Expression of transcription factor AP-1 in rat lens epithelial cells during wound repair

Arginase-1 promotes lens epithelial-to-mesenchymal transition in different models of anterior subcapsular cataract

BACKGROUND

Arginase-1 (ARG1) promotes collagen synthesis and cell proliferation. ARG1 is highly expressed in various tumour cells. The mechanisms of ARG1 in epithelial-to-mesenchymal transition (EMT)-associated cataracts were studied herein.

METHODS

C57BL/6 mice, a human lens epithelial cell line (HLEC-SRA01/04), and human lens capsule samples were used in this study. The right lens anterior capsule of the mouse eye was punctured through the central cornea with a 26-gauge hypodermic needle. Human lens epithelial cells (HLECs) were transfected with ARG1-targeted (siARG1) or negative control siRNA (siNC). For gene overexpression, HLECs were transfected with a plasmid bearing the ARG1 coding sequence or an empty vector. Medium containing 0.2% serum with or without transforming growth factor beta-2 (TGF-β2) was added for 6 or 24 h to detect mRNA or protein, respectively. The expression of related genes was measured by quantitative real-time polymerase chain reaction (RT-qPCR), western blotting, and immunohistochemical staining. Transwell assays and wound healing assays were used to determine cell migration. Cell proliferation, superoxide levels, nitric oxide (NO) levels, and arginase activity were estimated using Cell Counting Kit-8 assays, a superoxide assay kit, an NO assay kit, and an arginase activity kit.

RESULTS

ARG1, alpha-smooth muscle actin (α-SMA), fibronectin, and Ki67 expression increased after lens capsular injury, while zonula occludens-1 (ZO-1) expression decreased. Fibronectin and collagen type I alpha1 chain (collagen 1A1) expression increased, and cell migration increased significantly in ARG1-overexpressing HLECs compared with those transfected with an empty vector after TGF-β2 treatment. These effects were reversed by ARG1 knockdown. The arginase-related pathway plays an important role in EMT. mRNAs of enzymes of the arginase-related pathway were highly expressed after ARG1 overexpression. ARG1 knockdown suppressed these expression changes. Numidargistat (CB-1158) dihydrochloride (CB-1158), an ARG1 inhibitor, suppressed TGF-β2-induced anterior subcapsular cataract (ASC) by reducing the proliferation of lens epithelial cells (LECs) and decreasing fibronectin, α-SMA, collagen 1A1, and vimentin expression. Compared with that in nonanterior subcapsular cataract (non-ASC) patients, the expression of ARG1, collagen 1A1, vimentin, fibronectin, and Ki67 was markedly increased in ASC patients.

CONCLUSIONS

ARG1 can regulate EMT in EMT-associated cataracts. Based on the pathogenesis of ASC, these findings are expected to provide new therapeutic strategies for patients.

The Immediate Early Response of Lens Epithelial Cells to Lens Injury

Cataracts are treated by lens fiber cell removal followed by intraocular lens (IOL) implantation into the lens capsule. While effective, this procedure leaves behind numerous lens epithelial cells (LECs) which undergo a wound healing response that frequently leads to posterior capsular opacification (PCO). In order to elucidate the acute response of LECs to lens fiber cell removal which models cataract surgery (post cataract surgery, PCS), RNA-seq was conducted on LECs derived from wild type mice at 0 and 6 h PCS. This analysis found that LECs upregulate the expression of numerous proinflammatory cytokines and profibrotic regulators by 6 h PCS suggesting rapid priming of pathways leading to inflammation and fibrosis PCS. LECs also highly upregulate the expression of numerous immediate early transcription factors (IETFs) by 6 h PCS and immunolocalization found elevated levels of these proteins by 3 h PCS, and this was preceded by the phosphorylation of ERK1/2 in injured LECs. Egr1 and FosB were among the highest expressed of these factors and qRT-PCR revealed that they also upregulate in explanted mouse lens epithelia suggesting potential roles in the LEC injury response. Analysis of lenses lacking either Egr1 or FosB revealed that both genes may regulate a portion of the acute LEC injury response, although neither gene was essential for expression of either proinflammatory or fibrotic markers at later times PCS suggesting that IETFs may work in concert to mediate the LEC injury response following cataract surgery.

