CCN1/Cyr61-PI3K/AKT signaling promotes retinal neovascularization in oxygen-induced retinopathy

Targeting cell-type-specific, choroid-peripheral immune signaling to treat age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness featuring pathogenic neovascularization of the choroidal vasculature (CNV). Although systemic immunity plays a role in AMD, the ocular signals that recruit and activate immune cells remain poorly defined. Using single-cell RNA sequencing, we prospectively profile peripheral blood mononuclear cells from 65 individuals including AMD and controls, which we integrate with existing choroid data. We generate a network of choroid-peripheral immune interactions dysregulated in AMD, including known AMD-relevant gene vascular endothelial growth factor (VEGF) receptor 2. Additionally, we find CYR61 is upregulated in choroidal veins and may signal to circulating monocytes. In mice, we validate that CYR61 is abundant in endothelial cells within CNV lesions neighboring monocyte-derived macrophages. Mechanistically, CYR61 activates macrophage anti-angiogenic gene expression, and ocular Cyr61 knockdown increases murine CNV size, indicating CYR61 inhibits CNV. This study highlights the potential of multi-tissue human datasets to identify disease-relevant and potentially therapeutically modifiable targets.

JMJD3 and SNAI2 synergistically protect against Parkinson's disease by mediating the YAP/HIF1α signaling pathway in a mouse model

This study aimed to characterize the functional relevance and mechanistic basis of the histone demethylase Jumonji domain-containing protein-3 (JMJD3) in preserving dopaminergic neuron survival in Parkinson's disease (PD). Mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced lesions and MN9D dopaminergic neuronal cell lines exposed to 6-OHDA, respectively, were used to simulate in vivo and in vitro PD-like environments. PD-related genes with differential expressions were identified using RNA sequencing of hippocampal tissues collected from MPTP-lesioned mice. A specific lentiviral shRNA vector was used to investigate the effects of JMJD3 on neuron activities in vitro and PD-like phenotypes in vivo. JMJD3 was found to up-regulate the expression of Snail family transcriptional repressor 2 (SNAI2) through the inhibition of H3 on lysine 27 (H3K27me3) enrichment in the SNAI2 promoter region. As a result, the viability of 6-OHDA-exposed MN9D cells was stimulated, and cell apoptosis was diminished. Knockdown of SNAI2 decreased the expression of yes-associated protein (YAP) and HIF1α while also reducing the viability of 6-OHDA-exposed MN9D cells and increasing cell apoptosis. The in vivo experiments demonstrated that JMJD3 activated the SNAI2/YAP/HIF1α signaling pathway, inhibiting PD-like phenotypes in MPTP-lesioned mice. Thus, the findings provide evidence that JMJD3 inhibits the enrichment of H3K27me3 at the SNAI2 promoter, leading to the upregulation of SNAI2 expression and activation of the YAP/HIF1α signaling pathway, ultimately exerting a protective effect on PD mice. This finding suggests that targeting the JMJD3-SNAI2 pathway could be a promising therapeutic strategy for PD. Further in-depth studies are needed to elucidate the underlying mechanisms and identify potential downstream targets of this pathway.

Downregulation of PIK3IP1 in retinal microglia promotes retinal pathological neovascularization via PI3K-AKT pathway activation

Retinal pathological neovascularization involves endothelial cells, pericytes, photoreceptor cells, ganglion cells, and glial cells, whose roles remain unclear. Using the Scissor algorithm, we found that microglia are associated with formation of fibrovascular membranes and can promote pathological neovascularization. GO and KEGG results showed that PI3K-AKT pathway activation in retinal microglia was associated with pathological neovascularization, and PIK3IP1 was associated with retinal microglia activation. Then we used PCR, Western blot and Elisa techniques to confirm that the expression of VEGFA, FGF2, HGFα and MMP9 was increased in microglia after Lipopolysaccharide (LPS) induction. We also used cell flow cytometry and OIR models to verify the role of PI3K-AKT pathway and PIK3IP1 in microglia. Targeting of PIK3IP1 regulated the activation of the PI3K-AKT pathway in microglia, microglia function activation, and pro-angiogenic effects. These findings reveal the role of M1-type microglia in pathological neovascularization and suggests that targeting the PI3K-AKT pathway in microglia may be a new strategy for treating retinal pathological neovascularization.

Changes and related factors of blood CCN1 levels in diabetic patients

Objective

To study the differences in blood cellular communication network factor 1 (CCN1) levels between patients with diabetes mellitus (DM) and healthy individuals and to explore the relationship between CCN1 and diabetic retinopathy (DR).

Methods

Plasma CCN1 levels were detected using ELISA in 50 healthy controls, 74 patients with diabetes without diabetic retinopathy (DM group), and 69 patients with diabetic retinopathy (DR group). Correlations between CCN1 levels and age, body mass index, mean arterial pressure, hemoglobin A1c, and other factors were analyzed. The relationship between CCN1 expression and DR was explored using logistic regression after adjusting for confounding factors. Blood mRNA sequencing analysis was performed for all subjects, and the molecular changes that may be related to CCN1 were explored. The retinal vasculature of streptozotocin-induced diabetic rats was examined using fundus fluorescein angiography; in addition, retinal protein expression was examined using western blotting.

Results

Plasma CCN1 levels in patients with DR were significantly higher than in the control and DM groups; however, no significant differences were observed between healthy controls and patients with DM. CCN1 levels negatively correlated with body mass index and positively correlated with the duration of diabetes and urea levels. It was observed that high (OR 4.72, 95% CI: 1.10-20.25) and very high (OR 8.54, 95% CI: 2.00-36.51) levels of CCN1 were risk factors for DR. Blood mRNA sequencing analysis revealed that CCN1-related pathways were significantly altered in the DR group. The expression of hypoxia-, oxidative stress-, and dephosphorylation-related proteins were elevated, while that of tight junction proteins were reduced in the retinas of diabetic rats.

