E-cadherin to N-cadherin switching in the TGF-ß1 mediated retinal pigment epithelial to mesenchymal transition.

A serious form of ocular fibrotic disease is proliferative vitreoretinopathy (PVR) that can ultimately lead to blindness. While the pathogenesis of PVR is known to be closely tied to retinal pigment epithelial (RPE) cell epithelial-mesenchymal transition (EMT) characterized by E-cadherin downregulation and N-cadherin upregulation. Herein, we developed a model of transforming growth factor-ß1 (TGF-ß1)-induced EMT using human RPE (hRPE) cells as a tool for exploring the mechanistic basis for E-cadherin to N-cadherin switching. This analysis revealed that the loss of E-cadherin led to the separation of ß-catenin from the catenin-cadherin complex whereupon it underwent nuclear entry to activate zinc finger E-box binding homeobox 1 (ZEB1), in turn promoting N-cadherin upregulation in this biological context. E-cadherin overexpression was sufficient to inhibit this EMT process and proliferation in RPE cells, further constraining their TGF-ß1-induced apoptosis.

TSPAN4-positive migrasome derived from retinal pigmented epithelium cells contributes to the development of proliferative vitreoretinopathy.

BACKGROUND: Proliferative vitreoretinopathy (PVR) is a blind-causing disease initiated by the activation of retinal pigmented epithelium (RPE) primarily induced by TGF-ß families. Migrasome is a recently discovered type of extracellular vesicle related to cell migration. RESULTS: Here, we used ex vivo, in vitro, and in vivo models, to investigate the characteristics and functions of migrasomes in RPE activation and PVR development. Results indicated that the migrasome marker tetraspanin-4 (TSPAN4) was abundantly expressed in human PVR-associated clinical samples. The ex vivo model PVR microenvironment is simulated by incubating brown Norway rat RPE eyecups with TGF-ß1. Electron microscope images showed the formation of migrasome-like vesicles during the activation of RPE. Further studies indicated TGF-ß1 increased the expression of TSPAN4 which results in migrasome production. Migrasomes can be internalized by RPE and increase the migration and proliferation ability of RPE. Moreover, TSPAN4-inhibited RPE cells are with reduced ability of initiating experimental PVR. Mechanically, TSPAN4 expression and migrasome production are induced through TGF-ß1/Smad2/3 signaling pathway. CONCLUSION: In conclusion, migrasomes can be produced by RPE under PVR microenvironment. Migrasomes play a pivotal role in RPE activation and PVR progression. Thus, targeting TSPAN4 or blocking migrasome formation might be a new therapeutic method against PVR.

Detecting Three-Dimensional Vascular Networks in the Mouse Embryonic Hindbrain.

Blood vessel formation is a fine-regulated process and interfering with blood vessel formation causes embryonic lethality as well as associated with many diseases in the adult, including inflammatory, ischemic, and cancer metastatic diseases. Brain contains abundant blood vessels and has some unique physiological functions, such as blood-brain barrier. Due to the thickness and opaque characters of the tissues, it is a challenge to visualize the three-dimensional structures of the brain blood vessels in the mouse. Therefore, establishing a protocol to display the three-dimensional structures in the brain is required for exploring the regulatory molecular mechanisms in brain blood vessel formation. In this manuscript, we introduced a whole-mount and a vibratome thick section of mouse embryonic hindbrain to display the three-dimensional structures of brain vascular system.

Long noncoding RNA ERLR mediates epithelial-mesenchymal transition of retinal pigment epithelial cells and promotes experimental proliferative vitreoretinopathy.

Proliferative vitreoretinopathy (PVR) is a disease that causes severe blindness and is characterized by the formation of contractile fibrotic subretinal or epiretinal membranes. The epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is a hallmark of PVR. This work aims to examine the role of a long noncoding RNA (lncRNA) named EMT-related lncRNA in RPE (ERLR, LINC01705-201 (ENST00000438158.1)) in PVR and to explore the underlying mechanisms. In this study, we found that ERLR is upregulated in RPE cells stimulated with transforming growth factor (TGF)-ß1 as detected by lncRNA microarray and RT-PCR. Further studies characterized full-length ERLR and confirmed that it is mainly expressed in the cytoplasm. In vitro, silencing ERLR in RPE cells attenuated TGF-ß1-induced EMT, whereas overexpressing ERLR directly triggered EMT in RPE cells. In vivo, inhibiting ERLR in RPE cells reduced the ability of cells to induce experimental PVR. Mechanistically, chromatin immunoprecipitation (ChIP) assays indicated that the transcription factor TCF4 directly binds to the promoter region of ERLR and promotes its transcription. ERLR mediates EMT by directly binding to MYH9 protein and increasing its stability. TCF4 and MYH9 also mediate TGF-ß1-induced EMT in RPE cells. Furthermore, ERLR is also significantly increased in RPE cells incubated with vitreous PVR samples. In clinical samples of PVR membranes, ERLR was detected through fluorescent in situ hybridization (FISH) and colocalized with the RPE marker pancytokeratin (pan-CK). These results indicated that lncRNA ERLR is involved in TGF-ß1-induced EMT of human RPE cells and that it is involved in PVR. This finding provides new insights into the mechanism and treatment of PVR.