Degradation of nuclear DNA by DNase II-like acid DNase in cortical fiber cells of mouse eye lens

The fiber cells of eye lens communicate directly with each other by exchanging ions, dyes and metabolites. In most tissues this type of communication (cell coupling) is mediated by gap junctions. In the lens, the fiber cells are extensively interconnected by junctions. However, lens junctions, although morphologically similar to gap junctions, differ from them in a number of structural, biochemical and immunological features. Like gap junctions, lens junctions are regions of close cell-to-cell apposition. Unlike gap junctions, however, the extracellular gap is apparently absent in lens junctions, such that their thickness is approximately 2 nm smaller than that of typical gap junctions (Fig. 1,c). In freeze-fracture replicas, the particles of control lens junctions are more loosely packed than those of typical gap junctions (Fig. 1,a) and crystallize, when exposed to uncoupling agents such as Ca++, or H+, into pseudo-hexagonal, rhombic (Fig. 1,b) and orthogonal arrays with a particle-to-particle spacing of 6.5 nm. Because of these differences, questions have been raised about the interpretation of the lens junctions as communicating junctions, in spite of the fact that they are the only junctions interlinking lens fiber cells.

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Abstract 80: Accumulation of Mitochondrial DNA in Autolysosome Causes Inflammation and Heart Failure Through Toll-Like Receptor 9 (TLR9) Signaling

Circulation Research ◽

10.1161/res.111.suppl_1.a80 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Takafumi Oka ◽

Osamu Yamaguchi ◽

Issei Komuro ◽

Kinya Otsu

Keyword(s):

Heart Failure ◽

Mitochondrial Dna ◽

Nuclear Dna ◽

Apoptotic Cell ◽

Pressure Overload ◽

Wild Type ◽

Dnase Ii ◽

Cardiac Phenotype ◽

Deficient Mice ◽

Tlr9 Signaling

Backgrounds Nuclear DNA in apoptotic cell is digested by lysosomal deoxyribonuclease II (DNase II) in macrophages. Improper DNA digestion can lead to inflammation. We previously reported that cardiac-specific DNase II-deficient mice (CKO) exhibited heart failure after transverse aortic constriction (TAC). We observed inflammatory response and DNA accumulation in autolysosome in TAC-operated CKO heart. They were considered to be mitochondrial DNA (mtDNA). In present study, we elucidated the mechanism of inflammation integrated by DNA accumulation in TAC-operated CKO hearts. Furthermore we investigated the pathogenesis of inflammation and heart failure in wild-typeTAC-operated mice. Methods & Results First, we identified the origin of accumulated DNA in lysosome. To label cardiac mtDNA, EdU (5-ethynyl 2’ deoxyuridine) were injected into mice before TAC. In TAC-operated CKO mice, EdU- and LAMP2a (lysosomal marker) or LC3 (autophagosome marker) positive deposits were observed, indicating that mtDNA accumulated in autolysosome. Then, we examined the mechanism how the mtDNA accumulation leads to inflammation. mtDNA has similarities to bacterial DNA, which contains inflammatogenic unmethylated CpG motif. TLR9, localized in the endolysosome, senses DNA with unmethylated CpG motifs. Therefore, we hypothesized that undigested mtDNA is sensed by TLR9. We administrated the inhibitory oligodeoxynucleotides against TLR9 to TAC-operated CKO mice. They attenuated the development of cardiomyopathy in CKO mice. Ablation of Tlr9 also canceled the cardiac phenotype of CKO mice. Next, we examined the involvement of DNA accumulation and TLR9 signaling in wild-type TAC-operated mice. DNase II activity was up-regulated in hypertrophied hearts, but not in failing hearts. LAMP2a- or LC3- positive DNA accumulation was observed in failing hearts. To determine the significance of TLR9 signaling pathway in the pathogenesis of heart failure, we subjected TLR9-deficient mice to TAC. They showed significant resistance to pressure-overload. TLR9-inhibitory oligodeoxynucleotides also improved the mortality in wild-type TAC-operated mice. Conclusion mtDNA-TLR9 axis is involved in inflammation in failing hearts in response to pressure overload.

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Drosophila acid DNase is a homolog of mammalian DNase II

Gene ◽

10.1016/s0378-1119(02)00819-3 ◽

2002 ◽

Vol 295 (1) ◽

pp. 61-70 ◽

Cited By ~ 8

Author(s):

Cory J. Evans ◽

John R. Merriam ◽

Renato J. Aguilera

Keyword(s):

Dnase Ii ◽

Acid Dnase

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Secreted frizzled-related protein disrupts PCP in eye lens fiber cells that have polarised primary cilia

Developmental Biology ◽

10.1016/j.ydbio.2009.11.033 ◽

2010 ◽

Vol 338 (2) ◽

pp. 193-201 ◽

Cited By ~ 34

Author(s):

Yuki Sugiyama ◽

Richard J.W. Stump ◽

Anke Nguyen ◽

Li Wen ◽

Yongjuan Chen ◽

...