Conclusion

Blood CCN1 levels are significantly elevated in patients with DR. High and very high levels of plasma CCN1 are risk factors for DR. Blood CCN1 level may be a potential biomarker for diagnosis of DR. The effects of CCN1 on DR may be related to hypoxia, oxidative stress, and dephosphorylation.

Dual roles of FAK in tumor angiogenesis: A review focused on pericyte FAK

Focal adhesion kinase (FAK), also known as protein tyrosine kinase 2 (PTK2), is a ubiquitously expressed non-receptor tyrosine kinase, that plays a pivotal role in integrin-mediated signal transduction. Endothelial FAK is upregulated in many types of cancer and promotes tumorigenesis and tumor progression. However, recent studies have shown that pericyte FAK has the opposite effect. This review article dissects the mechanisms, by which endothelial cells (ECs) and pericyte FAK regulate angiogenesis, with an emphasis on the Gas6/Axl pathway. In particular, this article discusses the role of pericyte FAK loss on angiogenesis during tumorigenesis and metastasis. In addition, the existing challenges and future application of drug-based anti-FAK targeted therapies will be discussed to provide a theoretical basis for further development and use of FAK inhibitors.

Triciribine attenuates pathological neovascularization and vascular permeability in a mouse model of proliferative retinopathy

Proliferative retinopathies are the leading cause of irreversible blindness in all ages, and there is a critical need to identify novel therapies. We investigated the impact of triciribine (TCBN), a tricyclic nucleoside analog and a weak Akt inhibitor, on retinal neurovascular injury, vascular permeability, and inflammation in oxygen-induced retinopathy (OIR). Post-natal day 7 (P7) mouse pups were subjected to OIR, and treated (i.p.) with TCBN or vehicle from P14-P16 and compared with age-matched, normoxic, vehicle or TCBN-treated controls. P17 retinas were processed for flat mounts, immunostaining, Western blotting, and qRT-PCR studies. Fluorescein angiography, electroretinography, and spectral domain optical coherence tomography were performed on days P21, P26, and P30, respectively. TCBN treatment significantly reduced pathological neovascularization, vaso-obliteration, and inflammation marked by reduced TNFα, IL6, MCP-1, Iba1, and F4/80 (macrophage/microglia markers) expression compared to the vehicle-treated OIR mouse retinas. Pathological expression of VEGF (vascular endothelial growth factor), and claudin-5 compromised the blood-retinal barrier integrity in the OIR retinas correlating with increased vascular permeability and neovascular tuft formation, which were blunted by TCBN treatment. Of note, there were no changes in the retinal architecture or retinal cell function in response to TCBN in the normoxia or OIR mice. We conclude that TCBN protects against pathological neovascularization, restores blood-retinal barrier homeostasis, and reduces retinal inflammation without adversely affecting the retinal structure and neuronal function in a mouse model of OIR. Our data suggest that TCBN may provide a novel therapeutic option for proliferative retinopathy.

Study on the Antioxidant Effect of Tanshinone IIA on Diabetic Retinopathy and Its Mechanism Based on Integrated Pharmacology

AIM

To explore the effect of tanshinone IIA on diabetic retinopathy (DR) and its mechanism.

METHODS

GeneCards and OMM databases were used to mine DR-related genes. The chemical structure of tanshinone IIA was searched by PubChem, and the potential target was predicted by PharmMapper. Cystape 3.8.2 was used to visualize and analyze the tanshinone IIA-DR protein interaction network. DAVID ver 6.8 data were used to perform enrichment analysis of the tanshinone IIA-DR protein interaction network. Then animal experiments were carried out to further explore the mechanism of tanshinone IIA in the treatment of DR. Male SD rats were intraperitoneally injected with streptozotocin to establish a diabetes model and were randomly divided into a model group, a low-dose tanshinone IIA group and a high-dose group. Normal rats served as the control group. Hematoxylin-eosin (HE) staining was used to observe the structural changes of the retina; the SOD, GSH-Px, and MDA levels in the retina were detected by the xanthine oxidase method; the expression of VEGF, IL-1β, IL-6, TNF-α, and caspase-3 mRNA were detected by qRT-PCR; and the Bcl-2, Bax, and VEGFA proteins were determined by the western blot.

RESULTS

A total of 213 tanshinone IIA potential targets and 223 DR-related genes were obtained. The enrichment analysis showed that tanshinone IIA may regulate hypoxia, oxidative stress, positive regulation of ERK1 and ERK2 cascade, steroid hormone-mediated signaling pathway, inflammatory response, angiogenesis, VEGF signaling pathway, apoptosis, PI3K-Akt signaling pathway, TNF signaling pathway, and biological processes and signaling pathways. The structure of the retina in the normal control group was clear, the retina in the model group was not clear, the nerve fiber layer was edema, the retinal cell layers of the tanshinone IIA low-dose group are arranged neatly, the inner and outer nuclear layers are slightly disordered, and the tanshinone IIA low-dose group was large. The structure of the mouse retina was further improved compared with the low-dose tanshinone IIA group. Compared with the model group, the retinal tissue SOD and GSH-PX of rats in the tanshinone IIA group increased, and the MDA level decreased (P < 0.05). Compared with the model group, the expression of VEGF, IL-1β, IL-6, TNF-α, and caspase-3 mRNA in the retina of tanshinone IIA groups was significantly reduced (P < 0.01). Compared with the model group, the Bcl-2 protein in the tanshinone IIA groups increased, while the Bax and VEGFA proteins decreased (P < 0.05).

CONCLUSION

Tanshinone IIA may improve the morphological performance of the retina of diabetic rats and inhibit DR, the mechanism of which may be anti-inflammatory, antiangiogenesis, etc.

