Attenuation of human lens epithelial cell spreading, migration and contraction via downregulation of the PI3K/Akt pathway

Network Pharmacology-Based Strategy to Reveal the Mechanism of Cassiae Semen against Cataracts

Cassiae semen (CS) is one of the most well-known herbs used in the treatment of cataracts in China. However, the potential mechanisms of its anticataract effects have not been fully explored. In this study, network pharmacology was used to investigate the potential mechanism underlying the actions of CS against cataracts, and molecular docking was performed to analyze the binding activity of proteins and compounds. qPCR was performed to detect the mRNA level of genes, and the cell apoptotic rate was measured using flow cytometry. We identified 13 active compounds from CS and 105 targets, as well as 238 cataract-related targets. PPI networks were constructed, and fifty key targets were obtained. These key targets were enriched in the regulation of transcription, apoptotic process, and signal transduction pathways. Molecular docking demonstrated that the compounds of CS exhibited good affinity to some critical targets. Furthermore, CS prevented the apoptosis of human lens epithelial cells induced by UVB lights by decreasing the gene expression of CASP3, ESR1, and TP53 and increasing the CRYAB gene expression. The present study attempted to explain the mechanisms for the effects of CS in the prevention and treatment of cataracts and provided an effective strategy to investigate active ingredients from natural medicines. Further studies are required to verify these findings via in vivo and in vitro experiments.

miRNA-26b suppresses the TGF-β2-induced progression of HLE-B3 cells via the PI3K/Akt pathway

AIM

To study the effect of miR-26b on lens epithelial cells induced by transforming growth factor beta (TGF-β) 2 and the underlying signaling pathways.

METHODS

Human lens epithelial cell line B-3 (HLE-B3) was incubated with TGF-β2 (5 ng/mL) and then transfected with miR-26b mimics. The expression of miR-26b was determined using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), while 5'-bromodeoxyuridine (BrdU) and wound-healing assays were used to measure the growth and migration of HLE-B3 cells, respectively. The expression of epithelial-mesenchymal transition (EMT) markers and the activity of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway were measured by Western blotting assay and immunofluorescence staining. Electron microscopy was also used to observe cellular morphology.

RESULTS

The expression levels of miR-26b were significantly reduced in human posterior capsular opacification-attached lens tissue and TGF-β2-stimulated HLE-B3 cells. In the presence of TGF-β2, the growth, migration, and EMT of HLE-B3 cells were distinctly enhanced; these effects were attenuated by the administration of miR-26b mimics. Furthermore, the overexpression of miR-26b significantly reduced upregulation of the PI3K/Akt pathway when stimulated by TGF-β2 in HLE-B3 cells. Moreover, the addition of an activator (740 Y-P) led to the upregulation of the PI3K/Akt pathway and abolished the protective effect of miR-26b on the HLE-B3 cells that was mediated by TGF-β2.

CONCLUSION

The miR-26b suppresses TGF-β2-induced growth, migration, and EMT in HLE-B3 cells by regulating the PI3K/Akt signaling pathway.

Cross-talk of Signaling Pathways in the Pathogenesis of Allergic Asthma and Cataract

Allergic asthma is a chronic inflammatory disease, which involves many cellular and cellular components. Cataract is a condition that affects the transparency of the lens, which the opacity of the lens caused by any innate or acquired factor degrades its transparency or changes in color. Both of them belong to diseases induced by immune disorders or inflammation. We want to confirm the signaling pathways involved in the regulation of asthma and cataract simultaneously, and provide reference for the later related experiments. So we conducted a scoping review of many databases and searched for studies (Academic research published in Wiley, Springer and Bentham from 2000 to 2019) about the possible relationship between asthma and cataract. It was found that during the onset of asthma and cataract, Rho/Rock signaling pathway, Notch signaling pathway, Wnt/β-catenin signaling pathway, PI3K/AKT signaling pathway, JAK/STAT signaling pathway, MAPK signaling pathway, TGF-β1/Smad signaling pathway and NF-κB signaling pathway are all active, so they may have a certain correlation in pathogenesis. Asthma may be associated with cataract through the eight signaling pathways, causing inflammation or immune imbalance based on allergy that can lead to cataract. According to these studies, we speculated that the three most likely signaling pathways are PI3K/AKT, MAPK and NF-κB signaling pathway.

