Transforming growth factor-β2-mediated mesenchymal transition in lens epithelial cells is repressed in the absence of RAGE

Abstract

Transforming growth factor-β2 (TGFβ2)-mediated epithelial to mesenchymal transition (EMT) in lens epithelial cells (LECs) has been implicated in fibrosis associated with secondary cataracts. In this study, we investigated whether the receptor for advanced glycation end products (RAGE) plays a role in TGFβ2-mediated EMT in LECs. Unlike in the LECs from wild-type mice, TGFβ2 failed to elicit an EMT response in LECs from RAGE knockout mice. The lack of RAGE also diminished TGFβ2-mediated Smad signaling. In addition, treatment with TGFβ2 increased IL-6 levels in LECs from wild-type mice but not in those from RAGE knockout mice. Treatment of human LECs with the RAGE inhibitor FPS-ZM1 reduced TGFβ2-mediated Smad signaling and the EMT response. Unlike that in wild-type lenses, the removal of fiber cell tissue in RAGE knockout lenses did not result in elevated levels of α-smooth muscle actin (α-SMA), fibronectin (FN), and integrin β1 in capsule-adherent LECs. Taken together, these results suggest that TGFβ2 signaling is intricately linked to RAGE. Targeting RAGE could be explored as a therapeutic strategy against secondary cataracts.

Lens Fibrosis: Understanding the Dynamics of Cell Adhesion Signaling in Lens Epithelial-Mesenchymal Transition

“…For example, overexpression of RAGE in the human FHL124 cell line enhanced the TGFβ2-mediated EMT response in cells when cultured on AGE-modified basement membrane ( Raghavan and Nagaraj, 2016 ). A more recent study employing RAGE knockout (KO) mice showed that LECs isolated from RAGE KO lenses did not undergo EMT in response to TGFβ2 as the wild-type cells did and this was likely due to the reduced Smad signaling observed ( Nam et al, 2021 ). Further lensectomy experiments performed on RAGE KO mice showed that unlike wild-type littermates that exhibited elevated levels of αSMA, FN and b1 integrin in remaining capsular bag post-surgery, the RAGE KO capsules did not ( Nam et al, 2021 ).…”

“…A more recent study employing RAGE knockout (KO) mice showed that LECs isolated from RAGE KO lenses did not undergo EMT in response to TGFβ2 as the wild-type cells did and this was likely due to the reduced Smad signaling observed ( Nam et al, 2021 ). Further lensectomy experiments performed on RAGE KO mice showed that unlike wild-type littermates that exhibited elevated levels of αSMA, FN and b1 integrin in remaining capsular bag post-surgery, the RAGE KO capsules did not ( Nam et al, 2021 ). Overall, these findings suggest that the interaction of lens matrix AGEs with RAGE plays an important role in the TGFβ2-mediated EMT of lens and fibrosis.…”

Long Non-Coding RNA H19 Prevents Lens Fibrosis through Maintaining Lens Epithelial Cell Phenotypes

“…Many studies have been conducted to explore the potential therapeutic options for preventing or reversing lens fibrosis using diverse experimental models. To better validate their roles in lens transparency maintenance, in recent years, apart from in vitro studies using lens epithelial cell lines, semi-in vivo epithelial explants, the whole lens culturing, and in vivo animal models have been more widely used, including injury-induced ASC models, mock lens cataract surgery (Extracapsular Lens Extraction, ECLE) for PCO models, and transgenic/genetic knockout mice [ 19 , 52 , 53 , 54 , 55 , 56 , 57 ]. It is generally accepted that during TGF-β2-induced EMT, loss of LEC integrity is accompanied by the abnormal secretion of ECM and aberrant cell migration, resulting in fibrotic plaques and lens opacification.…”

AAV2-Mediated Expression of HspB1 in RGCs Prevents Somal Damage and Axonal Transport Deficits in a Mouse Model of Ocular Hypertension

“…Western blotting was performed as previously described. 46 The sHsp-specific primary antibodies (1:1,000 dilution) were incubated overnight at 4°C. Anti-rabbit IgG (1:5,000 dilution, Cat no.…”