%0 Journal Article
%T Substrate Stiffness Influences the Time Dependence of CTGF Protein Expression in M¨¹ller Cells - Substrate Stiffness Influences the Time Dependence of CTGF Protein Expression in M¨¹ller Cells - Open Access Pub
%A Joshua T Davis
%A William J Foster
%J OAP | Home | International Physiology Journal | Open Access Pub
%D 2018
%X Following ocular trauma and retinal detachment, gliotic changes in the retina may develop over the subsequent month, a process known as PVR (proliferative vitreoretinopathy). There have been no successful therapeutic interventions to inhibit PVR. The protein CTGF (Connective Tissue Growth Factor) has been associated with retinal PVR and other fibrotic diseases of the retina in clinical studies but the mechanistic link between different pathologies and retinal gliosis has not been determined. In addition, CTGF has been previously noted to be associated, in some cases, with YAP/TAZ (Yes-associated protein and Tafazzin protein complex), transcriptional regulatory proteins that change subcellular localization in response to mechanical cues, such as the stiffness of the underlying material. We have previously shown that the mRNA for CTGF is markedly (100-fold) upregulated in retinal M¨¹ller cells grown on soft substrates. In order to evaluate if the mechanism by which mechanotransduction modulating CTGF production in retinal M¨¹ller cells involves the YAP/TAZ complex, this study tests the influence of substrate stiffness on the time dependence of CTGF protein expression, as well as subcellular localization of YAP/TAZ using a conditionally-immortalized mouse retinal M¨¹ller cell line plated on laminin-coated, polyacrylamide substrates of varying elastic modulus. Changes were assayed using immunohistochemistry and ELISA (Enzyme-Linked ImmunoSorbent Assay). In retinal M¨¹ller cells, the relationship between elastic modulus and the pattern of CTGF protein expression was bimodal, with CTGF levels rising more rapidly for cells on hard substrates and more slowly for cells grown on soft substrates. In addition, nuclear localization of YAP/TAZ corresponded directly to the maximum CTGF expression. DOI 10.14302/issn.2578-8590.ipj-17-1910 Extracellular matrix stiffness plays a critical role in influencing the morphology, gene expression, and differentiation of a wide variety of cell types1, 2, 3, 4, 5, 6. The elastic modulus of the cells in adult mammalian retina varies between 200 Pa and 1000 Pa, and many pathologic processes of the retina lead to local changes in stiffness of retinal tissue7. For example, Bruch¡¯s membrane increases in stiffness by an order of magnitude with age8. Retinal detachments and laser photocoagulation can also strongly affect the stiffness of the retina16. At the molecular level, Connective Tissue Growth Factor (CTGF) expression is directly regulated by Yes-associated protein and Tafazzin protein (YAP/TAZ) complexes9, 10. Previously, substrate
%U https://www.openaccesspub.org/ipj/article/675