NF-κB/Cartilage Acidic Protein 1 Promotes Ultraviolet B Irradiation-Induced Apoptosis of Human Lens Epithelial Cells

NDRG2 Promotes Lens Epithelial Cells Senescence via NLRP3/Caspase1-Mediated Pyroptosis

OBJECT

This study aims to investigate the molecular mechanism of NDRG2 (N-myc downstream-regulated gene 2) in the cell senescence of lens endothelial cells.

METHODS

Lens endothelial cells (SRA01/04) were irradiated with UVB at different times. Cell viability was measured by CCK-8 kit and cell cycle was detected by flow cytometry. Cell senescence was detected using SA-β-gal staining. Western blot was utilized to detect the expressions of p53, p21 and NDRG2. TUNEL staining and flow cytometry were used to detect apoptosis and pyroptosis.

RESULTS

UVB-irradiation significantly induces cell senescence and the expression of NDRG2, p53 and p21 in SRA01/04 cells was up-regulated. Down-regulation of NDRG2 inhibited UVB-induced cell senescence, significantly reversed pyroptosis and promoted cell proliferation. UVB-induced pyroptosis is closely related to caspase-1/NLRP3 axis.

CONCLUSION

Our study confirmed downregulation of NDRG2 significantly inhibited UVB radiation-induced cell senescence by regulating caspase-1/NLRP3-mediated pyroptosis.

Cataractogenesis and molecular pathways, with reactive free oxygen species as a common pathway

Slowing down or stopping the natural process of cataractogenesis is certainly a challenge for those who today propose an option other than surgery. Addressing the same problem in different ways constitutes a new approach to solving what is today the number one cause of reversible blindness worldwide. The technological revolution, as well as the advances in the biological sciences, allows us to conceive mechanisms never thought of before to stop the process that, as a common pathway, constitutes opacification of the crystalline lens. A new dawn for cataracts is coming through molecular, newly-discovered mechanisms. Cataractogenesis and molecular pathways have reactive free oxygen species as a common pathway. Surgical removal is today's gold standard, but perhaps not for much longer.

CRTAC1 enhances the chemosensitivity of non-small cell lung cancer to cisplatin by eliciting RyR-mediated calcium release and inhibiting Akt1 expression

Sensitivity to platinum-based combination chemotherapy is associated with a favorable prognosis in patients with non-small cell lung cancer (NSCLC). Here, our results obtained from analyses of the Gene Expression Omnibus database of NSCLC patients showed that cartilage acidic protein 1 (CRTAC1) plays a role in the response to platinum-based chemotherapy. Overexpression of CRTAC1 increased sensitivity to cisplatin in vitro, whereas knockdown of CRTAC1 decreased chemosensitivity of NSCLC cells. In vivo mouse experiments showed that CRTAC1 overexpression increased the antitumor effects of cisplatin. CRTAC1 overexpression promoted NFAT transcriptional activation by increasing intracellular Ca2+ levels, thereby inducing its regulated STUB1 mRNA transcription and protein expression, accelerating Akt1 protein degradation and, in turn, enhancing cisplatin-induced apoptosis. Taken together, the present results indicate that CRTAC1 overexpression increases the chemosensitivity of NSCLC to cisplatin treatment by inducing Ca2+-dependent Akt1 degradation and apoptosis, suggesting the potential of CRTAC1 as a biomarker for predicting cisplatin chemosensitivity. Our results further reveal that modulating the expression of CRTAC1 could be a new strategy for increasing the efficacy of cisplatin in chemotherapy of NSCLC patients.

Nuclear import of Mas-related G protein-coupled receptor member D induces pathological cardiac remodeling

Alamandine (Ala), a ligand of Mas-related G protein-coupled receptor, member D (MrgD), alleviates angiotensin II (AngII)-induced cardiac hypertrophy. However, the specific physiological and pathological role of MrgD is not yet elucidated. Here, we found that MrgD expression increased under various pathological conditions. Then, MrgD knockdown prevented AngII-induced cardiac hypertrophy and fibrosis via inactivating Gα_i-mediacted downstream signaling pathways, including the phosphorylation of p38 (p-P38), while MrgD overexpression induced pathological cardiac remodeling. Next, Ala, like silencing MrgD, exerted its cardioprotective effects by inhibiting Ang II-induced nuclear import of MrgD. MrgD interacted with p-P38 and promoted its entry into the nucleus under Ang II stimulation. Our results indicated that Ala was a blocking ligand of MrgD that inhibited downstream signaling pathway, which unveiled the promising cardioprotective effect of silencing MrgD expression on alleviating cardiac remodeling. Video Abstract.