Morphological comparison between three-dimensional structure of immortalized human lens epithelial cells and Soemmering's ring

The incidence rate of post-cataract surgery posterior capsule opacification (PCO) and lens turbidity is about 20% in 5 years. Soemmering's ring, which is a type of PCO also called a regenerated lens with similar tissue structure to that of a human lens, is an important proxy for elucidating the mechanism of lens regeneration and maintenance of transparency. The authors created new human immortalized crystalline lens epithelial cells (iHLEC-NY1s) with excellent differentiation potential, and as a result of culturing the cells by static and rotation-floating methods, succeeded in producing a three-dimensional cell structure model (3D-iHLEC-NY1s) which is similar to Soemmering's ring in tissue structure and expression characteristics of αA-crystalline, βB2-crystalline, vimentin proteins. 3D-iHLEC-NY1s is expected to be a proxy in vitro experimental model of Soemmering's ring to enable evaluation of drug effects on suppression of cell aggregate formation and transparency. By further improving the culture conditions, we aim to control the cell sequence and elucidate the mechanism underlying the maintenance of lens transparency.

Do Mast Cells Have a Role in Tendon Healing and Inflammation?

Understanding the links between the tendon healing process, inflammatory mechanisms, and tendon homeostasis/pain after tissue damage is crucial in developing novel therapeutics for human tendon disorders. The inflammatory mechanisms that are operative in response to tendon injury are not fully understood, but it has been suggested that inflammation occurring in response to nerve signaling, i.e., neurogenic inflammation, has a pathogenic role. The mechanisms driving such neurogenic inflammation are presently not clear. However, it has recently been demonstrated that mast cells present within the injured tendon can express glutamate receptors, raising the possibility that mast cells may be sensitive to glutamate signaling and thereby modulate neurogenic inflammation following tissue injury. In this review, we discuss the role of mast cells in the communication with peripheral nerves, and their emerging role in tendon healing and inflammation after injury.

Cell death and survival following manual and femtosecond laser-assisted capsulotomy in age-related cataract

AIM

To study molecular and morphological changes in lens epithelial cells following femtosecond laser-assisted and manually performed continuous curvilinear capsulotomy (CCC) in order to get information about these methods regarding their potential role in the induction of development of secondary cataract.

METHODS

Anterior lens capsules (ALC) were removed from 40 patients with age-related cataract by manual CCC and by femtosecond laser-assisted capsulotomy (FLAC). Samples removed by manual CCC were assorted in group 1, FLAC samples were classified in group 2. Morphology of lens epithelial cells was examined with light and electron microscopes. Following capsulotomy, expressions of p53, Bcl-2 and cyclin D1 genes were analyzed with reverse transcriptase polymerase chain reaction. Immunohistochemistry was used to detect the pro-apoptotic p53 in the epithelial cells.

RESULTS

Light and electron microscopic examination showed that ALC of group 1 contained more degenerating cells following manual CCC than after FLAC. The expression level of p53 was higher after manual than laser-assisted surgery. Immunocytochemistry indicated significantly higher number of cells containing p53 protein in the manual CCC group than following FLAC. Bcl-2 and cyclin D1 gene expression levels were slightly lower following manual CCC than after FLAC, but the difference was not significant.

CONCLUSION

Manually removed ALC shows slightly, but not significantly larger damage due to the mechanical stretching and pulling of the capsule than those removed using FLAC.

Bioinformatics analysis of microarray data to explore the key genes involved in HSF4 mutation-induced cataract

AIM

To reveal the mechanisms of heat-shock transcription factor 4 (HSF4) mutation-induced cataract.

