Fibrosis in the lens. Sprouty regulation of TGFβ-signaling prevents lens EMT leading to cataract

Polystyrene nanoplastics chronic exposure cause zebrafish visual neurobehavior toxicity through TGFβ-crystallin axis

The ubiquitous presence of micro-and nanoplastics (MNPs) in the environment and everyday products has attracted global attention for their hazardous risks. However, the effects and underling mechanisms of MNPs chronic exposure on behavioral/visual changes of the adult and offspring remain unclear. The present study investigated the impact of polystyrene (PS) nanoplastics of 80, 200 and 500 nm diameters on zebrafish visual behaviors at an environmentally relevant concentration of 0.1 mg/L. Exposure to PS resulted in zebrafish hyperactivity, enhanced aggression, compacted shoaling and less sociability, and especially suppressed the adult optokinetic response (OKR) and offspring larval phototactic behavior, with the 500 nm PS being the most detrimental. Histopathological analysis showed 500 nm PS caused significant structural damage to the retina's pigment epithelium (RPE), photoreceptor cells (PRC), and crystalline lens. Fluorescence observation found PS accumulation in retinal layers correlated with reduced oligodendrocyte transcription factor 2 (Olig2) in optic nerve. Further transcriptomic analysis of the adult eye tissue revealed that 500 nm PS affected the transforming growth factor β (TGFβ) and phototransduction signaling pathways, dysregulated visual perception and lens development, potentially leading to dysopia in zebrafish. Specifically, TGFβ and its regulated-extracellular matrix/inflammatory factors and crystallin genes were increased, but the visual perception genes were decreased, suggesting the TGFβ-crystallin axis disorders contribute to the eye dysfunction induced by PS exposure. Collectively, our results provide new evidence revealing the molecular mechanisms of PS-induced visual toxicity and neurobehavioral changes highlighting that MNPs may pose a risk to vision health.

Skullcapflavone II suppresses TGF-β-induced corneal epithelial mesenchymal transition in vitro

AIM

To investigate the effect of skullcapflavone II (SCF-II) on the epithelial-mesenchymal transition (EMT) induced by transforming growth factor beta (TGF-β) in human corneal epithelial cells (HCECs), as well as to identify the signaling pathways that may be involved.

METHODS

HCECs were cultured in vitro. At a SCF-II (5, 10 µmol/L) dose, cell viability was analysed with a cell counting kit-8 (CCK-8) assay, and cell migration was monitored with wound healing and Transwell migration assays. There were 4 groups: SCF-II, TGF-β, SCF-II+TGF-β and Control. Western blotting and immunofluorescence were performed to show the expression of EMT markers and the translocation of nuclear factor kappa-B (NF-κB) into the nucleus in the 4 groups.

RESULTS

Treatment with SCF-II decreased HCEC viability in a dose-dependent manner. A concentration below 10 µmol/L did not present obvious cell toxicity, and survival rates were more than 70% at 48h. Treatment with SCF-II (5 and 10 µmol/L) significantly impeded migration in wound healing and Transwell migration assays (P<0.05), and EMT markers and NF-κB translocation into the nucleus were inhibited. After both TGF-β and SCF-II treatment, the migration of TGF-β-treated HCECs were suppressed by SCF-II (P<0.05). The expression levels of the mesenchymal markers N-cadherin (P<0.05), α-smooth muscle actin (α-SMA; P<0.05) and NF-κB (P<0.05) in both TGF-β- and SCF-II-treated HCECs were lower than those in the HCECs treated with TGF-β alone and higher than those in HCECs treated with SCF-II alone. Immunofluorescence showed that the entry of NF-κB into the nucleus in both TGF-β- and SCF-II-treated HCECs was less than that in the TGF-β-treated HCECs.

CONCLUSION

SCF-II inhibit TGF-β-induced EMT in HCECs by potentially regulating the NF-κB signalling pathway. Thus, SCF-II represents a candidate putative therapeutic agent in corneal fibrotic diseases.

Exosomes containing miR-148a-3p derived from mesenchymal stem cells suppress epithelial-mesenchymal transition in lens epithelial cells

Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is responsible for the development of fibrotic cataracts, which contribute to severe visual impairment. Recent evidence has shown that mesenchymal stem cell-derived exosomes (MSC-Exo) can attenuate EMT in several tissues. However, the effect of MSC-Exo on EMT in LECs (LECs-EMT) has not been determined. In this study, we isolated exosomes from human umbilical cord MSCs (hucMSC-Exo) and evaluated their effect on LECs-EMT both in vitro and in vivo. HucMSC-Exo application significantly suppressed the expression of mesenchymal cell-associated genes while increasing the expression of epithelial cell-associated genes. Cell proliferation and migration of LECs undergoing EMT were inhibited after hucMSC-Exo treatment. The volume of EMT plaques in mice with injury-induced anterior subcapsular cataract (ASC) was significantly reduced in the hucMSC-Exo-treated group. Furthermore, miR-148a-3p was abundant in hucMSC-Exo. After transfection with miR-148a-3p inhibitor, the anti-fibrotic effect of hucMSC-Exo was attenuated in LECs-EMT. A dual-luciferase reporter assay identified PRNP as a direct target gene of miR-148a-3p. Furthermore, we verified that hucMSC-Exo inhibited LECs-EMT through the miR-148a-3p/PRNP axis and the potential downstream ERK signaling pathway. Taken together, our work reveals the inhibitory effect of hucMSC-Exo on LECs-EMT and the underlying mechanism involved, which may provide potential therapeutic options for fibrotic cataracts.

RRM2 Regulates Hepatocellular Carcinoma Progression Through Activation of TGF-β/Smad Signaling and Hepatitis B Virus Transcription

BACKGROUND

Hepatocellular carcinoma (HCC) is a type of malignant tumor with high morbidity and mortality. Untimely treatment and high recurrence are currently the major challenges for HCC. The identification of potential targets of HCC progression is crucial for the development of new therapeutic strategies.

METHODS

Bioinformatics analyses have been employed to discover genes that are differentially expressed in clinical cases of HCC. A variety of pharmacological methods, such as MTT, colony formation, EdU, Western blotting, Q-PCR, wound healing, Transwell, cytoskeleton F-actin filaments, immunohistochemistry (IHC), hematoxylin-eosin (HE) staining, and dual-luciferase reporter assay analyses, were utilized to study the pharmacological effects and potential mechanisms of ribonucleotide reductase regulatory subunit M2 (RRM2) in HCC.

RESULTS

RRM2 expression is significantly elevated in HCC, which is well correlated with poor clinical outcomes. Both in vitro and in vivo experiments demonstrated that RRM2 promoted HCC cell growth and metastasis. Mechanistically, RRM2 modulates the EMT phenotype of HCC, and further studies have shown that RRM2 facilitates the activation of the TGF-β/Smad signaling pathway. SB431542, an inhibitor of TGF-β signaling, significantly inhibited RRM2-induced cell migration. Furthermore, RRM2 expression was correlated with diminished survival in HBV-associated HCC patients. RRM2 knockdown decreased the levels of HBV RNA, pgRNA, cccDNA, and HBV DNA in HepG2.2.15 cells exhibiting sustained HBV infection, while RRM2 knockdown inhibited the activity of the HBV Cp, Xp, and SpI promoters.

CONCLUSION

RRM2 is involved in the progression of HCC by activating the TGF-β/Smad signaling pathway. RRM2 increases HBV transcription in HBV-expressing HCC cells. Targeting RRM2 may be of potential value in the treatment of HCC.

Mefunidone Inhibits Inflammation, Oxidative Stress, and Epithelial-Mesenchymal Transition in Lens Epithelial Cells

Purpose

Inflammation, oxidative stress, and epithelial-mesenchymal transition (EMT) play crucial roles in forming posterior capsular opacification (PCO), particularly in fibrotic PCO. Here we investigated the protective effects of mefunidone (MFD), a novel compound with potent antifibrotic properties, which could be useful in preventing PCO.

Methods

We utilized an extracapsular lens extraction (ECLE) surgery in mice to simulate the development of PCO in vivo. Treatment was performed immediately postsurgery through the intracameral injection of MFD solution. Expression levels of EMT and inflammatory markers were analyzed using Western blot, qRT-PCR, immunofluorescence, and hematoxylin and eosin staining. Additionally, the oxidative stress indicator malondialdehyde and glutathione expression were monitored to assess the oxidative stress response. In vitro experiments, TGF-β2, and H2O2 were used to treat lens epithelial cells to induce EMT and oxidative stress models, respectively. These models were employed to explore the effects of MFD and investigate its underlying mechanisms.

Results

Compared to the model group, the group treated with anterior chamber MFD injection effectively suppressed inflammation, oxidative stress, and fibrotic responses within the capsular bag after ECLE and partially inhibited the downregulation of the epithelial marker E-cadherin. To further elucidate the underlying mechanisms, we discovered that MFD treatment in vitro remarkably reduced inflammation, decreased the production of reactive oxygen species, and suppressed the phosphorylation of TGF-β/SMAD as well as MAPK/ERK, thereby inhibiting the occurrence of EMT.

Conclusions

Our findings substantiate the efficacy of MFD in treating PCO and provide insights into its potential mechanisms of action.