Ultraviolet B radiation induces oxidative stress and apoptosis in human lens epithelium cells by activating NF-κB signaling to down-regulate sodium vitamin C transporter 2 (SVCT2) expression

Ultraviolet B (UVB) exposure is reported to cause cataract formation by inducing excessive reactive oxygen species (ROS) and apoptosis in human lens epithelial cells (HLECs). Sodium-dependent Vitamin C transports-2 (SVCT2) is a ascorbic acid (AsA) transporter for that can protect cells and tissues from oxidative stress. Here, we focus on the functional characterization and mechanism analysis of SVCT2 in UVB-treated HLECs. The results showed a significant reduction of SVCT2 expression in HLECs treated with UVB. SVCT2 abated apoptosis and Bax expression and increased Bcl-2 expression. Moreover, SVCT2 decreased ROS accumulation and MDA level, but increased the activities of antioxidant enzymes (SOD and GSH-PX). NF-κB inhibitor (PDTC) alleviated ROS production and apoptosis, and promoted SVCT2 expression in UVB-treated HLECs. Additionally, ROS inhibitor (NAC) suppressed oxidative stress, apoptosis, and induced SVCT2 expression in UVB-treated HLECs, while these effects were significantly abated due to the activation of NF-κB signaling. Furthermore, SVCT2 facilitated 14C-AsA absorption in UVB-treated HLECs. Together, our findings demonstrated that UVB exposure-induced ROS generation, which further activated NF-κB signaling to down-regulate SVCT2 expression in HLECs. Then, downregulated SVCT2 promoted ROS accumulation and induced apoptosis by decreasing AsA uptake. Our data reveal a novel NF-κB/SVCT2/AsA regulatory pathway and suggest the therapeutic potential of SVCT2 in UVB-induced cataract.

Senescence marker protein30 protects lens epithelial cells against oxidative damage by restoring mitochondrial function

Etiology and pathogenesis of age-related cataract is not entirely clear till now. Senescence marker protein 30 (SMP30) is a newly discovered anti-aging factor, which plays an important role in preventing apoptosis and reducing oxidative stress damage. Mitochondria are located at the intersection of key cellular pathways, such as energy substrate metabolism, reactive oxygen species (ROS) production and apoptosis. Oxidative stress induced by 4-hydroxynonenal (4-HNE) is closely related to neurodegenerative diseases and aging. Our study focused on the effect of SMP30 on mitochondrial homeostasis of human lens epithelial cells (HLECs) induced by 4-HNE. Western blots and qPCR were used to compare the expression of SMP30 protein in the residual lens epithelial cells in the lens capsule of age-related cataract (ARC) patients and the donated transparent lens capsule. On this basis, SMP30 overexpression plasmid and SMP30 shRNA interference plasmid were introduced to explore the effect of SMP30 on the biological behavior in HLECs under the condition of oxidative stress induced by 4-HNE through immunohistochemistry, ROS evaluation, metabolic spectrum analysis and JC-1 fluorescence measurement. Given that Nuclear Factor erythroid 2-Related Factor 2 (Nrf2)/Kelch Like ECH Associated Protein 1 (KEAP1) signaling pathway is the most important antioxidant stress pathway, we further analyzed the regulatory effect of SMP30 by WB to explore its molecular mechanism. Our study indicated that SMP30 may inhibit ROS accumulation, restore mitochondrial function, activate Nrf2/Keap1 signaling pathway, therefore protecting lens epithelial cells from oxidative stress-induced cell damage.

Cartilage Acidic Protein a Novel Therapeutic Factor to Improve Skin Damage Repair?