Development of degradable magnesium-based metal implants and their function in promoting bone metabolism (A review)

Background

Use of degradable magnesium (Mg)-based metal implants in orthopaedic surgeries can avoid drawbacks associated with subsequent removal of the non-degradable metallic implants, reducing cost and trauma of patients. Although Mg has been applied in the clinic for orthopaedic treatment, the use of Mg-based metal implants is largely in the research phase. But its application is potentially beneficial in this context as it has been shown that Mg can promote osteogenesis and inhibit osteoclast activity.

Methods

A systematic literature search about “degradable magnesium (Mg)-based metal implants” was performed in PubMed and Web of Science. Meanwhile, relevant findings have been reviewed and quoted.

Results

In this review, we summarize the latest developments in Mg-based metal implants and their role in bone regeneration. We also review the various molecular mechanisms by which Mg ions regulate bone metabolic processes, including osteogenesis, osteoclast activity, angiogenesis, immunity, and neurology. Finally, we discuss the remaining research challenges and opportunities for Mg-based implants and their applications.

Conclusion

Currently, establishment of the in vitro and in vivo biological evaluation systems and phenotypic modification improvement of Mg-based implants are still needed. Clarifying the functions of Mg-based metal implants in promoting bone metabolism is beneficial for their clinical application.

The Translational potential of this article

All current reviews on Mg-based implants are mainly concerned with the improvement of Mg alloy properties or the progress of applications. However, there are few reviews that provides a systematic narrative on the effect of Mg on bone metabolism. This review summarized the latest developments in Mg-based metal implants and various molecular mechanisms of Mg ions regulating bone metabolism, which is beneficial to further promote the translation of Mg based implants in the clinic and is able to provide a strong basis for the clinical application of Mg based implants.

Cellular communication network factor 1 interlinks autophagy and ERK signaling to promote osteogenesis of periodontal ligament stem cells

OBJECTIVES

To investigate the effects of cellular communication network factor 1 (CCN1), a critical matricellular protein, on alveolar bone regeneration, and to elucidate the underlying molecular mechanism.

BACKGROUND

In the process of orthodontic tooth movement, bone deposition on the tension side of human periodontal ligament stem cells (hPDLSCs) ensured high efficiency and long-term stability of the treatment. The matricellular protein CCN1 is responsive to mechanical stimulation, exhibiting important tasks in bone homoeostasis. However, the role and mechanism of CCN1 on alveolar bone remodeling of hPDLSCs remains unclear.

METHODS

The expression and distribution of CCN1 in rat periodontal ligament were detected by immunofluorescence staining and immunohistochemical staining. ELISA verified the secretion of CCN1 triggered by stretch loading. To examine the mineralization ability of hPDLSCs induced by CCN1, Western blotting, qRT-PCR, ARS, and ALP staining were performed. CCK-8 and cell migration assay were performed to detect the cell proliferation rate and the wound healing. PI3K/Akt, MAPK, and autophagy activation were examined via Western blotting and immunofluorescence.

RESULTS

Mechanical stimuli induced the release of CCN1 into extracellular environment by hPDLSCs. Knockdown of CCN1 attenuated the osteogenesis of hPDLSCs while rhCCN1 enhanced the expression of Runx2, Col 1, ALPL, and promoted the mineralization nodule formation. CCN1 activated PI3K/Akt and ERK signaling, and blockage of PI3K/Akt signaling reversed the accelerated cell migration triggered by CCN1. The enhanced osteogenesis induced by CCN1 was abolished by ERK signaling inhibitor PD98059 or autophagy inhibitor 3-MA. Further investigation demonstrated PD98059 abrogated the activation of autophagy.

CONCLUSION

This study demonstrated that CCN1 promotes osteogenesis in hPDLSCs via autophagy and MAPK/ERK pathway.

Propranolol ameliorates retinopathy of prematurity in mice by downregulating HIF-1α via the PI3K/Akt/ERK pathway

BACKGROUND

Retinopathy of prematurity (ROP) is the leading cause of blindness in infants, and elevation of HIF-1α through the PI3K/Akt and ERK pathways is implicated in ROP pathogenesis. The mechanism of action of propranolol in ROP remains controversial. We investigated the effect of propranolol on ROP and explored its potential mechanisms of action in an oxygen-induced retinopathy (OIR) mouse model.

METHODS

OIR mice were first treated with propranolol intraperitoneally, and the retina integrity was measured by FITC-dextran and hematoxylin-eosin staining. The expression of HIF-1α, VEGF, and key signaling pathway proteins was determined using real-time PCR and western blotting.

RESULTS

FITC-dextran staining showed that propranolol treatment reduced damage to retinal morphology in OIR mice. Mice treated with propranolol showed a reduced number of nuclei of vascular endothelial cells penetrating the inner limiting membrane of the retina, confirming the therapeutic effect of propranolol on ROP. Further analysis showed that HIF-1α and PI3K/Akt/ERK pathway protein levels were significantly elevated in OIR mice. In contrast, propranolol treatment downregulated the expression of these proteins, indicating that the PI3K/Akt/ERK/HIF-1α axis is associated with propranolol-induced ROP alleviation.

CONCLUSIONS

Propranolol has a therapeutic function against ROP, likely through the downregulation of HIF-1α via the PI3K/Akt/ERK pathway.

IMPACT

Propranolol can reduce the formation of abnormal retinal neovascularization in oxygen-induced retinopathy (OIR) models, and reduce leaking, tortuous, and abnormally expanding retinal blood vessels. Propranolol possibly improves OIR by inhibiting the activated ERK and HIF-1α pathways. Furthermore, propranolol may downregulate HIF-1α via the PI3K/Akt/ERK pathway to ameliorate retinopathy of prematurity. This study elucidated that the therapeutic effect of propranolol in OIR mice does not involve the VEGFR-2 pathway.

