UVB irradiation-induced dysregulation of plasma membrane calcium ATPase1 and intracellular calcium homeostasis in human lens epithelial cells

1,25-Dihydroxvitamin D3 attenuates the damage of human immortalized keratinocytes caused by Ultraviolet-B

Objective Ultraviolet-B (UVB) radiation is an important factor in causing skin damage. The study is to explore whether 1,25-Dihydroxvitamin D3(1,25(OH)₂D₃) will attenuate the damage of human immortalized keratinocytes (HaCaT) cells caused by UVB and relevant underlying mechanisms.

METHODS

CCK-8 was employed to determine the UVB irradiation intensity and 1,25(OH)₂D₃ concentration. Western blot was used to detect the expression of NF-κB, Caspase9, Caspase3, Bax, Bcl2, FADD, CytC, Beclin-1; Flowcytometry was applied to measure the production of ROS.

RESULTS

The concentration of 1,25(OH)₂D₃ used in the study was 100nM and the UVB irradiation intensity was 20 mJ/cm². Compared with the HaCaT cells irradiated with UVB, the HaCaT cells were pretreated with 1,25(OH)₂D₃ had lower production of ROS, lower expression of NF-κB, Caspase9, Caspase3, Bax, FADD, CytC and Beclin-1(P < 0.05).

CONCLUSION

1,25(OH)₂D₃ could inhibit the development of oxidative stress and apoptosis in HaCaTs triggered by UVB. This inhibition might be achieved through suppression of mitochondria-modulated apoptosis and autophagy. Vitamin D may be a potential UVB protective component.

The protective mechanism of Grx2 in ultraviolet-B (UVB)-induced cataract formation

OBJECTIVE

We established a mouse cataract model by irradiating Grx2 knockout (KO) and knock-in (KI) genetically modified mice with UVB to explore the protective mechanism of Grx2 against UVB lens damage.

METHODS

After irradiating Grx2 KO and Grx2 KI mice with UVB lamps, we observed and recorded the general physiological conditions and lens opacity of the mice. The crystalline grading system of the University of Oxford was used to classify the opacity of the lens. Lens reactive oxygen species (ROS) contents were detected using a microplate reader, western blot, and enzyme-linked immunosorbent assay (ELISA) to detect antioxidant and antioxidant enzyme contents. Statistical analysis of the recorded data was performed by using SPSS 19.0 software.

RESULTS

After UVB irradiation, the weight of Grx2 KO mice was slightly lower than that of wild-type (WT) mice of the same age. Compared to WT mice, the lens opacity of Grx2 KO mice appeared earlier, the nucleus density of the lens increased, and the opacity increased in the first week after UVB irradiation. Meanwhile, the lenses of Grx2 KI mice remained transparent. The experiment showed that the content of ROS increased, the level of glutathione (GSH) decreased, the content of 8-OHdG increased, and the expression of BCL2 decreased after UVB irradiation. Compared to WT mice, these changes were more significant in Grx2 KO mice.

CONCLUSION

This experiment found that knocking out the Grx2 gene accelerated the occurrence and development of UVB-induced cataracts in mice and that Grx2 plays an important role in the oxidative damage caused by UVB radiation by repairing the antioxidant enzymes of the lens. This study provides a new animal model and research ideas for the study of cataract pathogenesis.

Association between host genetics of sheep and the rumen microbial composition

A synergy between the rumen microbiota and the host genetics has created a symbiotic relationship, beneficial to the host's health. In this study, the association between the host genetics and rumen microbiome of Damara and Meatmaster sheep was investigated. The composition of rumen microbiota was estimated through the analysis of the V3-V4 region of the 16S rRNA gene, while the sheep blood DNA was genotyped with Illumina OvineSNP50 BeadChip and the genome-wide association (GWA) was analyzed. Sixty significant SNPs dispersed in 21 regions across the Ovis aries genome were found to be associated with the relative abundance of seven genera: Acinetobacter, Bacillus, Clostridium, Flavobacterium, Prevotella, Pseudomonas, and Streptobacillus. A total of eighty-four candidate genes were identified, and their functional annotations were mainly associated with immunity responses and function, metabolism, and signal transduction. Our results propose that those candidate genes identified in the study may be modulating the composition of rumen microbiota and further indicating the significance of comprehending the interactions between the host and rumen microbiota to gain better insight into the health of sheep.