METHODS

GSE22362, including 3 HSF4-null lens and 3 wild-type lens, was obtained from Gene Expression Omnibus database. After data preprocessing, the differentially expressed genes (DEGs) were identified using the limma package. Based on Database for Annotation, Visualization and Integrated Discovery (DAVID) tool, functional and pathway enrichment analyses were performed for the DEGs. Followed by protein-protein interaction (PPI) network was constructed using STRING database and Cytoscape software. Furthermore, the validated microRNA (miRNA)-DEG pairs were obtained from miRWalk2.0 database, and then miRNA-DEG regulatory network was visualized by Cytoscape software.

RESULTS

A total of 176 DEGs were identified in HSF4-null lens compared with wild-type lens. In the PPI network, FBJ osteosarcoma oncogene (FOS), early growth response 1 (EGR1) and heme oxygenase (decycling) 1 (HMOX1) had higher degrees and could interact with each other. Besides, mmu-miR-15a-5p and mmu-miR-26a-5p were among the top 10 miRNAs in the miRNA-DEG regulatory network. Additionally, mmu-miR-26a-5p could target EGR1 in the regulatory network.

CONCLUSION

FOS, EGR1, HMOX1, mmu-miR-26a-5p and mmu-miR-15a-5p might function in the pathogenesis of HSF4 mutation-induced cataract.

Lens Epithelial Apoptosis and Cell Proliferation in Human Age-Related Cortical Cataract

Purpose

To probe the presence of apoptosis in the epithelium of human lenses with age-related cortical cataract as well as to assess cell proliferation, a predicted consequence of apoptotic cell death, in this specific cell population.

Methods

DNA fragmentation was assessed using terminal digoxigenin-labeled dUTP nick end labeling (TUNEL) in capsulotomy specimens obtained from patients who underwent either extracapsular cataract extraction for the removal of adult-onset cortical cataract (n=27) or clear lens extraction for the correction of high myopia (n=25). Cell proliferation was assayed in 23 epithelia of cataractous lenses, and 20 epithelia of non-cataractous lenses with the proliferation marker MIB1, a monoclonal antibody against the nuclear antigen Ki-67 that is detected throughout the cell cycle but is absent in the resting (G0) cell.

Results

TUNEL staining was observed in 25 (92.6%) specimens of cataractous lenses, whereas cells undergoing apoptosis were identified in 2 (8%) of the epithelia from non-catarac-tous lenses. Only two MIB1-positive samples were detected, one of which was a capsule obtained during intracapsular cataract extraction.

Conclusions

The epithelium of human lenses with cortical cataract undergoes low rate apoptotic death. This limited epithelial apoptosis is unlikely to result in any significant cell density decrease since epithelial gaps are likely to be replaced by cell proliferation at the germinative zone of the anterior lens capsule. Nevertheless, the accumulation of small-scale epithelial losses during lifetime may induce alterations in lens fiber formation and homeostasis and result in loss of lens transparency.

Primary gene response to mechanical loading in healing rat Achilles tendons

Loading can stimulate tendon healing. In healing rat Achilles tendons, we have found more than 150 genes upregulated or downregulated 3 h after one loading episode. We hypothesized that these changes were preceded by a smaller number of regulatory genes and thus performed a microarray 15 min after a short loading episode, to capture the primary response to loading. We transected the Achilles tendon of 54 rats and allowed them to heal. The hind limbs were unloaded by tail-suspension during the entire experiment, except during the loading episode. The healing tendon tissue was analyzed by mechanical testing, microarray, and quantitative real-time polymerase chain reaction (qRT-PCR). Mechanical testing showed that 5 min of loading each day for 4 days created stronger tissue. The microarray analysis after one loading episode identified 15 regulated genes. Ten genes were analyzed in a repeat experiment with new rats using qRT-PCR. This confirmed the increased expression of four genes: early growth response 2 (Egr2), c-Fos, FosB, and regulation of G protein signaling 1 (Rgs1). The other genes were unaltered. We also analyzed the expression of early growth response 1 (Egr1), which is often co-regulated with c-Fos or Egr2, and found that this was also increased after loading. Egr1, Egr2, c-Fos, and FosB are transcription factors that can be triggered by numerous stimuli. However, Egr1 and Egr2 are necessary for normal tendon development, and can induce ectopic expression of tendon markers. The five regulated genes appear to constitute a general activation machinery. The further development of gene regulation might depend on the tissue context.

