title: Muller cell expression of genes implicated in proliferative vitreoretinopathy is influenced by substrate elastic modulus.
abstract: OBJECTIVE
  Matrix stiffness is recognized increasingly as a significant factor in cell and tissue function. To understand better the mechanosensitivity of Müller cells and its association with vitreoretinal disorders, we examined morphology, propagation, and expression of genes in Müller cells that were cultured on substrates of varying elastic moduli.
  
  
  METHODS
  A conditionally immortalized mouse Müller cell line was cultured on laminin-coated polyacrylamide substrates with calibrated Young's moduli. Glass was used as a control. Phase contrast, fluorescence, and atomic force microscopy were used to study cell morphology and propagation. Expression of extracellular matrix (ECM) genes was analyzed using quantitative reverse-transcription PCR.
  
  
  RESULTS
  The adherent area, stiffness, and propagation of Müller cells all are affected by matrix stiffness, but to different extents and with different ranges of sensitivity. Of 85 ECM genes tested 11 showed a continuous >4-fold increase or decrease in mRNA expression as a function of the substrate elastic modulus. The changes were statistically significant in four genes: connective tissue growth factor (Ctgf, P = 0.04), tenascin C (Tnc, P = 0.035), Collagen Iα1 (Col1a1, P = 0.0001), and Collagen IVα3 (Col4a3, P = 0.05), with all showing increased expression on softer substrates.
  
  
  CONCLUSIONS
  There are significant changes in morphology, cytoskeletal integrity, and gene regulation in Müller cells as a function of the stiffness of the substrate. Changes in local tissue elastic modulus may have a role in vitreoretinal disorders. These findings also may have implications for strategies for improved integration of retinal prosthetics, and for stem cell therapies, particularly targeting the transcriptional regulators YAP and TAZ.
authors.affiliation: Department of Physics, The University of Houston, Houston, Texas, USA.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Davis
authors.forename: Qi
authors.initials: Q
authors.lastname: Wen
authors.forename: Paul A
authors.initials: PA
authors.lastname: Janmey
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Otteson
authors.forename: William J
authors.initials: WJ
authors.lastname: Foster
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024141:Collagen Type IV / Q000235:genetics / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism; D055119:Elastic Modulus / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D015870:Gene Expression / Q000235:genetics; D007797:Laminin / Q000737:chemistry; D051379:Mice; D008853:Microscopy; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019063:Tenascin / Q000235:genetics / Q000378:metabolism; D018630:Vitreoretinopathy, Proliferative / Q000473:pathology*; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001324:Autoantigens; D024042:Collagen Type I; D024141:Collagen Type IV; D055513:Connective Tissue Growth Factor; D007797:Laminin; D012333:RNA, Messenger; D019063:Tenascin; D000099166:Polyacrylamides; C057112:type IV collagen alpha3 chain