scholarly journals A Role for Caspases in Lens Fiber Differentiation

1998 ◽  
Vol 140 (1) ◽  
pp. 153-158 ◽  
Author(s):  
Yasuki Ishizaki ◽  
Michael D. Jacobson ◽  
Martin C. Raff
Keyword(s):  
Epithelial Cells ◽  
Cysteine Proteases ◽  
Lens Epithelial Cells ◽  
Lens Fiber ◽  
Caspase Family ◽  
Vitro Model ◽  
Normal Differentiation ◽  
Enzymatic Machinery

There is increasing evidence that programmed cell death (PCD) depends on a novel family of intracellular cysteine proteases, called caspases, that includes the Ced-3 protease in the nematode Caenorhabditis elegans and the interleukin-1β–converting enzyme (ICE)-like proteases in mammals. Some developing cells, including lens epithelial cells, erythroblasts, and keratinocytes, lose their nucleus and other organelles when they terminally differentiate, but it is not known whether the enzymatic machinery of PCD is involved in any of these normal differentiation events. We show here that at least one CPP32 (caspase-3)-like member of the caspase family becomes activated when rodent lens epithelial cells terminally differentiate into anucleate lens fibers in vivo, and that a peptide inhibitor of these proteases blocks the denucleation process in an in vitro model of lens fiber differentiation. These findings suggest that at least part of the machinery of PCD is involved in lens fiber differentiation.

scholarly journals MicroRNA-26a and -26b inhibit lens fibrosis and cataract by negatively regulating Jagged-1/Notch signaling pathway

2017 ◽  
Vol 24 (8) ◽  
pp. 1431-1442 ◽  
Author(s):  
Xiaoyun Chen ◽  
Wei Xiao ◽  
Weirong Chen ◽  
Xialin Liu ◽  
Mingxing Wu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Notch Signaling ◽  
Cancer Metastasis ◽  
Epithelial Mesenchymal Transition ◽  
Notch Pathway ◽  
Lens Epithelial Cells ◽  
Mesenchymal Transition ◽  
Fibrotic Diseases

Abstract Fibrosis is a chronic process involving development and progression of multiple diseases in various organs and is responsible for almost half of all known deaths. Epithelial–mesenchymal transition (EMT) is the vital process in organ fibrosis. Lens is an elegant biological tool to investigate the fibrosis process because of its unique biological properties. Using gain- and loss-of-function assays, and different lens fibrosis models, here we demonstrated that microRNA (miR)-26a and miR-26b, members of the miR-26 family have key roles in EMT and fibrosis. They can significantly inhibit proliferation, migration, EMT of lens epithelial cells and lens fibrosis in vitro and in vivo. Interestingly, we revealed that the mechanisms of anti-EMT effects of miR-26a and -26b are via directly targeting Jagged-1 and suppressing Jagged-1/Notch signaling. Furthermore, we provided in vitro and in vivo evidence that Jagged-1/Notch signaling is activated in TGFβ2-stimulated EMT, and blockade of Notch signaling can reverse lens epithelial cells (LECs) EMT and lens fibrosis. Given the general involvement of EMT in most fibrotic diseases, cancer metastasis and recurrence, miR-26 family and Notch pathway may have therapeutic uses in treating fibrotic diseases and cancers.

Factors modulating mouse lens epithelial cell morphology with differentiation and development of a lentoid structure in vitro

Development ◽  
1987 ◽  
Vol 99 (1) ◽  
pp. 25-32
Author(s):  
A.L. Muggleton-Harris ◽  
N. Higbee
Keyword(s):  
Epithelial Cells ◽  
Collagen Gel ◽  
Cell Aggregation ◽  
Lens Epithelial Cell ◽  
Lens Capsule ◽  
Lens Epithelial Cells ◽  
Collagen Membrane ◽  
Mouse Lens