Rac1 is required for epithelial stem cell function during dermal and oral mucosal wound healing but not for tissue homeostasis in mice

BACKGROUND

The regenerative capacity of the skin, including the continuous replacement of exfoliated cells and healing of injuries relies on the epidermal stem cells and their immediate cell descendants. The relative contribution of the hair follicle stem cells and the interfollicular stem cells to dermal wound healing is an area of active investigation. Recent studies have revealed that the small GTPase Rac1, which regulates cell migration and nuclear gene expression, is required for hair follicle stem function but not for the normal homeostasis of the interfollicular skin.

METHODOLOGY/PRINCIPAL FINDINGS

Here we explored whether Rac1 contributes to wound healing in the skin and in the oral mucosa, the latter an anatomical site that presents similar architecture to that of the skin but is devoid of any hair follicle structures, and hence lacks hair follicle stem cells. Epidermal Rac1 gene excision led to the clearly delayed closure of cutaneous wounds. Remarkably, genetic ablation of Rac1 from the oral mucosa resulted in the complete inability of oral wounds to heal. We present evidence that the lack of oral mucosal re-epithelization may result from the reduced migratory capacity of cells lacking Rac1 together with altered expression of injury-induced proliferative and cellular stress-related expression programs.

CONCLUSIONS/SIGNIFICANCE

Together, these observations support that while the normal development and homeostasis of the interfollicular skin and oral mucosa do not require Rac1 function, the interfollicular and oral epithelial stem cells may require a Rac1-dependent program to orchestrate the tissue response to injury and ultimate for wound closure. Ultimately, these findings may enable the molecular characterization of the acute tissue regenerative response of these stem cell populations, thus facilitating the identification of novel molecular-targeted strategies aimed at accelerating wound closure.

Perturbed intraepithelial differentiation of corneal epithelium in c-Fos-null mice

PURPOSE

AP-1 is a transcription factor that plays a pivotal role in regulating cellular homeostasis and which may modulate the differentiation of corneal epithelial cells. We examined the role of c-Fos in the differentiation of corneal epithelial cells by using c-Fos-deficient (c-fos (-/-)) mice.

METHODS

Ten adult c-fos (-/-) mice and ten control (c-fos (+/-) or c-fos (+/+)) mice were used. The expression patterns of the mRNA and protein of keratin 12 (K12) were determined to examine the differentiation of cornea-type epithelium. To evaluate the intraepithelial differentiation from basal cells to superficial cells, the ultrastructure of the corneal epithelium was studied. We focused on the formation of desmosomes in the superficial, suprabasal, and basal cell layers, and also on the hemidesmosomes. The number of desmosomes in each epithelial layer was statistically analyzed by using an unpaired t test. The expressions of keratin 14 (K14), desmoglein, E-cadherin, occludin, connexin 43, filaggrin, loricrin, and involucrin were examined to analyze epithelial differentiation.

RESULTS

The mRNA and protein of K12 were expressed in the corneal epithelium of c-fos (-/-) and control mice. Ultrastructural observations showed that the number of desmosomes between the basal cells of the corneal epithelia was similar in c-fos (-/-) and control mice. However, there were fewer desmosomes between suprabasal cells and between superficial cells in c-fos (-/-) mice than in control mice. The number of hemidesmosomes in the corneal epithelial cells in c-Fos-null mice was similar to that in control mice. The expressions of the other epithelial cell differentiation markers were not affected by the absence of c-Fos. Ultrastructural observations showed a disarrangement of the corneal epithelium in the c-Fos-null mice.

