Biomedical subjects

Choun-Ki Joo

Publications and source records attributed to Choun-Ki Joo.

36 records · Page 2Linked to original sources

PubMed2004

Wnt signaling enhances FGF2-triggered lens fiber cell differentiation.

Wnt signaling is implicated in many developmental processes, including cell fate changes. Several members of the Wnt family, as well as other molecules involved in Wnt signaling, including Frizzled receptors, LDL-related protein co-receptors, members of the Dishevelled and Dickkopf families, are known to be expressed in the lens during embryonic or postembryonic development. However, the function of Wnt signaling in lens fiber differentiation remains unknown. Here, we show that GSK-3beta kinase is inactivated and that beta-catenin accumulates during the early stages of lens fiber cell differentiation. In an explant culture system, Wnt conditioned medium (CM) induced the accumulation of beta-crystallin, a marker of fiber cell differentiation, without changing cell shape. In contrast, epithelial cells stimulated with Wnt after priming with FGF elongated, accumulated beta-crystallin, aquaporin-0, p57kip2, and altered their expression of cadherins. Treatment with lithium, which stabilizes beta-catenin, induced the accumulation of beta-crystallin, but explants treated with lithium after FGF priming did not elongate as they did after Wnt application. These results show that Wnts promote the morphological aspects of fiber cell differentiation in a process that requires FGF signaling, but is independent of beta-catenin. Wnt signaling may play an important role in lens epithelial-to-fiber differentiation.

Animals↗

PubMed2004

Accumulation and aberrant modifications of alpha-crystallins in anterior polar cataracts.

Crystallins are the major proteins found in the lens, and the localization of specific crystallins is well known. Overexpression and accumulation of alphaB-crystallin has been observed in response to stress conditions or in certain diseases, such as brain tumors and neurodegenerative diseases. The purpose of this study was to examine whether alpha-crystallins are modified during pathological myofibroblastic changes in lens epithelial cells. Lens epithelial cells attached to the anterior capsules of patients with nuclear or anterior polar cataracts were analyzed quantitatively for alpha-crystallin proteins and mRNAs using Western blot and RT-PCR analysis., respectively. The degree of modification of alpha-crystallins was determined by 2-dimensional gel electrophoresis followed by Western blotting. Higher molecular weight protein bands that were immunoreactive to anti-alphaA- and anti-alphaB-crystallin antibodies around 45 kDa accumulated more in the anterior polar cataract samples than in those with the nuclear type of cataracts. Also monomeric alphaB-crystallins accumulated more in lens epithelial cells of patients with anterior polar cataracts. By comparison, no significant changes were found in the levels of the mRNAs encoding alphaA- and alphaB-crystallins in the different types of cataracts. Both alphaA- and alphaB-crystallin proteins seemed to undergo more extensive modification in anterior polar cataracts. Conclusion. In addition to fibrotic changes, which accompany increased levels of extracellular matrix molecules, accumulation and abnormal modification of alpha-crystallins might be implicated in the pathogenic mechanism of this type of cataract.

Adult↗

PubMed2004

Efficacy of the soft-shell technique using Viscoat and Hyal-2000.

PURPOSE: To evaluate whether the soft-shell technique using Viscoat (sodium hyaluronate 3%-chondroitin sulfate 4%) and Hyal-2000 (sodium hyaluronate 1%) reduces corneal endothelial cell damage during cataract surgery. SETTING: Department of Ophthalmology, Kangnam St. Mary's Hospital, Seoul, Korea. METHODS: The nuclear opacity in 252 eyes of 230 cataract patients was classified as grade 1, 2, 3, or > or =4 using the Lens Opacities Classification System III. In each classification, the patients were divided into 4 groups before phacoemulsification based on the type of ophthalmic viscosurgical device (OVD) used during surgery: Viscoat and Hyal-2000 (soft-shell technique), Viscoat alone, Hyal-2000 alone, or Provisc (sodium hyaluronate 1%) alone. All patients were operated on using the same technique except for the OVD. The visual acuity, corneal endothelial cell density, corneal thickness, and intraocular pressure (IOP) were evaluated postoperatively. RESULTS: The rate of endothelial cell loss 2 months after surgery in eyes with a nuclear opacity grade of > or =4 was significantly different between the 4 OVD groups. The rate in eyes with a nuclear opacity grade of < or =3 was not significantly different between the groups. There were no statistically significant differences between the 4 groups in visual acuity, corneal thickness, or IOP throughout the follow-up period. CONCLUSION: The soft-shell technique using Viscoat and Hyal-2000 protected corneal endothelial cells during cataract surgery in patients with a nuclear opacity grade of > or =4.