LGALS3BP in Microglia Promotes Retinal Angiogenesis Through PI3K/AKT Pathway During Hypoxia

Purpose

Retinal microglia promote angiogenesis and vasculopathy in oxygen-induced retinopathy (OIR); however, its specific molecular mechanism in the formation of retinal angiogenesis remains unclear. The lectin galactoside-binding soluble 3 binding protein (LGALS3BP), a member of the scavenger receptor cysteine-rich (SRCR) domain protein family, is involved in tumor neovascularization, and we therefore hypothesized that LGALS3BP plays an active role in microglia-induced angiogenesis.

Methods

The expression of LGALS3BP in microglia was detected by immunofluorescence, RT-qPCR, and western blotting. Functional assays of human umbilical vein endothelial cells (HUVECs) such as migration, proliferation, and tube formation were measured by Transwell, EdU, and Matrigel assays. Angiogenesis-related factors and PI3K/AKT levels were detected by western blotting. The relationship between LGALS3BP and PI3K or HIF-1α was investigated by immunoprecipitation.

Results

Our results showed that the expression of LGALS3BP was significantly increased in microglia surrounding neovascularization of the OIR mice and was also upregulated in human microglial clone 3 (HMC3) cells after hypoxia. Moreover, HUVECs co-cultured with hypoxic HMC3 cells showed increased migration, proliferation, and tube formation, as well as levels of angiogenesis-related factor. However, the proangiogenic ability and angiogenesis-related factor expression of HMC3 cells was suppressed after silencing LGALS3BP. LGALS3BP induces the upregulation of angiogenesis-related factors through the PI3K/AKT pathway and then promotes angiogenesis in microglia.

Conclusions

Collectively, our findings suggest that LGALS3BP in microglia plays an important role in angiogenesis, suggesting a potential therapeutic target of LGALS3BP for angiogenesis.

Ocular macrophage origin and heterogeneity during steady state and experimental choroidal neovascularization

BACKGROUND

Neovascular age-related macular degeneration (nAMD) commonly causes vision loss from aberrant angiogenesis, termed choroidal neovascularization (CNV). Macrophages are heterogeneous cells that are necessary for experimental CNV, present in human CNV samples, and can display diverse functions, which are dependent upon both their origin and tissue microenvironment. Despite these associations, choroidal macrophage heterogeneity remains unexplored.

METHODS

We performed multi-parameter flow cytometry on wildtype (WT) and Ccr2-/- mice after laser injury to identify macrophage subtypes, and determine which subsets originate from classical monocytes. To fate map tissue resident macrophages at steady state and after laser injury, we used the Cx3cr1CreER/+ ; Rosa26zsGFP/+ mouse model. We reanalyzed previously published single-cell RNA-seq of human choroid samples from healthy and nAMD patients to investigate human macrophage heterogeneity, disease association, and function.

RESULTS

We identified 4 macrophage subsets in mice: microglia, MHCII+CD11c-, MHCII+CD11c+, and MHCII-. Microglia are tissue resident macrophages at steady state and unaffected by laser injury. At steady state, MHCII- macrophages are long lived, tissue resident macrophages, while MHCII+CD11c- and MHCII+CD11c+ macrophages are partially replenished from blood monocytes. After laser injury, MHCII+CD11c- macrophages are entirely derived from classical monocytes, MHCII- macrophages originate from classical monocytes (90%) and an expansion of tissue resident macrophages (10%), and MHCII+CD11c+ macrophages are derived from classical monocytes (70%), non-classical monocytes (10%), and an expansion of tissue resident macrophages (20%). Single-cell RNA-seq analysis of human choroid found 5 macrophage subsets: two MHCII+CD11C- and three MHCII+CD11C+ populations. One MHCII+CD11C+ subset was 78% derived from a patient with nAMD. Differential expression analysis identified up-regulation of pro-angiogenic gene expression in one MHCII+CD11C- and two MHCII+CD11C+ subsets, including the disease-associated cluster. The upregulated MHCII+CD11C- pro-angiogenic genes were unique compared to the increased MHCII+CD11C+ angiogenesis genes.

CONCLUSIONS

Macrophage origin impacts heterogeneity at steady state and after laser injury in mice. Both mice and human patients demonstrate similar macrophage subtypes. Two discrete pro-angiogenic macrophage populations exist in the human choroid. Targeting specific, pro-angiogenic macrophage subsets is a potential novel therapeutic for nAMD.

Somanath P, Zhang D. The Roles of CCN1/CYR61 in Pulmonary Diseases

CCN1 (cysteine-rich 61, connective tissue growth factor, and nephroblastoma-1), previously named CYR61 (cysteine-rich angiogenic inducer 61) belongs to the CCN family of matricellular proteins. CCN1 plays critical roles in the regulation of proliferation, differentiation, apoptosis, angiogenesis, and fibrosis. Recent studies have extensively characterized the important physiological and pathological roles of CCN1 in various tissues and organs. In this review, we summarize both basic and clinical aspects of CCN1 in pulmonary diseases, including acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), lung fibrosis, pulmonary arterial hypertension (PAH), lung infection, and lung cancer. We also emphasize the important challenges for future investigations to better understand the CCN1 and its role in physiology and pathology, as well as the questions that need to be addressed for the therapeutic development of CCN1 antagonists in various lung diseases.

Normal vitreous promotes angiogenesi via the epidermal growth factor receptor

Vitreous, a transparent tissue in our body, contains anti-angiogenesis factors. Our previous work reported that vitreous activates the signaling pathway of epidermal growth factor receptor (EGFR), which plays a critical role in angiogenesis. The aim of this study was to determine the role of EGFR in vitreous-induced angiogenesis-related cellular responses in vitro. Using a pharmacologic and molecular approach, we found that vitreous increased proliferation and migration via EGFR in human umbilical vein endothelial cells (HUVECs). Furthermore, we demonstrated that vitreous promoted tube formation via EGFR in HUVECs. Subsequently, depletion of EGFR using CRISPR/Cas9 and blockage with EGFR inhibitor AG1478 suppressed vitreous-induced Akt activation and cell proliferation, migration, and tube formation in HUVECs. The significance of the angiogenic effect derived from vitreous demonstrates the importance of vitreous in the ocular physiology and the pathobiology of angiogenesis-related ophthalmic diseases, such as proliferative diabetic retinopathy.