A Critical Appraisal of New Developments in Intraocular Lens Modifications and Drug Delivery Systems for the Prevention of Cataract Surgery Complications

Cataract surgery is the commonest ophthalmic surgery worldwide. The replacement of the diseased lens with a synthetic one (intraocular lens-IOL) remains the treatment of choice, despite its potential complications that include infection, inflammation and posterior capsule opacification. The potential for drug delivery via the IOL has been researched extensively over a period of twenty-five years, yet there is very limited progress in transferring the findings from research to everyday practice. The objective of this review is to assess the progress made in the field of IOL lens modifications and drug delivery systems over the past five years. Thirty-six studies that were conducted during the past five years were identified and deemed suitable for inclusion. They were grouped in three broad categories, studies that described new methods for loading a drug onto the IOL, assessment of the effects of drugs that were loaded to the IOL and studies that assessed the effects of non-pharmaceutical modifications of IOLs. While considerable progress is continually being made with regard to methods and materials, there is still little capitalization upon these research studies, with no commercially available IOL-based drug delivery system being available. Close cooperation between researchers in basic sciences (chemistry, physics, materials science and pharmacy), clinical researchers, IOL manufacturers and the pharmaceutical industry is an important prerequisite for further development.

Identification of tRNA-derived fragments and their potential roles in diabetic cataract rats

Aim: To illustrate the expression profile of transfer RNA-derived fragments and reveal their putative role in the pathogenesis of diabetic cataract (DC) rats. Materials & methods: Small RNA sequencing was conducted in the lens epithelium of rats lens. The data were validated by quantitative real-time PCR, and bioinformatic analysis was performed to explore the roles of the fragments in DC pathogenesis. Results: A total of 213 differentially expressed tRNA-related fragments were identified, in which 111 were upregulated and 102 were downregulated in DC rats. Bioinformatics analysis revealed that several associated pathways might participate in the development of DC rats. Conclusion: tRNA-derived fragments may be involved in the pathogenesis of DC rats.

Circular RNA HIPK3 regulates human lens epithelial cell dysfunction by targeting the miR-221-3p/PI3K/AKT pathway in age-related cataract

Circular RNA Homeodomain Interacting Protein Kinase 3 (circHIPK3) was found to involve in the pathogenesis of age-related cataract (ARC). Here, we further disclosed the related target genes and molecular mechanism of circHIPK3 in the ARC progression. The expression of circHIPK3, microRNA (miR)-221-3p was detected using the quantitative real-time polymerase chain reaction. Human lens epithelial cell (HLEC) proliferation and apoptosis were measured by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay and flow cytometry, respectively. Western blot was used to detect the levels of apoptosis-related proteins, and phosphoinositide 3-kinase (PI3K)/p-protein kinase B (AKT) pathway-related proteins. Levels of malondialdehyde (MDA) and glutathione peroxidase (GSH-PX) were measured by kits. The interaction between miR-221-3p and circHIPK3 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. CircHIPK3 was down-regulated while miR-221-3p was up-regulated in human lens epithelium samples of ARC patients. CircHIPK3 up-regulation or miR-221-3p down-regulation mediated the promotion of proliferation, inhibition of apoptosis, decrease of MDA level as well as increase of GSH-PX level in HLECs. MiR-221-3p was a target of circHIPK3, and miR-221-3p overexpression reversed the protective action of circHIPK in HLEC functions. In addition, circHIPK3 activated PI3K/AKT pathway via regulating miR-221-3p, and silencing miR-221-3p protected HLECs from dysfunction by activating PI3K/AKT pathway. We demonstrated that circHIPK3 protected HLECs from dysfunction by regulating miR-221-3p/PI3K/AKT pathway, indicating a new insight into the pathogenesis of ARC and providing a potential therapeutic target for ARC.

