Connective tissue growth factor promotes retinal pigment epithelium mesenchymal transition via the PI3K/AKT signaling pathway

Abstract

Proliferative vitreoretinopathy (PVR) is a disease leading to the formation of contractile preretinal membranes (PRMs) and is one of the leading causes of blindness. Connective tissue growth factor (CTGF) has been identified as a possible key determinant of progressive tissue fibrosis and excessive scarring. Therefore, the present study investigated the role and mechanism of action of CTGF in PVR. Immunohistochemical staining was performed to detect the expression of CTGF, fibronectin and collagen type III in PRMs from patients with PVR. The effects and mechanisms of recombinant human CTGF and its upstream regulator, TGF-β1, on epithelial-mesenchymal transition (EMT) and the synthesis of extracellular matrix (ECM) by retinal pigment epithelium (RPE) cells were investigated using reverse transcription-quantitative PCR, western blotting and a [ 3 H]proline incorporation assay. The data indicated that CTGF, fibronectin and collagen type III were highly expressed in PRMs. In vitro, CTGF significantly decreased the expression of the epithelial markers ZO-1 and E-cadherin and increased that of the mesenchymal markers fibronectin, N-cadherin and α-smooth muscle actin in a concentration-dependent manner. Furthermore, the expression of the ECM protein collagen type III was upregulated by CTGF. However, the trends in expression for the above-mentioned markers were reversed after knocking down CTGF. The incorporation of [ 3 H]proline into RPE cells was also increased by CTGF. In addition, 8-Bromoadenosine cAMP inhibited CTGF-stimulated collagen synthesis and transient transfection of RPE cells with a CTGF antisense oligonucleotide inhibited TGF-β1-induced collagen synthesis. The phosphorylation of PI3K and AKT in RPE cells was promoted by CTGF and TGF-β1 and the latter promoted the expression of CTGF. The results of the present study indicated that CTGF may promote EMT and ECM synthesis in PVR via the PI3K/AKT signaling pathway and suggested that targeting CTGF signaling may have a therapeutic or preventative effect on PVR.

Epithelial–mesenchymal transition‐related serum markers ET‐1, IL‐8 and TGF‐β2 are elevated in a Finnish wet age‐related macular degeneration cohort

“…2020; Wang et al. 2021). In a recent article of ours, we showed an AMD‐resembling mouse model exhibiting typical EMT‐style morphological changes in the RPE, as well as alterations in the cellular levels of EMT‐related transcription factors and cellular‐level markers such as Snail, vimentin and OB‐cadherin (Blasiak et al.…”

“…The possibility of EMT occurring in the RPE during the advanced stages of AMD is well established, and it has also been observed in AMD-simulating cell and animal models (Ishikawa et al 2016;Chen et al 2020;Shu et al 2020;Zhou et al 2020;Wang et al 2021). In a recent article of ours, we showed an AMDresembling mouse model exhibiting typical EMT-style morphological changes in the RPE, as well as alterations in the cellular levels of EMTrelated transcription factors and cellular-level markers such as Snail, vimentin and OB-cadherin (Blasiak et al 2021).…”

Lysyl oxidase-like 1-antisense 1 (LOXL1-AS1) lncRNA differentially regulates gene and protein expression, signaling and morphology of human ocular cells

“…These hub proteins included pAKT/AKT, pMAPK/MAPK, pFAK/FAK, YAP, TAZ, VLK, talin-1, vinculin and rhoA. For example, phosphorylation of AKT is associated with a decrease in TM cell size ( 46 ) and an increase in phosphorylation of eNOS in SC cells ( 47 ), as well as signaling in processes such as proliferation, cell cycle and EMT responses ( 34 , 48 ). Activation of MAPK by phosphorylation regulates processes including proliferation, differentiation, motility and survival ( 49 ).…”

Understanding Drivers of Ocular Fibrosis: Current and Future Therapeutic Perspectives

“…CTGF was found to be overexpressed in the filtration blebs after trabeculectomy [ 36 ]. Moreover, CTGF activity was associated with the process of EMT and ECM synthesis by human RPE cell line ARPE19 in vitro [ 37 ]. A possible cross-talk is also proposed between the nerve growth factor (NGF) and TGFβ.…”