Binding with HSP90β, cimifugin ameliorates fibrotic cataracts in vitro and in vivo by inhibiting TGFβ signaling pathways

Fibrotic cataracts, the most frequent complications after phacoemulsification, cannot be cured by drugs in clinic. The primary mechanism underlying the disease is the epithelial-mesenchymal transition (EMT). Cimifugin is a natural monomer component of traditional Chinese medicines. Previous researches have demonstrated the effect of cimifugin inhibiting EMT in the lung. The purpose of this work is to evaluate the impact of cimifugin on EMT in the lens and elucidate its precise mechanism. The pathogenesis of fibrotic cataracts was simulated using TGFβ2-induced cell model of EMT and the injury-induced anterior subcapsular cataract animal model. Through H&E staining and immunofluorescence of mice eyeballs, we discovered that cimifugin can inhibit the expansion of fibrotic lesions in vivo. Furthermore, at mRNA and protein levels, we confirmed that cimifugin can allay EMT of lens epithelial cells (LECs) in vitro and in vivo. Additionally, the inhibition of cimifugin on the activation of TGFβ-related signaling pathways was certified by immunoblot. HSP90β, the target of cimifugin, was predicted by network pharmacology and verified by drug affinity responsive target stability, the cellular thermal shift assay, and microscale thermophoresis. Moreover, co-immunoprecipitation revealed the interaction between HSP90β and TGFβ receptor (TGFβR) II. Together, our findings showed that by weakening the binding of HSP90β and TGFβRII, cimifugin suppressed the TGFβ signaling pathways to alleviate fibrotic cataracts. Cimifugin is a promising medication for the treatment of fibrotic cataracts.

Circ_0000099/miR-223-3p/CTGF Regulates the Growth, Metastasis, and EMT Processes in TGF-β2-Stimulated Human Lens Epithelial Cells

PURPOSE

Posterior capsule opacification (PCO) is the major complication of visual impairment after cataract surgery. Circular RNAs (circRNAs) are involved in the development of many diseases. The purpose of this study was to explore the role and molecular mechanism of circ_0000099 in PCO.

METHODS

SRA01/04 cells were treated with TGF-β2 to establish a PCO cell model. The expression of circ_0000099, miR-223-3p, and connective tissue growth factor (CTGF) mRNA was determined by real-time quantitative polymerase chain reaction (qRT-PCR). Western blot assay was used to analyze the protein expression. Cell proliferation, migration, and invasion were analyzed by (4-5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), 5-ethynyl-2 '-Deoxyuridine (EdU), transwell, and wound healing tests. The circ_0000099/miR-223-3p/CTGF relationship was verified by dual luciferase reporter gene and RNA binding protein immunoprecipitation (RIP) assays.

RESULTS

TGF-β2 treatment promoted SRA01/04 cell proliferation invasion, migration, and EMT. Circ_0000099 expression was increased in POC patients and TGF-β2-treated SRA01/04 cells.Knockdown of circ_0000099 suppressed TGF-β2-induced proliferation, invasion, migration, and EMT in SRA01/04 cells. miR-223-3p was identified as the target of circ_0000099, and miR-223-3p inhibitor might partly abolish the repression of circ_0000099 silencing on TGF-β2-triggered SRA01/04 cell disorders. MiR-223-3p directly targeted CTGF. Knockdown of CTGF suppressed TGF-β2-induced SRA01/04 cell injury. Circ_0000099 can regulate CTGF expression by targeting miR-223-3p.

CONCLUSIONS

Circ_0000099 silencing might relieve TGF-2-induced SRA01/04 cell injury by the miR-223-3p/CTGF axis, providing new avenues for the prevention and treatment of PCO.

Targeting PYK2, entrectinib allays anterior subcapsular cataracts in mice by regulating TGFβ2 signaling pathway

BACKGROUND

Fibrosis cataract occurs in patients receiving cataract extraction. Still, no medication that can cure the disease exists in clinical. This study aims to investigate the effects and mechanisms of Entrectinib on fibrotic cataract in vitro and in vivo.

METHODS

The human lens cells line SRA 01/04 and C57BL/6J mice were applied in the study. Entrectinib was used in animals and cells. Cataract severity was assessed by slit lamp and Hematoxylin and Eosin staining. Expression of alpha-smooth muscle actin, fibronectin, and collagen I were examined by real-time quantitative PCR, western blotting, and immunofluorescence. Cell proliferation was evaluated by Cell Counting Kit-8. Cell migration was measured by wound healing and transwell assays. Molecular docking, Drug Affinity Responsive Target Stability, and Cellular Thermal Shift Assay were applied to seek and certify the target of Entrectinib treating fibrosis cataract.

RESULTS

Entrectinib can ameliorate fibrotic cataract in vitro and in vivo. At the RNA and the protein levels, the expression of alpha-smooth muscle actin, collagen I, and fibronectin can be downgraded by Entrectinib, while E-cadherin can be upregulated. The migration and proliferation of cells were inhibited by Entrectinib. Mechanistically, Entrectinib obstructs TGFβ2/Smad and TGFβ2/non-Smad signaling pathways to hinder the fibrosis cataract by targeting PYK2 protein.

CONCLUSIONS

Targeting with PYK2, Entrectinib can block TGF-β2/Smad and TGF-β2/non-Smad signaling pathways, lessen the activation of EMT, and alleviate fibrosis cataract. Entrectinib may be a potential treatment for fibrosis cataract in clinic.

[Conbercept reverses TGF-β2-induced epithelial-mesenchymal transition in human lens epithelial cells by regulating the TGF-β/Smad signaling pathway]

OBJECTIVE

To investigate the mechanism by which conbercept reverses transforming growth factor-β2 (TGF-β2)-induced epithelial-mesenchymal transition (EMT) in human lens epithelial cells (HLECs).

METHODS

Cultured HLEC SRA01/04 cells were treated with TGF-β2, conbercept, or both, and the changes in cell proliferation, apoptosis, and migration were observed using MTT assay, flow cytometry, scratch assay, and Transwell assay. Western blotting and qRT-PCR were used to detect the changes in the expression of EMT-related epithelial cell markers (E-Cadherin, α-SMA, and Snail), extracellular matrix components, and genes related to the TGF-β/Smad signaling pathway.

RESULTS

Conbercept significantly reduced TGF-β2-induced EMT of SRA01/04 cells, decreased the expression levels of mesenchymal and extracellular matrix markers α-SMA, Snail, collagen I, collagen IV, and FN1, and upregulated the protein and mRNA expressions of E-cadherin (P <0.05). Transwell assay showed significantly lower cell migration ability in TGF-β2+conbercept group than in TGF-β2 group (P <0.05). Conbercept also inhibited the increase in Smad2/3 phosphorylation levels in HLEC-SRA01/04 cells with TGF-β2-induced EMT (P <0.01).

CONCLUSION

Conbercept inhibits TGF-β2 induced EMT by downregulating the expression of pSmad2/3 in TGF-β/Smad signaling pathway, indicating a potential therapeutic strategy against visual loss induced by posterior capsule opacification.

Evaluation of nintedanib efficacy: Attenuating the lens fibrosis in vitro and vivo

PURPOSE

Organ fibrosis is a huge challenge in clinic. There are no drugs for fibrotic cataracts treatments in clinic. Nintedanib is approved by the FDA for pulmonary fibrosis treatments. This study aims to investigate the efficacy and mechanism of nintedanib on fibrotic cataracts.

METHODS

Drug efficacy was validated through TGFβ2-induced cell models and injury-induced anterior subcapsular cataract (ASC) mice. A slit lamp and the eosin staining technique were applied to access the degree of capsular fibrosis. The CCK-8 assay was used to evaluate the toxicity and anti-proliferation ability of the drug. The cell migration was determined by wound healing assay and transwell assay. The anti-epithelial mesenchymal transition (EMT) and anti-fibrosis efficacy were evaluated by qRT-PCR, immunoblot, and immunofluorescence. The inhibition of nintedanib to signaling pathways was certified by immunoblot.

RESULTS

Nintedanib inhibited the migration and proliferation of TGFβ2-induced cell models. Nintedanib can also repress the EMT and fibrosis of the lens epithelial cells. The intracameral injection of nintedanib can also allay the anterior subcapsular opacification in ASC mice. The TGFβ2/ Smad and non-Smad signaling pathways can be blocked by nintedanib in vitro and in vivo.

CONCLUSION

Nintedanib alleviates fibrotic cataracts by suppressing the TGFβ2/ Smad and non-Smad signaling pathways. Nintedanib is a potential drug for lens fibrosis.

Consilience and unity in ocular anterior segment research

In his beautiful book, Consilience: The Unity of Knowledge, the eminent biologist Edward O Wilson, advocates the need for integration and reconciliation across the sciences. He defines consilience as "literally a 'jumping together' of knowledge with a linking of facts ... to create a common groundwork of explanation". It is the premise of this paper that as much as basic biomedical research is in need of data generation using the latest available techniques- unifying available knowledge is just as critical. This involves the necessity to resolve contradictory findings, reduce silos, and acknowledge complexity. We take the cornea and the lens as case studies of our premise. Specifically, in this perspective, we discuss the conflicting and fragmented information on protein aggregation, oxidative damage, and fibrosis. These are fields of study that are integrally tied to anterior segment research. Our goal is to highlight the vital need for Wilson's consilience and unity of knowledge which in turn should lead to enhanced rigor and reproducibility, and most importantly, to greater understanding and not simply knowing.

