suppressing protein aggregation. Ranbp2 haploinsufficiency promotes the age-dependent neuroprotection of the chorioretina against phototoxicity by proteostatic regulations of neuroprotective substrates of Ranbp2 and by suppressing the buildup of polyubiquitylated substrates. Losses of peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone activities of the cyclophilin domain (CY) of Ranbp2 recapitulate molecular effects of Ranbp2 haploinsufficiency. These CY impairments also stimulate deubiquitylation activities and phase transitions of 19S cap subunits of the 26S proteasome that associates with Ranbp2. However, links between CY moonlighting activity, substrate ubiquitylation, and proteostasis remain incomplete. Here, we reveal the Ranbp2 regulation of small heat shock chaperones─crystallins in the chorioretina by proteomics of mice with total or selective modular deficits of Ranbp2. Specifically, loss of CY PPIase of Ranbp2 upregulates αA-Crystallin, which is repressed in adult nonlenticular tissues. Conversely, impairment of CY's chaperone activity opposite to the PPIase pocket downregulates a subset of αA-Crystallin's substrates, γ-crystallins. These CY-dependent effects cause age-dependent and chorioretinal-selective declines of ubiquitylated substrates without affecting the chorioretinal morphology. A model emerges whereby inhibition of Ranbp2's CY PPIase remodels crystallins' expressions, subdues molecular aging, and preordains the chorioretina to neuroprotection by augmenting the chaperone capacity and the degradation of polyubiquitylated substrates against proteostatic impairments. Further, the druggable Ranbp2 CY holds pan-therapeutic potential against proteotoxicity and neurodegeneration.
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Affiliation(s)
- Hemangi Patil
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Haiqing Yi
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Kyoung-In Cho
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Paulo A Ferreira
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Pathology Duke University Medical Center, Durham, North Carolina 27710, United States
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Patil H, Cho KI, Ferreira PA. Proteostatic remodeling of small heat shock chaperones - crystallins by Ran-binding protein 2 and the peptidyl-prolyl cis-trans isomerase and chaperone activities of its cyclophilin domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.26.577462. [PMID: 38352504 PMCID: PMC10862737 DOI: 10.1101/2024.01.26.577462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Disturbances in phase transitions and intracellular partitions of nucleocytoplasmic shuttling substrates promote protein aggregation - a hallmark of neurodegenerative diseases. The modular Ran-binding protein 2 (Ranbp2) is a cytosolic molecular hub for rate-limiting steps of disassembly and phase transitions of Ran-GTP-bound protein ensembles exiting nuclear pores. Chaperones also play central roles in phase transitions and proteostasis by suppressing protein aggregation. Ranbp2 haploinsufficiency promotes the age-dependent neuroprotection of the chorioretina against photo-oxidative stress by proteostatic regulations of Ranbp2 substrates and by countering the build-up of poly-ubiquitylated substrates. Further, the peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone activities of the cyclophilin domain (CY) of Ranbp2 modulate the proteostasis of selective neuroprotective substrates, such as hnRNPA2B1, STAT3, HDAC4 or L/M-opsin, while promoting a decline of ubiquitylated substrates. However, links between CY PPIase activity on client substrates and its effect(s) on ubiquitylated substrates are unclear. Here, proteomics of genetically modified mice with deficits of Ranbp2 uncovered the regulation of the small heat shock chaperones - crystallins by Ranbp2 in the chorioretina. Loss of CY PPIase of Ranbp2 up-regulates αA-crystallin proteostasis, which is repressed in non-lenticular tissues. Conversely, the αA-crystallin's substrates, γ-crystallins, are down-regulated by impairment of CY's C-terminal chaperone activity. These CY-dependent effects cause the age-dependent decline of ubiquitylated substrates without overt chorioretinal morphological changes. A model emerges whereby the Ranbp2 CY-dependent remodeling of crystallins' proteostasis subdues molecular aging and preordains chorioretinal neuroprotection by augmenting the chaperone buffering capacity and the decline of ubiquitylated substrates against proteostatic impairments. Further, CY's moonlighting activity holds pan -therapeutic potential against neurodegeneration.
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Mollick T, Darekar S, Dalarun B, Plastino F, Zhang J, Fernández AP, Alkasalias T, André H, Laín S. Retinoblastoma vulnerability to combined de novo and salvage pyrimidine ribonucleotide synthesis pharmacologic blockage. Heliyon 2024; 10:e23831. [PMID: 38332874 PMCID: PMC10851301 DOI: 10.1016/j.heliyon.2023.e23831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 12/05/2023] [Accepted: 12/13/2023] [Indexed: 02/10/2024] Open
Abstract
Retinoblastoma is an eye cancer that commonly affects young children. Despite significant advances, current treatments cause side effects even when administered locally, and patients may still have to undergo enucleation. This is particularly disheartening in cases of bilateral retinoblastoma. Hence, there is an urgent need for novel therapeutic strategies. Inhibitors of the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in the de novo pyrimidine ribonucleotide synthesis pathway, have proven to be effective in preclinical trials against several cancers including pediatric cancers. Here we tested whether blocking pyrimidine ribonucleotide synthesis promotes retinoblastoma cell death. Cultured retinoblastoma cell lines were treated with small molecule inhibitors of DHODH alone or in combination with inhibitors of nucleoside uptake to also block the salvage pathway for pyrimidine ribonucleotide formation. On their own, DHODH inhibitors had a moderate killing effect. However, the combination with nucleoside uptake inhibitors greatly enhanced the effect of DHODH inhibition. In addition, we observed that pyrimidine ribonucleotide synthesis blockage can cause cell death in a p53 mutant retinoblastoma cell line derived from a patient with metastasis. Explaining these results, the analysis of a published patient cohort revealed that loss of chr16q22.2 (containing the DHODH gene) is amongst the most frequent alterations in retinoblastoma and that these tumors often show gains in chromosome regions expressing pyrimidine ribonucleotide salvage factors. Furthermore, these genome alterations associate with malignancy. These results indicate that targeting pyrimidine ribonucleotide synthesis may be an effective therapeutic strategy to consider as a treatment for retinoblastoma.
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Affiliation(s)
- Tanzina Mollick
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Suhas Darekar
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Basile Dalarun
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Flavia Plastino
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Juan Zhang
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Andres Pastor Fernández
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Twana Alkasalias
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
- General Directorate of Scientific Research Center, Salahaddin University-Erbil, Erbil, Kurdistan Region, Iraq
| | - Helder André
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Sonia Laín
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
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Richards CJ, Pulido JS. Random Allelic Expression in Inherited Retinal Disease Genes. Curr Issues Mol Biol 2023; 45:10018-10025. [PMID: 38132471 PMCID: PMC10742332 DOI: 10.3390/cimb45120625] [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: 11/13/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a significant contributor to visual loss in children and young adults, falling second only to diabetic retinopathy. Understanding the pathogenic mechanisms of IRDs remains paramount. Some autosomal genes exhibit random allelic expression (RAE), similar to X-chromosome inactivation. This study identifies RAE genes in IRDs. Genes in the Retinal Information Network were cross-referenced with the recent literature to identify expression profiles, RAE, or biallelic expression (BAE). Loss-of-function intolerance (LOFI) was determined by cross-referencing the existing literature. Molecular and biological pathways that are significantly enriched were evaluated using gene ontology. A total of 184 IRD-causing genes were evaluated. Of these, 31 (16.8%) genes exhibited RAE. LOFI was exhibited in 6/31 (19.4%) of the RAE genes and 18/153 (11.8%) of the BAE genes. Brain tissue exhibited BAE in 107/128 (83.6%) genes for both sexes. The molecular pathways significantly enriched among BAE genes were photoreceptor activity, tubulin binding, and nucleotide/ribonucleotide binding. The biologic pathways significantly enriched for RAE genes were equilibrioception, parallel actin filament bundle assembly, photoreceptor cell outer segment organization, and protein depalmitoylation. Allele-specific expression may be a mechanism underlying IRD phenotypic variability, with clonal populations of embryologic precursor cells exhibiting RAE. Brain tissue preferentially exhibited BAE, possibly due to selective pressures against RAE. Pathways critical for cellular and visual function were enriched in BAE, which may offer a survival benefit.
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Bonezzi PJ, Tarchick MJ, Moore BD, Renna JM. Light drives the developmental progression of outer retinal function. J Gen Physiol 2023; 155:e202213262. [PMID: 37432412 PMCID: PMC10336150 DOI: 10.1085/jgp.202213262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 02/24/2023] [Accepted: 06/08/2023] [Indexed: 07/12/2023] Open
Abstract
The complex nature of rod and cone photoreceptors and the light-evoked responsivity of bipolar cells in the mature rodent retina have been well characterized. However, little is known about the emergent light-evoked response properties of the mouse retina and the role light plays in shaping these emergent responses. We have previously demonstrated that the outer retina is responsive to green light as early as postnatal day 8 (P8). Here, we characterize the progression of both photoreceptors (rods and cones) and bipolar cell responses during development and into adulthood using ex vivo electroretinogram recordings. Our data show that the majority of photoreceptor response at P8 originates from cones and that these outputs drive second-order bipolar cell responses as early as P9. We find that the magnitude of the photoresponse increases concurrently with each passing day of postnatal development and that many functional properties of these responses, as well as the relative rod/cone contributions to the total light-evoked response, are age dependent. We compare these responses at eye opening and maturity to age-matched animals raised in darkness and found that the absence of light diminishes emergent and mature cone-to-bipolar cell signaling. Furthermore, we found cone-evoked responses to be significantly slower in dark-reared retinas. Together, this work characterizes the developmental photoresponsivity of the mouse retina while highlighting the importance of properly timed sensory input for the maturation of the first visual system synapse.
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Affiliation(s)
- Paul J. Bonezzi
- Department of Biology, The University of Akron, Akron, OH, USA
| | | | | | - Jordan M. Renna
- Department of Biology, The University of Akron, Akron, OH, USA
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Zhu S, Xu R, Engel AL, Wang Y, McNeel R, Hurley JB, Chao JR, Du J. Proline provides a nitrogen source in the retinal pigment epithelium to synthesize and export amino acids for the neural retina. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.18.537355. [PMID: 37131780 PMCID: PMC10153141 DOI: 10.1101/2023.04.18.537355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
It is known that metabolic defects in the retinal pigment epithelium (RPE) can cause degeneration of its neighboring photoreceptors in the retina, leading to retinal degenerative diseases such as age-related macular degeneration. However, how RPE metabolism supports the health of the neural retina remains unclear. The retina requires exogenous nitrogen sources for protein synthesis, neurotransmission, and energy metabolism. Using 15N tracing coupled with mass spectrometry, we found human RPE can utilize the nitrogen in proline to produce and export 13 amino acids, including glutamate, aspartate, glutamine, alanine and serine. Similarly, we found this proline nitrogen utilization in the mouse RPE/choroid but not in the neural retina of explant cultures. Co-culture of human RPE with the retina showed that the retina can take up the amino acids, especially glutamate, aspartate and glutamine, generated from proline nitrogen in the RPE. Intravenous delivery of 15N proline in vivo demonstrated 15N-derived amino acids appear earlier in the RPE before the retina. We also found proline dehydrogenase (PRODH), the key enzyme in proline catabolism is highly enriched in the RPE but not the retina. The deletion of PRODH blocks proline nitrogen utilization in RPE and the import of proline nitrogen-derived amino acids in the retina. Our findings highlight the importance of RPE metabolism in supporting nitrogen sources for the retina, providing insight into understanding the mechanisms of the retinal metabolic ecosystem and RPE-initiated retinal degenerative diseases.