The morphological and cellular changes that occur with differentiation and development of a lentoid structure from cultured mouse lens epithelial cells have been found to be dependent on the presence of lens capsule in association with the cells. The development of the ‘lentoid body’ is a multiphase process involving cell replication, synthesis of mucosubstances and a basement collagen membrane, cell aggregation and differentiation. Stage-specific synthesis of lens proteins confirms that the genes regulating normal differentiation in vivo are operating in the in vitro system. The hydrated collagen gel studies described in this report demonstrate that the cuboidal morphology and apical-basal polarity of the lens epithelial cells are dependent on their relationship with the lens capsule. Following a replicative phase the cells assume a mesenchyme-like morphology and migrate into the gel. Trypsinized cells freed from the lens capsule replicate but form colonies on the surface of the gel. The implications of these results are discussed with respect to previous observations made on normal lens development and the abnormalities associated with the congenital cataractous embryonic lens.

scholarly journals Oxidative stress induces inflammation of lens cells and triggers immune surveillance of ocular tissues

2021 ◽  
Author(s):  
Brian Thompson ◽  
Emily A Davidson ◽  
Ying Chen ◽  
David J Orlicky ◽  
David C Thompson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Ex Vivo ◽  
Immune Surveillance ◽  
Cytokine Expression ◽  
Lens Epithelial Cells ◽  
Mesenchymal Transition ◽  
Lens Cells

Recent reports have challenged the notion that the lens is immune-privileged. However, these studies have not fully identified the molecular mechanism(s) that promote immune surveillance of the lens. Using a mouse model of targeted glutathione (GSH) deficiency in ocular surface tissues, we have investigated the role of oxidative stress in upregulating cytokine expression and promoting immune surveillance of the eye. RNA-sequencing of lenses from postnatal day (P) 1-aged Gclcf/f;Le-CreTg/- (KO) and Gclcf/f;Le-Cre-/- control (CON) mice revealed upregulation of many cytokines (e.g., CCL4, GDF15, CSF1) and immune response genes in the lenses of KO mice. The eyes of KO mice had a greater number of cells in the aqueous and vitreous humors at P1, P20 and P50 than age-matched CON and Gclcw/w;Le-CreTg/- (CRE) mice. Histological analyses revealed the presence of innate immune cells (i.e., macrophages, leukocytes) in ocular structures of the KO mice. At P20, the expression of cytokines and ROS content was higher in the lenses of KO mice than in those from age-matched CRE and CON mice, suggesting that oxidative stress may induce cytokine expression. In vitro administration of the oxidant, hydrogen peroxide, and the depletion of GSH (using buthionine sulfoximine (BSO)) in 21EM15 lens epithelial cells induced cytokine expression, an effect that was prevented by co-treatment of the cells with N-acetyl-L-cysteine (NAC), a antioxidant. The in vivo and ex vivo induction of cytokine expression by oxidative stress was associated with the expression of markers of epithelial-to-mesenchymal transition (EMT), α-SMA, in lens cells. Given that EMT of lens epithelial cells causes posterior capsule opacification (PCO), we propose that oxidative stress induces cytokine expression, EMT and the development of PCO in a positive feedback loop. Collectively these data indicate that oxidative stress induces inflammation of lens cells which promotes immune surveillance of ocular structures.

Secreted FGFR3, but not FGFR1, inhibits lens fiber differentiation

Development ◽  
2001 ◽  
Vol 128 (9) ◽  
pp. 1617-1627 ◽  
Author(s):  
V. Govindarajan ◽  
P.A. Overbeek
Keyword(s):  
Cell Differentiation ◽  
Epithelial Cells ◽  
Vitreous Humor ◽  
Fiber Cell ◽  
Marker Genes ◽  
Lens Fiber ◽  
Lens Fiber Cell ◽  
Posterior Side