Fish skin has been gaining attention due to its efficacy as a human-wound-treatment product and to identify factors promoting its enhanced action. Skin fibroblasts have a central role in maintaining skin integrity and secrete extra cellular matrix (ECM) proteins, growth factors and cytokines to rapidly repair lesions and prevent further damage or infection. The effects on scratch repair of the ubiquitous but poorly characterized ECM protein, cartilage acidic protein 1 (CRTAC1), from piscine and human sources were compared using a zebrafish SJD.1 primary fibroblast cell line. A classic in vitro cell scratch assay, immunofluorescence, biosensor and gene expression analysis were used. Our results demonstrated that the duplicate sea bass Crtac1a and Crtac1b proteins and human CRTAC-1A all promoted SJD.1 primary fibroblast migration in a classic scratch assay and in an electric cell impedance sensing assay. The immunofluorescence analysis revealed that CRTAC1 enhanced cell migration was most likely caused by actin-driven cytoskeletal changes and the cellular transcriptional response was most affected in the early stage (6 h) of scratch repair. In summary, our results suggest that CRTAC1 may be an important factor in fish skin promoting damage repair.

Hallmarks of lens aging and cataractogenesis

Lens homeostasis and transparency are dependent on the function and intercellular communication of its epithelia. While the lens epithelium is uniquely equipped with functional repair systems to withstand reactive oxygen species (ROS)-mediated oxidative insult, ROS are not necessarily detrimental to lens cells. Lens aging, and the onset of pathogenesis leading to cataract share an underlying theme; a progressive breakdown of oxidative stress repair systems driving a pro-oxidant shift in the intracellular environment, with cumulative ROS-induced damage to lens cell biomolecules leading to cellular dysfunction and pathology. Here we provide an overview of our current understanding of the sources and essential functions of lens ROS, antioxidative defenses, and changes in the major regulatory systems that serve to maintain the finely tuned balance of oxidative signaling vs. oxidative stress in lens cells. Age-related breakdown of these redox homeostasis systems in the lens leads to the onset of cataractogenesis. We propose eight candidate hallmarks that represent common denominators of aging and cataractogenesis in the mammalian lens: oxidative stress, altered cell signaling, loss of proteostasis, mitochondrial dysfunction, dysregulated ion homeostasis, cell senescence, genomic instability and intrinsic apoptotic cell death.

Deciphering the role of cartilage protein 1 in human dermal fibroblasts: a transcriptomic approach

Cartilage acidic protein 1A (hCRTAC1-A) is an extracellular matrix protein (ECM) of human hard and soft tissue that is associated with matrix disorders. The central role of fibroblasts in tissue integrity and ECM health made primary human dermal fibroblasts (NHDF) the model for the present study, which aimed to provide new insight into the molecular function of hCRTAC1-A. Specifically, we explored the differential expression patterns of specific genes associated with the presence of hCRTAC1-A by RNA-seq and RT-qPCR analysis. Functional enrichment analysis demonstrated, for the very first time, that hCRTAC1-A is involved in extracellular matrix organization and development, through its regulatory effect on asporin, decorin, and complement activity, in cell proliferation, regeneration, wound healing, and collagen degradation. This work provides a better understanding of putative hCRTAC1-A actions in human fibroblasts and a fundamental insight into its function in tissue biology.

Protective Effects of Nicotinamide Riboside on H2O2-induced Oxidative Damage in Lens Epithelial Cells