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Affiliation(s)
- Siyan Zhu
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506
- Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, WV 26506
| | - Rong Xu
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506
| | - Abbi L. Engel
- Department of Ophthalmology, University of Washington, Seattle, WA 98109
| | - Yekai Wang
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506
| | - Rachel McNeel
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506
| | - James B. Hurley
- Department of Ophthalmology, University of Washington, Seattle, WA 98109
- Department of Biochemistry, University of Washington, Seattle, WA 98109
| | - Jennifer R. Chao
- Department of Ophthalmology, University of Washington, Seattle, WA 98109
| | - Jianhai Du
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506
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7
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Pandey RS, Krebs MP, Bolisetty MT, Charette JR, Naggert JK, Robson P, Nishina PM, Carter GW. Single-Cell RNA Sequencing Reveals Molecular Features of Heterogeneity in the Murine Retinal Pigment Epithelium. Int J Mol Sci 2022; 23:10419. [PMID: 36142331 PMCID: PMC9499471 DOI: 10.3390/ijms231810419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/09/2022] [Accepted: 09/05/2022] [Indexed: 11/16/2022] Open
Abstract
Transcriptomic analysis of the mammalian retinal pigment epithelium (RPE) aims to identify cellular networks that influence ocular development, maintenance, function, and disease. However, available evidence points to RPE cell heterogeneity within native tissue, which adds complexity to global transcriptomic analysis. Here, to assess cell heterogeneity, we performed single-cell RNA sequencing of RPE cells from two young adult male C57BL/6J mice. Following quality control to ensure robust transcript identification limited to cell singlets, we detected 13,858 transcripts among 2667 and 2846 RPE cells. Dimensional reduction by principal component analysis and uniform manifold approximation and projection revealed six distinct cell populations. All clusters expressed transcripts typical of RPE cells; the smallest (C1, containing 1-2% of total cells) exhibited the hallmarks of stem and/or progenitor (SP) cells. Placing C1-6 along a pseudotime axis suggested a relative decrease in melanogenesis and SP gene expression and a corresponding increase in visual cycle gene expression upon RPE maturation. K-means clustering of all detected transcripts identified additional expression patterns that may advance the understanding of RPE SP cell maintenance and the evolution of cellular metabolic networks during development. This work provides new insights into the transcriptome of the mouse RPE and a baseline for identifying experimentally induced transcriptional changes in future studies of this tissue.
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Affiliation(s)
- Ravi S. Pandey
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Dr., Farmington, CT 06032, USA
| | - Mark P. Krebs
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Mohan T. Bolisetty
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Dr., Farmington, CT 06032, USA
| | | | | | - Paul Robson
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Dr., Farmington, CT 06032, USA
| | - Patsy M. Nishina
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
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Rasys AM, Pau SH, Irwin KE, Luo S, Kim HQ, Wahle MA, Trainor PA, Menke DB, Lauderdale JD. Ocular elongation and retraction in foveated reptiles. Dev Dyn 2021; 250:1584-1599. [PMID: 33866663 PMCID: PMC10731578 DOI: 10.1002/dvdy.348] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Pronounced asymmetric changes in ocular globe size during eye development have been observed in a number of species ranging from humans to lizards. In contrast, largely symmetric changes in globe size have been described for other species like rodents. We propose that asymmetric changes in the three-dimensional structure of the developing eye correlate with the types of retinal remodeling needed to produce areas of high photoreceptor density. To test this idea, we systematically examined three-dimensional aspects of globe size as a function of eye development in the bifoveated brown anole, Anolis sagrei. RESULTS During embryonic development, the anole eye undergoes dynamic changes in ocular shape. Initially spherical, the eye elongates in the presumptive foveal regions of the retina and then proceeds through a period of retraction that returns the eye to its spherical shape. During this period of retraction, pit formation and photoreceptor cell packing are observed. We found a similar pattern of elongation and retraction associated with the single fovea of the veiled chameleon, Chamaeleo calyptratus. CONCLUSIONS These results, together with those reported for other foveated species, support the idea that areas of high photoreceptor packing occur in regions where the ocular globe asymmetrically elongates and retracts during development.
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Affiliation(s)
- Ashley M. Rasys
- Department of Cellular Biology, The University of Georgia, Athens, Georgia
| | - Shana H. Pau
- Department of Genetics, The University of Georgia, Athens, Georgia
| | - Katherine E. Irwin
- Department of Cellular Biology, The University of Georgia, Athens, Georgia
| | - Sherry Luo
- Department of Genetics, The University of Georgia, Athens, Georgia
| | - Hannah Q. Kim
- Department of Cellular Biology, The University of Georgia, Athens, Georgia
| | | | - Paul A. Trainor
- Stowers Institute for Medical Research, Kansas City, Missouri
- Department of Anatomy & Cell Biology, The University of Kansas School of Medicine, Kansas City, Kansas
| | - Douglas B. Menke
- Department of Genetics, The University of Georgia, Athens, Georgia
| | - James D. Lauderdale
- Department of Cellular Biology, The University of Georgia, Athens, Georgia
- Neuroscience Division of the Biomedical and Translational Sciences Institute, The University of Georgia, Athens, Georgia
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9
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BRCA2 Promotes Spontaneous Homologous Recombination In Vivo. Cancers (Basel) 2021; 13:cancers13153663. [PMID: 34359565 PMCID: PMC8345144 DOI: 10.3390/cancers13153663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND BRCA2 is known to be a tumor suppressor involved in homologous recombination repair and presumed to prevent genome instability in normal tissues prior to the development of tumors. Typical assessment of BRCA2 deficiency on the genome involves cell-based models using cancer cells with mixed genetic contexts, but the role in normal tissue in vivo has not been clearly demonstrated. METHODS Using conditional deletion of Brca2 exon 11, the region containing all eight BRC repeats, in the retinal pigment epithelium and the pink-eyed unstable mouse model, we evaluate the frequency of DNA deletion events. RESULTS In the current study, we show that conditional loss of Brca2 exon 11 results in a decreased frequency of spontaneous homologous recombination compared to wild-type mice. Of note, we observe no apparent concomitant increase in events that indicate single-strand annealing by the pink-eyed unstable mouse model. CONCLUSIONS Therefore, our results demonstrate that BRCA2, as expected, is required for high-fidelity homologous recombination DNA repair in normal tissues, here in a tissue undergoing normal proliferation through normal development.
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Choi EH, Suh S, Einstein DE, Leinonen H, Dong Z, Rao SR, Fliesler SJ, Blackshaw S, Yu M, Peachey NS, Palczewski K, Kiser PD. An inducible Cre mouse for studying roles of the RPE in retinal physiology and disease. JCI Insight 2021; 6:146604. [PMID: 33784255 PMCID: PMC8262343 DOI: 10.1172/jci.insight.146604] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/25/2021] [Indexed: 01/04/2023] Open
Abstract
The retinal pigment epithelium (RPE) provides vital metabolic support for retinal photoreceptor cells and is an important player in numerous retinal diseases. Gene manipulation in mice using the Cre-LoxP system is an invaluable tool for studying the genetic basis of these retinal diseases. However, existing RPE-targeted Cre mouse lines have critical limitations that restrict their reliability for studies of disease pathogenesis and treatment, including mosaic Cre expression, inducer-independent activity, off-target Cre expression, and intrinsic toxicity. Here, we report the generation and characterization of a knockin mouse line in which a P2A-CreERT2 coding sequence is fused with the native RPE-specific 65 kDa protein (Rpe65) gene for cotranslational expression of CreERT2. Cre+/– mice were able to recombine a stringent Cre reporter allele with more than 99% efficiency and absolute RPE specificity upon tamoxifen induction at both postnatal days (PD) 21 and 50. Tamoxifen-independent Cre activity was negligible at PD64. Moreover, tamoxifen-treated Cre+/– mice displayed no signs of structural or functional retinal pathology up to 4 months of age. Despite weak RPE65 expression from the knockin allele, visual cycle function was normal in Cre+/– mice. These data indicate that Rpe65CreERT2 mice are well suited for studies of gene function and pathophysiology in the RPE.
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Affiliation(s)
- Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Susie Suh
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - David E Einstein
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
| | - Henri Leinonen
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - Zhiqian Dong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry, Jacobs School of Medicine and Biomedical Sciences and.,Neuroscience Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York, USA.,Research Service, VA Western New York Healthcare System, Buffalo, New York, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry, Jacobs School of Medicine and Biomedical Sciences and.,Neuroscience Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York, USA.,Research Service, VA Western New York Healthcare System, Buffalo, New York, USA
| | - Seth Blackshaw
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA
| | - Neal S Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA.,Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Department of Chemistry, School of Physical Sciences, University of California, Irvine, Irvine, California, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
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11
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Kim YK, Yu H, Summers VR, Donaldson KJ, Ferdous S, Shelton D, Zhang N, Chrenek MA, Jiang Y, Grossniklaus HE, Boatright JH, Kong J, Nickerson JM. Morphometric Analysis of Retinal Pigment Epithelial Cells From C57BL/6J Mice During Aging. Invest Ophthalmol Vis Sci 2021; 62:32. [PMID: 33616620 PMCID: PMC7910641 DOI: 10.1167/iovs.62.2.32] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 02/01/2021] [Indexed: 12/19/2022] Open
Abstract
Purpose To quantitatively evaluate the changes in orientation and morphometric features of mouse retinal pigment epithelial (RPE) cells in different regions of the eye during aging. Methods We segmented individual RPE cells from whole RPE flatmount images of C57BL/6J mice (postnatal days 30 to 720) using a machine-learning method and evaluated changes in morphometric features, including our newly developed metric combining alignment and shape of RPE cells during aging. Results Mainly, the anterior part of the RPE sheet grows during aging, while the posterior part remains constant. Changes in size and shape of the peripheral RPE cells are prominent with aging as cells become larger, elongated, and concave. Conversely, the central RPE cells maintain relatively constant size and numbers with aging. Cell count in the central area and the overall cell count (approximately 50,000) were relatively constant over different age groups. RPE cells also present a specific orientation concordance that matches the shape of the specific region of the eyeball. Those cells near the optic disc or equator have a circumferential orientation to cover the round shape of the eyeball, whereas those cells in the periphery have a radial orientation and corresponding radial elongation, the extent of which increases with aging and matches with axial elongation of the eyeball. Conclusions These results suggest that the fluid RPE morphology reflects various growth rates of underlying eyeball, and RPE cells could be classified into four regional classes (near the optic disc, central, equatorial, and peripheral) according to their morphometric features.