CONCLUSIONS

The absence of c-Fos disturbs the formation of desmosomes in the superficial layers of the corneal epithelium, suggesting a perturbation of intraepithelial differentiation from the basal epithelial cells to the suprabasal and superficial epithelial cells.

Exposure of human corneal epithelial cells to contact lenses in vitro suppresses the upregulation of human β-defensin-2 in response to antigens of Pseudomonas aeruginosa

Bacterial keratitis is a sight-threatening complication of contact lens wear, and Pseudomonas aeruginosa is a commonly isolated pathogen. The mechanisms by which lenses predispose the cornea to P. aeruginosa infection are unknown. Corneal epithelial cells express numerous innate defenses, some of which have bactericidal effects against P. aeruginosa. One of these is human beta-defensin-2 (hBD-2), which is upregulated in response to lipopolysaccharide or flagellin antigens. We hypothesized that prior exposure of corneal epithelia to a contact lens would interfere with upregulation of hBD-2 in response to P. aeruginosa. A novel in vitro model was used in which cultured human corneal epithelial cells were exposed to a hydrophilic contact lens for up to 3.5 days prior to challenge with a culture supernatant of P. aeruginosa antigens for 6h. Without prior lens exposure, the supernatant caused >2-fold upregulation of hBD-2 mRNA message and expression of hBD-2 peptide. Prior contact lens exposure blocked this upregulation without obvious effects on cell health. Western immunoblot and luciferase reporter studies showed that Pseudomonas-induced hBD-2 upregulation involved MyD88, c-Jun N-terminal kinase and both AP-1 and NF-kappaB transcription factors. Contact lenses did not affect surface expression of Toll-like receptor-2, -4 or -5, but did block antigen activation of AP-1, but not NF-kappaB, transcription factors. These data show that contact lenses can interfere with epithelial defense responses to bacterial antigens in vitro, and if translated in vivo, could help predispose the cornea to infection.

Somatic excision demonstrates that c-Jun induces cellular migration and invasion through induction of stem cell factor

Cancer cells arise through sequential acquisition of mutations in tumor suppressors and oncogenes. c-Jun, a critical component of the AP-1 complex, is frequently overexpressed in diverse tumor types and has been implicated in promoting cellular proliferation, migration, and angiogenesis. Functional analysis of candidate genetic targets using germ line deletion in murine models can be compromised through compensatory mechanisms. As germ line deletion of c-jun induces embryonic lethality, somatic deletion of the c-jun gene was conducted using floxed c-jun (c-jun(f/f)) conditional knockout mice. c-jun-deleted cells showed increased cellular adhesion, stress fiber formation, and reduced cellular migration. The reduced migratory velocity and migratory directionality was rescued by either c-Jun reintroduction or addition of secreted factors from wild-type cells. An unbiased analysis of cytokines and growth factors, differentially expressed and showing loss of secretion upon c-jun deletion, identified stem cell factor (SCF) as a c-Jun target gene. Immunoneutralizing antibody to SCF reduced migration of wild-type cells. SCF addition rescued the defect in cellular adhesion, cellular velocity, directional migration, transwell migration, and cellular invasion of c-jun(-/-) cells. c-Jun induced SCF protein, mRNA, and promoter activity. Induction of the SCF promoter required the c-Jun DNA-binding domain. c-Jun bound to the SCF promoter in chromatin immunoprecipitation assays. Mutation of the c-Jun binding site abolished c-Jun-mediated induction of the SCF promoter. These studies demonstrate an essential role of c-Jun in cellular migration through induction of SCF.