The vertebrate lens has a distinct polarity with cuboidal epithelial cells on the anterior side and differentiated fiber cells on the posterior side. It has been proposed that the anterior-posterior polarity of the lens is imposed by factors present in the ocular media surrounding the lens (aqueous and vitreous humor). The differentiation factors have been hypothesized to be members of the fibroblast growth factor (FGF) family. Though FGFs have been shown to be sufficient for induction of lens differentiation both in vivo and in vitro, they have not been demonstrated to be necessary for endogenous initiation of fiber cell differentiation. To test this possibility, we have generated transgenic mice with ocular expression of secreted self-dimerizing versions of FGFR1 (FR1) and FGFR3 (FR3). Expression of FR3, but not FR1, leads to an expansion of proliferating epithelial cells from the anterior to the posterior side of the lens due to a delay in the initiation of fiber cell differentiation. This delay is most apparent postnatally and correlates with appropriate changes in expression of marker genes including p57(KIP2), Maf and Prox1. Phosphorylation of Erk1 and Erk2 was reduced in the lenses of FR3 mice compared with nontransgenic mice. Though differentiation was delayed in FR3 mice, the lens epithelial cells still retained their intrinsic ability to respond to FGF stimulation. Based on these results we propose that the initiation of lens fiber cell differentiation in mice requires FGF receptor signaling and that one of the lens differentiation signals in the vitreous humor is a ligand for FR3, and is therefore likely to be an FGF or FGF-like factor.

scholarly journals Antibodies to Tyvelose Exhibit Multiple Modes of Interference with the Epithelial Niche of Trichinella spiralis

2000 ◽  
Vol 68 (4) ◽  
pp. 1912-1918 ◽  
Author(s):  
Catherine S. McVay ◽  
Peter Bracken ◽  
Lucille F. Gagliardo ◽  
Judith Appleton
Keyword(s):  
Epithelial Cells ◽  
Trichinella Spiralis ◽  
In Vivo Studies ◽  
Parasite Development ◽  
Multiple Modes ◽  
Protective Antibodies ◽  
Sensory Reception ◽  
Vitro Model

ABSTRACT Infection with the parasitic nematode Trichinella spiralis is initiated when the L1 larva invades host intestinal epithelial cells. Monoclonal antibodies specific for glycans on the larval surface and secreted glycoproteins protect the intestine against infection. Protective antibodies recognize tyvelose which caps the target glycan. In this study, we used an in vitro model of invasion to further examine the mechanism(s) by which tyvelose-specific antibodies protect epithelial cells against T. spiralis. Using cell lines that vary in susceptibility to invasion, we confirmed and clarified the results of our in vivo studies by documenting three modes of interference: exclusion of larvae from cells, encumbrance of larvae as they migrated within epithelial monolayers, and inhibition of parasite development. Excluded larvae bear cephalic caps (C. S. McVay et al., Infect. Immun. 66:1941–1945, 1998) of immune complexes that may physically block invasion or may interfere with sensory reception. Monovalent Fab fragments prepared from a tyvelose-specific antibody also excluded larvae from cells, demonstrating that antibody binding can inhibit the parasite in the absence of antigen aggregation and cap formation. In contrast, encumbered larvae caused extensive damage to the monolayer yet were not successful in establishing a niche, as reflected by their failure to molt. These results show that antibodies to tyvelose exhibit multiple modes of inhibitory activity, further implicating tyvelose-bearing glycoproteins as mediators of invasion and niche establishment by T. spiralis.

scholarly journals Filament Tip-Associated Antigens Involved in Adherence to and Invasion of Murine Pulmonary Epithelial Cells In Vivo and HeLa Cells In Vitro by Nocardia asteroides

1998 ◽  
Vol 66 (10) ◽  
pp. 4676-4689 ◽  
Author(s):  
Blaine L. Beaman ◽  
LoVelle Beaman
Keyword(s):  
Epithelial Cells ◽  
Hela Cells ◽  
Nocardia Asteroides ◽  
Pulmonary Epithelial Cells ◽  
Pulmonary Epithelial Cell ◽  
Vitro Model ◽  
The Brain ◽  
Invasion Assays

