HPV16-E6 Oncoprotein Activates TGF-β and Wnt/β-Catenin Pathways in the Epithelium-Mesenchymal Transition of Cataracts in a Transgenic Mouse Model.

Genaro Rodríguez-Uribe,José Bonilla-Delgado,Paul F Lambert,Carlos Ugarte-Briones,Anne E Griep,José Moreno,Gabriela Damian-Morales,Cynthia R Trejo-Muñoz,Odette Verdejo-Torres,Patricio Gariglio,Enoc Mariano Cortés-Malagón,Vicky García-Hernández,Teresa Mancilla Percino ,Jessica Campos-Blázquez ,Nicolás Serafín-Higuera ,Rubén G Contreras ,Elizabeth Álvarez-Ríos ,Carmen Palacios‐Reyes ,Jaime Escobar‐Herrera ,Rodolfo Ocadiz‐Delgado

doi:10.1155/2018/2847873

Abstract

Objective This work aimed to determine if cataractous changes associated with EMT occurring in the K14E6 mice lenses are associated with TGF-β and Wnt/β-catenin signaling activation. Materials and Methods Cataracts of K14E6 mice were analysed histologically; and components of TGF-β and Wnt/β-catenin signaling were evaluated by Western blot, RT-qPCR, in situ RT-PCR, IHC, or IF technics. Metalloproteinases involved in EMT were also assayed using zymography. The endogenous stabilisation of Smad7 protein was also assessed using an HDAC inhibitor. Results The K14E6 mice, which displayed binocular cataracts in 100% of the animals, exhibited loss of tissue organisation, cortical liquefaction, and an increase in the number of hyperproliferative-nucleated cells with mesenchymal-like characteristics in the lenses. Changes in lenses' cell morphology were due to actin filaments reorganisation, activation of TGF-β and Wnt/β-catenin pathways, and the accumulation of MTA1 protein. Finally, the stabilisation of Smad7 protein diminishes cell proliferation, as well as MTA1 protein levels. Conclusion The HPV16-E6 oncoprotein induces EMT in transgenic mice cataracts. The molecular mechanism may involve TGF-β and Wnt/β-catenin pathways, suggesting that the K14E6 transgenic mouse could be a useful model for the study or treatment of EMT-induced cataracts.

Highlights

The term cataract refers to the opacification of the crystalline lens, and it is the most common cause of visual loss in humans [1]
The K14HPV16E6 transgenic (K14E6) mouse contains the HPV16-E6 oncogene flanked by the human cytokeratin 14 (K14) promoter, the keratin 14 promoter (K14) polyadenylation sequences (K14 polyA), and a translational termination linker (TTL) inserted into the 3󸀠 region of the E7 oncogene, so that translation of E7 is disrupted (Figure 1(b))
Since downregulation of E-cadherin and upregulation of Vimentin are considered as a hallmark of epithelial-mesenchymal” transition (EMT) [29, 30], we studied the expression of these proteins in the lens of 2-month-old NT and K14E6 transgenic mice

Summary

Introduction

The term cataract refers to the opacification of the crystalline lens, and it is the most common cause of visual loss in humans [1]. Surgery is the most effective treatment to remove cataracts, a common postoperative complication consists in the development of a secondary cataract, known as posterior capsule opacification (PCO), caused by a fibrotic growth of residual lens epithelial cells left behind in the capsular bag after surgery [2]. Lens epithelial explants cultured in the presence of TGF-β1 developed cataractous changes characterised by an accumulation of fibrous/collagenous extracellular matrix (ECM), along with changes in the lens’ cell morphology, which resembles a “mesenchymal-like” phenotype, a process known as “epithelial-mesenchymal” transition (EMT) [5]. During cataract formation, lens epithelium-derived myofibroblasts become capable of expressing components of the fibrous ECM, as well as matrixdegrading enzymes [3]

Methods

Results

Conclusion