A 3D in vitro model for assessing the influence of intraocular lens: Posterior lens capsule interactions on lens epithelial cell responses

Posterior Capsule Opacification (PCO), the most frequent complication of cataract surgery, is caused by the infiltration and proliferation of lens epithelial cells (LECs) at the interface between the intraocular lens (IOL) and posterior lens capsule (PLC). According to the "no space, no cells, no PCO" theory, high affinity (or adhesion force) between the IOL and PLC would decrease the IOL: PLC interface space, hinder LEC migration, and thus reduce PCO formation. To test this hypothesis, an in vitro hemisphere-shaped simulated PLC (sPLC) was made to mimic the human IOL: PLC physical interactions and to assess their influence on LEC responses. Three commercially available IOLs with different affinities/adhesion forces toward the sPLC, including Acrylic foldable IOL, Silicone IOL, and PMMA IOL, were used in this investigation. Using the system, the physical interactions between IOLs and sPLC were quantified by measuring the adhesion force and interface space using an adhesion force apparatus and Optical Coherence Tomography, respectively. Our data shows that high adhesion force and tight binding between IOL and sPLC contribute to a small interface space (or "no space"). By introducing LECs into the in vitro system, we found that, with small interface space, among all IOLs, acrylic foldable IOLs permitted the least extent of LEC infiltration, proliferation, and differentiation (or "no cells"). Further statistical analyses using clinical data revealed that weak LEC responses are associated with low clinical PCO incidence rates (or "no PCO"). The findings support that the in vitro system could simulate IOL: PLC interplays and predict IOLs' PCO potential in support of the "no space, no cells, no PCO" hypothesis.

GDF-15 Attenuates the Epithelium-Mesenchymal Transition and Alleviates TGFβ2-Induced Lens Opacity

Purpose

We sought to evaluate the efficacy of growth differentiation factor (GDF)-15 treatment for suppressing epithelial-mesenchymal transition (EMT) and alleviating transforming growth factor β2 (TGFβ2)-induced lens opacity.

Methods

To test whether GDF-15 is a molecule that prevents EMT, we pretreated the culture with GDF-15 in neural progenitor cells, retinal pigment epithelial cells, and lens epithelial cells and then treated with factors that promote EMT, GDF-11, and TGFβ2, respectively. To further investigate the efficacy of GDF-15 on alleviating lens opacity, we used mouse lens explant culture to mimic secondary cataracts. We pretreated the lens culture with GDF-15 and then added TGFβ2 to develop lens opacity (n = 3 for each group). Western blot and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to measure EMT protein and gene expression, respectively.

Results

In cell culture, GDF-15 pretreatment significantly attenuated EMT marker expression in cultured cells induced by treatment with GDF-11 or TGFβ2. In the lens explant culture, GDF-15 pretreatment also reduced mouse lens opacity induced by exposure to TGFβ2.

Conclusions

Our results indicate that GDF-15 could alleviate TGFβ2-induced EMT and is a potential therapeutic agent to slow or prevent posterior capsular opacification (PCO) progression after cataract surgery.

Translational Relevance

Cataracts are the leading cause of blindness worldwide, with the only current treatment involving surgical removal of the lens and replacement with an artificial lens. However, PCO, also known as secondary cataract, is a common complication after cataract surgery. The development of an adjuvant that slows the progression of PCO will be beneficial to the field of anterior complications.

MicroRNA-1225-5p Promotes the Development of Fibrotic Cataracts via Keap1/Nrf2 Signaling

PURPOSE

Fibrotic cataracts, including anterior subcapsular cataract (ASC) as well as posterior capsule opacification (PCO), are a common vision-threatening cause worldwide. Still, little is known about the underlying mechanisms. Here, we demonstrate a miRNA-based pathway regulating the pathological fibrosis process of lens epithelium.

METHODS

Gain- and loss-of-function approaches, as well as multiple fibrosis models of the lens, were applied to validate the crucial role of two miR-1225 family members in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice.

RESULTS

Both miR-1225-3p and miR-1225-5p prominently stimulate the migration and EMT process of lens epithelial cells (LECs) in vitro as well as lens fibrosis in vivo. Moreover, we demonstrated that the underlying mechanism for these effects of miR-1225-5p is via directly targeting Keap1 to regulate Keap1/Nrf2 signaling. In addition, evidence showed that Keap1/Nrf2 signaling is activated in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice, and inhibition of the Nrf2 pathway can significantly reverse the process of LECs EMT as well as lens fibrosis.

CONCLUSIONS

These results suggest that blockade of miR-1225-5p prevents lens fibrosis via targeting Keap1 thereby inhibiting Nrf2 activation. The 'miR-1225-Keap1-Nrf2' signaling axis presumably holds therapeutic promise in the treatment of fibrotic cataracts.

miR-26 Deficiency Causes Alterations in Lens Transcriptome and Results in Adult-Onset Cataract

Purpose

Despite strong evidence demonstrating that normal lens development requires regulation governed by microRNAs (miRNAs), the functional role of specific miRNAs in mammalian lens development remains largely unexplored.

Methods

A comprehensive analysis of miRNA transcripts in the newborn mouse lens, exploring both differential expression between lens epithelial cells and lens fiber cells and overall miRNA abundance, was conducted by miRNA sequencing. Mouse lenses lacking each of three abundantly expressed lens miRNAs (miR-184, miR-26, and miR-1) were analyzed to explore the role of these miRNAs in lens development.

Results

Mice lacking all three copies of miR-26 (miR-26TKO) developed postnatal cataracts as early as 4 to 6 weeks of age. RNA sequencing analysis of neonatal lenses from miR-26TKO mice exhibited abnormal reduced expression of a cohort of genes found to be lens enriched and linked to cataract (e.g., Foxe3, Hsf4, Mip, Tdrd7, and numerous crystallin genes) and abnormal elevated expression of genes related to neural development (Lhx3, Neurod4, Shisa7, Elavl3), inflammation (Ccr1, Tnfrsf12a, Csf2ra), the complement pathway, and epithelial to mesenchymal transition (Tnfrsf1a, Ccl7, Stat3, Cntfr).

Conclusions

miR-1, miR-184, and miR-26 are each dispensable for normal embryonic lens development. However, loss of miR-26 causes lens transcriptome changes and drives cataract formation.

RASFF1A inhibits the epithelial-mesenchymal transition of lens epithelial cells induced by TGFβ through regulating HDAC6

To explore the role of Ras-association domain family 1 A (RASSF1A) in TGFβ2-induced changes of lens epithelial cells (LECs) behavior. The human LEC line SRA01/04 cells were treated with TGFβ2 in the presence or absence of RASSF1A and histone deacetylase 6 (HDAC6). qRT-PCR and western blot were performed to analysis mRNA and proteins expression. Cell proliferation was evaluated using MTT assay and colony formation assay. Transwell and scratch-wound healing assays were conducted to detected cell migration ability. RASSF1A was downregulated in TGFβ2-induced SRA01/04 cells. RASSF1A overexpression inhibited the cell viability, colony formation and migration abilities of SRA01/04 cells induced by TGFβ2. Overexpression of RASSF1A suppressed TGFβ2-induced EMT of SRA01/04 cells, which was manifested as inhibition of EMT-related proteins α-SMA, Vimentin, Snail and Fn expression. Moreover, RASSF1A down-regulated the expression of HDAC6. Importantly, HDAC6 reversed the effects of RASSF1A on SRA01/04 cells. These findings indicate that RASSF1A prevented TGFβ2-induced proliferation, migration, and EMT of LECs by regulating HDAC6 expression, suggesting that RASSF1A holds promise as a potential target for cataracts treatment.

Let-7c-3p suppresses lens epithelial-mesenchymal transition by inhibiting cadherin-11 expression in fibrotic cataract

Fibrotic cataract, including anterior subcapsular cataract (ASC) and posterior capsule opacification, always lead to visual impairment. Epithelial-mesenchymal transition (EMT) is a well-known event that causes phenotypic alterations in lens epithelial cells (LECs) during lens fibrosis. Accumulating studies have demonstrated that microRNAs are important regulators of EMT and fibrosis. However, the evidence explaining how microRNAs modulate the behavior and alter the cellular phenotypes of the lens epithelium in fibrotic cataract is insufficient. In this study, we found that hsa-let-7c-3p is downregulated in LECs in human ASC in vivo as well as in TGFβ2-induced EMT in vitro, indicating that hsa-let-7c-3p may participate in modulating the profibrotic processes in the lens. We then demonstrated that overexpression of hsa-let-7c-3p markedly suppressed human LEC proliferation and migration and attenuated TGFβ2-induced EMT and injury-induced ASC in a mouse model. In addition, hsa-let-7c-3p mediated lens fibrosis by directly targeting the CDH11 gene, which encodes cadherin-11 protein, an important mediator in the EMT signaling pathway. It decreased cadherin-11 protein expression at the posttranscriptional level but not at the transcriptional level by binding to a specific site in the 3-untranslated region (3'-UTR) of CDH11 mRNA. Moreover, blockade of cadherin-11 expression with a specific short hairpin RNA reversed TGFβ2-induced EMT in LECs in vitro. Collectively, these data demonstrated that hsa-let-7c-3p plays a clear role in attenuating ASC development and may be a novel candidate therapeutic for halting fibrosis and maintaining vision.

Lack of Elevated Expression of TGFβ3 Contributes to the Delay of Epithelial Wound Healing in Diabetic Corneas

Purpose

To investigate the mechanisms underlying the differential roles of TGFβ1 and TGFβ3 in accelerating corneal epithelial wound healing (CEWH) in diabetic (DM) corneas, with normoglycemia (NL) corneas as the control.

Methods

Two types of diabetic mice, human corneal organ cultures, mouse corneal epithelial progenitor cell lines, and bone marrow-derived macrophages (BMDMs) were employed to assess the effects of TGFβ1 and TGFβ3 on CEWH, utilizing quantitative PCR, western blotting, ELISA, and whole-mount confocal microscopy.