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Affiliation(s)
- Yong-Kyu Kim
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
- Department of Ophthalmology, Hallym University College of Medicine, Kangdong Sacred Heart Hospital, Seoul, South Korea
| | - Hanyi Yu
- Department of Computer Science, Emory University, Atlanta, Georgia, United States
| | - Vivian R. Summers
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Kevin J. Donaldson
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Salma Ferdous
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Debresha Shelton
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Nan Zhang
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
- Department of Ophthalmology, Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Micah A. Chrenek
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia, United States
| | - Hans E. Grossniklaus
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Jeffrey H. Boatright
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, Georgia, United States
| | - Jun Kong
- Department of Computer Science, Emory University, Atlanta, Georgia, United States
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia, United States
- Department of Computer Science, Georgia State University, Atlanta, Georgia, United States
| | - John M. Nickerson
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
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12
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Novikova YP, Grigoryan EN. Early Appearance of Aging Signs in the Retinal Pigment Epithelium in Young Albino Rats. Russ J Dev Biol 2020. [DOI: 10.1134/s1062360420060065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Sun WR, Ramirez S, Spiller KE, Zhao Y, Fuhrmann S. Nf2 fine-tunes proliferation and tissue alignment during closure of the optic fissure in the embryonic mouse eye. Hum Mol Genet 2020; 29:3373-3387. [PMID: 33075808 DOI: 10.1093/hmg/ddaa228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/29/2020] [Accepted: 10/12/2020] [Indexed: 11/14/2022] Open
Abstract
Uveal coloboma represents one of the most common congenital ocular malformations accounting for up to 10% of childhood blindness (~1 in 5000 live birth). Coloboma originates from defective fusion of the optic fissure (OF), a transient gap that forms during eye morphogenesis by asymmetric, ventral invagination. Genetic heterogeneity combined with the activity of developmentally regulated genes suggests multiple mechanisms regulating OF closure. The tumor suppressor and FERM domain protein Neurofibromin 2 (NF2) controls diverse processes in cancer, development and regeneration, via Hippo pathway and cytoskeleton regulation. In humans, NF2 mutations can cause ocular abnormalities, including coloboma, however, its actual role in OF closure is unknown. Using conditional inactivation in the embryonic mouse eye, our data indicate that loss of Nf2 function results in a novel underlying cause for coloboma. In particular, mutant eyes show substantially increased retinal pigmented epithelium (RPE) proliferation in the fissure region with concomitant acquisition of RPE cell fate. Cells lining the OF margin can maintain RPE fate ectopically and fail to transition from neuroepithelial to cuboidal shape. In the dorsal RPE of the optic cup, Nf2 inactivation leads to a robust increase in cell number, with local disorganization of the cytoskeleton components F-actin and pMLC2. We propose that RPE hyperproliferation is the primary cause for the observed defects causing insufficient alignment of the OF margins in Nf2 mutants and failure to fuse properly, resulting in persistent coloboma. Our findings indicate that limiting proliferation particularly in the RPE layer is a critical mechanism during OF closure.
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Affiliation(s)
- Wesley R Sun
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sara Ramirez
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Kelly E Spiller
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yan Zhao
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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14
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Keeling E, Chatelet DS, Tan NYT, Khan F, Richards R, Thisainathan T, Goggin P, Page A, Tumbarello DA, Lotery AJ, Ratnayaka JA. 3D-Reconstructed Retinal Pigment Epithelial Cells Provide Insights into the Anatomy of the Outer Retina. Int J Mol Sci 2020; 21:ijms21218408. [PMID: 33182490 PMCID: PMC7672636 DOI: 10.3390/ijms21218408] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 11/05/2020] [Accepted: 11/06/2020] [Indexed: 11/16/2022] Open
Abstract
The retinal pigment epithelium (RPE) is located between the neuroretina and the choroid, and plays a critical role in vision. RPE cells internalise outer segments (OS) from overlying photoreceptors in the daily photoreceptor renewal. Changes to RPE structure are linked with age and retinopathy, which has been described in the past by conventional 2D electron microscopy. We used serial block face scanning electron microscopy (SBF-SEM) to reconstruct RPE cells from the central mouse retina. Three-dimensional-reconstructed OS revealed the RPE to support large numbers of photoreceptors (90–216 per RPE cell). Larger bi-nucleate RPE maintained more photoreceptors, although their cytoplasmic volume was comparable to smaller mono-nucleate RPE supporting fewer photoreceptors. Scrutiny of RPE microvilli and interdigitating OS revealed the angle and surface area of contact between RPE and photoreceptors. Bi-nucleate RPE contained more mitochondria compared to mono-nucleate RPE. Furthermore, bi-nucleate cells contained larger sub-RPE spaces, supporting a likely association with disease. Use of perfusion-fixed tissues ensured the highest possible standard of preservation, providing novel insights into the 3D RPE architecture and changes linked with retinopathy. This study serves as a benchmark for comparing retinal tissues from donor eyes with age-related macular degeneration (AMD) and other retinopathies.
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Affiliation(s)
- Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
| | - David S. Chatelet
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, Southampton SO16 6YD, UK; (D.S.C.); (P.G.); (A.P.)
| | - Nicole Y. T. Tan
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
| | - Farihah Khan
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
| | - Rhys Richards
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
| | - Thibana Thisainathan
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
| | - Patricia Goggin
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, Southampton SO16 6YD, UK; (D.S.C.); (P.G.); (A.P.)
| | - Anton Page
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, Southampton SO16 6YD, UK; (D.S.C.); (P.G.); (A.P.)
| | - David A. Tumbarello
- Biological Sciences, Faculty of Environmental and Life Sciences, Life Sciences Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK;
| | - Andrew J. Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK
| | - J. Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (E.K.); (N.Y.T.T.); (F.K.); (R.R.); (T.T.); (A.J.L.)
- Correspondence: ; Tel.: +44-238120-8183
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15
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Patterson M, Swift SK. Residual Diploidy in Polyploid Tissues: A Cellular State with Enhanced Proliferative Capacity for Tissue Regeneration? Stem Cells Dev 2019; 28:1527-1539. [PMID: 31608782 PMCID: PMC11001963 DOI: 10.1089/scd.2019.0193] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/09/2019] [Indexed: 01/07/2023] Open
Abstract
A major objective of modern biomedical research aims to promote tissue self-regeneration after injury, obviating the need for whole organ transplantation and avoiding mortality due to organ failure. Identifying the population of cells capable of regeneration, alongside understanding the molecular mechanisms that activate that population to re-enter the cell cycle, are two important steps to advancing the field of endogenous tissue regeneration toward the clinic. In recent years, an emerging trend has been observed, whereby polyploidy of relevant parenchymal cells, arising from alternative cell cycles as part of a normal developmental process, is linked to restricted proliferative capacity of those cells. An accompanying hypothesis, therefore, is that a residual subpopulation of diploid parenchymal cells retains proliferative competence and is the major driver for any detected postnatal cell turnover. In this perspective review, we examine the emerging literature on residual diploid parenchymal cells and the possible link of this population to endogenous tissue regeneration, in the context of both heart and liver. We speculate on additional cell types that may play a similar role in their respective tissues and discuss outstanding questions for the field.
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Affiliation(s)
- Michaela Patterson
- Department of Cell Biology Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Samantha K. Swift
- Department of Cell Biology Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
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16
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Ferdous S, Grossniklaus HE, Boatright JH, Nickerson JM. Characterization of LSD1 Expression Within the Murine Eye. Invest Ophthalmol Vis Sci 2019; 60:4619-4631. [PMID: 31675426 PMCID: PMC6827424 DOI: 10.1167/iovs.19-26728] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 09/23/2019] [Indexed: 01/03/2023] Open
Abstract
Purpose The purpose of this study was to extend the current understanding of endogenous lysine-specific demethylase 1 (LSD1) expression spatially and temporally in the retina. Toward that end, we determined the localization and levels of LSD1 and its substrates H3K4me1 and H3K4me2 (H3K4me1/2) within the murine eye. Methods Immunofluorescent microscopy for LSD1, H3K4me1, and H3K4me2 was conducted on murine formalin-fixed paraffin-embedded eye sections across development in addition to Western immunoblotting to assess localization and protein levels. Results Retinal LSD1 protein levels were highest at postnatal day 7 (P7), whereas its substrates H3K4me1 and H3K4me2 had equally high levels at P2 and P14. Concentrations of all three proteins gradually decreased over developmental time until reaching a basement level of ∼60% of maximum at P36. LSD1 and H3K4me1/2 were expressed uniformly in all retinal progenitor cells. By P36, there was variability in LSD1 expression in the ganglion cell layer, uniform expression in the inner nuclear layer, and dichotomous expression between photoreceptors in the outer nuclear layer. This contrasted with H3K4me1/2 expression, which remained uniform. Additionally, LSD1 was widely expressed in the lens, cornea, and retinal pigment epithelium. Conclusions Consistent with its known role in neuronal differentiation, LSD1 is highly and uniformly expressed throughout all retinal progenitor cells. Variability in LSD1 expression, particularly in photoreceptors, may be indicative of their unique transcriptomes and epigenetic patterns of rods and cones. Murine rod nuclei exhibit LSD1 expression in a ring or shell, rather than throughout the nucleus, consistent with their unique inverted chromatin organization. LSD1 has substantial expression throughout adulthood, especially in cone nuclei. By providing insight into endogenous LSD1 expression, our current findings could directly inform future studies to determine the exact role of Lsd1 in the development and maintenance of specific structures and cell types within the eye.
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Affiliation(s)
- Salma Ferdous
- Department of Ophthalmology, Emory University, Atlanta, Georgia, United States
| | | | - Jeffrey H. Boatright
- Department of Ophthalmology, Emory University, Atlanta, Georgia, United States
- Atlanta Veterans Administration Center for Visual and Neurocognitive Rehabilitation, Decatur, Georgia, United States
| | - John M. Nickerson
- Department of Ophthalmology, Emory University, Atlanta, Georgia, United States
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17
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Corredor VH, da Silva FT, Baran LCP, Ventura DF, Joselevitch C. Distribution and density of mixed-input ON bipolar cells of the goldfish (Carassius auratus) during growth. J Comp Neurol 2019; 527:903-915. [PMID: 30408167 DOI: 10.1002/cne.24579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 10/18/2018] [Accepted: 10/26/2018] [Indexed: 11/09/2022]
Abstract
Neurons are continuously produced at different rates and locations in the teleost retina. Goldfish rods are homogeneously distributed and maintain a stable density throughout growth, whereas little is known about their postsynaptic partners. We examined the distribution and density of mixed-input ON bipolar cells (ON mBCs) in 57 goldfish of various sizes by immunolabeling their retinas with an antibody against PKCα and counting PKCα-positive neurons in wholemounts. Cell densities were correlated with morphometric data for the same animals, and the spatial resolution of the ON mBC mosaic was calculated in each case. The distribution of ON mBCs is homogeneous throughout growth. For a 10-fold change in body size (i.e., from 20 to 200 mm), the total number of ON mBCs increases 2.8 times, while retinal area expands around 10 times. As a consequence, the density of ON mBCs in large fish falls to ∼1/3 of that of small animals, and intercellular spacing doubles. The eye and the lens become around three times larger from small to large fish. This causes the retinal magnification factor (and thereby the image projected onto retina) to augment by the same amount. Because the retinal magnification factor rises more than the intercellular spacing in the same animals, the spatial resolution of the ON mBC mosaic improves from 0.8 to 1.4 cycles/degree as the body size increases from 20 to 200 mm. As ON mBCs are mostly rod-driven, our results suggest that the scotopic acuity of the goldfish may improve as the animal grows.