Keyword(s):

Primary Cilia ◽

Eye Lens ◽

Lens Fiber ◽

Related Protein ◽

Fiber Cells

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Severe Defects in Proliferation and Differentiation of Lens Cells in Foxe3 Null Mice

Molecular and Cellular Biology ◽

10.1128/mcb.25.20.8854-8863.2005 ◽

2005 ◽

Vol 25 (20) ◽

pp. 8854-8863 ◽

Cited By ~ 54

Author(s):

Olga Medina-Martinez ◽

Isaac Brownell ◽

Felipe Amaya-Manzanares ◽

Qiyong Hu ◽

Richard R. Behringer ◽

...

Keyword(s):

Lens Epithelium ◽

Abnormal Development ◽

Distinct Region ◽

Lens Development ◽

Forkhead Transcription Factor ◽

Surface Ectoderm ◽

Dnase Ii ◽

Lens Cells ◽

Acid Dnase ◽

Normal Lens

ABSTRACT During mouse eye development, the correct formation of the lens occurs as a result of reciprocal interactions between the neuroectoderm that forms the retina and surface ectoderm that forms the lens. Although many transcription factors required for early lens development have been identified, the mechanism and genetic interactions mediated by them remain poorly understood. Foxe3 encodes a winged helix-forkhead transcription factor that is initially expressed in the developing brain and in the lens placode and later restricted exclusively to the anterior lens epithelium. Here, we show that targeted disruption of Foxe3 results in abnormal development of the eye. Cells of the anterior lens epithelium show a decreased rate of proliferation, resulting in a smaller than normal lens. The anterior lens epithelium does not properly separate from the cornea and frequently forms an unusual, multilayered tissue. Because of the abnormal differentiation, lens fiber cells do not form properly, and the morphogenesis of the lens is greatly affected. The abnormally differentiated lens cells remain irregular in shape, and the lens becomes vacuolated. The defects in lens development correlate with changes in the expression of growth and differentiation factor genes, including DNase II-like acid DNase, Prox1, p57, and PDGFα receptor. As a result of abnormal lens development, the cornea and the retina are also affected. While Foxe3 is also expressed in a distinct region of the embryonic brain, we have not observed abnormal development of the brain in Foxe3 −/− animals.

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Faculty Opinions recommendation of Secreted frizzled-related protein disrupts PCP in eye lens fiber cells that have polarised primary cilia.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.2478978.2118080 ◽

2010 ◽

Author(s):

Jeffrey Axelrod

Keyword(s):

Primary Cilia ◽

Eye Lens ◽

Lens Fiber ◽

Related Protein ◽

Fiber Cells

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Structural and immunocytochemical alterations in eye lens fiber cells from Cx46 and Cx50 knockout mice

European Journal of Cell Biology ◽

10.1016/j.ejcb.2006.03.006 ◽

2006 ◽

Vol 85 (8) ◽

pp. 729-752 ◽

Cited By ~ 21

Author(s):

Irene Dunia ◽

Christian Cibert ◽

Xiaohua Gong ◽

Chun-hong Xia ◽

Michel Recouvreur ◽

...

Keyword(s):

Knockout Mice ◽

Eye Lens ◽

Lens Fiber ◽

Fiber Cells

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Eph-ephrin Signaling Affects Eye Lens Fiber Cell Intracellular Voltage and Membrane Conductance

Frontiers in Physiology ◽

10.3389/fphys.2021.772276 ◽

2021 ◽

Vol 12 ◽

Author(s):

Catherine Cheng ◽

Junyuan Gao ◽

Xiurong Sun ◽

Richard T. Mathias

Keyword(s):

Cell Membrane ◽

Water Channel ◽

Membrane Conductance ◽

Building Blocks ◽

Fiber Cell ◽

Eye Lens ◽

Lens Fiber ◽

Fiber Cells ◽

Lens Fibers ◽

Lens Transparency

The avascular eye lens generates its own microcirculation that is required for maintaining lifelong lens transparency. The microcirculation relies on sodium ion flux, an extensive network of gap junction (GJ) plaques between lens fiber cells and transmembrane water channels. Disruption of connexin proteins, the building blocks of GJs, or aquaporins, which make up water and adhesion channels, lead to lens opacification or cataracts. Recent studies have revealed that disruption of Eph-ephrin signaling, in particular the receptor EphA2 and the ligand ephrin-A5, in humans and mice lead to congenital and age-related cataracts. We investigated whether changes in lens transparency in EphA2 or ephrin-A5 knockout (–/–) mice is related to changes in GJ coupling and lens fluid and ion homeostasis. Immunostaining revealed changes in connexin 50 (Cx50) subcellular localization in EphA2–/– peripheral lens fibers and alteration in aquaporin 0 (Aqp0) staining patterns in ephrin-A5–/– and EphA2–/– inner mature fiber cells. Surprisingly, there was no obvious change in GJ coupling in knockout lenses. However, there were changes in fiber cell membrane conductance and intracellular voltage in knockout lenses from 3-month-old mice. These knockout lenses displayed decreased conductance of mature fiber membranes and were hyperpolarized compared to control lenses. This is the first demonstration that the membrane conductance of lens fibers can be regulated. Together these data suggest that EphA2 may be needed for normal Cx50 localization to the cell membrane and that conductance of lens fiber cells requires normal Eph-ephrin signaling and water channel localization.