Results

Epithelial debridement led to an increased expression of TGFβ1 and TGFβ3 in cultured human NL corneas, but only TGFβ1 in DM corneas. TGFβ1 and TGFβ3 inhibition was significantly impeded, but exogenous TGFβ1 and, more potently, TGFβ3 promoted CEWH in cultured TKE2 cells and in NL and DM C57BL6 mouse corneas. Wounding induced similar levels of p-SMAD2/SMAD3 in NL and DM corneas but weaker ERK1/2, Akt, and EGFR phosphorylation in DM corneas compared to NL corneas. Whereas TGFβ1 augmented SMAD2/SMAD3 phosphorylation, TGFβ3 preferentially activated ERK, PI3K, and EGFR in healing DM corneas. Furthermore, TGFβ1 and TGFβ3 differentially regulated the expression of S100a9, PAI-1, uPA/tPA, and CCL3 in healing NL and DM corneas. Finally, TGFβ1 induced the expression of M1 macrophage markers iNOS, CD86, and CTGF, whereas TGFβ3 promoted the expression of M2 markers CD206 and NGF in BMDMs from db/db or db/+ mice.

Conclusions

Hyperglycemia disrupts the balanced expression of TGFβ3/TGFβ1, resulting in delayed CEWH, including impaired sensory nerve regeneration in the cornea. Supplementing TGFβ3 in DM wounds may hold therapeutic potential for accelerating delayed wound healing in diabetic patients.

A bibliometric and visualized analysis of the pathogenesis of cataracts from 1999 to 2023

Research on the pathogenesis of cataracts is ongoing and the number of publications on this topic is increasing annually. This study offers an overview of the research status, popular topics, and scholarly tendencies in the field of cataract pathogenesis over recent decades，which helps to guide future research directions, and optimize resource allocation. In the present study, we performed a bibliometric analysis of cataract pathogenesis. Publications from January 1, 1999, to December 20, 2023, were collected from the Web of Science Core Collection (WoSCC), and the extracted data were quantified and analyzed. We analyzed and presented the data using Microsoft Excel, VOSviewer, CiteSpace, and Python. In all, 4006 articles were evaluated based on various characteristics, including publication year, authors, countries, institutions, journals, citations, and keywords. This study utilized VOSviewer to conduct visualized analysis, including co-authorship, co-citation, co-occurrence, and network visualization. The CiteSpace software was used to identify keywords with significant bursts of activity. The number of annual global publications climbed from 76 to 277 between 1999 and 2023, a 264.47% rise. Experimental Eye Research published the most manuscripts (178 publications), whereas Investigative Ophthalmology & Visual Science received the most citations (6675 citations). The most influential and productive country, institution, and author were the United States (1244 publications, 54,456 citations), University of California system (136 publications, 5401 citations), and Yao Ke (49 publications, 838 citations), respectively. The top 100 ranked keywords are divided into four clusters through co-occurrence analysis: (1) secondary cataracts, (2) oxidative stress, (3) gene mutations and protein abnormalities, and (4) alteration of biological processes in lens epithelial cells. Further discussions on the four subtopics outline the research topics and trends. In conclusion, the specific mechanism of cataract formation remains a popular topic for future research and should be explored in greater depth.

miR-143 promotes cell proliferation, invasion and migration via directly binding to BRD2 in lens epithelial cells

OBJECTIVE

Cataract causes the greatest number of blindnesses worldwide. This study aims to investigate the role of miR-143 in lens epithelial cells.

METHODS

Clustering analysis was conducted to systematically compare miRNA expression levels across cataract and myopia. The levels of miR-143 and Bromodomain containing 2 (BRD2) were determined using real-time quantitative PCR (RT-qPCR) assay in lens epithelial cells. Transwell and wound healing assays were conducted to detect cell invasive and migratory abilities. The regulation relationship between MiR-143 and BRD2 was assessed using dual-luciferase reporter gene assays. BRD2 was knocked down using siRNA-BRD2, and siRNA-BRD2, and miR-143 inhibitors were transfected into cells with lipofectamine 2000.

RESULTS

Through retrieving five databases, 2690 miRNAs were selected. Volcano plot results demonstrated that 200 miRNAs were differentially expressed between cataract and myopia, in which 152 miRNAs were upregulated and 48 miRNAs downregulated in myopia compared with cataract. MiR-143 was upregulated in cataract compared with myopia (P<0.05). MiR-143 inhibitor suppressed the proliferation, invasion and migration of lens epithelial cells (all P<0.05). Luciferase reporter assays confirmed that BRD2 was a miR-143 target gene in SRA01/04 cells. Knockdown of BRD2 promoted SRA01/04 cell proliferation, invasion and migration (all P<0.05). In addition, silencing of BRD2 partially reversed the functions of miR-143 inhibitor on proliferation, invasion and migration (all P<0.05).

CONCLUSION

MiR-143 suppresses lens epithelial cell proliferation, invasion and migration by regulating BRD2, which may support a novel therapeutic strategy for cataract patients.

miR-26 deficiency causes alterations in lens transcriptome and results in adult-onset cataract

Purpose

Despite strong evidence demonstrating that normal lens development requires regulation governed by miRNAs, the functional role of specific miRNAs in mammalian lens development remains largely unexplored.

Methods

A comprehensive analysis of miRNA transcripts in the newborn mouse lens, exploring both differential expression between lens epithelial cells and lens fiber cells and overall miRNA abundance was conducted by miRNA-seq. Mouse lenses lacking each of three abundantly expressed lens miRNAs: miR-184, miR-26 and miR-1 were analyzed to explore the role of these miRNAs in lens development.

Results

Mice lacking all three copies of miR-26 (miR-26TKO) developed postnatal cataracts as early as 4-6 weeks of age. RNA-seq analysis of neonatal lenses from miR-26TKO mice exhibited abnormal reduced expression of a cohort of genes found to be lens-enriched and linked to cataract (e.g. Foxe3, Hsf4, Mip, Tdrd7, and numerous crystallin genes), and abnormal elevated expression of genes related to neural development (Lhx3, Neurod4, Shisa7, Elavl3 ), inflammation (Ccr1, Tnfrsf12a, Csf2ra), the complement pathway, and epithelial to mesenchymal transition (Tnfrsf1a, Ccl7, Stat3, Cntfr).

Conclusion

miR-1, miR-184 and miR-26 are each dispensable for normal embryonic lens development. However, loss of miR-26 causes lens transcriptome changes and drives cataract formation.

Self-assembled coating with a metal-polyphenolic network for intraocular lens modification to prevent posterior capsule opacification

Posterior capsule opacification (PCO) is a main complication after cataract surgery and intraocular lens (IOLs) implantation and is attributed to residual lens epithelial cells (LECs) migrating to the IOL surface and posterior capsules. IOL surface modification has been a newly-developing research filed in recent years; however, the applicability and economical acquisition of modified materials remain unsolved. In this study, we first applied a metal-polyphenolic network coating with a self-assembly technique on the IOL surface by using tannic acid (TA) combined with AlCl3, which are easily acquire and applying on the IOL surface to solve the IOL transmittance affair. Using wound healing and Transwell assay to verify AZD0364 inhibits cell migration (P< 0.05), the lipopolysaccharide-induced macrophage inflammation model to verify pterostilbene (PTE) inhibits the inflammatory reaction (P< 0.01). By optimizes its self-assembly coating parameters and calculating its drug release kinetics, we successfully loaded these two drugs on the coating, named TA (AZD0364/PTE) IOL. Its surface morphology characteristics were analyzed by scanning electron microscope, x-ray photoelectron spectrometer and water contact angle. The optical performance was carefully investigated by optical instruments and equipment (n= 3). Thein vitroresults showed that TA (AZD0364/PTE) IOL can significantly inhibit cell adhesion and acute inflammation (n= 3,P< 0.0001). Importantly, afterin vivoimplantation for 28 d with eight rabbits PCO models in two groups, the TA (AZD0364/PTE) IOL group maintained clear refracting media and decreased the inflammatory reaction compared with the original IOL group (P< 0.05). This study provides a new applicable and economical strategy for preventing PCO and offers a reference for the next generation of IOLs that benefit cataract patients.

Implantation of a capsular tension ring during cataract surgery attenuates predicted remodeling of the post-surgical lens capsule along the visual axis

Introduction: Cataract surgery permanently alters the mechanical environment of the lens capsule by placing a hole in the anterior portion and implanting an intraocular lens (IOL) that has a very different geometry from the native lens. We hypothesized that implant configuration and mechanical interactions with the post-surgical lens capsule play a key role in determining long-term fibrotic remodeling. Methods: We developed the first finite element-growth and remodeling (FE-G&R) model of the post-surgical lens capsule to evaluate how implantation of an IOL with and without a capsular tension ring (CTR) impacted evolving lens capsule mechanics and associated fibrosis over time after cataract surgery. Results: Our models predicted that implantation of a CTR with the IOL into the post-surgical lens capsule reduced the mechanical perturbation, thickening, and stiffening along the visual axis in both the remnant anterior and posterior portions compared to implantation of the IOL alone. Discussion: These findings align with patient studies and suggest that implantation of a CTR with the IOL during routine cataract surgery would attenuate the incidence of visually-debilitating capsule fibrosis. Our work demonstrates that use of such modeling techniques has substantial potential to aid in the design of better surgical strategies and implants.

Lanosterol Synthase Prevents EMT During Lens Epithelial Fibrosis Via Regulating SREBP1

Purpose

Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a predominant pathological process underlying fibrotic cataracts. Here we investigated the role and mechanism of lanosterol synthase (LSS), a key rate-limiting enzyme in sterol biosynthesis, in EMT of LECs.

Methods

Human lens epithelial explants, primary rabbit LECs, and whole rat lenses were treated with TGFβ2. RNA-sequencing was conducted to explore genetic changes during fibrosis of human lens epithelial explants. Loss- and gain-of-function studies were performed in primary LECs to investigate roles and mechanisms of LSS, lanosterol and sterol regulatory element binding transcription protein 1 (SREBP1) in EMT. Rat lenses were applied to evaluate the potential effect of lanosterol on lens fibrosis. Expression of LSS, SREBP1, EMT-related regulators, and markers were analyzed by Western blot, qRT-PCR, or immunofluorescent staining.