LncRNA TUG1 Promotes Hepatocellular Carcinoma Migration and Invasion Via Targeting miR-137/AKT2 Axis

Background: The current study aimed to investigate the effects of TUG1 on the migration and invasion of hepatoma cells. Materials and Methods: The expressions of TUG1, miR-137, and AKT2 were detected in hepatoma tissues and cells by performing quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The correlations among TUG1, miR-137, and AKT2 were predicted by bioinformatics analysis and confirmed by dual-luciferase reporter assay, and Pearson test was performed to analyze their relevance. The effects of TUG1, miR-137, and AKT2 on viability, migration, and invasion of transfected hepatoma cells were detected by CCK-8, wound scratch, and Transwell. Epithelial-mesenchymal transition (EMT)-related protein levels were determined by western blot and qRT-PCR. Results: TUG1 was highly expressed in hepatoma tissues and cells. Silencing TUG1 expression inhibited the viability, migration, and invasion of hepatoma cells. TUG1 targeted miR-137 and the two was negatively correlated, and silencing TUG1 expression inhibited the effects of low-expressed miR-137 on promoting proliferation, migration, and invasion of hepatoma cells. AKT2 was predicted to be the target gene for miR-137, and the two were negatively correlated. Moreover, inhibiting miR-137 expression promoted the expression of MMP2, MMP9, and N-cadherin and inhibited E-cadherin expression, while silencing TUG1 expression reversed the effects of low-expressed miR-137 on EMT-related protein levels. Conclusion: LncRNA TUG1 promotes hepatocellular carcinoma migration and invasion through targeting miR-137/AKT2 axis.

CCAAT/Enhancer-Binding Protein β Mediates Oxygen-Induced Retinal Neovascularization via Retinal Vascular Damage and Vascular Endothelial Growth Factor

OBJECTIVE

To evaluate the role of CCAAT/enhancer-binding protein β (C/EBP β (C/EBP.

METHODS

Rats with OIR were exposed to alternating hypoxic and hyperopic conditions for 14 days. Then, the rats with OIR were assigned randomly to groups that received intravitreal injections of either shRNA lentiviral particles targeting C/EBP β (C/EBP β (C/EBP β (C/EBP β (C/EBP β (C/EBP β (C/EBP.

RESULTS

In OIR rats, the expression levels of C/EBP β (C/EBP P < 0.01). The p-C/EBP β (C/EBP β (C/EBP β (C/EBP β (C/EBP β (C/EBP P < 0.01). The p-C/EBP β (C/EBP β (C/EBP β (C/EBP P < 0.01). The p-C/EBP.

CONCLUSIONS

C/EBP β shRNA inhibits RNV in OIR. A potential mechanism may be that the activity of C/EBP β increases with its overexpression, which in turn aggravates the amount of the retinal vascular damage and promotes transcription of VEGF. C/EBP β might be a new therapeutic target for preventing RNV.β (C/EBP β (C/EBP β (C/EBP.

Functional Vascular Tissue Engineering Inspired by Matricellular Proteins

Modern regenerative medicine, and tissue engineering specifically, has benefited from a greater appreciation of the native extracellular matrix (ECM). Fibronectin, collagen, and elastin have entered the tissue engineer's toolkit; however, as fully decellularized biomaterials have come to the forefront in vascular engineering it has become apparent that the ECM is comprised of more than just fibronectin, collagen, and elastin, and that cell-instructive molecules known as matricellular proteins are critical for desired outcomes. In brief, matricellular proteins are ECM constituents that contrast with the canonical structural proteins of the ECM in that their primary role is to interact with the cell. Of late, matricellular genes have been linked to diseases including connective tissue disorders, cardiovascular disease, and cancer. Despite the range of biological activities, this class of biomolecules has not been actively used in the field of regenerative medicine. The intent of this review is to bring matricellular proteins into wider use in the context of vascular tissue engineering. Matricellular proteins orchestrate the formation of new collagen and elastin fibers that have proper mechanical properties-these will be essential components for a fully biological small diameter tissue engineered vascular graft (TEVG). Matricellular proteins also regulate the initiation of thrombosis via fibrin deposition and platelet activation, and the clearance of thrombus when it is no longer needed-proper regulation of thrombosis will be critical for maintaining patency of a TEVG after implantation. Matricellular proteins regulate the adhesion, migration, and proliferation of endothelial cells-all are biological functions that will be critical for formation of a thrombus-resistant endothelium within a TEVG. Lastly, matricellular proteins regulate the adhesion, migration, proliferation, and activation of smooth muscle cells-proper control of these biological activities will be critical for a TEVG that recellularizes and resists neointimal formation/stenosis. We review all of these functions for matricellular proteins here, in addition to reviewing the few studies that have been performed at the intersection of matricellular protein biology and vascular tissue engineering.

Neurofibromin Deficiency Induces Endothelial Cell Proliferation and Retinal Neovascularization

Purpose

Neurofibromatosis type 1 (NF1) is the result of inherited mutations in the NF1 tumor suppressor gene, which encodes the protein neurofibromin. Eye manifestations are common in NF1 with recent reports describing a vascular dysplasia in the retina and choroid. Common features of NF1 retinopathy include tortuous and dilated feeder vessels that terminate in capillary tufts, increased endothelial permeability, and neovascularization. Given the retinal vascular phenotype observed in persons with NF1, we hypothesize that preserving neurofibromin may be a novel strategy to control pathologic retinal neovascularization.