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Tropomyosin 3.5 protects F-actin networks required for tissue biomechanical properties

10.1101/357509 ◽

2018 ◽

Cited By ~ 1

Author(s):

Catherine Cheng ◽

Roberta B. Nowak ◽

Michael B. Amadeo ◽

Sondip K. Biswas ◽

Woo-Kuen Lo ◽

...

Keyword(s):

Mechanical Load ◽

Biomechanical Properties ◽

Tissue Mechanics ◽

Actin Binding ◽

Eye Lens ◽

Lens Fiber ◽

Load Bearing ◽

Actin Networks ◽

Fiber Cells

AbstractTropomyosins (Tpms) stabilize F-actin and regulate interactions with other actin-binding proteins. The eye lens changes shape in order to fine focus light to transmit a clear image, and thus lens organ function is tied to its biomechanical properties, presenting an opportunity to study Tpm functions in tissue mechanics. The major mouse lens Tpm is Tpm3.5 (TM5NM5), a previously unstudied isoform. Decreased levels of Tpm3.5 lead to softer and less mechanically resilient lenses that are unable to resume their original shape after compression. While cell organization and morphology appear unaffected, Tmod1 dissociates from the membrane in Tpm3.5-deficient lens fiber cells resulting in reorganization of the spectrin-F-actin and α-actinin-F-actin networks at the membrane. These rearranged F-actin networks appear to be less able to support mechanical load and resilience leading to an overall change in tissue mechanical properties. This is the firstin vivoevidence that Tpm is essential for cell biomechanical stability in a load-bearing non-muscle tissue and indicates that Tpm3.5 protects mechanically stable, load-bearing F-actinin vivo.SummaryTropomyosin 3.5 stabilizes F-actin in eye lens fiber cells and promotes normal tissue biomechanical properties. Tpm3.5 deficiency leads to F-actin network rearrangements and decreased lens stiffness and resilience.

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Developmental analysis of the eye lens obsolescence (Elo) gene in the mouse: cell proliferation and Elo gene expression in the aggregation chimera

Development ◽

10.1242/dev.113.4.1293 ◽

1991 ◽

Vol 113 (4) ◽

pp. 1293-1304 ◽

Cited By ~ 1

Author(s):

A. Yoshiki ◽

M. Hanazono ◽

S. Oda ◽

N. Wakasugi ◽

T. Sakakura ◽

...

Keyword(s):

Cell Proliferation ◽

Epithelial Cells ◽

Cell Number ◽

S Phase ◽

Lens Epithelium ◽

Posterior Region ◽

Lens Epithelial Cells ◽

Eye Lens ◽

Lens Fiber ◽

Fiber Cells

This study investigates the primary effect of the eye lens obsolescence (Elo) gene of the mouse. Morphological features of the Elo lens were defined as follows: (1) deficient elongation of lens fiber cells, (2) morphological abnormality of nuclei of lens fiber cells, (3) lack of eosinophilic granules in the central fiber cells and (4) rupture of lens capsule in the posterior region. We have immunohistologically examined, by means of an in vivo BrdU incorporation system, whether or not the Elo gene regulates cell proliferation during lens development. The lens fiber cells were morphologically abnormal in day 13 embryonic Elo lens. However, there were no significant differences in morphology or cell proliferation between normal and Elo lens epithelium until day 14 of gestation. After day 15, the total cell number in the Elo lens epithelium was significantly less than that in the normal, but the total numbers of S-phase cells in the two genotypes were not significantly different. The ratio of the total S-phase cell number to the total number of lens epithelial cells may be affected by the developmental stage, but not directly by the genotype. The genotype, however, may be having a direct influence at later ages because malformation of Elo lens fiber cells must cause reduction of the total number of lens epithelial cells in older embryos. Although, at 30 days old, Elo lens cells were externally extruded through the ruptured capsule into the vitreous cavity, BrdU-labelled lens epithelial cells were detectable. To investigate whether the Elo lens phenotype is determined by its own genotype or by its cellular environment, we produced aggregation chimeras between C3H-Elo/+(C/C) and BALB/c(c/c). Most lenses of BALB/c dominant chimeras were oval in shape without the ruptured lens capsule. However, they were opaque in the center and slightly smaller in size than normal. The lenses of C3H-Elo/+ dominant chimeras were morphologically similar to the Elo lens. Although normal nuclei were regularly arranged in the anterior region, Elo-type nuclei were located in the posterior region. Immunohistological staining by using anti-C3H strain-specific antibody demonstrated that the lens fiber cells with abnormal nuclei were derived only from C3H-Elo/+, not from BALB/c. These observations suggest that the primary effect of the Elo gene in the developing lens may be specific to the fiber cell differentiation rather than to the cell proliferation.(ABSTRACT TRUNCATED AT 400 WORDS)

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