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Affiliation(s)
- Vitor H Corredor
- Department of Experimental Psychology, University of São Paulo, São Paulo - SP, Brazil.,Graduate Program in Neurosciences and Behavior, University of São Paulo, São Paulo - SP, Brazil
| | - Flávio T da Silva
- Department of Experimental Psychology, University of São Paulo, São Paulo - SP, Brazil.,Graduate Program in Neurosciences and Behavior, University of São Paulo, São Paulo - SP, Brazil
| | - Luiz C P Baran
- Department of Experimental Psychology, University of São Paulo, São Paulo - SP, Brazil.,Graduate Program in Neurosciences and Behavior, University of São Paulo, São Paulo - SP, Brazil
| | - Dora F Ventura
- Department of Experimental Psychology, University of São Paulo, São Paulo - SP, Brazil.,Graduate Program in Neurosciences and Behavior, University of São Paulo, São Paulo - SP, Brazil
| | - Christina Joselevitch
- Department of Experimental Psychology, University of São Paulo, São Paulo - SP, Brazil.,Graduate Program in Neurosciences and Behavior, University of São Paulo, São Paulo - SP, Brazil
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18
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Korkka I, Viheriälä T, Juuti-Uusitalo K, Uusitalo-Järvinen H, Skottman H, Hyttinen J, Nymark S. Functional Voltage-Gated Calcium Channels Are Present in Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium. Stem Cells Transl Med 2018; 8:179-193. [PMID: 30394009 PMCID: PMC6344904 DOI: 10.1002/sctm.18-0026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/24/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022] Open
Abstract
Retinal pigment epithelium (RPE) performs important functions for the maintenance of photoreceptors and vision. Malfunctions within the RPE are implicated in several retinal diseases for which transplantations of stem cell‐derived RPE are promising treatment options. Their success, however, is largely dependent on the functionality of the transplanted cells. This requires correct cellular physiology, which is highly influenced by the various ion channels of RPE, including voltage‐gated Ca2+ (CaV) channels. This study investigated the localization and functionality of CaV channels in human embryonic stem cell (hESC)‐derived RPE. Whole‐cell patch‐clamp recordings from these cells revealed slowly inactivating L‐type currents comparable to freshly isolated mouse RPE. Some hESC‐RPE cells also carried fast transient T‐type resembling currents. These findings were confirmed by immunostainings from both hESC‐ and mouse RPE that showed the presence of the L‐type Ca2+ channels CaV1.2 and CaV1.3 as well as the T‐type Ca2+ channels CaV3.1 and CaV3.2. The localization of the major subtype, CaV1.3, changed during hESC‐RPE maturation co‐localizing with pericentrin to the base of the primary cilium before reaching more homogeneous membrane localization comparable to mouse RPE. Based on functional assessment, the L‐type Ca2+ channels participated in the regulation of vascular endothelial growth factor secretion as well as in the phagocytosis of photoreceptor outer segments in hESC‐RPE. Overall, this study demonstrates that a functional machinery of voltage‐gated Ca2+ channels is present in mature hESC‐RPE, which is promising for the success of transplantation therapies. stem cells translational medicine2019;8:179&15
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Affiliation(s)
- Iina Korkka
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Taina Viheriälä
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland.,Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Kati Juuti-Uusitalo
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Hannele Uusitalo-Järvinen
- Eye Centre, Tampere University Hospital, Tampere, Finland.,Faculty of Medicine and Life Sciences, Department of Ophthalmology, University of Tampere, Tampere, Finland
| | - Heli Skottman
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Jari Hyttinen
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Soile Nymark
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
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19
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Rajapakse D, Chen M, Curtis TM, Xu H. PKCζ-dependent upregulation of p27kip1 contributes to oxidative stress induced retinal pigment epithelial cell multinucleation. Aging (Albany NY) 2018; 9:2052-2068. [PMID: 29016360 PMCID: PMC5680555 DOI: 10.18632/aging.101299] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 09/28/2017] [Indexed: 01/24/2023]
Abstract
Retinal pigment epithelial (RPE) cells increase in size and multinucleate during aging. We have shown using human and mouse cell lines that oxidised photoreceptor outer segments (oxPOS)-induced cytokinesis failure is related to RPE cell multinucleation, although the underlying mechanism remains unknown. This study investigated the role of the PKC pathway in oxPOS-induced RPE multinucleation using ARPE19 cells. oxPOS treatment promoted PKC activity and upregulated the mRNA expression of PKC α, δ, ζ, ι and μ. Inhibition of PKCα with Gö6976 resulted in a 33% reduction of multinucleate ARPE19 cells, whereas inhibition of PKCζ with Gö6983 led to a 50% reduction in multinucleate ARPE19 cells. Furthermore, oxPOS treatment induced a PKCζ-dependent upregulation of the Cdk inhibitor p27kip1, its inhibition using A2CE reduced oxPOS-induced ARPE19 multinucleation. Our results suggest that oxPOS-induced ARPE19 cytokinesis failure is, at least in part, due to the upregulation of p27kip1 through activating the PKC, particularly PKCζ pathway. Targeting the PKCζ-p27kip1 signalling axis may be a novel approach to restore RPE repair capacity during aging.
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Affiliation(s)
- Dinusha Rajapakse
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT97 BL, UK
| | - Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT97 BL, UK
| | - Tim M Curtis
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT97 BL, UK
| | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT97 BL, UK
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20
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Iwai-Takekoshi L, Ramos A, Schaler A, Weinreb S, Blazeski R, Mason C. Retinal pigment epithelial integrity is compromised in the developing albino mouse retina. J Comp Neurol 2016; 524:3696-3716. [PMID: 27097562 DOI: 10.1002/cne.24025] [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: 12/23/2015] [Revised: 04/15/2016] [Accepted: 04/18/2016] [Indexed: 12/22/2022]
Abstract
In the developing murine eye, melanin synthesis in the retinal pigment epithelium (RPE) coincides with neurogenesis of retinal ganglion cells (RGCs). Disruption of pigmentation in the albino RPE is associated with delayed neurogenesis in the ventrotemporal retina, the source of ipsilateral RGCs, and a reduced ipsilateral RGC projection. To begin to unravel how melanogenesis and the RPE regulate RGC neurogenesis and cell subpopulation specification, we compared the features of albino and pigmented mouse RPE cells during the period of RGC neurogenesis (embryonic day, E, 12.5 to 18.5) when the RPE is closely apposed to developing RGC precursors. At E12.5 and E15.5, although albino and pigmented RPE cells express RPE markers Otx2 and Mitf similarly, albino RPE cells are irregularly shaped and have fewer melanosomes compared with pigmented RPE cells. The adherens junction protein P-cadherin appears loosely distributed within the albino RPE cells rather than tightly localized on the cell membrane, as in pigmented RPE. Connexin 43 (gap junction protein) is expressed in pigmented and albino RPE cells at E13.5 but at E15.5 albino RPE cells have fewer small connexin 43 puncta, and a larger fraction of phosphorylated connexin 43 at serine 368. These results suggest that the lack of pigment in the RPE results in impaired RPE cell integrity and communication via gap junctions between RPE and neural retina during RGC neurogenesis. Our findings should pave the way for further investigation of the role of RPE in regulating RGC development toward achieving proper RGC axon decussation. J. Comp. Neurol. 524:3696-3716, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lena Iwai-Takekoshi
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Anna Ramos
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Ari Schaler
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Samuel Weinreb
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Richard Blazeski
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Carol Mason
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, USA. .,Department of Neuroscience, College of Physicians and Surgeons, Columbia University, New York, New York, USA. .,Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
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21
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Starnes AC, Huisingh C, McGwin G, Sloan KR, Ablonczy Z, Smith RT, Curcio CA, Ach T. Multi-nucleate retinal pigment epithelium cells of the human macula exhibit a characteristic and highly specific distribution. Vis Neurosci 2016; 33:e001. [PMID: 26923500 PMCID: PMC4798426 DOI: 10.1017/s0952523815000310] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND The human retinal pigment epithelium (RPE) is reportedly 3% bi-nucleated. The importance to human vision of multi-nucleated (MN)-RPE cells could be clarified with more data about their distribution in central retina. METHODS Nineteen human RPE-flatmounts (9 ≤ 51 years, 10 > 80 years) were imaged at 12 locations: 3 eccentricities (fovea, perifovea, near periphery) in 4 quadrants (superior, inferior, temporal, nasal). Image stacks of lipofuscin-attributable autofluorescence and phalloidin labeled F-actin cytoskeleton were obtained using a confocal fluorescence microscope. Nuclei were devoid of autofluorescence and were marked using morphometric software. Cell areas were approximated by Voronoi regions. Mean number of nuclei per cell among eccentricity/quadrant groups and by age were compared using Poisson and binominal regression models. RESULTS A total of 11,403 RPE cells at 200 locations were analyzed: 94.66% mono-, 5.31% bi-, 0.02% tri-nucleate, and 0.01% with 5 nuclei. Age had no effect on number of nuclei. There were significant regional differences: highest frequencies of MN-cells were found at the perifovea (9.9%) and near periphery (6.8%). The fovea lacked MN-cells almost entirely. The nasal quadrant had significantly more MN-cells compared to other quadrants, at all eccentricities. CONCLUSION This study demonstrates MN-RPE cells in human macula. MN-cells may arise due to endoreplication, cell fusion, or incomplete cell division. The topography of MN-RPE cells follows the topography of photoreceptors; with near-absence at the fovea (cones only) and high frequency at perifovea (highest rod density). This distribution might reflect specific requirements of retinal metabolism or other mechanisms addressable in further studies.