Lens epithelial cells promote regrowth of retinal ganglion cells in culture and in vivo

Lens damage has been demonstrated to promote axonal regeneration of retinal ganglion cells. Various mechanisms associated with this enhancement have been proposed, including macrophage recruitment and stimulatory factors from the lesioned lens. Lens epithelial cells, which become activated as a result of injury, are another potential stimulus. A recent study of co-culturing lens epithelial cells adjacent to retinal explants without direct contact showed that neurites were attracted to grow towards them. We explored the ability of lens epithelial cells to act as a favorable substrate for ganglion cell axonal regeneration, by culturing retinal explants on top of a lens epithelial cell layer, as well as in vivo by transplanting freshly isolated lens epithelial cells to the cut optic nerve. Retinal explants cultured on lens epithelial cells regenerated more and longer neurites than those cultured on either an acellular substrate or a substrate of corneal cells, while lens epithelial cells transplanted to the optic nerve stimulated axons to regenerate in close association with them.

Delayed wound healing and epidermal hyperproliferation in mice lacking JunB in the skin

The cutaneous response to injury and stress comprises a temporary change in the balance between epidermal proliferation and differentiation as well as an activation of the immune system. Soluble factors play an important role in the regulation of these complex processes by coordinating the intercellular communication between keratinocytes, fibroblasts, and inflammatory cells. In this study, we demonstrate that JunB, a member of the activator protein-1 transcription factor family, is an important regulator of cytokine expression and thus critically involved in the cutaneous response to injury and stress. Mice lacking JunB in the skin develop normally, indicating that JunB is neither required for cutaneous organogenesis, nor homeostasis. However, upon wounding and treatment with the phorbol ester 12-O-decanoyl-phorbol-13-acetate, JunB-deficiency in the skin likewise resulted in pronounced epidermal hyperproliferation, disturbed differentiation, and prolonged inflammation. Furthermore, delayed tissue remodelling was observed during wound healing. These phenotypic skin abnormalities were associated with JunB-dependent alterations in expression levels and kinetics of important mediators of wound repair, such as granulocyte macrophage colony-stimulating factor, growth-regulated protein-1, macrophage inflammatory protein-2, and lipocalin-2 in both the dermal and epidermal compartment of the skin, and a reduced ability of wound contraction of mutant dermal fibroblasts in vitro.

[Influence of intraocular lens material and design on the development of posterior capsule opacification]

Based on the literature of 1999-2005, we attempted to clarify the influence of material and design of an intraocular lens (IOL) on the development of posterior capsule opacification (PCO) and identify the future problems to be solved. The sharp edge design of an IOL has significantly reduced PCO in recent years. Histopathological studies showed that a sharp capsular bend was formed at the sharp posterior optic edge, and the migration of lens epithelial cells was obviously inhibited at the site. Experimental and clinical studies suggest that the sharper the edge is, the sharper the capsular bend, and the greater the preventive effect, regardless of IOL material. The sharp capsule bend appears to represent a physical hindrance, which may induce contact inhibition of cell movement. How material participates in the preventive effect should be clarified in a future study. Thus, at the moment, the formation of capsular bend at the posterior optic edge appears to be the decisive criterion to evaluate the influence of IOL material and design on the development of PCO. Optimization of design and material of an IOL, which facilitates capsular bend formation as sharply and quickly as possible, may reduce PCO to a clinically negligible level.

Transcriptional activation in lens epithelial cells following an ocular blunt trauma

PURPOSE

To determine whether an ocular blunt trauma activates anterior ocular segment (cornea and lens) by examining the expression patterns of c-fos and c-jun mRNAs in these tissues of an eye of adult rat following a blunt trauma.

SETTING

Department of Ophthalmology, Wakayama Medical University School of Medicine, Kimiidera, Wakayama, Japan.