Epigallocatechin gallate enhances human lens epithelial cell survival after UVB irradiation via the mitochondrial signaling pathway

The aim of the present study was to explore the mechanism underlying the ultraviolet B (UVB) irradiation-induced apoptosis of human lens epithelial cells (HLECs), and to investigate the protective effect of epigallocatechin gallate (EGCG) against the UVB-induced apoptosis of HLECs. HLECs were exposed to different concentrations of EGCG plus UVB (30 mJ/cm²). Cell viability was determined using the MTT assay. Furthermore, mitochondrial membrane potential (Δψm) and apoptosis were assessed by flow cytometry with JC-1 and Annexin V/PI staining, respectively. Moreover, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), as well as the levels of GSH, hydrogen peroxide (H₂O₂) and hydroxyl free radicals were determined using biochemical assay techniques. Reverse transcription-quantitative PCR and western blotting were used to detect the mRNA and protein expression levels of Bcl-2, Bax, cytochrome c, caspase-9 and caspase-3, respectively. The results revealed that UVB irradiation reduced the Δψm of HLECs and induced apoptosis. Notably, EGCG significantly attenuated the generation of H₂O₂ and hydroxyl free radicals caused by UVB irradiation in HLECs, and significantly increased CAT, SOD and GSH-Px activities, however, the GSH levels were not significantly increased. EGCG also reduced UVB-stimulated Bax, cytochrome c, caspase-9 and caspase-3 expression, and elevated Bcl-2 expression, suggesting that EGCG may possess free radical-scavenging properties, thus increasing cell viability. In conclusion, EGCG may be able to protect against UVB-induced HLECs apoptosis through the mitochondria-mediated apoptotic signaling pathway, indicating its potential application in clinical practice.

Epigallocatechin gallate protects the human lens epithelial cell survival against UVB irradiation through AIF/endo G signalling pathways in vitro

OBJECTIVE

Oxidative stress has been recognised as an important mediator of apoptosis in lens epithelial cells. It also plays an important role in the pathogenesis of cataracts. It is reported that (-)-Epigallocatechin gallate (EGCG), the most abundant component in green tea, exhibits potent antioxidant activity against oxidative stress. This study aimed to investigate the protective effect of EGCG against Ultraviolet B (UVB) induced apoptotic death and the underlying mechanism in human lens epithelial cells (HLECs).

METHODS

HLECs were exposed to various concentrations of EGCG under UVB (30 mJ/cm²), and cell viability was monitored by the MTT assay. Next, mitochondrial membrane potential (Δψm), reactive oxygen species (ROS) and apoptosis were detected by flow cytometry. Meanwhile, the total antioxigenic capacity (T-AOC) was determined by enzyme standard instrument, and the expression of apoptosis inducing factor (AIF) and endonuclease G (Endo G) was measured by quantitative PCR (Q-PCR) and western blotting, respectively. Moreover, the localisation of AIF and Endo G within cells was further detected by confocal optical microscopy.

RESULTS

The results indicated that EGCG could enhance the cell viability and protect against cell apoptosis caused by UVB irradiation in HLECs. EGCG could also decrease the UVB-induced generation of ROS and collapse of Δψm, increase the T-AOC level. In addition, EGCG could also inhibit the UVB-stimulated increase of AIF and Endo G expression at mRNA and protein levels and ameliorate the UVB-induced mitochondria-nuclear translocation of AIF and Endo G.

CONCLUSIONS

UVB irradiation could damage HLECs viability, while EGCG exhibits antioxidant effect and inhibits UVB-induced apoptosis in HLECs through AIF/Endo G signalling pathways. Our findings reveal the underlying mechanism of EGCG against UVB-induced oxidative stress in HLECs.

De Novo Development of a Quantitative Adverse Outcome Pathway (qAOP) Network for Ultraviolet B (UVB) Radiation Using Targeted Laboratory Tests and Automated Data Mining

Ultraviolet B (UVB) radiation is a natural nonchemical stressor posing potential hazards to organisms such as planktonic crustaceans. The present study was conducted to revisit the lethal effects of UVB on crustaceans, generate new experimental evidence to fill in knowledge gaps, and develop novel quantitative adverse outcome pathways (qAOPs) for UVB. A combination of laboratory and computational approaches was deployed to achieve the goals. For targeted laboratory tests, Daphnia magna was used as a prototype and exposed to a gradient of artificial UVB. Targeted bioassays were used to quantify the effects of UVB at multiple levels of biological organization. A toxicity pathway network was assembled based on the new experimental evidence and previously published data extracted using a novel computational tool, the NIVA Risk Assessment Database (NIVA RAdb). A network of AOPs was developed, and weight of evidence was assessed based on a combination of the current and existing data. In addition, quantitative key event relationships in the AOPs were developed by fitting the D. magna data to predefined models. A complete workflow for assembly and evaluation of qAOPs has been presented, which may serve as a good example for future de novo qAOP development for chemical and nonchemical stressors.