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Affiliation(s)
- Austin C Starnes
- University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, AL, USA
| | - Carrie Huisingh
- University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, AL, USA
| | - Gerald McGwin
- University of Alabama at Birmingham, Department of Epidemiology, Birmingham, AL, USA
| | - Kenneth R Sloan
- University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, AL, USA
- University of Alabama at Birmingham, Department of Computer and Information Sciences, Birmingham, AL, USA
| | - Zsolt Ablonczy
- Medical University of South Carolina, Department of Ophthalmology, Charleston, SC, USA
| | - R. Theodore Smith
- New York University School of Medicine, Department of Ophthalmology, New York, NY, USA
| | - Christine A Curcio
- University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, AL, USA
| | - Thomas Ach
- University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, AL, USA
- University Hospital Würzburg, Department of Ophthalmology, Würzburg, Germany
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22
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Bennett JEM, Bair W. Refinement and Pattern Formation in Neural Circuits by the Interaction of Traveling Waves with Spike-Timing Dependent Plasticity. PLoS Comput Biol 2015; 11:e1004422. [PMID: 26308406 PMCID: PMC4550436 DOI: 10.1371/journal.pcbi.1004422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 07/02/2015] [Indexed: 12/20/2022] Open
Abstract
Traveling waves in the developing brain are a prominent source of highly correlated spiking activity that may instruct the refinement of neural circuits. A candidate mechanism for mediating such refinement is spike-timing dependent plasticity (STDP), which translates correlated activity patterns into changes in synaptic strength. To assess the potential of these phenomena to build useful structure in developing neural circuits, we examined the interaction of wave activity with STDP rules in simple, biologically plausible models of spiking neurons. We derive an expression for the synaptic strength dynamics showing that, by mapping the time dependence of STDP into spatial interactions, traveling waves can build periodic synaptic connectivity patterns into feedforward circuits with a broad class of experimentally observed STDP rules. The spatial scale of the connectivity patterns increases with wave speed and STDP time constants. We verify these results with simulations and demonstrate their robustness to likely sources of noise. We show how this pattern formation ability, which is analogous to solutions of reaction-diffusion systems that have been widely applied to biological pattern formation, can be harnessed to instruct the refinement of postsynaptic receptive fields. Our results hold for rich, complex wave patterns in two dimensions and over several orders of magnitude in wave speeds and STDP time constants, and they provide predictions that can be tested under existing experimental paradigms. Our model generalizes across brain areas and STDP rules, allowing broad application to the ubiquitous occurrence of traveling waves and to wave-like activity patterns induced by moving stimuli. In several areas of the developing brain, waves of electrical activity trace out distinct patterns across the nervous tissue. These waves are intricately involved in developmental processes that set up the structural connections of the adult brain, but it is unclear what role the wave patterns play. Here, we examine how the strength of connections in these brain areas may change by a process called spike-timing dependent plasticity, which is sensitive to the precise times at which individual neurons become electrically active. We use mathematical models and simulations to show that interactions between waves and plasticity build highly structured patterns into the connections. The results of our model are analogous to many cases of biological pattern formation seen, for example, in zebra stripes, leopard spots and seashells. An important connectivity pattern we consider is the receptive field, which determines to a large extent the specific function of a neuron. We demonstrate how pattern formation can refine the shape of a receptive field and therefore the specificity of a neuron, and explore several ways in which pattern formation may be disrupted, providing clues regarding pathologies in receptive field development. Our theory makes several predictions that may be tested using existing experimental paradigms.
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Affiliation(s)
- James E. M. Bennett
- Dept. Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Wyeth Bair
- Dept. Biological Structure, University of Washington, Seattle, Washington, United States of America
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McIlhatton MA, Murnan K, Carson D, Boivin GP, Croce CM, Groden J. Genetic Manipulation of Homologous Recombination In Vivo Attenuates Intestinal Tumorigenesis. Cancer Prev Res (Phila) 2015; 8:650-6. [PMID: 25908507 DOI: 10.1158/1940-6207.capr-15-0001-t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/07/2015] [Indexed: 11/16/2022]
Abstract
Although disruption of DNA repair capacity is unquestionably associated with cancer susceptibility in humans and model organisms, it remains unclear if the inherent tumor phenotypes of DNA repair deficiency syndromes can be regulated by manipulating DNA repair pathways. Loss-of-function mutations in BLM, a member of the RecQ helicase family, cause Bloom's syndrome (BS), a rare, recessive genetic disorder that predisposes to many types of cancer. BLM functions in many aspects of DNA homeostasis, including the suppression of homologous recombination (HR) in somatic cells. We investigated whether BLM overexpression, in contrast with loss-of-function mutations, attenuated the intestinal tumor phenotypes of Apc(Min/+) and Apc(Min/+);Msh2(-/-) mice, animal models of familial adenomatous polyposis coli (FAP). We constructed a transgenic mouse line expressing human BLM (BLM-Tg) and crossed it onto both backgrounds. BLM-Tg decreased adenoma incidence in a dose-dependent manner in our Apc(Min/) (+) model of FAP, although levels of GIN were unaffected and concomitantly increased animal survival over 50%. It did not reduce intestinal tumorigenesis in Apc(Min/) (+);Msh2(-/-) mice. We used the pink-eyed unstable (p(un)) mouse model to demonstrate that increasing BLM dosage in vivo lowered endogenous levels of HR by 2-fold. Our data suggest that attenuation of the Min phenotype is achieved through a direct effect of BLM-Tg on the HR repair pathway. These findings demonstrate that HR can be manipulated in vivo to modulate tumor formation at the organismal level. Our data suggest that lowering HR frequencies may have positive therapeutic outcomes in the context of specific hereditary cancer predisposition syndromes, exemplified by FAP.
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Affiliation(s)
- Michael A McIlhatton
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio.
| | - Kevin Murnan
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio
| | - Daniel Carson
- Clermont College, University of Cincinnati, Batavia, Ohio
| | - Gregory P Boivin
- Department of Pathology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio
| | - Carlo M Croce
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio
| | - Joanna Groden
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio
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Venters SJ, Mikawa T, Hyer J. Early divergence of central and peripheral neural retina precursors during vertebrate eye development. Dev Dyn 2014; 244:266-76. [PMID: 25329498 DOI: 10.1002/dvdy.24218] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/07/2014] [Accepted: 10/12/2014] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND During development of the vertebrate eye, optic tissue is progressively compartmentalized into functionally distinct tissues. From the central to the peripheral optic cup, the original optic neuroepithelial tissue compartmentalizes, forming retina, ciliary body, and iris. The retina can be further sub-divided into peripheral and central compartments, where the central domain is specialized for higher visual acuity, having a higher ratio and density of cone photoreceptors in most species. RESULTS Classically, models depict a segregation of the early optic cup into only two domains, neural and non-neural. Recent studies, however, uncovered discrete precursors for central and peripheral retina in the optic vesicle, indicating that the neural retina cannot be considered as a single unit with homogeneous specification and development. Instead, central and peripheral retina may be subject to distinct developmental pathways that underlie their specialization. CONCLUSIONS This review focuses on lineage relationships in the retina and revisits the historical context for segregation of central and peripheral retina precursors before overt eye morphogenesis.
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Affiliation(s)
- Sara J Venters
- Cardiovascular Research Institute, University of California, San Francisco, California; Department of Neurosurgery, University of California, San Francisco San Francisco, California
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25
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Abstract
Ocular injection (intravitreal, subretinal, or into the anterior space) is an efficient approach to deliver many classes of drugs, cells, and other treatments to various cell types of the eye. In particular, subretinal injection is efficient since delivered agents accumulate as there is no dilution due to transport processes or diffusion and the volume of the interphotoreceptor space (IPS) is minimal (10-20 μl in the human eye, less than 1 μl in the mouse eye). We previously reported methods using subretinal injection and electroporation to deliver DNA to photoreceptor and retinal pigment epithelium cells in retinas of live mice (Johnson et al., 14:2211-2226; Nickerson et al. 884:53-69, 2012; Andrieu-Soler et al. 13:692-706, 2007). Here we detail further optimization of that approach and additionally report its use in delivering DNA expression plasmids to the corneal endothelium.
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Analysis of mouse RPE sheet morphology gives discriminatory categories. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:601-7. [PMID: 24664749 PMCID: PMC4083704 DOI: 10.1007/978-1-4614-3209-8_76] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We are interested in developing quantitative tools to study retinal pigmented epithelium (RPE) morphology. We want to detect changes in the RPE by strain, disease, genotype, and age. Ultimately these tools should be useful in predicting retinal disease progression. The morphometric data will also help us to understand RPE sheet formation and barrier functions. A clear disruption of the regular cell size and shape appeared in mouse mutants. Aspect ratio and cell area together gave rise to principal components that predicted age and genotype accurately and well before visually obvious damage could be seen.
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Jiang Y, Qi X, Chrenek MA, Gardner C, Boatright JH, Grossniklaus HE, Nickerson JM. Functional principal component analysis reveals discriminating categories of retinal pigment epithelial morphology in mice. Invest Ophthalmol Vis Sci 2013; 54:7274-83. [PMID: 24114543 DOI: 10.1167/iovs.13-12450] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To determine whether multivariate, functional principal component analysis of the size and shape of retinal pigment epithelial (RPE) cell morphology allows discrimination of mouse RPE genotypes and age. METHODS Flatmounts of RPE sheets obtained from C57BL/6J (n = 50) and rd10 (n = 61) mice at postnatal days 30 to 720 were stained for zonula occludens-1 (ZO-1) and imaged with confocal microscopy. A total of 111 flatmounts were prepared. Twenty-one morphometric measurements were made on tiled, composite images of complete flatmounts, including cell location, area, and eccentricity, using automated image analysis software for quantitatively measuring cell phenotypes. RESULTS In young (≤61-day-old) C57BL/6J mice, the RPE morphology resembled a regular hexagonal array of cells of uniform size throughout the retina, except near the ciliary body, where the shapes of RPE resembled a soft network. Old (≥180-day-old) C57BL/6J eyes had a subpopulation of large cells. A clear disruption of the regular cell size and shape appeared in rd10 mutants. Aspect ratio and cell area gave rise to principal components that predictively classified mouse age and genotype. CONCLUSIONS Quantitative differences in the RPE sheet morphology allowed discrimination of rd10 from C57BL/6J strains despite the confounding effect of aging. This has implications for RPE sheet morphology as a potential early biomarker for diagnosis of eye disease and prognosis of the eye at early stages when disease is subtle. We conclude that an RPE cell's area and aspect ratio are very early quantitative indicators that predict progression to advanced RPE disease as manifested in rd10.
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Affiliation(s)
- Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia
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Fuhrmann S, Zou C, Levine EM. Retinal pigment epithelium development, plasticity, and tissue homeostasis. Exp Eye Res 2013; 123:141-50. [PMID: 24060344 DOI: 10.1016/j.exer.2013.09.003] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/05/2013] [Accepted: 09/07/2013] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium (RPE) is a simple epithelium interposed between the neural retina and the choroid. Although only 1 cell-layer in thickness, the RPE is a virtual workhorse, acting in several capacities that are essential for visual function and preserving the structural and physiological integrities of neighboring tissues. Defects in RPE function, whether through chronic dysfunction or age-related decline, are associated with retinal degenerative diseases including age-related macular degeneration. As such, investigations are focused on developing techniques to replace RPE through stem cell-based methods, motivated primarily because of the seemingly limited regeneration or self-repair properties of mature RPE. Despite this, RPE cells have an unusual capacity to transdifferentiate into various cell types, with the particular fate choices being highly context-dependent. In this review, we describe recent findings elucidating the mechanisms and steps of RPE development and propose a developmental framework for understanding the apparent contradiction in the capacity for low self-repair versus high transdifferentiation.