Results

LSS and steroid biosynthesis were downregulated in TGFβ2-induced lens fibrosis. LSS inhibition directly triggered EMT by inducing Smad2/3 phosphorylation and nucleus translocation, an overexpression of LSS protected LECs from EMT by inhibiting Smad2/3 activation. Moreover, LSS inhibition decreased the expression of SREBP1, which regulated EMT via intervening TGFβ2/Smad2/3 transduction. Furthermore, lanosterol protected LECs from EMT caused by both TGFβ2 treatment and LSS inhibition via suppressing Smad2/3 activation and maintained lens transparency by preventing fibrotic plaques formation.

Conclusions

We first identified that LSS protected LECs from EMT and played an antifibrotic role to maintain lens transparency. Additionally, lanosterol and sterol biosynthesis regulation might be promising strategies for preventing and treating fibrotic cataracts.

KLF5/MDM2 Axis Modulates Oxidative Stress and Epithelial-Mesenchymal Transition in Human Lens Epithelial Cells: The Role in Diabetic Cataract

Diabetic cataract (DC) is a common cause of visual loss in older diabetic subjects. Krüppel-like factor 5 (KLF5) plays an essential role in migration and the epithelial-mesenchymal transition (EMT) in diverse cells and is involved in oxidative stress. However, the effects of KLF5 on DC remain unknown. This study aimed to examine the biological function of KLF5 in DC and its underlying mechanism. The expression patterns of KLF5 were detected in vivo and in vitro. Then, KLF5 was knocked down in human lens epithelial cells (HLECs) to explore its functional roles and underlying mechanisms. Dual-luciferase reporter assay and chromatin immunoprecipitation analysis were used to detect whether KLF5 could bind the promoter of E3 ubiquitin ligase mouse double minute 2 (MDM2), a key regulator of EMT. Lastly, the regulation of KLF5 in the biological behaviors of HLECs via MDM2 was analyzed. We found a significant increase of KLF5 in the DC lens anterior capsular, diabetic rat lens, and high glucose (HG)-stimulated HLECs. Knockdown of KLF5 inhibited oxidative stress, inflammation, migration, and EMT of HG-stimulated HLECs. KLF5 silencing impeded MDM2 expression and restricted the activation of MARK1/FAK and NF-κB signaling pathways in HLECs under HG condition. Additionally, KLF5 was found to bind the MDM2 promoter and enhance the transcriptional activity of MDM2. The protective effects by silencing KLF5 on HG-cultured HLECs could be offset by MDM2 overexpression. We demonstrated that knockdown of KLF5 alleviated oxidative stress, migration, and EMT of HG-cultured HLECs by regulating MDM2, suggesting a potential therapeutic strategy for DC.

Oxidative stress-induced temporal activation of ERK1/2 phosphorylates coreceptor of Wnt/β-catenin for myofibroblast formation in human lens epithelial cells

Purpose

Posterior capsular opacification (PCO) is the most common complication postcataract surgery, and its underlying mechanisms involve epithelial-mesenchymal transition (EMT) of remnant lens epithelial cells (LECs) in response to drastic changes in stimuli in the intraocular environment, such as oxidative stress and growth factors. Wnt/β-catenin signaling is a major pathway mediating oxidative stress-induced EMT in LECs, but its interplay with other transduction pathways remains little known in the development of PCO. ERK1/2 signaling is the downstream component of a phosphorelay pathway in response to extracellular stimuli (e.g., reactive oxygen species), and its activation regulates multiple cellular processes, including proliferation and EMT. Thus, this study aimed to investigate how ERK1/2 signaling and Wnt/β-catenin pathway crosstalk in oxidative stress-induced EMT in LECs.

Methods

Hydrogen peroxide (H2O2) at 50 μM treatment for 48 h was used to establish a moderate oxidative stress-induced EMT model in LECs. ERK1/2 signaling was inhibited using MEK1/2 inhibitor U0126 at 20 μM. Western blotting was used to quantify protein expression of various biomarkers of EMT and phosphorylated components in ERK1/2 and Wnt/β-catenin signaling. LEC proliferation was determined using an EdU staining assay and expression of proliferating cellular nuclear antigen (PCNA). Subcellular localization of biomarker proteins was visualized with immunofluorescent staining.

Results

Under the moderate level of H2O2-induced EMT in LECs, ERK1/2 signaling was activated, as evidenced by a marked increase in the ratio of phosphorylated ERK1/2 to total ERK1/2 at early (i.e., 5-15 min) and late time points (i.e., 12 h); the canonical Wnt/β-catenin pathway was activated by H2O2 at 48 h. LECs exposed to H2O2 exhibited hyperproliferation and EMT; however, these were restored by inhibition of ERK1/2 signaling demonstrated by reduced DNA synthesis and PCNA expression for cellular proliferation and altered expression of various EMT protein markers, including E-cadherin, α-SMA, and vimentin. More importantly, inhibition of ERK1/2 signaling reduced β-catenin accumulation in the activated Wnt/β-catenin signaling cascade. Specifically, there was significant downregulation in the phosphorylation level of LRP6 at Ser 1490 and GSK-3β at Ser 9, the key coreceptor of Wnt and regulator of β-catenin, respectively.

Conclusions

ERK1/2 signaling plays a crucial role in the moderate level of oxidative stress-induced EMT in LECs. Pharmacologically blocking ERK1/2 signaling significantly inhibited LEC proliferation and EMT. Mechanistically, ERK1/2 signaling regulated Wnt/β-catenin cascade by phosphorylating Wnt coreceptor LRP6 at Ser 1490 in the plasma membrane. These results shed light on a potential molecular switch of ERK1/2 and Wnt/β-catenin crosstalk underlying the development of PCO.

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.

Biomarker Signature in Aqueous Humor Mirrors Lens Epithelial Cell Activation: New Biomolecular Aspects from Cataractogenic Myopia

Inflammatory, vasculogenic, and profibrogenic factors have been previously reported in vitreous (VH) and aqueous (AH) humors in myopic patients who underwent cataract surgery. In light of this, we selected some mediators for AH and anterior-capsule-bearing lens epithelial cell (AC/LEC) analysis, and AH expression was correlated with LEC activation (epithelial-mesenchymal transition and EMT differentiation) and axial length (AL) elongation. In this study, AH (97; 41M/56F) and AC/LEC samples (78; 35M/43F) were collected from 102 patients who underwent surgery, and biosamples were grouped according to AL elongation. Biomolecular analyses were carried out for AH and LECs, while microscopical analyses were restricted to whole flattened AC/LECs. The results showed increased levels of interleukin (IL)-6, IL-8, and angiopoietin-2 (ANG)-2 and decreased levels of vascular endothelium growth factor (VEGF)-A were detected in AH depending on AL elongation. LECs showed EMT differentiation as confirmed by the expression of smooth muscle actin (α-SMA) and transforming growth factor (TGF)-βR1/TGFβ isoforms. A differential expression of IL-6R/IL-6, IL-8R/IL-8, and VEGF-R1/VEGF was observed in the LECs, and this expression correlated with AL elongation. The higher VEGF-A and lower VEGF-D transcript expressions were detected in highly myopic LECs, while no significant changes were monitored for VEGF-R transcripts. In conclusion, these findings provide a strong link between the AH protein signature and the EMT phenotype. Furthermore, the low VEGF-A/ANG-2 and the high VEGF-A/VEGF-D ratios in myopic AH might suggest a specific inflammatory and profibrogenic pattern in high myopia. The highly myopic AH profile might be a potential candidate for rating anterior chamber inflammation and predicting retinal distress at the time of cataract surgery.

ErbBs in Lens Cell Fibrosis and Secondary Cataract

Purpose

TGFβ-induced epithelial-to-myofibroblast transition (EMyT) of lens cells has been linked to the most common vision-disrupting complication of cataract surgery-namely, posterior capsule opacification (PCO; secondary cataract). Although inhibitors of the ErbB family of receptor tyrosine kinases have been shown to block some PCO-associated processes in model systems, our knowledge of ErbB signaling in the lens is very limited. Here, we investigate the expression of ErbBs and their ligands in primary cultures of chick lens epithelial cells (dissociated cell-derived monolayer cultures [DCDMLs]) and how TGFβ affects ErbB function.

Methods

DCDMLs were analyzed by immunofluorescence microscopy and Western blotting under basal and profibrotic conditions.

Results

Small-molecule ErbB kinase blockers, including the human therapeutic lapatinib, selectively inhibit TGFβ-induced EMyT of DCDMLs. Lens cells constitutively express ErbB1 (EGFR), ErbB2, and ErbB4 protein on the plasma membrane and release into the medium ErbB-activating ligand. Culturing DCDMLs with TGFβ increases soluble bioactive ErbB ligand and markedly alters ErbBs, reducing total and cell surface ErbB2 and ErbB4 while increasing ErbB1 expression and homodimer formation. Similar, TGFβ-dependent changes in relative ErbB expression are induced when lens cells are exposed to the profibrotic substrate fibronectin. A single, 1-hour treatment with lapatinib inhibits EMyT in DCDMLs assessed 6 days later. Short-term exposure to lower doses of lapatinib is also capable of eliciting a durable response when combined with suboptimal levels of a mechanistically distinct multikinase inhibitor.

Conclusions

Our findings support ErbB1 as a therapeutic target for fibrotic PCO, which could be leveraged to pharmaceutically preserve the vision of millions of patients with cataracts.