Cytoprotective role of humanin in lens epithelial cell oxidative stress‑induced injury

Oxidative stress-induced injury and apoptosis of human lens epithelial cells (HLECs) are early events in the development of age-related cataracts (ARCs). Humanin (HN) is a mitochondrial-related peptide that serves a cytoprotective role in various cell types and animal models. Following HN knockdown or overexpression, the level of reactive oxygen species (ROS), mitochondrial membrane potential and mitochondrial DNA copy number, cell viability, LDH activity and apoptosis of HLECs under oxidative stress were detected, and apoptosis and autophagy were detected via transmission electron microscopy. The results suggested that HN may be involved in the response of HLECs to oxidative stress, and that HN expression was significantly upregulated under oxidative stress conditions. Furthermore, exogenous HN reduced intracellular ROS content and mitochondrial damage, and enhanced mitochondrial biosynthesis; however, this protection was lost in an endogenous HN knockdown cell model. In addition, to the best of our knowledge, the present study was the first to identify that HN increased mitochondrial autophagy, which was involved in reducing ROS production under oxidative stress. The present study indicated a potential mechanism underlying the anti-oxidative damage and apoptotic effects of HN under oxidative stress. In conclusion, HN may be a potential therapeutic target for ARCs as it has a significant cellular protective effect on HLECs under oxidative stress; therefore, further study is required to investigate its role in the occurrence and development of ARCs.

Protective effects of calbindin‑D28K on the UVB radiation‑induced apoptosis of human lens epithelial cells

Calbindin-D28K (Calb1) may protect human lens epithelial cells (HLECs) from apoptosis, which is a process resulting in individual cell death. The protective effects of Calb1 may be attributed to buffering high concentrations of Ca²⁺. The present study investigated the mechanisms through which Calb1 protects SRA01/04 cells (a human lens epithelial cell line) against apoptosis induced by ultraviolet B (UVB) exposure. Cells transfected with a lentivirus overexpressing Calb1 and control cells were treated with 40 µW/cm² irradiation for 15 min and then cultured for 24 h. The changes in intracellular Ca²⁺ were detected by colorimetry, and the protein expression levels of Bad, Bcl-2 and caspase-12 were measured by western blot analysis. The intracellular Ca²⁺ concentration of control HLECs increased significantly following UVB irradiation, whereas in Calb1-overexpressing cells, the Ca²⁺ levels remained steady. In the control cells, the expression of Bad and caspase-12 was upregulated, and that of Bcl-2 was down-regulated. Notably, during UVB radiation-induced apoptosis, the overexpression of Calb1 inhibited cell death, resulting in the decreased expression of Bad and caspase-12, and in the upregulated expression of Bcl-2. These results suggested that Calb1 inhibited the upregulation of genes involved in apoptosis. The siRNA-mediated knockdown of Calb1 resulted in increased rates of UVB radiation-induced apoptosis, the increased expression of Bad and caspase-12, and the decreased expression of Bcl-2, further demonstrating that Calb1 may mediate UVB radiation-mediated apoptosis by regulating Ca²⁺. On the whole, the findings of the present study indicate that UVB exposure can lead to an imbalance in the intracellular Ca²⁺ homeostasis in HLECs and that Calb1 protein exerts a negative effect on the expression of pro-apoptotic genes in HLECs. Calb1 may thus inhibit the UVB radiation-induced apoptosis of HLECs by regulating Ca²⁺.

UVB induces apoptosis via downregulation of CALML3-dependent JNK1/2 and ERK1/2 pathways in cataract