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Affiliation(s)
- Sabine Fuhrmann
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
| | - ChangJiang Zou
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
| | - Edward M Levine
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
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Karia B, Martinez JA, Bishop AJR. Induction of homologous recombination following in utero exposure to DNA-damaging agents. DNA Repair (Amst) 2013; 12:912-21. [PMID: 24029142 DOI: 10.1016/j.dnarep.2013.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/06/2013] [Accepted: 08/19/2013] [Indexed: 11/19/2022]
Abstract
Much of our understanding of homologous recombination, as well as the development of the working models for these processes, has been derived from extensive work in model organisms, such as yeast and fruit flies, and mammalian systems by studying the repair of induced double strand breaks or repair following exposure to genotoxic agents in vitro. We therefore set out to expand this in vitro work to ask whether DNA-damaging agents with varying modes of action could induce somatic change in an in vivo mouse model of homologous recombination. We exposed pregnant dams to DNA-damaging agents, conferring a variety of lesions at a specific time in embryo development. To monitor homologous recombination frequency, we used the well-established retinal pigment epithelium pink-eyed unstable assay. Homologous recombination resulting in the deletion of a duplicated 70 kb fragment in the coding region of the Oca2 gene renders this gene functional and can be visualized as a pigmented eyespot in the retinal pigment epithelium. We observed an increased frequency of pigmented eyespots in resultant litters following exposure to cisplatin, methyl methanesulfonate, ethyl methanesulfonate, 3-aminobenzamide, bleomycin, and etoposide with a contrasting decrease in the frequency of detectable reversion events following camptothecin and hydroxyurea exposure. The somatic genomic rearrangements that result from such a wide variety of differently acting damaging agents implies long-term potential effects from even short-term in utero exposures.
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Affiliation(s)
- Bijal Karia
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA; Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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30
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Jawad S, Liu B, Li Z, Katamay R, Campos M, Wei L, Sen HN, Ling D, Martinez Estrada F, Amaral J, Chan CC, Fariss R, Gordon S, Nussenblatt RB. The role of macrophage class a scavenger receptors in a laser-induced murine choroidal neovascularization model. Invest Ophthalmol Vis Sci 2013; 54:5959-70. [PMID: 23927892 DOI: 10.1167/iovs.12-11380] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Laser-induced choroidal neovascularization (CNV) is a widely used model to mimic many features of CNV resulting from wet AMD. Macrophages have been implicated in the pathogenesis of AMD. Class A scavenger receptors, scavenger receptor-A (SR-A) and macrophage receptor with collagenous domain (MARCO), are expressed on macrophages and are associated with macrophage function. The goal of this study is to examine the role of macrophage scavenger receptors in immune cell recruitment and the formation of CNV. METHODS Laser photocoagulation was performed in wild-type and knockout mice with deletion of SR-A (SR-A(-/-)), MARCO (MARCO(-/-)), or both SR-A and MARCO double knockout (DKO). Immune cell recruitment at different time points and CNV lesions at 14 days after laser treatment were evaluated through immunostaining and confocal microscopy. Microarray analysis was performed in eyes 1 day after laser injury. RESULTS Wild-type eyes showed higher chemokine/receptor expression compared with knockout eyes after laser injury. Scavenger receptor deficiency markedly impaired the recruitment of neutrophils and macrophages to CNV lesions at 1- and 3-days post laser injury, respectively. Significantly reduced CNV volumes were found in the eyes from scavenger receptor knockout mice compared with wild-type mice. CONCLUSIONS The deficiency of scavenger receptors impairs the formation of CNV and immune cell recruitment. Our findings suggest a potential role for scavenger receptors in contributing to CNV formation and inflammation in AMD.
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Affiliation(s)
- Shayma Jawad
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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Nickerson JM, Goodman P, Chrenek MA, Bernal CJ, Berglin L, Redmond TM, Boatright JH. Subretinal delivery and electroporation in pigmented and nonpigmented adult mouse eyes. Methods Mol Biol 2012; 884:53-69. [PMID: 22688698 DOI: 10.1007/978-1-61779-848-1_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Subretinal injection offers one of the best ways to deliver many classes of drugs, reagents, cells and treatments to the photoreceptor, Müller, and retinal pigment epithelium (RPE) cells of the retina. Agents delivered to this space are placed within microns of the intended target cell, accumulating to high concentrations because there is no dilution due to transport processes or diffusion. Dilution in the interphotoreceptor space (IPS) is minimal because the IPS volume is only 10-20 μl in the human eye and less than 1 μl in the mouse eye. For gene delivery purposes, we wished to transfect the cells adjacent to the IPS in adult mouse eyes. Others transfect these cells in neonatal rats to study the development of the retina. In both neonates and adults, electroporation is found to be effective. Here we describe the optimization of electroporation conditions for RPE cells in the adult mouse eye with naked plasmids. However, both techniques, subretinal injection and electroporation, present some technical challenges that require skill on the part of the surgeon to prevent untoward damage to the eye. Here we describe methods that we have used for the past 10 years (Johnson et al. Mol Vis 14: 2211-2226, 2008).
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Affiliation(s)
- John M Nickerson
- Department of Ophthalmology, Emory University, Atlanta, GA, USA.
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Chang SP, Mullins JJ, Morley SD, West JD. Transition from organogenesis to stem cell maintenance in the mouse adrenal cortex. Organogenesis 2011; 7:267-80. [PMID: 22198434 PMCID: PMC3265829 DOI: 10.4161/org.7.4.18060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 09/12/2011] [Accepted: 09/13/2011] [Indexed: 11/19/2022] Open
Abstract
Mice showing mosaic expression of an appropriate marker gene that is activated during development provide simple tools for investigating cell lineages. We used the mosaic β-galactosidase staining patterns in adrenal cortices of 21OH/ LacZ transgenic mice to study both organogenesis and maintenance of the adult tissue. Randomly orientated mosaic patterns present in embryonic day 14.5 (E14.5) adrenals changed progressively during the perinatal period from discrete spots, via patches and radial arrays, to radial stripes, which first emerged between postnatal days 0 and 7 (P0 and P7). The mosaic radial stripe pattern was fully established by P21 and remained unchanged throughout the adult period (8-52 weeks). The mouse adrenal gland grew continuously between E14.5 and P21, including the period during which stripes emerge. Ki67-positive, proliferative cells in the adrenal cortex were mainly localized to the outer cell layers between E18.5 and P3. By P10, cell proliferation had increased, and the proliferative region had expanded but was still mainly confined to the outer cortex. Correlation of changes in mosaic patterns in 21OH/LacZ adrenal cortices with the locations of adrenocortical cell proliferation suggest that the radial stripes arise by edge-biased growth during the perinatal period, even if they are maintained by stem cells in adults. The stability of the adult stripe pattern suggests that stem cell function is unchanged between 8 and 52 weeks.
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Affiliation(s)
- Su-Ping Chang
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, UK
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Hodson BA, Unbekandt M, Keighren MA, Springbett A, West JD. Evaluation of methods for one-dimensional spatial analysis of two-dimensional patterns in mouse chimaeras. J Anat 2011; 219:418-37. [PMID: 21615733 PMCID: PMC3171778 DOI: 10.1111/j.1469-7580.2011.01395.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2011] [Indexed: 11/29/2022] Open
Abstract
The relative extent of cell mixing in tissues of mouse chimaeras or mosaics can be studied by comparing the distributions of the two cell populations in the tissues. However, the mean patch size is misleading because it is affected by both the extent of cell mixing and the relative contributions of the two cell populations. Previous work suggested that effects attributable to differences in tissue composition among chimaeras can be factored out either by correcting the mean patch size or by using the median patch size for the minority cell population and restricting the analysis to grossly unbalanced chimaeras. In the present study, computer simulations of two-dimensional mosaic arrays of black and white squares (representing cells) were used to simulate chimaeric tissues. Random arrays simulated tissues with extensive cell mixing, arrays of cell clumps (representing coherent clones) simulated less mixed tissues, and striped arrays simulated tissues with elongated but fragmented descendent clones. The computer simulations predicted that (i) the median patch length (minority cell population) and the corrected mean patch length would both distinguish between random and clumped patterns and (ii) differences in the variation of the composition of two perpendicular series of one-dimensional transects would distinguished between stripes and randomly orientated patches. Both predictions were confirmed by analysis of histological sections of the retinal pigment epithelium from fetal and adult mouse chimaeras. This study demonstrates that two types of non-random two-dimensional variegated patterns (clumps and stripes) can be identified in chimaeras without two-dimensional reconstruction of serial sections.
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Affiliation(s)
- Benjamin A Hodson
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, George Square, Edinburgh, UK
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Claybon A, Bishop AJR. Dissection of a mouse eye for a whole mount of the retinal pigment epithelium. J Vis Exp 2011:2563. [PMID: 21403630 DOI: 10.3791/2563] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and cones). The RPE is a monolayer of pigmented cuboidal cells and associates closely with the neural retina just above it. This association makes the RPE of great interest to researchers studying retinal diseases. The RPE is also the site of an in vivo assay of homology-directed DNA repair, the p(un )assay. The mouse eye is particularly difficult to dissect due to its small size (about 3.5mm in diameter) and its spherical shape. This article demonstrates in detail a procedure for dissection of the eye resulting in a whole mount of the RPE. In this procedure, we show how to work with, rather than against, the spherical structure of the eye. Briefly, the connective tissue, muscle, and optic nerve are removed from the back of the eye. Then, the cornea and lens are removed. Next, strategic cuts are made that result in significant flattening of the remaining tissue. Finally, the neural retina is gently lifted off, revealing an intact RPE, which is still attached to the underlying choroid and sclera. This whole mount can be used to perform the p(un) assay or for immunohistochemistry or immunofluorescent assessment of the RPE tissue.
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Affiliation(s)
- Alison Claybon
- UT Health Science Center at San Antonio, Greehey Children's Cancer Research Institute, USA
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The effects of a CD81 null mutation on retinal pigment epithelium in mice. Neurochem Res 2010; 36:569-73. [PMID: 20882409 DOI: 10.1007/s11064-010-0268-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2010] [Indexed: 10/19/2022]
Abstract
The present study examines the effects of Cd81-null mutation on the development of the retinal pigment epithelium (RPE), specifically cell size and number of cells with multiple nuclei. The outlines of RPE in retinal flat mounts were stained with rhodamine-labeled phalloidin and RPE nuclei with Hoechst stain. The RPE layer was sampled to define the number of cells, the size of the RPE cells and the number of nuclei within the cells. The Cd81-null mutation caused an increase in the number of cells within the RPE layer. The cells were smaller than those in the wild type mice. Furthermore there was an increase in the number of mono-nucleated cells. In the posterior portion of the eye there was a significant increase in the number of multi-nucleated cells. The data indicate that CD81 plays a significant role in the final stages of RPE development, controlling cell number and overall developmental pattern.
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Schouwey K, Aydin IT, Radtke F, Beermann F. RBP-Jκ-dependent Notch signaling enhances retinal pigment epithelial cell proliferation in transgenic mice. Oncogene 2010; 30:313-22. [DOI: 10.1038/onc.2010.428] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Brown AD, Claybon AB, Bishop AJR. Mouse WRN Helicase Domain Is Not Required for Spontaneous Homologous Recombination-Mediated DNA Deletion. J Nucleic Acids 2010; 2010. [PMID: 20847942 PMCID: PMC2933912 DOI: 10.4061/2010/356917] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2010] [Accepted: 07/07/2010] [Indexed: 12/22/2022] Open
Abstract
Werner syndrome is a rare disorder that manifests as premature aging and age-related diseases. WRN is the gene mutated in WS, and is one of five human RecQ helicase family members. WS cells exhibit genomic instability and altered proliferation, and in vitro studies suggest that WRN has a role in suppressing homologous recombination. However, more recent studies propose that other RecQ helicases (including WRN) promote early events of homologous recombination. To study the role of WRN helicase on spontaneous homologous recombination, we obtained a mouse with a deleted WRN helicase domain and combined it with the in vivo pink-eyed unstable homologous recombination system. In this paper, we demonstrate that WRN helicase is not necessary for suppressing homologous recombination in vivo contrary to previous reports using a similar mouse model.