Aged↗

PubMed2004

Morphological and functional changes in the rat cornea with an ethanol-mediated epithelial flap.

PURPOSE: To establish morphologic and functional changes in the rat cornea after 20% ethanol-mediated epithelial flap creation. METHODS: The epithelial flap was detached using 20% ethanol and then repositioned. On the other eye, the corneal epithelium was mechanically scraped. The morphologic changes were examined by light and transmission electron microscopy (LM and TEM). Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assays and proliferative cell nuclear antigen (PCNA) staining were performed to detect apoptosis and proliferation, respectively. The number of central stromal keratocytes was counted during wound-healing periods. A Y-chromosome-specific gene (SRY) was detected in genomic DNA obtained from female epithelial cells with male epithelial flap. Expressions of matrix metalloproteinase (MMP)-9, aquaporine5 (AQP5), and mucin1 (MUC1) mRNAs were examined by reverse transcription-polymerase chain reaction. RESULTS: After flap repositioning, damaged basal cells were observed until day 1, and the death of epithelial cells and stromal keratocytes loss peaked at day 1. Cell proliferation and MMP-9 mRNA levels peaked from days 1 to 3. By contrast, after mechanical scraping, the denuded stromal surface was covered with multilayer epithelial cells at day 3, cell death peaked at 4 hours, cell proliferation peaked from 12 hours to day 1, stromal keratocytes loss peaked at 8 hours, and MMP-9 mRNA was widely expressed from 12 hours to day 3. In both corneas, hemidesmosomes were not observed until day 1, and they continued to be present at day 3. The SRY gene was detected in female epithelial cells at day 1 after transplantation, but not at day 3. Expressions of AQP5 and MUC1 mRNAs were unchanged. CONCLUSIONS: Ethanol-mediated flap creation induces less keratocyte loss and a slower wound-healing process than mechanical scraping. The flap protecting the underlying stromal surface may have epithelial function. In addition, this Sprague-Dawley rat model may be useful in the study of the wound-healing response after LASEK.

Animals↗

PubMed2004

Retinal pigment epithelial cell behavior is modulated by alterations in focal cell-substrate contacts.

PURPOSE: To investigate how the cellular behavior of cultured retinal pigment epithelial (RPE) cells was affected by the manipulation of early focal contact. METHODS: To manipulate early focal contact, a reduced focal cell-substrate contact area on the micropatterned surfaces was implemented by microfabrication with polydimethylsiloxane (PDMS). The micropatterned PDMS surfaces had a circular pillar with a diameter of 5 microm. The human retinal pigment epithelial cell line, ARPE-19, was seeded onto the fibronectin-coated PDMS surfaces. Cell adhesion, growth, cell cycle, morphology, and interleukin-6 (IL-6) expression were observed for 3 weeks. RESULTS: The fluorescent images of localized vinculin and actin stress fibers appeared to be more prominent on smooth PDMS surfaces. Although there was no significant effect on cell adhesion, a statistically significant inhibition of cell cycle progression was observed for micropatterned PDMS surfaces. Similarly, micropatterned surfaces showed significantly less cell growth than that of smooth surfaces. Cultures over a period of 3 weeks showed a distinct cell-cell phenotype discrepancy. Furthermore, IL-6 mRNA and secreted protein induced by IL-1beta in ARPE-19 were downregulated on micropatterned PDMS surfaces. CONCLUSIONS: Disturbed focal contact in ARPE-19 cells grown on micropatterned surfaces altered cell cycle, growth, morphology, and the expression of IL-6 in vitro.