Glutaredoxin 1 protects lens epithelial cells from epithelial-mesenchymal transition by preventing casein kinase 1α S-glutathionylation during posterior capsular opacification

Oxidative stress drives protein S-glutathionylation, which regulates the structure and function of target proteins and is implicated in the pathogenesis of many diseases. Glutaredoxin 1 (Grx1), a cytoplasmic deglutathionylating enzyme, maintains a reducing environment within the cell under various conditions by reversing S-glutathionylation. Grx1 performs a wide range of antioxidant activities in the lens and prevents protein-thiol mixed disulfide accumulation, reducing protein-protein aggregation, insolubilization, and apoptosis of lens epithelial cells. Oxidative stress is related to epithelial-mesenchymal transition (EMT) during posterior capsular opacification (PCO). However, whether Grx1-regulated protein S-glutathionylation plays an essential role in PCO remains unclear. In this study, we revealed that Grx1 expression was decreased in mice following cataract surgery. Furthermore, the absence of Grx1 elevated oxidative stress and protein S-glutathionylation and aggravated EMT in both in vitro and in vivo models. Concurrently, these results could be reversed by Grx1 overexpression. Notably, liquid chromatography-tandem mass spectrometry results showed that casein kinase 1α (CK1α) was susceptible to S-glutathionylation under oxidative stress, and CK1α S-glutathionylation (CK1α-SSG) was mediated at Cys249. The absence of Grx1 upregulated CK1α-SSG, subsequently decreasing the CK1α-induced phosphorylation of β-catenin at Ser45. The consequential downregulation of degradative β-catenin and upregulation of its nuclear translocation activated the Wnt/β-catenin signaling pathway and aggravated EMT. In conclusion, the downregulated expression of Grx1 in mice following cataract surgery aggravated EMT by upregulating the extent of CK1α-SSG. To the best of our knowledge, our study is the first to report how S-glutathionylation regulates CK1α activity under oxidative stress.

FGF-2 Differentially Regulates Lens Epithelial Cell Behaviour during TGF-β-Induced EMT

Fibroblast growth factor (FGF) and transforming growth factor-beta (TGF-β) can regulate and/or dysregulate lens epithelial cell (LEC) behaviour, including proliferation, fibre differentiation, and epithelial–mesenchymal transition (EMT). Earlier studies have investigated the crosstalk between FGF and TGF-β in dictating lens cell fate, that appears to be dose dependent. Here, we tested the hypothesis that a fibre-differentiating dose of FGF differentially regulates the behaviour of lens epithelial cells undergoing TGF-β-induced EMT. Postnatal 21-day-old rat lens epithelial explants were treated with a fibre-differentiating dose of FGF-2 (200 ng/mL) and/or TGF-β2 (50 pg/mL) over a 7-day culture period. We compared central LECs (CLECs) and peripheral LECs (PLECs) using immunolabelling for changes in markers for EMT (α-SMA), lens fibre differentiation (β-crystallin), epithelial cell adhesion (β-catenin), and the cytoskeleton (alpha-tropomyosin), as well as Smad2/3- and MAPK/ERK1/2-signalling. Lens epithelial explants cotreated with FGF-2 and TGF-β2 exhibited a differential response, with CLECs undergoing EMT while PLECs favoured more of a lens fibre differentiation response, compared to the TGF-β-only-treated explants where all cells in the explants underwent EMT. The CLECs cotreated with FGF and TGF-β immunolabelled for α-SMA, with minimal β-crystallin, whereas the PLECs demonstrated strong β-crystallin reactivity and little α-SMA. Interestingly, compared to the TGF-β-only-treated explants, α-SMA was significantly decreased in the CLECs cotreated with FGF/TGF-β. Smad-dependent and independent signalling was increased in the FGF-2/TGF-β2 co-treated CLECs, that had a heightened number of cells with nuclear localisation of Smad2/3 compared to the PLECs, that in contrast had more pronounced ERK1/2-signalling over Smad2/3 activation. The current study has confirmed that FGF-2 is influential in differentially regulating the behaviour of LECs during TGF-β-induced EMT, leading to a heterogenous cell population, typical of that observed in the development of post-surgical, posterior capsular opacification (PCO). This highlights the cooperative relationship between FGF and TGF-β leading to lens pathology, providing a different perspective when considering preventative measures for controlling PCO.

Extracellular HSP90 promotes differentiation of lens epithelial cells to fiber cells by activating LRP1-YAP-PROX1 axis

Capsular residual lens epithelial cells (CRLEC) undergo differentiation to fiber cells for lens regeneration or tansdifferentiation to myofibroblasts leading to posterior capsular opacification (PCO) after cataract surgery. The underlying regulatory mechanism remains unclear. Using human lens epithelial cell lines and the ex vivo cultured rat lens capsular bag model, we found that the lens epithelial cells secrete HSP90α extracellularly (eHSP90) through an autophagy-associated pathway. Administration of recombinant GST-HSP90α protein or its M-domain induces the elongation of rat CRLEC cells with concomitant upregulation of the crucial fiber cell transcriptional factor PROX1and its downstream targets, β- and γ-crystallins and structure proteins. This regulation is abolished by PROX1 siRNA. GST-HSP90α upregulates PROX1 by binding to LRP1 and activating LRP1-AKT mediated YAP degradation. The upregulation of GST-HSP90α on PROX1 expression and CRLEC cell elongation is inhibited by LRP1 and AKT inhibitors, but activated by YAP-1 inhibitor (VP). These data demonstrated that the capsular residue epithelial cells upregulate and secrete eHSP90α, which in turn drive the differentiation of lens epithelial cell to fiber cells. The recombinant HSP90α protein is a potential novel differentiation regulator during lens regeneration.

The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens

The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.

ceRNA network construction and identification of hub genes as novel therapeutic targets for age-related cataracts using bioinformatics

Background

The aim of this study is to investigate the genetic and epigenetic mechanisms involved in the pathogenesis of age-related cataract (ARC).

Methods

We obtained the transcriptome datafile of th ree ARC samples and three healthy, age-matched samples and used differential expression analyses to identify the differentially expressed genes (DEGs). The differential lncRNA-associated competing endogenous (ceRNA) network, and the protein-protein network (PPI) were constructed using Cytoscape and STRING. Cluster analyses were performed to identify the underlying molecular mechanisms of the hub genes affecting ARC progression. To verify the immune status of the ARC patients, immune-associated analyses were also conducted.

Results

The PPI network identified the FOXO1 gene as the hub gene with the highest score, as calculated by the Maximal Clique Centrality (MCC) algorithm. The ceRNA network identified lncRNAs H19, XIST, TTTY14, and MEG3 and hub genes FOXO1, NOTCH3, CDK6, SPRY2, and CA2 as playing key roles in regulating the pathogenesis of ARC. Additionally, the identified hub genes showed no significant correlation with an immune response but were highly correlated with cell metabolism, including cysteine, methionine, and galactose.

Discussion

The findings of this study may provide clues toward ARC pathogenic mechanisms and may be of significance for future therapeutic research.

TGF-β/Smad Signalling Activation by HTRA1 Regulates the Function of Human Lens Epithelial Cells and Its Mechanism in Posterior Subcapsular Congenital Cataract

Congenital cataract is the leading cause of blindness among children worldwide. Patients with posterior subcapsular congenital cataract (PSC) in the central visual axis can result in worsening vision and stimulus deprivation amblyopia. However, the pathogenesis of PSC remains unclear. This study aims to explore the functional regulation and mechanism of HTRA1 in human lens epithelial cells (HLECs). HTRA1 was significantly downregulated in the lens capsules of children with PSC compared to normal controls. HTRA1 is a suppression factor of transforming growth factor-β (TGF-β) signalling pathway, which plays a key role in cataract formation. The results showed that the TGF-β/Smad signalling pathway was activated in the lens tissue of PSC. The effect of HTRA1 on cell proliferation, migration and apoptosis was measured in HLECs. In primary HLECs, the downregulation of HTRA1 can promote the proliferation and migration of HLECs by activating the TGF-β/Smad signalling pathway and can significantly upregulate the TGF-β/Smad downstream target genes FN1 and α-SMA. HTRA1 was also knocked out in the eyes of C57BL/6J mice via adeno-associated virus-mediated RNA interference. The results showed that HTRA1 knockout can significantly upregulate p-Smad2/3 and activate the TGF-β/Smad signalling pathway, resulting in abnormal proliferation and irregular arrangement of lens epithelial cells and leading to the occurrence of subcapsular cataract. To conclude, HTRA1 was significantly downregulated in children with PSC, and the downregulation of HTRA1 enhanced the proliferation and migration of HLECs by activating the TGF-β/Smad signalling pathway, which led to the occurrence of PSC.

Observation of Cyclosporin A: Sustained Release Intraocular Lens Implantation in Rabbit Eyes

PURPOSE

To observe the performance of cyclosporine A (CsA)-loaded intraocular lens (IOLs) implanted into rabbit eyes.

METHODS

To prepare a PLGA-based CsA-sustained release IOLs and study the in vitro drug release. Forty-two New Zealand white rabbits were randomly and equally divided into three groups, and all right eyes underwent phacoemulsification. In group A, a common polymethylmethacrylate (PMMA) IOLs was implanted, while polylactide-glycoli acid (PLGA-loaded)-PMMA-IOLs was implanted in group B, and CsA-PLGA-PMMA-IOLs was implanted in group C. All experimental eyes were examined by slit-lamp microscopy. In addition, fundoscopy and the number of corneal endothelial cells, anterior chamber flare grading, and the number of aqueous humor cells were assessed at different time points post-surgery. The wet lens capsule was weighed and histological examination was performed 6 months post-operation.