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Affiliation(s)
- Adam D Brown
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Claybon A, Karia B, Bruce C, Bishop AJR. PARP1 suppresses homologous recombination events in mice in vivo. Nucleic Acids Res 2010; 38:7538-45. [PMID: 20660013 PMCID: PMC2995050 DOI: 10.1093/nar/gkq624] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Recent studies suggest that PARP1 inhibitors, several of which are currently in clinical trial, may selectively kill BRCA1/2 mutant cancers cells. It is thought that the success of this therapy is based on immitigable lethal DNA damage in the cancer cells resultant from the concurrent loss or inhibition of two DNA damage repair pathways: single-strand break (SSB) repair and homologous recombination repair (HRR). Presumably, inhibition of PARP1 activity obstructs the repair of SSBs and during DNA replication, these lesions cause replication fork collapse and are transformed into substrates for HRR. In fact, several previous studies have indicated a hyper-recombinogenic phenotype in the absence of active PARP1 in vitro or in response to DNA damaging agents. In this study, we demonstrate an increased frequency of spontaneous HRR in vivo in the absence of PARP1 using the pun assay. Furthermore, we found that the HRR events that occur in Parp1 nullizygous mice are associated with a significant increase in large, clonal events, as opposed to the usually more frequent single cell events, suggesting an effect in replicating cells. In conclusion, our data demonstrates that PARP1 inhibits spontaneous HRR events, and supports the model of DNA replication transformation of SSBs into HRR substrates.
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Affiliation(s)
- Alison Claybon
- Greehey Children's Cancer Research Institute, Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Held under arrest: Many mature albino RPE cells display polyploidal features consistent with abnormal cell cycle retention. Exp Eye Res 2009; 90:368-72. [PMID: 19833124 DOI: 10.1016/j.exer.2009.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 09/23/2009] [Accepted: 10/07/2009] [Indexed: 11/21/2022]
Abstract
A population of peripheral retinal pigment epithelium (RPE) cells in mature pigmented rats are retained in the cell cycle and divide, as determined by Ki67 and BrdU labeling. Their cell cycle rate is approximately 5 days. Ten times as many Ki67 positive cells are found in albinos compared with pigmented animals, but it is not known if they actually divide or only express cell cycle markers. In spite of the increased number of cells expressing cell cycle markers, we show here using BrdU, that levels of cell division in albino RPE are similar to those in pigmented animals and have a similar cell cycle rate. Hence, cell cycle activity does not progress through to cell division in the majority of albino RPE cells. Peripheral RPE cells in albinos are different from those in pigmented animals. Many have very large distorted or highly fragmented nuclei. These data along with patterns of Ki67 and BrdU labeling are consistent with such cells being retained abnormally in the cell cycle, replicating their DNA, but not able to progress through to full cell division. Hence, there are two populations of RPE cells in albinos, those undergoing normal cell division and those that appear to be arrested in the cell cycle. These abnormalities are present from early postnatal stages.
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40
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Lopes VS, Wasmeier C, Seabra MC, Futter CE. Melanosome maturation defect in Rab38-deficient retinal pigment epithelium results in instability of immature melanosomes during transient melanogenesis. Mol Biol Cell 2007; 18:3914-27. [PMID: 17671165 PMCID: PMC1995718 DOI: 10.1091/mbc.e07-03-0268] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pathways of melanosome biogenesis in retinal pigment epithelial (RPE) cells have received less attention than those of skin melanocytes. Although the bulk of melanin synthesis in RPE cells occurs embryonically, it is not clear whether adult RPE cells continue to produce melanosomes. Here, we show that progression from pmel17-positive premelanosomes to tyrosinase-positive mature melanosomes in the RPE is largely complete before birth. Loss of functional Rab38 in the "chocolate" (cht) mouse causes dramatically reduced numbers of melanosomes in adult RPE, in contrast to the mild phenotype previously shown in skin melanocytes. Choroidal melanocytes in cht mice also have reduced melanosome numbers, but a continuing low level of melanosome biogenesis gradually overcomes the defect, unlike in the RPE. Partial compensation by Rab32 that occurs in skin melanocytes is less effective in the RPE, presumably because of the short time window for melanosome biogenesis. In cht RPE, premelanosomes form but delivery of tyrosinase is impaired. Premelanosomes that fail to deposit melanin are unstable in both cht and tyrosinase-deficient RPE. Together with the high levels of cathepsin D in immature melanosomes of the RPE, our results suggest that melanin deposition may protect the maturing melanosome from the activity of lumenal acid hydrolases.
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Affiliation(s)
- Vanda S. Lopes
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Christina Wasmeier
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Miguel C. Seabra
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Clare E. Futter
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
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Bharti K, Nguyen MTT, Skuntz S, Bertuzzi S, Arnheiter H. The other pigment cell: specification and development of the pigmented epithelium of the vertebrate eye. ACTA ACUST UNITED AC 2006; 19:380-94. [PMID: 16965267 PMCID: PMC1564434 DOI: 10.1111/j.1600-0749.2006.00318.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vertebrate retinal pigment epithelium (RPE) cells are derived from the multipotent optic neuroepithelium, develop in close proximity to the retina, and are indispensible for eye organogenesis and vision. Recent advances in our understanding of RPE development provide evidence for how critical signaling factors operating in dorso-ventral and distal-proximal gradients interact with key transcription factors to specify three distinct domains in the budding optic neuroepithelium: the distal future retina, the proximal future optic stalk/optic nerve, and the dorsal future RPE. Concomitantly with domain specification, the eye primordium progresses from a vesicle to a cup, RPE pigmentation extends towards the ventral side, and the future ciliary body and iris form from the margin zone between RPE and retina. While much has been learned about the molecular networks controlling RPE cell specification, key questions concerning the cell proliferative parameters in RPE and the subsequent morphogenetic events still need to be addressed in greater detail.
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Affiliation(s)
- Kapil Bharti
- Mammalian Development Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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42
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Fisher JC, Bodenstein L. Computer simulation analysis of normal and abnormal development of the mammalian diaphragm. Theor Biol Med Model 2006; 3:9. [PMID: 16483386 PMCID: PMC1434728 DOI: 10.1186/1742-4682-3-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 02/17/2006] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Congenital diaphragmatic hernia (CDH) is a birth defect with significant morbidity and mortality. Knowledge of diaphragm morphogenesis and the aberrations leading to CDH is limited. Although classical embryologists described the diaphragm as arising from the septum transversum, pleuroperitoneal folds (PPF), esophageal mesentery and body wall, animal studies suggest that the PPF is the major, if not sole, contributor to the muscular diaphragm. Recently, a posterior defect in the PPF has been identified when the teratogen nitrofen is used to induce CDH in fetal rodents. We describe use of a cell-based computer modeling system (Nudge++) to study diaphragm morphogenesis. METHODS AND RESULTS Key diaphragmatic structures were digitized from transverse serial sections of paraffin-embedded mouse embryos at embryonic days 11.5 and 13. Structure boundaries and simulated cells were combined in the Nudge++ software. Model cells were assigned putative behavioral programs, and these programs were progressively modified to produce a diaphragm consistent with the observed anatomy in rodents. Homology between our model and recent anatomical observations occurred under the following simulation conditions: (1) cell mitoses are restricted to the edge of growing tissue; (2) cells near the chest wall remain mitotically active; (3) mitotically active non-edge cells migrate toward the chest wall; and (4) movement direction depends on clonal differentiation between anterior and posterior PPF cells. CONCLUSION With the PPF as the sole source of mitotic cells, an early defect in the PPF evolves into a posteromedial diaphragm defect, similar to that of the rodent nitrofen CDH model. A posterolateral defect, as occurs in human CDH, would be more readily recreated by invoking other cellular contributions. Our results suggest that recent reports of PPF-dominated diaphragm morphogenesis in the rodent may not be strictly applicable to man. The ability to recreate a CDH defect using a combination of experimental data and testable hypotheses gives impetus to simulation modeling as an adjunct to experimental analysis of diaphragm morphogenesis.
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Affiliation(s)
- Jason C Fisher
- Division of Pediatric Surgery, Morgan Stanley Children's Hospital of New York-Presbyterian and Department of Surgery, College of Physicians and Surgeons, Columbia University, 3959 Broadway, 216B, New York, NY 10032, USA
| | - Lawrence Bodenstein
- Division of Pediatric Surgery, Morgan Stanley Children's Hospital of New York-Presbyterian and Department of Surgery, College of Physicians and Surgeons, Columbia University, 3959 Broadway, 216B, New York, NY 10032, USA
- Olana Technologies, Inc., 5424 Arlington Avenue, H51, Bronx, NY 10471, USA
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Bishop AJR, Kosaras B, Hollander MC, Fornace A, Sidman RL, Schiestl RH. p21 controls patterning but not homologous recombination in RPE development. DNA Repair (Amst) 2006; 5:111-20. [PMID: 16202662 DOI: 10.1016/j.dnarep.2005.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 08/10/2005] [Accepted: 08/17/2005] [Indexed: 12/27/2022]
Abstract
p21/WAF1/CIP1/MDA6 is a key cell cycle regulator. Cell cycle regulation is an important part of development, differentiation, DNA repair and apoptosis. Following DNA damage, p53 dependent expression of p21 results in a rapid cell cycle arrest. p21 also appears to be important for the development of melanocytes, promoting their differentiation and melanogenesis. Here, we examine the effect of p21 deficiency on the development of another pigmented tissue, the retinal pigment epithelium. The murine mutation pink-eyed unstable (p(un)) spontaneously reverts to a wild-type allele by homologous recombination. In a retinal pigment epithelium cell this results in pigmentation, which can be observed in the adult eye. The clonal expansion of such cells during development has provided insight into the pattern of retinal pigment epithelium development. In contrast to previous results with Atm, p53 and Gadd45, p(un) reversion events in p21 deficient mice did not show any significant change. These results suggest that p21 does not play any role in maintaining overall genomic stability by regulating homologous recombination frequencies during development. However, the absence of p21 caused a distinct change in the positions of the reversion events within the retinal pigment epithelium. Those events that would normally arrest to produce single cell events continued to proliferate uncovering a cell cycle dysregulation phenotype. It is likely that p21 is involved in controlling the developmental pattern of the retinal pigment. We also found a C57BL/6J specific p21 dependent ocular defect in retinal folding, similar to those reported in the absence of p53.