The aim of the current study was to understand the mechanisms of apoptosis occurring in cultured human lens epithelial cells (HLECs) following ultraviolet B (UVB) irradiation. The investigations intended to confirm the presence of apoptosis and to reveal the roles of oxidative stress, calcium (Ca2+), c‑Jun NH2‑terminal kinase (JNK)1/2, and extracellular signal‑regulated kinase (ERK)1/2 signaling pathway in these progresses. Cell apoptosis, ROS generation and intracellular Ca2+ concentration was measured by flow cytometry. The expression of CALML3, caspase-3, Bax, Bcl-2, p-JNK1/2, JNK1/2, p-ERK1/2 and ERK1/2 was measured by RT-qPCR and western blot analysis. Annexin V‑fluorescein isothiocyanate/propidium iodide staining demonstrated that UVB irradiation increased the apoptotic rate, reactive oxygen species (ROS) production and intracellular Ca2+ concentration of HLECs in dose‑ and time‑dependent manners. Overexpression of calmodulin like 3 (CALML3) reversed the effects of UVB irradiation on apoptosis, ROS production and Ca2+ concentration of HLECs, and decreased expressions of caspase‑3 and Bax, with increased expressions of Bcl‑2. Notably, silencing of CALML3 had similar effects to UVB irradiation and inhibited the activation JNK1/2 and ERK1/2 pathways. Nimodipine, a Ca2+‑channel antagonist, significantly attenuated the damages induced by CALML3 downregulation. In conclusion, UVB irradiation induced increase in apoptosis, ROS production and Ca2+ concentration of HLECs, in part, by downregulating the expression of CALML3 and involved oxidative stress, Ca2+, JNK1/2 and ERK1/2 signaling pathways, suggesting that investigating CALML3 may useful for developing cataract treatment.

The Plasma Membrane Calcium ATPases and Their Role as Major New Players in Human Disease

The Ca²⁺ extrusion function of the four mammalian isoforms of the plasma membrane calcium ATPases (PMCAs) is well established. There is also ever-increasing detail known of their roles in global and local Ca²⁺ homeostasis and intracellular Ca²⁺ signaling in a wide variety of cell types and tissues. It is becoming clear that the spatiotemporal patterns of expression of the PMCAs and the fact that their abundances and relative expression levels vary from cell type to cell type both reflect and impact on their specific functions in these cells. Over recent years it has become increasingly apparent that these genes have potentially significant roles in human health and disease, with PMCAs1-4 being associated with cardiovascular diseases, deafness, autism, ataxia, adenoma, and malarial resistance. This review will bring together evidence of the variety of tissue-specific functions of PMCAs and will highlight the roles these genes play in regulating normal physiological functions and the considerable impact the genes have on human disease.

Effect of Geranylgeranylacetone on Ultraviolet Radiation Type B-Induced Cataract in Heat-Shock Transcription Factor 1 Heterozygous Mouse

PURPOSE

We investigated whether heat-shock transcription factor 1 (HSF1) was involved in ultraviolet radiation type B (UVR-B)-induced lens opacity (cataract) using HSF1 heterozygous mice. We also examined the effects of geranylgeranylacetone (GGA), an inducer of heat-shock proteins via activation of HSF, on the UVR-B-induced cataract.

MATERIAL AND METHODS

Male HSF1^+/- and WT mice were unilaterally exposed to UVR-B (total: 1200mJ) at 16 weeks of age. At 48 h after the last UVR-B irradiation, the lens was isolated and the induction of the cataract was quantified as the cataract area ratio (opacity area/anterior capsule). GGA was orally administered at a dosage of 500 mg/kg once a day for two days before the first UVR-B exposure until the end of the experiment (21days in total).

RESULTS

The HSF1 expression was more greatly decreased in the lens from HSF1^+/- mice than in that from WT mice (p < 0.01). UVR-B exposure could mainly induce cataracts in the anterior capsule in both HSF1^+/- and WT mice, while the opacity of the lens was markedly enhanced in HSF^1+/- mice compared to that in WT mice(p (0.01). GGA treatment could prevent the induction of lens opacity by UVR-B exposure in both WT and HSF1^+/- mice as compared with the non-administration group (p < 0.01). No obvious alteration by the UVR-B radiation was seen in lens protein levels of αA-crystallin, αB-crystallin, or γ-crystallin with or without GGA administration among all groups of mice. In contrast to the crystallins, the lens protein level of HSP25 was decreased by UVR-B exposure in both HSF1^+/- and WT mice, and was significantly recovered in WT mice by the GGA treatment (p < 0.01). The induction of HSP25 was suppressed in HSF1^+/- mice compared with that in WT mice.

CONCLUSIONS

These data suggest that HSF1 plays an important role in the occurrence of UVR-B-induced cataracts, possibly via regulation of HSPs such as HSP25.

Solar ultraviolet radiation cataract

Despite being a treatable disease, cataract is still the leading cause for blindness in the world. Solar ultraviolet radiation is epidemiologically linked to cataract development, while animal and in vitro studies prove a causal relationship. However, the pathogenetic pathways for the disease are not fully understood and there is still no perfect model for human age related cataract. This non-comprehensive overview focus on recent developments regarding effects of solar UV radiation wavebands on the lens. A smaller number of fundamental papers are also included to provide a backdrop for the overview. Future studies are expected to further clarify the cellular and subcellular mechanisms for UV radiation-induced cataract and especially the isolated or combined temporal and spatial effects of UVA and UVB in the pathogenesis of human cataract. Regardless of the cause for cataract, there is a need for advances in pharmaceutical or other treatment modalities that do not require surgical replacement of the lens.