ABSTRACT The interactions of Nocardia asteroides GUH-2 with pulmonary epithelial cells of C57BL/6 mice and with HeLa cells were studied. Electron microscopy demonstrated that only the tips of log-phase cells penetrated pulmonary epithelial cells following intranasal administration, and nocardiae were recovered from the brain. Coccobacillary cells neither invaded nor disseminated. Serum from immunized mice (IMS) decreased attachment to and penetration of pulmonary epithelial cell surfaces by log-phase GUH-2 and inhibited spread to the brain. IMS was adsorbed against stationary-phase cells. Western immunoblots suggested that this adsorbed IMS was reactive primarily with 43- and 62-kDa proteins. Immunofluorescence showed that adsorbed IMS preferentially labeled the tips of log-phase GUH-2 cells. Since this IMS was reactive to culture filtrate antigens, several of these proteins were cut from gels, and mice were immunized. Sera against 62-, 55-, 43-, 36-, 31-, and 25-kDa antigens were obtained. The antisera against the 43- and 36-kDa proteins labeled the filament tips of GUH-2 cells. Only the antiserum against the 43-kDa antigen increased pulmonary clearance, inhibited apical attachment to and penetration of pulmonary epithelial cells, and prevented spread to the brain. An in vitro model with HeLa cells demonstrated that the tips of log-phase cells of GUH-2 adhered to and penetrated the surface of HeLa cells. Invasion assays with amikacin treatment demonstrated that nocardiae were internalized. Adsorbed IMS blocked attachment to and invasion of these cells. These data suggested that a filament tip-associated 43-kDa protein was involved in attachment to and invasion of pulmonary epithelial cells and HeLa cells by N. asteroides GUH-2.

Metalloprotease-mediated cleavage secretion of pulmonary ACE by vascular endothelial and kidney epithelial cells

1996 ◽  
Vol 271 (2) ◽  
pp. H744-H751 ◽  
Author(s):  
R. Ramchandran ◽  
S. Kasturi ◽  
J. G. Douglas ◽  
I. Sen
Keyword(s):  
Epithelial Cells ◽  
Cysteine Proteases ◽  
Significant Inhibition ◽  
The Body ◽  
Rabbit Serum ◽  
Vascular Endothelial ◽  
Renal Epithelial Cells ◽  
Proximal Tubular Epithelial Cells

The pulmonary isozyme of angiotensin-converting enzyme (ACEP) is present in the body both as a cell-associated protein in endothelial, epithelial, and monocytic cells and as a soluble protein in various body fluids including serum. The mechanism by which soluble ACEP is produced in vivo is unknown. Using in vitro transfected cell culture systems, we previously demonstrated that the rabbit testicular isozyme of ACE (ACET), which shares extensive homology with ACEP, is first synthesized as a plasma membrane-anchored ectoprotein and then secreted to the culture medium by cleavage removal of its COOH-terminal membrane-anchored tail. Here, using in vitro cultures of arterial endothelial cells and acutely isolated renal epithelial cells, we demonstrate that ACEP is also cleavage secreted from their natural producer cells. Biochemical and immunological characterization of the in vitro secreted ACEP protein revealed that it is missing the COOH-terminal membrane-anchored region of the cell-associated ACEP. Similar analysis of ACEP proteins present in rabbit serum, lung, and kidney established that ACEP secretion in vivo is also caused by the cleavage removal of the COOH-terminal region of the cell-associated protein. To characterize the proteolytic enzyme responsible for ACEP secretion, we employed rabbit renal proximal tubular epithelial cells and demonstrated significant inhibition of secretion by compound 3, a hydroxamic acid-based inhibitor of specific metalloproteases. In contrast, the inhibitors of chymotrypsin, trypsin, serine, aspartate, and cysteine proteases were ineffective. These results indicate that soluble ACEP production by vascular endothelial and renal epithelial cells, both in vitro and in vivo, is achieved by cleavage removal of its membrane-anchoring COOH-terminal tail by a metalloprotease.

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