METHODS

Adult Wistar rats (n=36) were generally anesthetized by ether inhalation. One eye was hit with an iron sphere (30 gram) that fell to the eye from 1 m. After the procedure, the animals were killed and the affected eye was enucleated at 15, 30, 60, 120, and 180 minutes. In situ hybridization using radiolabeled oligoprobes was used to detect mRNAs of c-fos and c-jun in tissue.

RESULTS

The c-fos and c-jun mRNAs were not detected in the epithelium of uninjured cornea and lens by in situ hybridization. The mRNAs for c-fos and c-jun were then detected in corneal epithelium from 15 to 60 minutes posttreatment, and were no longer observed thereafter. In lens epithelium, mRNA for c-fos or c-jun were transiently detected from 15 to 60 minutes or 30 minutes posttreatment, respectively.

CONCLUSION

The c-fos and c-jun mRNAs were transiently expressed in corneal and lens epithelial cells after blunt trauma. Ocular blunt trauma activates corneal and lens epithelial cells without apparent corneal ablation or direct injury in the lens epithelium. Such activation in lens epithelium might be involved in cataractogenesis.

Accumulation of thrombospondin-1 in post-operative capsular fibrosis and its down-regulation in lens cells during lens fiber formation

Thrombospondin-1 (TSP-1) is a glycoprotein involved in activation of latent transforming growth factor beta (TGFbeta) expression. We examined changes in its expression pattern during human capsular opacification (PCO) and anterior subcapsular cataractogenesis (ASC), as well as in a healing injured mouse lens. Its expression pattern was also compared in a mouse embryonic lens with that in an adult lens. Based on immunohistochemistry under light microscopy, TSP-1 expression and other matrix components were evident in the anterior epithelium of an uninjured human lens, whereas fiber-differentiating cells in the equator of human lens lack TSP-1 immunoreactivity. In contrast, in post-operative human lens epithelial or fibroblastic cells, there was TSP-1 immunoreactivity, whereas it decreased in fiber-differentiating cells in PCO. Matrix components accumulated on the healing capsule also labeled with anti-TSP-1 antibody like antibodies against collagen I, IV, V and laminin. In uninjured, injured mouse lens epithelial cells and its matrix, there was TSP-1 expression. Embryonic lens cells in the posterior pole, undergoing differentiation to fiber cells, began to express TSP-1 protein at embryonic day (E) 11.5 whereas anterior epithelial cells started to express it at E13.5 in association with marked expression in central fiber cells. At E16.5, TSP-1 was detected in fibers just beneath the anterior epithelium, but the fiber mass showed minimal expression. At E18.5 and post-natally day 1, lens fiber TSP-1 expression was no longer seen. On the other hand, it was evident in both intact human anterior epithelial and dispersed mouse cells. The results indicate that there is TSP-1 expression in uninjured human and mouse lens epithelial cells and their fibrous tissue. In contrast, in post-operative lens cells differentiating to fiber cells, its expression levels decline. Further study is needed to clarify the roles of TSP-1 in modulating lens cell phenotype expression.

Expression of c-Fos and c-Jun in developing mouse lens

We carried out immunohistochemistry in embryonic eye-specific antibodies in the mouse to determine the spatial/temporal expression pattern of c-Fos and c-Jun proteins--the main components of the AP-1 transcription factor, in lens epithelial cells during mouse lens morphogenesis. c-Fos protein expression was detected in the equatorial epithelium at E14.5-P25, with a peak at P1-P8. c-Jun protein expression was detected in equatorial lens epithelial cells at E18.5-P8, with a peak at P1. During these intervals, the anterior epithelium lacked expression of c-Fos and c-Jun. They were not detected in an adult mouse lens. The expression pattern of the AP-1 transcription factor in equatorial epithelium may suggest its role in fiber differentiation.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Endostatin's antiangiogenic signaling network