Zinc oxide nanoparticles inhibit murine photoreceptor-derived cell proliferation and migration via reducing TGF-β and MMP-9 expression in vitro

OBJECTIVES

To investigate behaviour and expression of transforming growth factor-β (TGF-β) and matrix metalloproteinases (MMP-9) in murine photoreceptor-derived cells (661W) after incubation with zinc oxide (ZnO) nanoparticles.

MATERIALS AND METHODS

We explored effects of ZnO nanoparticles on 661W cells using a real-time cell electronic sensing system, flow cytometry, multiple function microplate reading, real-time quantitative PCR detection system and enzyme-linked immunosorbent assay respectively.

RESULTS

Our results indicate that ZnO nanoparticles induced overload of calcium and reactive oxygen species within cells, causing formation of apoptotic bodies, disruption of cell cycle distribution, and reduction in expression of TGF-β and MMP-9, to suppress cell proliferation and migration. Our findings show that disruption of intracellular calcium homoeostasis and overproduction of reactive oxygen species were closely associated with reduction of TGF-β and MMP-9 in 661W cells under ZnO nanoparticle treatment.

CONCLUSIONS

Results of our study indicate that ZnO nanoparticles suppressed cell proliferation and migration, and reduced production of TGF-β and MMP-9 at both gene and protein levels. Our findings contribute to the understanding of the molecular mechanisms that reduced TGF-β and MMP-9 levels inhibit cell proliferation and migration under ZnO nanoparticle influence.

Protective effect of tea polyphenol ophthalmic gel on lens epithelial cells in rabbits with silicone oil tamponade after vitrectomy

Purpose. The aim of this study was to investigate the effect of tea polyphenols (TP) ophthalmic gel on lens epithelial cells (LECs) in rabbits with silicone oil tamponade after vitrectomy. Methods. In this study, unilateral vitrectomy with silicone oil tamponade was performed using 2-month-old New Zealand white rabbits (n = 72); meanwhile, age-matched nonoperated rabbits (n = 18) were used as controls. The TP ophthalmic gel was administered topically in the surgical eyes till they were sacrificed. On days 45 and 90 after operation, the levels of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), and apoptosis of LECs were analyzed, respectively. Meanwhile, caspase-3 mRNA and protein levels were also determined. Results. The results indicate that the levels of ROS and apoptosis were elevated for LECs in rabbits after operation, whereas ΔΨm was decreased. Caspase-3 was apparently increased at both mRNA and protein levels. Treatment of TP ophthalmic gel could reduce the generation of ROS, maintain ΔΨm, inhibit the overexpression of caspase-3, and thus decrease the apoptosis of LECs of rabbits after operation. Conclusions. TP ophthalmic gel can efficiently inhibit caspase-3 overexpression, reduce the apoptosis of LECs, and prevent LECs from damage. Our result provides a new approach to prevent the development of complicated cataract after vitrectomy.

Disrupted calcium homeostasis is involved in elevated zinc ion-induced photoreceptor cell death

Zinc (Zn), the second abundant trace element in living organisms, plays an important role in regulating cell metabolism, signaling, proliferation, gene expression and apoptosis. Meanwhile, the overload of Zn will disrupt the intracellular calcium homeostasis via impairing mitochondrial function. However, the specific molecular mechanism underlying zinc-induced calcium regulation remains poorly understood. In the present study, using zinc chloride (ZnCl2) as a stressor, we investigated the effect of exogenous Zn(2+) in regulating murine photoreceptor cell viability, reactive oxygen species (ROS), cell cycle distribution and calcium homeostasis as well as plasma membrane calcium ATPase (PMCA) isoforms (PMCA1 and PMCA2, i.e., ATP2B1, ATP2B2) expression. We found that the exogenous Zn(2+) in the exposure range (31.25-125.0 μmol/L) results in the overgeneration of ROS, cell cycle arrest at G2/M phases, elevation of cytosolic [Ca(2+)], inactivation of Ca(2+)-ATPase and reduction of both PMCA1 and PMCA2 in 661 W cells, and thus induces cell death. In conclusion, ZnCl2 exposure can elevate the cytosolic [Ca(2+)], disrupt the intracellular calcium homeostasis, further initiate Ca(2+)-dependent signaling pathway in 661 W cells, and finally cause cell death. Our results will facilitate the understanding of cell death induced by the zinc ion-mediated calcium homeostasis disruption.