Purpose: To investigate the protective effects of nicotinamide riboside (NR) on oxidative damage in hydrogen peroxide (H₂O₂)-exposed human lens epithelial cell lines (SRA01/04) and the possible mechanisms underlying its protective effects.Materials and methods: SRA01/04 cells were divided into three groups: the control (CON) group, model (H₂O₂) group and treatment (NR+H₂O₂) group. Superoxide dismutase (SOD), catalase (CAT) and total glutathione (GSH) levels were detected to evaluate oxidative damage induced by different concentrations of H₂O₂ in SRA01/04 cells. After SRA01/04 cells were treated with NR and/or H₂O₂, cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst staining, cell apoptosis was analysed using flow cytometry, reactive oxygen species (ROS) were measured with the DCFH-DA probe, and mitochondria were stained with MitoTracker to measure the mitochondrial membrane potential (MMP). In addition, western blotting was performed to detect the levels of proteins associated with apoptosis and related signalling pathways.Results: H₂O₂ induced oxidative damage in SRA01/04 cells by inhibiting the activity of SOD and CAT and reducing total GSH levels. Treatment of SRA01/04 cells with NR significantly increased cell viability and reduced cell apoptosis and ROS generation, whereas SOD and CAT activities and total GSH and MMP levels were improved by the NR treatment in an H₂O₂-exposed cell model. Furthermore, NR significantly inhibited the activation of the MAPK pathway but promoted activation of the JAK2/Stat3 pathway compared with the model group.Conclusions: NR may alleviate oxidative damage by targeting the MAPK and JAK2/Stat3 pathways in H₂O₂-treated SRA01/04 cells. NR may represent anovel drug for preventing or treating cataracts.

Exosomes from adipose-derived stem cells attenuate UVB-induced apoptosis, ROS, and the Ca2+ level in HLEC cells

Cartilage acid protein 1 (CRTAC1) encodes a protein containing the Ca²⁺binding domain, which can promote apoptosis of human lens epithelial cells (HLECs) induced by ultraviolet B radiation. Exosomes secreted from adipose-derived stem cells (ASC-exo) have been used to treat many diseases, but the effect of ASC-exo on cataracts has not been established. We hypothesized that ASC-exo has a therapeutic effect on cataracts by regulating CRTAC1. We established the UVB-induced injured HLECs model to test the interactions between CRTAC1 and miR-10a-5p, and the effect on the Ca²⁺ level and reactive oxygen species (ROS) generation in apoptotic HLECs. We found that UVB significantly increased the level of CRTAC1 expression and induced HLEC apoptosis, while ASC-exo inhibited the induction of UVB and exosome inhibitor reduced the inhibition of ASC-exo. The qRT-PCR results showed that miR-10a-5p had a low level of expression in cataract lesions, whereas CRTAC1 was highly expressed. There was a negative correlation between the expression of CRTAC1 and miR-10a-5p. ASC-exo reversed UVB-inhibited miR-10a-5p expression and miR-10a-5p negatively regulated CRTAC1. In vitro data showed that miR-10a-5p reversed UVB-induced ROS, apoptosis, and the Ca²⁺ level in HLECs. Overexpression of CRTAC1 reversed the induction of ASC-exo in UVB-injured HLECs, and low expression of CRTAC1 reversed the induction of miR-10a-5p inhibitor. By upregulating the level of miR-10a-5p expression and downregulating the level of CRTAC1 expression, exosomes from ASCs attenuated UVB-induced apoptosis, ROS generation, and the Ca²⁺ level in HLECs. Our research provides novel insight into the treatment methods and associated mechanisms underlying cataracts.

Down-regulation of CRTAC1 attenuates UVB-induced pyroptosis in HLECs through inhibiting ROS production

Pyroptosis has been found to be related to diverse ocular diseases, including cataract. Abnormal CRTAC1 expression has been reported to involve in cataract formation by affecting cell apoptosis. Whether CRTAC1 regulates pyroptosis in the formation progress of cataract is completely unknown. Here, we aimed to investigate the regulatory effects of CRTAC1 on pyroptosis and the potential mechanism in the UVB-induced cell damage model. The results showed that the levels of the established pyroptosis markers (NLRP3, active Caspase-1, pro Caspase-1, GSDMD-N, IL-1β and IL-18) were significantly increased in cataract patients. The above pyroptosis markers could be obviously induced by UVB-irradiation in human lens epithelial cells (HLECs), while down-regulation of CRTAC1 significantly reversed the UVB-induced pyroptosis. Up-regulation of CRTAC1 promoted HLECs pyroptosis, while the ROS inhibitor N-acetyl-l-cysteine blocked the effects of CRTAC1 overexpression. In conclusion, our findings further suggested that the prominent role of CRTAC1 in cataract formation.