It is here demonstrated that the set of gene expressions underlying the angiogenic balance in tissues can be molecularly reset en masse by a single protein. Using genome-wide expression profiling, coupled with RT-PCR and phosphorylation analysis, we show that the endogenous angiogenesis inhibitor endostatin downregulates many signaling pathways in human microvascular endothelium associated with proangiogenic activity. Simultaneously, endostatin is found to upregulate many antiangiogenic genes. The result is a unique alignment between the direction of gene regulation and angiogenic status. Profiling further reveals the regulation of genes not heretofore associated with angiogenesis. Our analysis of coregulated genes shows complex interpathway communications in an intricate signaling network that both recapitulates and extends on current understanding of the angiogenic process. More generally, insights into the nature of genetic networking from the cell biologic and therapeutic perspectives are revealed.

Transcription activation in lens epithelial cells after anterior capsule rubbing in rats. expression of c-Fos

PURPOSE

To determine whether lens epithelial cells (LECs) are transcriptionally activated after a foreign body is attached to the anterior lens surface.

SETTING

Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.

METHODS

One eye of adult Wistar rats (N = 32) was used. After the anterior capsule of the lens was rubbed with a dull 27-gauge needle 10 times, the eye was enucleated immediately (within 1 minute) or at 30 minutes or 1, 3, or 5 hours. The 32 globes were immunohistochemically analyzed using anti-c-Fos and anti-c-Jun antibodies.

RESULTS

Immunohistochemistry showed that normal LECs lacked immunoreactivity for c-Fos or c-Jun. The c-Fos protein was localized in the nuclei of LECs in the equatorial region of the injured lens 3 hours after treatment and was not detected thereafter. The c-Jun protein was not detected at any interval.

CONCLUSION

The protein c-Fos was transiently expressed in equatorial LECs after the anterior lens capsule was rubbed, indicating that equatorial LECs are transcriptionally activated by minor mechanical stimuli to the anterior lens surface.

c-Jun is essential for organization of the epidermal leading edge

The migration of epithelial layers requires specific and coordinated organization of the cells at the leading edge of the sheet. Mice that are conditionally deleted for the c-jun protooncogene in epidermis are born at expected frequencies, but with open eyes and with defects in epidermal wound healing. Keratinocytes lacking c-Jun are unable to migrate or elongate properly in culture at the border of scratch assays. Histological analyses in vitro and in vivo demonstrate an inability to activate EGF receptor at the leading edge of wounds, and we demonstrate that this can be rescued by supplementation with conditioned medium or the EGF receptor ligand HB-EGF. Lack of c-Jun prevents EGF-induced expression of HB-EGF, indicating that c-jun controls formation of the epidermal leading edge through its control of an EGF receptor autocrine loop.

Effect of the optic size of a single-piece acrylic intraocular lens on posterior capsule opacification

PURPOSE

To investigate the effect of the optic size of an intraocular lens (IOL) with sharp optic edges on posterior capsule opacification (PCO).

SETTING

Nishi Eye Hospital, Osaka, Japan.

METHODS

In 5 rabbits, a single-piece 5.5 mm optic AcrySof IOL (Alcon Laboratories) was implanted in 1 eye and a specially fabricated single-piece 7.0 mm optic AcrySof IOL was implanted in the contralateral eye. Histopathological examinations were performed 3 weeks after surgery.

RESULTS

On posterior views, less PCO was noted with the 5.5 mm optic in all rabbits except 1. Histopathological sections demonstrated adhesion of the anterior and posterior capsules between the haptic and optic and the formation of a sharp capsular bend at the posterior optic edge in 3 eyes with the 5.5 mm optic but in no eye with the 7.0 mm optic. Abundant PCO was noted when a sharp capsular bend had not formed.

CONCLUSIONS

Capsular adhesion is a prerequisite of capsular-bend formation. The sharp optic edge alone does not provide a substantial barrier when a capsular bend is not formed. Bulky haptics such as those of the single-piece AcrySof and large optics may hamper capsular adhesion and bend formation.