Actins↗

PubMed2004

Hepatocyte growth factor induces proliferation of lens epithelial cells through activation of ERK1/2 and JNK/SAPK.

PURPOSE: Posterior capsule opacification (PCO) is caused by proliferation and migration of lens epithelial cells (LECs) remaining after cataract surgery. In this study, the effect of HGF in LECs and the signaling pathways that contribute to HGF-induced proliferation were investigated. METHODS: Capsular bags prepared from porcine eyes were maintained in serum-free DMEM. The human lens epithelial B3 cells (HLE B3) and rat lens epithelial explants were cultured in MEM supplemented with 20% FCS and medium 199 with 0.1% BSA, respectively. Cell proliferation was determined by MTT assay, proliferating cell nuclear antigen (PCNA) expression, or flow cytometry. An antisense oligonucleotide was used to inhibit cyclin D1 expression. Activation of the mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways was detected by immunoblot analysis. RESULTS: The proliferation of LECs in a capsular bag culture was significantly inhibited by treatment with the neutralizing antibody for HGF receptor. Stimulation of HLE B3 with hepatocyte growth factor (HGF) activated the MAPKs, ERK, and JNK/SAPK, but not p38. Activation of both ERK and JNK/SAPK was necessary for the HGF-stimulated induction of cyclin D1, which in turn was necessary for the HGF-induced proliferation of LECs. PI3K also participated in the regulation of cyclin D1 expression upstream of ERK and JNK/SAPK. CONCLUSIONS: The data indicate that HGF is a potent growth factor for LECs and may contribute to the development of PCO and suggest that the signaling pathways involved in HGF-stimulated proliferation may constitute potential therapeutic targets in the treatment of PCO.

Animals↗

PubMed2003

Clinical results of laser in situ keratomileusis with superior and nasal hinges.

PURPOSE: To compare the differences in the clinical results of LASIK with a nasal corneal flap and with a superior corneal flap. SETTING: Department of Ophthalmology, Kangnam St. Mary's Hospital, Seoul, Korea. METHODS: This randomized prospective study comprised 30 patients whose age and degrees of myopia were similar. In 1 group (25 eyes), a superior hinge was made and in the other group (25 eyes), a nasal hinge was made. Uncorrected visual acuity (UCVA), spherical equivalent (SE), astigmatism, and corneal topographical change before surgery and 1 week and 2 and 6 months after surgery were compared. The tear breakup time (BUT) and the Schirmer test before surgery and 2 months postoperatively were also compared. RESULTS: At 6 months, there were no significant between-group differences in UCVA, SE, astigmatism, and corneal ablation decentration (P >.05). At 2 months, the results of BUT and the Schirmer tests were 6.80 seconds and 9.54 mm, respectively, in the nasal hinge group (P >.05) and 5.08 seconds and 6.05 mm, respectively, in the superior hinge group (P <.05). CONCLUSIONS: There were no between-group differences in UCVA, SE, astigmatism, and corneal ablation decentration at 6 months, but the BUT and Schirmer test results were aggravated after LASIK in the superior hinge group.

Adult↗

PubMed2003

Activation of MAPK and CREB by GM1 induces survival of RGCs in the retina with axotomized nerve.