Research Progress of Drug Prophylaxis for Lens Capsule Opacification after Cataract Surgery

Phacoemulsification combined with intraocular lens (IOL) implantation is the international standard operation procedure for cataract and has been generalized worldwide. However, lens capsule opacification, one of the common complications after cataract surgery, impacts the recovery of patients' visual function to a large extent. Lens capsule opacification has two types, anterior capsule opacification (ACO) and posterior capsule opacification (PCO), according to the location. There is not an accepted approach to treat ACO. Nd : YAG laser capsulotomy, the common treatment of PCO, can effectively improve the vision, but may cause a series of complications and is inappropriate for children who are too young to cooperate with this treatment. It is generally known that the responses of lens epithelial cells (LECs) after cataract surgery, including cell proliferation, migration, and epithelial-mesenchymal transition (EMT), play a key role in the pathogenesis of lens capsule opacification. Scholars found that substantial drugs can reduce the occurrence of lens capsule opacification by inhibiting, clearing, or killing LECs, and made great efforts as well as innovations on the exploration of drug species or modes of administration. This article is a systematic interpretation and elaboration about how to prevent lens capsule opacification after cataract surgery via different drugs.

Contribution of Connexin Hemichannels to the Decreases in Cell Viability Induced by Linoleic Acid in the Human Lens Epithelial Cells (HLE-B3)

Connexin (Cx) proteins form gap junction channels (GJC) and hemichannels that a allow bidirectional flow of ions and metabolites between the cytoplasm and extracellular space, respectively. Under physiological conditions, hemichannels have a very low probability of opening, but in certain pathologies, hemichannels activity can increase and induce and/or accelerate cell death. Several mechanisms control hemichannels activity, including phosphorylation and oxidation (i.e., S-nitrosylation). Recently, the effect of polyunsaturated fatty acids (PUFAs) such as linoleic acid (LA), were found to modulate Cxs. It has been seen that LA increase cell death in bovine and human lens cells. The lens is a structure allocated in the eye that highly depends on Cx for the metabolic coupling between its cells, a condition necessary for its transparency. Therefore, we hypothesized that LA induces lens cells death by modulating hemichannel activity. In this work, we characterized the effect of LA on hemichannel activity and survival of HLE-B3 cells (a human lens epithelial cell line). We found that HLE-B3 cells expresses Cx43, Cx46, and Cx50 and can form functional hemichannels in their plasma membrane. The extracellular exposure to 10–50 μM of LA increases hemichannels activity (dye uptake) in a concentration-dependent manner, which was reduced by Cx-channel blockers, such as the Cx-mimetic peptide Gap27 and TATGap19, La³⁺, carbenoxolone (CBX) and the Akt kinase inhibitor. Additionally, LA increases intracellular calcium, which is attenuated in the presence of TATGap19, a specific Cx43-hemichannel inhibitor. Finally, the long exposure of HLE-B3 cells to LA 20 and 50 μM, reduced cell viability, which was prevented by CBX. Moreover, LA increased the proportion of apoptotic HLE-B3 cells, effect that was prevented by the Cx-mimetic peptide TAT-Gap19 but not by Akt inhibitor. Altogether, these findings strongly suggest a contribution of hemichannels opening in the cell death induced by LA in HLE-B3 cells. These cells can be an excellent tool to develop pharmacological studies in vitro.

