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Vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) plays a crucial role in breakdown of the blood-retinal barrier due to hyperpermeability in diabetic retinopathy (DR). However, the distinct signaling driven by VEGF and PlGF in the pathogenesis of DR remains unclear. In this study, we investigated VEGF- and PlGF- related signaling pathways and their roles in cultured human microvascular retinal endothelial cells (hRECs) under high glucose conditions (HG; 25 mM). Apoptotic cell death was evaluated, and FITC conjugated bovine serum albumin across monolayer hRECs served as an index of permeability. Western blots were used to assess the protein levels of VEGF and PlGF, as well as the phosphorylation of p38MAPK, STAT1 and Erk1/2. Knockdown of VEGF and PlGF was performed by using siRNA. Following HG treatment, increases of VEGF and PlGF as well as PKC activity were detected in hRECs. Increased phosphorylations of p38MAPKThr180/Thr182, STAT1Ser727, and Erk1/2Tyr202/Tyr185 as well as VEGFR1Tyr1213 and VEGFR2Tyr1175 were also detected in HG-treated hRECs. Inhibition of PKC activity by Go 6976 prevented HG-induced increases of phosphor-Erk1/2 and nitric oxide synthase (NOS1) expressions as well as hyperpermeability, whereas inhibition of p38MAPK pathway by SB203580 selectively suppressed activation of STAT1 and decreased apoptotic cell death under HG conditions. Moreover, VEGF knockdown predominantly inhibited activation of VEGFR2, and phosphorylation of p38MAPK and STAT1, as well as apoptotic cell death in HG-treated hRECs. Nevertheless, PlGF knockdown mainly suppressed phosphorylation of VEGFR1, PKC, and Erk1/2, as well as NOS1 expressions and hyperpermeability. Taken together, we provide evidence demonstrating that HG-induced elevation of PlGF is responsible for hyperpermeability mainly through increasing activation of PKC-Erk1/2-NOS axis via VEGFR1, while HG-induced elevation of VEGF is associated with induction of apoptotic cell death mainly through increasing activation of p38MAPK/STAT1 signaling via VEGFR2.

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The present study investigated the function of microRNA (miR)-106b in the proliferation, migration and invasion of retinoblastoma (RB) cells, and aimed to elucidate the underlying mechanism. A total of 56 patients with RB were enrolled in the present study. The expression of miR-106b in RB tissues was measured by reverse transcription quantitative polymerase chain reaction. After transfection with miR-106b mimics or miR-106b inhibitor, a Cell-Counting kit-8 assay was used to determine the proliferation of WERI-Rb-1 cells and a Transwell assay was employed to measure the migration and invasion of the cells. Western blot analysis was performed to determine the expression of zinc finger and BTB domain containing 4 (ZBTB4) protein. By silencing or overexpression of ZBTB4 protein, the biological functions of ZBTB4 in WERI-Rb-1 cells were studied. A dual luciferase reporter assay was performed to test whether ZBTB4 was a target gene of miR-106b. The expression of miR-106b in RB tissues was elevated and closely associated with the severity of the disease. Overexpression of miR-106b increased but inhibition of miR-106b expression decreased the proliferation, migration and invasion abilities of WERI-Rb-1 cells. In addition, overexpression of miR-106b decreased but inhibition of miR-106b expression increased ZBTB4 protein expression in WERI-Rb-1 cells. Similarly, overexpression of ZBTB4 reduced but inhibition of ZBTB4 expression promoted the proliferation, migration and invasion of WERI-Rb-1 cells. Finally, miR-106b regulated the expression of ZBTB4 by binding to the 3'-untranslated region of the ZBTB4 gene. The present study demonstrated that increased expression of miR-106b in RB tissues is positively associated with the metastasis and differentiation of RB cells. As an oncogene, miR-106b promotes the proliferation, migration and invasion of WERI-Rb-1 cells by inhibiting the expression of ZBTB4 protein.

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OBJECTIVE: Zinc oxide (ZnO) nanoparticles can exhibit toxicity towards organisms and oxidative stress is often hypothesized to be one of the most important factors. Nevertheless, the detailed mechanism of toxicity-induced by ZnO nanoparticles has not been completely addressed. The present study aimed to investigate the toxic effects of ZnO nanoparticles on the expression and activity of Na+ /K+ -ATPase and on potassium channel block. MATERIALS AND METHODS: In the present study, we explored the cytotoxic effect of ZnO nanoparticles on murine photoreceptor cells using lactate dehydrogenase (LDH) release assay, reactive oxygen species (ROS) determination, mitochondrial membrane potential (Δφm) measurement, delayed rectifier potassium current recordings and Na+ /K+ -ATPase expression and activity monitoring. RESULTS: The results indicated that ZnO nanoparticles could increase the LDH release in medium, aggravate the ROS level within cells, collapse the Δφm, block the delayed rectifier potassium current, and attenuate the expressions of Na+ /K+ -ATPase at both mRNA and protein levels and its activity, and thus exert cytotoxic effects on murine photoreceptor cells, finally damaging target cells. CONCLUSION: Our findings will facilitate the understanding of the mechanism involved in ZnO nanoparticle-induced cytotoxicity in murine photoreceptor cells via potassium channel block and Na+ /K+ -ATPase inhibition.

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Dynamic methylation/demethylation of histones and non-histone proteins occurs during the cell cycle. Lysine-specific demethylase 1 (LSD1) exhibits diverse transcriptional activities through catalyzing demethylation of mono- and di-methylated histone H3 on lysine 4 (H3K4) and lysine 9 (H3K9). We show here that inhibition of LSD1 expression by siRNA leads to abnormal chromosomal segregation in unperturbed mitosis and abnormal centrosome duplication, and is associated with decreased protein levels of MAD2 and BUBR1. LSD1 positively regulates the BUBR1 and MAD2 promoter activity and maintains local monomethylation status of H3K9, which is a repressive histone mark for gene transcription. Expression of exogenous BUBR1 and MAD2 in LSD1-depleted cells partially rescues the defect of chromosome segregation. Our results suggest that LSD1 plays a role in chromosomal segregation during mitosis partially through transcriptional regulation of BUBR1 and MAD2.

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