PURPOSE: Neuronal cells undergo apoptosis when the supply of neurotrophic factor is limited by injury, trauma, or neurodegenerative disease. Ganglioside has both neuritogenic and neurotropic functions. Exogenously administered monosialoganglioside (GM1) has been shown to have a stimulatory effect on neurite outgrowth and to prevent degeneration of neuronal cells in the central nervous system. Even though GM1 has been shown to mimic, or have synergy with, neurotrophic factors, the neuroprotective mechanism of GM1 has not been well understood. In this study, optic nerve transection, or axotomy, was used as an in vivo model system for injury, to examine the protective mechanism of GM1 in injured retinal ganglion cells. METHODS: GM1 was injected into the vitreous body before axotomy, and the protective effect of GM1 observed with regard to activation of mitogen-activated protein kinase (MAPK) and phosphorylation of cAMP-responsive element-binding (CREB) protein. Activation of MAPK and CREB were examined by Western blot analysis and immunohistochemistry, and the surviving retinal ganglion cells were counted after retrograde fluorescence labeling. RESULTS: GM1 inhibited the degeneration of axotomized retinal ganglion cells. In addition, GM1 enhanced the activation of MAPK and CREB with the treatment of GM1 in the retina with axotomized nerve. Treatment of MAPK inhibitor PD98059 with GM1 reduced the protective action of GM1 and prevented GM1-induced phosphorylation of CREB. CONCLUSIONS: GM1 protected the axotomized retinal ganglion cells (RGCs) from cell death after axotomy through the activation of MAPK and CREB.

Animals↗

PubMed2003

Alteration of cadherin in dexamethasone-induced cataract organ-cultured rat lens.

PURPOSE: A side effect associated with long-term treatment of various diseases with steroids is a high incidence of posterior subcapsular cataracts (PSC). To understand the mechanism underlying steroid-induced cataract, the cultured lens model was developed, and the expression of potential candidate proteins during opacity formation was examined. METHOD: Rat lenses were carefully dissected from the surrounding ocular tissue and incubated in medium 199. Dexamethasone was then added to the medium. The lenses were cultured for 7 days and photographed daily to record the development of opacity. Differential expression of candidate proteins was examined by Western blot analysis. RESULT: Various degrees of opacity were observed on the posterior subcapsular region as early as 5 days after incubation with dexamethasone. The expression of E-cadherin and N-cadherin decreased in the cultured rat lenses during the development of opacity. CONCLUSIONS: The pattern of opacity that developed in cultured rat lenses closely resembled that observed in patients with PSC. The results suggest that the decrease in E-cadherin plays a role in the formation of steroid-induced cataract.

Animals↗

PubMed2002

Involvement of cell-cell interactions in the rapid stimulation of Cas tyrosine phosphorylation and Src kinase activity by transforming growth factor-beta 1.

Transforming growth factor-beta (TGF-beta) regulates a wide range of physiological and pathological cellular processes, including cell migration, mesenchymal transition, extracellular matrix synthesis, and cell death. Cas (Crk-associated substrate, 130 kDa), an adaptor protein localized at focal adhesions and stress fibers, is also known to have important functions in cell migration and the induction of immediate-early gene expression. Here, we report that a rapid and transient tyrosine phosphorylation of Cas is induced by TGF-beta 1 and that E-cadherin-mediated cell-cell interaction and the Src kinase pathway are involved in this early TGF-beta signaling. The addition of TGF-beta 1 to epithelial cells rapidly induced tyrosine phosphorylation of Cas and promoted the formation of complexes between focal adhesion molecules. Cas phosphorylation required the integrity of the actin cytoskeleton but was not dependent on cell adhesion, implying that Cas-dependent signaling may be distinct from integrin signaling. TGF-beta 1 also stimulated Src kinase activity, and specific inhibitors of Src completely blocked the induction of Cas phosphorylation by TGF-beta 1. The Cas phosphorylation and Src kinase activation seen in our results were induced in an epithelial phenotype-specific manner. Stable transfection of E-cadherin to L929 cells and L cells as well as E-cadherin blocking assay revealed that E-cadherin-mediated cell-cell interactions were essential for both Cas phosphorylation and Src kinase activation. Taken together, our data suggest that rapid Cas phosphorylation and Src kinase activation may play a novel role in TGF-beta signal transduction.