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Affiliation(s)
- A J R Bishop
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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Inoue T, Kagawa T, Fukushima M, Shimizu T, Yoshinaga Y, Takada S, Tanihara H, Taga T. Activation of canonical Wnt pathway promotes proliferation of retinal stem cells derived from adult mouse ciliary margin. Stem Cells 2005; 24:95-104. [PMID: 16223856 DOI: 10.1634/stemcells.2005-0124] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Adult retinal stem cells represent a possible cell source for the treatment of retinal degeneration. However, only a small number of stem cells reside in the ciliary margin. The present study aimed to promote the proliferation of adult retinal stem cells via the Wnt signaling pathway. Ciliary margin cells from 8-week-old mice were dissociated and cultured to allow sphere colony formation. Wnt3a, a glycogen synthase kinase (GSK) 3 inhibitor, fibroblast growth factor (FGF) 2, and a FGF receptor inhibitor were then applied in the culture media. The primary spheres were dissociated to prepare either monolayer or secondary sphere cultures. Wnt3a increased the size of the primary spheres and the number of Ki-67-positive proliferating cells in monolayer culture. The Wnt3a-treated primary sphere cells were capable of self-renewal and gave rise to fourfold the number of secondary spheres compared with nontreated sphere cells. These cells also retained their multilineage potential to express several retinal markers under differentiating culture conditions. The Wnt3a-treated cells showed nuclear accumulation of beta-catenin, and a GSK3 inhibitor, SB216763, mimicked the mitogenic activity of Wnt3a. The proliferative effect of SB216763 was attenuated by an FGF receptor inhibitor but was enhanced by FGF2, with Ki-67-positive cells reaching over 70% of the total cells. Wnt3a and SB216763 promoted the proliferation of retinal stem cells, and this was partly dependent on FGF2 signaling. A combination of Wnt and FGF signaling may provide a therapeutic strategy for in vitro expansion or in vivo activation of adult retinal stem cells.
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Affiliation(s)
- Toshihiro Inoue
- Department of Cell Fate Modulation, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto-city, Japan
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Lambert IB, Singer TM, Boucher SE, Douglas GR. Detailed review of transgenic rodent mutation assays. Mutat Res 2005; 590:1-280. [PMID: 16081315 DOI: 10.1016/j.mrrev.2005.04.002] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 04/04/2005] [Accepted: 04/12/2005] [Indexed: 11/17/2022]
Abstract
Induced chromosomal and gene mutations play a role in carcinogenesis and may be involved in the production of birth defects and other disease conditions. While it is widely accepted that in vivo mutation assays are more relevant to the human condition than are in vitro assays, our ability to evaluate mutagenesis in vivo in a broad range of tissues has historically been quite limited. The development of transgenic rodent (TGR) mutation models has given us the ability to detect, quantify, and sequence mutations in a range of somatic and germ cells. This document provides a comprehensive review of the TGR mutation assay literature and assesses the potential use of these assays in a regulatory context. The information is arranged as follows. (1) TGR mutagenicity models and their use for the analysis of gene and chromosomal mutation are fully described. (2) The principles underlying current OECD tests for the assessment of genotoxicity in vitro and in vivo, and also nontransgenic assays available for assessment of gene mutation, are described. (3) All available information pertaining to the conduct of TGR assays and important parameters of assay performance have been tabulated and analyzed. (4) The performance of TGR assays, both in isolation and as part of a battery of in vitro and in vivo short-term genotoxicity tests, in predicting carcinogenicity is described. (5) Recommendations are made regarding the experimental parameters for TGR assays, and the use of TGR assays in a regulatory context.
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Affiliation(s)
- Iain B Lambert
- Mutagenesis Section, Environmental Health Sciences Bureau, Healthy Environments and Consumer Safety Branch, 0803A, Health Canada, Ottawa, Ont., Canada K1A 0L2.
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Reliene R, Schiestl RH. Glutathione depletion by buthionine sulfoximine induces DNA deletions in mice. Carcinogenesis 2005; 27:240-4. [PMID: 16162646 DOI: 10.1093/carcin/bgi222] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Oxidative stress and genomic rearrangements play a role in cancer development. l-Buthionine-sulfoximine (BSO) induces oxidative stress in a cell by irreversibly inhibiting gamma-glutamylcysteine synthetase, an essential enzyme for the synthesis of glutathione (GSH). We postulated that oxidative stress induced by GSH depletion might lead to genomic rearrangements, such as DNA deletions, and that counteracting such pro-oxidant conditions by the exogenous antioxidant N-acetyl-L-cysteine (NAC), might suppress DNA deletions. Therefore, we determined the frequency of 70 kb DNA deletions and thiol levels in mouse fetuses exposed to BSO (alone or in combination with NAC) via drinking water given to female mice during gestation. BSO treatment resulted in a significantly increased frequency of DNA deletions and decreased concentrations of GSH and cysteine. An amount of 2 mM BSO treatment resulted in a 30% higher DNA deletion frequency, 45% lower GSH and 27% lower cysteine levels, when compared with the untreated control and 20 mM BSO treatment caused a 40% higher DNA deletion frequency, 70% lower GSH and 55% lower cysteine levels. In combination BSO and NAC resulted in reduced levels of GSH consistent with the effect of BSO; however, cysteine levels increased and the frequency of DNA deletions was within the normal range. Thus, NAC protected against genome rearrangements caused by GSH depletion. This study showed that lowering the concentrations of thiol antioxidants results in DNA deletions that may play a role in carcinogenesis.
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Affiliation(s)
- Ramune Reliene
- Department of Pathology, Geffen School of Medicine and School of Public Health, UCLA, Los Angeles, CA 90024, USA
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Giménez E, Lavado A, Jeffery G, Montoliu L. Regional abnormalities in retinal development are associated with local ocular hypopigmentation. J Comp Neurol 2005; 485:338-47. [PMID: 15803509 DOI: 10.1002/cne.20495] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The retinal pigment epithelium (RPE) plays a key role in regulating retinal development. The critical enzyme in pigment production is tyrosinase. Transgenic mice with a tyrosinase construct where the locus control region was deleted (YRT4) display a variegated phenotype of tyrosinase expression. Their central retina is largely pigment free, whereas more peripheral regions are heavily pigmented. We have used this model to ask whether the influence of pigmented RPE over the retina during development is fundamentally governed by local interactions or is global. Our data show that YRT4 eyes have intermediate melanin content and relatively low tyrosinase activity compared with wild-type and albino animals. Rod counts are comparable to those in pigmented mice in peripheral regions but similar to those in albinos centrally. Anterograde labelling of retinal pathways demonstrates the presence of relatively normal ipsilateral chiasmatic projection in YRT4 mice, comparable with that in pigmented animals and consistent with the peripheral pigmented origin of this pathway. Examination of cellular proliferation levels during retinal development reveals that YRT4 mice display an extended period of mitosis, similar to that found in albinos. Hence, our results show that the regulatory influence of the RPE over the developing retina depends on localized interactions between these tissues.
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Affiliation(s)
- Estela Giménez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Campus de Cantoblanco, C/Darwin 3, 28049 Madrid, Spain
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Song BK, Levy S, Geisert EE. Increased density of retinal pigment epithelium in cd81-/- mice. J Cell Biochem 2005; 92:1160-70. [PMID: 15258899 PMCID: PMC2821794 DOI: 10.1002/jcb.20145] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Our laboratories have focused on the role of the tetraspanin CD81 in the regulation of mitotic activity. Previously we have shown that antibodies directed against CD81 can block the proliferation of cultured retinal pigment epithelial (RPE) cells. The present study investigates the role of this protein by analyzing the structure of the adult retina in mice with a null mutation of cd81. Adult cd81(-/-) mice were produced by crossing two inbred strains, NIHS-BC/Tac and 129X1/SvJ, carrying the cd81 mutation as heterozygotes (+/-). Seven cd81(-/-) mice and 11 wildtype (cd81(+/+)) littermates were anesthetized and perfused with paraformaldehyde. The eyes were removed and processed for examination by light and electron microscopy. In general, the retinas of the cd81(-/-) mice appeared normal. However, upon close examination, there was an 18% increase in the number of RPE nuclei in the cd81(-/-) mice. The photoreceptor layer of the cd81(-/-) mice was significantly thinner than that of the wild-type mice, even though there was no difference in the total thickness of the retinas in the two groups of mice. At the electron microscopic level we did not observe any differences in cell-cell junctions in the retinas of the cd81(-/-) mice as compared to their wild-type littermates. These data support a role for CD81 controlling cell-cycle and the number of RPE nuclei in the mouse retina.
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Affiliation(s)
- Bong K. Song
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Shoshana Levy
- Department of Medicine, Division of Oncology, Stanford University Medical Center, Stanford, California 94305
| | - Eldon E. Geisert
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
- Correspondence to: Eldon E. Geisert, Jr., Department of Ophthalmology, University of Tennessee Health Science Center, 855 Monroe Avenue, Memphis, Tennessee 38163.
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Reliene R, Fischer E, Schiestl RH. Effect of N-acetyl cysteine on oxidative DNA damage and the frequency of DNA deletions in atm-deficient mice. Cancer Res 2004; 64:5148-53. [PMID: 15289318 DOI: 10.1158/0008-5472.can-04-0442] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ataxia telangiectasia (AT) is a hereditary human disorder resulting in a wide variety of clinical manifestations, including progressive neurodegeneration, immunodeficiency, and high incidence of lymphoid tumors. Cells from patients with AT show genetic instability, hypersensitivity to radiation, and a continuous state of oxidative stress. Oxidative stress and genetic instability, including DNA deletions, are involved in carcinogenesis. We examined the effect of dietary supplementation with the thiol-containing antioxidant N-acetyl-l-cysteine (NAC) on levels of oxidative DNA damage and the frequency of DNA deletions in Atm-deficient (AT-mutated) mice. We confirmed that Atm-deficient mice display an increased frequency of DNA deletions (Bishop et al., Cancer Res 2000;60:395). Furthermore, we found that Atm-deficient mice have significantly increased levels of 8-OH deoxyguanosine, an indication of oxidative DNA damage. Dietary supplementation with NAC significantly reduced 8-OH deoxyguanosine level and the frequency of DNA deletions in Atm-deficient mice. These levels were similar to the levels in wild-type mice. Our findings demonstrate that NAC counteracts genetic instability and suggest that genetic instability may be a consequence of oxidative stress in Atm-deficient mice.
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Affiliation(s)
- Ramune Reliene
- Department of Pathology, Geffen School of Medicine and School of Public Health, University of California-Los Angeles, 650 Charles E. Young Drive South, Los Angeles, CA 90024, USA
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Abstract
Exposure to environmental factors and genetic predisposition of an individual may lead individually or in combination to various genetic diseases including cancer. These diseases may be a consequence of genetic instability resulting in large-scale genomic rearrangements, such as DNA deletions, duplications, and translocations. This review focuses on mouse assays detecting genetic instability at endogenous loci. The frequency of DNA deletions by homologous recombination at the pink-eyed unstable (p(un)) locus is elevated in mice with mutations in ATM, Trp53, Gadd45, and WRN genes and after exposure to carcinogens. Other quantitative in vivo assays detecting loss of heterozygosity events, such as the mammalian spot assay, Dlb-1 mouse and Aprt mouse assays, are also reviewed. These in vivo test systems may predict hazardous effects of an environmental agent and/or genetic predisposition to cancer.
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Affiliation(s)
- Ramune Reliene
- Department of Pathology, David Geffen School of Medicine and School of Public Health, UCLA, 650 Charles E Young Drive South, Los Angeles, CA 90024, USA
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