Methods

Nf1 expression in human endothelial cells (EC) was reduced using small hairpin (sh) RNA and EC proliferation, migration, and capacity to form vessel-like networks were assessed in response to VEGF and hypoxia. Wild-type (WT), Nf1 heterozygous (Nf1^+/−), and Nf1^flox/+;Tie2cre pups were subjected to hyperoxia/hypoxia using the oxygen-induced retinopathy model. Retinas were analyzed quantitatively for extent of retinal vessel dropout, neovascularization, and capillary branching.

Results

Neurofibromin expression was suppressed in response to VEGF, which corresponded with activation of Mek-Erk and PI3-K-Akt signaling. Neurofibromin-deficient EC exhibited enhanced proliferation and network formation in response to VEGF and hypoxia via an Akt-dependent mechanism. In response to hyperoxia/hypoxia, Nf1^+/− retinas exhibited increased vessel dropout and neovascularization when compared with WT retinas. Neovascularization was similar between Nf1^+/− and Nf1^flox/+;Tie2cre retinas, but capillary drop out in Nf1^flox/+;Tie2cre retinas was significantly reduced when compared with Nf1^+/− retinas.

Conclusions

These data suggest that neurofibromin expression is essential for controlling endothelial cell proliferation and retinal neovascularization and therapies targeting neurofibromin-deficient EC may be beneficial.

Inhibition of LY294002 in retinal neovascularization via down-regulation the PI3K/AKT-VEGF pathway in vivo and in vitro

AIM

To investigate the effects of the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 on retinal neovascularization (RNV) in the oxygen-induced retinopathy (OIR) mouse model and human umbilical vein endothelial cells (HUVECs).

METHODS

C57BL/6J mice were randomly divided into normoxia-control, OIR-control and LY294002 treatment groups. LY294002 or phosphate-buffered solution was intraperitoneally injected daily into mouse pups from P6 to P9 in LY294002 treatment group or OIR-control group. Morphological and pathological changes in RNV, as well as expression levels of PI3K, serine-threonine kinase (AKT) and vascular endothelial growth factor (VEGF) were observed. HUVECs treating with LY294002 were exposed to hypoxia; the expression of PI3K, AKT and VEGF were examined by Western blot and RT-PCR analyses.

RESULTS

Compared with the OIR-control group, LY294002 significantly inhibit RNV. Adenosine diphosphatase (ADPase) staining and hematoxylin and eosin staining indicated that the clock hour scores of neovascularization and the nuclei of pre-retinal neovascular cells in the LY294002 treatment group were clearly less than those in the OIR-control group (1.41±0.52 vs 6.20±1.21; 10.50±1.58 vs 22.25±1.82, both P<0.05). Intravitreal injection of LY294002 (in the LY294002 treatment group) markedly decreased PI3K/AKT-VEGF expression compared with the OIR-control group by immunohistochemistry, Western blotting and RT-PCR (all P<0.05). In HUVECs treated with hypoxia, expression of PI3K, AKT and VEGF were downregulated in the hypoxia-LY294002 group (all P<0.05).

CONCLUSION

The PI3K inhibitor LY294002 can inhibit RNV by downregulating PI3K, AKT, and VEGF expression in vivo and in vitro. LY294002 may provide an effective method for preventing retinopathy of prematurity (ROP).

Differentially expressed miRNAs in premature infants with retinopathy-a bioinformatics analysis

AIM

To reveal the role of miRNAs in retinopathy of prematurity (ROP) by bioinformatics analysis.

METHODS

The raw data of this study came from the researches of Wang et al and Zhao et al who analyzed the microRNA (miRNA) expression profile between ROP and controls. Based on the identified differentially expressed miRNAs, the related target genes, lncRNA and circRNA were predicted. Then we performed functional enrichment analysis to further analyze the functions of target genes.

RESULTS

Hsa-miRNA-128-3p and hsa-miRNA-9-5p showed significantly different expression in both studies. LncRNA of POLDIP2, GAS5, NEFL and UHRF1, circRNA of ZNF280C_hsa_circ_001211 and SIAE_hsa_circ_002083, tar-get gene of QKI showed meaningful differential expression in ROP. Enrichment analysis showed that TGF-β signaling pathway, PI3K-Akt signaling pathway and MAPK signaling pathway might play important roles in the prog-ress of ROP.

CONCLUSION

This research may provide a comprehensive bioinformatics analysis of differentially expressed miRNAs which are possibly involved in ROP.

Advanced glycation end products promote VEGF expression and thus choroidal neovascularization via Cyr61-PI3K/AKT signaling pathway

Choroidal neovascularisation (CNV) causes severe vision loss among old patients, especially those with diabetes. Previously, Cyr61 has been found to play a critical role in the pathogenesis of both AMD and diabetes. In the present study, we found that increased CNV severity together with higher expression of Cyr61 and VEGF in diabetes mice compared with control mice. Moreover, knockdown of Cyr61 decreased CNV severity. In vitro mechanism study revealed that the advanced glycation end products (AGEs) significantly increased the expression of Cyr61 in retinal pigment epithelial (RPE) cells, mimicking the effects of diabetes. In turn, the increased Cyr61 enhanced VEGF expression through FAK and PI3K/Akt pathways. Chemically blocking the above pathway significantly inhibited CNV formation, providing a new strategy for clinical prevention and treatment of CNV in related diseases.

Hypoxia and Redox Signaling on Extracellular Matrix Remodeling: From Mechanisms to Pathological Implications

SIGNIFICANCE

The extracellular matrix (ECM) is an essential modulator of cell behavior that influences tissue organization. It has a strong relevance in homeostasis and translational implications for human disease. In addition to ECM structural proteins, matricellular proteins are important regulators of the ECM that are involved in a myriad of different pathologies. Recent Advances: Biochemical studies, animal models, and study of human diseases have contributed to the knowledge of molecular mechanisms involved in remodeling of the ECM, both in homeostasis and disease. Some of them might help in the development of new therapeutic strategies. This review aims to review what is known about some of the most studied matricellular proteins and their regulation by hypoxia and redox signaling, as well as the pathological implications of such regulation.