3T3 Cells↗

PubMed2002

Inhibitory effects of salmosin, a disintegrin, on posterior capsular opacification in vitro and in vivo.

The proliferation, migration and transdifferentiation of the remaining lens epithelial cells (LECs) after cataract surgery are a major cause of posterior capsular opacification (PCO). It has previously been reported that salmosin, a novel disintegrin, significantly inhibits solid tumor growth in mice by perturbation of tumor-specific angiogenesis via blocking alpha v beta 3 integrin expressed on vascular endothelial cells. In this study, the inhibitory function of salmosin in PCO was investigated and was found that salmosin inhibits the attachment of bovine LECs and rabbit lens cells (N/N1003A) to extracellular matrix-coated plates. The anti-adhesive activity of salmosin was approximately 1000 times higher than that of synthetic Arg-Gly-Asp peptide. In addition, the cell proliferation and migration of bovine LECs and N/N1003A were strongly inhibited by salmosin, whereas the proliferation of corneal endothelial cells was less affected. LEC migration and proliferation were also decreased by salmosin treatment in rabbit eyes without any toxic effect in the cornea, iris and retina. In this study, salmosin was shown to specifically inhibit LEC migration and proliferation in an animal model. Therefore, the authors suggest that further investigation may show salmosin to be a good candidate for inhibiting PCO development.

Animals↗

PubMed2002

Effect of a capsular tension ring on intraocular lens decentration and tilting after cataract surgery.

PURPOSE: To evaluate the effect of a capsular tension ring (CTR) on the tilting and decentration of intraocular lenses (IOLs) after cataract surgery. SETTING: Department of Ophthalmology, Ilsan Paik Hospital, Inje University, Kyunggyi-do, Korea. METHODS: Cataract surgery was performed in both eyes of 20 patients ranging in age from 57 to 75 years. The 40 eyes were divided into 2 groups based on whether a CTR (Lucid Korea) was implanted. Each patient received a CTR in 1 eye only. All IOLs (AcrySof MA60BM, Alcon) were implanted in the capsular bag after a continuous curvilinear capsulorhexis smaller than the IOL optic was created and phacoemulsification performed. The extent of IOL tilting and decentration was measured with the EAS-1000 anterior eye segment analysis system 7, 30, and 60 days after surgery. RESULTS: The extent of IOL decentration was statistically significantly less in eyes with both an IOL and CTR than in those with an IOL only. The mean decentration in the CTR-IOL group was 0.38 mm +/- 0.16 (SD) at 7 days, 0.43 +/- 0.15 mm at 30 days, and 0.42 +/- 0.17 mm at 60 days. The mean values in the IOL-only group were 0.49 +/- 0.11 mm, 0.53 +/- 0.14 mm, and 0.57 +/- 0.16 mm, respectively. The amount of IOL tilting was also significantly less in the CTR-IOL group. The mean tilting in the CTR-IOL group was 2.22 +/- 0.46 degrees at 7 days, 2.36 +/- 0.50 degrees at 30 days, and 2.47 +/- 0.40 degrees at 60 days. The mean values in the IOL-only group were 3.14 +/- 0.65 degrees, 2.91 +/- 0.67 degrees, and 3.06 +/- 0.56 degrees, respectively. CONCLUSION: These results indicate that the CTR reduces undesirable postsurgical IOL movement for at least 60 days.

Aged↗

PubMed2002

Downregulated expression of ADAM9 in anterior polar cataracts.