RESULTS

In the early post-operative period, the inflammatory reaction of anterior chamber in groups A and B were more severe than group C. The initial appearance of PCO in group C was much later than the other two groups (F = 68.91; p = 0.000), and PCO grade in group C was much lower than the other two groups (χ² = 36.07; p = 0.000). The mean weights of wet lens capsules in groups A and B were significantly heavier than group C (F = 134.88; p = 0.00). Histological observation showed no obvious toxic reaction in the intraocular tissues of the CsA-PLGA-PMMA-IOLs group, and the proliferation and accumulation of lens epithelial cells in groups A and B were greater than in group C.

CONCLUSION

CsA-sustained release IOLs can effectively prevent PCO in rabbit eyes without defined intraocular toxicity.

Bit1 is involved in regulation between integrin and TGFβ signaling in lens epithelial cells

Bit1, as an integrin-specific effector, is specifically expressed in lens epithelial cells (LECs) and may be essential to maintain the normal function of LECs. The present study investigated the function of Bit1 and its regulatory mechanism in LECs. Knockdown of Bit1 was mediated by a lentivirus with a specific short-hairpin RNA against Bit1 in SRA01/04 cells. Cell proliferation ability was measured by CCK-8 assay. Cell migration was examined by transwell and wound-healing assays. The effect of Bit1 knockdown on genome-wide expression patterns was studied via a GeneChip® PrimeView™ Human Gene Expression Array. Based on the ingenuity pathway analysis (IPA), Bit1's regulation of target pathways and genes was verified by real-time qPCR and Western blotting. Bit1 knockdown inhibited proliferation, migration, and regulated cell cycle and apoptosis of LECs. Microarray gene expression analysis and IPA assays revealed that integrin and TGFβ signaling pathways were remarkably impacted by Bit1 expression. FAK, PAK2, ITGA5, and ITGB1 were identified as core node molecules under the control of Bit1. Bit1 participates in integrin and TGFβ signaling via regulating downstream FAK and PAK2 and subsequently affecting EMT-related gene expression including ITGA5, ITGB1, and αSMA. In conclusion, Bit1 plays as an important role in the regulation between integrin and TGFβ signaling, which affects cell survival, migration, and EMT of LECs.

17β-Estradiol Inhibits Oxidative Damage in Cataracts Rats via NOTCH1 Signaling

This study assesses the effect of 17β-estradiol on oxidative damage and NOTCH1 levels in cataract rats. 45 SD rats, aged 8–12 weeks old and weighted 225–312 g were assigned into healthy group, cataract group, and treatment group with n = 15 in each group followed by analysis of the pathological morphology of rat lens by HE staining, cell apoptosis by flow cytometry, and the degree of turbidity under a microscope. Meanwhile, MDA and SOD levels were measured and NOTCH1, p53 and BAX expressions was detected by PT-PCR. The Healthy group rats showed complete and orderly lens structure, whereas, the cataract group showed disorganized and distributed loosely lens, with the formation of vacuoles and the rupture and degradation of fibrocells. In the treatment group, the lens epithelial cells were orderly and evenly distributed, and the vacuoles were significantly reduced. The apoptotic rate of lens epithelial cells in healthy group (1.79±0.11)% was significantly lower than that in cataract group (15.22±1.17)% (P < 0.05), which showed significantly higher apoptotic rate than treatment group (6.31±1.12)% (P < 0.05). The degree of eye turbidity was increased in cataract group and reduced in treatment group compared with that in healthy group (P < 0.05). In addition, cataract group showed significantly reduced SOD and increased MDA level groups along with upregulated Notch1, p53 and Bax (P < 0.05). However, treatment group showed significantly increased SOD, decreased MDA and downregulated Notch1, p53 and Bax. In conclusion, 17β-estradiol reduces the apoptosis rate of lens epithelial cells in cataract rats by reducing NOTCH1 level, thereby enhancing the ability to resist oxidative damage.

IGF-1 Promotes Epithelial-Mesenchymal Transition of Lens Epithelial Cells That Is Conferred by miR-3666 Loss

The abnormal proliferation, migration, and epithelial-mesenchymal transformation (EMT) of lens epithelial cells (LECs) are the main reasons for vision loss caused by posterior capsular opacification (PCO) after cataract surgery. Insulin-like growth factor-1 (IGF-1) was found to be associated with the pathogenesis of cataracts, but its biological role in PCO is poorly understood. In the present study, IGF-1 overexpression facilitated the proliferation, migration, and EMT, whereas knockdown of IGF-1 markedly suppressed the proliferation, migration, and TGF-β2-induced EMT of LECs. Additionally, to evaluate valuable microRNAs (miRNAs) which target IGF-1 to modulate LEC-EMT, we predicted miR-3666 might regulate IGF-1 by binding its 3'UTR according to the bioinformatics database. Furthermore, we verified that miR-3666 directly targeted IGF-1 by luciferase reporter assay. By using miR-3666 mimics, cell proliferation, migration, and invasion were suppressed, while being enhanced by the reduction of miR-3666. Knockout of IGF1 reverses the effect of the miR-3666 inhibitor on the malignant behavior of LECs. These results indicate the role of miR-3666/IGF-1 in LEC-EMT that offers new strategies for the therapy and prevention of PCO.

REPS2 downregulation facilitates FGF-induced adhesion and migration in human lens epithelial cells through FAK/Cdc42 signaling and contributes to posterior capsule opacification

Posterior capsular opacification (PCO) can cause postoperative visual loss after cataract surgery. Residual human lens epithelial cell (HLEC) proliferation, migration, epithelial-mesenchymal transition (EMT) and synthesis of extracellular matrix (ECM) are the entitative reasons for PCO. Low expression of Ral-binding protein 1-associated Eps domain-containing 2 (REPS2) and high levels of basic fibroblast growth factor (b-FGF) were observed in the lens and postoperative aqueous humor of cataract patients. REPS2 was identified as a negative regulator in growth factor signaling; however, its function in HLECs is unknown. This was first investigated in the present study by evaluating REPS2 expression in anterior lens capsules from cataract patients, a mouse cataract model, and HLE-b3 cells. The biological function of REPS2 in HLE-B3 cells was assessed by REPS2 silencing and Cell Counting Kit 8, wound healing, Transwell migration, F-actin staining, G-protein pulldown and western blot assays. In the present study, REPS2 was significantly downregulated in human and mouse cataract capsules and H₂O₂-treated HLE-B3 cells. REPS2 knockdown increased fibronectin, type I collagen, and α-smooth muscle actin expression levels and stimulated HLECs proliferation and migration; these effects were enhanced by FGF treatment and accompanied with focal adhesion kinase (FAK) phosphorylation, cell division cycle 42 (Cdc42) activation, focal adhesion protein upregulation, and F-actin cytoskeleton reorganization. However, treatment with the FAK inhibitor PF573228 abolished these effects. Thus, REPS2 downregulation in cataract HLECs induces their proliferation and facilitates FGF-induced ECM synthesis, EMT, cell adhesion and migration by activating FAK/Cdc42 signaling, which may underlie PCO pathogenesis.

Lens Fibrosis: Understanding the Dynamics of Cell Adhesion Signaling in Lens Epithelial-Mesenchymal Transition

Injury to the ocular lens perturbs cell-cell and cell-capsule/basement membrane interactions leading to a myriad of interconnected signaling events. These events include cell-adhesion and growth factor-mediated signaling pathways that can ultimately result in the induction and progression of epithelial-mesenchymal transition (EMT) of lens epithelial cells and fibrosis. Since the lens is avascular, consisting of a single layer of epithelial cells on its anterior surface and encased in a matrix rich capsule, it is one of the most simple and desired systems to investigate injury-induced signaling pathways that contribute to EMT and fibrosis. In this review, we will discuss the role of key cell-adhesion and mechanotransduction related signaling pathways that regulate EMT and fibrosis in the lens.

MYPT1/PP1-Mediated EZH2 Dephosphorylation at S21 Promotes Epithelial-Mesenchymal Transition in Fibrosis through Control of Multiple Families of Genes

The methyltransferase EZH2 plays an important role in regulating chromatin conformation and gene transcription. Phosphorylation of EZH2 at S21 by AKT kinase suppresses its function. However, protein phosphatases responsible for the dephosphorylation of EZH2-S21 remain elusive. Here, it is demonstrated that EZH2 is highly expressed in the ocular lens, and AKT-EZH2 axis is important in TGFβ-induced epithelial-mesenchymal transition (EMT). More importantly, it is identified that MYPT1/PP1 dephosphorylates EZH2-S21 and thus modulates its functions. MYPT1 knockout accelerates EMT, but expression of the EZH2-S21A mutant suppresses EMT through control of multiple families of genes. Furthermore, the phosphorylation status and gene expression modulation of EZH2 are implicated in control of anterior subcapsular cataracts (ASC) in human and mouse eyes. Together, the results identify the specific phosphatase for EZH2-S21 and reveal EZH2 dephosphorylation control of several families of genes implicated in lens EMT and ASC pathogenesis. These results provide important novel information in EZH2 function and regulation.

Interfering Hsa_circRNA_0060640 Suppresses TGF-β2-Induced Proliferation, Motility and EMT in Human Lens Epithelium Cells by Targeting miR-214-3p and Collagen Type I alpha2 Chain

BACKGROUND

Circular RNA (circRNA) is a novel star factor in the research of ocular diseases including cataract and the most common postoperative complication posterior capsule opacification (PCO). Hsa_circRNA_0060640 (circ_0060640) is an age-related cataract-related circRNA. However, its role in cataractogenesis is unrevealed yet.