CRITICAL ISSUES

Matricellular proteins have complex regulatory functions and are modulated by hypoxia and redox signaling through diverse mechanisms, in some cases with controversial effects that can be cell or tissue specific and context dependent. Therefore, a better understanding of these regulatory processes would be of great benefit and will open new avenues of considerable therapeutic potential.

FUTURE DIRECTIONS

Characterizing the specific molecular mechanisms that modulate matricellular proteins in pathological processes that involve hypoxia and redox signaling warrants additional consideration to harness the potential therapeutic value of these regulatory proteins. Antioxid. Redox Signal. 27, 802-822.

Trigonostemon reidioides modulates endothelial cell proliferation, migration and tube formation via downregulation of the Akt signaling pathway

Trigonostemon reidi`oides (TR) is used as a Thai traditional medicine for the treatment of drug addiction, asthma, food poisoning, constipation and snake bites. The present study investigated the effects and molecular mechanisms of the ethanolic extract of TR (ETR) on mitogen-induced human umbilical vein endothelial cells (HUVECs) responses, proliferation, adhesion, migration and tube formation. ETR treatment inhibited mitogen-induced HUVEC proliferation by downregulation of cell cycle-associated proteins, including cyclins and cyclin-dependent kinases, which induced retinoblastoma protein hypophosphorylation. The present study also demonstrated that ETR treatment suppressed mitogen-induced HUVEC adhesion, migration, invasion and tube formation, and that these anti-angiogenic activities were mediated by inactivation of mitogen-induced Akt and matrix metalloproteinase (MMP)-2, but not of extracellular signal-regulated kinase, p70 ribosomal S6 kinase or MMP-9. Collectively, the results of the present study suggested pharmacological functions and molecular mechanisms of ETR in regulating endothelial cell fates, and supported further evaluation and development of ETR as a potential therapeutic agent for the treatment and prevention of angiogenesis-associated diseases, including cancer.

Hyperactive FOXO1 results in lack of tip stalk identity and deficient microvascular regeneration during kidney injury

Loss of the microvascular (MV) network results in tissue ischemia, loss of tissue function, and is a hallmark of chronic diseases. The incorporation of a functional vascular network with that of the host remains a challenge to utilizing engineered tissues in clinically relevant therapies. We showed that vascular-bed-specific endothelial cells (ECs) exhibit differing angiogenic capacities, with kidney microvascular endothelial cells (MVECs) being the most deficient, and sought to explore the underlying mechanism. Constitutive activation of the phosphatase PTEN in kidney MVECs resulted in impaired PI3K/AKT activity in response to vascular endothelial growth factor (VEGF). Suppression of PTEN in vivo resulted in microvascular regeneration, but was insufficient to improve tissue function. Promoter analysis of the differentially regulated genes in KMVECs suggests that the transcription factor FOXO1 is highly active and RNAseq analysis revealed that hyperactive FOXO1 inhibits VEGF-Notch-dependent tip-cell formation by direct and indirect inhibition of DLL4 expression in response to VEGF. Inhibition of FOXO1 enhanced angiogenesis in human bio-engineered capillaries, and resulted in microvascular regeneration and improved function in mouse models of injury-repair.

Effects of microRNA-29a on retinopathy of prematurity by targeting AGT in a mouse model

BACKGROUND

This study aimed to explore the effects of microRNA-29a (miR-29a) on retinopathy of prematurity (ROP) by targeting angiotensinogen (AGT) expression in a mouse model.

METHODS

Ninety-six C57BL/6J mice were selected and divided into the normal control group (n = 12) and the oxygen-induced retinopathy (OIR) group (n = 84). All the mice in the OIR group were assigned to the following seven groups (12 mice in each group): the blank, miR-29a mimics, miR-29a inhibitors, empty plasmid, miR-29a mimics + si-AGT, miR-29a inhibitors + si-AGT and si-AGT groups. ADPase histochemical staining was conducted to detect the morphology of retinal neovascularization. H&E staining was performed to quantify retinal neovascularization. The qRT-PCR assay was applied to detect the expression levels of miR-29a and the AGT mRNA. Western blotting was used to detect the protein expressions of AGT, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), angiotensin (ANG) and angiotensin II (AngII).

RESULTS

Compared with the normal control group, miR-29a expression decreased, while the AGT mRNA expression and the protein expression levels of AGT, VEGF, HGF, ANG and AngII increased, and retinal vascular density and neovascularization also increased in the OIR group. In the OIR group, compared with the blank, empty plasmid, miR-29a inhibitors and miR-29a inhibitors + si-AGT groups, miR-29a expression increased, while the AGT mRNA expression and protein expression levels of AGT, VEGF, HGF, ANG and AngII decreased, and retinal vascular density and neovascularization also decreased in the miR-29a mimics, miR-29a mimics + si-AGT and si-AGT groups.

CONCLUSION

MiR-29a could inhibit retinal neovascularization to prevent the development and progression of ROP by down-regulating AGT.