PURPOSE: To determine whether ADAM (a disintegrin and metalloproteinase) is regulated in lens epithelial cells (LECs) of patients with anterior polar cataracts and by transforming growth factor (TGF)-beta 1 in cultured LECs. SETTING: Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS: Lens epithelial cells attached to the anterior capsules of human cataractous lenses with nuclear and anterior subcapsular cataracts and noncataractous lenses were analyzed by reverse transcribed-polymerase chain reaction for the expression of ADAMs. The effect of TGF-beta 1 on ADAM gene expression was also tested in mouse lens epithelial explants and cultured LEC lines (alpha TN-4 and HLE B-3). RESULTS: Significantly reduced expression of mRNA for ADAM9 was observed in LECs from patients with anterior polar cataracts. The expression of mRNA for ADAM9 was downregulated by TGF-beta 1 in cultured human LECs. Treatment of cultured mouse LECs with TGF-beta 1 led to a reduction in ADAM1 mRNA. CONCLUSIONS: ADAMs are expressed and regulated in LECs. The downregulated expression of ADAM9 may serve as a marker for anterior polar cataracts in addition to previously known proteins, fibronectin, alpha-SMA, and beta ig-h3. The functions of this protein in lens pathology require further investigation.

ADAM Proteins↗

PubMed2002

Progressive opacification of hydrophilic acrylic intraocular lenses in diabetic patients.

Four patients with diabetes mellitus had cataract extraction with implantation of a hydrophilic acrylic intraocular lens (IOL) (ACRL-C160, Ophthalmed). The IOLs showed progressive and generalized opacification 10 to 20 months after implantation, decreasing visual acuity. All 4 IOLs were removed. By light microscopic examination, the IOL surfaces were wrinkled and encrusted with microspheres. Electron microscopy revealed the material to be crystalline in nature. Energy dispersive x-ray spectrum analysis showed that the deposits were mainly composed of calcium and phosphate.

Acrylic Resins↗

PubMed2002

Wnt/beta-catenin/Tcf signaling induces the transcription of Axin2, a negative regulator of the signaling pathway.

Axin2/Conductin/Axil and its ortholog Axin are negative regulators of the Wnt signaling pathway, which promote the phosphorylation and degradation of beta-catenin. While Axin is expressed ubiquitously, Axin2 mRNA was seen in a restricted pattern during mouse embryogenesis and organogenesis. Because many sites of Axin2 expression overlapped with those of several Wnt genes, we tested whether Axin2 was induced by Wnt signaling. Endogenous Axin2 mRNA and protein expression could be rapidly induced by activation of the Wnt pathway, and Axin2 reporter constructs, containing a 5.6-kb DNA fragment including the promoter and first intron, were also induced. This genomic region contains eight Tcf/LEF consensus binding sites, five of which are located within longer, highly conserved noncoding sequences. The mutation or deletion of these Tcf/LEF sites greatly diminished induction by beta-catenin, and mutation of the Tcf/LEF site T2 abolished protein binding in an electrophoretic mobility shift assay. These results strongly suggest that Axin2 is a direct target of the Wnt pathway, mediated through Tcf/LEF factors. The 5.6-kb genomic sequence was sufficient to direct the tissue-specific expression of d2EGFP in transgenic embryos, consistent with a role for the Tcf/LEF sites and surrounding conserved sequences in the in vivo expression pattern of Axin2. Our results suggest that Axin2 participates in a negative feedback loop, which could serve to limit the duration or intensity of a Wnt-initiated signal.

Animals↗

PubMed2002

Molecular properties of wild-type and mutant betaIG-H3 proteins.