METHODS

PCO in vitro model was established in human lens epithelium cells (hLECs) induced by transforming growth factor-beta2 (TGF-β2). RNA and protein expressions were respectively detected by quantitative PCR and western blotting. Direct interaction between two RNAs was predicted by Starbase tool and confirmed by dual-luciferase reporter assay. MTS and EdU assays measured cell proliferation; Transwell, starch wound and western blotting assays evaluated cell motility and epithelial-mesenchymal transition (EMT).

RESULTS

Circ_0060640 expression is higher in anterior lens capsule tissues from human cataractous eyes and TGF-β2-stimulated hLECs cells line SRA01/04. RNA interference of circ_0060640 could prevent SRA01/04 cells from TGF-β2-induced cell proliferation, migration and invasion, accompanied with decreased N-cadherin and α-smooth muscle actin and increased E-cadherin. Mechanistically, circ_0060640 directly controls microRNA (miR)-214-3p expression and then regulates gene expression of collagen type I alpha2 chain (COL1A2). Notably, COL1A2 inhibition is underlying the protective role of circ_0060640 silencing and miR-214-3p ectopic expression in TGF-β2-stimulated SRA01/04 cells.

CONCLUSION

Circ_0060640 is a novel cataract-related gene and its silencing could block TGF-β2-evoked hLECs proliferation, motility and EMT in vitro via targeting miR-214-3p-COL1A2 axis. Therefore, targeting circ_0060640 via RNA interference might be a treatment strategy for PCO development.

Znhit1 Regulates p21Cip1 to Control Mouse Lens Differentiation

Purpose

The transparency of the ocular lens is essential for refracting and focusing light onto the retina, and transparency is controlled by many factors and signaling pathways. Here we showed a critical role of chromatin remodeler zinc finger HIT-type containing 1 (Znhit1) in maintaining lens transparency.

Methods

To explore the roles of Znhit1 in lens development, the cre-loxp system was used to generate lens-specific Znhit1 knockout mice (Znhit1Mlr10-Cre; Znhit1 cKO). Morphological changes in mice lenses were examined using hematoxylin and eosin staining. RNA sequencing (RNA-seq) and assay for transposase accessible chromatin using sequencing (ATAC-seq) were applied to screen transcriptome changes. Immunofluorescence staining were performed to assess proteins distribution and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining were used for determining apoptosis. The mRNAs expression was examined by quantitative RT-PCR and proteins expression by Western blot.

Results

Lens-specific conditional knockout mice had a severe cataract, microphthalmia phenotype, and seriously abnormal lens fiber cells differentiation. Deletion of Znhit1 in the lens resulted in decreased cell proliferation and increased cell apoptosis of the lens epithelia. ATAC-seq showed that Znhit1 deficiency increased chromatin accessibility of cyclin-dependent kinase inhibitors, including p57Kip2 and p21Cip1, and upregulated the expression of these genes in mRNA and protein levels. And we also showed that loss of Znhit1 lead to lens fibrosis by upregulating the expression of p21Cip1.

Conclusions

Our findings suggested that Znhit1 is required for the survival of lens epithelial cells. The loss of Znhit1 leads to the overexpression of p21Cip1, further resulting in lens fibrosis, and impacted the establishment of lens transparency.

Changes in DNA methylation hallmark alterations in chromatin accessibility and gene expression for eye lens differentiation

Background

Methylation at cytosines (mCG) is a well-known regulator of gene expression, but its requirements for cellular differentiation have yet to be fully elucidated. A well-studied cellular differentiation model system is the eye lens, consisting of a single anterior layer of epithelial cells that migrate laterally and differentiate into a core of fiber cells. Here, we explore the genome-wide relationships between mCG methylation, chromatin accessibility and gene expression during differentiation of eye lens epithelial cells into fiber cells.

Results

Whole genome bisulfite sequencing identified 7621 genomic loci exhibiting significant differences in mCG levels between lens epithelial and fiber cells. Changes in mCG levels were inversely correlated with the differentiation state-specific expression of 1285 genes preferentially expressed in either lens fiber or lens epithelial cells (Pearson correlation r = − 0.37, p < 1 × 10^–42). mCG levels were inversely correlated with chromatin accessibility determined by assay for transposase-accessible sequencing (ATAC-seq) (Pearson correlation r = − 0.86, p < 1 × 10^–300). Many of the genes exhibiting altered regions of DNA methylation, chromatin accessibility and gene expression levels in fiber cells relative to epithelial cells are associated with lens fiber cell structure, homeostasis and transparency. These include lens crystallins (CRYBA4, CRYBB1, CRYGN, CRYBB2), lens beaded filament proteins (BFSP1, BFSP2), transcription factors (HSF4, SOX2, HIF1A), and Notch signaling pathway members (NOTCH1, NOTCH2, HEY1, HES5). Analysis of regions exhibiting cell-type specific alterations in DNA methylation revealed an overrepresentation of consensus sequences of multiple transcription factors known to play key roles in lens cell differentiation including HIF1A, SOX2, and the MAF family of transcription factors.

Conclusions

Collectively, these results link DNA methylation with control of chromatin accessibility and gene expression changes required for eye lens differentiation. The results also point to a role for DNA methylation in the regulation of transcription factors previously identified to be important for lens cell differentiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13072-022-00440-z.

Curcumin suppresses TGF-β2-induced proliferation, migration, and invasion in lens epithelial cells by targeting KCNQ1OT1/miR-377-3p/COL1A2 axis in posterior capsule opacification

BACKGROUND

Posterior capsule opacification (PCO) is a common complication after cataract surgery, which can lead to secondary loss of vision. Curcumin has been reported to play a suppressive role in PCO progression, and the potential molecular mechanism was explored in this study.

METHODS

Cell viability and proliferation were analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 5-Ethynyl-2'-deoxyuridine (EdU) assay. Transwell assay and wound healing assay were performed to assess cell invasion and migration abilities. Western blot assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were conducted to measure the expression of proteins and RNAs. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to confirm the interaction between microRNA-377-3p (miR-377-3p) and KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) or collagen type I alpha 2 chain (COL1A2).

RESULTS

Curcumin dose-dependently alleviated transforming growth factor-β2 (TGF-β2)-induced proliferation, migration, and invasion in SRA01/04 cells. KCNQ1OT1 was up-regulated in PCO patients and TGF-β2-induced SRA01/04 cells. Curcumin-induced protective effects in TGF-β2-induced SRA01/04 cells were largely overturned by KCNQ1OT1 overexpression. KCNQ1OT1 directly interacted with miR-377-3p and negatively regulated its expression. miR-377-3p silencing overturned Curcumin-mediated protective effects in SRA01/04 cells upon TGF-β2 treatment. miR-377-3p directly interacted with the 3' untranslated region (3'UTR) of COL1A2. COL1A2 overexpression largely counteracted KCNQ1OT1 silencing-induced effects in TGF-β2-stimulated SRA01/04 cells. KCNQ1OT1 could up-regulate COL1A2 expression by sponging miR-377-3p in SRA01/04 cells.

CONCLUSION

In conclusion, Curcumin suppressed TGF-β2-induced malignant changes in lens epithelial cells by targeting KCNQ1OT1/miR-377-3p/COL1A2 axis.

TRPM7 Elicits Proliferation and Differentiation of Human Lens Epithelial Cells through the TGF-β/Smad Pathways

Epithelial-mesenchymal transition (EMT) plays a crucial role in the development of cataract. This study aimed to explore the effects of TRPM7 on the proliferation and differentiation of human lens epithelial cells. TRPM7 was over-expressed in LECs treated with TGF-β2. Down-regulation of TRPM7 attenuated the increase in cell viability and cell proliferation induced by TGF-β2. The LEC migration induced by TGF-β2 was also repressed by down-regulation of TRPM7. Epithelial-specific protein E-cadherin was up-regulated through knock-down of TRPM7. EMT-specific proteins, α-SMA, fibronectin and vimentin, were down-regulated through knockdown of TRPM7. Moreover, phosphorylation of Smad2 and Smad3 was also prevented by inhibition of TRPM7. Therefore, TRPM7 elicited LEC proliferation and EMT through enhancing activation of the TGF-β/Smad pathways, implying a new therapeutic target for cataract.

[Pirfenidone inhibits proliferation of rabbit tenon fibroblasts by down-regulating TGF-β3 in the TGF-β/Smad pathway]

OBJECTIVE

To investigate the molecular mechanism by which pirfenidone inhibits scar formation through the TGF-β/Smad pathway.

METHODS

Cultured rabbit tenon fibroblasts (RTFs) were treated with different concentrations of pirfenidone to determine its initial active concentration and optimum concentration of pirfenidone for inhibiting RTF proliferation using CCK-8 assay. In RTFs treated with pirfenidone at the initial and optimal concentrations, expressions of TGF-β3, collagen I and collagen III were examined with both immunofluorescence assay and Western blotting, and their mRNA expression levels were detected using RT-PCR.

RESULTS

The initial and optimal concentrations of pirfenidone for inhibiting RTF proliferation were 0.1 mg/mL and 0.27 mg/mL, respectively. In RTFs treated with pirfenidone at the two concentrations for 24 h, both immunofluorescence assay and Western blotting showed significantly lowered protein expressions of TGF-β3, collagen I and collagen III as compared with those in the control group (P < 0.05). The mRNA expressions of TGF-β3, collagen I and collagen III in the RTFs were also significantly lowered after treatment with pirfenidone at the initial and optimal concentrations (P < 0.05).

CONCLUSIONS

Pirfenidone concentration-dependently inhibits the proliferation of RTFs possibly by down-regulating the expression of TGF-β3 in the TGF-β/Smad pathway.