7,8-DHF Treatment Induces Cyr61 Expression to Suppress Hypoxia Induced ER Stress in HK-2 Cells

Acute kidney injury (AKI) is a common syndrome which is strongly linked to high morbidity and mortality. Hypoxia is the leading cause of AKI and the proximal renal tubular cells are the most damaged part in the kidney during this period. It has been observed that 7,8-dihydroxyflavone (7,8-DHF) plays a protective role by acting on antiapoptosis and antioxidative stress. In this study we explored functions of 7,8-DHF in protecting human proximal tubular cell line HK-2 from hypoxia insults. We observed that treatment of 7,8-DHF could improve the viability of ischemic cell. Mechanistically, we found that 7,8-DHF could elevate the expression of cysteine-rich protein 61 (Cyr61), a protective immediate early gene in AKI. In addition, treatment of 7,8-DHF decreased CCAAT/enhancer-binding protein homologous protein (CHOP) expression, which is a marker protein during endoplasmic reticulum (ER) stress activation. Intriguingly, overexpression of Cyr61 significantly reduced CHOP expression. Taken together, our results provide novel insights into the possible protective role of 7,8-DHF by activating Cyr61 signaling and suppressing ER stress in hypoxic HK-2 cells which have potential clinical implications for the treatment of AKI.

Baclofen Protects Primary Rat Retinal Ganglion Cells from Chemical Hypoxia-Induced Apoptosis Through the Akt and PERK Pathways

Retinal ganglion cells (RGCs) consume large quantities of energy to convert light information into a neuronal signal, which makes them highly susceptible to hypoxic injury. This study aimed to investigate the potential protection by baclofen, a GABA_B receptor agonist of RGCs against hypoxia-induced apoptosis. Cobalt chloride (CoCl₂) was applied to mimic hypoxia. Primary rat RGCs were subjected to CoCl₂ with or without baclofen treatment, and RNA interference techniques were used to knock down the GABA_B2 gene in the primary RGCs. The viability and apoptosis of RGCs were assessed using cell viability and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assays, Hoechst staining, and flow cytometry. The expression of cleaved caspase-3, bcl-2, bax, Akt, phospho-Akt, protein kinase RNA (PKR)-like ER kinase (PERK), phospho-PERK, eIF2α, phospho-eIF2α, ATF-4 and CCAAT/enhancer-binding protein homologous protein (CHOP) were measured using western blotting. GABA_B2 mRNA expression was determined using quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Our study revealed that CoCl₂ significantly induced RGC apoptosis and that baclofen reversed these effects. CoCl₂-induced reduction of Akt activity was also reversed by baclofen. Baclofen prevented the activation of the PERK pathway and the increase in CHOP expression induced by CoCl₂. Knockdown of GABA_B2 and the inactivation of the Akt pathway by inhibitors reduced the protective effect of baclofen on CoCl₂-treated RGCs. Taken together, these results demonstrate that baclofen protects RGCs from CoCl₂-induced apoptosis by increasing Akt activity and by suppressing the PERK pathway and CHOP activation.

Function and Hormonal Regulation of GATA3 in Human First Trimester Placentation

Pregnancies resulting from fresh in vitro fertilization (IVF) cycles exposed to supraphysiologic estrogen levels have been associated with higher rates of low birth weight and small for gestational age babies. We identified GATA3, a transcription factor selectively expressed in the trophectoderm during the blastocyst stage of embryo development, in an upstream analysis of genes that were differentially methylated in chorionic villus samples between IVF and non-IVF infertility treatment pregnancies. In this study, we investigate the hypothesis that GATA3 is hormonally regulated and plays an important functional role in trophoblast migration, invasion, and placentation. We found that GATA3 expression was hormonally regulated by estradiol in HTR8/SVneo first trimester trophoblast cells; however, no change in expression was seen with progesterone treatment. Furthermore, GATA3 knockdown resulted in decreased HTR8/SVneo cell migration and invasion compared with controls. RNA sequencing of GATA3 knockdown cells demonstrated 96 differentially regulated genes compared with controls. Genes known to play an important role in cell-cell and cell-extracellular matrix interactions, cell invasion, and placentation were identified, including CTGF, CYR61, ADAMTS12, and TIMP3. Our results demonstrate estradiol down-regulates GATA3, and decreased GATA3 expression leads to impaired trophoblast cell migration and invasion, likely through regulation of downstream genes important in placentation. These results are consistent with clinical data suggesting that supraphysiologic estrogen levels seen in IVF pregnancies may play an important role in attenuated trophoblast migration, invasion, and impaired placentation. GATA3 appears to be an important regulator of placentation and may play a role in impaired outcomes associated with fresh IVF cycles.

Cysteine‑rich 61 RNA interference inhibits pathological angiogenesis via the phosphatidylinositol 3‑kinase/Akt‑vascular endothelial growth factor signaling pathway in endothelial cells

Hypoxia is a key factor in the pathogenesis of angiogenesis, and cysteine‑rich 61 (CCN1), an angiogenic factor, is involved in the development of pathological angiogenesis. The aim of the present study was to investigate the mechanism of CCN1 RNA interference (RNAi)‑induced inhibition of hypoxia‑induced pathological angiogenesis in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions in vitro. The effects of inhibiting phosphoinositide 3‑kinase (PI3K)/Akt signaling using LY294002 were investigated in hypoxic HUVECs. The proliferation and apoptosis of HUVECs under hypoxia were assessed using CCN1 RNAi. The CCN1‑PI3K/Akt‑vascular endothelial growth factor (VEGF) pathway was analyzed under hypoxic conditions using reverse transcription‑quantitative polymerase chain reaction and western blotting. CCN1 RNAi inhibited the proliferation and induced the apoptosis of the HUVECs under hypoxia, with hypoxia significantly increasing the mRNA and protein expression levels of CCN1, Akt and VEGF. By contrast, CCN1 RNAi reduced the mRNA and protein expression levels of CCN1, Akt and VEGF in the HUVECs (P<0.05). Furthermore, LY294002 reduced the mRNA and protein expression levels of CCN1 in the hypoxic cells (P<0.05). These data indicated that CCN1 inhibits apoptosis and promotes proliferation in HUVECs. Therefore, CCN1 RNAi may offer a novel therapeutic strategy, which may aid in the treatment of pathological angiogenesis via inhibition of the PI3K/Akt‑VEGF pathway.