PURPOSE: BetaIG-H3 is a TGF-beta-induced cell adhesion molecule, the mutations of which are responsible for a group of 5q31-linked corneal dystrophies. The characteristic findings in these diseases are accumulation of protein deposits of different ultrastructures. To understand the mechanisms of protein deposits in 5q31-linked corneal dystrophies, the molecular properties of betaIG-H3 and the effects of mutation on these properties were studied in vitro. METHODS: Substitution mutations were generated by two-step PCR. Wild-type and mutant recombinant betaIG-H3 proteins were raised in Escherichia coli. For structural study, nondenaturing gel electrophoresis, cross-linking experiments, and electron microscopy examination were performed. A solid-phase interaction assay was performed for the interaction of betaIG-H3 with other matrix proteins. Wild-type and mutant betaIG-H3 cDNAs were cloned into a mammalian expression vector and overexpressed in the corneal epithelial cells by transient transfection. Immunoprecipitation and immunoblot analysis were performed with an antibody against human betaIG-H3. Cell adhesion was assayed by measuring enzyme activities of N-acetyl-beta-D-glucosaminidase. RESULTS: The recombinant betaIG-H3 protein self-assembled to form multimeric bands and appeared to have a fibrillar structure. Solid-phase in vitro interaction assay showed that it bound strongly to type I collagen, fibronectin, and laminin; moderately to collagen type II and VI; and minimally to collagen type IV. Five recombinant mutant forms of betaIG-H3 (R124C, R124H, R124L, R555W, and R555Q) commonly found in 5q31-linked corneal dystrophies did not significantly affect the fibrillar structure, interactions with other extracellular matrix proteins, or adhesion activity in cultured corneal epithelial cells. In addition, the mutations apparently produced degradation products similar to those of wild-type betaIG-H3. CONCLUSIONS: BetaIG-H3 polymerizes to form a fibrillar structure and strongly interacts with type I collagen, laminin, and fibronectin. Mutations found in the 5q31-linked corneal dystrophies do not significantly affect these properties. The results suggest that mutant forms of betaIG-H3 may require other cornea-specific factors, to form the abnormal accumulations in 5q31-linked corneal dystrophies.

Acetylglucosaminidase↗

PubMedDate not supplied

Activation of caspase-3 during degeneration of the outer nuclear layer in the rd mouse retina.

Caspase activation has been implicated in apoptosis, and the nature of the apoptotic stimulus determines the specific caspase activation during apoptosis. In this study, we examined the activation of caspase-3 during photoreceptor degeneration in the rd mouse, which has a mutation on a gene encoding cyclic GMP phosphodiesterase. The outer nuclear layer of the rd mouse retina was observed using light and electron microscopy. The progress of degeneration was determined chronologically and correlated with the activation of caspase-3 and the fragmentation of poly-ADP-ribose polymerase. Additionally, the active form of caspase-3 was detected during photoreceptor degeneration in the outer nuclear layer of the rd mouse. The chronological observation of the caspase-3 activation pattern correlates with the pattern of photoreceptor degeneration. As a result of this study, we present here our findings that caspase-3 was activated in photoreceptor cells of the rd mouse.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMedDate not supplied

Mitomycin C-induced cell death in mouse lens epithelial cells.

The mode of action of mitomycin C (MMC)-induced cell death in lens epithelia was investigated using cell culture system. The cytotoxicity of MMC on alpha-TN4 mouse lens epithelial cells (LECs) was measured by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)-based assay. To determine the type of cell death induced by MMC, we stained LECs with acridine orange and ethidium bromide, and performed TUNEL assay and electron microscopic examination. The activation of MMC was also investigated with N-acetly-L-cystein (NAC), a free radical scavenger, and dicumarol, an inhibitor of DT-diaphorase, to analyze one- and two-electron reduction pathways involved in the activation of MMC. MTT assay showed that 400 microg/ml of MMC decreased the cell viability of the control cells to 45%, and the cytotoxicity of MMC on alpha-TN4 cells was increased in a dose-dependent manner. Based on the results obtained from acridine orange and ethidium bromide staining, the TUNEL assay, and transmission electron microscopic examination, we confirmed that MMC-induced cell death, at 400 microg/ml of MMC, occurs with necrosis as well as apoptotis. The treatment of cells with 2 mM NAC for 1 h or 20 microM dicumarol for 30 min, prior to 5 min of MMC (400 microg/ml) treatment, restored the growth suppression to 76 and 80% of the control level, respectively. In addition, the cotreatment of cells with NAC and dicumarol restored cell viability to 90% of the control level. The cellular death in MMC-treated LECs showed the involvement of oxidative stress in this apoptosis accounting for 22% of the observed cell death at 400 microg/ml of MMC.

Acetylcysteine↗