Therapeutic potential of a dual mTORC1/2 inhibitor for the prevention of posterior capsule opacification: An in vitro study

Mammalian target of rapamycin (mTOR) serves a central role in regulating cell growth and survival, and has been demonstrated to be involved in the pathological progression of posterior capsule opacification (PCO). In the present study, the potency of PP242, a novel dual inhibitor of mTOR complex 1/2 (mTORC1/2), in the suppression of the growth of human lens epithelial cells (HLECs) was investigated. Using a Cell Counting Kit‑8 and a wound healing assay, it was demonstrated that PP242 inhibited the proliferation and migration of HLECs. In addition, western blot analysis indicated that PP242 completely inhibited mTORC1 and mTORC2 downstream signaling activities, whereas rapamycin only partially inhibited mTORC1 activity within LECs. Furthermore, PP242 treatment led to an upregulation of the expression levels of p53 and B cell lymphoma‑2 (Bcl‑2)‑associated X and downregulation of Bcl‑2. In addition, flow cytometric analysis demonstrated that PP242 induced the cell cycle arrest at the G0/G1 phase, which may have caused apoptosis and induced autophagy within the LECs. The results of the present study suggested that administration of PP242 may potentially offer a novel therapeutic approach for the prevention of PCO.

Metformin attenuates motility, contraction, and fibrogenic response of hepatic stellate cells in vivo and in vitro by activating AMP-activated protein kinase

AIM

To investigate the effect of metformin on activated hepatic stellate cells (HSCs) and the possible signaling pathways involved.

METHODS

A fibrotic mouse model was generated by intraperitoneal injection of carbon tetrachloride (CCl₄) and subsequent treatment with or without metformin. The level of fibrosis was detected by hematoxylin-eosin staining, Sirius Red staining, and immunohistochemistry. The HSC cell line LX-2 was used for in vitro studies. The effect of metformin on cell proliferation (CCK8 assay), motility (scratch test and Transwell assay), contraction (collagen gel contraction assay), extracellular matrix (ECM) secretion (Western blot), and angiogenesis (ELISA and tube formation assay) was investigated. We also analyzed the possible signaling pathways involved by Western blot analysis.

RESULTS

Mice developed marked liver fibrosis after intraperitoneal injection with CCl₄ for 6 wk. Metformin decreased the activation of HSCs, reduced the deposition of ECM, and inhibited angiogenesis in CCl₄-treated mice. Platelet-derived growth factor (PDGF) promoted the fibrogenic response of HSCs in vitro, while metformin inhibited the activation, proliferation, migration, and contraction of HSCs, and reduced the secretion of ECM. Metformin decreased the expression of vascular endothelial growth factor (VEGF) in HSCs through inhibition of hypoxia inducible factor (HIF)-1α in both PDGF-BB treatment and hypoxic conditions, and it down-regulated VEGF secretion by HSCs and inhibited HSC-based angiogenesis in hypoxic conditions in vitro. The inhibitory effects of metformin on activated HSCs were mediated by inhibiting the Akt/mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) pathways via the activation of adenosine monophosphate-activated protein kinase (AMPK).

CONCLUSION

Metformin attenuates the fibrogenic response of HSCs in vivo and in vitro, and may therefore be useful for the treatment of chronic liver diseases.

Neuron membrane trafficking and protein kinases involved in autism and ADHD

A brain-enriched multi-domain scaffolding protein, neurobeachin has been identified as a candidate gene for autism patients. Mutations in the synaptic adhesion protein cell adhesion molecule 1 (CADM1) are also associated with autism spectrum disorder, a neurodevelopmental disorder of uncertain molecular origin. Potential roles of neurobeachin and CADM1 have been suggested to a function of vesicle transport in endosomal trafficking. It seems that protein kinase B (AKT) and cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) have key roles in the neuron membrane trafficking involved in the pathogenesis of autism. Attention deficit hyperactivity disorder (ADHD) is documented to dopaminergic insufficiencies, which is attributed to synaptic dysfunction of dopamine transporter (DAT). AKT is also essential for the DAT cell-surface redistribution. In the present paper, we summarize and discuss the importance of several protein kinases that regulate the membrane trafficking involved in autism and ADHD, suggesting new targets for therapeutic intervention.